Slip control system for torque converter

• US 6,217,481 B1
• Filed: 11/03/1999
• Issued: 04/17/2001
• Est. Priority Date: 11/06/1998
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Watanabe, Akira, Adachi, Kazutaka
• Primary Examiner(s): Estremsky, Sherry
• Assistant Examiner(s): LEWIS, TISHA D
• Application Number:
  US09/433,381
• Time in Patent Office: 531 Days
• Field of Search: 477/169, 477/62, 477/63, 477/64, 477/176, 192/3.28, 192/3.29, 192/3.3, 192/3.31
• US Class Current: 477/169
• 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 slip control system for a torque converter with a lockup clutch comprises a controller that outputs a slip control signal to a slip control actuator of the lockup clutch to adjust an actual slip rotation speed of the torque converter at a target slip rotation speed. The controller is coupled to sensors for detecting information indicative of a condition of a drive system including the torque converter. The controller decides an operating state of the torque converter at time when the slip control is started, and selects one of initial valves for a slip command signal corresponding to the slip control signal according to the decided operating state of the torque converter at the start of the slip control. This arrangement functions to prevent troubles including shocks due to shortage of slippage in the torque converter and generation of radial slippage of the torque convert from generating at a time staring the slip control.

Claims

1. A slip control system for a torque converter with a lockup clutch, the slip control system controlling an actual slip rotation speed between input and output elements of the torque converter at a target slip rotation speed, the torque converter being connected to an engine and a transmission of a vehicle, the slip control system comprising:

a vehicle operating condition detector detecting operating condition of the vehicle;

an actuator controlling a lockup clutch engagement pressure of the lockup clutch according to a control signal to adjust the actual slip rotation speed at the target slip rotation speed; and

a controller connected to said vehicle operating condition detector and said actuator, said controller being arranged to decide an operating state of the torque converter when the slip control is started, to decide an initial value of a slip rotation speed command value according to the operating state of the torque converter at the start of the slip control, to calculate the slip rotation speed command value on the basis of the detected vehicle operating condition, and to output the control signal corresponding to the slip rotation speed command value to said actuator;

wherein the control signal is selected from a first value by which the actual slip rotation speed becomes greater than or equal to a limit of a range wherein shocks caused by engaging the lockup clutch is negligible, and a second value by which the actual slip rotation speed becomes zero, the initial value of the slip rotation speed command value being obtained by executing inverse calculation steps of the calculation steps on the basis of the determined control signal.

2. A slip control system as claimed in claim 1, wherein when the slip control is started at a converter state where the actual slip rotation speed is not limited by the lockup clutch, the initial value of the slip rotation speed command value is set at a value by which the actual slip rotation speed becomes greater than a lower limit of a range wherein shocks caused by engaging the lockup clutch is negligible.

3. A slip control system as claimed in claim 1, wherein when the slip control is started at a converter state where the actual slip rotation speed is not limited by the lockup clutch, the initial value of the slip rotation speed command value is set at a value by which the actual slip rotation speed becomes equal to a lower limit of a range wherein shocks caused by engaging the lockup clutch is negligible.

4. A slip control system as claimed in claim 1, wherein when the slip control is started at a lockup state where the actual slip rotation speed is kept at zero, the initial value of the slip rotation speed command value is set at a value by which the actual slip rotation speed becomes zero.

5. A slip control system as claimed in claim 1, wherein said vehicle operating condition detector includes a throttle opening sensor, a converter input element rotation speed sensor, a converter output element rotation speed sensor, a converter oil temperature sensor, a transmission output rotation speed sensor, and a transmission ratio calculating section.

6. A slip control system for a torque converter with a lockup clutch, the slip control system controlling an actual slip rotation speed between input and output elements of the torque converter at a target slip rotation speed, the torque converter being connected to an engine and a transmission of a vehicle, the slip control system comprising:

a vehicle operating condition detector detecting operating condition of the vehicle;

an actuator controlling a lockup clutch engagement pressure of the lockup clutch according to a control signal to adjust the actual slip rotation speed at the target slip rotation speed; and

a controller connected to said vehicle operating condition detector and said actuator, said controller being arranged to decide an operating state of the torque converter when the slip control is started, to decide an initial value of a slip rotation speed command value according to the operating state of the torque converter at the start of the slip control, to calculate the slip rotation speed command value on the basis of the detected vehicle operating condition, and to output the control signal corresponding to the slip rotation speed command value to said actuator;

wherein a command value of the lockup engagement pressure is selected from a first value by which the actual slip rotation speed becomes greater than a lower limit of a range wherein shocks caused by engaging the lockup clutch is negligible, and a second value by which the actual slip rotation speed becomes zero, the initial value of the slip rotation speed command value being obtained by executing inverse calculation steps of the calculation steps on the basis of the determined lockup engagement pressure command value.

7. A slip control system for a torque converter with a lockup clutch, the slip control system controlling an actual slip rotation speed between input and output elements of the torque converter at a target slip rotation speed, the torque converter beings connected to an engine and a transmission of a vehicle, the slip control system comprising:

a vehicle operating condition detector detecting operating condition of the vehicle;

an actuator controlling a lockup clutch engagement pressure of the lockup clutch according to a control signal to adjust the actual slip rotation speed at the target slip rotation speed; and

a controller connected to said vehicle operating condition detector and said actuator, said controller being arranged to decide an operating state of the torque converter when the slip control is started, to decide an initial value of a slip rotation speed command value according to the operating state of the torque converter at the start of the slip control, to calculate the slip rotation speed command value on the basis of the detected vehicle operating condition, and to output the control signal corresponding to the slip rotation speed command value to said actuator;

wherein a target value of a lockup clutch engagement capacity is selected from a first value by which the actual slip rotation speed becomes greater than or equal to a lower limit of a range wherein shocks caused by engaging the lockup clutch is negligible, and a second value by which the actual slip rotation speed be comes zero, the initial value of the slip rotation speed command value being obtained by executing inverse calculation steps of the calculation steps on the basis of the determined target value of the lockup clutch engagement capacity.

8. A slip control system for a torque converter with a lockup clutch, the slip control system controlling an actual slip rotation speed between input and output elements of the torque converter at a target slip rotation speed, the torque converter being connected to an engine and a transmission of a vehicle, the slip control system comprising:

a vehicle operating condition detector detecting operating condition of the vehicle;

an actuator controlling a lockup clutch engagement pressure of the lockup clutch according to a control signal to adjust the actual slip rotation speed at the target slip rotation speed; and

a controller connected to said vehicle operating condition detector and said actuator, said controller being arranged to decide an operating state of the torque converter when the slip control is started, to decide an initial value of a slip rotation speed command value according to the operating state of the torque converter at the start of the slip control, to calculate the slip rotation speed command value on the basis of the detected vehicle operating condition, to obtain the control signal by executing calculating steps on the basis of the slip rotation speed command value, the vehicle operating condition and maps indicative of characteristics of the torque converter and the engine, and to output the control signal to said actuator;

wherein the control signal is selected from a first value by which the actual slip rotation speed becomes greater than a lower limit of a range wherein shocks caused by engaging the lockup clutch is negligible, and a second value by which the actual slip rotation speed becomes zero, the initial value of the slip rotation speed command value being obtained by executing inverse calculation steps of the calculation steps on the basis of the determined control signal.

9. A slip control system for a torque converter with a lockup clutch, the slip control system controlling an actual slip rotation speed between input and output elements of the torque converter at a target slip rotation speed, the torque converter being connected to an engine and a transmission of a vehicle, the slip control system comprising:

a vehicle operating condition detector detecting operating condition of the vehicle;

an actuator controlling a lockup clutch engagement pressure of the lockup clutch according to a control signal to adjust the actual slip rotation speed at the target slip rotation speed; and

a controller connected to said vehicle operating condition detector and said actuator, said controller being arranged to decide an operating state of the torque converter when the slip control is started, to decide an initial value of a slip rotation speed command value according to the operating state of the torque converter at the start of the slip control, to calculate the slip rotation speed command value on the basis of the detected vehicle operating condition, to obtain the control signal by executing calculating steps on the basis of the slip rotation speed command value, the vehicle operating condition and maps indicative of characteristics of the torque converter and the engine, and to output the control signal to said actuator;

wherein a command value of the lockup engagement pressure is selected from a first value by which the actual slip rotation speed becomes greater than a lower limit of a range wherein shocks caused by engaging the lockup clutch is negligible, and a second value by which the actual slip rotation speed becomes zero, the initial value of the slip rotation speed command value being obtained by executing inverse calculation steps of the calculation steps on the basis of the determined lockup engagement pressure command value.

10. A slip control system for a torque converter with a lockup clutch, the slip control system controlling an actual slip rotation speed between input and output elements of the torque converter at a target slip rotation speed, the torque converter being connected to an engine and a transmission of a vehicle, the slip control system comprising:

a vehicle operating condition detector detecting operating condition of the vehicle;

an actuator controlling a lockup clutch engagement pressure of the lockup clutch according to a control signal to adjust the actual slip rotation speed at the target slip rotation speed; and

a controller connected to said vehicle operating condition detector and said actuator, said controller being arranged to decide an operating state of the torque converter when the slip control is started, to decide an initial value of a slip rotation speed command value according to the operating state of the torque converter at the start of the slip control, to calculate the slip rotation speed command value on the basis of the detected vehicle operating condition, to obtain the control signal by executing calculating steps on the basis of the slip rotation speed command value, the vehicle operating condition and maps indicative of characteristics of the torque converter and the engine, and to output the control signal to said actuator;

wherein a target value of a lockup clutch engagement capacity is selected from a first value by which the actual slip rotation speed becomes greater than or equal to a lower limit of a range wherein shocks caused by engaging the lockup clutch is negligible, and a second value by which the actual slip rotation speed becomes zero, the initial value of the slip rotation speed command value being obtained by executing inverse calculation steps of the calculation steps on the basis of the determined target value of the lockup clutch engagement capacity.