Fluid-pressure and analogous brake systems – Speed-controlled – Regenerative brakes
Reexamination Certificate
1997-10-01
2001-01-30
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Regenerative brakes
C303S113100
Reexamination Certificate
active
06179395
ABSTRACT:
This application is related to co-pending applications, entitled “METHOD AND APPARATUS FOR REGENERATIVE AND FRICTION BRAKING” “METHOD AND APPARATUS FOR PROPORTIONING REGENERATIVE BRAKING” and “METHOD AND APPARATUS FOR REGENERATIVE AND FRICTION BRAKING”, respectively, all filed on Sep. 30, 1997 and assigned to the assignee of the present application.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a method and apparatus for regenerative and anti-skid friction braking of a motor vehicle having an electric drive motor. More particularly, the present invention relates to a braking system that smoothly and efficiently transitions from anti-skid control into wheel speed based proportioning of front to rear braking during regenerative braking.
2. Disclosure Information
The general principle of regenerative braking has been recognized by manufacturers of electric vehicles as a way of increasing the overall efficiency of the vehicle. Regenerative braking seeks to recover as much of the kinetic energy of the vehicle which is normally dissipated as heat through a normal hydraulic friction system by operating the electric motor drive even as a generator and restoring the generated electricity to a battery or other energy storage device. Various methods have been proposed for accomplishing regenerative braking in such electric vehicles, however, these regenerative systems generally require additional hardware above and beyond that normally associated with a hydraulic braking system.
It would therefore be advantageous to provide a regenerative and friction braking system capable of recovering the kinetic energy normally lost through heat generation and dissipation resulting from the use of conventional hydraulic brake systems, including immediately after an anti-skid braking event.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a method and apparatus for providing regenerative and friction braking on a vehicle having one or more wheels driven by a drive motor utilizing hardware from a conventional anti-skid hydraulic friction braking system. The regenerative and friction braking apparatus includes a master cylinder for generating a hydraulic signal in response to a driver brake command and a pressure sensor for generating a pressure signal representative of the hydraulic signal. A throttle sensor is also included for generating an acceleration signal in response to a driver acceleration command.
The apparatus also includes an undriven left wheel having a first brake actuator and a first speed sensor operatively associated therewith for generating an undriven left wheel speed signal as well as an undriven right wheel having a second brake actuator and a second speed sensor operatively associated therewith for generating an undriven right wheel speed signal. Additionally, driven left and right wheels connect to the drive motor and include third and fourth brake actuators and third and fourth speed sensors operatively associated therewith for generating driven left and right wheel speed signals.
A hydraulic control unit is provided and is in fluid communication with the master cylinder and the first, second, third and fourth brake actuators, respectively.
The apparatus further includes a power storage device in communication with the drive motor.
A brake controller is included for generating a transition signal responsive to exiting an anti-skid control mode and entering a wheel speed based proportioning with regenerative braking control mode and reducing the hydraulic signal communicated to the third and fourth brake actuators in response to the transition signal.
A drive motor controller is provided for increasing regenerative braking generated by the drive motor in response to the transition signal and the pressure signal.
The method of operating the regenerative and friction braking apparatus for the vehicle comprises 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 the hydraulic signal;
producing an acceleration signal in response to a driver acceleration command;
producing undriven left and right wheel speed signals;
producing driven left and right wheel speed signals;
generating a transition signal responsive to exiting an anti-skid control mode and entering a wheel speed based proportioning with regenerative braking control mode;
modulating the hydraulic signal with third and fourth build and dump valve pairs in response to the transition signal so as to reduce hydraulic braking generated at the driven left and right wheels; and
commanding the drive motor to regeneratively brake the driven left and right wheels in response to the transition, acceleration and pressure signals.
Advantageously, the method and apparatus for providing regenerative and anti-skid friction braking increases the efficiency of such hybrid braking systems to maximize the recovery of kinetic energy normally lost through heat generation and dissipation resulting from the use of conventional hydraulic brake systems using conventional anti skid hardware.
REFERENCES:
patent: 5318355 (1994-06-01), Asanuma et al.
patent: 5378053 (1995-01-01), Patient et al.
patent: 5399000 (1995-03-01), Aoki et al.
patent: 5542754 (1996-08-01), Aoki et al.
patent: 5765929 (1998-06-01), Hirano et al.
Hodges Leslie C.
Kramer Devon
Oberleitner Robert J.
Visteon Global Technologies Inc.
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