Control device and control method for continuously variable transmission

Patent metadata

Field	Value
Publication number	US-2018017156-A1
Application number	US-201615546199-A
Country	US
Kind code	A1
Filing date	Mar 15, 2016
Priority date	Mar 27, 2015
Publication date	Jan 18, 2018
Grant date	—

Abstract

A speed change ECU for a CVT sets a target input rotational speed (Nin*) such that the speed ratio of the CVT is varied stepwise a plurality of times consecutively to the downshift side in response to an operation to depress a brake pedal by a driver, and sets the target input rotational speed (Nin*) such that the time interval between consecutive downshifts becomes longer as the number of times of execution of downshifts is increased on the basis of intershifting times (tint(1)), (tint(2)), . . . while downshifts in which the speed ratio is varied stepwise are executed consecutively.

First claim

1 - 8 . (canceled)

9 . A control device for a continuously variable transmission mounted on a vehicle, the control device controlling the continuously variable transmission such that an input rotational speed of the continuously variable transmission coincides with a target input rotational speed, the control device comprising:
an electronic control unit that:
sets the target input rotational speed such that a speed ratio of the continuously variable transmission is varied stepwise a plurality of times consecutively to a downshift side in response to an operation to depress a brake pedal by a driver, and sets the target input rotational speed such that an interval between consecutive downshifts becomes longer as the number of times of execution of downshifts is increased while downshifts in which the speed ratio is varied stepwise are executed consecutively.

10 . The control device for a continuously variable transmission according to claim 9 , wherein the electronic control unit acquires a required braking amount required by the driver when he/she depresses the brake pedal, and sets the target input rotational speed such that the interval between consecutive downshifts is shorter as the required braking amount is larger.

11 . The control device for a continuously variable transmission according to claim 9 , wherein
the electronic control unit sets the target input rotational speed such that a rise gradient at which the input rotational speed becomes higher from a timing to start a downshift becomes smaller as the number of times of execution of downshifts is increased.

12 . The control device for a continuously variable transmission according to claim 9 , further comprising:
a mode select switch that allows a driver to select one of a continuously variable speed change mode, in which the speed ratio is changed continuously, and a stepwise speed change mode, in which the speed ratio is changed stepwise at least in response to an operation to depress the brake pedal.

13 . The control device for a continuously variable transmission according to claim 10 , wherein
the electronic control unit sets the target input rotational speed such that a rise gradient at which the input rotational speed becomes higher from a timing to start a downshift becomes smaller as the number of times of execution of downshifts is increased.

14 . The control device for a continuously variable transmission according to claim 10 , further comprising:
a mode select switch that allows a driver to select one of a continuously variable speed change mode, in which the speed ratio is changed continuously, and a stepwise speed change mode, in which the speed ratio is changed stepwise at least in response to an operation to depress the brake pedal.

15 . The control device for a continuously variable transmission according to claim 11 , wherein
the electronic control unit sets the target input rotational speed such that the rise gradient in each downshift is larger as a required braking amount required by the driver when he/she depresses the brake pedal is larger.

16 . The control device for a continuously variable transmission according to claim 11 , further comprising:
a mode select switch that allows a driver to select one of a continuously variable speed change mode, in which the speed ratio is changed continuously, and a stepwise speed change mode, in which the speed ratio is changed stepwise at least in response to an operation to depress the brake pedal.

17 . The control device for a continuously variable transmission according to claim 13 , wherein
the electronic control unit sets the target input rotational speed such that the rise gradient in each downshift is larger as a required braking amount required by the driver when he/she depresses the brake pedal is larger.

18 . The control device for a continuously variable transmission according to claim 17 , wherein:
the control device has
a target post-shifting rotational speed map that prescribes, for each of a plurality of downshifts, a relationship between the required braking amount and a target post-shifting rotational speed which is a target value for the input rotational speed after the speed ratio is varied stepwise to the downshift side,
a rise gradient map that prescribes, for each of a plurality of downshifts, a relationship between the required braking amount and a target rise gradient in each downshift, and
a shifting interval map that prescribes, for each of a plurality of downshifts, a relationship between the required braking amount and the interval between downshifts; and
wherein the electronic control unit acquires the target post-shifting rotational speed corresponding to the required braking amount for each downshift from the target post-shifting rotational speed map, acquires the target rise gradient corresponding to the required braking amount for each downshift from the rise gradient map, and acquires the interval between downshifts corresponding to the required braking amount for each downshift from the shifting interval map when the brake pedal is depressed by the driver, and sets the target input rotational speed such that the input rotational speed is raised to the target post-shifting rotational speed corresponding to the downshift at the target rise gradient corresponding to the downshift when the timing to start a downshift corresponding to the interval comes.

19 . The control device for a continuously variable transmission according to claim 18 , wherein:
the target post-shifting rotational speed map is prepared such that the target post-shifting rotational speed becomes higher as the number of times of execution of downshifts is increased, and such that the target post-shifting rotational speed in each downshift is higher as the required braking amount is larger; and in the case where a difference between the target post-shifting rotational speed corresponding to a first downshift and the input rotational speed at a time when the driver depresses the brake pedal is smaller than a predetermined value, the electronic control unit sets the target input rotational speed using the target post-shifting rotational speed corresponding to a downshift, the difference for which is equal to or more than the predetermined value, and subsequent downshifts.

20 . The control device for a continuously variable transmission according to claim 19 , further comprising:
a mode select switch that allows a driver to select one of a continuously variable speed change mode, in which the speed ratio is changed continuously, and a stepwise speed change mode, in which the speed ratio is changed stepwise at least in response to an operation to depress the brake pedal.

21 . The control device for a continuously variable transmission according to claim 15 , wherein:
the control device has
a target post-shifting rotational speed map that prescribes, for each of a plurality of downshifts, a relationship between the required braking amount and a target post-shifting rotational speed which is a target value for the input rotational speed after the speed ratio is varied stepwise to the downshift side,
a rise gradient map that prescribes, for each of a plurality of downshifts, a relationship between the required braking amount and a target rise gradient in each downshift, and
a shifting interval map that prescribes, for each of a plurality of downshifts, a relationship between the required braking amount and the interval between downshifts; and
wherein the electronic control unit acquires the target post-shifting rotational speed corresponding to the required braking amount for each dow

Assignees

• Aisin Aw Co

Inventors

• Kato Masachika
• Kikkawa Akihiro
• Kurita Kiyoshi

Classifications

• F16H59/54 Primary

  dependent on signals from the brakes, e.g. parking brakes · CPC title

• F16H61/24

  Providing feel, e.g. to enable selection · CPC title

• F16H61/66272

  characterised by means for controlling the torque transmitting capability of the gearing · CPC title

• F16H59/044

  consisting of electrical switches or sensors · CPC title

• F16H61/66

  specially adapted for continuously variable gearings (control of exclusively fluid gearing F16H61/38) · CPC title