Cyclonic separation apparatus for a vacuum cleaner

CROSS-REFERENCE TO RELATED APPLICATIONS

0001This application claims priority to European Patent Application No. 11 184 822.2 filed Oct. 12, 2011. The entire contents of that application are expressly incorporated herein by reference.

FIELD OF THE INVENTION

0002The present invention relates to a cyclonic separation apparatus. In particular, but not exclusively, the present invention relates to a cyclonic separation apparatus for use in vacuum cleaners.

BACKGROUND OF THE INVENTION

0003Vacuum cleaners are well known for collecting dust and dirt, although wet-and-dry variants which can also collect liquids are known as well. Typically, vacuum cleaners are intended for use in a domestic environment, although they also find uses in other environments, such as worksites or in the garden. Generally, they are electrically powered and therefore comprise an electric motor and a fan connected to an output shaft of the motor, an inlet for dirty air, an outlet for clean air and a collection chamber for dust, dirt and possibly also liquids. Electrical power for the motor may be provided by a source of mains electricity, in which case the vacuum cleaner will further comprise an electrical power cable, by a removable and replaceable battery pack, or by one or more in-built rechargeable cells, in which case the vacuum cleaner will further comprise some means, such as a jack plug or electrical contacts, for connecting the vacuum cleaner to a recharging unit. When the vacuum cleaner is provided with electrical power from one of these sources, the electric motor drives the fan to draw dirty air along an air flow pathway in through the dirty air inlet, via the collection chamber to the clean air outlet. The fan is often a centrifugal fan, although it can be an impeller or a propeller

0004Interposed at some point along the air flow pathway, there is also provided some means for separating out dust and dirt (and possibly also liquids) entrained with the dirty air and depositing these in the collection chamber. This dirt separation means may comprise a bag filter, one or more filters and/or a cyclonic separation apparatus.

0005In the event that the dirt separation means comprises a bag filter, dirty air, which has entered the vacuum cleaner via the dirty air inlet, passes through the bag filter. This filters out, and collects within the bag filter, dust and dirt entrained with the dirty air. The filtered material remains in the bag filter which lines the collection chamber. The clean air then passes to the other side of bag filter and through a grille in the collection chamber under the influence of the fan. The fan draws air in and expels it out, from where the air then passes to the clean air outlet of the vacuum cleaner.

0006There is always a small risk of dust and dirt passing through the bag filter and it is undesirable that it be allowed to pass through the fan and cause damage. To reduce this potential problem, there is often a fine filter located across the grille of the collection chamber to remove any fine dust and dirt particles remaining in the air flow after passage through the bag filter. This is commonly known as a pre-fan filter.

0007Occasionally, and in addition to any pre-fan filter, there is a high efficiency filter located downstream of the fan before the air flow leaves the vacuum cleaner. This is to remove any remaining extremely fine particulate matter which will not harm the fan or motor, but which may be harmful to the household environment. The term “filtering efficiency” is intended to relate to the relative size of particulate matter removed by a filter. For example, a high efficiency filter is able to remove smaller particulate matter from air flow than a low efficiency filter. A HEPA filter is a high efficiency filter which should be able to remove extremely fine particulate matter having a diameter of 0.3 micrometers (μm) and lower.

0008The purpose of the bag filter is to filter dust and dirt entrained in dirty air flow and to collect the filtered material within the bag filter. This progressively clogs the bag filter. The volumetric flow rate of air through the vacuum cleaner is progressively reduced and its ability to pick up dust and dirt diminishes correspondingly. Hence, the bag filter needs replacement before it becomes too full and before vacuum cleaner performance becomes unacceptable. The volume of the collection chamber must be sufficiently large to merit the cost of regular bag filter replacement.

0009An upright vacuum cleaner commonly has an upright main body with a dirt separating means, a motor and fan unit, a handle at the top and a pair of support wheels at the bottom. A cleaner head with a dirty air inlet facing the floor is pivotally mounted to the main body. A cylinder vacuum cleaner commonly has a cylindrical main body with a separating dirt means, a motor and fan unit and maneuverable support wheels underneath. A flexible hose with a cleaner head communicates with the main body. Bag filters are commonly used in upright and cylinder vacuum cleaners as separation means because their main body has sufficient internal space for the large collection chamber required to accommodate the bag filter.

0010In the event that the dirt separation means comprises a filter, dirty air, which has entered the vacuum cleaner via the dirty air inlet, passes through the filter. This filters out dust and dirt entrained with the dirty air and the filtered material remains in the collection chamber on the upstream side of the filter. Sometimes the filter is supplemented by a sponge to absorb any liquids entrained in the dirty air flow. The clean air then passes to the other side of filter under the influence of the fan, and from the fan the air then passes to the clean air outlet of the vacuum cleaner.

0011Filtered material accumulates around, and progressively clogs, the filter. The volumetric flow rate of air through the vacuum cleaner is progressively reduced and its ability to pick up dust and dirt diminishes correspondingly. Hence, the collection chamber needs regular emptying and the filter needs frequent cleaning to mitigate against this effect. Sometimes, the vacuum cleaner has a filter cleaning mechanism. Alternatively, the filter needs to be removable for cleaning with a brush, or in a dish washer, for example.

0012Hand-holdable vacuum cleaners, as their name would suggest, are compact and lightweight and are intended to perform light, or quick, cleaning duties around a household. Typically, hand-holdable vacuum cleaners are battery-powered to be easily portable.

0013An example of a hand-holdable vacuum cleaner having the conventional motor, fan and filter arrangement is described in European patent publication no. EP 1 752 076 A, also in the name of the present applicant. This vacuum cleaner has dirty air inlet at one end of a dirty air duct leading to a collection chamber with a filter. The collection chamber is generally cylindrical and is arranged transverse the body of the vacuum cleaner. The dirty air duct is rotatable, with the collection chamber, in relation to the body. The dirty air duct may be adjusted to access awkward spaces while the vacuum cleaner is held comfortably by a user.

0014In the event that the dirt separation means comprises cyclonic separation apparatus, dirty air, which has entered the vacuum cleaner via the dirty air inlet, passes through the cyclonic separation apparatus having one or more cyclones. A cyclone is a hollow cylindrical chamber, conical chamber, frustro-conical chamber or combination of two or more such types of chamber. The cyclone may have a vortex finder part way, or all way, along its internal length. The vortex finder is commonly a hollow cylinder and it has a smaller external diameter than the internal diameter of the cyclone.

0015Dirty air enters via a tangentially arranged air inlet port and swirls around the cyclone in an outer vortex. Centrifugal forces move the dust and dirt outwards to strike the side of the cyclone unit and separate it from the air flow. The dust and dirt is deposited at the bottom of the cyclone and into a collection chamber below. An inner vortex of cleaned air then rises back up the cyclone. The role of a vortex finder is to gather and direct the cleaned air through an air outlet port at the top of the cyclone. As an alternative to a vortex finder, the cyclone may have an inner cylindrical air permeable wall providing the cleaned air with a path from the cyclone. From the cyclone the cleaned air passes, under the influence of the fan, to the clean air outlet of the vacuum cleaner.

0016As with a bag filter, a vacuum cleaner with a cyclonic separation apparatus may have a pre-fan filter to protect the fan and motor, especially if the air flow is used to cool the motor. Nevertheless, volumetric flow rate of air through the vacuum cleaner remains virtually constant as separated material accumulates in the collection chamber. Thus, an attraction of cyclonic separation apparatus in a vacuum cleaner is a consistent ability to pick up dust and dirt. Another attraction is that the cost of regular bag filter replacement is avoided.

0017An example of an upright vacuum cleaner having a motor, fan and cyclonic separation apparatus is described in European patent publication no. EP 0 042 723 A. This cyclonic separation apparatus is divided into a first cyclonic separating unit with a cyclone formed by an annular chamber and a second cyclonic separating unit with a generally frustro-conical cyclone. The first cyclonic separating unit is ducted in series with the second cyclonic separating unit. Air flows sequentially through the first, and then the second, cyclonic separating units. The frustro-conical cyclone has a smaller diameter than the annular chamber within which the frustro-conical cyclone is partially nested. Separated material from both cyclonic separating units collects in the cylindrical collection chamber formed at the bottom of the annular chamber.

0018The term “separation efficiency” is used in the same way as filtering efficiency and it relates to the relative ability of a cyclonic separation apparatus to remove small particulate matter. For example, a high efficiency cyclonic unit can remove smaller particulate matter from air flow than a low efficiency cyclonic separating unit. Factors that influence separation efficiency can include the size and inclination of the dirty air inlet of a cyclone, size of the clean air outlet of a cyclone, the angle of taper of any frustro-conical portion of a cyclone, and the diameter and the length of a cyclone. Small diameter cyclones commonly have a higher separation efficiency than large diameter cyclones, although other factors listed above can have an equally important influence.

0019The first cyclonic separating unit of EP 0 042 723 A has a lower separating efficiency than the second cyclonic separating unit. The first cyclonic separating unit separates larger dust and dirt from the air flow. This leaves the second cyclonic separating unit to function in its optimum conditions with comparatively clean air flow and separate out smaller dust and dirt.

0020A hand-holdable vacuum cleaner having a motor, fan and cyclonic separation apparatus is described in United Kingdom patent publication no. GB 2 440 110 A. This cyclonic separation apparatus is smaller than that of EP 0 042 723 A in order to be used in a hand-holdable vacuum. It is divided into a first cyclonic separating unit and a second cyclonic separating unit located downstream of the first cyclonic separating unit. The separating efficiency of the first cyclonic separating unit is lower than that of the second cyclonic separating unit.

0021The second cyclonic separating unit of GB 2 440 110 A comprises six cyclones of much smaller diameter than the annular chamber of the first cyclone separating unit. These cyclones are arranged in a circular array protruding a part way into the chamber. There remains a generous amount of space below, and within, this circular array of cyclones which is used to duct air flow from the annular chamber. The cyclones are inclined outwardly from the top of the annular chamber which makes the apparatus relatively tall.

BRIEF SUMMARY OF THE INVENTION

0022It is an object of the present invention to provide a cyclonic separation apparatus which makes improved use of the space it occupies so that it may be more versatile. It is also an object of the present invention to provide a cyclonic separation apparatus particularly suitable for use in a vacuum cleaner. A further object of the invention is to provide a vacuum cleaner comprising such a cyclonic separation apparatus.

0023Accordingly, in a first aspect, the present invention provides a cyclonic separation apparatus for a vacuum cleaner, the cyclonic separation apparatus comprising: a first cyclonic separating unit comprising a hollow substantially cylindrical dirt container with a longitudinal central axis and an air inlet port arranged tangentially to the cylindrical dirt container; and a second cyclonic separating unit comprising a plurality of cyclones arranged in a generally circular array about the central axis, wherein each cyclone has an air inlet port and an air outlet port, wherein the second cyclonic separating unit receives air flow downstream from the first cyclonic separating unit, wherein the second cyclonic separating unit has a higher separation efficiency than the first cyclonic separating unit and wherein the second separating unit is located within the dirt container.

0024The present invention improves use of the space within the cyclonic separation apparatus by locating the circular array of cyclones and the various air ducts between the first and second cyclonic separating units within the dirt container. The resulting apparatus is more compact. It may be used in an up-right position. Advantageously, it is suited for transverse orientation in a vacuum cleaner due to its diminished axial length which may avoid making the vacuum cleaner too wide and cumbersome. Also, the shorter overall air flow path inside the cyclonic separation apparatus reduces energy losses.

0025Preferably, the first cyclonic separation apparatus comprises a substantially cylindrical intermediate wall arranged within the dirt container, wherein the intermediate wall surrounds the air inlet ports of the circular array of cyclones. The intermediate wall shields the air inlet ports from the dirty air flow within the cylindrical dirt container. This helps to avoid re-entrainment of dirt in the air flow destined for the cyclones.

0026Preferably, the intermediate wall comprises an air permeable wall arranged as an air outlet from the first cyclonic separating unit. Partially cleaned air flows in a gentle inner vortex back up and around the intermediate wall before passing through the air permeable wall to the air inlet ports of the cyclones. The air permeable wall provides the benefit of an extra dirt filtration stage and deposits filtered dirt in the dirt container.

0027Preferably, the first and second cyclonic separating units are arranged to deposit material separated from air flow in a longitudinal end of the dirt container. All the separated dirt is contained together and can be emptied together, thus making the cyclonic separation apparatus more user-friendly.

0028Preferably, the cyclonic separation apparatus comprises at least one protruding lip arranged to impede movement of separated material from said longitudinal end of the dirt container. This may help to avoid re-entrainment of separated dirt into the partially cleaned air flow destined for the second cyclonic separating unit.

0029Preferably, the intermediate wall comprises a funnel arranged to collect material separated by the cyclones, wherein the funnel comprises a conical wall tapered towards said longitudinal end of the dirt container to convey material separated by the cyclones to a part of the dirt container isolated from air flow in the first cyclonic separating unit. The tapered funnel helps to deposit small dirt particles in a relatively smaller area of the dirt container than the larger dirt particles which take more space. This may help to prolong the time between emptying the dirt container by balancing the filling rate of the dirt container.

0030Preferably, the dirt container comprises a generally cylindrical exterior wall and a generally circular end wall at said longitudinal end of the dirt container and wherein the end wall is detachably connected to the exterior wall. The detachable end wall facilitates emptying of the dirt container.

0031Preferably, the end wall is hingedly connected to the exterior wall. The end wall may not be mislaid after opening.

0032Preferably, the plurality of cyclones comprises at least five cyclones arranged in the generally circular array having an inner annulus and an outer annulus, wherein the inner annulus diameter is no more than 50 percent of the outer annulus diameter. This may provide enough cyclones of a suitable diameter to perform vacuum cleaning without occupying too much space in the middle of the circular array.

0033Preferably, the outer annulus diameter is at least 25 percent of the dirt container outer diameter. This may provide enough cyclones of a suitable capacity to receive air flow downstream from the first cyclonic separating unit.

0034Preferably, the axial length of the cyclones is at least 25 percent of the axial length of the dirt container. This may provide cyclones with a suitable capacity to receive air flow downstream from the first cyclonic separating unit.

0035In a second aspect, the present invention provides a vacuum cleaner comprising: a motor coupled to a fan for generating air flow; and the cyclonic separation apparatus according to the first aspect, wherein the cyclonic separation apparatus is located in the path of the air flow generated by the fan. The vacuum cleaner may have a more compact design by virtue of compact features of the cyclonic separation apparatus which may also reduce the overall air flow path and reduce energy losses.

0036Preferably, the main body has a main axis and wherein the central axis of the dirt container is arranged transverse to the main axis of the main housing. As such, the vacuum cleaner may have a slimmer, less cumbersome, profile by virtue of the diminished axial length of the cyclonic separation apparatus.

0037Preferably, the vacuum cleaner is a hand-holdable vacuum cleaner. It may be readily portable and convenient to use without need for connection to a mains electrical supply.

0038Preferably, the dirt container is transparent. This enables visual inspection to decide when to empty separated material from the dirt container. Preferably, the cyclones are arranged at equi-angular intervals about the central axis of the cyclonic separation apparatus. The cyclones are arranged evenly thus and occupy less space. Preferably, each cyclone comprises: a hollow cylindrical and/or frustro-conical body with a longitudinal axis; a vortex finder arranged concentrically inside the cyclone body; a discharge nozzle arranged at a longitudinal end of the cyclone body; the air inlet port through a side of the body, wherein the air inlet port is arranged tangentially to the cyclone body; and an air outlet port the through the vortex finder and an opposite end of the cyclone body. Preferably, each cyclone body has a cylindrical portion and a frustro-conical portion depending from the cylindrical portion, wherein the cylindrical portion is proximal the vortex finder and wherein the frustro-conical portion terminates at the nozzle. The vortex of air flowing towards the discharge nozzle accelerates as the body's diameter decreases to separate ever smaller dust particles and to increase separation efficiency. Preferably, the plane of the nozzle is inclined with respect to the longitudinal axis of the cyclone body. This helps to avoid separated material from re-entering the discharge nozzle. Preferably, the longitudinal axis of each cyclone is in line with the central axis of the cyclonic separation apparatus. Preferably, the longitudinal axis of each cyclone is parallel with the central axis of the cyclonic separation apparatus. Preferably, the air outlet port through each vortex finder has one or more longitudinal internal ribs. This helps to reduce noise generated by Helmholtz resonance caused by air flow through the air outlet port. Preferably, the fan is a centrifugal fan having a tangential output. Preferably, the vacuum cleaner comprises a pre-fan filter located in the path of the air flow downstream of the second cyclonic separation apparatus and upstream from the fan. Preferably, the vacuum cleaner comprises an outlet duct for ducting the path of air flow between the first cyclonic separation apparatus and the fan. Preferably, the outlet duct has a transparent and/or detachable duct wall. Any blockages may be seen by the user. The user may have access to the pre fan filter in the event it is seen to need renewal. Preferably, the vacuum cleaner comprises a plurality of rechargeable cells for powering the motor, wherein the motor has a drive shaft with a longitudinal central axis and wherein the cells are arranged in a circular array about the motor with a longitudinal central axis of each cell arranged substantially parallel to the central axis of the drive shaft. Preferably, the vacuum cleaner comprises a main body housing the fan, the motor and the rechargeable cells, wherein the main body ducts air flow from the fan past the motor and cells. The clean air may cool the motor and the cells. Preferably, the vacuum cleaner comprises a flexible hose located in the path of the air flow upstream of the cyclonic separation apparatus. Preferably, the vacuum cleaner comprises an elongate body with a handle at one end and a cleaner head at the other end, wherein the cleaner head is located in the path of the air flow upstream of the cyclonic separation apparatus. Preferably, the vacuum cleaner comprises at least one support wheel support wheel for supporting the vacuum cleaner upon a floor, and wherein the at least one support wheel rotates about the longitudinal central axis of the dirt container. The cyclonic separation apparatus is located close to the floor so that the duct from the cleaner head is shortened. This reduces energy loss by reducing the overall air flow path. Preferably, the at least one support wheel defines a cylinder surrounding the dirt container. The cyclonic separation apparatus performs an additional role of axle to the support wheel which makes the vacuum cleaner more compact. Preferably, the elongate body is telescopically extendible so that it can be extended for operation and retracted for storage in a smaller location. Preferably, the vacuum cleaner is a blower-vac. This is an outdoor garden tool which can perform the role of blowing garden debris for collection and the role of vacuum cleaner for sucking garden debris into a container.

BRIEF DESCRIPTION OF THE DRAWINGS

0039Further features and advantages of the present invention will be better understood by reference to the following description, which is given by way of example and in association with the accompanying drawings, in which:

0040<figref idref="DRAWINGS">FIG. 1</figref> shows perspective view of a first embodiment of a hand-held vacuum cleaner with a motor, fan and cyclonic separation apparatus arrangement;

0041<figref idref="DRAWINGS">FIG. 2</figref> shows a longitudinal cross-section of the motor, fan and cyclonic separation apparatus arrangement of <figref idref="DRAWINGS">FIG. 1</figref>;

0042<figref idref="DRAWINGS">FIG. 3</figref> shows a perspective view of the longitudinal cross-section of <figref idref="DRAWINGS">FIG. 2</figref>;

0043<figref idref="DRAWINGS">FIG. 4</figref> shows an exploded perspective view of the motor, fan and cyclonic separation apparatus arrangement of <figref idref="DRAWINGS">FIG. 1</figref>;

0044<figref idref="DRAWINGS">FIG. 5</figref> shows an exploded perspective view of internal components of the cyclonic separation apparatus of <figref idref="DRAWINGS">FIG. 1</figref>;

0045<figref idref="DRAWINGS">FIG. 6</figref> shows a partially exploded perspective view of the motor, fan and cyclonic separation apparatus arrangement of <figref idref="DRAWINGS">FIG. 1</figref>;

0046<figref idref="DRAWINGS">FIG. 7</figref> shows a perspective view of an end cap of the cyclonic separation apparatus arrangement of <figref idref="DRAWINGS">FIG. 1</figref>;

0047<figref idref="DRAWINGS">FIG. 8</figref> shows a perspective view of a vortex finder assembly of the cyclonic separation apparatus of <figref idref="DRAWINGS">FIG. 1</figref>;

0048<figref idref="DRAWINGS">FIGS. 9A to 9H</figref> show the longitudinal cross-section of <figref idref="DRAWINGS">FIG. 2</figref> including the air flow pathways through the motor, fan, cyclonic separation apparatus and a motor cooling passage, in use;

0049<figref idref="DRAWINGS">FIG. 10</figref> shows a perspective view of a second embodiment of a hand-held vacuum cleaner with a motor, fan and cyclonic separation apparatus arrangement;

0050<figref idref="DRAWINGS">FIG. 11</figref> shows the perspective view of <figref idref="DRAWINGS">FIG. 10</figref> with a portion of the body removed;

0051<figref idref="DRAWINGS">FIG. 12</figref> shows a longitudinal cross-section of the cyclonic separation apparatus of <figref idref="DRAWINGS">FIG. 10</figref>;

0052<figref idref="DRAWINGS">FIG. 13</figref> shows a perspective view of the cross-section of <figref idref="DRAWINGS">FIG. 12</figref>;

0053<figref idref="DRAWINGS">FIG. 14</figref> shows a longitudinal cross-section of the motor, fan and cyclonic separation apparatus arrangement of <figref idref="DRAWINGS">FIG. 10</figref>;

0054<figref idref="DRAWINGS">FIG. 15</figref> shows an exploded perspective view of the motor, fan and cyclonic separation apparatus arrangement of <figref idref="DRAWINGS">FIG. 10</figref>;

0055<figref idref="DRAWINGS">FIG. 16</figref> shows an exploded perspective view of internal components of the cyclonic separation apparatus of <figref idref="DRAWINGS">FIG. 10</figref>;

0056<figref idref="DRAWINGS">FIG. 17A to 17F</figref> shows the longitudinal cross-section of <figref idref="DRAWINGS">FIG. 12</figref> including the air flow through the cyclonic separation apparatus arrangement, in use;

0057<figref idref="DRAWINGS">FIGS. 18 to 22</figref> show diagrammatical representations of various constructions of the cyclonic separation apparatus of <figref idref="DRAWINGS">FIG. 10</figref>;

0058<figref idref="DRAWINGS">FIG. 23</figref> shows a perspective view of a third embodiment of a hand-held vacuum cleaner with a motor, fan and cyclonic separation apparatus arrangement;

0059<figref idref="DRAWINGS">FIG. 24</figref> shows a perspective view of the vacuum cleaner of <figref idref="DRAWINGS">FIG. 23</figref> without a dirt container wall;

0060<figref idref="DRAWINGS">FIG. 25</figref> shows a perspective view of a vortex finder;

0061<figref idref="DRAWINGS">FIG. 26</figref> shows a perspective view of the vacuum cleaner of <figref idref="DRAWINGS">FIG. 23</figref> with a transparent dirt container wall;

0062<figref idref="DRAWINGS">FIG. 27</figref> shows a diagrammatical cross-section XXVI-XXVI of the vacuum cleaner of <figref idref="DRAWINGS">FIG. 23</figref> including air flow pathways;

0063<figref idref="DRAWINGS">FIG. 28</figref> shows a diagrammatical cross-section XXVII-XXVII of the vacuum cleaner of <figref idref="DRAWINGS">FIG. 23</figref> including air flow pathways;

0064<figref idref="DRAWINGS">FIG. 29</figref> shows side elevation view of a battery-powered vacuum cleaner with an extendible dirty air duct and the motor, fan and cyclonic separation apparatus arrangement of <figref idref="DRAWINGS">FIGS. 2 to 9</figref>;

0065<figref idref="DRAWINGS">FIG. 30</figref> shows a perspective view of the vacuum cleaner of <figref idref="DRAWINGS">FIG. 29</figref>;

0066<figref idref="DRAWINGS">FIG. 31</figref> shows a cross-sectional view, of a portion of the vacuum cleaner of <figref idref="DRAWINGS">FIG. 29</figref> showing a battery pack;

0067a. <figref idref="DRAWINGS">FIG. 32</figref> shows a perspective view of the vacuum cleaner of <figref idref="DRAWINGS">FIG. 29</figref> with the dirty air duct extended;

0068<figref idref="DRAWINGS">FIG. 33</figref> shows a side elevation view of a battery-powered vacuum cleaner with a flexible hose and the motor, fan and cyclonic separation apparatus arrangement of <figref idref="DRAWINGS">FIGS. 2 to 9</figref>;

0069<figref idref="DRAWINGS">FIG. 34</figref> shows a perspective view of the vacuum cleaner of <figref idref="DRAWINGS">FIG. 33</figref>;

0070<figref idref="DRAWINGS">FIG. 35</figref> shows a perspective view of a battery-powered vacuum cleaner with a telescopic body and a cleaner head with the motor, fan and cyclonic separation apparatus arrangement of <figref idref="DRAWINGS">FIGS. 2 to 9</figref>;

0071<figref idref="DRAWINGS">FIG. 36</figref> shows a close-up perspective view of the vacuum cleaner of <figref idref="DRAWINGS">FIG. 35</figref>;

0072<figref idref="DRAWINGS">FIG. 37</figref> shows a side elevation view of the vacuum cleaner of <figref idref="DRAWINGS">FIG. 35</figref> with the telescopic body retracted;

0073<figref idref="DRAWINGS">FIG. 38</figref> shows a perspective view of a removable battery pack and the cyclonic separation apparatus of <figref idref="DRAWINGS">FIGS. 2 to 9</figref>;

0074<figref idref="DRAWINGS">FIG. 39</figref> shows a transverse cross-section XXXVIII-XXXVIII of the battery pack of <figref idref="DRAWINGS">FIG. 38</figref> with cylindrical rechargeable cells;

0075<figref idref="DRAWINGS">FIG. 40</figref> shows a transverse cross-section XXXVIII-XXXVIII of the battery pack of <figref idref="DRAWINGS">FIG. 38</figref> with flat plate rechargeable cells;

0076<figref idref="DRAWINGS">FIG. 41</figref> shows a transverse cross-section of an annular battery pack with cylindrical rechargeable cells;

0077<figref idref="DRAWINGS">FIGS. 42 and 43</figref> show a transverse cross-section of an annular battery pack with flat plate rechargeable cells; and

0078<figref idref="DRAWINGS">FIG. 44</figref> shows a table of test data relating to the temperature of the motor of <figref idref="DRAWINGS">FIG. 2</figref> in different operational conditions.

DETAILED DESCRIPTION OF THE INVENTION

0079Referring to <figref idref="DRAWINGS">FIG. 1</figref>, there is shown first embodiment of a hand-held vacuum cleaner <b>2</b> comprising a main body <b>4</b>, a handle <b>6</b> connected to the main body, a cyclonic separation apparatus <b>8</b> mounted transverse across the main body, and a dirty air duct <b>10</b> with a dirty air inlet <b>12</b> at one end. The vacuum cleaner comprises a motor coupled to a fan for generating air flow through the vacuum cleaner and rechargeable cells (not shown) to energise the motor when electrically coupled by an on/off switch <b>14</b>.

0080Referring to <figref idref="DRAWINGS">FIGS. 2 to 8</figref>, there is shown an arrangement comprising the motor <b>16</b>, the fan <b>18</b> and the cyclonic separation apparatus <b>8</b>. The motor has a drive shaft <b>20</b> with a central axis <b>21</b>. The fan is a centrifugal fan <b>18</b> with an axial input <b>22</b> facing the motor and a tangential output <b>24</b>. The fan has a diameter of 68 mm. The fan is mounted upon the drive shaft at the top of the motor. In use, the motor drives the fan to generate air flow through the cyclonic separation apparatus, as will be described in more detail below. A small portion of the drive shaft <b>20</b> protrudes from the bottom of the motor <b>16</b>. A second fan, comprising a paddle wheel <b>26</b>, is mounted upon the drive shaft <b>20</b> at the bottom of the motor. The motor and the paddle wheel are clad in a cylindrical outer body of the motor, which is often referred to as a “motor can”. In use, the motor turns the paddle wheel to circulate and augment air flow inside the motor can and about the bottom of the motor.

0081The motor <b>16</b> and the fan <b>18</b> are housed in a motor fan housing <b>27</b> comprising a generally cylindrical body portion <b>28</b> enclosing the motor and a generally circular head portion <b>29</b> enclosing the fan. The head portion <b>29</b> has a larger diameter than the body portion <b>28</b>. The motor fan housing <b>27</b> comprises a perforated end cap <b>30</b> mounted upon the head portion on the opposite side to the body portion. The end cap <b>30</b> protects the fan. The end cap has a circular array of perforations <b>36</b> near where air flow is expelled from the fan. The head portion acts as a baffle to direct air flow from the fan and out the perforations. The body portion has an array of bottom slots <b>32</b> around the bottom of the motor and an array of top slots <b>34</b> about where the drive shaft <b>20</b> protrudes from the top of the motor.

0082The cyclonic separation apparatus <b>8</b> comprises a pre-fan filter <b>40</b>, a vortex finder assembly <b>50</b>, a generally cylindrical inner wall <b>60</b>, a cyclone seal <b>70</b>, a cyclone assembly <b>80</b>, a cylindrical perforated intermediate wall <b>90</b>, a circular bulkhead <b>100</b>, a tapered funnel <b>110</b>, a transparent generally cylindrical dirt container <b>120</b>, and a circular bowl door <b>130</b> all arranged about the central axis <b>21</b> of the motor drive shaft <b>20</b>.

0083The pre-fan filter <b>40</b> is an annular shape surrounding the top air flow slots <b>34</b> of the body portion <b>28</b> of the motor fan housing <b>27</b>. The pre-fan filter is enclosed in an annular shell <b>42</b> except where the pre-fan filter communicates with the vortex finder assembly <b>50</b> and with the top air flow slots <b>34</b> of the body portion <b>28</b>. This permits air flow from the cyclonic separating apparatus, through the pre-fan filter and on to the fan.

0084The vortex finder assembly <b>50</b> comprises planar ring <b>52</b> moulded with twelve hollow cylindrical vortex finders <b>54</b> protruding from one side of the planar ring. Holes <b>56</b> through the vortex finders penetrate the opposite side of the planar ring whereupon the pre-fan filter <b>40</b> is seated. The pre-fan filter <b>40</b> helps to muffle high frequency sounds caused by Helmholtz resonance as air flows through the vortex finder holes <b>56</b>. The vortex finders are arranged in a circular array about the central axis <b>21</b> of the motor drive shaft <b>20</b>. Each vortex finder has its own longitudinal central axis <b>57</b> arranged parallel to the central axis <b>21</b>. The vortex finders may have longitudinal internal ribs (not shown) along the vortex finder holes to further reduce high frequency noise caused by Helmholtz resonance. The longitudinal ribs also tend to straighten air flow in the vortex finder to help reduce energy losses as the air flows into the pre-fan filter <b>40</b>.

0085The inner wall <b>60</b> is a generally cylindrical shape in two portions of different diameter. The inner wall comprises an annular flange <b>62</b> at an open end of the inner wall, a hollow cylindrical cup <b>64</b> at an opposite closed end of the inner wall, a hollow cylindrical wall <b>66</b> and an annular shoulder <b>68</b>. The flange extends radially outwardly from the open end of the cylindrical wall. The cylindrical wall is located between the flange and the cylindrical cup. The cylindrical wall has a larger diameter than the cylindrical cup. The annular shoulder joins the cylindrical wall to the cylindrical cup. The shoulder is perforated with a circular array of twelve holes <b>69</b> spaced at equi-angular intervals about the central axis <b>21</b>. The annular flange <b>62</b> is connected to an annular roof wall <b>121</b> of the dirt container <b>120</b>.

0086The vortex finder assembly <b>50</b> is seated in the cylindrical wall <b>66</b> with the planar ring <b>52</b> facing the shoulder <b>68</b> and the vortex finders <b>54</b> protruding through the shoulder's holes <b>68</b>. The pre-fan filer <b>40</b> is nested within the cylindrical wall <b>66</b>. The bottom of the motor fan housing's body portion <b>28</b> is nested within the cylindrical cup <b>64</b>.

0087The cyclone seal <b>70</b> is perforated with a circular array of twelve holes <b>72</b> spaced at equi-angular intervals about the central axis <b>21</b>. The shoulder <b>68</b> of the inner wall <b>60</b> is seated upon the cyclone seal. The vortex finders <b>54</b> protrude through the seal holes <b>72</b>.

0088The cyclone assembly <b>80</b> comprises a cylindrical collar <b>82</b> and a circular array of twelve cyclones <b>84</b> surrounded by the collar. The cyclones are spaced at equi-angular intervals about the central axis <b>21</b>. Each cyclone has a hollow cylindrical top part <b>85</b> and a hollow frustro-conical bottom part <b>86</b> depending from the cylindrical top part and terminating with a discharge nozzle <b>87</b> at the bottom of the cyclone.

0089The shoulder <b>68</b> of the inner wall <b>60</b> is arranged upon the cyclone assembly <b>80</b> with the cyclone seal <b>70</b> interposed therebetween. The collar <b>82</b> has the same outer diameter as, and abuts with, the cylindrical wall <b>66</b> of the inner wall <b>60</b>. The vortex finders <b>54</b> protrude through the holes <b>72</b> in the cyclone seal and into the cylindrical top part <b>85</b> of a respective cyclone <b>84</b>. The only passage through the top of the cyclone <b>84</b> is via its vortex finder <b>54</b> which acts as an air flow outlet port to the pre-fan filter <b>40</b>. Each vortex finder is concentric with its respective cyclone. The plane of each nozzle <b>87</b> is inclined with respect to the central axis <b>57</b>. This helps to prevent dust and dirt particles from re-entry after discharge from the nozzle.

0090The cylindrical top part <b>85</b> of each cyclone <b>84</b> has an air inlet port <b>88</b> arranged tangentially through the side of the cyclone and proximal the vortex finder <b>54</b>. The twelve air inlet ports are in communication with a distribution chamber <b>170</b> below the collar <b>82</b> around the cyclones <b>84</b>, as is described in more detail below.

0091The intermediate wall <b>90</b> is arranged upon the cyclone assembly <b>80</b>. The intermediate wall <b>90</b> has the same outer diameter as, and abuts with, the cylindrical collar <b>82</b>.

0092The bulkhead <b>100</b> is arranged upon, and has approximately the same outer diameter as, the intermediate wall <b>90</b>. The bulkhead <b>100</b> is perforated by a circular array of twelve holes <b>102</b> spaced at equi-angular intervals about the central axis <b>21</b>. The discharge nozzles <b>87</b> of the cyclones <b>84</b> protrude through respective bulkhead holes <b>102</b>. The bulkhead <b>100</b> has a circumferential lip <b>104</b> inclined radially outwardly from the central axis <b>21</b> towards the bowl door <b>130</b>. The lip <b>104</b> protrudes a small way from the intermediate wall <b>90</b>.

0093The tapered funnel <b>110</b> comprises a hollow circumferential skirt <b>112</b>, a frustro-conical cone <b>114</b> depending from the skirt, and a hollow cylindrical nose <b>116</b> depending from the cone. The skirt is arranged upon, and has approximately the same outer diameter as, the bulkhead. The cone tapers radially inwardly from the bulkhead <b>100</b> towards the bowl door <b>130</b>. A perforated portion <b>118</b> of the skirt protrudes axially rearward from the cone towards the bowl door <b>130</b>.

0094The generally cylindrical dirt container <b>120</b> comprises the annular roof wall <b>121</b> and a hollow cylindrical exterior wall <b>122</b> with a frustro-conical dirt collection bowl <b>124</b> depending from the exterior wall. The dirt container has a dirty air inlet port <b>126</b> arranged tangentially through the exterior wall <b>122</b>. The dirt container <b>120</b> has a circumferential lip <b>128</b> inclined radially inwardly towards the central axis <b>21</b> and towards the bowl door <b>130</b>. The lip <b>128</b> protrudes a small way in from the transition between the exterior wall and the dirt collection bowl. The motor fan housing's head portion <b>29</b> is nested within the centre of the annular roof wall <b>121</b>. The annular roof wall is detachably connected to an outer circumferential edge <b>138</b> of the exterior wall <b>122</b>. The annular roof wall <b>121</b> may be connected to the exterior wall <b>122</b> and the inner wall <b>60</b> by snap-fit, bayonet fit, interlocking detents, interference fit or by a hinge. A resilient seal or seals made of polyethylene, rubber or a similar elastomeric material is provided around the annular roof wall to ensure airtight connection with the exterior wall.

0095The bowl door <b>130</b> is detachably connected to an outer circumferential edge <b>132</b> of the dirt collection bowl <b>124</b>. The bowl door abuts the cylindrical nose <b>116</b> thereby dividing the dirt collection bowl into two separate chambers: a generally circular chamber <b>134</b> inside the tapered funnel <b>110</b> and a generally annular chamber <b>162</b> outside the tapered funnel. The bowl door <b>130</b> may be connected to the dirt collection bowl <b>124</b> by snap-fit, bayonet fit, interlocking detents, interference fit or by a hinge. A resilient seal made of polyethylene, rubber or a similar elastomeric material is provided around bowl door <b>130</b> to ensure airtight connection with the dirt collection bowl.

0096The annular flange <b>62</b> of the inner wall <b>60</b> is in complementary mating relationship with a circular ring <b>123</b> protruding from inside the annular roof wall <b>121</b>.

0097The nose <b>116</b> is in complementary mating relationship with a circular ring <b>140</b> protruding from inside the bowl door <b>130</b>. This ensures that components of the cyclonic separation apparatus <b>8</b> remain concentric with the central axis <b>21</b> when the bowl door is closed.

0098Between the annular roof wall <b>121</b> and the bowl door <b>130</b>, the various components of the cyclonic separation apparatus <b>8</b> (i.e. pre-fan filter <b>40</b>, vortex finder assembly <b>50</b>, inner wall <b>60</b>, cyclone seal <b>70</b>, cyclone assembly <b>80</b>, intermediate wall <b>90</b>, bulkhead <b>100</b>, tapered funnel <b>110</b>) are arranged upon each other by detachable connection, typically a snap-fit, bayonet fit, interlocking detents, or interference fit. The permits disassembly and reassembly, without tools, of the cyclonic separation apparatus <b>8</b> in order to clean, or replace, its individual components. Resilient seals made of polyethylene, rubber or a similar elastomeric material, or other suitable seal material, are provided around connections of the annular flange <b>62</b> and pre-fan filter shell <b>42</b> with the annular roof wall <b>121</b>. The seals are to ensure airtight connection. The internal diameter of the dirt container <b>120</b> and the bowl door <b>130</b> is large enough to permit removal of the components of the cyclonic separation apparatus <b>8</b> (i.e. pre-fan filter <b>40</b>, vortex finder assembly <b>50</b>, inner wall <b>60</b>, cyclone seal <b>70</b>, cyclone assembly <b>80</b>, intermediate wall <b>90</b>, bulkhead <b>100</b>, tapered funnel <b>110</b>) through either end of the dirt container.

0099In use, dirty air flows, under the influence of the fan <b>18</b>, in the dirty air inlet <b>12</b>, up the dirty air duct <b>10</b> and into the cyclonic separation apparatus <b>8</b> where dust and dirt entrained in the air flow is separated therefrom. The dust and dirt is collected within the cyclonic separation apparatus. The air flows out the cyclonic separation apparatus <b>8</b>, through the pre-fan filter <b>40</b>, into the motor fan housing <b>27</b> via the top slots <b>34</b>, though the fan <b>18</b> and out the perforations <b>36</b> in the end cap <b>30</b>.

0100Referring to <figref idref="DRAWINGS">FIG. 9A</figref>, the cyclonic separation apparatus <b>8</b> is divided into a first cyclonic separating unit <b>160</b>, a second cyclonic separating unit <b>150</b> and a distribution chamber <b>170</b>. The first cyclonic separating unit is located in the air flow pathway upstream of the distribution chamber. The distribution chamber is located in the air flow pathway upstream of the second cyclonic separating unit.

0101The first cyclonic separating unit <b>160</b> comprises the cylindrical dirt container <b>120</b>. The second cyclonic separating unit <b>150</b> comprises the circular array of twelve cyclones <b>84</b>. The dirt container is concentric with the central axis <b>21</b> of the motor drive shaft <b>20</b>. The distribution chamber <b>170</b> is bounded by the hollow cylindrical cup <b>64</b> of the inner wall, cyclone assembly <b>80</b>, intermediate wall <b>90</b> and bulkhead <b>100</b>. The second cyclone unit <b>150</b> received air flow from the first cyclone unit <b>160</b> via the distribution chamber <b>170</b>.

0102The exterior wall <b>122</b> of the dirt container <b>120</b> has a diameter of approximately 130 mm. The cyclones <b>84</b> have a much smaller diameter than the dirt container. Helical air flow in the cyclones experiences greater centrifugal forces than in the annular chamber. Thus, the cyclones of the second cyclonic separating unit <b>150</b>, when combined, have higher separation efficiency than the dirt container of the first cyclonic separating unit <b>160</b>.

0103The air flow pathway though the cyclonic separation apparatus <b>8</b> is described in more detail with reference to <figref idref="DRAWINGS">FIGS. 9B to 9E</figref>.

0104Referring to <figref idref="DRAWINGS">FIG. 9B</figref>, dirty air (triple-headed arrows) flows into the first cyclonic separating unit <b>160</b> via the dirty air inlet port <b>126</b>. The tangential arrangement of the dirty air inlet port <b>126</b> causes the dirty air to flow in a helical path around the cylindrical dirt container <b>120</b>. This creates an outer vortex in the dirt container. Centrifugal forces move the comparatively large dust and dirt particles outwards to strike the side of the dirt container and separate them from the air flow. The dust separated and dirt (D) swirls towards the dirt collection bowl <b>124</b> where it is deposited.

0105Referring to <figref idref="DRAWINGS">FIG. 9C</figref>, partially-cleaned air (double-headed arrows) flows back on itself to follow an inner helical path closely about the tapered funnel <b>110</b> and towards the cylindrical intermediate wall <b>90</b>. The partially-cleaned air flows through the perforated portion <b>118</b> of the tapered funnel's skirt <b>112</b> largely unimpeded. The circumferential lip <b>104</b> of the bulkhead <b>100</b> and the lip <b>128</b> of the dirt container <b>120</b> converge at a width restriction X in the first cyclonic separating unit <b>160</b>. The width restriction reduces a radial width between the dirt container and the intermediate wall by at least 15 percent. The width restriction tapers towards the bowl door <b>130</b> so that air, and entrained dirt, can flow more easily towards the bowl door than in the opposite direction. Thus, the circumferential lips <b>104</b>, <b>128</b> and perforated portion <b>118</b> of the tapered funnel's skirt <b>112</b> catch separated dirt in the bowl <b>124</b> before it can be re-entrained in the partially-cleaned air flow. The partially-cleaned air flows through perforations in the intermediate wall, which filters any remaining large dirt particles, and into the distribution chamber <b>170</b>.

0106As can be seen in <figref idref="DRAWINGS">FIG. 5</figref>, the air inlet ports <b>88</b> of the twelve cyclones are moulded into the collar <b>82</b> of the cyclone assembly <b>80</b>. The distribution chamber <b>170</b> is in communication with the air inlet ports <b>88</b> of the twelve cyclones <b>84</b>. Referring to <figref idref="DRAWINGS">FIG. 9D</figref>, the partially-cleaned air flow (double-headed arrows) divides itself, in the distribution chamber, evenly between the twelve air inlet ports <b>88</b> from where it flows into the twelve cyclones <b>84</b> of the second cyclonic separating unit <b>150</b>. The air inlet ports <b>88</b> direct the partially-cleaned air flow in a helical path around the vortex finders <b>54</b>. This creates an outer vortex inside each cyclone <b>84</b>. Centrifugal forces move the dust and dirt outwards to strike the side of the cyclone and separate it from the air flow. The separated dust and dirt swirls towards the discharge nozzle <b>87</b>. The internal diameter of the frustro-conical part <b>86</b> of cyclone diminishes as the air flow approaches the nozzle. This accelerates the outer helical air flow thereby increasing centrifugal forces and separating ever smaller dust and dirt particles. The dust and dirt particles exit the nozzle to be deposited inside the part of the bowl <b>124</b> bounded by the tapered funnel <b>110</b>.

0107Referring to <figref idref="DRAWINGS">FIG. 9E</figref>, cleaned air (single-headed arrows) flows back on itself to follow a narrow inner helical path through the middle of the cyclone <b>84</b>. The cleaned air flows out the internal hole <b>56</b> of the vortex finder <b>54</b>, under the influence of the fan, into the pre-fan filter <b>40</b>. The pre-fan filter <b>40</b> is to remove any fine dust and dirt particles remaining in the air flow after the cyclonic separation apparatus <b>8</b>.

0108The pre-fan filter is in communication with the motor fan housing <b>27</b>. Cleaned air flows, via the top slots <b>34</b> in the motor fan housing, to the axial input <b>22</b> of the fan <b>18</b>, out the tangential output <b>24</b> of the fan and through the perforations <b>36</b> of the end cap <b>30</b> where it is exhausted from the vacuum cleaner <b>2</b>. Dust and dirt separated by the first and second cyclonic separating units and deposited in the dirt collection bowl <b>124</b> which can be emptied by opening the bowl door <b>130</b>.

0109Returning to <figref idref="DRAWINGS">FIG. 7</figref>, there are shown three of a total of four motor cooling inlet ports <b>31</b> in the annular roof wall <b>121</b> of the dirt container <b>120</b>. One other motor cooling inlet port is obscured by the end cap <b>30</b> in <figref idref="DRAWINGS">FIG. 7</figref>.

0110Returning to <figref idref="DRAWINGS">FIG. 8</figref>, there are shown four vortex finder seals <b>58</b>. Each vortex finder seal forms a webbed collar around three consecutive vortex finders <b>54</b>. Four equiangular spaced small gaps <b>59</b> exist between the four vortex finder seals. The vortex finder seals <b>58</b> seal the connection between the vortex finder assembly <b>50</b> and the inner wall <b>60</b> except where the gaps <b>59</b> are located.

0111Referring to <figref idref="DRAWINGS">FIG. 9F</figref>, there is shown the pathway of clean motor cooling air (single-headed arrow) flow through the motor <b>16</b> and fan <b>18</b>. The four motor cooling inlet ports are in communication with a first motor cooling passage <b>61</b><i>a </i>between the shell <b>42</b> of the pre-fan filter <b>40</b> and the cylindrical wall <b>66</b> of the inner wall <b>60</b>.

0112Referring to <figref idref="DRAWINGS">FIG. 9G</figref>, there is shown a longitudinal cross-section of a vortex finder <b>54</b> in the region of Detail X of <figref idref="DRAWINGS">FIG. 9F</figref>. Here, the vortex finder seal <b>58</b> blocks communication between the first motor cooling passage <b>61</b><i>a </i>and a second motor cooling passage <b>61</b><i>b </i>between the motor fan housing <b>27</b> and the cylindrical cup <b>64</b> of the inner wall <b>60</b>.

0113Referring to <figref idref="DRAWINGS">FIG. 9H</figref>, there is shown a longitudinal cross-section between two vortex finders <b>54</b> and two vortex finder seals <b>58</b> in the region of Detail X of <figref idref="DRAWINGS">FIG. 9F</figref>. Here, the gap <b>59</b> between the vortex finder seals <b>58</b> permits communication between the first and second motor cooling passages <b>61</b><i>a, </i><b>61</b><i>b. </i>

0114Returning to <figref idref="DRAWINGS">FIG. 9F</figref>, in use, clean motor cooling air flows under the influence of the fan though the four motor cooling inlet ports <b>31</b> and along the first motor cooling passage <b>61</b><i>a, </i>through the gaps <b>59</b> and along the second motor cooling passage <b>61</b><i>b </i>from where it enters the motor fan housing <b>27</b> via the bottom air flow slots <b>32</b>. The motor comprises motor vents <b>17</b><i>a </i>in the bottom, and motor vents <b>17</b><i>b </i>in the top, of the motor can to ventilate the interior of the motor. The paddle wheel <b>26</b> circulates and augments motor cooling air about the bottom of the motor. Motor cooling air is drawn, under the influence of the fan, into the bottom motor vents <b>17</b><i>a, </i>through the interior of the motor, and passes out of the top motor vents <b>17</b><i>b. </i>The motor is cooled by the motor cooling air flow. The motor cooling air flow pathway joins the cleaned air flow pathway from the cyclonic separation apparatus <b>8</b> around the axial input <b>22</b> of the fan <b>18</b>. The motor cooling air flow is expelled from the tangential output <b>24</b> of the fan and out the perforations <b>36</b> of the end cap <b>30</b>.

0115The motor cooling inlet ports <b>31</b> are spaced at equiangular intervals about the central axis <b>21</b>. The motor cooling inlet ports are axially aligned with the gaps <b>59</b> between the vortex spaces seals <b>58</b> and with the bottom air flow slots <b>32</b> in the motor fan housing <b>27</b>. This axial alignment is to help minimise any resistance encountered by the motor cooling air flow along the motor cooling passages <b>61</b><i>a, </i><b>61</b><i>b. </i>The bottom motor vents <b>17</b><i>a </i>are also aligned with the bottom air flow slots <b>32</b> in the motor fan housing <b>27</b> to help minimise any resistance encountered by the motor cooling air flow.

0116The clean motor cooling air flow pathway is separate from the air flow pathway through the cyclonic separation apparatus <b>8</b> up to the axial input of the fan <b>18</b>. This has particular benefits in vacuum cleaning. Typically, motor speed increases as the fan encounters resistance to volumetric air flow and the pressure across the fan increases accordingly. An example of how this may occur is when the vacuum cleaner is operational and the dirty air inlet contacts carpet, hard floor, curtains or other surface to restrict air flow. Should the air flow path through the cyclonic separation apparatus <b>8</b> become blocked, or impeded, for whatever reason, the motor cooling air flow path would not necessarily be blocked, or impeded. Instead, the increased pressure across the fan <b>18</b> would increase suction through the motor cooling air flow pathway. This has the benefit of increased motor cooling when the motor is working hardest and cooling is needed most.

0117Referring to <figref idref="DRAWINGS">FIG. 44</figref>, there is shown a table of test data relating to the temperature of the motor <b>16</b>. Two thermocouples were attached to the motor can while the motor was driving the fan <b>18</b> to generate air flow. The cyclonic separation apparatus <b>8</b> was subjected to three separate tests involving different operational conditions: (a) free air flow (dirty air inlet <b>12</b> fully open); (b) maximum power output (air watts) of cyclonic separation apparatus; and (c) sealed suction (dirty air inlet <b>12</b> closed). As the skilled person will appreciate, air watt is a measurement of vacuum power calculated from volumetric flow rate (volume/time) multiplied by suction (force/area) multiplied by a correction factor depending on humidity and atmospheric pressure. The ambient temperature was measured and compared to the motor temperature after ten minutes run time. The same three tests were carried out with four motor cooling inlet ports <b>31</b> and then repeated with one of the four motor cooling inlet ports <b>31</b> closed. The test data clearly reveal the benefits of the motor cooling air flow pathway and the importance of having four motor cooling inlet ports <b>31</b>.

0118Referring to <figref idref="DRAWINGS">FIGS. 10 and 11</figref>, there is shown a second embodiment of a hand-held vacuum cleaner <b>202</b> comprising a main body <b>204</b> with a main axis <b>205</b>, a handle <b>206</b>, a cyclonic separation apparatus <b>208</b> mounted transverse to the main axis of the main body, and a dirty air duct <b>210</b> with a dirty air inlet <b>212</b> at one end. The vacuum cleaner comprises a motor <b>216</b> coupled to a fan for generating air flow through the vacuum cleaner and rechargeable cells <b>217</b> to energise the motor when electrically coupled by an on/off switch <b>214</b>.

0119Referring to <figref idref="DRAWINGS">FIGS. 12 to 16</figref>, there is shown an arrangement comprising the motor <b>216</b>, the rechargeable cells <b>217</b>, the fan <b>218</b>, a pre-fan filter <b>240</b>, a cyclonic separation apparatus outlet duct <b>260</b> and the cyclonic separation apparatus <b>208</b>.

0120The motor has a drive shaft <b>220</b> with a longitudinal central axis <b>221</b>. The fan is a centrifugal fan <b>218</b> with an axial input <b>222</b> facing away from the motor and a tangential output <b>224</b>. The fan has a diameter of 68 mm. The fan is mounted upon the drive shaft at the top of the motor. The cells <b>217</b> are arranged in a circular array about the motor <b>216</b> with the longitudinal axis of the cells parallel to the central axis <b>221</b>, as is shown most clearly in <figref idref="DRAWINGS">FIGS. 11 and 14</figref>. In use, the motor drives the fan to generate air flow through the cyclonic separation apparatus, as will be described in more detail below.

0121The main body <b>204</b> comprises a central housing <b>226</b>, a motor housing <b>228</b>, a frame <b>230</b> and an end cap <b>232</b>. The fan <b>218</b> is housed in the central housing <b>226</b>. The central housing is connected to the handle <b>206</b>. The motor <b>216</b> and the cells <b>217</b> are housed in the motor housing <b>228</b>. The motor housing is generally elongate to suit the profile of the cells. The end cap <b>230</b> is connected to an opposite end of the motor housing to the fan. The end cap has a circular array of perforations <b>236</b>.

0122The frame <b>230</b> connects the central housing <b>226</b> to the cyclonic separation apparatus <b>208</b>. One end of the frame supports a pre-fan filter <b>240</b> arranged in front of the axial input <b>222</b> of the fan <b>218</b>. The other end of the frame supports the cyclonic separation apparatus.

0123The outlet duct <b>260</b> is defined by a generally oval-shaped duct wall <b>262</b> arranged upon the frame <b>230</b> to form the outlet duct between the duct wall and frame. The outlet duct <b>260</b> provides an air flow path between the cyclonic separation apparatus <b>208</b> and the pre-fan filter <b>240</b>. The duct wall is detachable from the frame. The duct wall is transparent to permit visual inspection of the pre-fan filter. The duct wall is removed from the frame if the pre-fan filter needs cleaning or replacement.

0124The cyclonic separation apparatus <b>208</b> comprises, a vortex finder assembly <b>250</b>, a vortex finder seal <b>270</b>, a cyclone assembly <b>280</b>, a cylindrical perforated intermediate wall <b>290</b>, a circular bulkhead <b>300</b>, a tapered funnel <b>310</b>, a transparent generally cylindrical dirt container <b>320</b> with a longitudinal central axis <b>321</b>, and a circular dirt collection bowl <b>330</b> all arranged about the central axis <b>321</b> of the dirt container <b>320</b>.

0125The vortex finder assembly <b>250</b> comprises a planar generally circular base <b>252</b> with six hollow cylindrical vortex finders <b>254</b>. Each vortex finder has a central through-hole <b>256</b> and its own longitudinal central axis <b>257</b>. The vortex finders are arranged in a circular array about the central axis <b>321</b> of the dirt container <b>320</b>. Each vortex finder is parallel to the central axis <b>321</b>. The vortex finders protrude from one side of the base. A small portion of each vortex finder also protrudes from the opposite side of the base. The vortex finders may have longitudinal internal ribs (not shown) along the through-holes to help dampen high frequency sounds caused by Helmholtz resonance as air flows through the vortex finder though-holes <b>256</b>.

0126The cyclone assembly <b>280</b> comprises a generally cylindrical collar <b>282</b> and a circular array of six cyclones <b>284</b> surrounded by the collar. The cyclones are spaced at equi-angular intervals about the central axis <b>321</b> of the dirt container <b>320</b>. Each cyclone has a hollow cylindrical top part <b>285</b> and a hollow frustro-conical bottom part <b>286</b> depending from the cylindrical top part and terminating with a discharge nozzle <b>287</b> at the bottom of the cyclone.

0127The vortex finder assembly <b>250</b> is arranged upon the collar <b>282</b> of the cyclone assembly <b>280</b>. The vortex finders <b>254</b> protrude into the cylindrical top part <b>285</b> of a respective cyclone <b>284</b>. The only passage through of the top of the cyclone <b>284</b> is via its vortex finder <b>254</b> which acts as an air flow port to the outlet duct <b>260</b>. Each vortex finder is concentric with its respective cyclone. The plane of each nozzle <b>287</b> is inclined with respect to the central axis <b>257</b>. This helps to prevent dust and dirt particles from re-entry after discharge from the nozzle.

0128The cylindrical top part <b>285</b> of each cyclone <b>284</b> has an air inlet port <b>288</b> arranged tangentially through a side of the cyclone and proximal the vortex finder <b>254</b>. The six air inlet ports are in communication with a distribution chamber <b>370</b> located below the collar <b>282</b> around the cyclones <b>284</b> as described in more detail below.

0129The intermediate wall <b>290</b> is arranged upon the cyclone assembly <b>280</b>. The intermediate wall <b>290</b> has approximately the same outer diameter as, and abuts with, the cylindrical collar <b>282</b>.

0130The bulkhead <b>300</b> is arranged upon, and has approximately the same outer diameter as, the intermediate wall <b>290</b>. The bulkhead <b>300</b> is perforated by a circular array of six holes <b>302</b> spaced at equi-angular intervals about the central axis <b>321</b>. The discharge nozzles <b>287</b> of the cyclones <b>284</b> protrude through respective bulkhead holes <b>302</b>. The bulkhead <b>300</b> has a circumferential lip <b>304</b> inclined radially outwardly from the central axis <b>321</b> towards the collection bowl <b>330</b>. The lip <b>304</b> protrudes a small way from the intermediate wall <b>290</b>.

0131The tapered funnel <b>310</b> comprises a hollow circumferential skirt <b>312</b>, a frustro-conical cone <b>314</b> depending from the skirt, and a hollow cylindrical nose <b>316</b> depending from the cone. The skirt is arranged upon, and has approximately the same outer diameter as, the bulkhead <b>300</b>. The cone tapers radially inwardly from the bulkhead towards the collection bowl <b>330</b>. A perforated portion <b>318</b> of the skirt protrudes axially rearward from the cone towards the collection bowl <b>330</b>.

0132The generally cylindrical dirt container <b>320</b> comprises a hollow cylindrical exterior wall <b>322</b> with a circular shoulder <b>324</b> extending radially inwardly from the top of the exterior wall. The dirty container has a dirty air inlet port <b>326</b> arranged tangentially through the exterior wall <b>322</b>. The dirty air inlet port communicates with the dirty air duct <b>210</b>. The exterior wall <b>322</b> is rotatingly connected to the frame <b>230</b> to enable the cyclonic separation apparatus <b>208</b> to rotate about its central axis <b>321</b> in relation to the main body <b>204</b>. The dirty air duct <b>210</b> is rotatable with the cyclonic separation apparatus <b>208</b>, as is shown in <figref idref="DRAWINGS">FIG. 11</figref> where the dirty air duct is in a folded position.

0133The planar base <b>252</b> of the vortex finder assembly <b>250</b> nests within the aperture in the circular shoulder <b>324</b> of the dirt container <b>320</b>. The collar <b>282</b> of the cyclone assembly <b>280</b> abuts the circular shoulder <b>324</b>. The cyclones <b>284</b> are located within the dirt container <b>320</b>.

0134The dirt collection bowl <b>330</b> is detachably connected to an outer circumferential edge <b>332</b> of the dirt container <b>320</b>. The dirt collection bowl abuts the nose <b>316</b> thereby dividing the dirt container and dirt collection bowl into two separate chambers: a circular chamber <b>334</b> inside the tapered funnel <b>310</b> and a generally annular chamber <b>362</b> outside the tapered funnel. The dirt collection bowl <b>330</b> may be connected to the dirt container's outer circumferential edge by snap-fit, bayonet fit, interlocking detents, interference fit or by a hinge. A resilient seal <b>336</b> made of polyethylene, rubber or a similar elastomeric material is provided around the dirt collection bowl <b>330</b> to ensure airtight connection with the dirt container.

0135The dirt container <b>320</b> has an annular lip <b>328</b> inclined radially inwardly to the central axis <b>321</b> towards the collection bowl <b>330</b>. The lip <b>328</b> protrudes a small way in from the exterior wall. The lip <b>328</b> is proximal to the bowl <b>330</b>.

0136The nose <b>316</b> of the tapered funnel <b>310</b> is in complementary mating relationship with a circular ring <b>340</b> protruding from inside the dirt collection bowl <b>330</b>. This ensures that components of the cyclonic separation apparatus <b>208</b> remain concentric with the central axis <b>321</b> of the dirt container <b>320</b>.

0137In use, dirty air flows, under the influence of the fan <b>218</b>, in the dirty air inlet <b>212</b>, up the dirty air duct <b>210</b> and into the cyclonic separation apparatus <b>208</b> where dust and dirt entrained in the air flow is separated therefrom. The dust and dirt is collected within the cyclonic separation apparatus. The air flows out the cyclonic separation apparatus <b>208</b>, via the through-holes <b>256</b> of the vortex finders, along the outlet duct <b>260</b>, through the _pre-fan filter <b>240</b>, through the fan <b>218</b> and over the motor <b>216</b> and batteries cells <b>217</b> via the motor housing <b>228</b> and out the perforations <b>236</b> in the end cap <b>230</b>.

0138Referring to <figref idref="DRAWINGS">FIG. 17A</figref>, the cyclonic separation apparatus <b>208</b> is divided into a first cyclonic separating unit <b>360</b>, a second cyclonic separating unit <b>350</b> and the distribution chamber <b>370</b>. The first cyclonic separating unit is located in the air flow pathway upstream of the distribution chamber. The distribution chamber is located in the air flow pathway upstream of the second cyclonic separating unit.

0139The first cyclonic separating unit <b>360</b> comprises the cylindrical dirt container <b>310</b>. The second cyclonic separating unit <b>350</b> comprises the circular array of six cyclones <b>284</b>. The dirt container is concentric with the central axis <b>321</b> of the dirt container. The distribution chamber <b>370</b> is bounded by the collar <b>282</b>, cyclone assembly <b>280</b>, intermediate wall <b>290</b> and bulkhead <b>300</b>. The second cyclonic separating unit <b>350</b> receives air flow from the first cyclonic separating unit <b>360</b> via the distribution chamber <b>370</b>.

0140The exterior wall <b>322</b> of the dirt container <b>320</b> has a diameter of approximately 120 mm. The cyclones <b>284</b> have a smaller diameter than the annular chamber <b>362</b>. Helical air flow in the cyclones experiences greater centrifugal forces than in the dirt container. Thus, the cyclones of the second cyclonic separating unit <b>350</b>, when combined, have higher separation efficiency than the dirt container of the first cyclonic separating unit <b>360</b>.

0141The air flow pathway though the cyclonic separation apparatus <b>208</b> is described in more detail with reference to <figref idref="DRAWINGS">FIGS. 17B to 17F</figref>.

0142Referring to <figref idref="DRAWINGS">FIG. 17B</figref>, dirty air (triple-headed arrows) flows from the dirty air duct <b>210</b> and into the dirt container <b>320</b> via the dirty air inlet port <b>326</b>. The tangential arrangement of the dirty air inlet port <b>326</b> causes the dirty air to flow in a helical path around the dirt container. This creates an outer vortex in the dirt container. Centrifugal forces move the comparatively large dust and dirt (D) particles outwards to strike the side of the dust container <b>320</b> and separate them from the air flow. The separated dust and dirt swirls towards the dirt collection bowl <b>330</b> where it is deposited.

0143Referring to <figref idref="DRAWINGS">FIG. 17C</figref>, partially-cleaned air (double-headed arrows) flows back on itself to follow an inner helical path closely about the tapered funnel <b>310</b> and towards the cylindrical intermediate wall <b>290</b>. The partially-cleaned air flows through the perforated portion <b>318</b> of the tapered funnel's skirt <b>312</b> largely unimpeded. The circumferential lip <b>304</b> of the bulkhead <b>300</b> and the lip <b>328</b> of the dirt container <b>320</b> converge at a width restriction Y in the first cyclonic separating unit <b>360</b>. The width restriction reduces a radial width between the dirt container and the intermediate wall by at least 15 percent. The width restriction tapers towards the bowl <b>330</b> so that air, and entrained dirt, can flow more easily towards the bowl door than in the opposite direction. Thus, the circumferential lips <b>304</b>, <b>328</b> and perforated portion <b>318</b> of the tapered funnel's skirt <b>312</b> catch separated dirt in the bowl <b>324</b> before it can be re-entrained in the partially-cleaned air flow. The partially-cleaned air flows through perforations in the intermediate wall, which filters any remaining large dirt particles, and into the distribution chamber <b>370</b>.

0144As can be seen in <figref idref="DRAWINGS">FIG. 16</figref>, the air inlet ports <b>288</b> of the six cyclones are moulded into the collar <b>282</b> of the cyclone assembly <b>280</b>. The distribution chamber <b>370</b> is in communication with the air inlet ports <b>288</b> of the six cyclones <b>284</b>. Referring to <figref idref="DRAWINGS">FIG. 17D</figref>, the partially-cleaned air flow (double-headed arrows) divides itself, in the distribution chamber, evenly between the six air inlet ports <b>288</b> from where it flows into the six cyclones <b>284</b> of the second cyclonic separating unit <b>350</b>. The air inlet ports <b>288</b> direct the partially-cleaned air flow in a helical path around the vortex finders <b>254</b>. This creates an outer vortex inside each cyclone <b>284</b>. Centrifugal forces move the dust and dirt outwards to strike the side of the cyclone and separate it from the air flow. The separated dust and dirt swirls towards the discharge nozzle <b>287</b>. The internal diameter of the frustro-conical body <b>286</b> of cyclone diminishes as the air flow approaches the nozzle. This accelerates the helical air flow thereby increasing centrifugal forces and separating ever smaller dust and dirt particles. The dust and dirt particles exit the nozzle to be deposited inside the part of the bowl <b>330</b> bounded by the tapered funnel <b>310</b>.

0145Referring to <figref idref="DRAWINGS">FIG. 17E</figref>, cleaned air (single-headed arrows) flows back on itself to follow a narrow inner helical path through the middle of the cyclone <b>284</b>. The cleaned air flows out the internal through-hole <b>256</b> of the vortex finder <b>254</b>, under the influence of the fan.

0146Returning to <figref idref="DRAWINGS">FIG. 17F</figref>, the cleaned air flows from the vortex finders <b>254</b> into the outlet duct <b>260</b> and to the pre-fan filter <b>240</b>. The pre-fan filter <b>240</b> is to remove any fine dust and dirt particles remaining in the air flow after the cyclonic separation apparatus <b>208</b> and before the fan <b>218</b>. The clean air flows into the axial input <b>222</b> of the fan <b>218</b> and is expelled from the tangential output <b>224</b> of the fan. Pathways in the central housing <b>226</b> direct the clean air flow from the fan over the motor <b>216</b> and cells <b>217</b>, to cool the motor and cells, before the air flows out the perforations <b>236</b> in the end cap <b>232</b>.

0147Dust and dirt separated by the first and second cyclonic separating units and deposited in the dirt collection bowl <b>330</b> which can be opened for emptying.

0148Referring to <figref idref="DRAWINGS">FIG. 18</figref>, there is shown a diagrammatical view of the various components of the cyclonic separation apparatus <b>208</b> (vortex finder assembly <b>250</b>, vortex finder seal <b>270</b>, cyclone assembly <b>280</b>, intermediate wall <b>290</b>, bulkhead <b>300</b>, tapered funnel <b>310</b>) located within confines of the outlet duct <b>260</b>, frame <b>230</b>, dirt container <b>320</b> and dirt collection bowl <b>330</b>.

0149The vortex finder seal <b>270</b> seals the connections between the vortex finder assembly <b>250</b> and the dirt container <b>320</b> in an airtight manner. An outlet duct seal <b>266</b> seals the connection between the frame <b>230</b> and the outlet duct wall <b>262</b> in an airtight manner. The vortex finder seal <b>270</b> and the outlet duct seal <b>266</b> are made of polyethylene, rubber or a similar elastomeric material.

0150Certain components of the cyclonic separation apparatus <b>208</b> are detachably connected, typically by a snap-fit, bayonet fit, interference fit or by interlocking detents. This permits disassembly and reassembly, without tools, of the cyclonic separation apparatus in order to clean, or replace, its individual components, as is described with reference to <figref idref="DRAWINGS">FIGS. 19 to 22</figref>.

0151Referring to <figref idref="DRAWINGS">FIG. 19</figref>, there is shown a method of disassembling a first construction of the cyclonic separation apparatus <b>208</b> whereby the outlet duct wall <b>262</b> is detachable from the frame <b>230</b>. The dirt container <b>320</b> is detachable from the frame. The vortex finder assembly is detachable from the frame with, or without, the dirt container. The cyclone assembly <b>280</b>, intermediate wall <b>290</b>, bulkhead <b>300</b>, and tapered funnel <b>310</b> are also detachable, in unison, from the vortex finder assembly. The dirt collection bowl <b>330</b> has a large enough diameter to enable, when the dirt collection bowl is opened, removal of the cyclone assembly <b>280</b>, intermediate wall <b>290</b>, bulkhead <b>300</b>, and tapered funnel <b>310</b> out the dirt container <b>320</b>.

0152Referring to <figref idref="DRAWINGS">FIG. 20</figref>, there is shown a method of disassembling an alternative construction of the cyclonic separation apparatus <b>208</b> whereby the outlet duct wall <b>262</b> is detachable from the frame <b>230</b>. The dirt container <b>320</b> is detachable from the frame. The vortex finder assembly <b>250</b>, cyclone assembly <b>280</b>, intermediate wall <b>290</b>, bulkhead <b>300</b>, and tapered funnel <b>310</b> are detachable, in unison, from the frame with, or without, the dirt container. The dirt collection bowl <b>330</b> is can be opened for emptying.

0153Referring to <figref idref="DRAWINGS">FIG. 21</figref>, there is shown a method of disassembling a second alternative construction of the cyclonic separation apparatus <b>208</b> whereby the outlet duct wall <b>262</b> is detachable from the frame <b>230</b>. The dirt container <b>320</b>, vortex finder assembly <b>250</b>, cyclone assembly <b>280</b>, intermediate wall <b>290</b>, bulkhead <b>300</b>, and tapered funnel <b>310</b> are detachable, in unison, from the frame. The dirt collection bowl <b>330</b> can be opened for emptying.

0154Referring to <figref idref="DRAWINGS">FIG. 22</figref>, there is shown a method of disassembling a third alternative construction of the cyclonic separation apparatus <b>208</b> whereby the outlet duct <b>260</b> (i.e. duct wall <b>262</b> and frame <b>230</b>) is detachable from the frame. The dirt container <b>320</b> remains with the frame. The vortex finder assembly <b>250</b>, cyclone assembly <b>280</b>, intermediate wall <b>290</b>, bulkhead <b>300</b>, and tapered funnel <b>310</b> are removable, in unison, from the frame when the dirt bowl <b>330</b> is opened.

0155Referring to <figref idref="DRAWINGS">FIG. 23</figref>, there is shown a third embodiment of hand-held vacuum cleaner <b>402</b> comprising a main body <b>404</b> with a handle <b>406</b>, a cyclonic separation apparatus <b>408</b> mounted to the main body, and a dirty air duct <b>410</b> with a dirty air inlet <b>412</b> at one end. The vacuum cleaner comprises a motor coupled to a fan for generating air flow through the vacuum cleaner and rechargeable cells to energise the motor when electrically coupled by an on/off switch <b>414</b>.

0156Referring to <figref idref="DRAWINGS">FIGS. 24 to 27</figref>, there is shown in more detail the motor <b>416</b>, the rechargeable cells <b>417</b>, the fan <b>418</b>, a pre-fan filter <b>440</b>, a cyclonic separation apparatus outlet duct <b>460</b> and the cyclonic separation apparatus <b>408</b>.

0157The motor has a drive shaft <b>420</b>. The fan <b>418</b> is mounted upon the drive shaft at the top of the motor. The fan has a diameter of approximately 68 mm. The cells <b>417</b> are arranged about the motor <b>416</b>. In use, the motor drives the fan to generate air flow through the cyclonic separation apparatus, as will be described in more detail below.

0158The main body <b>404</b> comprises a central housing <b>426</b> and a frame <b>430</b>. The motor <b>416</b>, fan <b>418</b> and cells <b>417</b> are housed in the central housing <b>426</b>. The central housing is connected to the handle <b>406</b>. The central housing has an array of perforations <b>436</b> near the bottom of the motor. The perforations <b>436</b> are for air flow expelled from the central housing.

0159The frame <b>430</b> connects the central housing <b>426</b> to the cyclonic separation apparatus <b>408</b>. One end of the frame supports a pre-fan filter <b>440</b> arranged in front of the fan's input. The other end of the frame supports the cyclonic separation apparatus. The cyclonic separation apparatus is rotatingly connected to the frame.

0160Outlet duct <b>460</b> comprises a duct wall <b>462</b> arranged upon the frame to form a passage between the duct wall and frame approximately 10 mm deep. The outlet duct <b>460</b> provides an air flow path between the cyclonic separation apparatus <b>408</b> and the pre-fan filter <b>440</b>. The duct wall is detachable from the frame. The duct wall is transparent to permit visual inspection of the pre-fan filter. A resilient seal made of polyethylene, rubber or similar elastomeric material is provided around the duct wall to ensure air tight connection with the frame. The duct wall is removed from the frame if the pre-fan filter needs cleaning or replacement.

0161The cyclonic separation apparatus <b>408</b> comprises a vortex finder assembly <b>450</b>, a cyclone assembly <b>480</b>, and an elongate generally oval-shaped dirt container <b>520</b> with a transparent door <b>530</b>.

0162The vortex finder assembly <b>450</b> has a hollow cylindrical vortex finder <b>452</b> with a tapered deflector fin <b>454</b>. The vortex finder has a central through-hole <b>456</b> with a longitudinal central axis <b>457</b>. The deflector fin protrudes radially from the outer surface of the vortex finder. In the present embodiment the tapered deflector fin is triangular although it could have another tapered profile. The triangular profile of the deflector fin <b>454</b> is a right angled triangle.

0163The cyclone assembly <b>480</b> comprises a cyclone <b>484</b> and a dirty air inlet port <b>488</b>. The cyclone has a hollow cylindrical body <b>485</b> with the dirty air inlet port and a hollow frustro-conical bottom body <b>486</b> extending from the cylindrical body and terminating with a discharge nozzle <b>487</b> at the narrower end. The air inlet port is arranged tangentially through a side of the cylindrical body. The vortex finder <b>454</b> is arranged inside the cyclone <b>484</b>. The vortex finder is concentric with the cyclone. The deflector fin <b>454</b> is arranged transverse to the path of air flow from the air inlet port. The radially extending short side of the deflector fin abuts the frame <b>430</b>. An apex <b>4541</b> of the deflector fin is proximal to the air inlet port. The hypotenuse side of the deflector fin tapers radially inwardly from the apex to the end of the vortex finder proximal to the discharge nozzle <b>487</b>. There is a small gap of Z approximately 5 mm between the apex and the cylindrical body <b>485</b> of the cyclone <b>484</b>.

0164The dirt container <b>520</b> is connected to the central housing <b>426</b> at one end and the discharge nozzle <b>487</b> of the cyclone <b>484</b> at the other end. The dirt container comprises a perimeter wall <b>522</b> following the outer perimeter of the elongate generally oval-shaped dirt container and base wall <b>524</b> with a cylindrical pocket <b>526</b> protruding from the base wall into the confines of the dirt container. The cyclone <b>484</b> is in communication with the dirt container where the nozzle <b>487</b> protrudes through the base wall <b>524</b>. The bottom of the motor <b>416</b> is seated inside the pocket <b>526</b> on the opposite side to the dirt container thereby reducing the overall width of the vacuum cleaner by about 20 to 25 mm.

0165The cyclone <b>484</b> has a curved fin <b>490</b> protruding axially from the discharge nozzle <b>487</b> into the dirt container <b>520</b>. The curved fin circumscribes an arc of about half the circumference of the nozzle facing the pocket <b>526</b>. The ends of the curved fin taper towards the nozzle. The dirt container has a flat fin <b>492</b> protruding from the base wall <b>524</b>. The flat fin extends tangentially from the top of the pocket <b>526</b> to about the middle of the dirt container. The flat fin is generally parallel to an adjacent initial flat portion <b>522</b><i>a </i>of the perimeter wall <b>522</b> uppermost on the dirt container in normal use.

0166The door <b>530</b> is detachably connected to the perimeter wall <b>522</b> of the container <b>520</b>. The door <b>530</b> may be connected to the dirt container by snap-fit, interlocking detents, a hinge <b>528</b> or by interference fit with the dirt container's exterior wall. In the example shown, the door is held firmly closed by a spring-loaded latch <b>529</b>. A resilient seal (not shown) made of polyethylene, rubber or a similar elastomeric material is provided around the door <b>530</b> to ensure connection to the dirt container <b>320</b> in an airtight manner. Dust and dirt separated by the cyclonic separation apparatus and deposited in the dirt container <b>520</b> can be emptied by opening the door <b>530</b>. The door is transparent to enable visual inspection of when the dirt container <b>520</b> is full and is in need of emptying.

0167In use, dirty air flows, under the influence of the fan <b>418</b>, in the dirty air inlet <b>412</b>, up the dirty air inlet duct <b>410</b> and into the cyclonic separation apparatus <b>408</b> where dust and dirt entrained in the air flow is separated therefrom. The dust and dirt is collected within the cyclonic separation apparatus. Air flows out the cyclonic separation apparatus <b>408</b>, via the through-hole <b>456</b> of the vortex finder, along the outlet duct <b>460</b>, through the pre-fan filter <b>440</b>, through the fan <b>418</b> and over the motor <b>416</b> and cells <b>417</b> via the central housing <b>426</b> and out the perforations <b>436</b> in the central housing.

0168Referring to <figref idref="DRAWINGS">FIGS. 24</figref>, <b>27</b> and <b>28</b>, air flow though the cyclonic separation apparatus <b>408</b> is described in more detail. Dirty air (triple headed arrows) from the dirty air duct <b>410</b> enters the cylindrical body <b>485</b> of the cyclone <b>484</b> via the air inlet port <b>488</b>. The tangential arrangement of the air inlet port <b>488</b> and presence of the triangular deflector fin <b>454</b> protruding from the vortex finder <b>452</b> direct the dirty air to flow in a helical path around the cyclone and towards the frustro-conical body <b>486</b> and then the discharge nozzle. This creates an outer vortex in the cyclone. Centrifugal forces move the comparatively large dust and dirt particles outwards to strike the side of the cyclone and separate them from the air flow. The separated dust and dirt swirls towards the discharge nozzle <b>487</b> and into the dirt container <b>520</b>.

0169The partially-cleaned air flow (double-headed arrows) is directed by the curved fin <b>490</b> and a proximal curved portion <b>522</b><i>d </i>of the perimeter wall <b>522</b> to leave the cyclone <b>484</b> in an anti-clockwise upward direction, as viewed in <figref idref="DRAWINGS">FIG. 24</figref>. This helps maintains air flow speed. The flat fin <b>492</b> and the pocket <b>526</b> help to direct the partially cleaned air flow to follow an elongate circuit about the perimeter wall <b>522</b> of dirt container <b>520</b>, similar in shape to a two-pulley belt drive wherein the discharge nozzle <b>487</b> simulates a pulley at one end and the pocket <b>526</b> simulates a pulley at the opposite end. For example, the elongate circuit of air flow begins outbound away from the discharge nozzle in proximity to the initial flat portion <b>522</b><i>b </i>of the perimeter wall <b>522</b> and is redirected inside a distal curved portion <b>522</b><i>c </i>of the perimeter wall <b>522</b> to turn around the pocket <b>526</b> and continue inbound towards the discharge nozzle adjacent to a further flat portion <b>522</b><i>d </i>of the perimeter wall lower most on the dirt container in normal use. An axis of elongation of the elongate circuit runs approximately through the centres of the discharge nozzle and the pocket. The flat fin and the pocket prevent the bulk of the dust and dirt particles (D) from dropping out of the circulating air flow before being deposited upon the further flat portion <b>522</b><i>d </i>of the perimeter wall at the bottom of the dirt container. The perimeter wall <b>522</b> has a generally lozenge shape in cross-section parallel to the base wall <b>524</b>. The initial flat portion <b>522</b><i>a </i>and the further flat portion <b>522</b><i>c </i>of the perimeter wall taper inwardly and away from the distal curved portion <b>522</b><i>b </i>of the perimeter wall. This encourages deposit of dust and dirt around the pocket end of the dirt container where there is more space than at the opposite discharge nozzle end of the dirt container. Also, the curved fin <b>490</b> acts as an obstacle to laminar air flow inbound to the discharge nozzle. The air flow is forced to deviate around the curved fin. This disruption of laminar air flow provokes deposit of any remaining entrained dirt and dust (D) in the dirt container. As such, the shape of the perimeter wall <b>522</b>, the flat fin <b>492</b>, the pocket <b>526</b> and the curved fin <b>490</b> combine to help to separate any remaining dust and dirt from air flow path destined for the pre-fan filter <b>440</b>. This increases sustained performance of the vacuum cleaner <b>502</b>.

0170Having deviated past the curved fin <b>490</b>, clean air flow (single-headed arrows) turns back on itself and, under the influence of the fan, flows in a narrow inner helical path into the vortex finder's through-hole <b>456</b> from where it leaves the cyclonic separation apparatus <b>408</b> and enters the outlet duct <b>460</b>.

0171Referring to <figref idref="DRAWINGS">FIGS. 29 to 38</figref>, there is shown a variety of battery-powered vacuum cleaners with the motor <b>16</b>, fan <b>18</b> and cyclonic separation apparatus <b>8</b> arrangement of the first embodiment. The arrangement is, in all examples, arranged with the central axis <b>21</b> of the drive shaft <b>20</b> orientated transverse a main axis of the main body of the vacuum cleaner. In particular, there is shown a hand-holdable vacuum cleaner <b>602</b> with pivotable dirty air duct <b>610</b>; a hand-holdable vacuum cleaner <b>702</b> connected to a cleaning nozzle <b>712</b> by a flexible hose <b>710</b> to resemble a small cylinder vacuum cleaner; and a vacuum cleaner <b>802</b> with an elongate body. <b>806</b>, a support wheel <b>807</b> and a cleaner head <b>812</b> to resemble an upright vacuum cleaner, also commonly referred to as a “stick-vac”.

0172Referring to <figref idref="DRAWINGS">FIGS. 29 to 32</figref>, the hand-holdable vacuum cleaner <b>602</b> comprises a main body <b>604</b> with a main axis <b>605</b> and a handle <b>606</b>. The motor <b>16</b>, fan <b>18</b> and cyclonic separation apparatus <b>8</b> of the first embodiment are rotatingly connected to the main body <b>604</b> at the annular roof wall <b>121</b> of the dirt container <b>120</b>. The central axis <b>21</b> of the cyclonic separation apparatus is orientated at a right angle (i.e. transverse) to the main axis of the main body. The vacuum cleaner <b>602</b> comprises a battery pack <b>900</b> of rechargeable cells <b>917</b> to energise the motor <b>16</b> when electrically coupled by an on/off switch. The dirty air duct <b>610</b> is connected to the air inlet port <b>126</b>.

0173Referring in particular to <figref idref="DRAWINGS">FIG. 31</figref>, the battery pack <b>900</b> has a curvilinear cross-sectional profile with a curvilinear inner wall <b>902</b> shaped to fit around the cylindrical dirt container <b>120</b>. The battery pack <b>900</b> has a pair of electrical contacts <b>904</b> on a curvilinear outer wall <b>906</b> so that the cells may be recharged in situ. The battery pack is detachably connected to the dust container <b>120</b>. The battery pack may be detached from the duct container to enable replacement, or external recharging of the cells, if necessary. The cells have a generally cylindrical shape. Longitudinal axes of cells are arranged parallel to the central axis <b>21</b> of the motor <b>16</b>.

0174The dirty air duct <b>610</b> and the battery pack <b>900</b> are rotatable, with the cyclonic separation apparatus <b>8</b>, about the central axis <b>21</b> through an arc subtending 210 degrees from a folded position. This allows the vacuum cleaner <b>602</b> to be pointed in different directions, whilst a user is able to hold the vacuum cleaner in the same orientation. The vacuum cleaner may be used to access awkward spaces and can be held more comfortably by orientating the main axis <b>605</b> of the main body <b>604</b> to suit the user and adjusting the position of the dirty air inlet <b>612</b> to point at a surface to be cleaned, rather than orientating the main axis to best suit the surface to be cleaned and requiring the user to hold the vacuum cleaner in whichever orientation this demands.

0175<figref idref="DRAWINGS">FIGS. 29 and 30</figref> show the vacuum cleaner <b>602</b> in the folded position where the dirty air duct is folded at zero degrees under the handle <b>606</b> for compact storage. The battery pack <b>900</b> is rotated to the diametrically opposite side of the dirt container <b>120</b>. The vacuum cleaner may be cradled by a battery charger <b>916</b> in the upright position shown in <figref idref="DRAWINGS">FIG. 29</figref>. This allows the vacuum cleaner to be stood in a small surface area and without excessive height because the dirty air duct is folded under the handle. Arranged like this, the vacuum cleaner is easier to grab. The vacuum cleaner's centre of gravity is lowered by the battery pack thus making the upright position more stable. Moreover, the cells <b>917</b> are electrically coupled by the electrical contacts <b>904</b> to the battery charger <b>916</b> for recharging in the upright position.

0176<figref idref="DRAWINGS">FIG. 32</figref> shows the vacuum cleaner <b>602</b> in an extended position. The dirty air duct <b>610</b> is rotated through 180 degrees from the folded position and is ready for use. The dirty air duct <b>610</b> has been telescopically extended to double its length. The battery pack <b>900</b> occupies a gap <b>616</b> between the handle <b>606</b> and the dirt container <b>120</b>. The battery pack is relatively heavy and its location in the gap <b>616</b> moves the vacuum cleaner's centre of gravity closer to the handle. This improves the ergonomics of the vacuum cleaner.

0177Referring to <figref idref="DRAWINGS">FIGS. 33 and 34</figref>, the hand-holdable vacuum cleaner <b>702</b> comprises a body <b>704</b> with a handle <b>706</b>. The motor <b>16</b>, fan <b>18</b> and cyclonic separation apparatus <b>8</b> is connected to the body <b>704</b> at the annular roof wall <b>121</b> of the dirt container <b>120</b>. The vacuum cleaner <b>702</b> comprises a pack <b>910</b> of rechargeable cells. The cells are to energise the motor <b>16</b> when electrically coupled by an on/off switch. The air inlet port <b>126</b> is connected to one end of the flexible hose <b>710</b>. The cleaning nozzle <b>712</b> is connected to the other end of the flexible hose.

0178The battery pack <b>910</b> has a curvilinear inner wall <b>902</b> which is shaped to cradle the cylindrical dust container <b>120</b>. The battery pack is detachably connected to the dust container <b>120</b>. The cells may be recharged in situ. The battery pack may be detached from the dirt container to enable replacement, or external recharging of the cells, if necessary. The battery pack has a pair of feet <b>912</b> arranged to support the vacuum cleaner <b>702</b> in a stable manner when placed upon a flat surface. The cells have a generally cylindrical shape. Longitudinal axes of the cells are arranged parallel to the central axis <b>21</b> of the motor <b>16</b>.

0179<figref idref="DRAWINGS">FIGS. 32 and 34</figref> show a compact configuration of the vacuum cleaner <b>702</b>. The flexible hose <b>710</b> is wrapped around the dirt container <b>120</b> and under the battery pack <b>910</b> via rebates <b>914</b> in the battery pack feet <b>912</b>. The cleaning nozzle <b>712</b> is cradled by the handle <b>706</b>. The handle is moulded in plastics material with natural resilience. The cleaning nozzle is gripped by the handle. The cleaning nozzle can be readily detached from the handle for use in vacuum cleaning.

0180Referring to <figref idref="DRAWINGS">FIGS. 35 and 37</figref>, the vacuum cleaner <b>802</b> comprises the elongate body <b>804</b>. The elongate body is telescopic. The elongate body has a handle <b>806</b> at one end and a bracket <b>805</b> at the other end. The motor <b>16</b>, fan <b>18</b> and cyclonic separation apparatus <b>8</b> of the first embodiment are rotatingly connected to the bracket <b>805</b> at the annular roof wall <b>121</b> of the dirt container <b>120</b>. The bracket arches around one side of the dirt container so that the latter may be connected transverse to the elongate body. The support wheel <b>807</b> surrounds the dirt container <b>120</b>. The support wheel is supported for rotation about the dirt container by a bearing <b>809</b>. The air inlet port <b>126</b> is connected to one end of the dirty air duct <b>810</b>. The cleaner head <b>812</b> is connected to the other end of the dirty air duct <b>810</b>. The cleaner head is pivotable in relation to the dirt container about a longitudinal axis <b>8100</b> of the dirty air duct. The dirty air duct is arranged tangentially to the dirt container.

0181The vacuum cleaner comprises a battery pack <b>900</b> of rechargeable cells <b>917</b> to energise the motor <b>16</b> when electrically coupled by an on/off switch. Referring to <figref idref="DRAWINGS">FIG. 37</figref>, the battery pack <b>900</b> has a curvilinear inner wall <b>902</b> which is shaped to embrace the support wheel <b>807</b> and part of the cylindrical dirt container <b>120</b>. The battery pack is detachably connected to the bracket <b>805</b>. The cells <b>917</b> may be recharged in situ. The battery pack may be detached from the bracket to enable replacement, or external recharging of the cells, if necessary. The cells have a generally cylindrical shape. Longitudinal axes of the cells are arranged parallel to the central axis <b>21</b> of the motor <b>16</b>.

0182Returning to <figref idref="DRAWINGS">FIG. 35</figref>, there is shown the vacuum cleaner <b>802</b>, prepared for use, with the support wheel <b>807</b> and the cleaning head <b>812</b> upon a floor and the elongate body <b>804</b> fully extended. The support wheel <b>807</b> is arranged about the midpoint of the axial length of the dirt container. The diameter of support wheel <b>807</b> is approximately the same as the axial length of the dirt container <b>120</b> so that the elongate body can be rocked from side to side by about 45 degrees each way and the vacuum cleaner <b>802</b> can be steered with ease.

0183Returning to <figref idref="DRAWINGS">FIG. 37</figref>, there is shown the vacuum cleaner with the elongate body <b>804</b> fully retracted to approximately a quarter of the elongate body's extended length. The vacuum cleaner's overall length when the elongate body is extended is at least double the vacuum cleaner's overall length when the elongate body is retracted. The vacuum cleaner <b>802</b> is prepared for storage in a kitchen cupboard when the elongate body is retracted. The elongate body may be locked in its retracted and extended positions. The skilled person will appreciate that any suitable locking system will suffice, like, for example, a spring-loaded detent interlockable with holes along the elongate body corresponding to the retracted position, the extended position and any intermediate position therebetween.

0184Referring to <figref idref="DRAWINGS">FIG. 38</figref>, there is shown in perspective the shape of the battery pack <b>900</b> and, in particular, the curvilinear inner wall <b>902</b> which is to embrace, or connect to, the outside of the dirt container <b>120</b> of the cyclonic separation apparatus <b>8</b>.

0185Referring to <figref idref="DRAWINGS">FIGS. 39 and 40</figref>, there is shown the battery pack <b>900</b> along cross-section XXXVIII-XXXVIII. Commercially available rechargeable cells may be cylindrical in shape. <figref idref="DRAWINGS">FIG. 39</figref> shows five cylindrical cells <b>917</b> stacked in a curved array to conform to the internal cavity of the curvilinear cross-section profile of the battery pack. Also commercially available are plate rechargeable cells <b>927</b> composed of flexible anode and cathode plates, or sheets, interposed by a polymer electrolyte material and separator material. The anode sheets are electrically connected to the positive cell terminal and the cathode sheets are electrically connected to the negative cell terminal, and those sheets can be connected in series or in parallel to form a battery pack. These plate cells are flexible and they can be stacked upon each other. <figref idref="DRAWINGS">FIG. 40</figref> shows three plate cells <b>927</b> stacked upon each other and curved to conform to the internal cavity of the curvilinear cross-section profile of the battery pack.

0186Referring to <figref idref="DRAWINGS">FIGS. 41 to 43</figref> there is shown an annular battery pack <b>920</b> in cross-section which is adapted to surround the dirt container <b>120</b> of the cyclonic separation apparatus <b>8</b> with a hollow cylindrical inner surface <b>922</b>. The annular battery pack has a cylindrical inner wall <b>922</b> and a cylindrical outer wall <b>926</b>.

0187<figref idref="DRAWINGS">FIG. 41</figref> shows <b>12</b> cylindrical cells <b>917</b> arranged in a circular array to conform to the internal cavity of the annular cross-sectional profile of the annular battery pack <b>920</b>.

0188<figref idref="DRAWINGS">FIG. 42</figref> shows three plate cells <b>927</b> stacked upon each other and curved into a hollow cylindrical shape to conform to the internal cavity of the annual cross-section of the annular battery pack <b>920</b>.

0189<figref idref="DRAWINGS">FIG. 43</figref> shows five plate cells <b>927</b> wound into a hollow cylindrical shape to conform to the internal cavity of the annular cross-section of the annular battery pack <b>920</b>.

0190The curved plate cells <b>927</b> improve use of the internal cavity of the battery packs <b>920</b> by eliminating the gaps which naturally exist between the cylindrical cells <b>917</b>. This results in a more compact design of battery pack with reduced packaging and a higher energy density.

0191The curvilinear or cylindrical inner walls <b>902</b>,<b>922</b> of the curvilinear battery pack <b>900</b>,<b>910</b> and the annular battery pack <b>920</b> embrace, or attach themselves to, the dirt container <b>120</b>. This facilitates new design choices for accommodating cells in a compact manner.

0192The skilled addressee will appreciate that the rechargeable cells can be any type of energy accumulator, including rechargeable Lithium Ion, Nickel Metal Hydride or Nickel Cadmium rechargeable cells, for driving the electric motor <b>16</b>, <b>216</b>, <b>416</b>.

0193The skilled addressee will appreciate that the specific overall shapes and sizes of the arrangements comprising the motor <b>16</b>, <b>216</b>, <b>416</b> the fan <b>18</b>, <b>218</b>, <b>418</b> and the cyclonic separation apparatus <b>8</b>, <b>208</b>, <b>408</b> can be varied according to the type of vacuum cleaner in which either of the arrangements is to be used. For example, the overall length or width of each arrangement, and, in particular, the cyclonic separation apparatus, can be increased or decreased with respect to its diameter, and vice versa.

0194In particular, the hand-holdable vacuum cleaner <b>702</b> of <figref idref="DRAWINGS">FIGS. 33 and 34</figref> can be modified to comprise the motor <b>216</b>, fan <b>218</b> and cyclonic separation apparatus <b>208</b> of the embodiment by modifying the form of the battery pack <b>910</b> to suit the underside of the dirt container <b>320</b>. The flexible hose <b>710</b> would need extension to be wrapped around the dirt container <b>320</b> and the central housing <b>226</b> and motor housing <b>228</b>.

0195Further, the hand-holdable vacuum cleaner <b>802</b> of <figref idref="DRAWINGS">FIGS. 35 to 38</figref> can be modified to comprise the motor <b>216</b>, fan <b>218</b> and cyclonic separation apparatus <b>208</b> of the second embodiment by substituting the central housing <b>226</b> and motor housing <b>228</b> for the main bracket <b>805</b>. This could be done by attaching the elongate body <b>804</b> directly to the central housing <b>226</b> in place of the handle <b>206</b> and the bracket <b>805</b>. The cyclonic separation apparatus outlet duct <b>260</b> would need extension to create enough clearance for the support wheel <b>807</b> and bearing <b>809</b> to surround the dirt container <b>320</b>.

0196The motor <b>16</b>, <b>216</b>, <b>416</b> discussed above is a typically a brushed d.c. motor with its drive shaft <b>20</b>,<b>220</b>,<b>420</b> directly coupled to the centrifugal fan <b>18</b>, <b>218</b>, <b>418</b>. The motor's drive shaft has a rotational speed within a range of 25,000 and 40,000 revolutions per minute (rpm). A centrifugal fan with a rotational speed within this range has an outer diameter approximately double the outer diameter of the motor can in order to have sufficient tip speed to generate the required volumetric flow rate through the cyclonic separation apparatus. The skilled person will appreciate that the motor <b>16</b>,<b>216</b>,<b>416</b> can be a d.c. motor, an a.c. motor, or an asynchronous multi-phase motor controlled by an electronic circuit. A permanent magnet brushless motor, a switched reluctance motor, a flux switching motor, or other brushless motor type, may have a high rotational speed within a range of 80,000 to 120,000 rpm. If such a high speed motor were used then the fan diameter could be at least halved and yet still generate the required volumetric flow through the cyclonic separation apparatus because the fan's tip speed would be so much higher. This would make the fan's outer diameter the same as the motor can's outer diameter and could possibly make it less than the motor can's outer diameter if the motor operates at around the upper end of the high rotational speed range. A smaller diameter fan operating within this range of high rotational speeds would typically be an impeller although it may be an axial fan or a centrifugal fan. The outer profile of the smaller fan coupled to the drive shaft of the high rotational speed motor would have a generally cylindrical outer profile. This provides additional flexibility in the layout of the cyclonic separation apparatus.

0197In a modification of the first or second embodiment of a cyclonic separation apparatus <b>8</b>,<b>208</b> which is not shown in the drawings, the cyclones <b>84</b>,<b>284</b> can be rearranged to accommodate a high rotational speed permanent magnet brushless motor, a switched reluctance motor or a flux switching motor coupled to a fan which is coaxial with the motor and has an outer diameter substantially the same as or less than the outer diameter of the motor. The generally cylindrical outer profile of high speed motor and fan can be sunk into the cyclonic separation apparatus amongst the cyclones and clustered into a generally circular array. Air flow can be directed to the axial input of the fan and expelled from the tangential output of the fan by a baffle. The high speed motor and fan may be located on the periphery of the circular array in which case air flow from the fan may be expelled from one side of the circular array and directed out of the cyclonic separating apparatus. The high speed motor and fan may be nested near, or at, the middle of the circular array in which case air flow from the fan may be expelled from one end of the circular array and directed out of the cyclonic separating apparatus. If the high speed motor and fan were nested in a circular array of cyclones inclined with respect to a central axis, like, for example, a modified version of the cyclones disclosed by GB 2 440 110 A, then air flow from the fan may be expelled from one end of the circular array of cyclones or through gaps between the cyclones.