Abstract: A dual position pilot operated valve assembly having a main piston, with a valve member, reciprocable within a valve body, wherein the valve body is adapted for sealingly mating with a valve seat and passage located intermediate the valve body inlet and outlet ports, the valve body having a cylindrical adapter secured to an open end thereof and housing a secondary piston, reciprocable therein, with an axial stem depending from the second piston bottom surface and extending through the adaptor to the first piston cavity for intermittent contact therewith; and an end cap secured to and closing the adapter and having an inlet port interconnected with a source of high pressure control gas and respective first and second conduits leading to the main and secondary piston bore cavities, with an adjustment mechanism controlling the degree of opening/closing of the valve assembly. Several methods of operation are also set forth.

Abstract: A metering solenoid valve is provided for refrigeration applications, wherein the metering solenoid valve combines the function and characteristics of a solenoid valve and a hand expansion valve into a single valve. The valve includes an adjustable stem housing allowing the flow of the valve to be adjusted.

Abstract: A dual position pilot operated valve assembly having a main piston, with a valve member, reciprocable within a valve body, wherein the valve body is adapted for sealingly mating with a valve seat and passage located intermediate the valve body inlet and outlet ports, the valve body having a cylindrical adapter secured to an open end thereof and housing a secondary piston, reciprocable therein, with an axial stem depending from the second piston bottom surface and extending through the adaptor to the first piston cavity for intermittent contact therewith; and an end cap secured to and closing the adapter and having an inlet port interconnected with a source of high pressure control gas and respective first and second conduits leading to the main and secondary piston bore cavities, with an adjustment mechanism controlling the degree of opening/closing of the valve assembly. Several methods of operation are also set forth.

Abstract: A dual position pilot operated valve assembly having a main piston, with a valve member, reciprocable within a valve body, wherein the valve body is adapted for sealingly mating with a valve seat and passage located intermediate the valve body inlet and outlet ports, the valve body having a cylindrical adapter secured to an open end thereof and housing a secondary piston, reciprocable therein, with an axial stem depending from the second piston bottom surface and extending through the adaptor to the first piston cavity for intermittent contact therewith; and an end cap secured to and closing the adapter and having an inlet port interconnected with a source of high pressure control gas and respective first and second conduits leading to the main and secondary piston bore cavities, with an adjustment mechanism controlling the degree of opening/closing of the valve assembly. Several methods of operation are also set forth.

Abstract: A valve assembly having a valve body, a piston, a modulating plug, a valve cover adjoining the valve body, and a throttling member. The valve body has an inlet and outlet port, a partition with a valve seat separating the valve body into a first and second flow passage. The piston has a throughbore including an orifice, reciprocably mounted in the valve body and movable between a first and second position. The modulating plug, in abutting contact with the piston and reciprocably mounted in the valve body, gradually moves between an open position, permitting a main fluid flow, and a closed position engaging the valve seat, blocking the main fluid flow. The throttling member is adapted to insure a gradual alteration of the cross-section of the orifice upon piston movement. A method of gradually opening the valve assembly modulating plug is also set forth.

Abstract: A valve assembly comprised of a valve body, a piston, a modulating plug, a valve cover adjoining the valve body, and a throttling member. The valve body has an inlet and outlet port, a partition with a valve seat separating the valve body into a first and second flow passage. The piston has a throughbore including an orifice, reciprocably mounted in the valve body and movable between a first and second position. The modulating plug, in abutting contact with the piston and reciprocably mounted in the valve body, gradually moves between an open position, permitting a main fluid flow, and a closed position engaging the valve seat, blocking the main fluid flow. The throttling member is adapted to insure a gradual alteration of the cross-section of the orifice upon piston movement. A method of gradually opening the valve assembly modulating plug is also set forth.

Abstract: A rotary compressor is provided that has a housing including a bore, bearings, a low pressure end having a low pressure inlet and a high pressure end having a high pressure outlet. A rotor is rotatably mounted by the bearings in the bore and has an end face subject to a variable axial thrust force; and a plurality of compression chambers having a low pressure, a high pressure and intermediate pressures. A piston is provided for exerting a counterbalancing force on the rotor in opposition to the axial thrust force at the high pressure end of the compressor. An intermediate pressure port is provided in communication with the intermediate pressure chamber. A conduit is connected between the piston and the intermediate pressure port which varies according to suction pressure to cause the piston to apply a variable counterbalance force on the rotor through the output range of the compressor.

Abstract: In a disc-type stop valve, a valve disc located at the lower end of a rotatable valve stem takes the form of a solid cylindrical metal member having an annular groove formed around the periphery of its lower surface in which an annular resiliently deformable plastic seal ring is disposed. The seal ring is held in place by a smaller-diameter circular metal retainer plate which is secured by bolts against the lower surface of the valve disc and against the underside of seal ring. When the valve is closed, a circumferential lower edge of the seal ring bears against a conically-shaped annular metal valve seat surface in the valve body. A large-diameter resilient compressible conventional O-ring is disposed in an annular space defined by the rear side of the retainer plate, the annular inner edge of the seal ring and a chamfered edge along the intersection of the lower surface and the side edge of the valve disc.

Abstract: An oil separator operates to remove oil entrained in a refrigerant being circulated in a refrigeration system, especially a system using a screw-type compressor. The oil separator generally comprises a vessel having a chamber therein and a perforated plate on which oil coalescing elements are mounted divides the chamber into a lower primary oil separator section and an upper secondary oil separator section. A mixture inlet pipe extends through a side of the tank into the lower section for admitting a pressurized mixture of refrigerant and oil. A refrigerant gas outlet port is provided in the upper section for expelling refrigerant from which the oil has been separated. An oil outlet port is provided in the lower section for expelling oil collected in an oil sump at the bottom of the lower section.

Abstract: A method is disclosed for operating a large motor-driven refrigeration gas compressor which has independently movable suction and discharge slide valves to prevent undesirable, possibly damaging hydraulic pressure build-up caused by sealing oil remaining in the gas compression chambers during compressor start-up. While the compressor is started and brought up to full speed, the suction slide valve is disposed in fully unloaded position to fully open the gas suction port and the discharge slide valve is disposed in position to fully open the gas discharge port to enable excess oil in the gas compression chambers to exit freely through the compressor gas discharge port before oil pressure build-up can occur. When the compressor is at full speed, the suction slide valve is positioned to maintain a desired gas suction pressure and the discharge slide valve is positioned to equalize gas pressure between the gas compression chambers and the compressor gas discharge port.

Abstract: A rotary screw gas compressor for a refrigeration system comprises a motor-driven single main rotor having helical grooves and mounted for rotation in a rotor bore in the compressor housing and a pair of star-shaped gate rotors rotatably mounted in the housing and engageable with the helical grooves to define a plurality of compression chambers. A suction slide valve member is slidably positionable (between full load and unload positions) to control where low pressure uncompressed refrigerant gas from a suction port is admitted to the compression chambers to thereby function as a suction bypass to control compressor capacity. A discharge slide valve member is slidably positionable (between minimum and adjusted volume ratio positions) to control where high pressure compressed refrigerant gas is expelled from the compression chambers to a discharge port to thereby control the volume ratio and thereby the input power to the compressor.

Abstract: A refrigeration system comprises a compressor, a condenser, a receiver, an evaporator, and an adjustably controllable expansion valve connected in the refrigerant supply line from the receiver to the evaporator. An electronic control system adjustably controls the expansion valve so as to maintain the maximum amount of liquid refrigerant in the evaporator while preventing flow of liquid refrigerant to the compressor. The electronic control system measures both the actual refrigerant temperature and refrigerant vapor pressure at a common point near the evaporator outlet port, converts the measured vapor pressure to a saturation temperature, determines the differential between the two temperatures and adjusts the expansion valve in accordance therewith, i.e., closing or opening in response to differentials below or above a set point, respectively.

Abstract: A multi-cylinder single-stage rotary rolling piston type gas compressor comprises four modular cylinder housings, partitions and end covers bolted together in end-to-end arrangement. Each cylinder housing includes an inner wall which defines a centrally located cylinder chamber and vane slot and an outer wall which defines a suction chamber, a discharge chamber and an oil chamber or reservoir surrounding the cylinder chamber. The four suction chambers are connected together end-to-end to a common gas inlet port. The four discharge chambers are connected together end-to-end to a common gas discharge port. The four oil chambers are connected together end-to-end. An internally lubricated rotor assembly extends axially through the four cylinder chambers and comprises a shaft rotatably supported on the end covers. The shaft has four eccentric crankarms on which four roller pistons are rotatably mounted, one for each cylinder chamber. The two central pistons are angularly displaced 180.degree.

Abstract: The invention relates to improvements in a refrigeration system having an oil cooled screw compressor from which mixed oil and compressed refrigerant issues to an oil separator via a discharge duct, and wherein a refrigerant pump draws liquid refrigerant from the high pressure receiver and delivers it to the discharge duct to cool the oil and desuperheat the refrigerant. The refrigerant pump and a hydraulic motor that drives it are in a single sealed housing. The hydraulic motor is energized with pressure oil from the oil pump whereby oil is returned to the compressor from the oil separator. Oil flow to the hydraulic motor is throttled in accordance with output from a temperature sensor at the discharge duct, to maintain a constant temperature of oil-refrigerant mixture passing to the oil separator. A standpipe arrangement prevents cavitation at the refrigerant pump.

Abstract: In a large refrigeration system comprising a screw compressor of controllably variable output, compressor lubricating oil, discharged from the compressor in a mixture with compressed refrigerant, is separated from the refrigerant at an oil separator from which it is returned to the compressor. Compressed refrigerant flows from the separator, through a condenser, to a high pressure receiver, where it is held for circulation through an evaporator and thence back to the compressor.Through a bypass conduit in which a small liquid refrigerant pump is connected, condensed refrigerant from the receiver is delivered to a duct communicating the compressor discharge outlet with the oil separator inlet, to cool the oil-refrigerant mixture before it enters the separator. A thermostat senses temperature of that mixture near the separator inlet and so controls a throttling valve in the bypass conduit as to maintain that temperature substantially constant.

Abstract: In a refrigeration system wherein compressed refrigerant flows from a compressor discharge chamber successively through an oil separator and a condenser to a high pressure receiver, a minor portion of the condensed refrigerant that enters the high pressure receiver is passed through a pump by which its pressure is raised to above that of compressed refrigerant at said discharge chamber. From the pump the refrigerant is passed through an oil cooler in indirect heat exchange with compressor lubricating oil and is then released into the discharge chamber where it desuperheats the compressed refrigerant, thereby also cooling the compressor itself and increasing the effectiveness of the oil separator. The rate of flow of such refrigerant through the oil cooler is controlled to maintain a desired temperature of refrigerant flowing from the discharge chamber to the oil separator.

Abstract: A variable capacity rotary screw compressor driven by an electric motor and having an adjustable slide valve for varying compressor capacity is provided with a control system for adjusting the slide valve to regulate compressor capacity and thereby maintain a variable system condition, such as gas inlet or outlet pressure or temperature, within a predetermined range. The control system comprises first means including a current transformer for sensing changes in motor current as compressor capacity varies and a current converter connected to the current transformer for providing a first electrical signal proportional to compressor capacity. The control system also comprises means for sensing changes in the particular system condition being monitored and for providing a second electrical signal proportional thereto.