Source: https://patents.google.com/patent/US10145388B2/en
Timestamp: 2019-04-24 14:23:19+00:00

Document:
A fan assembly for creating an air current is described, the fan assembly having a nozzle, a system for creating an air flow through the nozzle and a filter for removing particulates from the air flow, the nozzle having an interior passage, a mouth for receiving the air flow from the interior passage, and a Coanda surface located adjacent the mouth and over which the mouth is arranged to direct the air flow, wherein the fan provides an arrangement producing an air current and a flow of cooling air created without requiring a bladed fan, i.e. air flow is created by a bladeless fan.
This application is a continuation of U.S. patent application Ser. No. 13/125,742, filed Jul. 8, 2011, which is a national stage application under 35 USC 371 of International Application No. PCT/GB2009/051401, filed Oct. 19, 2009, which claims the priority of United Kingdom Application No. 0819612.3, filed Oct. 25, 2008, the entire contents of which are incorporated herein by reference.
In a domestic environment it is desirable for appliances to be as small and compact as possible. U.S. Pat. No. 1,767,060 describes a desk fan with an oscillating function that aims to provide an air circulation equivalent to two or more prior art fans. In a domestic environment it is undesirable for parts to project from the appliance, or for the user to be able to touch any moving parts of the fan, such as the blades. USD 103,476 includes a cage around the blades. Other types of fan or circulator are described in U.S. Pat. Nos. 2,488,467, 2,433,795 and JP 56-167897. The fan of U.S. Pat. No. 2,433,795 has spiral slots in a rotating shroud instead of fan blades.
A disadvantage of certain of the prior art arrangements is that the air flow produced by the fan is not felt uniformly by the user due to variations across the blade surface or across the outward facing surface of the fan. Uneven or ‘choppy’ air flow can be felt as a series of pulses or blasts of air. The uneven air flow may move and disturb dust and debris located in the vicinity of the fan, causing it to be projected towards the user. Furthermore, this type of air flow can cause lightweight items, such as papers or stationery, placed close to the fan to move or become dislodged from their location. This is disruptive in a home or office environment.
The filter may comprise one or any number of filters or filters assemblies in one or more locations within the fan assembly. The filter material may comprise filter media such as foam materials, carbon, paper, HEPA (High Efficiency Particle Arrester) filter media, fabric or open cell polyurethane foam, for example. The filter may comprise a mesh or porous material located around a base of the fan assembly, and may form part of, or be mounted to, the outer casing. The filter may be suitable for removal of specific pollutants and particulates from the air flow and may be used for chemical or odor removal. Other filtration schemes or processing systems such as ionization or UV treatment could be used in any combination within the filter and within the fan assembly.
The fan assembly achieves the output and cooling effect described above with a nozzle which includes a Coanda surface to provide an amplifying region utilizing the Coanda effect. A Coanda surface is a known type of surface over which fluid flow exiting an output orifice close to the surface exhibits the Coanda effect. The fluid tends to flow over the surface closely, almost ‘clinging to’ or ‘hugging’ the surface. The Coanda effect is already a proven, well documented method of entrainment whereby a primary air flow is directed over the Coanda surface. A description of the features of a Coanda surface, and the effect of fluid flow over a Coanda surface, can be found in articles such as Reba, Scientific American, Volume 214, June 1963 pages 84 to 92.
Advantageously, the assembly results in the entrainment of air surrounding the mouth of the nozzle such that the primary air flow is amplified by at least 15%, while a smooth overall output is maintained. The entrainment and amplification features of the fan assembly result in a fan with a higher efficiency than prior art devices. The air current emitted from the opening defined by the nozzle has an approximately flat velocity profile across the diameter of the nozzle. Overall the flow rate and profile can be described as plug flow with some regions having a laminar or partial laminar flow.
In the preferred embodiment the nozzle comprises a diffuser located downstream of the Coanda surface. An angular arrangement of the diffuser surface and an aerofoil-type shaping of the nozzle and diffuser surface can enhance the amplification properties of the fan assembly while minimizing noise and frictional 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 opposing surfaces at the outlet of the mouth is in the range from 1 mm to 10 mm, more preferably around 5 mm By this arrangement a nozzle can be provided with the desired flow properties to guide the primary air flow over the Coanda surface and provide a relatively uniform, or close to uniform, total air flow reaching the user.
FIG. 8 is an enlarged side sectional detail of a portion of the fan assembly as illustrated in FIG. 7.
FIGS. 3, 4 and 5 show further specific details of the fan assembly 100. A motor 22 for creating an air flow through the nozzle 1 is located inside the base 16. The base 16 further comprises an air inlet 24 a, 24 b formed in the outer casing 18 and through which air is drawn into the base 16. A motor housing 28 for the motor 22 is also located inside the base 16. The motor 22 is supported by the motor housing 28 and held or fixed in a secure position within the base 16.
An inlet 34 to the impeller 30 communicates with the air inlet 24 a, 24 b formed in the outer casing 18 of the base 16. The outlet 36 of the diffuser 32 and the exhaust from the impeller 30 communicate with hollow passageway portions or ducts located inside the base 16 in order to establish air flow from the impeller 30 to the interior passage 10 of the nozzle 1. The motor 22 is connected to an electrical connection and power supply and is controlled by a controller (not shown). Communication between the controller and the plurality of selection buttons 20 enable a user to operate the fan assembly 100.
The features of the nozzle 1 will now be described with reference to FIGS. 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 1 may have any desired diameter, for example around 300 mm. The interior passage 10 is annular and is formed as a continuous loop or duct within the nozzle 1. The nozzle 1 is formed from at least one wall defining the interior 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 looped or folded shape such that the inner wall 38 and outer wall 40 approach one another. The inner wall 38 and the outer wall 40 together define the mouth 12, and the mouth 12 extends about the axis X. The mouth 12 comprises a tapered region 42 narrowing to an outlet 44. The outlet 44 comprises a gap or spacing formed between the inner wall 38 of the nozzle 1 and the outer wall 40 of the nozzle 1. The spacing between the opposing surfaces of the walls 38, 40 at the outlet 44 of the mouth 12 is chosen to be in the range from 1 mm to 10 mm. The choice of spacing will depend on the desired performance characteristics of the fan. In this embodiment the outlet 44 is around 5 mm wide, and the mouth 12 and the outlet 44 are concentric with the interior passage 10.
The fan assembly 100 described above operates in the following manner When a user makes a suitable selection from the plurality of buttons 20 to operate or activate the fan assembly 100, a signal or other communication is sent to drive the motor 22. The motor 22 is thus activated and air is drawn into the fan assembly 100 via the air inlet. In the preferred embodiment air is drawn in at a rate of approximately 40 to 100 liters per second, preferably around 80 l/s (liters per second). The air passes through the outer casing 18 and along the route illustrated by arrows F, F″ of FIGS. 3 and 6 to the inlet 34 of the 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 that proceed in opposite directions through the interior passage 10. The air flow is constricted as it enters the mouth 12 and is further constricted at the outlet 44 of the mouth 12. The constriction creates pressure in the system. The motor 22 creates an air flow through the nozzle 1 having a pressure of at least 300 kPa and a pressure of up to 700 kPa may be used. The air flow created overcomes the pressure created by the constriction and the air flow exits through the outlet 44 as a primary air flow.
A first filter arrangement for the fan assembly 100 is illustrated in FIGS. 3 and 5. The first filter arrangement comprises a filter 26, which comprises a filter medium 50. In this filter arrangement the filter 26 is placed upstream of the motor 22 and impeller 30 of the fan assembly 100, and downstream of the air inlet 24 a, 24 b. Consequently air flow drawn into the base 16 through the air inlet 24 a passes through the filter 26 and the filter medium 50 before entering the motor housing 28. The air flow is constricted as it enters the filter 26 and passes through the filter medium 50. The filter 26 provides a pre-motor filter in the fan assembly 100, and the motor is thereby reliably protected from dirt, dust and debris that may be drawn into the device.
In the illustrated arrangement, the filter 26 is positioned adjacent the air inlet 24 a, 24 b. The filter 26 is located such that it extends cylindrically about an axis Y, perpendicular to the axis X. The fan assembly 100 will include a recess or other shaping into which the filter 26 is received. The recess is preferably designed to accommodate snugly the filter 26. In addition, the filter 26 is preferably mounted and secured within the recess to establish an air-tight seal so that all of the air flow drawn into the air inlet 24 a, 24 b will pass through the filter medium 50. The filter 26 is preferably fixedly connected and secured within the fan assembly 100 by suitable fixings such as screw-threaded portions, fasteners, seal members or other equivalent means.
A second filter arrangement for the fan assembly 100 is illustrated in FIG. 6. The second filter arrangement comprises a filter 126, which comprises a filter medium 150. The fan assembly 100 illustrated in FIG. 6 differs from that illustrated in FIGS. 3 and 5 in that air inlets 25 a, 25 b are formed in the lower surface of the outer casing 18, rather than in the cylindrical side wall thereof. The filter 126 is positioned adjacent the lower air inlets 25 a, 25 b and shaped so as to substantially cover the lower surface of the base 16. The filter 126 is preferably mounted and secured in a fixed arrangement within the base 16 to establish an air-tight seal so that all of the air flow drawn into air inlet 25 a, 25 b will pass through the filter medium 150. The filter 126 is preferably fixedly connected and secured within the fan assembly 100 by suitable fixings. As described previously, the filter 126 thus provides a pre-motor filter in the fan assembly 100, and the motor is thereby reliably protected from dirt, dust and debris that may be drawn into the device.
A third filter arrangement for the fan assembly 100 is illustrated in FIGS. 7 and 8. This third arrangement may be used in combination with, or separately from, any of the first and second filter arrangements. The third filter arrangement comprises a filter 226, which comprises a filter medium 250. The filter 226 is annular and is housed within the interior passage 10 of the nozzle 1 such that the filter 226 extends about the axis X. The filter 226 has a depth of around 5 cm in the direction of the axis X. The dimensions of the filter 226 are chosen so that the filter 226 is accommodated snugly within the nozzle 1. In a similar manner to the first and second filter arrangements, the filter 226 is preferably fixedly connected and secured within the interior passage 10 of the nozzle 1 by suitable fixings such as screw-threaded portions, fasteners, seal members or other equivalent means.
In any of the above filter arrangements the filter may comprise one or any number of filters or filters assemblies in one or more locations within the fan assembly. For example, the shape and size of the filter and the type of filter material, may be altered. The filter material may comprise filter media such as foam materials, carbon, paper, HEPA (High Efficiency Particle Arrester) filter media, fabric or open cell polyurethane foam, for example. The filter material could be material having different density and thickness to that described and illustrated above. The filter may comprise a mesh or porous material located around the base and may form part of, or be mounted to, the outer casing. The filter may be suitable for removal of specific pollutants and particulates from the air flow and may be used for chemical or odor removal. Other filtration schemes or processing systems such as ionization or UV treatment could be used in any combination within the filter and within the fan assembly.
The invention is not limited to the detailed description given 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 performance of the fan assembly may be modified by increasing the diameter of the nozzle and the area of the mouth opening, the distance that the nozzle extends in the direction of the axis may be greater than 5 cm, and may be up to 20 cm. The fan need not be located on a desk, but could be free standing, wall mounted or ceiling mounted. The fan shape could be adapted to suit any kind of situation or location where a cooling flow of air is desired. A portable fan could have a smaller nozzle, say 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 an air current in a room. Examples include a motor such as an AC induction motor or types of DC brushless motor, but may also comprise any suitable air movement or air transport device such as a pump or other means of providing directed fluid flow to generate and create an air flow. Features of a motor may include a diffuser or a secondary diffuser located downstream of the motor to recover some of the static pressure lost in the motor housing and through the motor.
The outlet of the mouth may be modified. The outlet of the mouth may be widened or narrowed to a variety of spacings to maximize air flow. The Coanda effect may be made to occur over a number of different surfaces, or a number of internal or external designs may be used in combination to achieve the flow and entrainment required.
1. A fan assembly for creating an air current, the fan assembly comprising a nozzle that extends about an axis to define an opening through which air from outside the fan assembly is drawn by an air flow, a base connected to the nozzle, the base comprising a system for creating the air flow through the nozzle comprising a single air inlet, at least one base air inlet, and a filter surrounding the base and surrounding the system for creating the air flow for removing particulates from the air flow, the nozzle comprising an interior passage, a mouth for receiving the air flow from the interior passage, wherein the single air inlet to the system for creating the air flow is perpendicular to the at least one base air inlet.
2. The fan assembly of claim 1, wherein the filter is located upstream of the system for creating the air flow.
3. The fan assembly of claim 1, wherein an additional filter is located within the nozzle.
4. The fan assembly of claim 2, comprising an additional filter located downstream of the system for creating the air flow.
5. The fan assembly of claim 1, wherein the nozzle extends by a distance of at least 5 cm in the direction of the axis.
6. The fan assembly of claim 1, wherein the nozzle extends about the axis by a distance in the range from 30 cm to 180 cm.
10. The fan assembly of claim 1, wherein the nozzle comprises a diffuser.
12. The fan assembly of claim 11, wherein the mouth has an outlet, and the spacing between the opposing surfaces at the outlet of the mouth is in the range from 0.5 mm to 10 mm.
13. The fan assembly of claim 1, wherein the system for creating the air flow through the nozzle comprises an impeller driven by a motor.
14. The fan assembly of claim 13, wherein the system for creating the air flow comprises a DC brushless motor and a mixed flow impeller.
15. The fan assembly of claim 1, wherein the base comprises an air inlet and the filter is located upstream of the air inlet.
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References: Application No. 0819612
 Application No. 16
 Application No. 0819612
 Application No. 1004813
 Application No. 1004812
 Application No. 1004814