Patent ID: 7819093

Claim:
An engine hydraulic control apparatus, which is an apparatus that controls the hydraulic pressure of an engine, comprising: an oil pump that draws oil from an oil tank; a piston jet that opens when the hydraulic pressure of oil that has been drawn by the oil pump attains a valve opening pressure Qa, and injects oil towards a piston through an oil injection path; a relief valve that is disposed on an oil return path that differs from the oil injection path, and that opens when the hydraulic pressure of the oil that has been drawn by the oil pump attains a valve opening pressure Qb; and a switching valve that is disposed on the oil return path, wherein: the valve opening pressure Qb is set to the valve opening pressure that is within a range of the necessary hydraulic pressure that can ensure the necessary amount of oil that is required for the lubrication of the engine and is lower than the valve opening pressure Qa; the switching valve carries out the opening and closing operation by referring to an estimated oil amount that is estimated by circulating oil amount estimating means; and the circulating oil amount estimating means calculates the estimated oil amount based on a hydraulic pressure value that has been obtained by hydraulic pressure measuring means, an oil temperature value that has been obtained from oil temperature measuring means, and the pumping speed.