Rotary valve structure for four-stroke engine

Abstract

A rotary valve structure is provided for a four-stroke engine having a cylinder in which a piston is brought by a crankshaft to move in reciprocating motion and a combustion chamber is provided to communicate with separated gas-in and gas-out passages. The rotary valve structure includes an intake and an exhaust rotary rod rotatably located at a gas inlet of the gas-in passage and a gas outlet of the gas-out passage, respectively. The intake and the exhaust rotary rods are rotated by a transmission mechanism driven by the crankshaft, such that an intake and an exhaust hole radially extended through the intake and the exhaust rotary rod, respectively, are turned either to communicate the gas-in and the gas-out passages with the combustion chamber or to close the gas-in and said gas-out passages at the gas inlet and the gas outlet.

What is claimed is:  
     
         1 . 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.  
     
     
         2 . The rotary valve structure for four-stroke engine as claimed in  claim 1 , wherein said intake rotary rod has a diameter larger than that of said exhaust rotary rod, and said radially extended intake hole of said intake rotary rod is larger than said radially extended exhaust hole of said exhaust rotary rod.  
     
     
         3 . The rotary valve structure for four-stroke engine as claimed in  claim 1 , wherein said transmission mechanism includes an extending shaft provided along an end of said crankshaft, a driving belt, and a belt pulley; said driving belt being supported at an end on said extending shaft and at another end on said belt pulley, so that said belt pulley rotates along with said crankshaft synchronously; and said intake rotary rod and said exhaust rotary rod being connected to one side of said belt pulley and brought to rotate by said belt pulley.  
     
     
         4 . The rotary valve structure for four-stroke engine as claimed in  claim 3 , wherein said belt pulley includes a driving screw fixedly mounted at a center of said side of said belt pulley having said intake and said exhaust rotary rods connected thereto, and said intake and said exhaust rotary rods being located at two sides of said driving screw, and being externally provided at predetermined positions with threads for meshing with said driving screw.  
     
     
         5 . The rotary valve structure for four-stroke engine as claimed in  claim 1 , wherein said intake rotary rod defines an inner bore for movably receiving a movable stick therein to control an intake flow at said intake hole.