Back pressure valve
First Claim
1. An improved back-pressure valve for a centrifugal compressor of the type driven by an electric motor which is cooled by refrigerant passing through a motor casing and out to a cooler by way of the valve, wherein the improvement comprises;
- a valve body having an inlet opening formed in one end thereof for receiving a flow of refrigerant from the motor casing and allowing it to pass through said body and out a discharge end to the cooler;
a shaft mounted in said body in alignment with the general direction of refrigerant flow;
a piston mounted on said shaft so as to be positionable between a minimum flow position near the inlet opening upon compressor start-up and a maximum flow position nearer said discharge end when the compressor reaches maximum speed; and
a first biasing means for biasing said piston toward said minimum flow position.
1 Assignment
0 Petitions
Accused Products
Abstract
A shaft-mounted piston is reciprocally disposed on the axis of a valve inlet opening such that increased pressure from within the motor casing of a centrifugal compressor causes the piston to move in the direction of the refrigerant flow, against a biasing means, to increase the flow of refrigerant through the opening, and to thereby regulate the pressure drop across said valve to a predetermined level. The shaft has an extended portion projecting through the piston toward the motor casing such that when the compressor is shut down and the pressure is thus greater in the valve than in the motor casing, the piston can move out of the inlet opening to the extended portion of the shaft to thereby allow the unrestricted flow of refrigerant into the motor casing.
54 Citations
14 Claims
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1. An improved back-pressure valve for a centrifugal compressor of the type driven by an electric motor which is cooled by refrigerant passing through a motor casing and out to a cooler by way of the valve, wherein the improvement comprises;
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a valve body having an inlet opening formed in one end thereof for receiving a flow of refrigerant from the motor casing and allowing it to pass through said body and out a discharge end to the cooler; a shaft mounted in said body in alignment with the general direction of refrigerant flow; a piston mounted on said shaft so as to be positionable between a minimum flow position near the inlet opening upon compressor start-up and a maximum flow position nearer said discharge end when the compressor reaches maximum speed; and a first biasing means for biasing said piston toward said minimum flow position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14)
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11. A method of operating a centrifugal compressor of the type having an electric motor which is cooled by refrigerant passing through a motor casing and out a return line, comprising of the steps of;
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providing a pressure responsive valve in the return line such that the flow of refrigerant from the motor casing to the return line is automatically regulated in such a manner as to maintain a predetermined pressure drop across said valve during normal operation of the centrifugal compressor; and when the compressor is shut down, providing for the relatively unrestricted flow of refrigerant gas from the return line, through the valve, and into the motor casing. - View Dependent Claims (12)
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Specification