Cam mechnism and weight-adjustable barbell

Abstract

A cam mechanism configured to hitch a weight plate includes a bearing layer, a first wear-resistant layer arranged on one side of the bearing layer, and a second wear-resistant layer arranged on another side of the bearing layer. The second wear-resistant layer is configured to reduce wear of the weight plate in response to the weight plate being in contact with the cam mechanism. A weight-adjustable barbell includes: a barbell rod assembly including two transmission shafts, a plurality of weight plates, and a plurality of the above cam mechanisms sleeved on the two transmission shafts and configured for hitching the plurality of weight plates.

1 . A cam mechanism configured to hitch a weight plate, the cam mechanism comprising:
 a bearing layer;   a first wear-resistant layer arranged on one side of the bearing layer; and   a second wear-resistant layer arranged on another side of the bearing layer;   wherein the second wear-resistant layer is configured to reduce wear of the weight plate in response to the weight plate being in contact with the cam mechanism.   
     
     
         2 . The cam mechanism according to  claim 1 , wherein the cam mechanism further comprises:
 a connecting neck configured to hitch the weight plate, the connecting neck comprising a connecting end and a free end, the connecting end being connected to an outer surface of the second wear-resistant layer; and   a connecting protrusion arranged at the free end of the connecting neck.   
     
     
         3 . The cam mechanism according to  claim 2 , wherein the connecting neck is integrally formed at the outer surface of the second wear-resistant layer. 
     
     
         4 . The cam mechanism according to  claim 2 , wherein the connecting neck comprises an outer wall, and the outer wall is cylindrical. 
     
     
         5 . The cam mechanism according to  claim 4 , wherein an outer surface of the connecting protrusion does not go beyond a side surface of the outer wall of the connecting neck. 
     
     
         6 . The cam mechanism according to  claim 2 , wherein the cam mechanism defines an inner cavity along an axial direction of the cam mechanism, the inner cavity comprises a mounting hole and a connecting groove in communication with each other, a cross section of the connecting groove is greater than a cross section of the mounting hole to allow a step surface being formed between the connecting groove and the mounting hole;
 the inner cavity runs through middle portions of the bearing layer, the first wear-resistant layer, the second wear-resistant layer, the connecting neck, and the connecting protrusion; and   a size of the connecting protrusion is not greater than a size of the connecting groove.   
     
     
         7 . The cam mechanism according to  claim 6 , wherein a cross-section of an inner wall of the mounting hole is polygonal. 
     
     
         8 . The cam mechanism according to  claim 6 , wherein a shape of the connecting protrusion is the same as a shape of the connecting groove. 
     
     
         9 . The cam mechanism according to  claim 8 , wherein a cross-section of an outer wall of the connecting protrusion is polygonal, and a cross-section of an inner wall of the connecting groove also polygonal. 
     
     
         10 . The cam mechanism according to  claim 1 , wherein a thickness of the bearing layer is greater than a thickness of the first wear-resistant layer, and the thickness of the bearing layer is greater than a thickness of the second wear-resistant layer. 
     
     
         11 . The cam mechanism according to  claim 1 , wherein a plurality of protrusions are arranged on an outer surface of the second wear-resistance layer. 
     
     
         12 . The cam mechanism according to  claim 1 , wherein the cam mechanism defines at least one pair of hitching parts and at least one pair of avoidance parts;
 the at least one pair of hitching parts are symmetrically arranged about a center point the cam mechanism; and   the at least one pair of avoidance parts are symmetrically arranged about the center point of the cam mechanism.   
     
     
         13 . The cam mechanism according to  claim 1 , wherein the bearing layer comprises a galvanized iron plate. 
     
     
         14 . The cam mechanism according to  claim 1 , wherein the first wear-resistant layer and the second wear-resistant layer are made of plastic. 
     
     
         15 . The cam mechanism according to  claim 1 , wherein the cam mechanism further defines at least one through hole at a side of the inner cavity. 
     
     
         16 . A weight-adjustable barbell, comprising:
 a barbell rod assembly comprising two transmission shafts;   a plurality of weight plates;   a plurality of cam mechanisms sleeved on the two transmission shafts and configured for hitching the plurality of weight plates, each of the plurality of cam mechanisms comprising:
 a bearing layer, 
 a first wear-resistant layer arranged on one side of the bearing layer, 
 a second wear-resistant layer arranged on another side of the bearing layer, 
 wherein the first wear-resistant layers and the second wear-resistant layers of the plurality of cam mechanisms are configured to reduce wear of the plurality of weight plates in response to the plurality of weight plates being in contact with the plurality of cam mechanisms.