Abstract: A screw compressor includes a valve hole formed at a discharge side end surface of a discharge casing and at a position opening to a compression work chamber; a bypass flow path having the valve hole and a discharge chamber communicate with each other; and a valve body arranged in the valve hole. The screw compressor also includes cylinder chambers provided on a rear surface side of the valve body; a piston reciprocally moving in the cylinder chambers; a rod connecting the piston and the valve body; communication paths for introducing a fluid on a discharge side into the cylinder chamber on a side opposite to a valve body side of the piston and on the valve body side; a pressure discharge path; a plurality of valve means; and a controller controlling the plurality of valves means.

Abstract: A helium management control system for controlling the helium refrigerant supply from a common manifold supplies a plurality of cryogenic refrigerators with an appropriate helium supply. The system employs a plurality of sensors to monitor and regulate the overall refrigerant supply to deliver an appropriate refrigerant supply to each of the cryogenic refrigerators depending on the computed aggregate cooling demand of all of the cryogenic refrigerators. An appropriate supply of helium is distributed to each cryopump by sensing excess and sparse helium refrigerant and redistributing refrigerant accordingly. If the total refrigeration supply exceeds the total refrigerant demand, or consumption, excess refrigerant is directed to cryogenic refrigerators which can utilize the excess helium to complete a current cooling function more quickly.

Abstract: An air conditioning system for a vehicle has a refrigerant cycle device which has an evaporator and a compressor and in which refrigerant is discharged from the compressor to be evaporated in the evaporator so that air passing the evaporator is cooled to be blown into a passenger compartment of the vehicle. The control unit drives the compressor at a control value which is determined based on at least one of a pressure of the refrigerant in the refrigerant cycle device and an outside-air temperature outside the passenger compartment, when the control unit actuates the compressor.

Abstract: A method and system for detecting and correcting unintended reverse or backward operation of an electric motor driven scroll compressor of a refrigeration system is characterized by monitoring the pressure at a suction side of the compressor during operation of the refrigeration and determining whether the pressure, after a first time interval following startup of the compressor, exceeds and remains in excess of a predetermined upper pressure limit for at least a second time interval. If it does, the compressor is turned off for a third time interval and is then restarted. The foregoing is repeated and if the compressor is turned off a selected number of times because of successive occurrences of high suction side pressures during operation of the refrigeration system in a chilling cycle, an error indication is generated and the refrigeration system is shut down.

Abstract: A structure for sensing refrigerant flow rate in a compressor. The structure includes a passage forming member, a restriction hole, a differential pressure-type flow rate sensor, and a partition plate. The compressor includes a housing connected to an external refrigerant circuit via a refrigerant passage. The passage forming member is connected to an outer surface of the housing and forms a part of the refrigerant passage. The restriction hole divides the refrigerant passage into an upstream passage and a downstream passage. The upstream passage is formed in either the housing or the passage forming member. The sensor is provided in the passage forming member and detects pressure in the upstream passage and pressure in the downstream passage to sense flow rate of refrigerant in the refrigerant passage. The partition plate is disposed between the housing and the passage forming member. The restriction hole is formed in the partition plate to extend through the partition plate.

Abstract: In a refrigeration cycle device in which a compressor is driven by power transmitted from an engine, a torque limiter is adapted to interrupt a transmission of the power from the engine to the compressor when a torque transmitted from the engine to the compressor becomes a predetermined value. A control unit is adapted to determine whether the transmission of the power from the engine to the compressor is interrupted by the torque limiter by determining whether a deviation of a refrigerant discharge pressure of the compressor is below a predetermined pressure when the control unit commands the compressor to change the refrigerant discharge flow amount of the compressor. Thus, the control unit can determine whether the torque limiter interrupts the transmission of power from the engine to the compressor without, using a compressor revolution sensor.

Abstract: Embodiments of the present invention permit the transfer of heat energy from one process fluid to another in an industrial process without the need for an energy field or centralized energy storage. Preferred embodiments include one or more heat transfer modules that draw heat from one process fluid into circulating refrigerant in an evaporator heat exchanger and supply that heat to a different process fluid in a condenser heat exchanger. In some embodiments, adjustments are made to one or more parameters of one or more process fluids to ensure the desired heat transfer is accomplished with the heat transfer module's compressor operating near optimum efficiency.

Abstract: A system and method is provided for monitoring a system pressure to infer whether a high pressure cut out (HPCO) switch has opened disabling a heating, ventilating, and air conditioning (HVAC) compressor. A system and method are also provided for determining whether to disable the heating, ventilating, and air conditioning (HVAC) compressor based on a status of a low pressure cut out (LPCO) switch, an ambient temperature, and system mode state. The systems and methods may be used interchangeably with the appropriate adjustments to decision limits, such as where the LPCO may be monitored to infer status and the HPCO status may be directly used with temperature and system mode state.

Abstract: A displacement control valve for a variable displacement compressor. The displacement control valve includes a drive force transmission body, a pressure sensitive chamber, an internal passage, and a valve body. The valve body includes an annular seal which is contactable with a valve seat surface facing toward the first valve body. The drive force transmission body includes a drive rod and a valve body structure having a shaft passage and forming the first valve body. The drive rod is fitted to the shaft passage and coupled to the valve body structure so as to form a gap passage between an outer surface of the drive rod and a wall surface of the shaft passage. The internal passage includes a recess arranged radially inward from the annular seal, the shaft passage, and the gap passage. The gap passage is in direct communication with the recess.

Abstract: A sealed electric compressor having a normally-off type pressure switch and a fuse element. The pressure switch is placed in a sealed housing, connected parallel to a main winding of an electric motor, and, when the pressure of refrigerant in the sealed housing is abnormally high, activates to short-circuit the main winding. The fuse element is connected in series to the main winding and an auxiliary winding of the electric motor and interrupts conduction of electricity to the electric motor when an excess current that is produced when the pressure switch short-circuits the main winding flows.

Abstract: There is provided a turbo chiller that can be operated at high efficiency within an adequate chilling capacity range even when the cooling water temperature changes during the operation. The adequate chilling capacity range is obtained by using a flow coefficient and a pressure coefficient at a specific operating point of a turbo compressor as well as a predetermined coefficient to determine an arithmetic expression representing the relationship between a head and a chilling capacity, using a chilling capacity that can lead to a substantially highest coefficient of performance at a single head to obtain the predetermined coefficient as an optimum coefficient, computing an adequate operation coefficient range having a predetermined range and including the optimum coefficient, and substituting the adequate operation coefficient range and a head at the time of operation into the arithmetic expression.

Abstract: A linear compressor control system includes an electronic circuit controlling an electric motor that drive a piston of the compressor, such that the motor is operated intermittently with an on-time (tL) and an off-time (tD) to keep the compression capacity of the compressor substantially constant. The compressor is associated with a closed cooling circuit having an evaporator and a condenser. The off-time (tD) is shorter than the time necessary for the evaporation pressure (PE) in the evaporator and the condensation pressure (Pc) in the condenser to equalize each other after the compressor has been turned off.

Abstract: An air conditioner is switchable between a cooling mode and a heating mode using highly pressurized hot gas in a refrigerant cycle. During the cooling mode, a controller controls an input electric current to a solenoid to operate the control valve based on a lower pressure side pressure of the refrigerant cycle acting on a pressure sensitive mechanism and a quantity of the input electric current to the solenoid. During the heating mode, the controller controls the input electric current to the solenoid to operate the control valve based not on the lower pressure side pressure of the refrigerant cycle acting on the pressure sensitive mechanism, but only on the quantity of the input electric current to the solenoid.

Abstract: An air conditioning system having a cooling mode and a free-cooling mode. The system having a refrigeration circuit having a compressor and a pump; a suction pressure sensor for measuring a suction pressure of the compressor; a discharge pressure sensor for measuring a discharge pressure of the compressor; a controller for selectively operating in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via the compressor or operating in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump; and a recover-refrigerant sequence resident on the controller, the recover-refrigerant sequence being configured to pump the refrigerant in a portion of the refrigeration circuit not used in the free-cooling mode to remaining portions of the refrigeration circuit used in the free-cooling mode when the controller switches from the cooling mode to the free-cooling mode.

Abstract: A system and method is provided for monitoring a system pressure to infer whether a high pressure cut out (HPCO) switch has opened disabling a heating, ventilating, and air conditioning (HVAC) compressor. A system and method are also provided for determining whether to disable the HVAC compressor based on a status of a low pressure cut out (LPCO) switch, an ambient temperature, and system mode state. The systems and methods may be used interchangeably with the appropriate adjustments to decision limits, such as where the LPCO may be monitored to infer status and the HPCO status may be directly used with temperature and system mode state.

Abstract: The invention relates to a refrigeration circuit having a mono- or multi-component refrigerant circulating therein, said refrigeration circuit comprising, in the direction of flow, a condenser, a collecting container, a relief device connected upstream of an evaporator, an evaporator and a compressor unit with single-stage compression. According to the invention, there is an intermediate relief device (a) arranged between the condenser (1) and the collecting container (3). Furthermore, there is disclosed a method of operating a refrigeration device in which pressure relief of the refrigerant to an (intermediate) pressure of 5 to 40 bar is effected in the intermediate relief device (a) arranged between the condenser (1) and the collecting container (3).

Abstract: An air conditioner includes an indoor heat exchanger (radiator) and a controller. The radiator causes heat radiation to be performed with respect to air from a supercritical refrigerant during heating operation. The controller controls a room temperature by causing a high-pressure side pressure and a refrigerant outlet temperature of the radiator to reach respective target values. Preferably, the controller detects a refrigerant outlet temperature of the radiator with an outlet temperature sensor and detects a room temperature with a room temperature sensor. The controller increases or decreases a target value of the high-pressure side pressure when the controller has judged that there is an excess or a deficiency of capacity in view of the room temperature inside a room that is to be heated even when the refrigerant outlet temperature of the radiator has reached a target value during heating.

Abstract: A refrigerant compressor assembly for a refrigeration circuit controls the temperature within a temperature controlled space. The refrigerant compressor assembly includes a first unloading valve, a first valve actuator, and a first valve control system that adjusts the first valve actuator via a pulse-width-modulated signal, a second unloading valve, a second valve actuator, and a second valve control system that adjusts the second valve actuator via a pulse-width-modulated signal. The refrigerant compressor assembly also includes a third unloading valve. The first valve actuator is coupled to the first and third unloading valves and controlled by the first valve control system. The unloading valves selectively allow or resist fluid flow from higher to lower pressure areas within the refrigerant compressor assembly.

Abstract: A refrigerating cycle apparatus is obtained that can determine excess/shortage of a refrigerant amount in a refrigerating circuit at high precision even if a factor such as a heat exchanger whose refrigerant amount is difficult to calculate exists.

Abstract: A heat pump system includes: a heat-source-side refrigerant circuit having a heat-source-side compressor, a first usage-side heat exchanger operable as a radiator of heat-source-side refrigerant, and a heat-source-side heat exchanger operable as a radiator of heat-source-side refrigerant; and a usage-side refrigerant circuit having a usage-side compressor, a refrigerant/water heat exchanger operable as a radiator of usage-side refrigerant to heat an aqueous medium, and the first usage-side heat exchanger operable as an evaporator of usage-side refrigerant by radiation of heat-source-side refrigerant.

Abstract: An energy efficient and highly versatile electrically-powered air conditioning and heating system for mobile vehicles. Multiple variable-speed compressors operate in series and parallel modes giving an exceptionally wide range of operating capacity making the system suitable for combined on-highway and no-idle use in trucks. In series mode, the single-stage compressors function like a two-stage compressors for increased energy efficiency. A unique power control and storage system has multi-voltage input and output capability without the use of DC-DC or DC-AC converters. A battery management system is incorporated which is compatible with all advanced battery technologies and offers cell-level charge and discharge control.

Abstract: A compressor inlet pressure estimation apparatus for a refrigeration cycle system is disclosed. An electronic control unit 14 uses Tefin_lag(N) as an actual corrected temperature Tefin_AD(N) during a period Tp1 included in the timing t1 to t2. During a period Tp2 included in the timing t1 to t2, Tefin_fwd(N) is used as the actual corrected temperature Tefin_AD(N). Thus, a highly accurate corrected temperature Tefin_AD(N) can be determined over the on period (t1 to t2) of a compressor 2. In addition, Tefin_fwd(N) is used as the actual corrected temperature Tefin_AD(N) during the off period (t2 to 3) of the compressor 2. As a result, a highly accurate corrected temperature Tefin_AD(N) can be determined over the whole period including the on and off periods of the compressor 2. In this way, a highly accurate estimated value Ps_es(N) of the refrigerant inlet pressure of the compressor 2 can be determined.

Abstract: An air conditioning system that comprises a controller that is in electrical communication with a compressor, a condenser fan, a temperature sensor that measures the temperature of the ambient air, a temperature sensor that measures the temperature of a condenser coil of the air conditioning system, and a low pressure switch (LPS) that measure the pressure of a refrigerant disposed within the air conditioning system. An algorithm resident on the controller controls the controller to enter a low ambient cooling mode when the temperature of the ambient air is less than a set temperature. The algorithm further controls the controller so that a minimum and/or maximum cycling frequency is imposed on the condenser fan.

Abstract: To provide a multistage compressor including an injection circuit, which can continue high-efficiency and high-capacity operations even if the injection circuit is turned on/off in accordance with operating conditions. A multistage compressor includes a high stage side compressing mechanism suctioning the intermediate pressure refrigerant gas compressed with a low stage side compressing mechanism to perform two-stage compression, and an injection circuit for injecting an intermediate pressure refrigerant into the intermediate pressure refrigerant gas suctioned to the high stage side compressing mechanism, the high stage side compressing mechanism including a capacity control mechanism for bypassing a refrigerant gas that is being compressed to a suction side, the injection circuit including an on/off mechanism for performing on/off control of refrigerant injection, and the capacity control mechanism and the on/off mechanism being operated in conjunction with each other.

Abstract: Both of maintenance of cooling performance of low-temperature showcases and enhancement of energy saving performance of a refrigerating machine are enabled. A cooling system 1 is constructed to have a refrigeration circuit 2 in which low-temperature showcases 7 as plural load facilities are connected to a rack system refrigerating machine 3 in parallel through refrigerant pipes 5a and 5b, a main controller 4 for generating and outputting control data of compressors 9 constructing the rack system refrigerating machine 3 on the basis of the cooling state of the low-temperature showcases 7, and a compressor controller 6 which is constructed to acquire control setting required for capacity control of the compressors 9 as main elements of the rack system refrigerating machine 3, receives control data from the main controller 4 and controls the compressors 9 on the basis of the control setting and the control data.

Abstract: An intelligent controller (68), adapted for regulating operation of either a refrigeration system or an air conditioning system (20), receives an output electrical signal produced by a pressure sensor (72, 74, 76, 78) included in the system (20). Responsive to the received electrical signal, the intelligent controller (68) energizes operation of a motor (24) that drives a compressor (22) included in the system (20). The programmable electronic circuit (68) performs a calibration operation in which the circuit (68) measures the output electrical signal received from the pressure sensor (72, 74, 76, 78) and stores as an offset the value so measured. The programmable electronic circuit (68) subsequently applies the stored offset for adjusting a value of the output electrical signal received from the pressure sensor (72, 74, 76, 78) during normal operation of the system (20).

Abstract: In a refrigeration unit including a variable performance compressor driven by an inverter motor, a sensor is configured to detect a physical amount corresponding to a refrigerant pressure on the high-pressure side of a refrigerant circuit. A measured value of the physical amount is compared with a first reference value corresponding to a first predetermined pressure of the refrigerant and a second reference value corresponding to a second predetermined pressure lower than the first predetermined pressure. A protective operation can start if the comparison result indicates that an actual refrigerant pressure is higher than the first predetermined pressure. The performance of the compressor can be gradually lowered if the comparison result indicates that an actual refrigerant pressure is between the first predetermined pressure and the second predetermined pressure.

Abstract: The present invention relates to a method for controlling a vehicle air-conditioner, which can prevent undershoot of an evaporator by performing a maximum capacity control or controlling an discharge capacity of a compressor through the outputting of an discharge capacity control value of the compressor directly before the stop of the air conditioner, and can improve the pleasant feelings of the passengers by preventing delay of response, which converges into the target temperature of the evaporator due to the delay of the decrease of the temperature of the evaporator.

Abstract: A pulse width modulation control is provided for a suction modulation valve in a refrigerant system. An intentional small “leakage” path is maintained through the suction modulation valve to ensure that the pressure inside the compressor shell does not decrease below a safe reliability threshold but, at the same time, does not exceed a certain value, which would cause the refrigerant system to operate inefficiently, when the pulse width modulation control has moved the suction modulation valve to a closed position. The size of this minimum “leakage” path is continuously adjusted to ensure that the optimum pressure inside the compressor shell is maintained regardless of the evaporator pressure and other operating conditions.

Abstract: A refrigerant compressor has a control valve for controlling the degree of conveyance of the refrigerant compressor by setting a drive housing pressure pC of the refrigerant compressor. A control body controls a conveying-side control line between a discharge chamber, acted upon by high pressure of the compressor, and the drive housing of the compressor, and also controls a suction-side control line between the drive housing and a suction chamber, acted upon by suction pressure of the compressor variably in a throttling and/or shutting-off manner. The control body is driven electromagnetically. To improve the refrigerating capacity and the control behavior of the refrigerating system, the control body, which can shut off both the conveying-side and the suction-side control line, is also driven by means of a pressure cell.

Abstract: A cooling system is provided that comprises: a refrigerant loop having a pump; an evaporator heat exchanger thermally coupled to a heat source, the evaporator plumbed in the loop; a condensing heat exchanger and a receiver plumbed in the loop; and an equalizing conduit plumbed between an inlet to the condenser and the receiver and comprising a flow regulating valve.

Abstract: A humidity controller includes a differential pressure detection means (93, 97) for detecting a difference between high voltage and low voltage in a refrigeration cycle of a refrigerant circuit (50) and a control means (30) for controlling the capacity of the compressor (53). The control means (30) reduces the capacity of the compressor (53) when a detected value of the differential pressure detection means (93, 97) exceeds a reduction threshold. Further, the control means (30) stops the compressor (53) when the detected value of the differential pressure detection means (93, 97) exceeds a stop threshold higher than the reduction threshold.

Abstract: A refrigerant cycle is provided with a multi-port compressor or compressor stages connected in series, and multiple condensers. A single evaporator communicates with the plurality of condensers. At least one of the plurality of condensers receives fully compressed refrigerant while the other condensers receive refrigerant at intermediate pressure. A control can optionally direct refrigerant to the condensers to achieve desired system heat rejection characteristics and operating conditions. One or multiple reheat coils may be associated with the evaporator and are arranged either in series or in parallel to provide a desired dehumidification function and reheat stages. One or several of the intermediate pressure condensers may be utilized for the reheat function as well.

Abstract: A system and method includes a compressor operable in a refrigeration circuit and including a motor, a current sensor providing a high-side signal indicative of an operating condition of a high-pressure side of the refrigeration circuit, a discharge line temperature sensor providing a low-side signal indicative of an operating condition of a low-pressure side of the refrigeration circuit, and processing circuitry processing the high-side signal and the low-side signal to indirectly determine a non-measured operating parameter of the refrigeration circuit.

Abstract: A stability control algorithm is provided for a centrifugal compressor. The stability control algorithm is used to control a variable geometry diffuser and a hot gas bypass valve (when provided) in response to the detection of compressor instabilities. The stability control algorithm can adjust the position of a diffuser ring in the variable geometry diffuser in response to the detection of a surge condition or a stall condition. The diffuser ring in the variable geometry diffuser can be adjusted to determine an optimal position of the diffuser ring. The stability control algorithm can also be used to open a hot gas bypass valve in response to the detection of continued surge conditions.

Abstract: An air-conditioning system for a motor vehicle includes a coolant circuit, through which it is possible to pump coolant with the aid of a compressor, the air-conditioning system having a torque-determining unit for determining a drive torque required for operating the compressor as a function of a temperature of air, which has flowed past an evaporator integrated into the coolant circuit for evaporating coolant, a pressure of the coolant prevailing in the coolant circuit in front of the compressor relative to a flow direction of the coolant or an actuating signal for setting a settable compressor stroke of the compressor.

Abstract: In a refrigeration cycle device with a capacity-variable compressor, a preset suction pressure that serves as a target value of a refrigerant suction pressure of the compressor is calculated and a refrigerant discharge capacity of the compressor is controlled by operating a capacity varying portion such that the suction pressure of the compressor is appreciated to the preset suction pressure. A thermal load detection portion is configured to detect a thermal load of a refrigeration cycle, and a refrigerant flow amount detection portion is configured to detect a flow amount of refrigerant circulating through the refrigeration cycle. In the refrigeration cycle device, a pressure at a predetermined part of the compressor is estimated based on the thermal load detected by the thermal load detection portion and on the flow amount detected by the refrigerant flow amount detection portion.

Abstract: A system and method includes a compressor operable in a refrigeration circuit and including a motor, a current sensor detecting current supplied to the motor, a discharge line temperature sensor detecting discharge line temperature of the compressor, and processing circuitry receiving current data from the current sensor and discharge line temperature data from the discharge line temperature sensor and processing the current data and the discharge line temperature data to determine a capacity of the refrigeration circuit.

Abstract: A refrigerant system includes a compressor with a discharge valve that temporarily restricts the compressor's outflow at startup so that the discharge pressure can quickly rise to force lubricant back to the compressor. The discharge valve also helps prevent an axial face of a rotor of a screw compressor from rubbing against a bearing housing axial face of the compressor's housing. When the system turns off under certain low ambient air temperature conditions, the valve closes to help prevent the system's evaporator from freezing up. The discharge valve includes a novel arrangement of a piston, a valve stem extending from the piston, and a valve plug pivotally attached to the valve stem. The pivotal connection ensures a positive seal between the valve plug and a valve seat. A somewhat restricted fluid passageway between the valve's discharge chamber and piston chamber helps prevent the valve from chattering as the valve opens.

Abstract: A cut-out circuit for an air conditioner protects the air conditioning system components when subjected to low pressure conditions, without manually resetting the system after low pressure cut-out. The cut-out circuit preferably includes a relay, connectable to a voltage source through a normally closed low pressure switch to a compressor clutch, the relay operable in a closed state to output a voltage from the voltage source through the low pressure switch to the clutch, and in an open state to interrupt the voltage. The low pressure switch may open responsive to a low pressure condition interrupting voltage flow to the clutch. The circuit includes a normally open high pressure switch, connected to the relay and a voltage source, operable to close responsive to a high pressure condition, to output a voltage from a voltage source to the relay for changing the relay operating state to open.

Abstract: A controller and method for control of a refrigeration system having a compressor rack operable at a plurality of capacities may include determining a rate of change in suction pressure for a first capacity, determining a rate of change in suction pressure associated with a second capacity, and determining which of the first capacity and the second capacity will produce the least variation between a measured suction pressure and a desired suction pressure based on the rate of change in suction pressure associated with each.

Abstract: A variable displacement compressor includes a housing assembly. A displacement control structure for the variable displacement compressor includes a passage forming member, a flat partition and a displacement control valve. The passage forming member is connected to an exterior surface of the housing assembly for forming a refrigerant passage for allowing the refrigerant to be discharged out from the compressor to an external refrigerant circuit. The flat partition is interposed between the passage forming member and the housing assembly. A throttle penetrates through the partition, which divides the refrigerant passage into an upstream passage and a downstream passage. The displacement control valve is provided in the passage forming member. The displacement control valve senses pressure of refrigerant in the upstream passage and pressure of the refrigerant in the downstream passage to control flow rate of the refrigerant flowing through a supply passage.

Abstract: Methods, systems, and apparatus for linearizing control of a commercial refrigeration system. In an embodiment of the invention, a controller is configured to receive a non-linear sensed suction pressure and convert the suction pressure to a linear temperature equivalent. The linear temperature equivalent is used by the controller to achieve efficient system operation over an entire range of operating temperatures.

Abstract: In a refrigeration system, a first non-inverter compressor (2B) backs up one of an inverter compressor (2A) and a second non-inverter compressor (2C) by switching of a third four-way selector valve (3C). The refrigeration system includes: a suction pressure detection section (81) for detecting the suction pressure of the first non-inverter compressor (2B) after the issue of a switching command to the third four-way selector valve (3C); a command holding section (82) for, when the detected pressure of the suction pressure detection section (81) becomes lower than a predetermined value, determining that the third four-way selector valve (3C) has malfunctioned and holding the switching command; and a compressor standby section (83) for, upon the command holding section (82) holding the switching command, stopping the first non-inverter compressor (2B) and putting it into standby for a predetermined time.

Abstract: A discharge displacement control system for a variable displacement compressor includes controlled object setting means. The controlled object setting means selects a control mode out of two or more control modes in accordance with external information detected by external information detection means, and sets a controlled object matching the selected control mode. In accordance with the external information detected by the external information detection means, the controlled object setting means sets, as the controlled object, a target pressure for one of a pressure in a suction pressure region and a pressure in a crank chamber in a first control mode, which is one of the control modes, and a target working pressure difference between a pressure in a discharge pressure region and one of the pressure in the suction pressure region and the pressure in the crank chamber in a second control mode, which is another of the control modes.

Abstract: A control method controlling a compression capacity of a variable capacity compressor (8), using a capacity control valve (13) which senses a pressure difference between a high pressure (Pd) and a low pressure (Ps) in a refrigeration cycle (7a), including: calculating a target duty factor (Dt1) for the capacity control valve (13) based on a target evaporator-exit temperature (TMeva) and an actual evaporator-exit temperature (Teva); calculating a driving torque (Trq2) of the compressor (8) as an upper-limit driving torque (Trq2) based on a high pressure (Pd) under an assumption that the compressor (8) is in a full-stroke state; calculating an estimated driving torque (Trq1) of the compressor (8) based on an actual control electric current (Isolc); and selecting the target duty factor (Dt1) as an output duty factor (Dtc) when the estimated driving torque (Trq1) is smaller than the upper-limit driving torque (Trq2), and selecting a duty factor (Dt2) calculated based on the upper-limit driving torque (Trq2) as th

Abstract: There is provided a refrigeration apparatus in which a refrigerant accumulating in non-operating outdoor units is supplied to an outdoor unit being operated in which a shortage of refrigerant occurs without starting the compressors of the non-operating outdoor units.

Abstract: A refrigerant compressor assembly for a refrigeration circuit controls the temperature within a temperature controlled space. The refrigerant compressor assembly includes a first unloading valve, a first valve actuator, and a first valve control system that adjusts the first valve actuator via a pulse-width-modulated signal, a second unloading valve, a second valve actuator, and a second valve control system that adjusts the second valve actuator via a pulse-width-modulated signal. The refrigerant compressor assembly also includes a third unloading valve. The first valve actuator is coupled to the first and third unloading valves and controlled by the first valve control system. The unloading valves selectively allow or resist fluid flow from higher to lower pressure areas within the refrigerant compressor assembly.

Abstract: A system and a method for operating a variable-displacement compressor are provided wherein a volume of a compression chamber of at least one cylinder is varied during a compression cycle, wherein during the cycle the at least one cylinder is alternately coupled to a low pressure side and a high pressure side of the compressor. A first thermodynamic state of the low pressure side and a second thermodynamic state of the high pressure side can be estimated and a current compression ratio ( v in v out ) of the compressor can be estimated. Accordingly, a compressor displacement (D) as a function of the compression ratio ( v in v out ) can be calculated. From this, a compressor torque (M) depending on the calculated displacement (D) can be computed, and the compressor torque (M) can be provided to a control unit for operating the compressor or an engine coupled to the compressor.

Abstract: A refrigerant system includes a compressor that has safe operating limits that are also built into a refrigerant system control to protect the compressor. Under certain conditions, these safe operational limits may be changed to allow the compressor to operate beyond the safety limits at least for a period of time.