Abstract:
A rail adjustment device including an adjustment mechanism for adjusting and locating the rail. The adjustment mechanism includes a bar body having a locating section. Multiple pairs of notches are formed on opposite corners of the locating section. By means of swiveling the bar body, a locating member can be engaged in or disengaged from one of the notches. The locating member can be snugly engaged in the notch without swinging. This ensures good quality of the rail in use or operation.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention is related to a rail of a chair, and more particularly to a rail adjustment device.  
         [0002]      FIGS. 8 and 9  show a conventional rail adjustment mechanism of a chair. The adjustment mechanism includes a tubular body  7  having a slide channel  71 . The tubular body  7  is formed with multiple locating holes  72 . A bar member  81  and a cooperative iron plate  82  are mounted on a bracket  8 . The bracket  8  is fitted into the slide channel  71  of the tubular body  7 . The bar member  81  can be pulled to push a slope  821  of the iron plate  82 . At this time, the free end of the iron plate  82  will be lifted to retract a locating member  83  connected with the free end. At this time, the locating member is disengaged from the locating hole  72 , permitting the bar member  81  to freely slide within the tubular body  7  for adjusting the position of the rail pad  9 .  
         [0003]     In order to engage the locating member  83  in the locating hole  72 , a tolerance is preserved in the locating hole  72 . Therefore, the size of the locating hole  72  is slightly larger than the thickness of the locating member  83 . As a result, when engaged, the locating member  83  will be slightly loosened. This affects the quality of the rail.  
         [0004]     Moreover, the bar member  81  must precisely cooperate with the iron plate  82  for effectively pushing the slope  821  of the iron plate  82  to drive and totally disengage the locating member  83  from the locating hole  72 . Only under such circumstance, the bar member  81  can freely slide within the tubular body  7 . The high precision necessitates higher manufacturing cost.  
       SUMMARY OF THE INVENTION  
       [0005]     It is therefore a primary object of the present invention to provide a rail adjustment device including an adjustment mechanism for adjusting and locating the rail. The adjustment mechanism includes a bar body having a locating section. Multiple pairs of notches are formed on opposite corners of the locating section. By means of swiveling the bar body, a locating member can be engaged in or disengaged from one of the notches. The locating member can be snugly engaged in the notch without swinging. This ensures good quality of the rail in use or operation.  
         [0006]     It is a further object of the present invention to provide the above rail adjustment device which achieves the adjustment function by means of simple engagement structures. Therefore, no precise assembly or adaptation is required so that the manufacturing cost is lowered.  
         [0007]     According to the above objects, the rail adjustment device of the present invention includes:  
         [0008]     an inner tube having a fixed section at one end for fixing the inner tube on a chair, the other end of the inner tube having an insertion section;  
         [0009]     an outer tube slidably fitted around the inner tube, one end of the outer tube being expanded to form a connecting section, a window being formed on one side of the outer tube near the connecting section;  
         [0010]     an adjustment mechanism disposed in the inner tube and outer tube for adjustably driving the outer tube to reciprocally slide along the inner tube through a certain distance; and  
         [0011]     a rail pad, a lower side of the rail pad being connected with the connecting section of the outer tube, an upper side of the rail pad being for a user&#39;s hand to rest thereon.  
         [0012]     The rail adjustment device is characterized in that the adjustment mechanism includes a fixing member, a resilient member, a bar body, a locating member engageable with the bar body, a driving member, a handle fitted on the driving member for driving the bar body, wherein:  
         [0013]     the fixing member is connected in the connecting section of the outer tube, the fixing member having a coupling section connected with a connecting section of one end of the bar body, the resilient member being fitted on the coupling section and two ends of the resilient member being respectively connected with the fixing member and the bar body;  
         [0014]     the locating member is inserted in the insertion section of the inner tube, the locating member having an upper stop face and a lower stop face, the locating member being formed with a through hole along an axis of the bar body, whereby the bar body is fitted through the through hole; and  
         [0015]     a guide slot is obliquely formed on outer circumference of the connecting section of the bar body, a post being disposed on inner face of the driving member, whereby the post can be inlaid in the guide slot to drive the bar body, the bar body further having a locating section adjacent to the connecting section, multiple pairs of notches being formed on opposite corners of the locating section, each notch having an upper stop face and a lower stop face, the bar body further having a stop section extending from the locating section opposite to the connecting section.  
         [0016]     The upper and lower stop faces of the locating member respectively abut against the upper and lower stop faces of the notch of the bar body. Therefore, the locating member can be precisely engaged in the notch.  
         [0017]     The present invention can be best understood through the following description and accompanying drawings wherein:  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a perspective exploded view of the present invention;  
         [0019]      FIG. 2  is a perspective assembled view of the present invention;  
         [0020]      FIG. 3  is a sectional view of the adjustment mechanism of the present invention;  
         [0021]      FIG. 4  shows the engagement between the locating member and the notch of the locating section of the bar body of the present invention in one state;  
         [0022]      FIG. 5  shows the engagement between the locating member and the notch of the locating section of the bar body of the present invention in another state;  
         [0023]      FIG. 6  shows the disengagement between the locating member and the notch of the locating section of the bar body of the present invention in one state;  
         [0024]      FIG. 7  shows the disengagement between the locating member and the notch of the locating section of the bar body of the present invention in another state;  
         [0025]      FIG. 8  is a sectional view of a conventional rail adjustment mechanism of a chair in an engaged state; and  
         [0026]      FIG. 9  is a sectional view of the conventional rail adjustment mechanism of a chair in a disengaged state. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0027]     Please refer to  FIG. 1 . The rail adjustment device of the present invention includes an inner tube  1  having a fixed section  11  at one end for fixing the inner tube  1  on a chair. The other end of the inner tube  1  has an insertion section  12 .  
         [0028]     The rail adjustment device of the present invention further includes an outer tube  2  slidably fitted around the inner tube  1 . One end of the outer tube  2  is expanded to form a connecting section  21  having two wing sections. An upward protruding boss section  22  is disposed in each wing section. A window  23  is formed on one side of the outer tube  2  near the connecting section  21 . A linear slide channel  24  is formed on inner wall face of the outer tube  2  beside the window  23 .  
         [0029]     The rail adjustment device of the present invention further includes an adjustment mechanism  3  including a fixing member  31 . The fixing member  31  has two wings each having a through hole  311 . A coupling section  312  downward protrudes from the middle of the fixing member  31 . The present invention further includes a resilient member  32  which is a torque spring in this embodiment. The resilient member  32  serves to bear radial action force and has an upper connecting end  321  and a lower connecting end  322 . The present invention further includes a bar body  33 . One end of the bar body  33  has a connecting section  331 . A guide slot  332  is obliquely formed on outer circumference of the connecting section  331 . The bar body  33  further has a minified locating section  333  immediately under the connecting section  331 . Multiple pairs of notches  334  are formed on opposite corners of the locating section  333 . Each notch  334  has an upper stop face  335  and a lower stop face  336 . In addition, a stop section  337  downward extends from the locating section  333 . The. stop section  337  is swiveled about the axis of the bar body  33  by a certain angle. The present invention further includes a locating member  34  having an upper stop face  341  and a lower stop face  342 . The locating member  34  is formed with a through hole  343  along the axis of the bar body  33 . The bar body  33  is fitted through the through hole  343 . The present invention further includes a driving member  35  having a wing section  351 . A post  352  is disposed on inner face of the driving member  35 . A tongue plate  353  is disposed on outer face of the driving member  35 . A handle  36  is fitted on the tongue plate  353 .  
         [0030]     The present invention further includes a rail pad  4 . A lower side of the rail pad  4  is connected with the connecting section  21  of the outer tube  2 . A user&#39;s hand can rest on an upper side of the rail pad  4 .  
         [0031]     Referring to  FIG. 2 , when assembled, the locating member  34  of the adjustment mechanism  3  is first inserted in the insertion section  12  of the inner tube  1 . The resilient member  32  is fitted on the coupling section  312  of the fixing member  31 . Then the connecting section  331  of the bar body is coupled with the coupling section  312  of the fixing member  31 . The upper connecting end  321  of the resilient member  32  is fixed with the fixing member  31  and the lower connecting end  322  is fixed with the connecting section  331  of the bar body. The driving member  35  is placed into the outer tube  2  with the tongue plate  353  extending out through the window  23  of the outer tube  2 . The wing section  351  of the driving member  35  is slidably attached to the slide channel  24  of the outer tube  2 . then the handle  36  is fitted on the tongue plate  353  of the driving member  35  from outer side of the outer tube  2 .  
         [0032]     Then, the outer tube  2  is fitted around the inner tube  1 . Then the stop section  337  of the bar body  33  is aimed at the through hole  343  of the locating member  34  to fit the bar body  33  through the through hole  343  of the locating member  34 . After the stop section  337  is totally passed through the through hole  343 , the bar body  33  is swiveled by a certain angle, whereby the locating section  333  of the bar body  33  can further pass through the through hole  343  of the locating member  34 . When the guide slot  332  of the bar body  33  is nearly aligned with the window  23  of the outer tube  2 , the fixing member  31  is swiveled by a certain angle to fit the bosses  22  of the connecting section  21  of the outer tube  2  into the through holes  311  of two wings of the fixing member  31 . Accordingly, the post  352  of the driving member  35  can be inlaid in the guide slot  332  of the bar body  33 . Finally, the rail pad  4  is locked on the connecting section  21  of the outer tube with locking members.  
         [0033]     After the fixing member  31  is swiveled by a certain angle relative to the outer tube  2 , a torque is applied to the resilient member  32 . When the resilient member  32  restores to its home state, the resilient member  32  will exert a torque onto the bar body  33  and swivel the bar body  33 , whereby the locating member  34  can be engaged in the notch  334  of the locating section  333  of the bar body  33 . Accordingly, the rail can be lifted or lowered and located as shown in  FIG. 3 .  
         [0034]     The post  352  of the driving member  35  is inlaid in the guide slot  332  of the connecting section  331  of the bar body  33 . When the bar body  33  is swiveled by the resilient member  32 , the post  352  will be moved along the guide slot  332  to a lowermost end thereof and the driving member  35  abuts against lower side of the slide channel  24  of the outer tube  2  as shown in  FIGS. 4 and 5 . When adjusting the height of the rail, the handle  36  is shifted upward to drive the driving member  35  to upward abut against the slide channel  24  of the outer tube  2 . When the driving member  35  slides upward, the post  352  is moved upward within the guide slot  24 . At this time, the bar body  33  is forcedly swiveled to apply a torque onto the resilient member  32 . The bar body  33  is turned right and the locating member  34  is disengaged from the notch  334  of the locating section  333  as shown in  FIGS. 6 and 7 . Under such circumstance, the outer tube  2  can be slid up and down along the inner tube  1  to adjust the height of the rail. After adjusted, the resilient member  32  restores to its home state to again engage the locating member  34  in another notch  334  of the locating section  333 . At this time, the rail is located in a new height.  
         [0035]     The above embodiment is only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiment can be made without departing from the spirit of the present invention.