Aisin Seiki Kabushiki Kaisha

Tetsuhiro Miyazawa

Masaru Ebata

Masato Shimei

Hiroshi Kawazoe

Shigeki Goto

Yoshitami Saitou

Nobuyuki Isono

Shuji Sadakari

Tsuyoshi Oyama

Masato Mori

During a shift operation, a time interval TT which is required to switch a mechanical gear ratio is detected. To bring it into coincidence with a reference value, the duty cycle with which a linear solenoid valve SL6 which determines a back pressure on an accumulator is energized is adjusted. The duty cycle is adjusted in accordance with an oil temperature, a throttle valve opening and a shift mode of an automatic transmission in order to prevent the occurrence of shift shocks as a result of a variation in the shift response of the automatic transmission from transmission to transmission or with time.

Hydraulic control system with condition responsive accumulator control

Hydraulic control system for automatic transmission

An apparatus and method for synchronizing shifting of a main transmission and a subtransmission, particularly in automatic transmissions having more than four speed ranges. Synchronism is achieved by initiating the shifting of the main transmission when the speeds of the input and output shafts of the main transmission achieve a predetermined relationship.

Automatic transmission

For a 2.fwdarw.1 shift, a timing solenoid valve SL5 is maintained at a duty cycle of 0% (off) for an interval TE=1.5 sec from the initiation of the shift operation and then the duty cycle is changed to 100% (on) after the TE interval so that an oil pressure of a brake B.sub.2 is maintained low during the shift operation while the oil pressure is increased to a high oil pressure for transfer of a maximum torque used in the first speed range upon completion of the shift operation. In response to a switching of a shift lever from D or S range to L range, the timing solenoid valve SL5 is energized with a duty cycle of 100% (on) at 2 sec after such switching to provide a high oil pressure for transfer of the maximum torque, thus preventing a shift shock from occurring as a result of a switching from D or S to L range. Since a control over the oil pressure through the timing solenoid valve SL5 during the shift operation takes place by switching an energization level of the solenoid SL5, the oil pressure can be switched in an accurate manner.

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Nagoya, Japan

Tetsuhiro Miyazawa