Patent Publication Number: US-5829839-A

Title: Height-adjustable chair arm assembly having gear-type adjusting mechanism

Description:
FIELD OF THE INVENTION 
     The invention relates to chairs with adjustable arms and, more particularly, to an armrest which can be conveniently vertically adjusted with respect to the chair seat. 
     BACKGROUND OF THE INVENTION 
     Chairs designed for use particularly in office environments and the like are being increasingly provided with adjustment features so as to improve the ergonomics of the chair, particularly in those situations where the chair is used for long periods of time, such as when an occupant is working at a computer terminal, to provide improved comfort and healthful support of the occupant&#39;s body. One of the areas which has been addressed to improve such comfort relates to the chair arms, and some known chairs have provided arms having position adjustability, particularly with respect to the ability to vary the armrest height relative to the seat. The known chairs which possess height-adjustable chair arms typically employ vertically telescopic supports and a cooperating releasable latch arrangement for permitting height adjustment. Most known arrangements, however, have disadvantages, either from a manufacturing or structural viewpoint, or from an operational viewpoint. For example, many of the structures are undesirably complex, and/or do not provide for approximately continuous height adjustment (in contrast to discrete height adjustment at a small number of widely spaced-apart discrete positions) and/or have a less secure locking arrangement that may allow disengagement of the locking parts which may cause the accidental lowering of the armrest relative to the chair seat and/or the overall support arrangement and cooperating latch mechanism is such as to make release of the latch and adjustment of arm height difficult or inconvenient, particularly to an occupant seated in the chair. 
     Examples of known height-adjustable chair arms are shown in the following U.S. Pat. Nos.: 5,439,267, 5,435,626, 5,393,125, 5,393,124, 5,388,892, 5,382,079, 5,368,365, 5,346,284, 5,324,096, 5,318,347 and 5,265,938. 
     Accordingly, it is an object of this invention to provide a chair having a height-adjustable arm assembly associated therewith, which arm assembly significantly improves upon and overcomes many of the disadvantages as briefly summarized above. 
     More specifically, the improved height-adjustable chair arm assembly of this invention provides an improved locking mechanism which extends through the armrest and into the arm upright so as to permit easy and efficient unlocking and height adjustment if desired, with the occupant in a seated position being able to easily release and maintain the locking mechanism in a releasing position, and with the occupant having the feel of approximately continuous height adjustment of the arm assembly, while at the same time permitting the occupant to easily raise or lower the arm while seated, and then permit the locking mechanism to re-engage. 
     Briefly, the present invention comprises a chair having height-adjustable arm assemblies respectively mounted adjacent opposite sides of a seat. Each arm assembly includes a horizontally elongate armrest which is connected to an upper end of an arm upright. The arm upright includes a vertically oriented support segment which has a guide bore defined therein. The armrest includes a vertically elongate slide tube and a horizontally elongate arm element. The arm element is connected to an upper end of the slide tube. A lower end of the slide tube is movably mounted within the guide bore. A lock arrangement functions to permit the slide tube to be positioned relative to the support segment at any one of a plurality of height positions. The lock arrangement includes a cartridge assembly that has a gear which is rotatably supported and carried by the slide tube. The gear has a plurality of gear teeth which engage with a series of vertically spaced notches (i.e. a gear rack) defined within the support segment. A lock releasing mechanism functions to displace a lock member between a locking position and a releasing position. The lock releasing mechanism includes an actuator lever and an actuator rod. The actuator lever is supported on the arm element and the actuator rod extends into the support element and mounts the lock member thereon. The lock member has a plurality of locking teeth which engage the gear when the lock member is positioned in the locking position. 
     Other objects and purposes of the invention will be apparent to persons familiar with structures of this general type upon reading the following specification and inspecting the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a chair having the improved height-adjustable chair arm assembly of this invention mounted thereon, this view showing the right-side chair arm assembly; 
     FIG. 2 is an exploded perspective view of the right-side height-adjustable chair arm assembly according to the present invention, the chair arm assembly being shown removed from the chair for clarity of description, and an upper portion of the armrest being shown removed from the chair arm assembly for clarity of description; 
     FIG. 3 is an enlarged, fragmentary sectional view taken generally along line 3--3 of FIG. 1; 
     FIG. 4 is a sectional view taken generally along line 4--4 in FIG. 3; 
     FIG. 5 is a sectional view taken generally along line 5--5 in FIG. 3; 
     FIG. 6 is a fragmentary sectional view of the armrest of the chair arm assembly of FIG. 1 which shows the cooperation between the actuator rod and the actuator lever; and 
     FIG. 7 is a fragmentary view of only the locking member and gear of FIG. 3, the rest of the chair arm assembly parts being removed for clarity of illustration. 
    
    
     Certain terminology will be used in the following description for convenience in reference only, and will not be limiting. For example, the words &#34;upwardly&#34;, &#34;downwardly&#34;, &#34;rightwardly&#34; and &#34;leftwardly&#34; will refer to directions in the drawings to which reference is made. It will be understood that the words &#34;upwardly&#34; and &#34;downwardly&#34; will also refer to the directions of height adjustment of the armrest relative to the chair seat, these being the actual physical directions experienced by the chair occupant during height adjustment. The words &#34;inwardly&#34; and &#34;outwardly&#34; will respectively refer to directions toward and away from the center of the chair, the center of the arm assembly, or designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import. 
     DETAILED DESCRIPTION 
     FIG. 1 diagrammatically illustrates a chair 2, often referred to as an office-type chair. This chair employs a center pedestal 3 which projects upwardly from a wheeled base 4. A suitable seat assembly is mounted on an upper end of the center pedestal 3. The seat assembly includes a chair seat 6 and a chair control or seat frame 5. The chair control 5 supports the chair seat 6 and is mounted thereto. A chair back 7 projects upwardly from a location above the rear edge of the chair seat 6. 
     The chair 2 is provided with a pair of height-adjustable arm assemblies 8 mounted thereon, namely right and left assemblies which are respectively disposed adjacent the right and left sides of the seat 6 so as to project upwardly therefrom to hence permit the chair occupant to be seated therebetween. The right and left chair arm assemblies 8 are substantially identical except for being mirror images of one another, and only the right side assembly is visible in FIG. 1. 
     Referring now to FIGS. 2-7, the right side height-adjustable arm assembly 8 includes an arm upright 10 which is fixed to and projects upwardly from adjacent the seat 6. The arm upright 10 in the illustrated embodiment is generally L-shaped and includes a base leg 10B which is fixed to the seat frame 5, and also includes a vertically elongate and upwardly cantilevered leg or support segment 10A. The support segment 10A has an elongate plastic sleeve 12 fixed vertically therein. The sleeve 12 is constructed of two parts which effectively snap together. The sleeve 12 defines a guide bore 13 which extends through the sleeve. The sleeve 12 further defines interiorly thereof a gear rack 14 which has a plurality of uniformly vertically spaced notches as shown in FIG. 3. 
     The arm assembly 8 further includes an armrest 28 having an upper portion or arm cap 28A for supporting an occupant&#39;s arm thereon and a lower cover portion 28B extending downwardly from the upper portion. The armrest 28 also includes an arm element 21 having a slide tube 22 fixed thereto and projecting downwardly therefrom. The tube 22, in the illustrated embodiment, is of rectangular cross-section and is slidably supported within the guide bore 13 of the sleeve 12. 
     The arm assembly 8 additionally includes a compact cartridge assembly 15 which is secured interiorly of the tube 22. The cartridge assembly 15 includes a generally channel-shaped housing 16 which is fixed within the tube 22. The tube 22 has a window or aperture 38 defined in a vertical side wall 22A thereof as shown in FIG. 3, which window 38 communicates with the interior of the housing 16 through an open side thereof. A gear 24 is rotatably supported within the housing 16 by a pin 17 which extends transversely between and is supported on opposite side walls of the housing 16. The gear 24 is supported in the housing 16 such that a plurality of teeth on one side of the gear 24 project through the open side of the housing and extend through the aperture 38 so as to engage the plurality of vertically spaced notches of the gear rack 14 as shown in FIG. 3. 
     The housing 16 further has an opening 36 defined within a top wall thereof. An elongate actuator rod 25 projects downwardly through the tube 22 and the housing opening 36 and has a lock member 26 secured to the lower end thereof. The lock member 26 includes a plurality of downwardly projecting locking teeth 27 which engage the upper toothed portion of the gear 24. The locking teeth 27 are configured to be generally rectangularly shaped as shown in FIGS. 3 and 7. Moreover, the locking teeth 27 protrude downwardly from a substantially planar bottom portion or surface 34 of the lock member 26. FIG. 7 depicts a side elevational view of the lock member 26 which shows the planar bottom portion of the lock member defining a line L from which the locking teeth 27 protrude. Since the locking teeth 27 are configured to be generally rectangularly shaped and have generally parallel side surfaces which protrude substantially perpendicularly from a substantially planar wall portion of the lock member 26, the locking teeth 27 and the gear 24 cooperate so as to provide for a more positive locking relationship therebetween which reduces the likelihood of accidental disengagement between the locking teeth 27 and the gear 24. 
     The lock member 26 is vertically slidably confined within the cartridge housing 16 by being slidably engaged and positioned between the bight or base wall of the channel-shaped housing 16 and the wall 22A of the tube 22 as shown in FIG. 3. A spring 29 coacts between the top wall of housing 16 and the locking member 26 for movably biasing the locking teeth 27 downwardly in perpendicular relation relative to the rotational axis of the gear 24 into a position of meshed engagement with gear 24 as illustrated in FIG. 3. The lock member 26 is thus confined for movement in a direction which is substantially perpendicular to the rotational axis of the gear 24. Also, the engaged or meshed relation between the locking teeth 27 and the teeth of gear 24 also occurs on or is substantially centered along a radial line which intersects the gear axis and which is substantially parallel with the movement direction of the lock member 26. 
     To provide a close fit of the lock member 26 in the cartridge housing 16, vertically spaced pairs of fins or ribs 40 and 41 are formed on opposite sides of the lock member 26. To ensure the correct orientation of the lock member 26, a horizontally spaced pair of projections 42 are formed on the cartridge housing 16. The fins 41 are formed vertically elongate so to be slidable between the projections 42. The fins 40, however, are T-shaped such that the horizontal legs thereof interfere with the projections 42 to insure the proper orientation of the lock member 26 as seen in FIG. 3. 
     The actuator rod 25 has its upper end coupled to an actuator lever 31. A first end of the actuator lever 31 is urged downwardly against the arm element 21 at a pivot point 30. A second end of the actuator lever 31 extends through an opening 32 defined in the arm element 21. Secured to the second end of the actuator lever 31 is a finger-engaging pad or button 33. The pad 33 is located adjacent to but under a forward end of the armrest 28 for easy engagement by an occupant&#39;s fingers. 
     In operation, when the occupant presses the pad 33 upwardly, the actuator rod 25 is pulled upwardly against the bias of spring 29 so as to disengage the locking teeth 27 from the gear 24, thus allowing gear 24 to roll along rack 14 to permit height adjustment of the armrest 28. When the occupant desires to lock the armrest 28 at a certain height position, the pad 33 is released and spring 29 urges the locking teeth 27 downwardly so as to automatically reengage the gear 24 when the gear teeth reach a position where they engage the slots defined between the locking teeth 27. 
     Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variation or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.