Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1999-04-22
2001-06-19
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303S007000, C303S123000, C303S127000
Reexamination Certificate
active
06247764
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a full-function brake valve for use in fluid pressure braking systems that are primarily employed on the semitrailers of heavy duty highway tractor-trailer vehicle combinations. More particularly, the invention relates to a full-function relay brake valve combining the functions of multiple separate brake valves to control the brakes of axles that are exempt from spring brakes on semi-trailers, including multiple axletrailers.
BACKGROUND OF THE INVENTION
The emergency and service requirements of modern heavy-duty highway tractor-trailer combinations meeting all of the pertinent governmental regulations that are applied to the trucking industry have necessitated installing a plurality of complex semi-trailer brake valve arrangements. The valve arrangements, which have been successfully designed to meet the requirements, are expensive and pose installation and maintenance problems. A system that is typical of the known valve arrangements includes a plurality of valves with multiple complex inter-connections, all designed to carry out multiple requisite brake functions.
One of the functions of the known multiple brake valve systems is a pressure protection valve that maintains pressure in the air supply line between the steering and at least one steerable axle in the event of failure of a pressurized air reservoir of the vehicle. This function is important because it is designed to prevent automatic application of spring brakes that are activated once the pressure in the air supply line drops below a predetermined low pressure.
A further function of the multiple brake systems relates to a check valve arrangement employed on the heavy-duty vehicles to block bleeding of pressurized air from the pressurized air reservoir through an air supply port.
Another function of the brake valve systems is to allow pressurized air from the air reservoir to be applied to the service brakes of the semi-trailers if the main air supply system has failed.
Still another function, which is critical to a modern tandem braking system, is the use of antilock brakes (ABS) during driving and braking operations of the semi-trailers. As known, ABS brakes increase safety by eliminating lockup and minimizing the danger of skidding, thereby allowing the semi-trailers to stop in a straight line. ABS brakes also allow the driver to maintain steering control during heavy braking so the vehicle can be driven to avoid an obstacle or another vehicle. Thus, ABS brakes optimize braking by monitoring the relative speed of the wheels to one another to module brake pressure as needed to control wheel slippage and maintain traction when the brakes are applied.
A tractor-trailer tandem braking system typically employs a multi-port relay valve to control the operation of the service brakes. The relay valve supplies pressurized air to, maintains pressurized air in, and releases pressurized air from the service brake chambers pursuant to control signals that are received from the tractor.
Manifestly, the various valve installations and interconnections accomplishing only partially the above-discussed functions on a multi-axle vehicle are complex, costly, difficult and inconvenient to install, troubleshoot, service, and maintain and otherwise are undesirable from a parts inventory standpoint. Previous efforts to integrate the various valve requirements within a single envelope or housing have not resulted in brake systems that could successfully meet current requirements. Moreover, a single housing enveloping ABS, regular service, and pressure protection valves has not been suggested by the known prior art.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a cost-sensitive and space-efficient tractor-trailer tandem brake system.
Still another object of the invention is to provide a full-function brake valve overcoming the drawbacks of the known prior art.
Yet another object of the invention is to provide within a single envelope an improved full-function brake valve for heavy-duty highway trailer vehicles which performs all of the required functions of the tandem brake system.
Another object of the present invention is to provide a full-function brake valve for heavy-duty trailer vehicles which meets all of the pertinent governmental requirements.
These objects are achieved by a full-function valve of the invention coping with the operating and safety requirements of modern semi-trailers. It meets the requirements of present pertinent Federal Regulations and does so by advantageously integrating various valve functions within a single space-saving and cost-saving envelope or housing, thereby eliminating a complexity of multiple valves and interconnecting lines. Essential to the inventive subject matter is a combination of check, pressure protection, modulator and delivery valves providing quick and reliable drive-away and braking.
The full-function valve according to the invention is formed with a unitary valve body comprising service brake, ABS/control and delivery units. A plurality of ports traversed by respective supply and control air includes service, supply, reservoir, control, delivery, and exhaust air ports. Supply and service ports are formed in a service brake unit, while the rest of the ports are provided in an ABS/control unit of the unitary body of the invention. A plurality of internal passageways within the valve body provides a pressurized fluid communication among the ports.
To differentiate pressurized air that fills the reservoir and actuates the service brakes from pressurized air that controls the relay valve module, the former is known in the art as supply or emergency air, and the latter as control or service air. Only the terms supply and control air are used in this text. Similarly, the respective ports which are provided in the service, ABS/control and reservoir units are referred to as the air supply ports and the air control ports.
The full-function valve of the invention provides a plurality of modes of the tandem brake system. An initial mode corresponding to an at-rest position of the brake system is characterized by the service port being closed. The whole brake system is under atmospheric pressure.
Upon starting the engine of the vehicle, the service unit receives pressurized supply air via a supply air line leading from and pressurized by a conventional compressor. As a result of increasing pressure, the service port opens while a reservoir passage closes, but not before the reservoir is filled up with supply air. The pressurization of the reservoir continues until the sufficient pressure is available at the reservoir to actuate the service brakes. Usually, the pressurized reservoir of the trailer or dally is filled out at the maximum of its capacity, typically, at most, 150 psig. This mode of the brake system corresponds to a cruising mode of the vehicle.
As known, a braking mode of the brake systems is initiated by depressing a brake pedal, which is connected to a conventional compressor commonly known in the art to provide delivery of control air through the supply port to the ABS/control unit. During braking, a modulator piston received in a main chamber is displaced in response to increase of control air pressure and, while moving, it engages and actuates a delivery piston. The delivery piston is so designed that during its displacement a passage providing flow communication between the reservoir and the delivery ports opens. A number of the delivery ports may vary, but according to the preferred embodiment of the invention, the brake system is equipped with four delivery ports.
Once a braking event is over, and the brake pedal is released to minimize the control air pressure upon the modulator piston, the spring-loaded delivery valve forces displacement of the delivery piston in a direction opposite to the initial direction. Pressurized control air escapes through the same passageway that provides delivery of control air to the modulator piston.
The full-function valve according to the invention provide
Haldex Brake Corporation
Oberleitner Robert J.
St.Onge Steward Johnston & Reens LLC
Sy Mariano
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