Aisin Seiki Kabushiki Kaisha

Toyota Jidosha Kabushiki Kaisha

Satoshi Maruchi

Shigeki Goto

Choji Furusawa

Isamu Minemoto

In an automatic transmission having a torque converter, a planetary gear mechanism receiving an output from the torque converter and including brakes and clutches, and a hydraulic pressure circuit for actuating the brakes and clutches. An arrangement is provided for varying servo hydraulic pressure, which is for achieving low gear, in dependence upon vehicle velocity.

Automatic transmission control system incorporating an exhaust brake

An exhaust brake control system includes an input switch for commanding actuation of an exhaust brake, a throttle sensor for sensing that an accelerator pedal has been depressed in excess of a predetermined angle, a control unit for outputting a control signal in dependence upon output signals from the input switch and throttle sensor, and a valve means for opening and closing an exhaust passageway in dependence upon a control signal produced by the control unit. The control unit includes a shift sensor for sensing at least an L-range shift of an automatic transmission, and a servo hydraulic pressure sensor for sensing servo hydraulic pressure that actuates a servo piston for establishing 1st speed range. When the shift sensor senses that the automatic transmission has been shifted to the L range, the control unit outputs a control signal for actuating the valve means to open the exhaust gas passageway at such time that the servo hydraulic pressure sensor outputs a signal indicative of a value greater than a predetermined value. Exhaust braking is applied following attainment of a sufficiently high servo hydraulic pressure immediately after a downshift, thus preventing the engine from stopping at application of exhaust braking. The same is applied to downshifting to '2' range.

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Toyota, Japan

Satoshi Maruchi