Patent Publication Number: US-6990877-B1

Title: Torque wrench

Description:
RELATED U.S. APPLICATIONS 
   Not applicable. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable. 
   REFERENCE TO MICROFICHE APPENDIX 
   Not applicable. 
   FIELD OF THE INVENTION 
   The present invention relates generally to a torque wrench, and more particularly to a torque wrench which comprises improved structure of overload movement. 
   BACKGROUND OF THE INVENTION 
   To avoid structural damage from excessive external force, the torque wrench is typically designed with overload protective measures. So, in case where the applied force of the pressure handle exceeds the preset value, the sheath end and pressure handle will move alternatively, thus preventing structural damage arising from continuous application of force by the user. With regard to a conventional structure of overload protective measure, a ratchet ring is typically mounted within the groove at the sheath end of torque wrench. The interior of the ratchet ring is provided with a supporting surface for articulation during positive and reverse rotation of sheath end, whereas the exterior of the ratchet ring is normally positioned securely by a flexible bead. In case the applied force of the pressure handle of torque wrench exceeds the preset value, the sheath end will activate the ratchet outside the ratchet ring to forcibly cross over the flexible bead, thus the sheath end and pressure handle will move alternatively to prevent structural damage. However, it has been found from practical experience that, owing to the sharp ratchet of ratchet ring, a bigger frictional wear will likely occur between the ratchet and groove of torque wrench during the former one crossing the flexible bead. In such case, the ratchet of ratchet ring will be broken and deformed rapidly, thus reducing the intended function of overload protection at the handle end and greatly shortening the service life of torque wrench. Also, it is unlikely to preset accurately the torque due to the strong friction of movement, leading to an unstable state against ideal utility model. Additionally, there is available with another typical structure for overload protection that is mounted onto the middle section of the pressure handle of the torque wrench. The principle of operation is that overload protection can be achieved through alternative movement of two components. However, if the end users continue to apply force during the movement, the component at one side will further bump the structural body of the pressure handle, leading to consequent damage. 
   Therefore, with a view to the above-mentioned disadvantages of typical torque wrench, this industry shall assume the responsibility to make some pioneering R&amp; D and innovations for an ideal utility model. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention can offer an improved efficiency as detailed below. 
   To provide an innovative structure of a torque wrench that the exterior of the overload movement ring  40  is designed with a polygon, and a containment groove  43  is installed at the intersection of various surfaces  42  to accommodate the rolling rod  51  and rolling bead  52 . This is a preferred option of this Industry in conformity with the requirements of new patent. 
   Based upon the modified structural design, as the overload movement ring  40  is placed in a rolling contact state through the rolling rod  51 , rolling bead  52  and the assembly groove  21 , it is possible to reduce considerably the wear, protect against deformation and prolong the service life of components. 
   Given the rolling contact feature through the rolling rod  51 , rolling bead  52  and assembly groove  21 , it is feasible to preset more accurate torque as the overload movement ring  40  can move more smoothly. 
   Based upon the polygonal structural design of overload movement ring  40 , in the case of every movement of torque wrench, the bolster  63  of the movable shore  61  will cross over a rolling rod  51  for flexible reduction, and then protrude and support the next surface  42  to restore initial state. In case where the torque wrench of the present invention moves continuously, the applied force of bolster  63  will present an up-and-down recycling state, thus yielding no structural damage for permanent use and excellent durability. 
   The new advantages of this invention are as follows: 
   Based upon the structural design that various surfaces  42 B of overload movement ring  40  can be designed with a concave arch, it is possible to promote the torque as it provides a bigger grading angle to the bolster  63  of the movable shore  61  when crossing over the rolling rod  51  and rolling bead  52 . Furthermore, this design can prevent continuous cross/movement as the bolster is securely fixed onto the next surface. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  shows a perspective view of the present invention. 
       FIG. 2  shows an exploded perspective view of the internal of the invention 
       FIG. 3  shows a local magnified perspective view of  FIG. 2 . 
       FIGS. 4–5  shows sectional views of the present invention. 
       FIG. 6  shows another sectional view the overload state of the torque wrench. 
       FIG. 7  shows a partial magnified sectional view of the peripheral plane of the overload movement ring. 
       FIG. 8  shows another partial magnified sectional view of the application of the bolster of movable shore. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The features and the advantages of the present invention will be more readily understood upon a thoughtful deliberation of the following detailed description of a preferred embodiment of the present invention with reference to the accompanying drawings. 
   As shown in  FIGS. 1–4 , there is a torque wrench embodied in the present invention. 
   The invention has a pressure handle  10 , which is provided internally with a hollow hole  11 . 
   The invention also has a sheath end  20 , which is provided at one side of the pressure handle  10 , and equipped with an assembly groove  21 . The assembly groove is provided with a threaded hole  22  at the bottom, while one side of the assembly groove  21  opposite to the pressure handle  10  is connected to the hollow hole  11 . 
   There is also a directional brake module  30 , which is mounted within the assembly groove  21  of the sheath end, being comprised of a sheath rod  31 , a brake section  32  and a control unit  33 . The sheath rod  31 , generally designed with a square column, can cross through the threaded hole  22  of the assembly groove  21 , whereas the brake section  32  of many types can be provided at the middle section. As shown in the attached drawing, it can be designed with a reversible block, each end of which is provided with positive and reverse brake tooth rim  34 ,  35 , respectively. The control unit  33 , designed with a rotary button, is provided at the top, whereby the end users can manually adjust and control the direction (i.e. positive and reverse brake tooth rim for optional articulation) of the brake section  32 . 
   The invention also includes an overload movement ring  40 , which is provided between the brake section  32  of directional brake module  30  and assembly groove  21 . The interior of the overload movement ring  40  is designed with a circular tooth rim  41  for the articulation/brake of the brake section  32  of directional brake module  30 , while the exterior is designed with a polygon. Moreover, a containment groove  43  is provided at the intersection of various surfaces  42  penetrating both sides, and the exterior of various containment grooves is designed with a reducing aperture  44  corresponding to the wall of assembly groove  21 . 
   The invention has a rolling rod  51  and rolling bead  52 , which are provided within various containment grooves  43  at the exterior of overload movement ring  40 . In detail, each end of a rolling rod  51  is equipped a rolling bead  52 , thus the outer flank of various rolling rods  51  and rolling beads  52  will protrude the aperture  44  of the containment groove  43 , and then keep in close contact with the wall of the assembly groove  21 . 
   There is also a spring bolster  60 , provided within the hollow hole  11  of the pressure handle  10 , comprised of a movable shore  61  and a spring  62 . One end of the movable shore  61  is supported by the spring  62  while the other end has a bolster  63  that crosses over the assembly groove  21  of the sheath end  20 , and supports a surface  42  corresponding to the exterior of the overload movement ring  40 . This will help brake the overload movement ring  40  (namely avoiding movement). 
   As shown in  FIG. 4 , various surfaces  40  of peripheral polygon of the overload movement ring  40  can be designed with a plain edge. 
   As shown in  FIG. 7 , various surfaces  40 B of peripheral polygon of the overload movement ring  40  can also be designed with a concave arch. As compared with the above-specified plain edge, this structural design can promote the torque as it provides a bigger grading angle to the bolster  63  of the movable shore  61  when crossing over the rolling rod  51  and rolling bead  52 . Furthermore, this design can prevent continuous cross/movement as the bolster is securely fixed onto the next surface. 
   As shown in  FIG. 4 , the bolster  63  of the movable shore  61  is designed with a groove  64  wherein a rolling bead  65  is placed. Once the friction takes place between the overload movement ring  40  and bolster  63 , it can help reduce the friction coefficient to guarantee a smooth movement thanks to its rolling feature of rolling bead  65 . 
   As shown in  FIG. 8 , the bolster  63 B of the movable shore  61  can also be designed with a circular flange at the end of the movable shore  61 . 
   Based upon the above-specified structure and construction of torque wrench for this utility model, the exterior surface  42  of the overload movement ring  40  is supported flexibly by the bolster  63  of the movable shore  61  as shown in  FIG. 4 , with the elastic force depending on the spring  62 . Under normal service state, the supporting force of the bolster  63  is enough to activate the overload movement ring  40  to rotate simultaneously, namely capable of screwing the bolt when it activates the sheath rod  31  of directional brake module  30  to rotate. But, if the resistance arising from screwing the bolt is bigger than the force fixing the overload movement ring  40 , it will be activated by the sheath rod  31 . In such case, the exterior of the overload movement ring  40  is placed in a rolling contact state through the rolling rod  51 , rolling bead  52  and the assembly groove  21  of the sheath end  20 , enabling the overload movement ring  40  to generate rotary motion within the assembly groove  21 . During rotation, the bolster  63  of the movable shore  61  will cross over a rolling rod  51  from the surface  42  of overload movement ring  40  (as shown in  FIG. 6 ), then stop at the next surface  42 . Finally, it will be placed into initial supporting state again.