An appliance

ES 2 355 441 T3

DESCRIPTION

The present invention relates to a ventilator apparatus. Particularly, though not exclusively, the present invention relates to a household fan, such as a tabletop fan, for creating air circulation and a draft of air in a room, an office or other domestic environment.

A variety of types of household fans are known. It is common for a conventional fan to include a single set of blades or blades mounted to rotate about an axis, and a drive apparatus mounted around the axis to rotate the set of blades. Household fans are available in a variety of sizes and diameters, for example, a ceiling fan can be at least 1m in diameter and is typically mounted suspended from the ceiling and positioned to provide downward flow of air and to fully cool a room.

Desktop fans, on the other hand, are often around 12 inches in diameter and are typically self-contained and portable. In standard tabletop fan mounts, the single set of blades is positioned close to the user and the rotation of the fan blades provides a forward flow of air stream in a room or part of a room, and towards the user. . Other types of fans can be attached to the floor or mounted on a wall. The movement and circulation of air creates a so-called cooling or breeze, and as a result, the user experiences a cooling effect as heat is dissipated by convection and evaporation. Fans such as the one disclosed in US $ 103,476 are suitable for placement on a table or desk. US 2,620,127 discloses a dual-purpose fan, suitable for use either mounted on a window or as a portable tabletop fan.

In a home environment it is desirable that the appliances are as small and compact as possible. Document US 1,767,060 describes a tabletop fan with an oscillating function whose objective is to provide an air circulation equivalent to that of two or more fans of the prior art. In a home environment it is undesirable for parts to project from the appliance, or for the user to be able to touch any of the moving parts of the fan, such as the blades. Document USD 103,476 includes a grill around the blades. Other types of fans or circulators are described in US 2,488,467, US 2,433,795 and JP 56167897. The fan of US 2,433,795 has spiral grooves in a rotating cowl, instead of fan blades.

Some of the prior prior art assemblies have safety features such as a grill or fairing around the blades to prevent the user from injuring themselves with the moving parts of the fan. However, lattice blade pieces can be difficult to clean and the movement of the blades through the air can be loud and disruptive in a home or office environment.

A disadvantage of certain assemblies of the prior art is that the air flow produced by the fan is not perceived uniformly by the user, due to variations along the surface of the blades or along the surface of the fan. fan facing outward. An uneven or choppy airflow can be perceived as a series of pulses or blows of air. A further disadvantage is that the cooling effect created by the fan decreases with distance from the user. This means that the fan must be located in close proximity to the user in order for the user to receive the benefit of the fan.

Placing fans such as those described above close to a user is not always possible because the bulky shape and structure implies that the fan occupies a significant amount of area of ​​the user's workspace. In the particular case of a fan located on or near a desk, the body of the fan reduces the area available for papers, a computer, or other office equipment.

The shape and structure of a fan on a desk not only reduces the work area available to the user but can block access of natural light (or light from artificial sources) to the desk area. A well-lit desk area is desirable for working and reading. Additionally, a well-lit area can reduce eye strain and related health problems that can be the result of prolonged periods of work at reduced light levels.

The present invention seeks to provide an improved fan assembly that overcomes the disadvantages of the prior art. It is an object of the present invention to provide a fan assembly which, in use, generates a flow of air at a homogeneous speed over the exhaust outlet area of ​​the fan. It is another object to provide an improved fan assembly in which a user at a distance from the fan perceives an improved air flow and cooling effect compared to prior art fans.

In accordance with the invention, there is provided a bladeless fan assembly for creating an air stream, fan assembly comprising a nozzle and means for creating an air flow through the nozzle, nozzle comprising an interior passage, and a mouth to receive the air flow from the interior passage, characterized in that the nozzle comprises a Coanda surface located adjacent to the mouth and on which the mouth is arranged to direct the air flow.

Advantageously, by means of this assembly an air current is generated and a cooling effect is created without the need for a blade fan. Bladeless mounting leads to lower noise emission due to the absence of sound from moving through the air of a fan blade, and a reduction in moving parts and complexity.

In the following description of fans, and in particular of a fan of the preferred embodiment, the term bladeless is used to describe an apparatus in which air flow is emitted or projected forward from a fan assembly without using blades. . By this definition, a fan assembly can be considered to have an outlet area or emission zone devoid of blades or blades from which a flow of air is released or emitted in a direction appropriate to the user. A bladeless fan assembly can be powered from a source

ES 2 355 441 T3 primary air from a variety of sources or generating means such as pumps, generators, motors or other fluid transfer devices, including rotating devices such as a motor rotor and a blade impeller to generate a air flow. The supply of air generated by the motor causes a flow of air to pass from the room or environment outside to the fan assembly through the inside passage to the nozzle, and then out through the mouth.

Herein, the description of a bladeless fan assembly is not intended to extend to the description of the power source and components such as motors required for secondary fan functions. Examples of such secondary fan functions may include lighting, adjusting, and fan oscillation.

The bladeless fan assembly achieves the output and cooling effect described above with a nozzle that includes a Coanda surface to provide an amplification region that utilizes the Coanda effect. A Coanda surface is a known type of surface on which a fluid flow leaving an exit port close to the surface exhibits the Coanda effect. The fluid tends to flow over the surface closely, almost sticking or hugging the surface. The Coanda effect is a proven and well documented convection entrainment procedure in which a primary air flow is directed over the Coanda surface. A description of the characteristics of a Coanda surface, and the effect of a fluid flow on a Coanda surface, can be found in articles such as Reba, Scientific American, volume 214, June 1963, pages 84 to 92.

Preferably, the nozzle defines an opening through which air is drawn from outside the fan assembly by the flow of air directed over the Coanda surface. Air from the external environment is drawn through the opening by air flow directed over the Coanda surface. Advantageously, by means of this assembly, the assembly can be produced and manufactured with a reduced number of parts with respect to that required in fans of the prior art. This reduces manufacturing cost and complexity.

In the present invention, an air flow is created through the nozzle of the fan assembly. In the following description this air flow will be referred to as the primary air flow. The primary airflow exits the nozzle through the mouth and passes over the Coanda surface. The primary airflow draws the air around the mouth of the nozzle, which acts as an air amplifier to supply the user with both the primary airflow and entrained air. The entrained air will be referred to here as the secondary air flow. The secondary air flow is drawn from the room space, region or external environment surrounding the mouth of the nozzle and, by displacement, from other regions around the fan assembly. The primary air flow directed over the Coanda surface, combined with the secondary air flow entrained by the air amplifier, gives a total air flow emitted or projected towards a user from the opening defined by the nozzle. The total airflow is sufficient for the fan assembly to create a suitable air stream for cooling.

The air stream supplied to the user by the fan assembly has the benefit of being an air flow of low turbulence and with a more linear air flow profile than that provided by other prior art devices. A low turbulence linear airflow travels efficiently from the point of emission and loses less energy and speed due to turbulence than the airflow generated by prior art fans. An advantage for a user is that the cooling effect can be perceived even from a distance and the overall efficiency of the fan is increased. This means that the user can choose to place the fan some distance from a work area or desk and is still able to see the benefit of fan cooling.

Advantageously, the assembly results in entrainment of the air surrounding the mouth of the nozzle such that primary air flow is amplified by at least 15%, while maintaining a uniform overall flow rate. The drive and amplification characteristics of the fan assembly result in a fan with greater efficiency than prior art devices. The stream of air emitted from the opening defined by the nozzle has an approximately flat velocity profile along the diameter of the nozzle. Overall, flow rate and profile can be described as plug flow with some regions having laminar or partially laminar flow.

Preferably the mouthpiece comprises a loop. The shape of the nozzle is not limited by the requirement to include space for a blade fan. In a preferred embodiment, the nozzle is annular. By providing an annular nozzle the fan can potentially reach a wide area. In a further preferred embodiment the nozzle is at least partially circular. This mounting can provide a variety of design options for the fan, increasing the options available to a user or customer.

Preferably, the interior passage is continuous. This allows for a smooth, unobstructed air flow within the nozzle and reduces friction losses and noise. In this assembly, the nozzle can be manufactured as a single piece, reducing the complexity of the fan assembly and therefore reducing manufacturing costs.

It is preferred that the mouth is substantially annular. By providing a substantially annular mouth the total air flow can be emitted towards a user over a wide area.

Advantageously, a light source in the room or in the position of the tabletop fan, or natural light can reach the user through the central opening.

Preferably, the mouth is concentric with the interior passage. This assembly will be visually attractive and the concentric position of the mouth with the passage makes it easy to manufacture. Preferably, the Coanda surface extends symmetrically about an axis. More preferably, the subtended angle between the Coanda surface and the axis is in the range of 7 ° to 20 °, preferably around 15 °. This provides efficient primary airflow over the Coanda surface and leads to maximum air entrainment and secondary airflow.

ES 2 355 441 T3

Preferably, the nozzle extends a distance of at least 5 cm in the direction of the axis. Preferably the nozzle extends around the axis in the form of a loop and preferably over a distance in the range of 30 cm to 180 cm. This provides options for emitting air in a range of different outlet areas and aperture sizes, such that they may be suitable for cooling a user's upper body and face when working at a desk, for example. In the preferred embodiment, the nozzle comprises a diffuser located downstream of the Coanda surface. An angular mounting of the diffuser surface and a streamlined shaping of the nozzle and diffuser surface can improve the amplification properties of the fan assembly while minimizing noise and friction losses.

In a preferred arrangement, the nozzle comprises at least one wall defining the interior passage and the mouth, and the at least one wall comprises opposing surfaces defining the mouth. Preferably, the mouth has an outlet, and the spacing between the surfaces opposite the outlet of the mouth is in the range of 1mm to 5mm, more preferably about 1.3mm. By this assembly a nozzle can be provided with the desired flow properties to guide the primary air flow over the Coanda surface and provide a total air flow that reaches the user relatively uniform, or close to uniformity.

In the preferred fan assembly the means for creating a flow of air through the nozzle comprises a motor driven impeller. This mount provides a fan with efficient airflow generation. More preferably, the means for creating an air flow comprises a brushless DC motor and a mixed flow impeller. This mounting reduces friction losses from motor brushes and also reduces carbon residue from brushes in a traditional motor. Reducing carbon waste and emissions is advantageous in a clean or pollution sensitive environment, such as a hospital or around those with allergies.

The nozzle can be rotatable or pivotal relative to a base portion, or other portion, of the fan assembly. This allows the nozzle to be directed towards a user, or away from the user, as needed. The fan assembly can be mounted on a desk, floor, wall or ceiling. This can increase the portion of a room in which the user experiences cooling.

An embodiment of the invention will now be described with reference to the attached drawings, in which:

Figure 1 is a front view of a fan assembly;

Figure 2 is a perspective view of a portion of the fan assembly of Figure 1;

Figure 3 is a side sectional view through a portion of the fan assembly of Figure 1, taken on line AA;

Figure 4 is an enlarged side sectional detail of a portion of the fan assembly of Figure 1; and Figure 5 is a sectional view of the fan assembly taken along line BB of Figure 3 and viewed in direction F of Figure 3.

Figure 1 shows an example of a fan assembly 100 viewed from the front of the device. The fan assembly 100 comprises an annular nozzle 1 defining a central opening 2. Referring also to Figures 2 and 3, the nozzle 1 comprises an interior passage 10, a mouth 12 and a Coanda surface 14 contiguous to the mouth 12 . The Coanda surface 14 is arranged so that a primary air flow leaving the mouth 12 and directed onto the Coanda surface 14 is amplified by the Coanda effect. The nozzle 1 is connected to and supported by a base 16 having an outer casing 18. Base 16 includes a plurality of selection buttons 20 accessible through outer casing 18 and by which fan assembly 100 can be operated.

Figures 3, 4 and 5 show additional specific details of fan assembly 100. A motor 22 for creating air flow through nozzle 1 is located within base 16. Base 16 further comprises an air inlet 24 formed in the outer casing 18. An engine housing 26 is located within base 16. Engine 22 is supported by engine housing 26 and is held in a secured position by a rubber mount or sealing member 28.

In the illustrated embodiment, motor 22 is a brushless DC motor. An impeller 30 is connected to a rotating shaft extending outward from motor 22, and a diffuser 32 is located downstream of impeller 30. Diffuser 32 comprises a stationary, fixed disk having spiral blades.

An inlet 34 to the impeller 30 communicates with the air inlet 24 formed in the outer casing 18 of the base.

16. The outlet 36 of the diffuser 32 and the exhaust of the impeller 30 communicate with hollow passage portions or conduits located within the base 16 in order to establish a flow of air from the impeller 30 to the interior passage 10 of the nozzle 1. The engine 22 is connected to an electrical connection and a power source and is controlled by a controller (not shown). Communication between the controller and the plurality of select buttons 20 allows a user to operate the fan assembly 100.

The characteristics of the nozzle 1 will be described with reference to Figures 3 and 4. The shape of the nozzle 1 is annular. In this embodiment, the nozzle 1 has a diameter of around 350 mm, but the nozzle can have any desired diameter, for example around 300 mm. The inner passage 10 is annular and is formed as a continuous loop or conduit within the nozzle 1. The nozzle 1 is formed by at least one wall defining the inner passage 10 and the mouth 12. In this embodiment, the nozzle 1 comprises an inner wall 38 and an outer wall 40. In the illustrated embodiment, the walls 38, 40 are arranged in a loop or folded such that the inner wall 38 and the outer wall 40 approximate each other. The inner wall 38 and the outer wall

ES 2 355 441 T3 together define mouth 12, and mouth 12 extends about the X axis. Mouth 12 comprises a flared region 42 that tapers to an outlet 44. Outlet 44 comprises a gap or spacing formed between the wall inside 38 of nozzle 1 and outside wall 40 of nozzle 1. The spacing between the opposite surfaces of the walls 38, 40 at the outlet 44 of the nozzle 12 is chosen to be in the range of 1mm to 5mm . The choice of spacing will depend on the desired fan performance characteristics. In this embodiment, the outlet 44 has a width of about 1.3 mm, and the mouth 12 and the outlet 44 are concentric with the inner passage.

10.

The mouth 12 is contiguous with the surface of Coanda 14. The mouthpiece 1 further comprises a diffuser portion located downstream of the surface of Coanda. The diffuser portion includes a diffuser surface 46 to further contribute to the flow of air stream supplied or expelled from the fan assembly 100. In the embodiment illustrated in Figure 3, the mouth 12 and the overall mounting of the mouthpiece 1 are such that the subtended angle between the surface of Coanda 14 and the X axis is around 15 °. The angle is chosen for efficient air flow over the surface of Coanda 14. Base 16 and nozzle 1 have a depth in the direction of the X-axis. Nozzle 1 extends a distance of about 5 cm in the direction From the axis. The diffuser surface 46 and the overall profile of the nozzle 1 are based on an aerodynamic shape, and in the example shown the diffuser portion extends a distance of about 2/3 of the overall depth of the nozzle 1.

The fan assembly 100 described above operates as follows. When a user makes a suitable selection of the plurality of buttons 20 to operate or activate the fan assembly 100, a signal or other communication is sent to operate the motor 22. The motor 22 is thus activated and air is drawn into the assembly. fan 100 through air inlet 24. In the preferred embodiment, air is withdrawn at a rate of about 20 to 30 liters per second, preferably about 27 l / s (liters per second). Air passes through outer casing 18 and along the path illustrated by arrow F 'in Figure 3 toward inlet 34 of impeller 30. The air flow leaving the outlet 36 of the diffuser 32 and the exhaust of the impeller 30 is divided into two air flows proceeding in opposite directions through the inner passage 10. The air flow is limited when it enters the mouth 12 and it is further limited to the outlet 44 of the mouth 12. The air flow exits through the outlet 44 as a primary air flow.

The flow rate and emission of primary air flow creates an area of ​​low pressure at the air inlet 24 with the effect of drawing additional air into the fan assembly 100. The operation of the fan assembly induces a high air flow through from nozzle 1 and out through aperture 2. Primary air flow is directed over Coanda surface 14 and diffuser surface 46, and is amplified by the Coanda effect. A secondary air flow is generated by entrainment of air from the external environment, specifically from the region surrounding the outlet 44 and around the outer edge of the nozzle 1. A portion of the secondary air flow entrained by the air flow Primary can also be guided onto diffuser surface 46. This secondary air flow passes through opening 2, where it combines with the primary air flow to produce a total air flow, projected forward from the fan assembly 100 in the region, of 500 to 700 L / s.

The combination of entrainment and amplification results in a total airflow from opening 2 of fan assembly 100 that is greater than the airflow rate of a fan assembly without such a Coanda or amplification surface contiguous to the emission area. .

The amplification and laminar type of air flow produced results in a sustained flow of air that is directed towards a user from nozzle 1. The flow velocity over a distance of up to three nozzle diameters (that is, around 1000 at 1200mm) from a user is around 400 to 500 l / s. The total airflow has a velocity of around 3 to 4 m / s (meters per second). Higher speeds can be achieved by reducing the subtended angle between the Coanda surface 14 and the X axis. A smaller angle results in a total airflow that is emitted in a more focused and directed fashion. This type of air flow tends to be emitted at a higher velocity but with a reduced mass flow velocity. Conversely, a higher mass flow can be achieved by increasing the angle between the Coanda surface and the shaft. In this case, the velocity of the emitted air flow is reduced, but the generated mass flow increases.

Thus, the performance of the fan assembly can be altered by altering the subtended angle between the Coanda surface and the X axis.

The invention is not limited to the detailed description provided above. Variations will be apparent to the person skilled in the art. For example, the fan could be of a different height or diameter. The fan does not need to be placed on a desk, but could be free-standing, wall-mounted, or ceiling-mounted. The shape of the fan could be adapted to suit any situation or location where a flow of cooling air is desired. A portable fan could have a smaller nozzle, for example 5 cm in diameter. The means for creating an air flow through the nozzle can be a motor or other air emitting device, such as any air blower or vacuum source that can be used so that the fan assembly can create a stream of air. air in a room. Examples include a motor such as an AC induction motor or types of brushless DC motors, although they may also comprise any suitable air moving or air transport device, such as a pump or other means of providing directed fluid flow to generate and create a flow of air. Features of an engine may include a diffuser or secondary diffuser located downstream of the engine to recover some of the static pressure lost in the engine housing and along the engine.

The outlet of the mouth can be modified. The outlet of the mouth can be widened or narrowed to a variety of spacings to maximize air flow. The Coanda effect can be elicited on a variety of different surfaces, or a variety of internal or external designs can be used in combination to achieve the necessary flow and drag.

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Other shapes of nozzle are envisaged. For example, a nozzle could be used that comprises an oval or racetrack shape, a single strip or line, or a block shape. The fan assembly provides access to the center of the fan, as there are no blades. This means that additional features could be provided in the opening defined by the nozzle, such as lighting or a clock or LCD display device.

Other features could include a pivoting or tilting base to facilitate movement and adjustment of the nozzle position by the user.