Fail-safe gear-shifting control system for an automatic transmission
AssigneeMazda Motor Corporation
InventorsShinji Shimaoka, Koichi Yamamoto
Life of this patent
Estimating the term…
Abstract
In a gear-shifting control system for an automatic transmission, gear-shifting is normally controlled according to main gear-shifting characteristics in which gear-shifting points are determined using the turbine rpm as a parameter. On the other hand, gear-shifting is effected according to backup gear-shifting characteristics which are determined using the vehicle speed as a parameter in case of failure of the part for detecting the turbine rpm.
Claims11
A-gear-shifting control system for an automatic transmission having a torque converter connected to an engine output shaft, a transmission gear mechanism connected to the output shaft of the torque converter, a fluid pressure type actuator means for actuating the transmission gear mechanism to shift, and an electromagnetic means for controlling the supply of pressurized fluid to the fluid pressure type actuator means, the gear-shifting control system comprising a rotational speed detecting means for detecting the rotational speed of the output shaft or the input shaft of the torque converter;
- an engine load detecting means for detecting engine load;
- a vehicle speed detecting means for detecting the vehicle speed;
- a main gear-shifting characteristic memory in which main gear-shifting characteristics are stored, gear-shifting points being determined with at least the engine load and the rotational speed of the output shaft or the input shaft of the torque converter employed as parameters in the main gear-shifting characteristics;
- a main gear-shifting determining means which receives at least the outputs of the rotational speed detecting means and the engine load detecting means and determines a main gear speed to be selected in accordance with the main gear-shifting characteristics;
- a backup gear-shifting characteristic memory in which backup gear-shifting characteristics are stored, gear-shifting points being determined with at least the vehicle speed employed as a parameter in the backup gear-shifting characteristics;
- a backup gear-shifting determining means which receives at least the output of the vehicle speed detecting means and determines a backup gear speed to be selected in accordance with the backup gear-shifting characteristics;
- a failure detecting means for detecting failure of the rotational speed detecting means;
- a gear speed signal switching means which receives the signals from the failure detecting means and the main and backup gear-shifting determining means and outputs the signal from the backup gear-shifting determining means when the rotational speed detecting means fails;
- and a transmission control means which controls the electromagnetic means according to the output of the gear speed signal switching means.
A gear-shifting control system for an automatic transmission having a torque converter connected to an engine output shaft, a transmission gear mechanism connected to the output shaft of the torque converter, a fluid pressure type actuator means for actuating the transmission gear mechanism to shift, and an electromagnetic means for controlling supply of pressurized fluid to the fluid pressure type actuator means, the gear-shifting control system comprising a rotational speed detecting means for detecting the rotational speed of the output shaft of the torque converter;
- an engine load detecting means for detecting load on the engine;
- a vehicle speed detecting means for detecting the vehicle speed;
- a main gear-shifting characteristic memory in which main gear-shifting characteristics are stored, gear-shifting points being determined with the engine load and the rotational speed of the output shaft of the torque converter employed as parameters in the main gear-shifting characteristics;
- a main gear-shifting determining means which receives the outputs of the rotational speed detecting means and the engine load detecting means and determines a main gear speed to be selected in accordance with the main gear-shifting characteristics;
- a backup gear-shifting characteristic memory in which backup gear-shifting characteristics are stored, gear-shifting points being determined with at least the vehicle speed employed as a parameter in the backup gear-shifting characteristics;
- a backup gear-shifting determining means which receives at least the output of the vehicle speed detecting means and determines a backup gear speed to be selected in accordance with the backup gear-shifting characteristics;
- a failure detecting means for detecting failure of the rotational speed detecting means;
- a gear speed signal switching means which receives the signals from the failure detecting means and the main and backup gear-shifting determining means and outputs the signal from the backup gear-shifting determining means when the rotational speed detecting means fails;
- and a transmission control means which controls the electromagnetic means according to the output of the gear speed signal switching means.
Dependencies are inferred from the claim text.