| 摘要 |
PROBLEM TO BE SOLVED: To inhibit instability of engine operation caused by pressure drop of oil. SOLUTION: A hydraulic control device for an internal combustion engine includes a relief valve 21 opening and releasing part of oil when the pressure of oil delivered from an oil pump 14 becomes a prescribed valve opening pressure or higher, and a change-over valve 29 changing over the valve opening pressure according to an engine operation state. Pressure stage of oil supplied to each section of an internal combustion engine is changed over between a high pressure stage and a low pressure stage by changing valve the opening pressure by the change-over valve 29. An oil pressure sensor 44 detecting the pressure of oil after pressure regulation by the relief valve 21 is provided. The valve opening pressure is forcibly changed to a high pressure corresponding to the high pressure stage when the oil pressure detected by the oil pressure sensor 44 is below a pressure drop determination value set as a value lower than a value assumed from engine speed NE at that time in a state where the valve opening pressure is set to a pressure corresponding to the low pressure stage. COPYRIGHT: (C)2011,JPO&INPIT
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