A SYSTEM AND METHOD FOR CONTROLLING DRIVETRAIN TORQUE AND HILL HOLDING OF A HYBRID VEHICLE

• US 20050143877A1
• Filed: 03/10/2005
• Published: 06/30/2005
• Est. Priority Date: 07/23/2003
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Sureshbabu, Suresh, Cikanek, Susan
• Granted Patent: US 8,396,618 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60L 15/2063 for creeping
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/32 Driving direction
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 2240/461 Speed
• CPC Class Codes: B60L 2240/463 Torque
• CPC Class Codes: B60L 2240/465 Slip
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60L 2240/507 Operating parameters
• CPC Class Codes: B60L 2240/642 Slope of road
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 2260/22 Standstill, e.g. zero speed
• CPC Class Codes: B60L 2260/26 Transition between different drive modes
• CPC Class Codes: B60L 3/0076 relating to braking
• CPC Class Codes: B60L 3/106 for maintaining or recovering the adhesion of the drive wheels
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• 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 10/18 : including control of braking systems
• 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 20/12 : using control strategies taking into account route information estimation or calculation of non-directly measurable driving parameters B60W40/00
• CPC Class Codes: B60W 2050/0052 : Filtering, filters
• CPC Class Codes: B60W 2510/0283 : Clutch input shaft speed
• CPC Class Codes: B60W 2510/0291 : Clutch temperature
• CPC Class Codes: B60W 2510/1015 : Input shaft speed, e.g. turbine speed
• CPC Class Codes: B60W 2520/10 : Longitudinal speed
• CPC Class Codes: B60W 2540/10 : Accelerator pedal position
• CPC Class Codes: B60W 2540/12 : Brake pedal position
• CPC Class Codes: B60W 2540/16 : Ratio selector position
• CPC Class Codes: B60W 2552/15 : Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 30/18063 : Creeping
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/16 : Information or communication technologies improving the operation of electric vehicles

Abstract

A system and method for controlling torque in a hybrid electric vehicle. The system provides a regenerative braking torque with an electrical machine when a level of braking torque indicated by actuation of a brake control device exceeds a level of traction torque indicated by actuation of an acceleration control device. The regenerative braking torque is supplemented by a friction braking system when the braking torque requested by a vehicle operator exceeds a maximum regenerative braking capacity of the electrical machine.

Claims

1. A system for controlling drivetrain torque in a hybrid electric vehicle having primary and secondary power sources, the system comprising:

a power transfer unit adapted to drive vehicle traction wheels;

an electrical machine selectively coupled to the power transfer unit, the electrical machine being adapted to provide traction torque to the traction wheels when powered by the primary or secondary power sources and impose a regenerative braking torque on the traction wheels when not powered by the primary or secondary power sources;

an acceleration control device for providing a first signal indicative of a level of traction torque requested by a vehicle operator; and

a brake control device for providing a second signal indicative of a level of braking torque requested by the vehicle operator;

wherein regenerative braking torque is provided by the electrical machine when engagement of a gear of the power transfer unit is requested by the vehicle operator, the speed of the hybrid electric vehicle is less than a creep speed value, and the level of braking torque indicated by the second signal exceeds the level of traction torque indicated by the first signal.

2. The system of claim 1 wherein the hybrid electric vehicle further comprises a friction braking system for inhibiting rotation of the traction wheels and wherein the regenerative braking torque is supplemented by the friction braking system when the braking torque requested by the vehicle operator exceeds a maximum regenerative braking capacity of the electrical machine.

3. The system of claim 1 wherein the primary power source is an internal combustion engine.

4. The system of claim 3 wherein the internal combustion engine is turned off when engagement of a gear of the power transfer unit is requested by the vehicle operator, the speed of the hybrid electric vehicle is less than the creep speed value, and the accelerator and brake control devices are not actuated.

5. The system of claim 1 wherein the friction braking system is actuated to inhibit rollback of the hybrid electric vehicle when the vehicle operator requests engagement of a gear of the power transfer unit, the speed of the hybrid electric vehicle is less than the creep speed value, and the traction wheels are rotating in a first direction that is opposite a direction associated with the gear requested by the vehicle operator.

6. A method of controlling torque in a hybrid electric vehicle drivetrain having an engine and an electrical machine adapted to drive a vehicle wheel, the method comprising:

determining whether a vehicle rollback condition exists;

actuating a friction brake system to inhibit rollback if the vehicle rollback condition exists;

determining a desired braking torque and a desired traction torque; and

providing a regenerative braking torque with the electrical machine when the desired braking torque exceeds the desired traction torque.

7. The method of claim 6 wherein the engine is turned off if accelerator and brake control devices are not actuated.

8. The method of claim 6 wherein the step of providing regenerative braking torque further comprises turning off the engine if a brake control device is actuated and an acceleration control device is not actuated.

9. The method of claim 6 wherein the regenerative braking torque is supplemented with braking torque provided by the friction braking system when the desired braking torque exceeds a maximum regenerative braking capacity of the electrical machine.

10. A method of controlling torque in a drivetrain of a hybrid electric vehicle, the method comprising:

determining whether a drivetrain gear is selected by an operator;

determining whether a speed of the hybrid electric vehicle is less than a creep speed value when the gear is selected;

determining whether a vehicle rollback condition exists when the speed of the hybrid electric vehicle is less than the creep speed value;

actuating a friction braking system to inhibit rollback when the vehicle rollback condition exists;

determining a desired braking torque and a desired traction torque; and

providing a braking torque with an electrical machine to capture energy when the desired braking torque exceeds the desired traction torque.

11. The method of claim 10 wherein the desired braking torque is based on actuation of a brake control device.

12. The method of claim 10 wherein the desired traction torque is based on actuation of an acceleration control device.

13. The method of claim 10 wherein the method further comprises providing braking torque with the friction braking system when the desired braking torque exceeds a maximum regenerative braking capacity of the electrical machine.

14. The method of claim 13 wherein the maximum regenerative braking capacity is based on a gear ratio of the electrical machine and an electrical machine engagement factor.

15. The method of claim 13 wherein the amount of braking torque provided by the friction braking system is not greater than the difference between the desired braking torque and the maximum regenerative braking capacity of the electrical machine.

16. The method of claim 10 wherein the drivetrain includes an engine and the method further comprises the step of applying traction torque with the engine when the desired braking torque is less than the desired traction torque.

17. The method of claim 10 wherein the hybrid electric vehicle includes an engine, a brake control device, and an acceleration control device, wherein the desired braking torque and desired traction torque are based on actuation of the brake and acceleration control devices, respectively, and wherein the method further comprises the step of turning off the engine if the brake control device and acceleration control device are not actuated.

18. The method of claim 17 wherein the engine is turned off if the brake control device is actuated and the acceleration control device is not actuated.

19. The method of claim 17 further comprising the step of running the engine if the brake control device is not actuated and the acceleration control device is actuated.

20. The method of claim 17 further comprising the step of running the engine if the brake control device and the acceleration control device are actuated and the desired traction torque exceeds the desired braking torque.