| 摘要 |
<p>PURPOSE:To keep satisfactory lubricating ability in respect to a cam and a bearing, and improve switching responsiveness by independently providing a hydraulic circuit for controlling a valve timing and hydraulic circuits for lubricating the cam and the bearing, and providing a directional changeover valve on the controlling hydraulic circuit. CONSTITUTION:When an engine operation condition is shifted to a high load area to a low load area, a three-directional solenoid valve 26 is set OFF, a hydraulic passage 22 is interrupted, and an upstream side of the hydraulic passage 22 is communicates with a drain passage 25. Lubricating oil in a pressure chamber 17 flows back through an oil passage 24, a radial passage 21, the hydraulic passage 22, and discharged from the drain passage 25 into a cylinder head 2. A cylindrical gear is moved frontward until it abut against a front end 8a by means of spring force of a compressive spring 19, for relatively rotating a timing pulley 7 and a cam shaft 1 in different directions. A closing timing of an intake valve is delayed. The lubricating oil press-fed from an oil pump 20 is always supplied to a portion between the cam shaft 1 and a bearing 3 through lubricating hydraulic circuits 28, 29.</p> |
