Patent Publication Number: US-6655238-B1

Title: Reinforcement teeth structure for ratchet

Description:
FIELD OF THE INVENTION 
     The present invention relates to a ratchet tool that has a toothed engaging ring rotatably received in the head of the tool and an adjacent angle 2-4 degrees is defined from a center of the engaging ring to any two adjacent teeth on the engaging ring. 
     BACKGROUND OF THE INVENTION 
     A conventional ratchet tool is shown in FIGS. 1 and 2 and generally includes a head  10  with a hole  11  for receiving an engaging ring  20  therein and fastening clamps  13  are used to retain the engaging ring  20  in the hole  11 . A side hole  12  is defined in a side of the head  10  and communicates with the hole  11 . A pawl  21  is movably received in the side hole  12  and biased by a spring  22 . An end cap  23  seals the side hole  12  such that the pawl  21  and the spring  22  are retained in the side hole  12 . The pawl  21  has teeth  211  which are matched with the teeth  201  on an outer periphery of the engaging ring  20 . An inherent problem is that, as shown in FIG. 3, the torque output is small if the number of the matched teeth  211  and  201  is less than a certain amount of number. Gaps between the teeth  211 ,  201  will be too large. As shown in FIG. 4, a larger number of the matched teeth  211  and  201  requires much precise machining processes and the teeth  211 ,  201  could slide over each other because of the short height of the teeth  211 ,  201 . 
     The present invention intends to provide reinforcement teeth structure for the engaging ring and the pawl so as to increase the torque that the ratchet tool can output. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, there is provided a ratchet tool that includes a head with a hole in which an engaging ring is received, and a side hole is defined from a side of the head so as to receive a pawl biased by a spring therein. 
     The engaging ring has first teeth defined in an outer periphery thereof and which are engaged with second teeth defined in a side of the pawl. An adjust angle “a” of 2 to 4 degrees is defined between a center of the engaging ring and two points of two adjacent first teeth of the engaging ring. An angle “b” between two adjacent face of two adjacent second teeth is larger than an angle “c” between two faces of any first tooth. A height “D” of any of the first teeth is not less than a height “d” of any of the second teeth. 
     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 conventional ratchet tool; 
     FIG. 2 is a cross sectional view to show the conventional ratchet tool; 
     FIG. 3 shows the engagement of less number of teeth of the engaging ring and the pawl of a conventional ratchet tool; 
     FIG. 4 shows the engagement of to many teeth of the engaging ring and the pawl of a conventional ratchet tool; 
     FIG. 5 is a cross sectional view to show the ratchet tool of the present invention; 
     FIG. 6 shows the engagement of the teeth of the engaging ring and the pawl of the ratchet tool of the present invention, and 
     FIG. 7 shows the detail restrictions of the teeth of the engaging ring and the pawl of the ratchet tool of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 5 to  7 , the ratchet tool of the present invention comprises a head  30  having a hole  31  defined therethrough and an engaging ring  40  is rotatably received in the hole  31  and has first teeth  42  defined in an outer periphery thereof. Each of said teeth is defined by two faces intersection at an apex. The engaging ring  40  has a polygonal inside  41  so as to clamp an object to be tightened or loosened. 
     A side hole  32  is defined from a side of the head  30  and communicates with the hole  31 . A pawl  50  is biased by a spring  34  and movably received the side hole  32 . An end cap  35  threadedly seals the side hole  32  so as to restrict the spring  34  and the pawl  50  from dropping from the side hole  32 . A plurality of second teeth  51  are defined in a side of the pawl  50  and engaged with the first teeth  42  of the engaging ring  40 . The spring  34  exerts a force to urge the pawl  50  toward the engaging ring  40  so as to keep the engagement status of the first teeth  42  and the second teeth  51 . 
     An adjust angle “a” of 2 to 4 degrees is defined between a center “O” of the engaging ring  40  and apices of two adjacent first teeth  42  of the engaging ring  40 . An angle “b” between two adjacent face of two adjacent second teeth  51  is larger than an angle “c” between the two faces of any first teeth  42 . A height “D” of any of the first teeth  42  is not less than a height “d” of any of the second teeth  51 . 
     The angle “a” makes the contact area between the first teeth  42  and the second teeth  51  to be maximum and the restrictions mentioned above allows the number of the teeth  42 ,  51  for the engaging ring  40  and the pawl  50  to be optimized. 
     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.