Archery bow cam rotation assist device

Abstract

An archery bow is provided including a cam body rotatably joined with a limb and a cam rotation assist device engaging a portion of the cam body so as to urge rotation of the cam body independent of the limb. With the action thereon by the cam rotation assist device, the cam body rotates faster upon initial rotation during a shot cycle when the bow is shot than the cam body otherwise would rotate if the cam rotation assist device was absent. This can reduce the effect of inertia on the cam, and can improve dynamic efficiency of the bow. The rotation assist device can be in the form of a mini limb, a coil spring, programmable magnets and other components that can urge cam rotation of the cam body. The cam body can include a draw stop that engages the mini limb. Related methods are provided.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
         1 . An archery bow comprising:
 at least one limb;   a bowstring;   a bowstring cam defining a bowstring groove, the bowstring groove adapted to receive the bowstring, the bowstring cam adapted for rotation relative to the at least one limb;   a power cable;   a power cable cam joined with the bowstring cam in a fixed position, the power cable cam defining at least one of a power cable take up groove and a power cable let out groove;   an axle to which at least one of the bowstring cam and the power cable cam is joined;   a cam rotation assist device joined with the at least one limb; and   a cam projection joined with at least one of the bowstring cam and the power cable cam, the cam projection distal from the axle, the cam projection adapted to travel in a non-linear pathway as the bow is draw to a drawn mode, the cam projection adapted to engage the cam rotation assist device when the bowstring cam has rotated a preselected amount, so that the cam rotation assist device stores energy, so that the cam rotation assist device can urge the cam projection away from the limb when the bow is shot.   
     
     
         2 . The archery bow of  claim 1  wherein the cam rotation assist device is a mini limb joined with the at least one limb. 
     
     
         3 . The archery bow of  claim 2  wherein the cam projection is a draw stop, the draw stop including an elastomeric bumper. 
     
     
         4 . The archery bow of  claim 2 ,
 wherein the draw stop compresses at least a portion of the mini limb upon drawing of the bow,   wherein the mini limb moves toward the limb when engaged by the drawstop.   
     
     
         5 . The archery bow of  claim 1 ,
 wherein the cam rotation assist device includes a cantilevered portion with a fixed end joined with the limb, and a free end distal from the fixed end,   wherein the free end engages the cam projection as the cam projection moves along the pathway as the bow is drawn.   
     
     
         6 . The archery bow of  claim 5 ,
 wherein the cam projection urges the free end toward the limb as the bow is drawn,   wherein the cantilevered portion stores energy therein due to urging of the free end toward the limb.   
     
     
         7 . The archery bow of  claim 6  wherein the cantilevered portion exerts a force on the cam projection, thereby urging the bowstring cam to rotate when the archery bow is shot to return the bow to an undrawn state. 
     
     
         8 . The archery bow of  claim 1  wherein the cam rotation assist device includes a coil spring engaging at least one of the bowstring cam and the power cable cam. 
     
     
         9 . The archery bow of  claim 8  wherein the coil spring is coiled about the axle. 
     
     
         10 . The archery bow of  claim 1 ,
 wherein the cam rotation assist device includes a first programmable magnet joined with at least one of the bowstring cam and the power cable cam, and a second programmable magnet joined with the limb,   wherein the first and second programmable magnets at least one of attract and repel one another to urge rotation of the at least one of the bowstring cam and the programmable cam upon initiation of a shot cycle of the archery bow.   
     
     
         11 . An archery bow comprising:
 a limb;   a cam body rotatably joined with the limb;   a bowstring engaging the cam body;   a cam rotation assist device adapted to engage a portion of the cam body so as to urge rotation of the cam body independent of the limb;   wherein the cam body rotates faster upon initiation of a shot cycle of the archery bow due to the urging by the cam rotation assist device than the cam body otherwise would rotate upon initiation of the shot cycle if the cam rotation assist device was absent.   
     
     
         12 . The archery bow of  claim 11  wherein the cam body includes a cam projection extending laterally from the cam body and movable along a circular path. 
     
     
         13 . The archery bow of  claim 12 ,
 wherein the cam rotation assist device is placed along the circular path, so that as the cam body rotates in a first direction, the cam projection compresses the cam rotation assist device so that the cam rotation in the first direction assist device stores energy therein,   wherein the stored energy urges rotation of the cam body in an opposite direction when the bow is shot and returns to an undrawn mode.   
     
     
         14 . The archery bow of  claim 11 ,
 wherein the cam rotation assist device is a mini limb joined with the limb,   wherein the mini limb bends when the cam body rotates.   
     
     
         15 . The archery bow of  claim 11 ,
 wherein the cam rotation assist device is a coil spring joined with the cam body,   wherein the coil string at least one of coils and uncoils upon rotation of the cam body.   
     
     
         16 . The archery bow of  claim 11 ,
 wherein the cam rotation assist device includes a first programmable magnet joined with the cam body and a second programmable magnet selectively located adjacent a path of rotation of the first programmable magnet,   wherein the first and second programmable magnetic is adapted to at least one of attract and repel one another to thereby urge rotation of the cam body.   
     
     
         17 . The archery bow of  claim 11 ,
 wherein the portion of the cam body is a draw stop that projects laterally from the cam body,   wherein the draw stop includes an elastomeric bumper surrounding at least a portion thereof to prevent marring of the cam rotation assist device which the draw stop engages.   
     
     
         18 . An archery bow comprising:
 a limb;   a cam body rotatably joined with the limb;   a bowstring engaging the cam body;   a mini limb joined with the limb, the mini limb disposed in a pathway of a portion of the cam body, the mini limb adapted to flex upon engagement of the mini limb by the portion of the cam body, with the mini limb storing a force within upon flexing, the mini limb exerting the force on the portion of the cam body when the bowstring moves from a drawn state to an undrawn state during a shot cycle of the archery bow;   whereby the cam body rotates faster due to the urging by the mini limb than the cam body otherwise would rotate if the mini limb was absent.   
     
     
         19 . The archery bow of  claim 18 ,
 wherein the portion of the cam body includes a draw stop that projects laterally from the cam body,   wherein the draw stop engages the mini limb as the draw stops moves along a circular pathway about an axis of rotation of the cam body.   
     
     
         20 . The archery bow of  claim 18 ,
 wherein the mini limb includes a fixed end joined with the limb and a free end that is distal from the fixed and spaced a distance from the limb,   wherein the mini limb bends upon engagement thereof by the portion of the cam body to reduce the distance from the limb.