Abstract:
An adjustable torque wrench having fixed torsion value is provided with a positioning structure, through which the torsion value of the wrench can be well maintained and fixed after adjustment so as to improve work efficiency, in addition, which is further provided with a plurality of protrusions and orifices, the engagement structure between the protrusions and the orifices enables the adjustment on torsion value to be more exactly and precisely performed.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an adjustable torque wrench, and more particularly to a wrench having an ability of fixing and maintaining the torsion value after adjustment.  
         [0003]     2. Description of the Prior Arts  
         [0004]     With the improvement on the rate of utilization of the hand tools, the demand on the functions of the hand tool is increased accordingly. Adjustable torque wrench is one of the tools most commonly used, and which is mainly applied to the parts that require accurate torsion values (such as engine housing, cylinder, clutch and etc.). However, how to develop an adjustable torque wrench which torsion value can be well fixed and maintained after adjustment has become the problem that the producers want to overcome mostly and also is the motivation of the present invention.  
         [0005]     As shown in  FIG. 1 , a conventional adjustable torque wrench generally comprises a base body  10 , a central rod  11  and an adjusting handle  12 . Wherein at a first end of the base body  10  is provided with a driving head  13  and at a second end of the base body  10  an adjusting handle  12  is adjustably disposed. The central rod  11  is received in the base body  10  and fixed to the adjusting handle  12  by virtue of a fixture  14 , which revolves along with the adjustment of the adjusting handle  12 , such that the torsion value of which can be set by virtue of the adjustment of the adjusting handle  12 . However, there are still some disadvantages need to be improved in operation.  
         [0006]     The adjusting handle  12  is adjustably disposed at the second end of the base body  10 , while after the user set the torsion value according to the indicated graduation of the base body  10 , in operation, the torsion value is probably changed while the user holding the adjusting handle  12  and needs to be adjusted back to the original set torsion value again, such decreases the work efficiency.  
         [0007]     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional adjustable torque wrench.  
       SUMMARY OF THE INVENTION  
       [0008]     The primary object of the present invention is to provide an adjustable torque wrench having fixed torsion value that is provided with a positioning structure, through which the torsion value can be fixed and maintained after adjustment whereby to increase work efficiency.  
         [0009]     Another object of the present invention is to provide an adjustable torque wrench having fixed torsion value that is provided with a plurality of protrusions and orifices, the engagement structure between the protrusions and the orifices enables the adjustment on torsion value to be more exactly and precisely performed.  
         [0010]     The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which shows, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a plan view, partly in section, of a conventional adjustable torque wrench;  
         [0012]      FIG. 2  is an exploded view of an adjustable torque wrench in accordance with the present invention;  
         [0013]      FIG. 3  is a side view of the adjustable torque wrench in accordance with the present invention;  
         [0014]      FIG. 4  is a cross sectional view of the adjustable torque wrench in accordance with the present invention;  
         [0015]      FIG. 5  is another cross sectional view of the adjustable torque wrench in accordance with the present invention;  
         [0016]      FIG. 6  is a partial amplified view of the adjustable torque wrench in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]     Referring to  FIGS. 2-4 , an adjustable torque wrench having fixed torsion value in accordance with the present invention generally comprises a wrench body  20 , a central rod  30 , a positioning block  40 , an engaging member  50 , an adjusting handle  60 , a fixture  70  and a limiter  80 .  
         [0018]     The wrench body  20  is a tubular member and provided with a driving head (not shown) at an end and an aperture  21  at another end.  
         [0019]     The central rod  30  is provided with a peripheral shoulder  31 , connecting to the shoulder  31  is a toothed portion  32  formed, while next to the toothed portion  32  is defined with a threaded portion  33 . The central rod  30  is received in the wrench body  20  and able to change the torsion value of the wrench after adjustment.  
         [0020]     The positioning block  40  is provided at the periphery with a hole  41  and two grooves  42  respectively; the positioning block  40  is corresponding to the aperture  21  of the wrench body  20  and positioned in the wrench body  20  by virtue of a pin  43 .  
         [0021]     The engaging member  50  has a hole  51  defined thererof, around the contiguous periphery of the hole  51  a plurality of orifices  52  are defined, the engaging member  50  is further provided at both sides with an inserting plate  53  respectively. The engaging member  50  serves to mount onto the central rod  30  with the two inserting plates  53  inserted in the two grooves  42  of the positioning block  40  respectively while the hole  51  abutting against the shoulder  31  of the central rod  30 .  
         [0022]     The adjusting handle  60  has a transmission block  61  disposed at an end; the transmission block  61  is provided with a toothed hole  62 , a first end surface  63  and a second surface  64  with corresponding to each other. Contiguous to the toothed hole  62  four inserting holes  621  are formed thereof. The first end surface  63  is annularly provided with a plurality of protrusions  631  while the second end surface  64  is alike annularly provided with a plurality of apertures  641 . The adjusting handle  60  is adjustably disposed at the end of the wrench body  20  in a manner that the protrusions  631  engaged with the orifices  52  respectively, the toothed hole  62  engaged with toothed portion  32  of the central rod  30  and the threaded portion  33  of the central rod  30  protrudes out of the toothed hole  62 . By adjusting the handle  60  the central rod  30  is revolved accordingly.  
         [0023]     The fixture  70  is provided with a pair of ear portions  71 , at one of the ear portions  71  a recess  72  is formed for receipt of a resilient device  73 , the resilient device  73  consists of a spring  731  and a steel ball  732 . The steel ball  732  is able to timely protrude out of the mouth of the recess  72 . The fixture  70  serves to screw on the threaded portion  33  of the central rod  30  and the steel ball  732  of resilient device  73  engages with corresponding apertures  641  of the transmission block  61 .  
         [0024]     The limiter  80  is a column member and removably inserted in one of the inserting holes  621  of the transmission block  61 , furthermore, the limiter  80  corresponding to the two ear portions  71  of the fixture  70  and serves to prevent the loose of the fixture  70  after the same is screwed on the central rod  30 .  
         [0025]     Referring now to  FIG. 4 , in which, in case that the user adjusts the adjusting handle  60  to a predetermined torsion value, then revolves the fixture  70 , the fixture  70  presses against the second end surface  64  of the transmission block  61  and the first end surface  63  of the transmission block  61  presses against the engaging member  50  accordingly, while the engaging member  50  then will press the shoulder  31  of the central rod  30 . In addition, due to the two inserting plates  53  of the engaging member  50  insert in the two grooves  42  of the positioning block  40 , and the positioning block  40  and wrench body  20  are positioned with relative to each other (that is to say the positioning block  40  is unable to revolve with respect to the wrench body  20 ). Accordingly, the position of the adjusting handle  60  can be locked completely after it is adjusted, such that the torsion value of wrench will not be changed during operation and the work efficiency is accordingly increased.  
         [0026]     In addition, in case that wants to change the torsion value of adjustable torque wrench, the user can unscrew the fixture  70  initially, and then adjust the adjusting handle  60  to a desired force indicated on the graduator of the wrench base  20 , and finished by screwing up the fixture  70 .  
         [0027]     Referring again to  FIG. 3 , in which, in case of a loose state of the fixture  70 , due to the limiter  80  is inserted in the transmission block  61  and located in the revolving scope of the fixture  70 . In other words, in case of revolution of the fixture  70 , which ear portions  71  stopped by the limiter  80  and unable to revolve further. In this case, the fixture  70  only can be unscrewed in a certain range and unable to be disengaged from the threaded portion  33  of the central rod  30 . Such that prevent the toothed portion  32  of the central rod  30  disengaging from the toothed hole  62  of the transmission block  61  of the adjusting handle  60 , and further prevent the failure of the wrench in adjusting the predefined torsion value.  
         [0028]     On the other hand, with referring to  FIGS. 5,6 , in which, in case of revolution of the fixture  70 , the steel ball  732  in the fixture  70 , under the pressure of the internal surface of the aperture  641  of the transmission block  61 , moves within the recess  72 , which steel ball  732  will not engage in the aperture  641  again until next aperture  641 , such that the fixture  70  is positioned. After the fixture  70  is unscrewed, the adjusting handle  60  is allowed to be pulled toward the fixture  70  such that the transmission block  61  doesn&#39;t tightly abut against the engaging member  50  any more and then the adjusting handle  60  is able to adjust the torsion value. In operation, due to the transmission block  61  is annularly provided with a plurality of protrusions  631  and the engaging member  50  is annularly provided with a plurality of orifices  52 , the adjusting handle  60  is allowed to adjust the torsion value based on the distance of the adjacent paired orifices  52  (protrusions  631 ) such that ensures the torsion adjustment to be more exactly and precisely performed.  
         [0029]     While we have shown and described various embodiments 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.