U.S. patent application number 10/592161 was filed with the patent office on 2007-08-23 for fan,especially a ceiling fan with a balanced single blande.
Invention is credited to Daniel Gasser, Michael J. Hort, John M. Levey.
Application Number | 20070196212 10/592161 |
Document ID | / |
Family ID | 34916883 |
Filed Date | 2007-08-23 |
United States Patent
Application |
20070196212 |
Kind Code |
A1 |
Hort; Michael J. ; et
al. |
August 23, 2007 |
Fan,especially a ceiling fan with a balanced single blande
Abstract
The invention provides a fan (10) with a blade (12), suitable
for use as a ceiling fan. Blade (12) may be regarded as a single
blade, although shaft (18) is not attached to blade (12) at one end
thereof; rather, shaft (18) is attached to blade (12) at a point
between first end (14) and second end (16). Blade (12) is balanced
by counterweight means (22) located in blade (12). In on
embodiment, blade (12) is connected to shaft (18) by means which
permit angular movement, such as a teeter hinge.
Inventors: |
Hort; Michael J.;
(Chatswood, AU) ; Gasser; Daniel; (Tamarama,
AU) ; Levey; John M.; (Bondi, AU) |
Correspondence
Address: |
TRASK BRITT
P.O. BOX 2550
SALT LAKE CITY
UT
84110
US
|
Family ID: |
34916883 |
Appl. No.: |
10/592161 |
Filed: |
March 8, 2005 |
PCT Filed: |
March 8, 2005 |
PCT NO: |
PCT/AU05/00316 |
371 Date: |
December 14, 2006 |
Current U.S.
Class: |
416/229R |
Current CPC
Class: |
F04D 29/384 20130101;
F04D 29/662 20130101; F04D 29/36 20130101; F04D 25/088
20130101 |
Class at
Publication: |
416/229.00R |
International
Class: |
F04D 29/38 20060101
F04D029/38 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2004 |
AU |
2004901170 |
Claims
1. A blade for a fan comprising: a first portion having a first
end; a second portion having a second end, the second end opposed
to the first end; and at least one counterweight coupled to one of
the first portion and the second portion, both the first and the
second portions are adapted to provide aerodynamic lift.
2. The blade of claim 1, wherein the first portion has a first
leading edge and a first trailing edge; the second portion has a
second leading edge and a second trailing edge; and the aerodynamic
lift provided by the second portion at least partially balances the
aerodynamic lift provided by the first portion.
3. The blade of claim 1, further comprising a connection point
located between the first end and the second end, the connection
point for coupling to a shaft.
4. The blade of claim 3, wherein the connection point is located at
a junction between the first and the second portions.
5. The blade of claim 3, wherein the center of mass approximately
aligns with the connection point.
6. The blade of claim 3, wherein the connection point is closer to
the second end than the first end and at least one counterweight is
located in the second portion.
7. The blade of claim 3, wherein an angle of approximately 170
degrees between the first end and the second end, and the angle
being proximate the connection point.
8. The blade of claim 3, further comprising a variable pitch
connector coupled to the connection point, the variable pitch
connector permits angular movement relative to a shaft when coupled
thereto.
9. The blade of claim 8, wherein the variable pitch connector
includes a teeter hinge.
10. The blade of claim 8, wherein the variable pitch connector is
located proximate to the center of mass of the blade.
11. The blade of claim 8, further comprising a shaft coupled to the
variable pitch connector, and a fan motor coupled to the shaft for
rotationally driving the shaft, wherein at any given speed of
rotation, the first end will rise until a position is found at
which the aerodynamic, gravitational and centripetal forces acting
on the blade are balanced to minimize or eliminate any bending
moment on the shaft.
12. The blade of claim 11, wherein a point on the first leading
edge is constrained to rotate about the variable pitch connector in
a plane in which the aerodynamic lift force of the blade on the
first leading edge is acting to maintain the correct angle of
attack of the blade.
13. The blade of claim 11 wherein, when viewed in plan, the axis of
the variable pitch connector is perpendicular to a line drawn from
the axis of rotation of the blade when balanced to the center of
lift of the first portion.
14. The blade of claim 1, wherein all of the at least one
counterweights is located in the first and second portions.
15. The blade of claim 11, wherein part of the at least one
counterweight is located on the shaft.
16. The blade of claim 2, wherein some or all of the at least one
counterweight is located along the first leading edge of the
blade.
17. The blade of claim 2, wherein some of the at least one
counterweight is located along the first leading edge of the first
portion and some of the at least one counter weight is located
along the first trailing edge of the first portion.
18. The blade of claim 11, further comprising a mounting plate
coupled to the fan motor for selectively attaching to a
ceiling.
19. (canceled)
20. (canceled)
21. A fan assembly comprising: a blade comprising: a first portion
having a first end; a second portion having a second end, the
second end opposed to the first end, the blade adapted to provide
aerodynamic lift when rotationally driven; and a connection point
located between the first end and the second end; a shaft; a
variable pitch connector coupled to the connection point of the
blade and to the shaft, the variable pitch connector permits
angular movement relative between the shaft and the blade; at least
one counterweight coupled to either of the blade and the shaft; and
a fan motor coupled to the shaft for rotationally driving the
shaft.
22. The fan of claim 21, wherein at any given speed of rotation
when driven by the motor, the first end of the first portion of the
blade will rise until a position is found at which the aerodynamic,
gravitational and centripetal forces acting on the blade are
balanced to minimize or eliminate any bending moment on the shaft.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to fans and, in particular, to
a ceiling fan which is balanced. The invention is especially
concerned with the type of ceiling fan which may be regarded as
having a single blade.
BACKGROUND OF THE INVENTION
[0002] Single blade ceiling fans are desirable because,
potentially, they may produce less drag, thereby increasing the
efficiency of the fan. This means that greater air flow may be
accomplished at lower rotational speeds. Another potential
advantage with a single blade is that the weight of the fan may be
reduced, thus allowing the span of the blade to be of a larger
dimension, compared to a conventional blade for a multi-bladed
fan.
[0003] However, there have been problems in balancing single-blade
fans. Counterweights have been applied to the shaft of the fan, or
opposite the mass of the blade. An attempt to address the problem
has been made in U.S. Pat. No. 6,726,451, where the ceiling fan
blade mounting arrangement produces a centre of rotational gravity
that lies outside the vertical axis of the rotating fan.
[0004] It is an object of the present invention to provide a
ceiling fan which can be balanced both statically and dynamically,
for stabilised rotation at high and low rotational speeds. It is
also an object of the present invention, in a preferred embodiment,
to provide a ceiling fan which can be an architectural feature,
being aesthetically pleasing. In the preferred embodiment, the
single bladed fan has a blade similar to the shape of a sycamore
seed pod, and thus can have a sculptured shape, which may be
appreciated even when the fan is not in use. It is believed that
such a shape has aerodynamic advantages compared to the shape of a
conventional blade.
DISCLOSURE OF THE INVENTION
[0005] Accordingly, the present invention provides a fan including
a blade having a first end, a second end, a leading edge and a
trailing edge, the blade being rotatable by a shaft connected to a
motor, wherein the blade is balanced by counterweight means, at
least some of which is located in the blade.
[0006] The fan of the invention is preferably a ceiling fan but is
not limited thereto.
[0007] The invention also provides a blade for a fan, the blade
having a first end, a second end, a leading edge and a trailing
edge, the blade being adapted for rotation by a shaft connected to
a motor, wherein the blade includes counterweight means.
[0008] The blade may be constructed of any suitable material. The
material may be a solid low density material or a high density
material, such as metal, polymer or wood. The blade may be made
from a thin rigid skin filled with foam reinforcing, such as
self-skinning polyurethane. Preferably, the fan is made by
extrusion blow moulding or reaction injection moulding or other
suitable technique, such as metal casting.
[0009] Preferably, the blade is an irregular sculptured form. Even
more preferably, the blade takes the form of or is adapted from the
shape of a sycamore seed pod. The blades in the drawings below are
adapted from the shape of a sycamore seed pod. Such a blade is not
flat as many conventional fan blades are, but has curves and
contours.
[0010] In this embodiment, the blade has an aerofoil cross section,
with varying vertical thickness from the leading edge to the
trailing edge. The aerofoil part of the blade is designed to create
less turbulence and drag in its wake. It may require less energy to
rotate it about its vertical axis compared to a conventional flat
blade and it may also create less wind noise. The aerofoil design
may also create higher airflow at lower speeds, compared to
conventional ceiling fans.
[0011] The blade in this embodiment may be wider than many
conventional fan blades. At low speed, a longer chord length
aerofoil section is more efficient. The first and second ends are
shaped to be curved--preferably elliptical. It is known that
aircraft wings with elliptical wing tips (in plan view) produce
less turbulence than square ended wing tips at low speed.
[0012] In this preferred embodiment, the blade is not linear in
plan view but is angled. In this configuration, there is an angle
of approximately 170 degrees between the first end and the second
end.
[0013] The shaft and the motor may be of any suitable shape or
arrangement. Preferably, the blade is attached to the shaft at a
connection point located between the first end and the second end.
It is also preferred that the connection point is closer to the
second end than to the first end. Where the blade is bent so that
there is an angle of approximately 170 degrees between the first
end and the second end, it is preferred that the connection point
is at or located close to the angle of bend.
[0014] It will be appreciated that the blade of the fan of the
present invention may be regarded as a single blade because,
although the connection point is preferably located between the
first end and the second end, being closer to the second end than
to the first end, the whole blade is a single unit. Another view
may be taken of the blade: the portion of the blade from the
connection point to the first end may be regarded as the primary
blade and the portion of the blade from the connection point to the
second end may be regarded as a pod, in view of the similarity to a
sycamore seed pod. The pod preferably has its leading edge higher
than its trailing edge. The pod may not contribute greatly to air
flow provided by the fan of the invention. However, the pod may
provide aero dynamic lift which can partially balance aero dynamic
lift created by the primary blade. In addition, the pod as
illustrated in the drawings, below, may be designed to create
minimum turbulence in its wake, in order to minimise the energy
required to overcome its aero dynamic drag.
[0015] The organic form shape, profile and relative orientation of
the primary blade and pod of the blade of the invention in this
embodiment have been designed to allow the incorporation of at
least some of the counterweight means within the form of the blade.
The purpose of this is to avoid interruption of the continuous
sculptural surface of the blade of the invention whilst allowing
the position of the centre of gravity of the blade to be located
within the blade.
[0016] In the embodiment under discussion, the blade of the
invention has been designed so that incorporation of at least some
of the counterweight means in the pod causes the centre of mass of
the blade of the invention to lie at a point within the blade in
top plan view. In addition, the position and mass of the
counterweight means may be adjusted to ensure that the combined
centre of mass of the blade of the invention and the counterweight
means is located on the vertical axis of rotation of the blade of
the invention.
[0017] In an especially preferred embodiment, the blade is
connected to the shaft by means adapted to permit angular movement
of the blade relative to the shaft. Preferably, these means include
or comprise the type of hinge known as a teeter hinge, an example
of which is illustrated in the drawings.
[0018] It is also preferred that the centre of mass of the blade of
the invention and the counterweight means is located within the
body of the blade of the invention, when the blade is viewed in
front elevation. The shape, profile and relative orientation of the
primary blade and pod may be determined to ensure that the centre
of mass is sufficiently far within the blade form to allow all the
components required to permit angular movement of the blade
relative to the shaft to be located within the blade without
compromising the sculptural integrity of the blade form.
[0019] The counterweight means preferably includes at least one
discrete mass of material. The counterweight means may comprise two
or more discrete masses of such material. All the counterweight
means may be located in the blade. Alternately, some of the
counterweight means may be located in the blade and some elsewhere
such as on the shaft. The material of one discrete mass may be the
same as or different from the material of another discrete mass in
the same fan. In one embodiment, the counterweight means is made of
a material having a mass greater than that of the material of the
blade. In another embodiment, the counterweight means is made of a
material having a mass lesser than that of the material of the
blade. In yet another embodiment, the counterweight means is
provided by increasing wall thickness within the blade, for example
during manufacture. For example, the blade may be manufactured by
extrusion blow moulding. During manufacture, the wall thickness of
selected parts of the blade may be increased in order to provide
all or some of the counterweight means.
[0020] By way of another example, a blade may be moulded in two
halves, such as top and bottom, by a reaction injection moulding
process or other suitable technique, such as metal
casting--aluminium or magnesium, fibreglass layup or wood shaping,
with different, varying wall sections as required to provide some
or all of the counterweight means, prior to joining the two halves
to create the complete blade.
[0021] Preferably, the location of at least some of the
counterweight means is adjustable, so that compensation can be made
for manufacturing tolerances. Preferably also, additional
counterweights may be added to the fan of the invention for tuning
the balance during manufacture. In one embodiment, these are
located under a removable cover on the blade. The same cover can
cover a cavity into which some or all of the counterweight means
may be inserted. Such a cover may be sculpted to match the surface
form of the blade or may be a simple flat or round infill, on the
top surface of the blade.
[0022] Of course, any counterweight means located in the blade may
be assembled into a pocket in the exterior of the blade (with or
without a cover) or moulded into the surface of the blade (with or
without a cover).
[0023] Where all the counterweight means is not located in the
blade, it is preferred that part of the counterweight means is
located on the shaft.
[0024] It is preferred that some or all of the counterweight means
is located along the leading edge of the blade. Part of the
counterweight means may be located along the leading edge and part
along the trailing along the blade.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The present invention will now be described in connection
with certain non-limiting thereof as set out in the accompanying
drawings, in which:
[0026] FIG. 1 is a side elevation of a first embodiment of a
ceiling fan, viewed from the trailing edge;
[0027] FIG. 2 is a side elevation of the fan of FIG. 1, viewed from
the leading edge;
[0028] FIG. 3 is a side elevation of a second embodiment of fan,
viewed from the leading edge;
[0029] FIG. 4 is a side elevation of a blade for a further
embodiment of a ceiling fan, viewed from the leading edge;
[0030] FIG. 5 is a top plan view of the blade of FIG. 4;
[0031] FIG. 6 is a perspective view of the blade of FIGS. 4 and 5,
cut away at the second end to show internal construction;
[0032] FIG. 7 is a top plan view of a further embodiment of a
blade;
[0033] FIG. 8 is a top plan view of the second embodiment of a
blade of FIG. 3;
[0034] FIG. 9 is a perspective view of a further embodiment of a
blade which includes a teeter hinge;
[0035] FIG. 10 shows in more detail the connection point and part
of the teeter hinge of the FIG. 9 embodiment;
[0036] FIG. 11 shows the second end of the blade of FIGS. 9 and 10,
with counterweight means within the blade in dotted outline;
[0037] FIG. 12 is a partial cross-sectional view of the blade of
FIGS. 9, 10 and 11 taken along the line A-A of FIG. 10;
[0038] FIG. 13 shows cross-sectional detail of the blade taken
along the line B-B of FIG. 10; and
[0039] FIG. 14 shows the teeter hinge and connection point
illustrated in sectional view in FIG. 13
BEST MODES OF CARRYING OUT THE INVENTION
[0040] Referring first to FIG. 1, ceiling fan 10 has a blade 12
which can be regarded as a single blade having first end 14 and
second end 16. Blade 12 is sculptured in a form similar to that of
a sycamore seed pod. It is curved and designed to provide a
downward draught when it rotates clockwise (as viewed from
above).
[0041] Blade 12 is rotatable by a shaft 18, connected to an
electric motor (not shown) within motor cover 20.
[0042] As can be seen from FIGS. 1 and 2, blade 12 is irregular in
shape and is fixed to shaft 18 closer to second end 16 than to
first end 14.
[0043] In this embodiment, the counterweight means is comprised of
a balancing weight 22 located along leading edge 24 of the primary
blade (that part between shaft 18 and first end 14) and along the
trailing edge of the pod (that part between shaft 18 and second end
16) and close to second end 16. Balancing weight 22 is made from a
material which is of greater density than the material of blade 12.
Weight 22 comprises a single discrete mass and is moulded to follow
the contours of blade 12 so that it is unobtrusive.
[0044] Because there is no counterweight attached to shaft 18,
motor cover 20 does not need to be enlarged to accommodate any such
weight, and indeed may be somewhat smaller than that
illustrated.
[0045] FIG. 3 shows a similar embodiment to the embodiment in FIGS.
1 and 2 and the same numbers are used for the same parts as in
FIGS. 1 and 2. In the FIG. 3 embodiment, a counterweight 28 is
located in blade 12 very close to second end 16. In this
embodiment, however, weight 28 is somewhat smaller in mass than
weight 22 of FIG. 2. There is a second discrete weight 30 (not
visible in the figure) attached to shaft 18. The combination of the
weights 28 and 30 balances blade 12 when rotating.
[0046] If desired, weight 30 on shaft 18 could be divided into two
masses and distributed around shaft 18.
[0047] Referring now to FIGS. 4, 5 and 6, although this is a
different embodiment from the embodiment of FIGS. 1 and 2 and the
embodiment of FIG. 3, the same part numbers will be used where the
parts are the same or very similar. In this embodiment, blade 12
has substantially elliptical first end 14, substantially elliptical
second end 16, leading edge 24 and trailing edge 26. As shown by
the plan view of FIG. 5, blade 12 is curved at leading edge 24 and
there is an angle of approximately 170.degree. between first end 14
and second end 16. Located at approximately the bend point is
connection point 32. In this embodiment, connection point 32 is a
circular aperture adapted to receive shaft 18 (not shown).
Connection point 32 may be of any other suitable shape.
[0048] Blade 12 includes two discrete masses by way of
counterweight means, first mass 34 and second mass 36. Each of
masses 34 and 36 is inserted within blade 12. Part of second mass
36 can be seen in FIG. 6, inserted in cavity 38. Cover 40 covers
first mass 34 and cover 42 covers second mass 36. Each of covers 40
and 42 is removable, so that the mass in the underlying cavity may
be removed or changed as appropriate.
[0049] It will also be noted from FIG. 6 that blade 12 is generally
hollow, being made of thermoplastic polymer material, such as ABS
or high density polyethylene.
[0050] The embodiment in FIG. 7 is similar to that in FIGS. 4, 5
and 6, except that first 34 and second mass 36 are replaced by a
single mass 44.
[0051] The FIG. 8 embodiment shows in top plan view the embodiment
discussed above in connection with FIG. 3.
[0052] In the fiber embodiment shown in FIGS. 9, 10 and 11, a
single discrete mass or a plurality of masses may be inserted in
cavity 48 covered by cover 50. Cavity 48 is extended in this
embodiment to accommodate connection point 32 and teeter hinge 52,
discussed in more detail in connection with FIGS. 12, 13 and 14
below.
[0053] Shown in ghosted outline in FIG. 11 is a single discrete
mass 54 suspended within blade 12 by bracket 56.
[0054] Details of teeter hinge 52 can be seen in FIGS. 12, 13 and
14. Teeter hinge 52 can be applied to any of the embodiments
illustrated herein in FIGS. 4, 5, 6, 7, 9, 10 and 11.
[0055] Teeter hinge 52 has cross bar 58 originally attached or
integral with (as in this case) plates 60 and 62. Cross bar 58
includes screw hole apertures 64 into which are fitted screws 66
which serve to secure cross bar 58 to blade 12 (refer FIG. 13).
[0056] Connection point 32, which connects blade 12 to shaft 18
(not shown) has tail 68. Aperture 70 in tail 68 receives pivot pin
72 to connect tail 68 pivotably to plate 60 and 62.
[0057] As can be seen from FIGS. 13 and 14, there is a small amount
of clearance between the inner ends of cross bar 58 and tail 68, so
that connection point 32 can pivot to a small extent around pivot
pin 72.
[0058] Blade 12 and the location of the counterweights are designed
so that the centre of mass of blade 12 (when viewed in plan) is
located approximately in the location of connection point 32 and
drive shaft 18 (not shown). Also when viewed in plan, the pivot
axis is perpendicular to a line drawn from the axis of rotation of
the balanced blade to the centre of lift of the blade portion of
the balanced blade. The pivot axis is also aligned with the
horizontal plane. The tip of blade 12 is thus free to move in a
vertical direction by rotating about the pivot, but is constrained
to rotate only in the plane in which the aerodynamic lift force of
the blade is acting, thus maintaining the correct angle of attach
of the blade.
[0059] This is in contrast to conventional fans, where the blades
are generally rigidly connected to the motor housing or drive
shaft.
[0060] It will be appreciated that the aerodynamic centre of blade
12--the point at which lift is deemed to act--will vary, depending
on air speed of blade 12 and also on the pitch of blade 12. The
aerodynamic force on blade 12 is composed of both lift from blade
12 and also of lift and drag from blade 12, including lift and drag
from the part of blade 12 near second end 16. It is preferred that
the combined centre of action of these forces is the point which is
used to define the line to which the pivot axis is perpendicular.
The aerodynamic forces involved are relatively small and
consequently the calculation of the angle of the pivot axis may be
represented by a range of values.
[0061] Because blade 12 is suspended at the centre of mass on the
pivot, blade 12 is free to find its own balance--the position where
the centre of mass lies on the vertical axis of rotation and the
principal axes of inertia of the centre of gravity of balanced
blade 12 lie in the vertical and horizontal planes. It is believed
that if blade 12 were rigidly mounted and were balanced such that
the principal axes of inertia of the centre of gravity were not in
the horizontal/vertical planes, even though the centre of gravity
might be on the vertical axis, the centrifugal forces would not be
balanced and rotation of the blade would shake the bearings of the
motor.
[0062] When blade 12 is supported at the centre of mass of the
balanced blade, and blade 12 is allowed to "self level" because of
teeter hinge 52, it has been found that the mass of blade 12 does
not impart unwanted centrifugal forces to shaft 18 which would
cause blade 12 to run off centre or wobble, cause unwanted
vibrations or wear within the motor and/or transmit undue stresses
to the mechanism used to fasten the fan assembly to the ceiling.
Because the pivot is incorporated at the centre of mass, blade 12
can rotate about this freely. The aerodynamic forces acting on
blade 12 cause blade 12 to rotate until the aerodynamic forces are
matched by the gravitational and centripetal forces acting on blade
12. Thus, at any given speed, first end 14 will rise until the
position is found at which the aerodynamic forces and the
gravitational and centripetal forces acting on blade 12 are in
balance. Any bending moment on shaft 18 may thus be eliminated or
minimised, and fan 10 may run smoothly with no or minimal
out-of-balance forces being transmitted to shaft 18, etc.
INDUSTRIAL APPLICABILITY
[0063] The fan of the invention provides a worthwhile addition to
fan technology, especially where ceiling fans are involved. The fan
of the invention can be presented in a modem, streamlined form
which can cause movement of a greater is volume of air with less
rotational speed.
* * * * *