Patent Publication Number: US-6334377-B1

Title: Adjustable torque wrench having a lock device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an adjustable torque wrench, and more particularly to an adjustable torque wrench having a lock device for lock the adjustable torque wrench and for preventing the adjustable torque wrench from being further adjusted or rotated after the adjustable torque wrench has been adjusted to the required driving torque. 
     2. Description of the Prior Art 
     U.S. Pat. No. 4,870,879 to Shieh discloses a typical adjustable torque wrench including a ratchet arm received in a shank, a spring and a sleeve engaged with the ratchet arm via a roller seat and a roller, and a knob coupled to the spring for adjusting the biasing force of the spring against the ratchet arm. However, the knob may not be locked and may be rotated or driven inadvertently during the operation of the adjustable torque wrench. 
     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional adjustable torque wrenches. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide an adjustable torque wrench including a lock device for lock the adjustable torque wrench and for preventing the adjustable torque wrench from being further adjusted after the adjustable torque wrench has been adjusted to the required driving torque. 
     In accordance with one aspect of the invention, there is provided an adjustable torque wrench comprising a shank including a first end and a second end, a driving head including a ratchet arm received in the first end of the shank, a follower received in the second end of the shank, a spring engaged between the follower and the ratchet arm to apply a spring biasing force against the ratchet arm, means for moving the follower relative to the spring to adjust the spring biasing force of the spring against the ratchet arm, and means for locking the follower to the shank and to prevent the follower from moving relative to the shank. 
     The moving means includes a handle threaded onto the second end of the shank, and means for guiding the follower to slide relative to the shank and to prevent the follower from rotating relative to the shank, the shank is rotated relative to the handle by the follower in order to move and to adjust the follower relative to the shank when the follower and thus the shank are rotated relative to the handle. 
     The guiding means includes at least one longitudinal groove formed in the shank, and a pin engaged through the follower and slidably engaged in the longitudinal groove of the shank. 
     A device is further provided for adjusting the follower relative to the handle and includes a lock fastener threaded to the handle and engaged with the follower, the follower is moved and adjusted relative to the handle when the lock fastener is rotated and threaded relative to the handle. 
     A lock nut is further threaded onto the lock fastener and selectively engaged with the handle in order to lock the lock fastener to the handle. 
     A knob is further provided and secured to the follower in order to rotate the follower relative to the handle. The locking means includes a control ferrule engaged on the knob and selectively engaged onto the handle in order to lock the knob to the handle and to prevent the knob from being rotated relative to the handle. 
     The handle includes at least one longitudinal tooth formed thereon, the knob includes at least one longitudinal tooth formed thereon, the control ferrule includes at least one longitudinal tooth formed thereon and slidably engaged with the longitudinal teeth of the handle and the knob in order to prevent the knob from being rotated relative to the handle when the control ferrule is engaged with the handle. 
     A device is further provided for retaining the control ferrule to the knob and includes a spring-biased projection provided in the knob and engaged with the control ferrule to secure the control ferrule to the knob. 
     Further objectives and advantages of the present invention will become apparent from a careful reading of a detailed description provided hereinbelow, with appropriate reference to accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded view of an adjustable torque wrench in accordance with the present invention; 
     FIG. 2 is a perspective view of of the adjustable torque wrench; 
     FIG. 3 is a cross sectional view taken along lines  3 — 3  of FIG. 2; and 
     FIG. 4 is a cross sectional view similar to FIG. 3, illustrating the operation of the adjustable torque wrench. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings, and initially to FIGS. 1-3, an adjustable torque wrench in accordance with the present invention comprises a shank  10 , a driving head  11  having a ratchet arm  19  extended therefrom and received in the shank  10 , a roller seat  70  slidably received in the shank  10  and having a roller  71  for engaging with the ratchet arm  19 , and a spring  15  received in the shank  10  and biased against the ratchet arm  19 , and an adjusting device is provided for adjusting the biasing force against the ratchet arm  19  in order to adjust the driving torque of the torque wrench. The above-described configuration is not related to the present invention and has been disclosed in U.S. Pat. No. 4,870,879 to Shieh which is taken as a reference of the present invention. 
     The shank  10  includes one or more, particularly two longitudinal slots or grooves  12  formed in the end portion, such as the lower end portion thereof distal to the driving head  11 . A follower  13  is slidably received in the shank  10  and engaged with the spring  15 . A pin  14  is engaged through the follower  13  and slidably engaged in the grooves  12  of the shank  10  in order to guide the follower  13  to slide in the shank  10  only and to prevent the follower  13  from being rotated relative to the shank  10 . The follower  13  includes an extension  16  having a diameter smaller than that of the follower  13  for forming a peripheral shoulder  17  between the follower  13  and the extension  16 . The shank  10  includes an outer thread  18  formed in the outer portion of the lower end portion thereof. 
     A handle  20  includes an inner thread formed therein for threading with outer thread  18  of the shank  10 , such that the handle  20  may be moved toward and away from the driving head  11  when the handle  20  is rotated or threaded relative to the shank  10 . The handle  20  includes one end, particularly the lower end portion having one or more longitudinal ribs or teeth  24  formed on the outer peripheral portion thereof. A lock fastener  21  is threaded to the lower end of the handle  20  and includes an orifice  22  formed therein for receiving the extension  16  of the follower  13 . The lock fastener  21  is engaged with the follower  13  for retaining the follower  13  within the shank  10  and may be rotated or threaded relative to the shank  10  in order to move the follower  13  relative to the spring  15  and in order to micro-adjust the spring biasing force of the spring  15  against the follower  13  and/or the ratchet arm  19 . Another lock fastener, such as a lock nut  23  may further be provided and threaded onto the lock fastener  21  and engaged with the handle  20  so as to lock and to secure the lock fastener  21  to the handle  20 . 
     A knob  26  is secured to the extension  16  with one or more fasteners  27  or with the keys or with the latches etc., and is thus secured to the follower  13 , such that the follower  13  and thus the shank  10  may be rotated relative to the handle  20  by the knob  26 . The knob  26  includes one or more longitudinal ribs or teeth  28  formed on the outer peripheral portion thereof and includes a spring-biased projection  29  provided therein. A control ferrule  30  is slidably engaged on and between the lower end of the handle  20  and the knob  26 , and includes one or more longitudinal channels or ribs or teeth  31  formed on the inner peripheral portion thereof for engaging with the longitudinal ribs or teeth  24 ,  28  of the handle  20  and of the knob  26  and for guiding the control ferrule  30  to slide relative to the handle  20  and the knob  26  only and to prevent the control ferrule  30  from being rotated relative to the handle  20  and the knob  26 . 
     As shown in FIG. 4, the control ferrule  30  may be moved onto the knob  26  and may be moved away from or disengaged from the handle  20  in order to disengage the channels or the ribs or the teeth  31  of the control ferrule  30  from the ribs or the teeth  24  of the handle  20 . When the control ferrule  30  is disengaged from the handle  20 , the knob  26  may be rotated relative to the handle  20  in order to rotate the follower  13  and thus the shank  10  relative to the handle  20 , such that the shank  10  may be rotated relative to the handle  20  and may thus be moved toward and away from the knob  26  and guided by the sliding engagement of the pin  14  in the grooves  12  of the shank  10 . The shank  10  may thus be slided or moved relative to the follower  13  in order to adjust the spring biasing force of the spring  15  against the ratchet arm  19 . 
     As shown in FIG. 3, the control ferrule  30  may also be moved away from the knob  26  and moved onto the lower portion of the handle  20  in order to engage the channels or the ribs or the teeth  31  of the control ferrule  30  with the ribs or the teeth  24  of the handle  20 . When the control ferrule  30  is fully engaged onto the teeth  24  of the handle  20 , the control ferrule  30  is still engaged with the teeth  28  of the knob  26 , such that the handle  20  and the knob  26  are locked together with the engagement between the teeth  24 ,  28  of the handle  20  and of the knob  26  and of the control ferrule  30 . The knob  26  is thus locked to the handle  20  and may not be rotated relative to the handle  20 . The spring-biased projection  29  of the knob  26  may engage with the control ferrule  30  to secure the control ferrule  30  to the knob  26 , and to lock the control ferrule  30  relative to the knob  26  at least at the engagement position with the handle  20  (FIG. 3) and at the disengagement position with the handle  20  (FIG.  4 ). 
     Accordingly, the adjustable torque wrench includes a lock device for lock the adjustable torque wrench and for preventing the adjustable torque wrench from being further adjusted after the adjustable torque wrench has been adjusted to the required driving torque. 
     Although this invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made by way of example only and that numerous changes in the detailed construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.