| 摘要 |
1,201,558. 558. Regulating I.C. engines; valve gear. GENERAL MOTORS CORP. May 16, 1968 [June 7, 1967], No.23312/68. Heading F1B. In a spark ignition I.C. engine an hydraulic lash adjuster 56 forms the pivot for a rocker lever 45, which forms part of the valve train of an inlet valve 26, and is selectively angularly displaceable to adjust the extent of opening movement of the valve. The lash adjuster 56 operates during engine operation to displace the locus of pivotal movement of the lever 45 irrespective of angular lash adjuster displacement, to take up clearance in the valve train. An hydraulic tappet 36 may be provided between the valve actuating cam on the cam-shaft 35 and the push rod 37. The V-8 engine shown in Fig.1 has the lash adjusters 56 for the two banks of cylinders 18 mounted in cylinders 55a in members 55 fired to rotatable shafts 53. The shafts 53 are connected by levers 54 to a common control shaft 54a which may be controlled automatically in accordance with the desired power output of the engine. The surfaces 58 of the lash adjusters 56 engage the concave surfaces 47 of the levers 45 and the centres of curvature 49 of the surfaces 47 coincide with the axes 52 of the shafts 53 when the inlet valves 26 are closed. The adjusters 56 are located between raised portions 47a of the levers 45 to reduce lever wobble. Lateral movement of the push rods 37 is prevented by metal plates 39 with slots 40 engaging the sides of the rods. A ball and socket conformation may be provided between the stem 26a of an inlet valve 26 and the end 48 of its rocker lever 45. Threaded sleeves 41 surrounding the rods 37 limit movement of the levers 45 under the bias of springs 61. The valve gear covers 32 may have transparent top portions 34. Fuel is delivered to nozzles 78 adjacent the inlet valves 26 by a fuel metering apparatus 71 controlled by a pressure signal from an orifice 69 at the throat of an air inlet Venturi 68. The inlet valve opening at idling may be 1/50 of the maximum opening and the ignition timing may be controlled solely as a function of engine speed. The variation in inlet valve opening allows lean fuel-air mixtures to be used as a result of the turbulence produced by throttling at the inlet port, e. g. air-fuel weight ratios of 18:1 to 23:1. |
