Lock-up clutch control method for vehicle, and lock-up clutch control device for vehicle

Patent metadata

Field	Value
Publication number	US-10801614-B2
Application number	US-201716633629-A
Country	US
Kind code	B2
Filing date	Aug 16, 2017
Priority date	Aug 16, 2017
Publication date	Oct 13, 2020
Grant date	Oct 13, 2020

Abstract

A vehicle lock-up clutch control method is performed in which an output of an engine is transmitted to an automatic transmission via a torque converter having a lock-up clutch. The method includes controlling a transmission torque capacity of the lock-up clutch such that a slip rotation speed of the lock-up clutch becomes zero after the lockup clutch is brought into a non-engaged state immediately after starting an accelerator operation, and when the accelerator operation is carried out during a fuel cut of the engine or in a state in which a road load and a driving force of the vehicle are balanced, and after completion of a downshift when the automatic transmission is downshifted while executing a slip control of the lock-up clutch from the non-engaged state to an engaged state during the accelerator operation.

First claim

The invention claimed is:

1. A vehicle lock-up clutch control method in which an output of an engine is transmitted to an automatic transmission via a torque converter having a lock-up clutch, the vehicle lock-up clutch control method comprising:
controlling a transmission torque capacity of the lock-up clutch such that a slip rotation speed of the lock-up clutch becomes zero after the lockup clutch is brought into a non-engaged state immediately after starting an accelerator operation that is carried out during a fuel cut of the engine or in a state in which a road load and a driving force of the vehicle are balanced, and after completion of a downshift when the automatic transmission is downshifted while executing a slip control of the lock-up clutch from the non-engaged state to an engaged state during the accelerator operation.

2. The vehicle lock-up clutch control method according to claim 1 , wherein
the transmission torque capacity is controlled such that the change gradient of the engine rotation speed becomes larger than a prescribed gradient during the slip control.

3. The vehicle lock-up clutch control method according to claim 1 , wherein
the transmission torque capacity in the engaged state of the lock-up clutch is changed in accordance with a presence or an absence of the downshift.

4. The vehicle lock-up clutch control method according to claim 1 , wherein
the transmission torque capacity during the slip control is calculated in accordance with a target slip rotation speed or a target engine rotation speed of the lock-up clutch, and the target slip rotation speed or the target engine rotation speed is changed in accordance with a presence or an absence of the downshift.

5. The vehicle lock-up clutch control method according to claim 4 , wherein
the target slip rotation speed or the target engine rotation speed is set to zero at a time of the completion of the downshift in a case that the automatic transmission is downshifted.

6. The vehicle lock-up clutch control method according to claim 1 , wherein
the transmission torque capacity during the slip control is calculated in accordance with an accelerator opening degree, and the transmission torque capacity is changed in accordance with a presence or an absence of the downshift.

7. The vehicle lock-up clutch control method according to claim 6 , wherein
a command value of the transmission torque capacity is set such that the slip rotation speed of the lock-up clutch becomes zero at a time of the completion of the downshift in a case that the automatic transmission is downshifted.

8. A vehicle lock-up clutch control device, comprising
a torque converter that has a lock-up clutch and that transmits an output of an engine to an automatic transmission, and
a controller that controls a transmission torque capacity of the lock-up clutch,
wherein
the controller controls the transmission torque capacity such that the slip rotation speed of the lock-up clutch becomes zero after the lockup clutch is brought into a non-engaged state immediately after starting an accelerator operation that is carried out during a fuel cut of the engine or in a state in which a road load and a driving force of the vehicle are balanced, and after completion of a downshift when the automatic transmission is downshifted while executing a slip control of the lock-up clutch from the non-engaged state to an engaged state during the accelerator operation.

Assignees

• Nissan Motor

Inventors

• Tohta Yuzuru

Classifications

• F16H59/18

  dependent on the position of the accelerator pedal · CPC title

• F16H2059/366

  Engine or motor speed · CPC title

• F16H59/34

  dependent on fuel feed · CPC title

• F16H61/143 Primary

  using electric control means · CPC title

• F16H2061/145

  for controlling slip, e.g. approaching target slip value · CPC title