Honda Giken Kogyo Kabushiki Kaisha

Tadahiro Suzuki

Masaharu Suzuki

Toshiyuki Suzuki

Tatsuyuki Ohashi

Osahide Miyamoto

Koichi Hasegawa

Masaaki Takamatsu

Masahide Saito

Takehiro Katakura

Tooru Takahashi

Kimiaki Yamada

In a control apparatus for that automatic transmission of a vehicle which is provided with speed-change solenoid valves for regulating the hydraulic oil pressures in the hydraulic engaging elements through speed-change control valves corresponding to the hydraulic engaging elements, cleaning work to remove foreign matter in the solenoid valves is performed by varying the opening degree of the speed-change solenoid valves during running of the vehicle without affecting the hydraulic oil pressures in the hydraulic engaging elements. At the time of a line pressure control mode in which the line pressure is reduced below a maximum set pressure, the opening degree of the speed-change solenoid valve is varied within a range in which there is outputted a signal pressure higher than a minimum signal pressure required to fully open a speed-change control valve which corresponds to the hydraulic engaging element of the then-established speed transmission train.

Control apparatus for automatic transmission of vehicle

A system for controlling an automatic vehicle transmission, including a gear system and hydraulic clutches which hold a member of the gear system stationary to produce gear reduction or reverse, having an oil line which connects the clutches to an oil pressure source, a pressure control valve having a solenoid provided in the oil line which generates a regulated oil pressure to be supplied to the clutches in response to a current supplied to the solenoid, a switch valve provided in the oil line which switches the oil pressure to be supplied to the one of the clutches between the regulated oil pressure and a line pressure. In the system, it is discriminated whether the pressure control valve does not supply the regulated oil pressure to the clutches and if so, a dither current is supplied to the solenoid such that the valve repeatedly performs a vibrational motion to remove any grit therefrom, thereby removing grit without causing gear-shift shock or clutch vibration.

Solenoid self-cleaning pressure valve for automatic vehicle transmission

In a control apparatus for a hydraulically operated vehicular transmission, the hydraulic pressure of a hydraulic clutch on the engaging side which is engaged at the time of speed changing (engaging pressure) is detected by a hydraulic pressure sensor. When the detected value of the engaging pressure has exceeded a predetermined value, the hydraulic pressure of a hydraulic clutch on the disengaging side to be disengaged at the time of speed changing (disengaging pressure) is reduced to a predetermined low pressure. Even if the detected value of the engaging pressure has exceeded a predetermined value YPC, the decrease in the disengaging pressure down to a predetermined low pressure QUPOFFB is delayed by a predetermined time YTMUP9 at the time of low oil temperature when the detected value of an oil temperature to be detected by an oil temperature sensor is below a predetermined value YTO. When a discrimination is made as to whether the detected value of the engaging pressure PC(N+1) has exceeded the predetermined value YPC from a predetermined time after the start of the speed changing, the time to start the discrimination may be delayed by a predetermined time at the time of low oil temperature.

Transmission controller responsive to low oil temperature to delay the

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Tochigi-ken, Japan

Tadahiro Suzuki