US 5,666,807 AGranted

Oil processor circuit

AssigneeCaterpillar Inc.

InventorDonald L. Bianchetta

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Abstract

Oil coolers are commonly used in hydraulic systems for maintaining oil below a preselected temperature under normal operating conditions. The subject oil cooler circuit includes a pilot operated valve disposed in a conduit connecting the hydraulic system to the cooler and an electromagnetic pilot valve connected to one end of the pilot operated valve. The pilot valve is spring biased to its closed position when the temperature of the oil is above a predetermined temperature and is moved to an open position when the oil temperature is at or below the predetermined temperature. The end is vented to a tank at the open position of the pilot valve so that the pilot operated valve is maintained at the closed position to prevent cold viscous oil from being transmitted to the oil cooler when the oil temperature is below the predetermined temperature.

Claims3

Dependent claims

An oil processor circuit having an oil processor connected to a tank and a conduit connected to the oil processor, comprising:

a pilot operated valve disposed in the conduit and having open and closed positions, first and second ends, an orifice communicating pressurized fluid from the conduit upstream of the pilot operated valve to the first end, and a spring disposed at the second end biasing the valve to one of said positions;
a two position electromagnetic pilot valve connected to the first end of the pilot operated valve and being movable to an open position communicating the first end to the tank to establish said one position of the pilot operated valve in response to receiving an electrical control signal;
and
means for sensing the temperature of the oil in the circuit and for outputting the electrical control signal to the electromagnetic pilot valve when the oil temperature is at or on one side of a predetermined temperature.

1 more element

Dependencies are inferred from the claim text.