Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1998-08-19
2001-10-23
Butler, Douglas C. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303S069000, C303S015000
Reexamination Certificate
active
06305759
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the art of braking systems, and more particularly to a trailer antilock brake system (ABS) modulator valve. The invention is particularly applicable to a tractor-trailer type vehicle equipped with an air braking system in which a vehicle operator generates a control signal to operate a brake control valve. The signal is transmitted to relay valves which, in response, communicate compressed air from storage reservoirs to vehicle brakes. It will be appreciated, however, that the invention may relate to similar environments and applications.
ABS brakes for these types of systems typically include an impermeable or solid walled piston or flexible diaphragm that selectively moves during normal service braking to establish communication with an exhaust passage. Although providing for effective normal service braking, the control line and control volume disposed on one side of the piston or diaphragm of an ABS modulator is less frequently in communication with an ABS exhaust passage. Since air is involved, moisture is always an attendant consideration. In other words, moisture can build up and remain in the control volume. Since ABS braking is less frequently used, the potential exists for blockage to occur at the ABS exhaust passage which is not desirable. The exhaust passage is necessarily exposed to ambient conditions such as ice, mud, etc., and if the exhaust passage is not frequently used, the passage could be less effective than desired.
On the other hand, normal service braking is frequently and necessarily employed. The separate exhaust passage associated with normal service braking in known vehicles has less problems associated with ice or mud since, whenever a brake application is released, the exhaust passage is used and likewise ice or mud expelled therefrom.
Known modulators also have an extended or longer exhaust passage since separate exhaust passages were used for normal service braking and ABS control events. Longer exhaust passages result in reduced response time during normal service braking.
Alternatively, known ABS braking systems for tractor trailer type vehicles are commercially successful and have been widely adopted and accepted in the industry. Thus, any improvement that addresses these concerns would necessarily be attractive if can be easily incorporated into the existing structure without substantial modification.
SUMMARY OF THE INVENTION
The present invention contemplates a new and improved ABS modulator for a tractor trailer that has direct exhaust and control line and control volume drain capabilities and which overcomes all of the above-referenced problems and others in a simple, economical manner that is achieved without drastic modification of the existing structure.
According to the present invention, a valve member received in a valve assembly housing is movable between first and second positions to control communication between the supply port, delivery port, and exhaust port. A solenoid valve assembly associated with an ABS feature communicates with a common exhaust to improve quick exhaust during normal service braking and improve exhaust during an antilock braking event.
According to another aspect of the invention, the solenoid valve assembly communicates with the exhaust port through the valve member.
According to still another aspect of the invention, a portion of the antilock braking system is in constant communication with the exhaust port.
According to yet anther aspect of the invention, the solenoid valve assembly is a non-flow through arrangement where only one end thereof is in communication with the system pressure.
A principal advantage of the invention is the ability to provide a direct exhaust for the ABS modulator.
Another advantage of the invention resides in the ability to drain the control line or control volume associated with the ABS modulator, particularly on a more frequent basis.
Still another advantage of the invention is the improved exhaust during ABS mode of braking.
Yet another advantage of the invention is associated with the common control exhaust for the solenoid valve assembly.
Still other advantages and benefits of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description.
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Herbst Robert J.
Ho Thanh
AlliedSignal Truck Brake Systems Company
Butler Douglas C.
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