HYBRID VEHICLE BRAKING LIMIT DETERMINATION SYSTEM AND METHOD

• US 20150203106A1
• Filed: 01/17/2014
• Published: 07/23/2015
• Est. Priority Date: 01/17/2014
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: ZHAO, Yanan, CONNOLLY, Francis Thomas, DAI, Zhengyu, KUANG, Ming Lang, NEFCY, Bernard D.
• Granted Patent: US 9,352,744 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 3/0038 relating to sensors
• CPC Class Codes: B60L 3/0084 relating to control modules
• CPC Class Codes: B60L 3/0092 with use of redundant elements for safety purposes
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 7/18 Controlling the braking effect B60L7/12, B60L7/14, B60L7/16 take precedence
• CPC Class Codes: B60W 10/00 Conjoint control of vehicle sub-units of different type or different function for propulsion of purely electrically-propelled vehicles with power supplied within the vehicle B60L50/00 - B60L58/00
• CPC Class Codes: B60W 10/026 of lock-up clutches
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/14 in conjunction with braking regeneration
• CPC Class Codes: B60W 20/50 Control strategies for responding to system failures, e.g. for fault diagnosis, failsafe operation or limp mode
• CPC Class Codes: B60W 2050/022 Actuator failures
• CPC Class Codes: B60W 2510/0241 Clutch slip, i.e. difference between input and output speeds
• CPC Class Codes: B60W 30/18127 Regenerative braking
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y10S 903/947 : Characterized by control of braking, e.g. blending of regeneration, friction braking

Abstract

A vehicle includes a powertrain having an electric machine configured to selectively apply regenerative torque to cause deceleration in response to braking demand; the powertrain further including a torque converter configured to decouple the electric machine from wheels of the vehicle. The vehicle is also provided with a controller programmed to, during a regenerative braking event, receive a signal defining a regenerative torque limit, and in response to a fault condition associated with the regenerative torque limit, generate a replacement regenerative torque limit based upon a torque converter open speed to decrease roughness during transitions into and out of regenerative braking.

Claims

1. A vehicle comprising:

a powertrain having an electric machine configured to selectively apply regenerative torque to cause deceleration in response to braking demand, the powertrain further including a torque converter configured to decouple the electric machine from wheels of the vehicle; and

a controller programmed to, during a regenerative braking event, receive a signal defining a regenerative torque limit, and in response to a fault condition associated with the regenerative torque limit, generate a replacement regenerative torque limit based upon a torque converter open speed to decrease roughness during transitions into and out of regenerative braking.

2. The vehicle of claim 1 wherein the controller is further programmed to prevent the electric machine from applying regenerative torque in response to a coupling status fault condition associated with the torque converter.

3. The vehicle of claim 1 wherein the controller is further programmed to prevent the regenerative torque from increasing in response to a coupling status slip condition associated with the torque converter.

4. The vehicle of claim 1 wherein the fault condition comprises a regenerative torque limit being outside of a predetermined range corresponding to current vehicle operating conditions.

5. The vehicle of claim 1 wherein the controller is further programmed to select a regenerative torque mode based upon the regenerative torque limit or a coupling status of the torque converter.

6. The vehicle of claim 5 wherein the regenerative torque mode comprises a normal mode using the regenerative torque limit or a limited mode using the replacement regenerative torque limit.

7. The vehicle of claim 1 wherein the controller is further programmed to prevent the regenerative torque from increasing during a downshift of a transmission gear ratio.

8. The vehicle of claim 1 wherein the torque converter open speed is based on a transmission oil temperature and a torque converter impeller speed.

9. A method of controlling regenerative braking comprising:

receiving a signal indicative of a subservient regenerative torque limit; and

in response to braking demand, issuing a command for an electric machine to apply regenerative braking torque, wherein the applied regenerative torque is less than or equal to (i) a replacement regenerative torque limit if a fault is detected with the subservient regenerative torque limit or (ii) the subservient regenerative torque limit if no fault is detected.

10. The method of claim 9 further comprising sensing a coupling status of a torque converter, and disabling regenerative braking torque in response to a fault associated with the coupling status.

11. The method of claim 9 further comprising sensing a coupling status of a torque converter, and preventing an increase of the regenerative braking torque in response to a coupling status slip condition.

12. The method of claim 9 wherein the fault comprises an inability to detect the subservient regenerative torque limit.

13. The method of claim 9 wherein the fault comprises the subservient regenerative torque limit falling outside of a predetermined range corresponding to present vehicle operating conditions.

14. The method of claim 9 further comprising preventing an increase of the regenerative braking torque during a downshift of a transmission gear ratio.

15. A vehicle comprising:

a powertrain having an electric machine configured to selectively apply regenerative torque causing deceleration in response to braking demand; and

a first controller programmed to validate a signal indicative of an electric machine regenerative torque limit sent from a second controller, and in response to a fault condition associated with the signal, issue a replacement limit based upon vehicle speed such that applied regenerative torque remains less than the replacement limit.

16. The vehicle of claim 15 wherein the fault condition comprises the first controller not detecting the signal or the regenerative torque limit being outside of a predetermined range.

17. The vehicle of claim 15 further comprising a torque converter configured to selectively decouple the electric machine from wheels of the vehicle, wherein the second controller is programmed to issue a signal indicative of a torque converter coupling status and wherein the first controller is further programmed to prevent the regenerative torque from increasing in response to the torque converter coupling status indicating a slip condition of the torque converter.

18. The vehicle of claim 17 wherein the first controller is further programmed to derive a torque converter open speed based on a transmission oil temperature and a torque converter impeller speed.

19. The vehicle of claim 15 wherein the first controller is further programmed to prevent the regenerative torque from increasing during a downshift of a transmission gear ratio.