A rotary compressor system includes a compressor housing that includes a compressor motor that draws in fluid from a suction side. The fluid is compressed within a compression chamber and discharged through a discharge side. The compression chamber is disposed between the suction side and the discharge side. An overload-protection switch is electrically coupled in series with the compressor motor and is adapted to cut power to the compressor motor responsive to an overload event. A solenoid valve is fluidly coupled between the compression chamber and a location upstream of the suction side and is electrically coupled in series with the overload-protection switch. An interruption of electrical current to the compressor motor also interrupts electrical current to the solenoid valve, which opens the solenoid valve to equalize pressure between the suction side and the discharge side.

A device to protect a compressor against liquid flooding, oil heater malfunction, low refrigerant charge, high superheat. The system includes a device that measures two temperatures separated by a heat source (the electric compressor or the suction heat exchanger or both). The temperature difference can detect a liquid return to the compressor, a high superheat, a low refrigerant charge or a crankcase heater malfunction and the temperature difference can control the electronic expansion valve.

An air conditioning device includes a vapor injection cycle in which an operating speed of a compressor is adjusted to improve efficiency, and a method for controlling the device. The air conditioning device includes an inner heat-exchanger for exchanging heat between a first portion of refrigerant passing through a condenser and a second portion of the refrigerant branched from the first refrigerant, and an injection channel through which the second portion of the refrigerant is injected into the compressor. The inner heat exchanger includes an outer tube and an inner tube disposed inside the outer tube. The first portion of the refrigerant flows into the inner tube, while the second portion of the refrigerant flows into the outer tube. Thus, when a variation of air-conditioning load is small and an injection super-heating temperature is low, the device enables reduction of the compressor rotation speed to ensure high injection super-heating temperature.

A method of heating a component within a heating, ventilation and air conditioning (HVAC) system is provided. The method includes maintaining a non-heating condition of the HVAC system component when the HVAC system component is in a non-operational state. The method also includes determining when the HVAC system component will switch from the non-operational state to an operational state, the determination based on a threshold parameter being met. The method further includes operating a heating device from the non-heating condition to a heating condition to heat the HVAC system component from a temperature to a target temperature suitable for the operational state of the HVAC system component.

A heat-pump air-conditioning hot-water supply device includes a first refrigerant passage connecting a compressor and a decompressor, a second refrigerant passage branching from between the compressor and a first solenoid valve and connecting a second solenoid valve, a hot-water supply heat exchanger, and the decompressor, a pressure sensor configured to measure discharge pressure of the compressor, and a control device configured to adjust an operational frequency of the compressor and adjust an opening degree of a valve of the decompressor. The control device is configured to calculate a condensing temperature from the discharge pressure, and perform operation in one of an air conditioning prioritized mode in which a preset operational frequency of the compressor is changed, and an energy saving prioritized mode in which the opening degree of the valve of the decompressor is changed, when the condensing temperature is not lower than a set condensing temperature.

A rotary compressor system includes a compressor housing that includes a compressor motor that draws in fluid from a suction side. The fluid is compressed within a compression chamber and discharged through a discharge side. The compression chamber is disposed between the suction side and the discharge side. An overload-protection switch is electrically coupled in series with the compressor motor and is adapted to cut power to the compressor motor responsive to an overload event. A solenoid valve is fluidly coupled between the compression chamber and a location upstream of the suction side and is electrically coupled in series with the overload-protection switch. An interruption of electrical current to the compressor motor also interrupts electrical current to the solenoid valve, which opens the solenoid valve to equalize pressure between the suction side and the discharge side.

A refrigeration device equipped with: a cascade cycle; a storage unit having a storage space for an object to be cooled by a second evaporator; an internal temperature sensor that detects the temperature of the storage space; a control unit that determines a second rotational speed of a second compressor on the basis of a target temperature for the storage space and the detection result from the internal temperature sensor, and that determines a first rotational speed for a first compressor having a prescribed correspondence relationship with the second rotational speed; and a first power supply unit and a second power supply unit that supply power respectively to the first compressor and the second compressor on the basis of the first rotational speed and the second rotational speed determined by the control unit.

A driving device drives a motor having coils. The driving device includes a converter to generate a bus voltage, an inverter to convert the bus voltage to an AC voltage and supply the AC voltage to the coils, and a connection switching unit to switch a connection state of the coils. The bus voltage generated by the converter is switched in accordance with the connection state of the coils.

A compressor includes a housing defining a working chamber. The housing further includes a bore and an endplate disposed toward a discharge end. The compressor further includes a rotor having helical threads, the rotor being configured to be housed in the bore, a rotor clearance, a controllable bearing supporting the rotor, and a controller configured to control the controllable bearing such that the controllable bearing moves the rotor in a manner to reduce and/or enlarge the rotor clearance.

An illustrative example refrigerant system includes a compressor configured to pressurize a refrigerant fluid. The compressor includes a sump portion. A heater is situated to heat at least the sump portion. A controller is configured to selectively operate the heater to apply heat to at least the sump portion while the compressor is off to establish and maintain a superheat condition in the compressor.