Patent Publication Number: US-11045924-B2

Title: Folding torque wrench with fast adjustable torque value

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a torque wrench, and more particularly to a folding torque wrench, the torque value of which can be quickly adjusted. 
     2. Description of the Related Art 
     A torque wrench can be set with a torque value. When the applied torque of the torque wrench reaches the set torque value, the torque wrench will have a specific motion to remind an operator to stop wrenching. 
     A mechanical torque wrench has an elastic member inside. When adjusting the set torque value of the torque wrench, the elastic energy of the elastic member is changed.  FIG. 1  shows a conventional folding torque wrench  10 , which is a mechanical torque wrench. The folding torque wrench  10  has a front portion  11  and a front portion  12  pivotally connected with each other. An adjustment button  15  is screwed in the front portion  12  for adjusting the set torque value. When the operation torque of the wrench  10  reaches the set torque value, the front portion  11  and the front portion  12  will relatively bend around two pivotal connection sections  13 ,  14  as rotational fulcrums. 
     Please refer to  FIG. 2 . The front end of the adjustment button  15  has a threaded hole  16 . A thread  171  of a rod member  17  is screwed in the threaded hole  16 . When rotating the adjustment button  15 , the adjustment button  15  is moved in the axial direction of the rod member  17  so as to increase or decrease the elastic energy of an elastic member  18  and adjust the set torque value of the wrench  10 . 
     Such folding torque wrench is a professional wrench specifically applied to a large-size threaded member. The torque applied by such folding torque wrench always has a great value. Also, the torque value of such folding torque wrench is often adjusted within a larger range, but a small range, for example, from 600 pound-feet to 700 pound-feet. However, in such conventional folding torque wrench, the adjustment member  15  and the rod member  17  are both designed with single-start threads. When adjusting the torque value, the adjustment member  15  is displaced in the axial direction of the rod member  17  by a small distance. Therefore, it is necessary to rotate the adjustment member  15  by many circles to reach the needed torque value. This is time-consuming and needs to be improved. 
     SUMMARY OF THE INVENTION 
     It is therefore a primary object of the present invention to provide a folding torque wrench, the torque value of which can be quickly adjusted and set. 
     To achieve the above and other objects, the folding torque wrench of the present invention includes: 
     a bar body, a drive head being disposed at a front end of the bar body, a first pivotal connection section and a second pivotal connection section being disposed at a rear end of the bar body; 
     a connection rod having a pivotal connection end and a rod body, a threaded section being disposed at a rear end of the rod body, the pivotal connection end of the connection rod being pivotally connected with the first pivotal connection section of the bar body; 
     a tubular body fitted on the connection rod and slidable relative to the connection rod; 
     a linking mechanism mounted on a circumference of the tubular body and pivotally connected with the second pivotal connection section of the bar body; and 
     a torque adjustment mechanism having at least one elastic member and an adjustment member, the adjustment member being formed with a threaded hole, the threaded section of the connection rod being screwed in the threaded hole, two ends of the elastic member respectively abutting against the adjustment member and an abutment section of the tubular body, the threaded section of the connection rod and the threaded hole of the adjustment member being respectively formed as a first threaded section and a second threaded section, the first threaded section being multi-start threads of at least double-start threads, whereby when rotating the adjustment member by one circle, the adjustment member is moved in the longitudinal direction of the connection rod by a travel, which is at least two time the pitch of the first threaded section. 
     Accordingly, the displacement travel of the adjustment member is at least two time the pitch of the first threaded section. The set torque value of the wrench can be greatly adjusted only by means of rotating the adjustment member by few circles. Therefore, the torque value of the wrench can be quickly adjusted. 
     The present invention can be best understood through the following description and accompanying drawings, wherein: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a conventional folding torque wrench; 
         FIG. 2  is a sectional view of the rear end of the conventional folding torque wrench according to  FIG. 1 ; 
         FIG. 3  is a front view of a preferred embodiment of the folding torque wrench of the present invention, in which one half side of the tubular body of the wrench is sectioned to show the inside of the tubular body; 
         FIG. 4  is a view according to  FIG. 3 , in which the tubular body of the wrench is sectioned to show the inside of the tubular body; 
         FIG. 5  is a sectional view showing the pivotal connection section between the front portion and the front portion of the wrench; 
         FIG. 6  is an enlarged view of a part of  FIG. 4 ; 
         FIG. 7  is a view showing the threaded section of the connection rod of the present invention; and 
         FIG. 8  is a view according to  FIG. 3 , showing that the wrench is adjusted to a greater set torque value. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Please refer to  FIGS. 3 and 4 . According to a first embodiment, the folding torque wrench  20  of the present invention includes a front portion and a front portion of the wrench. The front portion mainly includes a bar body  30 . The front portion of the wrench mainly has a connection rod  40 , a tubular body  50  and a torque adjustment mechanism  70 . 
     A drive head  32  is disposed at a front end of the bar body  30 . The drive head  32  can be a drive head of any type of wrench. In this embodiment, the drive head  32  is, but not limited to, a ratchet structure for illustration purposes only. The drive head  32  has an insertion pin  33  for connecting with a socket (not shown). The socket can be fitted onto a threaded member to wrench the threaded member. Please refer to  FIG. 5 . A first pivotal connection section  34  is disposed at a rear end of the bar body  30 . The bar body  30  further has a forked arm  36  extending from the rear end of the bar body to one side. A rear end of the forked arm  36  forms a second pivotal connection section  37  of the bar body. 
     The connection rod  40  has a front end, which is a pivotal connection end with larger outer diameter. The connection rod  40  further has a rod body  42  securely connected with a rear end of the pivotal connection end  41 . The rod body  42  has a diameter smaller than that of the pivotal connection end  41 . A threaded section  44  with an (outer) thread is disposed at the rear end of the connection rod  40 . The pivotal connection end  41  of the connection rod is pivotally connected with the first pivotal connection section  34  of the bar body via a pivot pin  411 , whereby the connection rod  40  and the bar body  30  can be relatively rotated around the pivot pin  411  as a rotational fulcrum. 
     A front end of the tubular body  50  is fitted on the pivotal connection end  41  of the connection rod  40 . The tubular body  50  is slidable relative to the connection rod in the longitudinal direction of the connection rod  40 . An abutment section is disposed in the tubular body  50 . In this embodiment, the abutment section is a fixed block  52 , which is a hollow cylindrical body having an internal axial passage  54 . The fixed block  52  is affixed to an inner wall of the tubular body  50 . The rod body  42  of the connection rod  40  is received in the tubular body  50  and passed through the passage  54  of the fixed block  52 . The rear end of the rod body  42  extends to the rear end of the tubular body  50 . A handle  56  is securely disposed at the rear end of the tubular body  50  for a user to hold and operate the wrench. 
     Please refer to  FIG. 5 . A linking mechanism  60  is disposed on one side of the tubular body  50 . The linking mechanism  60  has a case  62  securely disposed on a circumference of the tubular body and a link member  64  disposed in the internal space of the case  62  and movable within the case. One end of the link member  64  is pivotally connected with the second pivotal connection section  37  of the bar body  30  via a pivot pin  641 , whereby the link member  64  can be swung around the second pivotal connection section  37  as a rotational fulcrum. The linking mechanism  60  is not the subject of the present invention and thus will not be further described hereinafter. 
     Please refer to  FIGS. 4 and 6 . The torque adjustment mechanism  70  is mounted in the tubular body  50 . The torque adjustment mechanism  70  includes at least one elastic member  72  and an adjustment member  74 . The elastic member  72  is a compression spring fitted on the rod body  42 . The adjustment member  74  is a cylindrical body formed with an internal axial threaded hole  75 . The threaded section  44  of the connection rod  40  is screwed in the threaded hole  75  with the (inner) thread of the threaded hole  75  screwed with the (outer) thread of the threaded section  44 . The rear end of the adjustment member  74  outward protrudes from the tubular body  50 . A cylindrical rotary button  76  with larger outer diameter is securely connected with the rear end of the adjustment member  74 , whereby an operator can rotate the adjustment member  74  via the rotary button  76 . Two ends of the elastic member  72  respectively abut against the fixed block  52  and the front end of the adjustment member  74 . In practice, the front end of the adjustment member  74  abuts against the elastic member  72  via a bearing  741  or another component. The elastic member  72  applies elastic force to the fixed block  52 , whereby the tubular body  50  is slid toward the front end of the connection rod  40 . When the front end of the tubular body  50  touches the shoulder section  412  of the pivotal connection end  41 , the tubular body  50  is located as shown in  FIG. 5 . When rotating the adjustment member  74 , the adjustment member  74  is moved in the axial direction of the connection rod  40  to increase or decrease the elastic energy of the elastic member  72  so as to adjust and set the torque value of the wrench  20 . 
     Please now refer to  FIG. 7 . In this embodiment, the rear end of the rod body  42  of the connection rod  40  has a large-diameter section  45 . The large-diameter section  45  is formed of a hollow cylindrical body fitted on the rod body  42 . The rod body  42  and the large-diameter section  45  are radially securely connected with each other by means of at least one fixing member such as at least one fixing pin  451 . The threaded section  44  is formed on a circumference of the large-diameter section  45 . The threaded section  44  is multi-start threads in a range of double-start threads to quadruple-start threads. In this embodiment, the threaded section  44  is triple-start threads  441 ,  442 ,  443  as shown in the drawings. 
     The diameter of the threaded hole  75  of the adjustment member  74  is adapted to the diameter of the large-diameter section  45 . The threads of the threaded hole  75  can be single-start threads or multi-start threads and preferably multi-start threads. In this embodiment, the threaded hole  75  is made with triple-start threads (not shown) in cooperation with the threads of the threaded section  44 . The triple-start threads of the threaded hole  75  can be known from the three threads  441 ,  442 ,  443  of the threaded section  44 . The threaded section  44  of the connection rod  40  is screwed in the threaded hole  75  of the adjustment member  74 . By means of the design of the triple-start threads, when rotating the adjustment member  74  by one circle, the adjustment member  74  is moved in the longitudinal direction of the connection rod  40  by a travel S, which is three time the pitch P of the threaded section  44 . 
     It should be noted that the threaded section  44  and the threaded hole  75  are respectively formed as a first threaded section and a second threaded section screwed with each other. The first threaded section can be the threaded section  44  of the connection rod  40 , while the second threaded section can be the threaded hole  75  of the adjustment member  74 . Alternatively, the first threaded section can be the threaded hole  75  of the adjustment member  74 , while the second threaded section can be the threaded section  44  of the connection rod  40 . In practice, the travel S of the adjustment member  74  can be several time the pitch P with only at least one threaded section is designed with multi-start threads and it is unnecessary to design both the first and second threaded sections with multi-start threads. For example, the first threaded section (such as the threaded section  44 ) is formed with multi-start threads, while the second threaded section (such as the threaded hole  75 ) is formed with multi-start threads or single-start threads. In the case that the second threaded section is formed with single-start threads, the spiral form of the single-start threads is as one of the three threads  441 ,  442 ,  443  such as the thread  441  as shown in  FIG. 7 . 
     In normal state, the tubular body  50  of the wrench  20  is substantially in parallel to the bar body  30 . The elastic member  72  applies elastic force to the fixed block  52  to push the tubular body  50  to slide forward (toward the bar body). When the front end of the tubular body  50  touches the shoulder section  412  of the pivotal connection end  41  of the connection rod  40 , the tubular body  50  is located. 
     In operation, an operator holds the handle  56  to wrench the wrench  20  so as to rotate the threaded member. When the operation torque of the wrench  20  reaches the set torque value, the linking mechanism  60  will push the tubular body  50  to move backward. Under such circumstance, the tubular body  50  overcomes the elastic energy of the elastic member  72  to move backward. Accordingly, the front portion of the wrench (the tubular body  50  and the connection rod  40 ) is rotated around the pivot pin  411  as a fulcrum and bent from the bar body  30 . At the same time, the link member  64  will angularly displace around the pivot pin  641  as a fulcrum. The bending state of the wrench  20  reminds the operator that the operation torque of the wrench  20  has reached the set torque value. The substantial bending process of the wrench that takes place when the operation torque of the wrench reaches the set torque value will not be redundantly described hereinafter. 
     When adjusting the set torque value of the wrench  20 , the adjustment member  74  is rotated to move forward or backward in the longitudinal direction of the connection rod  40  so as to change the elastic energy of the elastic member  72  and increase or decrease the set torque value. 
     In this embodiment, the threads of the threaded hole  75  of the adjustment member  74  and the threads of the threaded section  44  of the connection rod  40  are designed with the triple-start threads  441 ,  442 ,  443 . Therefore, when rotating the adjustment member  74  by one circle, the displacement travel S of the adjustment member  74  is three time the pitch P as shown in  FIG. 7 . The displacement travel is relatively large so that the adjustment member  74  can quickly move in the longitudinal direction of the connection rod  40  to quickly increase or decrease the elastic energy of the elastic member  72 . By means of such design, when it is desired to adjust the set torque value of the wrench within a large range, for example, from 600 pound-feet to 700 pound-feet, a user only needs to rotate the adjustment member  74  by few circles to make the adjustment member displace by a large travel. For example, the adjustment member can be quickly moved from the position of  FIG. 3  to the position of  FIG. 8  by a long distance. Accordingly, the torque value of the wrench can be quickly adjusted within a large range. 
     Referring to  FIG. 8 , when the adjustment member  74  is moved toward the tubular body  50 , the rear end of the tubular body  50  is moved into an annular space  78  defined between the inner circumference of the rotary button  76  and the outer circumference of the adjustment member  74 . 
     The present invention is such designed that the threaded section  44  of the connection rod  40  and the threaded hole  75  of the adjustment member  74  have multi-start threads, which are screwed with each other. In this case, the set torque value of the wrench can be quickly adjusted to save time. Such design is especially applicable to those torque wrenches with large torque value and those torque wrenches with large torque value adjustment range. 
     In the preferred embodiment, the large-diameter section  45  is disposed on the rod body  42  and the threaded section  44  with the multi-start threads is disposed on the large-diameter section  45 . In the condition that the original structure is unchanged, the structural strength of the screwing portion can be increased and the pitch P and the travel S can be enlarged so as to elongate the displacement distance of the adjustment member and speed the displacement of the adjustment member. 
     The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention.