Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
1999-07-08
2001-02-06
Rivell, John (Department: 3753)
Fluid handling
Systems
Multi-way valve unit
C137S625230, C091S468000
Reexamination Certificate
active
06182697
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
MICROFICHE APPENDIX
Not Applicable.
BACKGROUND OF THE DISCLOSURE
The present invention relates to cartridge valve assemblies, and more particularly, to such cartridge valve assemblies for use in raising and lowering accessories in vehicle hydraulic systems.
On many vehicles, such as lawn and garden tractors, there is a hydraulic system which may include one or more priority functions, such as a power steering system, and one or more ancillary (or auxiliary) hydraulic functions, such as driving a rotary actuator to wind up a winch, or raising and lowering a cylinder to control some portion of the vehicle. For example, on turf equipment, it is common to have a hydraulic cylinder associated with the mower deck, and operable to raise and lower the mower deck, in response to movement of a main control valve.
In most vehicle hydraulic systems of the type described above, conventional spool type direction and flow control valves have been used to control flow to and from such hydraulic accessories. Unfortunately, a typical spool valve assembly adds substantially to the overall cost of the vehicle hydraulic system. This is especially true in the case wherein the auxiliary hydraulic function is a cylinder or some other actuator which requires “load holding” capability. An example would be a lift cylinder for a mower deck, wherein the control valve assembly must be capable of maintaining the lift cylinder at a desired position so that the weight of the mower deck does not cause fluid leakage, thus permitting the mower deck to move downward from its desired position.
In the case of hydraulic functions which require load holding capability, it is typical to provide the control valve assembly with pilot operated check valves. Such check valves are normally effective to provide the load holding capability, but add substantially to the overall cost and complexity, and even the physical size, of the total control valve assembly. This is especially true if the vehicle manufacturer purchases pilot operated check valves which are separate from the main control spool, and must be separately plumbed into the system.
BRIEF SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an improved control valve assembly, especially for use in vehicle hydraulic systems, which overcomes the disadvantages of the prior art.
It is a more specific object of the present invention to provide such a control valve assembly in the form of a cartridge valve assembly, which is able to provide the necessary flow control functions in response to a somewhat conventional manual input.
It is another object of the present invention to provide such an improved cartridge valve assembly which has, integral therewith, load holding capability, but without the need for a separate check valve arrangement.
The above and other objects of the invention are accomplished by the provision of a cartridge valve assembly adapted to be disposed in a valve housing defining a cartridge bore, an inlet port, a tank port, and first and second actuator ports. The cartridge valve assembly includes a sleeve valve fixed within the cartridge bore and a spool valve disposed within the sleeve valve for movement therein.
The improved cartridge valve assembly is characterized by the spool valve being moveable both axially and rotatably within the sleeve valve. The assembly includes means biasing the spool valve toward a neutral axial and rotational position within the sleeve valve, in which the inlet port is blocked from fluid communication with the first actuator port. There is means operable to displace the spool valve in a first rotational direction, away from the neutral rotational position, in response to an input in the first direction, and in a second rotational direction, away from the neutral rotational position, in response to an input in the second direction. The means operable to displace the spool valve includes cam means whereby rotation of the spool valve in the first direction results in axial movement of the spool valve from the neutral axial position toward an axial operating position, and rotation of the spool valve in the second direction results in axial movement of the spool valve from the neutral axial position toward the axial operating position. The spool valve and the sleeve valve, when the spool valve is displaced in the first rotational direction, and is in the axial operating position, provide fluid communication from the inlet port to the first actuator port and from the second actuator port to the tank port. The spool valve and the sleeve valve, when the spool valve is displaced in the second rotational direction, and is in the axial operating position, provide fluid communication from the inlet port to the second actuator port, and from the first actuator port to the tank port.
In accordance with another aspect of the invention, the improved cartridge valve assembly is characterized by the spool valve defining a load holding land in sealing engagement with a seat surface disposed within the valve sleeve. When the spool valve is in the neutral axial and rotational position, the engagement of the load holding land and the seat surface block fluid communication from the first actuator port to any of the inlet port, the tank port and the second actuator port.
REFERENCES:
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patent: 2940476 (1960-06-01), Schultz
patent: 3015344 (1962-01-01), Hausmann et al.
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patent: 3972246 (1976-08-01), Link
patent: 4738279 (1988-04-01), Kropp
patent: 5131431 (1992-07-01), Vullmahn
patent: 5339917 (1994-08-01), Eberhart
patent: 5465755 (1995-11-01), Lapp
patent: 5992454 (1999-11-01), Schrag
patent: 6098647 (2000-08-01), Haussler et al.
patent: 2201277 (1972-01-01), None
Lantsberg Gregory F.
Nelson Peter R.
Parker Scott M.
Eaton Corporation
Kasper L. J.
Rivell John
Schoenfield Meredith H.
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