Patent Publication Number: US-2007101832-A1

Title: Ratchet mechanism for hand tools

Description:
FIELD OF THE INVENTION  
      The present invention relates to a ratchet mechanism including first member with a curved surface and a second member with teeth which are engaged with the driving member in the head of the tool.  
     BACKGROUND OF THE INVENTION  
      A conventional ratchet hand tool  6  such as a ratchet wrench is shown in  FIG. 10  and generally includes handle  61  and a head  62  which includes a through hole  63  and a recess  64  defined in an inner periphery of the through hole  63 . A driving member  7  is rotatably received in the through hole  63  and retained by a C-shaped clip  72 . A ratchet mechanism  8  is received in the recess  64  and includes a first pawl  81  and a second pawl  82 , a spring  83  has two ends thereof engaged with two respective protrusions  812 ,  833  3× ending from the two pawls  81 ,  82 . Each of the first and second pawls  81 ,  82  has teeth  811 / 821  defined in a side thereof and the first pawl  81  or the second pawl  82  is engaged with teeth  71  defined in an outer periphery of the driving member  7  alternatively. When the first pawl  81  is engaged with the driving member  7 , the driving member  7  is rotated with the handle  61  so as to output torque in a first direction. When the second pawl  82  is engaged with the driving member  7 , the driving member  7  is rotated with the handle  61  so as to output torque in a second direction. However, it is noted that when the first pawl  81  is engaged with the driving member  7 , the teeth  822  of the second pawl  82  are in contact with the teeth  71  of the driving member  7 , so that the teeth  71  of the driving member  7  and the teeth  822  of the second pawl  82  wear out during rotating in the first direction, vice versa.  
      The present invention intends to provide a ratchet mechanism which includes two members and one of which includes a curved surface and the other one has teeth to be engaged with the driving member, so that during operation, the teeth of the driving member do not wear out by the member with the curved surface.  
     SUMMARY OF THE INVENTION  
      The present invention relates to a ratchet hand tool that includes a handle and a head which has a through hole for receiving a driving member which has first teeth, and a recess is defined in an inner periphery of the through hole so as to receive a ratchet mechanism therein. The ratchet mechanism has a first member with a curved and smooth surface, a second member with second teeth, and a spring member connected between the first and second members. The second teeth are engaged with the first teeth. The first member has a first notch and the second member has a second notch. Two ends of the spring member are engaged with the first and second notches.  
      The primary object of the present invention is to provide a ratchet mechanism for a hand tool and the mechanism includes a first member with a curved and smooth surface, a second member with teeth which are engaged with the driving member, and a spring connected between the first and second members. The teeth of the driving member are not worn out during operation because of the curved and smooth surface.  
      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 a ratchet hand tool of the present invention;  
       FIG. 2  is a cross sectional view to show the ratchet hand tool of the present invention;  
       FIG. 3  shows a second embodiment of the spring of the ratchet mechanism;  
       FIG. 4  shows a third embodiment of the spring of the ratchet mechanism;  
       FIG. 5  shows a fourth embodiment of the spring of the ratchet mechanism;  
       FIG. 6  is an exploded view to show a second embodiment of the ratchet mechanism of the ratchet hand tool of the present invention;  
       FIG. 7  is a cross sectional view to show the ratchet hand tool of the present invention as shown in  FIG. 6 ;  
       FIG. 8  shows a second embodiment of the spring of the ratchet mechanism as shown in  FIG. 6 ;  
       FIG. 9  is an exploded view to show a second embodiment of the ratchet tool of the present invention, and  
       FIG. 10  shows an exploded view of a conventional ratchet tool.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      Referring to  FIGS. 1 and 2 , the ratchet hand tool  1  of the present invention comprises a handle  11  and a head  12  is connected to an end of the handle  11 . A through hole  13  is defined in the head  12  and a recess  14  defined in an inner periphery of the through hole  13 . A driving member  3  with first teeth  31  defined in an outer periphery thereof is rotatably received in the through hole  13  and retained by engaging a C-shaped clip  32  with the head  12 . A ratchet mechanism  2  is received in the recess  14  and has a first member  21  with a curved and smooth surface  211  facing the driving member  3 , a second member  22  with second teeth  221 , and a spring member  23  connected between the first and second members  21 ,  22 . The second teeth  221  are engaged with the first teeth  31  so that when rotating the handle  11 , the driving member  3  is rotated with the rotation of the handle  11 . The first member  21  has a first notch  212  defined in an end thereof and the second member  22  has a second notch  222  defined in an end thereof. Two ends of the spring member  23  are two rings which are engaged with the first and second notches  212 ,  222 . The spring member  23  is a compression spring.  
      The first teeth  31  of the driving member  3  are engaged with the second teeth  221  of the second member  22 , and curved and smooth surface  211  of the first member  21  does not cause any significant friction to the first teeth  31  so that the first teeth  31  are not worn out during operation. If the user wants to output a torque in opposite direction, the hand tool  1  is then flip over and engage the workpiece (not shown) again to output the torque.  
       FIG. 3  shows that the spring member  23 A can be an inverted U-shaped member and two ends  230 A of the spring member  23 A are engaged with the notches  212 A of the first member  21 A and the second notch  222 A of the second member  22 A.  
      As shown in  FIG. 4 , the spring member  23 E can be a U-shaped member and the two ends  231 E of the spring member  23 E are engaged with the first and second notches  212 E,  222 E of the first and second members  21 E,  22 E.  
       FIG. 5  shows that the spring member  23 F can be a p-shaped member and the two ends  231 F of the spring member  23 F are engaged with the first and second notches  212 F,  222 F of the first and second members  21 F,  22 F.  
       FIG. 6  shows a second embodiment of the ratchet mechanism  2 B of the present invention and the ratchet mechanism  2 B comprises a handle  11 B and a head  12 B is connected to an end of the handle  11 B. A through hole  13 B is defined in the head  12 B and a recess  14 B is defined in an inner periphery of the through hole  13 B. A driving member  3 B is rotatably received in the through hole  13 B and retained by engaging a C-shaped clip  32 B with the head  12 B. The driving member  3 B has first teeth  31 B defined in an outer periphery thereof. The ratchet mechanism  2 B is received in the recess  14 B and has a first member  21 B with a curved and smooth surface  211 B which faces the driving member  3 B, a second member  22 B with second teeth  221 B, and a spring member  23 B connected between the first and second members  21 B,  22 B. The spring member  23 B is a compression spring and the second teeth  221 B are engaged with the first teeth  31 B. The first member  21 B has a first protrusion  212 B and the second member  22 B has a second protrusion  222 B. Two ends of the spring member  23 B are engaged with the first and second protrusions  212 B,  222 B.  
      As shown in  FIG. 8 , the spring member  24  is a spring plate which has two holes  241  defined in two ends thereof. Each of the first and second members  21 C,  22 C has a protrusion  212 C/ 222 C. The two protrusions  212 C and  222 C are engaged with the two holes  241  of the spring member  24 .  
       FIG. 9  shows a second embodiment of the ratchet hand tool wherein a first head  12 D and a second head  15 D are connected to two ends of the handle  11 D. The first head  12 D has a through hole for receiving a driving member  3 D with teeth  31 D in outer periphery thereof and a ratchet mechanism is received in a recess defined in an inner periphery of the through hole in the first head  12 D. The ratchet mechanism includes a first member  21 D with a curved and smooth surface  211 D. A spring member  23 D is connected between the first and second members  21 D,  22 D. The second head  15 D includes a second through hole  16 D defined therein and a second recess  17 D is defined in an inner periphery of the second through hole  16 D. A driving member  4  is rotatably received in the second through hole  16 D and retained by engaging a second C-shaped clip  42  with the second head  15 D. The driving member  4  has third teeth  41  defined in an outer periphery thereof and a ratchet mechanism  5  is received in the second recess  17 D. The ratchet mechanism  5  has a third member  51  with a second curved and smooth surface  511  facing the driving member  4 , a fourth member  52  with fourth teeth  521 , and a spring member  53  which is a compression spring and connected between the third and fourth members  51 ,  52 . The fourth teeth  521  are engaged with the third teeth  41 . The third member  51  has a third protrusion  512  and the fourth member  52  has a fourth protrusion  522 , and two ends of the spring member  53  are engaged with the third and fourth protrusions  512 ,  522 . The user can use the two ratchet mechanisms in the two heads  12 D.  15 D to output torque in different directions.  
      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.