METHODS AND SYSTEMS FOR A HYBRID VEHICLE

• US 20130297112A1
• Filed: 01/10/2013
• Published: 11/07/2013
• Est. Priority Date: 05/04/2012
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Gibson, Alex O'Connor, Yamazaki, Mark Steven, Doering, Jeffrey Allen, Reed, Dennis Craig, Banker, Adam Nathan
• Granted Patent: US 8,738,215 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60K 2006/4825 Electric machine connected or connectable to gearbox input shaft
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: B60W 20/50 Control strategies for responding to system failures, e.g. for fault diagnosis, failsafe operation or limp mode
• CPC Class Codes: B60W 2050/0075 Automatic parameter input, automatic initialising or calibrating means
• CPC Class Codes: B60W 2050/0088 Adaptive recalibration
• CPC Class Codes: B60W 2556/00 Input parameters relating to data
• CPC Class Codes: B60W 2556/10 Historical data
• CPC Class Codes: F02D 41/1402 Adaptive control
• CPC Class Codes: F02D 41/30 Controlling fuel injection F02D41/182, F02D41/24 take precedence
• CPC Class Codes: G01M 15/044 by monitoring power, e.g. by operating the engine with one of the ignitions interrupted; by using acceleration tests
• CPC Class Codes: G06N 20/00 Machine learning
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/93 Conjoint control of different elements
• CPC Class Codes: Y10S 903/946 Characterized by control of driveline clutch

Abstract

Systems and methods for learning torque estimate errors and updating torque estimation models are presented. In one example, torque errors are learned during an engine shut-down, after a disconnect clutch coupled between an engine and an electric machine has been released. An updated torque estimation model is then used to control torque during subsequent engine operation to improve drive feel and vehicle performance.

Claims

1. A method for a hybrid vehicle, comprising:

during selected engine shut-down conditions,

releasing a disconnect clutch coupled between an engine and an electric machine in a vehicle driveline; and

after disconnect clutch release, estimating torque errors based on deviations of an actual engine speed profile from a commanded engine speed profile at each of a plurality of engine speed set-points.

2. The method of claim 1, wherein the plurality of engine speed set-points are selected based on an engine torque error history.

3. The method of claim 2, wherein a number of engine speed set-points are selected based on a desired duration to engine rest during the engine shut-down conditions, the number of engine speed set-points increased as the desired duration to engine rest increases.

4. The method of claim 2, wherein a larger number of engine speed set-points are selected during engine shut-down conditions when the engine is coasting to rest, and a smaller number of engine speed set-points are selected when the engine is substantially immediately stopped.

5. The method of claim 1, further comprising, not estimating the torque errors if a fuel level in a vehicle fuel tank is lower than a threshold.

6. The method of claim 1, further comprising, in response to a driver change of mind restart request received during the estimating, discontinuing the estimating of torque errors, and expediting spinning down of the engine to rest.

7. The method of claim 1, wherein the electric machine is a crankshaft integrated starter/generator (CISG) mechanically coupling the engine to a transmission and wheels of the vehicle driveline

8. The method of claim 1, further comprising, learning the estimated torque errors as a function of corresponding engine speed set-points and updating an engine torque estimation model with the estimated torque errors.

9. The method of claim 8, wherein the estimated torque errors are further learned as a function of one or more engine actuator settings including throttle angle, spark timing, manifold air flow, and boost level.

10. The method of claim 8, further comprising, during a subsequent engine restart, applying the disconnect clutch and adjusting an engine air and fueling based on the learned torque errors to control an engine torque commanded at clutch application.

11. The method of claim 1, wherein estimating torque errors after disconnect clutch release includes estimating torque errors after disconnect clutch release and before fuel injection to the engine is deactivated.

12. A method for a hybrid vehicle driveline, comprising:

in response to idle-stop conditions,

selectively deactivating an engine and releasing a disconnect clutch coupled between the engine and a CISG;

the CISG coupled to driveline transmission and wheels; and

while the engine is decelerating,

maintaining an engine torque command; and

learning an engine torque error within an engine speed window, the error estimated based on deviation of an actual engine speed profile from an expected engine speed profile in the engine speed window, upon release of the clutch.

13. The method of claim 12, wherein the engine speed window is selected based on an engine speed set-point having a history of torque disturbances.

14. The method of claim 13, wherein the learning an engine torque error within an engine speed window is performed at each of a plurality of engine speed set-points, the plurality of engine speed set-points selected based on driveline disturbances experienced during disconnect clutch release on previous engine idle-stop conditions.

15. The method of claim 13, wherein learning an engine torque error includes, learning an engine torque over-estimation error if the actual engine speed profile in the engine speed window is higher than the expected engine speed profile, and learning an engine torque under-estimation error if the actual engine speed profile in the engine speed window is lower than the expected engine speed profile.

16. The method of claim 12, wherein releasing a disconnect clutch includes releasing a disconnect clutch while a vehicle speed is above a threshold speed.

17. The method of claim 12, further comprising, learning the engine torque error as a function of engine speed and actuator settings at the engine speed and controlling an engine torque commanded during a subsequent engine restart based on the learned engine torque error.

18. A hybrid vehicle method, comprising:

attempting to provide zero torque across a disconnect clutch upon clutch release, the clutch mechanically coupling an engine to an electric machine; and

while an engine is decelerating with the clutch released, learning errors in air and fueling required to provide the zero torque based on an engine speed profile in a window at each of a plurality of engine speed set-points.

19. The method of claim 18, wherein attempting to provide zero torque across the clutch includes determining an engine torque command that provides substantially zero torque and commanding the determined torque command immediately before the clutch release.

20. The method of claim 18, wherein a number of engine speed set-points at which the errors are learned is increased as a difference between an engine speed at which the clutch is released and engine rest increases, and wherein the errors in air and fueling are learned as a function of corresponding engine speed set-points.