GB2484276A

GB2484276A - A bladeless portable fan

Info

Publication number: GB2484276A
Application number: GB201016640A
Authority: GB
Inventors: Kevin John Simmonds
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2010-10-04
Filing date: 2010-10-04
Publication date: 2012-04-11
Also published as: GB201016640D0

Abstract

A portable fan assembly includes a body 10 and an air outlet section 14. The body includes an air inlet 18, an impeller, and a motor for driving the impeller to draw an air flow through the air inlet. The air outlet section 14 includes an air passage for receiving the air flow from the body, an air outlet 20 for emitting the air flow from the fan assembly, and an opening through which the air from outside the fan assembly is drawn by the air flow emitted from the air outlet.

Description

A FAN ASSEMBLY

The present invention relates to a fan assembly. In its preferred embodiment, the present invention relates to a low power, mains-operated fan assembly.

The present invention provides a fan assembly comprising a body comprising an air inlet, an impeller, and a motor for driving the impeller to drawn an air flow through the air inlet; and an air outlet section comprising an annular outer section which is integral with part of the body, and an annular inner section located within the outer section, the inner and outer sections defining an air passage for receiving the air flow from the body, an air outlet for emitting the air flow from the fan assembly, and an opening through which the air from outside the fan assembly is drawn by the air flow emitted from the air outlet.

In order to minimise manufacturing costs the fan assembly has a relatively low number of component parts by making part of the air outlet section integral with part of the body. Preferably, the air outlet section comprises an outer section and an inner section which define the air passage, air outlet and the opening, and the body comprises a side wall containing the motor and the impeller, and which is integral with the outer section of the air outlet section of the fan assembly.

The body may comprise a base for supporting the fan assembly. The side wall is preferably tubular, more preferably a cylindrical wall having an opening at the upper end thereof through which the air flow enters the air outlet section of the fan assembly.

The base is preferably integral with the side wall, and so may extend outwardly from the lower open end of the side wall to enhance the stability of the fan assembly. The base may have a generally circular outer periphery having a diameter which is at least 1.5 times, preferably at least twice, the diameter of the side wall of the body. Ahematively, the base may have any other desired shape, such as an elliptical or polygonal shape.

The base may be locatable on a rotatable base plate for allowing a user to rotate the fan assembly to re-direct the air flow generated by the fan assembly. The base plate may be

I

oscillated by an oscillation mechanism to sweep the air flow over an angle, for example around 90°.

The fan assembly preferably comprises a support for supporting the motor and the impeller. The side wall preferably comprises a bore into which the support is inserted.

For example, the support may comprise a frame which is insertable into the bore of the side wall of the body through the lower open end of the side wall. The lower end of the frame is preferably closed to provide a substantially continuous lower surface of the fan assembly. The frame is preferably a tubular frame which is substantially co-axial with the side wall of the body. The frame preferably comprises a plurality of apertures through which the air flow passes between the air inlet and the impeller.

The power supply circuit is preferably mounted on the support, and so is inserted into the body simuhaneously with the support. During assembly, the motor and impeller may be inserted into the body, through the lower open end of the side wall, before the support is inserted into the body. An actuator may then be connected to the power supply circuit, for example through an aperture formed in the side wall of the body, to enable a user to selectively activate and deactivate the motor. An annular diffuser may be located between the impeller and the air outlet section to control the flow characteristics of the air flow emitted from the impeller before it enters the air outlet section. The diffuser may be integral with the housing of the motor, or it may be a separate component.

The fan assembly preferably comprises an input terminal for receiving a direct current (DC) voltage, preferably in the range from 4 to 12 V, from an extemal power source, and a power supply circuit connected to the input terminal for providing a driving voltage to the motor. The input terminal is preferably located at the rear of the side wall. The input terminal may be configured for connection to one of a number of different external power sources. In a preferred embodiment, the input terminal is connectable to an adapter for converting an alternating current (AC) voltage, such as a or 220 AC voltage provided by a mains power supply, to a DC voltage, for example a 4.8 V DC voltage. Alternatively, the input terminal may be connectable to a 6 V or a 12 V power source of a vehicle, such as a lighter socket, by an appropriate cable. As another ahernative, the input terminal may be in the form of a Universal Serial Bus (USB) port for receiving a vohage in the range from 4.4 to 5.25 V from a computer via a USB cable. In this latter case the fan assembly may comprise a memory for storing data received from the USB port.

The fan assembly is thus preferably a low power fan assembly in which, in use, the motor draws less than 10 W of power, preferably less than 5 W of power.

Each of the inner and outer sections is preferably annular in shape so that the opening has a generally circular profile. The fan assembly preferably has relatively small dimensions; the diameter of the opening is preferably less than 150 mm, and the height of the fan assembly is preferably less than 250 mm. The fan assembly can therefore be a portable fan assembly, suitable for location on a desk, bench or other item of furniture, or in a car, caravan or other vehicle with a suitable external power supply for driving the motor of the fan assembly.

The air inlet may comprise one or more apertures formed in the side wall of the body and through which the air flow enters the body. The air outlet section may comprise a single air outlet extending about the opening, preferably surrounding the opening.

Alternatively, the air outlet section may comprise a plurality of air outlets spaced about the opening. For example, the air outlet section may comprise a pair of air outlets located on opposite sides of the opening, with each air outlet emitting a respective portion of the air flow.

The, or each, air outlet is preferably in the form of a slot, and which preferably has a width in the range from 0.5 to 5 mm. In a preferred embodiment, the, or each, slot has a width of around 3 mm. Spacers may be formed on the outer section of the air outlet section for engaging the inner section of the air outlet section to maintain a relatively uniform spacing between the inner and outer sections of the air outlet section.

Alternatively, the spacers may be formed on the inner section of the air outlet section.

The air outlets(s) are preferably located towards the rear of the air outlet section, and are preferably arranged to direct the air flow through a bore defined by the external surface of the inner section of the air outlet section. The, or each, air outlet is preferably defined by overlapping sections of the external surface of the inner section and the internal surface of the outer section of the air outlet section.

The air outlet section preferably comprises a surface located adjacent the air outlet(s) and over which the air outlet(s) is arranged to direct the air flow emitted therefrom.

Preferably, this surface is a curved surface, and more preferably is a Coanda surface.

Preferably, the external surface of the inner section of the air outlet section is shaped to define the Coanda surface. 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 in which a primary air flow is directed over a 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 1966 pages 84 to 92. Through use of a Coanda surface, an increased amount of air from outside the fan assembly is drawn through the opening by the air emitted from the air outlet(s).

In a preferred embodiment an air flow is created which is emitted from the air outlet section of the fan assembly. In the following description this air flow will be referred to as the primary air flow. The primary air flow passes over a Coanda surface. The primary air flow entrains air surrounding the air outlet section, which acts as an air amplifier to supply both the primary air flow and the entrained air to the user. The entrained air will be referred to here as a 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, and passes predominantly through the opening defined by the air outlet section. The primary air flow directed over the Coanda surface combined with the entrained secondary air flow equates to a total air flow emitted or projected forward from the air outlet section of the fan assembly.

Preferably, the air outlet section comprises a diffuser surface located downstream of the Coanda surface. The diffuser surface directs the air flow emitted towards a user's location while maintaining a smooth, even output.

The Coanda surface preferably extends about an axis which is orthogonal to the plane of the opening. The angle subtended between the Coanda surface and the axis is preferably in the range from 5 to 300, more preferably in the range from 15 to 25°.

The body and the air outlet section are preferably formed from plastics material. For example, the body and the inner and outer sections of the air outlet section may be formed from a polycarbonate (PC) material, such as a PC/acrylonitrile butadiene styrene (ABS) blend. The impeller and, where provided, the diffuser located immediately downstream from the impeller, are also preferably formed from plastics material, and a PC/ABS blend may also be used to form these components. The support may also be formed from plastics material, but as this component is located mainly within the body it may be foniied from a weaker plastics material, such as a polypropylene/talc blend.

Preferred features of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a front perspective view, from above, of a fan assembly; Figure 2 is a front view of the fan assembly; Figure 3 is a side sectional view of the fan assembly, taken along line A-A in Figure 2; Figure 4 is an exploded view of the impeller and motor of the motor and impeller unit; and Figure 5 is a rear view of the fan assembly.

Figures 1 and 2 illustrate a fan assembly 10. The fan assembly 10 comprises a main body having an air inlet section 12 and an air outlet section 14. The air inlet section 12 comprises a generally cylindrical side wall 16 having an air inlet 18 in the form of a plurality of apertures formed in the side wall 16, and through which a primary air flow is drawn into the air inlet section 12 from the external environment. The air outlet section 14 comprises an air outlet 20 for emitting the primary air flow from the fan assembly 10.

The air outlet section 14 comprises an annular outer section 22 connected to and extending about an annular inner section 24. The annular sections 22, 24 of the air outlet section 14 extend about and define an opening 26. Each of these sections may be formed from a plurality of connected parts, but in this embodiment each of the outer section 22 and the inner section 24 is formed from a respective, single moulded part. In this example the outer section 22 is integral with the side wall 16 of the air inlet section 12, but the outer section 22 may be connected to the side wall 16, for example by a snap-fit connection, a bayonet fitting, a screw fitting, gluing, uhrasonic welding or by any other suitable connection. During assembly, the inner section 24 is inserted into the outer section 22 through the open front end 28 of the outer section 22. As shown in Figure 3, the front end 28 is received in a rearwardly-facing annular slot 30 located at the front of the inner section 24. The outer and inner sections 22, 24 may be connected together using an adhesive introduced to the slot 30.

The outer section 22 and the inner section 24 together define an annular interior passage 32 (shown in Figure 3) for conveying the primary air flow to the air outlet 20. The interior passage 32 is bounded by the intemal surface of the outer section 22 and the internal surface of the inner section 24. The side wall 16 of the air inlet section 12 has an open upper end 34 defining an aperture through which the primary air flow enters the interior passage 32 from the air inlet section 12.

The air outlet 20 is located towards the rear of the air outlet section 14, and is arranged to emit the primary air flow towards the front of the fan assembly 10, through the opening 26. The air outlet 20 extends at least partially about the opening 26, and preferably surrounds the opening 26. The air outlet 20 is defined by overlapping, or facing, portions of the internal surface of the outer section 22 and the external surface of the inner section 24, respectively, and is in the form of an annular slot, preferably having a relatively constant width in the range from 0.5 to 5 mm. In this example the air outlet has a width of around 3 mm. Spacers 35 may be spaced about the air outlet 20 for urging apart the overlapping portions of the outer section 22 and the inner section 24 to maintain the width of the air outlet 20 at the desired level. These spacers 35 may be integral with either the outer section 22 or the inner section 24, and in this example are integral with the outer section 22.

The air outlet 20 is shaped to direct the primary air flow over the external surface of the inner section 24. The external surface of the inner section 24 comprises a Coanda surface 36 located adjacent the air outlet 20 and over which the air outlet 20 directs the air emitted from the fan assembly 10, and a diffuser surface 38 located downstream of the Coanda surface 36. The diffuser surface 38 is arranged to taper away from the central axis X of the opening 26 in such a way so as to assist the flow of air emitted from the fan assembly 10. The angle subtended between the diffuser surface 38 and the central axis X of the opening 26 is in the range from 5 to 30°, and in this example is around 24°.

As mentioned above, the air inlet section 12 comprises a side wall 16 which is integral with the outer section 22 of the air outlet section 14. The side wall 16 is generally cylindrical in shape, and has an open upper end 34, an open lower end 40 and a bore 42.

The side wall 16 comprises the air inlet 18 through which the primary air flow enters the fan assembly 10. In this embodiment the air inlet 18 comprises an array of apertures formed in the side wall 16. Alternatively, the air inlet 18 may comprise one or more grilles or meshes mounted within windows formed in the side wall 16.

The fan assembly 10 comprises a base 44 for engaging a surface on which the fan assembly 10 is located. The base 44 is connected to, and is preferably integral with, the side wall 16 of the air inlet section 12. The base 44 extends outwardly from the lower end 40 of the side wall 16. In this example, the base 44 is in the form of an annular plate having a circular outer edge having a diameter which is around twice the diameter of the side wall 16.

The height of the fan assembly 10 is in the range from 150 to 250 mm, and in this example is around 210 mm. The diameter of the base 44 is in the range from 100 to mm and in this example is around 130 mm. The diameter of the opening 26 defined by the air outlet section 14 increases from the rear of the fan assembly 10 towards the front of the fan assembly 10, and in this example the diameter varies from around 90 mm at the rear of the fan assembly 10 to around 130 mm at the front of the fan assembly 10. The fan assembly 10 is thus dimensioned to be locatable readily on a desk or other work surface, or on a shelf, ledge or other similar surface.

With reference now to Figure 3, the air inlet section 12 houses a motor and impeller unit, indicated generally at 46 in Figure 3, for drawing the primary air flow through the air inlet 18 and into the bore 42. As illustrated in Figure 4, the motor and impeller unit 46 comprises an impeller 48 connected to a rotary shaft 50 extending outwardly from a motor 52. In this embodiment, in use the motor 52 draws less than 10 W of power, preferably less than 5 W of power. The impeller 48, shaft 50 and motor 52 are preferably contained within a motor and impeller unit 46 which is inserted into the air inlet section 12 through the open lower end 40 of the side wall 16. The air inlet section 12 includes an annular diffuser 54 having a plurality of blades for receiving the primary air flow exhausted from the impeller 48 and for guiding the air flow into the air outlet section 14. The diffuser 54 may be integral with the motor and impeller unit 46, or, as in this example, it may be a separate component inserted into the air inlet section 12 before the motor and impeller unit 46 so that it is located adjacent the upper open end 34 of the side wall 16, and is supported by the upper end of the motor and impeller unit 46. The body of the fan assembly 10 may include a ledge 55 extending inwardly from an inner surface of the body to prevent the diffuser 54 from passing beyond the open upper end 34 of the side wall 16.

The motor and impeller unit 46 is supported within the air inlet section 12 by a support 56. The support 56 comprises a generally tubular frame 58 which is co-axial with the side wall 16, and which comprises a plurality of apertures 60 through which the primary air flow passes between the air inlet 18 and the impeller 48. The motor and impeller unit 46 is supported by the upper end of the support 56. The support 56 also retains a power supply circuit 62 which is connected to the motor 52 for providing a driving voltage to the motor 52. Similar to the motor and impeller unit 46, the support 56 is inserted into the air inlet section 12 through the open lower end 40 of the side wall 16.

The support 56 preferably has a support base 64 which serves to close the open lower end 40 of the side wall 16 when the support 56 is inserted fully into the bore 42 of the side wall 16. Alternatively, the support base 64 may be a separate component which is inserted into the bore 42 of the side wall 16 after the support 56. The outer surface of the support base 64 may connect to the side wall 16 by a snap-fit connection.

Alternatively, the support base 64 may be secured to the side wall 16 or to the base 44 using screws or other fasteners.

The support 56 preferably comprises a plurality of resilient retainers 66 for retaining the circuit 62. The circuit 62 comprises an input terminal 68 for receiving a direct current (DC) voltage, preferably in the range from 4 to 13 "/, from an external power source. In this example, the input terminal 68 is configured for connection to an adapter (not shown) for converting an alternating current (AC) voltage, such as a 110 or 220 AC voltage provided by a mains power supply, to a DC voltage, for example a 4.8 V DC voltage. With reference to Figure 5, the input terminal 68 is positioned on the circuit 62 so as to be located within a slot 70 formed in the open lower end 40 of the side wall 16 when the support 56 is inserted into the air inlet section 12. The slot 70 is preferably located at or towards the rear of the fan assembly 10.

The circuit 62 also includes a switch 72 for allowing a user to selectively activate and de-activate the motor 52. The switch 72 may protrude through an aperture 74 located on the front of the side wall 16, generally opposite to the input terminal 68, and may be connected to the circuit 62 following the insertion of the circuit 62 into the air inlet section 12. The switch 72 may be in the form of a depressible or rotatable onloff switch, or ft may be in the form of a dial for allowing the user to vary the speed of rotation of the impeller 48. The circuit 62 may include a light emitting diode (LED) or other illuminating device for illuminating a portion of the side wall 16 which surrounds the switch 72 when the fan assembly 10 is switched on.

To operate the fan assembly 10 the user connects the input terminal 68 to the mains supply using the adapter, and presses the switch 72. In response, the circuit 62 activates the motor 52 to rotate the impeller 48. The rotation of the impeller 48 causes a primary air flow to be drawn into the air inlet section 12 through the air inlet 18. The primary air flow passes sequentially through the apertures 60 of the support 56 and through the motor and impeller unit 46 before passing through the open upper end 34 of the side wall 16 and into the air outlet section 14.

Within the air outlet section 14, the primary air flow is divided into two air streams which pass in opposite directions around the opening 26 of the air outlet section 14. As the air streams pass through the interior passage 32, air is emitted through the air outlet 20. The primary air flow emitted from the air outlet 20 is directed over the Coanda surface 36 of the air outlet section 14, causing a secondary air flow to be generated by the entrainment of air from the external environment, specifically from the region around the air outlet 20 and from around the rear of the air outlet section 14. This secondary air flow passes through the opening 26 of the air outlet section 14, where ft combines with the primary air flow to produce a total air flow, or air current, projected forward from the air outlet section 14.

Claims

CLAIMS1. A fan assembly comprising: a body comprising an air inlet, an impeller, and a motor for driving the impeller to drawn an air flow through the air inlet; and an air outlet section comprising an outer section which is integral with part of the body, and an inner section located within the outer section, the inner and outer sections defining an air passage for receiving the air flow from the body, an air outlet for emitting the air flow from the fan assembly, and an opening through which the air from outside the fan assembly is drawn by the air flow emitted from the air outlet.
2. A fan assembly as claimed in claim 1, wherein the body comprises a side wall, the side wall comprising the air inlet of the body.
3. A fan assembly as claimed in claim 2, wherein the side wall extends about the motor and the impeller of the body.
4. A fan assembly as claimed in claim 2 or claim 3, wherein the outer section of the air outlet section is integral with the side wall of the body.
5. A fan assembly as claimed in any of claims 2 to 4, comprising a support for supporting the motor and the impeller, and wherein the side wall comprises a bore into which the support is inserted.
6. A fan assembly as claimed in claim 5, wherein the support comprises a frame.
7. A fan assembly as claimed in claim 6, wherein the frame has a closed lower end.
8. A fan assembly as claimed in claim 6 or claim 7, wherein the frame is substantially co-axial with the side wall of the body.
9. A fan assembly as claimed in any of claims 6 to 8, wherein the frame comprises a plurality of apertures through which the air flow passes between the air inlet and the impeller.
10. A fan assembly as claimed in any of claims 5 to 9, comprising a power supply circuit mounted on the support for providing a driving vohage to the motor.
11. A fan assembly as claimed in any of claims 2 to 10, wherein the body comprises a base for supporting the fan assembly, and wherein the base is integral with the side wall.
12. A fan assembly as claimed in any of claims 2 to 11, wherein the side wall comprises an input terminal for receiving a direct current voltage in the range from 4 to 12 V from an extemal power source.
13. A fan assembly as claimed in any of the preceding claims, wherein the opening has a generally circular profile.
14. A fan assembly as claimed in claim 13, wherein the diameter of the opening is less than 15 cm.
15. A fan assembly as claimed in any of the preceding claims, wherein the fan assembly has a height which is less than 250 mm.
16. A fan assembly substantially as herein described with reference to the accompanying drawings.