Methods and system for operating a powertrain during regenerative braking

• US 9,656,663 B2
• Filed: 06/29/2015
• Issued: 05/23/2017
• Est. Priority Date: 06/29/2015
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Nefcy, Bernard D., Yamazaki, Mark Steven, Meyer, Jason, Davison, Mark
• Primary Examiner(s): Troost, Aaron L
• Application Number:
  US14/754,256
• Publication Number:
  US 20160375893A1
• Time in Patent Office: 694 Days
• CPC Class Codes: B60K 2006/4825 Electric machine connected or connectable to gearbox input shaft
• CPC Class Codes: B60K 6/387 Actuated clutches, i.e. clutches engaged or disengaged by electric, hydraulic or mechanical actuating means
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 10/115 with planetary gears
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 10/30 including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
• CPC Class Codes: B60W 20/14 in conjunction with braking regeneration
• CPC Class Codes: B60W 2510/1005 Transmission ratio engaged
• 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 2520/30 Wheel torque
• CPC Class Codes: B60W 2710/021 Clutch engagement state
• CPC Class Codes: B60W 2710/022 Clutch actuator position
• CPC Class Codes: B60W 2710/023 Clutch engagement rate
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2710/1011 Input shaft speed, e.g. turbine speed
• CPC Class Codes: B60W 2710/182 : Brake pressure, e.g. of fluid or between pad and disc
• CPC Class Codes: B60W 30/18 : Propelling the vehicle
• CPC Class Codes: B60W 30/18127 : Regenerative braking
• CPC Class Codes: B60W 50/06 : Improving the dynamic response of the control system, e.g. improving the speed of regulation or avoiding hunting or overshoot
• CPC Class Codes: B60Y 2300/89 : Repartition of braking force, e.g. friction braking versus regenerative braking
• CPC Class Codes: F16H 2061/009 : using formulas or mathematic relations for calculating parameters
• CPC Class Codes: F16H 61/0204 : for gearshift control, e.g. control functions for performing shifting or generation of shift signal
• CPC Class Codes: F16H 61/0213 : characterised by the method for generating shift signals
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y10S 903/93 : Conjoint control of different elements

Abstract

Systems and methods for operating a transmission of a hybrid powertrain that includes a motor/generator are described. The systems and methods may adjust one or more actuators in response to an estimated transmission input shaft speed that is determined from transmission output shaft speed. The one or more actuators may include a transmission clutch, the motor/generator, or a gear selection solenoid.

Claims

1. A powertrain operating method, comprising:

predicting a transmission input shaft speed from a transmission output shaft speed;

adjusting an actuator in response to an actual transmission input shaft speed minus the predicted transmission input shaft speed; and

determining a negative powertrain wheel torque limit based on the actual transmission input shaft speed minus the predicted transmission input shaft speed.

2. The method of claim 1, where the transmission input speed is predicted via multiplying the transmission output shaft speed by a presently selected transmission gear ratio and subtracting an offset.

3. The method of claim 1, further comprising adjusting a friction brake torque in response to the actual transmission input shaft speed minus the predicted transmission input shaft speed.

4. The method of claim 1, further comprising determining a negative powertrain torque based on the actual transmission input shaft speed minus the predicted transmission input shaft speed.

5. The method of claim 4, further comprising adjusting torque of an integrated starter/generator to provide the negative powertrain torque.

6. A powertrain operating method, comprising:

in response to an actual transmission input shaft speed decreasing to less than a threshold value, decreasing a negative wheel torque magnitude limit toward a value of zero; and

adjusting a torque of a motor/generator to provide negative wheel torque less than the negative wheel torque limit.

7. The method of claim 6, further comprising increasing friction brake torque to provide a desired wheel brake torque based on adjusting the torque of the motor/generator.

8. The method of claim 7, where the friction brake torque is increased by an amount of torque the motor/generator is decreased.

9. The method of claim 6, where a transmission is commanded to a fixed ratio gear while the transmission input shaft speed is decreasing to less than a threshold value.

10. The method of claim 6, where a transmission is commanded to shift between two gear ratios while the transmission input shaft speed is decreasing to less than a threshold value.

11. The method of claim 6, where a powertrain in which the motor/generator operates is in a regeneration mode.

12. The method of claim 6, further comprising determining a negative powertrain wheel torque limit based on the actual transmission input shaft speed minus a predicted transmission input shaft speed.

13. The method of claim 6, further comprising adjusting the torque of the motor/generator to maintain a transmission input shaft speed to a speed greater than a speed where a transmission pump outputs a threshold flow.

14. A system, comprising:

an engine;

a motor/generator;

a disconnect clutch positioned in a powertrain between the engine and the motor/generator;

a transmission coupled to the motor/generator; and

a controller including executable instructions stored in non-transitory memory for adjusting a clutch pressure in response to an actual transmission input shaft speed minus a predicted transmission input shaft speed, and further comprising additional instructions to decrease a negative torque of the motor/generator toward zero torque in response to the actual transmission input shaft speed minus the predicted transmission input shaft speed.

15. The system of claim 14, where the predicted transmission input shaft speed is provided by multiplying a transmission output shaft speed by a presently selected transmission gear ratio.

16. The system of claim 14, further comprising additional instructions to adjust a friction brake torque in response to the actual transmission input shaft speed minus the predicted transmission input shaft speed.

17. The system of claim 16, further comprising additional instructions to operate the system in a regeneration mode while adjusting the clutch pressure.

18. The system of claim 14, further comprising additional instructions to decrease a negative wheel torque limit toward a value of zero in response to the actual transmission input shaft speed minus the predicted transmission input shaft speed.