| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic control unit of an automatic transmission capable of maintaining the stable vehicle driving even if the failure of an electricity system occurs in an automatic transmission with a by-pass clutch. SOLUTION: The automatic transmission has plural drive gears established on an input shaft, the change gear line group composed of a driven gear established on an output shaft, the switching mechanism that switches the change gear line transmitting the power, and a by-pass clutch that transmits the power from the input shaft to the output shaft through the change gear line. The by-pass clutch control unit 70 that supplies oil to the by-pass clutch 31, 35 from a hydraulic pressure supply 61, and a fail mode valve 67 that supplies the hydraulic pressure at the time of failure of electricity system, are provided. An oil path 75A, 78A of the by-pass clutch control unit 70 is blocked by the oil pressure from the fail mode valve 67 in the power transmission condition via change gear line of the change gear line group, and the communicating condition of the oil path 75A or 78A is maintained in the engagement condition of the by-pass clutch 31 or 35. COPYRIGHT: (C)2004,JPO |
