Patent Publication Number: US-7896440-B2

Title: Chair armrest having a height adjustable function

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an armrest and, more particularly, to an armrest for a chair. 
     2. Description of the Related Art 
     A conventional chair comprises a seat, a stand mounted on the bottom of the seat, two armrests mounted on the top of the seat, and a backrest mounted on the top of the seat and located between the two armrests. However, each of the two armrests of the chair has a fixed structure, so that the height of each of the two armrests cannot be adjusted according to a user&#39;s requirement. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided an armrest for a chair, comprising an armrest support, a sleeve movably and adjustably mounted on the armrest support, a support arm mounted on the sleeve to move with the sleeve, a locking member secured in the armrest support and located in the sleeve, and a lifting device mounted between the armrest support and the sleeve and operable between a first position where the lifting device is locked by the locking member to lock the sleeve onto the armrest support and a second position where the lifting device is unlocked from the locking member to unlock the sleeve from the armrest support so that the sleeve is movable relative to the armrest support freely. 
     The primary objective of the present invention is to provide an armrest for a chair, wherein when the drive knob of the drive lever is pressed upward, the movable shaft is unlocked from the locking member so that the movable shaft is movable in the locking member and the support post of the armrest support freely, and the sleeve is movable relative to the support post of the armrest support to adjust the height of the support arm. 
     Another objective of the present invention is to provide an armrest for a chair, wherein a user only needs to press the drive knob of the drive lever so as to adjust the height of the support arm so that the height of the support arm is adjusted easily and quickly in an energy-saving manner, thereby facilitating the user adjusting the height of the support arm  6 . 
     A further objective of the present invention is to provide an armrest for a chair, wherein when the sleeve is movable relative to the support post of the armrest support, the pressing pin is pushed by the elastic member to press the inner wall of the sleeve to prevent the sleeve from being vibrated or swayed during movement of the sleeve on the support post of the armrest support. 
     A further objective of the present invention is to provide an armrest for a chair, wherein the elastic member provides a buffering effect to the sleeve so that the sleeve is movable on the support post of the armrest support smoothly and stably. 
     Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG. 1  is a perspective view of an armrest for a chair in accordance with the preferred embodiment of the present invention. 
         FIG. 2  is an exploded perspective view of the armrest for a chair as shown in  FIG. 1 . 
         FIG. 3  is an exploded perspective view of a lifting device of the armrest for a chair as shown in  FIG. 2 . 
         FIG. 4  is an another exploded perspective view of the lifting device of the armrest for a chair as shown in  FIG. 2 . 
         FIG. 5  is a front assembly view of the lifting device of the armrest for a chair as shown in  FIG. 3 . 
         FIG. 6  is a front cross-sectional view of the armrest for a chair taken along line  6 - 6  as shown in  FIG. 1 . 
         FIG. 7  is a schematic operational view of the armrest for a chair as shown in  FIG. 5 . 
         FIG. 8  is a schematic operational view of the armrest for a chair as shown in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and initially to  FIGS. 1-7 , an armrest for a chair in accordance with the preferred embodiment of the present invention comprises an armrest support  1 , a sleeve  4  movably and adjustably mounted on the armrest support  1 , a support arm  6  mounted on the sleeve  4  to move with the sleeve  4 , a locking member  2  secured in the armrest support  1  and located in the sleeve  4 , and a lifting device  3  mounted between the armrest support  1  and the sleeve  4  and operable between a first position where the lifting device  3  is locked by the locking member  2  to lock the sleeve  4  onto the armrest support  1  and a second position where the lifting device  3  is unlocked from the locking member  2  to unlock the sleeve  4  from the armrest support  1  so that the sleeve  4  is movable relative to the armrest support  1  freely. 
     The armrest support  1  includes an upright support post  11  having an inside provided with a receiving chamber  111  to receive the lifting device  3  and a transverse connecting member  10  mounted on a lower end of the support post  11 . The receiving chamber  111  of the support post  11  has a substantially oblong profile. The support post  11  of the armrest support  1  has an upper end provided with two opposite pin holes  112  and a passage  113 . 
     The locking member  2  is mounted on the upper end of the support post  11  and is received in the receiving chamber  111  of the support post  11 . The locking member  2  has a substantially oblong cross-sectional profile matching that of the receiving chamber  111  of the support post  11  so that the locking member  2  is secured in the receiving chamber  111  of the support post  11  to prevent the locking member  2  from being rotated relative to the support post  11 . 
     The locking member  2  is provided with a semi-circular locking hole  20  which has a planar locking side  25  which is provided with at least one engaging groove  21 . The locking member  2  is further provided with a pin bore  22 , and the armrest further comprises a positioning pin  24  extending through the pin holes  112  of the support post  11  and the pin bore  22  of the locking member  2  to fix the locking member  2  on the support post  11  of the armrest support  1 . The locking member  2  has a side provided with a receiving recess  23 , and the armrest further comprises a pressing pin  13  movably mounted in the passage  113  of the support post  11  and pressing an inner wall of the sleeve  4  to prevent the sleeve  4  from being vibrated or swayed when the sleeve  4  is movable relative to the support post  11  of the armrest support  1 , and an elastic member  12  mounted in the receiving recess  23  of the locking member  2  and biased between the locking member  2  and the pressing pin  13  to push the pressing pin  13  toward the sleeve  4 . The pressing pin  13  is partially received in the receiving recess  23  of the locking member  2 . 
     The lifting device  3  includes a positioning member  33  located in an upper end of the sleeve  4  to move with the sleeve  4 , a movable shaft  30  rotatably mounted on the positioning member  33  and detachably locked in the locking hole  20  of the locking member  2  by rotation of the movable shaft  30  relative to the locking member  2 , a drive lever  31  pivotally mounted on the positioning member  33  and connected with the movable shaft  30  to drive the movable shaft  30  to rotate relative to the locking member  2  by pivot of the drive lever  31  relative to the positioning member  33 , and a restoring member  32  biased between the positioning member  33  and the drive lever  31  and to push the drive lever  31  to pivot relative to the positioning member  33 . 
     The armrest further comprises a mounting plate  5  secured on the upper end of the sleeve  4  to move with the sleeve  4 , and the positioning member  33  of the lifting device  3  is secured on the mounting plate  5  to move with the mounting plate  5 . 
     The movable shaft  30  of the lifting device  3  is an elongate rod and has a surface provided with a plurality of locking teeth  306  detachably engaged with the engaging groove  21  of the locking side  25  of the locking hole  20  of the locking member  2  and a planar side  307  located beside the locking teeth  306 . The movable shaft  30  of the lifting device  3  has a periphery provided with a transverse drive rod  304 . 
     Thus, the movable shaft  30  of the lifting device  3  is rotatable relative to the locking member  2  between a first position as shown in  FIG. 6  where the locking teeth  306  of the movable shaft  30  align with and are locked by the engaging groove  21  of the locking side  25  of the locking hole  20  of the locking member  2  to lock the movable shaft  30  onto the locking member  2  and a second position as shown in  FIG. 8  where the planar side  307  of the movable shaft  30  aligns with and movably rests on the locking side  25  of the locking hole  20  of the locking member  2  to unlock the movable shaft  30  from the locking member  2  so that the movable shaft  30  is movable in the locking member  2  and the support post  11  of the armrest support  1  freely, and the sleeve  4  is movable on the support post  11  of the armrest support  1  freely. 
     The drive lever  31  of the lifting device  3  has a first end provided with a protruding push portion  311  which is movable relative to the movable shaft  30  to move the drive rod  304  of the movable shaft  30  and to drive and rotate the movable shaft  30  relative to the locking member  2 , a second end provided with a protruding drive knob  315  to drive and pivot the drive lever  31  relative to the positioning member  33 , and a mediate portion located between the push portion  311  and the drive knob  315  and pivotally mounted on the positioning member  33 . The push portion  311  of the drive lever  31  is movable by pivot of the drive lever  31  relative to the positioning member  33  and is provided with an elongated guide slot  312  slidably mounted on the drive rod  304  of the movable shaft  30  to guide movement of the drive rod  304  of the movable shaft  30  relative to the drive lever  31 . The guide slot  312  of the push portion  311  is inclined relative to the drive lever  31  of the lifting device  3 . The mediate portion of the drive lever  31  is provided with a pivot hole  313 . The second end of the drive lever  31  has a top provided with a receiving chamber  314  to receive the restoring member  32 . 
     The positioning member  33  of the lifting device  3  has an inside provided with a through hole  332 . The positioning member  33  of the lifting device  3  has a periphery provided with two opposite protruding ears  330  each provided with a screw hole  331 . The positioning member  33  of the lifting device  3  has a bottom provided with a receiving space  333  to receive the restoring member  32 . The receiving space  333  of the positioning member  33  has a wall provided with a protruding positioning post  334  inserted into the restoring member  32  to position the restoring member  32 . The positioning member  33  of the lifting device  3  has two opposite sidewalls each provided with a fixing hole  335 , and the armrest further comprises a pivot pin  35  extending through the fixing holes  335  of the positioning member  33  and the pivot hole  313  of the drive lever  31  so that the mediate portion of the drive lever  31  is pivotally mounted in the positioning member  33 . 
     The movable shaft  30  of the lifting device  3  is movable in the locking hole  20  of the locking member  2  and the receiving chamber  111  of the support post  11 . The movable shaft  30  of the lifting device  3  has an upper end provided with a reduced rotation rod  301  rotatably mounted in the through hole  332  of the positioning member  33 . The rotation rod  301  of the movable shaft  30  is provided with a screw bore  303 , and the armrest further comprises a fastening screw  34  extending through the through hole  332  of the positioning member  33  and screwed into the screw bore  303  of the rotation rod  301  to attach the movable shaft  30  to the positioning member  33 . The drive rod  304  of the movable shaft  30  is located on the upper end of the movable shaft  30  and is movable to abut a top of the locking member  2  to stop movement of the movable shaft  30  relative to the locking member  2 . The movable shaft  30  of the lifting device  3  has a lower end provided with an enlarged bottom edge  305  that is movable to abut a bottom of the locking member  2  to stop movement of the movable shaft  30  relative to the locking member  2  and to prevent the movable shaft  30  of the lifting device  3  from being detached from the locking member  2  and the support post  11  of the armrest support  1 . The locking teeth  306  and the planar side  307  of the movable shaft  30  is located between the drive rod  304  and the bottom edge  305  of the movable shaft  30 . The bottom edge  305  of the movable shaft  30  has a semi-circular shape. 
     The sleeve  4  is movably mounted on the support post  11  of the armrest support  1  and has an inside provided with a receiving hole  40  mounted on the support post  11  of the armrest support  1 . The upper end of the sleeve  4  has a periphery provided with a plurality of screw bores  41 . The upper end of the sleeve  4  has a surface provided with an exposing slot  42 , and the drive knob  315  of the drive lever  31  protrudes outwardly from the exposing slot  42  of the sleeve  4 . 
     The mounting plate  5  is provided with a plurality of through bores  53 , and the armrest further comprises a plurality of fixing screws  54  each extending through a respective one of the through bores  53  of the mounting plate  5  and each screwed into a respective one of the screw bores  41  of the sleeve  4  to secure the mounting plate  5  to the sleeve  4 . The mounting plate  5  is further provided with two through holes  50 , and the armrest further comprises two locking screws  56  each extending through a respective one of the through holes  50  of the mounting plate  5  and each screwed into the screw hole  331  of a respective one of the protruding ears  330  of the positioning member  33  to secure the positioning member  33  to the mounting plate  5 . The mounting plate has a top provided with a protruding mounting stud  51  which is provided with a screw bore  52  for fixing the support arm  6  to the mounting plate  5 . 
     In operation, referring to  FIGS. 5-8  with reference to  FIGS. 1-4 , when the locking teeth  306  of the movable shaft  30  align with the locking side  25  of the locking hole  20  of the locking member  2 , the locking teeth  306  of the movable shaft  30  are locked by the engaging groove  21  of the locking side  25  of the locking hole  20  of the locking member  2  as shown in  FIG. 6  to lock the movable shaft  30  onto the locking member  2 , so that the sleeve  4  is fixed on the support post  11  of the armrest support  1 . At this time, the drive rod  304  of the movable shaft  30  is located at a lower end of the guide slot  312  of the drive lever  31  as shown in  FIG. 5  when the locking teeth  306  of the movable shaft  30  align with the locking side  25  of the locking hole  20  of the locking member  2  as shown in  FIG. 6 . 
     When the drive knob  315  of the drive lever  31  is pressed toward the positioning member  33  to compress the restoring member  32  and to drive and pivot the drive lever  31  relative to the positioning member  33  as shown in  FIG. 7 , the push portion  311  of the drive lever  31  is moved outwardly relative to the positioning member  33  to move the drive rod  304  of the movable shaft  30  and to drive and rotate the movable shaft  30  relative to the locking member  2 , until the planar side  307  of the movable shaft  30  aligns with the locking side  25  of the locking hole  20  of the locking member  2  as shown in  FIG. 8  so as to unlock the movable shaft  30  from the locking member  2 , so that the movable shaft  30  is movable in the locking member  2  and the support post  11  of the armrest support  1  freely, and the sleeve  4  is movable on the support post  11  of the armrest support  1  freely. In such a manner, the sleeve  4  is movable relative to the support post  11  of the armrest support  1  to adjust the height of the support arm  6 . 
     At this time, when the drive rod  304  of the movable shaft  30  is driven by the push portion  311  of the drive lever  31 , the drive rod  304  of the movable shaft  30  is slidable in the guide slot  312  of the drive lever  31 , so that the drive rod  304  of the movable shaft  30  is located at an upper end of the guide slot  312  of the drive lever  31  as shown in  FIG. 7  when the planar side  307  of the movable shaft  30  aligns with the locking side  25  of the locking hole  20  of the locking member  2  as shown in  FIG. 8 . 
     After the force applied on the drive lever  31  disappears, the drive knob  315  of the drive lever  31  is pushed outwardly relative to the positioning member  33  by the restoring force of the restoring member  32  as shown in  FIG. 5 , to drive and pivot the drive lever  31  relative to the positioning member  33 , and the push portion  311  of the drive lever  31  is moved toward the positioning member  33  to move the drive rod  304  of the movable shaft  30  and to drive and rotate the movable shaft  30  relative to the locking member  2 , until the locking teeth  306  of the movable shaft  30  align with the locking side  25  of the locking hole  20  of the locking member  2 , so that the locking teeth  306  of the movable shaft  30  are locked by the engaging groove  21  of the locking side  25  of the locking hole  20  of the locking member  2  as shown in  FIG. 6  to lock the movable shaft  30  onto the locking member  2 , and the sleeve  4  is fixed on the support post  11  of the armrest support  1  again. 
     Accordingly, when the drive knob  315  of the drive lever  31  is pressed upward, the movable shaft  30  is unlocked from the locking member  2  so that the movable shaft  30  is movable in the locking member  2  and the support post  11  of the armrest support  1  freely, and the sleeve  4  is movable relative to the support post  11  of the armrest support  1  to adjust the height of the support arm  6 . In addition, a user only needs to press the drive knob  315  of the drive lever  31  so as to adjust the height of the support arm  6  so that the height of the support arm  6  is adjusted easily and quickly in an energy-saving manner, thereby facilitating the user adjusting the height of the support arm  6 . Further, when the sleeve  4  is movable relative to the support post  11  of the armrest support  1 , the pressing pin  13  is pushed by the elastic member  12  to press the inner wall of the sleeve  4  to prevent the sleeve  4  from being vibrated or swayed during movement of the sleeve  4  on the support post  11  of the armrest support  1 . Further, the elastic member  12  provides a buffering effect to the sleeve  4  so that the sleeve  4  is movable on the support post  11  of the armrest support  1  smoothly and stably. 
     Although the invention has been explained in relation to its preferred embodiment(s) as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claim or claims will cover such modifications and variations that fall within the true scope of the invention.