Abstract:
A height-adjustment mechanism may include an integral one-piece leverage body; an integral one-piece sleeve; and a locking member. In an embodiment, the integral one-piece leverage body has a handle, a pair of pivot pins projecting from opposed sides, a tongue projecting rearwardly, and a resilient biasing member projecting forwardly. These parts may be made of low cost materials suitable for integrally forming their features in an injection-moulding operation. Various features built in to these parts may provide a user with a sense of quality.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates generally to adjustable chairs, and more particularly to a height-adjustment mechanism for an armrest.  
         [0002]     Various designs for height-adjustable armrests are known. Some known designs require numerous parts and relatively expensive materials, making such designs less cost competitive. Other known designs include relatively few parts, making them generally less expensive, but such designs may not appear to be of a high quality.  
         [0003]     For example, U.S. Pat. No. 5,318,347 issued to Tseng (“Tseng &#39;347”) discloses a design for a height-adjustable armrest unit comprising an L-shaped support bar, a vertical sleeve, and a leverage body. In Tseng &#39;347, a tongue provided at a lower end of the leverage body is adapted to engage a positioning hole located on the support bar. The leverage body may be pivoted to disengage the tongue from the positioning hole to allow the sleeve (and the leverage body) to be vertically adjusted relative to the support bar. While Tseng &#39;347 may reduce product cost with fewer parts, the design may not provide a user with a sense that the armrest adjustment mechanism is of a high quality.  
         [0004]     Consequently, what is needed is a height-adjustment mechanism for an armrest which can be manufactured at a low cost, yet is long-lasting and capable of giving a user a sense of high quality.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention provides a height-adjustment mechanism for an armrest. In an embodiment, the height-adjustment mechanism includes an integral one-piece leverage body; an integral one-piece sleeve; and a locking member. These parts may be made of low cost materials suitable for integrally forming their features in an injection-moulding operation. Various features built into these parts may provide a user with a sense of quality.  
         [0006]     In an embodiment, the integral one-piece leverage body has a handle, a pair of pivot pins projecting from opposed sides, a tongue projecting rearwardly, and a resilient biasing member projecting forwardly.  
         [0007]     The leverage body may be elongate, with the handle located at an upper portion of said body, the tongue located at a lower portion of the body, and the pair of pivot pins located intermediately between the handle and the tongue.  
         [0008]     The leverage body may be made of a material suitable for integrally forming the handle, the pivot pins, the tongue and the resilient biasing member in an injection-moulding operation.  
         [0009]     The height-adjustment mechanism may further comprise an integral, one-piece sleeve having pivot seats receiving the pivot pins of the leverage body.  
         [0010]     The sleeve may be made of a material suitable for forming the pivot seats and the ribs in an injection-moulding operation.  
         [0011]     The height-adjustment mechanism may further comprise a support, and a plurality of ribs extending from inner walls of the sleeve to form a channel slidably receiving the support.  
         [0012]     The height-adjustment mechanism may further comprise a locking member locking the pivot pins of the leverage body in the pivot seats.  
         [0013]     The locking member may be formed of a material suitable for forming the locking member in an injection-moulding operation.  
         [0014]     Anti-rattling fingers may be provided to prevent rattling between the various parts of the height-adjustment mechanism.  
         [0015]     These and other aspects of the invention will become apparent through the illustrative figures and accompanying description provided below. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     In the figures which illustrate example embodiments of this invention:  
         [0017]      FIG. 1  is a view of an illustrative chair that may embody the invention.  
         [0018]      FIG. 2  is an exploded perspective view of a height-adjustment mechanism for an armrest in accordance with an embodiment of the invention.  
         [0019]      FIG. 3  is a cross sectional side view of the height-adjustment mechanism of  FIG. 2  showing the leverage body in a first position.  
         [0020]      FIG. 4  is the cross sectional side view of  FIG. 3  showing the leverage body in a second position.  
         [0021]      FIG. 5A  is a cross sectional side view of a portion of the height-adjustment mechanism of  FIG. 2 .  
         [0022]      FIG. 5B  is a cross sectional view of another embodiment of this invention.  
         [0023]      FIG. 6  is a cross sectional front view of a portion of the height-adjustment mechanism of  FIG. 2  showing a feature detail of yet another embodiment of the invention.  
         [0024]      FIGS. 7A-7E  are views of a feature detail of yet another embodiment of the invention.  
         [0025]      FIG. 8  is a perspective view of another embodiment of the leverage body of  FIG. 2 . 
     
    
     DETAILED DESCRIPTION  
       [0026]     Referring to  FIG. 1 , shown is an illustrative chair  11  that may embody the present invention. The chair  11  has a chair seat  13  mounted on a chair seat frame  10  and supported by a chair seat support  21 . A backrest  15  is supported on a backrest support  17 , and the backrest support  17  is mounted on the chair seat frame  10 . The chair  11  may further include a pair of armrests, each armrest including a height-adjustment mechanism  20  supported on an armrest support  30 .  
         [0027]      FIG. 2  shows an exploded perspective view of a height-adjustment mechanism  20  in accordance with an exemplary embodiment of the invention. As shown, the height-adjustment mechanism  20  may include a sleeve  40 , a leverage body  60 , and a locking member  70 . The sleeve  40 , with leverage body  60 , are adapted to mount to, and engage, the armrest support  30 , as explained below.  
         [0028]     In the exemplary embodiment, the support  30  is an L-shaped bar having a first arm  30   a  and a second arm  30   b . In use, the first arm  30   a  is generally horizontally oriented and may include a plurality of mounting holes  32  for mounting the support  30  to the chair seat frame  10  (using mounting screws, not shown). The generally vertically oriented second arm  30   b  of the support  30  may include a plurality of vertically spaced slots  34 . In an embodiment, a vertical groove  36  may join all of the slots  34 . As will be explained further below, a protruding tongue  64  formed on a lower portion of the leverage body  60  is adapted to selectively engage one of the slots  34 , and the vertical position of the slot  34  engaged by the tongue  64  will determine the vertical position of the height-adjustment mechanism  20 .  
         [0029]     In order to support the height-adjustment mechanism  20 , and the weight placed on the height-adjustment mechanism  20  by an occupant of the chair  11 , the support  30  should be made of a sufficiently strong and rigid material. For example, in the exemplary embodiment, an elongate plate made of steel, or another suitable metal, may be used. Other materials such as reinforced plastics and carbon composites may also be used.  
         [0030]     Still referring to  FIG. 2 , the sleeve  40  may be formed as an integral, single-piece, injection-moulded structure. For example, the sleeve  40  may be formed of a plastic material that may be injection-moulded in the desired shape. As shown, the sleeve  40  is adapted to be vertically oriented in use and has an upper end  42  and a lower end  43 . The lower end  43  of the sleeve  40  has an opening  44  suitably sized to receive the generally vertically oriented second arm  30   b  of the armrest support  30 . The upper end  42  of the sleeve  40  is suitably shaped to receive an armrest pad  50  ( FIG. 3 ). Mounting holes  41   a  and  41   b  are provided at the upper end  42  of the sleeve  40  to mount the armrest pad  50  (using mounting screws, not shown).  
         [0031]     Still referring to  FIG. 2 , the sleeve  40  is shown in a partial cutout view with an arrangement of structural reinforcing ribs located on each inside wall of the sleeve  40 . A first pair of reinforcing ribs  48   a ,  48   b  is located on a first inside wall  48  of the sleeve  40 . A second pair of reinforcing ribs  52   a ,  52   b  is provided on an opposite inside wall  52  of the sleeve  40 . Additional reinforcing ribs  54   a  and  56   a  are provided on inner side walls  54  and  56 , respectively, which extend between the first and second walls  48  and  52 .  
         [0032]     Together, the edges of the reinforcing ribs  48   a ,  48   b ,  52   a ,  52   b ,  54   a  and  56   a  form a “channel”  45 . As shown, the channel  45  is aligned with opening  44  to slidably receive the vertically oriented second arm  30   b  of the support  30 .  
         [0033]     Still referring to  FIG. 2 , a notch  58  is provided at the top of the first wall  48  of the sleeve  40 . As shown, the notch  58  is substantially centered between the reinforcing ribs  48   a  and  48   b  and suitably sized to allow a portion of the leverage body  60 , namely the handle  68 , to extend outside the sleeve  40 . A pair of pivot seats  53   a  and  53   b  are provided at the top of the reinforcing ribs  48   a  and  48   b  to position the handle of the leverage body  60  through the notch  58 . The leverage body  60  is then free to pivot about the pivot seats  53   a ,  53   b  when the handle  68  is moved by an operator.  
         [0034]     In the exemplary embodiment, a pair of mounting posts  59   a  and  59   b  is integrally formed on the sleeve  40  and are located adjacent the pivot seats  53   a ,  53   b . These mounting posts  59   a ,  59   b  may be used to lock the leverage body  60  in position, using a locking member  70 , as described further below.  
         [0035]     Still referring to  FIG. 2 , the leverage body  60  is formed as an integral, single-piece, injection-moulded body. For example, the leverage body  60  may be made of a plastic material injection-moulded into the desired shape. In the exemplary embodiment, the leverage body has a generally elongate body with a pair of pivot pins  62   a ,  62   b  located intermediately along its length. The tongue  64 , as mentioned earlier, protrudes from a lower portion of the elongate leverage body  60 . Also, a biasing member  66  is integrally formed with the leverage body  60  and extends outwardly in a direction opposite the tongue  64 . As mentioned, a handle  68  is provided at an upper end of the leverage body  60 . The handle  68  allows an operator to pivot the leverage body  60  about the pivot pins  62   a ,  62   b . In operation, the biasing member  66  provides a biasing force, acting against the force applied by the operator to the handle  68  of the leverage body  60 .  
         [0036]     With the integral, one-piece, injection-moulded leverage body  60 , advantageously, the most wearable parts—the protruding tongue  64 , the pivot pins  62   a ,  62   b , and the biasing member  66 —are all provided on one smaller part which, at the end of its life, may be readily replaced at relatively little cost.  
         [0037]     Still referring to  FIG. 2 , the locking member  70  is preferably formed as an integral, single-piece, injection-moulded body. For example, the locking member  70  may be made of a plastic material that may be injection-moulded into the desired shape. In the exemplary embodiment, the locking member  70  has a frame  72  having first and second arms  72   a ,  72   b . At the end of each arm  72   a ,  72   b , first and second pivot caps  73   a ,  73   b  are formed to engage the top of pivot pins  62   a ,  62   b , when these pivot pins  62   a ,  62   b  are seated in the pivot seats  59   a ,  59   b . The locking member  70  may further include first and second laterally extending wings  76   a ,  76   b  provided with mounting holes  78   a  and  78   b , respectively. As shown in  FIG. 3 , these mounting holes  78   a  and  78   b  may be received by mounting posts  59   a  and  59   b  formed on the sleeve  40  to mount the locking member  70  to the sleeve  40 . If the leverage body  60  is placed such that pivot pins  62   c ,  62   b  are received by pivot seats  53   a ,  53   b , and the locking member  70  is mounted, locking member  70  locks the pivot pins  62   a  and  62   b  in place, while still allowing the leverage body  60  to pivot.  
         [0038]     In an embodiment, the locking member  70  may be suitably sized and shaped such that, once mounted, the top of its frame  72  is substantially flush with the top  42  of the sleeve  40 . Thus, when an armrest pad  50  is secured to the top of the sleeve  40  (for example by mounting screws mounted through mounting holes  41   a  and  41   b ), the locking member  70  may be held securely in position on the mounting posts  59   a  and  59   b . The laterally extending wings  76   a ,  76   b  of the locking member  70  may be suitably sized and shaped such that these laterally extending wings  76   a ,  76   b  engage one or more of the reinforcing ribs within the sleeve  40 . This may further reinforce the locking member  70  laterally, such that the leverage body  60  is held securely in position.  
         [0039]     In another embodiment, once the locking member  70  has been mounted in position on the mounting posts  59   a ,  59   b , the tip of the mounting posts may be deformed, for example by the application of heat, such that the locking member  70  is locked on the mounting posts  59   a ,  59   b . This is advantageous where the height-adjustment mechanism  20  may be shipped as a unit prior to its incorporation in a chair. In other circumstances, as the locking member  70  may be kept securely in position by mounting the armrest pad  50 , and by lateral reinforcement of the reinforcing ribs, the mounting posts  59   a ,  59   b  may be left as is such that the leverage body  60  may be readily replaced, if necessary.  
         [0040]     The height adjustment operation of the height-adjustment mechanism  20  will now be explained.  
         [0041]     Referring to  FIG. 3 , the sleeve  40  is shown mounted on the vertically oriented second arm  30   b  of the armrest support  30 . The leverage body  60  is shown with its pivot pins  62   a  and  62   b  seated within the pivot seats  53   a  and  53   b  and secured thereat by the locking member  70 .  
         [0042]     As shown in  FIG. 3 , the handle  68  of the leverage body  60  extends through the notch  58  in the first wall  48  of sleeve  40 . Within the sleeve  40 , the biasing arm  66  of leverage body  60  engages the first wall  48  and biases the leverage body  60  away from the first wall  48 . When the leverage body  60  is not actuated by an operator, the biasing force provided by the biasing arm  66  causes the tongue  64  protruding from the lower arm of the leverage body  60  to continuously engage one of the slots  34  in the support  30 . As noted earlier, the vertical position of the slot  34  engaged by the tongue  64  determines the vertical height of the height-adjustment mechanism  20 .  
         [0043]     As shown in  FIG. 4 , in order to adjust the height of the height-adjustment mechanism  20 , the handle  68  of leverage body  60  may be lifted or pulled back by an operator in direction A. This action by the operator will cause the leverage body  60  to pivot about pivot pins  62   a  and  62   b , against the biasing force of the resiliently flexible biasing arm  66 . The biasing arm  66  is resiliently deformed when the handle  68  is lifted by the operator such that the biasing arm  66  will act to reengage the tongue  64  with one of the slots  34  when the handle  68  is released.  
         [0044]     In one embodiment, the tongue  64  includes a base  64   a , and a tip  64   b . As shown, when the leverage body  60  is pivoted about pivot pins  62   a  and  62   b , the base  64   a  of the tongue  64  disengages from the slots  34 , as shown at B. However, the tip  64   b  of the tongue  64  remains engaged in the vertical groove  36  ( FIG. 2 ). As the vertical groove  36  runs the length of the slots  34 , the leverage body  60  and the sleeve  40  may be adjusted vertically, as indicated at C, relative to the support  30 . The tongue  64  continuously guides the leverage body  60  within the vertical groove  36 , thereby allowing the base  64   a  of tongue  64  to more readily engage any one of the slots  34  when the operator finally releases the handle  68 .  
         [0045]     In an embodiment, the vertical adjustment of the height-adjustment mechanism  20  by the operator may be limited at an upper and lower limit by the tip  64   b  of the tongue  64  engaging the top and bottom of the slot  36 .  
         [0046]     Referring to  FIG. 5A , in an embodiment, an offset  38  may be formed in the support  30  at the top of the vertical groove  36  to accommodate and guide the tip  64   b  of the tongue  64  of the leverage body  60  when the height-adjustment mechanism  20  is first slidably received on the support  30 . When this offset  38  is provided, a separate feature may be provided to limit vertical adjustment of the height-adjustment mechanism  20 . For example, a protuberance  39  (seen from the back in  FIG. 2 ) may be formed and suitably located on the vertically oriented second arm  30   b  of the support  30 . The protuberance  39  may be ramped in a downward direction such that an inwardly extending part  45  of sleeve  40  will deform and pass over the protuberance  39  on the way down, when the sleeve  40  is first installed, but the inwardly extending part  45  of sleeve  40  will catch on the protuberance  39  on the way up. Thus, the protuberance  39  may prevent the height-adjustment mechanism  20  from being inadvertently lifted clear off the support  30  by the operator.  
         [0047]     Referring to  FIG. 5B , as shown in this alternative embodiment, the offset  38  of  FIG. 5A  may be absent. In this case, in order to assist in fitting the tip  64   b  of the tongue  64  over the top of the support  30  and into the vertical groove  36  ( FIG. 2 ) during assembly, a ramped surface  64   c  may be provided on the lower portion of the tip  64   b . As the tip  64   b  otherwise remains the same, the tip  64   b  having the ramped surface  64   c  may continue to engage the vertical groove  36 , as described above.  
         [0048]     Referring to  FIG. 6 , in a further embodiment, a flexibly resilient anti-rattling finger  46  may be formed on one of the inner side walls  54 ,  56  of the sleeve  40  to flexibly bias the support  30  against the opposite one of the inner side walls  54 ,  56  of the sleeve  40 . In operation, the anti-rattling finger  46  acts to reduce or prevent rattling between the sleeve and the support  30 , providing the operator of the height-adjustment mechanism  20  with a more smooth and solid feel.  
         [0049]     Referring to  FIGS. 7A-7E , in a further embodiment, rather than moulding a resilient finger  46  in sleeve  40 , the sleeve  40  may be moulded to include a track  82  along a length of a reinforcing rib  54   b ′. As shown in  FIG. 7   d , the track  82  may have retaining walls  83  to retain an insert  84  having a plurality of projecting anti-rattling fingers  86 . The anti-rattling fingers  86  extend to abut an edge of the support  30 . The anti-rattling fingers  86  are resiliently flexible and may be suitably shaped and sized so they will push the support  30  against the opposite side of the channel  45  ( FIG. 2 ) of sleeve  40  to remove any tolerances between the sleeve  40  and the support  30 . In this regard, the insert  84  may be made integrally formed of a resilient plastic material. Advantageously, the anti-rattling fingers  86  may provide a smooth gliding action when the height-adjustment mechanism  20  is adjusted. In order to keep the insert  84  from sliding out of the track  82 , a suitable cap may be provided on top of the track  82 . For example, as shown in  FIG. 7   e , an extension  79  may provided on the locking member  70  in order to contain the insert  84  within the track  82 .  
         [0050]     In yet another embodiment, as shown in  FIG. 8 , an alternative leverage body  60 ′ has a biasing member  66 ′ extending from a bottom end, rather than extending from an intermediate region (as shown at  60  in  FIG. 2 ). It will be apparent that this alternative leverage body  60 ′ is interchangeable with the leverage body  60  of  FIG. 2 . It will also be apparent that a biasing member may be integrally formed on the leverage body  60  at various other locations, and that such a biasing member may be embodied in various other configurations.  
         [0051]     While an exemplary embodiment of the invention has been shown and described, it will be apparent to those skilled in the art that various modifications and alterations may be made. Therefore, the invention is defined in the following claims.