Mazda Motor Corporation

Toru Kawano

Hidehiko Mishima

An automatic transmission has a transmission gear mechanism for transmitting the engine output power by way of a plurality of power transmission paths, and friction engagement elements which are operated by a line pressure from a control valve to change the power transmission path through the transmission gear mechanism. Feed of the line pressure is controlled by a throttle pressure corresponding to the engine load and a governor pressure corresponding to the output speed of the transmission gear mechanism to effect gear shifting. A line pressure control system for controlling the line pressure comprises a regulator valve for regulating the line pressure, and a throttle modulator valve for determining a throttle modulator pressure for controlling the regulator valve according to the governor pressure and the throttle pressure so that the line pressure is increased with increase of the throttle pressure and is lowered with increase of the output speed of the transmission gear mechanism.

Line pressure control system for automatic transmission

An automatic transmission has a transmission gear mechanism for transmitting the engine output power by way of a plurality of power transmission paths, and friction engagement elements which are operated by a line pressure to change the power transmission path through the transmission gear mechanism to shift the gears. A hydraulic control system for the automatic transmission comprises a manual shift valve for changing the driving range, a plurality of shift valves each for effecting gear-shifting assigned thereto by controlling the feed of the line pressure to the friction engagement elements corresponding to the gear-shifting according to a throttle pressure and a governor pressure, and a range control valve which is provided in one of the hydraulic lines for transmitting the throttle pressure and the governor pressure to one of the shift valves to control transmission of the corresponding pressure to the shift valve according to the driving range determined by the manual shift valve, thereby changing the shift pattern according to the driving range.

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Hiroshima, Japan

Toru Kawano