VARIABLE VALVE TIMING APPARATUS

摘要

The present invention relates to a variable valve timing apparatus which is capable of adjusting a time of closing an intake and exhaust valves of an engine, comprising: an actuator housing including a top chamber, a bottom chamber and a connection chamber; a first communication path for communicating side surfaces of the top chamber and the bottom chamber; a second communication path including an opening and closing valve for communicating the first communication path and the bottom chamber; a pushrod lifting unit for opening or closing the first communication path according an ascending or descending operation of the top chamber, and interrupting a movement of oil to the bottom chamber as well; a return spring installed in the bottom chamber; and a piston for opening or closing a lower end of the second communication path according to the ascending or descending operation. Therefore, an oil circulation path can be selectively changed, so the time of closing the intake and exhaust valve can be adjusted.