Torque modulation in a hybrid vehicle downshift during regenerative braking

• US 10,336,315 B2
• Filed: 10/27/2016
• Issued: 07/02/2019
• 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, Connolly, Francis Thomas, Colvin, Dan, Ortmann, Walt Joseph, Kraska, Marvin Paul, Crombez, Dale Scott, Yamazaki, Mark Steven
• Primary Examiner(s): Mahne, Kevin P
• Application Number:
  US15/335,725
• Publication Number:
  US 20170043760A1
• Time in Patent Office: 978 Days
• Field of Search: None
• 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 method for reducing shift shock in a hybrid electric vehicle powertrain system including an engine and a step ratio automatic transmission for delivering an output torque, the method comprising:

transferring a first input torque from the engine to the transmission;

effecting a downshift of the transmission during regenerative braking which tends to cause variations in the output torque; and

modulating the first input torque during the downshift to counteract the variations and maintain the output torque substantially constant to reduce the shift shock.

2. The method of claim 1, further comprising:

maintaining the output torque substantially constant; and

preventing ramping or spiking of an output torque signal by controlling the first input torque from the engine.

3. The method of claim 2, further comprising:

measuring an output torque signal indicative of the output torque, wherein maintaining the output torque substantially constant includes maintaining the output torque signal substantially constant.

4. The method of claim 1, further comprising:

causing the engine to generate the first input torque and modulating an engine torque signal to cause the engine to modulate the first input torque.

5. The method of claim 1, wherein modulating the first input torque includes modulating the first input torque using a controller.

6. The method of claim 1, further comprising:

causing a motor to generate a second input torque; and

transferring the second input torque to the transmission.

7. The method of claim 6, further comprising:

modulating the second input torque during the downshift to maintain the output torque substantially constant.

8. The method of claim 6, further comprising sending a motor torque signal to the motor to modulate the second input torque.

9. The method of claim 1, further comprising:

taking time to complete the downshift; and

extending the time taken to complete the downshift to maintain the output torque substantially constant.

10. The method of claim 1, further comprising:

causing friction brakes mounted at drive wheels to apply a friction braking force; and

varying the friction braking force to maintain the output torque substantially constant, wherein the output torque is a wheel torque.

11. The method of claim 10, wherein causing the friction brakes to apply the friction braking force includes sending a friction braking signal to the friction brakes and varying the friction braking force includes varying the friction braking signal.

12. The method of claim 10, further comprising:

determining a timing for applying the friction braking force by predicting a lag time associated with applying the friction braking force and compensating for the lag time.

13. The method of claim 10, further comprising:

decreasing an amount of friction braking during a torque phase of the downshift.

14. The method of claim 13, further comprising:

restoring the amount of friction braking during an inertia phase of the downshift.

15. The method of claim 1, further comprising:

removing the regenerative braking before the downshift; and

reinstating the regenerative braking after the downshift.

16. The method of claim 1, further comprising:

increasing an amount of regenerative braking during both a torque phase and an inertia phase of the downshift.

17. A hybrid electric vehicle powertrain system comprising:

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

an engine for generating a first input torque that is transferred to the transmission;

a controller configured to;

effect a downshift of the transmission during regenerative braking which tends to cause variations in the output torque; and

modulate the first input torque during the downshift to counteract the variations and maintain the output torque substantially constant thereby reducing shift shock during the down shift.

18. The powertrain system of claim 17, further comprising:

an electric motor for generating a second input torque that is transferred to the transmission.

19. The powertrain system of claim 18, wherein the controller is further configured to modulate the second input torque during the downshift to maintain the output torque substantially constant.

20. The powertrain system of claim 17, further comprising:

friction brakes mounted at the set of drive wheels for applying a friction braking force, wherein the controller is further configured to vary the friction braking force to maintain the output torque substantially constant, wherein the output torque is a wheel torque.

21. A method for reducing shift shock in a hybrid electric vehicle powertrain, the method comprising:

transferring an input torque from an engine to a transmission in the powertrain;

effecting a downshift of the transmission during regenerative braking which tends to cause variations in a output torque from the transmission; and

modulating the input torque during the downshift to counteract the variations and maintain the output torque substantially constant to reduce the shift shock.

22. The method of claim 21, wherein the shift shock is reduced throughout the downshift.