CAM FOR LIFTING/LOWERING EXHAUST VALVE, FOUR-CYCLE ENGINE EQUIPPED WITH SUPERCHARGER, AND METHOD FOR CONTROLLING VALVE TIMING

摘要

PROBLEM TO BE SOLVED: To provide a cam for lifting/lowering an exhaust valve and the like recirculating the larger amount of exhaust gas from the other cylinder to one cylinder without depending on electronic control without bringing a piston into contact with the exhaust valve.

SOLUTION: In this method for controlling the valve timing of the exhaust valve, exhaust gas exhausted from the exhaust port of the other cylinder is recirculated into the one cylinder through the exhaust port of the one cylinder. An exhaust valve pressing cam 4 for the one cylinder is so formed that an exhaust main lift part 4a for exhausting the exhaust gas from the inside of the cylinder and a recirculation lift part 4b formed on a down side in the rotating direction of the exhaust valve pressing cam 4 in order to increase the amount of exhaust gas recirculated led to flow from the other cylinder into the exhaust port of the one cylinder and delaying a valve lift closing timing or maintaining high lift are raised from a base circle R so that the amount of overlap with the exhaust valve of the other cylinder is increased while avoiding contact of the exhaust valve with the piston.

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