Patent Publication Number: US-2017348836-A1

Title: Torque Wrench

Description:
BACKGROUND 
     The present invention relates to a torque wrench and, more particularly, to a torque wrench permitting adjustment of a working angle and digitally showing the adjusted torque value after a change in the working angle. 
     Generally, to precisely tighten a fastener (such as a screw, a nut, or a bolt) to a set torque value according to its original specification, a user must tighten the fastener to a certain extent and then uses a torque wrench of the set torque value to proceed with the final adjustment. 
     There are various torque wrenches available in the market. These torque wrenches can be classified into electric, hydraulic, and manual types according to the power source. Manual torque wrenches can be further classified into mechanical and electronic types. 
     U.S. Pat. No. 6,722,235 discloses a torque wrench with a scale. The torque wrench is of mechanical type and includes an adjusting knob rotatably attached to an end of a shank. A stepped protrusion is formed on the adjusting knob and is connected to a pushing bar of a torque-adjusting device. The pushing bar is rotated when the adjusting knob is rotated. Due to the threaded engagement between a pushing sleeve and the pushing bar, the pushing sleeve will move relative to the shank to compress or stretch a biasing member. Accordingly, the torque value provided by the wrench is adjusted. 
     U.S. Pat. No. 6,981,436 discloses an electronic torque wrench using strain gauges to detect the torque of the wrench which is applied to a processor through an analog-to-digital converter, and the torque value is rapidly displayed on an LCD display. Due to provision of the gauges, pivotal movement between the head and the sensory yoke is allowed to permit adjustment of the working angle, and the real torque value after a change in the lever aim resulting from adjustment of the working angle can be immediately measured through the amount of strain. 
     The mechanical torque wrenches and electronic torque wrenches are substantially different in structure. A mechanical torque wrench uses a torque release device to hint the set torque value has been reached. The torque release device generally includes a spring, a release joint, and a tappet. A user firstly sets the required torque value of the torque wrench. At this time, the spring mounted around the tappet exerts a force on the release joint. When the torque wrench is used to drive a fastener and reaches the set torque value, the torque value will be larger than the force exerted on the release joint by the spring to create an instantaneous disengagement effect. An audible sound resulting from impacting a metal housing of the torque wrench is generated to remind the user that the set torque value has been reached. Thus, mechanical torque wrenches have a complicated structure. By contrast, electronic torque wrenches only require mounting strain gauges on an ordinary wrench to achieve instant measurement of the torque value. 
     However, operation of mechanical torque wrenches is apt to be affected by obstacles in the working environments. Specifically, due to the inherent structural limitation, the working angle of a mechanical torque wrench cannot be changed after setting the torque value. Namely, the lever arm of the torque wrench is changed when the working angle varies, leading to a change in the set torque value. Thus, the mechanical torque wrench cannot obtain a precise torque value. Consequently, unlike electronic torque wrenches with strain gauges, the mechanical torque wrench cannot instantly measure the torque value after adjustment of the working angle and is, thus, difficult to provide the function of adjusting the working angle. As a result, conventional mechanical wrenches cannot change the working angle or cannot provide the precise torque value after the working angle is changed. 
     However, electronic torque wrenches completely reply on electronic components, particularly strain gauges, and, thus, have a high cost, failing to provide a high capability/price ratio. Furthermore, although an electronic torque wrench can instantly display the torque valve after the working angle is changed, the torque value continuously changes during rotation of the torque wrench rotated by the user, such that it is difficult for the user to judge whether the desired torque value is reached. Furthermore, as can be seen from FIG. 2 of U.S. Pat. No. 6,981,436, many options of the working angle between the head and the sensory yoke of the wrench result in complicated operation. 
     Thus, a need exists for a novel torque wrench to mitigate and/or obviate the above disadvantages. 
     BRIEF SUMMARY 
     A torque wrench according to the present invention includes a body having a first end and a second end. A driving device includes a connecting rod and a head. The connecting rod is pivotably connected to the first end of the body. The connecting rod includes a pivotal end and an abutting end. The pivotal end is pivotably connected to the head. The connecting rod is pivotable relative to the head between a first position and a second position. The torque wrench has a first lever arm when the connecting rod is in the first position. The torque wrench has a second lever arm when the connecting rod is in the second position. A torque device is mounted to the body and presses against the abutting end of the connecting rod. An adjusting device is movably mounted to the second end of the body and is operatively connected to the torque device for setting an initial torque value. An operating device is mounted to the body. The operating device includes a measuring unit, an operating unit, and a display. The measuring unit, the operating unit, and the display unit are electrically connected to each other. The measuring unit is configured to measure the initial torque value. 
     The operating unit has a first mode and a second mode. When the operating unit is in the first mode, the operating unit multiplies the initial torque value by a first correction coefficient corresponding to the first lever arm to obtain a first corrected torque value. When the operating unit is in the second mode, the operating unit multiplies the initial torque value by a second correction coefficient corresponding to the second lever arm to obtain a second corrected torque value. The display unit displays the first corrected torque value or the second corrected torque value according to the first mode or the second mode of the operating unit. 
     In an example, the body is a hollow cylindrical member. The connecting rod extends along a first axis. The pivotal end is spaced from the abutting end along the first axis. The head is adapted to drive a fastener to rotate about a rotating axis. The head extends along a second axis perpendicular to the rotating axis. The pivotal end of the connecting rod is spaced from the rotating axis along the second axis. The first axis is coincident with the second axis when the connecting rod is in the first position. When the connecting rod is in the second position, the first axis is at an angle of 15° to the second axis. The torque device elastically presses against the abutting end of the connecting rod. 
     In an example, a receptacle is defined in the pivotal end of the connecting rod and extends along a sliding axis perpendicular to the first axis. The pivotal end of the connecting rod includes two arms defining a pivotal groove therebetween. The pivotal groove intercommunicates with the receptacle via a passage. The head includes a pivotal portion received in the pivotal groove between the two arms. The torque wrench further includes a pivotal member extending through the two arms and the pivotal portion to permit the connecting rod to pivot relative to the head between the first position and the second position. A positioning device is mounted in the receptacle and engages with the pivotal portion of the head to position the connecting rod in the first position or the second position. 
     In an example, the pivotal portion of the head includes a toothed portion. The positioning device includes a slideable button, an elastic member, and a pawl. The slideable button is received in the receptacle, is slideable along the sliding axis perpendicular to the first axis, and includes a stepped groove having a varied depth along the first axis that varies along the sliding axis. The elastic element is mounted between a bottom wall of the receptacle and the slideable button. The pawl is received in the passage, abuts against the stepped groove of the slideable button, and engages with the toothed portion of the head. When the slideable button slides in the receptacle along the sliding axis, the pawl slides along the varied depth of the stepped groove to move along the first axis to thereby change an engagement relationship between the pawl and the toothed portion of the head. 
     In an example, the toothed portion includes a plurality of teeth. A valley is defined between two adjacent teeth. A third axis at an angle of 15° to the first axis passes through one of the valleys and a central axis of the pivotal member. 
     In an example, the abutting end of the connecting rod includes an abutting groove. The torque device includes a clutch member and a biasing member. The clutch member is biased by a biasing force provided by the biasing member to disengageably engage with the abutting groove. The biasing member is mounted between the clutch member and the adjusting device. The biasing force of the biasing member exerted on the clutch member is adjustable in response to a displacement of the adjusting device relative to the body to thereby set the initial torque value. The clutch member disengages from the abutting groove when a force larger than the initial torque valve is applied to the torque wrench. 
     In an example, the adjusting device includes a handle, a threaded member, a screw rod, and a pushing member. The handle is rotatably mounted to the second end of the body. The threaded member is mounted in the handle and includes a screw hole. The screw rod extends through and is in threading connection with the screw hole of the threaded member. The screw rod is movable relative to the threaded member along the first axis. The pushing member is mounted to an end of the screw rod opposite to the threaded member. The pushing member adjusts a pushing force exerted on the biasing member in response to a displacement of the screw rod relative to the threaded member along the first axis. 
     In an example, the adjusting device further includes an indicator mounted to the pushing member. The measuring unit senses a displacement of the indicator related to the displacement of the screw rod along the first axis to thereby measure the initial torque value that is set by the pushing member pressing against the biasing member. 
     In an example, the operating unit includes a first button, a second button, a third button. The first button is configured to set the operating unit to the first mode and to display the first corrected torque value on the display unit. The second button is configured to set the operating unit to the second mode and to display the second corrected torque value on the display unit. The first corrected torque value and the second corrected torque value are displayable on the display unit in one of two units. The third button is configured to switch the first corrected torque value or the second corrected torque value displayed on the display unit between the two units. 
     In an example, the operating unit is a printed circuit board. 
     Illustrative embodiments will become clearer in light of the following detailed description described in connection with the drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The illustrative embodiments may best be described by reference to the accompanying drawings where: 
         FIG. 1  is a perspective view of a torque wrench of an embodiment according to the present invention. 
         FIG. 2  is an exploded, perspective view of the torque wrench of  FIG. 1 . 
         FIG. 3  is a cross sectional view of the torque wrench of  FIG. 1  with a connecting rod in a first position and with an operating unit in a first mode. 
         FIG. 4  is another cross sectional view of the torque wrench of  FIG. 1  with a clutch member engaged with an abutting groove. 
         FIG. 5  is a view similar to  FIG. 4  with the clutch member disengaged from the abutting groove due to a force larger than a initial torque value set by a biasing member. 
         FIG. 6  is a diagrammatic cross sectional view illustrating use of the torque wrench of  FIG. 1  with the connecting rod in a second position and with the operating unit in the first mode. 
         FIG. 7  is a diagrammatic cross sectional view illustrating use of the torque wrench of  FIG. 1  with the connecting rod in the second position and with the operating unit in a second mode. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1-7  show a torque wrench of an embodiment according to the present invention. The torque wrench includes a body  10 , a driving device  20 , a torque device  30 , an adjusting device  40 , and an operating device  50 . 
     Body  10  includes a first end  101  and a second end  102 . In this embodiment, body  10  is a hollow cylindrical member. First end  101  of body  10  includes two flat faces respectively on two sides thereof. 
     Driving device  20  includes a connecting rod  21  and a head  22 . Connecting rod  21  is pivotably connected to first end  101  of body  10  by a pin  12 . Connecting rod  21  includes a pivotal end  211  and an abutting end  212 . Pivotal end  211  is pivotably connected to head  22 . Connecting rod  21  is pivotable relative to head  22  between a first position and a second position. The torque wrench has a first lever arm A 1  when connecting rod  21  is in the first position (see  FIG. 3 ). The torque wrench has a second lever arm A 2  when connecting rod  21  is in the second position (see  FIG. 6 ). Thus, after adjusting a working angle of the torque wrench, head  22  can directly or indirectly couple with a workpiece, such as a socket or an extension. 
     In this embodiment, connecting rod  21  extends along a first axis L 1 . Pivotal end  211  is spaced from abutting end  212  along first axis L 1 . Head  22  is adapted to drive a fastener to rotate about a rotating axis. Head  22  extends along a second axis L 2  perpendicular to the rotating axis. Pivotal end  211  of connecting rod  21  is spaced from the rotating axis along second axis L 2 . First axis L 1  is coincident with second axis L 2  (0° position) when connecting rod  21  is in the first position. When connecting rod  21  is in the second position, first axis L 1  is at an angle of 15° to second axis L 2 . Thus, the torque wrench can be positioned in the 0° position or the 15° position to avoid ineffective operation due to hindrance by obstruction during rotation of the torque wrench. 
     A receptacle  213  is defined in pivotal end  211  of connecting rod  21  and extends in a sliding axis perpendicular to first axis L 1 . Pivotal end  211  of connecting rod  21  includes two arms  214  defining a pivotal groove  215  therebetween and extending parallel to first axis L 1 . Pivotal groove  215  intercommunicates with receptacle  213  via a passage  217 . Abutting end  212  of connecting rod  21  includes an abutting groove  216 . 
     Head  22  includes a pivotal portion  221  received in pivotal groove  215  between two arms  214 . Pivotal portion  221  of head  22  includes a toothed portion  222 . In this embodiment, toothed portion  222  includes a plurality of teeth. A valley is defined between two adjacent teeth. A third axis L 3  at an angle of 15° to the first axis L 1  passes through one of the valleys and a central axis of a pivotal member  60 . First axis L 1  passes through another valley of toothed portion  222  and the central axis of pivotal member  60 . The working angle can be fixed in 0° or 15°. 
     Torque device  30  is mounted to body  10  and elastically presses against abutting end  212  of connecting rod  21 . Torque device  30  includes a clutch member  31  and a biasing member  32 . Clutch member  31  is biased by a biasing force provided by biasing member  32  to disengageably engage with abutting groove  216 . Biasing member  32  is mounted between clutch member  31  and adjusting device  40 . The biasing force of biasing member  32  exerted on clutch member  31  is adjustable in response to a displacement of adjusting device  40  relative to body  10  to thereby set the initial torque value (see  FIG. 4 ). Clutch member  31  disengages from abutting groove  216  when a force larger than the initial torque valve set by using biasing member  32  is applied to the torque wrench (see  FIG. 5 ). 
     Adjusting device  40  is movably mounted to second end  102  of body  10  and is operatively connected to torque device  30  for setting the initial torque value. In this embodiment, adjusting device  40  sets the initial torque value by pressing torque device  30 . 
     Adjusting device  40  includes a handle  41 , a threaded member  42 , a screw rod  43 , and a pushing member  44 . Handle  41  is rotatably mounted to second end  102  of body  10  and is not moveable relative to second end  102  of body  10  along first axis L 1 . Threaded member  42  is mounted in the handle  41  and includes a screw hole  421 . Screw rod  43  extends through and is in threading connection with screw hole  421  of threaded member  42 . Screw rod  43  is movable relative to threaded member  42  along first axis L 1 . Pushing member  44  is mounted to an end of screw rod  43  opposite to threaded member  42 . Pushing member  44  adjusts a pushing force exerted on biasing member  32  in response to a displacement of screw rod  43  relative to threaded member  42  along first axis L 1 . Adjusting device  40  further includes an indicator  45  mounted to the pushing member  44 . 
     Operating device  50  is mounted to body  10  and includes a measuring unit  51 , an operating unit  52 , and a display unit  53 . Measuring unit  51 , operating unit  52 , and display unit  53  are electrically connected to each other. Measuring unit  51  is configured to measure the initial torque value set by using adjusting device  40  to press against torque device  30 . Operating unit  52  has a first mode and a second mode. When operating unit  52  is in the first mode, operating unit  52  multiplies the initial torque value by a first correction coefficient corresponding to first lever arm A 1  to obtain a first corrected torque value. When operating unit  52  is in the second mode, operating unit  52  multiplies the initial torque value by a second correction coefficient corresponding to second lever arm A 2  to obtain a second corrected torque value. Measuring unit  51  senses a displacement of indicator  45  related to the displacement of screw rod  43  along first axis L 1  to thereby measure the initial torque value that is set by pushing member  44  pressing against biasing member  32 . 
     Display unit  53  displays the first corrected torque value or the second corrected torque value according to the first mode or the second mode of operating unit  52 . In this embodiment, operating unit  52  is a printed circuit board, and display unit  53  is an LCD screen. 
     Operating unit  52  includes a first button  521 , a second button  522 , a third button  523 . First button  521  is configured to set operating unit  52  to the first mode and to display the first corrected torque value on display unit  53 . Second button  522  is configured to set operating unit  52  to the second mode and to display the second corrected torque value on display unit  53 . The first corrected torque value and the second corrected torque value are displayable on display unit  53  in one of two units, such as newton-meters and pound-feet. Third button  523  is configured to switch the first corrected torque value or the second corrected torque value displayed on the display unit  53  between the two units. 
     The torque wrench further includes a pivotal member  60  and a positioning device  70 . Pivotal member  60  extends through two arms  214  and pivotal portion  221  to permit connecting rod  21  to pivot relative to head  22  to thereby adjust the working angle. Positioning device  70  is mounted in receptacle  213  and engages with head  22 . 
     Positioning device  70  includes a slideable button  71 , an elastic member  72 , and a pawl  73 . Slideable button  71  is received in receptacle  213  and is slideable along the sliding axis perpendicular to first axis L 1 . Slideable button  71  includes a stepped groove  711  having a varied depth along first axis L 1  that varies along the sliding axis. Namely, the depth of stepped groove  711  of slideable button  71  along first axis changes from an end to another end of slideable button  71  along the sliding axis. Elastic element  72  is mounted between a bottom wall of receptacle  213  and slideable button  71 . Pawl  73  is received in passage  217 , abuts against stepped groove  711  of slideable button  71 , and engages with toothed portion  222  of head  22 . When the slideable button  71  slides in receptacle  213  along the sliding axis, pawl  73  slides along the varied depth of stepped groove  711  to move along first axis L 1  to thereby change an engagement relationship between pawl  73  and toothed portion  222  of head  22 . 
     Namely, when a user presses the slideable button  71  to compress elastic element  72 , paw  73  moving along the varied depth of stepped groove  711  of slideable button  73  slides along first axis L 1  and disengages from toothed portion  222  of head  22 , and connecting head  21  is switchable between the first position and the second position. When the user stops pressing slideable button  71 , the returning force of elastic element  72  pushes slideable button  71 . Pawl  73  slides along first axis L 1  to reengage with toothed portion  222  of head  22 , achieving the positioning function. 
     Specifically, after the user uses adjusting device  40  to press against torque device  30  to set the initial torque value, when connecting rod  21  is in the first position and the initial torque value is set, operating unit  52  is switched to the first mode to obtain the first corrected torque value. The user can see the first corrected torque value from display unit  53 , which is the real torque value provided by the torque wrench in the first position. When the user switches connecting rod  21  from the first position to the second position, the initial torque value will be changed when first lever arm A 1  changes to second lever arm A 2 . Operating unit  52  is switched to the second mode to obtain the second corrected torque value, and the user can see the second corrected torque value from display unit  53 , which is the real torque value provided by the torque wrench in the second position. Thus, after the working angle is changed, the torque wrench can digitally show the corrected torque value without delicate electronic elements. Thus, the manufacturing costs can be reduced to provide the customers with a torque wrench with a high capability/price ratio. 
     When connecting rod  21  is in the first position, the user firstly uses adjusting device  40  to press against torque device  30  to set the initial torque value. Namely, operating unit  52  is selected to be in the first mode or the second mode according to the first or second position of connecting rod  21 . Namely, the user selects a suitable one of the first mode and the second mode according to the first lever arm A 1  or the second lever arm A 2  in the first position or the second position. The first corrected torque value can be obtained when operating unit  52  is switched to the first mode and can be seen from display unit  53  by the user, which is the real torque value provided by the torque wrench. In this embodiment, connecting rod  21  is in the first position relative to head  22 , first axis L 1  is coincident with second axis L 2 . Thus, the first correction coefficient is 1. Namely, the first corrected torque value is equal to the initial torque value. 
     When the user intends to changes the working angle, the slideable button  71  is pressed to compress elastic element  72 . Pawl  73  slides along the varied depth of stepped groove  711  of slideable button  71  and, thus, slides along first axis L 1  to disengage from toothed portion  222  of head  22 . Connecting rod  21  is pivotable relative to head  22  from the first position to the second position. When the user stops pressing slideable button  71 , connecting rod  21  is positioned in the second position. Accordingly, connecting rod  21  can be positioned in the first position or the second position relative to head  22 , avoiding unintentional pivotal movement of connecting rod  21  while providing easy operation of changing the working angle. 
     At this time, connecting rod  21  is positioned in the second position, and first lever arm A 1  is changed to second lever arm A 2 , leading to a change in the torque value. In this embodiment, first axis L 1  is at an angle of 15° to second axis L 2 , such that the second correction coefficient is about 0.97. Assume first lever arm A 1  is 1, when the angle between first axis L 1  and second axis L 2  is 15°, second lever arm A 2  is equal to first lever arm A 1  multiplied by cos 15°. Thus, the second corrected torque value is about 97% of the first corrected torque value. When operating unit  52  is switched to the second mode, the second corrected torque value can be obtained and can be seen from display unit  53  by the user. As a result, the user has to rotate handle  41  to increase the pressing force against biasing member  32 , such that the second corrected torque value displayed on display unit  53  is equal to the desired initial torque value. By such an arrangement, even though connecting rod  21  is positioned in the second position relative to head  22  and causes a change from first lever arm A 1  to second lever arm A 2 , the user can precisely control the torque value of the torque wrench. 
     When connecting rod  21  is switched from the second position back to the first position relative to head  22  and operating unit  52  is switched to the first mode, since second lever arm A 2  changes back to first lever arm A 1 , the first corrected torque value displayed on display unit  53  is about 103% of the initial torque value. The user has to rotate handle  41  to reduce the pressing force against biasing member  32  until the first corrected torque value displayed on display unit  53  is equal to the initial torque value. 
     Thus since the illustrative embodiments disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope is to be indicated by the appended claims, rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.