Fluid-pressure and analogous brake systems – Electric control
Reexamination Certificate
2000-02-24
2002-06-18
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Electric control
Reexamination Certificate
active
06406102
ABSTRACT:
BACKGROUND
1. Field of the Invention
This present invention relates to a system and method for control of electrically operated parking brake-by-wire systems, and more particularly to a method and system for controlling the operation of electrically operated parking brake-by-wire systems that interfaces with various elements and systems of a motor vehicle which is capable of processing information obtained from vehicle Systems, parking brake by wire systems, and the driver/user; and using this information to prevent inadvertent and/or inappropriate operation of the parking brake-by-wire system, alerting the driver/user to potential problems associated with operation of the parking brake-by-wire system and related vehicle systems.
2. Background of the Invention
With the advent of parking brake by wire systems, parking brake systems that are engaged/disengaged by an electrical contact closure, inadvertent operation or operating the system at an inappropriate time could result in loss of control of the vehicle due to a lock-up condition of the parking brake axle, which is normally the rear axle. Parking brake activator systems such as systems described in U.S. Pat. No. 5,004,077 of Carlson et al., titled Electromechanical Parking Brake System, and U.S. Pat. No. 5,180,038 of Arnold et al., titled Electronically Controlled Parking Brake System, provide the force/power to operate a conventional mechanically operated parking brake system. These systems do not use conventional foot or hand operated controls but have electromechanical devices (motors) for operating the control mechanism (hand lever or foot pedal) for the driver/user.
Generally, prior art exists with regard to the following areas: 1) Control and Interface systems between parking brake(s) and Stop Lights; 2) Control Systems for electrically operated Parking Brakes; 3) Electronic/Electric Parking Brake(s); and 4) Illumination Systems/Designs for Shift Position Indicators.
Information on vehicle systems is available in the following reference books: 1)Modern Automotive Technology by James E. Duffy, 1994; 2) Chilton General Motors Chevy/GMC Pickups and Suburban 1980-87 Repair Manual; 3) Chilton General Motors Full-Size Trucks 1988-96 Repair Manual, and 4) Automotive Electronics Handbook by Ronald Jurgen, 1994.
True parking brake-by-wire systems such as described in U.S. Pat. No. 5,443,132 of Arnold, titled Magnetic Latch Mechanism and Method Particularly for Brakes, describe a self-contained system built into the wheel assembly that is attached to the axle. This system contains an activation mechanism and a parking brake system which share common components with the service brake system designed/built into the wheel assembly on an axle. This system only requires an electrical controller/driver (power supply and switch) for operation.
Currently, there are no viable systems that adequately control the operation of the new generation of parking brake-by wire-systems to allow the static parking brake system to operate safely in a dynamic environment. Designs of parking brake systems have tended to focus on the static designs and operation of the parking brake system, as opposed to emergency brake systems designed for dynamic operation.
The early generation of parking brake-by-wire systems were digital in nature either being fully On (i.e., applied), or fully Off (i.e., released). Parking brake-by-wire systems, electrically operated parking brake systems, such as the Magnetic Latching Parking Brake (MLPB), and other systems, such as that described by U.S. Pat. No. 5,443,132, titled Magnetic Latch Mechanism and Method Particularly for Brakes, and U.S. Pat. No. 5,180,038 of Arnold et al., titled Electronically Controlled Parking Brake System, provide the force/power to operate a conventional parking brake system. These systems do not use conventional foot or hand operated controls but have electromechanical devices (motors) for operating a control mechanism for the driver/user only requiring a switch contact closure and associated power source to operate, engage/disengage the parking brake.
Early parking brake-by-wire systems were either “Fully On” or “Fully Off” and often lacked user/driver intervention/control and provided the user/operator with little or no feedback pertaining to the use, operation, or status of the system. These systems, with their digital operating nature, present some very interesting problems relating to operation of the system when the vehicle is moving or in a dynamic operating mode. For example, most systems currently do not allow modulation, partial application, or other control of the rate of application, which is necessary to stop a moving vehicle without causing ‘lock-up’ of the braking wheels of the parking brake system (typically the rear axle).
In contrast, the second or the new generation of parking brake-by-wire systems is capable of being modulated or partially applied to provide a controlled amount of braking. However, even with this new generation of parking brake by-wire-systems, inadvertent operation of the parking brake system can lead to unexpected braking, resulting in loss of control of the vehicle or rear-end collisions due to the lack of an interface between the parking brake-by-wire system and the stop/brake lights. Emergency situation brake requirements (service brake failure) must prevent total lock out of these parking brakes by wire systems, which would otherwise prevent their engagement during dynamic operation and thus eliminate ‘emergency brake’ function.
In the prior art, as long as this type of system is used as a ‘static’ parking brake and is not intended to function as a ‘dynamic’ emergency brake, these designs and control systems and operating switches are sufficient so long as the braking system is locked-out or prevented from engaging when the vehicle is moving. However, in the rare occurrence of service brake failure, these systems need to be available as an emergency brake or dynamic brake. The lack of control of the amount of brake application force of these digital type systems has not gained acceptance by major automotive or the driver/user and generally have not been produced for vehicles.
There remains a need for a control system for a parking brake-by-wire system that interfaces with the various elements and systems of a motor vehicle; processes various information obtained from vehicle systems, parking brake-by-wire systems, and the driver/user; and uses this information to safely control the operation of the parking brake-by-wire system, alerting the driver/user to potential problems associated with operation of the parking brake-by-wire system and related vehicle systems.
Conventional brake systems contain: 1) a force/energy management converter (an initiator or parking brake pedal/lever); 2) a linkage or force transfer unit (conventional brake cables); 3) an activator (brake arm); and 4) brake, friction. The driver/user activates the parking brake pedal or lever which generates cable tension on the brake cables. These cables are connected to a brake arm at the drum or disc which applies the friction brake. This cable tension causes the brake arm to exert pressure on stationary friction material which then contacts the drum/disc holding the vehicle in place (if the vehicle is stopped). If the vehicle is moving, this static brake can be used to stop or slow the vehicle.
Brake-by-Wire Systems, whether service or parking brake, have similar components/functional elements. These functional elements are: 1) an initiator (switch operator); 2) driver (electronics control unit/module); 3) force generating system (energy pack-motor/gear-box, hydraulics, etc.); 4) force transfer system (cable, linkage, etc.); and 5) mechanical brake (friction). The initiator or switch operator provides the contact information to an electrical driver that controls/conditions electrical power that is used by the force generating system which converts electrical energy into mechanical force. The force transfer unit transfers the force generated/produced by the force generating system (mo
Bednarek Michael D.
Oberleitner Robert J.
Orscheln Management Co.
Pezzlo Benjamin A.
Shaw Pittman LLP
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