Launch control of a hybrid electric vehicle

• US 20090042689A1
• Filed: 08/09/2007
• Published: 02/12/2009
• Est. Priority Date: 08/09/2007
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Soliman, Ihab S., Aswani, Deepak, Silveri, Andrew J.
• Granted Patent: US 7,678,013 B2
• Time in Patent Office: Days
• US Class Current: 477/5
• CPC Class Codes: B60K 6/52 Driving a plurality of drive axles, e.g. four-wheel drive
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/486 Operating parameters
• 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 10/08 including control of electric propulsion units, e.g. motors or generators
• 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 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2710/025 Clutch slip, i.e. difference between input and output speeds
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2710/105 Output torque
• CPC Class Codes: B60W 30/18027 Drive off, accelerating from standstill
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility

Abstract

A method for controlling the launch of a vehicle having a powertrain that includes a first power path for driving a first wheel set and including an engine, a transmission having an input driveably connected to a crankshaft of the engine, a current gear, an input clutch associated with the current gear and an output connected to first wheel set, and a second power path including an electric machine for driving a second wheel set. The method includes determining a desired magnitude of wheel torque to be produced at the first wheel set, using the desired magnitude of wheel torque to be produced at the first wheel set to determine a magnitude of crankshaft torque, producing a predetermined magnitude of torque capacity at the input clutch, determining a crankshaft speed error, determining a change in magnitude of torque at the crankshaft that will reduce the crankshaft speed error, and operating the engine to produce a desired engine torque, whose magnitude is determined from the change in magnitude of torque at the crankshaft and the magnitude of desired crankshaft torque.

Claims

1. A method for controlling the launch of a vehicle having a powertrain that includes a first power path for driving a first wheel set and including an engine, a transmission having an input driveably connected to a crankshaft of the engine, a current gear, an input clutch associated with the current gear and an output connected to first wheel set, and a second power path including an electric machine for driving a second wheel set, comprising the steps of:

(a) determining a desired magnitude of wheel torque to be produced at the first wheel set;

(b) using the desired magnitude of wheel torque to be produced at the first wheel set to determine a magnitude of crankshaft torque;

(c) producing a predetermined magnitude of torque capacity at the input clutch;

(d) determining a crankshaft speed error;

(e) determining a change in magnitude of torque at the crankshaft that will reduce the crankshaft speed error; and

(f) operating the engine to produce a desired engine torque, whose magnitude is determined from the change in magnitude of torque at the crankshaft and the magnitude of desired crankshaft torque.

2. The method of claim 1 further comprising the step of using a speed of the vehicle and a position of an accelerator pedal to determine a vehicle propulsion request demand.

3. The method of claim 1, further comprising the steps of:

increasing the torque capacity of the input clutch along a ramp to a torque capacity that is equal to the torque at crankshaft; and

further increasing the torque capacity of the input clutch to a torque capacity greater than the torque at the crankshaft.

4. The method of claim 1, further comprising the steps of:

determining a desired magnitude of wheel torque to be produced at the second wheel set; and

operating the electric machine to produce the desired magnitude of torque at the second wheel set.

5. The method of claim 1, wherein step (c) further comprises the step of using the desired magnitude of wheel torque to be produced at the first wheel set and a gear ratio of the current gear to determine the magnitude of torque capacity of the input clutch.

6. The method of claim 1, wherein step (d) further comprises the steps of:

determining a desired slip across the input clutch;

using the desired slip across the input clutch and speed of the output of the input clutch to determine desired crankshaft speed; and

using a difference between the desired crankshaft speed and a speed of the crankshaft to determine the crankshaft speed error.

7. The method of claim 6 further comprising the step of using a current vehicle speed and an accelerator pedal position to determine the desired slip across the input clutch.

8. The method of claim 6 further comprising the step of using the desired input clutch slip and a speed of an output of the input clutch to determine the desired crankshaft speed.

9. The method of claim 1 wherein step (e) further comprises the step of using a controller and the crankshaft speed error to determine the desired change in torque at the crankshaft that will reduce the crankshaft speed error.

10. The method of claim 1 further comprising the steps of:

(A) determining whether a slip across the input clutch is substantially zero;

(B) determining whether a speed of the engine is greater than a speed of the output of the input clutch;

(C) determining whether a speed of the vehicle is greater than a predetermined vehicle speed; and

discontinuing performance of the method if conditions (A), (B) and (C) are present.

11. The method of claim 1 wherein step (d) further comprises the steps of:

using a vehicle speed and a position of an accelerator pedal to determine a desired input clutch slip;

using a current speed of the input clutch and the desired input clutch slip to determine a desired speed of the crankshaft;

using the current speed of the crankshaft and the desired speed of the crankshaft to determine the crankshaft speed error.

12. A method for controlling the launch of a vehicle having a powertrain that includes a first power path for driving a first wheel set and including an engine, a transmission having an input driveably connected to a crankshaft of the engine, a current gear, an input clutch associated with the current gear and an output connected to first wheel set, and a second power path including an electric machine for driving a second wheel set, comprising the steps of:

(A) using an operator demand for a desired wheel torque to determine a desired wheel torque at the first wheel set and a desired wheel torque at the second wheel set;

(B) using the desired magnitude of wheel torque to be produced at the first wheel set to determine a magnitude of desired crankshaft torque;

(C) producing a predetermined magnitude of torque capacity of the input clutch;

(D) determining a crankshaft speed error;

(E) determining a change in magnitude of torque at the crankshaft that will reduce the crankshaft speed error;

(F) operating the engine to produce a desired engine torque, whose magnitude is determined from the change in magnitude of torque at the crankshaft and the magnitude of desired crankshaft torque; and

(G) operating the electric machine to produce the desired magnitude of torque at the second wheel set.

13. The method of claim 12, further comprises the steps of:

increasing the torque capacity of the input clutch along a ramp to a torque capacity that is equal to the torque at the crankshaft; and

further increasing the torque capacity of the input clutch to a torque capacity greater than the torque at the crankshaft.

14. The method of claim 12, wherein step (C) further comprises the step of using the desired wheel torque at the first wheel set and a gear ratio of the current gear to determine the magnitude of torque capacity of the input clutch.

15. The method of claim 12, wherein step (D) further comprises the steps of:

determining a desired slip across the input clutch;

using the desired slip across the input clutch and a speed of an output of the input clutch to determine a desired crankshaft speed; and

using a difference between the desired crankshaft speed and a speed of the crankshaft to determine the crankshaft speed error.

16. The method of claim 15 further comprising the step of using a current vehicle speed and an accelerator pedal position to determine the desired slip across the input clutch.

17. The method of claim 15 further comprising the step of using the desired input clutch slip and a speed of an output of the input clutch to determine the desired crankshaft speed.

18. The method of claim 12 wherein step (E) further comprises the steps of using a controller and the crankshaft speed error to determine the desired change in torque at the transmission input that will reduce the crankshaft speed error.

19. The method of claim 12 wherein step (D) further comprises the steps of:

using a vehicle speed and a position of an accelerator pedal to determine a desired input clutch slip;

using a current speed of the input clutch and the desired input clutch slip to determine a desired speed of the crankshaft;

using the current speed of the crankshaft and the desired speed of the crankshaft to determine the crankshaft speed error.

20. A system for controlling a vehicle launch condition comprising:

the first wheel set driveably connected to an engine that includes a crankshaft;

a transmission including an input driveably connected to the crankshaft and an output, the transmission being able to operate in a current gear;

an input clutch for alternately closing and opening a drive connection between the crankshaft and transmission input; and

an electric machine driveably connected to the second wheel set;

a controller configured to determine a desired magnitude of wheel torque to be produced at the first wheel set and the second wheel set, determine a magnitude of crankshaft torque, produce a predetermined magnitude of torque capacity of the input clutch, determine a crankshaft speed error, determine a change in magnitude of torque at the crankshaft that will reduce the crankshaft speed error, operate the engine to produce a desired engine torque, whose magnitude is determined from the change in magnitude of torque at the crankshaft and the magnitude of desired crankshaft torque, and operating the electric machine to produce the desired magnitude of torque at the second wheel set

21. The system of claim 20 further including a second wheel set, and wherein the controller is configured further to determine a desired magnitude of wheel torque to be produced at the second wheel set, and operating the electric machine to produce the desired magnitude of torque at the second wheel set.

22. The system of claim 20, wherein the controller is further configured to:

increase the torque capacity of the input clutch along a ramp to a torque capacity that is equal to the torque at the crankshaft; and

further increase the torque capacity of the input clutch to a torque capacity greater than the torque at the crankshaft.

23. The system of claim 20, wherein the controller is further configured to use the desired magnitude of wheel torque to be produced at the first wheel set and a gear ratio of the current gear to determine the magnitude of torque capacity of the input clutch.

24. The system of claim 20, wherein the controller is further configured to:

determine a desired slip across the input clutch;

use the desired slip across the input clutch and speed of the an output of the input clutch to determine desired crankshaft speed; and

use a difference between the desired crankshaft speed and a speed of the crankshaft to determine the crankshaft speed error.

25. The system of claim 20 wherein the controller is further configured to use the crankshaft speed error to determine the desired change in torque at the crankshaft that will reduce the crankshaft speed error.