Note: Descriptions are shown in the official language in which they were submitted.
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LINEAR ACTUATION DRIVE MECHANISM FOR POWER-ASSISTED CHAIRS
CROSS-REFERENCE TO RELATED U.S. PATENTS
The present application is related to U.S. Patents
Nos. 5,314,238 and 5,466,046.
BACKGROUND OF THE INVENTION
The present invention relates generally to power-assisted
articles of furniture and, more particularly, to a multi-function chair having
a linear actuation drive mechanism selectively operable for lifting and tilting
the chair, extending and retracting a leg rest assembly and reclining the chair
between upright and fully reclined positions.
Conventionally, power-assisted chairs typically include a motor-
operated lift mechanism for aiding invalids and those persons requiring
assistance in entering or exiting the chair. More particularly, motor-operated
lift mechanisms are interconnected between a stationary base assembly and
a moveable chair frame. An example of such a power-assisted chair is
disclosed in commonly owned U.S. Patent No.
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4,993,777 which issued February 19, 1991, and is entitled "Recliner Chair Lift Base
Assembly".
Some power-assisted chairs also include se,uarale linkage mechanisms
for perr"illi,)g the seat occupant to selectively ~ te an extensible leg rest assembly
5 and/or produce reclining angular movement of a seat assembly between "upright" and
"reclined" positions. However, power-assisted chairs which provide such a multi-
functional combination generally require the use of multiple motors for driving (i.e.,
pushing) the separate linkages which results in extremely large and expensive chair
units. Moreover, such power-assisted chairs typically incorporate a drive mechanism
10 which employs both a power "drive" function (i.e., for extending the leg rest, lifting the
chair, and reclining the chair) and a power "return" function for returning the chair to
the normal seated position.
SUMMARY OF THE INVENTION
Accordingly, the present invention overcomes the disadvantages
15 associated with conventional power-assisled chairs by providing a single linear
actuation drive mechanism that is operable for selectively and independently ~ctu~ting
a reclining linkage assembly and a leg rest linkage assembly, in addition to ~ctll~tirlg
a lift and tilt mechanism for raising, lowering and tilting the chair.
In a preferred form, the power-assisted linear actuation drive mechanism
20 of the present invention includes a driven member which is linearly movable in
response to rotation of a motor-driven screw shaft in a first direction for selectively
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~ctu~ting the lift and tilt mechanism for causing forward lifting and tilting movement of
the chair. Thereafter, rotation of the motor-driven screw shaft in a reverse or second
direction acts to lower the chair to the normal seating position. Continued rotation of
the screw shaft in the second direction c~uses cam means associated with the driven
5 member to sequentially engage a first follower assembly for extending the leg rest
assembly and a second follower assembly for causing angular reclining movement of
the chair. Moreover, such sequential actuation of the leg rest assembly and the
reclining linkage assembly are independent and may be easily disabled to selectively
eliminate either of the power-assisted features. In addition, the linear actuation drive
10 mechanism of the present invention also includes adjustable means for permitting
precise calibration (i.e., setting) of the fully extended position for the leg rest assembly
during final assembly of the power-assisted chair. Furthermore, the adjustable means
is also adapted to facilitate in-service re-calibration of the fully extended position for
the leg rest assembly.
In an alternative preferred embodiment of the present invention the lift
base assembly of the present invention includes a number of novel structural
enhancements which even further enhance the rigidity of the various components of
the lift base assembly of the present invention and contribute to even further longevity
of the lift base assembly while adding little to the overall cost of constructing the lift
20 base assembly.
In the alternative preferred embodiment the single linear actuation drive
mechanism includes a modified leg rest follower assembly adapted to even better
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handle the wear and tear experienced during operation of the leg rest assembly of the
power-assisted multi-function chair described herein.
The alternative preren ed embodiment further incorporates novel
reinforcing strùcture for reinforcing various pivotally disposed tubular members at the
5 points about which they pivot. Angle reinforcing members are further incorporated to
"cradle" a portion of the wooden side rails of a lift base assembly of the ~ctu~tion
mechanism. A single-piece metal reinforcing plate has further been included to
provide even further rigidity to the wooden side rails between the points where the
drive mechanism couples to the wooden side rails. Numerous other structural
1û improvements are also included to improve the overall strength and rigidity of the
structure supporting and coupling the linear actuation drive mechanism to the lift base
assembly of the power assisted chair.
Other features and advantages of the present invention will become
apparent upon consideration of the drawings and the description set forth hereinafter.
DESCRIPTION OF THE DRAWINGS
Figures 1A through 1 D illustrate the various operative seating positions
for a power-assisted chair constructed according to a preferred embodiment of the
present invention;
Figure 2 is a plan view of a left-side portion of the chair frame, with its
2û upholstery removed, illustrating the various components of a power-assisted linear
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actuation drive mechanism which is adapted to selectively actuate a lift and tilt
mechanism, a reclinil ,y linkage asseml,ly and a leg rest linkage assemL,ly;
Figure 3 is a vertical cross-sectional view taken through the power-
assisled chair shown in Figure 1A;
Figure 4 is a vertical cross-sectional view taken through the power-
assisted chair shown in Figure 1 B;
Figure 5 is an opposite vertical cross-sectional view taken through the
power-assisted chair shown in Figure 1 C and showing the leg rest linkage assembly
in a fully extended position;
Figure 6 is a vertical cross-sectional view taken through the power-
assisted chair shown in Figure 1 D for illustrating the operative position of the reclining
linkage assembly following extension of the leg rest linkage assembly;
Figure 7 is an exploded perspective view of a cam and follower
arrangement associated with the linear actuation drive mechanism of the present
1 5 invention;
Figure 8 is an exploded view, generally similar to portions of Figure 7,
showing a modified construction for the follower assembly used to actu~te the leg rest
linkage assembly;
Figure 9 is an end view of the leg rest follower assembly shown in Figure
8;
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Figure 10 is a plan view, similar to Figure 2, illustrating an alternative
construction of the power-assisted linear actuation drive mechanism according
to another preferred embodiment of the present invention; and
Figure 1 1 is an exploded perspective view of the various components
5 associated with the linear actuation drive mechanism shown in Figure 10;
Figure 12 is a top, elevational, fragmentary view of a portion of the
lift base assembly showing the metal attachment plate used to reinforce each
wooden side rail between the points where the actuation drive mechanism is
supported on each wooden side rail;
Figure 13 is a side view of the portion of the lift base assembly
shown in Figure 12;
Figure 14 is a cross sectional view of one of the tubular side legs
showing how the side leg has been reinforced by the placement of an inner
tubular member coaxially therein, and further showing an enlarged pivot pin for
even better structurally supporting the tubular side leg for pivotal movement
relative to the wooden side rails;
Figure 15 is a side view of a portion of the lift base assembly
showing an angle bracket for supporting the upper frame member of the power
assisted chair in a manner which "cradles" the upper frame member;
Figure 16 is a cross sectional view of the upper frame member
showing the angle bracket secured thereto in accordance with section line
16-16 in Figure 15;
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Figure 17 is a front view of a portion of the leg rest follower assembly
showing the modified positioning of the cam followers, the increased size of the cam
followers, and the modified spacer bars;
Figure 18 is a side view of a portion of the power ~ssisted chair showing
5 a metal plate for rein~orc;ng securing of a frame member of the chair to each side arm
of the power-assisted chair; and
Figure 19 is a cross sectional view of a portion of the side arm in
accordance with section line 19-19 in Figure 18.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In general, the present invention is directed to a modified
construction for the cam and follower arrangement disclosed in commonly
owned U.S. Patent No. 5,061,010 which issued October 29, 1991, entitled
"Cam Guide Drive Mechanism For Power-Assisted Chairs And The Like".
However, to provide a sufficient basis for one skilled in the art to understand
the novelty of the inventive features to be hereinafter disclosed, the
following is a thorough discussion of the structure and function of a power-
assisted chair constructed according to the preferred embodiments of the
present invention.
According to the present invention, a lift base assembly 1 is
shown in Figures 1A through 1D supporting an upholstered chair 3 in
various operative positions. While any of a wide variety of chair
constructions can be used with lift base assembly 1, a well-known chair sold
by the assignee hereof under the registered trademark RECLINA-REST is an
example of one type of chair that can be mounted on lift base assembly 1.
In general, chair 3 has a frame 5 with side arms 7 and a seat assembly 8
supported from frame 5 and defined by a seat back 9 that may recline in
response to pressure applied thereto by a seat occupant and a seat portion
11 that moves simultaneously with seat back 9. Chair 3 also includes an
extensible leg rest assembly 13. Thus, Figure 1A shows upholstered chair
3 in a "normal" seated or "upright" position. Figure 1B illustrates chair 3
"lifted" to a forward-tilted position upon actuation of a lift and tilt
mechanism for making it easier for a person to enter or exit
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chair 3. Next, Figure 1C illusl,ales leg rest assembly 13 in a fully extended position
with chair 3 maintained in the upright seated position. Finally, Figure 1 D illuslrales
chair 3 having seat assembly 8 angularly moved to a fully "reclined" position following
extension of leg rest assembly 13.
With particular reference to Figures 3 through 6, lift base assembly 1 is
shown to have a stationary lower frame member 31 that rests on the floor and a
movable upper frame member 33 on which chair 3 is removably but securely attached
by suitable fasteners (not shown). Lower frame member 31 includes a pair of laterally-
spaced wooden side rails 35 that are rigidly secured to a wooden front cross rail 39.
Preferably, side rails 35 have suitable scuff-resistant pads 41 secured to a bottom
surface thereof which engage the floor.
Upper frame member 33 has a pair of laterally-spaced wooden side rails
45 that are rigidly interconnected to a wooden rear cross rail 49. Soft rubber-like pads
50 secured to the bottom surface of upper side rails 45 are adapted to help transfer
vertically-directed chair loads into bottom side rails 35 when chair 3 is in a non-lifted
position. Thus, wooden outer portions of lift base assembly 1 give the appearance
of an ordinary chair base. However, the lift and tilt mechanism to be described nests
inside of the wooden frame members and within chair frame 5 such that lift base
assembly 1 is of a low profile.
The front of upper frame member 33 is reinforced by a U-shaped pivot
bracket 51 having laterally-spaced side plates 53 (Figure 4) that are securely afffixed
to the inside faces of wooden side rails 45. In addition, the front ends of side plates
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53 are rigidly secured to pivot plates 57 which extend below wooden side rails
45 and into the confines of lower frame member 31, as seen in Figure 3. As
shown, pivot bracket 51 also includes a rectangular tube 59 that acts as a front
cross piece between pivot plates 57, and which is made rigid therewith such as
5 by welding. Furthermore, a tubular cross brace 61, located somewhat below
and to the rear of front cross piece 59, also extends between pivot plates 57
and is likewise made rigid therewith, as by welding.
The rear of lower frame member 31 is reinforced by a transverse
pivot bracket member 71 that includes side plates 73 that are securely affixed
10 to the inside faces of wooden side rails 35, as indicated at 75. Pivot bracket
member 71 also includes a rectangular tube 79 that acts as a rear cross piece
extending between side plate 73. Another transverse rectangular tube 83 is
fixed on top of tube 79 such that tubes 79 and 83 form a T-shaped load
carrying component of lift base assembly 1. Preferably, the height of tube 79
15 is such that tube 83 is located within the confines of upper frame member 33.
As best seen from Figure 2, the opposite ends of top tube 83
terminate a slight distance inwardly from side plates 73 and have a U-shaped
bracket 85 rigidly affixed in close proximity thereto. Brackets 85 receive the
rear ends of laterally-spaced side legs 87 of a U-shaped upper tilt bar member
20 89, with front ends of side legs 87 being rigidly affixed, such as by welding, to
opposite ends of a transversely extending front cross piece 91. More
preferably, the rear ends of upper tilt bar side legs 87 fit inside U-shaped
brackets 85 on lower frame member 31 and are pivotally attached
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thereto, as indicated at pivot point 93. In addition, the upper or front ends of side legs
87 are pivotally attached to pivot plates 57 on upper frame member 33. As seen best
in Figure 3, the height of combined tubes 79 and 83 is such that side legs 87 are
substantially horizontal when lift base assembly 1 is in the fully lowered or seated
position.
Upper tilt bar member 89 is a part of a lift and tilt linkage mecha"is,l, 97
that is operably associated with base lift assembly 1. Lift and tilt linkage mechanism
97 also includes a lower lift bar member 99 having tubular side legs 101 that are
pivoted at their rear ends to a central portion of lower frame member 31 and at their
forward ends to pivot plates 57 of upper frame member 33. More specifically, lower
lift bar member 99 is substantially H-shaped and includes a pair of laterally-spaced
side legs 101 that are spaced apart the same amount as side legs 87 of upper tilt bar
member 89, so as to be substantially coplanar therewith, though substantially shorter
in length. A rigid rectangular tube 103, similar to tube 79, extends between side legs
101 and is fixed thereto at central portions of side legs 101. The rearward ends of
side legs 101 are pivotally attached at pivots 105 to side brackets 107 that are rigidly
secured to the inside faces of lower frame member side rails 35, as indicated at 109.
In addition, the upper and front ends of side legs 101 are pivotally attached to lower
portions of pivot plates 57, as indicated at pivots 111. A pair of laterally-spaced
reinforcement bars 113 are provided to mainlai,1 parallelism and are cutout at 115 so
that they can pass close to the rear of cross brace tube 61. As seen best in Figure
3, the various parts of upper tilt bar member 89 and lower lift bar member 99
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associated with lift and tilt linkage mechanism 97 are confined within upper and
lower frame members 33 and 31, respectively, when lift base assembly 1 is in
the lowered or normal seating position. Thus, lift and tilt mechanism 97 is
constructed to have an operably low profile and be compact in nature.
In accordance with a preferred construction for lift base assembly 1,
a power-assist mechanism is operably connected to lower lift bar member 99
for arcuately pivoting it up or down about pivot pins 105 and, thereby for
operatively driving lift and tilt mechanism 97. The power-assist arrangement
includes an electric motor 121 having a flange 123 which fits between and is
pivotally attached at pivot 125 to opposite sides of a U-shaped pivot bracket
127 that is secured to a central portion of top cross piece 83 of pivot bracket
member 71 on lower frame member 31. Motor 121 is selectively operable for
rotating an elongated screw shaft 129 in either of a first or second direction.
Both motor 121 and rotary screw shaft 129 can arcuately swing up and down
in a generally vertical plane about pivot 125. While no attempt is made to limit
the specific control system for motor 121, reference can be made to U.S.
Patent No.5,061,010 for a complete description of a suitable electrical control
system as well as the structure of a suitable hand-operated control device for
selectively controlling the direction of rotation of screw shaft 129.
With particular reference to Figures 3 through 7, the power-assist
arrangement of the present invention is shown to also include a linear actuation
drive mechanism 132 that is adapted to selectively actuate a reclining linkage
assembly 134, leg rest assembly 13, and lift and tilt mechanism 97 in response
to energization of
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motor 121. In general, linear actuation drive mecl ,anism 132 is operable for
sequentially and independently ~ctuatirlg leg rest assembly 13 and reclining linkage
asse",bly 134 utilizing a single electric motor 121 and a driven member, hereina~ler
referred to as cam nut or guide 130. As will be described, screw shaft 129 exlel1cls
through and drives the internally threaded cam guide 130 such that cam guide 130moves forwardly or rearwardly along the length of screw shaft 129 upon driven
rotation of shaft 129 in one of the first and second directions. More specifically, cam
guide 130 is adapted to move linearly relative to screw shaft 129 for sequentially
engaging and driving a leg rest follower assembly 136 and a recliner follower
assembly 138 which, in turn, are operatively coupled to leg rest assembly 13 andreclining linkage 134, respectively. As will be appreciated, the use of a single power-
assisted drive system, such as linear actuation drive mecl,anis,n 132, provides for
selectively lifting and tilting chair 3 (via lift and tilt mechanism 97), extending and
retracting leg rest assembly 13 (via leg rest follower assembly 136), and angularly
moving seat back 9 and seat 11 of seat assembly 8 between an "upright" and a
"reclined" position (via recliner follower assembly 138).
Chair frame 5 is shown to include left and right side panels 140 having
rearwardly sloping uprights 142 with side panels 140 being interconnected by a rear
cross member 144 and front top and bottom transverse cross rails 146 and 148,
2û respectively, and which are joined together by bracket plates 150. Bracket plates 150
are secured to vertical uprights 152 located at the front end of side panels 140. As
best seen from Figures 2 and 6, chair frame 5 is mounted outside and generally on
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top of lift base assembly 1 and is pivotally secured thereto about a pivot 154 between
a bracket 156 fixed to an inner wall of chair frame side members 140 and a second
bracket 158 secured to an upper surface of side members 45 of upper frame member
33. In addition, a leg rest board or panel 160 (Figure 3) is supported upon chair
5 frame 5 by a pair of e,~le"sible pantograph leg rest linkage assemblies 162, an
example of which is clearly illustrated and described in the U.S. Patent No. 3,588,170
to E. M. Knabusch et al., issued June 28, 1971 for "Motor-Operated Reclining Chair",
It is to be understood that pantograph linkages 162 are applied to both lateral
10 sides of chair frame 5 but since both are exactly alike, only one will be described
hereinafter with much detail.
As is generally known, pantograph linkages 162 are operably suspended
from a square drive shaft 15 which extends transversely to chair frame 5 and is
supported between chair frame side members 140 for rotational movement relative
15 thereto. An L-shaped drive bracket 164 (Figure 2) is coupled for rotation with drive
shaft 15 and includes a down-turned operating arm 166. An actuating or long drive
link 168 of pantograph linkage 162 is pivotally secured about a pivot 170 to a lower
end of arm 166, with the opposite end of drive link 168 being pivotally secured about
a pivot 172 to a link 174. Link 174 is pivotally secured about a pivot 176 to a link 178
20 which, in turn, is pivotally secured about a pivot 180 to the front portion of a mounting
bracket 182, one of which is mounted near each lateral end of leg rest panel 160. A
pivot 184 secures one end of link 186 to the rear portion of mounting bracket 182
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while its opposite end is pivotally secured about a pivot 188 to a link 190 which, in
turn, is pivotally secured to a front bracket (not shown) that is supported from top rail
146 of chair frame 5 about a pivot 192. In addilion, link 186 is also secured to an
intermediate portion of link 174 by a pivot 194, while long drive link 168 is joined to link
190 by a pivot 196. A brace or "spacing" link 198 having a central strengthening rib
200 is pivotally secured at one end to the front bracket at pivot 192 and is journally
connected at its opposite end to square drive shaft 15. In operation, brace links 198
prevent any substantial bending of square drive shaft 15 during operation of camguide 130 when leg rest assembly 13 is being ~ctl~ted.
With particular reference to Figures 4 through 6, reclining linkage
assembly 134 is shown which is operable for causing reclining angular movement
between seat frame 11 and seat back 9. In general, reclining linkage assembly 134
includes a pair of laterally-spaced front swing linkages 204 and a pair of laterally-
spaced rear swing linkage 206. More particularly, each front swing linkage 204
includes a pivot 208 associated with plate bracket 150 which supports an S-shaped
link 210, the lower end of which is pivotally secured about pivot 208 to a first end of
link 212. The opposite end of link 212 is pivotally connected at pivot 214 to a lower
end of link 216. While not shown, an intermediate portion of link 216 is pivotally
secured to a pivot bracket attached to a forward upper surface of side rail 45 of upper
frame member 33. The upper end of link 216 is pivotally connected to one end of J-
shaped toggle link 218 with the opposite end of J-shaped toggle link 218 being
pivotably connected to L-shaped bracket 164 which, as noted, is secured for rotation
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with square drive rod 15. In addition, the upper end of S-shaped links 210 are pivoted
on pins 220 on left and right side rails 395 of seat frame 11. In operation, theeraclion between the various links associated with front swing linkages 204 cause
rearward tilting of chair frame 5 about pivots 154 relative to lift base assembly 1 upon
extension of leg rest assembly 13. More particularly, upon drive shaft 15 being
rotatably driven in a counterclockwise direction, link 216 pivots on the pivot bracket
to cause link 212 to drive the front of chair frame 5 upwardly and rearwardly.
As previously noted, reclining linkage assembly 134 also includes a pair
of rear swing linkage 206 each having a seat bracket 224 secured to each of seatframe side rails 222 near the rear end thereof. Bracket 224 has an upwardly
extending rear portion 226 and a downwardly extending forward portion 228. An S-shaped link 230 is pivotally secured about a pivot 232 to upstanding rear portion 226
and a link 234 is pivotally secured about a pivot 236 to downwardly extending forward
portion 228, the structure being generally similar to that illustrated and described in
the above-mentioned U. S. Patent No. 3,588,170.
An arm link 239 is secured to uprights 142 of chair frame 5 by screws,
rivets or any other reliable securing means. In addition, the upper ends of S-shaped
links 230 are pivotably secured to arm links 239 about pivot 240 such that when slide
brackets 242 secured to back frame 9 are slidably mounted on the upper end of S-shaped links 408, seat back 9 is pivotably movable relative to uprights 142. With this
arrangement, seat back frame 9 is supported for forward and rearward reclining
movement within chair frame 5. The lower end of S-shaped link 230 is pivotally
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secured about a pivot 244 to an offset link 246, the opposite end of which is coupled
to a tubular crossbar 248 and to which the opposite end of link 234 is pivotallysecured. It is to be understood that similar linkages 234 and 246 associated with the
opposite lateral side of seat frame 9 are likewise secured to the opposite end of
crossbar 248. A spring member 250 is attached between an underside surface of side
frames 222 of seat frame 11 and cross rail 144 of chair frame 5 for normally biasing
rear swing linkage 206 toward the upright position (Figure 3).
In accordance with the preferred construction of multi-function power-
assisted chair 3, lift and tilt mechanism 97 includes tall L-shaped pivot brackets 252
that are located on opposite sides of screw shaft 129 and rigidly secured to a top
surface of cross piece 103 of lower lift bar member 99. Moreover, L-shaped pivotbrackets 252 are laterally spaced to permit cam guide 130 to move linearly (fore and
aft) therebetween and are each formed to include a set of aligned elongated slots 254.
A rigid top plate 253 is secured between L-shaped pivot brackets 252 for maintaining
the lateral spacing therebetween. A rigid torque tube 256 is provided which extends
transversely between side legs 87 of U-shaped upper tilt bar member 89. Torque tube
256 is located in close proximity to front cross piece 91 for defining the pivot point
about which the upper ends of reinforcement brackets 113 are pivotally secured.
Guide pins 258 are fixed to opposite transversely extending boss portions 260 of cam
guide 130 so as to project through slots 254 in L-shaped pivot brackets 252. As
noted, screw shaft 129 extends through and drives internally threaded cam guide 130
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such that cam guide 130 moves forwardly or rearwardly along the length of screw
shaft 129 upon rotalion thereof in response to selective eneryi~aLion of motor 121.
As will be apprec;dled, and with particular reference to Figure 3, when
chair 3 is in the "normal" seating (i.e., lowered and upright) position, cam guide 130
5 is positioned near a central portion of screw shaft 129. Lifting and tilting of chair 3 is
accomplished by selectively energizing motor 121 to rotate screw shaft 129 in a first
direction for drawing cam guide 130 rearwardly toward motor 121. Following a slight
amount of initial rotation of screw shaft 129, guide pins 258 on cam guide 130 engage
the rearward end stop surfaces of slots 254 such that continued rotation of screw
10shaft 129 causes lower lift bar member 99 to pivot upwardly about pivots 105 for
moving chair frame 5 to the raised and forwardly tilted position shown in Figure 4.
Obviously, rotation of screw shaft 129 in the opposite or second direction will return
chair 3 from the lifted and forwardly tilted position of Figure 4 to the lowered upright
position of Figure 3.
15Another unique feature of the present invention encompasses elimination
of a "power pinch" condition upon a foreign object or resistances encountered by
upper frame member 33 as it is lowered. More particularly, the mechanical interaction
of cam guide 130 with lift and tilt mechanism 97 is such that guide pins 258 are free
to move forwardly in slots 254 when an obstruction is encountered upon lowering
20 chair frame 5 for eliminating the "power pinch" condition.
With particular reference now to Figures 5, 6 and 7, means are provided
for seléctively actuating leg rest assembly 13 and reclining linkage assembly 134 upon
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selective continued rotation of screw shaft 129 in the second direction. In general, leg
rest ~c"~wer assembly 136 and recliner follower assemL,ly 138 are concenl,icallymounted for independent pivotable movement on torque tube 256. Leg rest followerassembly 136 is adapted to rotate drive shaft 15 for causing power-assisted actuation
of leg rest pantograph linkages 162. Likewise, recliner follower assembly 138 isadapted to drive (i.e., "pull") crossbar 248 for causing power-assisted actuation of
reclining linkage assen,bly 134. Leg rest follower assembly 136 is shown to include
a first tubular sleeve 260 concentrically supported on torque tube 256 and on which
is secured a first cam lever 262 and a first cam link 264. First cam lever 262 and first
cam link 264 are rigidly secured to first tubular sleeve 260 such as by welding and a
spacer bar 266 is provided therebetween for supplying additional rigidity. Attached
to an upper end of first cam lever 262 is a follower member, such as nylon roller 268,
that is adapted to rollingly engage a first cam surface 270 formed on an undersided
surface of cam guide 130 and which is generally ~dj~cent to a front transverse end
272 thereof.
First cam link 264 is pivotally connected at its upper end to a first end
of toggle link 274, the opposite end of which is connected to a drive link 276. Drive
link 276 is coupled to drive shaft 15 for rotation therewith. As such, leg rest follower
assembly 136 is designed to interact with first cam surface 270 of cam guide 130 for
selectively actuating leg rest pantograph linkages 162 by causing rotation of drive
shaft 15. More particularly, as cam guide 130 moves forwardly on screw shaft 129,
first cam surface 270 engages first roller 268 such that first cam link 264 is forwardly
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pivoted on torque tube 256 for causing a corresponding amount of angular movement
of drive shaft 15 which, in turn, causes pantograph linkages 162 to extend.
Furthermore, a pair of laterally-spaced springs 280 are provided which interconnect
each pantograph linkages 162 to a bracket 282 rigidly supported from rear cross
5 frame 49 for normally biasing leg rest assembly 13 toward its retracted or "~lored
position. Thus, once first cam surface 270 disel,gages first follower 260 upon
reversing the rotation of screw shaft 129, springs 280 act to forcibly urge leg rest
assembly 13 to return to its "stored" position which, in turn, causes a cor,esponding
amount of angular movement of drive shaft 15. As such, since leg rest follower
assembly 136 is coupled for rotation with drive shaft 15, springs 280 are further
adapted to bias leg rest follower assembly 136 toward the non-engaged positions
shown in Figure 3.
As noted, recliner follower assembly 138 is also installed concentrically
about torque tube 256 and includes a second cam lever 284, a second tubular sleeve
286, a second cam link 288 and a second spacer bar 290. A second roller 291 is
supported from second cam lever 284 and is adapted to rollingly engage a second
cam surface 292 formed on the right half underside surface of cam guide 130.
Second cam surface 292 is located sufficiently rearward of first cam surface 270 to
permit full extension of leg rest asse,nbly 13 prior to initiation of any reclining
20 movement. This orientation of first cam surface 270 relative to second cam surface
292 is clearly illustrated in reference to Figure 5. The upper end of second cam link
288 is pivotally connected to an attach link 294 provided for connecting second cam
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link 288 to tubular cross bar 248. As such, second cam surface 292 acts on second
follower 291 of recliner follower assembly 138 for moving cross bar 248 forwardly in
response to such forward movement of cam guide 130. As will be appreciated,
movement of cross bar 248 c~uses cGr,es~.ondi,ly movement of reclining linkage
5 assembly 134 for moving chair 3 to the fully "reclined" position of Figure 6. In ~d~ lition,
one end of a spring link 296 is interconnected to second cam link 288 with its other
end secured to one end of a spring member 298. The other end of spring member
298 is supported from a bracket 300 that is rigidly secured to cross rail 49 of upper
frame member 33. Thus, spring member 298 is provided for urging second cam link
288 and, in turn, recliner follower assembly 138 rearwardly so as to bias reclining
linkage 134 and, in turn, seat assembly 8 toward the "upright" position. Therefore,
recliner follower assembly 138 is also adapted to provide spring-biased return means.
In operation, when a hand-operated control device (not shown) is
selectively operated by the seat occupant to energize motor 121 for rotalably driving
15 screw shaft 129 in the first direction, chair 3 moves from the "normal" position shown
in Figure 1A to the forward "lifted" position shown in Figure 1B. More particularly,
rotation in the first direction causes cam guide 130 to move rearwardly toward motor
121 such that guide pins 258 engage the rear stop surfaces of slots 254 for pivoting
lift and tilt mechanism 97 in the manner heretofore described. As is apparent,
20 selective rotation of screw shaft 129 in the second opposite direction c~uses chair 3
to be lowered for returning to the normal seating position of Figure 1A. However, in
accordance with the teachings of the present invention, continued rotation of screw
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Al lO..i:-Y LOChtl: 1202-000~6CPf
shaft 129 in the second direction causes continued forward movement of cam guide
130 relative to screw shaft 129. Thus, guide pins 258 move forwardly through slots
254 until first cam surface 270 formed on the underside of cam guide 130 engages
first roller 268 on first cam lever 262 of leg rest follower assembly 136. Continued
5 forward movement of cam guide 130 acts to pivotably drive leg rest foilower assembly
136 about torque tube 256, in opposition to the biasing of springs 280, such that first
cam link 264 drives toggle link 274 which, in turn, drives connector link 276 for rotating
drive shaft 15. In this manner, pantograph leg rest linkages 162 are protracted to their
fully extended position of Figure 5. To inhibit excessive bending of screw shaft 129
10in response to engagement of cam guide 130 with follower assemblies 136 and 138,
a wear pad 257 is secured to top plate 253 which is sized to provide a clearance with
a top surface of cam guide 130. Preferably, wear pad 257 is made of a low-friction
material which promotes sliding movement of cam guide 130 upon engagement
therewith.
15Adjacent first cam surface 270 is a generally planar surface 302 upon
which first roller 268 continues to ride during continued forward movement of cam
guide 130 following complete extension of leg rest assembly 13. This planar surface
302 permits continued forward movement of cam guide 130 without generating any
additional rotation of drive shaft 15. In operation, leg rest assembly 13 can be
20 returned to its retracted position by simply reversing the rotation of screw shaft 129
for moving cam guide 130 rearwardly so as to permit spring members 280 to
rearwardly rotate leg rest follower assembly 136 and, in turn, cause concurrent rotation
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of drive shaft 15. In this manner, the present invention includes spring-biased return
means instead of power return typically associated with conventional power-assisled
chair units. This is desirable in that this spring-biased return means generates a
significantly reduced return force as compared to systems having a power return
5 feature while eliminating the possibility of "power pinch" conditions.
Following full extension of leg rest assembly 13 in the manner desc, ibed,
continued forward movement of cam guide 130 causes engagement between second
roller 291 of recliner follower assembly 138 and second cam surface 292. Such
engagement acts to forwardly pivot second cam link 288 which, in turn, forwardly
drives (i.e. pulls) tubular cross bar 248 via connector link 294 for actuating rear swing
linkage 206 and front swing linkage 204, whereby chair 3 is moved to a reclined
position. Preferably, a slight amount of linear disrl~cement of cam guide 130 along
screw shaft 129 is provided between the end of the point of contact of first follower
268 with first cam surface 270 and the beginning of contact by second follower 291
with second cam surface 292 such that the seat occupant may fully extend leg rest
assembly 13 withcut initiating reclining movement.
To effectively limit the range of motion of power-assisted chair 3, switch
means are provided at the forward and rearward ends of screw shaft 129 for
terminating rotation thereof. As shown in Figure 3, a limit switch 310 is provided which
is adapted to contact a portion of cam guide 130, such as pin 258, for terminating
rotation of screw shaft 129 once cam guide 130 has moved forwardly to a position
defining the fully reclined seating position with leg rest assembly 13 also being fully
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Al IO...:-Y DOCKET: 1202-000/6CPF
extended (Figure 6). Similarly a rear limit switch 312 is provided to define a " ,axi" ,um
forward tilted position for lift and tilt linkage 97.
As will be apprec;aled the present invention can be easily modified to
include one or both of leg rest and reclined follower asse"~L.lies 136 and 138
5 respectively. As shown ~Gtu~fion is preferably sequential when both follower
assemblies are utilized. As such it is possible to manufacture various combinations
of power-assisted chair 3 by simply eliminali,1g one of the respective follower
assemblies or rendering one of the follower assemblies inoperative. Furthermore
linear actuation drive mechanism 132 is adapted for simple installation into
10 conventional manually actuated drive systems without a significant number of new
parts or design changes being required.
With particular reference now to Figures 8 and 9 an aller"ali~re
construction for the leg rest follower assembly is shown which is identified by
reference number 136'. In general the modified construction is substantially similar
15 to leg rest follower assembly 136 with the exception adjustment means are now
provided for per"lilling the fully extended leg rest position to be simply and accurately
set (i.e. "calibrated~) during final assembly of chair 3 and which practically eliminates
problems inherent with conventional linkage tolerance stack-ups. In addition the
adjustment means is also highly desirable in that in-service re-calibration of the
20 extended position for leg rest 13 can be quickly accomplished without the requirement
of replacing or reworking any linkages. Due to the similarity of several components
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of leg rest follower assembly 136' to those previously described, like numbers
are used to designate like components.
In general, the adjustment means associated with modified leg rest
follower assembly 136' includes a two-piece first cam link 320 having a fixed
member 322 secured to first tubular sleeve 260 and an adjustable member 324
pivotably coupled to a first end of toggle link 274. Fixed member 322 has an
elongated leg portion 326 that is adapted to be slidably disposed within an
open-channel portion of adjustable member 324. More specifically, the open
channel of adjustable member 324 is defined by a planar segment 328 and a
pair of laterally-spaced and transversely extending edge flanges 330 which are
adapted to retain leg portion 326 of fixed member 322 therein. An elongated
slot 332 is formed in planar segment 328 of adjustable member 324 and is
adapted to be adjustably alignable with a bore 334 formed in leg portion 326
of fixed member 322. A suitable fastener, such as a threaded bolt 336, is
adapted to extend through bore 334 and slot 332 and is releasably retained
therein by a suitable locking member, such as nut 338. To provide additional
rigidity, drive link 276 has a square tubular sleeve 340 fixed (i.e., welded)
thereto that is aligned with a square aperture (not shown) formed in drive link
276 and through which drive shaft 15 extends. A pair of set screws 344 are
retained within threaded bores formed through tubular sleeve 340 and which are
adapted to lockingly engage an outer surface of drive shaft 15 for fixing the
orientation of drive link 276 relative to drive shaft 15.
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During final assel,lbly of chair 3, the second end of toggle link 274 is
coupled to drive link 276. Thereafter, adjustable member 324 is slidably inserted over
fixed member 322 such that leg portion 326 is retained between end flanges 330 and
against planar segment 328. Next, leg rest follower assembly 136' is pivoted forwardly
5 to rotate drive shaft 15 until pantograph linkages 162 are adequately extended for
positioning leg rest frame board 160 at the desired elevated position. Following this
calibration step, threaded bolt 336 is inserted through the aligned bore 334 and slot
332, and nut 338 is sufficiently tightened thereon to releasably secure adjustable
member 324 to leg portion 326 of fixed member 322. Thus, this arrangement
10 eliminates the inherent problems encountered with typical tolerance stack-ups between
the various links of pantograph linkages 162 as well as inaccuracies in the initial
angular relationship between drive shaft 15 and first follower 268. Moreover, such an
arrangement f~ciiil~les easy in-service re-calibration of the elevated position of frame
board 160 by simply re-adjusting the relationship between fixed member 322 and
15 adjustable member 324. Moreover, such in-service re-calibration, which may be
necessitated due to sagging of frame board 160 from worn pivotal connections
between the various moving linkages, can be accomplished without the requirement
of disassembling chair 3 and replacing pantograph linkages 162.
With particular reference now to Figures 10 and 11, an alternative
20 preferred construction for the linear actuation drive mechanism is shown and identified
by reference numeral 132'. In general, linear ~ctu~tion drive mechanism 132' is similar
in function and structure to linear actuation drive mechanism 132 with the exception
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A I I O. .;:-Y DOCKET: 1202~6CPF
that cam guide 130 is now a multi-piece assei"uly. Accordingly, due to the similarity
of several co" " o"ents of linear ~ctu~tion drive mecl ,a";sr" 132' to those components
previously desc,iL,ed in rererel)ce to linear actuation drive mechanism 132 like
numbers are used hereinafter to designate like components. Thus it will be readily
5 understood from the following disclosure that linear ~ctu~tion drive mecl ,a"is,n 132'
can be incorporated into power-assisted chair 3 for permitting selective movement
thereof to the various operative positions shown in Figure 1A through 1 D.
In general linear actuation drive mechanism 132' is operable for
selectively actuating reclining linkage assembly 134 leg rest assembly 13 and lift and
tilt mechanism 97 utilizing a single electric motor 121 and an internally threaded driven
member hereinafter lead screw nut 350. Moreover screw shaft 129 extends through
and drives the inler"ally threaded lead screw nut 350 such that lead screw nut 350
moves forwardly or rearwardly (i.e. "fore and aft") along the length of screw shaft 129
upon driven rotation of screw shaft 129 in one of the first and second positions. As
15 previously disclosed rotaliGn of screw shaft 129 in the first direction results in linear
movement of lead screw nut 350 toward motor 121 while rotation in the second
direction results in linear movement of lead screw nut 350 away from motor 121. As
further noted the particular direction and amount of rotation of screw shaft 129 can
be controlled by selectively energizing motor 121 via a hand-held control device (not
20 shown).
With continued referel ,ce to Figures 10 and 11 a leg rest cam block 352
is shown to be pivotably fixed to one lateral edge of lead screw nut 350. Leg rest cam
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block 352 is further shown to include a first cam surface 354 formed on an underside
surface thereof that is adapted for engagement with first roller 268 of leg rest follower
assembly 136'. Similarly, a recliner cam block 356 is shown to be pivotably fixed to
the opposite lateral edge of lead screw nut 350 and has a second cam surface 358formed on an undel :,ide surface thereof which is acJa~led for ei ,yayel "ent with second
follower 291 of recliner follower assembly 138. Thus, forward linear movement of lead
screw nut 350 relative to screw shaft 129 is operable for causing leg rest cam block
352 to engage and pivotably displace leg rest follower assembly 136' for actuating leg
rest assembly 13 in a manner substantially identical to that disclosed above.
Furthermore, continued forward linear movement of lead screw nut 350 on screw shaft
129 is adapted to cause recliner cam block 356 to engage and pivotably ~ispl~ce
recliner follower assembly 138 for actuating recliner linkage 134 in a substantially
identical manner to that disclosed above. While not critical to the operation of linear
actuation drive mechanism 132', it is preferaLle that both leg rest cam block 352 and
recliner cam block 356 be fabricated from a rigid plastic material such as, for example,
nylon or the like.
As will again be appreciated, the use of a single power-assisted drive
system, such as linear actuation drive mecl ,anisln 132', provides a simple yet effective
means for selectively lifting and tilting chair 3 (via lift and tilt mechanism 97), extending
and retracting leg rest assembly 13 (via leg rest follower assembly 136'), and angularly
moving seat back 9 and seat 11 of seat assembly 8 between an "upright" and a
"reclined" position (via recliner follower assembly 138). In essence, leg rest cam block
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352 and recliner cam block 356 are adapted to provide the "cammi"g" functions
previously associated with cam surfaces 270 and 292, respectively, of cam guide 130.
However, due to the pivotable interconnection between each cam block and lead
screw nut 350, bending loads exerted by lead screw nut 350 on threaded screw shaft
5 129 during linear movement thereof are significantly minimized. Moreover, the use of
separate cam blocks 352 and 354 provides a simple arrangement for manufacturing
various combinations of power-assicte~ chairs 3 by using one or both of leg rest cam
block 352 and recliner cam block 356. Furthermore, in-service repair or replacement
of one of the cam blocks can be accomplished without removing motor assembly 121
such that lead screw nut 350 need not be removed from screw shaft 129.
According to the modified construction shown in Figures 10 and 11, lift
and tilt mechanism 97 now includes a pair of laterally-spaced L-shaped pivot brackets
360 (which are similar in function and structure to pivot brackets 252) that are located
on opposite sides of screw shaft 129 and rigidly secured to a top surface of cross
piece 103 of lower lift bar member 99. L-shaped pivot brackets 360 are laterally
spaced to permit and guide the linear movement (fore and aft) of lead screw nut 350
therebetween and are formed to each include an elongated slot 254. In addition, a
rigid cross rail 362 is secured between a forward end of pivot brackets 360 for
maintaining the lateral spacing therebetween. As noted, leg rest cam block 352 is
20 pivotably secured to one lateral side of lead screw nut 350 while recliner cam block
356 is pivotably secured to the other lateral side thereof. As will be described, both
cam blocks are adapted to move linearly in concert with lead screw nut 350 upon
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Al lO.~ Y DOCKET: 1202-000/~CFI;
rotation of screw shaft 129 in response to selective actuation of motor 121. In
operation, first cam surface 354 of leg rest cam block 352 is engageable with first
roller 268 of leg rest follower assembly 136' for causing corresponding angular
movement of drive shaft 15 which, in turn, results in a cor,es~.onding amount of
5 exle,)sil,le movement of leg rest pa"loy,d~l, linkages 162. Similarly, second cam
surface 358 of recliner cam block 356 is engageable with second roller 291 of recliner
follower assembly 138 for causing corresponding movement of reclining linkage 134
and, in turn, a corresponding amount of "reclining" movement of seat asse"~L,ly 8.
As best seen from Figure 11, leg rest cam block 352 is positioned
10 adjacent an outer lateral surface of one of L-shaped pivot brackets 360 and is
pivotably fixed to the corresponding lateral edge of lead screw nut 350 via a first guide
pin 362a. More specifically, guide pin 362a extends through a non-threaded bore 364
formed through leg rest cam block 352 and through slot 254 in L-shaped pivot bracket
360 such that a threaded portion 366a thereof is threaded into a thread bore (not
15 shown) formed in one lateral edge of lead screw nut 350. Preferably, leg rest cam
block 352 is journally supported for pivotable movement on a non-threaded portion
368a of first guide pin 362a. Moreover, an outwardly extending transverse flange
segment 370 formed at the uppermost portion of pivot bracket 360 is adapted to be
slidably engageable with an upper planar surface 372 of leg rest cam block 352 so
20 as to limit pivotable movement thereof during linear movement. In addition, flange
segment 370 is also adapted to maintain alignment of leg rest cam block 352 upon
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A I I O. .i: Y DOCKET: 1202~ 6CPF
linear movement thereof and particularly upon engagement with first roller 268 of leg
rest follower assembly 136'.
Similarly, recliner cam block 356 is positioned ~ cent an outer lateral
surface of the other one of L-shaped pivot brackets 360 and is pivotably fixed to the
cor~espo"ding lateral edge of lead screw nut 350 via a second guide pin 362b. Guide
pin 362b extends through a non-threaded bore 374 formed through recliner cam block
356 and through slot 254 in the corres~onding L-shaped pivot bracket 360 such that
a threaded portion 366b thereof is threaded into a threaded bore 376 formed in the
corresponding lateral edge of lead screw nut 350. Pl ereral,ly, a threaded insert 380
which is, for example made of brass, is molded into each lateral edge of lead screw
nut 350 for threaded receipt of guide pins 362 and 362b. Again, it is preferred that
recliner cam block 356 be journally supported for pivotable movement on a non-
threaded portion 368b of guide pin 362b. Moreover, the outwardly extending
transverse flange segment 370 formed on the pivot bracket 360 located ~dj-cent to
recliner cam block 356 is likewise adapted to be slidably engageable with an upper
planar surface 382 of recliner cam block 356 for maintaining alignment as well as
guiding linear movement thereof.
As will be appreciated, when chair 3 is in the "normal" seating (i.e.,
lowered and upright) position of Figure 1A and 3, lead screw nut 350 is positioned
near a central portion of screw shaft 129. Lifting and tilting of chair 3 is accomplished
by selectively energizing motor 121 via the hand-operated control device (not shown)
to rotate screw shaft 129 in the first direction for drawing lead screw nut 350
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A I I O. ..: Y DOCKET: 1 202-000 ~6CPF
rearwardly toward motor 121. Following a slight amount of initial rotation of screw
shaft 129, guide pins 362a and 362b engage the rearward end stop surfaces of slots
254 in pivot brackets 360 such that continued rolalio" of screw shaft 129 in the first
direction causes lower lift bar member 99 to pivot upwardly about pivots 105 for
5 moving chair frame 5 to the raised and forwardly tilted or "lifted" position shown in
Figures 1 B and 4. Again, subsequent rotation of screw shaft 129 in the opposite or
second direction will return chair 3 from the lifted and upwardly tilted position of Figure
4 to the lowered position of Figure 3.
In accordance with the teachings of the present invention, with chair 3
in the normal seated position of Figures 1A and 3, rotation of screw shaft 129 in the
second direction causes forward movement of lead screw nut 350 and, in turn, cam
blocks 352 and 356 relative to screw shaft 129. Thus, guide pins 362a and 362b
move forwardly through slots 254 until first cam surface 354 of leg rest cam block 352
engages first roller 268 on first cam lever 262 of leg rest follower assembly 136'.
15 Continued forward movement of léad screw nut 350 acts to pivotably drive leg rest
follower assembly 136' about torque tube 256 such that cam link 320 drives toggle link
274 which, in turn, drives connector link 276 for rotaling drive shaft 15. In this manner,
pantograph leg rest linkages 162 may be protracted to their fully extended position
of Figures 1C and 5. To inhibit excessive up/down bending of screw shaft 129 in
20 response to engagement of leg rest cam block 352 with leg rest follower assembly
136', leg rest cam block 352 is pivotably moveable about guide pin 362a relative to
lead screw nut 350 for maintaining sliding engagement between its top surface 372
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and flange segment 370 of pivot bracket 360. As such, the loading transferred
from leg rest cam block 352 to lead screw nut 350 and ultimately to screw
shaft 129 is significantly reduced. The pivotable relationship between recliner
cam block 356 and lead screw nut 350 is likewise adapted to minimize the
5 loading ultimately transferred to screw shaft 129 in a similar fashion. As noted,
leg rest cam block 352 and recliner cam block 356 are preferably made of a
low-friction material such as, without limitation, nylon or the like which
promotes smooth sliding movement thereof upon engagement with flange
segments 370. In order to provide further stability first and second gusset
members, 386 and 388, respectively, are welded to the lower portion of pilot
brackets 360. Gussets 386 and 388 prevent side deflection of pivot brackets
360, and therefore, prevent side-to-side deflection of screw shaft 129.
As seen from Figure 11, adjacent first cam surface 354 is a generally
planar surface 384 upon which first roller 268 continues to ride during
continued forward movement of lead screw nut 350 following complete
extension of leg rest assembly 13. This planar surface 384 permits continued
forward movement of leg rest block 352 without generating any additional
rotation of drive shaft 15. In operation, leg rest assembly 13 can be returned
to its retracted position by simply reversing the rotation of screw shaft 129 for
moving lead screw nut 350 and leg rest cam block 352 rearwardly so as to
permit spring members 280 to forcibly urge leg rest follower assembly 136 to
rotate rearwardly and, in turn, cause concurrent rotation of drive shaft 15. As
noted, such spring-biased return means generates a significantly reduced
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21442~5
A l l O, .i:-Y UOCr~t ~ 000~6CPF
return force as compared to systems having a power return feature while concurrently
eliminating the possibility of "power pinch" conditions.
Durir;g engage"~e,ll of first follower 268 with cam surface 354, second
follower 291 rides on a forward planar surface 390 located ~ cenl cam surface 358
5 and which permits a predelel")illed amount of forward linear movement of recliner
cam block 356 without generating pivotable movement of recliner follower assemLly
138. However, following full extension of leg rest assembly 13 in the manner
described, continued forward movement of lead screw nut 350 causes engagement
between second cam surface 358 of recliner cam block 356 and second roller 291 of
10 recliner follower assembly 138. Such engagement acts to forwardly pivot second cam
link 288 which, in turn, forwardly drives (i.e. pulls) tubular cross bar 248 via connector
link 294 for concurrently actuating rear swing linkage 206 and front swing linkage 204,
whereby chair 3 is moved toward the l'reclined" position of Figure 1 D. Preferably, a
slight amount of linear displacement of lead screw nut 350 along screw shaft 129 is
15 provided between the end of the point of contact of first follower 268 with cam surface
354 and the beginning of contact of follower 291 with second cam surface 358 such
that the seat occupant may fully extend leg rest assembly 13 without initiating reclining
movement.
To effectively limit the range of motion of power-assisted chair 3, switch
20 means are provided at the forward and rearward ends of screw shaft 129 for
terminating rotation thereof. As shown in Figure 10, a limit switch 392 is fixed to a
stationary portion of either chair frame 5 or base 1 and which is adapted to contact
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Al IO...:-Y DOCKET: 1202~u~oCPF
a portion of recliner follower asser"bly 138, such as link 288, for terminating rotation
of screw shaft 129 in the second direction once lead screw nut 350 has moved
forwardly to a position defining the fully "reclined" seating position with leg rest
assembly 13 also being fully extended (Figures 1A and 6). Similarly, rear limit switch
5 312 is provided to define a maximum forward tilted position for lift and tilt linkage 97.
As will be appreciated, both ,ure~rled embodiments of the present
invention can be easily modified to include one or both of leg rest and reclined
follower assemblies 136' (or 136) and 138, respectively. As shown, ~ctlJ~tion is
sequential when both follower assemblies are utilized. As such, it is possible to
10 manufacture various combination recliner chairs 3 by simply eliminating one of the
respective follower asser"blies, rendering one of the follower assemblies inoperative,
or eliminating one of the separate cam blocks. Furthermore, linear actuation drive
mechanis",s 132 and 132' are adapted for simple installation into conventional
manually actuated drive systems without a significant number of new parts or design
15 changes being required.
Chair 3 is especially useful for invalids since by pressing switches on the
hand-operated control device the seat occupant can change his position on the seat
to provide greater cGmro~ I when desired. If the disability of the occupant is such as
to render the occupant unable to reach switches mounted on the side of chair 3, it is
20 within the purview of the invention to provide a switch box which may rest on his lap
and be operated by the simple movement of a finger.
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Referring now to Figures 12 and 13, a metal, reinforcing attachment
plate 400 is shown for helping to secure the transverse pivot bracket member
71 and the pivot pin 105 to each wooden side rail 35. The attachment plate
400 comprises a first portion 402 and a second portion 404 which are
5 separated by a protruding portion 406. The portions 402 and 404 are secured
via a plurality of threaded screws 408 to the wooden side raii 35 to provide
even further added rigidity to the wooden side rail 35 between points 410 and
412 along the side rail 35. The protruding portion 406 allows a small degree
of clearance for the pivot pin. The pivot pin 105 further has an increase in
10 diameter of about 33 percent for added structural support of the side leg 101 on each side of the chair 3.
Referring now to Figure 14, an alternative preferred form of the side
leg 101 is shown. In this embodiment the side leg 101 includes an inner tubular
member 414 which is welded or otherwise securely fixed in place inside the side
15 leg 101. The inner tubular member 414 may vary in length but preferably
comprises a length of at least about two inches. The inner tubular member 414
further includes a pair of openings 416 in alignment with one another to allow
the pivot pin 105 to pass therethrough. Incorporating the inner tubular member
414 effectively doubles the cross sectional thickness of the side leg 101 which
20 allows each side leg to even better handle the stress and torque incurred during
operation of the chair 3. Most advantageously, this increase in strength is
accomplished without requiring the entire length of the side leg 101 to be
increased .
sc/lcd:s~ - 36
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Referring now to Figure 15, yet another structural improvement is
illustrated in the form of an angle bracket 418. The angle bracket 418 is adapted to
"cradle" or support a bolloi,l surface 33a of the upper frame member 33. With brief
rererence to Figure 16, the angle bracket 418 includes a first portion 420 and asecond ,uoi lion 422 extending generally perpendicularly from the first portion 420. The
first portion 420 is secured to the upper frame member 33 over the side plate 53 so
as to help "clamp" the side plate 53 to the upper frame member 33. The angle
bracket 418 is secured via conventional threaded screws 424 to the bottom surface
33a and a side surface 33b of the upper frame member 33. The angle bracket 418
thus even more securely supports the upper frame member 33 over simply using
threaded fasteners such as threaded screws only in the side surface 33b of the upper
frame member 33, and only through the side plate 53.
Referring now to Figure 17, an allernali~/e ,urefer,ed embodiment of the
spacer bars 266 and 290 and the nylon rollers 268 and 291 (Figure 7) is shown. The
modified spacer bars are designated by reference numerals 426 and 428. The
modified cam followers are designated by reference numerals 430 and 432. The
modified spacer bars 426 and 428 have each been lengthened by approxi,nalely 60
percent over the spacer bars 260 and 286, respectively, for significant added strength
and rigidity. Each of the modified spacer bars 426 and 428 is shorter, width-wise,
than their corresponding spacer bars 266 and 290 as shown in Figure 7. This
provides a greater lateral spacing between the cam followers 430 and 432 which in
turn allows wider cam followers 430 and 432 to be incorporated. The cam followers
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430 and 432 are approximately 10 percent to 15 percent wider than the rollers
268 and 291. This helps to reduce the stress on the cam followers 430 and
432 during operation of the chair 3.
Referring now to Figures 18 and 19, still another structural
enhancement is illustrated. A metal reinforcing member 434 is placed on one
side of each of the chair frame side members 140. A threaded bolt is then
placed through an opening 436 in each side member 140 to effectively clamp
a portion of a bracket used to interconnect the front portions 140a (Figure 18)
of the generally parallel disposed side members 140 together. In this manner
the stress on the side members 140 is reduced by the "clamping" action
effected by the metal reinforcing member 434.
Accordingly, those of ordinary skill in the art will appreciate that the
above-described structural reinforcing elements described in connection with
Figures 12-19 even further enhance the structural rigidity of the linear actuation
mechanism of the present invention.
Another feature of the present invention is the use of wax on any
wood surface which makes contact with any metal part. The use of wax has
been found to be effective in preventing "squeaks" which could otherwise
develop over time.
The foregoing discussion discloses and describes merely exemplary
embodiments of the present invention. One skilled in the art will readily
recognize from such discussion, and from the accompanying drawings and
claims, that various changes, modifications and variations can be made therein
without departing from the spirit and scope of the invention as defined in the
following claims.
sc/lcd:s~ ~ 38 -
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