Patent Publication Number: US-2006011366-A1

Title: Inlet valve for pneumatic tool

Description:
BACKGROUND OF INVENTION  
      1. Field of Invention  
      The present invention relates to a pneumatic tool and, more particularly, to an inlet valve for a pneumatic tool.  
      2. Related Prior Art  
      Pneumatic tools are convenient and efficient tools for drilling and driving screws.  
      In Taiwanese Patent Publication 567954, for example, is disclosed an inlet valve for a pneumatic tool. The pneumatic tool includes a pistol-shaped body  200 . The inlet valve includes a ring  20  put in the body  200 , a housing  30  connected to the ring  20 , a ball  40  put in the housing  30 , an sealing washer  50  put between the housing  30  and the ball  40 , and a C-ring  60  put in the housing  30  for restraining the ball  40  in the housing  30 . The housing  30  defines a space  35  and an aperture  36  communicated with the space  35 . The ball  40  is put in the space  35 . An end of a rod  91  can be inserted in the space  35  through the aperture  36 . An opposite end of the rod  91  can be pushed by means of a trigger  10  installed on the body  200 . Normally, the ball  40  rests against the sealing washer  50  and blocks the aperture  36 . When the trigger  10  is pulled, the ball  40  is pushed from the sealing washer  50  due to the rod  90  put between the trigger  10  and the ball  40 . However, the use of the pneumatic tool with this conventional inlet valve is not convenient in some cases. An example is made of an operation where the pneumatic tool is used to drive nuts for fastening a wheel to a vehicle. At first, the nuts are loosely engaged with bolts that carry the wheel. Only after all of the nuts are loosely engaged with bolts is the engagement tightened. This operation requires some personal skills to operate the pneumatic tool in a two-step manner. This operation is troublesome.  
      The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.  
     SUMMARY OF INVENTION  
      According to the present invention, an inlet valve is provided for a pneumatic tool. The pneumatic tool defines a space and a passageway communicated with the space. The inlet valve includes a ring and a controller. The ring can be tilted in the space between a first position where it blocks the space from the passageway and a second position where it allows the communication between the space and the passageway. The ring defines a central aperture. The controller can be pivoted in the space between a first position, a second position and a third position. The controller includes a disc and a rod raised from the disc. The disc is put against the ring as the controller is in the first position and pivoted from the ring as the controller is in the second position. The rod is inserted through the central aperture of the ring. The diameter of the rod is smaller than that of the central aperture of the ring in order to allow pressurized air to travel through the central aperture of the ring as the controller is in the second position. The rod pivots the ring to the second position as the controller is in the third position.  
      The primary advantage of the pneumatic tool equipped with the inlet valve according to the present invention is the two-step operation.  
      Other advantages and novel features of the invention will become more apparent from the following detailed description in conjunction with the drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
      The present invention will be described through detailed illustration of the preferred embodiment referring to the drawings.  
       FIG. 1  is a cross-sectional view of a pneumatic tool with an inlet valve according to the preferred embodiment of the present invention.  
       FIG. 2  is an exploded view of the inlet valve shown in  FIG. 1 .  
       FIG. 3  is a cross-sectional view of the inlet valve shown in  FIG. 1  at a first step of operation.  
       FIG. 4  is a cross-sectional view of the inlet valve shown in  FIG. 1  at a second step of operation. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT  
      Referring to  FIGS. 1 and 2 , a pneumatic tool  10  is equipped with an inlet valve according to the preferred embodiment of the present invention. The pneumatic tool  10  includes a pistol-shaped body that is only shown partially. The pistol-shaped body includes a barrel (not shown), a handle  11  extended from the barrel, and a trigger  13  put on the handle  11 . The handle  11  defines a space  12  and a passageway  121  communicated with the space  12 . Pressurized air can travel through the space  12  and the passageway  121 . The inlet valve is put in the space  12  in order to control the travel of the pressurized air.  
      The inlet valve includes a washer  15 , a ring  20 , a controller  30 , and a spring  35 . The washer  15  is put in the space  12  against an annular shoulder (not numbered) formed between the space  12  and the passageway  121 . The washer  15  defines an aperture  151 .  
      The ring  20  is put in the space  12  against the washer  15 . The ring  20  includes a central aperture  21  defined therein, several peripheral apertures  23  defined therein, and an annular ridge  24  formed thereon between the central aperture  21  and the peripheral apertures  23 . The annular ring  24  of the ring  20  is put against the washer  15 . The central aperture  21  of the ring  20  is communicated with the aperture  151  of the washer  15 .  
      The controller  30  includes a block  33 , an enlarged disc  32  formed on the block  33  and a rod  31  formed on the disc  32 . The rod  31  is inserted through the central aperture  21  of the ring  20  and the aperture  151  of the washer  15 . The diameter of the rod  31  is smaller than that of the central aperture  21  of the ring  20  so that the pressurized gas can travel between the rod  31  and the ring  20 .  
      An end of the spring  35  is put around the block  33 . An opposite end of the spring  35  is put in a recess  41  defined in a tube  40 . The spring  35  is compressed between the disc  32  and the tube  40 . Because of the spring  35 , the disc  32  is pressed against the ring  20 .  
      A hollow restraint  17  is put in the space  12  in order to restrain the inlet valve in the space  12 . A thread formed on the hollow restraint  17  is engaged with a thread formed on the wall of the space  12 .  
      The trigger  13  includes a reduced end  131  in contact with the rod  31 .  
      Referring to  FIG. 3 , a first step of the operation of the inlet valve will be described. At the first step, the trigger  13  is slightly pushed. The reduced end  131  of the trigger  13  pushes the rod  31  slightly. Thus, the disc  32  is tilted slightly. A gap occurs between the ring  20  and the disc  32 . The pressurized air travels to passageway  121  from the space  12  through the gap between the disc  32  and the ring  20  and through the central aperture  21 . The annular ridge  24  is still in sealing contact with washer  15 .  
      Referring to  FIG. 4 , a second step of the operation of the inlet valve will be described. At the second step, the trigger  13  is further pushed than at the first step. The reduced end  131  of the trigger  13  further pushes the rod  31 . Thus, the disc  32  is further tilted. The gap between the ring  20  and the disc  32  becomes bigger. In addition, the ring  20  is tilted. The pressurized air travels to the passageway  121  from the space  12  through the peripheral apertures  23  and through the aperture  151 . The pressurized air travels through the pneumatic tool  10  at a higher rate at the second step than at the first step.  
      Advantages of the pneumatic tool equipped with the inlet valve of the present invention will be discussed in an exemplary operation where it is used to drive nuts for fastening a wheel to a vehicle. At first, the nuts are loosely engaged with bolts on which the wheel is installed. Only after all of the nuts are engaged with the bolts loosely is the engagement tightened. Thus, the wheel is attached to the vehicle adequately. To this end, a user operates the trigger to a first extent in order to actuate the inlet valve to the first step. At this instant, the user can only engage the nuts with the bolts loosely no matter how long he or she operates the trigger. Then, the user operates the trigger to a second extent in order to actuate the inlet valve to the second step. At this instant, the user can tighten the engagement of the nuts with the bolts. With the pneumatic tool equipped with the inlet valve of the present invention, the user can attach the wheel to the vehicle adequately without skills.  
      Those skilled in the art can derive variations from the preferred embodiment without departing from the scope of the present invention. Therefore, the preferred embodiment shall not limit the scope of the present invention defined in the claims.