Distribution of torque when driven wheels slip during regenerative braking

• US 6,488,344 B2
• Filed: 05/03/2001
• Issued: 12/03/2002
• Est. Priority Date: 05/03/2001
• Status: Active Grant

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Huls, Timothy Allen, Napier, Steven Lee
• Primary Examiner(s): Graham, Matthew C.
• Application Number:
  US09/848,570
• Publication Number:
  US 20020163250A1
• Time in Patent Office: 579 Days
• Field of Search: 303/152, 303/113.5, 303/3.15, 303/20, 303/186, 180/165, 180/197, 180/65-- 6
• US Class Current: 303/152
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2240/461 Speed
• CPC Class Codes: B60L 2240/465 Slip
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60L 2260/28 Four wheel or all wheel drive
• CPC Class Codes: B60L 3/108 whilst braking, i.e. ABS
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 7/10 Dynamic electric regenerative braking B60L7/22 takes precedence
• CPC Class Codes: B60L 7/18 Controlling the braking effect B60L7/12, B60L7/14, B60L7/16 take precedence
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60W 2520/26 Wheel slip
• CPC Class Codes: B60W 2710/105 Output torque
• CPC Class Codes: Y02T 10/40 Engine management systems
• 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

Abstract

A method of braking an electric or hybrid vehicle 7 is provided. The vehicle (7) has electric regenerative brakes and friction brakes (94). In a normal braking situation regenerative brakes are applied. If a wheel (42) slip condition is sensed, a selectively operable clutch (76) tortionally connects an undriven axle (60) to the driven axles (44, 45) to alleviate the slip condition. The alleviation of the slip condition prevents the electric regenerative brakes from being shut off in favor of an antilock friction brake application.

Claims

1. A method of braking a vehicle, comprising:

electrically regeneratively braking a first wheeled axle;

sensing for a slip condition of a wheel of said first wheeled axle; and

torsionally connecting said first wheeled axle with at least a second wheeled axle upon a slip condition of a wheel of said first wheeled axle.

2. A method of braking a vehicle as described in claim 1, wherein said regenerative braking first occurs on a driven axle.

3. A method of braking a vehicle as described in claim 1, further comprising reducing the regenerative braking of said first and second wheeled axles below a slip condition of said first wheeled axle.

4. A method of braking a vehicle as described in claim 1, further including shutting off said regenerative braking of said first wheeled axle and engaging said first wheeled axle with a second brake system having an antilock braking mode of operation.

5. A method of braking a vehicle having an electrically driven and an electrically regenerative braked first wheeled axle, said vehicle also having a second wheeled axle selectively torsionally connected with said first wheeled axle, said method comprising:

electrically regeneratively braking said first wheeled axle;

sensing to determine if said first wheeled axle wheels are slipping; and

selectively torsionally connecting said second wheeled axle to said first wheeled axle to electrically regeneratively brake said first and second wheeled axles.

6. A method of braking a vehicle as described in claim 5, further including reducing the electric regenerative braking of said first and second axles to cause said wheels on said first wheeled axle to come out of a slip condition.

7. A method of braking a vehicle as described in claim 5, further including braking said first wheeled axle with a second brake system having an antilock mode of operation.

8. A method of braking a vehicle having an electrically driven and regeneratively braked first wheeled axle and a second wheeled axle, said vehicle also having a second brake system for said first axle having an antilock mode of operation, said method comprising the steps of:

sensing a slip condition on a wheel of said first axle;

determining if said first axle is currently being regeneratively braked;

braking said first wheeled axle with said second brake system in an antilock mode of operation when a slip condition is sensed on a wheel of said first wheeled axle and when said electric regenerative brake is not activated;

sensing if said second wheeled axle is torsionally connected with said first wheeled axle if said electric regenerative brake is activated;

engaging said second brake system on said first wheeled axle in an antilock mode of operation if said second wheeled axle is torsionally connected to said first wheel axle or reducing the electric regenerative braking of said first axle to a level below said wheel slip level; and

torsionally connecting said second wheeled axle with said first wheeled axle if said first wheeled axle is being electrically regeneratively braked.

9. A method as described in claim 8, wherein said first wheeled axle is being electrically regeneratively braked to compression brake said vehicle.

10. A method of braking a vehicle as described in claim 8, wherein said vehicle is electrically regeneratively braked in response to an operator command signal.

11. A method of braking a vehicle as described in claim 9, wherein said first wheeled axle is driven by an electric motor or an internal combustion engine.

12. A method as described in claim 10, wherein there are two motor generators and all electric regenerative braking is performed by a second motor generator.