Gear shift system for vehicle, control method and control device for automatic transmission

A gear shift system for a vehicle comprising:

• an automatic transmission;
• and
• a control unit,
• said control unit being adapted to detect a vehicle speed,
• a first information representing a driver's operation of an accelerator pedal or a brake pedal, and
• a second information representing a running environment of said vehicle, characterized in that
• said control unit sets a parameter having one of a detected vehicle speed, an accelerator pedal position and a throttle position as well as drive force as components, wherein each of said accelerator pedal position, said throttle position and said drive force is set according to said first information and said second information,
• sets a gear ratio according to said parameter and a map determining the gear ratio based on one of the accelerator pedal position and the throttle position as well as the vehicle speed and the drive force,
• controls said automatic transmission to shift the gear according to said set gear ratio,
• allows down-shift after up-shift as well as the up-shift after the down-shift when at least one of a first condition that an amount of change of one of the accelerator pedal position and the throttle position after the last change of the gear ratio is larger than a threshold and a second condition that an amount of change of the drive force after the last change of the gear ratio is larger than the threshold is satisfied, and
• inhibits the down-shift after the up-shift as well as the up-shift after the down-shift when neither said first nor said second condition is satisfied.

A control method for an automatic transmission mounted on a vehicle, comprising the steps of:

• detecting a vehicle speed;
• detecting a first information representing a driver's operation of an accelerator pedal or a brake pedal;
• detecting a second information representing a running environment of said vehicle;
• setting a parameter using said control unit having one of the detected vehicle speed, an accelerator pedal position and a throttle position as well as a drive force as components, wherein each of said accelerator pedal position and said drive force is set according to said first information and said second information;
• setting a gear ratio using said control unit according to said parameter and a map determining the gear ratio based on one of the accelerator pedal position and the throttle position as well as the vehicle speed and the drive force, and having shift-down lines at which shifting is carried out in dependence on the vehicle speed and the drive force, wherein said shift-down lines change in accordance with changes of the accelerator pedal position or the throttle position such that the drive force decreases with an increase of the accelerator pedal position or the throttle position;
• and
• controlling said automatic transmission to shift the gear according to said set gear ratio.

A control method for an automatic transmission mounted on a vehicle, comprising the steps of;

• detecting a vehicle speed;
• detecting a first information representing a driver's operation of an accelerator pedal or a brake pedal;
• detecting a second information representing a running environment of said vehicle;
• setting a parameter using said control unit having one of the detected vehicle speed, an accelerator pedal position and a throttle position as well as a drive force as components, wherein each of said accelerator pedal position and said drive force is set according to said first information and said second information;
• setting a gear ratio using said control unit according to said parameter and a map determining the gear ratio based on one of the accelerator pedal position and the throttle position as well as the vehicle speed and the drive force;
• controlling said automatic transmission to shift the gear according to said set gear ratio;
• allowing down-shift after up-shift as well as the up-shift after the down-shift when at least one of a first condition that an amount of change of one of the accelerator pedal position and the throttle position after the last change of the gear ratio is larger than a threshold and a second condition that an amount of change of the drive force after the last change of the gear ratio is larger than the threshold is satisfied;
• and
• inhibiting the down-shift after the up-shift as well as the up-shift after the down-shift when neither said first nor said second condition is satisfied.