Patent ID: 7643924
Filing Date: 2010-01-05
Classification: F16H

Abstract:
1. A failure determining apparatus of a hydraulic pressure control circuit, comprising: a switching valve which switches a lock-up clutch of a fluid power transmitting device that transmits output of an internal combustion engine to a shift mechanism to an applied state; a solenoid valve which outputs hydraulic pressure for regulating a pressure difference between an apply side fluid chamber and a release side fluid chamber of the fluid power transmitting device; a hydraulic pressure switch that operates in response to an amount of hydraulic pressure output from the solenoid valve; a determining device that determines whether a failure has occurred in one of the solenoid valve and the hydraulic pressure switch based on an operating state of the hydraulic pressure switch when the lock-up clutch is in a released state; and an identifying device which, when the determining device has determined that there is a failure in one of the solenoid valve and the hydraulic pressure switch, identifies which, from among the solenoid valve and the hydraulic pressure switch, the failure has occurred in based on the application state of the lock-up clutch when the switching valve is instructed to supply hydraulic fluid to the apply side fluid chamber and discharge hydraulic fluid from the release side fluid chamber, and the solenoid valve is instructed not to output hydraulic pressure, wherein the hydraulic pressure control circuit releases the lock-up clutch by supplying hydraulic fluid to the release side fluid chamber and discharging hydraulic fluid from the apply side fluid chamber, and applies the lock-up clutch by supplying hydraulic fluid to the apply side fluid chamber and discharging hydraulic fluid from the release side fluid chamber using the switching valve, and regulating the pressure difference by outputting hydraulic pressure from the solenoid valve.