Abstract: A vehicle engine driven helical screw compressor for a gas refrigeration system includes a slide valve actuator for shifting the compressor slide valve to load and unload the compressor. In addition to a first solenoid operated control valve selectively connecting the slide valve actuator to compressor high side pressure to effect loading of the compressor and a second solenoid operated control for connecting the slide valve actuator to the compressor low side pressure to effect unloading, a tracking valve responsive to engine acceleration and deceleration connects the slide valve actuator to the low side pressure during engine acceleration for immediate unloading of the compressor and connects the slide valve actuator to the high side pressure during engine deceleration to immediately load the compressor.

Abstract: A check valve within a closed loop refrigeration system isolates the evaporator from the helical screw compressor. A normally open, solenoid operated valve is positioned within an unload line having one end coupled to a drive cylinder outboard chamber to the side of the piston opposite an inboard chamber which opens to compressor discharge pressure. The other end of the unload line is connected to the system low pressure side, downstream of the check valve. The same drive cylinder outboard chamber opens via a load line to the system high pressure side through a normally closed solenoid operated valve. Upon compressor shut down, the outboard chamber is vented to the system low pressure side, while the opposite side of the unloader drive cylinder piston sees the compressor high side, thus driving the slide valve to full unload position and eliminating the coil spring normally needed to drive the slide valve to that position.

Abstract: A heat exchanger formed by concentric, spaced tubes defining a substantially annular chamber therebetween. There is an internal metallic fin comprising a strip of corrugated sheet metal extending spirally within the annular chamber with the adjacent turns of the spirally formed strip being spaced from each other to provide a spiral passageway between the side edges of adjacent turns. The metallic fin corrugated sheet metal strip bears a plurality of small apertures to significantly improve the boiling heat transfer coefficient.

Abstract: An air source heat pump system incorporating a refrigerant charged bulb within the air flow passing over the outdoor coil of the heat pump system to sense outside ambient air temperature. The refrigerant charged bulb supplies a variable saturated pressure which acts upon a bellows of a control unit whose opposite side is subjected via a second bellows to saturated suction pressure (corresponding to refrigerant evaporating temperature) of the refrigerant returning from the outdoor coil to the inlet of the compressor. The bellows provides a spring load. An electrical switching device responsive to this pressure differential acts to first block unnecessary loading of the compressor and secondly to initiate unloading of the compressor. Additional switching means prevents excessive unloading of the compressor and insures subsequent initiation of loading to prevent liquid logging of the evaporator coil.

Abstract: An electronic control system for sequential actuation of a four-way solenoid valve is used to selectively load and unload a slide valve control for a screw compressor. The electronic control system is responsive to output air pressure and pulses a four-way solenoid valve to selectively load and unload the system so that it will maintain system pressure within a preselected deadband. Selective pulsing of the four-way solenoid valve is used to gate hydraulic fluid to load and unload chambers separated by a piston coupled to a slide valve which shifts longitudinally and changes the capacity of the screw compressor. The control system senses output line pressure, and when a limit pressure is exceeded, a dump solenoid valve and fast-unload system is actuated to entirely unload the system of air pressure until reduced to a level below the set deadband. The control circuit also monitors current to the motor which drives the screw compressor.

Abstract: A multi-cylinder reciprocating compressor is automatically staged at low ambient temperature to improve refrigerant volume flow while facilitating subcooler operation and return of vaporized refrigerant from the subcooler to the inlet of the second stage cylinders of the compressor in the two stage mode. A solar evaporator substitutes for the outdoor coil when the solar heated storage tank temperature exceeds that of ambient. During staging mode, the wrist pins of the low side cylinders and the high side cylinder undergo proper load reversals, since intermediate suction pressure is applied to the wrist pin of the high side cylinders.

Abstract: A solar-assisted multiple source and multiple sink heat pump system for use in residential homes includes a solar/air coil mounted in the attic of the residential home and selectively open to the attic interior with the attic roof bearing a solar window with selective shield permitting the attic solar space to constitute a passive solar collector. The solar/air coil is positioned within duct work which selectively opens to the attic interior or the outside air to permit thermal energy pick up from the attic solar space or outside air or wasting of heat thereto. The inside air coil is also mounted in a separate duct work within the attic shielded from the attic interior but selectively open thereto and to and from the building interior beneath the attic for adding heat to the building interior or removing the same. One or more thermal storage tanks may constitute heat and cold sinks.

Abstract: A helical screw rotary compressor or expander rotatably mounts intermeshed helical screw rotors within intersecting bores of a casing. An axially extending recess provided within the barrel portion of the casing in open communication with the bore bears a slide valve member whose inner face is complementary to the envelope of the casing. The slide valve member controls communication between the working chamber defined by the rotors and the casing to the outlet port and bears means at the end in communication with the outlet port for sensing the closed thread pressure adjacent to the end of the slide valve member closing off the outlet port. Comparison of that closed thread pressure to the outlet port pressure permits controlled shifting of the slide valve member to prevent overcompression and undercompression, when the unit acts as a compressor, or underexpansion or overexpansion when the unit acts as an expander.

Abstract: 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.

Abstract: A compression module in the form of a four cylinder reciprocating piston compressor, having two cylinders for each of two cylinder heads, is interconnected by conduits and manifolds which in turn incorporate solenoid operated control valves and check valves to provide five pressure levels for the compressor cylinders to remove automatically intermediate pressure refrigerant and to return intermediate pressure refrigerant, to achieve single or multiple cylinder compressor staging, and effect unloading of one head by cutting off low pressure suction return to that compressor head.

Abstract: A closed loop refrigeration system such as an air source heat pump includes a hermetic screw compressor and a helical screw rotary expander connected to an electric induction drive motor. The closed loop refrigeration circuit permits an air source evaporator to constitute a heat source for supplying vaporized refrigerant to the compressor and expander, while both are mechanically coupled to the electric induction drive motor and with both driven as compression units. The air source evaporator feeds to slide valve controlled inlet ports of both the compressor and expander. Compressed vapor from both units passes to condenser coil(s) such as heating condensers to increase the system capacity under this mode.

Abstract: A temperature control system for monitoring and controlling a zone supplied with low-pressure steam is disclosed. The system utilizes a series of balanced Wheatstone bridges to provide a variety of automatic and manual control techniques to maintain temperature in the zone. Means are also provided to obtain direct readings of temperature, rate at which heat is being supplied, and the position and movement of a steam control valve which is utilized as a heat metering apparatus. The bridge leg outputs are permanently connected by high impedance coupling circuits which act as voltage dividers to obtain the required resultant control signals. High impedance coupling eliminates the need for control circuit balancing, thereby minimizing required calibrations in actual field use. The sole balancing calibration is with each sensor leg to a centered bridge leg.

Abstract: A multi-cylinder reciprocating compressor is automatically controlled in terms of two speed operation and selective utilization of the cylinders under single stage action to meet heating and cooling loads by way of a two step indoor thermostat and an outdoor thermostat. The compressor may supply energy to storage during heating and cooling or receive energy therefrom with the storage coil selectively loop connected to the outside or indoor coils. Subcooling return is directed to a specific cylinder and overrides refrigerant return vapor to that cylinder from other coils functioning as evaporators. Solenoid operated valves effect unloading of the compressor during start up and automatically effect removal or inclusion of selected cylinders to the single stage compressor operation. Automatic load responsive control of compressor drive motor speed is effected.

Abstract: A compression module may comprise a hermetic helical screw rotary compressor having injection and ejection ports in addition to discharge and suction ports or may comprise a multiple cylinder, multiple level, reciprocating compressor. The module incorporates a subcooler coil and is connected to an outside air coil, a thermal energy storage coil, a direct solar energy supply coil, one or more inside coils for the space to be conditioned and a hot water coil through common, discharge manifold, suction manifold, liquid drain manifold and liquid feed manifold, by suitable solenoid operated control valves and check valves. The solenoid operated control valves are selectively operated in response to system operating parameters. Seal pots and positive displacement pumps may operate to force liquid refrigerant condensed at intermediate pressure to flow to the receiver which is pressurized at a pressure corresponding to the condensation temperature of the highest pressure condensing coil in the system.

Abstract: A helical screw,expander generator system preferably incorporates a hermetic helical screw expander and induction generator unit with the expander incorporated within a closed loop fluid circuit including an expander boiler upstream of the expander and a condenser downstream with the closed loop circuit carrying an organic working fluid, and the expander boiler receiving heat from a solar or reclaim heat source. The expander carries at least one slide valve for controlling expander capacity. Ejection ports may be carried by additional slide valves for ejecting partially expanded working fluid which is fed to first and second stage heat regenerators to preheat the liquified working fluid as it passes from the condenser to the expander boiler to permit cycle efficiency to approach the theoretical Carnot limits of the system.

Abstract: In a vertical hermetic compressor, an inner cylindrical housing coaxially mounted within a sealed outer enclosure, sealably carries at its lower end, paired helical screw rotors defining with the inner housing a screw compressor compression chamber and supports coaxially with one of the screw rotors and constituting an axial extension thereof the compressor electrical drive motor by longitudinally spaced tapered roller bearings. Oil is bled from the sump and fed to the suction inlet tube to the compressor upstream of the working gas filter. Compressed working fluid is discharged axially downwardly with the lower tapered roller bearing assembly providing a minimal high pressure gap between the screw rotor ends and the stationary end plates. Entrained oil from the discharge passage which extends through the electric motor rotor seeks the suction side of the compressor through the upper of the two tapered roller bearing pack assemblies for controlled continuous lubrication of the upper bearing assembly.

Abstract: A positive displacement compressor, such as a helical screw rotary compressor without capacity control element, is coupled in a refrigeration loop main line between the evaporator and an oil separator and upstream of the condensor. To unload the screw compressor at low evaporator load, any refrigerant discharging from the compressor is bypassed by a line connecting the suction and discharge sides of the screw compressor, and main line connection from the evaporator to the screw compressor is shut off such that the driven, unloaded screw compressor pulls oil from the separator through a restrictor and oil injection port and some refrigerant vapor which passes to the evaporator side through the screw compressor bypass line. As the evaporator pressure increases, the evaporator is connected through a restrictor within the main line to the screw compressor suction.

Abstract: A defrost control system includes in an electrical control circuit, a number of relay coils and contacts responsive thereto for insuring a delay in termination of the defrost mode and reverse refrigerant flow to the outdoor coil of the heat pump system to delay coil operation as an evaporator, and to effect automatically fan motor reversal and energization to blow air downwardly over the outdoor coil fins to assist gravity in removing the condensate during delay in initiation of heat pump heating cycle, thereby preventing refreezing of condensate on the coil fins.

Abstract: A liquid injection expansion valve permits liquid refrigerant at high pressure, bled from the condenser, to be injected into the working chamber between the screws and intermediate of the suction and discharge sides of a helical rotary screw compressor for cooling the refrigerant working fluid and the captured oil. A solenoid valve limits bleeding of liquid refrigerant from the condenser at high compressor loads. A thermostat sensing the temperature of the screw compressor discharge, modulates the liquid injection expansion valve downstream of the liquid injection solenoid valve. A compressor unloader slide valve may port oil and the liquid refrigerant into the working chamber. The condenser may be positioned at a height considerably above that of the screw compressor to increase the head of the bled liquid refrigerant to a pressure higher than the screw compressor discharge pressure.

Abstract: In a vertical hermetic compressor, an inner cylindrical housing coaxially mounted within a sealed outer enclosure, sealably carries at its lower end, paired helical screw rotors defining with the inner housing a screw compressor compression chamber and supports coaxially with one of the screw rotors and constituting an axial extension thereof the compressor electrical drive motor by longitudinally spaced tapered roller bearings. Oil is bled from the sump and fed to the suction inlet tube to the compressor upstream of the working gas filter. Compressed working fluid is discharged axially downwardly with the lower tapered roller bearing assembly providing a minimal high pressure gap between the screw rotor ends and the stationary end plates. Entrained oil from the discharge passage which extends through the electric motor rotor seeks the suction side of the compressor through the upper of the two tapered roller bearing pack assemblies for controlled continuous lubrication of the upper bearing assembly.