Abstract:
A variable compression tool comprising a retaining surface attached to a lever arm and a cam surface attached to a second lever arm. The two arms are moveably connected through a fixed pivot point. The profile of the jaw pocket may be of various shapes. In one instantiation, the jaw pocket conforms to at least two sides of a nut. The orientation of the cam surface to the jaw pocket is such that the force generated by closing the jaws forces the nut into the retaining surface. Adjustment of the cam lever arm is regulated by an eccentric cam adjuster bearing which changes the effective center of rotation of lever arm two in two dimensions simultaneously by rotation of the bearing.

Description:
FIELD OF THE INVENTION 
     The present invention relates to mechanical tools and, more particularly, to wrenches and other devices designed to apply pressure to an object placed between two jaws of a tool. 
     BACKGROUND OF THE INVENTION 
     Wrenches and other hand tools often can not exert enough force to grip an object securely. In the case of wrenches, rusted, frozen and undersized nuts are often difficult to remove and become further deformed by the action of the wrench jaws. Wire cutters and other hand tools that apply an increasing force on an object between jaws of a hand tool often lack sufficient mechanical advantage to function with wire of more than a small gage. 
     Pliers, socket wrenches, open end wrenches, vise grips type devices and pipe wrenches are well known. 
     Wrenches which function as an approximation of the nut head, such as open end wrenches and socket wrenches, must by necessity be slightly oversized so that they can accommodate a rusted nut and so that they can be applied and removed easily. This mismatch between the nut head and the wrench face will tend to reduce mechanical efficiency and limit the gripping force exerted upon the faces of the nut. Likewise traditional wire cutters have a limited leverage and force which can be exerted on the wire or other material to be cut when inserted between jaws of the tool. 
     Vise grip tools enable an adjustable degree of leverage to increase pressure on the object grasped. Problems with the vise grip include high pressure on the handles in order to get a tight grip, a tendency to distort or destroy the surface of the object gripped, high pressure required to release the grip, and lack of any feedback or “mechanic&#39;s feel” when using the vise grip. 
     Traditional pliers are usually made to fit a large range of sizes of nut or object to be gripped. Conventional pliers are severely limited in the amount of mechanical advantage they provide and often strip nut heads because of the mechanical force fed back into the handles when the closed pliers is turned forces the handles open and releases the grip on the nut. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided a tool comprising at least one movable arm with an integral or attached cam surface and a second opposing retaining surface to which the cam surface is moveably related such that closing the movable arm causes the cam surface to press against an object set between the cam surface and a retaining surface. The compression force is proportional to the degree of closure of the arm and the cam is angled relative to the retaining surface to apply force perpendicular to the retaining surface. 
     A feature of the preferred instantiation of the invention is to provide a compression hand tool which can be used to apply variable pressure to an object placed between a retaining surface and of an opposing cam surface. 
     It is another feature of the preferred instantiation of the invention to provide for regulation of the pressure applied by closing the arms of the tool. 
     It is another feature of the preferred instantiation of the invention to enable the turning force of the tool to be independent of the amount of compression exerted. 
     It is another feature of the preferred instantiation of the invention to align the cam surface relative to the retaining surface such that closing the lever arms results in a force vector at an angle to the center line so that the nut or other intervening object is driven into the pocket of the jaw. In the case of a nut, the resulting force tends to form the nut head into the vertex and side shapes of the jaw pocket. 
     It is another feature of the preferred instantiation of the invention to adjust for a range of sizes of intervening object by the design of the cam surface. In particular a slightly under or over sized nut can be accommodated at one setting of the levers and rounded or stripped nuts will be compressed to restore their original edges by compression of the cam surface against the pocket of the jaw. 
     It is another feature of the preferred instantiation of the invention to enable the cam arm to be adjustable so that the distance from the cam surface to the opposing surface may be increased or decreased. 
     In accordance with another feature of the preferred embodiments of the invention an adjustable cam wrench has handles, or lever arms. One lever arm has a retaining surface for a nut or bolt. The retaining surface contacts two or three faces of the nut, depending upon the size of the nut. The other lever arm has a cam surface. Both lever arms rotate about a fixed pivot. One lever arm, most preferably the lever arm with the cam surface is rotatably fixed to a bearing member and the bearing member is rigidly fixed to the fixed pivot. Most important, is that the fixed pivot is positioned off center, that is, non-concentric with respect to the bearing. Accordingly, the bearing and the fixed pivot have an offset center of rotation. A lever arm position adjuster fits over the bearing and locks to it, preferably with a transverse pin that enables the arm position adjuster to rotate in a plane parallel to the plane of the body of the wrench. Rotation of the adjuster arm varies the distance between the cam surface and the fixed pivot. 
     In accordance with another feature of the present invention one end of the arm position adjuster is fitted with one or more locking pins that fit into engagement holes formed in the lever arm having the cam surface. The arm position adjuster is pivotable about a transverse pin that locks the arm position adjuster to the bearing. 
     In accordance with another feature of the invention a wrench is provided which has a pair of lever arms that rotate about a fixed pivot. The position of one lever arm is variable relative to the fixed pivot. The lever arm whose position is variable relative to the fixed pivot is provided with a bearing member. The fixed pivot is mounted in the bearing non-concentric with the bearing whereby movement of the position adjuster from the position in which the wrench accommodates a large nut or bolt head to the position in which the wrench accommodates a small nut, increases the distance between the cam surface and the fixed pivot. The cam surface lever arm is in a rotational relationship with the bearing, and accordingly, has an eccentric relationship with fixed pivot. It should be noted that the term “cam surface” refers to a surface which bears against one face of a nut and forces the nut into engagement with a nut retaining region of the other lever arm. The cam or bearing surface of the lever arm forces the nut into the vertex formed by the intersection of the face of the nut retaining region of a lever arm essentially parallel to the cam surface and a second face of the nut retaining region. The nut retaining region has an open end and a closed end and the second face is at the closed end. Thus, a nut is always forced against two nut retaining faces, irrespective of the size of the nut. 
     In accordance with another feature of the invention a wrench is provided with a tapered relief angle of the distal ends of the lever arms such that nuts attached to a flat surface may be approached by holding the cam compression tool at an angle to the work surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A complete understanding of the present invention may be obtained by reference to the accompanying drawings, when considered in conjunction with the subsequent, detailed description, in which: 
         FIG. 1  is a front view of an adjustable cam compression wrench adjusted to the smallest opening position in accordance with the disclosure; 
         FIG. 2  is a front view of an adjustable cam wrench with arm position adjuster at a middle opening position in accordance with the disclosure; 
         FIG. 3  is a front view of an adjustable cam wrench with arm position adjuster at the fully opened position in accordance with the disclosure; 
         FIG. 4  is a front view of an assembled wrench with arm position adjuster opened to maximum position fully opened in accordance with the disclosure; 
         FIG. 5  is a front view of a non-adjustable alternate embodiment of a fixed pivot cam wrench in accordance with the disclosure; 
         FIG. 6  is a side view of the fixed pivot wrench of  FIG. 5  in accordance with the disclosure; 
         FIG. 7  is front view of the cam wrench with a side and top view of the arm position adjuster in accordance with the disclosure; 
         FIG. 8  is a front view of an adjustable cam wrench having an alternative orientation of the retaining surface and cam surface and showing details of the arm position adjuster in accordance with the disclosure; 
         FIG. 9  is a front view of an adjustable cam compression tool with the arm position adjuster removed in a fully open position, showing the preferred orientation of the cam surface to the nut and the retaining surface in accordance with the disclosure; 
         FIG. 10  is a rear exploded view of an adjustable cam wrench in accordance with the disclosure; 
         FIG. 11  is a perspective view of the lever arm pivot and relief angle of the head in accordance with the disclosure; 
         FIG. 12  is a perspective view of an adjuster bearing of an adjustable cam wrench in accordance with the disclosure; 
         FIG. 13  is a front view of a lever arm showing engagement holes and cam surface in accordance with the disclosure; 
         FIG. 14  is a perspective front view of a lever arm of an adjustable cam wrench with fixed pivot in accordance with the disclosure; 
         FIG. 15  is a left plan view of an arm position adjuster with pins and spring in accordance with the disclosure; 
         FIG. 16  is a perspective view of a arm position adjuster of an adjustable cam wrench showing pins, transverse hole and spring in accordance with the disclosure; 
         FIG. 17  is a perspective view of an adjustable cam wrench partially disassembled in accordance with the disclosure; 
         FIG. 18  is an exploded left perspective view of a cam wrench showing arm position adjuster and lever arms in accordance with the disclosure; and, 
         FIG. 19  is an alternate embodiment of the wrench having the retaining surface of the fixed jaw at a 90 degree angle to the centerline of the tool. The cam lever arm is shown in its maximum and minimum travel positions corresponding to the largest and smallest size nut which the embodiment will accept. 
     
    
    
     For purposes of clarity and brevity, like elements and components will bear the same designations and numbering throughout the Figures. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It should be noted that the discussion of the theory of operation as presently understood is by way of providing a better understanding and does not limit the scope of the invention. 
       FIG. 1  is a front view of an adjustable cam wrench with handles, or lever arms,  12  and  14  at their minimum distance from each other. The Figure shows the first lever arm  12  and second lever arm  14  that are configured as well known in the art for user comfort. The retaining surface  32  of the fixed jaw and cam surface  42  extend from lever arm  12  and lever arm  14  respectively and are connected at a fixed pivot  20  with an associated adjuster bearing  30 . The bearing  30  and fixed pivot  20  have an offset center of rotation. The arm position adjuster  26  fits over the bearing  30  and locks to it with a transverse pin (not shown) that enables the arm position adjuster  26  to rotate horizontally relative to the body of the wrench. That is, it rotates in a plane essentially parallel to the plane of the body of the wrench. One end of the arm position adjuster  26  is fitted with one or more locking pins  38  ( FIG. 15 ) that fit into engagement holes  36  formed in lever arm  12 . 
     Arrow  18  represents the contact region between the cam surface  42  and the nut. The cam surface contact region is on the region of the face of the nut away from the closed region  32 A of the retaining surface  32  of the fixed jaw  21 A of the lever arm  12 . It should be noted that the term “fixed” is used to indicate that it rotates about a fixed pivot  20 , whereas the cam surface  42  path of movement is dependent upon the position of the position adjuster  26 , and thus is not fixed. 
     While both arms rotate about the fixed pivot  20  the position of lever arm  14  and its cam surface  42  are is variable relative to the fixed pivot  20 . Since the pivot  20  is not concentric with the bearing  30  movement of the position adjuster from the position in which the wrench accommodates a large nut or bolt head to the position in which it accommodates a small nut, increases the distance between the cam surface and the fixed pivot  20 . The terms nut and bolt are used herein interchangeably, and most typical are hexagonal. The term “hex head” is commonly employed to indicate such elements. As evident from  FIG. 10 , the bearing  30  is received in hole  30 A. Accordingly, lever arm is in a rotational relationship with bearing  30 , and accordingly, a eccentric relationship with fixed pivot  20 , since pivot  20  is not concentrically positioned with respect to bearing  30 . 
     The arm position adjuster  26  is utilized by pressing down on the end opposite the locking pins  38  and rotating the arm position adjuster  26  to a point such that the locking pins  38  engage with one or more engagement holes  36 . Rotation of the arm position adjuster  26  serves to reposition lever arm  14  relative to the fixed pivot  20 . In the preferred instantiation the rotation of the bearing adjuster  26  results in the cam surface  42  moving relative to the retaining surface  32  such that the point of contact of the cam surface  42  is maintained in the same relative position for a variety of sizes of hexagonal nuts. The point of contact and the orientation of the retaining surface  32  to the nut is such that closing the handles of the wrench drives the nut into the retaining surface  32 . In order to provide a better grip, the cam surface  42  has a slight convexity on the order of about five (5) degrees, as indicated in  FIG. 8 . An opening spring  34  is preferably fitted to aid in “ratcheting” the wrench so that it tends to open when the handles are released to enable a partial rotation of the wrench relative to the nut head without removing the tool from the nut. 
     It should be noted that any other method known in the art can be used to adjust the position of the cam surface and that the arm position adjuster illustrated herein is for example. The critical feature is the ability to adjust and retain the cam surface, through adjustment of the bearing, in one or more positions relative to the retaining surface. 
     The caming action, in addition to the slight convexity, serves to enable a user to apply a greater amount of pressure than can be attained using a flat contact surface. 
       FIG. 2  is a front view of the wrench of  FIG. 1  but with the arm position adjuster  26  selecting a medium setting. 
       FIG. 3  is a front view of the wrench of  FIG. 1  with the arm position adjuster  26  selecting the largest setting, enabling the maximum distance between the cam surface  42  and the retaining surface  32 . In  FIG. 4  the lever arms  12  and  14  have been opened to their maximum separation enabled by the arm position adjuster  26  setting of  FIG. 3 . 
       FIG. 5  is a non-adjustable variant of the cam compression tool. The cam surface  142  has, in the preferred embodiment, the convexity of about less than five (5) degrees. The lever arms  112  and  114  are, as with other embodiments disclosed herein, configured for user comfort and can be covered with a not-slip material if so desired. In this embodiment the spring  134  forces the lever arms to separate when in a “resting” position. The lever arms  112  and  114  rotate around the fixed pivot  120 . 
       FIG. 6  is a side view of the wrench of  FIG. 5  showing a relief angle  128  of the head enabling the wrench to be held at an angle to the work surface. 
       FIG. 7  illustrates the adjustable wrench showing the change in cam surface  42  position through rotation of the arm position adjuster  26 . 
       FIG. 8  is a front view of an alternate adjustable wrench having an alternative orientation of the retaining surface  232  and cam surface  242 . In this version the point of contact of the cam surface  242  and drive the nut into the retaining surface  232  from the vertex of the nut rather than the flat surface. 
       FIG. 9  is a top view of a partially disassembled cam compression wrench with the arm position adjuster  26  removed to display the engagement holes  36  more fully. The placement of the pivot  20  and bearing  30  in relationship to the engagement holes  36  and also be seen in greater detail. 
       FIG. 10  illustrates the wrench of  FIG. 1  disassembled showing all the elements, including optional spacing washers  50   
       FIG. 11  is a perspective view of lever arm  12  showing the pivot  20  and a relief angle  28  on the head. 
       FIG. 12  is a perspective view of the adjuster bearing  30  showing the transverse pin  40  used to maintain the bearing  30  on the pivot  20 . 
       FIG. 13  is the lever arm  14  of the cam wrench shown in  FIG. 1  showing the cam surface  42  and retaining holes  36 . 
       FIG. 14  is the lever arm  12  of the cam wrench shown in  FIG. 1  showing the pivot  20  and retaining surface  32 . 
       FIG. 15  is a side view of the arm position adjuster  26  showing the retaining pins  38  and receiving holes  41  for the transverse pin  40 . The return spring  44  keeps the arm position adjuster  26  parallel to the surface of the wrench. 
       FIG. 16  is a perspective view of the arm position adjuster  26  showing the receiving holes  41  for the transverse pin  40  and the locking pins  38 . 
       FIG. 17  is a perspective view of a partially disassembled led cam wrench of  FIG. 1  showing the placement of the transverse pin  40  which serves as a pivot bearing for the adjuster  26  and for locking the adjuster to the bearing  30 . 
       FIG. 18  is a side view of the cam wrench of  FIG. 1  showing the pivot  20  with a groove  22  to accept the transverse pin  40 . Also shown, is the bearing  30 , mounted in the lever arm  14 . 
       FIG. 19  is a front view of an alternative cam compression tool with the retaining surface of lever arm  314  oriented with the flat retaining surface  332  at a 90 degree angle to the center line  350  of the tool and the lever arm  312  oriented to maintain the cam surface  342  moving through a parallel orientation to said flat retaining surface  332 . 
     In the figure the lever arm  314  and cam surface  342  are positioned for the largest size nut  370  at the maximum travel position and at the positioning  314 A corresponding to the smallest nut  372 . It should be noted that the separation distance illustrated herein is for example is does not necessarily reflect any proportions or ratios. 
     It is thus seen that the arm position adjuster mechanism produces a tool that is the equivalent of a tool having a plurality of wrench arms each having a different orientation relative to the fixed pivot. 
     Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention. 
     Broad Scope of the Invention 
     While illustrative embodiments of the invention have been described herein, the present invention is not limited to the various preferred embodiments described herein, but includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations and/or alterations as would be appreciated by those in the art based on the present disclosure. The limitations in the claims (e.g., including that to be later added) are to be interpreted broadly based on the language employed in the claims and not limited to examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive. For example, in the present disclosure, the term “preferably” is non-exclusive and means “preferably, but not limited to.” In this disclosure and during the prosecution of this application, means-plus-function or step-plus-function limitations will only be employed where for a specific claim limitation all of the following conditions are present in that limitation: a) “means for” or “step for” is expressly recited; b) a corresponding function is expressly recited; and c) structure, material or acts that support that structure are not recited. In this disclosure and during the prosecution of this application, the terminology “present invention” or “invention” may be used as a reference to one or more aspect within the present disclosure. The language of the present invention or inventions should not be improperly interpreted as an identification of criticality, should not be improperly interpreted as applying across all aspects or embodiments (i.e., it should be understood that the present invention has a number of aspects and embodiments), and should not be improperly interpreted as limiting the scope of the application or claims. In this disclosure and during the prosecution of this application, the terminology “embodiment” can be used to describe any aspect, feature, process or step, any combination thereof, and/or any portion thereof, etc. In some examples, various embodiments may include overlapping features. In this disclosure, the following abbreviated terminology may be employed: “e.g.” which means “for example.”