Refrigerant flow control employing plural valves

Claim 2

In a refrigerant system comprising a refrigerant compressor, refrigerant condenser, and refrigerant evaporator arranged in a closed loop circuit: the improvement comprising a first thermostatically operated metering means located between the condenser and evaporator, said metering means including a first thermostatic operator responding to evaporator temperature to maintain a substantially constant temperature therein; and a second thermostatically operated metering means located in the suction line between the evaporator and compressor, said second metering means including a second thermostatic operator responding to suction line temperature to maintain a substantially constant superheat; the thermostatic operator for each metering means being responsive solely to refrigerant temperature and being unaffected by refrigerant pressure.

Claim 3

The system of claim 1 wherein the first thermostatic operator is thermally engaged with refrigerant entering the evaporator.

Claim 4

The system of claim 1 wherein the first thermostatic operator comprises a contained mass of solid thermal expansion material changeable to the liquid state over a temperature range to maintain the evaporator at a first relatively low temperature; the second thermostatic operator comprising a contained mass of solid thermal expansion material changeable to the liquid state to maintain the second operator at a second relatively high temperature different than the first temperature.

Claim 5

The system of claim 1 wherein the first metering means comprises a thermostatic operator thermally engaged with refrigerant entering the evaporator, a port directing refrigerant across the thermostatic operator, and a valve element connected with the operator to regulate flow through the port; said operator and valve element being oriented to the port so that temperature decrease in the operator causes the valve element to enlarge the flow path through the port, and temperature increase in the operator causes the valve element to restrict the flow path through the port.

Claim 6

The system of claim 1 wherein the first metering means comprises a valve casing having a port-forming means therein defining a high pressure chamber communicating with the condenser and a low pressure chamber communicating with the evaporator; a valve controlling flow through the port; and a thermostatic operator for moving the valve to thus regulate refrigerant flow through the port in accordance with the operator temperature; said thermostatic operator comprising a piston-container assembly disposed in the low pressure chamber so that refrigerant flows past the container as it moves toward the evaporator, and a mass of solid thermal expansion material contained within the container for producing an operating force on the piston; said expansion material undergoing a change to the liquid state over a range of temperatures spanning the boiling temperature of the refrigerant while in the evaporator.

Claim 7

The system of claim 5 wherein the port-forming means comprises a fixed partition having a relatively large pressure-equalizer opening therethrough, and a floating member having a relatively small flow control port therethrough; said floating member being arranged to close said opening during normal run periods, and said thermostatic operator being effective to move the floating member away from the opening at shutdown of the system so that system pressures are equalized through the opening.

Claim 8

The system of claim 1 wherein the first metering means comprises a thermostatic operator thermally engaged with liquid refrigerant entering the evaporator; said operator having a force capability substantially greater than pressures existing in the high side of the system, whereby the operator is insensitive to system pressure variations.

Claim 9

The system of claim 1 wherein the first metering means defines a relatively small volumetric flow orifice when its operator is at evaporator design temperature, and the second metering means defines a relatively large volumetric flow opening when its operator is at design superheat.

Claim 10

The system of claim 1 wherein the second metering means comprises a valve casing having a port-forming means therein defining an inlet chamber communicating with the evaporator and an outlet chamber communicating with the compressor; a valve element controlling flow through the port; and a thermostatic operator for moving the valve to thus regulate flow through the port in accordance with the operator temperature; said thermostatic operator comprising a piston-container assembly disposed in one of the chambers so that refrigerant flows past the container as it moves through the casing, and a mass of solid-liquid thermal expansion material contained within the container for producing an operating force on the piston due to change of state between the solid and liquid conditions; said operator and valve element being oriented to the port so that temperature decrease in the expansion material causes the valve element to restrict the flow path, and temperature increase in the expansion material tends to enlarge the flow path.