Mitsubishi Electric Corporation

Hiroaki Asanuma

Takuya Matsuda

Hiroyuki Okano

Kosuke Tanaka

Yusuke Shimazu

Katsuhiro Ishimura

Yohei Kato

Hiroki Ishiyama

Hiroki Maruyama

Satoru Yanachi

Kazuki Okochi

Kohei Kasai

A refrigeration cycle apparatus includes a refrigerant circuit in which a compressor, a first heat exchanger, a first expansion device, a second expansion device, and a second heat exchanger are connected by refrigerant pipes and through which refrigerant circulates, an accumulator provided to the refrigerant circuit, formed to store liquid refrigerant, and from which gas refrigerant is caused to be sucked into the compressor, a liquid-level sensing device provided to the accumulator and sensing a liquid level of the liquid refrigerant stored in the accumulator, and a controller performs, in a case in which the liquid level sensed by the liquid-level sensing device is higher than a threshold, a limiting operation of reducing an amount of suction of the gas refrigerant that is sucked from the accumulator into the compressor and, in a case in which the liquid level is lower than or equal to the threshold, a normal operation.

Refrigeration cycle apparatus

An air-conditioning apparatus including heat source apparatuses each including a compressor and an accumulator includes: a refrigerant amount calculation unit that calculates an amount of the refrigerant accumulated in the accumulator in one of the heat source apparatuses that is to be controlled; a refrigerant differential amount calculation unit configured to calculate, when the number of the heat source apparatuses is two, a differential amount between the calculated amount and an amount of the refrigerant in the accumulator in the other heat source apparatus, and calculate, when the number of the heat source apparatuses is three or more, a differential amount between the calculated amount of the refrigerant and an average amount of amounts of the refrigerant accumulated in the accumulators in the heat source apparatuses; and a liquid equalization control unit that controls the heat source apparatus to be controlled, based on the calculated differential amount.

Air-conditioning apparatus and method of controlling the same

An air-conditioning apparatus includes a refrigerant circuit in which a compressor, a heat source heat exchanger, an expansion device, and a load heat exchanger are connected via refrigerant pipes; a refrigerant leakage sensor configured to output a refrigerant leakage detection signal indicating detection of refrigerant leakage when the refrigerant leakage sensor detects the refrigerant leakage; a refrigerant leakage cutoff device configured to cut off a flow of refrigerant when the refrigerant leakage cutoff device is set to a closed state; and a controller configured to determine whether refrigerant leakage occurs on the basis of an operating state and whether the refrigerant leakage detection signal is received from the refrigerant leakage sensor. When the controller receives the refrigerant leakage detection signal and determines, on the basis of the operating state, that the refrigerant leakage occurs, the controller is configured to set the refrigerant leakage cutoff device to the closed state.

Air-conditioning apparatus and air-conditioning system

A liquid level detection device detecting a liquid level of a liquid in a container includes a heater configured to heat the container, a plurality of temperature sensors provided at different heights of the container, and configured to detect a surface temperature of the container, and a controller configured to detect the liquid level of the liquid in the container, based on the surface temperature of the container detected by the plurality of temperature sensors when the heater is caused to heat.

Liquid level detection device, accumulator, and air-conditioning apparatus

An air-conditioning apparatus includes a controller configured to control operations of an outdoor fan. The controller has a voltage acquisition unit configured to acquire drive voltages of the outdoor fan at set time intervals while the rotation speed of the outdoor fan is maintained at a reference rotation speed, a determination unit configured to determine whether or not an acquired drive voltage is equal to or greater than a lower limit threshold and less than an upper limit threshold, an extraction unit configured to calculate an evaluation value by extracting a drive voltage determined to be equal to or greater than the lower limit threshold and less than the upper limit threshold, and a defrosting determination unit configured to decide to defrost the outdoor heat exchanger if the calculated evaluation value is equal to or greater than an evaluation threshold.

Air-conditioning apparatus

A refrigeration cycle apparatus includes a refrigerant circuit, a fan configured to send air to a heat exchanger, and a controller. The controller is configured to switch among a first operation, a second operation, and a third operation. In the first operation, the heat exchanger is caused to act as an evaporator. In the second operation, the heat exchanger is caused to act as a radiator to defrost the heat exchanger. In the third operation that is performed after the second operation, a compressor is stopped and the fan is operated at a constant rotational speed. The controller is configured to finish the third operation and start the first operation when a physical value positively correlated with electric power supplied to the fan falls to or below a threshold value during the third operation.

An air conditioning system includes a bypass passage and a cooling-heating switching mechanism. The bypass passage is configured to be at least a part of a flow passage connecting a third port to a refrigerant inlet of a compressor. A linear expansion valve opens and closes the bypass passage. The cooling-heating switching mechanism includes check valves and four-way valves. The four-way valve causes a refrigerant outlet of the check valve to communicate with one of the refrigerant inlet and a refrigerant outlet of the compressor. The four-way valve causes a refrigerant inlet of the check valve to communicate with one of the refrigerant inlet and the refrigerant outlet of the compressor and causes a port to communicate with the other of the refrigerant inlet and the refrigerant outlet.

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Tokyo, Japan

Hiroaki Asanuma