Fluid-pressure and analogous brake systems – Locks
Reexamination Certificate
2000-11-28
2002-09-17
Dickson, Paul N. (Department: 3613)
Fluid-pressure and analogous brake systems
Locks
Reexamination Certificate
active
06450587
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to braking systems for vehicles. More particularly, this invention relates to a control system for automatically applying and “locking” a vehicle brake in an applied condition during times when it is not safe for the vehicle to move. The invention may be adapted for use with brakes of various types, for example, air parking brakes or mechanical parking brakes, or by adapting a hydraulic “application” brake, an air “application” brake, or an electric brake to serve as a parking brake. The automatic application and locking of a vehicle brake may be actuated by signals from various sensors/switches inside and outside the vehicle.
2. Related Art
Commercial and public transportation vehicles typically utilize the following types of conventional brakes:
1) Air parking brakes utilize an air-controlled spring system that cooperates with the brake shoes of a vehicle's back wheels. Air parking brake systems exist in commonly-used commercial vehicles, such as trucks, commercial buses, or school buses. The air parking brake system comprises an air source, the spring mechanism, and an air control valve called an “air loading valve” between the air source and the spring mechanism. The air loading valve is controlled only by a manual handle, which is in the vehicle cab on the dashboard or in other positions accessible to the operator. The loading valve manual handle works in a “Pull To Apply” and “Push To Release” manner. Pulling the handle closes the air loading valve, whereby air pressure from the air source is blocked and downstream air pressure is vented so that the springs move to a position that applies the brake. Pushing the handle opens the air loading valve and closes the vent, whereby air is supplied to the spring mechanism so that the springs move to a position that releases the brake.
2) Air application brakes, sometimes called “foundation brakes,” are the conventional means, in vehicles with air brakes, to slow and stop the vehicle, for example, during normal “stop and go” driving. The “air application brakes” are operated by a foot-actuated air control valve, which allows incremental application of the brakes depending on how far the operator has pushed on the foot pedal.
3) Mechanical parking brakes utilize a mechanical linkage or a cable, to operatively connect a manual handle in the vehicle cab either to brake shoes at the rear wheels, or to external brake bands or internal brake shoes working with a brake drum mounted on the drive line. The manual handle is typically either a pull-on hand-operated handle, or a push-on foot-operated pedal.
4) Hydraulic “application” (or “foundation”) brakes are the conventional means, in vehicles with mechanical parking brakes, to slow and stop the vehicle during normal driving. A hydraulic application brake system typically comprises a master brake cylinder for applying hydraulic force to brake shoes at the wheels, and a manual foot-pedal for actuating the master cylinder. Pushing on the brake pedal causes the brake cylinder to increase the fluid pressure in the line to the brake shoes at the wheel, which inhibits the rotation of the wheel to a incremental amount depending on how far the operator has pushed on the brake pedal. When the pedal is released, the master cylinder retracts to reduce or eliminate the pressure in the brake line, disengaging the brake shoe pads from contact with the brake drum and thereby allowing unhindered rotation of the wheel. Hydraulic application brakes are used in most family cars, sport utility vehicles, pick-ups, vans, and larger vehicles such as some school buses.
Regarding Vehicle Movement during Unsafe Conditions
Conditions may exist in or around a vehicle that make it unsafe for the vehicle to be in motion. Conventional safeguards against vehicle movement when such a condition exists are inadequate, at least in part because the safeguards typically depend on the driver taking appropriate action. This invention, without requiring driver action or involvement, automatically detects such conditions and automatically applies or locks the brakes, thereby preventing potentially unsafe vehicle movement.
Vehicle movement when conditions exist that potentially make such movement unsafe are generally the result of (1) the driver's failure to properly apply or engage the parking brake or application/foundation brake system, (2) a third party's intentional release or interference with the parking brake, or (3) the driver's failure, whether intentional or inadvertent, to detect and/or react to conditions which may make vehicle movement unsafe.
Examples of potentially dangerous conditions where movement of a vehicle may be unsafe include but are not limited to the following:
A driver leaves a vehicle, or is otherwise not in a position to safely operate the vehicle and fails to properly set the parking brake.
A driver attempts to put a vehicle in motion when people are attempting to enter or leaving the vehicle.
A driver attempts to put a vehicle in motion with a door open, wheel chair ramp in use, luggage compartment unlatched, or other equipment similarly not in a safe operating mode.
A driver puts a vehicle in motion when an object is in close proximity creating the potential for a collision. Examples include a driver failing to notice a pedestrian stepping in front of a bus or a child playing behind a parked car.
A driver's ability to recognize the existence of an unsafe condition is impaired. Examples include radio noise masking the warning whistle of a train at a railroad crossing, a driver who is intoxicated, or a passenger who has not fastened safety restraints.
A vehicle that is approaching too close to an object, such as a truck backing up to a loading platform.
A vehicle with equipment that has failed or is not within acceptable safety ranges, such as loss of tire or oil pressure.
An unauthorized driver is attempting to move or steal the vehicle.
Patent Literature
There are instances of parking brake locking systems in the patent literature, but none are as effective and safe as that of the present invention. None of the prior art locking systems includes the comprehensive safety features of the present invention.
There are inventions for the automatic engagement of parking brakes upon the turning off of an ignition or engine key switch. U.S. Pat. No. 5,624,352 (Smale) discloses an “ignition-controlled parking brake interlock.” This lever and latch interlock invention is activated by turning off the vehicle ignition key. U.S. Pat. No. 5,675,190 (Morita) discloses an “operating apparatus for parking brake and method for releasing parking brake.” The Morita invention uses a combination of the vehicle ignition key switch, with ON-OFF positions, and a three-way parking brake switch with ON-OFF-RESET positions, to engage the parking brake. A drawback of the Morita invention is the complexity incumbent in the use of its multiple switches.
U.S. Pat. No. 4,519,653, issued to Smith, discloses an anti-theft lock device, which includes a solenoid for attachment to the outer end of a conventional loading valve. When de-energized, the solenoid moves a lock member into the path of the valve actuating member of the conventional loading valve, physically blocking the actuating member so that it cannot be pushed in to disengage the parking brake. If the conventional loading valve has been disengaged prior to de-energizing of the solenoid, then the solenoid and its lock member are ineffectual, in that the lock member merely slideably contacts the side of the valve actuating member in a non-interfering relationship, and, hence, does not apply the brake or have any effect on the brake. Thus, the Smith device may be used as an anti-theft device, after the driver has manually pulled on the brake and turned off the ignition, but it does not have the automatic emergency safety features of the present invention.
Brooks, U.S. Pat. No. 5,553,795, illustrates a safety system with seat and door control. Brooks includes circui
Hamilton Noble
MacGregor G. David
Maslonka Dale
55 Brake Company
Bartz C. T.
Dickson Paul N.
Pedersen Barbara S.
Pedersen Ken J.
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