U.S. patent application number 14/204189 was filed with the patent office on 2014-09-11 for fan assembly.
This patent application is currently assigned to DYSON TECHNOLOGY LIMITED. The applicant listed for this patent is DYSON TECHNOLOGY LIMITED. Invention is credited to Joseph Eric HODGETTS, Roy Edward POULTON.
Application Number | 20140255173 14/204189 |
Document ID | / |
Family ID | 48189705 |
Filed Date | 2014-09-11 |
United States Patent
Application |
20140255173 |
Kind Code |
A1 |
POULTON; Roy Edward ; et
al. |
September 11, 2014 |
FAN ASSEMBLY
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 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 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.
Inventors: |
POULTON; Roy Edward;
(Swindon, GB) ; HODGETTS; Joseph Eric; (Bristol,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DYSON TECHNOLOGY LIMITED |
Wiltshire |
|
GB |
|
|
Assignee: |
DYSON TECHNOLOGY LIMITED
Wiltshire
GB
|
Family ID: |
48189705 |
Appl. No.: |
14/204189 |
Filed: |
March 11, 2014 |
Current U.S.
Class: |
415/182.1 |
Current CPC
Class: |
F04D 25/0693 20130101;
F24F 13/08 20130101; F04F 5/16 20130101; F24F 1/01 20130101; F04D
25/08 20130101; F04D 29/40 20130101; F24F 7/007 20130101; F24F
13/26 20130101 |
Class at
Publication: |
415/182.1 |
International
Class: |
F04D 29/40 20060101
F04D029/40 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 11, 2013 |
GB |
1304338.5 |
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 a control mechanism for selectively inhibiting a
flow of air through the flow control port.
2. The nozzle of claim 1, wherein said surface at least partially
defines the bore.
3. The nozzle of claim 1, wherein said surface extends at least
partially about the axis of the bore.
4. The nozzle of claim 1, wherein said surface surrounds the axis
of the bore.
5. The nozzle of claim 1, wherein said surface comprises a Coanda
surface located immediately downstream from the air outlet.
6. The nozzle of claim 1, wherein said surface comprises a diffuser
surface which tapers outwardly relative to an axis of the bore.
7. The nozzle of claim 6, comprising a guide surface located
between the diffuser surface and the flow control port.
8. The nozzle of claim 7, wherein said guide surface is shaped to
taper inwardly relative to the diffuser surface.
9. The nozzle of claim 7, wherein said guide surface is shaped to
taper inwardly relative to the axis of the bore.
10. The nozzle of claim 7, wherein the guide surface is defined by
an external surface of an air flow guiding member of the
nozzle.
11. The nozzle of claim 10, wherein an internal surface of the air
flow guiding member at least partially defines the flow control
port.
12. The nozzle of claim 1, wherein the flow control port is
arranged to direct an air flow over a second external surface of
the nozzle.
13. The nozzle of claim 12, wherein the second external surface at
least partially defines the bore of the nozzle.
14. The nozzle of claim 13, wherein the second external surface
defines at least part of a front section of the nozzle.
15. The nozzle of claim 12, wherein the second external surface
comprises a second Coanda surface located immediately downstream
from the flow control port.
16. The nozzle of claim 12, wherein the second external surface
comprises a second diffuser surface which tapers outwardly relative
to an axis of the bore.
17. The nozzle of claim 12, wherein the second external surface
comprises a second guide surface.
18. 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 a control mechanism for selectively inhibiting a
flow of air through the flow control port.
19.-24. (canceled)
25. The fan assembly comprising an impeller, a motor for rotating
the impeller to generate an air flow, the nozzle of claim 1 for
receiving the air flow, and a controller for controlling the motor
and for changing the state of the control mechanism.
26. The fan assembly of claim 25, wherein the control mechanism 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, and the controller is
arranged to adjust the speed of the motor as the state of the
control mechanism is changed.
27. (canceled)
28. The nozzle of claim 1, wherein the flow control chamber is
located in front of the interior passage.
29. The nozzle of claim 1, wherein each of the interior passage and
the flow control chamber surrounds the bore of the nozzle.
30. The nozzle of claim 1, wherein each of the air outlet and the
flow control port is in the form of a slot.
31. The nozzle of claim 1, wherein the control mechanism 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.
32. The nozzle of claim 1, wherein the control mechanism 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.
33. The nozzle of claim 1, comprising a heater assembly located at
least partially within the interior passage.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority of United Kingdom
Application No. 1304338.5, filed Mar. 11, 2013, the entire contents
of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a nozzle for a fan
assembly, and a fan assembly comprising such a nozzle.
BACKGROUND OF THE INVENTION
[0003] 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.
[0004] U.S. Pat. No. 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.
[0005] 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
U.S. Pat. No. 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.
[0006] 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.
[0007] 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.degree.. 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.degree. to the
horizontal.
SUMMARY OF THE INVENTION
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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).
[0031] 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.
[0032] 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.
[0033] The interior passage may comprise means for heating at least
part of the air flow received by the nozzle.
[0034] 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.
[0035] 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
[0036] An embodiment of the present invention will now be
described, by way of example only, with reference to the
accompanying drawings, in which:
[0037] FIG. 1 is a front view of a fan assembly;
[0038] FIG. 2 is a vertical cross-sectional view of the fan
assembly, taken along line A-A in FIG. 1;
[0039] FIG. 3 is a left perspective view, from above, of a nozzle
of the fan assembly;
[0040] FIG. 4 is an exploded view of the nozzle;
[0041] FIG. 5 is an exploded view of a rear casing section of the
nozzle;
[0042] FIG. 6 is a front view of the nozzle;
[0043] FIG. 7 is a horizontal cross-section of the nozzle, taken
along line B-B in FIG. 6;
[0044] FIG. 8 is a left perspective view, from below, of the
nozzle; and
[0045] FIG. 9 is a bottom view of the nozzle.
DETAILED DESCRIPTION OF THE INVENTION
[0046] FIG. 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.
[0047] 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.
[0048] FIG. 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.
[0049] 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.
[0050] 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.degree. and 180.degree., and in
this embodiment is around 70.degree.. 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.
[0051] 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.
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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.
[0056] With reference to FIG. 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.
[0057] FIGS. 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.
[0058] 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 FIGS. 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.
[0059] 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-by-side. 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.
[0060] 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.
[0061] 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.
[0062] 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 FIG.
2. Returning to FIG. 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.
[0063] 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.
[0064] 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
FIGS. 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.
[0065] 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.
[0066] 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.
[0067] Returning to FIGS. 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.degree., and in this
example is around 5.degree..
[0068] 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 FIG. 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.degree., and in
this example is around -10.degree..
[0069] 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.
[0070] 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.
[0071] 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.
[0072] 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.
[0073] 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.degree., and in this example is around 45.degree..
[0074] With reference now to FIGS. 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.
[0075] 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.
[0076] 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.
[0077] 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.
[0078] 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.
[0079] 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.
[0080] 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.
TABLE-US-00001 Speed setting First range of values (rpm) 10 9000 9
8530 8 8065 7 7600 6 7135 5 6670 4 6200 3 5735 2 5265 1 4800
[0081] 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.
[0082] 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.degree., and passes through the flow channels 128, 156, 178
defined by the chassis 120 towards a respective air outlet 18 of
the nozzle 16.
[0083] 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.
[0084] 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.
[0085] 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, T.sub.s,
previously selected by the user with the temperature T.sub.a, 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 T.sub.a<T.sub.s, the main
control circuit 38 instructs the heater control circuit 112 to
activate the heater assemblies 104.
[0086] 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.
TABLE-US-00002 Speed setting Second range of values (rpm) 10 6750 9
6600 8 6375 7 6150 6 5925 5 5700 4 5475 3 5250 2 5025 1 4800
[0087] 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.
[0088] 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.
[0089] 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.
[0090] 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, T.sub.a, 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 T.sub.a
has risen to 1.degree. C. above T.sub.s, 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.degree. C. below T.sub.s, the heater control
circuit 112 re-activates 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.
[0091] 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.
TABLE-US-00003 Speed setting Third range of values (rpm) 10 8400 9
8000 8 7600 7 7200 6 6800 5 6400 4 6000 3 5600 2 5200 1 4800
[0092] 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.
[0093] 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%.
[0094] 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.
[0095] 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.
[0096] 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.
[0097] 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.
[0098] 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.
* * * * *