Fluid-pressure and analogous brake systems – Multiple systems
Patent
1981-09-11
1984-09-11
Butler, Douglas C.
Fluid-pressure and analogous brake systems
Multiple systems
303 71, B60T 1322
Patent
active
044706405
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
TECHNICAL FIELD
This invention is directed to a control system for a spring applied, pressure released brake for use in a winch and draw-works mechanism such as that used on a pipelayer and more particularly to a control system for selectively staging the pressure to the brake and improving response time.
BACKGROUND ART
In a control system for a brake release on a winch, there are times at which the control valve and associated lines may leak fluid due to their attitude on the vehicle and allow air to fill the void. Upon actuation of the control valve to a metering position, a long pause time results because the oil is being used to fill the lines before the pressure level can be raised to release the brake.
Some types of hydraulic systems use a pressure relief valve or a flow restricting valve in a tank line to provide a back pressure, while others use a source of fluid to provide pressurized fluid to a control line in the system. However, none of these teach using a selective staging of the pressure levels in another source in response to positioning of the main control valve to control the pressure being supplied to the control line, such as, a brake release mechanism. The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the invention, a control system has a spring applied, pressure released brake connected to a first source of pressurized fluid by a control valve. The control valve has an inlet port connected to the source, an outlet port connected to the spring applied, pressure released brake, an exhaust port and a spool movable between a first, intermediate and second positions. At the first position of the spool, the inlet port is blocked from the outlet port and the outlet port is in fluid communication with the exhaust port. At the intermediate position, the inlet port is blocked from the outlet port and the outlet port is blocked from the exhaust port. At the second position, the inlet port is in fluid communication with the outlet port and the outlet port is blocked from the exhaust port. A second source of pressurized fluid is connected to the brake and has a one-way check valve positioned between the second source and the brake and adapted to pass fluid to the brake from the second source and prevent reverse flow. A means establishes a predetermined pressure level in the second source and the brake in response to the spool being moved to the intermediate position.
BRIEF DESCRIPTION OF THE DRAWING
The FIGURE is a partial schematic and diagrammatic representation of an embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to the FIGURE, a control system is generally indicated by reference numeral 10 and includes a first source of pressurized fluid, such as, a pump 12 drawing fluid from a tank 14, a relief valve 15 and a spring applied, pressure released brake 16 in fluid connection with the pump 12. The brake 16 has a brake actuator 17 to apply and release the brake 16. The brake 16 is coupled to a winch and draw-works mechanism 18 by a connection 20. A control valve 22 is positioned between the pump 12 and the brake actuator 17 to selectively control applying and releasing of the brake 16.
The control valve 22 has an inlet port 24 connected to the pump 12 by a conduit 26, an outlet port 28 connected to the brake actuator 17 of brake 16 by a conduit 30 and an exhaust port 32 connected to the winch and draw-works mechanism 18 through conduits 34,35. The control valve 22 has a spool 38 movable between a first, intermediate and second positions 40,42,44 and is spring biased to the first position by spring mechanism 39. At the first position 40, as shown, the inlet port 24 is blocked from the outlet port 28 and the outlet port 28 is in fluid communication with the exhaust port 32. At the intermediate position 42, the inlet port 24 is blocked from the outlet port 28 and the outlet port 28 is blocked from the exhaust port 32. At the second position
REFERENCES:
patent: 3326317 (1967-06-01), Marquardt
patent: 3608435 (1971-09-01), Conabee et al.
patent: 3957315 (1976-05-01), Cummins et al.
patent: 4253540 (1981-03-01), Berg
patent: 4278155 (1981-07-01), Golan et al.
patent: 4320691 (1982-03-01), McWilliams
Golan Kenneth F.
Schneider Marvin L.
Burrows J. W.
Butler Douglas C.
Caterpillar Tractor Co.
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