Patent Publication Number: US-2009226248-A1

Title: Quick-Release Coupler

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a quick-release coupler and, more particularly, to a quick-release coupler for securely coupling a bit to a pneumatic tool. 
       FIG. 1  shows a conventional quick-release coupler  2  and a bit  1  coupled to the quick-release coupler  2 . Bit  1  includes a driving end  12  for driving a screw or the like and a socket portion  11  having a coupling hole  111 . A recessed portion  112  is formed in each of four side walls defining coupling hole  1 . Quick-release coupler  2  includes a first end  21  for coupling with a hand-held tool such as a pneumatic tool (not shown) and a second end  22  having a receptacle  221  in which a spring  23  and a ball  24  are received. Ball  24  is biased by spring  23  such that an outermost portion  241  of ball  24  projects out of receptacle  221  and engages in one of recessed portions  112  of bit  1  when coupling hole  111  of bit  1  couples to second end  22  of quick-release coupler  4 . Thus, bit  3  is locked on quick-release coupler  4  and can be driven when first end  21  of quick-release coupler  2  secured to the pneumatic tool rotates. 
     To remove bit  1  from quick-release coupler  2 , a user generally grasps bit  1  and a handle of the pneumatic tool to pull them away from each other to make ball  24  retract into receptacle  221  to allow removal of bit  1  from quick-release coupler  2 . However, it is sometimes difficult to remove bit  1  from quick-release coupler  2 , particularly when ball  24  is jammed or the hands of the user are greasy. Moreover, bit  1  may be disengaged from quick-release coupler  2  during operation of the pneumatic tool when the resilience of spring  23  decreases. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide a quick-release coupler to allow secure attachment and easy removal of a bit to and from a hand-held tool such as a pneumatic tool. 
     A quick-release coupler according to the preferred teaching of the present invention includes a rod, a sleeve slidably mounted around the rod, a ball, and a spring. The rod includes a first end for coupling with a pneumatic tool and a second end having a recess. The recess includes a first, shallower contact section and a second, deeper contact section. The sleeve includes a first end, a second end adapted to couple with a bit and an axial bore extending from the first end through the second end for receiving the rod. The ball is movably received in the radial bore of sleeve along a vertical axis of the rod and moveably received in the recess of the rod along a longitudinal axis of the rod to engage the sleeve with the rod. The spring is mounted in the axial bore of the sleeve for biasing the sleeve towards the second end of the rod. The sleeve is moveable relative to the rod along the longitudinal axis of the rod between an extended, first position biased by the spring and a retracted, second position compressing the spring. The ball is engaged in the first contact section of the recess and an outermost portion of the ball projects out of the radial bore of the sleeve when the sleeve is in the extended, first position. The ball is engaged in the second contact section of the recess and does not project out of the radial bore of the sleeve when the sleeve is in the retracted, second position. 
     The present invention will become clearer in light of the following detailed description of an illustrative embodiment of this invention described in connection with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The illustrative embodiment may best be described by reference to the accompanying drawings where: 
         FIG. 1  is a partly cross-sectioned side view of a conventional quick-release coupler with a bit shown attached thereto. 
         FIG. 2  shows a cross sectional view of a quick-release coupler according to the present invention with a bit attached thereto. 
         FIG. 3  shows an exploded perspective view of the quick-release coupler and the bit of  FIG. 2 . 
         FIG. 4  shows a cross sectional view of the quick-release coupler and the bit of  FIG. 2  before engagement. 
         FIG. 5  shows a diagrammatic side view of the quick-release coupler and the bit of  FIG. 2  and a pneumatic tool to which the quick-release coupler is coupled. 
         FIG. 6  is a cross sectional view taken along plane  6 - 6  in  FIG. 2 . 
         FIG. 7  is a view similar to  FIG. 4 , wherein the bit is being coupled with the quick-release coupler. 
         FIG. 8  is a view similar to  FIG. 7 , wherein the bit is moved to push a sleeve of the quick-release coupler in a retracted position, and a ball is received in the bit. 
         FIG. 9  is a view similar to  FIG. 8 , wherein the bit is moved to be in contact with a radial flange of the sleeve of the quick-release couple. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A quick-release coupler according to the preferred teachings of the present invention is shown in  FIGS. 2 through 9  of the drawings and is designated  4 . Quick-release coupler  4  includes a rod  41 , a sleeve  42 , a ball  44 , and a spring  43 . 
     Rod  41  includes a first end  411  having an annular groove  413  by which rod  41  can be secured to a coupling end  51  of a pneumatic tool  5  ( FIG. 5 ). Rod  41  further includes a second end  412  having a recess  415 . Recess  415  includes a first, inclined contact section  416  adjacent to an end face  418  of second end  412  and a second contact section  417  extending toward first end  411  from a lower end of first contact section  416 . Second end  412  has a diameter smaller than that of first end  411 , and a shoulder  414  is formed between first and second ends  411  and  412 . 
     Sleeve  42  is slidably mounted around rod  41  and includes a first end  421 , a second end  422  adapted to couple with a bit  3 , and an axial bore  423  extending from first end  421  through second end  422 . Several grooves  428  are provided on an outer periphery of first end  421  of sleeve  42  for secure holding by a user. Axial bore  423  includes an enlarged section  424  formed in first end  421  and having an end face  427 . A radial bore  425  in communication with axial bore  423  is provided in second end  422  and generally aligns with recess  415  of second end  412  of rod  41 . In this illustrated embodiment, second end  422  of sleeve has rectangular cross sections, and a radial flange  426  is formed between first and second ends  421  and  422  of sleeve  42 . 
     Bit  3  includes a driving end  32  for driving a screw or the like and a socket portion  31  having a rectangular coupling hole  311  ( FIG. 6 ). Coupling hole  311  of bit  3  can engage second end  422  of sleeve  42 . A recessed portion  312  is formed in each of four side walls defining coupling hole  311 . 
     Ball  44  is movably received in radial bore  425  of sleeve  42  along a vertical axis of the rod  41 . A ring  45  is mounted in an outer end of radial bore  425  and has a diameter less than that of ball  44  so that only part of ball  44  can project out of radial bore  425  of sleeve  42 . Ball  44  is also received in recess  415  of rod  41  to engage sleeve  42  with rod  41  and movable between first contact section  416  and second contact section  417  along a longitudinal axis of the rod  41 . 
     Spring  43  is received in enlarged section  424  of axial bore  423  of sleeve  42  for biasing sleeve  42  towards second end  412  of rod  41 . Spring  43  has a first end  431  abutting against shoulder  414  of rod  41  and a second end  432  abutting against end face  427  of enlarged section  424 . Sleeve  42  is moveable relative to rod  41  along the longitudinal axis of the rod  41  between an extended first position biased by spring  43  ( FIG. 4 ) and a retracted, second position compressing spring  43  ( FIG. 8 ). 
     Referring to  FIG. 4 , when sleeve  42  is moved to the extended, first position, ball  44  is pushed by sleeve  42  and engages in first contact section  416  of recess  415 . A depth from first contact section  416  to an outer periphery of rod  41  is shorter than that from second contact section  417  to the outer periphery of rod  41 . Namely, first contact section  416  has a depth smaller than second contact section  417 . When ball  44  is seated in first contact section  416 , an outermost portion  441  of ball  44  projects out of radial bore  425  of sleeve  42  and engages one of recessed portions  312  of bit  3 . Referring to  FIG. 7 , when sleeve  42  is moved to the retracted, second position, ball  44  engages second contact section  417  of recess  415  and does not project out of radial bore  425  of sleeve  42 . 
     Coupling of bit  3  with quick-release coupler  4  will now be described. When bit  3  is initially engaged with second end  42  of quick-release coupler  4 , one of the side walls of coupling hole  311  presses ball  44  and pushes sleeve  42  to move inwardly relative to rod  41  and compress spring  43  ( FIG. 7 ). Then, sleeve  42  is moved to the retracted, second position ( FIG. 8 ) to further compress spring  43 , and ball  44  is released to drop from first contact section  416  into second contact section  417  of recess  415 . Then, bit  3  is further moved towards sleeve  42  to contact radial flange  426  of sleeve  42 , and ball  44  aligns with one of recessed portions  312  of bit  3  ( FIG. 9 ). Then, when bit  3  is released, sleeve  42  and bit  3  are biased by spring  43 , and sleeve  42  is moved to the extended, first position in which ball  44  is retained in place by engagement with first contact section  416  of recess  415  and recessed portion  312  of bit  3  ( FIG. 2 ). Thus, bit  3  is securely locked on quick-release coupler  4  as shown in  FIGS. 2 and 6  and can be driven when rod  41  of quick-release coupler  4  secured to pneumatic tool  5  rotates. 
     Coupling hole  311  of bit  3  is of a width such that one of recessed portions  312  of bit  3  is capable of aligning with the second contact section  417  of recess  415  when bit  3  is engaged with second end  422  of sleeve  42 , and sleeve  42  moves to the retracted, second position. To remove bit  3  from quick-release coupler  4 , the user needs only to grasp the bit  3  ( FIG. 2 ) and push the bit  3  to make sleeve  42  move to the retracted, second position ( FIG. 9 ) such that ball  44  no longer engages recessed portions  312  of bit  3 , allowing bit  3  to be removed from sleeve  42  ( FIG. 4 ) when the user firmly grips sleeve  42  and moves bit  3  away from sleeve  42 . 
     The present invention has been described via the detailed illustration of the embodiments. Those skilled in the art can derive variations from the embodiments without departing from the scope of the present invention. Therefore, the embodiments shall not limit the scope of the present invention defined in the claims