Lock-up-clutch control device for vehicle

Patent metadata

Field	Value
Publication number	US-9944286-B2
Application number	US-201415316244-A
Country	US
Kind code	B2
Filing date	Jul 9, 2014
Priority date	Jul 9, 2014
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

A vehicle lock-up clutch control device includes a torque converter, a fuel cutoff control unit and a lock-up release/transmission cooperative control unit. The torque converter is disposed between an engine and a continuously variable transmission. The fuel cutoff control unit is configured to prevent fuel injection to the engine while in a coasting state with the driver's foot away from the accelerator, and configured to restart the fuel injection based on a fuel recovery permission. The lock-up release/transmission cooperative control unit is configured to carry out a cooperative control of a lock-up release control for reducing the clutch engagement capacity of the lock-up clutch and a transmission control for shifting the transmission. Then, if there is an accelerator depression operation while coasting with the lock-up clutch in an engaged state, the lock-up release timing and the shift timing are offset from one another.

First claim

The invention claimed is:

1. A vehicle lock-up clutch control device comprising:
a torque converter including a lock-up clutch provided in the vehicle between an engine and a transmission;
a fuel cutoff control unit that stops fuel injection to the engine while in a coasting state by releasing a foot from an accelerator, and restarts fuel injection based on a fuel recovery permission; and
a lock-up release/transmission cooperative control unit that carries out a cooperative control of a lock-up release control that reduces a clutch engagement capacity of the lock-up clutch, and a transmission control that shifts the transmission, the lock-up release/transmission cooperative control unit offsets a lock-up release timing and a shift timing from one another if there is an accelerator depression operation while coasting with the lock-up clutch in an engaged state.

2. The vehicle lock-up clutch control device according to claim 1 , wherein
the lock-up release/transmission cooperative control unit starts a downshift control of the transmission control after the lock-up release control is started first and a lock-up release is detected, upon a lock-up request and a downshift request being outputted due to the accelerator depression operation, during coasting in the engaged state of the lock-up clutch.

3. The vehicle lock-up clutch control device according to claim 2 , wherein
the lock-up release/transmission cooperative control unit determines whether or not a transmission inertia torque will impact vehicle behavior if a shifting release and the lock-up release are simultaneously executed, and simultaneously carries out the lock-up release control and the transmission control if determined to not impact the vehicle behavior.

4. The vehicle lock-up clutch control device according to claim 2 , wherein
when the lock-up release control is started, the lock-up release/transmission cooperative control unit detects that a timing is one in which the lock-up clutch has been put in a lock-up release state with establishment of one of the following conditions:
(a) a slip rotational speed condition in which a slip rotational speed, which is the difference in a rotational speed between an engine rotation speed and a turbine rotational speed, has exceeded a first preset threshold value, or
(b) a time condition in which an elapsed time from a start of the lock-up release control has exceeded a second preset threshold value.

5. The vehicle lock-up clutch control device according to claim 4 , wherein
the lock-up release/transmission cooperative control unit prohibits fuel recovery of the engine when the lock-up release control is started, and permits fuel recovery when detecting the timing at which the lock-up clutch is put in the lock-up release state.

6. The vehicle lock-up clutch control device according to claim 1 , wherein
the lock-up release/transmission cooperative control unit determines whether or not a transmission inertia torque will impact vehicle behavior if shifting and lock-up release are simultaneously executed, and simultaneously carries out the lock-up release control and the transmission control if determined to not impact the vehicle behavior.

7. The vehicle lock-up clutch control device according to claim 6 , wherein
when the lock-up release control is started, the lock-up release/transmission cooperative control unit detects that a timing is one in which the lock-up clutch has been put in a lock-up release state with establishment of one of the following conditions:
(a) a slip rotational speed condition in which a slip rotational speed, which is the difference in a rotational speed between an engine rotation speed and a turbine rotational speed, has exceeded a first preset threshold value, or
(b) a time condition in which an elapsed time from a start of the lock-up release control has exceeded a second preset threshold value.

8. The vehicle lock-up clutch control device according to claim 7 , wherein
the lock-up release/transmission cooperative control unit prohibits fuel recovery of the engine when the lock-up release control is started, and permits fuel recovery when detecting the timing at which the lock-up clutch is put in the lock-up release state.

9. The vehicle lock-up clutch control device according to claim 1 , wherein
when the lock-up release control is started, the lock-up release/transmission cooperative control unit detects that a timing is one in which the lock-up clutch has been put in a lock-up release state with establishment of one of the following conditions:
(a) a slip rotational speed condition in which a slip rotational speed, which is the difference in a rotational speed between an engine rotation speed and a turbine rotational speed, has exceeded a first preset threshold value, or
(b) a time condition in which an elapsed time from a start of the lock-up release control has exceeded a second preset threshold value.

10. The vehicle lock-up clutch control device according to claim 9 , wherein
the lock-up release/transmission cooperative control unit prohibits fuel recovery of the engine when the lock-up release control is started, and permits fuel recovery when detecting the timing at which the lock-up clutch is put in the lock-up release state.

Assignees

• Nissan Motor

Inventors

• Kamiya Kohei

Classifications

• B60W2510/0638

  Engine speed · CPC title

• B60W2710/0627

  Fuel flow rate · CPC title

• B60W2510/1095

  Inertia · CPC title

• B60W30/18072 Primary

  Coasting · CPC title

• B60W2540/10

  Accelerator pedal position · CPC title