Patent Publication Number: US-2006011363-A1

Title: Pneumatic wrench having enhanced strength

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a pneumatic wrench, and more particularly to a pneumatic wrench having an enhanced strength.  
      2. Description of the Related Art  
      A conventional pneumatic wrench in accordance with the prior art shown in  FIGS. 4 and 5  comprises a pneumatic motor  10 , a striking portion  20 , and a drive shaft  30 . The striking portion  20  is driven by the pneumatic motor  10  to rotate in the normal direction and the reverse direction to drive the drive shaft  30  to rotate, so that the drive shaft  30  is rotated to rotate a socket (not shown) mounted on the drive shaft  30  so as to drive and rotate a screw member, such as a bolt, nut or the like.  
      The pneumatic motor  10  includes a cylinder  11 , a vane  12  mounted in the cylinder  11 , a rotor  15  mounted in the cylinder  11 , and a toothed shaft  16  mounted on the rotor  15 . The striking portion  20  includes a support seat  21 , an actuating shaft  22  mounted on the support seat  21  and engaged with the toothed shaft  16  of the pneumatic motor  10 , an eccentric portion  23  formed on an end of the actuating shaft  22  and mounted in the support seat  21 , and a hammer  26  pivotally mounted in the support seat  21  by a pivot shaft  25  and having a periphery formed with an operation recess  28 . The hammer  26  is formed with a pivot hole  27  mounted on the pivot shaft  25 . The support seat  21  has two end faces each formed with a through hole  24  for mounting the pivot shaft  25 . The drive shaft  30  has a first end mounted in the support seat  21  and formed with an engaging portion  35  engaged with the hammer  26  and formed with driven recess  36  aligning with the operation recess  28  of the hammer  26 . The drive shaft  30  has a second end formed with a mounting portion  31  for mounting a socket (not shown).  
      In operation, after the compressed air enters the cylinder  11  of the pneumatic motor  10 , the vane  12  and the rotor  15  are operated to rotate the toothed shaft  16  which rotates the actuating shaft  22 , so that the support seat  21  is rotated in the normal direction and the reverse direction to drive the hammer  26  to move. At this time, the eccentric portion  23  of the actuating shaft  22  drives the hammer  26  to strike the drive shaft  30  so as to drive the drive shaft  30  to rotate, so that the drive shaft  30  is rotated to rotate the socket (not shown) mounted on the mounting portion  31  of the drive shaft  30  so as to drive and rotate a screw member, such as a bolt, nut or the like.  
      However, the hammer  26  is pivoted to strike the drive shaft  30  when the support seat  21  is rotated each time, so that the pivot shaft  25  is subjected to a larger reaction, and the stress is concentrated on the pivot shaft  25 , thereby easily deforming the pivot shaft  25  during a long-term utilization, and thereby decreasing the lifetime of the pivot shaft  25 . In addition, the pivot shaft  25  is easily deformed during a long-term utilization, so that the hammer  26  is not operated smoothly, thereby affecting operation of the conventional pneumatic wrench.  
     SUMMARY OF THE INVENTION  
      The present invention is to mitigate and/or obviate the disadvantage of the conventional pneumatic wrench.  
      The primary objective of the present invention is to provide a pneumatic wrench having an enhanced strength.  
      Another objective of the present invention is to provide a pneumatic wrench, wherein the pivot shaft mounted between the hammer and the support seat is formed with an enlarged portion that withstands a larger reaction applied on the hammer due to the striking action of the hammer, thereby enhancing the structural strength of the pneumatic wrench.  
      A further objective of the present invention is to provide a pneumatic wrench, wherein the enlarged portion of the pivot shaft withstands a larger reaction so as to prevent the pivot shaft from being deformed due to the larger reaction, so that the pivot shaft is operated smoothly.  
      A further objective of the present invention is to provide a pneumatic wrench, wherein the enlarged portion of the pivot shaft enhances the structural strength of the pneumatic wrench, thereby increasing the lifetime of the pneumatic wrench.  
      In accordance with one embodiment of the present invention, there is provided a pneumatic wrench, comprising a striking portion including a support seat, and a hammer pivotally mounted in the support seat by a pivot shaft, wherein:  
      the support seat of the striking portion has a first end face formed with a through hole and a second end face formed with an enlarged hole;  
      the pivot shaft has a first end inserted into the through hole of the support seat and a second end formed with an enlarged portion inserted into the enlarged hole of the support seat; and  
      the hammer of the striking portion has first end formed with a shaft hole mounted on the pivot shaft and a second end formed with an enlarged hole mounted on the enlarged portion of the pivot shaft.  
      In accordance with one embodiment of the present invention, there is provided a pneumatic wrench, comprising a striking portion including a support seat, a first hammer pivotally mounted in the support seat by a first pivot shaft, and a second hammer pivotally mounted in the support seat by a second pivot shaft, wherein:  
      the support seat has a first end face formed with a first through hole and a second through hole and a second end face formed with a first enlarged hole and a second enlarged hole;  
      the first pivot shaft has a first end inserted into the first through hole of the support seat and a second end formed with a first enlarged portion inserted into the first enlarged hole of the support seat;  
      the second pivot shaft has a first end inserted into the second through hole of the support seat and a second end formed with a second enlarged portion inserted into the second enlarged hole of the support seat;  
      the first hammer has first end formed with a first shaft hole mounted on the first pivot shaft and a second end formed with a first enlarged hole mounted on the first enlarged portion of the first pivot shaft; and  
      the second hammer has first end formed with a second shaft hole mounted on the second pivot shaft and a second end formed with a second enlarged hole mounted on the second enlarged portion of the second pivot shaft.  
      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 DRAWINGS  
       FIG. 1  is an exploded perspective view of a pneumatic wrench in accordance with the preferred embodiment of the present invention;  
       FIG. 2  is a plan cross-sectional assembly view of the pneumatic wrench as shown in  FIG. 1 ;  
       FIG. 3  is an exploded perspective view of a pneumatic wrench in accordance with another embodiment of the present invention;  
       FIG. 4  is an exploded perspective view of a conventional pneumatic wrench in accordance with the prior art; and  
       FIG. 5  is a plan cross-sectional assembly view of the conventional pneumatic wrench as shown in  FIG. 4 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring to the drawings and initially to  FIGS. 1 and 2 , a pneumatic wrench in accordance with the preferred embodiment of the present invention comprises a pneumatic motor  50 , a striking portion  60 , and a drive shaft  80 .  
      The striking portion  60  is driven by the pneumatic motor  50  to rotate in the normal direction and the reverse direction to drive the drive shaft  80  to rotate, so that the drive shaft  80  is rotated to rotate a socket (not shown) mounted on the drive shaft  80  so as to drive and rotate a screw member, such as a bolt, nut or the like.  
      The pneumatic motor  50  includes a cylinder  51 , a vane  52  mounted in the cylinder  51 , a rotor  55  mounted in the cylinder  51 , and a toothed shaft  56  mounted on the rotor  55 .  
      The striking portion  60  includes a support seat  61 , an actuating shaft  62  mounted on the support seat  61  and engaged with the toothed shaft  56  of the pneumatic motor  50 , an eccentric portion  63  formed on an end of the actuating shaft  62  and mounted in the support seat  61 , and a hammer  70  pivotally mounted in the support seat  61  by a pivot shaft  66  and having a periphery formed with an operation recess  75 .  
      The support seat  61  of the striking portion  60  has a first end face formed with a through hole  64  and a second end face formed with an enlarged hole  65 . Preferably, the through hole  64  of the support seat  61  is co-axial with the enlarged hole  65  of the support seat  61 .  
      The pivot shaft  66  has a first end inserted into the through hole  64  of the support seat  61  and a second end formed with an enlarged portion  67  inserted into the enlarged hole  65  of the support seat  61 . Preferably, the enlarged portion  67  of the pivot shaft  66  is circular and has a diameter equal to that of the enlarged hole  65  of the support seat  61 .  
      The hammer  70  of the striking portion  60  has first end formed with a shaft hole  71  mounted on the pivot shaft  66  and a second end formed with an enlarged hole  72  mounted on the enlarged portion  67  of the pivot shaft  66 . Preferably, the enlarged hole  72  of the hammer  70  has a diameter equal to that of the enlarged portion  67  of the pivot shaft  66 .  
      In such a manner, the pivot shaft  66  is extended through the shaft hole  71  of the hammer  70  and the through hole  64  of the support seat  61 , and the enlarged portion  67  of the pivot shaft  66  is extended through the enlarged hole  65  of the support seat  61  and the enlarged hole  72  of the hammer  70 .  
      The drive shaft  80  has a first end mounted in the support seat  61  of the striking portion  60  and formed with an engaging portion  85  engaged with the hammer  70 . The engaging portion  85  of the drive shaft  80  is formed with driven recess  86  aligning with the operation recess  75  of the hammer  70  of the striking portion  60 . The drive shaft  80  has a second end formed with a mounting portion  81  for mounting a socket (not shown).  
      In operation, after the compressed air enters the cylinder  51  of the pneumatic motor  50 , the vane  52  and the rotor  55  are operated to rotate the toothed shaft  56  which rotates the actuating shaft  62 , so that the support seat  61  is rotated in the normal direction and the reverse direction to drive the hammer  70  to move. At this time, the eccentric portion  63  of the actuating shaft  62  drives the hammer  70  to strike the drive shaft  80  so as to drive the drive shaft  80  to rotate, so that the drive shaft  80  is rotated to rotate the socket (not shown) mounted on the mounting portion  81  of the drive shaft  80  so as to drive and rotate a screw member, such as a bolt, nut or the like.  
      Accordingly, the pivot shaft  66  mounted between the hammer  70  and the support seat  61  is formed with an enlarged portion  67  that withstands a larger reaction applied on the hammer  70  due to the striking action of the hammer  70 , thereby enhancing the structural strength of the pneumatic wrench. In addition, the enlarged portion  67  of the pivot shaft  66  withstands a larger reaction so as to prevent the pivot shaft  66  from being deformed due to the larger reaction, so that the pivot shaft  66  is operated smoothly. Further, the enlarged portion  67  of the pivot shaft  66  enhances the structural strength of the pneumatic wrench, thereby increasing the lifetime of the pneumatic wrench.  
      Referring to  FIG. 3 , the striking portion  60 A includes a support seat  90 , an actuating shaft  62  mounted on the support seat  90  and engaged with the toothed shaft  56  of the pneumatic motor  50 , an eccentric portion  63  formed on an end of the actuating shaft  62  and mounted in the support seat  90 , a first hammer  97  pivotally mounted in the support seat  90  by a first pivot shaft  95 , and a second hammer  98  pivotally mounted in the support seat  90  by a second pivot shaft  96 .  
      The support seat  90  has a first end face formed with a first through hole  92  and a second through hole  94  and a second end face formed with a first enlarged hole  91  and a second enlarged hole  93 . Preferably, the first through hole  92  of the support seat  90  is co-axial with the first enlarged hole  91  of the support seat  90 , and the second through hole  94  of the support seat  90  is co-axial with the second enlarged hole  93  of the support seat  90 .  
      The first pivot shaft  95  has a first end inserted into the first through hole  92  of the support seat  90  and a second end formed with a first enlarged portion  950  inserted into the first enlarged hole  91  of the support seat  90 . Preferably, the first enlarged portion  950  of the first pivot shaft  95  is circular and has a diameter equal to that of the first enlarged hole  91  of the support seat  90 .  
      Similarly, the second pivot shaft  96  has a first end inserted into the second through hole  94  of the support seat  90  and a second end formed with a second enlarged portion  960  inserted into the second enlarged hole  93  of the support seat  90 . Preferably, the second enlarged portion  960  of the second pivot shaft  96  is circular and has a diameter equal to that of the second enlarged hole  93  of the support seat  90 .  
      The first hammer  97  has first end formed with a first shaft hole  970  mounted on the first pivot shaft  95  and a second end formed with a first enlarged hole  971  mounted on the first enlarged portion  950  of the first pivot shaft  95 . Preferably, the first enlarged hole  971  of the first hammer  97  has a diameter equal to that of the first enlarged portion  950  of the first pivot shaft  95 .  
      Similarly, the second hammer  98  has first end formed with a second shaft hole  980  mounted on the second pivot shaft  96  and a second end formed with a second enlarged hole  981  mounted on the second enlarged portion  960  of the second pivot shaft  96 . Preferably, the second enlarged hole  981  of the second hammer  98  has a diameter equal to that of the second enlarged portion  960  of the second pivot shaft  96 .  
      In such a manner, the first pivot shaft  95  is extended through the first shaft hole  970  of the first hammer  97  and the first through hole  92  of the support seat  90 , and the first enlarged portion  950  of the first pivot shaft  95  is extended through the first enlarged hole  91  of the support seat  90  and the first enlarged hole  971  of the first hammer  97 .  
      Similarly, the second pivot shaft  96  is extended through the second shaft hole  980  of the second hammer  98  and the second through hole  94  of the support seat  90 , and the second enlarged portion  960  of the second pivot shaft  96  is extended through the second enlarged hole  93  of the support seat  90  and the second enlarged hole  981  of the second hammer  98 .  
      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.