U.S. patent application number 09/726135 was filed with the patent office on 2002-05-30 for height adjusting mechanism.
Invention is credited to Roark, Troy, Roslund, Richard N. JR..
Application Number | 20020063460 09/726135 |
Document ID | / |
Family ID | 24917386 |
Filed Date | 2002-05-30 |
United States Patent
Application |
20020063460 |
Kind Code |
A1 |
Roslund, Richard N. JR. ; et
al. |
May 30, 2002 |
HEIGHT ADJUSTING MECHANISM
Abstract
A height adjusting mechanism is connected between a rigid
upright extending upwardly from the seat assembly and an inner
shell of the back assembly. The height adjusting mechanism includes
a ratcheting latch which engages a vertically elongate rack to
maintain the back assembly at a selected elevation and a release
lever or cam which is connected to the catch and automatically
disengages the catch from the rack at the upper limit of travel of
the back assembly. The release cam continuously contacts the inner
shell of the back assembly and is deactivated merely by a short
upward shifting of the back assembly which thereby permits the pawl
to reengage the rack at any desired elevation. Accordingly,
reengagement of the pawl with the rack can be accomplished at any
point between the upper and lower limits of travel of the back
assembly.
Inventors: |
Roslund, Richard N. JR.;
(Jenison, MI) ; Roark, Troy; (West Olive,
MI) |
Correspondence
Address: |
FLYNN, THIEL, BOUTELL & TANIS, P.C.
2026 Rambling Road
Kalamazoo
MI
49008-1699
US
|
Family ID: |
24917386 |
Appl. No.: |
09/726135 |
Filed: |
November 29, 2000 |
Current U.S.
Class: |
297/353 |
Current CPC
Class: |
A47C 7/402 20130101 |
Class at
Publication: |
297/353 |
International
Class: |
A47C 007/40 |
Claims
What is claimed is:
1. A chair comprising: a base having an upright; a movable support
member which has an occupant supporting surface and is movable
vertically between upper and lower limits of travel to adjust a
height of the supporting surface; and a height adjusting mechanism
connected between said upright and said support member, said height
adjusting mechanism comprising a latch and a cam on one of said
upright and said support member and a vertical side wall and an
actuator member on the other of said upright and said support
member, said latch being movable toward and away from said side
wall between an engaged position and a disengaged position in which
said latch respectively engages and disengages said side wall to
prevent and permit downward movement of said support member, said
cam being moved from a standby position to an operative position by
said actuator member when said support member approaches said upper
travel limit such that said cam moves said latch to said disengaged
position and permits downward movement of said support member, said
cam being relatively movable along said side wall in contacting
relation therewith when said cam is in said operative position such
that upward movement of said support member at any point between
said upper and lower travel returns said cam to said standby
position to reengage said latch with said side wall.
2. The chair according to claim 1, wherein said cam is movable
vertically between said standby position and said operative
position, and said latch is movable sidewardly between said engaged
position and said disengaged position.
3. The chair according to claim 2, wherein said cam is pivotally
connected to said latch such that pivoting movement of said cam to
said operative position moves said latch away from said side wall
to said disengaged position.
4. The chair according to claim 2, wherein said side wall includes
a plurality of vertically spaced apart stops which are individually
engagable by said latch and further includes a vertically elongate
contact surface along which said cam slides, said cam and said
contact surface being in frictional contact which effects movement
of said cam to said standby position when said support member is
raised upwardly.
5. The chair according to claim 1, wherein said cam is a lever
which is pivotable about a pivot axis, said lever having a first
end on one side of said pivot axis which cooperates with said side
wall and a second end on the opposite side of said pivot axis which
cooperates with said actuator member.
6. The chair according to claim 5, wherein said cam is pivotally
connected to said latch by a pivot connection which defines said
pivot axis.
7. The chair according to claim 6, wherein said latch is pivotally
connected to said one of said upright and said support member.
8. In a chair having a base, a seat assembly and a back assembly
wherein said back assembly is connected to an upright which
projects upwardly above said seat assembly, said back assembly
being movable vertically between upper and lower limits of travel
to adjust a height thereof, a height adjusting mechanism connected
between said upright and said back assembly, comprising the
improvement wherein said height adjusting mechanism comprises a
plurality of stops on said back assembly, a latch supported on said
upright which is engagable with said stops to maintain said
occupant support surface at a selected elevation, said latch being
movable between an engaged position in engagement with said stops
and a disengaged position away from said stops which permits
lowering of said occupants support surface, and a movable actuator
member provided on said upright which is movable from a standby
position to an operative position to separate said latch from said
back assembly, said actuator member being in frictional contact
with an opposing contact surface of said back assembly such that
downward movement of said back assembly presses said actuator to
said operative position and upward movement of said back assembly
moves said actuator member to said standby position wherein said
back assembly is prevented from moving downwardly as soon as said
actuator member is returned to said standby position.
9. The chair according to claim 8, wherein said back assembly
includes an abutment which contacts said actuator member at said
upper travel limit to moves said actuator member from said standby
position to said operative position.
10. The chair according to claim 8, wherein said latch is pivotally
supported on said upright.
11. The chair according to claim 10, wherein said actuator member
is pivotally supported on said latch.
12. The chair according to claim 8, wherein said actuator member is
disposed between said latch and said stops when said actuator
member is in said operative position such that said latch member is
disposed in said disengaged position.
13. The chair according to claim 12, wherein said actuator member
includes a cam surface which contacts said contact surface of said
back assembly wherein said latch is moved to said disengaged
position by said actuator member.
14. The chair according to claim 8, wherein said actuator member
includes a first section connected to said latch and a second
section which abuts against said contact surface when in said
operative position such that said actuator member pushes said latch
to said disengaged position.
15. A chair comprising: a first chair component; a second chair
component, one of said first and second chair components being
slidably connected to the other of said first and second chair
components so as to be movable between an extended position and a
retracted position; and a height adjusting mechanism connected
between said first and second chair components, said height
adjusting mechanism including a latch on said first chair component
which is engagable with said second chair component wherein said
latch when engaged permits extension but prevents retraction of
said first and second chair components, said latch including a
pivoting cam thereon which is pivoted into engagement with said
second chair component to disengage said latch therefrom when said
first and second chair components are in said extended position,
said cam when engaged with said second chair component permitting
retraction and said cam being disengaged in response to extension
of said first and second chair components which thereby permits
reengagement of said latch with said second chair component.
16. The chair according to claim 15, wherein said one of said first
and second chair components is a back assembly and said other of
said first and second chair components is an upright.
17. The chair according to claim 16, wherein said first chair
component is said upright and said second chair component is said
back assembly.
18. The chair according to claim 15, wherein said latch is
pivotally connected to said first chair component.
19. The chair according to claim 15, wherein said latch engages a
vertical row of teeth on said second chair component, said cam
being slidable along an elongate contact surface extending along
said teeth.
20. The chair according to claim 15, wherein said latch includes a
biasing member which biases said latch into engagement with said
second chair component.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a height adjusting mechanism for an
office chair, and more particularly, to a height adjusting
mechanism which permits vertical adjustment of a back assembly of
the chair.
BACKGROUND OF THE INVENTION
[0002] Conventional office chairs have a seat assembly as well as a
back assembly which extends upwardly from a rear edge of the seat
assembly for respectively supporting the seat and back of the chair
occupant. The seat assembly typically supports a rigid upright and
the back assembly is supported on the upright. Also, such chairs
often include a pair of chair arms which extend upwardly from the
opposite side edges of the seat assembly for supporting the
occupant's arms.
[0003] To provide more comfortable office chairs, many of the chair
components are adjustable in various directions so that the
components of the chair more closely conform to and comfortably
support the seat, arms and back of the occupant. In this regard, it
is well known to provide a height adjusting mechanism in the back
assembly of the chair which permits the height of the chair to be
adjusted relative the to seat assembly. Height adjusting mechanisms
also are known to be provided in the chair arms to permit vertical
adjustment of the chair arm.
[0004] With respect to such height adjusting mechanisms and
primarily those height adjusting mechanisms used in the back
assembly, many of these mechanisms include ratchet-like mechanisms
having a vertically elongate row of teeth, which define a rack, and
a pawl which engages the rack. These ratchet mechanisms permit the
back assembly to be manually lifted upwardly along the upright
which mechanisms maintain the back assembly at a selected elevation
when the occupant releases the back assembly.
[0005] Many of these mechanisms include actuator parts such as
levers, pins and the like which act on the pawl when the back
assembly is at the upper limit of vertical travel to separate the
pawl from the rack and permit downward sliding, i.e. manual
lowering of the back assembly to a lowered position. Such height
adjusting mechanism includes further actuator parts at the lower
end of travel which automatically disengage the lever, pins or the
like to release or reset the pawl and permit the pawl to reengage
the rack. With such height adjusting mechanisms, however, it is
necessary to lower the back assembly to the lowermost position
before the pawl is reset, i.e. is able to reengage the rack, and
again permit upward adjustment of the height of the back
assembly.
[0006] It is an object of the invention to provide an improved
height adjusting mechanism which overcomes this and other
disadvantages associated with prior height adjusting
mechanisms.
[0007] The height adjusting mechanism of the invention is connected
between a rigid upright extending upwardly from the seat assembly
and an inner shell of the back assembly. The inventive height
adjusting mechanism includes a lever-like latch which engages a
vertically elongate rack to maintain the back assembly at a
selected elevation, wherein the teeth of the rack define a
plurality of incrementally spaced apart elevations. The latch is
pivotable outwardly away from the teeth in a ratcheting manner to
permit lifting of the back assembly upwardly to a selected one of
the predefined elevations at which the latch engages the rack to
maintain the back assembly at the selected elevation.
[0008] The latch further includes a release lever or cam which is
pivotally connected to the catch so as to move therewith. The cam
normally is in an inactive stored position which permits the latch
to ratchet along the rack. However, the cam is pivoted at the upper
end of travel of the back assembly toward the rack which causes the
latch to move in an opposite direction away from the rack to a
disengaged position which thereby allows lowering of the back
assembly.
[0009] The release cam continuously contacts the inner shell of the
back assembly during downward movement of the back assembly.
However, due to frictional contact between the cam and a rack
surface, the cam can be moved back to the stored position by a
short upward shifting or reversal of the back assembly such that
the latch reengages the rack. Accordingly, reengagement of the
latch with the rack can be accomplished at any point between the
upper and lower limits of travel of the back assembly. This thereby
eliminates the need to drop the back assembly to the lower limit to
reset the latch as is otherwise required in many known height
adjusting mechanisms.
[0010] Other objects and purposes of the invention, and variations
thereof, will be apparent upon reading the following specification
and inspecting the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a side elevational view of an office chair.
[0012] FIG. 2 is a side elevational view in partial cross-section
diagrammatically illustrating a height adjusting mechanism of the
invention connected between an upright of the seat assembly and an
inner shell of the back assembly.
[0013] FIG. 3 is a rear perspective view of the inner shell of the
back assembly.
[0014] FIG. 4 is a side elevational view in cross-section of the
inner shell as taken along line 4-4 of FIG. 3.
[0015] FIG. 5 is a front perspective view of the upright
illustrating a pair of bearings which mount to the upright for
connecting the height adjusting mechanism to the upright.
[0016] FIG. 6 is a front elevational view of the upright with the
bearings illustrated in phantom outline.
[0017] FIG. 7 is an exploded perspective view of the height
adjusting mechanism including the bearings.
[0018] FIG. 8 is a side elevational view of the height adjusting
mechanism.
[0019] FIG. 9 is a front elevational view of a latch of the height
adjusting mechanism.
[0020] FIG. 10 is a side cross-sectional view of the latch as taken
along line 10-10 of FIG. 9 with a cam lever connected thereto.
[0021] FIG. 11 is a partial side elevational view illustrating the
latch engaged with a rack on the inner shell.
[0022] FIG. 12 is a rear perspective view of the height adjusting
mechanism in the engaged position illustrated in FIG. 11.
[0023] FIG. 13 is a side elevational view with the back assembly at
the upper limit of travel wherein the cam lever is in a release
position and the latch is disengaged from the rack.
[0024] FIG. 14 is a rear perspective view of the height adjusting
mechanism in the disengaged position illustrated in FIG. 13.
[0025] FIG. 15 is a side elevational view of the height adjusting
mechanism near the lower limit of travel for the back assembly just
prior to reengagement of the latch with the rack.
[0026] Certain terminology will be used in the following
description for convenience in reference only, and will not be
limiting. For example, the words "upwardly", "downwardly",
"rightwardly" and "leftwardly" will refer to directions in the
drawings to which reference is made. The words "inwardly" and
"outwardly" will refer to directions toward and away from,
respectively, the geometric center of the arrangement and
designated parts thereof. Said terminology will include the words
specifically mentioned, derivatives thereof, and words of similar
import.
DETAILED DESCRIPTION
[0027] Referring to FIGS. 1 and 2, an office chair 10 is
illustrated which includes a seat assembly 12 and a back assembly
14. The seat assembly 12 includes a generally L-shaped upright 15
which projects upwardly above the rear edge of the seat assembly 12
and supports the back assembly 14 thereon. A height adjusting
mechanism 17 is diagrammatically illustrated in FIG. 2 connected
between the back assembly 14 and the upright 15 wherein the height
adjusting assembly 17 is disengaged at an upper travel limit to
permit the back assembly 14 to be lowered and is reset at any
elevation between the upper and lower travel limits.
[0028] The office chair 10 includes a base 20 having a plurality of
legs 21 which extend radially outwardly from a lower end of the
vertical pedestal 22. The outer ends of the legs 21 include
conventional casters 23 which support the office chair 10 on a
floor or other similar surface.
[0029] The upper end of the pedestal 22 rigidly supports the seat
assembly 12 thereon. In particular, the seat assembly 12 includes a
horizontally enlarged seat cushion 24 which seat cushion 24
overlies and is supported on the pedestal 22 by a tilt control
mechanism 25. The tilt control mechanism 25 includes a control
housing 26 which is rigidly connected to the pedestal 22, and
furthermore supports the upright 15 which is pivotally connected to
the control housing 26.
[0030] The upright 15 is rigid and includes a generally horizontal
leg 28 and a generally vertical leg 29 as seen in FIGS. 2 and 5.
The front end of the horizontal leg 28 is pivotally connected to
the control housing 26 while the vertical leg 29 extends upwardly
from the rear end of the horizontal leg 28. The vertical leg 29 is
disposed rearwardly of the seat cushion 24 and supports the back
assembly 14 on the upper end thereof.
[0031] The pivotal connection of the upright 15 to the control
housing 26 thereby permits rearward tilting of the back assembly 14
relative to the seat assembly 12 by the chair occupant. With the
particular tilt control mechanism 25, the rear edge of the seat
assembly of 12 also pivots downwardly relative to the front edge
thereof.
[0032] Referring to FIGS. 1-4, the back assembly 14 includes a
vertically enlarged plastic inner shell 30 which is covered on the
front face 31 thereof by a cushion 32. The back face 34 of the
inner shell 30 is covered by a vertically enlarged plastic outer
cover 35 which completely covers the inner shell 30 and mates with
the back cushion 32 about the periphery thereof to provide a
finished appearance to the back assembly 14.
[0033] The lower end of the back assembly 14 includes a downward
opening pocket 36 which pocket 36 generally is defined between back
face 34 of the inner shell 30 and an opposing inner face of the
cover 35. The pocket 36 is adapted to receive the upper end of the
upright 15 therein wherein the upright 15 is inserted upwardly into
this pocket 36. As will be discussed in more detail hereinafter,
the back assembly 14 is slidable vertically along the upper end of
the upright 15 to permit adjustment of the height of the back
assembly 14 relative to the seat assembly 12.
[0034] The upper end of the upright 15 further includes the height
adjusting mechanism 17 which is provided to control adjustment of
the vertical height of the back assembly 14 and support the back
assembly 14 at a selected elevation. The height adjusting mechanism
17 is supported on a front face of the upright 15 and cooperates
with the back face 34 of the inner shell 30 to define a
ratchet-like connection therebetween.
[0035] More particularly with respect to the inner shell 30 (FIGS.
3 and 4), the inner shell 30 preferably has a molded one-piece
construction. The front face 31 has a generally conventional
ergonomic shape which curves rearwardly at the upper end thereof,
and curves forwardly along the opposite left and right side edges
thereof as generally illustrated in FIG. 4 and more specifically
indicated by the curved upper edge 38 of FIG. 3.
[0036] With respect to the back face 34, ribbing 41 is provided
thereon which projects rearwardly and defines a plurality of
horizontal and vertical ribs that strengthen the inner shell 30.
The ribbing 41 further includes a plurality of cylindrical fastener
pockets 42 which open rearwardly and are provided to permit
securement of the outer cover 34 to the back face 33.
[0037] The ribbing 41 further defines the pocket 36. More
particularly, the ribbing 41 includes a pair of vertically elongate
side walls 44 and an upper wall 45 which extends sidewardly between
the upper ends of the side walls 44. The inner shell 30 further
includes a vertical front pocket wall 46. Accordingly, the side
walls 44, the upper wall 45 and the front wall 46 thereby define
the pocket 36 which is vertically elongate and opens both
rearwardly and downwardly to permit the upright 15 to be slidably
inserted upwardly therein.
[0038] The inner shell 30 further includes a bottom shell wall 47
which generally encloses the bottom of the back assembly 14 but is
notched in the center area thereof to define a generally
rectangular lower opening 48 of the pocket 36.
[0039] To support the upright 15 within the pocket 36, the inner
shell 30 includes vertically elongate grooves 50 (FIGS. 3, 4, 11
and 12) which grooves 50 are defined on a rear side thereof by
upper and lower flanges 51-1 and 51-2. The flanges 51-1 and 51-2
project sidewardly from the side walls 44 and are strengthened by
gussets 52. The front face of each flange 51-1 and 51-2 further
includes arcuate projections 54 which are adapted to contact a back
side 56 of the upright 15 and minimize friction therebetween. The
side walls 44 also have additional arcuate projections 58 (FIGS. 4
and 13) which project inwardly from the side walls 44 and slidably
contact the respective side edge 59 of the upright 15.
[0040] To slidably support the front face 61 of the upright 15, the
front pocket wall 46 further includes pairs of ribs 62-1 and 62-2
which project rearwardly from the front pocket wall 46 and are
sidewardly spaced apart. The rear terminal edges of the ribs 62-1
and 62-2 include additional arcuate projections 64 which are
adapted to slidably contact the front the upright face 61 while
minimizing friction therebetween.
[0041] With this arrangement, the opposite side edges 59 of the
upright 15 are slidably received within the respective grooves 50
as more clearly illustrated in FIGS. 11 and 12. More specifically,
the grooves 50 effectively include upper groove sections 66, which
are defined by the upper flanges 51-1 and the upper pairs of ribs
62-1, and lower groove sections 67 (FIGS. 3 and 13), which are
defined by the lower flanges 51-2 and the ribs 62-2. However, the
upper groove sections 66 have a significantly longer vertical
length than the lower grooves section 67 such that the upright 15
is primarily supported by the upper groove sections 66.
[0042] To provide vertical support to the height adjusting
mechanism 17, the front pocket wall 46 further includes a plurality
of teeth 70. The teeth 70 define downward facing steps and are
disposed individually one above the other to define two parallel
vertical rows such that the two rows of teeth 70 effectively define
a rack 71. As generally illustrated in FIGS. 3 and 4, the rows of
teeth 70 are sidewardly spaced apart in parallel rows to define a
vertically elongate slot 73 therebetween having a slot face 74
which faces rearwardly toward the upright 15.
[0043] Additionally referring to FIGS. 3, 4 and 12, the inner shell
30 also includes a stop plate 75 which extends sidewardly between
the pocket side walls 44 and is disposed generally below the lower
end of the upper groove sections 66. The stop plate 75 has upper
stop edges 76 which define the upper limit of travel of the back
assembly, and an actuator block 77 which projects upwardly from the
upper stop edges 76 to actuate or more particularly disengage the
height adjusting mechanism at the upper travel limit and then
permit lowering of the back assembly 14.
[0044] Referring to FIGS. 5 and 6, the upright 15 is adapted to
support the height adjusting mechanism 17 thereon as described in
further detail hereinafter. The upright 15 is rigidly fastened to
the control housing 26 by a plurality of apertures 80 at the front
end of the horizontal leg 28.
[0045] The vertical leg 29 includes a support opening 82 near the
upper end thereof which is generally rectangular and opens
forwardly through the upright 15. The support opening 82 includes a
pair of bearing supports 83 each of which projects inwardly toward
each other from the opposite sides of the support opening 82.
Additionally, a downwardly extending notch 84 is provided directly
below one of the bearing supports 83 at a lower left corner of the
opening 82.
[0046] Turning to the height adjusting mechanism 17, this mechanism
generally includes: a pair of bearings 87; a rack-engaging latch 88
pivotally supported on the upright 15 by the bearings 87; and a
lever-like cam 89 which is pivotally supported on the latch 88 and
is operable to disengage the latch 88 from the rack 71 to permit
lowering of the back assembly 14.
[0047] Each of the bearings 87 (FIGS. 7 and 8) includes a generally
rectangular bore 91 that opens horizontally therethrough and is
slidably fitted onto the bearing supports 83 of the upright 15.
Since the bearing supports 83 and bores 91 have cooperating
rectangular shapes as generally illustrated in FIG. 8, the bearing
supports 83 are non-rotatable relative to the upright 15. To
provide tight-fitting engagement, each bore 91 preferably includes
a rib 91a on one side thereof.
[0048] Each bearing 87 has a generally circular outer support
surface 92, and a stop projection 93 that extends generally
tangentially from the support surface 92. The stop projection 93
defines a downward facing stop surface 94 in order to contact the
opposing stop edges 76 at the upper travel limit (FIGS. 13 and
14).
[0049] More particularly as to the latch 88, the latch 88 is
preferably a one-piece molded plastic part that is adapted to be
pivotally mounted to the upright 15 like a lever or pawl and
cooperate with the rack 71 in ratcheting engagement therewith. To
support the latch 88 on the upright 15, a pair of sideward opening
bearing seats 96 are provided on the opposite sides thereof.
[0050] Referring to FIG. 8, each bearing seat 96 has a generally
circular shape which is adapted to rotatably receive the bearing 87
therein. The bearing seat 96, however, is open on one side thereof
so that the latch 88 can be snapped rearwardly onto the bearing
seats 87 when the bearing seats 87 are fixed on the corresponding
bearing supports 83 on the upright 15. As result, the latch 88 is
pivotally supported on the upright 15 as generally illustrated in
FIGS. 11 and 12.
[0051] More particularly, the latch 88 further includes an upper
latch end 97 which projects upwardly and forwardly toward the rack
71. To resiliently bias the latch 88 toward the rack 71, the latch
88 includes a pair of spring slots 98 near the upper end thereof
which are adapted to receive the lower ends 99 of a U-shaped
biasing spring wire 100. The lower spring ends 99 hook into the
spring slots 98 wherein the spring 100 projects upwardly above the
latch 88.
[0052] After assembly, the spring 100 is disposed between the upper
latch end 97 and the front face 61 of the upright 15 whereby the
spring 100 presses rearwardly on the front upright face which
thereby biases the latch 88 forwardly into engagement with the rack
71. The engagement position for the latch 88 is illustrated in FIG.
11 whereby the latch 88 engages the rack 71. Accordingly, downward
movement of the back assembly 12 is prevented since a sidewardly
adjacent pair of the teeth 70 abut downwardly on the latch 88.
[0053] However, the spring 100 also is resiliently deflectable to
permit the latch end 97 to pivot outwardly away from the rack 71 as
the back assembly 14 and specifically, the inner shell 30 thereof
is moved upwardly. The latch 88 thereby slides relative to the
teeth 70 in a manner similar to a ratchet. This permits the back
assembly 12 to be raised to a new elevation merely by manually
lifting the back assembly 12.
[0054] The spring 100 also is sufficiently deflectable to permit
the latch 88 to be pivoted farther away from the rack 71 to the
fully disengaged position illustrated in FIG. 13. To define the
fully disengaged position, the latch 88 includes a stop finger 102
which projects downwardly therefrom and cooperates with the notch
84 defined in the upright 15.
[0055] To maintain the latch 88 in this fully disengaged position
and thereby permit the back assembly 12 to be manually lowered, the
cam 89 is provided which cam 89 is pivotally connected to the latch
88 as described hereinafter.
[0056] To support the cam 89, the latch 88 (FIGS. 9 and 10)
includes a lower rectangular opening 103 which includes a
horizontal axle 104 extending therebetween which axle 104 is
adapted to pivotally support the cam 89 thereon. The opening 103
further includes a pair of cylindrical lower stops or pins 105
which are disposed below the axle 104. Also, the bottom end of the
opening 103 is spanned by a wall 107 wherein an upper edge of the
wall 107 has a stop post 108 projecting upwardly therefrom.
[0057] Additionally, the latch 88 also includes an upper opening
110 which is disposed centrally between the spring slots 98. The
upper opening 110 includes a pair of upper stops or pins 111 which
project toward each other.
[0058] Turning to the cam 89, the cam 89, as illustrated in FIGS. 7
and 10, is formed as a molded one-piece plastic part which includes
a horizontal channel or slot 115 approximately midway along the
length thereof. The slot 115 is open along one side 116 so that the
slot 115 of the cam 89 can be snap fittingly connected to the axle
104 in pivoting engagement therewith. Preferably, the open side 116
opens rearwardly away from the rack 71.
[0059] The lower end 117 of the cam 89 projects downwardly between
the axle 104 and the pivot stops 105 on the latch 88. Additionally
the upper end 118 thereof projects upwardly so as to be disposed
vertically between the upper pivot stops 111 and the stop post 108.
In this orientation, the upper end 118 defines a forward facing cam
surface 119 and is generally L-shaped so as to project rearwardly
and define a terminal end 120.
[0060] With this arrangement, the cam 89 is pivotable or rotatable
about the horizontal axle 104 between a fully stored or a standby
position as illustrated in FIG. 10 and an operative position as
seen in FIGS. 13. When in the stored position of FIG. 10, the upper
stop pins 111 contact the distal cam end 120 while the lower stop
pins 105 abut against the lower end 117 of the cam 89. The cam 89
also is pivotable downwardly away from this position in the
direction of reference arrow 121 to the operative position wherein
the front face 122 of the cam 89 contacts and rests on the stop
post 108. The lower section of the front face 122 also defines a
contact surface 124 which is used to shift the cam 89 from the
stored position of FIG. 11 to the operative position of FIGS.
13-15.
[0061] Since the cam 89 is mounted generally at the center of the
latch 88, the upper end of the cam 89 and specifically, the
L-shaped section which defines the cam surface 119 fits into and
slides along the vertically elongate slot 73 that is defined
between the parallel vertical rows of rack teeth 70. Therefore,
while the latch 97 slides along the teeth 70 in operative
engagement therewith, the cam surface 119 slides along the slot 73
near the opposing slot face 74.
[0062] During assembly, the bearings 97 are first mounted on the
bearing supports 83 of the upright 15. Preferably, the latch 88,
spring 100 and cam 89 are preassembled. As such, the cam 89 is snap
fitted onto the axle 104 of the latch 88 while the lower ends 99 of
the spring 100 are engaged with the spring slots 98. This assembly
is then mounted onto the bearings 97 in snap fitting engagement
therewith so that this assembly is disposed within the opening 82
formed in the upright 15 and is pivotable about the horizontal
pivot axis 125 (FIG. 7) which extends horizontally between the axes
of the bearings 87. With this arrangement, the latch 88 and cam 89
are pivotally supported on the upright 15 as a unit. Further, the
cam 89 also is independently pivotable relative to the latch 88
about a pivot axis defined by the axis of the axle 104.
[0063] Once the back assembly 14 is mounted in place on the upright
15, the assembly is disposed within the pocket 36 formed in the
chair shell 30. Referring to FIGS. 11 and 12, the latch 88 is
biased forwardly by the spring 100 to the engagement positioned so
that the upper end 97 thereof is engaged with the rack 70. While
the cam surface 119 projects forwardly somewhat into the region of
the teeth 70, the cam 89 is in the stored position and thus, does
not interfere with or contact the teeth 70 since the upper end 118
slides vertically within the slot 73. As such, the resilient
deflection of the spring 100 permits the latch 88 to ratchet along
the teeth 70 as the back assembly 14 is manually lifted. Each tooth
70 defines a different elevation whereby the chair occupant can
manually set the elevation of the back assembly 14.
[0064] To permit lowering of the back assembly 14, the cam 89 is
adapted to cooperate with the actuator block 77 of the inner shell
30 when the back assembly 14 is at the upper limit of travel as
generally illustrated in FIGS. 13 and 14. In particular, the stop
surfaces 76 of the inner shell 30 contact the bearing projections
93 so that further upward movement of the back assembly 14 is
prevented thereby.
[0065] At this upper limit of travel, the actuator block 77
contacts the contact surface 124 on the cam 89 and thereby pivots
the cam 89 in a counterclockwise direction as indicated by
reference arrow 127. This counterclockwise movement of the cam 89
causes the upper cam end 118 to move forwardly into contact with
the opposing surface 74 of the slot 73. Specifically, the arcuate
cam surface 119 slidably contacts the slot surface 74. Since the
slot 73 cannot be displaced away from the upright 15 as the inner
shell 30 is fixed on the upright 15, this rotating movement of the
cam 89 causes the interconnected latch 88 to pivot in the opposite
direction away from the rack 71 to the fully disengaged position of
FIG. 13.
[0066] To maintain the cam 89 in this operative position, the cam
89 is rotated sufficiently so as to move over center such that the
spring force from the spring 100 that is transferred through the
interconnection of the latch axle 104 and cam 89 continues to urge
the cam 89 in the counterclockwise rotation. This counterclockwise
rotation, however, eventually is stopped by the stop post 108 on
the latch 97. Therefore, the cam 89 is maintained in the operative
position even when the actuator block 77 begins to travel
downwardly with the back assembly 14. Due to the frictional contact
between the opposing slot face 74 and the cam surface 119, the cam
89 continues to be urged in the counterclockwise direction during
downward movement of the back assembly 14.
[0067] To release the cam 89 and permit reengagement of the latch
88, the cam 89 can be simply pivoted counterclockwise to the
release position of FIG. 13 merely by shifting the back assembly 14
a short distance upwardly as generally illustrated in FIG. 15. In
particular, near the lower limit of travel illustrated in FIG. 15
or any point between the upper and lower limits of travel, the back
assembly 15 can be shifted upwardly as generally indicated by
reference arrow 130. Due to the frictional contact between the slot
face 74 and the cam surface 119, this upward shifting of the back
assembly 14 causes the cam 89 to now rotate clockwise as generally
indicated by reference arrow 131. Once the cam 89 is moved
counterclockwise past the over center point, then the constant
spring force from the spring 100 begins to urge the cam 89
clockwise rather than counterclockwise. Therefore the same spring
100 now acts to automatically return the cam 89 to the release
position. As can be appreciated, at any elevation during the
downward return stroke of the back assembly, the back assembly 14
can be reversed, i.e. shifted upwardly a short distance to
disengage the cam 89 and reengage or reset the latch 88 with the
rack 71. This allows the height of the back assembly 14 to be set
at a desired elevation as soon as the elevation is reached and
avoids having to return the back assembly 14 all of the way to the
lower limit of travel before the latch 88 is reset.
[0068] With the above-described arrangement, disadvantages
associated with prior art mechanisms are overcome.
[0069] In addition to the specific arrangement disclosed herein,
modified versions of this arrangement also can be provided. For
example, while the cam 89 is pivotally connected to the latch 88,
the cam 89 also could be slidably connected thereto or
independently slidably supported on the upright 15. Additionally,
while the latch 88 is a rotating lever, the latch 88 also could be
slidable, for example, horizontally toward and away from the rack
77 wherein a cam is provided to press the latch away from the
rack.
[0070] Additionally, these components can also be reversed in
position wherein the lever and latch assembly are provided on the
back assembly 14 while a rack is provided on the upright 15. Still
further, this arrangement could be applied to other occupant
supporting components of the chair 10 such as an armrest having an
upright support member and an arm housing.
[0071] Although a particular embodiment of the invention has been
disclosed in detail for illustrative purposes, it will be
recognized that variations or modifications of the disclosed
apparatus, including the rearrangement of parts, lie within the
scope of the present invention.
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