Granted Patent B2

US 7,510,505 · App. 11/467,960 · Granted Mar 31, 2009

Abstract

Claims (28)

1. A method of releasing a lockup clutch for a fluid coupling assembly disposed between an engine and a transmission during a negative engine torque mode of operation, the method comprising:

commanding the engine to operate at a target engine torque value wherein said target engine torque value is one of a zero and a near zero value;

holding the engine at said target engine torque value; and

releasing or disengaging the lockup clutch when the engine is operating at said target engine torque value.

2. The method of claim 1 , further comprising determining a current engine torque value prior to commanding the engine to operate at said target engine torque value.

3. The method of claim 1 , wherein said near zero value is one of negative and positive.

4. The method of claim 1 , further comprising determining if abort conditions are present after commanding the engine to operate at a target engine torque value.

5. The method of claim 4 , further comprising commanding the engine to ramp or increase said target engine torque value toward a driver command torque value if at least one of said abort conditions are present.

6. The method of claim 1 , wherein the fluid coupling is a torque converter.

7. A powertrain comprising:

an engine;

a transmission;

a fluid coupling assembly disposed between said engine and said transmission and having a lockup clutch operable to substantially lock said engine with said transmission for unitary rotation; and

at least one controller sufficiently configured to: command said engine to a target engine torque value during engine braking conditions, wherein said target engine torque value is one of a zero and a near zero value; hold said engine at said target engine torque value; and release said lockup clutch when said engine is operating at said target engine torque value.

8. The powertrain of claim 7 , wherein said engine is one of a spark-ignited and compression-ignited internal combustion engine.

9. The powertrain of claim 7 , wherein said transmission is an automatically shiftable transmission.

10. The powertrain of claim 7 , wherein said fluid coupling assembly is a torque converter.

11. The powertrain of claim 7 , wherein said at least one controller includes a transmission controller operable to communicate command signals to said transmission and an engine controller operable to communicate command signals to said engine.

12. The powertrain of claim 11 , wherein said transmission controller and said engine controller communicate with each other over a data link.

13. The powertrain of claim 7 , wherein said near zero value is one of negative and positive.

14. A method of releasing a lockup clutch for a torque converter assembly disposed between an engine and an automatically shiftable transmission during a negative engine torque mode of operation, the method comprising:

determining a current engine torque value prior to commanding the engine to ramp to a target engine torque value;

commanding the engine to operate at a target engine torque value wherein said target engine torque value is one of a zero and a near zero value;

holding the engine at said target engine torque value

determining if abort conditions are present; and

releasing the lockup clutch when the engine is operating at said target engine torque value if said abort conditions are not present.

15. The method of claim 14 , further comprising commanding the engine to ramp or increase said target engine torque value toward a driver command torque value if said abort conditions are present.

16. The method of claim 14 , wherein said near zero value is one of negative and positive.

Assignments (14)