Camshaft drive for engine

Abstract

A camshaft drive for an engine, comprises a driving chain wrapped around a crankshaft sprocket and a larger camshaft sprocket, and a driven chain wrapped around a smaller sprocket coaxial with, and fixed to, the larger camshaft sprocket and a third camshaft sprocket spaced laterally from said smaller camshaft sprocket. The chain strength of the driven chain is made less than the chain strength of the driving chain. The chains sustain the required loads in the operation of the engine, but permit size reduction and cost reduction to be realized.

1 . A camshaft drive for an engine comprising: 
 a crankshaft sprocket;    large and small camshaft sprockets in coaxial relationship with each other, and fixedly connected to each other for rotation together about a first axis;    a third camshaft sprocket, spaced laterally from said large and small camshaft sprockets, and rotatable about a second axis parallel to said first axis;    a driving chain wrapped around the crankshaft sprocket and said large camshaft sprocket, for transmitting rotational power from the crankshaft sprocket to said large camshaft sprocket; and    a driven chain wrapped around said small camshaft sprocket and said third camshaft sprocket, for transmitting rotational power from said small camshaft sprocket to said third camshaft sprocket;    wherein the strength of said driven chain is less than the strength of said driving chain.    
     
     
         2 . A camshaft drive according to  claim 1 , in which the pitch of said driven chain is smaller than the pitch of said driving chain.