VARIABLE VALVE TIMING MECHANISM

PURPOSE: To highly precisely vary opening and closing time and lift quantity of a valve even at the time of high speed action by inserting a tappet in the inside of which an oil chamber is formed free to slide on a cylindrical sleeve fit in a hollow hole in an engine block and inserting an operating piston in the oil chamber free to slide. CONSTITUTION: A tappet 4 in the inside of which an oil chamber 4A is formed in inserted in a cylindrical sleeve 3 fit in a hollow hole in an engine block, and an operating piston 6 is inserted in the oil chamber 4A. Thereafter, communicating holes 19, 20 are drilled in the sleeve 3 driven in the vertical direction by actuation of a driving means 15, working oil supply and discharge passages 21, 22 are formed on the engine block 1, and a valve 2 is driven to open and close by integrally driving the operating piston 6 with the tappet 4 by way of blocking passage means 17, 18 drilled on the tappet 4 and the communicating holes 19, 20 from each other. The driving means 15 drives the sleeve 3 by specified quantity at the time of changing valve timing in accordance with information from a driving state detection means 27.