| 摘要 |
PROBLEM TO BE SOLVED: To prevent the balance of oil quantities from worsening even if converter pressure is excluded so that the lock-up control pressure of a three-circuit- type torque converter can be reduced. SOLUTION: During lock-up operation, a signal pressure PS is generated in a circuit 33 by causing a solenoid 23 to carry current, and the spools 21b, 22b of valves 21, 22 are held in depressed positions. The operating pressure PT of a circuit 26 is thereby introduced into a circuit 27 and, after it is supplied to a converter chamber 6 from a circuit 7 via an orifice 27a on one hand and directed to an oil cooler 24 from a circuit 29 via an orifice 28a on the other hand, it is used for lubricating a lubricated part 25. With a pressure PD serving as original pressure, a lock-up control pressure PL proportional to PS is output to a circuit 12 to cause a piston 10 to move rightward to engage a lock-up clutch 9 to thereby hold the torque converter 1 in a lock-up state. For oil returning from the chamber 6 to be excluded from a circuit 30 and the lubricated part 25, the lock-up control pressure PL in a chamber 11 can be lowered by lowering of pressure in the chamber 6. Since the oil excluded is used effectively in lubrication of the lubricated part 25, the balance of oil quantities will not worsen.
|
