METHOD FOR DETERMINING A PREFERRED ENGINE OPERATION IN A HYBRID POWERTRAIN SYSTEM DURING BLENDED BRAKING

• US 20090118934A1
• Filed: 10/14/2008
• Published: 05/07/2009
• Est. Priority Date: 11/04/2007
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG, Daimler AG (Mercedes-Benz Group AG), Chrysler Group LLC (Stellantis NV)
• Original Assignee: BMW AG (Bayerische Motoren Werke AG), Daimler AG (Mercedes-Benz Group AG), GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust), Chrysler LLC (Stellantis NV)
• Inventors: Heap, Anthony H.
• Granted Patent: US 8,494,732 B2
• Time in Patent Office: Days
• US Class Current: 701/54
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/26 characterised by the motors or the generators
• 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 2240/423 Torque
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 2240/486 Operating parameters
• 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 2510/0657 Engine torque
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2710/1022 Input torque
• CPC Class Codes: B60W 2710/105 Output torque
• CPC Class Codes: F16H 2037/0866 Power split variators with distributing differentials, with the output of the CVT connected or connectable to the output shaft
• CPC Class Codes: F16H 2037/102 : the input or output shaft of the transmission is connected or connectable to two or more differentials
• CPC Class Codes: F16H 2037/104 : Power split variators with one end of the CVT connected or connectable to two or more differentials
• CPC Class Codes: F16H 2037/106 : with switching means to provide two variator modes or ranges
• CPC Class Codes: F16H 3/728 : with means to change ratio in the mechanical gearing
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/84 : Data processing systems or methods, management, administration

Abstract

A hybrid transmission is operative to transfer power between an input member and a torque machine and an output member. A method for controlling the powertrain system during a braking event includes evaluating candidate input torques. An output torque reactable through the transmission to the driveline and limited within the range of permissible output torques is determined for the candidate engine input torque. A preferred input torque is determined.

Claims

1. Method for controlling a powertrain system including an engine, a transmission and a torque machine connected to an energy storage device, the transmission operative to transfer power between the engine and the torque machine and an output member coupled to a driveline coupled to a wheel including an actuable friction brake, the torque machine operative to react torque transferred from the wheel through the driveline to the output member of the transmission, the engine selectively operative in an all-cylinder state and a cylinder deactivation state and selectively operative in a fueled state and a fuel cutoff state, the method comprising:

monitoring operator torque requests;

detecting a braking event based upon the operator torque requests;

determining a range of permissible output torques based upon the operator torque requests;

evaluating candidate input torques from the engine for each of the engine states and determining corresponding candidate output torques reactable through the output member of the transmission to the driveline, the candidate output torques limited within the range of permissible output torques;

determining power costs for operating the hybrid transmission for the candidate input torques; and

identifying a preferred engine state and a preferred input torque comprising the candidate input torque and the corresponding engine state having a minimum power cost for operating the hybrid transmission during the braking event.

2. The method of claim 1, further comprising:

monitoring operator torque requests comprising operator inputs to a brake pedal and an accelerator pedal;

determining a net output torque request and an accelerator output torque request based upon the operator inputs to the brake pedal and the accelerator pedal; and

determining the range of permissible output torques based upon the net output torque request and the accelerator output torque request.

3. The method of claim 2, comprising

determining a preferred output torque corresponding to the preferred engine state and the preferred input torque;

and

controlling the engine based upon the preferred engine state and a preferred input torque and controlling motor torque from the torque machine based upon the preferred output torque.

4. The method of claim 3, further comprising controlling actuation of the friction brakes based upon the preferred output torque and the operator torque requests.

5. The method of claim 1, comprising determining the power costs for operating the hybrid transmission for the candidate input torques during the braking event based upon unrecovered kinetic energy power loss during the braking event.

6. The method of claim 1, further comprising executing a search over a range of candidate input torques for the engine in the fueled state and operating in one of the all-cylinder state and the cylinder deactivation state, determining preferred output torques reactable through the output member of the transmission to the driveline for the candidate input torques, and determining corresponding power costs for operating the hybrid transmission based thereon.

7. The method of claim 6, further comprising determining candidate input torques for the engine in the fuel cutoff state and operating in one of the all-cylinder state and the cylinder deactivation state, determining preferred output torques reactable through the output member of the transmission for the candidate input torques to the driveline, and determining corresponding power costs for operating the hybrid transmission based thereon.

8. The method of claim 1, further comprising iteratively selecting candidate input torques within an allowable range for the input torque, determining a corresponding candidate output torque reactable through the output member to the driveline based upon the candidate input torque, determining a friction braking torque based upon the operator torque requests and the candidate output torque, and determining a power cost for operating the powertrain system associated with the operator torque requests;

and selecting a preferred input torque comprising the candidate input torque that minimizes the power cost for operating the powertrain system.

9. Method for controlling a powertrain system including an engine, a transmission and a torque machine connected to an energy storage device, the transmission operative to transfer power between the engine and the torque machine and an output member coupled to a driveline coupled to a wheel including an actuable friction brake, the torque machine operative to react torque transferred from the wheel through the driveline to the output member of the transmission, the method comprising:

detecting a braking event based upon operator torque requests;

determining a range of permissible output torques based upon the operator torque requests;

evaluating candidate input torques from the engine and determining corresponding candidate output torques limited by the range of permissible output torques and reactable through the output member of the transmission to the driveline;

determining corresponding power costs for operating the powertrain to achieve the candidate output torque at the candidate input torque; and

identifying a preferred input torque comprising the candidate input torque that minimizes the power costs.

10. The method of claim 9, further comprising identifying a preferred engine state to minimize the power costs for operating the hybrid transmission during the braking event.

11. The method of claim 9, comprising determining the corresponding power costs for operating the powertrain to achieve the candidate output torque at the candidate input torques during the braking event based upon unrecovered kinetic energy power loss during the braking event.

12. The method of claim 9, further comprising executing a search over a range of candidate input torque values for the engine in the fueled state and operating in one of the all-cylinder state and the cylinder deactivation state, determining preferred output torques reactable through the output member of the transmission to the driveline for the candidate input torque values, and determining corresponding power costs for operating the hybrid transmission based thereon.

13. The method of claim 12, further comprising determining candidate input torque values for the engine in the fuel cutoff state and operating in one of the all-cylinder state and the cylinder deactivation state, determining preferred output torques reactable through the output member of the transmission for the candidate input torques to the driveline, and determining corresponding power costs for operating the hybrid transmission based thereon.

14. The method of claim 9, further comprising iteratively selecting candidate input torques within an allowable range for the input torque, determining a corresponding candidate output torque reactable through the output member to the driveline based upon the candidate input torque, determining a friction braking torque based upon the operator torque requests and the candidate output torque, and determining a power cost for operating the powertrain system associated with the operator torque requests;

and selecting a preferred input torque comprising the candidate input torque that minimizes the power cost for operating the powertrain system.

15. Method for controlling a hybrid transmission operative to transfer power between an input member and a torque machine and an output member, the method comprising:

monitoring operator torque requests associated with braking and acceleration;

detecting a braking event based upon the operator torque requests;

determining a range of permissible output torques based upon the operator torque requests;

evaluating candidate input torques to the input member and determining corresponding candidate output torques reactable through the output member of the transmission, the candidate output torques limited within the range of permissible output torques;

determining power costs for operating the hybrid transmission at each of the candidate input torques; and

identifying a preferred input torque comprising the candidate input torque having a minimum power cost for operating the hybrid transmission during the braking event to achieve the operator torque requests.