Honda Giken Kogyo Kabushiki Kaisha

Shoji Asatsuke

Tatsuyuki Ohashi

Hideki Wakamatsu

Takayuki Yamaguchi

Tetsuya Mochizuki

Takamichi Shimada

Yoshiharu Saito

Kazuma Hatakeyama

Keiichi Ishikawa

Koichi Kimura

Jiro Obinata

Tomonari Shirai

Shyoji Arai

A control system for an automatic transmission comprises a forward/reverse selection hydraulic servomechanism a D inhibitor valve, which controls the supply of a line pressure to the servo-oil chambers of this servomechanism, and a plurality of solenoid valves which are used for controlling the actuation of the shift valves and the D inhibitor valve. This control system comprises a first neutral mode and a second neutral mode for a neutral range. In the first neutral mode, the D inhibitor valve is switched to a forward drive position, and the forward drive servo-oil chamber is connected to a drain. In the second neutral mode, the D inhibitor valve is switched to a reverse drive position, and the forward drive and reverse drive servo-oil chambers are both connected to the drain.

Automatic transmission control system

An automatic transmission comprises a plurality of clutches , which are provided to select power transmission paths, respectively, in a parallel shaft speed change mechanism TM and a plurality of shift valves , which are used for controlling the supply and drain of hydraulic oil to and from these clutches. For this automatic transmission, a control system comprises a plurality of solenoid valves , which are used for controlling the supply and drain of a line pressure so as to control the actuation of these shift valves. This system, when the shift lever is manipulated to set the neutral range, sets the transmission into either a first neutral mode or a second neutral mode depending upon the speed of the vehicle, the first neutral mode being set when the vehicle is driving at a speed equal to or more than a critical speed, and the second neutral mode being set when the vehicle speed is less than the critical speed. In this control, the combination of on/off operations of the solenoid valves for setting the first neutral mode is different from the combination for setting the second neutral mode.

An automatic transmission comprises a forward/reverse selection hydraulic servomechanism which actuates a dog clutch and a plurality of clutches and For this automatic transmission, a control system comprises first&tilde;fifth on/off solenoid valves and first&tilde;third linear solenoid valves These valves are used to control the supply and drain of a line pressure to and from the forward/reverse selection hydraulic servomechanism and first&tilde;fifth shift valves and so as to control the actuation thereof for the selective engagement of the clutches. This system, when it detects, by a hydraulic switch a condition that the D range is selected and that the actuation command signals being sent to the solenoid valves correspond to one of the signal combinations which are used for setting the driving modes of the D range, allows the actuation of the solenoid valves by these actuation command signals.

A changeover valve (13) connected to a shift valve unit (12) via four oil passages L3-L6, and two pressure regulating valves (14.sub.1, 14.sub.2) are provided. At speed changing when the changeover valve (13) is in a first (right) position, an off-going hydraulic clutch is connected to oil passage L3 to control its pressure drop by the pressure regulating valve (14.sub.1) and an on-coming hydraulic clutch is connected to L5 to control its pressure rise by the pressure regulating valve (14.sub.2). After completion of the speed changing, the changeover valve (13) is switched to a second (left) position. At speed changing when the changeover valve (13) is in the second position, an on-coming hydraulic clutch is connected to L4 to control its pressure rise by the pressure regulating valve (14.sub.1) and an off-going hydraulic clutch is connected to the L6 to control its pressure drop by the pressure regulating valve (14). After completion of the speed changing, the changeover valve (13) is switched to the first position. After completion of the speed changing, oil at line pressure is supplied to the on-coming hydraulic clutch from the line pressure oil passage L2 without passing through the pressure regulating valves, and oil is discharged from the off-going hydraulic clutch without passing through the pressure regulating valves.

Control apparatus for hydraulically operated vehicular transmission

A hydraulic control apparatus for a hydraulically operated vehicular transmission provided with hydraulic engaging elements has a control valve provided with a drain port, and oil discharge passages which are connected, at the time of disengagement of the hydraulic engaging elements, to working oil passages which are in communication with the hydraulic engaging elements. The hydraulic oil to be discharged from the drain port of the control valve is supplied to the oil discharge passages. The apparatus is provided with an oil reservoir for storing therein the hydraulic oil to be discharged from the drain port of the control valve. The oil discharge passages are connected to the oil reservoir.

Hydraulic control apparatus for maintaining a filled condition for the

An oil ejection control valve is interposed in a first hydraulic engagement element of an automatic transmission system from which oil is ejected when a certain speed stage shifting operation is to be carried out. The oil ejection control valve is provided with a valve member which is normally biased to a closed position by a spring. The valve member is provided with a first pressure receiving surface to which the ejection pressure from the first hydraulic engagement element is applied and a second pressure receiving surface to which the supply pressure to a second hydraulic engagement element is applied during the afore-mentioned shifting operation, the second hydraulic engagement element being the one to which pressure is supplied so as to engage the same during the speed stage shifting operation. Since the ejection pressure can favorably contribute to the reduction in the engagement pressure of the first hydraulic engagement element that is about to be disengaged without waiting for the engagement pressure for the second hydraulic engagement element to be engaged to build up, a smooth shifting operation is made possible either in an upshift operation or a downshift operation, and a transmission shock can be avoided at all time.

Hydraulic control device for an automatic automotive transmission system

Holding device for holding the selector gear servo valve in the reverse position when the manual valve is in the neutral or parking position and when the manual valve is moved to a forward position, hydraulic pressure in the servo valve overcomes the holding to move the servo valve to a forward position. Additionally, a control valve is provided for binding the servo valve in the reverse position even when the manual valve is moved to the forward position until hydraulic pressure of the hydraulic clutch for the second transmission train reaches a predetermined level.

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Wako, Japan

Shoji Asatsuke