| 摘要 |
PURPOSE:To aim at fail-safe promotion at time of something going wrong in a lockup control solenoid valve by installing a lockup fail valve interposingly between a spool selecting chamber of a lockup control valve and this lockup control solenoid valve. CONSTITUTION:A lockup fail valve 26 is installed interposingly between a spool selecting chamber 21C of a lockup control valve 21 and a lockup control solenoid valve 23. When C1 clutch pressure Pc of the same pressure as line pressure and boost pressure PB are inputted into both first and second chambers 26B, 26C, that is, something going wrong of the like in a shifting solenoid valve, a spool 26A interrupts an interval between ports 26a and 26b, and holds a lockup clutch 20 at the release side irrespective of operation of the solenoid valve 23. On the other hand, when the clutch pressure Pc is inputted into only the first chamber 26B, this spool 26A interconnects an interval between these ports 26a and 26b, thereby allowing any transfer of the control valve 21 by the solenoid valve 23. Thus, fail-safe promotion at time of trouble in the lockup control solenoid valve is achievable in this way. |
