Motors: expansible chamber type – With motive fluid valve – Pilot valve
Patent
1980-12-19
1983-07-12
Walton, George L.
Motors: expansible chamber type
With motive fluid valve
Pilot valve
13762563, F16K 31122
Patent
active
043924158
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention is directed to pilot operated control valve systems and particularly to those requiring a float condition plus a controlled lowering of a raised load upon loss of pilot pressure.
BACKGROUND ART
Some systems use a signal obtained from the load supporting end of an actuator to supply pressure to the pilot valve in response to the failure of the engine. However these systems do not provide a float condition of operation. Other systems use a make-up valve which can be vented and thus opened to allow fluid to be passed to tank from a load supporting end of an actuator upon failure of the engine. However these systems do not provide an accurate control of the load during lowering because the check in the make-up may not respond quickly enough due to large amounts of fluid flowing therethrough.
A system, such as that in the U.S. Pat. No. 3,840,049 issued to Jesse L. Field, Jr. on Oct. 8, 1974 and assigned to the assignee of the present invention, teaches a system having a float condition and a mechanism for providing a lowering of a load under dead engine conditions, but this system also requires venting behind the make-up and having to control the degree of opening of the make-up during lowering. The system is also more complex in that it requires two different make-up valves and a selector valve responsive to pilot pressure to provide both float and dead engine lower.
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 fluid system has a fluid source, a tank and an actuator. The actuator has a first end and a second load supporting end. A pilot operated control valve having first and second ends is connected to the source and the actuator. A pilot control valve is connected to a source of pilot fluid and the first and second ends of the pilot operated control valve and movable between at least one operating position and a float position. A make-up valve is connected between the first end of the actuator and the pilot operated control valve and has a vent line connected to the make-up valve and the pilot control valve. The vent line is in communication with the tank at the float position of the pilot control valve. A means communicates the second load supporting end of the actuator to the tank through the vent line and the pilot control valve in response to loss of the source of pilot fluid and the pilot control valve being moved to the float position.
BRIEF DESCRIPTION OF THE DRAWINGS
The FIGURE is a schematic of an embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to the FIGURE, a fluid system is generally indicated by reference numeral 10 and includes a fluid source, such as, a pump 12 and a pilot operated control valve 14 connected to the pump 12 by conduit 16. The pilot operated control valve 14 has an inlet port 18 connected to the conduit 16, first and second outlet ports 20,22, an exhaust port 24 and a vent port 26. The pilot operated control valve is movable between first, second and third positions "A", "B" and "C". At the first position "A", the inlet port 18 is blocked from communication with the first and second outlet ports 20,22; the first and second outlet ports 20,22 are blocked from the exhaust port 24; and the vent port 26 is in communication with the exhaust port 24. At the second position "B", the inlet port 18 is in communication with the second outlet port 22, and the first outlet port 20 and the vent port 26 are in communication with the exhaust port 24. At the third position "C", the inlet port 18 is in communication with the first outlet port 20, and the second outlet port 22 and the vent port 26 are in communication with the exhaust port 24.
An actuator 28 having a first end 30 and a second load supporting end 32 is connected to the first and second outlet ports 20,22 of the pilot operated control valve 14, via conduits 34,36 respectively.
A tank 38 is connected to exhaust port 24 of the pilot ope
REFERENCES:
patent: 3568718 (1971-03-01), Wilke
patent: 3805678 (1974-04-01), Bianchetta et al.
patent: 3840049 (1974-10-01), Field, Jr.
patent: 3862643 (1975-01-01), Dezelan et al.
patent: 3987703 (1976-10-01), Latimer
Burrows J. W.
Caterpillar Tractor Co.
Walton George L.
LandOfFree
Control for dead engine lower does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control for dead engine lower, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control for dead engine lower will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-193161