Patent Publication Number: US-7895921-B2

Title: Ratchet tool

Description:
FIELD OF THE INVENTION 
     The present invention relates to a hand tool and more particularly, to a ratchet tool. 
     BACKGROUND OF THE INVENTION 
     A conventional ratchet tool is shown in  FIG. 7 , and generally includes a handle  90  with a head  91  connected to an end thereof and a space  92  is defined in the head  91  so as to receive a ratchet  93  therein. A hole  94  is defined through a wall of the head  91  and communicates with the space  92 , a pawl  95 , a spring  96  and a seal member  97  are engaged with the hole  94 . The pawl  95  is biased by the spring  96  so as to be engage with the ratchet  93  which can be operated in one direction. 
     It is noted that the hole  94  is defined through the wall of the head  91  and this weakens the structural strength of the head  91  which may not be able to bear large torque during use. 
     The ratchet  93  is engaged with the pawl  95  and can only work in one direction and this cannot meet requirements of use for ratchet tools. 
     The present invention intends to provide a ratchet tool that includes a compact and simple structure and can be operated in two different directions. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a ratchet tool that comprises a head and a handle, wherein the head has a space defined therein and a first groove is defined in an inner periphery of the space. A ratchet is received in the space and has teeth defined in an outer periphery thereof. The ratchet has an engaging portion so as to be engage with a work piece. Two recesses are defined in the inner periphery of the space so as to respectively receive two pawl sets therein. 
     Each pawl set has a pawl and a spring which is located on an inner end of the recess and biases the pawl to protrude out from the recess corresponding thereto. Each pawl has engaging teeth defined in an end thereof which protrudes into the space and are removably engaged with the teeth of the ratchet. Each pawl has a flat surface defined in the end having the engaging teeth. 
     An operation member has a flange rotatably engaged with the first groove and the flange includes a pressing surface which presses one of the flat surfaces of the two pawls. 
     The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view to show the ratchet tool of the present invention; 
         FIG. 2  shows that the lever of the operation member is shifted to left and the block is engaged with one of the notches; 
         FIG. 3  is a partial cross sectional view to show the first pawl is engaged with the ratchet and the second pawl is separated from the ratchet when shifting the lever to left; 
         FIG. 4  is a partial cross sectional view to show the second pawl is engaged with the ratchet and the first pawl is separated from the ratchet when shifting the lever to right; 
         FIG. 5  is a partial cross sectional view to show that both of the first and second pawls are separated from the ratchet when shifting the lever to the center; 
         FIG. 6  is an exploded view to show another embodiment of the ratchet tool of the present invention, and 
         FIG. 7  is a partial cross sectional view to show a conventional ratchet tool. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , the ratchet tool  1  of the present invention comprises a head  12  and a handle  13  is connected to the head  12 , the head  12  includes a space  14  defined therein and a ratchet  21  is rotatably received in the space  14 . The ratchet  21  has teeth  22  defined in an outer periphery thereof and an engaging portion which is used to engage with a work piece such as a nut or a bolt head (not shown). In  FIG. 1 , the engaging portion is a hole defined through the ratchet  21  and includes a polygonal inner periphery  24 . A lip  15  extends inward from the inner periphery of the space  14  and a first side of the ratchet  21  is stopped by the lip  15 . First and second recesses  17 A,  17 B are defined in the inner periphery of the space  14 . 
     A first pawl set  31 A and a second pawl set  31 B are respectively received in the first and second recesses  17 A,  17 B and each of the first and second pawl sets  31 A,  31 B has a pawl  32 A/ 32 B and a spring  33 A/ 33 B which is located on an inner end of the first/second recess  17 A/ 17 B and biases the first/second pawl  32 A/ 32 B to protrude out from the first/second recess  17 A/ 17 B corresponding thereto. Each first/second pawl  32 A/ 32 B has engaging teeth  34 A/ 34 B defined in an end thereof which protrudes into the space  14  and is located corresponding the teeth  22  of the ratchet  21 . The engaging teeth  34 A/B of each first/second pawl  32 A/ 32 B are removably engaged with the teeth  22  of the ratchet  21 . Each first/second pawl  32 A/ 32 B has a first/second flat surface  36 A/ 36 B defined in the end having the engaging teeth  34 A/ 34 B. The first and second pawls  32  are shaped to fit in the first and second recesses  17 A,  17 B so that the first and second pawls  32  are movable axially and linearly in the first and second recesses  17 A,  17 B. 
     An operation member  41  has a flange rotatably engaged with a first groove  16  defined in the inner periphery of the space  14  and the flange includes a pressing surface  47  which presses one of the first/second flat surfaces  36 A/ 36 B of the first and second pawls  32 A,  32 B. A second side of the ratchet  21  is engaged with the operation member  41 . The operation member  41  includes a second groove  42  defined in an outer periphery thereof and a clip  44  is engaged with the second groove  42 . The clip  44  is engaged with a positioning groove  46  defined in the inner periphery of the space  14  so as to position the operation member  41 . 
     A recessed area  18  is defined in a side of the head  12  and a hole  181  is defined in the recessed area  18 . A spring  191  and a block  192  are engaged with the hole  181 . The operation member  41  includes a lever  48  and a plurality of notches  49  are defined in an underside thereof. The lever  48  are movably received in the recessed area  18  and the block  192  is engaged with one of the notches  49 . The recessed area  18  includes two sidewalls  182  and two sides of the lever  48  are stopped by the two sidewalls  182  when operating the lever  48  to choose desired direction to output torque. 
     As shown in  FIGS. 2 and 3 , when shifting the lever  48  to the left and the left side of the lever  48  is stopped by the left sidewall  182 . The pressing surface  47  of the operation member  41  is rotated when shifting the lever  48  and presses the first flat surface  36 A so that the first pawl  32 A is pushed to disengage from the teeth  22  of the ratchet  21 . The second pawl  32 B is not pressed by the pressing surface  47  and pushed by the second spring  33 B, so that the engaging teeth  34 B are engaged with the teeth  22  of the ratchet  21 . The block  192  is engaged with the right end notch  19 . In this status, when rotating the ratchet tool clockwise, the work piece  9  (not shown) engaged with the polygonal inner periphery  24  and the head  12  are co-rotated clockwise. When rotating the handle  13  counter clock-wise, the second pawl  32 B is pushed by the teeth  22  of the ratchet  21  and compresses the second spring  33 B, so that the work piece is remained still and the handle  13  is rotated an angle. 
     As shown in  FIG. 4 , when shifting the lever  48  to the right and the right side of the lever  48  is stopped by the right sidewall  182 . The pressing surface  47  of the operation member  41  is rotated when shifting the lever  48  and presses the second flat surface  36 B so that the second pawl  32 B is pushed to disengage from the teeth  22  of the ratchet  21 . The first pawl  32 A is not pressed by the pressing surface  47  and pushed by the first spring  33 A, so that the engaging teeth  34 A are engaged with the teeth  22  of the ratchet  21 . The block  192  is engaged with the left end notch  19 . In this status, when rotating the ratchet too  1  counter clockwise, the work piece  9  (not shown) engaged with the polygonal inner periphery  24  and the head  12  are co-rotated counter clockwise. When rotating the handle  13  clock-wise, the first pawl  32 A is pushed by the teeth  22  of the ratchet  21  and compresses the first spring  33 A, so that the work piece is remained still and the handle  13  is rotated an angle. 
     As shown in  FIG. 5 , when the lever  48  is positioned at the center of the recessed area  18 , the block  192  is engaged with the notch  49  at the middle position. The first and second pawls  32 A,  32 B are not compressed by the pressing surface  47 , and the first and second pawls  32 A,  32 B are biased by the first and second springs  33 A,  33 B to engage with the teeth  22  of the ratchet  21 , so that the ratchet  21  cannot rotate in either direction. 
       FIG. 6  shows that the engaging portion of the ratchet  21  can be a driving protrusion  240  extending from a side of the ratchet  21  so as to be connected with a sleeve (not shown). 
     While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.