A multi-type air conditioning device controls an evaporation temperature and a condensing temperature, depending on required capacity of an indoor unit. The air conditioning device compares a current evaporation temperature or condensing temperature with a reference value, of an evaporation temperature or an condensing temperature, corresponding to a lower limit flow rate, of a gaseous refrigerant, required for refrigerating machine oil not to accumulate in, but to flow through, the gas branch pipes, and calculates an amount of the refrigerating machine oil accumulated in a gas branch pipe which does not satisfy the lower limit flow rate. When the calculated amount exceeds a set amount, the air conditioning device performs oil collecting operation, and controls the oil collecting operation in view of a flow rate of a gaseous refrigerant in gas branch pipes.

A refrigeration cycle apparatus controller includes an expansion-valve controller configured to output an opening-degree command for an expansion valve based on a deviation between a discharge temperature of refrigerant discharged from a compressor and a set discharge temperature, and at least two control parameters including a proportionality coefficient and an integral coefficient, a flow-rate-correction-coefficient calculator configured to calculate a flow-rate correction coefficient from a refrigerant flow rate of refrigerant circulating through a refrigerant circuit and a preset flow-rate reference value, and a coefficient corrector configured to calculate the proportionality coefficient by correcting a preset proportionality-coefficient reference value based on the flow-rate correction coefficient, and calculate the integral coefficient by correcting a preset integral-coefficient reference value based on the flow-rate correction coefficient. The proportionality coefficient and the integral coefficient are calculated such that a variation range of the integral coefficient rate is larger than a variation range of the proportionality coefficient.

An air conditioner has a refrigerant circuit filled with a predetermined amount of a refrigerant, the circuit being formed of an outdoor unit and an indoor unit connected to each other by refrigerant piping, the outdoor unit having a compressor, an outdoor heat exchanger, and an expansion valve, the indoor unit having an indoor heat exchanger. The conditioner has an estimation model that estimates an amount of remaining refrigerant remaining in the circuit by using at least rotation frequency of the compressor, refrigerant discharge temperature at the compressor, heat exchanger temperature, degree of opening of the expansion valve, and outside air temperature, of operation state quantities indicating operation states during operation. The indoor heat exchanger has a sensor that is provided at an indoor heat exchanger intermediate portion connecting a first indoor heat exchanger port and a second indoor heat exchanger port to each other.

No studies have been made regarding what kinds of refrigerants should be used in a refrigeration cycle device for a vehicle. An air conditioner (1) for a vehicle includes a refrigerant circuit (10) and a refrigerant that is sealed in the refrigerant circuit (10). The refrigerant circuit (10) includes a compressor (80), a first heat exchanger (85), which serves as a heat dissipater in a dehumidifying heating mode, an outside-air heat exchanger (82), a cooling control valve (87), and a second heat exchanger (86), which serves as an evaporator in the dehumidifying heating mode. The refrigerant is a refrigerant having a low GWP.

The invention discloses a multi-split system with partitioned control. An output end of a compressor is in communication with first interfaces of a first four-way valve, a second four-way valve, and a third four-way valve respectively, a third interface of the first four-way valve is in communication with one end of an outdoor heat exchanger, a second interface of the second four-way valve is in communication with one end of one indoor unit set therein, a third interface of the third four-way valve is in communication with one end of the other indoor unit set, and the other end of the outdoor heat exchanger and the other ends of the indoor unit sets are in communication with each other in a convergence manner; the remaining interfaces of the second four-way valve and the third four-way valve are all in communication with an air return end of the compressor.

A heat exchanger includes a pipe made of aluminum, a thermistor, and an attaching portion with which the thermistor is attached to the pipe. The pipe carries a flow of refrigerant. The thermistor detects a temperature of the refrigerant. The pipe includes a sacrificial layer provided on a part of a surface of the pipe. The sacrificial layer is lower in potential than the aluminum of the pipe. The attaching portion is higher in potential than the sacrificial layer. At least one part of the attaching portion is attached to the surface of the pipe where the sacrificial layer is not provided. The attaching portion includes a brazed portion that is higher in potential than the sacrificial layer. The thermistor is attached to the pipe with the brazed portion.

Air conditioner units and methods of operating the same are provided. A method of operating an air conditioner unit includes determining a fan speed as a function of a compressor speed of a variable speed compressor of the air conditioner unit. The method also includes activating a variable speed fan of the air conditioner unit at the fan speed. An air conditioner unit may include a controller, and the controller may be configured for performing the method.

A refrigeration cycle apparatus includes; a refrigerant circuit in which a compressor, a heat-source-side heat exchanger, a first expansion device, a second expansion device, and a load-side heat exchanger are sequentially connected by refrigerant pipes and in which refrigerant is circulated; a controller that controls the refrigerant circuit; a bypass pipe extending from a liquid pipe between the first expansion device and the second expansion device toward a suction side of the compressor; a third expansion device provided at the bypass pipe to decompress the refrigerant that flows through the bypass pipe; and a refrigerant cooler provided at the bypass pipe and downstream of the third expansion device to cause heat exchange to be performed between the refrigerant decompressed by the third expansion device and heat generated from the controller.

An air conditioner switches between a normal refrigeration cycle and a defrosting refrigeration cycle, and includes: a refrigerant circuit that connects a first heat exchanger, a second heat exchanger, a radiation panel, and an expansion valve that regulates a flow rate of a refrigerant flowing through the radiation panel; and a controller that causes the air conditioner to switch between the normal refrigeration cycle and the defrosting cycle. During the normal refrigeration cycle, the radiation panel performs cooling or heating. During the defrosting cycle, the first heat exchanger serves as a radiator and the second heat exchanger serves as an evaporator. During the defrosting cycle, the controller causes the expansion valve to be in a fully closed state.

An air conditioner comprises: a refrigerant circuit configured to circulate refrigerant through a compressor, a condenser, an LEV and an evaporator; a first temperature sensor configured to sense the temperature of liquid refrigerant at the inlet port of the evaporator; and a controller configured to control the compressor and the LEV. In a case where a temperature sensed by the first temperature sensor is lower than a frosting reference temperature, the controller increases the opening degree of the LEV and also increases the operating frequency of the compressor as compared with a case where the temperature sensed by the first temperature sensor is higher than the frosting reference temperature.