Mitsubishi Jidosha Kogyo Kabushiki Kaisha

Akihiro Kondo

Kenjiro Fujita

Seiichi Inukai

Katsutoshi Usuki

Yasuhiko Fujita

Mitsuru Yuge

Yoshio Hasegawa

Toyoji Ohnishi

A hydraulic control device for an automatic transmission including a first frictional engaging element for achieving a low-speed side position, a second frictional engaging element for achieving a position higher in speed than the low-speed side position, a third frictional engaging element for achieving a position even higher in speed than the high-speed side position, a regulator valve for regulating pressure from an oil pump to a predetermined pressure and reducing the predetermined pressure in response to supply of a pilot pressure, and a control valve for controlling the pressure from the regulator valve to a desired hydraulic pressure, for controlling hydraulic pressures to the plural frictional engaging elements. A change-over valve is provided for making the control valve in communication with one of the first frictional engaging element and the third frictional engaging element and supplying and discharging the pilot pressure to the regulator valve, so that the change-over valve is operated by hydraulic pressure supplied to the second frictional engaging element and takes a first position where the control valve communicates with the first frictional engaging element and blocks supply of the pilot pressure to the regulator valve when the supply pressure is lower than a predetermined value, and takes a second position where the control valve communicates with the third frictional engaging element and supplies the pilot pressure to the regulator valve when the supply pressure to the second frictional engaging element is higher than a predetermined value.

Hydraulic control appartus for automatic transmission

A bypass line is provided to return an excess portion of working oil, whose pressure has been regulated by a regulator valve, to a suction side of an oil pump from a point between the regulator valve and a torque converter pressure regulator valve. An oil filter is inserted in the bypass line.

Hydraulic circuit

A fluid pressure control device is equipped with a valve body which has an input port connected to a hydraulic fluid source, an output port which is connected to a pressure chamber of a clutch of an automatic transmission, and a discharge port. It further includes a solenoid valve which is incorporated in the valve body and has a valve spool designed to selectively connect the output port to the input port or the discharge port. A discharge passage extends from the discharge port of the valve body, the discharge passage having a discharge port which is positioned at a higher level than the liquid level of the oil pan of the automatic transmission. Finally, a reed valve acts to close the discharge port of the discharge passage to maintain fluid at the aforementioned higher level, and allows the discharge of the hydraulic fluid only through the discharge port.

Fluid pressure control device for an automatic transmission in a vehicle

Growing community of inventors

Kyoto, Japan

Akihiro Kondo