Patent Publication Number: US-6981433-B2

Title: Ratchet wheel mounting structure for wrench

Description:
The present invention is a continuation in part (CIP) of U.S. patent Ser. No. 10/213,301, now abandoned, filed Aug. 7, 2002, assigned to the inventor of the present invention, thereby, the content of U.S. patent Ser. No. 10/213,301 is incorporated into the present invention as a part of the present invention. 

   FIELD OF THE INVENTION 
   The present invention relates to wrenches, and more specifically, to a ratchet wheel mounting structure for wrench, which achieves high performance. 
   BACKGROUND OF THE INVENTION 
     FIGS. 1 and 2  show two different ratchet wheel designs according to the prior art. These ratchet wheels are made through latching and milling processes, having R-angle or straight teeth. The teeth of these ratchet wheels wear quickly as used for a longer time and have low torque values. Further, when the prior art wrench is engaged with the toothed stop block in the box of the wrench, but, in this prior art, output force is not fully transferred from the wrench to the ratchet wheel and then to a workpiece.  FIG. 3  shows still another design of ratchet wheel according to the prior art. According to this design, the ratchet wheel has a disk-like reinforcing structure integrally formed with the teeth at one end to reinforce the structural strength of the teeth. In either of the aforesaid three prior art ratchet wheel designs, the two distal ends of each teeth of the ratchet wheel art has right angles with respect to the base locating the teeth. When the wrench is twisted to rotate a workpiece, the teeth of the ratchet wheel may break easily, and the friction between the ends of each teeth of the ratchet wheel and the inside wall of the box of the wrench affects the performance of the wrench. Another drawback of the aforesaid prior art ratchet wheel designs is the difficulty in installing the C-shaped retainer ring. Because if the width of the two distal ends of the C-shaped retainer ring that secures the ratchet wheel in the box of the wrench is equal to the width of the locating groove of the ratchet wheel, it is not easy to fasten the C-shaped retainer ring to the locating groove of the ratchet wheel. Furthermore, because the pressure angle of the aforesaid prior ratchet wheel designs is 14.5° or 20 degrees, the engagement between the teeth and the stop block is not in coincidence with the pressure line, resulting in weak structural strength. 
   SUMMARY OF THE INVENTION 
   The present invention has been accomplished to provide a ratchet wheel mounting structure, which eliminates the aforesaid drawbacks. 
   It is one object of the present invention to provide a ratchet wheel mounting structure which comprises a ratchet wheel mounted in a box of a wrench body and meshed with a toothed stop block in said box, and a retainer ring mounted in between said box and said ratchet wheel to secure said ratchet wheel to said box, said ratchet wheel having teeth arranged around the periphery thereof, a locating block at one side of the ratchet wheel, and a locating groove being formed around the periphery of said locating block for positioning said retainer ring. Each tooth of said ratchet wheel is chamfered at one end thereof far away from the locating block; and a reinforcing bevel is provided in the valley between roots of another ends of each two adjacent teeth of said ratchet wheel adjacent to said locating block. Or each tooth is chamfered at two ends and thus no bevel slop is formed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a ratchet wheel of the prior art. 
       FIG. 2  illustrates another structure of the ratchet wheel of the prior art. 
       FIG. 3  illustrates still another structure of the ratchet wheel of the prior art. 
       FIG. 4  is an exploded view showing the structure of a ratchet wheel and a C-shaped retainer ring according to the present invention. 
       FIG. 5  is a plain view of the ratchet wheel according to the present invention. 
       FIG. 6  is a schematic view illustrating the chamfer angle of the teeth of the ratchet wheel. 
       FIG. 7  is a side view of the ratchet wheel according to the present invention. 
       FIG. 8  is a side view of an alternate form of the ratchet wheel according to the present invention. 
       FIG. 9  is a schematic view illustrated the best pressure angle. 
       FIG. 10  is a plain view of a ratchet wheel with teeth of equal angle tooth form according to the present invention. 
       FIG. 11  is a plain view of a ratchet wheel with teeth of unequal angle tooth form according to the present invention. 
       FIG. 12  is a schematic drawing explaining the design of the C-shaped retainer ring according to the present invention. 
       FIG. 13  is a sectional view showing the ratchet wheel installed in the box of the wrench and meshed with the toothed block in the box according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 4 ,  5  and  13 , a ratchet wheel  20  and a stop block  30  are mounted in the box  11  of a wrench body  10 . The stop block  30  is a toothed member engaged with the ratchet wheel  20  and adapted to control the direction of rotation of the ratchet wheel  20 . 
   The ratchet wheel  20  has teeth  21  arranged around the periphery thereof, a locating block  22  at one side thereof, and a locating groove  221  extended around the locating block  22  for the positioning of a retainer ring  40 , which secures the ratchet wheel  20  to the inside of the box  11  of the wrench body  10 . The outer diameter of the locating block  22  is equal to the outer diameter around the teeth  21 . 
   Referring to  FIG. 6 , each tooth  21  has a chamfered end  211  at one end thereof. Further, a reinforcing bevel end  212  is provided in the valley between another ends of each two adjacent teeth  21  adjacent to the locating block  22 . The structure will reinforce the structural strength of the teeth for smooth rotation. The retainer ring  40  is a C-shaped ring. Referring to  FIG. 12 , the ring  40  has two ends and each end has a respective cut angle  41 ,  42  at an inner side thereof for quick installation. By means of the aforesaid features, the ratchet wheel  20  is strong and wear resistant, and can easily be installed in the wrench for smooth operation. 
   Referring to  FIGS. 7 and 8 , another embodiment of the present invention is illustrated. In this embodiment, each tooth  21  has chamfer ends  211  at two ends thereof. The structure will reinforce the structural strength of the teeth for smooth rotation. Similarly, the retainer ring  40  is a C-shaped ring. The Ring  40  has two ends and each end has a respective cut angle  41 ,  42  disposed at two inner sides thereof for quick installation. By means of the aforesaid features, the ratchet wheel  20  is strong and wear resistant, and can easily be installed in the wrench for smooth operation. 
   As shown in  FIG. 9 , a pressure angle θ is illustrated. The pressure angle is an angle between two tangent lines tangent from two points on the periphery of the ratchet wheel, where the two points are distant with one teeth. 
   In  FIG. 9 , the engagement between the stop block  30  and the ratchet wheel  20  is illustrated that the pressure angle θ of the ratchet wheel  20  is set within 10˜13°. In this case, the applied force F of the wrench drives the teeth  21  of the ratchet wheel  20  perpendicularly. According to the principle of transmission of force, the output force is 100% when pushing the load with a force F at right angle, but if a force F is applied to the work piece at a tilted angle, and ineffective component of force will be produced during the output of force F, and the output of force will be below 100%. The greater the contained angle of the tilted output force is, the greater the ineffective component of force will be. By means of the aforesaid tooth arrangement, the effective component of force to the ratchet wheel is greatly increased to improve the working efficiency of the wrench. 
   Referring to  FIGS. 10 and 11 , the teeth of the ratchet wheel can be either of unsymmetrical type of equal angle design, as shown in  FIG. 10 , wherein the two angles θ 1  and θ 2  are unequal (where θ 1  and θ 2  are angles of one of two adjacent sides and a radial line passing through the apex of the connection of the two sides), or symmetrical type of unequal angle design, as shown in  FIG. 11 , wherein the two angles θ 1  and θ 2  are unequal. 
   Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.