Heaters

The present invention relates to heaters for heating, in particular for cooking liquids, e.g. water. Examples of such heaters are described in US 457 5615 A ​​and DE 3521989 A1.

[0002] Many methods are known to provide hot or boiling water for home users. Traditionally, electric kettles or jugs are used to cook a certain amount of water, for example to make hot drinks.

[0003] Very recently, products have appeared on the market that provide very fast delivery of a small amount of hot water. Rather than steady heating water masses, they are based on heating the flow, which heats the water when it passes through a narrow channel with a thick-film element printed on one side. However, this technology has significant disadvantages, one of the biggest is that it cannot be used for boiling water as will be explained below.

[0004] When boiling water in a conventional kettle, a large amount of water has substantially the same temperature, which gradually increases during the heating process. Only the boundary layer near the heated surface is significantly warmer. The heat is transferred from the heated surface to the boundary layer by conduction and at least initially from the boundary layer to mass by convection. In heaters with a high surface temperature, water in the boundary layer can reach a temperature of 100⁰ C and boils while the mass of water is relatively cool. Plug steam bubbles that increase in water initially condense and fall due to contact with the cooled mass of water.

[0005] As heating continues, steam bubbles that are lighter than the surrounding water rise from the surface of the heater. Because the bubbles rise, their thermal conductivity to cooler, surrounding water, and as a result of condensation, eventually cause the bubbles to fall. However, since the mass of water is approaching boiling point, this does not cause the condensation bubbles to completely condense, and they rise to the surface and release, which is usually a sign that the water is boiling. In practice, the temperature of the mass of water in this state will not actually have a temperature of 100⁰ C. Usually, home-made jugs and kettles will keep the "rolling boiling" for many seconds, which allows the mass of aqueous liquid to reach a temperature close to 100 in a uniform manner⁰C, although it will never reach it completely, and moreover, the actual boiling point depends on other factors such as atmospheric pressure and the presence of substances dissolved in water.

[0006] The flow heater by comparison has the advantage of being able to heat water on demand and for as long as is necessary to supply a certain amount of water. However, consumers expect a start-up in time that will manifest itself immediately of no more than a few seconds. In the context of small home products, the size of the power supply is related to that achieved at the outputs from the wall sockets (typically 1500W to 3000W) and cannot be

Given the constant set conditions, the flow rate of the water stream will be matched to the useful power of the heater according to the basic thermodynamic principles (for 3kW of the preheater, the flow rate is about 0.5 l / min to 1 l / min, which provides water at a temperature from close to boiling to fall to about 65⁰C). The heater type and heat exchanger mechanism have little effect.

[0007] When designing flow heaters with very fast start-up, it is important to minimize the thermal mass of the heater itself and the temperature to which heating will be required. It is also important to maximize the contact area between the water and the water heater. These requirements have been addressed to the latest state of the art by the use of a thick-film heating heater linked through an intermediate electrical insulating layer to a stainless steel heat exchanger. The heat exchanger is designed with a set of chambers facing the heater to maximize the contact area. However, the Applicant has realized that attention must be paid to the distribution of water flow over the surface of the heater. If any water compartment in contact with the surface is allowed to stand still, it will boil quickly, forming a steam shield. The steam shield will no longer provide cooling to the surface of the element. The result is a sudden location of the surface heating, and destruction, usually of the insulation between the heating path and the heating surface of the substrate. In order to avoid this, the water is therefore forced to flow in a winding narrow channel to avoid places of stillness.

[0008] The applicant has also appreciated another emerging problem associated with the use of a narrow water channel. As the water is approaching the end of heating, it will be the highest temperature - typically 85⁰C. The water channel, although small, however still consists of the boundary layer and with the water mass channel; water in the boundary layer will often boil, producing steam bubbles. In this configuration, water vapor bubbles appearing in a very small channel do not allow heat transfer by conduction and condensation, because they cannot reveal their surface area to the surrounding water, instead the forming bubbles will simply press the remaining water in front of them. It can be seen that if these bubbles appear, for example 80% of the way along the channel, then as a result all water in at least 20% of the channel will be emitted rapidly. From the user, to the prospect of splashing "a fragment of the undesirable effect of" water passing the end can often lead to premature failure of the element. Also, in the user's opinion, most of the emitted water will be significantly below boiling.

The use of heater means can be

In fact [0009] Problems to locate splashing foci, these heaters not used to provide boiling water are the biggest problems with targeting the water temperature.

As a result, in practice, the flow heaters have been limited to devices requiring water below the boiling point, such as shower heaters and hot water dispensers that do not boil water.

[0010] From the point of view of a first aspect, the present invention provides a heater for heating a boiling liquid, comprising a heating element, a first heating region heated by said heating element to heat the liquid flowing through it to a temperature below boiling, and a second heating region to heat said liquid to reflux wherein said second region has means for allowing the steam generated by said boiling liquid to exit from it separately from the heated water outlet.

Thus, it will be apparent to those skilled in the art that, according to the invention, standard flow heaters can be modified by providing a second heating region that allows steam to escape from the water surface without pumping heated water - i.e., the phenomenon of splashing is reduced or avoided him. In addition, to facilitate the escape of steam, the surface of the heater is allowed to remain embedded in water, and thus localized hot spot is maintained. Standard flow heaters may be those in which there is a temperature gradient along the direction of flow during use. While in the preferred embodiment, the invention allows the production of boiling water, water only in the second region boils; it is not necessary to heat the entire contents of the preheater before boiling water is produced, as could be the case with a kettle or other "series" of preheaters. For example, cold water at 20⁰C preheated to 90⁰C in the first region will have an average temperature of only 55⁰C.

[0012] According to the invention, the second heating region continues heating the water from the temperature at which it leaves the first region (for example, the first region is similar to a traditional flow heater). A separate heater could be used for this purpose. In a set of preferred embodiments, however, a single heater is provided providing balance that extends over the second heating region.

[0013] The form of transition between the first and second heating areas is not considered essential to the invention and various possibilities have been envisaged. For example, the first heating region could expand beyond its end to form a second heating region. In this case, the transition point between the first and second heating regions could be defined relatively arbitrarily. For example, the passage could be defined taking into account the dimensions of the channel through which the flowing fluid is heated, such as the cross-sectional point at which the expansion of the channel begins or at which it has been completely widened or a point halfway. Alternatively, the determination of the linear flow velocity conditions could be gradual, for example where the linear flow velocity is reduced to half the speed in the first region. Functionally, the transition will occur when water vapor bubbles can escape from the surface of the fluid without displacing the remaining fluid.

[0014] In the first region, the controlled parameter is water speed (achieving a balance between good heat transfer at high speed and acceptable hydraulic pressure drop) while in the second region the controlled parameter is the water level, achieving between heat transfer through the heater covers, and minimizing water volume by ensuring that the water level is as low as possible. Minimizing the volume of water in the first and second regions maintains the windshield starting time.

[0015] The heating element for the first region may take any convenient form. In one set of embodiments, the heating element is located outside the channel or conduit forming the first heating region. The element may take the form of a so-called thick-layer printed element. These components are conventionally flat, but can be made from non-flat substrates. Alternatively, they may contain a sheathed resistance element of the heating element with or without indirect heating of the metal in the form of a sheet metal spacer as is commonly used in so-called "underneath" heaters for home kettles. The advantage of using the element outside the channel is that it is relatively easy to manufacture and allows overheating protection to be provided in close thermal contact with the element to turn off the element in the event that it will be supplied with energy without water in the channel.

[0016] In another set of embodiments, the immersion heater element is disposed within the channel or conduit forming the first heating region.

Accordingly, in preferred embodiments, the first heating region includes a liquid transfer channel having a sheathed heating element disposed therein for heating the liquid. The element may be mounted to or may be in contact with the channel wall, although in a set of preferred embodiments it is positioned within the channel so that fluid is in contact with it all the way around its periphery. In a set of preferred embodiments, the first heating region preferably includes a tubular jacket around the heating element, so that fluid can flow between the element and the jacket. This is advantageous because it provides a larger contact area between the fluid and the heater surface and also helps to minimize the tendency to splash as some bubbles occur because individual bubbles cannot occupy the complete cross-section of the channel. During normal operation, i.e. at a water temperature not exceeding 85⁰C or 90⁰C, then the bubbles forming will be the result of the high speed of water in the remaining stream, improving heat transfer and minimizing the likelihood of circumferential bubble growth.

[0017] The coat can be adapted in the profile to the element

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block form having a channel defined therein for accommodating the element and the liquid around it.

[0018] Any useful material can be used for the jacket. In one set of preferred embodiments, the mantle comprises stainless steel. This gives an overall heating force and in particular ensures that it is tolerant to overheating, for example when operating without contact with liquid. The coat should have a perfectly low thermal mass and in the case of a stainless steel coat it means that in a preferred embodiment it should be relatively thin. In the case where a stainless steel or other metal jacket is provided, a thickness of less than 0.7 mm, more preferably approximately 0.5-0.6 mm, is preferred.

The applicant has found, in contrast to the prevailing state of the art, that in reality standard immersed sheathed elements (for example, with a diameter of 6.6 mm operating at 35 W / cm²) with a thin stainless steel jacket as outlined above, in fact has a reduced thermal mass than a typical corresponding system with a thick-layer heating element.

[0019] Preferably the heating element has a circular cross section. Preferably the channel or jacket (or at least its inner wall) has a circular cross-section. In the case where the cross-section of the heating element is not circular, the cross-section of the jacket or duct (or at least its inner wall) is preferably of the same shape.

[0020] In the case where the heating element is surrounded by liquid, the fixing end of the element and the outer pipe may remain in concentric relations between the pipes, however, advantages have been found in some embodiments in providing spacers between the element and the channel or jacket to assist in providing, that the right distance is kept between them. The distance means can be provided by a separate, useful heat resistance, coaxial insert. More conveniently, however, it is provided by useful features formed on one or both elements or the jacket.

[0021] In another convenient set of embodiments, for example, the jacket may be cut when viewed from the outside to form projections that contact the element to maintain a distance between the element and the rest of the jacket, while fluid flow over most of the surface of the element is still allowed. . The projections may be discontinuous in the longitudinal direction, but at the same time they may be in the form of continuous longitudinal ribs, effectively forming a plurality of discontinuous channels separated around the perimeter of the element. It is obvious that the protrusions can be on the element as well as or instead of on the coat.

[0022] It is important that it is possible to practice the desired control over the operation of the flow heaters according to the invention. One aspect of this is protection against severe overheating of the heater when it accidentally works without fluid. There are of course many ways that can be implemented. In a particularly convenient embodiment, a shielded, submerged heating element is utilized, part of which is connected to a metal "head" plate to create a heat return in exactly the same way as is well known in traditional immersed kettle elements. The benefit of this is that it allows submerged components to be inspected, such as the applicant's extremely popular and successful R7 control series giving both first and second protection of overheating. Details of such control are given in document GB-A2181598. A further advantage is that such control is used to ensure the electrical contact of the elements either directly or indirectly.

[0023] Preferably, protection against overheating is provided in the second region in which water can boil. This is addressed to a fundamental problem with providing protection against overheating when dry switched on in flow heaters containing a shielded heating element located in the channel and surrounded by liquid; the presence of the channel physically protects the sensor in correct contact with the element.

[0024] The thermal sensor may, for example, be a thermistor, a thermo connector or other electronic sensor, or it may be a thermomechanical sensor such as a shape-remembering metal starter or a bimetallic starter.

It must be in physical contact, but preferably good thermal contact is achieved through the thermally conductive wall of the second region, for example the traditional head and the heat return assembly described above.

[0025] Preferably the part of the element which is in good thermal contact with the thermal sensor is higher than the rest of the heated part of the element.

[0026] Additionally or alternatively, it may be desirable to measure the temperature of the fluid in / or from the heater. This can, for example, help detect overheating or it can be used as part of the feedback of the control system to control the flow of water passing through the heater. When boiling water is required, it is advantageous to be able to practice control over the flow stream because the optimal flow rate is determined by the precise power of the heater, the performance of the pump used, the supply voltage and the surrounding temperature of the incoming water. The first two of these factors are subject to manufacturing tolerance while the latter two may change during use.

[0027] Furthermore, although the invention advantageously allows the supply of boiling water from a flow heater, it may be desirable in some circumstances to provide water at a lower temperature or to allow the user to change the temperature. In fact, in one preferred embodiment, means are provided for controlling the temperature of the liquid supplied by the preheater.

[0028] The applicant has appreciated that the liquid outlet temperature is a function of both the heater power and the flow rate. parameters can be embodiments of these two

In a set of favorable temperature control

Accordingly, both variables. the means comprise means for changing the fluid flow stream through the preheater. For example, for a typical 3 Kilowatt heating element, the applicant has found that the water supply can have approximately 100⁰C (assuming its start at an approximate temperature

17⁰C) if the flow rate through the heater is approximately 520 ml per minute. If the flow rate is further reduced to approximately 475 mL / min, additional energy is supplied to the water to counteract energy loss through the steam that escapes without conducting heat to the surrounding water. As a result, we get the so-called rolling boiling, in which the mass of water at its nominal boiling point is ensured (typically 100⁰C). Alternatively, if the flow rate increases to 900 ml per min, water is supplied at a temperature of about 65⁰C.

[0029] The initiation of fluid flow (for example by starting the pump or opening the valve) can take place as soon as the heating element is powered. However, in preferred embodiments, the preheater is positioned to initiate water flow after the heating element's power supply has been delayed. Applicant has appreciated that by introducing the intended delay it will be ensured that substantially all fluid will be dispensed at the desired temperature - that is, there is no initial rise of cold fluid at the beginning of the dispensing operation. The delay can be set, but it is preferable to set it as a function of fluid temperature in the heater, so if the fluid in the heater is hot the delay is reduced, potentially below zero (without delay) or even negative - that is, the pump may start before the heater it will start working, for example, if the system is restarted shortly after the switch-on time and the desired temperature is selected below.

[0030] Similarly, the flow may be turned off simultaneously with the heating element, but in a set of preferred embodiments the heating element is turned off before the flow stops. This allows heat to accumulate in the element and other components that will be partially recovered in heated water. This is not only associated with greater energy efficiency, but means that the heater can be used more quickly, soon after the cold liquid is dispensed.

[0031] The length of time for which the liquid has been dispensed can be determined or identified - for example, as long as the user presses the button. In a set of preferred embodiments, the fluid is dispensed over its useful life. The time can be set directly, but it is preferable to determine by means of the dispensing volume control, in which case the dispensing time is also a function of the flow stream, which may in turn be a function of the dispensing temperature as explained above. Having a metered liquid at a predetermined time it is advantageous to allow the heating element to be rotated or closed towards the end of the metering operation to recover the accumulated heat, as outlined above.

[0032] The Applicant has appreciated that when the liquid supply can be in / near boiling, it is very difficult to measure its temperature accurately because the fluid in the second region will be moving turbulently and will contain a lot of steam bubbles, so any point of the temperature sensor one that the thermistor will try to give incorrect and widely varying results. However, the Applicant has invented a system that allows a more accurate and permanent determination of the fluid outlet temperature.

[0033] According to a preferred embodiment of the invention, the temperature reading means are arranged in the first heating region to determine the fluid outlet temperature. In this way, according to these preferred embodiments, the liquid temperature measurement is made before it is finally dispensed, rather than the actual measurement of the fluid outlet temperature. This is due to the applicant's realization that there is a strong correlation between the fluid temperature at a known point in the first heating region and the exit temperature. Assuming that both liquid performance and heating power of the heating element after the measurement point are known, the exit temperature can be calculated. The advantage of measuring the temperature in the first region is that because the liquid is not or substantially not boiling in that region, a more accurate temperature measurement can be made.

[0034] Accurate knowledge of the temperature of the water in the second region (e.g. obtained by measuring temperature in the first region) is beneficial to the device in many ways. is to allow water outlet temperature variation. However, it is also acceptable to take into account the situation of imbalance arising from previous operation of the device. For example, if the machine is used for dispensing boiling water and a subsequent request for control permission The first direction of the user is to use a water cooler, the water jet may start earlier relative to stimulation of heating, or it may not even be necessary to stimulate heating at all depending on how a lot of the liquid has been cooled.

[0035] When the temperature is measured in the first region, the applicant has realized that it is possible in some circumstances to encourage flow components to spin around the longitudinal axis of the channel or conduit because this provides a more reliable measurement of a single temperature point. The possibility of measuring temperature is advantageous in terms of costs in relation to the required use of many sensors. In one set of preferred embodiments, the channel or conduit includes a first region comprising an inlet arranged to introduce fluid into it along the displacement direction from the central axis of the channel or conduit to provide the desired spin, which promotes mixing of liquid within the channel, and hence even greater distribution temperature. For example, the inlet may be located to introduce fluid with a tangential flow component.

[0036] In other sets of the preferred embodiment, without being mutually excluded, the channel or conduit in the first region is configured to promote the swirling flow. There are many possible ways by which this can be achieved. In subsets of these examples, the inner surface of one or more channel walls is / are provided with spiral means. For example, the surface may be provided with ribs, grooves, or other protrusion or recess patterns that encourage flow to spin. These means may extend either along part of the path or along the entire path around the perimeter. Spiral means may instead be on the outside to introduce a flow shaping element.

internal surface and may extend over all or part of the road along the length of the channel. It is not necessary for these measures to be continuous; they may contain a number of tumors or other protrusions.

[0037] In the event that the channel is provided with an element immersed inside the channel, additionally provided or with the surface of the element. Another alternative is, again without mutual exclusion with the option cited above, is to the channel for the independent. In particular in a convenient set of embodiments, such a flow forming element comprises a coiled wire around an encapsulated heating element immersed in the channel. This is not only economical in production, but also relative to direct fusion. A similar alternative may include a resilient coil wrapped around an element that is installed during manufacture then released so that it expands relative to the inner surface of the channel wall. In another case, the thickness of the wire is preferably less than the width of the gap between the surface of the element and the wall of the channel; in other words, the wire does not define separate individual spiral channels, but rather encourages the flow of the swirling stream causing the swirling motion of the liquid boundary layer. In some embodiments, the wire thickness is less than the gap width.

[0038] According to the invention, the fluid stream can be activated by a hydraulic pressure achieved by placing the fluid reservoir above the outlet and using a valve or flap. Preferably, however, a pump is provided to drive the fluid through a flow heater. Any useful pump may be used, but in a set of preferred embodiments, the pump is a centrifugal pump. These are smaller and quieter than piston pumps, which are typically started by an AC supply obtained from the supply network, previously used because of their relative tolerance for variations in pressure drop; this is why the output of the flow stream remains substantially constant over a wide pressure range. In contrast, for centrifugal pumps, the flow rate is strongly dependent on the pressure drop. This is a problem in applications such as free-standing hot water dispensers that are supplied from a fixed tank, because the inlet pressure and the same flow rate at the outlet will depend on the water level in the tank. This problem can be presented in the form of feedback control for adjusting the speed of the pump. However, the applicant has invented a further setting that is particularly suitable for use when we have a water tank as it is preferred.

[0039] Thus, according to a set of preferred embodiments, there is provided an apparatus comprising a preheater, a pump supplying fluid to the described preheater reservoir for collecting fluid, the apparatus further comprises an intermediate holding chamber between the reservoir and the supporting level.

a pump and means filling the chamber from the reservoir to a predetermined [0040] According to such preferred embodiments, the pump does not drive the water fluid directly from the reservoir, but rather from the intermediate support chamber. Since it has been filled to a predetermined level, the head pressure at the pump inlet will be known and thus can be calculated into factors such as pump speed, flow stream and the like. Even if the water level in the intermediate support chamber can be reduced during dispensing, pressure changes are above the smallest range.

[0041] Another advantage of this arrangement is the means by which the fluid can be driven by the pump, are of a faster value than it may be desirable for the liquid to leave the tank. This is particularly suitable when the water filter cartridge is used at the outlet of the tank, because it is more effective when the flow stream through it is deliberately choked - for example, as in Aqua Optima (RTM) applicant filters. For example, a typical flow rate is approximately 400mL / min while as considered above, under some conditions a flow rate of up to 900mL / min may be desirable.

[0042] Preferably, the tank is higher than the intermediate support chamber, and is filled by gravity. [0043] In some embodiments, the predetermined level may be full - that is, the intermediate support chamber is simply filled to its capacity. In other embodiments, the predetermined level corresponds to an intermediate support chamber that is only partially filled. Various ways of partially filling the intermediate support chamber only to a predetermined level can be envisaged, taking into account electronic level sensors or a float valve. In a set of preferred embodiments, the means for filling the intermediate support chamber include a ventilation tube that connects to the attached air space above the fluid in the tank and extends down to a predetermined level in the support chamber, with the tank sealed against leakage of air in it above the liquid in addition to the tube means ventilation. Through this arrangement, the support chamber will be filled, dispensing air through the ventilation pipe until the fluid level reaches the bottom of the ventilation pipe. At this point, no more air will enter the intermediate support chamber, creating a partial vacuum in the reservoir that secures further air outflow into the intermediate support chamber.

[0044] There are many possible settings for dispensing the heated fluid from the second region of the invention. One possibility could be an uncomplicated valve or flap to allow drainage of the water of the second region. The problem with such a system is that the discharge through such a valve or flap would be precisely coordinated with the influence from the pump. For example, if the outflow stream is even slightly larger than the inflow stream (or if the outflow begins because of it too early), the heater will operate as dry. If the outflow stream is slightly lower than the outflow in the chamber, overflow will occur, or if the water level rises, boiling will occur as a result of boiling. This will happen because when the generated water vapor bubbles on the surface have to move through the vertical mass of water, it will tear the water droplets and move them at a higher speed to the surface. The flow in question in question can begin and end at an irregular time, and is constantly changing in response to all input parameters - desired output temperature, water inlet temperature, voltage fluctuations and actual fluctuations that can occur in any closed circuit control system. Difficulties in controlling the impact will further increase by the need, at start-up, to secure the discharge, until a sufficient amount of water has been introduced to fill the system to its intended operating level.

[0045] In a set of preferred embodiments, means are therefore provided for allowing an automatic outflow of fluid after the fluid has reached a predetermined level. This ensures that different liquid sizes will be fixed and thus can ensure that the surface of the heater is covered sufficiently to protect against overheating. This function could be achieved electronically or by using a float but preferably an overflow partition is provided so that the liquid flows over the overflow partition and out of the second region when the water level in the region reaches a predetermined height (defined height of the overflow partition).

[0046] The Applicant has appreciated that such a system even allows that a sufficiently large surface of the heater remains covered with a sufficiently thin layer of fluid and thus avoids overheating.

[0047] In all examples of the invention, the heated or boiling fluid existing in the heating chamber could be dispensed directly into the user's tank, i.e. through the spout, or could be transferred to another part of the device for further processing.

[0048] According to the invention, the steam has the possibility of separately escaping from the second region from the heated fluid. Water vapor can normally be ventilated directly into the atmosphere, although it is preferable to direct it to the part of the device outside the user. It can, for example, be ventilated to the back of the tool. In other examples, the steam may be captured and condensed into a suitable trap, drip pan or the like. It could be a special drain pan or, more conveniently, a drain pan could be used under the spout. In all these cases, it is preferred in some embodiments of the invention that the steam path between the second region and the atmosphere is sufficiently limited to ensure, through their use, an increase in pressure difference between 0.1 and 1 bar, preferably between 0.2 bar and 0.5 bar.

By allowing the pressure in the second region to slightly increase during use compared to the atmosphere, the boiling point of water or other liquid increases, which helps to increase the temperature of the fluid actually received in the user's tank.

[0049] The preferred embodiment will now be described, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a perspective view of the built-in boiling water dispensing device of the invention;

Fig. 2 is a partially cut-away view of the device showing its main components;

Fig. 3 is a cross-sectional view through the water tank and other components;

Fig. 4 is a horizontal cross-section through the water inlet end block and flow heater pipe.

Fig. 5 is a vertical cross section showing the interior of one of the flow heaters;

Fig. 6 is an exploded view of the head and the control assembly;

Fig. 7 is a rear view and exploded into elements of the head and control assembly;

Fig. 8 is a view of the boiling chamber with the head element removed for clarity;

Fig. 9 is a view similar to Fig. 8 of a variant of the boiling chamber;

Fig. 10 is a partial schematic plan view and an enlarged cross-sectional view of the element and the jacket according to another embodiment of the invention;

Fig. 11 is an enlarged view of the inlet manifold of another embodiment of the invention; Fig. 12 is an isolated view of a heating element for use in further embodiments of the invention;

Fig. 13 is a greatly enlarged cross-section through the heat pipe of an example using the element with

Figure 12;

Figures 14 and 15 are perspective views of an alternative flow heater of the invention;

Fig. 16 is a cross-sectional view of the heater part with

Fig. 14 and 15.

[0050] Fig. 1 shows an embodiment of the invention that can be used to dispense boiling water on demand into a cup 2 to produce a hot drink. The temperature can be adjusted by turning knob 4. The dosing temperature can be changed from 65⁰C until just boiling and otherwise to "spin boiling" (rolling boil), where more energy is transferred to the water to ensure the total volume of fully boiling. The amount of water to be dispensed is controlled by a second knob (not shown). The steam outlet 6 is also visible. On the upper part of the main part of the device there is a water tank 8, which must be filled periodically by the user.

[0051] Fig. 2 shows some of the main components of the device with other parts omitted for clarity. From here you can see the water tank 8, from which extends downwardly the outlet pipe 10 connected to the side inlet of the low voltage centrifugal pump 12. The lateral outlet of the pump 12 is connected via a pipe 14 to a water-separating equalizing block 16 that divides the water flowing into the block between two parallel flow heating sections 18, 20 which will be explained in detail below with reference to Figs. 4 and 5.

[0052] Behind the end of the flow heating part 18.20 is the boiling area 22. It is formed by a deep-pressed stainless steel cup 23 fitted to the approximately circular stainless steel head element 54 (see Fig. 3.5 to 7). The boiling area 22 has an outlet spout 24 projecting downwardly therefrom for dispensing heated water into a user cup 2. [0053] At least one part of the flow heater 18.20 has a small hole 70 drilled in the side wall of its outer casing near the boiling area to position the thermistor. Alternatively it can be placed outside the housing.

[0054] The cross section in Fig. 3 shows the water tank 8. From here it can be seen that the water tank 8 has a circular inside base opening 26, which is intended to receive the water filter, for example the Aqua water filter shown very marked with the number 28.

Optima of the applicant. This is schematically through the ingredients

The water filter 28 has a separated outlet (typically 4 mm) that has additional benefits in the present context, and which is too small to allow air to pass into the filter when water is in the filter; there were no cases that air bubbles could enter the filter and the tank allows a continuous flow of water. The lower part of the water filter 28 is received inside another intermediate support chamber 30 in which the outlet is connected to the pipe 10, which connects it to the pump 12.

[0055] The vertical pipe 32 extends from the top of the supporting chamber 30 to the main water tank 8 and ends just inside the part with the notches 34 at the top of the water tank 8. This allows pressure equalization between the holding chamber 30 and the water tank 8.

[0056] Fig. 4 shows a horizontal cross section through a separating equalizer block and two parallel flow heaters 18.20. The pump outlet side (not shown here) is connected through a pipe 14 to a vertical inlet channel 36 in the equalization block 16. This connects within the block to two parallel-extending pipes 38 which are open to the corresponding enlarged section of the circular diameter of the opening of the cylindrical chambers 40.42 at right angles to the transverse pipes 38. Cylindrical chambers 40,42 receive respectively the ends of two sections 18,20 flow heaters. As you can see now, each section 18.20 of the flow preheater includes an outer jacket 44.46 and the length of the sheathed bath heating element 48, which, although not shown, includes a stainless steel sheath and coiled resistive wire wrapped in insulating magnesium oxide powder . The ends of the 50.52 cold dive element emerge through the holes located at the rear of the equalizer block 16. [0057] The two sleeves 44, 46 of the flow heater have wider diameters than the corresponding heating element 48 and thus define between them the corresponding annular channel for each section of the flow heater

18.20. As can be seen from the cross-sectional side, the sleeves 44, 46 form a sealing connection with the front end of the circular channels 40, 42 in block 16, but they end soon at the point of these channels, where they meet the transverse channels 38 so that the above-mentioned channel the annular in each of the flow heaters 18.20 is open to cylindrical chambers 40.42 formed within the equalization block 16, while the housing element 48 extends through the block and is sealed to it. As a result, a fluid path is formed from the block inlet 36, through transverse channels 38 and cylindrical chambers 40.42, into the annular channels of the two flow heaters 18.20.

[0058] Fig. 5 shows the total length of the flow heaters 18.20. From here it can be seen that its respective outer sleeves 44, 46 are sealed at other ends to the boiling chamber 22. The heating element 48 extends into the boiling chamber 22 and is bent round to form two longitudinal arms that respectively form part of the two flow heaters 18.20. This is more evident in Figures 6 and 8.

[0059] As can be seen in Figs. 5 and 6, the bent part of the element 48 is soldered to the head plate 54 of the submerged element, which closely resembles the element head plates seen in the traditional submerged element of kettles. This arrangement is known as re-heat, and as can be seen in Fig. 7, the other side of the head plate 54 is formed of a semi-circular recess 56 for placing a latch-like bimetallic actuator 57 of the control module 58 of the standard submerged element. Fig. 7 shows copper strip 60 also extending from the heat recovery device, which supports the nylon thermal fuse 59 of the control unit 58 to provide protection for the second level of overheating. Alternatively, in a nickel-plated copper head of a submerged element, a copper strip is not required as is also well known in the art.

[0060] It would be appreciated by the skilled artisan looking at Fig. 7 that the cool parts of the element 50,52 do not protrude through the head element 54, as would be conventional for a submerged kettle element, but rather they protrude through the separating compensation block 16 (omitted for clarity in Fig. 7). Instead, the two artificially cooled terminals y 62, 64 protrude through the head 54 of the element to create electrical contact with the control unit 58 and are in turn connected by means of thin wire means (not shown) to properly cooled ends 50.52. This allows the use of the standard 58 control unit without modification, which is a major cost saving compared to the redesign and production of the new control unit. The element head is provided in the form of three threaded pins 66 for the control unit

58.

[0061] The interior of the boiling chamber 22 is best seen in the view in Fig. 8, in which the head 54 of the element is removed. From here, it can be seen that the chamber 22 is of a widely squat cylindrical shape, although its internal volume is limited by two tips 62.64 artificially cooled, the bent part of the element 48 and by a vertically protruding bead 66, which has a central opening 68 in connection with the outer spout 24 . The height of the bead 66 is at an approximate level with / or slightly at the level of the top of the tubular element 48. Given the depth of the meniscus, it has been ensured that the element 48 remains just covered in water, preventing overheating during normal use. An opening 72 is formed at the top of the wall of the cup 23 forming the boiling chamber 22 to provide a steam outlet that communicates with the steam outlet 6 at the top of the device.

[0062] A variation of this embodiment is shown in Fig. 9. In this embodiment, an additional U-shaped partition 69 above the bead 66 is provided with its open end facing away from the ends of the annular heating channels. This prevents the ascent from the water channels from flowing directly through outlet 68, thereby ensuring proper heating to boiling.

[0063] The operation of the device will now be described. First, the user fills the water tank 8 with water by removing it, inverting it, removing the water filter 28 and filling from above. The filter 28 is then replaced, the tank is inverted and then placed back on the device. Water immediately begins to pass through the water filter, inside it, at a predetermined rate by the restrictions of the water filter opening as is known. As the water passes through the filter 28, this begins to fill the connecting pipe 10 and then the lower supporting chamber 30, moving air through the ventilation pipe 32 into the sealed space of the water tank head 8. When the water level in the support chamber reaches the bottom of the ventilation pipe, the air may no longer be expelled from the chamber, which stops the flow of water. [0064] When the user wishes to dispense water, he / he sets the required temperature on the first knob 4 and then rotates the second knob (not shown) turning it from the off position to the desired volume. Initially, a control circuit (not shown) actuates the heating element 48. After one or two seconds of delay (depending on the temperature of the water contained in the heater), the pump 12 starts to pump water from the lower chamber 30 through pipes 10 and 14 to the distribution equalizing block 16. In other embodiments, the pump may start before the heater.

[0065] Since the water passes through the channels 38 in the balance block, the flow is balanced between the left and right channels. The opening of these channels 38 is selected such that the pressure drop through these sections is greater than for the rest of the entire hydraulic system. This is very important in maintaining proper flow (downward) behind annular channels 18, 20. For example, if slight restrictions arise in one channel 18.20 and not in the other, this will have little effect on the flow stream, since a dominant pressure drop occurs in the equalizing channels 38. A pressure drop ratio of 10: 1 provides the required effect. For example, if the pressure drops in 18.20 tube heaters, which is offset by a 40 mm water drop, the pressure falling in the equalizing channels 38 could be balanced to a 400 mm drop.

[0066] As soon as the water is pumped into the separation block 16, it is pumped through it and down the annular channels of each of the two flow heaters 18.20 between the heating element 48 and the corresponding stainless steel outer jackets 44.46. This heats the water quickly because it passes from the ambient temperature (of the order of 20⁰ C) in block 16 separating to about 85⁰C at the ends after the flow heaters 18.20.

[0067] The water temperature is monitored by a thermistor protruding into the holes 70 on the sides of the flow heaters 18.20 near the boiling chamber 22.

The temperature can be monitored accurately and reliably because the water does not boil and therefore there is no significant amount of water vapor bubbles within it.

[0068] The water then goes beyond the flow heaters 18.20 and into the boiling chamber 22 where it begins to fill this chamber through which it covers the curved part of the element 48 that projects into the boiling chamber.

The curved part of the heating element continues to heat the water in the boiling chamber, now a significant number of bubbles are created, which break the surface of the water tank in the chamber and evaporate in the form of steam. However, steam can easily escape from the boiling chamber by means of a steam outlet 72 at its top.

[0069] Referring in particular to Fig. 8, it can be seen that because the water level in the boiling chamber 22 increases the level from and above the protruding bead 66, it will start pouring through holes 68 and through the spout outlet 24 and into the user's cup 2. The pumped flow speed and power of the element 48 are adjusted such that during the time the water leaves the boiling chamber through the holes 68 and the spout 24 there is active boiling. This contains "surplus" uptake energy compared to energy that could theoretically be required to increase the water temperature to 100⁰C to ensure the cooking process and because the water reaches a true boiling point. The height of the bead 66 is chosen to ensure that the curved element 48 remains in the water regardless of the flow rate.

[0070] Boiling of the dispensing water continues until the volume set by the user is dispensed. At this point, pump 12 is turned off. To increase the energy efficiency of the device, the heating element 48 is turned off for about 2 seconds. before switching off the pump. There is enough accumulated energy in the element and other elements to ensure that the water boils.

[0071] Referring to Fig. 3, it will be indicated that because of the intermediate support chamber 30 from which water is drawn, the water can be led in a larger stream than that passing through the filter 28. The capacity of chamber 30 is designed so that, given the extent to which it is topped up while the pump is running, a large ordinary cup can be filled with water before the flow rate approaches too low (i.e. limited by the flow rate through the filter ) and so the device will close to protect element 48 from overheating. For example, assuming that within 15 seconds 250 ml of water (equivalent to too large a cup) will be dispensed at 65⁰C, only 100 ml will flow through a typical Aqua Optima filter at this time. However, by providing an intermediate support chamber only 150 ml so that the large cup can be safely filled without overheating.

[0072] It will also be indicated that the intermediate support chamber 30 indicating differences in water pressure levels opening the pump 12 at least initially is known, which means that a known flow can be achieved even by using a suitably inexpensive and quiet centrifugal pump. Of course, it is recommended to refill the chamber with water from tank 8.

[0073] If the water tank 8 runs dry, the heating element 48 will start overheating. However, this can be captured by a temperature sensor protruding through the opening 70 to the flow heaters 18.20. Since the spare element in the form of a bimetallic actuator on the control unit will register overheating of the element 48 and therefore there will be a flip in its reverse curvature to open the set of contacts in the control unit in a known manner. A secondary back-up protection is provided in the form of a thermal fuse of control unit 58, which is also very well known. The element is arranged to ensure that in the case of dry cooking or dry opening, the warm return part, soldered to the head 53, will become dry. This is achieved by ensuring that the flow in the twin pipes 18.20 of the first heater is balanced in all conditions (as previously explained) and also by ensuring that the return heat is slightly higher than the heat of the resting element 48 and the surrounding pipes 18.20 slightly inclined . This has further benefits, starting with a dry state, ensuring that the pipes 18, 20 are freely vented, and that the flowing water can easily push the initial volume of air in its front and out of the boiling chamber 22 without the air plug.

[0074] If the user wishes to dispense water at a low temperature, he or she can use the knob 4 located on top of the device, so that the temperature that causes the operation to set the low pump 12 at high speeds and thus will give a higher water flow through the device, which will mean that it will be warmed to low temperature before dispensing. Again, having a known difference in pressure levels for the water opening the pump, this allows the flow to be started which will be achieved for calculating a given speed and hence the temperature of the discharged water can be calculated. The temperature sensors protruding into the holes 70 allow the temperature of the water which is dispensed through the spout outlet to be predictable based on the knowledge of the proportion of the heating element 48 which is in front of it and the proportion of the corresponding element 48 which is located behind it, i.e. the curved part in the chamber reflux. The sensor can also be used to introduce a relative delay between the operating pump and the switching element 48, depending on the ambient temperature of the water placed in the device (e.g. as a result of previous operation) taking into account the water temperature required by the user.

[0075] In this way it will be apparent that the embodiment described above provides the benefits of using flow heaters, i.e. capable of dispensing controllable volumes of water on demand, but with significant benefits in the form of the ability to provide boiling water. The boiling chamber and the separation of steam through the steam outlet 72 from the water outlet 68 is the key that allows splashing and the location of hot spots on the element.

[0076] Returning to Fig. 10. it shows two views of an assembly of a sheathed conventional heating element 80 placed inside a thin stainless steel jacket 82, so that water can flow between the outer surface of the element 80 and the inner surface of the jacket 82. In this respect, the positioning described above with reference to of the previous embodiment, in particular to Figs. 4 and 5. However, in this embodiment, the stainless steel cladding is formed with a series of identical spaces both longitudinal and peripheral that protrude on the inner surface that locally reduces the diameter of the cladding 82 sufficiently to touch the surface of the sheathed element 80. This holds the element 80 in a centrally coaxial position in a coat 82. Indentation 84 has no material effect on the water flow between element 80 and jacket 82, because water can still flow substantially all the way around the element

80.

[0077] In an embodiment of this embodiment, the recess 84 could connect longitudinally to form a continuous depression with the corresponding continuous ribs on the inner surface which could serve to centrally locate the element 80. In this variant, separate water flow channels could be defined between the respective ribs. Of course, the number and distribution of cavities / protrusions is not critical. In addition, projections could also be provided on the surface of the element and instead of. These features may have been used in other embodiments of the invention.

[0078] Fig. 11 shows a variant of the embodiment of the previous figures with a slightly different arrangement of water inlet to the annular channels formed between the respective outer jackets 44, 46 and the U-shaped submerged member 48. Instead of distributing equalizer block 16, as shown in Fig. 4, this embodiment has a manifold inlet having a common inlet 86 connected to two respective centrifugal manifolds 88, 90 that direct water to the respective inlet flanges 92.94. As can be seen, the collar 94 provides a sealing connection at one end to the respective outer sleeves 44.46 of the flow heaters section, and at the other end provides a sealing connection to the surface of the sheathed heating element 48. This can be determined because the cold parts 50.52 of the element extend inside the elements 48 far enough so that part of the heater surface in contact with the inlet seal is not heated. [0079] then it should be further noted that the manifold channels 88.90 connect respective inlet flanges 92.94 in the direction of displacement from its central axis. The result is that the water enters the inlet flanges 92.94 and goes down into the annular channels defined by the sleeves 44.46 which gives a movement component around the centrally located element 48, i.e. has a swirl component as well as a velocity component. Because such a flow pattern continues down the tube, the vortex movement will continue, which helps to mix water inside the tube and thereby promotes more temperature distribution along the tube which facilitates temperature measurement accuracy.

[0080] Figures 12 and 14 describe another embodiment of a heater that is intended to encourage water inside the channels of the annular flow heaters. Fig. 12 shows, in an isolated view, a shielded heater element 48 'similar to that of previous embodiments. The differences seen in this particular embodiment are that each of the two arms of the element has a thin wire 96.98 wrapped tightly around and in the shape of a screw. This is done during manufacture before fixing the arms of the element 48 'in respective sleeves 44.46 (see for example Fig. 4) to form annular channels along which water flows during use. Wires 96.98 are conventionally made of stainless steel and have a diameter of, for example, 0.6 mm, although the material, dimensions and slope of the wires can be selected for matching in particular to the application. Note that in this particular embodiment, at least the wire 96 that is wrapped around the element 48 is not wide enough to fill the annular channel formed completely between the element 48 and the outer sleeve 44 completely. It may, for example, be less than half the height of the channel for example, approximately one-third the height of the u channel. During use, the presence of wire 96.98 was used to force the water to vortex within the respective channels, as explained above, which ensure the separation of even greater peripheral temperature and temperature measurements. The layout shown in this example would be easier

Returning initially to substantially the section 100 embodiment in Fig. 12 used in conjunction with the inlet manifold system shown in Fig. 11, although this is not essential.

[0081] A further embodiment of the invention will be described with reference to Figs. 14 and 16 of Fig. 14, this example comprises a conventional flow heater that is approximately S shaped and a boiling region arrangement 102 located after the end of the flow heater section 100. [0082] In addition, with reference now to Fig. 15, it will be seen that the flow heater section 100 includes an approximately rectangular section of the tube 104 to which the sheathed heating element 106 is soldered from below. The water pipe 104 and element 106 are closely matched to themselves because they are bent to form an S-shape. The aluminum heat diffuser plate 108 is soldered on the bottom of the heating element 106 along various parts of its length. The heat diffuser plate 108 is located underneath it by three mounting beads 110 (only two of them are visible) which allows the mounting of the 112 control unit providing good thermo-mechanical protection against overheating in good thermal contact with the heat diffuser plate 108. The control element 112 described in these figures is U11 the Applicant's controller, which includes a pair of bimetallic actuators acting as latches that individually operate even in the event of overheating detected to open the appropriate set of contacts in order to interrupt the power supply to element 106. Of course, many other control systems both thermo-mechanical and / or electronic could be used for this purpose.

[0083] Returning now to Fig.16, details of the boiling area 102 can only be seen in cross-section. The boiling area cover 102 was also omitted for clarity.

[0084] Fig. 16 illustrates a cross-sectional view of the boiling area 102 with its cover removed for image clarity. A sealed entrance for the water pipe 104 and the heating element 106 is located before the end of the boiling area. As can be seen in the figure, the water pipe 104 ends properly inside the boiling area 102, while the element 106 extends through the length of the boiling area 102 and projects from the other end through another sealed gap. This allows an electrical connection to be made to the other cold end 114.

direction from condensed in [0085] It can be seen that the boiling area 102 has an overall longitudinal rectangular shape in which part of the element 106 occupies the bottom part within it, although water can pass all the way around it. The hole in the upper part on one side of the wall of the boiling area opens outwards to the steam vapor vent 116 which allows water vapor to ventilate into the atmosphere at the user or can be caught and the appropriate trap, drying quickly without spinning or the like. Near the end of the boiling area 102 there is a hot water outlet pipe 118 that extends vertically up to the boiling area to a height of just above the height of the element 106. The hot water outlet 118 is shifted to the side of the element 106 and is adapted to usefully extend the vertical wall.

[0086] The operation of the embodiment of the invention is similar to that previously described. First, the heating element 106 is energized by supplying electric current to the cold terminals 107, 114 via connectors (not shown) to the control unit 112. The water is also pumped by means of a pump from the tank (none of which is shown) to the end situated in front of the tubular channel 104. As explained in the context of previous embodiments, water pumping can begin with, before or after power is supplied to the component, depending on the intended use. Since the water flows through the pipe 104, it is heated by the element 106 until it appears in the boiling area 102 at a temperature of about 85⁰C. The water in the boiling area 102 is constantly heated by means of the element 106, during this time a localized boiling occurs on the surface of the element, causing a rapid increase of water movement and large bubbles of steam are generated. However, this steam can easily come out through the steam vent 116, although the hose-like steam path after the steam vent 116 can be provided so that the steam pressure inside the boiling area 102 is allowed to rise slightly above atmospheric pressure for example from 0.25 to 0.5 bar. This slightly raises the temperature of the water at which the water boils so that it maximizes.

[0087] When the water in the water outlet temperature is the boiling area reaches the level of the top of the hot water outlet pipe 118, it can then freely flow down the spout pipe of the device not shown and out into the user tank. Therefore, it will be seen that the vertical wall of the tubular outlet 118 that is inside the boiling area acts as an overflow to maintain a minimum water level inside the boiling area. Since this minimum water level is above the top of the element 106, it will be ensured that during normal operation the element 106 remains covered with water and thus no overheating can occur. However, if the water flows out of the tank or the device is turned off without any water contained in it, the temperature of the element 106 will increase very rapidly. This rapid temperature rise is transmitted through the aluminum diffuser plate 108 to the bimetallic actuator of the control unit 112, which causes them to operate, thereby opening their respective contacts and interrupting the power supply to the element 106. In this way, dangerous overheating and / or damage is protected. It should be noted that the tip of the element 106 inside the boiling area is not in direct thermal contact with the heating diffuser plate 108. This has the advantageous property in this situation, when the water in the device tank ends, because under these conditions the element wrapped on the pipe 104 will start overheating first, while part of the element 106 in the boiling area will remain immersed in the minimum water area determined by the overflow formed by the pipe 118 outlet Accordingly, even under these conditions, the power supply to the element may be abruptly interrupted to protect against overheating.

Strix Limited

Proxy:

EP 2 432 355 B1