Patent Publication Number: US-6666111-B1

Title: Wrench teeth arrangement for ratchet tools

Description:
FIELD OF THE INVENTION 
     The present invention relates to a wrench that has an engaging ring with 90 to 180 teeth so that the wrench outputs torque within a small angle of rotation. 
     BACKGROUND OF THE INVENTION 
     A conventional wrench generally includes a head with an aperture with which an engaging ring is engaged. The engaging ring includes a polygonal hole so as to mount onto a nut or a bolt head. A pawl is movably received in the head and engaged with the teeth defined in an outer periphery of the engaging ring such that the engaging ring can be maintained stationary relative to the rotation of the wrench, or co-rotatable with the rotation of the wrench. Nevertheless, there is a gap between the teeth of the engaging ring and the pawl so that when the wrench is rotated a small angle the teeth of the engaging ring do not match with the pawl. Therefore, when the wrench is used in a narrow space which allows the wrench to be rotated only a limited angles, no torque can be exerted on the object to be tightened or loosened. 
     The present invention intends to provide a wrench which has an engaging ring with 90 to 180 teeth so as to response any angle of rotation of the wrench. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, there is provided a ratchet wrench includes an engaging ring rotatably engaged with a hole in the head and the engaging ring has first teeth defined in an outer periphery thereof so as to be engaged with second teeth of a pawl movably received in a side hole in the head. A distance between two adjacent second teeth of the pawl is twice the distance of two adjacent first teeth of engaging ring. 
     The primary object of the present invention is to provide a wrench that is able to output a torque within a small angle of rotation. 
    
    
     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 wrench; 
     FIG. 2 shows steps of method for making the engaging ring with 90-180 teeth; 
     FIG. 3 shows the initial product of the engaging ring; 
     FIG. 4 shows the initial product of the engaging ring is proceeded by way of center grinding; 
     FIG. 5 shows the initial product of the engaging ring is proceeded by way of centerless grinding; 
     FIG. 6 shows the initial product of the engaging ring is proceeded by way of rolling; 
     FIG. 7 is a perspective view to show the final product of the engaging ring; 
     FIG. 8 is a cross sectional view to show the ratchet tool; 
     FIG. 9A shows that the second teeth of the pawl are engaged with the first teeth of the engaging ring; 
     FIG. 9B shows that the second teeth of the pawl are disengaged from the first teeth of the engaging ring; 
     FIG. 10 is an exploded view to show another embodiment of the ratchet wrench of the present invention; 
     FIG. 11 is a cross sectional view to show the ratchet tool as shown in FIG. 10; 
     FIG. 12A shows that the second teeth of the pawl are engaged with the first teeth of the engaging ring of the embodiment shown in FIG. 10, and 
     FIG. 12B shows that the second teeth of the pawl are disengaged from the first teeth of the engaging ring of the embodiment shown in FIG.  10 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1,  8 ,  9 A and  9 B, the ratchet wrench  1  of the present invention comprises a head  10  with a hole  11  defined therethrough and an engaging ring  20  is rotatably engaged with the hole  11 . The engaging ring  20  has first teeth defined in an outer periphery thereof and a polygonal inner periphery for being engaged with a polygonal object such as a nut (not shown). A side hole  12  is defined in the head  10  and communicates with the hole  11 . A pawl  211  is movably received in the side hole  12  and has second teeth which are engaged with the first teeth of the engaging ring  20 . The side hole  12  is sealed by a bolt  22  and a spring  21  is biased between the bolt  22  and the pawl  211 . A distance between two adjacent second teeth of the pawl  211  is twice the distance of two adjacent first teeth of the engaging ring  20 . This arrangement ensures that the first teeth are engaged with the second teeth even if the ratchet wrench  1  is rotated only a small angle. Therefore, the ratchet wrench  1  can be used in a narrow space. 
     Referring to FIGS. 10,  11 ,  12 A and  12 B, the ratchet tool can also be made to have the engaging ring  20 ′ have first teeth such as 72 teeth and the pawl  212  has second teeth, wherein a distance between two adjacent first teeth of the engaging ring  20 ′ is twice the distance of two adjacent second teeth of the pawl  212 . 
     Referring to FIGS. 2 to  7 , the engaging ring  20  can be made by the following steps which are: 
     step 1: forging; 
     step 2: annealing; 
     step 3: trimming: 
     step 4: grinding: 
     step 5: rolling: 
     step 6: heat treatment; and 
     step 7: surface treatment. 
     An initial product of the engaging ring  10  is made in step 1 as shown in FIG.  3  and the initial product of the engaging ring  10  is then proceed by annealing twice preferably. The initial product of the engaging ring  10  is then trimmed by using a lather and ground by way of center grinding or centerless grinding so as to obtain a precision of 1μ to 5μ as shown in FIGS. 4 and 5. 
     A second initial product of the engaging ring  13  is made to have 90 to 180 teeth as shown in FIG.  6 . The second initial product of the engaging ring  13  is then proceeded through step 6 and step 7 to obtain the final product. 
     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.