INPUT TORQUE TRIM FOR TRANSMISSION SHIFT CONTROL DURING REGENERATIVE BRAKING

• US 20160304076A1
• Filed: 04/14/2015
• Published: 10/20/2016
• Est. Priority Date: 04/14/2015
• 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., COLVIN, Daniel Scott, NEDOREZOV, Felix, MCCULLOUGH, Todd
• Granted Patent: US 9,944,269 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60K 6/48 Parallel type
• 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 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 2050/0008 Feedback, closed loop systems or details of feedback error signal
• CPC Class Codes: B60W 2050/0012 Feedforward or open loop systems
• CPC Class Codes: B60W 2510/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2510/1025 Input torque
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2710/1011 Input shaft speed, e.g. turbine speed
• CPC Class Codes: B60W 2710/1022 Input 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: F16H 2061/0422 by an electric machine, e.g. by accelerating or braking the input shaft
• CPC Class Codes: F16H 61/0403 Synchronisation before shifting
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/93 Conjoint control of different elements

Abstract

A system and method for controlling a step-ratio transmission gearshift during a regenerative braking event for a hybrid vehicle having an engine selectively coupled to an electric machine and an automatic transmission control transmission input torque based on a measured shift profile and a target shift profile. A torque trim term may be added to the transmission input torque or electric machine output torque in response to a difference between the measured and target shift profiles. The torque trim term may be used to modify the transmission input torque to speed the shift up or shorten the shift time if the measured shift is progressing too slowly. Likewise, the torque trim term may be used to reduce the transmission input torque or electric machine output torque if the shift is progressing too quickly relative to the target shift profile.

Claims

1. A hybrid vehicle, comprising:

an electric machine coupled to an engine and a transmission by first and second clutches, respectively; and

a controller configured to adjust a transmission input torque based on a difference between a target shift profile and a measured shift profile during an inertia phase of a transmission downshift event conducted while the hybrid vehicle is in a regenerative braking mode.

2. The hybrid vehicle of claim 1 wherein the controller is further configured to control pressure using closed-loop pressure control of at least one shifting clutch during the downshift event.

3. The hybrid vehicle of claim 1, wherein the controller is configured to control the transmission input torque based on a driver demand and an expected inertia torque compensation.

4. The hybrid vehicle of claim 1, wherein the controller controls the electric machine to adjust the transmission input torque by a torque trim term in response to the difference between the target shift profile and the measured shift profile.

5. The hybrid vehicle of claim 1, wherein the controller is configured to adjust the transmission input torque by controlling output torque of the electric machine in response to the measured shift profile relative to the target shift profile.

6. The hybrid vehicle of claim 1, wherein the controller controls the electric machine to decrease the transmission input torque in response to the measured shift profile being faster than that of the target shift profile.

7. The hybrid vehicle of claim 1, wherein the controller is further configured to control hydraulic pressure of an oncoming transmission clutch in response to a requested output torque corresponding to a gear ratio after completion of the downshift.

8. A hybrid vehicle, comprising:

an engine;

an electric machine coupled to the engine by a first clutch;

a transmission including multiple discrete gear ratios coupled to the electric machine by a second clutch; and

a controller configured to control transmission input torque to effect a transmission gearshift between two gear ratios during regenerative braking in response to a difference between a target shift profile and a measured shift profile.

9. The hybrid vehicle of claim 8, wherein the controller modulates transmission input torque using an open-loop torque trim term determined from a difference in the target shift profile and the measured shift profile.

10. The hybrid vehicle of claim 9, wherein the controller is configured to provide pressure control of at least one shifting clutch associated with gearshift.

11. The hybrid vehicle of claim 9, wherein the controller implements closed-loop control of the transmission input torque and applies an open-loop torque trim term based on a comparison between the measured shift profile is greater than that of the target shift profile.

12. The hybrid vehicle of claim 9, wherein the controller is further configured to modulate the transmission input torque to compensate for variations caused by regenerative braking during the gearshift.

13. A method for controlling a hybrid vehicle having an electric machine coupled to an engine by a first clutch and a step-ratio transmission by a second clutch, comprising:

controlling, by a controller, during regenerative braking, output torque of the electric machine during a gearshift while performing closed-loop pressure control of a shifting clutch, the output torque controlled in response to a difference between a target shift profile and a measured shift profile.

14. The method of claim 13, wherein the target shift profile and the measured shift profile are associated with a percent of completion of the downshift.

15. The method of claim 13, wherein the output torque is based on a powertrain braking request and an expected inertia change associated with the transmission gearshift during an inertia phase of the gearshift.

16. The method of claim 13, further comprising:

adjusting the electric machine output torque by a torque trim term determined from the difference between the target shift profile and the measured shift profile.

17. The method of claim 13, further comprising:

reducing the electric machine output torque when a percent of completion of the measured shift profile is greater than that of the target shift profile.

18. The method of claim 13, further comprising:

increasing the electric machine output torque when a percent of completion of the measured shift profile is less than that of the target shift profile.

19. The method of claim 13 wherein in the shifting clutch is an on-coming clutch, the method further comprising:

stroking the on-coming clutch; and

reducing hydraulic pressure of an off-going clutch during a starting phase of the transmission gearshift.

20. The method of claim 13 wherein the second clutch is engaged during the transmission gearshift.