Jatco Corporation

Hideharu Sugiyama

Ikuo Hirose

Yoshifumi Fujita

An automatic transmission control system is capable of quickly and accurately judging the normal state and faulty state of an input shaft rotation speed sensor and/or an output shaft rotation speed sensor. The system includes an input shaft rotation speed sensor condition judging device for judging whether an input shaft rotation speed sensor detecting a rotation speed NI of an input shaft of the automatic transmission is in a normal or faulty state, an output shaft rotation speed sensor condition judging device for judging whether an output shaft rotation speed sensor detecting a rotation speed No of an output shaft of the automatic transmission is in a normal or faulty state, a multiplying means for multiplying the rotation speed No of the output shaft with a current transmission gear ratio, and comparing and judging means for judging whether the multiplied value is coincident with the rotation speed NI of the input shaft. On the basis of those judgements, the output shaft rotation speed sensor is judged whether it is in the normal state or not by the output shaft rotation speed sensor condition judging device.

Method and system for controlling automatic transmission

An automatic transmission learning control apparatus comprises a memory for storing parameters in memory locations specified for respective throttle valve position ranges. A physical quantity related to a gear shift operation made in an automatic transmission is measured. The parameter stored in the memory location specified by the throttle valve position range including the sensed throttle valve position is updated in a direction to bring the measured physical quantity into agreement with a target value. The parameter stored in the memory location specified by the throttle valve position range including the existing throttle valve position is used to control the gear shift operation. The throttle valve position ranges have a smaller width for a throttle valve position causing a greater rate of change of a torque inputted to the automatic transmission with respect to a throttle valve position change.

Automatic transmission learning control apparatus

An apparatus for controlling a lockup clutch provided in an automatic transmission having an impeller and a turbine. The pressure of the oil supplied to the lockup clutch is controlled by a lockup solenoid which is operable on a control signal having a variable duty cycle to operate the lockup clutch in a complete lockup mode to complete a mechanical connection between the turbine and the impeller and a released lockup mode to provide a hydrodynamic driving connection between the turbine and the impeller. In the presence of a command for a change of operation of the lockup clutch from its released lockup mode to its complete lockup mode, the initial value of the duty cycle of the control signal is set, based on at least one of conditions including the temperature of the oil, the engine load and the degree of slip permitted between the turbine and the impeller, at a value closer to the duty cycle set for the complete lockup mode of operation of the lockup clutch when the oil is in a condition causing a slow response to the duty cycle control.

Automatic transmission lockup clutch control apparatus

A gear shift control apparatus for use with an automatic transmission including a friction element operable on a hydraulic pressure applied thereto in an engaged and disengaged state. A gear ratio obtained in the automatic transmission is calculated based on transmission input and output shaft speeds. A reference gear ratio is set based on at least one of the transmission input and output shaft speeds. The hydraulic pressure is changed from a first level to a second level to change the friction element from the disengaged state to the engaged state so as to produce a change from a higher gear to a lower gear when the gear ratio reaches the reference gear ratio. The reference gear ratio increases as at least one of the transmission input and output shaft speeds increases. Alternatively, the reference gear ratio may be set at a smaller value as the rate of change of the gear ratio increases.

Gear shift control apparatus

A gear shift control apparatus for use in an automatic transmission having a friction element operable on a hydraulic pressure applied thereto in an engaged and disengaged state. A shift change control is performed to change the hydraulic pressure in a manner to produce a shift change according to a predetermined shift schedule based on transmission input and output shaft speeds and engine load. A section is provided for calculating the gear ratio obtained in the automatic transmission based on the transmission input and output shaft speeds. When a change is effected to one of highest and lowest gears or when a change is effected from one of the highest and lowest gears, a transient hydraulic pressure control of changing the hydraulic pressure from the first level to the second level is performed to change the friction element state so as to effect a shift change when the calculated gear ratio reaches a reference gear ratio. The transient hydraulic pressure control is interrupted with inhibition of any change to the highest and/or lowest gear when at least one of the first sensor, the second sensor and the gear ratio calculated section is subject to failure.

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Shizuoka, Japan

Hideharu Sugiyama