System for controlling overall coasting torque in a hybrid electric vehicle

Patent metadata

Field	Value
Publication number	US-9026296-B1
Application number	US-201314074748-A
Country	US
Kind code	B1
Filing date	Nov 8, 2013
Priority date	Nov 8, 2013
Publication date	May 5, 2015
Grant date	May 5, 2015

Abstract

A hybrid vehicle is provided that includes an engine, a reversible electric machine capable of generating and providing electric power, and a clutch for selectively engaging the engine to the electric machine. While the vehicle is traveling, an operator of the vehicle may release (“tip-out”) the accelerator pedal, indicating a desire for a reduction in speed and/or acceleration of the vehicle. If the clutch is engaged during the tip-out, the at least one controller is programmed to disengage the clutch and alter a commanded torque to the electric machine in response to the tip-out of the accelerator pedal to simulate compression braking of the engine. If the vehicle is operating in an electric-only mode of propulsion during the tip-out, and if a state-of-charge of the battery is relatively high, the controller is programmed to activate the engine and provide compression torque to the driveline in response to the tip-out.

First claim

What is claimed is:

1. A hybrid vehicle comprising:
an engine;
an electric machine selectively coupled to the engine via a clutch;
an accelerator pedal; and
at least one controller programmed to disengage the clutch and alter a commanded torque to the electric machine in response to a tip-out of the accelerator pedal to simulate compression braking of the engine.

2. The hybrid vehicle of claim 1 , wherein the at least one controller is further programmed to command braking torque in the electric machine in response to the tip-out of the accelerator pedal.

3. The hybrid vehicle of claim 2 , wherein a magnitude of the braking torque commanded by the at least one controller varies in response to various tip-outs of the accelerator pedal occurring at correspondingly various vehicle speeds such that the braking torque of the electric machine simulates various magnitudes of engine compression braking at various vehicle speeds.

4. The hybrid vehicle of claim 3 , wherein the magnitude of the braking torque commanded by the at least one controller is determined from a look-up table as a function of vehicle speed.

5. The hybrid vehicle of claim 1 , further comprising a battery electrically connected to the electric machine for storing electric power generated by the electric machine, wherein the at least one controller is further programmed to re-engage the clutch and activate the engine in response to (i) the accelerator pedal being non-depressed and (ii) a state of charge (SOC) of the battery exceeding a SOC threshold.

6. The hybrid vehicle of claim 5 , wherein the at least one controller is further programmed to alter the commanded torque to the electric machine during vehicle coasting based upon (i) vehicle speed and (ii) engine torque.

7. The hybrid vehicle of claim 6 , wherein the at least one controller is further programmed to reduce the commanded torque of the electric machine while a braking torque of the engine is maintained in response to a reduction of vehicle speed.

8. The hybrid vehicle of claim 6 , wherein the at least one controller is further programmed to increase the commanded braking torque in the electric machine during vehicle coasting based upon a decrease of engine torque.

9. The hybrid vehicle of claim 1 , wherein the electric machine includes an output, and wherein the at least one controller is further programmed to re-engage the clutch and activate the engine in response to (i) the accelerator pedal remaining non-depressed and (ii) the output of the electric machine having a rotational speed above a speed threshold.

10. A system for controlling coasting torque in a hybrid vehicle, comprising:
an engine;
an electric machine selectively coupled to the engine via a clutch;
a battery electrically connected to the electric machine;
an accelerator pedal; and
at least one controller programmed to engage the clutch during an electric-only mode of operation in response to (i) a tip-out of the accelerator pedal and (ii) a state-of-charge of the battery exceeding a charge threshold.

11. The system of claim 10 , wherein the at least one controller is further programmed to reduce a braking torque of the electric machine in response to the engagement of the clutch.

12. The system of claim 11 , wherein the at least one controller is further programmed to alter a rate of decrease of braking torque of the electric machine while a braking torque of the engine is maintained in response to a reduction of vehicle speed.

13. The system of claim 11 , wherein the at least one controller is further programmed to increase the braking torque in the electric machine during vehicle coasting based upon a decrease of engine torque.

14. The system of claim 11 , wherein the at least one controller is further programmed to alter a rate of decrease of the braking torque in the electric machine during vehicle coasting based upon an increase of engine torque.

15. A system for controlling coasting torque in a hybrid vehicle, comprising:
an engine;
an electric machine having an output and selectively coupled to the engine via a clutch;
an accelerator pedal; and
at least one controller programmed to engage the clutch during an electric-only mode of operation in response to (i) a tip-out of the accelerator pedal and (ii) a rotational speed of the output of the electric machine being above a speed threshold.

16. The system of claim 15 , wherein the at least one controller is further programmed to decrease a braking torque of the electric machine in response to the engagement of the clutch.

17. The system of claim 15 , further comprising a brake pedal, wherein a coasting event is defined during a time in which the accelerator pedal and the brake pedal are non-depressed.

18. The system of claim 17 , further comprising a battery electrically connected to the electric machine for storing electric power generated therefrom, wherein the at least one controller is further programmed to engage the clutch during the coasting event in response to a state of charge of the battery being above a threshold.

19. The system of claim 15 , further comprising a torque converter having an impeller coupled to the electric machine, wherein the output of the electric machine is the impeller such that the at least one controller is programmed to engage the clutch in response to a rotational speed of the impeller being above the speed threshold.

20. The system of claim 15 , further comprising a battery electrically connected to the electric machine, wherein a coasting event of the vehicle begins in response to the tip-out of the accelerator pedal, and wherein the at least one controller is further programmed to disengage the clutch to mechanically isolate the engine from the electric machine during the coasting event in response to a state of charge of the battery being below a threshold.

21. The system of claim 15 , wherein the at least one controller is further configured to, subsequent to engaging the clutch, disengage the clutch in response to a rotational speed of the output of the electric machine being below the speed threshold.

Assignees

• Ford Global Tech Llc

Inventors

• Johri Rajit
• Yamazaki Mark Steven
• Wang Xiaoyong
• Liang Wei
• Mcgee Ryan Abraham
• Kuang Ming Lang

Classifications

• B60W10/06

  including control of combustion engines · CPC title

• Y10S903/902

  Prime movers comprising electrical and internal combustion motors · CPC title

• B60W10/08

  including control of electric propulsion units, e.g. motors or generators · CPC title

• B60W20/10 Primary

  Controlling the power contribution of each of the prime movers to meet required power demand · CPC title

• B60W30/18072

  Coasting · CPC title