Method of operating a vehicle utilizing regenerative braking

• US 8,155,814 B2
• Filed: 10/24/2008
• Issued: 04/10/2012
• Est. Priority Date: 11/03/2007
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG, Daimler AG (Mercedes-Benz Group AG), Chrysler Group LLC (Stellantis NV)
• Original Assignee: Bayerische Motoren Werke AG, GM Global Technology Operations LLC (General Motors Company), Daimler AG (Mercedes-Benz Group AG), Chrysler LLC (Stellantis NV)
• Inventors: Tamai, Goro, Miller, Thomas S., Thompson, Scott J, Kaminsky, Lawrence A., Sah, Jy-Jen F., Heap, Anthony H.
• Primary Examiner(s): Trammell, James
• Assistant Examiner(s): Do, Truc M
• Application Number:
  US12/257,447
• Publication Number:
  US 20090118886A1
• Time in Patent Office: 1,264 Days
• Field of Search: 701/22, 701/51, 701/54, 477/181
• US Class Current: 701/22
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 2220/18 Reluctance machines
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 2240/445 Temperature
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60L 2240/662 Temperature
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 58/24 for controlling the temperature of batteries
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• 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 10/184 with wheel brakes
• 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 20/11 : using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance utilising navigation and traffic information in the control strategy B60W20/12
• CPC Class Codes: B60W 20/13 : in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 2050/0006 : Digital architecture hierarchy
• CPC Class Codes: B60W 2510/0638 : Engine speed
• CPC Class Codes: B60W 2510/0657 : Engine torque
• CPC Class Codes: B60W 2510/0671 : Engine manifold pressure
• CPC Class Codes: B60W 2510/0676 : Engine temperature
• CPC Class Codes: B60W 2510/1015 : Input shaft speed, e.g. turbine speed
• CPC Class Codes: B60W 2510/104 : Output speed
• CPC Class Codes: B60W 2510/244 : Charge state
• CPC Class Codes: B60W 2510/246 : Temperature
• 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 2555/20 : Ambient conditions, e.g. wind or rain
• CPC Class Codes: B60W 2710/0605 : Throttle position
• CPC Class Codes: B60W 2710/0616 : Position of fuel or air injector
• CPC Class Codes: B60W 2710/083 : Torque
• CPC Class Codes: B60W 30/18109 : Braking
• CPC Class Codes: B60W 30/18127 : Regenerative braking
• 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 vehicle includes a powertrain system and a friction braking system, the powertrain system including a hybrid transmission operative in one of a fixed gear operating range state and a continuously variable operating range state to transmit torque between an input member and a torque machine and an output member coupled to a driveline. A method for operating the vehicle includes monitoring operator inputs to an accelerator pedal and a brake pedal, monitoring vehicle speed, maintaining the transmission in a present operating range state subsequent to the operator disengaging the accelerator pedal absent the operator engaging the brake pedal, transitioning the transmission device to a continuously variable operating range state subsequent to the operator disengaging the accelerator pedal and the operator engaging the brake pedal, executing regenerative braking by controlling the torque machine to react torque through the transmission to brake the vehicle through the driveline when the operator engages the brake pedal and the speed of the vehicle is greater than a first threshold, and disabling the regenerative braking when the operator disengages the brake pedal and subsequently reengages the brake pedal when the speed of vehicle is less than a first threshold and greater less than a second threshold.

Claims

1. Method for operating a vehicle including a powertrain system and a friction braking system, the powertrain system including a hybrid transmission operative in one of a fixed gear operating range state and a continuously variable operating range state to transmit torque between an input member and a torque machine and an output member coupled to a driveline, the method comprising:

monitoring operator inputs to an accelerator pedal and a brake pedal;

monitoring vehicle speed;

maintaining the transmission in a present operating range state subsequent to the operator disengaging the accelerator pedal absent the operator engaging the brake pedal;

transitioning the transmission device to a continuously variable operating range state subsequent to the operator disengaging the accelerator pedal and the operator engaging the brake pedal;

executing regenerative braking by controlling the torque machine to react torque through the transmission to brake the vehicle through the driveline when the operator engages the brake pedal and the speed of the vehicle is greater than a first threshold; and

disabling the regenerative braking when one of

the speed of the vehicle is less than the first threshold and the operator disengages the brake pedal, and

the speed of the vehicle decelerates to at least a second threshold less than the first threshold and the brake pedal is continuously engaged.

2. The method of claim 1, further comprising re-enabling regenerative braking through the driveline when the vehicle speed increases from a first vehicle speed below the first threshold to a second vehicle speed exceeding a third threshold.

3. The method of claim 2, wherein the third threshold is based on the first threshold and a hysteresis speed value.

4. The method of claim 1, further comprising executing friction braking and regenerative braking to reduce vehicle speed when regenerative braking is enabled, and executing friction braking to reduce vehicle speed when regenerative braking is disabled.

5. The method of claim 1, comprising providing a preloaded torque from a frictional brake to the driveline when the vehicle speed is between the first threshold and the second threshold.

6. The method of claim 1, further comprising:

determining an operator torque request based upon an engagement level of the brake pedal and the engagement level of the accelerator pedal; and

determining an operating range state of the transmission device based on an optimization routine based on the operator torque request when the operator is engaging the accelerator pedal.

7. The method of claim 1, further comprising:

determining new engine state when the accelerator pedal is disengaged based on an operator torque request and a current vehicle speed; and

transitioning the engine from a current engine state to the new engine state when the accelerator pedal is disengaged based on an operator torque request and a current vehicle speed.

8. The method of claim 7, wherein the engine state comprises one of a fuel cutoff engine state, a cylinder deactivation engine state, and a fuel cutoff and cylinder deactivation engine state.

9. The method of claim 7, wherein the current engine state comprises one of a fueled, all-cylinder engine state.

10. The method of claim 7, comprising transitioning between a first continuously variable operating range state and a second continuously variable operating range state absent an intervening transition to one of the fixed gear operating range states when executing regenerative braking.

11. Method for operating a vehicle including a friction braking system and a transmission device operative in one of a plurality of operating range states including a fixed gear mode and a continuously variable mode to transmit torque between an engine and an electric machine connected to an energy storage device, the method comprising:

monitoring operator inputs to an accelerator pedal and a brake pedal and monitoring vehicle speed;

maintaining the transmission device in a present operating range state subsequent to the operator disengaging the accelerator pedal;

transitioning the transmission device to a continuously variable operating range state subsequent to the operator engaging the brake pedal;

executing regenerative braking by controlling the torque machine to react torque through the transmission to brake the vehicle through the driveline when the operator engages the brake pedal and the speed of the vehicle is greater than a first threshold;

enabling regenerative braking so long as one of the brake pedal is engaged and the vehicle speed is greater than a second threshold less than the first threshold, and

disabling the regenerative braking when one of the speed of the vehicle is less than the first threshold and the operator disengages the brake pedal, and the speed of the vehicle decelerates to at least a second threshold less than the first threshold and the brake pedal is continuously engaged.

12. The method of claim 11, further comprising re-enabling the regenerative braking only when the vehicle speed exceeds a third threshold.

13. The method of claim 11, further comprising:

determining a new engine state when the accelerator pedal is disengaged based on an operator torque request and a current vehicle speed; and

transitioning the engine to the new engine state when the operator disengages the accelerator pedal based on an operator torque request and a current vehicle speed.

14. The method of claim 13, wherein the new engine state comprises one of a fuel cutoff engine state, a cylinder deactivation engine state, and a fuel cutoff and cylinder deactivation engine state.

15. The method of claim 11, further comprising:

determining an operator torque request based on a level of engagement of the accelerator pedal and a level of engagement of the brake pedal; and

determining a new operating range state of the transmission based on the operator torque request when the operator engages the accelerator pedal.

16. Method for operating a vehicle including a friction braking system and a hybrid transmission operative in one of a plurality of operating range states including a fixed gear and a continuously variable mode to transmit torque between an engine and an electric machine connected to an energy storage device, the method comprising:

monitoring operator inputs to an accelerator pedal and a brake pedal;

monitoring vehicle speed;

maintaining the transmission in a present operating range state subsequent to the operator disengaging the accelerator pedal absent engagement of the brake pedal;

transitioning the transmission to the continuously variable mode subsequent to the disengagement of the accelerator pedal and engagement of the brake pedal;

executing regenerative braking by controlling the torque machine to react torque through the transmission to brake the vehicle through the driveline when the brake pedal is engaged and the speed of the vehicle is greater than a first threshold; and

disabling the regenerative braking when one of

the speed of the vehicle is less than the first threshold and the operator disengages the brake pedal, and

the speed of the vehicle decelerates to at least a second threshold less than the first threshold and the brake pedal is continuously engaged.

17. The method of claim 16, further comprising:

determining an operator torque request based on a level of engagement of the accelerator pedal; and

determining a new operating range state of the transmission based on the operator torque request.

18. The method of claim 16, further comprising transitioning the engine state to a new engine state when the accelerator pedal is disengaged.

19. The method of claim 16, comprising transitioning between a first continuously variable operating range state and a second continuously variable operating range state absent an intervening transition to one of the fixed gear operating range states concurrent with the regenerative braking.