U.S. patent application number 14/461630 was filed with the patent office on 2015-01-29 for electric motor and brake assembly.
The applicant listed for this patent is Invacare Corporation. Invention is credited to Robert Bekoscke, John Jindra, Nirav Pandya, Thomas Tuckowski, George H. Waterman.
Application Number | 20150027824 14/461630 |
Document ID | / |
Family ID | 45348532 |
Filed Date | 2015-01-29 |
United States Patent
Application |
20150027824 |
Kind Code |
A1 |
Pandya; Nirav ; et
al. |
January 29, 2015 |
ELECTRIC MOTOR AND BRAKE ASSEMBLY
Abstract
A motor and brake assembly includes a mounting member. A stator
winding assembly, a brake assembly, a hub, and a rotor magnet
assembly. The stator winding assembly is mounted to the mounting
member. The brake assembly is operably connected to the mounting
member. The hub is rotatably coupled to the mounting member. The
rotor magnet assembly is mounted to an inside of a radially outer
wall of the hub. The brake assembly is operable to move a component
of the brake assembly between an engaged position where the
component engages the inside of the radially outer hub wall and a
disengaged position where the component is spaced apart from the
inside of the radially outer hub wall.
Inventors: |
Pandya; Nirav; (North
Olmsted, OH) ; Tuckowski; Thomas; (Strongsville,
OH) ; Jindra; John; (Elyria, OH) ; Bekoscke;
Robert; (Medina, OH) ; Waterman; George H.;
(Plymouth, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Invacare Corporation |
Elyria |
OH |
US |
|
|
Family ID: |
45348532 |
Appl. No.: |
14/461630 |
Filed: |
August 18, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13160931 |
Jun 15, 2011 |
8807251 |
|
|
14461630 |
|
|
|
|
61354846 |
Jun 15, 2010 |
|
|
|
61412041 |
Nov 10, 2010 |
|
|
|
Current U.S.
Class: |
188/164 |
Current CPC
Class: |
H02K 7/102 20130101;
B60L 2220/50 20130101; F16D 2123/00 20130101; F16D 2121/26
20130101; B60K 7/0007 20130101; A61G 5/04 20130101; F16D 2121/22
20130101; F16D 2121/18 20130101; F16D 51/48 20130101; F16D 65/14
20130101; F16D 2127/04 20130101; Y02T 10/64 20130101; F16D 2125/30
20130101; A61G 5/1008 20130101; H02K 21/222 20130101; F16D 2066/003
20130101; F16D 2121/14 20130101; Y02T 10/641 20130101; B60K
2007/0092 20130101; B60L 7/24 20130101; F16D 65/08 20130101; B60L
2200/16 20130101; B60Y 2200/84 20130101; F16D 2121/20 20130101;
B60K 2007/0038 20130101; A61G 5/1032 20130101 |
Class at
Publication: |
188/164 |
International
Class: |
F16D 65/14 20060101
F16D065/14; F16D 51/48 20060101 F16D051/48 |
Claims
1-46. (canceled)
47. A brake actuator comprising: an electromagnet; a first shaft
that includes a frusto-conical recess that includes an inner
tapered surface and a flat inner wall; a second shaft that includes
a male frusto-conical end portion that includes an outer tapered
surface and a flat end wall; wherein application of an
electromagnetic field by the electromagnet relatively moves the
first and second shafts from an extended position to a retracted
position; wherein when the first and second shafts are in the
retracted position, the flat end wall of the second shaft is in
engagement with the flat inner wall of the first shaft.
48. The actuator of claim 47 wherein the inner tapered surface of
the first shaft is spaced apart from the outer tapered surface of
the second shaft when the flat end wall of the second shaft is in
engagement with the flat inner wall of the first shaft.
49. The actuator of claim 47 wherein application of said
electromagnetic field by said electromagnet moves said first
shaft.
50. The actuator of claim 47 wherein application of said
electromagnetic field by said electromagnet moves said second
shaft.
51. The actuator of claim 47 further comprising a housing disposed
around the electromagnet, a portion of the first shaft, and a
portion of the second shaft.
52. The actuator of claim 47 further comprising a spring that
biases the first and second shafts from the retracted position
toward said extended position.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation application of
U.S. Ser. No. 13/160,931, filed Jun. 15, 2011, titled ELECTRIC
MOTOR AND BRAKE ASSEMBLY, which claims priority to Provisional
Application Ser. No. 61/354,846 filed Jun. 15, 2010 and Provisional
Application Ser. No. 61/412,041 filed Nov. 10, 2010, the
disclosures of which are incorporated herein by reference in their
entirety.
BACKGROUND
[0002] Electric motor and brake assemblies can be used in a wide
variety of different conveyances. In one exemplary embodiment, the
electric motors are used to drive wheelchairs and similar
conveyances. Wheelchairs and similar conveyances are an important
means of transportation for a significant portion of society.
Powered wheelchairs provide an important degree of independence for
those they assist.
SUMMARY
[0003] The present application discloses exemplary embodiments of
motor and brake assemblies and components for motor and/or brake
assemblies. In one exemplary embodiment, a motor and brake assembly
includes a mounting member. A stator winding assembly, a brake
assembly, a hub, and a rotor magnet assembly. The stator winding
assembly is mounted to the mounting member. The brake assembly is
operably connected to the mounting member. The hub is rotatably
coupled to the mounting member. The rotor magnet assembly is
mounted to an inside of a radially outer wall of the hub. The brake
assembly is operable to move a component of the brake assembly
between an engaged position where the component engages the inside
of the radially outer hub wall and a disengaged position where the
component is spaced apart from the inside of the radially outer hub
wall.
[0004] In one exemplary embodiment, a release actuator is coupled
to the brake assembly. The release actuator is moveable between a
release position or condition and a normal operation position or
condition. When the release actuator is moved to the release
position or condition, the release actuator moves the component of
the brake assembly away from said inside of the radially outer hub
wall and prevents the component of the brake assembly from moving
to the engaged position. When the release actuator is in the normal
operating position, the service actuator is able to move said
component from the disengaged position to said engaged
position.
[0005] In one exemplary embodiment, an actuator for a brake
assembly includes an electromagnet, a first shaft, and a second
shaft. The first shaft includes a frusto-conical recess that
includes an inner tapered surface and a flat inner wall. The second
shaft includes a male frusto-conical end portion that includes an
outer tapered surface and a flat end wall. Application of an
electromagnetic field by the electromagnet relatively moves the
first and second shafts from an extended position to a retracted
position. When the first and second shafts are in the retracted
position, the flat end wall of the second shaft is in engagement
with the flat inner wall of the first shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] In the accompanying drawings which are incorporated in and
constitute a part of the specification, embodiments of the
invention are illustrated, which, together with a general
description of the invention given above, and the detailed
description given below, serve to example the principles of this
invention.
[0007] FIG. 1 is a perspective view of an exemplary embodiment of a
wheelchair, with a seat assembly separated from a chassis
assembly;
[0008] FIG. 1A is a perspective view of an exemplary embodiment of
a wheelchair;
[0009] FIG. 1B is a schematic illustration, in section, of an
exemplary embodiment of a hub motor and brake assembly;
[0010] FIG. 1C is an illustration similar to FIG. 1B with the brake
assembly in an engaged position;
[0011] FIG. 1D is an illustration similar to FIG. 1B where the
brake assembly includes a brake lining;
[0012] FIG. 1E is an illustration similar to FIG. 1D with the brake
assembly in an engaged position;
[0013] FIG. 1F is a schematic illustration, in section, of an
exemplary embodiment of a hub motor and brake assembly that
includes a brake assembly release actuator;
[0014] FIG. 1G is an illustration similar to FIG. 1F with the brake
assembly in an engaged position;
[0015] FIG. 2A is a perspective view of an exemplary embodiment of
a hub motor and brake assembly;
[0016] FIG. 2B is a second perspective view of the hub motor and
brake assembly shown in FIG. 2A;
[0017] FIG. 2C is a side elevational view of the hub motor and
brake assembly shown in FIG. 2A;
[0018] FIG. 2D is a rear view of the hub motor and brake assembly
shown in FIG. 2A;
[0019] FIG. 2E is a front view of the hub motor and brake assembly
shown in FIG. 2A;
[0020] FIG. 2F illustrates a sealing arrangement between a release
actuator and a hub;
[0021] FIG. 2G is an exploded perspective view of the sealing
arrangement shown in FIG. 2F;
[0022] FIG. 2H is a view similar to FIG. 2G with the hub
removed;
[0023] FIG. 3A is an exploded perspective view showing components
of the hub motor and brake assembly shown in FIG. 2A;
[0024] FIG. 3B is an exploded perspective view showing components
of the hub motor and brake assembly shown in FIG. 2A;
[0025] FIG. 4A is a perspective view of the hub motor and brake
assembly shown in FIG. 2A with a portion of a rotor housing
assembly removed;
[0026] FIG. 4B is a front view of the hub motor and brake assembly
shown in FIG. 2A with a portion of a rotor housing assembly
removed;
[0027] FIG. 5A is a perspective view of an exemplary embodiment of
a mounting plate for a hub motor and/or brake assembly;
[0028] FIG. 5B is a second perspective view of the mounting plate
shown in FIG. 5A;
[0029] FIG. 5C is a rear view of the mounting plate shown in FIG.
5A;
[0030] FIG. 5D is a front view of the mounting plate shown in FIG.
5A;
[0031] FIG. 6A is a sectioned perspective view of an exemplary
embodiment of a rotor housing assembly;
[0032] FIG. 6B is an exploded perspective view of an exemplary
embodiment of a rotor housing and mounting plate assembly;
[0033] FIG. 6C is a sectioned exploded perspective view the rotor
housing and mounting plate assembly shown in FIG. 6B;
[0034] FIG. 6D is a sectioned view of an exemplary embodiment of a
rotor housing and mounting plate assembly;
[0035] FIG. 7A is an exploded perspective view showing an exemplary
embodiment of a mounting plate, an exemplary embodiment of a stator
armature, and an exemplary embodiment of a rotor magnet ring
assembly;
[0036] FIG. 7B is a perspective view of the hub motor and brake
assembly shown in FIG. 2A with a portion of a rotor housing
assembly and other components removed;
[0037] FIG. 7C is a front view of the hub motor and brake assembly
shown in FIG. 2A with a portion of a rotor housing assembly and
other components removed;
[0038] FIG. 8A is an elevational view of an exemplary embodiment of
a brake assembly;
[0039] FIG. 8B is an exploded perspective view of an exemplary
embodiment of a brake assembly;
[0040] FIG. 8C is an elevational view of an exemplary embodiment of
a brake assembly;
[0041] FIG. 8D is a perspective view of an exemplary embodiment of
a brake assembly;
[0042] FIG. 9A is a perspective view of an exemplary embodiment of
a brake shoe assembly;
[0043] FIG. 9B is a front view of the brake shoe assembly shown in
FIG. 9A;
[0044] FIG. 9C is a side view of the brake shoe assembly shown in
FIG. 9A;
[0045] FIG. 10A is an enlarged portion of FIG. 8A, as indicated in
FIG. 8A;
[0046] FIG. 10B is a view similar to the view of FIG. 10A showing
the brake shoes in a position where the brake pads are engaged with
the rotor housing assembly;
[0047] FIG. 11 is a perspective view of an exemplary embodiment of
an actuator;
[0048] FIG. 12 is a perspective view of an exemplary embodiment of
a brake link;
[0049] FIG. 13 is an elevational view of an exemplary embodiment of
a brake assembly in a position where the brakes are released by an
actuator;
[0050] FIGS. 13A and 13B are elevational views of the brake
assembly shown in FIG. 13 with a brake release mechanism in two
different positions that allow normal operation of the brakes;
[0051] FIG. 14 is an elevational view of an exemplary embodiment of
a brake assembly in a position where the brakes are applied by an
actuator;
[0052] FIGS. 14A and 14B are elevational views of the brake
assembly shown in FIG. 14 with a brake release mechanism in a two
different positions that allow normal operation of the brakes;
[0053] FIG. 15 is an elevational view of an exemplary embodiment of
a brake assembly in a position where the brakes are released by a
manual brake release mechanism;
[0054] FIG. 15A is an exploded perspective view of the brake
assembly shown in FIG. 15;
[0055] FIG. 15B is an exploded perspective view of the brake
assembly shown in FIG. 15;
[0056] FIG. 16 is a perspective view of an exemplary embodiment of
a drive member of a manual brake release mechanism;
[0057] FIG. 17 is an enlarged perspective sectional view taken
along lines 17-17 in FIG. 8A;
[0058] FIG. 18A is a first exploded perspective view of another
exemplary embodiment of a hub motor and brake assembly;
[0059] FIG. 18B is a second exploded perspective view of the hub
motor and brake assembly shown in FIG. 18A;
[0060] FIG. 19A is a first perspective view of an exemplary
embodiment of a mounting plate and stator armature assembly;
[0061] FIG. 19B is a second perspective view of the mounting plate
and stator armature assembly shown in FIG. 19A;
[0062] FIG. 19C is a third perspective view of the mounting plate
and stator armature assembly shown in FIG. 19A;
[0063] FIG. 20A is a perspective view of an exemplary embodiment of
a mounting plate for a hub motor and/or brake assembly;
[0064] FIG. 20B is a second perspective view of the mounting plate
shown in FIG. 20A;
[0065] FIG. 21A is an exploded perspective view of an exemplary
embodiment of a rotor housing and mounting plate assembly;
[0066] FIG. 21B is a sectioned exploded perspective view of the
rotor housing and mounting plate assembly shown in FIG. 21A;
[0067] FIG. 21C is a perspective view of a rotor housing and magnet
ring assembly;
[0068] FIG. 22A is an elevational view of an exemplary embodiment
of a brake assembly;
[0069] FIG. 22B is an exploded perspective view of a brake shoe,
actuator, and release assembly and a mounting plate;
[0070] FIG. 22C is an enlarged perspective view of the brake shoe,
actuator, and release assembly shown in FIG. 22B;
[0071] FIG. 22D is a first exploded perspective view of the brake
shoe, actuator, and release assembly shown in FIG. 22C;
[0072] FIG. 22E is a second exploded perspective view of the brake
shoe, actuator, and release assembly shown in FIG. 22C;
[0073] FIG. 23A is a perspective view of an exemplary embodiment of
a brake shoe assembly;
[0074] FIG. 23B is a front view of the brake shoe assembly shown in
FIG. 23A;
[0075] FIG. 23C is a side view of the brake shoe assembly shown in
FIG. 23A;
[0076] FIG. 23D is a front view of an exemplary embodiment of a
brake shoe;
[0077] FIG. 23E is a front view of an exemplary embodiment of a
brake shoe and pad assembly;
[0078] FIG. 23F is a perspective view of an exemplary embodiment of
a brake shoe;
[0079] FIG. 23G is a perspective view of an exemplary embodiment of
a brake shoe and pad assembly;
[0080] FIG. 24A is an elevational view of a brake assembly in a
released condition;
[0081] FIG. 24B is an enlarged portion of FIG. 24A, as indicated in
FIG. 24A;
[0082] FIG. 24C is an elevational view of a brake shoe and a
centering pin;
[0083] FIG. 25A is a view similar to the view of FIG. 24A showing
the brake shoes in a position where the brake pads are engaged with
the rotor housing assembly;
[0084] FIG. 25B is an enlarged portion of FIG. 25A, as indicated in
FIG. 25A;
[0085] FIG. 26A is a perspective view of an exemplary embodiment of
an actuator in an extended position;
[0086] FIG. 26B is an elevational view of the actuator shown in
FIG. 26A;
[0087] FIG. 26C is a sectional view taken along the plane indicated
by lines 26C-26C in FIG. 26A;
[0088] FIG. 26D is an enlarged sectional view of shaft members of
the actuator in the extended position;
[0089] FIG. 27A is an elevational view of the actuator shown in
FIG. 26A in a retracted position;
[0090] FIG. 27B is a sectional view of the actuator shown in FIG.
27A;
[0091] FIG. 27C is an enlarged sectional view of the shaft members
of the actuator in the retracted position;
[0092] FIG. 27D is an enlarged sectional view of an exemplary
embodiment of shaft members of an actuator in a retracted
position;
[0093] FIG. 27E is an enlarged sectional view of the shaft members
shown in FIG. 27D in an extended position;
[0094] FIG. 28 is an elevational view of an exemplary embodiment of
a brake assembly in a position where the brakes are released by an
actuator;
[0095] FIGS. 28A and 28B are elevational views of the brake
assembly shown in FIG. 28 with a brake release mechanism in two
different positions that allow normal operation of the brakes;
[0096] FIG. 29 is an elevational view of an exemplary embodiment of
a brake assembly in a position where the brakes are applied by an
actuator;
[0097] FIGS. 29A and 29B are elevational views of the brake
assembly shown in FIG. 19 with a brake release mechanism in two
different positions that allow normal operation of the brakes;
[0098] FIG. 30 is an elevational view of an exemplary embodiment of
a brake assembly in a position where the brakes are released by a
manual brake release mechanism;
[0099] FIG. 31A is a plan view an exemplary embodiment of a drive
member of a manual brake release mechanism; and
[0100] FIG. 31B is a perspective view of the drive member
illustrated by FIG. 31.
DETAILED DESCRIPTION
[0101] As described herein, when one or more components are
described as being connected, joined, affixed, coupled, attached,
or otherwise interconnected, such interconnection may be direct as
between the components or may be indirect such as through the use
of one or more intermediary components. Also as described herein,
reference to a "member," "component," or "portion" shall not be
limited to a single structural member, component, or element but
can include an assembly of components, members or elements.
[0102] Referring to FIG. 1, a conveyance such as a wheelchair 100
is illustrated. The wheelchair 100 includes a seat assembly 102 and
a chassis 112. The chassis 112 includes drive wheels 114 and 116
connected thereto for propulsion of wheelchair 100. Drive wheels
114 and 116 may be driven by a plurality of types of drive
assemblies 200 including, for example, electric motor and gear
combinations or gearless brushless motors such as wheel hub motors.
Casters 118 and 120 are connected to the chassis 112 for providing
forward support of wheelchair 100. One or more rear anti-tip wheels
may also be included. A footplate 122 is connected to the front
portion of chassis 112 to support the feet of a user. A joystick
124 is provided to allow a user to control the drive system of
wheelchair 100.
[0103] Referring to FIG. 1B, in one exemplary embodiment, the drive
assemblies 200 are hub motors with internal brakes. The hub motors
with internal brakes include a mounting member 202, a stator
winding assembly 206, a rotor magnet assembly 208, a brake assembly
210, and a hub 204 or rotor housing. The stator winding assembly
206 is mounted to the mounting member 202. The brake assembly is
operably connected to the mounting member 202. The hub 204 is
rotatably coupled to the mounting member 202. The hub 204 includes
a radially outer wall 170. The rotor magnet assembly 208 is mounted
to an inside 172 of the radially outer wall 170 of the hub 204. The
brake assembly 206 is operable to move a component 174 of the brake
assembly between an engaged position (FIG. 1C) where the component
174 engages the inside 172 of the radially outer hub wall and a
disengaged position (FIG. 1B) where the component is spaced apart
from the inside 172 of the radially outer hub wall.
[0104] The inside 172 of the radially outer hub wall 170 may be an
inner surface 176 of the radially outer wall 170 itself (FIGS. 1B
and 1C) or the inside 172 may be a lining 178 (FIGS. 1D and 1E),
coating, etc. on or attached to the inner surface 176 of the
radially outer wall 170. In other embodiments, the component 174
may engage another portion of the hub 204 when the brake assembly
206 is engaged.
[0105] The mounting member 202 may take a wide variety of different
forms. In one exemplary embodiment, the mounting member 202 is a
circular plate that includes a central post 241 that is rotatably
mounted to the hub 204 and a circular (or other shape) plate 240.
In the example illustrated by FIG. 1B, the stator winding assembly
206 is mounted to one side of the plate and the brake assembly 210
is operably connected on the other side of the plate, such that the
plate substantially isolates the stator winding assembly from the
brake assembly. However, in another exemplary embodiment, the
stator winding assembly 206 and the brake assembly are both be
disposed on the same side of the plate 240
[0106] In an exemplary embodiment, an actuator 2604 is coupled to
the brake assembly 210 for moving the brake assembly between the
engaged position and the disengaged position. The actuator 2604 can
take a wide variety of different forms. The actuator may be a
mechanical, manual, electrical, pneumatic, hydraulic, or hybrid
actuator. In one exemplary embodiment, the actuator 2604 is an
electromagnetic actuator.
[0107] Referring to FIGS. 1F and 1G, in one exemplary embodiment,
both a service actuator 2604 and a release actuator 1000 are
included. The service actuator 2604 is coupled to the brake
assembly 210 for normal operation of the brakes (i.e. the service
actuator moves the component 174 of the brake assembly between the
engaged position and the disengaged position). In an exemplary
embodiment, the release actuator 1000 is moveable or changeable
between a release position or condition and a normal operation
position or condition. When the release actuator 1000 is in the
release position or condition, the release actuator 1000 moves the
component 174 of the brake assembly to away from the inside 172 of
the radially outer hub wall 170 as indicated by arrow 182 and
prevents the component 174 of the brake assembly 210 from moving to
the engaged position. When the release actuator 1000 is in the
normal operating position or condition, the service actuator 2604
is able to move the component 174 from the disengaged position to
the engaged position.
[0108] The release actuator 1000 can take a wide variety of
different forms. The actuator may be a mechanical, manual,
electrical, pneumatic, hydraulic, or hybrid actuator. In the
examples that follow in this application, the release actuator 1000
is a manual mechanism that engages the brake shoes to move the
brakes to the released position and maintain the brakes in the
released position. However, the release actuator may be powered and
may be coupled to the brake assembly in any manner. For example,
the release actuator 1000 may comprise a switch or other input
device that controls a powered actuator, such as an electrical,
pneumatic, or hydraulic actuator, to move the brakes to the
released position and maintain the brakes in the released
position.
[0109] FIGS. 2A-2E, 3A and 3B illustrate one exemplary embodiment
of a drive assembly 200 that is a hub motor with internal brakes.
Referring to FIGS. 3A and 3B, the illustrated drive assembly
includes a mounting plate 202, a rotor housing assembly 204, a
stator armature assembly 206, a rotor magnet ring assembly 208, and
a brake assembly 210. Referring to FIGS. 7B and 7C, in one
exemplary embodiment, the rotor housing assembly 204 is rotatably
connected to the mounting plate 202, with the stator armature
assembly 206 fixed with respect to the mounting plate and the rotor
magnet ring assembly 208 fixed with respect to the rotor housing
assembly 204. As such, when the stator armature assembly 206 is
energized, the rotor magnet ring assembly 208 and attached rotor
housing assembly 204 is driven to rotate around the stator armature
assembly 206 and mounting plate 202. As will be explained in more
detail below, when disengaged (See FIG. 13), the brake assembly 210
allows rotation of the rotor housing assembly 204 around the
mounting plate 202. When engaged (See FIG. 14), the brake assembly
210 resists rotation of the rotor housing assembly 204 around the
mounting plate 202.
[0110] Referring to FIGS. 4A and 4B, in one exemplary embodiment,
the drive assembly 200 includes drive circuitry 230 that is
optionally mounted inside the rotor housing assembly 204. In other
embodiments, the drive circuitry 230 may be remote from the drive
assembly 200, or is disposed in a housing of the drive assembly
that is outside the rotor housing assembly 204. The drive circuitry
230 can take a wide variety of different forms. For example, the
drive circuitry 230 can comprise any circuit that controls the
power applied to the stator armature assembly 206 and/or the brake
assembly 210.
[0111] The mounting plate 202 can take a wide variety of different
forms. The mounting plate 202 is illustrated as a single component,
but it (and other components described in this application) can be
multiple components that are fixed together or otherwise coupled.
In the illustrated embodiment, the mounting plate 202 is configured
to support or mount the stator armature assembly 206 and the brake
assembly 210. Referring to FIGS. 5A-5D, the illustrated mounting
plate 202 includes a wall portion 240, a central post 241 having a
stator side portion 242 and a brake side portion 244, and a stator
support wall 245. The central wall portion 240 includes a stator
side 246. Referring to FIGS. 7A and 7B, the stator armature
assembly 206 is mounted upon the stator side 246 around the stator
support wall 245. Referring to FIG. 5B, the stator side portion 242
of the central post and the stator support wall 245 form an annular
space 248. Referring to FIGS. 4A and 4B, in the illustrated
embodiment, the drive circuitry 230 is mounted to the stator side
246 of the central wall portion 240 in the annular space. The drive
circuitry 230 may be mounted on an annular circuit board that
includes a central opening that fits around the stator side portion
of the central post 241. However, the drive circuitry may have any
physical configuration. In one exemplary embodiment, the mounting
plate 202 is optionally made from a thermally conductive material,
such as aluminum, and is used as a heat sink for one or more of the
components of the drive circuitry 230.
[0112] Referring to FIGS. 3A, 3B and 6C, the illustrated central
post 241 is generally cylindrical to allow the mounting plate 202
to be rotatably coupled to the rotor housing assembly 204 by first
and second bearings 250, 252. The central post 241 includes an
opening 254 that accepts a fastener 255 for mounting the drive
assembly to a frame 150 of the chassis 112 (FIGS. 1 and 1A).
Referring to FIG. 2B, the opening 254 may include a counterbore 260
and a head 262 of the fastener does not extend axially past an
outer side wall 264 of the rotor housing assembly 204. A cap may be
placed over the fastener 255 in the counterbore 260 to conceal the
fastener. In the illustrated embodiment, the opening 254 is
centered in the post 241, but may be offset from a central axis X
of the post in other embodiments.
[0113] Referring to FIG. 2A, the illustrated post 241 also includes
one or more alignment features 256 that mate with corresponding
features included on the frame 150 (FIG. 1) to set the rotational
position of the mounting plate 202 (and attached components)
relative to the frame 150. The alignment features 256 and
corresponding alignment features of the frame may take a wide
variety of different forms. For example, the alignment features 256
may be projections and/or recesses that mate with respective
recesses and/or projections to set the position of the base member
202. In the illustrated embodiment, the alignment features 256
comprise counterbores that mate with projections, such as pins,
included on the frame 150. The alignment features 256 facilitate
quick alignment and connection of each drive assembly to the frame
150 with a single fastener 255. The fastener may take a wide
variety of different forms and any conventional fastener can be
used. In one embodiment, a single threaded fastener or a quick
release fastener is used and the entire drive assembly can be
quickly mounted to the frame 150 or removed from the frame with the
single threaded fastener or the single quick release fastener.
[0114] Referring to FIG. 2A, in one exemplary embodiment, the
central post 241 includes a wireway 270. The wireway 270 can take a
wide variety of different forms. The illustrated wireway 270 is a
slot that extends from the drive circuitry 230 to the end 272 of
the central post 241 that is outside the rotor housing assembly
204. Wires or other types of communication lines that couple the
drive circuitry 230 to a joystick (or other type of user interface)
and/or other control circuitry are routed through the wireway 270.
A protective sheath may be disposed over the wires in the wireway
270. The wireway 270 and the protective sheath may be complimentary
in shape, such that the protective sheath can simply slide over the
wires and snap into the wireway 270. In an exemplary embodiment,
the wireway 270 is positioned to be at the top dead-center (or
bottom dead-center) when the drive assembly is mounted to the
wheelchair 100 (or other vehicle). This positioning places the
wires at the same location on each side of the wheelchair 100 (or
other vehicle). As such, the same drive assembly can easily be used
on either side of the wheelchair 100 (or other vehicle).
[0115] Referring to FIG. 2D, in one exemplary embodiment, the
central post 241 includes one or more brake control passages 280.
The brake control passages 280 can take a wide variety of different
forms. For example, the brake control passage 280 may be any
opening, channel, bore, etc. that provides access to the brake
assembly 210 from the end 272 of the central post 241. The
illustrated brake control passage 280 comprises a pair of generally
rectangular slots that extend from the brake assembly 210 to the
end 272 of the central post 241. As will be described in more
detail below, components of a manual brake disengagement mechanism
1000 (or other type of user interface) extend through the brake
control passage 280.
[0116] The rotor housing assembly 204 can take a wide variety of
different forms. For example, any arrangement that can be rotatably
mounted around the mounting plate 202 and that can support a tire
160 (FIGS. 1 and 1A) can be used. In the embodiment illustrated by
FIGS. 6A-6D, the rotor housing assembly 204 has a clam-shell
configuration that includes an outer cover 302 and an inner cover
304. The illustrated outer cover 302 includes a disk shaped end
face 306, a radially outer wall 308, and a radially inner bearing
wall 310. Referring to FIGS. 6B-6D, the outer cover 302 fits over
the stator armature assembly 206 (removed in FIG. 6D to simplify
the drawing) and mounting plate 202 and is rotatably connected to
the stator side portion 242 of the central post by the bearing 250
(FIG. 6D). The bearing 250 may be coupled to the outer cover 302
and to the stator side portion 242 of the central post 241 in a
wide variety of different ways. For example, in the illustrated
embodiment, the bearing 250 may be press fit into the radially
inner wall 310 against a bearing support flange 312 (FIG. 6D) that
extends radially inward from the radially inner wall 310, past an
annular groove 314 that extends radially outward from the radially
inner wall 310. A snap ring 316 snaps into the annular groove 314
to secure the bearing 350 to the outer cover 302. The bearing 250
may also be press fit around the stator side portion 242 of the
post 241 against a bearing support flange 322 (FIG. 6D) of the post
241. However, any manner of coupling the outer cover 302 and to the
stator side portion 242 of the central post 241 may be employed. In
the illustrated embodiment, a rim 309 is connected to the outer
cover 302 by a plurality of fasteners. However, the rim 309 may be
integrally formed with the outer cover 302.
[0117] Referring to FIGS. 6A-6D, the illustrated inner cover 304
includes a disk shaped end face 336, a radially outer wall 338, a
rim 339 extending radially outward from the wall, and a radially
inner bearing wall 340. The rim 339, like the other components
described in this application, may be made from a single piece, or
multiple pieces. The inner cover 304 fits over the brake assembly
210 and mounting plate 202 and is rotatably coupled to the brake
side portion 244 of the central post 241 by the bearing 252 (FIG.
6D). The bearing 252 may be coupled to the inner cover 304 and to
the brake side portion 244 of the central post 241 in a wide
variety of different ways. In the illustrated embodiment, the
bearing 252 is press fit into the radially inner wall 340 against a
bearing support flange 342 (FIG. 6D) that extends radially inward
from the radially inner wall 340. The bearing 250 may also be press
fit around the brake side portion 244 of the post 241 against a
bearing support flange 352 of the post 241 (FIG. 6D). However, any
manner of coupling the inner cover 304 and to the brake side
portion 244 of the central post 241 may be employed.
[0118] Referring to FIG. 6D, a small gap 380 is provided between
the outer circumference of the mounting plate 202 and the rotor
housing assembly 204, such that the rotor housing assembly 204 can
freely rotate around the mounting plate 202.
[0119] In an exemplary embodiment, the outer cover 302 is secured
to the and the inner cover 304 to complete the rotor housing
assembly 204. This connection may be achieved in a wide variety of
different ways. In the illustrated embodiment, the outer cover 302
is secured to the inner cover 304 by a plurality of fasteners.
However, any manner of connection may be used. In the illustrated
embodiment, an annular recess 360 is defined between the two rims
309, 339. In an exemplary embodiment, a tire 160 (FIGS. 1 and 1A)
is mounted in the recess 360 between the two rims 309, 339 in a
known manner. One or both of the rims 309, 339 may be integrally
formed with the outer cover 302 and/or the inner cover 304 or one
or both of the rims may be separately attached to and removable
from the outer cover 302 and/or the inner cover 304. By removably
attaching one of the rims 309, 339 to the inner cover 304 and/or
the outer cover 302, a solid tire can easily be changed, without
requiring significant disassembly of the drive assembly 200.
[0120] The stator armature assembly 206 may take a wide variety of
different forms. Any conventional stator armature assembly may be
used. In the embodiment illustrated by FIG. 7A, the stator armature
assembly 206 includes a core 400 and a plurality of windings 402.
The illustrated core 400 comprises a plurality of annular plates
404 that are stacked. The plates each include an annular central
opening 406 and a plurality of radially outwardly extending legs
408. Mounting tabs 410 extend radially inward from the opening 406.
The stacked legs 408 form winding posts. The windings 402 are wound
around the posts. Insulators may be provided around the adjacent
wires of each pair of adjacent windings to insulate the windings
from the core 400. The illustrated stator armature assembly 206 is
fixed to the base member 202 around the stator support wall 245. In
the embodiment illustrated by FIG. 7A, the mounting tabs 410 are
secured in recesses 412 in the outer surface of the outer wall 245.
Referring to FIGS. 4A and 4B, the windings 402 of the stator
armature assembly 206 are electrically connected to and are
selectively powered by the drive electronics 230.
[0121] The rotor magnet ring assembly 208 may take a wide variety
of different forms. Any conventional rotor configuration may be
employed. In the embodiment illustrated by FIG. 7A, the rotor
magnet ring assembly 208 includes an annular support ring 450 and a
plurality of permanent magnets 452 attached to an inner wall of the
support ring. The illustrated rotor magnet ring assembly 208 is
fixed to the rotor housing assembly 204 around the stator armature
assembly 206.
[0122] The brake assembly 210 can take a wide variety of different
forms. For example, the brake assembly 210 may be a drum brake
assembly, a disc brake assembly, a strap brake assembly, a cam
brake assembly, etc. Any arrangement capable of arresting relative
rotation between the mounting plate 202 and the rotor housing
assembly 204 can be used. In the embodiment illustrated by FIGS.
8A-8D, the brake assembly 210 has a drum brake configuration and is
positioned on a brake side 247 of the central portion 240 of the
base member 202.
[0123] The illustrated brake assembly 210 includes a pair of brake
shoes 600, a pair of brake pads 602, and a brake actuator 604. The
brake actuator 604 selectively moves the brake shoes 600 and
associated pads into (FIG. 14) and out of (FIG. 13) engagement with
an inner surface 608 of the rotor housing assembly 204 (or
alternatively with a lining secured to the inner surface of the
rotor housing assembly).
[0124] The brake shoes 600 can take a wide variety of different
forms. Any brake shoe configuration capable of pressing brake pads
into contact with the surface 608 can be used. In the illustrated
embodiment, the brake shoes 600 are mirror images of one another.
As such, only one brake shoe 600 will be described in detail.
Referring to FIGS. 9A-9C, each brake shoe 600 has an outer pad
mounting surface 620, a plurality of glides 622, and an actuator
mounting portion 624 that extends radially inward from the pad
mounting surface 620. The outer pad mounting surface 620 is
generally the shape of a cylindrical segment and is positioned to
be parallel to the cylindrical inner surface 608 of the rotor
housing assembly 204 when the brakes are disengaged (FIG. 13). In
the illustrated embodiment, the pad mounting surfaces 624 extend
along a substantial portion of the cylindrical inner surface of the
rotor housing assembly 204. For example, an angle .theta. between
ends 630, 632 of the pad mounting surfaces 624 may be 150.degree.
or more (See FIG. 9B).
[0125] The actuator mounting portion 624 includes an actuator
mounting aperture 650 and a link mounting aperture 652. A pin
clamping surface 654 is defined at an end of the actuator mounting
portion 624. The pin clamping surface 654 is shaped to engage a pin
656 that is attached to the mounting plate. The pin clamping
surface 654 and the pin 656 may take a wide variety of different
forms. In one embodiment, the pin clamping surface is round and
mates with a round pin that is fixed to the plate. When the brakes
are disengaged in this embodiment, the brake shoes could possibly
swing about the pin as indicated by arrows 658 (in FIG. 8A the
round pin is not shown). For example, this swinging might occur as
the vehicle travels up or down a hill or accelerates/decelerates.
This swinging from a circular pin could potentially cause some
dragging of the brakes.
[0126] Referring to FIG. 10A, in one exemplary embodiment, the pin
clamping surface 654 and the pin 656 are shaped to allow each brake
shoe 600 that is pressed against the pin to rotate somewhat in the
direction indicated by arrow 690 when the brakes are engaged and to
prevent rotation of each engaged shoe 600 (one when brakes
actuated, two when brakes disengaged) in the direction indicated by
arrow 692. This can be accomplished in a variety of different ways.
In the illustrated embodiment, the pin 656 includes a rounded
surface 693, a pair of flat surfaces 694 that extend from the
rounded surface, and a pair of flat surfaces 695, that extend from
the flat surfaces 694 at first and second corners 696, 697 and meet
at a third corner 698. This configuration may resemble the shape of
a hex-nut with one side rounded off. However, other shapes may be
adopted. The illustrated clamping surface 654 includes a curved
surface 683 that overlies the rounded surface 693, a flat surface
684 that engages flat surface 694, a flat surface 685 that engages
flat surface 695, and a relief 686 at the intersection of the flat
surfaces 684, 685. The illustrated reliefs 686 are below the
corners 696, 697 in the orientation illustrated by FIG. 10A.
However, the reliefs 686 can be configured in a wide variety of
different ways.
[0127] If a moment is applied to either of the brake shoes 600 in
the direction indicated by arrows 692 in FIG. 10A while the surface
654 of the shoes are pressed against the pin 656, rotation of the
shoe(s) in the direction indicated by arrow 692 is prevented by
engagement between flat surfaces 684/694 and the engagement between
flat surfaces 685/695. As such, when both clamping surfaces 654 are
pressed against the pin 656, the shoes 600 cannot swing or rotate
about the pin 656, because the pressing of the surface 654 of one
shoe against the pin 656 prevents swinging of the assembly in one
direction and the pressing of the surface 654 of the other shoe
against the pin prevents swinging of the assembly in the other
direction. As such, when both shoes are pressed against the pin,
neither shoe can swing about the pin.
[0128] Referring to FIG. 10B, when the brakes are engaged (See FIG.
14), the shoe shown on the left in FIG. 10B moves away from the pin
656. This allows the shoe 600 shown on the right to pivot about the
pin in the direction indicated by arrow 690. The curved surface 683
slides along the rounded surface 693. The relief 686 allows the
pivoting, without binding against the corner 697 of the pin 656. In
this manner, the pin 656 and engagement surfaces 654 allow some
pivoting of the shoe engaged with the pin during brake actuation,
but prevents swinging of the brake shoes 600 about the pin 656 when
the brakes are disengaged.
[0129] There may be situations where resisting pivoting of the
shoes that is engaged with the pin during brake actuation is
desirable. In these situations, it may be beneficial to have the
pin clamping surface 654 shaped to mate more precisely with a
complimentary shaped pin 656. For example, a hexagonally shaped pin
and a clamping surface that has three surfaces that engage three
sides of the hexagonally shaped pin may be used. However, any shape
(square, triangular, star shaped, etc) may be selected for the pin
656. Any arrangement that limits rotation of the shoes with respect
to the pin 656 when the brakes are disengaged can be used.
[0130] By preventing the brake shoes 602 from rotating with respect
to the pin 654 when the brakes are disengaged, the brakes are
prevented from dragging when the vehicle travels up or down a hill
and/or when the vehicle accelerates or decelerates. That is, the
brake shoes 602 are prevented from swinging about the pin 654 such
that one of the brake pads contacts the rotor housing assembly 204
when the vehicle travels up or down a hill and/or when the vehicle
accelerates or decelerates.
[0131] The brake pads 602 may take a wide variety of different
forms and the pads can be made from a variety of different types of
materials. The brake pads may be made from relatively soft
materials, such as rubber, rubber compounds, cork, mixtures of
rubber and cork, and/or harder materials, such as metals, graphite,
ceramics, etc. The pads 602 may be molded on to the brake shoes or
connected to the brake shoes in a conventional manner. Any brake
pad configuration that can engage and slow rotation of the rotor
housing assembly 204 can be used. In the illustrated embodiment,
the brake pads 602 are mirror images of one another. However, in
other embodiments, the brake pads 602 may have different sizes and
shapes. Each brake pad 602 is mounted to the pad mounting surface
620 of a brake shoe. The brake pad 602 has the shape of a
cylindrical segment. In the embodiment illustrated by FIGS. 9A-9C,
the brake pads 602 extend along a substantial portion of the
cylindrical inner surface of the rotor housing assembly 204. For
example, an angle 13 between ends 680, 682 of the pads 602 may be
150.degree. or more (See FIG. 9B).
[0132] The brake actuator 604 can take a wide variety of different
forms. The brake actuator 604 can be electrically powered,
pneumatically powered, hydraulically powered, etc. The brake
actuator 604 can be a linear actuator, rotary actuator, etc. The
brake actuator 604 can be any mechanism capable of moving brake
pads into and out of contact with a moving surface. Referring to
FIG. 11, the illustrated brake actuator 604 comprises an
electrically powered linear actuator 700 and a spring 702. A wide
variety of different electrically powered linear actuators can be
used. The illustrated electrically powered linear actuator 700
includes a body 703 that accepts a shaft 704. A mounting member 706
is fixed to the body 703 at the end that is opposite the shaft 704.
The mounting member 706 is illustrated as being adjustable in
length, but may be a member having a fixed length. The mounting
member 706 has a slot 708 at its end and has a bore 710 that
intersects the slot 708. Referring to FIG. 8A, the slot 708 is
placed over the actuator mounting portion 624 and a fastener is
placed through the bore 710 of the mounting member 706 and through
the actuator mounting aperture 650 to connect one end of the
actuator 700 to one of the shoes 600.
[0133] The shaft 704 has a slot 718 at its end and has a bore 720
that intersects the slot 718. Referring to FIG. 8A, the slot 718 is
placed over the actuator mounting portion 624 and a fastener is
placed through the bore 720 of the shaft 704 and through the
actuator mounting aperture 650 to connect the other end of the
actuator 700 to the other shoe 600.
[0134] The spring 702 can take a wide variety of different forms.
Any spring capable of biasing the brakes to an engaged position or
to a released position can be used. In the illustrated embodiment,
the spring 702 is a compression spring that is disposed around the
shaft 704 and acts against the actuator body 703. The illustrated
shaft 704 has an annular groove 730 that accepts a snap ring 732 or
another fastening arrangement can be used. The spring 702 is
captured between the body 703 and the snap ring 732. As such, the
spring 702 biases the shaft 704 as indicated by arrow 734 to a
normally extended position. Referring to FIG. 14, the spring 702
biases the brakes into a normally engaged position. Referring to
FIG. 13, when the actuator 700 is energized, the shaft 704 is
pulled into the body 703 against the biasing force of the spring
702 to move the brakes to a released position.
[0135] In the illustrated embodiment, the brake assembly 210 also
includes a brake link 750 (See FIG. 12). The brake link 750 is
illustrated as being adjustable in length, but may be a member
having a fixed length. The brake link 750 has slots 758 at its ends
and has bore 760 that intersect the slots 758. Referring to FIG.
8A, the slots 758 are placed over the actuator mounting portion 624
and fasteners are placed through the bores 760 and through the
brake link mounting aperture 652 to connect the ends of the brake
link to the shoes 600.
[0136] The brake shoe glides 622 can take a wide variety of
different forms. Referring to FIG. 8B, the glides 622 are
configured to allow the brake shoes 600 to smoothly move back and
forth between the engaged and released positions. In the
illustrated embodiment, the glides comprise cylindrical bosses with
flat engagement surfaces 770. The glides 622 slide against the
brake side 247 of the central wall portion 240 of the mounting
plate 202. The glides 622 and/or the central wall portion 240 of
the mounting plate 202 can be configured to reduce friction between
the glides 622 and the mounting plate 202. This reduction in
friction can be accomplished in a wide variety of different ways.
For example, the glides 622 can be made from a low-friction
material, such as nylon, Teflon, silicone, etc., surfaces or
portions of surfaces of the glides 622 and/or the brake side 247 of
the central wall portion 240 of the mounting plate 202 can be
coated with a low friction material, such as nylon, Teflon,
silicone, etc. and/or an anti-friction grease can be applied
between the contacting surfaces.
[0137] In one exemplary embodiment, the brake assembly 210 includes
a retaining mechanism 800 (See FIG. 8B) that prevents the brake
shoes 600 from moving too far axially away from the wall portion
240 of the mounting plate 202. For example, the retaining mechanism
800 prevents the brake shoes 600 from moving away from the wall
portion 240 into contact with the rotor housing assembly 204. In
one embodiment, the retaining mechanism 800 keeps the glides 622
near the wall portion 240 of the mounting plate 202 or in contact
with the wall portion 240 of the mounting plate 202. The retaining
mechanism 800 can take a wide variety of different forms. For
example, the retaining mechanism may comprise one or more springs
that bias the brake shoes 600 toward the wall portion 240 of the
mounting plate 202, one or more stops that limit the movement of
the brake shoes 600 away from the wall portion 240, etc. Any
mechanism that prevents the brake shoes 600 from moving axially
outward and into contact with the rotor housing assembly 204 or a
component that rotates with the rotor housing assembly may be used.
In the illustrated embodiment, the retaining mechanism 800
comprises washers that are connected in a spaced apart relationship
to the wall portion 240 by a brake release mechanism 1000
(described in detail below). The brake shoes 600 are positioned
between the wall portion 240 and the washers to limit the axial
movement of the brake shoes 600 away from the wall portion 240. A
clearance may be provided between the brake shoes 600 and the
washers of the retaining mechanism 800, such that the brake shoes
and glides float between the washers and the brake side 247 of the
mounting plate 202.
[0138] FIGS. 13 and 14 illustrate normal operation of the brake
assembly 210. That is, FIGS. 13 and 14 illustrate operation of the
brake assembly 210 by the actuator 700. FIG. 13 illustrates the
brake assembly 210 in a released or disengaged condition. For
example, when a user of the wheelchair 100 presses on the joystick
124, the actuator 700 is energized and the shaft 704 is retracted
against the biasing force of the spring 702. The actuator 700 pulls
the brake pads together as indicated by arrows 703 in FIG. 13 and
the pin clamping surfaces 654 are brought into engagement with the
pin 656. When the pin clamping surfaces 654 engage the pin 656, the
brake pads 602 are spaced apart from the inner wall (or brake
lining) 608 of the rotor housing assembly 204. When the brake
assembly 210 is in the disengaged position shown in FIG. 13, the
wheelchair begins to move in the direction selected by operating
the joystick 124 (FIG. 1). In the example illustrated by FIGS. 13
and 14, arrow 820 represents the direction of movement of the
wheelchair 100 and arrow 822 represents the corresponding direction
of rotation of the rotor housing assembly 204 around the mounting
plate 202 for movement in this direction.
[0139] FIG. 14 illustrates the brake assembly 210 in an engaged
position. For example, when the user of the wheelchair 100 releases
the joystick 124 (FIG. 1), the actuator 700 is de-energized and the
shaft 704 is extended by the biasing force of the spring 702. In
some embodiments, this de-energizing is delayed. For example, the
de-energizing may be delayed when the motor is operated to provide
regenerative braking until the wheelchair slows to a predetermined
speed or stops. The brake assembly 210 can be used in applications
where regenerative braking is performed and applications where
there is no regenerative braking.
[0140] When the actuator is de-energized, the spring 702 pushes the
brake pads apart as indicated by arrows 705 in FIG. 14 and into
contact with the rotor housing assembly 204. When the rotor housing
assembly 204 is rotating in the direction indicated by arrow 822,
the clamping surface 654 of the brake shoe shown on the right in
FIG. 14 substantially remains in engagement with the pin 656. The
brake shoe 600 shown on the left in FIG. 14 rotates about the
connection to the brake link 750 and the pad 602 is brought into
contact with the rotor housing assembly 204. As a result of the
engagement with the pin 656 by the brake shoe 600 shown on the
right and the pivoting of the brake shoe shown on the left, primary
braking occurs in the area labeled with the reference number 830
and secondary braking occurs in the area labeled with the reference
number 832 (the actual braking areas may be more or less, depending
on the brake force applied, the amount of wear of the pad,
tolerances, etc). When the wheelchair 100 is stopped, the brake
assembly 210 remains engaged until the actuator 700 is energized
again or the brakes are disengaged by a manual brake disengagement
mechanism 1000 (described in detail below).
[0141] One feature of the exemplary brake assembly shown in FIGS.
13 and 14 is that the brake shoes 600 and brake pads 602 are mirror
images of one another and the brake pads 602 are sized such that
the drive assembly 200 can be used on either side of the wheelchair
100 (or other vehicle), without changing the performance of the
brakes. This ambidextrous nature of the brake assembly 210 is
achieved by the use of brake pads 602 that are large enough to
engage at the primary braking region 830 and the secondary braking
region 832, regardless of which side of the vehicle the brakes are
positioned on (i.e. regardless of the direction of rotation of the
rotor housing assembly 204). As was described above, the brake pads
602 may be sized to have a 150.degree. sweep angle .beta. or more.
However, a significantly smaller sweep angle .beta. may be
selected, while still engaging at the primary braking region 830
and the secondary braking region 832, regardless of which side of
the vehicle the brakes are positioned on. For example, the sweep
angle .beta. may be as small as 60.degree. while still retaining
the ambidextrous nature of the brakes. Other pad configurations,
with smaller sweep angles .beta. (such as 45.degree. or less) can
be employed, but the brake assembly would be "handed" (i.e.
different brake assemblies would be used on the opposite sides of
the vehicle).
[0142] Another feature that contributes to the ambidextrous nature
of the brake assembly is that the action of the brake shoes (i.e.
one brake shoe 600 engages the pin 656, while the other brake shoe
pivots) automatically reverses, simply by placing the drive
assembly on the opposite side of the vehicle. No adjustment to the
brake assembly 210 is required to used the drive assembly on either
side of the vehicle.
[0143] Referring to FIG. 13, as was alluded to above, the drive
assembly 200 may include a brake release assembly 1000. The brake
release assembly 1000 disclosed herein may be used on a wide
variety of different types of vehicles. Also, the brake release
assembly 1000 may be used with a wide variety of different types of
braking systems and motors and is not limited in application to the
braking system and/or motor configurations disclosed in this
application. Similarly, the braking mechanisms disclosed by this
application may be used with a variety of different types and
configurations of motors and do not necessarily require a brake
release assembly. Further, the motor configurations disclosed by
this application can be used with a wide variety of different types
and configurations of brake assemblies or some applications may not
require the inclusion of a brake assembly.
[0144] When the drive assembly 200 is used on a powered wheelchair
100 (FIG. 1), it may be advantageous to include a brake release
assembly 1000. For example, should a person wish to manually push
the wheelchair 100 having a brake system as described above,
normally engaged brakes need to be released before the person could
push the wheelchair. While provisions can be made to release the
brakes electrically (i.e. by providing a switch that energizes the
actuator 700), a manual brake override is preferred, since it is
operable even though power may not be available to the actuator
700.
[0145] The manual brake release mechanism 1000 can take a wide
variety of different forms. Any configuration that allows the brake
assembly 210 to be manually disengaged can be implemented. In the
example illustrated by FIGS. 15-15B, the manual brake override
includes a cam driver mechanism 1002, brake shoe cam surfaces 1004,
and a handle 1006 (FIG. 15). The handle 1006 can be operated such
that the cam driver mechanism 1002 engages the brake shoe cam
surfaces 1002 to move the brake shoes 600 to a manual brake release
position (See FIG. 15).
[0146] The cam driver mechanism 1002 and brake shoe cam surfaces
1004 may take a wide variety of different forms. Any arrangement
capable of moving the brake shoes 600 to the released position can
be used. In the embodiment illustrated by FIGS. 15-15B, the cam
drive mechanism 1002 includes a drive member 1010 and a pair of cam
members 1011. Referring to FIG. 16, drive member 1010 may include
an annular central hub portion 1012, a pair of legs 1014 extending
axially from the annular central hub portion 1012, and a pair of
arms 1015 that extend radially outward from the central hub
portion. The illustrated cam members 1011 are rollers that are
rotatably mounted to the arms 1015. However, the cam members 1011
may be fixed to the arms or integrally formed with the arms.
[0147] The brake shoe cam surfaces 1004 can take a wide variety of
different forms. The cam surfaces 1004 may be integrally formed
with the brake shoes 600 or the cam surfaces 1004 may comprise
separate members that are attached to the brake shoes. The cam
surfaces 1004 may comprise any structure capable of being engaged
by the cam mechanism 1002 to move the brakes to a disengaged
position. In the illustrated embodiment, the cam surfaces 1004
comprise slots 1020 formed in the brake shoes. An inner surface of
each slot forms the cam surface 1004. The inner surface includes a
central portion 1024 and two outer portions 1026. The central
portion 1024 is closer to the central axis X of the base member 202
than the outer portions 1026.
[0148] Referring to FIG. 8B, the hub portion 1012 of the drive
member 1010 is rotatably coupled around the central post 241. An
optional bearing may be included to reduce friction between the
drive member 1010 and the central post 241 and/or the wall portion
240. Referring to FIG. 8A, the legs 1014 of the drive member 1010
are disposed in the brake passages 280. The clearance between the
legs 1014 and the passages 280 define the amount of possible
rotation of the drive member 1010 about the central post 241. In
the illustrated embodiment, about 15 degrees of travel is allowed,
but any amount of travel can be defined. The arms 1015 are
positioned between the brake shoes 600 and the wall portion 240 of
the mounting plate 202. The cam members 1011 are disposed in the
slots 1020.
[0149] Referring to FIGS. 2C and 13, the handle 1006 is connected
to the legs 1014 of the drive member 1010. The handle 1006 is
movable between a disengage position (See FIG. 15) and two "allow
engagement" positions (See FIGS. 13A, 13B, 14A, and 14B). In the
disengage position (FIG. 15), the cam members 1011 engage the
central portions 1024 of the slots 1020. The engagement of the cam
members 1011 press against central portions 1024 and pull the brake
pads together, such that the pin clamping surfaces 654 are brought
into engagement with the pin 656. This action compresses the spring
702. When the pin clamping surfaces 654 engage the pin 656, the
brake pads 602 are spaced apart from the inner wall 608 (See FIG.
8A) of the rotor housing assembly 204. When the manual brake
release mechanism 1000 is in the disengage position shown in FIGS.
8A and 15 the brakes are released and the wheelchair may easily be
pushed by a user.
[0150] When the handle 1006 is in one of the two "allow engagement"
positions (FIGS. 13A, 13B, 14A, 14B), the cam members 1011 are
spaced apart from the slots 1020 and the brake assembly 210 is
operated by the actuator 700 as described above. For example, if no
power is applied to the actuator 700, the brakes are engaged (FIGS.
14A 14B) and if power is applied to the actuator, the brakes are
disengaged (FIGS. 13A, 13B). In the illustrated embodiment, in the
allow engagement positions, enough clearance is provided between
the slots 1020 and cam members 1011 to prevent any engagement
between the cam members 1011 and the slots 1020 during operation of
the brake assembly by the actuator 700.
[0151] Referring to FIG. 8A, in one exemplary embodiment, a sensor
1100, such as a micro-switch (any type of sensor may be used) is
positioned to detect whether or not the manual brake release
mechanism 1000 is in the disengaged position (or the "allow
engagement" position). The output of the sensor 1100 may be used
for a variety of different control functions. For example, when the
output of the sensor 1100 indicates that the manual brake override
is in the disengage position, the drive circuitry 230 may prevent
power from being applied to the windings 402 and/or the actuator
700. Referring to FIG. 16, the illustrated central hub portion 1012
of the drive member 1010 includes a cam surface 1300. The
illustrated cam surface 1300 includes a pair of spaced part peaks
1302, 1304 and a valley 1306 between the peaks. Referring to FIGS.
8A and 15, an actuator 1308 of the sensor is disposed in the valley
1306, and is therefore extended. This indicates that the brake
release mechanism 1000 is in the brake release position. Referring
to FIGS. 13A and 13B, when the handle 1006 is in one of the "allow
brake engagement" positions, one of the peaks 1302 (depending on
which "allow disengagement" position the handle is in) depresses
the sensor actuator 1308. This depressed actuator 1308 indicates
that the brakes are in one of the "allow disengagement" positions.
It should be readily apparent that the illustrated sensor 1100 and
cam surface 1300 is but one of the many configurations that may be
used.
[0152] Referring to FIGS. 8A and 17, in one exemplary embodiment, a
detent mechanism 1200 may be included such that the handle 1006
positively stops at the disengagement position and each of the
"allow engagement" positions. Any type of detent mechanism 1200 may
be used. By way of example, the detent mechanism 1200 illustrated
by FIG. 17 comprises a spring loaded pin 1201 that is biased into a
recess 1203. Three recesses 1203 are provided in the illustrated
embodiment that correspond to the brake release position and the
two "allow brake engagement" positions. However, any arrangement
and number of recesses may be used.
[0153] Referring to FIG. 15, the manual brake release mechanism
1000 is constructed such that the handle 1006 is in a top
dead-center position when the brake release mechanism 1000 is in
the disengage position. Further, the brake release mechanism 1000
is configured such that the handle 1006 is moved and/or pivoted the
same distance and/or angle from the disengage position to each of
the "allow engagement" positions (See FIGS. 13A and 13B).
[0154] In another embodiment, the manual brake release mechanism
1000 is configured to have one "allow engagement" position and two
disengage positions. The manual brake release mechanism 1000 may be
constructed to have the handle 1006 in a top dead-center position
when the manual brake release mechanism 1000 is in the "allow
engagement" position. Further, the manual brake release mechanism
1000 may be configured such that the handle 1006 is moved and/or
pivoted the same distance and/or angle from the "allow engagement"
position to each of the disengage positions. For example, the
handle 1006 may be pivoted in opposite directions from the top
dead-center position to reach the disengage positions.
[0155] By configuring the handle 1006 to be positioned at top
dead-center for the manual disengage position (or "allow
engagement" position) and configuring the handle to be moveable in
opposite directions to two equally spaced "allow engagement"
positions (or manual disengage positions), the same drive assembly
200 can be used on either side of the wheelchair 100 (or other
vehicle), while providing the same control positions for the handle
1006 of the manual brake release mechanism 1000. That is,
regardless of the side of the wheelchair 100 (or other vehicle)
that the drive assembly 200 is mounted on, the control of the
manual brake release mechanism 1000 is the same. In the illustrated
embodiment, the drive assembly on either side of the wheelchair 100
is placed in the manual brake disengage position by positioning the
handle 1006 at the top dead center position and is placed in the
"allow engagement" position by moving the handle forward (and/or
backward). No adjustments to the drive assembly 200 are required.
However, if configuring the manual brake release mechanism 1000 to
have only one manual brake disengagement position and only one
allow engagement is desired, a simple bracket or other blocking
member can be positioned to prevent the handle 1006 (or other
component of the mechanism) from moving in one direction. Still,
the same drive assembly can be used on both sides of the wheelchair
100 (or other vehicle).
[0156] Referring to FIGS. 2F-2H, in one exemplary embodiment a
sealing arrangement 290 is included to reduce the amount of dirt
and/or moisture that can enter the rotor housing 204. The sealing
arrangement 290 may take a wide variety of different forms.
Examples of suitable sealing arrangements include, but are not
limited to, gaskets and sealants. Any arrangement that reduces the
amount of dirt and/or moisture that can enter the rotor housing 204
can be used. In the example illustrated by FIGS. 2F-2H, the sealing
arrangement 290 comprises first and second gaskets 291, 292. The
first gasket 291 fits around the central post 241 and seals against
the bearing 252 and the handle 1006. The second gasket 292 fits
snugly around the central post 241 and seals against the handle
1006. The second gasket includes projections 293 that fit in the
brake control passages 280 and a projection 294 that fits in the
wireway 270. The projection 294 includes an opening 295 to allow
passage of the wires through the gasket 292. The projections 293,
294 inhibit dirt, debris, and water from entering the rotor housing
204.
[0157] FIGS. 18A and 18B illustrate another exemplary embodiment of
drive assemblies 2200 that comprise hub motors with internal
brakes. The drive assembly 2200 includes a mounting plate 2202, a
rotor housing assembly 2204 and magnet ring assembly 2208, a stator
armature assembly 2206, and a brake assembly 2210. In one exemplary
embodiment, the rotor housing assembly 2204 and magnet ring
assembly 2208 are rotatably connected to the mounting plate 2202,
with the stator armature assembly 2206 fixed with respect to the
mounting plate. As such, when the stator armature assembly 2206 is
energized, the rotor magnet ring assembly 2208 and attached rotor
housing assembly 2204 is driven to rotate around the stator
armature assembly 2206 and mounting plate 2202. As will be
explained in more detail below, when disengaged (See FIG. 28), the
brake assembly 2210 allows rotation of the rotor housing assembly
2204 around the mounting plate 2202. When engaged (See FIG. 29),
the brake assembly 2210 resists rotation of the rotor housing
assembly 2204 around the mounting plate 2202.
[0158] The drive assembly 2200 includes drive circuitry 2230 that
is optionally mounted inside the rotor housing assembly 2204 (see
FIG. 19A). In other embodiments, the drive circuitry may be remote
from the drive assembly 2200, or is disposed in a housing of the
drive assembly that is outside the rotor housing assembly 2204.
[0159] The mounting plate 2202 can take a wide variety of different
forms. In FIGS. 20A and 20B, the mounting plate 2202 is illustrated
as a single component, but it can be multiple components that are
fixed together or otherwise coupled. In the illustrated embodiment,
the mounting plate 2202 is configured to support or mount the
stator armature assembly 2206 and the brake assembly 2210.
Referring to FIGS. 20A and 20B, the illustrated mounting plate 2202
includes a wall portion 2240, a central post 2241 having a stator
side portion 2242 and a brake side portion 2244, and a stator
support wall 2245.
[0160] Referring to FIGS. 19A-19C, the stator armature assembly
2206 is mounted upon the wall portion 2240 around the stator
support wall 2245. Referring to FIG. 20B, the stator side portion
2242 of the central post 2241 and the stator support wall 2245 form
an annular space 2248. The drive circuitry 2230 is mounted in the
annular space 2248 (FIGS. 19A and 19B). The mounting plate 2202 is
optionally made from a thermally conductive material, such as
aluminum, and is used as a heat sink for one or more of the
components of the drive circuitry.
[0161] Referring to FIG. 20A, the brake side of the central wall
portion 2240 includes a plurality of glide support protrusions
2247. The glide support protrusions provide support surfaces for
brake shoes to slide against as will be described in more detail
below. The illustrated support surfaces of the protrusions 2247 are
flat and are generally flat and parallel to the central wall
portion 2240. The glide support protrusions 2247 can take a wide
variety of different forms. In the illustrated embodiment, a
plurality of discrete, spaced apart glide support protrusions 2247
are included. In other embodiments, a single protrusion, for
example a single ring shaped protrusion may provide a sliding
support surface or surfaces for the brake shoes.
[0162] Referring to FIGS. 21A and 21B, the illustrated central post
2241 is generally cylindrical to allow the mounting plate 2202 to
be rotatably coupled to the rotor housing assembly 2204 by first
and second bearings 2250, 2252. The central post 2241 includes an
opening 2254 that accepts a fastener for mounting the drive
assembly to a frame in generally the same manner as shown in FIGS.
1 and 1A. In the illustrated embodiment, the opening 2254 is
centered in the post 2241, but may be offset from a central axis X
of the post in other embodiments.
[0163] Referring to FIG. 20A, the illustrated post 2241 also
includes or is adapted to include one or more alignment features
2256 that mate with corresponding features included on the frame
150 (FIG. 1) to set the rotational position of the mounting plate
2202 (and attached components) relative to the frame 150. The
alignment features 2256 and corresponding alignment features of the
frame may take a wide variety of different forms. For example, the
alignment features 2256 may be projections and/or recesses that
mate with respective recesses and/or projections to set the
position of the base member 2202. In the illustrated embodiment,
the alignment features 2256 comprise threaded apertures that accept
fasteners that include heads that mate with recesses or bores
included on the frame 150 (FIG. 1). The alignment features 2256
facilitate quick alignment and connection of each drive assembly
2200 to the frame 150 with a single fastener 255 (FIG. 1).
[0164] Referring to FIG. 20A, in one exemplary embodiment, the
central post 2241 includes a wire way 2270. The wire way 2270 can
take a wide variety of different forms. The illustrated wire way
2270 is a slot that extends from the drive circuitry to an end 2272
of the central post 2241 that is outside the rotor housing assembly
2204 (when assembled). Wires or other types of communication lines
that couple the drive circuitry 2230 to a joystick (or other type
of user interface) and/or other control circuitry are routed
through the wire way 2270. A protective sheath 2271 (FIG. 22A) may
be disposed over the wires in the wire way 2270. The wire way 2270
and the protective sheath may be complimentary in shape, such that
the protective sheath can simply slide over the wires and snap into
the wire way 2270. In an exemplary embodiment, the wire way 2270
and protective sheath 2271 are positioned to be at the top
dead-center (or bottom dead-center) when the drive assembly is
mounted to the wheelchair (or other vehicle). This positioning
places the wires at the same location on each side of the
wheelchair 100 (or other vehicle). As such, the same drive assembly
can easily be used on either side of the wheelchair 100 (or other
vehicle).
[0165] Referring to FIG. 20A, in one exemplary embodiment, the
central post 2241 includes one or more brake control passages 2280.
The illustrated brake control channels 2280 comprise a pair of
generally rectangular slots that extend to the end 2272 of the
central post 2241. Actuation shafts 3014 of a manual brake
disengagement mechanism 3000 (FIG. 22B) extend along the brake
control passage 2280.
[0166] The rotor housing assembly 2204 can take a wide variety of
different forms. For example, any arrangement that can be rotatably
mounted around the mounting plate 2202 and that can support a tire
160 (FIGS. 1 and 1A) can be used. In the embodiment illustrated by
FIGS. 21A and 21B, the rotor housing assembly 2204 has a clam-shell
configuration that includes an outer cover 2302 and an inner cover
2304. Referring to FIG. 21B, the illustrated outer cover 2302
includes a generally disk shaped end face 2306, a radially outer
wall 2308, and a radially inner bearing wall 2310. The outer cover
2302 fits over the stator armature assembly 2206 and mounting plate
2202 and is rotatably connected to the stator side portion 2242 of
the central post by the bearing 2250 (FIG. 21A). The bearing 2250
may be coupled to the outer cover 2302 and to the stator side
portion 2242 of the central post 2241 in a wide variety of
different ways. For example, in the illustrated embodiment, the
bearing 2250 may be press fit into the radially inner wall 2310
against a bearing support flange 2312 (FIG. 22B) that extends
radially inward from the radially inner wall 2310, past an annular
groove 2314 that extends radially outward from the radially inner
wall 2310. A snap ring 2316 snaps into the annular groove 2314 to
secure the bearing 2350 to the outer cover 2302. The bearing 2250
may also be press fit around the stator side portion 2242 of the
post 2241 against a bearing support flange 2322 (FIG. 21B) of the
post 2241. In the illustrated embodiment, a rim 2309 is connected
to the outer cover 2302 by a plurality of fasteners. However, the
rim 2309 may be integrally formed with the outer cover 2302.
[0167] Referring to FIGS. 21A and 21B, the illustrated inner cover
2304 includes a generally disk shaped end face 2336, a radially
outer wall 2338, a rim 2339 extending radially outward from the
wall, and a radially inner bearing wall 2340. The rim 2339, like
the other components described in this application, may be made
from a single piece, or multiple pieces. The inner cover 2304 fits
over the brake assembly 2210 and mounting plate 2202 and is
rotatably coupled to the brake side of the central post 2241 by the
bearing 2252 (FIGS. 21A and 21B). In the illustrated embodiment,
the bearing 2252 is press fit into the radially inner wall 2340
against a bearing support flange 2342 (FIG. 21B) that extends
radially inward from the radially inner wall 2340. The bearing 2250
may also be press fit around the brake side of the post 2241
against a bearing support flange 2352 of the post 2241. However,
any manner of coupling the inner cover 2304 and to the brake side
portion 2244 of the central post 2241 may be employed.
[0168] In an exemplary embodiment, the outer cover 2302 is secured
to the and the inner cover 2304 to complete the rotor housing
assembly 2204. In the illustrated embodiment, the outer cover 2302
is securable to the inner cover 2304 by a plurality of fasteners.
However, any manner of connection may be used. In the illustrated
embodiment, an annular recess is defined between the two rims 2309,
2339 to accept a tire.
[0169] The stator armature assembly 2206 may take a wide variety of
different forms. Any conventional stator armature assembly may be
used. In the embodiment illustrated by FIG. 19 A, the stator
armature assembly 2206 includes a core 2400 and a plurality of
windings 2402. The illustrated core 2400 comprises a plurality of
annular plates that are stacked. The plates each include an annular
central opening and a plurality of radially outwardly extending
legs. The illustrated stator armature assembly 2206 is fixed to the
base member 2202 around the stator support wall 2245.
[0170] The rotor magnet ring assembly 2208 may take a wide variety
of different forms. Any conventional rotor configuration may be
employed. In the embodiment illustrated by FIG. 21C, the rotor
magnet ring assembly 2208 includes an annular support ring 2450 and
a plurality of permanent magnets 2452 attached to an inner wall of
the support ring. The illustrated rotor magnet ring assembly 2208
is fixed to the rotor housing assembly 2204 around the stator
armature assembly 2206. The fixing of the rotor magnet ring
assembly 2208 to the rotor housing assembly 2204 may be
accomplished in a wide variety of different ways. For example, the
outer cover 2302 may be molded or cast over the annular support
ring 2450. Alternatively, the outer cover may be molded or cast
around the magnets 2452 and the support ring 2450 may optionally be
omitted. Further, adhesive, fasteners, etc may be used to connect
the support ring 2450 and/or the magnets to the housing assembly
2204.
[0171] In the embodiment illustrated by FIGS. 21A and 22B, the
brake assembly 2210 has a drum brake configuration and is
positioned on a brake side of the central portion 2240 of the base
member 2202. The brake assembly 2210 includes a pair of brake shoes
2600, a pair of brake pads 2602, and a brake actuator 2604. The
brake actuator 2604 selectively moves the brake shoes 2600 and
associated pads into (FIG. 29) and out of (FIG. 28) engagement with
an inner surface 2608 of the rotor housing assembly 2204 (or
alternatively with a lining secured to the inner surface of the
rotor housing assembly).
[0172] The brake shoes 2600 can take a wide variety of different
forms. In the embodiment illustrated by FIGS. 23A-23C, the brake
shoes 2600 are mirror images of one another. As such, only one
brake shoe 2600 will be described in detail. Each brake shoe 2600
has an outer pad mounting surface 2620, a plurality of glides 2622,
and an actuator mounting portion 2624 that extends radially inward
from the pad mounting surface 2620. The outer pad mounting surface
2620 is generally the shape of a cylindrical segment and is
positioned to be parallel to the cylindrical inner surface 2608 of
the rotor housing assembly 2204 when the brakes are disengaged
(FIG. 28). In the illustrated embodiment, the pad mounting surfaces
2624 extend along a substantial portion of the cylindrical inner
surface of the rotor housing assembly 2204. For example, an angle
.theta. between ends 2630, 2632 of the pad mounting surfaces 2624
may be 150.degree. or more (See FIG. 23B).
[0173] The actuator mounting portion 2624 includes an actuator
mounting aperture 2650 and a link mounting aperture 2652. A pin
clamping surface 2654 is defined at an end of the actuator mounting
portion 2624. The pin clamping surface 2624 has the shape of a
portion of a cylinder to engage a cylindrical pin 2656 that is
attached to the mounting plate. The complimentary shapes of the
clamping surfaces 2654 and the pin 2656 allow the brake assembly
2210 to be preassembled and then assembled with the mounting plate
2202 simply by sliding the clamping surfaces 2654 over the pin
2656. This may be done before or after the mounting plate 2202 is
assembled with the stator assembly 2206 and/or outer cover
2302.
[0174] FIGS. 23D-23G illustrate an exemplary embodiment where the
brake pads 2602 are overmolded onto the brake shoe 2600. In the
illustrated embodiment, the pad mounting surface 2620 includes a
plurality of discrete projections 2670 with undercuts 2672. When
the brake pads 2602 are molded onto the brake shoe 2600, the brake
pad material 2674 flows over the projections 2670 and into the
undercuts 2670 to secure the pads 2602 to the shoes 2600. The
illustrated brake pads 2602 include optional reliefs 2680.
[0175] The molded pads can be made from a wide variety of different
materials, including but not limited to, plastics, natural and/or
synthetic rubber, carbon fiber, powdered metals, ceramics, and
combinations of these materials. In one exemplary embodiment, the
molded pads are made from natural and/or synthetic rubber having a
durometer of 60-90 Shore A durometer, a 70-90 Shore A durometer, a
75-90 Shore A durometer, or an 80 Shore A durometer.
[0176] When the brakes are disengaged in the embodiment illustrated
by FIGS. 24A and 24B, the brake shoes could possibly swing about
the pin as indicated by arrows 2658. For example, this swinging
might occur as the vehicle travels up or down a hill or
accelerates/decelerates. This swinging from a circular pin could
potentially cause some dragging of the brakes.
[0177] In one exemplary embodiment, the brake assembly 2210
includes an anti-swing arrangement that inhibits or reduces the
swinging of the disengaged brakes to inhibit the dragging described
above. The anti-swing arrangement can take a wide variety of
different forms. For example, a structure that acts between the
mounting plate 2202 and the brake shoes, such as a spring, a stop,
etc. can be used. In the embodiment illustrated by FIGS. 24A-24C, a
pair of stops 2403 are secured to the mounting plate 2202. The
stops 2403 are positioned to engage the shoes 2600 if the brakes
begin to swing when the brakes are disengaged to thereby inhibit
brake drag. The stops 2403 can take a wide variety of different
forms. In one embodiment, the positions of the stops 2403 are not
adjustable. For example, the non-adjustable stops may comprise
cylindrical members with centered attachment structures (i.e.
centered male or female threads). It should be apparent that the
mounting plate could be adapted to make such non-adjustable stops
adjustable by allowing the stops to be mounted at multiple
locations (i.e. by providing a mounting slot, clearance, multiple
distinct locations, etc.).
[0178] In the illustrated embodiment, the positions of the stops
2403 are adjustable, for example to account for tolerances or to
allow different amounts of swing. The adjustability of the stops
may be accomplished in a variety of different ways. As noted above,
the mounting plate 2202 may be adapted to allow adjustment of the
stops. In an exemplary embodiment, the stops 2403 themselves are
configured to allow adjustment of the stops. The stops can be
configured to allow adjustment in a variety of different ways. In
the illustrated embodiment, the stops 2403 are cylindrical with an
off-center mounting structure 2405, such as off-center male or
female threads. To adjust the amount of allowable swing or to
compensate for tolerances, the stops are simply rotated about their
off-center mounting to adjust the distance between the brake shoes
2600 and the stops 2403. Once adjusted, the mounting is tightened
to fix the positions of the stops. For example, when the brakes are
disengaged, the stops 2403 may be rotated into contact with the
brake shoes 2600 or nearly into contact with the brake shoes and
then tightened to the mounting plate 2202.
[0179] In an exemplary embodiment the stops 2403 are configured to
allow the brake assembly 2210 to be pre-assembled and then
assembled with the mounting plate 2202. This can be accomplished in
a wide variety of different ways. In the embodiment illustrated by
FIG. 22-B, the stops 2403 fit between the brake shoes 2600 and the
clamping surfaces 2654 of the shoes slide over the pin 2656. The
stops 2403 may be adjusted and tightened after assembly with the
mounting plate 2200 or may be positioned and tightened before
assembly with the mounting plate 2202. As noted above, the assembly
of the brake assembly 2210 with the mounting plate 2202 may be done
before or after the mounting plate is assembled with the stator
assembly 2206 and/or the outer cover 2302.
[0180] By preventing the brake shoes 2602 from rotating with
respect to the pin 2654 as indicated by arrows 2658 (see FIGS. 24A
and 24B) when the brakes are disengaged, the brakes are prevented
from dragging when the vehicle travels up or down a hill and/or
when the vehicle accelerates or decelerates. That is, the brake
shoes 2602 are prevented from swinging about the pin 2654 such that
one of the brake pads contacts the rotor housing assembly 2204 when
the vehicle travels up or down a hill and/or when the vehicle
accelerates or decelerates.
[0181] In embodiment illustrated by FIG. 28, the brake pads 2602
are mirror images of one another. However, in other embodiments,
the brake pads 2602 may have different sizes and shapes. Each brake
pad 2602 is mounted to the pad mounting surface 2620 of a brake
shoe. The brake pad 2602 has the shape of a cylindrical segment. In
the embodiment illustrated by FIG. 24A, the brake pads 2602 extend
along a substantial portion of the cylindrical inner surface of the
rotor housing assembly 2204. For example, an angle 13 between ends
2680, 2682 of the pads 2602 may be 150.degree. or more.
[0182] Referring to FIGS. 26A and 27A, the illustrated brake
actuator 2604 comprises an electrically powered linear actuator
2700 and a spring 2702. FIGS. 26A-26C illustrate the actuator 2604
in and extended condition and FIGS. 27A and 27B illustrate the
actuator in a retracted condition. The illustrated electrically
powered linear actuator 2700 includes a body 2703 that surrounds a
magnet coil 2705 that accepts a movable shaft 2704. A fixed shaft
2706 is also surrounded by the magnet coil 2750, but is fixed
relative to the magnet coil 2705 and the body 2703 at the end that
is opposite the shaft 2704.
[0183] Referring to FIG. 26D, the movable shaft 2704 and the fixed
shaft 2706 have complimentary mating surfaces, which may take a
wide variety of different forms. In the illustrated embodiment, the
movable shaft 2704 has a male frusto-conical end 2671 that mates
with a female frusto-conical recess 2673 of the fixed shaft 2706.
However, the moveable shaft 2704 can be female and the fixed shaft
2706 can be male. The frusto-conical male end 2671 includes a
tapered surface 2675 and a flat end wall 2677. The frusto-conical
female recess 2673 includes a tapered surface 2685 and a flat end
wall 2687.
[0184] The size and shape of the size and shape of the mating
surfaces 2671, 2673 effect the performance of the actuator. For
example, larger end walls 2677, 2687 provide more holding force
(i.e. the force required to pull the end walls apart when the
electromagnet is energized and the end walls are in contact). As
such, cylindrical shafts with flat ends would provide the most
holding force. However, larger end walls 2677, 2687 can result in
lower pulling force (i.e. the force urging the movable shaft 2704
relatively toward the fixed shaft when the end walls 2677, 2687 are
spaced apart and the electromagnet is energized). Conversely,
larger tapered surfaces 2675, 2685, with one extending into the
other, increase the amount of pulling force, but do not provide as
much holding force. In an exemplary embodiment, the size and shape
of the end walls 2677, 2687 and the tapered surfaces 2675, 2685,
along with other parameters (i.e. electromagnet properties--size,
number of wire turns, power applied, etc., shaft materials, shaft
travel, etc.) are selected to provide the desired pulling force and
the desired holding force.
[0185] FIGS. 27D and 27E illustrate another exemplary configuration
of the shafts 2704, 2706. Either shaft can be the fixed shaft with
the other shaft being the moveable shaft. In the illustrated
example, the inner tapered surface 2685 of the shaft 2706 is spaced
apart from the outer tapered surface 2675 of the shaft 2704 when
the flat end wall 2677 of the shaft 2704 is in engagement with the
flat inner wall 2687 of the shaft 2706 to form a gap G. The gap G
ensures that the end walls 2677, 2687 always engage one another
before the shafts bottom out due to engagement between the tapered
surfaces 2675, 2685. This ensures that the actuator 2604 always
retracts to the same position while still providing a strong
pulling force.
[0186] The fixed shaft 2706 has a slot 2708 at its end and has a
bore 2710 that intersects the slot 2708. Referring to FIG. 22C, the
slot 2708 is placed over the actuator mounting portion 2624 and a
fastener is placed through the bore 2710 of the mounting member
2706 and through the actuator mounting aperture 2650 (see FIG. 23A)
to connect one end of the actuator 2700 to one of the shoes 2600.
Similarly, the shaft 2704 has a slot 2718 at its end and has a bore
2720 that intersects the slot 2718. Referring to FIG. 22C, the slot
2718 is placed over the actuator mounting portion 2624 and a
fastener is placed through the bore 2720 of the shaft 2704 and
through the actuator mounting aperture 2650 (see FIG. 23A) to
connect the other end of the actuator 2700 to the other shoe
2600.
[0187] The spring 2702 can take a wide variety of different forms.
Any spring capable of biasing the brakes to an engaged position or
to a released position can be used. In the illustrated embodiment,
the spring 2702 is a compression spring that is disposed around the
shaft 2704 and acts against the actuator body 2703. The illustrated
shaft 2704 has an annular groove 2730 (FIG. 26D) that accepts a
snap ring 2732 or another fastening arrangement can be used. The
spring 2702 is captured between the body 2703 and the snap ring
2732. As such, the spring 2702 biases the shaft 2704 as indicated
by arrow 2734 to a normally extended position. Referring to FIGS.
26A-26C and FIG. 29, the spring 2702 extends the shaft 2704 to bias
the brakes into a normally engaged position. Referring to FIGS.
27A, 27B and 28, when the actuator 2700 is energized, the shaft
2704 is pulled into the body 2703 against the biasing force of the
spring 2702 and into contact with the shaft 2706 to move the brakes
to a released position. In one exemplary embodiment, once the flat
end walls 2677, 2687 engage, the amount of power applied to the
electromagnet may be reduced, since the flat end walls provide
increased holding force. As such, the power consumed by operation
of the brakes may be reduced to extend the battery life of the
vehicle.
[0188] In the illustrated embodiment, the brake assembly 2210 also
includes a brake link 750. The brake link 750 is illustrated as
being adjustable in length, but may be a member having a fixed
length. The brake link 750 has bores 760 that align with apertures
2652 to connect the ends of the brake link to the shoes 2600.
[0189] The brake shoe glides 2622 and the glide support protrusions
2247 can take a wide variety of different forms. The glides 2622
and the glide support protrusions are configured to allow the brake
shoes 2600 to smoothly move back and forth between the engaged and
released positions. In the illustrated embodiment, the glides 2622
comprise cylindrical bosses with flat engagement surfaces. The
glides 2622 slide against the glide support protrusions 2247 on the
central wall portion 2240 of the mounting plate 2202. The glides
2622 and/or the glide support protrusions 2247 of the mounting
plate 202 can be configured to reduce friction between the glides
2622 and the mounting plate 2202. This reduction in friction can be
accomplished in a wide variety of different ways. For example, the
glides 622 and/or the glide support protrusions 2247 can be made
from a low-friction material, such as nylon, Teflon, silicone,
etc., surfaces or portions of surfaces of the glides 2622 and/or
the glide support protrusions 2247 can be coated with a low
friction material, such as nylon, Teflon, silicone, etc. and/or an
anti-friction grease can be applied between the contacting
surfaces.
[0190] In one exemplary embodiment, the brake assembly 2210
includes a retaining mechanism 2800 (See FIGS. 22C and 22D) that
prevents the brake shoes 2600 from moving too far axially away from
the wall portion 2240 of the mounting plate 2202. For example, the
retaining mechanism 2800 prevents the brake shoes 2600 from moving
away from the wall portion 2240 and into contact with the rotor
housing assembly 2204. In one embodiment, the retaining mechanism
2800 keeps the glides 2622 near the wall portion 2240 of the
mounting plate 2202 or in contact with the wall portion 2240 of the
mounting plate 2202. The retaining mechanism 2800 can take a wide
variety of different forms. For example, the retaining mechanism
may comprise one or more springs that bias the brake shoes 2600
toward the wall portion 2240 of the mounting plate 2202, one or
more stops or stop brackets that limit the movement of the brake
shoes 2600 away from the wall portion 2240, etc. Any mechanism that
prevents the brake shoes 2600 from moving axially outward and/or
tilting or canting such that the brake shoes axially contact with
the rotor housing assembly 2204 or a component that rotates with
the rotor housing assembly may be used.
[0191] In the embodiment illustrated by FIG. 22C, the retaining
mechanism 2800 comprises washers 2801 that are connected in a
spaced apart relationship to the wall portion 2240 by a brake
release mechanism 3000 (described in detail below). The brake shoes
2600 are positioned between the wall portion 2240 and the washers
to limit the axial movement of the brake shoes 2600 away from the
wall portion 2240. A clearance may be provided between the brake
shoes 2600 and the washers 2801 of the retaining mechanism 2800,
such that the brake shoes and glides float between the washers 2801
and the glide support protrusions 2247 of the mounting plate 2202.
An additional stop and/or stop bracket (not shown) may be provided
to prevent or limit tilting of each brake shoes 2600 about the area
of engagement between the brake shoe 2600 and corresponding washer
2801.
[0192] FIGS. 28 and 29 illustrate normal operation of the brake
assembly 2210. That is, FIGS. 28 and 29 illustrate operation of the
brake assembly 2210 by the actuator 2700. FIG. 28 illustrates the
brake assembly 2210 in a released or disengaged condition. For
example, when a user of the wheelchair 100 (FIG. 1) presses on the
joystick 124 (FIG. 1), the actuator 2700 is energized and the shaft
2704 is retracted against the biasing force of the spring 2702. The
actuator 2700 pulls the brake pads together as indicated by arrows
2703 in FIG. 28 and the pin clamping surfaces 2654 (FIG. 23A) are
brought into contact with the pin 2656. When the pin clamping
surfaces 2654 engage the pin 2656, the brake pads 2602 are spaced
apart from the inner wall (or brake lining) 2608 of the rotor
housing assembly 2204.
[0193] When the brake assembly 2210 is in the disengaged position
shown in FIG. 28, the wheelchair begins to move in the direction
selected by operating the joystick 124 (FIG. 1). In the example
illustrated by FIGS. 28 and 29, arrow 2820 represents the direction
of movement of the wheelchair 100 (FIG. 1) and arrow 2822
represents the corresponding direction of rotation of the rotor
housing assembly 2204 around the mounting plate 2202 for movement
in this direction.
[0194] FIG. 29 illustrates the brake assembly 2210 in an engaged
position. For example, when the user of the wheelchair 100 releases
the joystick 124 (FIG. 1), the actuator 2700 is de-energized and
the shaft 2704 is extended by the biasing force of the spring 2702.
In some embodiments, this de-energizing is delayed.
[0195] When the actuator is de-energized, the spring 2702 pushes
the brake pads apart as indicated by arrows 2705 in FIG. 29 and
into contact with the rotor housing assembly 2204. When the rotor
housing assembly 2204 is rotating in the direction indicated by
arrow 2822, the clamping surface 2654 of the brake shoe shown on
the right in FIG. 29 substantially remains in engagement with the
pin 2656 and rotates about the pin to bring its pad 2602 into
contact with the wall or lining 2608. The brake shoe 2600 shown on
the left in FIG. 29 rotates about the connection to the brake link
750 to bring its pad 2602 into contact with the wall or lining
2608. Once the wheelchair 100 (FIG. 1) is stopped, the brake
assembly 2210 remains engaged until the actuator 2700 is energized
again or the brakes are disengaged by a manual brake disengagement
mechanism 3000 (described in detail below).
[0196] One feature of the exemplary brake assembly shown in FIGS.
28 and 29 is that the brake shoes 2600 and brake pads 2602 are
mirror images of one another and the brake pads 2602 are sized such
that the drive assembly 2200 can be used on either side of the
wheelchair 100 (or other vehicle), without changing the performance
of the brakes.
[0197] Another feature that contributes to the ambidextrous nature
of the brake assembly is that the action of the brake shoes (i.e.
one brake shoe 2600 engages the pin 2656, while the other brake
shoe pivots) automatically reverses, simply by placing the drive
assembly on the opposite side of the vehicle. No adjustment to the
brake assembly 2210 is required to used the drive assembly on
either side of the vehicle.
[0198] Referring to FIG. 28, when the drive assembly 2200 is used
on a powered wheelchair 100 (FIG. 1), it may be advantageous to
include a brake release assembly 3000. For example, should a person
wish to manually push the wheelchair 100 having a brake system as
described above, normally engaged brakes need to be released before
the person could push the wheelchair. While provisions can be made
to release the brakes electrically (i.e. by providing a switch that
energizes the actuator 2700), a manual brake override is preferred,
since it is operable even though power may not be available to the
actuator 2700.
[0199] The manual brake release mechanism 3000 can take a wide
variety of different forms. Any configuration that allows the brake
assembly 2210 to be manually disengaged can be implemented. In the
example illustrated by FIGS. 22D and 22E, the manual brake override
includes a cam driver mechanism 3002, brake shoe cam surfaces 3004,
and a handle 3006 (FIG. 22A). The handle 3006 can be operated such
that the cam driver mechanism 3002 engages the brake shoe cam
surfaces 3002 to move the brake shoes 2600 to a manual brake
release position (See FIG. 22A).
[0200] The cam driver mechanism 3002 and brake shoe cam surfaces
3004 may take a wide variety of different forms. Any arrangement
capable of moving the brake shoes 2600 to the released position can
be used. In the embodiment illustrated by FIGS. 22D and 22E, the
cam drive mechanism 3002 includes a drive member 3010 and a pair of
cam members 3011 (In some views, the cam members 3011 are hidden
behind a washer 2801. In other views, washers 2801 are removed to
show the cam members 3011). Referring to FIGS. 31A and 31B, the
drive member 3010 may include an annular central hub portion 3012,
a pair of legs 3014 (which may be integrally formed or separate
members that are attached) extending axially from the annular
central hub portion 3012, and a pair of arms 3015 that extend
radially outward from the central hub portion. Referring to FIG.
22D, the illustrated cam members 3011 are rollers that are
rotatably mounted to the arms 3015. However, the cam members 3011
may be fixed to the arms or integrally formed with the arms.
[0201] The brake shoe cam surfaces 3004 can take a wide variety of
different forms. The cam surfaces 3004 may be integrally formed
with the brake shoes 2600 or the cam surfaces 3004 may comprise
separate members that are attached to the brake shoes. The cam
surfaces 3004 may comprise any structure capable of being engaged
by the cam mechanism 3002 to move the brakes to a disengaged
position. Referring to FIG. 23B, the illustrated cam surfaces 3004
comprise slots 3020 formed in the brake shoes. An inner surface of
each slot forms the cam surface 3004. The inner surface includes a
central portion 3024 and two outer portions 3026. The central
portion 3024 is closer to the central axis X of the base member
2202 than the outer portions 3026. The illustrated central portion
3024 is flat to provide a "dwell" to the brake release assembly.
That is, the flat portion 3024 prevents or reduces the likelihood
that the cam members will unintentionally slide or roll off of the
central portion 3024 to one of the outer portions 3026. One or more
detents can be added to the central portion 3024 to further reduce
the chance that the cam members will unintentionally roll off the
central portion 3024.
[0202] Referring to FIG. 22B, the hub portion 3012 of the drive
member 3010 is rotatably coupled around the central post 2241. An
optional bearing (not shown) may be included to reduce friction
between the drive member 3010 and the central post 2241 and/or the
wall portion 2240. The legs 3014 of the drive member 3010 are
disposed in the passages 2280. The clearance between the legs 3014
and the passages 2280 define the amount of possible rotation of the
drive member 3010 about the central post 2241. Referring to FIGS.
28 and 30, about 15 degrees of travel is allowed, but any amount of
travel can be defined. The arms 3015 are positioned between the
brake shoes 2600 and the wall portion 2240 of the mounting plate
2202. The cam members 3011 are disposed in the slots 3020.
[0203] Referring to FIG. 22B, a handle 3006 is connected to the
legs 3014 of the drive member 3010. The handle 3006 is movable
between a disengage position (See FIG. 30) and two "allow
engagement" positions (See FIGS. 28A, 28B, 29A, and 29B). In the
disengage position (FIG. 30), the cam members 3011 engage the
central portions 3024 of the slots 3020. The cam members 3011 press
against central portions 3024 and pull the brake pads together,
such that the pin clamping surfaces 2654 are brought into
engagement with the pin 2656 (see FIG. 24A). This action compresses
the spring 2702. When the pin clamping surfaces 2654 engage the pin
2656, the brake pads 2602 are spaced apart from the inner wall 2608
or brake lining. When the manual brake release mechanism 3000 is in
the disengage position shown in FIG. 30 the brakes are released and
the wheelchair may easily be pushed by a user.
[0204] When the handle 3006 is in one of the two "allow engagement"
positions (FIGS. 28A, 28B, 29A, 29B), the cam members 3011 are
spaced apart from the cam surfaces defined by the slots 3020 and
the brake assembly 2210 is operated by the actuator 2700 as
described above. For example, if no power is applied to the
actuator 2700, the brakes are engaged (FIGS. 29A 29B) and if power
is applied to the actuator, the brakes are disengaged (FIGS. 28A,
28B). In the illustrated embodiment, in the allow engagement
positions, enough clearance is provided between the cam surfaces
defined by the slots 3020 and cam members 3011 to prevent any
engagement between the cam members 3011 and the cam surfaces during
operation of the brake assembly by the actuator 2700.
[0205] Referring to FIG. 28, in one exemplary embodiment, a sensor
3100, such as a micro-switch (any type of sensor may be used) is
positioned to detect whether or not the manual brake release
mechanism 3000 is in the disengaged position (or the "allow
engagement" position). The output of the sensor 3100 may be used
for a variety of different control functions. For example, when the
output of the sensor 3100 indicates that the manual brake override
is in the disengage position, the drive circuitry may prevent power
from being applied to the motor windings 2402 and/or the actuator
2700. Referring to FIGS. 28 and 30, the illustrated central hub
portion 3012 of the drive member 3010 includes a cam surface 3300.
The illustrated cam surface 3300 includes a peak 3302. Referring to
FIG. 30, an actuator 3308 of the sensor is engaged by the peak
3302, and is therefore depressed. This indicates that the brake
release mechanism 3000 is in the brake release position. Referring
to FIGS. 28A and 28B, when the handle 3006 is in one of the "allow
brake engagement" positions, the sensor actuator 3308 is extended.
This extended actuator 3308 indicates that the brakes are in one of
the "allow disengagement" positions.
[0206] Referring to FIG. 28, in one exemplary embodiment, a dual
detent mechanism 3200 may be included such that the brake release
mechanism 300 positively stops at the disengagement position and
each of the "allow engagement" positions. Any type of detent
mechanism may be used. By way of example, the detent mechanism 3200
may a pair of spaced apart spring loaded pins 3201 that are
attached to the cam drive member 3010 (FIGS. 31A and 31B). The
spring loaded pins are biased into recess of a corresponding pair
of recess sets 3203 (FIG. 20A). Each set of recesses 3203 have a
recess that corresponds to the brake release position (the middle
recess in the illustrated embodiment) and the two recesses that
correspond to the "allow brake engagement" position (the two outer
recesses in the illustrated embodiment). In the illustrated
embodiment, the spring loaded pins 3201 are positioned to balance
the load applied to the drive member 3010 when the mechanism is
moved from one position to another.
[0207] Referring to FIG. 30, the manual brake release mechanism
3000 is constructed such that the handle 3006 is in a top
dead-center position when the brake release mechanism 3000 is in
the disengage position. Further, the brake release mechanism 3000
is configured such that the handle 3006 is moved and/or pivoted the
same distance and/or angle from the disengage position to each of
the "allow engagement" positions (See FIGS. 28A and 28B).
[0208] In another embodiment, the manual brake release mechanism
3000 is configured to have one "allow engagement" position and two
disengage positions. The manual brake release mechanism 3000 may be
constructed to have the handle 3006 in a top dead-center position
when the manual brake release mechanism 3000 is in the "allow
engagement" position. Further, the manual brake release mechanism
3000 may be configured such that the handle 3006 is moved and/or
pivoted the same distance and/or angle from the "allow engagement"
position to each of the disengage positions. For example, the
handle 3006 may be pivoted in opposite directions from the top
dead-center position to reach the disengage positions.
[0209] By configuring the handle 3006 to be positioned at top
dead-center for the manual disengage position (or "allow
engagement" position) and configuring the handle to be moveable in
opposite directions to two equally spaced "allow engagement"
positions (or manual disengage positions), the same drive assembly
2200 can be used on either side of the wheelchair 100 (or other
vehicle), while providing the same control positions for the handle
3006 of the manual brake release mechanism 3000. That is,
regardless of the side of the wheelchair 100 (or other vehicle)
that the drive assembly 2200 is mounted on, the control of the
manual brake release mechanism 3000 is the same. In the illustrated
embodiment, the drive assembly on either side of the wheelchair 100
is placed in the manual brake disengage position by positioning the
handle 3006 at the top dead center position and is placed in the
"allow engagement" position by moving the handle forward (and/or
backward). No adjustments to the drive assembly 2200 are required.
However, if configuring the manual brake release mechanism 1000 to
have only one manual brake disengagement position and only one
allow engagement is desired, a simple bracket or other blocking
member can be positioned to prevent the handle 1006 (or other
component of the mechanism) from moving in one direction. Still,
the same drive assembly can be used on both sides of the wheelchair
100 (or other vehicle).
[0210] While various inventive aspects, concepts and features of
the inventions may be described and illustrated herein as embodied
in combination in the exemplary embodiments, these various aspects,
concepts and features may be used in many alternative embodiments,
either individually or in various combinations and sub-combinations
thereof. Unless expressly excluded herein all such combinations and
sub-combinations are intended to be within the scope of the present
inventions. Still further, while various alternative embodiments as
to the various aspects, concepts and features of the
inventions--such as alternative materials, structures,
configurations, methods, circuits, devices and components,
hardware, alternatives as to form, fit and function, and so on--may
be described herein, such descriptions are not intended to be a
complete or exhaustive list of available alternative embodiments,
whether presently known or later developed. Those skilled in the
art may readily adopt one or more of the inventive aspects,
concepts or features into additional embodiments and uses within
the scope of the present inventions even if such embodiments are
not expressly disclosed herein. Additionally, even though some
features, concepts or aspects of the inventions may be described
herein as being a preferred arrangement or method, such description
is not intended to suggest that such feature is required or
necessary unless expressly so stated. Still further, exemplary or
representative values and ranges may be included to assist in
understanding the present disclosure, however, such values and
ranges are not to be construed in a limiting sense and are intended
to be critical values or ranges only if so expressly stated.
Moreover, while various aspects, features and concepts may be
expressly identified herein as being inventive or forming part of
an invention, such identification is not intended to be exclusive,
but rather there may be inventive aspects, concepts and features
that are fully described herein without being expressly identified
as such or as part of a specific invention. Descriptions of
exemplary methods or processes are not limited to inclusion of all
steps as being required in all cases, nor is the order that the
steps are presented to be construed as required or necessary unless
expressly so stated.
[0211] While the present invention has been illustrated by the
description of embodiments thereof, and while the embodiments have
been described in considerable detail, it is not the intention of
the applicant to restrict or in any way limit the scope of the
invention to such detail. Additional advantages and modifications
will readily appear to those skilled in the art. For example, the
specific locations of the component connections and interplacements
can be modified. Still further, while cylindrical or elliptical
tubular components have been shown and described herein, other
geometries can be used including polygonal (e.g., square,
rectangular, triangular, hexagonal, etc.) can also be used.
Therefore, the invention, in its broader aspects, is not limited to
the specific details, the representative apparatus, and
illustrative examples shown and described. Accordingly, departures
can be made from such details without departing from the spirit or
scope of the applicant's general inventive concept.
* * * * *