Control device for vehicle

1. A control device for a vehicle that controls a revolution speed of a drive power source or a gear ratio of a transmission coupled to an output side of the drive power source in the vehicle equipped with the drive power source and the transmission, the control device being configured to:

determine an index that is based on a running state of the vehicle, which is in accordance with driver's intention; and

control a required revolution speed of the drive power source or a required gear ratio for the transmission based on the index, wherein:

the index is increased when at least one of an obtained longitudinal vehicle acceleration value or an obtained transverse vehicle acceleration value, which are each repeatedly obtained during running of the vehicle, is larger than a previously obtained value, and the index is slowly decreased as compared to the index increased when the obtained value is smaller than the previously obtained value,

the required revolution speed or the required gear ratio is established in advance according to a speed of the vehicle and the index,

a required maximum acceleration ratio that is established in advance according to the index is determined based on the index, and a required acceleration for each vehicle speed is determined based on a maximum generated acceleration and the required maximum acceleration ratio for each vehicle speed, and

the required revolution speed or the required gear ratio is set based on the required acceleration.

2. The control device according to claim 1 , wherein

a required maximum acceleration ratio that is established in advance according to the index is determined based on the index, and a required acceleration is determined based on a maximum generated acceleration and the required maximum acceleration ratio at a point in time at which the index is determined, and

the required revolution speed or the required gear ratio is maintained at a value at which this required acceleration is attained.

3. The control device according to claim 1 , wherein

a required maximum acceleration ratio that is established in advance according to the index is determined based on the index, and

when the index is larger than a predetermined value, a required acceleration is determined based on a maximum generated acceleration and the required maximum acceleration ratio at a point in time at which the index is determined, and the required revolution speed or the required gear ratio is maintained at a value at which this required acceleration is attained.

4. The control device according to claim 1 , wherein a driving requirement amount for the vehicle is determined, and a target revolution speed of the drive power source or a target gear ratio of the transmission is further determined based on the driving requirement amount, and the drive power source is controlled to have either the required revolution speed or the target revolution speed whichever is higher, or the transmission is controlled to have either the required gear ratio or the target gear ratio whichever is higher.

5. The control device according to claim 4 , wherein a variation rate of the revolution speed of the drive power source in a case in which the target revolution speed exceeds the required revolution speed, or a variation rate of the gear ratio in a case in which the target gear ratio exceeds the required gear ratio is made different depending on the index.

6. The control device according to claim 5 , wherein when the index based on the running state of the vehicle is relatively large, the variation rate of the revolution speed or the variation rate of the gear ratio is higher than when the index is relatively small.

7. The control device according to claim 1 , wherein when the vehicle turns, a variation of the required revolution speed or the required gear ratio is suppressed compared with a case in which the vehicle does not turn.

8. A control method for a vehicle for controlling a revolution speed of a drive power source or a gear ratio of a transmission coupled to an output side of the drive power source in the vehicle equipped with the drive power source and the transmission, the control method comprising:

determining an index that is based on a running state of the vehicle with a control device,

controlling a required revolution speed of the drive power source or a required gear ratio for the transmission based on the index, wherein the required revolution speed or the required gear ratio is established in advance according to a speed of the vehicle and the index,

increasing the index when at least one of an obtained longitudinal vehicle acceleration value or an obtained transverse vehicle acceleration value, which are each repeatedly obtained during running of the vehicle, is larger than a previously obtained value, and decreasing the index as compared to the index increased when the obtained value is smaller than the previously obtained value,

establishing a required maximum acceleration ratio in advance according to the index is determined based on the index, and determining a required acceleration for each vehicle speed based on a maximum generated acceleration and the required maximum acceleration ratio for each vehicle speed, and

setting the required revolution speed or the required gear ratio based on the required acceleration.

9. The control device according to claim 1 , wherein the control device is configured to control a required revolution speed of the drive power source based on the index.