Torque Modulation in a Hybrid Vehicle Downshift During Regenerative Braking

• US 20120265382A1
• Filed: 04/13/2011
• Published: 10/18/2012
• Est. Priority Date: 04/13/2011
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Nefcy, Barney D., Colvin, Dan, Ortmann, Walt Joseph, Kraska, Marvin Paul, Crombez, Dale Scott, Yamazaki, Mark Steven, Connolly, Francis Thomas
• Granted Patent: US 9,493,148 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60K 2006/4825 Electric machine connected or connectable to gearbox input shaft
• CPC Class Codes: B60K 6/48 Parallel type
• 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 10/10 including control of change-speed gearings
• 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 10/188 hydraulic brakes
• CPC Class Codes: B60W 20/10 Controlling the power contribution of each of the prime movers to meet required power demand
• CPC Class Codes: B60W 20/15 Control strategies specially adapted for achieving a particular effect
• CPC Class Codes: B60W 20/30 Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 2030/18081 With torque flow from driveshaft to engine, i.e. engine being driven by vehicle
• CPC Class Codes: B60W 2030/206 related or induced by the engine
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2720/106 Longitudinal acceleration
• CPC Class Codes: B60W 2720/30 Wheel torque
• CPC Class Codes: B60W 30/18127 Regenerative braking
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: B60W 30/20 : Reducing vibrations in the driveline
• CPC Class Codes: B60Y 2200/92 : Hybrid vehicles
• CPC Class Codes: B60Y 2300/18125 : Regenerative braking
• CPC Class Codes: B60Y 2300/19 : Improvement of gear change, e.g. synchronisation or smoothing gear shift
• CPC Class Codes: B60Y 2400/112 : Batteries
• CPC Class Codes: B60Y 2400/73 : Planetary gearings
• CPC Class Codes: F16H 61/04 : Smoothing ratio shift
• CPC Class Codes: F16H 63/502 : for smoothing gear shifts
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y10S 903/93 : Conjoint control of different elements

Abstract

A controller and a control strategy minimizes shift shock in a hybrid electric vehicle during a downshift conducted while the vehicle is in a regenerative braking mode by maintaining total powertrain torque at a desired target during the downshift. The controller has three preferable modes including modulating just engine torque, modulating just electric motor torque or simultaneously modulating both motor and engine torque.

Claims

1. A hybrid electric vehicle powertrain system comprising:

an automatic transmission including multiple gear ratios for delivering an output torque to a set of drive wheels; and

a controller configured to effect a downshift between gear ratios during regenerative braking while maintaining the output torque substantially constant.

2. The powertrain system of claim 1, further comprising an engine for generating a first input torque that is transferred to the transmission and a motor for generating a second input torque that is transferred to the transmission.

3. The powertrain system of claim 2, wherein the regenerative braking tends to cause variations in the output torque, and wherein the controller is configured to modulate the first input torque to counteract the variations.

4. The powertrain system of claim 3, wherein the controller is configured to also modulate the second input torque to counteract the variations.

5. The powertrain system of claim 2, wherein the regenerative braking tends to cause variations in the output torque, and wherein the controller is configured to modulate the second input torque to counteract the variations.

6. The powertrain system of claim 1, further comprising friction brakes mounted at the drive wheels for applying a friction braking force and wherein the controller is configured to vary the friction braking force to counteract variations in the output torque which tend to be caused by the regenerative braking in the transmission during the downshift.

7. A method for reducing shift shock in a hybrid vehicle powertrain system including an automatic transmission for delivering an output torque through multiple gear ratios comprising:

effecting a downshift between the gear ratios during regenerative braking;

measuring an output torque signal indicative of the output torque; and

maintaining the output torque signal substantially constant during the downshift.

8. The method according to claim 7, further comprising:

sending an engine torque signal to an engine to cause the engine to generate a first input torque; and

transferring the first input torque to the transmission,

wherein maintaining the output torque signal substantially constant further includes modulating the engine torque signal to counteract variations in the output torque which tend to be caused by the regenerative braking during the downshift.

9. The method according to claim 8, further comprising:

sending a motor torque signal to an electric motor to cause the motor to generate a second input torque; and

transferring the second input torque to the transmission,

wherein maintaining the output torque signal substantially constant further includes modulating the motor torque signal to counteract variations in the output torque which tend to be caused by the regenerative braking during the downshift.

10. The method according to claim 8, further comprising extending a time taken to complete the downshift.

11. The method according to claim 7, further comprising:

sending a motor torque signal to an electric motor to cause the motor to generate an input torque; and

transferring the input torque to the transmission,

wherein maintaining the output torque signal constant further includes modulating the motor torque signal.

12. The method according to claim 7, further comprising:

sending a friction braking force signal to friction brakes mounted on drive wheels of the hybrid vehicle for applying friction braking; and

varying the friction braking force signal to counteract variations in the output torque which tend to be caused by the regenerative braking during the downshift.

13. The method according to claim 12, further comprising determining a timing for applying friction braking by:

predicting a lag time associated with the friction braking; and

compensating for the lag time.

14. The method according to claim 12, further comprising decreasing an amount of friction braking during a torque phase of the downshift.

15. The method according to claim 14, further comprising restoring the amount of friction braking during an inertia phase of the downshift.

16. The method according to claim 7, further comprising:

removing the regenerative braking before the downshift; and

reinstating the regenerative braking after the downshift.

17. The method according to claim 7, further comprising increasing the amount of regeneration braking during both a torque phase and an inertia phase of the downshift.

18. A method for reducing shift shock in a hybrid vehicle powertrain system including an automatic transmission with multiple gear ratios comprising:

delivering an output torque from the transmission;

effecting a downshift between the gear ratios during regenerative braking; and

maintaining the output torque substantially constant during the downshift.

19. The method according to claim 18, further comprising:

causing an engine to generate a first input torque; and

transferring the first input torque to the transmission,

wherein maintaining the output torque substantially constant further includes modulating the first input torque to counteract variations which tend to be caused by the regenerative braking during the downshift.

20. The method according to claim 19, further comprising:

causing an electric motor to generate a second input torque;

transferring the second input torque to the transmission; and

wherein maintaining the output torque substantially constant further includes modulating the second input torque to counteract variations which tend to be caused by the regenerative braking during the downshift.

21. The method according to claim 18, further comprising:

causing an electric motor to generate an input torque;

transferring the input torque to the transmission; and

wherein maintaining the output torque substantially constant further includes modulating the input torque to counteract variations which tend to be caused by the regenerative braking during the downshift.