| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic circuit for an automatic transmission that allows smooth traveling of a vehicle even when an electromagnetic solenoid valve of a pulley oil-pressure supply system fails, and also, allows a selector valve operated so as to reduce the maximum oil pressure, to be interposed in a lock-up oil-pressure supply system different from the pulley oil-pressure supply system. SOLUTION: The hydraulic circuit for an automatic transmission includes first/second electromagnetic solenoid valves 102, 104 for supplying oil pressure from oil passages for connecting cylinder chambers of a pulley, a third electromagnetic solenoid valve 116 for supplying an oil pressure from a third oil passage for connecting cylinder chambers of a lock-up clutch, and a selector valve 122 interposed in the third oil passage. When the first/second electromagnetic solenoid valves fail, the oil pressure is supplied to the cylinder chambers of the pulley so as to reduce a gear ratio. When the third electromagnetic solenoid valve fails, a spool of the selector valve is displaced to a position that opens the third oil passage while reducing the oil pressure supplied to the cylinder chambers of the pulley. COPYRIGHT: (C)2011,JPO&INPIT |
