Rotary valve structure for four-stroke engine

A rotary valve structure for four-stroke engine, said engine including a cylinder in which a piston is brought by a crankshaft to move in reciprocating motion, and said cylinder being provided at one end with separated gas-in and gas-out passages that communicate with a combustion chamber in said cylinder, comprising an intake rotary rod and an exhaust rotary rod rotatably located at a gas inlet of said gas-in passage and a gas outlet of said gas-out passage, respectively;

• said intake and said exhaust rotary rods being connected to a transmission mechanism that is connected to and driven to rotate by said crankshaft, such that an intake hole and an exhaust hole provided on said intake rotary rod and said exhaust rotary rod, respectively, to radially extend therethrough are oriented either to communicate said gas-in and said gas-out passages with said combustion chamber or to close said gas-in and said gas-out passages at said gas inlet and said gas outlet.