U.S. patent application number 13/880657 was filed with the patent office on 2013-10-24 for fan.
This patent application is currently assigned to Dyson Technology Limited. The applicant listed for this patent is Timothy Nicholas Stickney. Invention is credited to Timothy Nicholas Stickney.
Application Number | 20130280061 13/880657 |
Document ID | / |
Family ID | 45974746 |
Filed Date | 2013-10-24 |
United States Patent
Application |
20130280061 |
Kind Code |
A1 |
Stickney; Timothy Nicholas |
October 24, 2013 |
FAN
Abstract
A fan includes a nozzle and a device for creating a primary air
flow through the nozzle. The nozzle includes a mouth for emitting
the primary air flow, and defines a bore through which a secondary
air flow from outside the fan is drawn by the primary air flow
emitted from the mouth and which combines with the primary air flow
to produce a combined air flow. To allow a user to adjust at least
one parameter, for example at least one of the profile, orientation
and the direction, of the combined air flow, the fan comprises an
insert which is locatable at least partially within the bore of the
nozzle. The fan may be provided with a set of such inserts.
Inventors: |
Stickney; Timothy Nicholas;
(Malmesbury, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Stickney; Timothy Nicholas |
Malmesbury |
|
GB |
|
|
Assignee: |
Dyson Technology Limited
Malmesbury
GB
|
Family ID: |
45974746 |
Appl. No.: |
13/880657 |
Filed: |
September 26, 2011 |
PCT Filed: |
September 26, 2011 |
PCT NO: |
PCT/GB11/51816 |
371 Date: |
June 24, 2013 |
Current U.S.
Class: |
415/211.2 |
Current CPC
Class: |
F04D 23/00 20130101;
F04D 27/00 20130101; F04F 5/16 20130101; F04D 25/08 20130101; F04F
5/461 20130101 |
Class at
Publication: |
415/211.2 |
International
Class: |
F04D 23/00 20060101
F04D023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2010 |
GB |
1017706.1 |
Oct 20, 2010 |
GB |
1017707.9 |
Claims
1. A fan comprising a nozzle and a device for creating a primary
air flow through the nozzle, the nozzle comprising at least one
outlet for emitting the primary air flow, the nozzle defining a
bore through which a secondary air flow from outside the fan is
drawn by the primary air flow emitted from the at least one outlet
and which combines with the primary air flow to produce a combined
air flow, wherein the fan comprises an insert locatable at least
partially within the bore of the nozzle for adjusting at least one
parameter of the combined air flow.
2. The fan of claim 1, wherein the insert is rotatable within the
bore of the nozzle.
3. The fan of claim 1, wherein the insert is annular in shape.
4. The fan of claim 1, wherein the insert comprises a rim which is
locatable over a front end of the nozzle.
5. The fan of claim 1, wherein the insert tapers towards a rear end
thereof.
6. The fan of claim 1, wherein the insert comprises a surface
defining a bore through which, when the insert is located in the
nozzle, the secondary air flow from outside the fan is drawn by the
primary air flow emitted from the at least one outlet.
7. The fan of claim 6, wherein, when the insert is located within
the nozzle, the bore of the insert is substantially co-axial with
the bore of the nozzle.
8. The fan of claim 6, wherein, when the insert is located within
the nozzle, the at least one outlet of the nozzle is arranged to
direct the primary air flow through the bore of the insert.
9. The fan of claim 6, wherein the surface extends about an
axis.
10. The fan of claim 9, wherein at least part of the surface is
inclined to the axis.
11. The fan of claim 10, wherein the angle by which said at least
part of the surface is inclined to the axis varies about the
axis.
12. The fan of claim 10, wherein the angle by which said at least
part of the surface is inclined to the axis varies continuously
about the axis.
13. The fan of claim 6, wherein the surface is continuous about the
axis.
14. The fan of claim 1, wherein the insert comprises a plurality of
interconnected sections which are locatable simultaneously within
the bore of the nozzle.
15. The fan of claim 14, wherein the sections have substantially
the same shape.
16. The fan of claim 14, wherein the sections are substantially
wedge shaped.
17. The fan of claim 14, wherein the sections are arranged about an
axis.
18. The fan of claim 17, wherein the sections are regularly spaced
about the axis.
19. The fan of claim 14, wherein each of the sections comprises a
surface which is inclined to the axis.
20. The fan of claim 19, wherein the at least one outlet of the
nozzle is arranged to direct the primary air flow over the surfaces
of the sections of the insert.
21. The fan of claim 1, wherein said at least one parameter of the
combined air flow comprises at least one of the profile,
orientation, direction, flow rate and velocity of the combined air
flow.
22. The fan of claim 1, wherein the at least one outlet extends
about the bore.
23. The fan of claim 1, wherein the at least one outlet is in the
form of a slot.
24. (canceled)
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a national stage application under 35
USC 371 of International Application No. PCT/GB2011/051816, filed
Sep. 26, 2011, which claims the priority of United Kingdom
Application No. 1017706.1, filed Oct. 20, 2010, and United Kingdom
Application No. 1017707.9, filed Oct. 20, 2010, the entire contents
of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a fan. Particularly, but
not exclusively, the present invention relates to a floor or
table-top fan, such as a desk, tower or pedestal fan.
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] WO 2009/030879 describes a fan assembly which does not use
caged blades to project air from the fan assembly. Instead, the fan
assembly comprises a cylindrical base which houses a motor-driven
impeller for drawing a primary air flow into the base, and an
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.
SUMMARY OF THE INVENTION
[0005] In a first aspect, the present invention provides a fan
including a nozzle and means for creating a primary air flow
through the nozzle. The nozzle includes at least one outlet for
emitting the primary air flow, and defines a bore through which a
secondary air flow from outside the fan is drawn by the primary air
flow emitted from the at least one outlet and which combines with
the primary air flow to produce a combined air flow. To allow a
user to adjust at least one parameter of the combined air flow, the
fan comprises an insert which is locatable at least partially
within the bore of the nozzle.
[0006] The at least one parameter of the combined air flow may
comprise at least one of the profile, orientation, direction, flow
rate (as measured, for example, in litres per second), and velocity
of the combined air flow. Thus, through location of the insert
within the bore of the nozzle, a user may adjust the direction in
which the combined air flow is projected forward from the fan, for
example to angle the air flow towards or away from a person in the
vicinity of the fan. Alternatively, or additionally, the insert may
expand or restrict the profile of the combined air flow to increase
or decrease the number of users within the path of the air flow. As
another alternative the insert may change the orientation of the
air flow to provide a relatively wide air flow for cooling a number
of users.
[0007] The insert may be moveable within the bore of the nozzle to
allow a user to change quickly, for example the direction in which
the combined air flow is projected forward from the fan. For
example, the insert may be slid over and/or along the bore of the
nozzle, or it may be rotated within the bore of the nozzle. The
nozzle may include means for guiding the movement of the insert
relative to the bore.
[0008] The insert may have any shape suitable for changing the air
flow in a desired manner. For example, the insert may comprise one
or more sections which are locatable within the bore of the nozzle
to deflect the combined air flow in a particular direction, for
example towards or away from a person located to one side of the
fan. In one embodiment, the insert comprises a plurality of
interconnected sections which are locatable simultaneously within
the bore of the nozzle. These sections may have substantially the
same shape, or they may have different shapes. The sections may be
wedge-shaped, tapering towards the rear end of the nozzle. The
sections may be arranged about an axis. When the insert is located
within the nozzle, the insert is preferably substantially co-axial
with the bore of the nozzle. The sections may be regularly or
irregularly spaced about the axis.
[0009] The insert may be located partially within the bore of the
nozzle, for example so that part of the insert protrudes forwardly
from the front end of the nozzle to guide part or all of the
combined air flow in a particular direction. Alternatively, it may
be located substantially fully within the bore of the nozzle. The
bore of the nozzle preferably tapers outwardly towards the front
end of the bore, and so the insert is preferably inserted into the
bore through the front end of the nozzle. The insert may be annular
in shape. The insert may comprise a rim which is locatable over the
front edge of the nozzle to retain the insert within the bore of
the nozzle.
[0010] The at least one outlet of the nozzle may be located towards
the rear of the nozzle, and arranged to emit the primary air flow
through the bore of the nozzle. As mentioned above, the nozzle
preferably comprises a surface which defines the bore of the
nozzle, and the at least one outlet is preferably arranged to
direct the primary air flow over the surface of the nozzle.
Preferably, the surface over which the at least one outlet is
arranged to direct the primary air flow comprises a Coanda surface.
A Coanda surface is a known type of surface over which fluid flow
exiting an output orifice close to the surface exhibits the Coanda
effect. The fluid tends to flow over the surface closely, almost
`clinging to` or `hugging` the surface. The Coanda effect is
already a proven, well documented method of entrainment in which a
primary air flow is directed over a Coanda surface. A description
of the features of a Coanda surface, and the effect of fluid flow
over a Coanda surface, can be found in articles such as Reba,
Scientific American, Volume 214, June 1966 pages 84 to 92. Through
use of a Coanda surface, an increased amount of air from outside
the fan is drawn through the bore by the air emitted from the
nozzle.
[0011] In a preferred embodiment an air flow is created through the
nozzle of the fan. In the following description this air flow will
be referred to as the primary air flow. The primary air flow is
emitted from the at least one outlet of the nozzle and preferably
passes over a Coanda surface. The primary air flow entrains air
surrounding the nozzle, which acts as an air amplifier to supply
both the primary air flow and the entrained air to the user. The
entrained air will be referred to here as a secondary air flow. The
secondary air flow is drawn from the room space, region or external
environment surrounding the mouth of the nozzle and, by
displacement, from other regions around the fan, and passes
predominantly through the bore defined by the nozzle. The primary
air flow directed over the Coanda surface combined with the
entrained secondary air flow equates to a combined, or total, air
flow emitted or projected forward from the front end of the bore of
the nozzle.
[0012] The Coanda surface may comprise a diffuser portion located
downstream from the at least one outlet. The diffuser portion
preferably extends about an axis, and preferably tapers towards or
away from the axis.
[0013] The insert preferably covers at least part of the Coanda
surface of the nozzle, and so may be provided in the form of a mask
which is insertable into the bore of the nozzle. The insert
preferably covers at least part of the diffuser portion of the
Coanda surface. Where the insert comprises a plurality of
interconnected sections, each section may cover a respective part
of the diffuser portion of the Coanda surface.
[0014] As an alternative to providing the insert with a number of
interconnected sections, the insert may comprise a surface defining
a bore through which, when the insert is located in the nozzle, the
secondary air flow from outside the fan is drawn by the primary air
flow emitted from the mouth. This insert can cover an annular
section of the Coanda surface, preferably at least part of the
diffuser portion of the Coanda surface and more preferably
substantially all of the diffuser portion of the Coanda surface.
When the insert is located within the nozzle, the bore of the
insert is preferably substantially co-axial with the bore of the
nozzle. The at least one outlet of the nozzle is preferably
arranged to direct the primary air flow through the bore of the
insert.
[0015] The surface of the insert preferably extends about an axis,
and at least part of that surface is preferably inclined to that
axis. The inclination of the surface of the insert to the axis is
preferably different from the inclination of the diffuser portion
of the Coanda surface. In this case, the location of the insert
within the bore of the nozzle can change the flow rate and the
velocity of the combined air flow. For example where the angle by
which the surface of the insert is inclined to the axis is
shallower than the angle by which the diffuser portion of the
Coanda surface is inclined to the axis, the flow rate of the
combined air flow will decrease when the insert is located within
the nozzle, but the velocity of the combined air flow will
increase.
[0016] Substantially all of the surface of the insert may be
inclined to the axis by the same amount, and so the surface may
have a shape which is cylindrical or frusto-conical. The angle of
inclination may be in the range from -15 to 35.degree..
Alternatively, the angle of inclination may vary about the axis.
Through varying the angle of inclination about the axis, the air
current generated by the fan may have a non-cylindrical or a
non-frusto-conical profile when the insert is located within the
bore of the nozzle. The angle may vary along the surface, that is,
about the axis, between at least one maximum value and at least one
minimum value. Preferably, the angle varies along the surface
between a plurality of maximum values and a plurality of minimum
values. In a preferred embodiment the angle varies along the
surface between six maximum values and six minimum values. The
maximum values and the minimum values are preferably regularly
spaced about the axis. The minimum value may be in the range from
-15.degree. to 15.degree., whereas the maximum value may be in the
range from 20 to 35.degree.. In a preferred embodiment the maximum
value is at least twice the minimum value. The angle of inclination
may vary continuously or discontinuously about the axis.
[0017] The fan may comprise a set of inserts which are
interchangeably locatable within the bore of the nozzle, and so in
a second aspect the present invention provides a fan comprising a
nozzle and means for creating a primary air flow through the
nozzle, the nozzle comprising at least one outlet for emitting the
primary air flow, the nozzle defining a bore through which a
secondary air flow from outside the fan is drawn by the primary air
flow emitted from the at least one outlet and which combines with
the primary air flow to produce a combined air flow; characterised
in that the fan comprises a plurality of inserts insertable
interchangeably into the bore of the nozzle for adjusting at least
one parameter of the combined air flow, each insert having a
respective different profile. For example, as discussed above one
of the inserts may comprise a plurality of interconnected sections,
whereas another one of the inserts may comprise a bore through the
secondary air flow is drawn by the emission of the primary air flow
from the mouth of the nozzle.
[0018] The at least one outlet preferably extends about the bore of
the nozzle. The nozzle may comprise a single outlet which is
continuous about the bore, and may be substantially circular in
shape. Preferably, the spacing between opposing surfaces of the
nozzle at the outlet(s) is preferably in the range from 0.5 mm to 5
mm. The, or each, outlet is preferably in the form of a slot.
[0019] The nozzle is preferably mounted on a base housing said
means for creating an air flow. In the preferred fan the means for
creating an air flow through the nozzle comprises an impeller
driven by a motor.
[0020] The insert may be provided separately from the fan, and so
in a third aspect the present invention provides an accessory for a
fan comprising a nozzle having at least one outlet for emitting a
primary air flow and a bore through which a secondary air flow from
outside the fan is drawn by the primary air flow emitted from the
at least one outlet and which combines with the primary air flow to
produce a combined air flow, the accessory being locatable on the
nozzle, preferably within the bore of the nozzle.
[0021] As mentioned above, the accessory may change at least one
parameter of the combined air flow. However, the accessory may
provide alternative, or additional, benefits for the user. For
example, the accessory may have a different colour to the nozzle of
the fan, and/or may be formed from a different material to the
nozzle of the fan. The accessory may be formed from luminous
material, or may comprise one or more light emitting diodes (LEDs)
or other illuminating means. The accessory may be configured to
support a picture, photo or other item(s). For example, the
accessory may comprise a housing for retaining one or more items,
such as items of stationery, money, keys, a remote control and the
like. The accessory may clip on to the front end of the nozzle. The
accessory may comprise a thermometer, a barometer, a camera, a
display, a clock, a radio or other electronic or mechanical
device.
[0022] In a fourth aspect the present invention provides a fan
comprising a nozzle and means for creating an air flow through the
nozzle, the nozzle comprising an interior passage, at least one
outlet for receiving the air flow from the interior passage, and a
Coanda surface located adjacent the at least one outlet and over
which the at least one outlet is arranged to direct the air flow,
characterised in that the fan comprises a removable mask for
covering at least part of the Coanda surface.
[0023] Features described above in connection with the first aspect
of the invention are equally applicable to the second to fourth
aspects of the invention, and vice versa.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Preferred features of the invention will now be described,
by way of example only, with reference to the accompanying
drawings, in which:
[0025] FIG. 1 is a front perspective view, from above, of a
fan;
[0026] FIG. 2 is a side sectional view through the fan;
[0027] FIG. 3 is a front perspective view, from above, of an insert
for the fan;
[0028] FIG. 4 is a front perspective view, from above, of the fan
with the insert located in the bore of the nozzle;
[0029] FIG. 5 is a side view of the fan of FIG. 4;
[0030] FIG. 6 is a top view of the fan of FIG. 4;
[0031] FIG. 7 is a front view of the fan of FIG. 4;
[0032] FIG. 8 is a side sectional view taken along line A-A in FIG.
7;
[0033] FIG. 9 is a front perspective view, from above, of a second
insert for the fan;
[0034] FIG. 10 is a front perspective view, from above, of the fan
with the second insert located in the bore of the nozzle;
[0035] FIG. 11 is a front perspective view, from above, of a third
insert for the fan; and
[0036] FIG. 12 is a front perspective view, from above, of the fan
with the third insert located in the bore of the nozzle.
DETAILED DESCRIPTION OF THE INVENTION
[0037] FIG. 1 is an external view of a fan 10. The fan 10 comprises
a body 12 comprising an air inlet 14 through which a primary air
flow enters the fan 10, and a nozzle 16 in the form of an annular
casing mounted on the body 12, and which comprises a mouth 18 for
emitting the primary air flow from the fan 10.
[0038] 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 upper body section 20 is substantially
flush with the external 5. surface of the lower body section 22. In
this embodiment the body 12 has a height in the range from 100 to
300 mm, and a diameter in the range from 100 to 200 mm.
[0039] The main body section 20 comprises the air inlet 14 through
which the primary air flow enters the fan 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. The main body section 20 is open at the upper end
(as illustrated) thereof to provide an air outlet 23 through which
the primary air flow is exhausted from the body 12.
[0040] The main body section 20 may be tilted relative to the lower
body section 22 to adjust the direction in which the primary air
flow is emitted from the fan 10. For example, the upper surface of
the lower body section 22 and the lower surface of the main body
section 20 may be provided with interconnecting features which
allow the main body section 20 to move relative to the lower body
section 22 while preventing the main body section 20 from being
lifted from the lower body section 22. For example, the lower body
section 22 and the main body section 20 may comprise interlocking
L-shaped members.
[0041] The lower body section 22 comprises a user interface of the
fan 10. The user interface comprises a plurality of user-operable
buttons 24, 26, a dial 28 for enabling a user to control various
functions of the fan 10, and user interface control circuit 30
connected to the buttons 24, 26 and the dial 28. The lower body
section 22 is mounted on a base 32 for engaging a surface on which
the fan 10 is located.
[0042] FIG. 2 illustrates a sectional view through the body of the
fan 10. The lower body section 22 houses a main control circuit,
indicated generally at 34, connected to the user interface control
circuit 30. In response to operation of the buttons 24, 26 and the
dial 28, the user interface control circuit 30 is arranged to
transmit appropriate signals to the main control circuit 34 to
control various operations of the fan 10.
[0043] The lower body section 22 also houses a mechanism, indicated
generally at 36, for oscillating the lower body section 22 relative
to the base 32. The operation of the oscillating mechanism 36 is
controlled by the main control circuit 34 in response to the user
operation of the button 26. The range of each oscillation cycle of
the lower body section 22 relative to the base 32 is preferably
between 60.degree. and 120.degree., and in this embodiment is
around 80.degree.. In this embodiment, the oscillating mechanism 36
is arranged to perform around 3 to 5 oscillation cycles per minute.
A mains power cable 38 for supplying electrical power to the fan 10
extends through an aperture formed in the base 32. The cable 38 is
connected to a plug (not shown) for connection to a mains power
supply.
[0044] The main body section 20 houses an impeller 40 for drawing
the primary air flow through the air inlet 14 and into the body 12.
Preferably, the impeller 40 is in the form of a mixed flow
impeller. The impeller 40 is connected to a rotary shaft 42
extending outwardly from a motor 44. In this embodiment, the motor
44 is a DC brushless motor having a speed which is variable by the
main control circuit 34 in response to user manipulation of the
dial 28. The maximum speed of the motor 44 is preferably in the
range from 5,000 to 10,000 rpm. The motor 44 is housed within a
motor bucket comprising an upper portion 46 connected to a lower
portion 48. The upper portion 46 of the motor bucket comprises a
diffuser 50 in the form of a stationary disc having spiral
blades.
[0045] The motor bucket is located within, and mounted on, a
generally frusto-conical impeller housing 52. The impeller housing
52 is, in turn, mounted on a plurality of angularly spaced supports
54, in this example three supports, located within and connected to
the main body section 20 of the base 12. The impeller 40 and the
impeller housing 52 are shaped so that the impeller 40 is in close
proximity to, but does not contact, the inner surface of the
impeller housing 52. A substantially annular inlet member 56 is
connected to the bottom of the impeller housing 52 for guiding the
primary air flow into the impeller housing 52. An electrical cable
58 passes from the main control circuit 34 to the motor 44 through
apertures formed in the main body section 20 and the lower body
section 22 of the body 12, and in the impeller housing 52 and the
motor bucket.
[0046] Preferably, the body 12 includes silencing foam for reducing
noise emissions from the body 12. In this embodiment, the main body
section 20 of the body 12 comprises a first foam member 60 located
beneath the air inlet 14, and a second annular foam member 62
located within the motor bucket.
[0047] A flexible sealing member 64 is mounted on the impeller
housing 52. The flexible sealing member prevents air from passing
around the outer surface of the impeller housing 52 to the inlet
member 56. The sealing member 64 preferably comprises an annular
lip seal, preferably formed from rubber. The sealing member 64
further comprises a guide portion in the form of a grommet for
guiding the electrical cable 58 to the motor 44.
[0048] Returning to FIG. 1, the nozzle 16 has an annular shape,
extending about a central axis X to define a bore 70. The mouth 18
is located towards the rear of the nozzle 16, and is arranged to
emit the primary air flow towards the front of the fan 10, through
the bore 70. The mouth 18 surrounds the bore 70. In this example,
the nozzle 16 defines a generally circular bore 70 extending along
the central axis X. The innermost, external surface of the nozzle
16 comprises a Coanda surface 72 located adjacent the mouth 18, and
over which the mouth 18 is arranged to direct the air emitted from
the fan 10. The Coanda surface 72 comprises a diffuser portion 74
tapering away from the central axis X. In this example, the
diffuser portion 74 is in the form of a generally frusto-conical
surface extending about the axis X, and which is inclined to the
axis X at an angle in the range from 5 to 35.degree., and in this
example is around 28.degree..
[0049] The nozzle 16 comprises an annular front casing section 76
connected to and extending about an annular rear casing section 78.
The annular sections 76, 78 of the nozzle 16 extend about the
central axis X. Each of these sections may be formed from a
plurality of connected parts, but in this embodiment each of the
front casing section 76 and the rear casing section 78 is formed
from a respective, single moulded part. The rear casing section 78
comprises a base 80 which is connected to the open upper end of the
main body section 20 of the body 12, and which has an open lower
end for receiving the primary air flow from the body 12.
[0050] With reference also to FIG. 2, during assembly, the front
end 82 of the rear casing section 78 is inserted into a slot 84
located in the front casing section 76. Each of the front end 82
and the slot 84 is generally cylindrical. The casing sections 76,
78 may be connected together using an adhesive introduced to the
slot 84.
[0051] The front casing section 76 defines the Coanda surface 72 of
the nozzle 16. The front casing section 76 and the rear casing
section 78 together define an annular interior passage 88 for
conveying the primary air flow to the mouth 18. The interior
passage 88 extends about the axis X, and is bounded by the internal
surface 90 of the front casing section 76 and the internal surface
92 of the rear casing section 78. The base 80 of the front casing
section 76 is shaped to convey the primary air flow into the
interior passage 88 of the nozzle 16.
[0052] The mouth 18 is defined by overlapping, or facing, portions
of the internal surface 92 of the rear casing section 78 and the
external surface 94 of the front casing section 76, respectively.
The mouth 18 preferably comprises an air outlet in the form of an
annular slot. The slot is preferably generally circular in shape,
and preferably has a relatively constant width in the range from
0.5 to 5 mm. In this example the air outlet has a width of around 1
mm. Spacers may be spaced about the mouth 18 for urging apart the
overlapping portions of the front casing section 76 and the rear
casing section 78 to control the width of the air outlet of the
mouth 18. These spacers may be integral with either the front
casing section 76 or the rear casing section 78. The mouth 18 is
shaped to direct the primary air flow over the external surface 94
of the front casing section 76.
[0053] To operate the fan 10 the user the user presses button 24 of
the user interface. The user interface control circuit 30
communicates this action to the main control circuit 34, in
response to which the main control circuit 34 activates the motor
44 to rotate the impeller 40. The rotation of the impeller 40
causes a primary air flow to be drawn into the body 12 through the
air inlet 14. The user may control the speed of the motor 44, and
therefore the rate at which air is drawn into the body 12 through
the air inlet 14, by manipulating the dial 28 of the user
interface. Depending on the speed of the motor 44, the primary air
flow generated by the impeller 40 may be between 10 and 30 litres
per second. The primary air flow passes sequentially through the
impeller housing 52 and the air outlet 23 at the open upper end of
the main body portion 20 to enter the interior passage 88 of the
nozzle 16. The pressure of the primary air flow at the air outlet
23 of the body 12 may be at least 150 Pa, and is preferably in the
range from 250 to 1.5 kPa.
[0054] Within the interior passage 88 of the nozzle 16, the primary
air flow is divided into two air streams which pass in opposite
directions around the bore 70 of the nozzle 16. As the air streams
pass through the interior passage 70, air is emitted through the
mouth 18. The primary air flow emitted from the mouth 18 is
directed over the Coanda surface 72 of the nozzle 16, causing a
secondary air flow to be generated by the entrainment of air from
the external environment, specifically from the region around the
mouth 18 and from around the rear of the nozzle 16. This secondary
air flow passes through the bore 70 of the nozzle 16, where it
combines with the primary air flow to produce a combined, or total,
air flow, or air current, projected forward from the nozzle 16.
[0055] With reference now also to FIGS. 3 to 8, the fan 10 includes
a first example of a mask 100 which is removably locatable over the
Coanda surface 72 of the nozzle to change at least one parameter of
the combined air flow. The mask 100 is in the form of an insert
which is insertable into the bore 70 of the nozzle 16 to cover at
least part of the Coanda surface 72 of the nozzle 16. As the
diffuser portion 74 of the Coanda surface 72, and thus the bore 70,
tapers outwardly towards the open front end 96 of the bore 70, the
mask 100 is inserted into the bore 70 of the nozzle 16 through the
open front end 96 of the bore 70. The mask 100 includes an outer
annular rim 102 which is locatable over the front end 96 of the
bore 70, and which surrounds the outer surface of the front casing
section 76 of the nozzle 16 when the mask 100 is located on the
nozzle 16. In this example the mask 100 is retained on the nozzle
16 through an interference fit between the nozzle 16 and the mask
100, but the nozzle 16 may be provided with means for removably
securing the mask 100 to the nozzle 16. For example, a movable
catch may be located on the outer surface of the front casing
section 76 of the nozzle 16 to retain the mask 100 on the nozzle
16. As another example, the mask 100 may be attracted magnetically
to the nozzle 16. As a further example, the mask 100 may be
frictionally coupled to the nozzle 16.
[0056] To remove the mask 100, the user may simply pull the mask
100 from the nozzle 16.
[0057] The mask 100 is generally annular in shape. The mask 100
comprises a generally circular front end 104 and a generally
circular rear end 106, and an annular outer surface 108 and an
annular inner surface 110 which each extend between the front end
104 and the rear end 106 of the mask 100. Each of the outer surface
108 and the inner surface 110 of the mask 100 extend about an axis
Y, which, with reference to FIG. 2, is substantially co-linear with
the axis X of the nozzle 16 when the mask 100 is inserted into the
bore 70 of the nozzle 16. The outer surface 108 of the mask 100 has
generally the same size and shape as the diffuser portion 74 of the
Coanda surface. In particular, the angle of inclination of the
outer surface 108 to the axis Y is substantially the same as the
angle of inclination of the diffuser portion 74 of the Coanda
surface 72 to the axis X, Consequently, and as shown in FIG. 8,
when the mask 100 is inserted into the bore 70 of the nozzle 16 the
diffuser portion 74 of the Coanda surface 72 is fully covered by
the mask 100, but the mouth 18 of the nozzle 16 remains fully
exposed.
[0058] Thus, when the mask 100 is inserted into the bore 70 the
primary air flow emitted from the nozzle 16 is directed over the
rear section 73 of the Coanda surface 72, as indicated in FIG. 8,
and over the inner surface 110 of the mask 100. As mentioned above,
the inner surface 110 of the mask 100 is annular in shape, and so
defines a bore 112 passing through the mask 100 between the front
end 104 and the rear end 106 of the mask 100, and through which a
secondary air flow from outside the fan 10 is drawn by the primary
air flow emitted from the mouth 18.
[0059] The inner surface 110 of the mask 100 thus provides a
diffuser surface for guiding the combined air flow generated by the
fan 10 in a desired direction. The angle of inclination of the
inner surface 110 to the axis Y is different from the angle of
inclination of the diffuser portion 74 of the Coanda surface 72 to
the axis X, and so the result of inserting the mask 100 into the
bore 70 of the nozzle 16 is that a number of parameters of the
combined air flow are changed. In this example, the angle of
inclination of the inner surface 110 to the axis Y is shallower
than the angle of inclination of the diffuser portion 74 of the
Coanda surface 72 to the axis X, and so the radial thickness of the
mask 100 decreases towards the rear end 106 of the mask 100. In
this example the angle of inclination of the inner surface 110 to
the axis Y is around 10.degree., and so the insertion of the mask
100 into the bore 70 of the nozzle 16 serves to constrict the
profile of the combined air flow produced by the fan 10. This can
provide a combined air flow which is focussed towards a user
located in front of the fan 10. The shallower diffuser portion
provided by the mask 100 also serves to increase the velocity of
the combined air flow, and to decrease the flow rate of the
combined air flow.
[0060] FIGS. 9 and 10 illustrate a second example of a mask 120
which is removably locatable over the Coanda surface 72 of the
nozzle to change at least one parameter of the combined air flow.
Similar to the mask 100, the mask 120 is also in the form of an
insert which is insertable into the bore 70 of the nozzle 16 to
cover at least part of the Coanda surface 72 of the nozzle 16. The
mask 120 also includes an outer annular rim 122 which is locatable
over the front end 96 of the bore 70, and which surrounds the outer
surface of the front casing section 76 of the nozzle 16 when the
mask 100 is located on the nozzle 16. However, this mask 120 varies
from the mask 100 insofar as the front end 124, rear end 126, outer
surface 128 and inner surface 130 of the mask 120 are not
continuous. Instead, the mask 120 comprises a plurality of sections
132 which are connected by the annular rim 122, and which are
located about, and generally regularly spaced about, the axis Y of
the mask 120. In this example, the mask 120 comprises six sections
130 regularly spaced about the mask 120. Each section 132 is
generally wedge-shaped. The outer surfaces 128 each taper towards
the axis Y with the same angle of inclination as that between the
diffuser portion 74 of the Coanda surface 72 and the axis X so
that, when the mask 120 is located on the nozzle 16, the sections
132 of the mask 120 partially cover the diffuser portion 74 of the
Coanda surface 72. Similar to the inner surface 110 of the mask
100, the angle of inclination of the inner surfaces 130 to the axis
Y is shallower than the angle of inclination of the diffuser
portion 74 of the Coanda surface 72 to the axis X, and so the
radial thickness of the sections 132 decreases towards the rear
ends 126 of the sections 130. In this example the angle of
inclination of the inner surfaces 130 to the axis Y is also around
10.degree..
[0061] Thus, as illustrated in FIG. 9, when the mask 120 is
inserted into the nozzle 16 through the open front end 96 of the
bore 70, the bore 134 of the nozzle 16 is defined both by the
uncovered sections of the diffuser portion 74 of the Coanda surface
72, and by the inner surfaces 130 of the mask 120. The bore 134 of
the nozzle 126 thus has a stepped profile, in which the angle of
inclination of the bore 134 to the axis X varies between a
plurality of maximum values, in this example each at around
28.degree., and a plurality of minimum values, in this example each
at around 10.degree.. This variation in the profile of the bore 134
of the nozzle 16 causes the combined air flow to have a
non-circular, or non-frusto-conical, profile which is only
partially focussed towards the user due to the discontinuities in
the mask 120.
[0062] In this second example, the insertion of the mask 120 into
the nozzle 16 results in the bore 134 of the nozzle 16 adopting a
stepped profile. FIGS. 11 and 12 illustrate a third example of a
mask 140. This mask 140 is similar to the mask 100. The mask 140 is
also in the form of an insert which is insertable into the bore 70
of the nozzle 16 to cover at least part of the Coanda surface 72 of
the nozzle 16. The mask 140 also includes an outer annular rim 142
which is locatable over the front end 96 of the bore 70, and which
surrounds the outer surface of the front casing section 76 of the
nozzle 16 when the mask 100 is located on the nozzle 16. The mask
140 also has a continuous front end 144, and a circular rear end
146, an annular outer surface 148 and an annular inner surface 150
which defines a bore 152. The outer surface 148 of the mask 140 is
identical to the outer surface 108 of the mask 100. However, the
inner surface 150 of the mask 140 differs from the inner surface
110 of the mask 100 insofar as the angle of inclination of the
inner surface 150 to the axis Y of the mask 140 varies about the
axis Y. This angle of inclination varies between a plurality of
maximum values and a plurality of minimum values which are
regularly spaced about the axis Y. The inner surface 150 is shaped
so as to vary the angle of inclination gradually about the axis Y
between the maximum and minimum values.
[0063] Thus, when the mask 140 is inserted into the bore 70 of the
nozzle 16, the inner surface 150 of the mask 140 also provides a
diffuser surface for guiding the combined air flow generated by the
fan 10 so as to adopt a non-circular or non-frusto-conical profile.
Similar also to the mask 120, the mask 140 is rotatable relative to
the nozzle 16 to change the orientation of the combined air flow
generated by the fan.
* * * * *