Abstract: This expansion valve (10) can be used for a refrigeration system (1) having a compressor (2), an evaporator (3) and a condenser (4). The valve (10) comprises a body (12) including an inlet passage (26), an outlet passage (38), a piston passage (28) defining a piston port (30) and valve chamber (32), the piston passage (28) defining a piston chamber (46) communicating with valve chamber (32). A piston (40) is movably mounted in the piston passage (28) and selectively controls flow through the piston port (30), the piston (40) having an interior passage (60) communicating with the inlet passage (26) and having a pin port (62) communicating with the valve chamber (32), the piston (40) having a biasing spring (52) biasing the piston (40) into a closed position. A valve pin (70) is movably mounted in the valve chamber (32) and controls flow through the valve pin port (62), the valve pin (70) having a spring (74) biasing the pin (70) into the closed position.

Abstract: Pulse width modulation is used to control the flow rate through a solenoid expansion valve in a refrigeration system. A device for sensing suction line temperature is provided, and a controller is included for controlling the duty cycle of the pulse width modulated solenoid valve. The controller receives input from the suction line temperature sensing device as a basis for controlling the duty cycle. The suction line temperature sensing device may be a temperature sensor disposed on the suction line at the midpoint of the heat exchanger between the suction line and the liquid line. Alternatively, the suction line temperature sensing device may include a first temperature sensor disposed on the liquid line at one end of the heat exchanger and a second temperature sensor disposed on the liquid line at another end of the heat exchanger.

Abstract: A refrigeration system having a compressor, a condenser and an evaporator between the condenser and the compressor. A controllable valve unit at the input side of the evaporator has degrees of opening for controlling fluid flow through said evaporator. A control unit controls the degrees of opening of the valve unit. Sensors connected to the control unit and opposite ends of the evaporator detect superheat temperatures between the input and output sides of the evaporator. The control unit is operable to control the degrees of valve opening in accordance with the superheat temperatures (1) at a first greater desired opening and closing displacement rate between desired predetermined minimum and maximum values of a first range of superheat temperature values and (2) at a second opening and closing rate lesser than the first displacement rate for a second range of superheat temperature values lower than the first range of values.

Abstract: A refrigeration system, and method of operating same, with the refrigeration system having a refrigerant flow path which includes a heat exchanger having an inlet, an outlet, and a refrigerant flow path between the inlet and outlet. The refrigerant enters the inlet in a first predetermined phase and exits the outlet in a second predetermined phase. A first resistance device is disposed in heat exchange relation with the refrigerant in the flow path of the heat exchanger, adjacent to the inlet. A second resistance device is disposed in heat exchange relation with the refrigerant in the flow path of the heat exchanger, at a location between the inlet and outlet where the change in phase from the first phase to the second phase is desired. The first and second resistance devices are connected in a bridge circuit having bridge arms connected between input and output terminals, with a source of potential being connected to the input terminals.

Abstract: This expansion valve (10 ) can be used for a refrigeration system (1) having a compressor (2), an evaporator (3) and a condenser (4). The valve (10) comprises a body (12) including an inlet passage (26), an outlet passage (38), a piston passage (28) defining a piston port (30) and valve chamber (32), the piston passage (28) defining a piston chamber (46) communicating with valve chamber (32). A piston (40) is movably mounted in the piston passage (28) and selectively controls flow through the piston port (30), the piston (40) having an interior passage (60) communicating with the inlet passage (26) and having a pin port (62) communicating with the valve chamber (32), the piston (40) having a biasing spring (52) biasing the piston (40) into a closed position. A valve pin (70) is movably mounted in the valve chamber (32) and controls flow through the valve pin port (62), the valve pin (70) having a spring (74) biasing the pin (70) into the closed position.

Abstract: A refrigerating apparatus which is capable of accurate and swift correspondence to a transient change of a refrigerant circuit or an accumulated deviation of the degree of superheat of a refrigerant, thereby releasing the state in which the liquid refrigerant is flowing back to the compressor and the overheated state, and a method of controlling such a refrigerating apparatus. The refrigerating apparatus comprises a refrigerant circuit composed of a condenser, an expansion valve and an evaporator which are connected to each other in series, a means for detecting the evaporating temperature of the refrigerant, a means for detecting the exit temperature of the evaporator, and a control means for controlling the opening of the expansion valve on the basis of the evaporating temperature of the refrigerant and the exit temperature of the evaporator in accordance with a fuzzy reasoning.

Abstract: A method of controlling a refrigeration system employing an electronic controller for operating an electrically actuated refrigerant expansion valve supplying the evaporator or endothermic heat exchanger. The controller is of the type which modulates the valve for refrigerant flow to maintain a desired target level of superheated vapor discharging from the evaporator. When the compressor return, or evaporator discharge pressure (P.sub.c) is within a preselected range the system employs a strategy to increment or decrement the target level of superheat depending upon whether the rate of change (.DELTA.P.sub.c) of discharge pressure is positive or negative and thereby maximize pulldown by minimizing compressor cycling to achieve the superheat target.

Abstract: A valve controller which controls the opening degree of an electrically driven expansion valve mounted in the refrigerating cycle, in accordance with a difference between a refrigerant saturation temperature of an outdoor heat exchanger detected with a first temperature sensor and a refrigerant temperature at the suction port of a compressor detected with a second temperature sensor. A sensor error correcting unit is provided whereby a detected temperature error is calculated in accordance with the outputs of the first and second temperature sensors exposed in an atmospheric air having a specific temperature, and in accordance with the detected temperature error, a difference between the refrigerant saturation temperature and the refrigerant temperature at the suction port of the compressor is corrected.

Abstract: This thermostatic expansion valve (12) is intended for use in a refrigeration system (10) which includes a compressor (14), a condenser (16) and an evaporator (18). The valve (12) includes a valve body (20) having an inlet (26) and an outlet (28). A valve port (34) and a valve element (38) are disposed between the inlet and outlet. Upper and lower diaphragm assemblies (24, 25) are provided at each end of the valve (12) connected to associated sensing bulbs (56, 58) at the inlet and outlet respectively of the evaporator (18). A push rod assembly (40) operatively interconnects the upper and lower diaphragm assemblies (24, 25) and modulates the valve element (38) in response to the change in differential temperature across the evaporator. A compression spring (36) acts directly on the valve element and provides an adjustable feature.

Abstract: A microprocessor controlled system for use in a refrigeration system which includes a plurality of pulse controlled solenoid flow control valves suitable for use as expansion valves is disclosed. A pulse width modulated control signal is generated for cyclically opening and closing the flow through the solenoid expansion valve. The duty cycle of the pulsed control signal determines the average flow rate through the valve. The microprocessor responds to the flow rate through each of the solenoid valves to determine, on a system-wide basis, if each fixture in the system, as indicated by the flow rate through the expansion valve associated therewith, is operating properly.

Abstract: A refrigerating system including a refrigerant circuit having a condenser, evaporator and wobble plate type compressor with a variable displacement mechanism. Two passages communicate between the crank chamber and the suction chamber in the cylinder block. A bellows is disposed in a first passage and controls the communication between the crank chamber and the suction chamber response to crank chamber pressure. A control valve is disposed in the second passage and controls communication between the crank chamber and the suction chamber in the second passage in response to a signal generated outside of the compressor. A control circuit controls the generation of the signal in response to thermodynamic characteristics related to the evaporator. The signal activates or deactivates the second control valve when the characteristic indicates a value beyond a predetermined range of values.

Abstract: A refrigeration system in an ice making machine has an evaporator coil connected at its inlet side to an outlet of a refrigeration compressor through a condensing coil and at its outlet side to an inlet of the compressor. An expansion valve is interposed between the condensing coil and the evaporator coil. A bypass line is connected in parallel with the condensing coil and the expansion valve. A solenoid valve is disposed within the bypass line to permit the flow of hot gas supplied therethrough from the compressor into the evaporator coil when it has been energized. The expansion valve is in the form of an expansion valve of the externally equalized type associated with an external equalizer pipe having an extremity connected to an intermediate portion of the evaporator coil between the inlet and outlet sides thereof. A thermostat bulb is located on a return line between the outlet side of the evaporator coil and the compressor.

Abstract: In a refrigeration system including an incremental expansion valve and an electronic controller for controlling the operation of the expansion valve, a method of controlling the expansion valve in response to a sensed condition of the refrigerant in the system. According to the method, the valve controller alters the control gain rate to provide compensation in the valve flow rate for changing refrigerant conditions in the system due to the staging of multiple condenser fans and flooding of the evaporator.

Abstract: A system for controlling refrigerant flow in an air conditioning system employing an electrically operated valve for controlling flow of refrigerant from the condenser to the evaporator. Separate thermistors sense the temperature of the refrigerant entering and discharging from the evaporator. A comparison of the sensed temperatures is used to modify the control signal to the valve for maintaining proper refrigerant flow to the evaporator. A control module is directly attached on the valve body to enhance heat conduction.

Abstract: A system for refrigeration comprises: a compressor having an inlet, an oil sump, and an outlet; a condenser having an outlet, and an inlet connected to the compressor outlet; an expansion valve operable for controlling refrigerant flow in the system and having an outlet, and an inlet connected to the condenser outlet; an evaporator having an inlet connected to the expansion valve outlet and an outlet connected to the compressor inlet; and a control unit for operating the expansion valve to maintain a predetermined temperature differential between the temperature of oil in the oil sump and the saturated temperature of the refrigerant in the vicinity of the compressor inlet. The temperature differential is selected such that refrigerant in liquid phase in the compressor does not excessively dilute the compressor oil.

Abstract: A method for improving cooling of a compressor element used in an air conditioning system and having a refrigerant compressor and associated drive motor hermetically sealed in a fluid-tight shell includes the steps of detecting an excessive increase in the temperature of the compressor element, intermittently operating the system during the excessive temperature detection with a superheat of a refrigerant in the system below zero superheat degrees to concurrently allow liquid refrigerant to enter the shell to enhance the cooling of the compressor apparatus by the latent heat of vaporization of the liquid refrigerant and terminating the intermittent operation and the admittance of the liquid refrigerant into the compressor element upon a detection of a desired temperature of operation of the compressor element.

Abstract: A refrigeration system comprises a compressor, a condenser, an evaporator, an accumulator, and an adjustable controllable expansion valve. An electronic control system monitors the value of superheat and accordingly provides an electrical control signal to adjust the controllable expansion valve in order to maintain a set point superheat value. An unfiltered path is provided to ensure expedient response when the system starts operation and when dynamic changes occur. A filtered path is provided to reduce hunting, or oscillations about the set point, of the superheat value during steady state operation.

Abstract: A system for controlling refrigerant flow in an air conditioning system employing an electrically operated valve for controlling flow of refrigerant from the condenser to the evaporator. Separate thermistors sense the temperature of the refrigerant entering and discharging from the evaporator. A comparison of the sensed temperatures is used to modify the control signal to the valve for maintaining proper refrigerant flow to the evaporator.

Abstract: The invention relates to a device and method for regulating the superheat temperature of the evaporator of a refrigeration or heat pump system. The existing and desired superheat values are compared at intervals of two and the rate of departure between these two values is utilized for adjusting the desired superheat value.

Abstract: An electric signal T1 representing the evaporating temperature of refrigerant is processed by a phase lead network and thus converted to T1' with a single time constant so as to compensate for the time lag due to the time constant of a temperature sensor for sensing the evaporating temperature. An electrical signal T2 representing superheated vapor temperature at the outlet of an evaporator is processed by a phase lag network and thus converted to T2', so as to have a larger time constant than that of the unprocessed signal T2 and a signal corresponding to .DELTA.T'=T1'-T2' is used to control the degree of valve opening of an electric expansion valve.

Abstract: A condenser is connected to an outlet of a compressor. An expansion valve is connected to the condenser. An evaporator is connected between the expansion valve and an inlet of the compressor. A sensor detects a condition of refrigerant at an outlet side of the evaporator. A variation in rate of refrigerant flow into the evaporator is detected. A control device determines a variation in the detected condition of refrigerant which occurs in response to the variation in the rate of refrigerant flow. The control device judges a quantity of refrigerant to be insufficient when the determined variation in the refrigerant condition is equal to or smaller than a reference value.

Abstract: The degree of opening of the expansion valve in refrigeration system is controlled by means of PID control such that a refrigerant superheat at the outlet of the evaporator approaches a target valve. Since an elapsed time after the start of the refrigeration system varies in response to a change of a heat load of air to be cooled by the evaporator, if the control constant of the PID control is designed so that the expansion valve can be controlled adequately for high evaporator heat load, or for low evaporator heat load, adequate control cannot be achieved in the opposite case not taken into consideration in design. According to the present invention, the control constant of the PID control is varied when an elapsed time after the start of the refrigeration system reaches a reference time which is determined on the basis of a heat load of air to be cooled by the evaporator.

Abstract: A system for preventing vapor-lock in a positively pressurized loop-type engine fuel line having the low pressure or tank return portion of the fuel line passing through a heat exchanger disposed in the refrigerant line for the vehicle air conditioner between the endothermic heat exchanger or evaporator and the compressor inlet. A thermistor senses the temperature of the refrigerant discharging from the fuel line heat exchanger and a pressure transducer senses evaporator discharge saturation pressure. Look-up tables are used to determine saturation temperature from the saturation pressure, and saturation temperature and actual refrigerant temperature compared to generate a pulse-width modulated control signal for controlling an electrically operated refrigerant expansion valve to maintain a desired amount of superheat at the discharge of the fuel line heat exchanger.

Abstract: A method and apparatus for preventing flood back in refrigeration systems which include a compressor, expansion valve and evaporator coil, by sensing the temperature differential across the evaporator coil and deactivating the compressor when the differential exceeds in the negative direction a predetermined amount of superheat. A second embodiment uses the sensing to operate flooded systems at peak efficiency at or near 0 superheat. A third embodiment uses all electronic circuitry to operate the system.

Abstract: An expansion valve (8), which is arranged between the condenser (2) and the evaporator (3) in the pump medium circulation system of the heat pump and is continuously controllable, is regulated as a function of set values by means of a computer (10), in particular, while taking into account the evaporator input temperature measured by means of sensing devices (5) and/or the evaporator output temperature measured by means of sensing devices (6). Because of the regulating by means of computers, the control is suitable for different heat pumps and/or conditions of use without structurally altering the expansion valve (8).

Abstract: A cooling unit for an automotive air-conditioning system, comprising an evaporator, a compressor, an expansion valve connected to the inlet port of the evaporator, an accumulator connected to the outlet port of the evaporator, a temperature sensor for detecting the temperature of the refrigerant at the outlet port or within the evaporator, and temperature control means which controls the degree of opening of the expansion valve so that the temperature of the refrigerant at the outlet port or within the evaporator is maintained above a predetermined temperature which is slightly higher than a temperature at which the evaporator becomes frosted. The degree of opening of the expansion valve is increased to raise the vapor pressure of the refrigerant in the evaporator, instead of stopping the compressor, when the temperature of the refrigerant at the outlet port or within the evaporator drops to the predetermined temperature, so that the frequency of starting and stopping the compressor is reduced.

Abstract: A single outdoor unit has at least an inverter circuit, a compressor motor, a variable capacity compressor, and an outdoor heat exchanger. A plurality of indoor units each have at least an indoor heat exchanger and an air-conditioning load detector. A distribution unit couples the single outdoor unit to the plurality of indoor units in parallel by liquid-side refrigerant piping and gas-side refrigerant piping, to form a refrigerating cycle of a heat pump type. The liquid-side refrigerant piping includes a motor-operated flow regulating valve and pressure reducer, which are connected in series fashion. A pseudo-refrigerant superheating state detector detects a pseudo-refrigerant overheating state on the basis of the temperature of the refrigerant in the aggregated portion of gas-side refrigerant piping of the distribution unit. A first controller respectively controls the open factors of the motor-operated flow regulating valves.

Abstract: A system for controlling the flow rate of a refrigerant for refrigeration cycles which comprises an electronic expansion valve disposed at the inlet of an evaporator and a controller for controlling the opening-closing movement of the valve. The controller comprises a calculating unit for comparing the degree of superheat of the refrigerant measured at the evaporator with a preset degree of superheat and feeding a valve opening adjusting signal to the valve according to the value obtained by the comparison, and a valve full-closing signal generator for comparing the measured temperature of the space to be cooled with a preset temperature and feeding a valve full-closing signal to the valve based on the value obtained from the comparison of temperatures, in preference to the opening adjusting signal.

Abstract: A flood detection means for use with a solenoid expansion valve in a refrigeration system is disclosed. The flood detection means responds to the temperature differential across the evaporator coil for throttling down the flow rate through the expansion valve when the temperature differential is less than a temperature threshold. When the temperature differential is greater than the threshold, the valve resumes normal operations from the throttled down condition.

Abstract: The invention relates to a valve assembly for a refrigeration system of the modulating kind used for controlling the flow of refrigerant through the evaporator. The difference between the inlet and outlet temperatures of the evaporator is utilized to control the superheat but the evaporator inlet temperature taken alone is utilized to set different ranges for the valve actuator temperature to accomodate different operating conditions.

Abstract: A pulse controlled refrigeration expansion valve for multiple evaporators and method of controlling the valve is disclosed. The refrigeration system on which this invention is typically used includes a single source of pressurized refrigerant and a plurality of evaporators. Each evaporator has an expansion valve associated therewith which is preferably an on/off (open/closed) direct controlled solenoid valve. The valve is periodically energized (opened) and de-energized (closed) in response to a parameter (e.g., superheat) of its respective evaporator such that the ratio of energization time/de-energization time during each period (e.g., 4 seconds) of operation of the valve is varied in response to the system parameter(s) and such that the on/off solenoid valve functions as a modulated refrigerant flow control expansion valve. A temperature sensor is provided which senses the temperature of the space being refrigerated by a respective evaporator (e.g.

Abstract: Disclosed is a control device having a detector for detecting the degree of superheating or supercooling of refrigerating or air-conditioning units. The detector includes a pressure responsive chamber for guiding the pressure of a coolant and a diaphragm disposed therein. The diaphragm is connected with a temperature-responsive cylinder for sensing the temperature of the coolant and a connecting rod. The connecting rod moves corresponding to the pressure and temperature of the coolant, and the position thereof is sensed by a position sensor means.

Abstract: An expansion valve having a pressure chamber for changing its inside pressure, an expansion chamber provided with an orifice at a hole formed between a primary path and a secondary path, and a valve member provided within the expansion chamber, the position of the valve member being normally biased by one end of a spring in the direction of closing the orifice, in which the expansion valve further comprises an actuator having a solenoid, a rod coupled to the spring, and an action plate which is attracted by the solenoid when the solenoid is biased. With this construction, an additive force is applied to the spring and the opening of the orifice can be adjusted by a combined action of the distinctive force of the spring plus the additive force of the actuator through the valve member in the initial period of cooling condition in accordance with the change in the temperature of the evaporator, thereby adjusting the superheat.

Abstract: In a refrigeration cycle in which the opening of the expansion valve is controlled by the super-heat degree of the refrigerant periodically detected at the outlet of the evaporator, a negative control signal is produced to rapidly change the opening of the expansion valve when the detected super-heat degree has reached zero. As a result, occurrence of the liquid back is prevented.

Abstract: The invention relates to measuring apparatus for a refrigeration system for detecting a liquid component in refrigerant leaving the evaporator of the system through a suction conduit associated with a heating element heating the tube wall. The measuring apparatus includes a first temperature measuring sensor in thermal contact with the suction conduit located just sufficiently away from the heating element so as to be substantially unaffected by the heating element. A second temperature measuring reference sensor is in thermal contact with the suction conduit an optimum distance downstream from said heating element to provide a reference temperature indicative of the dry temperature of the refrigerant.

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 super-heat detector of refrigerant gas comprises a semiconductor pressure sensor for detecting a pressure of the refrigerant gas in a refrigerating apparatus, a semiconductor temperature sensor for detecting a temperature of said refrigerant gas, and an operational controller which converts an output signal from said semiconductor pressure sensor to a value corresponding to a saturation temperature of said refrigerant gas pressure, and produces an output electrical signal corresponding to super-heat condition of said refrigerant gas by comparison between said corresponding value of the saturation temperature and said output from said semiconductor temperature sensor.

Abstract: A method and control system are disclosed for operating a refrigeration system to protect the refrigeration system compressor from adverse operating conditions. A first signal indicative of the saturation temperature of the refrigerant in an evaporator of the refrigeration system, and a second signal indicative of the temperature of gaseous refrigerant flowing from the evaporator to the compressor of the refrigeration system compressor, are provided to a microcomputer system which processes the first and second signals to determine the superheat of the gaseous refrigerant flowing to the compressor. The microcomputer system generates an alarm signal to shut down operation of the refrigeration system if the detected superheat is less than a lower limit or greater than an upper limit of a normal range of superheat values.

Abstract: A refrigeration system is disclosed which may have multiple compression and condenser stages, in which an electronic refrigerant expansion valve is controlled by the digital output of a microcomputer which adjust the expansion valve in response to a valve change signal which is a function of a fraction of the deviation of the sensed refrigerant superheat from a desired superheat added to a multiple of the computed rate of change of the refrigerant superheat.

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: A control device for refrigeration cycle constructed with a compressor, a condenser, an electrically operated expansion valve, an evaporator, and so forth, all being connected in series, wherein there are further provided a by-pass extending from an inlet or an outlet or both of the expansion valve upto an inlet of the compressor through a capillary tube; a first temperature sensor to sense a temperature of a cooling medium at the inlet of the compressor; a second temperature sensor to sense a temperature of the cooling medium within an intake tubing, through which the cooling medium is taken into the inlet of the compressor; and a control device which calculates a super-heat quantity of the cooling medium taken into the compressor on the basis of a difference between the detection outputs of the first and second temperature sensors, and controls a degree of opening of the electrically operated expansion valve, thereby enabling the refrigeration cycle to be operated at high efficiency and in an energy-saving

Abstract: A refrigeration system including a refrigeration control system for controlling the operation of the refrigeration system so as to insure that the temperature of the refrigerant discharged from the evaporator coil is above the saturation temperature. The refrigeration system includes at least one refrigerated display case having an evaporator within the primary air conduit and an expansion valve coupled to the inlet end of the evaporator coil. The control system includes: a pressure sensor arranged within the refrigerant discharge line, i.e. suction line to compressor, from the evaporator coil; a first temperature sensor arranged at the air discharge side of the evaporator coil for sensing the temperature (T.sub.1) of the air that has passed over the evaporator coil, a second temperature sensor arranged adjacent to the refrigerant discharge end of the evaporator coil for measuring the temperature (T.sub.

Abstract: The invention relates to a valve assembly for a refrigeration plant of the kind used for controlling the flow of refrigerant from the evaporator to the compressor. The closure member for the valve unit is controlled directly or indirectly by a movable wall of an expansible chamber filled with a refrigerant medium having vapor and liquid phases. The pressure exerted by the vapor phase of the medium provides a bias in a valve opening direction which is directly related to the temperature of the liquid phase and is opposed by a spring bias in the valve closing direction. A heat transfer element such as a heating resistor in the liquid phase is heated or allowed to cool in a controlled manner by an external control unit. A temperature responsive sensor element in the liquid phase of the medium is part of a feedback system for the control unit which allows a selected temperature to be maintained in the chamber which results in a desired constant pressure in a valve opening direction to be maintained in a chamber.

Abstract: A pulse controlled refrigeration expansion valve and method of controlling the valve is disclosed. The valve is preferably an on/off (open/closed) direct controlled solenoid valve. The valve is periodically energized (opened) and de-energized (closed) in response to a refrigeration system parameter (e.g., superheat) such that the ratio of energization time/de-energization time during each period of operation of the valve is varied in response to the system parameter(s) and such that the on/off solenoid valve functions as a modulated refrigerant flow control expansion valve.

Abstract: A refrigeration control system for modulating an electrically-operated expansion valve in which a modulating, electrically-operated expansion valve is connected to the evaporator inlet, and first and second condition-responsive electrical sensors are positioned to respond to conditions at selected location in the system. An electrical amplifier circuit connects the condition-responsive electrical sensors to the valve for regulating the opening and closing of the valve in response to differences in the conditions sensed by the sensors. Refrigerant is fed to at least one of the sensors so as to cause modulation of the expansion valve. More particularly, the condition-responsive sensors are temperature-responsive, the first sensor being positioned to respond to the temperature of the liquid refrigerant expanded to suction pressure, and the second sensor being positioned to respond to suction line sensible temperature.

Abstract: A refrigeration control system for modulating an electrically-operated expansion valve in which a modulating, electrically-operated expansion valve is connected to the evaporator inlet, and first and second condition-responsive electrical sensors are positioned to respond to conditions at selected location in the system. An electrical amplifier circuit connects the condition-responsive electrical sensors to the valve for regulating the opening and closing of the valve in response to differences in the conditions sensed by the sensors. Refrigerant is fed to at least one of the sensors so as to cause modulation of the expansion valve. More particularly, the condition-responsive sensors are temperature-responsive, the first sensor being positioned to respond to the temperature of the liquid refrigerant expanded to suction pressure, and the second sensor being positioned to respond to suction line sensible temperature.

Abstract: A refrigeration control system for modulating an electrically-operated expansion valve in which a modulating, electrically-operated expansion valve is connected to the evaporator inlet, and first and second condition-responsive electrical sensors are positioned to respond to conditions at selected location in the system. An electrical amplifier circuit connects the condition-responsive electrical sensors to the valve for regulating the opening and closing of the valve in response to differences in the conditions sensed by the sensors. Refrigerant is fed to at least one of the sensors so as to cause modulation of the expansion valve. More particularly, the condition-responsive sensors are temperature-responsive, the first sensor being positioned to respond to the temperature of the liquid refrigerant expanded to suction pressure, and the second sensor being positioned to respond to suction line sensible temperature.

Abstract: An automatic control for a refrigeration system for regulating the superheat of refrigerant in its gaseous phase existing in the system. The control includes a sensor arranged in thermal control with the system suction line that is divided by a diaphragm into two chambers. One chamber is exposed to suction gas and the other chamber contains a fluid that is essentially the same as the system refrigerant. Mounted on the diaphragm is a four leg strain gage bridge sensor that produces an electrical signal in response to the pressure differential between the chambers.

Abstract: A control means is disclosed that is used with a closed refrigeration system having a chiller and a condenser to provide refrigeration to chill the fluid medium and a refrigerant pump for pumping the refrigerant through the system with refrigerant capacity control means determining the capacity of the refrigerant, the control means for the system using signal inputs representative of outside air temperature, return chilled water temperature, supply chilled water temperature, and condenser temperature, in which settable controllers are used to determine the optimum temperature signals for controlling the system at any given time. A timer is also connected to the control mechanism for alternately interrupting an optimum temperature signal to reduce the overall change in the control signal. Additional control may be obtained through the use of signals representative of humidity, strong solution temperature and cooling water output pressure.

Abstract: A pulse controlled refrigeration expansion valve for multiple evaporators and method of controlling the valve is disclosed. The refrigeration system on which this invention is typically used includes a single source of pressurized refrigerant and a plurality of .[.evaportors.]. .Iadd.evaporators.Iaddend.. Each evaporator has an expansion valve associated therewith which is preferably an on/off (open/closed) direct controlled solenoid valve. The valve is periodically energized (opened) and de-energized (closed) in response to a parameter (e.g., superheat) of its respective evaporator such that the ratio of energization time/de-energization time during each period (e.g., 4 seconds) of operation of the valve is varied in response to the system parameter(s) and such that the on/off solenoid valve functions as a modulated refrigerant flow control expansion valve. A temperature sensor is provided which senses the temperature of the space being refrigerated by a respective evaporator (e.g.