Abstract: 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.

Abstract: An air-conditioning apparatus includes: an outdoor unit including a compressor, and an outdoor heat exchanger; a first indoor unit including a first indoor heat exchanger; a relay unit including a relay heat exchanger through which the refrigerant exchanges heat with a heat medium different from the refrigerant, and a pump; and a second indoor unit including a second indoor heat exchanger, wherein the first indoor unit is installed in a first air-conditioned space, the second indoor unit is installed in a second air-conditioned space, the first air-conditioned space has a volume such that a concentration of the refrigerant in the first air-conditioned space is lower than a reference value even when a total amount of the refrigerant filled in the refrigerant circuit leaks in the first air-conditioned space, and a volume of the second air-conditioned space is smaller than the volume of the first air-conditioned space.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 second 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.

Abstract: 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.

Abstract: 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.

Abstract: A rod material made of Ti alloy has a larger diameter portion at the end, which is joined with the end of material made of Ti—Al intermetallic compound, by friction welding, to form a poppet valve for an internal combustion engine. Instead of providing such larger diameter portion, the end of the material made of Ti—Al intermetallic compound may be heated to facilitate joining.

Abstract: A Ti alloy poppet valve consists of a valve stem and a valve head, and is employed as intake or exhaust valve in an internal combustion engine of an automobile. O2 is put into the valve in a furnace at very slight amount and heated to introduce oxygen atoms into titanium of the valve to form a Ti—O interstitial solid solution without making titanium oxides. The valve is strengthened to increase hardness and wear resistance.

Abstract: Ti alloy is embedded in a powder such as graphite and heated with the powder in an oxygen atmosphere. Oxygen atoms are diffused into the Ti alloy to form an oxygen diffusion layer of Ti—O solid solution, thereby increasing wear resistance of the valve. A poppet valve in an internal combustion engine may be made of such Ti alloy.

Abstract: A Ti alloy poppet valve consists of a valve stem and a valve head, and is employed as intake or exhaust valve in an internal combustion engine of an automobile. O2 is put into the valve in a furnace at very slight amount and heated to introduce oxygen atoms into titanium of the valve to form a Ti—O interstitial solid solution without making titanium oxides. The valve is strengthened to increase hardness and wear resistance.

Abstract: Ti alloy is embedded in a powder such as graphite and heated with the powder in an oxygen atmosphere. Oxygen atoms are diffused into the Ti alloy to form an oxygen diffusion layer of Ti—O solid solution, thereby increasing wear resistance of the valve. A poppet valve in an internal combustion engine may be made of such Ti alloy.