| 摘要 |
1522405 IC engine valve gear S W MITCHELL 2 April 1976 13370/76 Heading F1B The valve timing of an I.C. engine is governed by crank-shaft driven plates 12, 19 mounted on a pivoted arm 15 to drive inlet and exhaust camshafts 7, 17 via an eccentric linkage comprising slots 27, 31 in the plates which receive followers 26, 30 supported eccentrically by cam-shafts 7, 17, the centres of plates 12, 19 being movable relative to the cam-shafts to vary the valve timing in accordance with engine operating conditions e.g. engine load or speed. Under certain conditions (preferably high speed), the centres of plates 12, 19 coincide with the axes of cam-shafts 7, 17; as the operating conditions alter (e.g. the speed falls), an actuator 20 pivots arm 15 about the shaft 16 of a gear forming part of the drive from the crankshaft 11 and causes displacement of the plates relative to the cam-shafts to delay valve opening and advance valve closing. The actuator 20 comprises a piston which is subject to balancing oil pressures giving rise to an equilibrium position which may be varied by a control piston coupled to a device for sensing engine speed and inlet manifold vacuum indicative of engine load. |
