CN106235713B

CN106235713B - Chair arm assembly

Info

Publication number: CN106235713B
Application number: CN201610649777.XA
Authority: CN
Inventors: 罗伯特·J·拜蒂; 小理查德·N·罗斯兰; N·麦考恩; P·美杜
Original assignee: This Deere Koss Corp
Current assignee: This Deere Koss Corp
Priority date: 2012-09-20
Filing date: 2013-09-19
Publication date: 2019-12-20
Anticipated expiration: 2033-09-19
Also published as: CN108784085B; WO2014047255A3; CA2881887A1; MY169026A; MX2015003446A; CN108784085A; CN104661567B; CN106235713A; CN104661567A; MX376921B; AU2013318083B2; HK1206222A1; MX2022011894A; AU2013318083A1; JP6244364B2; JP2015529144A; WO2014047255A2

Abstract

A chair assembly comprising: a four-bar linkage assembly including a first link, a second link, a third link, and a fourth link, each pivotably coupled to one another such that the four-bar linkage assembly includes an upper end adjustable between raised and lowered positions; and an armrest assembly adapted to support a seated user's arm thereon and supported on the upper end of the four-bar linkage assembly; wherein the lower end of the four-bar linkage assembly is pivotally supported for pivotal movement from the arm support structure such that the upper end of the four-bar linkage assembly is movable between a first position and a second position laterally outboard of the first position.

Description

Chair arm assembly

The patent application is a divisional application; the original application date is 2013, 9, 19 and application number is 201380049111.5, and the invention is named as a chair arm assembly. The original application is an international application, the international application number is PCT/US2013/060560, the international application date is 9 and 19 days in 2013, and the date of entering the national phase of China is 3 and 20 days in 2015.

Technical Field

The present invention relates to a chair assembly, and more particularly to an office chair arm assembly that is vertically and horizontally adjustable and includes a pivotally and linearly adjustable arm cap assembly.

Disclosure of Invention

One aspect of the present invention is to provide a chair assembly comprising a 4-bar linkage assembly including a first linkage member having a first end and a second end, a second linkage member having a first end and a second end, a third linkage member having a first end pivotably coupled to the first end of the first linkage member for rotation about a first pivot point, a second end pivotably coupled to the first end of the second linkage member for rotation about a second pivot point, and a fourth linkage member having a first end pivotably coupled to the second end of the first linkage member for rotation about a third pivot point, and a second end pivotably coupled to the second end of the second linkage member for rotation about a fourth pivot point, wherein the 4-bar linkage assembly includes a lower end and an upper end that is adjustable between a raised position and a lowered position. The chair assembly also includes an armrest assembly adapted to support a seated user's arm thereon and supported at an upper end of the 4-bar linkage assembly, wherein a lower end of the 4-bar linkage assembly is pivotally supported by the arm support structure for pivotal movement about a fifth pivot point such that the upper end of the 4-bar linkage assembly is movable between a first position and a second position, the second position being laterally outboard of the first position.

Another aspect of the present invention is to provide a chair assembly including a 4-bar linkage assembly comprising: a first link member having a first end, a second end, and a U-shaped cross-sectional configuration disposed along a length thereof; a second link member having a first end, a second end, and a U-shaped cross-sectional configuration disposed along a length thereof, and wherein the first link member and the second link member cooperate to form an interior space extending longitudinally along the length of the first and second link members; a third link member having a first end pivotably coupled to the first end of the first link member for rotation about the first pivot point and a second end pivotably coupled to the first end of the second link member for rotation about the second pivot point; and a fourth link member having a first end pivotably coupled to the second end of the first link member for rotation about the third pivot point and a second end pivotably coupled to the second end of the second link member for rotation about the fourth pivot point; wherein the 4-bar linkage assembly includes a lower end and an upper end that is adjustable between a raised position and a lowered position. The chair assembly further includes an armrest assembly adapted to support a seated user's arm thereon, and supported at an upper end of the 4-bar linkage assembly, and a locking assembly including a first locking coupling having a first surface, and a second locking coupling having a plurality of teeth, the teeth correspond to a plurality of vertical positions of the 4-bar linkage between a raised position and a lowered position, wherein the first and second locking couplings are movable relative to each other between a locked position and an unlocked position, in the locked position, the first surface engages at least one of the plurality of teeth to prevent the 4-bar linkage from being adjusted between the raised and lowered positions, and in the unlocked position, the first surface and the plurality of teeth are spaced from one another, thereby allowing the 4-bar to be adjusted between raised and lowered positions, and wherein the first and second locking couplings each have at least a substantial portion located within the interior space.

Yet another aspect of the present invention provides a chair assembly comprising: an arm support structure; an armrest assembly adapted to comfortably support a seated user's arm thereon; an arm support assembly having a lower end supported by the arm support structure and an upper end supporting the armrest assembly thereon, wherein the arm support assembly is adjustable between a vertically raised position and a vertically lowered position; and a locking assembly. The locking assembly includes: a first locking link having at least one of a first surface and a plurality of teeth; a second locking link having a first surface and the other of the plurality of teeth, and being movable between a locked position in which the first surface engages at least one of the plurality of teeth to prevent the arm support assembly from being adjusted between the raised and lowered positions, and an unlocked position in which the first surface and the plurality of teeth are spaced apart from each other, thereby allowing the arm support assembly to be adjusted between the raised and lowered positions; an actuating link operatively coupled with the first locking link and adapted to move between first and second positions, in the first position the first locking link being moved to the locked position by the actuator link, in the second position the first locking link being moved to the unlocked position by the actuator link; and an actuator member operatively coupled to the actuator coupling, wherein at least a portion of the actuator member is actuatable by a seated user, thereby allowing the user to couple the actuator member between the first and second positions.

Another aspect of the invention is an armrest assembly for an office chair. The armrest assembly includes an outer member having a cushion mounted thereon, and an inner member configured to be secured to an office chair structure. The inner member has teeth disposed thereon. The armrest assembly also includes upper and lower members that extend between and pivotally interconnect the inner and outer members to form a 4-bar linkage. The armrest assembly also includes a vertical adjustment lock assembly to lock the height of the cushion relative to the inner member. The vertical adjustment lock assembly includes a movable release member and an actuator member that is displaced between locked and unlocked positions when the release member is moved. The actuator member defines a base end. The vertical adjustment lock assembly also includes a movable locking member with teeth that selectively engage the teeth on the inner member of the 4-bar linkage. A spring biases the actuator member toward the locked position and also biases the teeth of the pivotable locking member out of engagement with the teeth on the inner member of the 4-bar linkage. The base end of the actuator member moves into the first recess of the locking member to allow the teeth of the locking member to move out of engagement with the teeth of the inner member of the 4-link. The armrest assembly also includes a second lock with a locking second recess in the locking member that receives an end of the actuator member and prevents movement of the locking member when a downward force is applied to the cushion.

Yet another aspect of the present invention is to provide a chair assembly comprising a seat support structure including a seat support surface configured to support a seated user thereon, an armrest assembly including an arm support surface for supporting an arm of a seated user thereon, and an arm support assembly having an upper end supporting the arm support assembly at a higher vertical elevation than the seat support surface, and a lower end including a selected one of a pivot boss and a pivot aperture. The chair assembly further comprises an arm support structure including the other of a pivot boss and a pivot aperture, wherein the pivot boss is received in the pivot aperture to pivotably support the arm support assembly for rotation about a pivot point between a first position and a second position, the pivot boss having a conical shape, and wherein the aperture has a conical shape that closely corresponds to the shape of the pivot boss.

Another aspect of the present invention is to provide a chair assembly comprising: an arm support assembly having an upper end and a lower end; an armrest assembly adapted to support a seated user's arm thereon and supported on an upper end of the arm support assembly; and an arm support structure pivotally supporting the arm support assembly for pivotal movement about a substantially vertical axis such that the upper end of the arm support assembly is pivotable about the substantially vertical axis between a first position and a second position, the second position being laterally outboard of the first position. The chair also includes a seat support structure comprising a seat support surface configured to support a seated user thereon, wherein the seat support surface comprises a longitudinal axis, and wherein the upper end of the arm support assembly moves greater than or equal to about 22 ° outwardly from an axis parallel to the longitudinal axis of the seat support surface, and wherein the upper end of the arm support assembly moves greater than or equal to about 17 ° inwardly from the axis parallel to the longitudinal axis of the seat support surface.

These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.

Drawings

FIG. 1 is a front perspective view of a chair assembly embodying the present invention;

FIG. 2 is a rear perspective view of the chair assembly;

FIG. 3 is a side view of the chair assembly shown in a lowered position and in phantom in a raised position, and showing the seat assembly in a retracted position and in phantom in an extended position;

FIG. 4 is a side view of the chair assembly shown in an upright position and in phantom in a reclined position;

FIG. 5 is an exploded view of the seat assembly;

FIG. 6 is an enlarged perspective view of the chair assembly with a portion of the seat assembly removed to show the spring support assembly;

FIG. 7 is a front perspective view of the back assembly;

FIG. 8 is a side view of the backrest assembly;

FIG. 9A is an exploded front perspective view of the back assembly;

FIG. 9B is an exploded rear perspective view of the back assembly;

FIG. 10 is an enlarged perspective view of region X of FIG. 9A;

FIG. 11 is an enlarged perspective view of region XI of FIG. 2;

FIG. 12 is a cross-sectional view of the upper back pivot assembly taken along line XXII-XXII of FIG. 7;

FIG. 13A is an exploded rear perspective view of the upper back pivot assembly;

FIG. 13B is an exploded front perspective view of the upper back pivot assembly;

FIG. 14 is an enlarged perspective view of region XIV of FIG. 9B;

FIG. 15A is an enlarged perspective view of a comfort member and a lumbar assembly;

FIG. 15B is a rear perspective view of the comfort member and lumbar assembly;

FIG. 16A is a front perspective view of a pawl member;

FIG. 16B is a rear perspective view of the pawl member;

FIG. 17 is a partial cross-sectional perspective view taken along line XVIII-XVIII of FIG. 15B;

FIG. 18A is a perspective view of the backrest assembly with a portion of the comfort member cut away;

FIG. 18B is an exploded perspective view of a portion of the back assembly;

FIG. 19 is a perspective view of a control input assembly supporting the seat support plate thereon;

FIG. 20 is a perspective view of the control input assembly with certain elements removed to show the interior thereof;

FIG. 21 is an exploded view of the control input assembly;

FIG. 22 is a side view of the control input assembly;

FIG. 23A is a front perspective view of a back support structure;

FIG. 23B is an exploded perspective view of the back support structure;

FIG. 24 is a side view of the chair assembly showing its pivot points;

FIG. 25 is a side perspective view of the control assembly showing a plurality of pivot points associated therewith;

FIG. 26 is a cross-sectional view of the chair showing the backrest in an upright position with the lumbar adjustment set at a neutral setting;

FIG. 27 is a cross-sectional view of the chair showing the backrest in an upright position with the lumbar portion set to a flat configuration;

FIG. 28 is a cross-sectional view of the chair showing the backrest reclined, with the lumbar adjusted to a neutral position;

FIG. 29 is a cross-sectional view of the chair in a reclined position, wherein the lumbar support has been adjusted to a flat configuration;

FIG. 29A is a cross-sectional view of the chair showing the back reclined with the lumbar portion of the housing set to a maximum arc;

FIG. 30A is an exploded view of a moment arm shift assembly;

FIG. 30B is an exploded view of the moment arm shift drive assembly;

FIG. 31 is a cross-sectional perspective view of the moment arm shift assembly;

FIG. 32 is a top plan view of a plurality of control links;

FIG. 33A is a side perspective view of the control assembly with the moment arm shift in the low tension position and the chair assembly in the upright position;

FIG. 33B is a side perspective view of the control assembly with the moment arm shift in the low tension position and the chair assembly in the reclined position;

FIG. 34A is a side perspective view of the control assembly with the moment arm shift in the high-tension position and the chair assembly in the upright position;

FIG. 34B is a side perspective view of the control assembly with the moment arm shift in the high-tension position and the chair assembly in the reclined position;

FIG. 35 is a graph of torque versus caster at low and high tension settings;

FIG. 36 is a perspective view of a direct drive assembly with the seat support plate exploded therefrom;

FIG. 37 is an exploded perspective view of the direct drive assembly;

FIG. 38 is a perspective view of a vertical height control assembly;

FIG. 39 is a side view of the vertical height control assembly;

FIG. 40 is a side view of the vertical height control assembly;

FIG. 41 is a front elevational view in section of the first input control assembly;

FIG. 42A is an exploded view of a control input assembly;

FIG. 42B is an enlarged perspective view of the clutch member of the first control input assembly;

FIG. 42C is an exploded view of the control input assembly;

FIG. 43 is a side perspective view of the variable back control assembly;

FIG. 44 is a perspective view of an arm assembly;

FIG. 45 is an exploded perspective view of the arm assembly;

FIG. 46 is a side elevational view of the arm assembly in a raised position with the lowered position shown in phantom;

FIG. 47 is a partial cross-sectional view of the arm assembly;

FIG. 48 is a top plan view of the chair assembly showing the arm assembly in an in-line position and an angled position in phantom;

figure 49 is an isometric view of the arm assembly including a vertical height adjustment lock;

FIG. 50 is an isometric view of the arm assembly including a vertical height adjustment lock;

FIG. 51 is an isometric view of the arm assembly including a vertical height adjustment lock;

FIG. 52 is a top plan view of the chair assembly showing the armrest assembly in an in-line position and in phantom lines in a rotated position and in a retracted position and in phantom lines in an extended position;

FIG. 53 is an exploded perspective view of the armrest assembly;

FIG. 54 is a cross-sectional view of the armrest assembly;

Detailed Description

For purposes of description herein, the terms "upper," "lower," "right," "left," "rear," "front," "vertical," "horizontal," and derivatives thereof shall relate to the invention as oriented in fig. 1. However, it is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. Various elements of the embodiments disclosed herein may be described as being operatively coupled to each other, including elements that are directly or indirectly coupled to each other. Further, the term "chair" as used herein encompasses a variety of seating arrangements, including office chairs, automobile seats, home seats, stadium seats, theater seats, and the like.

Reference numeral 10 (fig. 1 and 2) generally designates a chair assembly embodying the present invention. In the illustrated example, the chair assembly 10 includes a wheeled base assembly 12 abutting a supporting floor surface 13, a control or support assembly 14 supported by the wheeled base assembly 12, a seat assembly 16 and a back assembly 18 each operatively coupled to the control assembly 14, and a pair of arm assemblies 20. The control assembly 14 (fig. 3) is operatively coupled to the base assembly 12 such that the seat assembly 16, back assembly 18 and arm assembly 20 are vertically adjustable between a fully lowered position a and a fully raised position B and are pivoted about a vertical axis 21 in a direction 22. The seat assembly 16 is operatively coupled to the control assembly 14 such that the seat assembly 16 is longitudinally adjustable relative to the control assembly 14 between a fully retracted position C and a fully deployed position D. The seat assembly 16 (fig. 4) and the back assembly 18 are operatively coupled with the control assembly 14 and with one another such that the back assembly 18 is movable between a fully upright position E and a fully reclined position F, and further such that the seat assembly 16 is movable between a fully upright position G and a fully reclined position H, which correspond to the fully upright position E and the fully reclined position F, respectively, of the back assembly 18.

The base assembly 12 includes a plurality of pedestal arms 24 that extend radially and are spaced apart from one another about a hollow central column 26 that receives a pneumatic cylinder 28 therein. Each pedestal arm 24 is supported above the floor surface 13 by an associated caster assembly 30. Although the base assembly 12 is shown as comprising a multiple-arm pedestal assembly, it is noted that other suitable support structures may be employed, including but not limited to fixed posts, a multi-legged arrangement, a vehicle seat support assembly, and the like.

The seat assembly 16 (fig. 5) includes a relatively rigid seat support plate 32 having: a leading edge 34; a trailing edge 36; and a pair of C-shaped rails 38 defining the side edges of the seat support plate 32 and extending between the front and rear edges 34, 36. The seat assembly 16 further includes a flexibly resilient outer seat shell 40 having a pair of upturned side portions 42 and an upturned rear portion 44 which cooperate to define an upwardly disposed generally concave shape. In the illustrated example, the seat shell 40 is constructed of a relatively pliable material such as a thermoplastic elastomer (TPE). In assembly, the outer seat shell 40 is secured and sandwiched between the seat support plate 32 and a plastic, flexibly resilient seat pan 46 that is secured to the seat support plate 32 by a plurality of mechanical fasteners. The seat pan 46 includes a front edge 48, a rear edge 50, side edges 52 extending between the front edge 48 and the rear edge 50, a top surface 54, and a bottom surface 56 that cooperate to form an upwardly disposed generally concave shape. In the illustrated example, the seat pan 46 includes a plurality of longitudinally extending slots 58 that extend forwardly from the rear edge 50. The slots 58 cooperate to define a plurality of fingers 60 therebetween, each finger 60 being individually pliable, resilient. The seat pan 46 also includes a plurality of transversely oriented elongated apertures 62 located adjacent the leading edge 48. The apertures 62 cooperate to increase the overall flexibility of the seat pan 46 in the area thereof and particularly allow a forward portion 64 of the seat pan 46 to flex in a vertical direction 66 relative to a rearward portion 68 of the seat pan 46, as discussed further below. The seat assembly 16 further includes a foam cushion member 70 that rests on the top surface 54 of the seat pan 46 and is recessed within the outer seat shell 40, a fabric seat cover 72 (fig. 1 and 2), and an upper surface 76 of the cushion member 70. A spring support assembly 78 (fig. 5 and 6) is secured to the seat assembly 16 and is adapted to flexibly support the front portion 64 of the seat pan 46 for bending in the vertical direction 66. In the illustrated example, the spring support assembly 78 includes a support housing 80 containing foam and having side portions 82 defining an upwardly concave arcuate shape. The spring support assembly 78 also includes a relatively rigid attachment member 84 extending laterally between the side portions 82 of the support housing 80 and between the support housing 80 and the front portion 64 of the seat pan 46. A plurality of mechanical fasteners 86 secure the support housing 80 and the attachment member 84 to the front portion 64 of the seat pan 46. The spring support assembly 78 also includes a pair of cantilever springs 88 each having a distal end 90 received through a corresponding aperture 92 of the attachment member 84 and a proximal end 94 secured to the seat support plate 32 such that the distal end 90 of each cantilever spring 88 can flex in the vertical direction 66. A pair of linear bearings 96 are fixedly attached to the attachment member 84 and aligned with the apertures 92 thereof such that the linear bearings 96 slidably receive the distal end 90 of a respective cantilever spring 88. In operation, the cantilever springs 88 cooperate to allow the front portion 64 of the seat pan 46, and more generally the entire front portion of the seat assembly 16, to flex in the vertical direction 66 as a seated user rotates forward on the seat assembly 16 and applies a downward force to the forward edge thereof.

The back assembly 18 (fig. 7-9B) includes a back frame assembly 98 and a back support assembly 99 supported thereby. The back frame assembly 98 is generally comprised of a substantially rigid material, such as metal, and includes a laterally extending top frame portion 100, a laterally extending bottom frame portion 102, and a pair of curved side frame portions 104 that extend between and cooperate with the top frame portion 100 and the bottom frame portion 102 to define an opening 106 having a relatively large upper dimension 108 and a relatively narrow lower dimension 110.

The back assembly 18 further includes a flexibly resilient plastic back shell 112 having an upper portion 114, a lower portion 116, a pair of side edges 118 extending between the upper portion 114 and the lower portion 116, a forward surface 120 and a rearward surface 122, wherein the upper portion 114 has a width substantially greater than the width of the lower portion 116, and the lower portion 116 tapers downwardly to substantially follow the rear elevational aspect of the frame assembly 98. A lower reinforcing member 115 is attached to a hook 117 of a lower portion 116 of the back shell 112 (fig. 9A). The reinforcement member 115 includes a plurality of protrusions 113 that engage the reinforcement ribs 134 to prevent side-to-side movement of the lower reinforcement member 115 relative to the back shell 112. As discussed below, the reinforcement member 115 pivotally interconnects the back control link 342 (fig. 26) and the lower portion 116 of the back shell 112 at a pivot point or axis 346.

The back shell 112 also includes a plurality of integrally molded, forwardly and upwardly extending hooks 124 (fig. 10) that are spaced apart from one another about the periphery of the upper portion 114 of the back shell. An intermediate or lumbar portion 126 is vertically positioned between the upper and lower portions 114, 116 of the back shell 112 and includes a plurality of laterally extending slots 128 that cooperate to form a plurality of laterally extending ribs 130 positioned therebetween. The slots 128 cooperate to provide additional flexibility in their location for the back shell 112. A pair of transverse ribs 130 cooperate with vertically extending ribs 132 integrally formed therewith and located at about a transverse midpoint thereof. As the back assembly 18 is moved from the upright position E to the reclined position F as described below, the vertical ribs 132 act to tie the lateral ribs 130 together and reduce vertical expansion between the latter as the back shell 112 is flexed at its intermediate position 126. The back shell 112 also includes a plurality of laterally spaced apart stiffening ribs 134 extending longitudinally along the vertical length of the back shell 112 between the lower portion 116 and the intermediate portion 126. It is noted that the depth of each rib 134 increases from the middle portion 126 along each rib 134 such that the overall rigidity of the back shell 112 increases along the length of the rib from the middle portion 126 to the lower portion 116.

The back shell 112 also includes a pair of rearwardly extending, integrally molded pivot bosses 138 that form part of an upper back pivot assembly 140. The back pivot assembly 140 (fig. 11-13B) includes a pivot boss 138 of the back shell 112, a pair of cover members 142 surrounding the respective pivot bosses 138, a seat member 144 and a mechanical fastening assembly 146. Each pivot boss 138 includes a pair of side walls 148 and a rearwardly concave seating surface 150 having a vertically elongated pivot slot 152 extending therethrough. Each shroud member 142 is shaped to closely receive a respective pivot boss 138 and includes a plurality of side walls 154 corresponding to the side walls 148, and a rearwardly concave bearing surface 156 which includes a vertically elongated pivot slot 143 extending therethrough and which is adapted to align with the slot 152 of the respective pivot boss 138. The race member 144 includes a central portion 158 extending transversely along and abutting the top frame portion 100 of the back frame assembly 98 and a pair of arcuate bearing surfaces 160 at the ends thereof. Specifically, the central portion 158 includes a first portion 162 and a second portion 164, wherein the first portion 162 abuts a front surface of the top frame portion 100 and the second portion 164 abuts a top surface of the top frame portion 100. Each bearing surface 160 includes an aperture 166 extending therethrough that aligns with a corresponding sleeve member 168 integral with the back frame assembly 98.

In assembly, the cover member 142 is positioned about the respective pivot boss 138 of the back shell 112 and operatively positioned between the back shell 112 and the seat ring member 144 such that the bearing surface 156 is sandwiched between the seating surface 150 and a bearing surface 160 of the respective pivot boss 138. The mechanical fastening assemblies 146 each include a bolt 172 that secures a rounded abutment surface 174 of a bearing washer 176 in sliding engagement with an inner surface 178 of the corresponding pivot boss 138 and in threaded engagement with the corresponding sleeve member 168 of the back shell 112. In operation, upper back pivot assembly 140 allows back support assembly 99 to pivot in direction 180 (fig. 8) relative to back frame assembly about pivot 182 (fig. 7).

The back support assembly 99 (fig. 9A and 9B) also includes a flexibly resilient comfort member 184 (fig. 15A and 15B) that is attached to the back shell 112 and slidably supports a lumbar assembly 186. The comfort member 184 includes an upper portion 188, a lower portion 190, a pair of side portions 192, a front surface 193, and a rear surface 195, wherein the upper portion 188, the lower portion 190, and the side portions 192 cooperate to form an aperture 194 that receives the lumbar assembly 186 therein. As best shown in fig. 9B and 14, the comfort member 184 includes a plurality of box-shaped couplers 196 spaced about the periphery of the upper portion 188 and extending rearwardly from a rear surface 195. Each box-shaped coupler 196 includes a pair of side walls 198 and a top wall 200 that cooperate to form an interior space 202. A bar 204 extends between the side walls 198 and is spaced from the rear surface 195. In assembly, the comfort member 184 (fig. 12-14) is secured to the back shell 112 by aligning and vertically inserting the hooks 124 of the back shell 112 into the interior space 202 of each box-shaped coupler 196 until the hooks 124 engage the corresponding rods 204. It is noted that the front surface 120 of the back shell 112 and the rear surface 195 of the comfort member 184 are free of holes or apertures proximate the hooks 124 and box-shaped couplers 196 to provide a smooth front surface 193 and increase comfort for a seated user.

The comfort member 184 (fig. 15A and 15B) includes an integrally molded, longitudinally extending sleeve 206 extending rearwardly from the rear surface 195 and having a rectangular cross-sectional configuration. The lumbar assembly 186 includes a forward laterally concave and forward vertically convex, pliant, resilient body portion 208 and an integral support portion 210 extending upwardly from the body portion 208. In the illustrated example, the body portion 208 is shaped such that it vertically tapers along its height such that it generally follows the contour and shape of the aperture 194 of the comfort member 184. The support portion 210 is slidably received within the sleeve 206 of the comfort member 184 such that the lumbar assembly 186 is vertically adjustable relative to the remainder of the back support assembly 99 between a fully lowered position I and a fully raised position J. The pawl member 212 selectively engages a plurality of apertures 214 spaced along the length of the support portion 210 to releasably secure the lumbar assembly 186 in a selected vertical position between the fully lowered position I and the fully raised position J. The pawl member 212 (fig. 16A and 16B) includes a housing portion 216 having an engagement tab 218 at an end thereof and offset rearwardly from an outer surface 220 of the housing portion 216. A flexibly resilient finger 222 is centrally disposed within the housing portion 216 and includes a rearwardly extending detent 224.

When assembled, the pawl member 212 (fig. 17) is positioned within the aperture 226 in the upper portion 188 of the comfort member 184 such that the outer surface 220 of the housing portion 216 of the pawl member 212 is coplanar with the front surface 193 of the comfort member 184 and such that the engagement tabs 218 of the housing portion 216 abut the rear surface 195 of the comfort member 184. The support portion 210 of the lumbar assembly 186 is then positioned within the sleeve 206 of the comfort member 184 such that the sleeve 206 is slidable therein and the pawl 224 is selectively engageable with the aperture 214, thereby allowing the user to optimize the position of the lumbar assembly 186 relative to the overall back support assembly 99. Specifically, the body portion 208 of the lumbar assembly 186 includes a pair of outwardly extending, integral handle portions 251 (fig. 18A and 18B) each having a C-shaped cross-sectional configuration that defines a channel 253 therein that surrounds and is guided along the respective side edges 192 of the comfort member 184 and the side edges 118 of the back shell 112.

In operation, a user adjusts the relative vertical position of the lumbar assembly 186 with respect to the back shell 112 by grasping one or both of the handle portions 251 and sliding the handle assembly 251 in a vertical direction along the comfort member 184 and the back shell 112. The stop tab 228 is integrally formed in the distal end 230 and is offset therefrom to engage the end wall of the sleeve 206 of the comfort member 184, thereby limiting the vertical downward travel of the support portion 210 of the lumbar assembly 186 relative to the sleeve 206 of the comfort member 184.

The back assembly 99 (fig. 9A and 9B) further includes a cushion member 252 having an upper portion 254 and a lower portion 256, wherein the lower portion 256 is reduced along its vertical length to correspond to the overall shape and reduction of the back shell 112 and comfort member 184.

The seat assembly 16 and backrest assembly 18 are operatively coupled to and controlled by the control assembly 14 (fig. 19) and the control input assembly 260. The control assembly 14 (fig. 20-22) includes a housing or base structure or ground structure 262 including a front wall 264, a rear wall 266, a pair of side walls 268 and a bottom wall 270 that are integrally formed with one another and cooperate to define an upwardly open interior space 272. The bottom wall 270 includes an aperture 273 disposed at the center thereof for receiving the cylinder assembly 28 (FIG. 3) therethrough as described below. The base structure 262 further defines an upper and forward pivot point 274, a lower and forward pivot point 276, and an upper and rearward pivot point 278, wherein the control assembly 14 further includes a seat support structure 282 that supports the seat assembly 16. In the illustrated example, the seat support structure 282 has a generally U-shaped planar configuration that includes a pair of forwardly extending arm portions 284 that each include a forwardly located pivot aperture 286 pivotally secured to the base structure 262 by a pivot shaft 288 for pivotal movement about the upper and forward pivot points 274. The seat support structure 282 also includes a rear portion 290 that extends laterally between and cooperates with the arm portions 284 to form an interior space 292 within which the base structure 262 is received. The rear portion 290 includes a pair of rearwardly extending arm mounting portions 294 to which the arm assemblies 20 are attached as described below. The seat support structure 282 also includes a control input assembly mounting portion 296 to which the control input assembly 260 is mounted. The seat support structure 282 also includes a pair of bushing assemblies 298 that cooperate to define a pivot point 300.

The control assembly 14 further includes a back support structure 302 having a generally U-shaped planar configuration and including a pair of forwardly extending arm portions 304 each including a pivot aperture 305 and pivotally coupled to the base structure 262 by a pivot shaft 307 such that the back support structure 302 pivots about the lower and forward pivot points 276. The back support structure 302 includes a rear portion 308 that cooperates with the arm portion 304 to define an interior space 310 that receives the base structure 262 therein. The back support structure 302 also includes a pair of pivot apertures 312 disposed along its length that cooperate to define a pivot point 314. It is noted that in some instances, at least a portion of the back frame assembly 98 may be included as part of the back support structure 302.

The control assembly 14 also includes a plurality of control links 316, each having a first end 318 pivotally coupled to the seat support structure 282 by a pair of pivot pins 321 to pivot about the pivot point 300, and a second end 322 pivotally coupled to a corresponding pivot aperture 312 of the back support structure 302 by a pair of pivot pins 324 to pivot about the pivot point 314. In operation, the control link 316 controls the movement of the seat support structure 282 relative to the back support structure 302, and in particular the rate of recline of the former relative to the latter, as the chair assembly is moved to the reclined position, as described below.

As best shown in fig. 23A and 23B, the bottom frame portion 102 of the back frame assembly 98 is configured to be connected to the back support structure 302 via a quick connect device 326. Each arm portion 304 of the back support structure 302 includes a mounting aperture 328 at a proximal end 330 thereof. In the illustrated example, the quick-connect apparatus 326 includes the configuration of the bottom frame portion 102 of the back frame assembly 98 to include a pair of forwardly extending coupler portions 332, the coupler portions 332 cooperating to define a channel 334 therebetween, the channel 334 receiving the proximal end 330 of the arm portion 304 and the rear portion 308 therein. Each coupling portion 332 includes a downwardly extending sleeve 336 that is aligned with and received in a corresponding aperture 328. Mechanical fasteners (e.g., screws 338) are then threaded into the threads of the sleeves 336, thereby allowing the back frame assembly 98 to be quickly connected to the control assembly 14.

As best shown in fig. 24, the base structure 262, the seat support structure 282, the back support structure 302, and the control link 316 cooperate to form a 4-bar linkage assembly that supports the seat assembly 16, the back assembly 18, and the arm assembly 20. For ease of reference, the associated pivot assemblies associated with the 4-link assembly of the control assembly 14 are referred to as follows: the pivot point 274 between the base structure 262 and the base support structure 282 above and forward is referred to as the first pivot point 274; the lower and forward pivot point 276 between the base structure 262 and the back support structure 302 is referred to as the second pivot point 276; the pivot point 300 between the first end 318 of the control link 316 and the seat support structure 282 is referred to as the third pivot point 300; and the pivot point 314 between the second end 322 of the control link 316 and the back support structure 302 is referred to as the fourth pivot point 314. Additionally, fig. 24 shows the components of the chair assembly 10 in a reclined position in phantom, where the reference numerals of the chair in the reclined position are labeled with a "'".

In operation, the 4-bar linkage assembly of the control assembly 14 cooperates to recline the seat assembly 16 from the upright position G to the reclined position H as the back assembly 18 is moved from the upright position E to the reclined position F, where positions E and F are illustrated in the upper and lower representations of fig. 24 as the upper and lower portions of the back assembly 18 recline as a single piece. Specifically, the control link 316 is configured and coupled to the seat support structure 282 and the back support structure 302 such that when the back support structure 302 pivots about the second pivot point 276, the seat support structure 282 pivots about the first pivot point 274. Preferably, the seat support structure 302 rotates about the first pivot point 274 at a rate between about 1/3 and about 2/3 of the rate at which the back support structure 302 rotates about the second pivot point 276, more preferably the seat support structure rotates about the first pivot point 274 at a rate about half the rate at which the back support structure 302 rotates about the second pivot point 276, and most preferably the seat assembly 16 reclines from the fully upright position G to an angle β of about 9 ° to the fully reclined position H as the back assembly 18 reclines from the fully upright position E to an angle γ of about 18 ° to the fully reclined position F.

As best shown in fig. 24, the first pivot point 274 is located above and forward of the second pivot point 276 when the chair assembly 10 is in either the fully upright or fully reclined positions because the base structure 262 remains fixed relative to the supporting floor surface 13 when the seat assembly 10 is reclined. The third pivot point 300 remains behind and below its relative vertical height from the first pivot point 274 throughout the reclining motion of the chair assembly 10. It is further noted that the distance between the first pivot point 274 and the second pivot point 276 remains greater than the distance between the third pivot point 300 and the fourth pivot point 314 throughout the reclining motion of the chair assembly 10. As best shown in fig. 25, a longitudinally extending central axis 340 of the control link 316 forms an acute angle α with the seat support structure 282 when the chair assembly 10 is in the fully upright position, and forms an acute angle α' when the chair assembly 10 is in the fully reclined position. It is noted that the central axis 340 of the control link 316 does not rotate beyond an orthogonal alignment with the seat support structure 282 when the chair assembly 10 is moved between its fully upright and fully reclined positions.

With further reference to fig. 26, the back control link 342 includes a front end that is pivotally connected to the seat support structure 282 at a fifth pivot point 344. The rear end 345 of the back control link 342 is connected to the lower portion 116 of the back shell 112 at a sixth pivot point 346. Sixth pivot point 346 is optional and back control link 342 and back shell 112 may also be rigidly fixed to each other. In addition, pivot point 346 may include a stop that limits the rotation of back control link 342 relative to back shell 112 in the first and/or second rotational directions. For example, referring to fig. 26, pivot point 346 may include a stop that allows lower portion 116 of back shell 112 to rotate clockwise relative to control link 342. If tending to reduce the dimension D₁Is applied to the lumbar portion of the back shell 112, the above configuration allows the lumbar portion to become flatter. However, the stop may be configured to prevent the lower portion 116 of the back shell 112 from rotating in a counterclockwise direction relative to the control link 342 (fig. 26). This results in the link 342 and the lower portion 116 of the back shell 112 rotating at the same angular rate as the back assembly 18 as the user reclines in the chair by pushing on the upper portion of the back assembly 18.

A cam link 350 is also pivotally connected to the seat support structure 282 for rotation about a pivot point or axis 344. The cam linkage 350 has a curved lower cam surface 352 that slidably engages an upwardly facing cam surface 354 formed in the back support structure 302. A pair of torsion springs 356 (see also fig. 18A and 18B) to tend to increase the angle(fig. 26) rotatably biases the back control link 342 and the cam link 350. The torsion springs 356 generate a force tending to rotate the control link 342 in a counterclockwise direction (fig. 26) and simultaneously rotate the cam link 350 in a clockwise direction (fig. 26). Thus, the torsion springs 356 tend to increase the angle between the back control link 342 and the cam link 350. A stop 348 on the seat support structure 282 limits counterclockwise rotation of the back control link 342 to the position shown in fig. 26. This force may also bias the control link 342 into the stop in a counterclockwise direction.

As discussed above, the back shell 112 is pliable, particularly as compared to the rigid back frame structure 98. As also discussed above, the back frame structure 98 is rigidly connected to the back support structure 302 and thus pivots with the back support structure 302. The force generated by the torsion spring 356 urges the lower portion 116 of the back shell 112 upward. As also discussed above, the slots 128 in the back shell structure 112 create additional flexibility in the lumbar support portion 126 of the back shell 112. The force generated by the torsion spring 356 also tends to cause the lumbar portion 126 of the back shell 112 to bend forward such that the lumbar portion 126 has a greater arc than the area adjacent the lumbar portion 126.

As discussed above, the position of the lumbar assembly 186 is vertically adjustable. The vertical adjustment of the lumbar assembly 186 also adjusts the manner in which the back shell 112 flexes/bows during recline of the chair back. In fig. 26, the lumbar assembly 186 is adjusted to a neutral or neutral position such that the arc of the lumbar portion 126 of the back shell 112 is also neutral or neutral. With further reference to FIG. 27, if the vertical position of the lumbar assembly 186 is adjusted, the angleIs reduced and the arc of the lumbar region 126 is reduced. This also results in an angle, as shown in FIG. 27Becomes larger and the overall shape of the back shell 112 becomes relatively flat.

With further reference to fig. 28, if the height of the lumbar assembly 186 is set at the mid-level (i.e., as in fig. 26) and a user leans back, the 4-bar linkage defined by the links and structures 262, 282, 302, 316 and the pivot points 274, 276, 300, 314 will move from the configuration of fig. 26 to the configuration of fig. 28 (as described above)). This in turn causes the distance between the pivot point 344 and the cam surface 354 to increase. This results in an angleFrom about 49.5 ° (fig. 26) to about 59.9 ° (fig. 28). As the spring rotates toward the open position, some of the energy stored in the spring is transferred into the back shell 112, thereby causing the curvature of the lumbar portion 116 of the back shell 112 to become greater. As such, the back control link 342, the cam link 350, and the torsion spring 356 provide a greater curvature to the lumbar region 116 to reduce the curvature of the user's back as the user reclines in the chair.

Further, when the chair is tilted from the position of fig. 26 to the position of fig. 28, the distance D between the lumbar region 242 and the seat 16 increases from 174 mm to 234 mm. The dimension D between the lumbar region 126 of the back shell 112 and the back frame structure 98 when the back is reclined from the position in fig. 26 to the position in fig. 28₁And also increases. Thus, during recline, dimension D increases somewhat, although distance D increases somewhat₁The increase in dimension D decreases because the lumbar region 126 of the back shell 112 is displaced forward relative to the back frame 98.

Referring again to fig. 26, when a user is seated in an upright position, the spine 360 of the seated user 362 tends to curve forward at the lumbar region 364 by a first amount. As the user reclines from the position of fig. 26 to the position of fig. 28, the curvature of the lumbar region 364 tends to increase and the user's spine 360 will also rotate a little about hip joint 366 relative to the user's femur 368. The increase in dimension D and the increase in curvature of the lumbar region 126 of the back shell 112 simultaneously ensure that the user's hip joint 366 and femur 368 do not slide on the seat 16 and accommodate the curvature of the lumbar region 364 of the user's spine 360.

As discussed above, fig. 27 shows the back assembly 18 of the chair assembly 10 in an upright position with the lumbar region 126 of the back shell 112 adjusted to a flat position. If the back assembly 18 is reclined from the position of fig. 27 to the position of fig. 29, both the back control link 342 and the cam link 350 rotate in a clockwise direction. However, the cam linkage 350 rotates at a slightly higher rate, angleThus changing from 31.4 to 35.9. Distance D changed from 202 mm to 265 mm, and angleFrom 24.2 ° to 24.1 °.

With further reference to fig. 29A, if the back assembly 18 is reclined and the lumbar adjustment is set to high, the angle is setIs 93.6 deg., and the distance D is 202 mm.

Thus, when the seat back is tilted backward, the back shell 112 is bent. However, if the arc is initially adjusted to a higher level, the increase in arc of the lumbar region 126 from the upright to the reclined position is significantly greater. This is an arrangement made in consideration of the fact that: if the user's back is initially in a relatively flat condition when seated upright, the curvature of the user's back does not increase as much as the user reclines. Repeating the following steps: if the user's back is relatively straight when in the upright position, the user's back will remain relatively straight even when reclined, although the arc will increase slightly from the upright position to the reclined position. Conversely, if the user's back is significantly curved when in an upright position, the increase in curvature of the lumbar region as the user reclines will be higher than if the user's back was initially relatively straight.

A pair of spring assemblies 442 (fig. 20 and 21) bias the back assembly 18 from the reclined position F to the upright position E. As best shown in fig. 22, each spring assembly 442 includes a cylindrical housing 444 having a first end 446 and a second end 448. Each spring assembly 442 further includes a compression coil spring 450, a first coupling member 452, and a second coupling member 454. In the illustrated example, the first coupling is fixed to the first end 446 of the housing 444, while the second coupling 454 is fixed to a rod member 456 that extends through the coil spring 450. A washer 457 is secured to the distal end of the rod member 458 and abuts one end of the coil spring 450, while the other end of the coil spring 450 abuts the second end 448 of the housing 444. The first coupling 452 is pivotally secured to the back support structure 302 by a pivot pin 460 for pivotal movement about a pivot point 461, wherein the pivot pin 460 is received within a pivot aperture 462 of the back support structure 302, and the second coupling 454 is pivotally coupled to a moment arm shift assembly 466 (fig. 30-32) by a shaft 464 for pivoting about a pivot point 465. The moment arm shift assembly is adapted to shift the biasing or spring assembly 442 from a low tension setting (fig. 33A) to a high tension setting (fig. 34A) in which the force applied by the biasing assembly 442 to the back assembly 18 is increased relative to the low tension setting.

As shown in fig. 30A-32, the moment arm shift assembly 466 includes: an adjustment assembly 468; a moment arm shift linkage assembly 470 operatively coupling the control input assembly 260 to the adjustment assembly 468 and allowing an operator to move the biasing assembly 442 between the low and high tension settings; and an adjustment assist assembly 472 adapted to reduce the magnitude of the input force applied to the control input assembly 260 required by the user to move the moment arm shift assembly 466 from the low tension setting to the high tension setting, as described below.

The adjustment assembly 468 includes a pivot pin 467 that includes a threaded aperture that receives the threaded adjustment shaft 476 therein. The adjustment shaft 476 includes a first end 478 and a second end 484, wherein the first end 478 extends through an aperture 480 of the base structure 262 and is guided by a bearing assembly 482 for pivoting about a longitudinal axis. The pivot pin 467 is supported by the base structure 262 by a link assembly 469, the link assembly 469 including: a pair of link arms 471, the link arms 471 each having: a first end 473 pivotally coupled to the second coupling member 454 by the pivot pin 464; and a second end 475 pivotably coupled to the base structure 262 by a pivot pin 477 pivotably received in the pivot aperture 479 of the base structure 262 to pivot about a pivot point 481; and an aperture 483 that receives a respective end of pivot pin 467. The pivot pin 467 is pivotally coupled along its length to the link arm 471.

The moment arm shift linkage assembly 470 (fig. 30A and 30B) includes a first drive shaft 486 extending between the control input assembly 260 and the first beveled gear assembly 488, and a second drive shaft 490 extending between and operably coupling the first beveled gear assembly 488 and the second beveled gear assembly 492, wherein the second beveled gear assembly 492 is connected to the adjustment shaft 476. The first drive shaft 486 includes a first end 496 that is operably coupled to the control input assembly 260 by a first universal joint assembly 498, while the second end 500 of the first drive shaft 486 is operably coupled to a first helical gear assembly 488 by a second universal joint assembly 502. In the illustrated example, the first end 496 of the first drive shaft 486 includes a female coupling portion 504 of the first universal joint assembly 498 and the second end 500 of the first drive shaft 486 includes a female coupling portion 506 of the second universal joint assembly 502. The first beveled gear assembly 488 includes a housing assembly 508 that receives the first beveled gear 510 and the second beveled gear 512 therein. As shown, the first beveled gear 510 includes a male coupling portion 514 that is integral with the second universal joint assembly 502. The first end 496 of the second drive shaft 490 is coupled to the first beveled gear assembly 488 by a third universal joint assembly 516. The first end 518 of the second drive shaft 490 includes a female coupling portion 520 of the third universal joint assembly 516. The second beveled gear 512 includes a male coupling portion 522 with which the third universal joint assembly 516 is integral. The second end 524 of the second drive shaft 490 includes a plurality of longitudinally extending splines 526 that mate with corresponding longitudinally extending splines (not shown) of a coupler member 528. A coupler member 528 couples the second end 524 of the second drive shaft 490 with the second beveled gear assembly 492 through a fourth universal joint assembly 530. Fourth universal joint assembly 530 includes a housing assembly 532 that houses: a first beveled gear 534 coupled to the coupler member 528 by a fourth gimbal assembly 530, and a second beveled gear 536 fixed to the second end 484 of the adjustment shaft 476. The coupler member 428 includes a female coupling portion that receives a male coupling portion 540 integral with the first beveled gear 534.

When assembled, the adjustment assembly 468 of the moment arm shift assembly 466 is operatively supported by the base structure 262, while the control input assembly 260 is operatively supported by the control input assembly mounting portion 296 of the seat support structure 282. As a result, the relative angle and distance between the control input assembly 260 and the adjustment assembly 468 of the moment arm shift assembly 466 changes as the seat support structure 282 is moved between the fully upright position G and the fully reclined position H. The third and fourth gimbal assemblies 516, 530 cooperate with the spline assembly between the splines to compensate for these relative changes in angle and distance.

As best shown in fig. 33A-34B, the moment arm shift assembly 466 functions to adjust the biasing assembly 442 between the low tension and high tension settings. Specifically, fig. 33A shows the biasing assembly 442 in the low tension setting and the chair assembly 10 in the upright position, fig. 33B shows the biasing assembly in the low tension setting and the chair assembly 10 in the reclined position, fig. 34A shows the biasing assembly 442 in the high tension setting and the chair assembly in the upright position, and fig. 34B shows the biasing assembly in the high tension setting and the chair assembly 10 in the reclined position. The distance 542 measured between the pivot point 465 and the second end 448 of the housing 444 of the spring assembly 442 serves as a reference for the amount of compression applied to the spring assembly 442 when the moment arm shift assembly 466 is placed in the low-tension setting with the chair in the upright position. Distance 542' (fig. 33B) comparatively illustrates the incremental compressive force applied to the spring assembly 442 when the moment arm shift assembly 466 is in the high-tension setting and the chair is in the upright position. The user adjusts the amount of force exerted by the biasing assembly 442 on the back support structure 302 by moving the moment arm shift assembly 466 from the low tension setting to the high tension setting. Specifically, an operator drives the adjustment shaft 476 of the adjustment assembly 468 in rotation via the moment arm shift linkage assembly 470 with an input to the control input assembly 260, thereby causing the pivot shaft 467 to travel along the length of the adjustment shaft 476, thereby varying the compressive force exerted on the spring assembly 442 during adjustment of the pivot shaft 467 relative to the base structure 262. The pivot shaft 467 travels within a slot 544 disposed within a sideplate member 546 attached to a sidewall 268 of the base structure 262. It is noted that the distance 542' when the moment arm shift assembly 466 is in the high tension setting and the chair assembly 10 is in the upright position is greater than the distance 542 when the moment arm shift 466 is in the low tension setting and the chair is in the upright position, thereby illustrating that the compressive force exerted on the spring assembly 442 is greater when the moment arm shift is in the high tension setting than when it is in the low tension setting. Similarly, distance 543' (fig. 33B) is greater than distance 543 (fig. 34B), resulting in an increase in the biasing force exerted by biasing assembly 442 and urging back assembly 18 from the reclined position to the upright position. It is noted that a change in the biasing force applied by the biasing assembly 442 corresponds to a change in the biasing torque applied about the second pivot point 276, and that in some configurations, the biasing torque may be changed without changing the length of the biasing assembly 442 or the biasing force.

Fig. 35 is a graph of the amount of torque applied about the second pivot point 276 as the back support structure 302 is moved between the reclined position and the upright position, which forces the back support structure 302 from the reclined position to the upright position. In the illustrated example, the biasing assembly 442 exerts a torque about the second pivot point 276 of about 652 inch-pounds when the back support structure is in the upright position and the moment arm shift 466 is in the low tension setting, and about 933 inch-pounds when the back support structure is in the reclined position and the moment arm shift 466 is in the low tension setting, resulting in a change of about 43%. Similarly, the biasing assembly 442 exerts a torque about the second pivot point 274 of about 1.47E +03 inch-pounds when the back support structure is in the upright position and the moment arm shift 466 is in the high tension setting, and about 2.58E +03 inch-pounds when the back support structure is in the reclined position and the moment arm shift 466 is in the high tension setting, resulting in a change of about 75%. The amount of torque applied by the biasing assemblies 442 as the moment arm shift 466 is set between the low tension setting and the high tension setting as the back support structure 302 is moved between the upright and reclined positions produces a considerable change, which allows the overall chair assembly 10 to provide proper forward back support for users of different heights and weights.

The adjustment assist assembly 472 assists the operator in moving the moment arm shift assembly 466 from the high tension setting to the low tension setting. The adjustment assistance assembly 472 includes: a coil spring 548 secured to the front wall 264 of the base structure 262 with a mounting structure 550; and a catch member 552 extending about the shaft 306 fixed with the link arm 471 and including a catch portion 556 defining an aperture 558 that captures the free end 560 of the coil spring 548. The coil spring 548 applies a force F in an upward vertical direction on the catch member 552 and the shaft 306 and link arm 471, thereby reducing the input force that must be applied to the control input assembly 260 by the user to move the moment arm shift assembly 466 from the low tension setting to the high tension setting.

As described above, the seat assembly 16 is longitudinally movable relative to the control assembly 14 between a retracted position C and a deployed position D (FIG. 3). As best shown in fig. 19, 36 and 37, the direct drive assembly 562 includes a drive assembly 564 and a linkage assembly 566 that couples the control input assembly 260 to the drive assembly 564, thereby allowing a user to adjust the linear position of the seat assembly 16 relative to the control assembly 14 by adjusting the linear position of the seat assembly. In the illustrated example, the seat support plate 32 includes a C-shaped rail 38 that wraps around and slidably engages a corresponding guide flange 570 of a control plate 572 of the control assembly 14. A pair of C-shaped, longitudinally extending connecting rails 574 are positioned within the respective guide rails 38 and are coupled to the seat support plate 32. A pair of C-shaped bushing members 576 extend longitudinally within the connection rail 574 and are positioned between the connection rail 574 and the guide flange 570. The drive assembly 564 includes a rack member 578 having a plurality of downwardly extending teeth 580. The drive assembly 564 also includes a rack guide 582 having a C-shaped cross-sectional configuration that defines a channel 584 that slidably receives the rack member 578 therein. The rack guide 582 includes a slot 586 disposed along its length that matingly receives a bearing member 588 therein. Alternatively, the bearing member 588 may be formed as an integral part of the rack guide 582. The drive assembly 564 also includes a drive shaft 590 having a first end universally coupled with the control input assembly 260 and a second end 594 having a plurality of radially spaced teeth 596. In assembly, the seat support plate 32 is slidably coupled with the control plate 572 as described above, with the rack member 578 secured to the underside of the seat support plate 32 and the rack guide 582 secured within an upwardly open channel 598 of the control plate 572. In operation, an input force applied by a user to the control input assembly 260 is transmitted through the linkage assembly 566 to the drive assembly 564, thereby driving the teeth 596 of the drive shaft 590 against the teeth 580 of the rack member 578 and causing the rack member 578 and the seat support plate 32 to slide relative to the rack guide 582 and the control plate 572.

With further reference to fig. 38-40, the chair assembly 10 includes a height adjustment assembly 600 that allows for vertical adjustment of the seat 16 and backrest 18 relative to the base assembly 12. The height adjustment assembly 600 includes a pneumatic cylinder 28 disposed vertically in the center post 26 of the base assembly 12 in a known manner.

A bracket structure 602 is secured to the housing or base structure 262 and an upper end portion 604 of the pneumatic cylinder 28 is received in an opening 606 of the base structure 262 in a known manner. The pneumatic cylinder 28 includes a regulator valve 608 that can be moved downward to release the pneumatic cylinder 28 to provide height adjustment. The bell crank 610 has an upwardly extending arm 630 and a horizontally extending arm 640 configured to engage the release valve 608 of the pneumatic cylinder 28. Bell crank 610 is rotatably mounted to bracket 602. Cable assembly 612 operatively interconnects bell crank 610 with adjustment wheel/rod 620. Cable assembly 612 includes an inner cable 614 and an outer cable or sheath 616. The outer sheath 616 includes a ball fitting 618 that is rotatably received in a ball socket 622 formed in the bracket 602. A second ball fitting 624 is connected to an end 626 of inner cable 614. Second ball fitting 624 is rotatably received in second ball socket 628 of upwardly extending arm 630 of bell crank 610 to allow rotational movement of the cable end during height adjustment.

A second or outer end portion 632 of inner cable 614 wraps around wheel 620, and an end fitting 634 is connected to inner cable 614. A tension spring 636 is connected to the end fitting 634 and the seat structure at point 638. Spring 636 creates tension on inner cable 614 in a direction that when valve 608 is released, cable 614 also shifts in the same direction to rotate bell crank 610. Spring 636 does not generate sufficient force to actuate valve 608, but spring 636 does generate sufficient force to bias arm 640 of bell crank 610 into contact with valve 608. In this way, play or looseness due to tolerances in the components is eliminated. In operation, a user manually rotates adjustment wheel 620, thereby creating tension on inner cable 614. This causes bell crank 610 to rotate, causing arm 640 of bell crank 610 to press against and actuate valve 608 of pneumatic cylinder 28. An internal spring (not shown) of the pneumatic cylinder 28 biases the valve 608 upward, moving the valve 608 to a non-actuated position after the adjustment wheel 620 is released.

The control input assembly 260 (fig. 19 and 41-43) includes a first control input assembly 700 and a second control input assembly 702 that are each adapted to communicate input from a user to chair members and functions coupled thereto, which are housed within a housing assembly 704. The control input assembly 260 includes an anti-back drive assembly 706, an overload clutch assembly 708, and a knob 710. An anti-backdrive mechanism or assembly 706 that prevents the direct drive assembly 562 (fig. 36 and 37) and the seat assembly 16 from being driven between the retracted and deployed positions C, D without input from the control assembly 700. The anti-back drive assembly 706 is received in an interior 712 of the housing assembly 704 and includes an adapter 714 that includes a male portion 716 of a universal adapter coupled to a second end 594 of a drive shaft 590 (FIG. 37) at one end and a spline connector 717 at the other end. The cam member 718 is coupled with the adapter 714 through a clutch member 720. Specifically, the cam member 718 includes a splined end 722 coupled for rotation with the knob 710, and a cam end 724 having an outer cam surface 726. The clutch member 720 includes a pair of inwardly disposed splines 723 that slidably engage a spline connector 717 having a cam surface 730 that cammingly engages the outer cam surface 726 of the cam member 718 as described below. The clutch member 720 has a conical clutch surface 719 that is engagingly received by a locking ring 732 that is locked for rotation relative to the housing assembly 704 and includes a conical clutch surface 721 corresponding to the clutch surface 719 of the clutch member 720 that cooperate to form a conical clutch. The coil spring 734 biases the clutch member 720 into engagement with the locking ring 732.

In the absence of an input, the biasing spring 734 forces the conical surface of the clutch member 720 into engagement with the conical surface of the locking ring 732, thereby preventing "backdriving" -i.e., adjustment of the seat assembly 16 between the retracted and extended positions C, D by merely applying a rearward or forward force to the seat assembly 16 in the absence of an input from the first control input assembly 700. In operation, an operator actuates the direct drive assembly 562 via the first control input assembly 700 to move the seat assembly 16 between the retracted and deployed positions C, D. Specifically, the rotational force applied to the knob 710 by the user is transmitted from the knob 710 to the cam member 718. As the cam member 718 rotates, the outer cam surface 726 of the cam member 718 acts on the cam surface 730 of the clutch member 720, overcoming the biasing force of the spring 734 and forcing the clutch member 720 out of the engaged position, wherein the clutch member 720 disengages the locking ring 732. The rotational force is then communicated from the cam member 718 to the clutch member 720 to the adaptor 714, which is coupled to the direct drive assembly 562 via the linkage assembly 566.

It is noted that small tolerances in the first control input assembly 700 allow the cam member 718 to move (or "wobble") slightly in both a linear direction and a rotational direction as the clutch member 720 is moved between the engaged and disengaged positions. A rotating annular damper element 736 comprising a thermoplastic elastomer (TPE) is located within the interior 712 of the housing 704 and is attached to the clutch member 720. In the illustrated example, the dampener element 736 is urged against and frictionally engages the inner wall of the housing assembly 704.

The first control input assembly 700 also includes a second knob 738 that is adapted to allow a user to adjust the vertical position of the chair assembly between a lowered position a and a raised position B as described below.

The second control input assembly 702 is adapted to adjust the tension applied to the back assembly 18 upon recline and to control the recline of the back assembly 18. The first knob 740 is operably coupled to the moment arm shift assembly 466 by the moment arm shift linkage assembly 470. In particular, the second control input assembly 702 includes a male gimbal coupling portion 742 that couples with the female gimbal coupling portion 504 (fig. 30 and 31) of the shaft 486 of the moment arm shift linkage assembly 470.

Second knob 760 is adapted to adjust the recline of back assembly 18 via a cable assembly 762 that operably couples second knob 760 to variable back stop assembly 764 (fig. 43). The cable assembly 762 includes a first cable guide structure 766, a second cable guide structure 768, and a cable tube 770 extending therebetween that slidably receives an actuation cable 772 therein. The cable 772 includes a distal end 774 that is fixed relative to the base structure 262 and is biased in the direction 776 by a coil spring 778. The variable back stop assembly 764 includes: a stop 780 having a plurality of vertically graduated steps 782; a support bracket 784 fixedly supported relative to the seat assembly 16; and a sliding member 786 slidably coupled to the support bracket 784 to slide in the front-to-rear direction 788 and fixedly coupled to the stopper member 780 by a pair of screws 790. Cable 772 is clamped between stop member 780 and slide member 786 such that longitudinal movement of cable 772 causes stop member 780 to move in fore-aft direction 788. In operation, a user adjusts the position of the stop member 780 to adjust possible back recline via input to the second knob 760. As the back assembly 18 moves from the upright to reclined position, selected ones of the plurality of steps 782 of the stop member 780 contact the rear edge 792 of the base structure 262 to limit the available back recline.

Each arm assembly 20 (fig. 44-46) includes an arm support assembly 800 pivotally supported from an arm base structure 802 and adjustably supporting an armrest assembly 804. Arm support assembly 800 includes a first arm member 806, a second arm member 808, an arm support structure 810, and an armrest assembly support member 812 that cooperate to form a 4-bar linkage assembly. In the illustrated example, the first arm member 806 has a U-shaped cross-sectional configuration and includes: a first end 814 pivotably coupled to the arm support structure 810 to pivot about a pivot point 816; and a second end 818 pivotally coupled to the armrest assembly support member 812 for pivotal movement about a pivot point 820. Second arm member 808 has a U-shaped cross-sectional configuration and includes: a first end 822 pivotably coupled to the arm support structure 810 to pivot about a pivot point 824; and a second end 826 pivotally coupled to the armrest assembly support member 812 to pivot about a pivot point 828. As shown, the 4-bar linkage assembly of the arm support assembly 800 allows the armrest assembly 804 to be adjusted between a fully raised position K and a fully lowered position L, wherein the distance between the fully raised position K and the fully lowered position L is preferably at least about 4 inches. Each arm assembly further comprises a first arm cover member 807 having a U-shaped cross-sectional configuration and comprising a first edge portion 809, and a second arm cover member 811 having a U-shaped cross-sectional configuration and comprising a second edge portion 813, wherein the first arm member 806 is received within the first arm cover member 807 and the second arm member 808 is received within the second arm cover member 811 such that the second edge portion 813 overlaps the first edge portion 809.

Each arm base structure 802 includes a first end 830 connected to the control assembly 14 and a second end 832 pivotally supporting the arm support structure 810 to allow the arm assembly 20 to rotate in a direction 837 about a vertical axis 835. The first end 830 of the arm base structure 802 includes a body portion 833 and a narrowed bayonet portion 834 extending outwardly therefrom. In assembly, the body portion 833 and bayonet portion 834 of the first end 830 of the arm base structure 802 are received between the control plate 572 and the seat support structure 282 and are secured thereto by a plurality of mechanical fasteners (not shown) that extend through the body portion 833 and bayonet portion 834 of the arm base structure 802, the control plate 572 and the seat support structure 282. The second end 832 of the arm base structure 802 pivotally receives the arm support structure 810 therein.

As best shown in fig. 47, the arm base structure 802 includes an upwardly opening bearing recess 836 having a cylindrical upper portion 838 and a conical lower portion 840. A bushing member 842 is positioned within the bearing recess 836 and is similarly configured as the lower portion 840 of the bearing recess 836, including a conical portion 846. The arm support structure 810 includes a lower end having a cylindrical upper portion 848 and a conical lower portion 850 that is received within the lower portion 846 of the bushing member 842. The upper end 852 of the arm support structure 810 is configured to operably engage in a vertical locking arrangement, as described below. The pin member 854 is positioned within a centrally disposed, axially extending hole 856 of the arm support structure 810. In the illustrated example, the pin member 854 is made of steel and the upper end 852 of the arm support structure 810 is made of a metal powder that is formed around the proximal end of the pin member 854, and wherein the combination of the upper end 852 and the pin member 854 are encased within an outer aluminum coating. The distal end 853 of the pin member 854 includes an axially extending threaded bore 855 that threadably receives an adjustment screw 857 therein. The arm base structure 802 includes a cylindrical second recess 858 separated from the support recess 836 by a wall 860. A coil spring 864 is positioned within the second recess 858 about the distal end 853 of the pin member 854 and is trapped between the wall 860 of the arm base structure 802 and a washer member 866 such that the coil spring 864 exerts a downward force in the direction of arrow 868 against the pin member 854, thereby bringing the lower end of the arm support structure 810 into tight frictional engagement with the bushing member 842 and the bushing member 842 into tight frictional engagement with the bearing recess 836 of the arm base structure 802. The adjustment screw 857 is adjustable to adjust the frictional interaction between the arm support structure 810, the bushing member 842, and the arm base structure 802 and to increase the force required to be applied by a user to move the arm assembly 20 about the pivot access 835 in the pivot direction 837. The pivotal connection between the arm support structure 810 and the arm base structure 802 allows the entire arm assembly 800 to pivot inwardly in a direction 876 (fig. 48) from a line 874 extending through the pivot access 835 and extending parallel to a center axis 872 of the seat assembly 16 and outwardly in a direction 878 from the line 874. Preferably, the arm assembly 20 pivots more than or equal to about 17 ° in the direction 876 from the line 874 and more than or equal to about 22 ° in the direction 878 from the line 874.

With further reference to fig. 49-51, vertical height adjustment of the armrest is accomplished by rotating the 4-bar linkage, which is formed by the first arm member 806, the second arm member 808, the arm support structure 810, and the armrest assembly support member 812. Gear member 882 includes a plurality of teeth 884 that are arranged in an arc about pivot point 816. A locking member 886 is pivotally mounted to the arm 806 at pivot 888 and includes a plurality of teeth 890 that selectively engage the teeth 884 of the gear member 882. When the teeth 884 and 890 are engaged, the height of the arm rest 804 is fixed due to the rigid triangle formed between the pivot points 816, 824, and 888. If a downward force F4 is applied to the armrest, a counterclockwise (fig. 50) moment is generated on the locking member 886. This moment pushes teeth 890 into engagement with teeth 884, thereby securely locking the height of the armrest.

An elongated locking member 892 is rotatably mounted to arm 806 at pivot 894. A low friction polymer bearing member 896 is disposed on upper curved portion 893 of elongated locking member 892. As discussed in more detail below, a manual release lever or member 898 includes a pad 900 that can be moved upward by a user to selectively release the teeth 890 of the locking member 886 from the teeth 884 of the gear member 882 to allow vertical height adjustment of the armrest.

One leaf spring 902 includes a first end 904 that engages a notch 906 formed in an upper rim 908 of an elongated locking member 892. Thus, the leaf spring 902 is formed as a cantilever with the notch 906 of the locking member 892 as a support point. An upwardly extending tab 912 of the elongated locking member 892 is received in an elongated slot 910 of the leaf spring 902 to position the leaf spring 902 relative to the locking member 892. The end 916 of leaf spring 902 presses the knob 918 of the locking member 886 upward (F1), thereby creating a moment tending to rotate the locking member 886 in a clockwise (release) direction (fig. 51) about the pivot 888. Leaf spring 902 also generates a clockwise moment on elongated locking member 892 at notch 906 and also generates a moment on locking member 886 that tends to rotate locking member 886 in a clockwise (release) direction about pivot 888. This moment tends to disengage teeth 890 from teeth 884. If the teeth 890 are disengaged from the teeth 884, the height of the armrest assembly may be adjusted.

Locking member 886 includes a recess or notch 920 (fig. 50) that receives tip 922 of elongated locking member 892. The recess 920 includes a first shallow V-shaped portion having an angular position 924. The recess also includes a small recess or notch 926 and a transverse, upwardly facing surface 928 immediately adjacent notch 926.

As described above, leaf spring 902 generates a moment that acts on locking member 886, which tends to disengage teeth 890 from teeth 884. However, when the tip or end 922 of elongated locking member 892 is engaged with notch 926 of recess 920 of locking member 886, this engagement prevents rotational movement of locking member 886 in a clockwise (releasing) direction, thereby locking teeth 890 and 884 into engagement with each other and preventing height adjustment of the armrest.

To release the arm assembly for height adjustment of the armrest, the user pulls the pad 900 upward against a small leaf spring 899 (fig. 50). The release member 898 rotates about an axis 897 that extends in a fore-aft direction, and the inner end of the manual release lever 898 pushes downwardly against the bearing member 896/upper curved portion 893 (FIG. 51) of the elongated locking member 892. This creates a downward force which causes elongated locking member 892 to rotate about pivot 894. This moves end 922 (fig. 50) of elongated locking member 892 upwardly so that it is adjacent shallow corner 924 of recess 920 of locking member 886. This displacement of the locking member 892 releases the locking member 886 such that the locking member 886 rotates in a clockwise (release) direction due to the bias of the leaf spring 902. This rotation disengages the teeth 890 from the teeth 884 to allow for height adjustment of the armrest assembly.

The armrest assembly is also configured to prevent disengagement of the height adjustment member during application of a downward force F4 (fig. 50) to the armrest pad 804. Specifically, due to the 4-bar linkage formed by the arm members (806, 808), the arm support structure 810, and the armrest assembly support component 812, the downward force F4 will tend to move the pivot point 820 toward the pivot point 824. However, an elongated locking member 892 is disposed generally between pivots 820 and 824 in line therewith, thereby preventing downward rotation of the 4-link. As described above, downward force F4 causes teeth 890 to tightly engage teeth 884, securely locking the height of the armrest. If the release lever 898 is actuated when a downward force F4 is applied to the armrest, the locking member 892 will move and the end 922 of the elongated locking member 892 will disengage from the notch 926 of the recess 920 of the locking member 886. However, even if locking member 892 is moved to the release position, the torque applied to locking member 886 keeps teeth 890 and 884 engaged. Thus, the configuration of the 4-bar linkage, locking member 886 and gear member 882 provides a mechanism in which height adjustment of the armrest is not possible if a downward force F4 is acting on the armrest.

As best shown in fig. 52 and 53, each armrest assembly 804 is adjustably supported by the associated arm support assembly 800 such that the armrest assembly 804 is pivotable inwardly and outwardly about a pivot point 960 between an in-line position M and a pivoted position N. Each armrest assembly is also linearly adjustable between a retracted position O and a deployed position P relative to its associated arm support assembly 800. Each arm rest assembly 804 (fig. 53) includes an arm rest housing assembly 962 integral with the arm rest assembly support member 812 and defining an interior space 964. The armrest assembly 804 also includes a support plate 966 having a planar body portion 968 with a pair of mechanical fastener receiving apertures 969 and an upwardly extending pivot boss 970. A rectangular slider housing 972 includes a planar portion 974 having an oblong aperture 976 therethrough, a pair of side walls 978 extending longitudinally along and orthogonal from the planar portion 974, and a pair of end walls 981 extending transversely across the ends thereof and orthogonal from the planar portion 974. The arm rest assembly 804 also includes a rotational and linear adjustment member 980 having a planar body portion that defines an upper surface 984 and a lower surface 986. A centrally located aperture 988 extends through the body portion 982 and pivotally receives the pivot boss 970 therein. The rotation and linear adjustment member 980 further includes: a pair of arcuate apertures 990 located at opposite ends thereof; and a pair of two sets of ribs 991 laterally spaced from one another, arcuately disposed, extending upwardly from the upper surface 984 and defining a plurality of ratchet positions 993 therebetween. The rotary selection member 994 includes a planar body portion 996 and a pair of flexibly resilient fingers 998 centrally located therein, each of which includes a downwardly extending engagement portion 1000. Each arm rest assembly 804 also includes an arm pad base 1002 and an arm pad member 1004 that is molded over the base 1002.

In assembly, the support plate 966 is positioned on the armrest housing assembly 962, the slider housing 972 above the support plate 966 such that the bottom surface 1006 of the planar portion 974 frictionally abuts the top surface 1008 of the support plate 966, the rotational and linear adjustment member 980 between the side walls 978 and the end wall 981 of the slider housing 972 such that the bottom surface 986 of the rotational and linear adjustment member frictionally engages the planar portion 974 of the slider housing 972, and the rotational selection member 994 above the rotational and linear adjustment member 980. A pair of mechanical fasteners, such as rivets 1010, extend through the apertures 999 of the rotary selection member 994, the arcuate apertures 990 of the rotary and linear adjustment member 980, and the apertures 969 of the support plate 966 and are threadably secured to the armrest housing assembly 962, thereby securing the support plate 966, the rotary and linear adjustment member 980, and the rotary selection member 994 for linear movement relative to the armrest housing 962. The base 1002 and the arm pad component 1004 are then secured to the slider housing 972. The above arrangement allows the slider housing 972, the base 1002, and the arm pad member 1004 to slide in a linear direction such that the arm rest assembly 804 can be adjusted between the retracted position O and the extended position P. The rivet 1010 is adjustable to adjust the clamping force exerted by the support plate 966 and the rotational and linear adjustment member 980 on the slider housing 972. The base 1002 includes a centrally located, upwardly extending raised portion 1020 and a corresponding downwardly disposed recess (not shown) having a pair of longitudinally extending side walls. Each sidewall includes a plurality of ribs and detents similar to the ribs 991 and detents 993 previously described. In operation, when the arm pad 1004 is moved in a linear direction, the pivot boss 970 engages the detents of the recess, thereby providing tactile feedback to the user. In the illustrated example, the pivot boss 970 includes a slot 1022 that allows the end of the pivot boss 970 to elastically deform when the pivot boss 970 engages the detent, thereby reducing wear on the detent. The arcuate apertures 990 of the rotational and linear adjustment member 980 allow the adjustment member 980 to pivot about the pivot boss 970 of the support plate 966 and allow the armrest assembly 804 to be adjusted between the in-line position M and the angled position N. In operation, the engagement portion 1000 of each finger 998 of the rotating selection member selectively engages the detents 992 defined between the ribs 991, thereby allowing a user to position the arm rest assembly 804 in a selected rotational position and providing tactile feedback to the user when the arm rest assembly 804 is rotationally adjusted.

In the foregoing description, it will be readily understood by those skilled in the art that various alternative implementations of the various components and elements of the present invention and various modifications thereof may be made without departing from the concepts disclosed herein. Such modifications are to be considered as included in the following claims, unless these claims by their language expressly state otherwise.

Claims

1. A chair assembly, comprising:

an arm support structure;

an armrest assembly adapted to support a seated user's arm thereon;

an arm support assembly having a lower end supported by the arm support structure and an upper end supporting the armrest assembly thereon, wherein the arm support assembly is adjustable between a vertically raised position and a vertically lowered position; and

a locking assembly, comprising:

a first locking link with at least one of a plurality of teeth and a first surface;

a second locking link with the other of the plurality of teeth and the first surface, and movable between a locked position in which the first surface engages at least one of the plurality of teeth to prevent the arm support assembly from being adjusted between the raised and lowered positions, and an unlocked position in which the first surface is spaced from the plurality of teeth, thereby allowing the arm support assembly to be adjusted between the raised and lowered positions;

an actuating linkage operably coupled with the first locking linkage and adapted to move between first and second positions, the first locking linkage being moved by the actuator linkage to a locked position in the first locked position and the first locking linkage being moved by the actuator linkage to an unlocked position in the second unlocked position;

and

an actuator member operably coupled to the actuator coupling, wherein at least a portion of the actuator member is actuatable by a seated user, thereby allowing the user to couple the actuator between the first, locked position and the second, unlocked position.

2. The chair assembly of claim 1, wherein the second locking coupling is biased to a locked position.

3. The chair assembly of any one of claims 1 and 2, wherein the second locking coupling is biased by a leaf spring toward a locked position.

4. The chair assembly of claim 1, wherein the actuator coupling comprises a leaf spring.

5. The chair assembly of claim 1, wherein the actuator coupling includes an arcuate abutment surface, and wherein the actuator member abuts the abutment surface of the actuator coupling.

6. The chair assembly of claim 1, wherein the actuator linkage is pivotably coupled to the arm support assembly.

7. The chair assembly of claim 1, wherein the first locking link is pivotably coupled to the arm support assembly.

8. The chair assembly of claim 1, wherein the arm support assembly includes a four-bar linkage assembly comprising:

a first linkage member having a first end and a second end;

a second link member having a first end and a second end;

a third link member having a first end pivotably coupled to the first end of the first link member for rotation about the first pivot point and a second end pivotably coupled to the first end of the second link member for rotation about the second pivot point; and

a fourth link member having a first end pivotably coupled to the second end of the first link member for rotation about the third pivot point and a second end pivotably coupled to the second end of the second link member for rotation about the fourth pivot point.

9. The chair assembly of claim 8, wherein the third link member includes the plurality of teeth.

10. The chair assembly of claim 1, wherein the plurality of teeth form an arcuate path.

11. The chair assembly of claim 10, wherein the arm support assembly is pivotably coupled to the arm support structure, and wherein the plurality of teeth form the arcuate path about a pivot point between the arm support assembly and the arm support structure.

12. The chair assembly of claim 1, wherein a downward force applied to the armrest assembly urges the first surface into engagement with at least one of the plurality of teeth.

13. The chair assembly of claim 1, wherein the actuator member is disposed adjacent the armrest assembly such that the actuator member is readily accessible to a seated user.

14. The chair assembly of claim 1, wherein the armrest assembly is pivotally adjustable relative to the arm support structure.

15. The chair assembly of claim 1, wherein the armrest assembly is linearly adjustable relative to the arm support structure.

16. A chair assembly, comprising;

a seat support structure comprising a seat support surface configured to support a seated user thereon;

an armrest assembly comprising an arm support surface for supporting an arm of a seated user thereon;

an arm support assembly having an upper end and a lower end, the upper end supporting the arm support assembly at a vertical height above the seat support surface, the lower end including a selected one of a pivot boss and a pivot aperture; and

an arm support structure including the other of the pivot boss and the pivot aperture, wherein the pivot boss is received in the pivot aperture to pivotably support the arm support assembly for rotation about a pivot point between the first locked position and the second unlocked position, the pivot boss having a conical shape, and wherein the aperture has a conical shape that closely corresponds to the shape of the pivot boss.

17. The chair assembly of claim 16, wherein the arm support structure includes the pivot aperture.

18. The chair assembly of any one of claims 16 and 17, wherein a frictional force is applied between the pivot boss and the pivot aperture to thereby retain the arm support assembly in a selected position between the first locked position and the second unlocked position, and wherein the arm support assembly is not retained in the selected position by any other mechanical means other than the frictional force.

19. The chair assembly of claim 16, wherein the pivot boss and pivot aperture are biased toward one another.

20. The chair assembly of claim 16, wherein the pivot boss and pivot aperture are biased toward each other by a spring member.

21. The chair assembly of claim 20, wherein the spring member comprises a coil spring.

22. The chair assembly of any one of claims 20 and 21, further comprising:

an adjustment mechanism that adjusts the amount of biasing force exerted by the spring member.

23. The chair assembly of claim 16, further comprising:

a bushing member positioned between the pivot boss and the pivot aperture.

24. The chair assembly of claim 23, wherein the bushing component has a conical shape that generally corresponds to the shape of the pivot boss and the shape of the pivot aperture.

25. The chair assembly of claim 16, wherein the arm support assembly includes a four-bar linkage that allows vertical height adjustment of the armrest assembly relative to the seat support structure.

26. The chair assembly of claim 16, wherein the seat support surface includes a longitudinal axis, and wherein the arm support assembly moves greater than or equal to about 22 ° outward from an axis parallel to the longitudinal axis of the seat support surface.

27. The chair assembly of claim 16, wherein the seat support surface includes a longitudinal axis, and wherein the arm support assembly moves greater than or equal to about 17 ° from an axial direction parallel to the longitudinal axis of the seat support surface.

28. A chair assembly, comprising;

an arm support assembly having an upper end and a lower end;

an armrest assembly adapted to support a seated user's arm thereon and supported on an upper end of the arm support assembly;

an arm support structure pivotally supporting the arm support assembly for pivotal movement about a substantially vertical axis such that the upper end of the arm support assembly is pivotable about the substantially vertical axis between a first locked position and a second unlocked position laterally outboard of the first locked position; and

a seat support structure comprising a seat support surface configured to support a seated user thereon; wherein the seat support surface comprises a longitudinal axis; and is

Wherein the upper end of the arm support assembly moves greater than or equal to about 22 ° outwardly from an axis parallel to the longitudinal axis of the seat support surface, and wherein the upper end of the arm support assembly moves greater than or equal to about 17 ° inwardly from the axis parallel to the longitudinal axis of the seat support surface.

29. The chair assembly of claim 28, wherein the arm support assembly includes a four-bar linkage assembly comprising:

a first linkage member having a first end and a second end;

a second link member having a first end and a second end;

a fourth link member having a first end pivotably coupled to the second end of the first link member for rotation about the third pivot point and a second end pivotably coupled to the second end of the second link member for rotation about the fourth pivot point;

wherein the lower end of the arm support assembly is adjustable between a raised position and a lowered position.

30. The chair assembly of any one of claims 28-29, wherein the lower end of the arm support assembly includes a selected one of a pivot boss and a pivot aperture, the arm support structure includes the other of the pivot boss and the pivot aperture, and wherein the pivot boss is received in the pivot aperture to pivotably support the arm support assembly.

31. The chair assembly of claim 30, wherein the pivot boss is conical, and wherein the pivot aperture is conical and cooperatively receives the pivot boss therein.

32. The chair assembly of claim 30, wherein the arm support structure includes the pivot aperture.

33. The chair assembly of claim 30, wherein friction is applied between the pivot boss and the pivot aperture to retain the arm support assembly in a selected position between the first locked position and the second unlocked position, and wherein the arm support assembly is not retained in the selected position by any other mechanical means other than the friction.

34. The chair assembly of claim 33, wherein the pivot boss and pivot aperture are spring biased toward each other.

35. The chair assembly of one of claims 33 and 34, wherein the frictional force is adjustable by mechanical means.