Abstract: An oil recovery system for refrigeration apparatus of the type in which an oil lubricated screw compressor is oriented with a suction inlet in communication with an evaporated chamber positioned under the compressor so that under conditions of low capacity compressor operation, lubricating oil may fall from the compressor through the suction inlet thereof and into the evaporator. The recovery system takes advantage of an existing suction distribution tray in the upper region of the evaporator chamber of such systems, normally used to assure distribution of gaseous refrigerant to the suction inlet of the compressor, by removing oil dropping into the tray and returning it back to the compressor. An existing by-pass eductor loop for returning liquid refrigerant from the evaporator to the compressor is extended by a valve controlled branch to a second eductor for withdrawing the oil from the tray and returning it to the compressor.

Abstract: Radiant sound reduction is achieved in a variable speed compressor by bleeding a small amount of refrigerant into the oil sump for froth production. The refrigerant is bleed from the discharge of the compressor through a solenoid controlled valve which is opened to permit a bleed flow when the compressor is operating at or above a predetermined capacity/speed. This limits system efficiency losses and produces sound reduction only when it is needed.

Abstract: A refrigeration system is provided with a compressor whose speed is varied to provide load control. In order to prevent compressor damage is lubricating oil pressure sensing control is provided which generates a compressor speed increase signal whenever the oil pressure drops below a predetermined minumum.

Abstract: A thermally protected heater element is located in an oil sump such that it is normally located beneath the surface of the oil whereby the oil is heated and acts as a heat sink relative to the heater element. If the oil level drops below the heater element, the thermal protection disables the heater element and the compressor whereby the location of the heater element defines the nominal minimum oil level.

Abstract: Apparatus for protecting a compressor operating in a refrigeration device such as a heat pump includes a heater for maintaining lubricating oil contained in a crankcase of the compressor at a preselected temperature that will prevent the oil from absorbing any refrigerant. A control circuit is connected to an alternating current source of electrical power for controlling the operation of the compressor. The control circuit includes a thyristor having a blocking state and a conducting state. If the heater fails to operate, the thyristor will be disposed in the blocking state thereby preventing the compressor from operating. The control circuit also includes a trigger for changing the thyristor from the blocking state to the conducting state, and a full wave bridge or rectifier for converting the voltage drop across the thyristor from an alternating current voltage to a direct current voltage.

Abstract: A refrigeration system (10) having a compressor rotor (20) rotatably supported by a plurality of hydrodynamic bearings (22 and 24) lubricated by oiless pressurized liquid refrigerant and pressurizing refrigerant which flows to a condenser (34) providing liquid refrigerant which flows to an evaporator (68) in fluid communication with the condenser and the compressor in accordance with the invention includes a refrigeration circuit (36) coupled to the compressor, for providing pressurized refrigerant to the hydrodynamic bearings from the compressor and to the evaporator; a bearing pump (26), coupled to the refrigerant circuit and to the condenser, for providing pressurized refrigerant to the refrigeration circuit; a first temperature sensor (101) sensing a temperature Tsink of a heat exchange fluid at the condenser and providing a temperature signal representative of the temperature Tsink of the heat exchange fluid at the condenser; a second heat exchange sensor (103) sensing a temperature Tsource of a heat exc

Abstract: An oil separator suitable for separating oil from vaporized refrigerant leaving the high pressure discharge side of a refrigerant compressor, and for returning the separated oil to the compressor crankcase. The oil separator includes an elongated housing having a longitudinal axis. Oil separation stages and a capillary tube are disposed within the housing. The capillary tube has a first end into which oil may flow, and a second end in fluid flow communication with an oil return outlet on the housing. The first end of the capillary tube and the oil return outlet are positioned relative to one another such that the longitudinal axis of the housing may be oriented at any selected angle in a range of ninety degrees between horizontal and vertical orientations. The capillary tube has a bore and length selected such that a predetermined refrigerant flow rate is created which carries oil to the crankcase.

Abstract: The failure of compressors due to their most common causes of failure are avoided by monitoring the operation of a compressor and operating or locking off the compressor where appropriate. Specifically, the system in run after a predetermined number of pump-downs without a call for cooling and the compressor is locked off if it cycles a predetermined number of times within a preset time period or if a low pressure situation is sensed during a call for cooling.

Abstract: A control device for a freezer in which a compressor whose operation has been stopped due to low lubricating oil pressure may be automatically restarted. This control device eliminates manual restarting of the compressor repeatedly until it becomes fully operational and facilitates discovery of the true malfunctioning of lubrication mechanisms for bearings in freezer compressors, by prohibiting automatic restarting once the compressor has been operating at normal oil pressure for a preset amount of time.

Abstract: An outdoor unit has at least two variable-capability compressors and has an outdoor heat exchanger coupled to the compressors having lubricating oil supplying sections coupled together by an oil-balancing member. A plurality of indoor units are each coupled to the outdoor unit for forming a refrigerating cycle and each have at least an indoor heat exchanger and an output section for outputting demand capability data according to an air conditioning load of the indoor heat exchanger. In accordance with the demand capability data, a controller generates a parallel operation command for parallel operation involving both of the compressors of the outdoor unit with capability according to a sum of the demand capability data from the indoor units.

Abstract: In a refrigeration cycle in which a capacity-variable compressor a condenser, an expansion mechanism and an evaporator are connected in the order named, a device for controlling the capacity in the refrigeration cycle comprising a means for detecting the temperature of the compressor or the temperature of the gas discharged therefrom and a control device for limiting the maximum rotational speed of the compressor when the output from the means for detecting the temperature indicates a detected temperature lower than a predetermined level.

Abstract: A single or multiple evaporator vapor-compression refrigerant system for single or multi-story structures includes a lubricating oil collection reservoir and a separate oil pumping unit for returning oil separated from the refrigerant fluid in the refrigerant flow circuit to the compressor unit. In multi-story, direct expansion, vapor-compression, air conditioning systems, a simplified generally vertical refrigerant vapor return riser is provided with an oil reservoir at the lowest elevation point of the riser and a liquid level sensing switch for energizing and deenergizing the separate lubricating oil pumping unit. The pumping unit may include an electric or refrigerant fluid driven motor connected to a pump or the pumping unit may include a pressure vessel into which high pressure refrigerant vapor is admitted to displace oil back to the compressor through an oil return conduit.

Abstract: An oil return system for a multiple compressor refrigeration system in which said compressors have a common discharge and at least two of said compressors have their low pressure suction side connected to operate at substantially different suction pressures, said oil return system having oil and refrigerant separating means connected to receive the common discharge from said compressors and oil delivery means constructed and arranged to maintain compressor oil levels at the suction side of the respective compressors, and oil control valve means disposed between said separating means and oil delivery means for each of said two compressors, said oil control valve means for each such compressor having pressure means for maintaining the downstream oil pressure to the oil delivery means at a preselected value.

Abstract: A heat pump having improved compressor lubrication wherein an adequate amount of refrigerator oil is returned to the compressor at all times and the circulation time for the refrigerator oil is reduced. An oil separator is connected between a discharge side of the compressor and a four-way valve of the heat pump system. A bypass is connected between the oil separator and the accumulator. The bypass is provided with an electromagnetic valve for selectively opening and closing the bypass. A control device periodically opens the electromagnetic valve during the operation of the compressor to provide for supply of refrigerator oil to the compressor from the oil separator.

Abstract: Means for continuously shutting-down operation of an enclosed motor-compressor unit upon predetermined contamination of the refrigerant-oil mixture therein by conductive particles which comprises providing a normally open switch in the motor energizing circuit operated to a closed position by a sensitive D.C. relay when energized, in immersing a pair of spaced electrodes in the refrigerant-oil mixture, connecting the electrodes across an A.C. power source, connecting the D.C. relay in parallel with the electrodes across the A.C. power source through rectifying and voltage dropping means and in providing a fusible link in the A.C.

Abstract: Means for continuously shut-down operation of and enclosed motor-compressor unit for refrigeration or heat pump service when the refrigerant-oil mixture therein reaches a predetermined degree of contamination by conductive particles comprises the provision of a normally closed switch in the motor energizing circuit, a relay which when energized opens the switch, in immersing a pair of spaced electrodes in the mixture, in connecting the electrodes and a capacitor in series across a D.C. power source, in connecting a unidirectional solid state switch and the relay in parallel with the electrodes and capacitor and in providing voltage responsive gating means for turning on the switch in response to a predetermined charge on the capacitor, and in the provision of a normally open fusible switch responsive to fuse and close in response to a predetermined high motor temperature and through relay means opens a second normally closed switch in the motor energizing circuit.

Abstract: A single or multiple evaporator vapor-compression refrigerant system for single or multi-story structures includes a lubricating oil collection reservoir and a separate oil pumping unit for returning oil separated from the refrigerant fluid in the refrigerant flow circuit to the compressor unit. In multi-story, direct expansion, vapor-compression, air conditioning systems, a simplified generally vertical refrigerant vapor return riser is provided with an oil reservoir at the lowest elevation point of the riser and a liquid level sensing switch for energizing and deenergizing the separate lubricating oil pumping unit. The pumping unit may include an electric or refrigerant fluid driven motor connected to a pump or the pumping unit may include a pressure vessel into which high pressure refrigerant vapor is admitted to displace oil back to the compressor through an oil return conduit.

Abstract: A pressure regulating valve for use in the oil separation and delivery system of a refrigeration system, including a valve body having an oil inlet chamber for connection with a separated liquid source on the high pressure side of refrigeration system compressor means, an oil outlet adapted for low pressure connection with oil level controls for the compressor means, internal valve means for controlling oil flow between the high side and low side chambers, and movable pressure means responsive to oil outlet pressure and compressor suction pressure acting in opposition for regulating said internal valve means.

Abstract: Means for shutting down operation of an enclosed motor compressor unit for air conditioning and heat pump service consists in immersing a pair of spaced electrodes having a potential gradient thereacross in the refrigerant-oil mixture in the unit enclosure and in employing the ion and electron flow across the electrodes resulting from contaminants in the mixture to break the motor energizing circuit through relay means, and in the provision of a normally open fusible switch responsive to close in response to a predetermined high motor temperature and through relay means break the motor energizing circuit. In a simplified modification, the immersed electrodes are directly connected across the power supply leads and cause a fusible link connected in the power supply leads to open and break the motor energizing circuit when sufficient conduction across the electrodes occurs.

Abstract: An oil separation system for a refrigeration system having compressor, condenser-receiver and evaporator means, including an oil separator having a vortex separation chamber disposed in the refrigerant gas discharge line between the compressor means and condenser-receiver means, an oil reservoir for receiving oil from the separation chamber, and oil control means for maintaining a predetermined oil level in the compressor means including a pressure differential valve for regulating the flow of oil from the reservoir to the compressor means.

Abstract: A method for controlling the energization of a crankcase heater for use in a refrigeration circuit is disclosed. The crankcase heater is energized through normally closed relay contacts except when the compressor is operating and except for a delay period after compressor operation. A microprocessor control is utilized to calculate the delay period based on the length of the period of compressor operation and to control the energization of the crankcase heater.

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: A method of regulating startup operation of a vapor compression refrigeration system to prevent oil pump cavitation during startup of the refrigeration system is disclosed. The method comprises monitoring the rate of decrease in evaporator pressure or temperature or monitoring compressor suction line pressure and then comparing this monitored rate to a rate of pressure or temperature decrease which is predetermined to prevent oil pump cavitation. If the monitored rate exceeds the predetermined rate control action is taken to adjust the capacity of the compressor to provide a desired rate of pressure drop which prevents oil pump cavitation. A microprocessor control system and a mechanical control system are disclosed for carrying out the disclosed method.

Abstract: A method and apparatus to prevent oil pump cavitation in a hermetically sealed vapor compression refrigeration system are disclosed. A hermetically sealed housing containing the refrigeration compressor transmission and oil supply reservoir is connected to the suction side of the compressor to equalize the pressure in the housing and the suction to the compressor is constructed with a restriction such as an orifice or a venturi to create a pressure drop or is of a size small enough to create a pressure drop when refrigerant flows through the line. The pressure drop is sensed by a pressure differential switch to anticipate sharp drops in pressure in the housing. The flow of refrigerant to the compressor is throttled in response to predetermined pressure drops to prevent a sharp drop in pressure within the transmission housing and thus prevent vigorous boiling of refrigerant from the oil reservoir.

Abstract: A control system for operating a vapor compression refrigeration system to prevent oil pump cavitation during startup of the refrigeration system is disclosed. The control system includes a differential pressure switch which is connected on one side to a reservoir which is in fluidic communication with the refrigeration system evaporator or compressor suction line. The pressure switch is connected on its other side directly to the evaporator or compressor suction line. In operation, the reservoir fills with vaporous refrigerant from the refrigeration system when the refrigeration system is shut down and the vaporous refrigerant flows through a restrictor valve back to the refrigeration system at startup of the refrigeration system. The size of the reservoir and restrictor valve are selected so that the differential pressure switch is activated and a control is generated when too rapid a decrease in evaporator or compressor suction line pressure is detected.

Abstract: 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.

Abstract: A method and control system for operating a vapor compression refrigeration system to prevent oil pump cavitation during startup of the refrigeration system is disclosed. The control system includes a temperature or pressure sensor located in the evaporator of the refrigeration system, a microprocessor, and an inlet guide vane control mechanism. During startup, the pressure of the gaseous refrigerant or the temperature of the liquid refrigerant in the evaporator of the refrigeration system, or compressor suction line pressure, is measured and an electrical signal corresponding to the measured pressure or temperature is processed by the microprocessor to determine the actual rate of pulldown of refrigerant pressure in the evaporator. The microprocessor compares the actual pulldown rate to a pulldown rate which has been predetermined to prevent compressor oil pump cavitation.

Abstract: A compressor crankcase low differential temperature detection and control system for a reverse-cycle refrigeration system for detecting an abnormally low temperature crankcase and for controlling the system in response to such fault detection by inhibiting the operation of the compressor and for providing a fault indication.

Abstract: A gas compression system and method utilizing an oil-injected rotary compressor, an oil separator in the discharge line thereof, and an oil supply line between the oil separator and the working space of the compressor. Said oil line conducts oil and gas dissolved in the oil to a throttling device incorporated in the line which causes a decrease in the temperature of the oil due to boiling off of the gas dissolved in the oil, which cooled oil is then conducted into the working space of the compressor. The invention applies to refrigeration systems.

Abstract: A device for monitoring the physical and thermodynamic states and concentration of components of a fluid mixture within an operating refrigeration system to detect precursor conditions of system malfunction. Monitoring and detecting refrigeration system fluids is accomplished by continuously sampling the fluids at critical positions within the system during operation. The sampling is accomplished by means of a plurality of sensors positioned within and adapted to detect changes in the heat constants of the fluids. Electronic circuit means utilizing voltage signals derived from the sensors discriminates between normal operating conditions and malfunction precursor conditions. The electronic circuit output is applied to control operation of the system to prevent system damage and to actuate the system status visual display.

Abstract: A multiple function valve for a compressor cooling liquid system. A cylindrical valve housing has an inlet at one end and an outlet at the other with a flow passage therethrough. A thermal valve controls the liquid flow between the inlet and outlet and diverts liquid to a heat exchanger connected with ports in the valve body. A pressure responsive on-off valve is located between the thermal valve and the outlet. A filter is connected between the inlet and the thermal valve.

Abstract: A fail-safe timing circuit energizable in response to a starting signal for activating a system, such as an air conditioning system, includes a first switching circuit responsive to the request signal to activate the system to commence its operation tentatively, a time-out circuit responsive to the starting signal for generating a time-out signal after a predetermined time delay interval, a circuit responsive to a system variable such as the compressor oil pressure achieving a given desired value, for preventing the time-out circuit from generating its time-out signal, and a second switching circuit for causing the first switching circuit to de-activate the system in response to the time-out signal. As a result, the system is prevented from operating in an undesirable or unwanted manner should the system variable not reach the predetermined condition within the timing interval.

Abstract: A cooling unit for a building area or the like and a compressor control for the cooling unit, the latter including a compressor for compressing gaseous refrigerant and having temperature sensing means mounted on the compressor housing and coacting with heater means, for causing actuation of the compressor upon the rise of temperature of the housing to a predetermined point, with the temperature sensing means being operative to maintain the compressor in de-energized condition until the temperature of the compressor housing rises to said point, a heater means coacts with the compressor housing for applying heat thereto to cause heating of the compressor and resultant vaporization of liquid refrigerant in the compressor.

Abstract: The electrical control panel for a refrigeration unit using single or three phase power. The control portion has an oil pressure safety switch, defrost timer, temperature controls and perhaps a refrigerant pressure control in conjunction with the normal internal overload circuit breakers for the compressor. After operation of the refrigeration unit for a period of time, a defrost control device cuts off the compressor and turns on the electric defrost heaters. As the evaporator coils are defrosted, defrost thermostats open the defrost heater supply circuits. When the current sensing relay senses that all the defrost heaters have been shut off via the defrost thermostats, a time delay relay will return the refrigeration unit to the normal refrigeration cycle. The same current sensing relay will prevent false triggering by the oil pressure safety switch if the compressor's internal overload circuit breaker opens.