Fan with a filter

Abstract

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.

Claims

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.

7. The fan assembly of claim 1, wherein the nozzle comprises a loop.

8. The fan assembly of claim 1, wherein the nozzle is substantially annular.

9. The fan assembly of claim 1, wherein the nozzle is at least partially circular.

10. The fan assembly of claim 1, wherein the nozzle comprises a diffuser.

11. The fan assembly of claim 1, wherein the nozzle comprises at least one wall defining the interior passage and the mouth, and wherein said at least one wall comprises opposing surfaces defining the mouth.

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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

(2) FIG. 1 is a front view of a fan assembly;

(3) FIG. 2 is a perspective view of a portion of the fan assembly of FIG. 1;

(4) FIG. 3 is a side sectional view taken at line A-A through a portion of the fan assembly of FIG. 1, illustrating a first filter arrangement

(5) FIG. 4 is an enlarged side sectional detail of a portion of the fan assembly of FIG. 1;

(6) FIG. 5 is a sectional view of the fan assembly taken along line B-B of FIG. 3 and viewed from direction F of FIG. 3;

(7) FIG. 6 is a sectional view of the fan assembly of FIG. 1, illustrating a second filter arrangement;

(8) FIG. 7 is a side sectional view taken at line A-A through a portion of the fan assembly of FIG. 1, illustrating a third filter arrangement; and

(9) FIG. 8 is an enlarged side sectional detail of a portion of the fan assembly as illustrated in FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

(10) FIG. 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. With reference also to FIGS. 2 and 3, nozzle 1 comprises an interior passage 10, a mouth 12 and a Coanda surface 14 adjacent the mouth 12. The Coanda surface 14 is arranged so that a primary air flow exiting the mouth 12 and directed over 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. The base 16 includes a plurality of selection buttons 20 accessible through the outer casing 18 and through which the fan assembly 100 can be operated.

(11) 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 24a, 24b 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.

(12) In the illustrated embodiment, the motor 22 is a DC brushless motor. An impeller 30 is connected to a rotary shaft extending outwardly from the motor 22, and a diffuser 32 is positioned downstream of the impeller 30. The diffuser 32 comprises a fixed, stationary disc having spiral blades.

(13) An inlet 34 to the impeller 30 communicates with the air inlet 24a, 24b 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.

(14) 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.

(15) The mouth 12 is adjacent the Coanda surface 14. The nozzle 1 further comprises a diffuser portion located downstream of the Coanda surface. The diffuser portion includes a diffuser surface 46 to further assist the flow of air current delivered or output from the fan assembly 100. In the example illustrated in FIG. 3 the mouth 12 and the overall arrangement of the nozzle 1 is such that the angle subtended between the Coanda surface 14 and the axis X is around 15?. The angle is chosen for efficient air flow over the Coanda surface 14. The base 16 and the nozzle 1 have a depth in the direction of the axis X. The nozzle 1 extends by a distance of around 5 cm in the direction of the axis. The diffuser surface 46 and the overall profile of the nozzle 1 are based on an aerofoil shape, and in the example shown the diffuser portion extends by a distance of around two thirds the overall depth of the nozzle 1.

(16) 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.

(17) The output and emission of the primary air flow creates a low pressure area at the air inlet with the effect of drawing additional air into the fan assembly 100. The operation of the fan assembly 100 induces high air flow through the nozzle 1 and out through the opening 2. The primary air flow is directed over the Coanda surface 14 and the 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 around the outlet 44 and from around the outer edge of the nozzle 1. A portion of the secondary air flow entrained by the primary air flow may also be guided over the diffuser surface 46. This secondary air flow passes through the opening 2, where it combines with the primary air flow to produce a total air flow projected forward from the nozzle 1.

(18) The combination of entrainment and amplification results in a total air flow from the opening 2 of the fan assembly 100 that is greater than the air flow output from a fan assembly without such a Coanda or amplification surface adjacent the emission area.

(19) The amplification and laminar type of air flow produced results in a sustained flow of air being directed towards a user from the nozzle 1. In the preferred embodiment the mass flow rate of air projected from the fan assembly 100 is at least 450 l/s, preferably in the range from 600 l/s to 700 l/s. The flow rate at a distance of up to 3 nozzle diameters (i.e. around 1000 to 1200 mm) from a user is around 400 to 500 l/s. The total air flow has a velocity of around 3 to 4 m/s (meters per second). Higher velocities are achievable by reducing the angle subtended between the Coanda surface 14 and the axis X. A smaller angle results in the total air flow being emitted in a more focussed and directed manner This type of air flow tends to be emitted at a higher velocity but with a reduced mass flow rate. Conversely, greater mass flow can be achieved by increasing the angle between the Coanda surface and the axis. In this case the velocity of the emitted air flow is reduced but the mass flow generated increases. Thus the performance of the fan assembly can be altered by altering the angle subtended between the Coanda surface and the axis X. Performance of the fan assembly

(20) 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 24a, 24b. Consequently air flow drawn into the base 16 through the air inlet 24a 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.

(21) In the illustrated arrangement, the filter 26 is positioned adjacent the air inlet 24a, 24b. 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 24a, 24b 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.

(22) 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 25a, 25b 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 25a, 25b 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 25a, 25b 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.

(23) 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.

(24) The interior passage 10 is divided by the filter 226 into an outer air chamber 228 and an inner air chamber 230. Each air chamber 228, 230 comprises a continuous duct or passageway within the nozzle 1. The outer air chamber 228 is arranged to receive the airflow from the base 16, and the inner air chamber 230 is arranged to convey the air flow to the mouth 12.

(25) Thus, all of the air flow drawn into the nozzle 1 will enter the outer air chamber 228, pass through the filter medium 250 and into the inner air chamber 230 before exiting the nozzle 1 through the mouth 12. The filter 226 thus provides a post-motor filter in the fan assembly 100, and can thereby capture dirt and carbon debris that may be generated by motor brushes in a traditional motor or that may be drawn into the nozzle from outside the fan assembly.

(26) 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.

(27) Also the manner in which the filter arrangement is received and located within the appliance is immaterial to this invention and a skilled reader will appreciate that the location can be formed by the mating of corresponding surfaces, push or snap fittings or other equivalent means. The filter may be positioned in or formed around any part of the fan assembly, it may be located adjacent or in close proximity to the air inlet, it may surround the entire circumference or boundary of the base, the motor or the motor housing. The shape and size of the portion of the fan assembly accommodating the filter may be modified.

(28) 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.

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

(30) 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.

(31) Other features could include a pivotable or tiltable base for ease of movement and adjustment of the position of the nozzle for the user.