| 摘要 |
In an internal combustion engine utilizing hydraulic valve lifters, a source of pressurized engine oil at a higher than normally expected pressure is supplied thereto. The oil delivered to the lifter galley is derived from either an engine oil pump which produces a higher pressure oil flow then conventionally desired for normal engine operation or a separate oil pump. The pressure setting of the oil output from either pump is determined by the engine RPM, i.e. higher pressure with higher engine RPM or from pump speed if an electrically operated separate pump is employed. The exact oil pressure level delivered to the valve galley or to individual valve galleys is determined by an on board computer (engine controller) monitoring the manifold pressure, engine RPM and throttle position so that the hydraulic lifter plunger maintains contact with the valve stem regardless of engine RPM or pump motor speed and variable and different amounts oil pressure and resulting valve lift can be achieved at various selected locations on the valve lift curve created by the valve's camshaft lobe. Variable high oil pressure is supplied only to the lifters to selectively alter their normal degree of valve lift at any location along the valve's cam operating curve while the remaining oil delivery areas of the engine operate at their normally expected oil pressure levels. In event of a failure of normal engine oil pump operation when a second auxiliary pump for galley delivery is used, an electric valve is provided to channel oil from the auxiliary pump to the engine areas requiring lubrication.
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