Patent ID: 6953407

Claim:
A belt transmission apparatus, comprising: a rotating electric machine pulley of a rotating electric machine for transmitting starting power to an engine; an engine pulley for transmitting the starting power to said engine and also transmitting a rotation power of said engine to an accessory; an auxiliary pulley being driven to rotate by the power from said engine pulley thereby to drive said accessory; a belt wrapped around said rotating electric machine pulley, said engine pulley and said auxiliary pulley in succession; and a belt tension adjuster for urging said belt so as to set a tension of said belt in a plurality of stages, wherein said tension adjuster acts to adjust the tension of the belt such that the belt tension is set to be greater when said engine is started by said rotating electric machine than when said accessory is driven to operate after said engine has been started, wherein said tension adjuster comprises: a pulley unit around which said belt is wrapped whereby to rotate in accordance with movement of said belt; and an automatic belt tensioner for urging said pulley unit to push said belt through said pulley unit, and wherein said automatic belt tensioner comprises: a first housing with first and second axial end walls; an elastically deformable spring; a push rod extending through the first axial end wall, for urging said pulley unit with a reactive force generated upon elastic deformation of said spring, comprising a planar disk portion having an outer diameter equivalent to an inner diameter of the housing; and an elastic deformation unit, for elastically deforming said spring, comprising a planar disk portion having outer diameter equivalent to an inner diameter of the housing; wherein the elastically deformable spring is arranged between said disk portion of said piston and said disk portion of said push rod.