Method and apparatus for proportioning regenerative braking

• US 6,325,470 B1
• Filed: 10/01/1997
• Issued: 12/04/2001
• Est. Priority Date: 10/01/1997
• Status: Expired due to Fees

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Schneider, Michael John
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): Williams, Thomas J.
• Application Number:
  US08/942,042
• Time in Patent Office: 1,525 Days
• Field of Search: 303/152, 303/186, 303/187, 303/188, 303/189, 303/DIG.1, 303/DIG.2, 303/DIG.6, 303/3, 303/15, 303/20, 188/156, 188/159, 188/181.T
• US Class Current: 303/152
• CPC Class Codes: B60K 1/00 Arrangement or mounting of electrical propulsion units B60K7/00 takes precedence; arrangement or mounting of plural diverse prime-movers for mutual or common propulsion B60K6/00; electric transmission arrangements B60K17/12; electric equipment or propulsion of electrically-propelled vehicles per se B60L; current-collectors for power supply lines of electrically-propelled vehicles B60L5/00
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60T 1/093 in hydrostatic, i.e. positive displacement, retarders
• CPC Class Codes: B60T 8/00 Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force by changing number of effective brake cylinders in power brake systems B60T17/10

Abstract

A method and apparatus for providing regenerative and friction braking on a vehicle having one or more wheels driven by a drive motor includes a master cylinder (28), a hydraulic control unit (30), a brake control unit (38), a drive motor control unit (52) and a drive motor (18). The drive motor control unit determines a coast down regenerative torque signal and a driver brake command regenerative torque signal and commands the drive motor to regeneratively brake the driven left and right wheels in response to whichever of the coast down regenerative torque signal and the driver brake command regenerative torque signal is greatest, thereby maintaining a desirable proportioning of front to rear braking.

Claims

1. A regenerative and friction braking apparatus for a vehicle having one or more wheels driven by a drive motor, comprising:

a master cylinder for generating a hydraulic signal in response to a driver brake command;

a pressure sensor for generating a pressure signal representative of said hydraulic signal;

a throttle sensor for generating an acceleration signal in response to a driver acceleration command;

an undriven wheel having a first brake actuator;

a driven wheel connected to the drive motor and having a third brake actuator;

a hydraulic control unit in fluid communication with said master cylinder and said first and third brake actuators;

a power storage device in communication with the drive motor;

brake control means for commanding said hydraulic control unit in response to said pressure signal; and

drive motor control means for determining a coast down regenerative torque signal and a driver brake command regenerative torque signal and commanding the drive motor to regeneratively brake said driven wheel in response to whichever of said coast down regenerative torque signal and said driver brake command regenerative torque signal is greatest, thereby maintaining a desirable proportioning of front to rear braking.

2. A regenerative and friction braking apparatus according to claim 1, wherein said coast down regenerative torque signal is determined using said acceleration signal.

3. A regenerative and friction braking apparatus according to claim 1, wherein said driver brake command regenerative torque signal is determined using said pressure signal.

4. A regenerative and friction braking apparatus according to claim 1, wherein said driver brake command regenerative torque signal is equal to the product of the pressure signal and an empirically determined system constant.

5. A regenerative and friction braking apparatus according to claim 1, wherein said drive motor control means selectively reduces said regenerative braking in response to predetermined system conditions and said brake control means increases said hydraulic braking by said third hydraulic actuator, so as to maintain said desirable proportioning of front to rear braking.

6. A regenerative and friction braking apparatus for a vehicle having one or more wheels driven by a drive motor, comprising:

a master cylinder for generating a hydraulic signal in response to a driver brake command;

a pressure sensor for generating a pressure signal representative of said hydraulic signal;

a throttle sensor for generating an acceleration signal in response to a driver acceleration command;

an undriven left wheel having a first brake actuator and a first speed sensor operatively associated therewith;

an undriven right wheel having a second brake actuator and a second speed sensor operatively associated therewith;

a driven left wheel connected to the drive motor and having a third brake actuator and a third speed sensor operatively associated therewith;

a driven right wheel connected to the drive motor and having a fourth brake actuator and a fourth speed sensor operatively associated therewith;

a hydraulic control unit in fluid communication with said master cylinder and said first, second, third and fourth brake actuators, respectively;

a power storage device in communication with the drive motor;

brake control means for commanding said hydraulic control unit in response to said pressure signal and said driven and undriven left and right wheel speed signals; and

drive motor control means for determining a coast down regenerative torque signal in response to said acceleration signal and a driver brake command regenerative torque signal in response to said pressure signal and commanding the drive motor to regeneratively brake said driven left and right wheels in response to whichever of said coast down regenerative torque signal and said driver brake command regenerative torque signal is greatest, thereby maintaining a desirable proportioning of front to rear braking.

7. A regenerative and friction braking apparatus according to claim 6, wherein said driver brake command regenerative torque signal is equal to the product of the pressure signal and an empirically determined system constant.

8. A regenerative and friction braking apparatus according to claim 6, wherein said drive motor control means selectively reduces said regenerative braking in response to predetermined system conditions and said brake control means increases said hydraulic braking by said third and fourth hydraulic actuators, so as to maintain said desirable proportioning of front to rear braking.

9. A method of operating a regenerative and friction braking apparatus for a vehicle having one or more wheels driven by a drive motor and a hydraulic control unit in fluid communication with a brake actuator at each of said vehicle wheels, the method comprising the steps of:

generating a hydraulic signal in response to a driver brake command as applied to a master cylinder;

producing a pressure signal representative of said hydraulic signal;

producing an acceleration signal in response to a driver acceleration command;

determining a coast down regenerative torque signal from said accelerator signal;

determining a driver brake command regenerative torque signal in response to said pressure signal; and

commanding the drive motor to regeneratively brake the driven wheel in response to whichever of said coast down regenerative torque signal and said driver brake command regenerative torque signal is greatest, thereby maintaining a desirable proportioning of front to rear braking.

10. A method for operating regenerative and friction braking apparatus according to claim 9, wherein said driver brake command regenerative torque signal is determined by the taking the product of the pressure signal and an empirically determined system constant.

11. A method for operating regenerative and friction braking apparatus according to claim 9, further comprising the steps of:

selectively reducing said regenerative braking in response to predetermined system conditions; and

increasing said hydraulic braking by said third hydraulic actuator so as to maintain said desirable proportioning of front to rear braking.