Device and method for controlling automatic gearbox

1. A control device for an automatic transmission in which a speed ratio between an input shaft connected to an engine side of a vehicle and an output shaft connected to a driving system of the vehicle is modified, the control device comprising:

vehicle speed detecting means for detecting an actual vehicle speed, which is a traveling speed of the vehicle;

vehicle speed estimating means for calculating a read-ahead vehicle speed, which is a target future vehicle speed at a predetermined time, based on the actual vehicle speed and an acceleration component speed;

accelerator pedal opening angle detecting means for detecting an accelerator pedal opening angle;

target gear shift ratio calculating means for calculating a target gear shift ratio based on the read-ahead vehicle speed and the accelerator pedal opening angle when the accelerator pedal opening angle is equal to or larger than a first predetermined value and for calculating the target gear shift ratio based on the actual vehicle speed and the accelerator pedal opening angle when the accelerator opening angle is smaller than a second predetermined value; and

gear shift control means for controlling the automatic transmission based on the target gear shift ratio.

2. The control device for the automatic transmission as claimed in claim 1 ,

wherein the first predetermined value is larger than the second predetermined value, and

wherein the target gear shift ratio calculating means calculates the target gear shift ratio based on a weighted vehicle speed for which the read-ahead vehicle speed and the actual vehicle speed are weighted in accordance with the accelerator opening angle when the accelerator opening angle is smaller than the first predetermined value but is equal to or larger than the second predetermined value.

3. A control device for an automatic transmission, the automatic transmission being configured to modify a speed ratio between an input shaft connected to an engine side of a vehicle and an output shaft connected to a driving system of the vehicle, the control device comprising:

a vehicle speed detection section configured to detect an actual vehicle speed, which is a traveling speed of the vehicle;

an accelerator pedal opening angle detecting section configured to detect an accelerator pedal opening angle; and

a controller, the controller being configured to calculate a read-ahead vehicle speed, which is a target future vehicle speed at a predetermined time, based on the actual vehicle speed and an acceleration component speed, to calculate a target gear shift ratio based on the read-ahead vehicle speed and the accelerator pedal opening angle when the accelerator pedal opening angle is equal to or larger than a first predetermined value, to calculate the target gear shift ratio based on the actual vehicle speed and the accelerator pedal opening angle when the accelerator pedal opening angle is smaller than a second predetermined value, and to control the automatic transmission based on the target gear shift ratio.

4. The control device for the automatic transmission as claimed in claim 3 ,

wherein the first predetermined value is larger than the second predetermined value, and

wherein the controller calculates the target gear shift ratio based on a weighted vehicle speed for which the read-ahead vehicle speed and the actual vehicle speed are weighted in accordance with the accelerator pedal opening angle, when the accelerator opening angle is smaller than the first predetermined value but is equal to or larger than the second predetermined value.

5. A control method for an automatic transmission, the automatic transmission being configured to modify a speed ratio between an input shaft connected to an engine side of a vehicle and an output shaft connected to a driving system of the vehicle, the control method comprising:

detecting an actual vehicle speed, which is a traveling speed of the vehicle, through vehicle speed detecting means;

detecting an accelerator pedal opening angle through accelerator pedal opening angle detecting means;

calculating a read-ahead vehicle speed, which is a target future vehicle speed at a predetermined time, based on the actual vehicle speed and an acceleration component speed with an electronic controller;

calculating a target gear shift ratio based on the read-ahead vehicle speed and the accelerator pedal opening angle when the accelerator opening angle is equal to or larger than a first predetermined value with the electronic controller;

calculating the target gear shift ratio based on the actual vehicle speed and the accelerator pedal opening angle when the accelerator opening angle is smaller than a second predetermined value with the electronic controller; and

controlling the automatic transmission based on the target gear shift ratio with the electronic controller.

6. The control method for the automatic transmission as claimed in claim 5 ,

wherein the first predetermined value is larger than the second predetermined value, and

wherein when the accelerator pedal opening angle is smaller than the first predetermined value but is equal to or larger than the second predetermined value, the target gear shift ratio is calculated based on a weighted vehicle speed for which the read-ahead vehicle speed and the actual vehicle speed are weighted in accordance with the accelerator pedal opening angle.