AU2017258875A1

AU2017258875A1 - A fan assembly

Info

Publication number: AU2017258875A1
Application number: AU2017258875A
Authority: AU
Inventors: Joseph HODGETTS; Roy POULTON
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2013-03-11
Filing date: 2017-11-08
Publication date: 2017-11-30
Anticipated expiration: 2034-02-03
Also published as: AU2014229860B2; EP2971996B1; CA2900565A1; JP5749825B2; EP2971996A1; US20140255173A1; GB201600966D0; CN104047908B; GB2536767A; WO2014140518A1; CN203743091U; GB201304338D0; GB2511757B; JP2014173604A; AU2017258875B2; RU2015143195A; GB2511757A; RU2659947C2; HK1223996A1; AU2014229860A1

Abstract

A nozzle for a fan assembly includes an air inlet, an air outlet, an interior passage for conveying air from the air inlet to the air outlet, an annular inner wall, and an outer wall 5 extending about the inner wall. The interior passage is located between the inner wall and the outer wall. The inner wall at least partially defines a bore through which air from outside the nozzle is drawn by air emitted from the air outlet. The air outlet is arranged to direct air over an external surface at least partially defining the bore. A flow control port is located downstream from that surface. A flow control chamber is 10 provided for conveying air to the flow control port. A control mechanism selectively enables a flow of air through the flow control port to deflect an air flow emitted from the air outlet. (Figure 7) ---172 92108 106 108 226-l

Description

A FAN ASSEMBLY FIELD OF THE INVENTION

The present invention relates to a nozzle for a fan assembly, and a fan assembly comprising such a nozzle.

BACKGROUND OF THE INVENTION

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. A conventional domestic fan typically includes a set of blades or vanes mounted for rotation about an axis, and drive apparatus for rotating the set of blades to generate an air flow. The movement and circulation of the air flow creates a 'wind chill' or breeze and, as a result, the user experiences a cooling effect as heat is dissipated through convection and evaporation. The blades are generally located within a cage which allows an air flow to pass through the housing while preventing users from coming into contact with the rotating blades during use of the fan. US 2,488,467 describes a fan which does not use caged blades to project air from the fan assembly. Instead, the fan assembly comprises a base which houses a motor-driven impeller for drawing an air flow into the base, and a series of concentric, annular nozzles connected to the base and each comprising an annular outlet located at the front of the nozzle for emitting the air flow from the fan. Each nozzle extends about a bore axis to define a bore about which the nozzle extends.

Each nozzle is in the shape of an airfoil. An airfoil may be considered to have a leading edge located at the rear of the nozzle, a trailing edge located at the front of the nozzle, and a chord line extending between the leading and trailing edges. In US 2,488,467 the chord line of each nozzle is parallel to the bore axis of the nozzles. The air outlet is located on the chord line, and is arranged to emit the air flow in a direction extending away from the nozzle and along the chord line.

Another fan assembly which does not use caged blades to project air from the fan assembly is described in WO 2010/100451. This fan assembly comprises a cylindrical base which also houses a motor-driven impeller for drawing a primary air flow into the base, and a single annular nozzle connected to the base and comprising an annular mouth through which the primary air flow is emitted from the fan. The nozzle defines an opening through which air in the local environment of the fan assembly is drawn by the primary air flow emitted from the mouth, amplifying the primary air flow. The nozzle includes a Coanda surface over which the mouth is arranged to direct the primary air flow. The Coanda surface extends symmetrically about the central axis of the opening so that the air flow generated by the fan assembly is in the form of an annular jet having a cylindrical or frusto-conical profile.

The user is able to change the direction in which the air flow is emitted from the nozzle in one of two ways. The base includes an oscillation mechanism which can be actuated to cause the nozzle and part of the base to oscillate about a vertical axis passing through the centre of the base so that that air flow generated by the fan assembly is swept about an arc of around 180°. The base also includes a tilting mechanism to allow the nozzle and an upper part of the base to be tilted relative to a lower part of the base by an angle of up to 10° to the horizontal.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a nozzle for a fan assembly, the nozzle comprising an air inlet; an air outlet; an interior passage for conveying air from the air inlet to the air outlet; an annular inner wall; an outer wall extending about the inner wall, the interior passage being located between the inner wall and the outer wall, the inner wall at least partially defining a bore through which air from outside the nozzle is drawn by air emitted from the air outlet, the air outlet being arranged to direct air over an external surface of the nozzle; a flow control port located downstream from the air outlet and said surface; a flow control chamber for conveying air to the flow control port; and control means for selectively inhibiting a flow of air through the flow control port.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

Through varying a flow of air through the flow control port, the profile of the air flow emitted from the air outlet can be changed. The variation of the flow of air through the flow control port can have the effect of changing a pressure gradient across the air flow emitted from an air outlet of the nozzle. The change in the pressure gradient can result in the generation of a force that acts on the air flow emitted from the air outlet. The action of this force can result in the air flow moving in a desired direction.

The external surface over which the air outlet is arranged to direct air preferably at least partially defines the bore. The external surface preferably extends at least partially about the axis of the bore. This surface may surround the axis of the bore. The external surface preferably comprises a curved Coanda surface located immediately downstream from the air outlet. The external surface preferably comprises a diffuser surface which tapers outwardly relative to an axis of the bore. This diffuser surface is preferably located downstream from the curved Coanda surface. The diffuser surface may be frusto-conical in shape, or it may be curved.

The nozzle preferably comprises a guide surface located between the air outlet and the flow control port for guiding the air emitted from the air outlet in a desired direction. The guide surface preferably forms part of the external surface over which air is directed by the air outlet. The guide surface is preferably located between the diffuser surface and the flow control port. The guide surface is preferably angled relative to the diffuser surface. In a preferred embodiment, the guide surface is preferably shaped to taper inwardly relative to the diffuser surface, and preferably relative also to the axis of the bore. The guide surface may be faceted, with each facet being either straight or curved. The flow control port is preferably located adjacent to the guide surface. Preferably, the flow control port is located immediately downstream from the guide surface. The guide surface preferably extends at least partially about the bore, and more preferably surrounds the bore.

The nozzle preferably comprises an air flow guiding member, which may be connected to the inner wall of the nozzle. The guide surface is preferably defined by an external surface of the air flow guiding member. The air flow guiding member may at least partially define the flow control port. In a preferred example, the flow control port is located between an internal surface of the air flow guiding member, and an external surface of a third wall of the nozzle. This third wall of the nozzle is preferably a front wall of the nozzle. The front wall of the nozzle is preferably connected to at least one of the inner wall and the outer wall of the nozzle.

The flow control port is preferably arranged to direct an air flow over a second external surface of the nozzle. This second external surface of the nozzle is preferably part of the external surface of the front wall of the nozzle. The second external surface may at least partially define the bore of the nozzle, more preferably a front section of the bore of the nozzle. The second external surface preferably comprises a second Coanda surface located immediately downstream from the flow control port. The second external surface preferably comprises a second diffuser surface which tapers outwardly relative to an axis of the bore. The second diffuser surface may be frusto-conical, or it may be curved.

The nozzle preferably comprises a second guide surface located downstream from the flow control port for guiding the air emitted from the flow control port in a desired direction. The second guide surface is preferably angled relative to the guide surface located downstream from the air outlet. This second guide surface may be located downstream from the second diffuser surface. Alternatively, the second diffuser surface may be considered to form at least part of this second guide surface; for example a part of the second diffuser surface located remote from the flow control port may be considered to provide this second guide surface. The second guide surface may be angled relative to the second diffuser surface. The second guide surface is preferably angled relative to the guide surface located downstream from the air outlet. The guide surface located downstream from the air outlet is referred hereafter as the first guide surface.

When air is emitted from the air outlet, it will tend to become attached to one or more of the surfaces located downstream from the air outlet. In a preferred example, these surfaces include at least the diffuser surface located downstream from the air outlet, and the first guide surface located downstream from the diffuser surface. The first guide surface is preferably contiguous with the diffuser surface so that the air attaches to the first guide surface as it flows away from the diffuser surface. The shape of the first guide surface directs the air flow away from the external surface of the front wall of the nozzle.

The direction in which air is emitted from the nozzle tends to depend on the shape of the final external surface to which the air flow is attached. When the flow of air through the flow control port is inhibited, for example by occluding the flow control port or by inhibiting the flow of air through the flow control chamber connected to the flow control port, the shape of the first guide surface is preferably such that this air flow is guided away from the second external surface of the nozzle, and thus away from the second guide surface of the nozzle. Consequently, when the flow of air through the flow control port is inhibited the direction in which the air is emitted from the nozzle will depend on the shape of the first guide surface of the nozzle.

When air is emitted from the flow control port simultaneously with the emission of air from the air outlet, the air emitted from the flow control port will tend to become attached to the second external surface located downstream from the flow control port. The emission of air from the flow control port changes the pressure gradient across the air flow emitted from the air outlet. For example, a relatively low pressure may be created adjacent to the part of the second external surface located immediately downstream from the flow control port, and thus on one side of the air flow emitted from the air outlet. The pressure differential thus created across the air flow emitted from the air outlet generates a force which urges that air flow towards the second external surface. This can result in both the air emitted from the air outlet and the air emitted from the flow control port becoming attached to the second external surface of the nozzle. As mentioned above, the direction in which air is emitted from the nozzle depends on the shape of the final surface to which the air flow is attached, and so in this case the direction in which the air is emitted from the nozzle will depend on the shape of the second guide surface of the nozzle.

When the flow of air through the flow control port is subsequently inhibited, the pressure different across the air flow emitted from the air outlet is removed. As there is no longer any force pushing the air flow towards the second external surface, the air flow preferably becomes detached from that surface, and so the direction in which the air is emitted from the nozzle depends, once again, on the shape of the first guide surface of the nozzle.

Thus, through variation of an air flow from a flow control port the air flow emitted from the air outlet may become selectively attached to either one guide surface or two guide surfaces of the nozzle.

In a second aspect, the present invention provides a nozzle for a fan assembly, the nozzle comprising an air inlet; an air outlet; an interior passage for conveying air from the air inlet to the air outlet; an annular inner wall; an outer wall extending about the inner wall, the interior passage being located between the inner wall and the outer wall, the inner wall at least partially defining a bore through which air from outside the nozzle is drawn by air emitted from the air outlet, a first guide surface located downstream from the air outlet; a flow control port located downstream from the first guide surface; a second guide surface located downstream from the flow control port, the second guide surface being angled relative to the first guide surface; a flow control chamber for conveying air to the flow control port; and control means for selectively inhibiting a flow of air through the flow control port. Through selectively inhibiting the flow of air through the flow control port, the air emitted from the air outlet may become detached from the second guide surface.

As mentioned above, the flow control port is preferably arranged to direct an air flow over a second external surface of the nozzle. When air is emitted from the flow control port simultaneously with the emission of air from the air outlet, the air emitted from both the air outlet and the flow control port will tend to become attached to the second external surface located downstream from the flow control port. However, the nozzle may be arranged in an alternative manner so that when the flow of air through the flow control port is inhibited the air emitted from the air outlet becomes attached to the second external surface, and when the flow of air through the flow control port is enabled the air emitted from the air outlet becomes detached from the second external surface. For example, the flow control port may be arranged to direct a flow control air flow inwardly, for example radially inwardly, towards a vertical plane extending through, and containing, the bore axis. As the flow control air flow is emitted from the flow control port, the air emitted from the air outlet is deflected away from the second external surface of the nozzle. Consequently, when the flow of air through the flow control port is enabled the direction in which the air is emitted from the nozzle will depend on the shape of the first guide surface of the nozzle.

The air outlet is preferably in the form of a slot. The interior passage preferably surrounds the bore of the nozzle. The air outlet preferably extends at least partially about the bore. For example, the nozzle may comprise a single air outlet which extends at least partially about the bore. For example, the air outlet also may surround the bore. The bore may have a circular cross-section in a plane which is perpendicular to the bore axis, and so the air outlet may be circular in shape. Alternatively, the nozzle may comprise a plurality of air outlets which are spaced about the bore.

The nozzle may be shaped to define a bore which has a non-circular cross-section in a plane which is perpendicular to the bore axis. For example, this cross-section may be elliptical or rectangular. The nozzle may have two relatively long straight sections, an upper curved section and a lower curved section, with each curved section joining respective ends of the straight sections. Again, the nozzle may comprise a single air outlet which extends at least partially about the bore. For example, each of the straight sections and the upper curved section of the nozzle may comprise a respective part of this air outlet. Alternatively, the nozzle may comprise two air outlets each for emitting a respective part of an air flow. Each straight section of the nozzle may comprise a respective one of these two air outlets.

The air emitted from the nozzle, hereafter referred to as a primary air flow, entrains air surrounding the nozzle, which thus 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 nozzle. The primary air flow combines with the entrained secondary air flow to form a combined, or total, air flow projected forward from the front of the nozzle.

The variation of the direction in which the primary air flow is emitted from the nozzle can vary the degree of the entrainment of the secondary air flow by the primary air flow, and thus vary the flow rate of the combined air flow generated by the fan assembly.

Without wishing to be bound by any theory, we consider that the rate of entrainment of the secondary air flow by the primary air flow may be related to the magnitude of the surface area of the outer profile of the primary air flow emitted from the nozzle. For a given flow rate of air entering the nozzle, when the primary air flow is outwardly tapering, or flared, the surface area of the outer profile is relatively high, promoting mixing of the primary air flow and the air surrounding the nozzle and thus increasing the flow rate of the combined air flow, whereas when the primary air flow is inwardly tapering, the surface area of the outer profile is relatively low, decreasing the entrainment of the secondary air flow by the primary air flow and so decreasing the flow rate of the combined air flow. The inducement of a flow of air though the bore of the nozzle may also be impaired.

Increasing the flow rate, as measured on a plane perpendicular to the bore axis and offset downstream from the plane of the air outlet, of the combined air flow generated by the nozzle - by changing the direction in which the air flow is emitted from the nozzle - has the effect of decreasing the maximum velocity of the combined air flow on this plane. This can make the nozzle suitable for generating a relatively diffuse flow of air through a room or an office. On the other hand, decreasing the flow rate of the combined air flow generated by the nozzle has the effect of increasing the maximum velocity of the combined air flow. This can make the nozzle suitable for generating a flow of air for cooling rapidly a user located in front of the nozzle. The profile of the air flow generated by the nozzle can be rapidly switched between these two different profiles through selectively enabling or inhibiting the passage of an air flow through the flow control chamber.

The geometry of the air outlet(s) and the guide surface(s) may, at least in part, control the two different profiles for the air flow generated by the nozzle. For example, when viewed in a cross-section along a plane passing through the bore axis and located generally midway between the upper and lower ends of the nozzle, the shape of the first guide surface may be different from the shape of the second guide surface. For example, in this cross-section the angle subtended between the bore axis and the first guide surface may be smaller than the angle subtended between the bore axis and the second guide surface.

The control means preferably has a first state which inhibits a flow of air through the flow control port, and a second state which allows the flow of air through the flow control port. The control means may be in the form of a valve comprising a valve body for occluding an air inlet of the flow control chamber, and an actuator for moving the valve body relative to the inlet. Alternatively, the valve body may be arranged to occlude the flow control port. The valve may be a manually operable valve which is pushed, pulled or otherwise moved by a user between these two states. In one embodiment, the actuator is driven by a motor. The motor is preferably driven by a controller or control circuit of the nozzle. This control circuit may be a main control circuit of the fan assembly. Alternatively, this control circuit may be a second control circuit connected to a main control circuit of the fan assembly. The main control circuit is preferably arranged to drive the motor in response to a signal received from a user interface of the fan assembly. This user interface may comprise a button or other user-actuable member located on the body of the fan assembly which is actuated by a user to drive the motor. Alternatively, or additionally, the fan assembly may comprise a remote control for transmitting a signal instructing the main control circuit to actuate the motor to change the state of the control means.

The flow control chamber may have an air inlet located on an external surface of the nozzle. In this case, all of the air flow received by the interior passage may be emitted from the air outlet(s). However, the flow control chamber is preferably arranged to receive a flow control air flow from the interior passage. In this case, a first portion of the air flow received by the interior passage may be selectively allowed to enter the flow control chamber to form the flow control air flow, with the remainder of the air flow being emitted from the interior passage through the air outlet(s) to recombine with the flow control air flow downstream from the air outlet(s).

The interior passage may be separated from the flow control chamber by an internal wall of the nozzle. This wall preferably includes the air inlet of the flow control chamber. The air inlet of the flow control chamber is preferably located towards the base of the nozzle through which the air flow enters the nozzle.

The flow control chamber may extend through the nozzle adjacent to the interior passage. Thus, the flow control chamber may extend at least partially about the bore of the nozzle, and may surround the bore.

The interior passage may comprise means for heating at least part of the air flow received by the nozzle.

In a third aspect, the present invention provides a fan assembly comprising an impeller, a motor for rotating the impeller to generate an air flow, a nozzle as aforementioned for receiving the air flow, and a controller for controlling the motor and for changing the state of the control means. The controller may be arranged to adjust the speed of the motor as the state of the control means is changed. For example, the motor controller may be arranged to reduce the speed of the motor when the state of the control means is changed to produce a focused air flow, and to increase the speed of the motor when the state of the control means is changed to produce a diffuse air flow.

Features described above in connection with the first aspect of the invention are equally applicable to each of the second and third aspects of the invention, and vice versa.

BRIEF DESCRIPTION OF THE INVENTION

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a front view of a fan assembly;

Figure 2 is a vertical cross-sectional view of the fan assembly, taken along line A-A in Figure 1;

Figure 3 is a left perspective view, from above, of a nozzle of the fan assembly;

Figure 4 is an exploded view of the nozzle;

Figure 5 is an exploded view of a rear casing section of the nozzle;

Figure 6 is a front view of the nozzle;

Figure 7 is a horizontal cross-section of the nozzle, taken along line B-B in Figure 6; Figure 8 is a left perspective view, from below, of the nozzle; and Figure 9 is a bottom view of the nozzle.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 is an external view of a fan assembly 10. In this example, the fan assembly 10 is the form of a fan heater. The fan assembly 10 comprises a body 12 comprising an air inlet 14 through which an air flow enters the fan assembly 10, and an annular nozzle 16 mounted on the body 12. The nozzle 16 comprises air outlets 18 for emitting air from the fan assembly 10.

The body 12 comprises a substantially cylindrical main body section 20 mounted on a substantially cylindrical lower body section 22. The main body section 20 and the lower body section 22 preferably have substantially the same external diameter so that the external surface of the main body section 20 is substantially flush with the external surface of the lower body section 22. The main body section 20 comprises the air inlet 14 through which air enters the fan assembly 10. In this embodiment the air inlet 14 comprises an array of apertures formed in the main body section 20. Alternatively, the air inlet 14 may comprise one or more grilles or meshes mounted within windows formed in the main body section 20.

Figure 2 illustrates a sectional view through the fan assembly 10. The lower body section 22 comprises a user interface of the fan assembly 10. The user interface comprises a user operable actuator or button 24 to control various functions of the fan assembly 10, and a user interface control circuit 26 connected to the button 24. The fan assembly 10 may comprise a remote control (not shown) for transmitting control signals to the user interface circuit 26 of the fan assembly 10. In overview, the remote control comprises a plurality of buttons which are depressible by the user, and a control unit for generating and transmitting infrared light signals in response to depression of one of the buttons. The infrared light signals are emitted from a window located at one end of the remote control. The control unit is powered by a battery located within a battery housing of the remote control. The user interface circuit 26 comprises a sensor or receiver 28 for receiving signals transmitted by the remote control, and a display 30 for displaying a current operational setting of the fan assembly 10. For example, the display 30 may normally indicate a temperature setting selected by a user. The receiver 28 and the display 30 may be located immediately behind a transparent or translucent part 32 of the outer wall of the lower body section 22. The lower body section 22 is mounted on a base 34 for engaging a surface on which the fan assembly 10 is located. The base 34 includes an optional base plate 36.

The lower body section 22 houses a main control circuit, indicated generally at 38, connected to the user interface circuit 26. In response to operation of the button 24 or the receipt of a signal from the remote control, the user interface circuit 26 is arranged to transmit appropriate signals to the main control circuit 38 to control various operations of the fan assembly 10.

The lower body section 22 also houses a mechanism, indicated generally at 40, for oscillating the lower body section 22 relative to the base 34. The operation of the oscillating mechanism 40 is controlled by the main control circuit 38 in response to the user operation of one of the buttons of the remote control. The range of each oscillation cycle of the lower body section 22 relative to the base 34 is preferably between 60° and 180°, and in this embodiment is around 70°. A mains power cable 42 for supplying electrical power to the main control circuit 38 of the fan assembly 10 extends through an aperture formed in the base 34. The cable 42 is connected to a plug 44 for connection to a mains power supply.

The main body section 20 comprises a duct 50 having a first end defining an air inlet 52 of the duct 50 and a second end located opposite to the first end and defining an air outlet 54 of the duct 50. The duct 50 is aligned within the body 12 so that the longitudinal axis of the duct 50 is collinear with the longitudinal axis of the body 12, and so that the air inlet 52 is located beneath the air outlet 54.

The duct 50 extends about an impeller 56 for drawing the primary air flow into the body 12 of the fan assembly 10. The impeller 56 is a mixed flow impeller. The impeller 56 comprises a generally conical hub, a plurality of impeller blades connected to the hub, and a generally frusto-conical shroud connected to the blades so as to surround the hub and the blades. The blades are preferably integral with the hub, which is preferably formed from plastics material.

The impeller 56 is connected to a rotary shaft 58 extending outwardly from a motor 60 for driving the impeller 56 to rotate about a rotational axis which is collinear with the longitudinal axis of the duct 50. In this example, the motor 60 is a brushless DC motor having a speed which is variable by a brushless DC motor driver of the main control circuit 38. The user may adjust the speed of the motor 60 using the button 24 or the remote control. In this example, the user is able to select one of ten different speed settings. The number of the current speed setting is displayed on the display 30 as the speed setting is changed by the user.

The motor 60 is housed within a motor housing. The outer wall of the duct 50 surrounds the motor housing, which provides an inner wall of the duct 50. The walls of the duct 50 thus define an annular air flow path which extends through the duct 50. The motor housing comprises a lower section 62 which supports the motor 60, and an upper section 64 connected to the lower section 62. The shaft 58 protrudes through an aperture formed in the lower section 62 of the motor housing to allow the impeller 56 to be connected to the shaft 58. The motor 60 is inserted into the lower section 62 of the motor housing before the upper section 64 is connected to the lower section 62. The lower section 62 of the motor housing is generally frusto-conical in shape, and tapers inwardly in a direction extending towards the air inlet 52 of the duct 50. The upper section 64 of the motor housing is generally frusto-conical in shape, and tapers inwardly towards the air outlet 54 of the duct 50. An annular diffuser 66 is located between the outer wall of the duct 50 and the upper section 64 of the motor housing. The diffuser 66 comprises a plurality of blades for guiding the air flow towards the air outlet 54 of the duct 50. The shape of the blades is such that the air flow is also straightened as it passes through the diffuser 66. A cable for conveying electrical power from the main control circuit 38 to the motor 60 passes through the outer wall of the duct 50, the diffuser 66 and the upper section 64 of the motor housing. The upper section 64 of the motor housing is perforated, and the inner surface of the upper section 64 of the motor housing may be lined with noise absorbing material, preferably an acoustic foam material, to suppress broadband noise generated during operation of the fan assembly 10.

The duct 50 is mounted on an annular seat 68 located within the body 12. The seat 68 extends radially inwardly from the inner surface of the main body section 20 so that an upper surface of the seat 68 is substantially orthogonal to the rotational axis of the impeller 56. An annular seal 70 is located between the duct 50 and the seat 68. The annular seal 70 is preferably a foam annular seal, and is preferably formed from a closed cell foam material. The annular seal 70 has a lower surface which is in sealing engagement with the upper surface of the seat 68, and an upper surface which is in sealing engagement with the duct 50. The seat 68 comprises an aperture to enable the cable (not shown) to pass to the motor 60. The annular seal 70 is shaped to define a recess to accommodate part of the cable. One or more grommets or other sealing members may be provided about the cable to inhibit the leakage of air through the aperture, and between the recess and the internal surface of the main body section 20.

With reference to Figure 3, the nozzle 16 has an annular shape. The nozzle 16 extends about a bore axis X to define a bore 80 of the nozzle 16. In this example, the bore 80 has a generally elongate shape, having a height (as measured in a direction extending from the upper end of the nozzle to the lower end of the nozzle 16) which is greater than the width of the nozzle 16 (as measured in a direction extending between the side walls of the nozzle 16). The nozzle 16 comprises a base 82 which is connected to the open upper end of the main body section 20 of the body 12.

Figures 4 and 5 illustrate exploded views of the nozzle 16. The nozzle 16 comprises an annular rear casing section 84, an annular front casing section 86, and an annular air guiding section 88 located between the rear casing section 84 and the front casing section 86. While each of the front casing section 86 and the air guiding section 88 is illustrated here as being formed from a single component, one or more of these sections of the nozzle 16 may be formed from a plurality of components connected together, for example using an adhesive.

The rear casing section 84 comprises an annular outer casing section 90 connected to and extending about an annular inner casing section 92. Again, each of these sections may be formed from a plurality of connected parts, but in this embodiment each of the casing sections 90, 92 is formed from a respective, single moulded part. The outer casing section 90 comprises the base 82 of the nozzle 16. With reference also to Figures 6 and 7, the outer casing section 90 and the inner casing section 92 together define an annular interior passage 94 of the nozzle 16. The interior passage 94 extends about the bore 80 of the nozzle 16, and thus comprises two relatively straight sections each adjacent a respective elongate side of the bore 80, an upper curved section joining the upper ends of the straight sections, and a lower curved section joining the lower ends of the straight sections. The interior passage 94 is bounded by the internal surface 96 of the outer casing section 90 and the internal surface 98 of the inner casing section 92. The base 82 comprises an air inlet 100 through which air enters the lower curved section of the interior passage 94 from the body 12.

The rear casing section 84 of the nozzle 16 houses a pair of heater assemblies 104. Each heater assembly 104 comprises a row of heater elements 106 arranged side-byside. The heater elements 106 are preferably formed from positive temperature coefficient (PTC) ceramic material. The row of heater elements is sandwiched between two heat radiating components 108, each of which comprises an array of heat radiating fins located within a frame. The heat radiating components 108 are preferably formed from aluminium or other material with high thermal conductivity (around 200 to 400 W/mK), and may be attached to the row of heater elements 106 using beads of silicone adhesive, or by a clamping mechanism. The side surfaces of the heater elements 106 are preferably at least partially covered with a metallic film to provide an electrical contact between the heater elements 106 and the heat radiating components 108. This film may be formed from screen printed or sputtered aluminium. Electrical terminals located at the ends of the heater assemblies 104 are connected to a loom 110 for supplying electrical power to the heater assemblies 104. The loom 110 is in turn connected to a heater control circuit 112 located in the base 82 of the nozzle 16 for activating the heater assemblies 104. The heater control circuit 112 is in turn controlled by control signals supplied thereto by the main control circuit 38. The heater control circuit 112 comprises two triac circuits to control the heater elements 106 of the heater assemblies 104. A thermistor for providing an indication of the temperature of air entering the fan assembly 10 is connected to the heater control circuit 112. The thermistor may be located immediately behind the air inlet 14, but preferably it is located within the base 82 of the nozzle 16 so as to be connected readily to the heater control circuit 112. A thermal fuse and, optionally, a thermal cut out are located electrically between each heater assembly 104 and the heater control circuit 112.

The user may set a desired room temperature or temperature setting by pressing a button of the remote control. Depending on the current operational mode of the fan assembly 10, as discussed in more detail below, the user interface control circuit 26 may display a temperature currently selected by the user on the display 30, which temperature may correspond to a desired room air temperature. As the user changes the speed setting for the motor 60, the user interface control circuit 26 may display temporarily the speed setting currently selected by the user on the display 30 for a brief period of time, for example a few seconds, before returning to the display of the temperature selected by the user.

The heater assemblies 104 are each retained within a respective straight section of the interior passage 94 by a chassis 120. The chassis 120 comprises a pair of heater housings into which the heater assemblies 104 are inserted. The heater housings are defined by a pair of elongate inner walls 122 of an annular body 124, and a pair of elongate outer walls 126 which are each connected to a respective elongate inner wall 122, for example by using screws. The inner walls 122 are connected together by upper and lower curved portions 128, 130 of the annular body 124. The walls 122, 126 are shaped so that the heater housings are open at the front and rear ends thereof. The walls 122, 126 thus define two first air flow channels 132 within the interior passage 94.

The rear end of the inner casing section 92 comprises upper and lower curved flanges 134, 136. Each flange 134, 136 is shaped to retain a respective curved sealing member 138, 140. Each sealing member 138, 140 is arranged to engage a respective U-shaped protrusion 142, 144 extending forwardly from the upper and lower sections of the rear ends of the outer casing section 90 to form a seal therewith. During assembly of the nozzle 16, the annular body 124 is pushed over the rear end of the outer casing section 90 so that each curved portion 128, 130 of the annular body 124 engages a respective flange 134, 136. The sealing members 138, 140 are then pushed into the flanges 134, 136 so that the curved portions 128, 130 of the annular body 124 are sandwiched between the outer casing section 90 and the sealing members 138, 140. This is shown in Figure 2. Returning to Figure 7, the inner walls 122 of the chassis 120 are shaped so that the rear ends 146 of the inner walls 122 wrap around the rear ends 148 of the elongate sections of the inner casing section 92. The inner surface 98 of the inner casing section 92 comprises a first set of raised spacers 150 which engage the inner walls 122 to space the inner walls 122 from the inner surface 98 of the inner casing section 92. The rear ends 146 of the inner walls 122 comprise a second set of spacers 152 which engage the external surface 154 of the inner casing section 92 to space the rear ends 146 of the inner walls 122 from the external surface 154 of the inner casing section 92.

The inner walls 122 of the chassis 120 and the inner casing section 92 thus define two second air flow channels 156 within the interior passage 94. Each of the second flow channels 156 extends along the inner surface 98 of the inner casing section 92, and around the rear end 146 of the inner casing section 92. Each second flow channel 156 is separated from a respective first flow channel 128 by an inner wall 122 of the chassis 120. Each second flow channel 156 terminates at an air outlet 158 located between the external surface 154 of the inner casing section 92 and the rear end 146 of the inner wall 122. Each air outlet 158 is thus in the form of a vertically-extending slot located on a respective side of the bore 80 of the assembled nozzle 16. Each air outlet 158 preferably has a width in the range from 0.5 to 5 mm, and in this example the air outlets 158 have a width of around 1 mm.

With the annular body 124 of the chassis 120 connected to the inner casing section 92, the heater assemblies 104 are placed along the inner walls 122 of the chassis 120 so that lugs 160 located at the upper end of each heater assembly 104 are received within a respective housing 162 formed on the annular body 124. This serves to locate the heater assemblies 104 generally relative to the annular body 124 before the outer walls 126 are connected to the inner walls 122 to retain the heater assemblies 104 within the heater housings defined by the chassis 120. Each of the inner walls 122 and the outer walls 126 comprises a set of ribs 164, 166 which serve to space the heater assemblies 104 from the inner surfaces of the heater housings. This allows air to pass both through the heat radiating components 108 of the heater assemblies 104 and around the heater assemblies 104 as it passes through the first air flow channels 132. The loom 110 is then connected to the heater assemblies 104, and the heater control circuit 112 is connected to the loom 110. The heater control circuit 112 may be supported in a stable position by the inner casing section 92. With reference to Figures 8 and 9, the heater control circuit 112 may be connected to the inner casing section 92 using screws 168 which are inserted through holes formed in a printed circuit board of the heater control circuit 112 and received within bosses 170 formed in the inner casing section 92.

The inner casing section 92 of the nozzle 16 is then inserted into the outer casing section 90 of the nozzle 16. The outer casing section 90 is shaped so that part of the inner surface 96 of the outer casing section 90 extends around the outer walls 126 of the chassis 120. The outer walls 126 have a front end 172 and a rear end 174, and a third set of spacers 176 located on the outer side surfaces of the outer walls 126 and which extend between the ends 172, 174 of the outer walls 126. The spacers 176 are configured to engage the inner surface 96 of the outer casing section 90 to space the outer walls 126 from the inner surface 96 of the outer casing section 90. The outer walls 126 of the chassis 120 and the outer casing section 90 thus define two third air flow channels 178 within the interior passage 94. Each of the third flow channels 178 is located adjacent and extends along the inner surface 96 of the outer casing section 90. Each third flow channel 178 is separated from a respective first flow channel 128 by an outer wall 126 of the chassis 120. Each third flow channel 178 terminates at an air outlet 180 located within the interior passage 94, between the rear end 174 of the outer wall 126 of the chassis 120 and the outer casing section 90. Each air outlet 180 is also in the form of a vertically-extending slot, located within the interior passage 94 of the nozzle 16, and preferably has a width in the range from 0.5 to 5 mm. In this example the air outlets 180 have a width of around 1 mm.

The outer casing section 90 is shaped so as to curve inwardly around part of the rear ends 146 of the inner walls 122 of the chassis 120. The rear ends 146 of the inner walls 122 comprise a fourth set of spacers 182 located on the opposite side of the inner walls 122 to the second set of spacers 152, and which are arranged to engage the inner surface 96 of the outer casing section 90 to space the rear ends 146 of the inner walls 122 from the inner surface 96 of the outer casing section 90. The outer casing section 90 and the rear ends 146 of the inner walls 122 thus define a further two air outlets 184. Each air outlet 184 is located adjacent a respective one of the air outlets 158, with each air outlet 158 being located between a respective air outlet 184 and the external surface 154 of the inner casing section 92. Similar to the air outlets 158, each air outlet 184 is in the form of a vertically-extending slot located on a respective side of the bore 80 of the assembled nozzle 16. The air outlets 184 preferably have the same length as the air outlets 158. Each air outlet 184 preferably has a width in the range from 0.5 to 5 mm, and in this example the air outlets 184 have a width of around 2 to 3 mm. Thus, the air outlets 18 for emitting air from the fan assembly 10 comprise the two air outlets 158 and the two air outlets 184. As mentioned above, the outer casing section 90 comprises a pair of curved protrusions 142, 144 which each engage a respective sealing member 138, 140 to inhibit the emission of air from the upper and lower curved sections of the interior passage 94.

Returning to Figures 2 to 4, the external surface 154 of the inner casing section 92 comprises a convex Coanda surface 190 located adjacent the air outlets 18, and over which the air outlets 18 are arranged to direct the air emitted therefrom. The external surface 154 of the inner casing section 92 further comprises a diffuser surface 192 located downstream of the Coanda surface 190. The diffuser surface 192 is arranged to taper away from the bore axis X of the bore 80 in a direction extending from the air outlets 18 towards the front of the nozzle 16. An angle subtended between the diffuser surface 192 and the bore axis X of the bore 80 - as viewed in a horizontal plane passing through and containing the bore axis X - is in the range between 0 and 25°, and in this example is around 5°.

The inner casing section 92 includes an outwardly flared front surface 194 connected to the diffuser surface 192. The air guiding section 88 of the nozzle 16 is connected to the front surface 194 of the inner casing section 92. In this example, the inner casing section 92 comprises a set of pins 198 spaced about the front surface 194, and the air guiding section 88 comprises a set of apertures 196 similarly spaced about the outer periphery of the air guiding section 88. During assembly, the air guiding section 88 is pushed on to the front surface 194 of the inner casing section 92 so that the pins 198 enter the apertures 196 to guide the location of the air guiding section 88 on to the rear casing section 84. As shown in Figure 7, the rear end 200 of the air guiding section 88 enters a recess 202 located on the front surface 194 of the inner casing section 92 as the air guiding section 88 is pushed on to the rear casing section 84. When the air guiding section 88 is pushed fully on to the rear casing section 84, a front section 204 of the air guiding section 88 protrudes forwardly from the front surface 194 of the inner casing section 92. This front section 204 of the air guiding section 88 comprises an annular guide surface 206 which is located downstream from, and contiguous with, the diffuser surface 192 of the inner casing section 92. The guide surface 206 is arranged to taper towards the bore axis X of the bore 80 in a direction extending from the air outlets 18 towards the front of the nozzle 16. The angle subtended between the guide surface 206 and the bore axis X of the bore 80 - as viewed in a horizontal plane passing through and containing the bore axis X - is in the range between 0 and -25°, and in this example is around -10°.

Following the attachment of the air guiding section 88 to the rear casing section 84, the front casing section 86 is pushed on to the front of the rear casing section 84. The inner surface of the front casing section 86 is shaped to define a first annular recess 210 which receives both the front end 212 of the outer casing section 90 and the front end 214 of the inner casing section 92. An adhesive may be supplied to the recess 210 to secure the front casing section 86 to the rear casing section 84. The inner surface of the front casing section 86 is also shaped to define a second annular recess 216 which receives curved protrusions 218, 219 extending forwardly from the upper end and the lower end respectively of the air guiding section 88. Again, an adhesive may be supplied to the recess 216 to secure the front casing section 86 to the air guiding section 88.

In addition to the interior passage 94, the nozzle 16 defines a flow control chamber 220. The flow control chamber 220 is annular in shape and extends about the bore 80 of the nozzle 16. The flow control chamber 220 thus comprises two relatively straight sections each adjacent a respective elongate side of the bore 80, an upper curved section joining the upper ends of the straight sections, and a lower curved section joining the lower ends of the straight sections. The flow control chamber 220 is bounded by the front surface 194 of the inner casing section 92, the internal surface 222 of the air guiding section 88 and the internal surface 224 of the front casing section 86.

The flow control chamber 220 is arranged to convey air to two flow control ports 226 for emitting air from the straight sections of the flow control chamber 220. The engagement between the recess 216 of the front casing section 86 and the curved protrusions 218, 219 of the air guiding section 88 inhibits the emission of air from the curved sections of the flow control chamber 220. The flow control ports 226 are located immediately downstream from the guide surface 206. Each flow control port 226 is in the form of a vertically-extending slot located on a respective side of the bore 80 of the assembled nozzle 16. The flow control ports 226 preferably have the same length as the air outlets 18. Each flow control port 226 preferably has a width in the range from 0.5 to 5 mm, and in this example the flow control ports 226 have a width of around 1 mm.

The flow control ports 226 are located between the internal surface 222 of the front section 204 of the air guiding section 88 and the external surface 228 of the front casing section 86. A fifth set of spacers 230 is provided on the front casing section 86 and arranged to engage the inner surface 96 of the outer casing section 90 to space the internal surface 222 of the front section 204 of the air guiding section 88 from the external surface 228 of the front casing section 86 in the vicinity of the flow control ports 226.

The flow control ports 226 are arranged to direct air over the external surface 228 of the front casing section 86. The external surface 228 comprises a convex Coanda surface 232 located adjacent the flow control ports 226, and over which the flow control ports 226 are arranged to direct the air emitted therefrom. The external surface 228 of the front casing section 86 further comprises a diffuser surface 234 located downstream of the Coanda surface 232. The diffuser surface 234 is arranged to taper away from the bore axis X of the bore 80 in a direction extending from the flow control ports 226 towards the front of the nozzle 16. An angle subtended between the diffuser surface 234 and the bore axis X of the bore 80 - as viewed in a horizontal plane passing through and containing the bore axis X - is in the range between 20 and 70°, and in this example is around 45°.

With reference now to Figures 4, 5, 8 and 9, air enters the flow control chamber 220 through one or more air inlets 236 formed in the front surface 194 of the inner casing section 92. In this example, the flow control chamber 220 has two air inlets 236. The air inlets 236 are arranged to receive air from the lower curved section of the interior passage 94. The nozzle 16 includes a control mechanism 240 for controlling the flow of air through the flow control chamber 220. In this example, the control mechanism 240 is arranged to selectively inhibit the flow of air through the flow control chamber 220. In other words, the control mechanism 240 has a first state, in which the control mechanism 240 is arranged to inhibit the flow of air through the flow control chamber 220 so that there is substantially no air emitted from the flow control ports 226, and a second state, in which the control mechanism 240 is arranged to allow the flow of air through the flow control chamber 220 so that air is emitted simultaneously from both of the flow control ports 226.

The control mechanism 240 comprises a valve body 242. The valve body 242 is moveable relative to the nozzle 16 as the control mechanism 240 toggles between the first state and the second state. In this example, the valve body 242 comprises a pair of valves 244 for occluding the air inlets 236 to inhibit the flow of air through the flow control chamber 220 when the control mechanism 240 is in the first state. The valves 244 are arranged to engage annular seals 246 attached to the internal surface of the front surface 194 of the inner casing section 92 which prevent air leaking to the air inlets 236 from between the valves 244 and the internal surface of the inner casing section 92 when the control mechanism 240 is in the first state.

The valve body 242 is connected to the inner casing section 92 for movement relative to the nozzle 16. The valve body 242 comprises a pair of fingers 248 at opposite ends thereof, with the end of each finger 248 being received within a housing 250 formed in the internal surface of the front surface 194 of the inner casing section 92. The valve body 242 is thus pivotable relative to the nozzle 16 about a pivot axis which passes through the ends of the fingers 248. The control mechanism 240 comprises an actuator 252 for moving the valve body 242 relative to the nozzle 16. The actuator 252 is in the form of a wire which has one end connected to the valve body 242 and another end connected to a motor 254 for actuating movement of the actuator 252. The motor 254 is driven by the heater control circuit 112, in response to a signal received from the main control circuit 38. As described in more detail below, the main control circuit 38 controls the actuation of the motor 254 in response to the reception by the user interface circuit 26 of a signal generated by the remote control.

The motor 254 is driven in different directions as the control mechanism 240 toggles between the first state and the second state. When the motor 254 is driven in a first direction to place the control mechanism 240 in the first state, the actuator 252 pivots the valve body 242 in a first angular direction to move the valves 244 towards the front surface 194 of the inner casing section 92 to occlude the air inlets 236. When the motor is driven in a second direction opposite to the first direction, the actuator 252 pivots the valve body 242 in a second angular direction, opposite to the first angular direction, to move the valves 244 away from the front surface 194 of the inner casing section 92 to open the air inlets 236.

In this example, the fan assembly 10 is operable in three different operational modes. In a first operational mode, which may be referred to as a fan mode, the heating assemblies 104 are not activated and the control mechanism 240 is placed in the first state. In a second operational mode, which may be referred to as a spot heating mode, the heating assemblies 104 are activated and the control mechanism 240 is placed in the first state. In a third operational state, which may be referred to as a room heating mode, the heating assemblies 104 are activated and the control mechanism 240 is placed in the second state. Each of these operational modes may be selected by a user during operation of the fan assembly 10 by pressing one or more of the buttons on the remote control. The user interface circuit 26 may comprise a number of LEDs which are illuminated in a different manner by the user interface circuit 26 depending on the currently selected operational mode.

The fan assembly 10 is switched on and off either by depressing the button 24 or by depressing a dedicated button on the remote control. When the fan assembly 10 is switched off, the main control circuit 38 stores the current user selected operational parameters, which include the current operational mode of the fan assembly 10, the current user selected speed setting of the motor 60 and - if the fan assembly 10 is in either the second or third operational mode - the current temperature selected by the user. When the fan assembly 10 is next switched on, the fan assembly 10 is operated using those stored operational parameters.

If, for example, the fan assembly 10 is switched on following a previous operation of the fan assembly 10 in the fan mode, the main control circuit 38 selects the rotational speed of the motor 60 from a first range of values, an example of which is listed below. Each value within the first range of values is associated with a respective one of the user selectable speed settings.

Initially, the speed which is selected by the main control circuit 38 corresponds to the speed setting which had been selected by the user when the fan assembly 10 was previously switched off. For example, if the user had selected speed setting 7, the motor 60 is rotated at 7,600 rpm, and the number “7” is displayed on the display 30. As the user selects a different speed setting, the current speed setting is displayed on the display 30.

The motor 60 rotates the impeller 56 to cause a primary air flow to enter the body 12 through the air inlet 14, and to pass to the air inlet 52 of the duct 50. The air flow passes through the duct 50 and is guided by the shaped peripheral surface of the air outlet 54 of the duct 50 into the lower curved section of the interior passage 94 of the nozzle 16. Within the lower curved section of the interior passage 94, the primary air flow is divided into two air streams which pass in opposite directions around the bore 80 of the nozzle 16. One of the air streams enters the straight section of the interior passage 94 located to one side of the bore 80, whereas the other air stream enters the straight section of the interior passage 94 located on the other side of the bore 80. As the air streams pass through the straight sections of the interior passage 94, each air stream turns through around 90°, and passes through the flow channels 128, 156, 178 defined by the chassis 120 towards a respective air outlet 18 of the nozzle 16.

The primary air flow emitted from the air outlets 18 passes, in turn, over the Coanda surface 190 defined by the rear casing section 84 of the nozzle 16, over the diffuser surface 192 defined by the rear casing section 84 of the nozzle 16, and finally over the guide surface 206 defined by the air guiding section 88 of the nozzle 16. As the primary air flow passes over these surfaces, it attaches to these surfaces and so the profile and the direction of the primary air flow as it is emitted from the nozzle 16 then depends on the shape of the guide surface 206. As mentioned above, in this example the guide surface 206 tapers inwardly towards the bore axis X of the nozzle 16 and so the primary air flow is emitted from the nozzle 16 with a profile which also tapers inwardly towards the bore axis X.

The emission of the air flow from the air outlets 18 causes a secondary air flow to be generated by the entrainment of air from the external environment. Air is drawn into the air flow through the bore 80 of the nozzle 16, and from the environment both around and in front of the nozzle 16. This secondary air flow combines with the air flow emitted from the nozzle 16 to produce a combined, or total, air flow, or air current, projected forward from the fan assembly 10. With the air flow tapering inwardly towards the bore axis X, the surface area of its outer profile is relatively low, which in turn results in a relatively low entrainment of air from the region in front of the nozzle 16 and a relatively low flow rate of air through the bore 80 of the nozzle 16, and so the combined air flow generated by the fan assembly 10 has a relatively low flow rate. However, for a given flow rate of a primary air flow generated by the impeller, decreasing the flow rate of the combined air flow generated by the fan assembly 10 is associated with an increase in the maximum velocity of the combined air flow experienced on a fixed plane located downstream from the nozzle. Together with the direction of the air flow towards the bore axis X, this makes the combined air flow suitable for cooling rapidly a user located in front of the fan assembly 10. The user may actuate the oscillating mechanism 40, through depressing a dedicated button on the remote control, to cause the nozzle 16 to oscillate the direction in which the combined air flow is projected forward from the fan assembly 10.

If the user depresses a button on the remote control for placing the fan assembly 10 in the second operational mode, or spot heating mode, the remote control generates and transmits an infrared light signal containing data which is indicative of this action. The signal is received by the receiver 28 of the user interface circuit 26, which communicates the receipt of this signal to the main control circuit 38 to place the fan assembly 10 in the second operational mode. When in this second operational mode, the main control circuit 38 compares the temperature, Ts, previously selected by the user with the temperature Ta, of the air within or passing though the fan assembly 10, as detected by the thermistor and provided to the main control circuit 38 by the heater control circuit 112. When Ta<Ts, the main control circuit 38 instructs the heater control circuit 112 to activate the heater assemblies 104.

In this second operational mode, the main control circuit 38 selects the rotational speed of the motor 60 from a second range of values, an example of which is listed below. Again, each value within the second range of values is associated with a respective one of the user selectable speed settings.

In general, for the majority of the speed settings selectable by the user, the associated rotational speed of the motor 60 is lower in the second range of values than it is in the first range of values to avoid the undesirable creation of a draught within the localised environment to be heated by the fan assembly 10. For example, if the user had selected speed setting 7, the rotational speed of the motor 60 is decreased from 7,600 rpm to 6,150 rpm as the fan assembly 10 switches from the first operational mode to the second operational mode.

As mentioned above, as the air streams pass through the straight sections of the interior passage 94 each air stream passes through the flow channels 128, 156, 178 defined by the chassis 120 towards a respective air outlet 18 of the nozzle 16. A first portion of each air stream passes through a first flow channel 128, a second portion of each air stream passes through a second flow channel 156, and a third portion of each air stream passes through a third flow channel 178. When the heater assemblies 104 are activated, the heat generated by the activated heating assemblies 104 is transferred by convection to the first portions of the primary air flow to raise the temperature of the first portions of the primary air flow. The second portions of the primary air flow pass along the internal surface 98 of the inner casing section 92, thereby acting as a thermal barrier between the relatively hot first portions of the primary air flow and the inner casing section 92. The third portions of the primary air flow pass along the internal surface 96 of the outer casing section 90, thereby acting as a thermal barrier between the relatively hot first portions of the primary air flow and the outer casing section 90.

The third air flow channels 178 are arranged to convey the third portions of the primary air flow to the air outlets 180 located within the interior passage 94. Upon emission from the air outlets 180, the third portions of the primary air flow merge with the first portions of the primary air flow. These merged portions of the primary air flow are conveyed between the internal surface 96 of the outer casing section 88 and the inner walls 122 of the heater housings to the air outlets 184. The air outlets 184 are arranged to direct the relatively hot, merged first and third portions of the primary air flow over the relatively cold second portions of the primary air flow emitted from the air outlets 158, which acts as a thermal barrier between the outer surface 92 of the inner casing section 90 and the relatively hot air emitted from the air outlets 184. Consequently, the majority of the internal and external surfaces of the nozzle 16 are shielded from the relatively hot air generated by the fan assembly 10.

When operating in this second operational mode, the profile of the combined air flow generated by the fan assembly 10 is substantially the same as that generated during the operation of the fan assembly 10 in the first operational mode. As the temperature of the air in the external environment increases, the temperature of the primary air flow drawn into the fan assembly 10 through the air inlet 14, Ta, also increases. A signal indicative of the temperature of this primary air flow is output from the thermistor to the heater control circuit 112. When Ta has risen to 1°C above Ts, the heater control circuit 112 de-activates the heater assemblies 104 and the main control circuit 38 reduces the rotational speed of the motor 60 to 1,000 rpm. When the temperature of the primary air flow has fallen to a temperature around 1°C below Ts, the heater control circuit 112 reactivates the heater assemblies 104 and the main control circuit 38 returns the speed of the motor 60 to that associated with the currently selected speed setting.

If the user now depresses a button on the remote control for placing the fan assembly 10 in the third operational mode, or room heating mode, the remote control generates and transmits an infrared light signal containing data which is indicative of this action. The signal is received by the receiver 28 of the user interface circuit 26, which communicates the receipt of this signal to the main control circuit 38 to place the fan assembly 10 in the third operational mode. When in this third operational mode, the main control circuit 38 selects the rotational speed of the motor 60 from a third range of values, an example of which is listed below. Again, each value within the third range of values is associated with a respective one of the user selectable speed settings.

In general, for the majority of the speed settings selectable by the user, the associated rotational speed of the motor 60 is higher in the third range of values than it is in the second range of values to increase the velocity and the flow rate of a combined air flow generated by the fan assembly 10, and so promote a more rapid heating of the room or other location in which the fan assembly 10 is located. For example, if the user had selected speed setting 7, the rotational speed of the motor 60 is increased from 6,150 rpm to 7,200 rpm as the fan assembly 10 switches from the second operational mode to the third operational mode.

In this third operational mode, the main control circuit 38 instructs the heater control circuit 112 to drive the motor 254 in the second direction to place the control mechanism 240 in its second state. This actuates the actuator 252 to pivot the valve body 242 in the second angular direction to move the valves 244 away from the front surface 194 of the inner casing section 92 to open the air inlets 236 of the flow control chamber 220. With the control mechanism 240 in this second state, a first portion of the air flow passes through the air inlets 236 from the lower curved section of the interior passage 94 to form a flow control air flow which passes through the flow control chamber 220. A second portion of the air flow remains within the interior passage 94, wherein, as described above, it is divided into the two air streams which pass in opposite directions around the bore 80 of the nozzle 16. The proportion of the air flow which enters the flow control chamber 220 is preferably in the range from 5 to 30%, and in this example is around 20%.

Within the flow control chamber 220, the flow control air flow is divided into two air streams which also pass in opposite directions around the bore 80 of the nozzle 16. As in the interior passage 94, each of these air streams enters a respective one of the two straight sections of the flow control chamber 220, and is conveyed in a substantially vertical direction up through each of these sections towards the upper curved section of the flow control chamber 220. As these air streams pass through the straight sections of the flow control chamber 220, air is emitted from the flow control ports 226. The flow control air flow emitted from the flow control ports 226 passes, in turn, over the Coanda surface 232 defined by the front casing section 86 of the nozzle 16, and over the diffuser surface 234 defined by the front casing section 86 of the nozzle 16.

As the flow control air flow passes over these surfaces, it attaches to these surfaces 232, 234 to generate a relatively low pressure adjacent to the end of the front section 204 of the air guiding section 88. This in turn generates a pressure differential across each of the air streams emitted from the air outlets 18 of the nozzle 16, which are each passing over the external guide surface 206 defined by the front section 204 of the air guiding section 88. The pressure differential thus created across the air streams generates a force which urges the air streams towards the external surface 228 of the front casing section 86, which results in the air streams becoming attached to the external surface 228 of the front casing section 86 and merging with the flow control air flow to re-form the primary air flow.

As mentioned above, the diffuser surface 234 of the front casing section 86 tapers away from the bore axis X of the nozzle 16, and so the air flow is emitted from the nozzle 16 with a profile which tapers outwardly away from the bore axis X. With the air flow now tapering outwardly away from the bore axis X, the surface area of its outer profile is relatively large, which in turn results in a relatively high entrainment of air from the region in front of the nozzle 16 and so, for a given flow rate of air generated by the impeller, the combined air flow generated by the fan assembly 10 has a relatively high flow rate. Thus, placing the control mechanism 240 in its second state has the result of the fan assembly 10 generating a relatively wide, heated flow of air through a room or an office.

If subsequently the user selects either the fan mode or the spot heating mode, the main control circuit 38 instructs the heater control circuit 112 to drive the motor 254 in the first direction to return the control mechanism 240 to its first state. This actuates the actuator 252 to pivot the valve body 242 in the first angular direction to move the valves 244 towards the front surface 194 of the inner casing section 92 to occlude the air inlets 236 of the flow control chamber 220. As the passage of the air through the flow control chamber 220 is now inhibited by the flow control mechanism 240 the pressure differential across the air streams emitted from the air outlets 18 is removed. This causes the air streams to detach from the external surface 228 of the front casing section 86, and return the profile of the primary air flow emitted from the nozzle 16 to one which tapers inwardly towards the bore axis X.

In summary, a nozzle for a fan assembly includes an air inlet, an air outlet, an interior passage for conveying air from the air inlet to the air outlet, an annular inner wall, and an outer wall extending about the inner wall. The interior passage is located between the inner wall and the outer wall. The inner wall at least partially defines a bore through which air from outside the nozzle is drawn by air emitted from the air outlet. The air outlet is arranged to direct air over an external surface of the nozzle. A flow control port is located downstream from that surface. A flow control chamber is provided for conveying air to the flow control port. A control mechanism selectively enables a flow of air through the flow control port to deflect an air flow emitted from the air outlet.

Claims

1. A nozzle for a fan assembly, the nozzle comprising an air inlet; an air outlet; an interior passage for conveying air from the air inlet to the air outlet; an annular inner wall; an outer wall extending about the inner wall, the interior passage being located between the inner wall and the outer wall, the inner wall at least partially defining a bore through which air from outside the nozzle is drawn by air emitted from the air outlet, the air outlet being arranged to direct air over an external surface of the nozzle; a flow control port located downstream from the air outlet and said surface; a flow control chamber for conveying air to the flow control port; and control means for selectively inhibiting a flow of air through the flow control port..

2. A nozzle as claimed in claim 1, wherein the air outlet is arranged to direct air over an external surface of the nozzle.

3. A nozzle as claimed in claim 2, wherein said external surface at least partially defines the bore.

4. A nozzle as claimed in claim 2 or claim 3, wherein said external surface extends at least partially about the axis of the bore.

5. A nozzle as claimed in any one of claims 2 to 4, wherein said external surface surrounds the axis of the bore.

6. A nozzle as claimed in any one of claim 2 to 5, wherein said external surface comprises a Coanda surface located immediately downstream from the air outlet.

7. A nozzle as claimed in any one of claims 2 to 6, wherein said external surface comprises a diffuser surface which tapers outwardly relative to an axis of the bore.

8. A nozzle as claimed in claim 7, wherein the first guide surface is located between the diffuser surface and the flow control port.

9. A nozzle as claimed in claim 8, wherein said first guide surface is shaped to taper inwardly relative to the diffuser surface.

10. A nozzle as claimed in claim 8 or claim 9, wherein said first guide surface is shaped to taper inwardly relative to the axis of the bore.

11. A nozzle as claimed in any of claims 7 to 9, wherein said first guide surface is defined by an external surface of an air flow guiding member of the nozzle.

12. A nozzle as claimed in claim 11, wherein an internal surface of the air flow guiding member at least partially defines the flow control port.

13. A nozzle as claimed in any preceding claim, wherein the flow control port is arranged to direct an air flow over a second external surface of the nozzle.

14. A nozzle as claimed in claim 13, wherein the second external surface at least partially defines the bore of the nozzle.

15. A nozzle as claimed in claim 14, wherein the second external surface defines at least part of a front section of the nozzle.

16. A nozzle as claimed in any of claims 13 to 15, wherein the second external surface comprises a second Coanda surface located immediately downstream from the flow control port.

17. A nozzle as claimed in any of claims 13 to 16, wherein the second external surface comprises a second diffuser surface which tapers outwardly relative to an axis of the bore.

18. A nozzle as claimed in any of claims 13 to 17, wherein the second external surface comprises the second guide surface.

19. A nozzle as claimed in any preceding claim, wherein the flow control chamber is located in front of the interior passage.

20. A nozzle as claimed in any preceding claim, wherein each of the interior passage and the flow control chamber surrounds the bore of the nozzle.

21. A nozzle as claimed in any preceding claim, wherein each of the air outlet and the flow control port is in the form of a slot.

22. A nozzle as claimed in any preceding claim, wherein the control means has a first state for inhibiting the passage of air through the flow control chamber, and a second state for permitting the passage of air through the flow control chamber.

23. A nozzle as claimed in any preceding claim, wherein the control means comprises a valve body for occluding an air inlet of the flow control chamber, and an actuator for moving the valve body relative to the air inlet of the flow control chamber.

24. A nozzle as claimed in any preceding claim, comprising a heater assembly located at least partially within the interior passage.

25. A fan assembly comprising an impeller, a motor for rotating the impeller to generate an air flow, a nozzle as claimed in any preceding claim for receiving the air flow, and a controller for controlling the motor and for changing the state of the control means.

26. A fan assembly as claimed in claim 25 when dependent from claim 22, wherein the controller is arranged to adjust the speed of the motor as the state of the control means is changed.