HYDRAULIC SWITCH MALFUNCTION ASSESSMENT DEVICE

摘要

A hydraulic switch malfunction assessment device includes a solenoid valve disposed in a hydraulic circuit of an automatic transmission and having a characteristic such that a hydraulic pressure supplied to a frictional engagement element changes due to a change in an electric current supplied to the solenoid valve, and a hydraulic switch interposed between the solenoid valve and the frictional engagement element and configured to output an ON signal when the hydraulic pressure is higher than or equal to a threshold value and output an OFF signal when the hydraulic pressure is less than the threshold value. Also provided is a controller configured to control the supplied current to a prescribed current value or less when a predetermined running condition has been met, and then assess a malfunction of the hydraulic switch, based on a state of operation of the solenoid valve and the signal from the hydraulic switch.

主权项

1. A hydraulic switch malfunction assessment device comprising:
a solenoid valve disposed in a hydraulic circuit of an automatic transmission mounted on a vehicle and having a characteristic such that a working hydraulic pressure supplied to a frictional engagement element of the automatic transmission changes due to a change in an electric current supplied to the solenoid valve; a hydraulic switch installed in the hydraulic circuit and interposed between the solenoid valve and the frictional engagement element and configured to output an ON signal when the working hydraulic pressure is higher than or equal to a prescribed threshold value and output an OFF signal when the working hydraulic pressure is less than the prescribed threshold value; a detection means for detecting a state of operation of the solenoid valve; and a malfunction assessment means for assessing a malfunction of the hydraulic switch based on the state of operation of the solenoid valve detected by the detection means and the signal from the hydraulic switch, wherein the malfunction assessment means is configured to control the supplied electric current to a prescribed electric current value or less when a predetermined running condition has been met, and then assess the malfunction of the hydraulic switch.