Abstract:
A torque wrench having a handle and an output shaft is disclosed. The output shaft may be constrained to turn only unidirectionally due to a ratchet. Rotation of the output shaft may be permanently disabled by an internal mechanism. Torque imposed on the output shaft may be limited by a torque responsive cam clutch. The handle forms or is part of an enclosure enclosing internal components such as the ratchet, the internal disablement mechanism, and the torque responsive cam clutch. A seal between the body and the output shaft prevents ingress and egress of lubricants and contamination between the inside of the body and the output shaft.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the filing date under 35 USC §119(e) of U.S. Provisional Application Ser. No. 62/063,898, filed Oct. 14, 2014, the contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates to hand tools, and more particularly, to a torque wrench which has unidirectional functionality, and also can be rendered unserviceable automatically after a predetermined number of usages. 
       BACKGROUND 
       [0003]    Tools for certain operations require a fairly high degree of precision. Illustratively, some operations require precise torque values to be applied to fasteners. One of the most effective ways to accomplish this goal is to provide a self-limiting torque wrench having a mechanism for limiting maximum applied torque. With such a mechanism, a user can freely turn the wrench without having to pay attention to the amount of torque being developed. Free turning of the wrench may entail alternating direction of wrench rotation, since that can be performed conveniently with one hand, without requiring that the hand be removed from the tool. 
         [0004]    In some usages and environments, such a torque wrench can develop serious deficiencies. For example, in the field of high precision assembly, a torque wrench may go out of calibration to a degree unacceptable to assembly or fabrication standards. In another example, a torque wrench used in medical procedures such as installation of inserts in the human body may become internally contaminated, or may start to leak lubricant. 
         [0005]    There exists a need for a torque wrench which overcomes the problems facing manually used wrenches. 
       SUMMARY 
       [0006]    The disclosed concepts address the above stated situation by providing a manual torque wrench having a self-limiting torque feature and a feature which disables the wrench after a predetermined number of operations have been performed. The self-limiting torque feature may be based on an adjustable ratchet clutch mechanism in series with the torque delivery path. The disablement feature is based on internal components which cause a threaded end of a torque delivering shaft to progressively disengage from threading in the handle of the wrench over a predetermined number of usages of the torque wrench. Upon the torque delivering shaft becoming disengaged from the threading in the handle, an internal component of the wrench is moved to a position permanently disabling transmission of torque from the handle to an output shaft of the torque wrench. 
         [0007]    It is an object to provide improved elements and arrangements thereof by apparatus for the purposes described which is inexpensive, dependable, and fully effective in accomplishing its intended purposes. 
         [0008]    These and other objects will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Various objects, features, and attendant advantages of the disclosed concepts will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
           [0010]      FIG. 1  is an exploded perspective view of a torque wrench, according to at least one aspect of the disclosure; 
           [0011]      FIG. 2  is an exploded perspective detail view, showing only some of the components of  FIG. 1 , and is drawn to greater scale than  FIG. 1 ; 
           [0012]      FIG. 3  is a side cross sectional view of some components shown at the lower end of  FIG. 1 , reflecting the assembled condition of the subject torque wrench, and drawn to enlarged scale; 
           [0013]      FIG. 4  is a perspective detail view of some components shown towards the center of  FIG. 1 , reflecting the assembled condition, and drawn to enlarged scale; 
           [0014]      FIG. 5  is a perspective detail view similar to  FIG. 4 , but shown partially broken away to reveal internal detail, reflecting an engaged position of the subject components; 
           [0015]      FIG. 6  is a perspective detail view similar to  FIG. 5 , but showing some components moved to a disengaged position; and  FIG. 7  is a bottom plan detail view taken along line  7 - 7  of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Referring first to  FIG. 1 , according to at least one aspect of the disclosure, there is shown a torque wrench  100  having a feature for permanently discontinuing ability to transmit torque. Torque wrench  100  comprises a handle  102  and an output shaft  104  coupled to, and driven by rotation of, handle  102 . Output shaft  104  has an axis of rotation  106  about which output shaft  104  rotates when handle  102  rotates. 
         [0017]    Torque wrench  100  may include a torque control (to be described hereinafter) responsive to torques imposed on output shaft  104  from handle  102 , and may include a disengagement feature which becomes operable to permanently disconnect handle  102  from output shaft  104 . Permanent disconnection of handle  102  from output shaft  104  enables torque wrench  100  to be utilized throughout a period of predictable accuracy and freedom from unreliability and other issues. When disengagement occurs, would be users of torque wrench  100  are obliged to select a relatively new torque wrench  100 , and are thereby not susceptible to inaccurate torque settings and other problems resulting from an overused tool. 
         [0018]      FIG. 1  shows components of one contemplated implementation of torque wrench  100 , including components having little if any bearing on presently claimed features of torque wrench  100 . These components are shown to further appreciation of the compact nature achieved in torque wrench  100 , but are not identified by reference numeral or description. Further details regarding operation of torque wrench  100  and its components may be gleaned from U.S. Pat. No. 7,487,700, issued to Cutler et al. on Feb. 10, 2009, which patent is incorporated herein by reference. 
         [0019]    Handle  102  comprises a handle cap  108  which complements a handle body  110 . When mated together, handle cap  108  and handle body  110  of handle  102  form an enclosure which encloses all of the internal components of torque wrench  100 , except for output shaft  104 . Referring to  FIGS. 1 and 3 , in an example of torque wrench  100 , handle  102  forms an enclosure from which output shaft  104  projects. Torque wrench  100  further comprises a seal  112  between output shaft  104  and handle  102 . Seal  112  comprises a first resilient layer  114  and a second resilient layer  116  each spaced apart from one another along axis of rotation  106 . First and second resilient layers  114 ,  116  are supported and may be permanently secured to an intervening structural member or holder  118 . 
         [0020]    Unless otherwise indicated, the terms “first”, “second”, etc., are used herein merely as labels, and are not intended to impose ordinal, positional, or hierarchical requirements on the times to which these terms refer. Moreover, reference to, e.g., a “second” item does not either require or preclude the existence of, e.g., a “first” or lower-numbered item, and/or, e.g., a “third” or higher-numbered item. 
         [0021]    In an example of torque wrench  100 , the torque control comprises a torque responsive clutch  120  which automatically disengages output shaft  104  from handle  102  upon attainment of a predetermined torque. Torque responsive clutch  120  is contained entirely within handle  102 . 
         [0022]    Referring to  FIGS. 1 and 2 , torque responsive clutch  120  comprises opposed cams  122 ,  124 , wherein opposed cams  122 ,  124  interfit with one another in a torque transmitting mode when transmitting torque. Opposed cams  122 ,  124  separate from one another in a released mode when not transmitting torque. A spring  126  urges opposed cams  122 ,  124  towards one another. As used herein, cams  122  and  124  will be understood to refer to a cam assembly including both the actual cam surfaces, and also additional structural members formed monolithically with the cam surfaces. Each cam  122 ,  124  has inclined ramps of known type of pitches enabling one cam  122  or  124  to rotate the other cam  124  or  122  until a predetermined threshold of torque is attained. This threshold is determined in part by spring  126 . When torque increases above the threshold, cams  122  and  124  slide over the ramps of the other cam  124  or  122 , thereby spacing cams  122 ,  124  apart axially (with respect to axis of rotation  106 ) until they are no longer able to rotate in tandem. When this happens, cam  122 , which receives rotational input by rotating handle  102 , rotates ineffectually, while cam  124  remains immobile. 
         [0023]    This is a known torque limiting arrangement which is not novel per se. Providing this torque limiting arrangement enables the user to concentrate on rotating torque wrench  100 , without the distraction of monitoring applied torques. 
         [0024]    Although the torque limiting arrangement has been presented in terms of a device which decouples output shaft  104 , the torque limiting arrangement could be instead a readout or other signaling arrangement which annunciates attainment of a predetermined torque value. Examples include a needle deflected by imposition of torque, taken together with a scale, or alternatively, an alphanumerical display. 
         [0025]    In an example of torque wrench  100 , the disengagement feature comprises a rotational coupling  128  between handle  102  and output shaft  104 . Rotational coupling  128  is contained entirely within handle  102 . This is one of several structural features of torque wrench  100  providing highly compact configuration. 
         [0026]    In the example of  FIGS. 1 and 2 , rotational coupling  128  comprises a unidirectional ratchet  130  performing or contributing to two distinct functions. In one function, unidirectional ratchet  130  selectively enables output shaft  104  to rotate relative to handle  102  in a first direction when handle  102  is turned in the first direction about axis of rotation  106 , and constrains output shaft  104  against rotating relative to handle  102  when handle  102  is turned in a second direction about axis of rotation  106  opposite the first direction. Therefore, torque wrench  100  can be operated using one hand, by alternating directions of rotation of handle  102 , without obliging the user to remove his or her hand from handle  102 . 
         [0027]    As seen in  FIGS. 2 and 4-6 , in an implementation of torque wrench  100 , unidirectional ratchet  130  is supported on and at least partially contained within rotational coupling  128 . More specifically, and best seen in  FIGS. 5 and 6 , unidirectional ratchet  130  is received within a partially enclosed space  132  formed by a skirt  134  extending from cam  124 . This results in a highly compact arrangement accommodating components providing several functions of torque wrench  100  within handle  102 . 
         [0028]    Looking particularly at  FIGS. 5 and 6 , unidirectional ratchet  130  has teeth  136  projecting radially outwardly relative to axis of rotation  106 . Teeth  136  of unidirectional ratchet  130  engage corresponding grooves  138  (see  FIG. 7 ) in rotational coupling  128 . The disengagement feature displaces teeth  136  of unidirectional ratchet  130  axially out of engagement with corresponding grooves  138  of rotational coupling  128 , thereby enabling output shaft  104  to rotate freely relative to handle  102 . 
         [0029]      FIGS. 2 and 7  clarify the nature of unidirectional ratchet  130 . Pawls or teeth  136  are mounted on two swing arms  140  pivotally mounted to a ratchet support member  142 . Pins  141  (one representative pin  141  is shown in  FIG. 1 ) pivotally support swing arms  140 . Swing arms  140  are urged against the inner wall of skirt  134  by swing arm springs  143 , which inner wall bears grooves  138 . Teeth  136  and corresponding grooves  138  are configured such that when ratchet support member  142  is rotated in one direction about axis of rotation  106 , the ratchet mechanism engages skirt  134  of cam  124 , and torque is transmitted. When ratchet support member is rotated in an opposite direction, teeth  136  readily disengage from grooves  138 , and no torque is transmitted. Configuration of teeth  136  and grooves  138  implies that pitch angles, rounding of contours, and the like of teeth  136  and grooves  138  favor slippage in one direction, but tend to oppose mutual slippage in the opposite direction. 
         [0030]    Thus far, one of the two functions involving unidirectional ratchet  130  has been described, notably, effecting unidirectional rotation of output shaft  104  responsive to torque inputs imposed on handle  102 . The second function is that of permanently disabling transmission of torque from handle  102  to output shaft  104 . This latter function will now be described. Generally, permanent disablement can be accomplished by displacing ratchet support member  142  and its associated swing arms  140  and teeth  136  along axis of rotation  106 , such that teeth  136  no longer align with associated grooves  138 . 
         [0031]    Turning now to  FIG. 2 , torque wrench  100  further comprises a push rod  144  operable to advance along rotational axis  106  within handle  102 . Push rod  144  then contacts unidirectional ratchet  130 , and displaces unidirectional ratchet  130  axially out of engagement with rotational coupling  128 . Push rod  144  may be regarded as an upper section of output shaft  104 , and plays a role in receiving torque and transmitting torque to output shaft  104  via rotational coupling  128  and unidirectional ratchet  130 . 
         [0032]    It should be noted at this point that orientational terms such as upper refer to the subject drawing as viewed by an observer. The drawing figures depict their subject matter in orientations of normal use, which could obviously change depending on how novel torque wrench  100  is held. Therefore, orientational terms must be understood to provide semantic basis for purposes of description only, and do not imply that their subject matter can be used only in one position. 
         [0033]    In the example of  FIGS. 1, 2, and 4-6 , push rod  144  has threading  146 . Handle  102  comprises a threaded inhibiting member  148  matingly compatible with threading  146  of push rod  144 . Push rod  144  is initially threaded to threaded inhibiting member  148  of handle  102 , and progressively unthreads from threaded inhibiting member  148  with each usage of torque wrench  100 . Torque wrench  100  comprises a second spring  150  urging push rod  144  towards unidirectional ratchet  130 . When push rod  144  is fully unthreaded from threaded inhibiting member  148 , second spring  150  urges push rod  144  against unidirectional ratchet  130  such that unidirectional ratchet  130  is disengaged from rotational coupling  128  by displacing teeth  136  of unidirectional ratchet  130  axially out of engagement with grooves  138  of rotational coupling  128 .  FIG. 5  shows unidirectional ratchet  130  in the normal or engaged position. In  FIG. 6 , unidirectional ratchet  130  has been displaced downwardly, leaving visible an upper space  152  in the enclosed space  132  of cam  124 . A third spring  154  holds unidirectional ratchet  130  in the normal position until acted on by push rod  144 . Third spring  154  seats against a clip  156  secured to output shaft  104 . Second spring  150  seats at one end against threaded inhibiting member  148  and at an opposed end at a clip  158  secured to push rod  144 . Spring  150  has greater force than spring  154 , so that unidirectional ratchet  130  will not spontaneously reassume the normal position shown in  FIG. 5 . 
         [0034]    Threaded inhibiting member  148  is presented as a part of handle  102 . In the implementations of torque wrench  100  presented herein, threaded inhibiting member  148  is depicted as a nut held within a hexagonally configured passage  162  of a projection  161  of a cap  160  which cap  160  is, in the assembled torque wrench  100 , fixed to handle  102 . 
         [0035]    In the above description, numerous specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known components or methods have not been described in detail but rather in a block diagram in order to avoid unnecessarily obscuring the present invention. Thus, the specific details set forth are merely exemplary. The specific details may be varied from and still be contemplated to be within the spirit and scope of the present invention. 
         [0036]    While the disclosed concepts have been described in connection with what is considered the most practical and preferred implementation, it is to be understood that the disclosed concepts are not to be limited to the disclosed arrangements, but are intended to cover various arrangements which are included within the spirit and scope of the broadest possible interpretation of the appended claims so as to encompass all modifications and equivalent arrangements which are possible. 
         [0037]    It should be understood that the various examples of the apparatus(es) disclosed herein may include any of the components, features, and functionalities of any of the other examples of the apparatus(es) disclosed herein in any feasible combination, and all of such possibilities are intended to be within the spirit and scope of the present disclosure. Many modifications of examples set forth herein will come to mind to one skilled in the art to which the present disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. 
         [0038]    Therefore, it is to be understood that the present disclosure is not to be limited to the specific examples presented and that modifications and other examples are intended to be included within the scope of the appended claims. Moreover, although the foregoing description and the associated drawings describe examples of the present disclosure in the context of certain illustrative combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative implementations without departing from the scope of the appended claims.