Dunham-bush

Donald D Schaefer

David N Shaw

Joseph A Gagnon

Sebastian J Gianni

Joseph S Orosz

Anthony J Bianco

A large slide valve member concentrically mounts a small slide valve member or slide stop at one end thereof proximate to a helical screw rotary compressor discharge port with the small and large slide valve members movable as a unit for varying the built in volume ratio of the compressor. The small slide valve member is shiftable independently of the large slide valve member to vary the capacity of the machine. A large diameter cylinder fixedly mounted to the end of the compressor casing remote from an outlet port slidably mounts interiorly a smaller diameter cylinder fixed to the large slide valve via a spindle. The small slide valve is fixed to one end of a piston rod which extends through a bore within the large slide valve member and the spindle and terminates internally of the small diameter sliding inner cylinder and has fixed thereto a piston. Hydraulic fluid supplied to one side of the piston and removed from the other side shifts the small slide valve independent of the position of the large slide valve member. A stepping motor fixed to the outer cylinder has an output shaft fixed to an elongated ball screw mounted for rotation with its axis parallel to the concentric inner and outer cylinders and a cylindrical ball nut concentrically positioned on the ball screw, is flange connected through a slot opening within the side of the fixed outer cylinder, to the outer periphery of the inner cylinder. Bearing balls positioned between opposing screw threads of the ball screw and the ball nut move through a circulating loop such that the inner cylinder and thus the slide stop and the large slide valve member is driven bidirectionally, incremented by the stepping motor.

Screw step drive internal volume ratio varying system for helical screw

A vertical axis hermetic compressor includes an inner cylindrical housing fixed internally of a sealed outer enclosure bearing paired helical screw rotors defining with the inner housing closed thread compressor compression chambers. An electrical drive motor overlies the rotors and is shaft connected to one of the rotors. Compressed refrigerant vapor, where refrigerant is the working fluid, discharges through the motor rotor. A deflector within the top of the outer enclosure such that oil impacted by gas flow discharging axially from the motor adheres to the deflector to provide oil separation. Oil dropping from the deflector into the bottom of the outer enclosure functioning as an oil sump impacts against a two passage parallel flow dual transfer tube including one passage supplying liquid refrigerant from the condenser to the compressor working space for cooling the same through a liquid injection port and within a second passage, intermediate pressure refrigerant vapor injected into the compression process through a vapor injection port. This prevents excessive heating of the working fluid pulsing in the tubes during compression with control valves in the passages leading to the liquid injection and vapor injection ports closed.

Vertical axis hermetic helical screw rotary compressor with discharge

A modular three block assembly provides unloading control for a hydraulic cylinder functioning to variably position a slide valve on a helical screw rotary compressor. A first compressor block is fixedly and sealably mounted within the hermetic compressor outer casing and has through holes leading to a first tube connected to a source of oil under discharge pressure forming the hydraulic fluid for the hydraulic cylinder, a second tube connected to the hydraulic cylinder and a third tube to the suction tube returning low pressure vapor to the compressor suction side. A needle valve block is fixedly mounted to the external face of the compressor block and bears within longitudinal through passages paired needle valves determining the load and unload flow rates for the hydraulic fluid passing through said compressor block through holes. A solenoid valve block face connected to the needle valve block carries a three position solenoid valve assembly for controlling flow through the various passages leading to the internal tubes. Flow distribution plates of gasket material are interposed between the blocks at the block interfaces to seal the block interfaces and to provide lateral flow distribution between the various passages through the blocks interconnecting the tubes and under control of the solenoid valve assembly. Elimination of external tubing insures oil of low viscosity for proper operation at compressor start up and significantly reduces complexity and cost to the control system.

Modular unload slide valve control assembly for a helical screw rotary

A vertical axis hermetic compressor includes an inner cylindrical housing fixed internally of a sealed outer enclosure bearing paired helical screw rotors defining with the inner housing closed thread compressor compression chambers. An electrical drive motor overlies the rotors and is shaft connected to one of the rotors. Compressed refrigerant vapor, where refrigerant is the working fluid, discharges through the motor rotor. Centrifugal force functions as a primary oil separator for oil entrained within the working fluid. An inverted dish deflector underlies a gas discharge port axially within the top of the outer enclosure such that oil impacted by gas flow discharging axially from the motor adheres to the deflector to provide secondary oil separation while the gas passes about the periphery of the deflector to escape through the discharge opening of the outer enclosure. A non-woven plastic mesh pad fixed to the bottom of the deflector acts as a shock absorber for the entrained oil to prevent re-entraining oil in the gas stream in mist form to provide tertiary oil separation thereby reducing oil mist carried by the escaping gas to less than about 0.5 percent by weight. Oil dropping from the deflector into the bottom of the outer enclosure functioning as an oil sump impacts against a two passage parallel flow dual transfer tube including one passage supplying liquid refrigerant from the condenser to the compressor working space for cooling the same through a liquid injection port and within a second passage, intermediate pressure refrigerant vapor injected into the compression process through a vapor injection port. This prevents excessive heating of the working fluid pulsing in the tubes during compression with control valves in the passages leading to the liquid injection and vapor injection ports closed.

Parallel connected compressors are provided with an oil management scheme in which an oil equalization port on one compressor is connected via an oil return solenoid operated valve within a small diameter line to an injection port of a second compressor, and vice versa. When the oil level in one compressor drops to a level sensed by an oil float switch, the oil float switch changes state, the oil return solenoid operated valve is opened, feeding its injection port and energizing a one minute on delay timer. Failure of the oil float switch to reset itself causes the compressor to go off on oil failure, and the oil return solenoid operated valve is closed. If the oil float switch resets itself at any time during the first minute, upon resetting, an off delay timer is energized to keep the oil return solenoid operated valve open for an additional minute, and the compressor continues to operate.

Oil equalization system for parallel connected compressors

A compact, helical screw compressor/expander unit mounted in a vehicle and connected to the vehicle engine driven drive shaft has inlet and outlet ports and a capacity control slide valve and a pressure matching or volume ratio slide valve, respectively, for said ports. A refrigerant loop includes the compressor, a condenser mounted in the path of air flow over the engine and an evaporator mounted in a fresh air/cab return air flow duct for the occupant. Heat pipes thermally connect the cab air flow duct to the engine exhaust system which also bears the vapor boiler. Selectively operated damper valves control the fresh air/cab return air for passage selectively over the evaporator coil and the heat pipes as well as the exhaust gas flow over opposite ends of the heat pipes and the vapor boiler.

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Farmington, CT, United States of America

Donald D Schaefer