Valve opening and closing timing control apparatus

Abstract

A valve opening and closing timing control apparatus is disclosed, which includes an engine including a cam shaft and a crank shaft, a first sensor adapted for detecting rotary positions of the cam shaft, a second sensor adapted for detecting rotary positions of the crank shaft, a hydraulic pump driven by the crank shaft, a rotary phase varying means disposed on the cam shaft and adapted for varying rotary phases of the cam shaft, a hydraulic line connecting the hydraulic pump and the rotary phase varying means, an accumulator and a hydraulic control means, each disposed in the hydraulic line, an electronic control means adapted for controlling the hydraulic means and receiving output signals which are output by the first sensor and the second sensor at least, thereby operating the rotary phase varying means with the hydraulic control means under linear control. The valve opening and closing timing control apparatus can establish the valve opening and closing timing at optimum and desired occasions, which distinguishes over the conventional digitized valve opening and closing timing. Moreover, it is unnecessary to enlarge the hydraulic pump capacity because the accumulator supplies extra hydraulic pressures when the valve opening and closing timing should be varied considerably.