Patent ID: 7222005

Claim:
An abnormal oil pressure reduction determination device for use with a transmission of a vehicle with an engine, the transmission having an oil pressure control mechanism which comprises an oil pump driven by a rotation of the engine and performs speed change control using oil pressure from the oil pump, the abnormal oil pressure reduction determination device comprising: an oil pressure sensor which detects a real oil pressure, a sensor which detects a vehicle running state including a rotation speed of the engine, and a controller which sets an oil pressure command value for the oil pressure control mechanism, the controller comprising a microcomputer, wherein: the controller functions to: compute a lower limiting oil pressure which is possible in the vehicle running state, based on the rotation speed of the engine, compare the real oil pressure with the lower limiting oil pressure, compare the real oil pressure with the oil pressure command value, and when the real oil pressure is less than the lower limiting oil pressure and when a pressure difference between the real oil pressure and the oil pressure command value exceeds a reference value, determine a presence of an abnormal oil pressure reduction due to a fault in the oil pressure control mechanism.