| 摘要 |
<P>PROBLEM TO BE SOLVED: To precisely detect failure of a selector valve so as to prevent occurrence of interlock. <P>SOLUTION: An automatic transmission includes at least one frictional engagement element having two pistons and a first oil pressure chamber and a second oil chamber which are opposite to the pistons and to which hydraulic fluid pressure of the frictional engagement element is supplied, a pressure control valve to regulate the fluid pressure supplied to the frictional engagement element having the two pistons to be maintained at a predetermined pressure level, and the selector valve arranged to switch the communication state of an oil path for communication of the pressure control valve and the second oil pressure chamber. When shifting from a first gear position where the frictional engagement element having the two pistons is disengaged to a second gear position where the frictional engagement element is engaged, the selector valve is brought into the non-communication state. Further, the oil pressure is controlled to be supplied to the frictional engagement element having the two pistons by the pressure control valve, and it is judged (S15) based on a parameter at the time of the shifting operation that the selector valve is in an abnormal state such that it cannot be switched to the non-communication state. <P>COPYRIGHT: (C)2008,JPO&INPIT |
