| 摘要 |
PROBLEM TO BE SOLVED: To reduce the number of hydraulic switches, to reduce costs, to reduce a breakdown ratio of an automatic transmission caused by breakdowns of the hydraulic switches, and to improve reliability of a hydraulic pressure control unit. SOLUTION: The hydraulic pressure control unit for an automatic transmission comprises: control valves 22 to 25 for directly controlling connection and disconnection of frictional connection elements; shift valves 31 to 33 for switching an oil passage between a manual valve 21 and the control valves 22 to 25; a plurality of on-off solenoid valves S1 to S3 for switching positions of valve spools of the shift valves 31 to 33; and a hydraulic switch SW3 for detecting motions of the third control valve 24. The second shift valve 32 introduces output hydraulic pressure of the on-off solenoid valve S2 to the hydraulic switch SW3 when receiving the output hydraulic pressure of the on-off solenoid valve s2, and also introduces controlling hydraulic pressure of the third control valve 24 to the hydraulic switch SW3 when not receiving output hydraulic pressure of the on-off solenoid valve S2. COPYRIGHT: (C)2007,JPO&INPIT |
