| 摘要 |
<P>PROBLEM TO BE SOLVED: To safely implement forward movement low-speed stage or backward movement stage even in a primary failure. <P>SOLUTION: A hydraulic control device for an automatic transmission comprises: first off-fail valves 24 switched to keep a spool position of a gear stage before a failure state and output D pressure/R pressure, in the failure state where no hydraulic pressure is output from any of SL1 to SL4; a lock valve 21 switching spool positions so as to output output pressure from a predetermined one of SL1 to SL4 or the D pressure/R pressure; an on-off solenoid valve S which can control a spool position of the lock valve according to an energization state; and a second off-fail valve 25 switching spool positions, so as to output the D pressure/R pressure from the first off-fail valve 24 to a predetermined one of engaging elements C1 to C3 in the failure state, and so as to output hydraulic pressure from the lock valve 21 to a predetermined one of engaging elements C1 to C3 in a normal state where hydraulic pressure sent from any of SL1 to SL4 as prescribed. <P>COPYRIGHT: (C)2008,JPO&INPIT |
