Control of lock-up clutch

• US 20060122755A1
• Filed: 11/01/2005
• Published: 06/08/2006
• Est. Priority Date: 11/04/2004
• Status: Active Grant

• Current Assignee: Jatco Limited (Nissan Motor Co., Ltd.)
• Original Assignee: Jatco Limited (Nissan Motor Co., Ltd.)
• Inventors: Imamura, Tatsuya, Sekiya, Hiroshi, Saitou, Kouji, Dohi, Koji, Segawa, Satoshi
• Granted Patent: US 7,769,518 B2
• Time in Patent Office: Days
• US Class Current: 701/67
• CPC Class Codes: F16H 2061/145 for controlling slip, e.g. approaching target slip value
• CPC Class Codes: F16H 61/143 using electric control means

Abstract

A control device of a lock-up clutch of a torque converter interposed between a transmission and engine used with a vehicle, is disclosed. The control device has a sensor which detects an input rotation speed to the torque converter, a sensor which detects an output rotation speed from the torque converter, a differential pressure control device which controls the differential pressure applied to the lock-up clutch, and a controller which sets a target slip rotation speed of the torque converter; calculates a real slip rotation speed which is a difference between the detected input rotation speed and the detected output rotation speed; and performs feedback control to determine the differential pressure applied to the lock-up clutch so that the real slip rotation speed coincides with the target slip rotation speed. The controller is programmed to: set the target slip rotation speed to a first target slip rotation speed determined from a vehicle running parameter; perform feedback control so that the real slip rotation speed coincides with the first target slip rotation speed; change over the first target slip rotation speed to a second target slip rotation speed according to an error between the first target slip rotation speed and the real slip rotation speed; after changing over, and perform feedback control so that the real slip rotation speed coincides with the second target slip rotation speed; wherein the first and second target slip rotation speeds are different functions of time.

Claims

1. A control device of a lock-up clutch of a torque converter interposed between a transmission and engine used with a vehicle, comprising:

a sensor which detects an input rotation speed to the torque converter,

a sensor which detects an output rotation speed from the torque converter,

a differential pressure control device which controls the differential pressure applied to the lock-up clutch, and

a controller which sets a target slip rotation speed of the torque converter;

calculates a real slip rotation speed which is a difference between the detected input rotation speed and the detected output rotation speed; and

performs feedback control to determine the differential pressure applied to the lock-up clutch so that the real slip rotation speed coincides with the target slip rotation speed,

the controller being programmed to;

set the target slip rotation speed to a first target slip rotation speed determined from a vehicle running parameter;

perform feedback control so that the real slip rotation speed coincides with the first target slip rotation speed;

change over the first target slip rotation speed to a second target slip rotation speed according to an error between the first target slip rotation speed and the real slip rotation speed; and

after changing over, perform feedback control so that the real slip rotation speed coincides with the second target slip rotation speed;

wherein the first and second target slip rotation speeds are different functions of time.

2. The control device as defined in claim 1, wherein the controller performs open loop control of the slip rotation speed before the feedback control.

3. The control device as defined in claim 1, wherein the first target slip rotation speed and second target slip rotation speed coincide before the second target slip rotation speed becomes a predetermined slip rotation speed.

4. The control device as defined in claim 3, wherein:

the first and second target slip rotation speeds finally reach a slip rotation speed which does not vary with time, and

the predetermined slip rotation speed is a slip rotation speed which does not vary with time.

5. The control device as defined in claim 1., further comprising a sensor which detects an accelerator pedal depression amount,

wherein the controller is programmed to change over the first target slip rotation speed to the second target slip rotation speed when the detected accelerator pedal depression amount is equal to or more than a predetermined amount.

6. The control device as defined in claim 5, wherein the controller is further programmed to change over the first target slip rotation speed to the second target slip rotation speed when the detected accelerator pedal depression amount has increased or decreased to a predetermined value.

7. The control device as defined in claim 1, comprising a timer which measures an elapsed time from when the controller has changed over the first target slip rotation speed to the second target slip rotation speed,

wherein the controller is programmed to prohibit change-over of the first target slip rotation speed until the elapsed time reaches a predetermined time.

8. The control device as defined in claim 1, wherein the controller is programmed to set a time variation rate of the second target slip rotation speed to be identical to a time variation rate of the first target slip rotation speed.

9. The control device as defined in claim 1, wherein the controller is further programmed to set the absolute value of a time variation rate of the second target slip rotation speed to be equal to or less than a predetermined value.

10. The control device as defined in claim 1, further comprising a sensor which detects an accelerator pedal depression amount,

wherein the controller is programmed to set an initial value of the second target slip rotation speed according to the detected accelerator pedal depression amount when the target slip rotation speed is changed over.

11. The control device as defined in claim 1, wherein the controller is programmed to set an initial value of the second target slip rotation speed to be equal to the real slip rotation speed when the target slip rotation speed is changed over.

12. A control device of a lock-up clutch of a torque converter interposed between a transmission and engine used with a vehicle, comprising:

means for detecting an input rotation speed to the torque converter,

means for detecting an output rotation speed from the torque converter,

differential pressure control means for controlling the differential pressure applied to the lock-up clutch, and

a controller which sets a target slip rotation speed of the torque converter;

calculates a real slip rotation speed which is a difference between the detected input rotation speed and the detected output rotation speed; and

performs feedback control to determine the differential pressure applied to the lock-up clutch so that the real slip rotation speed coincides with the target slip rotation speed,

the controller comprising;

setting means for setting the target slip rotation speed to a first target slip rotation speed determined from a vehicle running parameter;

feedback control means for performing feedback control so that the real slip rotation speed coincides with the first target slip rotation speed;

switching means for switching the first target slip rotation speed to a second target slip rotation speed according to an error between the first target slip rotation speed and the real slip rotation speed; and

feedback control means for performing feedback control so that the real slip rotation speed coincides with the second target slip rotation speed after switching the first target slip rotation speed to a second target slip rotation speed;

wherein the first and second target slip rotation speeds are different functions of time.

13. A control method for use with a control device for controlling of a lock-up clutch of a torque converter interposed between a transmission and engine used with a vehicle, the control device comprising:

a sensor which detects an input rotation speed to the torque converter,

a sensor which detects an output rotation speed from the torque converter,

a differential pressure control device which controls the differential pressure applied to the lock-up clutch, and

a controller which sets a target slip rotation speed of the torque converter;

calculates a real slip rotation speed which is a difference between the detected input rotation speed and the detected output rotation speed; and

performs feedback control to determine the differential pressure applied to the lock-up clutch so that the real slip rotation speed coincides with the target slip rotation speed,

the control method comprising;

setting the target slip rotation speed to a first target slip rotation speed determined from a vehicle running parameter;

performing feedback control so that the real slip rotation speed coincides with the first target slip rotation speed;

changing over the first target slip rotation speed to a second target slip rotation speed according to an error between the first target slip rotation speed and the real slip rotation speed; and

performing feedback control so that the real slip rotation speed coincides with the second target slip rotation speed after changing over;

wherein the first and second target slip rotation speeds are different functions of time.