An air-conditioning device including multiple outdoor units and an indoor unit through a pipe includes a control section that obtains a degree of subcooling at an outlet of a subcooling circuit of each outdoor unit based on a temperature detected by a temperature sensor that detects the temperature of refrigerant having passed through the subcooling circuit of each outdoor unit, obtain a target value of the degree of subcooling based on the obtained multiple degrees of subcooling, and perform the control of increasing the rotation speed of a compressor of an outdoor unit having a higher degree of subcooling than the target value and decreasing the rotation speed of a compressor of an outdoor unit having a lower degree of subcooling than the target value such that a difference in the degree of subcooling at the outlet of the subcooling circuit of each outdoor unit is decreased.

An air conditioner of an embodiment includes a plurality of outdoor units, one or more indoor units, and a control unit. The outdoor unit includes a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion valve and an outdoor blower, and the outdoor units exchange heat between the outside air and a refrigerant. The indoor unit is an indoor unit connected to the plurality of outdoor units by a refrigerant pipe, includes an indoor heat exchanger, an indoor expansion valve, and an indoor blower, and exchanges heat between the indoor air and the refrigerant. The control unit controls the plurality of outdoor units and the one or more indoor units. The control unit controls the condensation pressure of the outdoor unit in a heating operation or the suction pressure of the outdoor unit in a defrosting operation to be equal to or smaller than an upper limit pressure, which is 1/1.5 times the rated maximum pressure during the heating operation when any of the outdoor units is in the defrosting operation.

An air conditioning system and a control method are provided. The air conditioning system includes: at least one heat exchanger (1, 2); and at least one control mechanism. Each control mechanism is connected to one of the at least one heat exchanger (1, 2) and is configured to control the corresponding heat exchanger to switch between a first working state and a second working state. The heat exchanger (1, 2) drains liquid when in the first working state and stores liquid when in the second working state.

An outdoor unit for a heat pump includes a refrigerant circuit, the outdoor unit including a compressor, a discharge pipe of the refrigerant circuit connected to a discharge side of the compressor, a bottom plate, the bottom plate having a base and an outer flange protruding upward from an outer edge of the base, a heat source heat exchanger supported on the bottom plate, a liquid refrigerant pipe of the refrigerant circuit connected to the heat source heat exchanger, and a defrosting bypass pipe connected at one end to the discharge pipe and at the opposite end to the liquid refrigerant pipe, the defrosting bypass pipe being arranged between an inner side of the flange and an outer side of the heat source heat exchanger.

An air-conditioning system includes: an air conditioner including an outdoor unit and a plurality of indoor units each provided in a corresponding one of a plurality of indoor spaces and each including a first control unit; and a second control unit capable of communicating with the first control units. Each first control unit is capable of communicating with a countermeasure device if the countermeasure device is installed in correspondence with one of the indoor spaces where the first control unit is located. The second control unit has a first function of prohibiting operation of the air conditioner if a first condition where communication between the first control unit and the countermeasure device is not established in any of the indoor units is satisfied.

A heat pump device includes a compressor that compresses refrigerant, a motor that drives the compressor, an inverter that applies a desired voltage to the motor, and an inverter controlling unit that generates a pulse width modulation signal for driving the inverter, has, as operation modes, a heating operation mode performing heating operation of the compressor and a normal operation mode performing normal operation of the compressor to compress the refrigerant, and periodically changes carrier frequency, that is frequency of a carrier signal, in the heating operation mode.

A heat pump apparatus includes a refrigerant circuit and a heat medium circuit. The refrigerant circuit performs a first operation using a load-side heat exchanger as a condenser, and a second operation using the load-side heat exchanger as an evaporator. A suction pipe provided between a refrigerant flow switching valve and a compressor has a container. To the heat medium circuit, an overpressure protection relief valve and a refrigerant leakage detector are connected. When leakage of refrigerant into the heat medium circuit is detected, the refrigerant flow switching valve is switched to a second state, an expansion device is set to a closed state, and the compressor is operated. When a requirement for ending the operation of the compressor is satisfied after the leakage is detected, the compressor is stopped, and the refrigerant flow switching valve is switched to a first state.

A refrigeration apparatus includes: a compressor; an outdoor heat exchanger connected to the compressor; an indoor heat exchanger connected to the compressor; and an expansion valve disposed between the outdoor heat exchanger and the indoor heat exchanger. In cooling operation, a refrigerant flows through the compressor, the outdoor heat exchanger, the expansion valve, and the indoor heat exchanger in this order. In heating operation, the refrigerant flows through the compressor, the indoor heat exchanger, the expansion valve, and the outdoor heat exchanger in this order. The refrigerant is an HFO (hydrofluoroolefin) refrigerant or a refrigerant mixture that includes an HFO refrigerant. The indoor heat exchanger and the outdoor heat exchanger are cross-fin-type heat exchangers or stack-type heat exchangers.

To predict and detect a failure in a compressor provided in an air conditioner, the air conditioner is provided with: a heat exchanger; the compressor; piping connecting the heat exchanger and the compressor with each other; and a control unit controlling the compressor and having a compressor failure predicting and detecting means, and in this air conditioner, the compressor failure predicting and detecting means of the control unit includes: a current detecting part detecting a driving current driving the compressor; a pulsation detecting part detecting pulsation in a driving current detected by the current detecting part; and an anomaly determining part predicting or detecting any failure in the compressor based on a magnitude and a duration of pulsation in a driving current detected by the pulsation detecting part.

An electronic expansion valve and an assembly method therefor. The electronic expansion valve includes a screw rod component, a movable connection component, a valve pin component and an elastic element. One end of the elastic element abuts the movable connection component, and the other end thereof abuts the valve pin component. In the period from the valve pin component closing the valve port part to the screw rod component moving a pre-set displacement amount in the valve closing direction, the elastic element does not generate an elastic force pushing the valve pin component towards the valve port part; and in the period from the valve pin component closing the valve port part to in a case that the screw rod component moving more than the pre-set displacement amount in the valve closing direction, the elastic element generates an elastic force pushing the valve pin component towards the valve port part.