An air conditioning apparatus includes a flow path switching valve. An outdoor heat exchanger is divided into a first heat exchanger and a second heat exchanger. During heating operation, a refrigerant is diverted and supplied to the first heat exchanger and the second heat exchanger. During the heating operation, the flow path switching valve combines the flows of the refrigerants discharged from the first heat exchanger and the second heat exchanger, and returns the resultant refrigerant to a refrigerant inlet of a compressor. Three ports of the flow path switching valve are internally communicated with one another while being isolated from an other single port during the heating operation. Two ports of the flow path switching valve are internally communicated with each other and other two ports are internally communicated with each other during defrosting operation of the first heat exchanger or the second heat exchanger.

Provided is a refrigeration apparatus in which a decrease in a temperature of an indoor heat exchanger can be suppressed as much as possible while depletion of refrigerator oil in a compressor is also suppressed. An air-conditioning apparatus configured from a parallel connection of a plurality of outdoor units to an indoor unit, wherein when a predetermined defrosting condition has been fulfilled, a controller includes at least one processor programmed to selectively execute a reverse-cycle defrost mode when a predetermined outflow condition pertaining to an outflow integrated quantity of refrigerator oil has also been fulfilled, and selectively execute an alternating defrost mode, in which the outdoor unit that is to be defrosted is changed in sequence, when the predetermined outflow condition has not been fulfilled.

An air-conditioning apparatus is capable of efficiently performing defrosting operation without suspending a heating operation of an indoor unit. The air-conditioning apparatus includes a main circuit sequentially connecting, via a pipe, a compressor, indoor heat exchangers, first flow control devices, and a plurality of parallel heat exchangers connected in parallel to each other to allow refrigerant to circulate, first defrost pipes branching a part of the refrigerant discharged from the compressor and causing the part of the refrigerant to flow into one of the plurality of parallel heat exchangers and to be defrosted, an interface heat exchanger located between the plurality of parallel heat exchangers, a first bypass pipe branching a part of the refrigerant discharged from the compressor and causing the part of the refrigerant to flow into the interface heat exchanger, and a second bypass pipe causing the part of the refrigerant flowing out of the interface heat exchanger to flow into the main circuit.

Disclosed in the present invention is a defrosting valve, characterized by comprising a valve body provided with a valve core therein and an upper cover thereon; a push piston is disposed in the valve core; the push piston is in a T-shape; the upper part of the push piston is inserted in the cavity of the upper cover; a return tension spring is sleeved at the lower part of the upper cover; the upper end of the return tension spring is connected to the upper cover, and the lower end is connected to the lower end of the push piston; a lower table top is disposed at the lower part in the valve body; a flow channel inlet is disposed on the upper cover; a bidirectional flow channel opening is disposed on the side wall of the valve body; and a flow channel outlet is disposed at the lower end of the valve body. Compared to the prior art, the present invention has the following positive effects: the present invention has a simple and reasonable structure and a long service life, and can sectionally defrost an evaporator, thus greatly improving the heating efficiency of an air-conditioner.

Disclosed in the present invention is a large capacity defrosting valve, comprising a valve body; the upper end of the valve body is connected to an upper end cover; the valve body is provided with a piston therein; the piston is connected to a valve core; the upper end of the valve core is connected to a tension spring; the upper end of the tension spring is connected to the lower end of the upper end cover; the lower end of the valve body is connected to a lower end cover; the valve body is provided with a first channel and a second channel thereon; the lower end cover is provided with a third channel thereon; the upper end cover is provided with a fourth channel thereon; a power cavity is formed between the piston and the upper end cover; and a buffer cavity is formed between the piston and the valve body. The present invention has no impact during operation, and has good stability, high reliability and long service lift, thus greatly improving the heating efficiency of an air-conditioner.

A refrigeration system includes a refrigerated cavity, a first compression system, and a second compression system. The refrigeration system further includes a controller configured to operate the refrigeration system in a first mode in which the first compression system and the second compression system operate to cool the refrigerated cavity. The refrigeration system is further configured to selectively operate the refrigeration system in a second mode in which a refrigerant discharged from the second compressor is routed through the first evaporator to defrost the first evaporator.

An air-conditioning apparatus includes a refrigerant circuit and a controller. The refrigerant circuit includes a main circuit and a bypass circuit. The bypass circuit is connected, by a pipe, to each of a plurality of parallel outdoor heat exchangers via a defrosting refrigerant pressure-reducing device, a defrosting flow passage switching device, and a backflow prevention device. The controller switches a flow passage for use in introduction of refrigerant using the defrosting flow passage switching device, to select one of the plurality of parallel outdoor heat exchangers as a defrosting target to be defrosted; and supplies defrosting refrigerant whose pressure is reduced by the defrosting refrigerant pressure-reducing device to the selected one of the plurality of parallel outdoor heat exchangers.

Disclosed in the present invention is a large capacity defrosting valve, comprising a valve body; the upper end of the valve body is connected to an upper end cover; the valve body is provided with a piston therein; the piston is connected to a valve core; the upper end of the valve core is connected to a tension spring; the upper end of the tension spring is connected to the lower end of the upper end cover; the lower end of the valve body is connected to a lower end cover; the valve body is provided with a first channel and a second channel thereon; the lower end cover is provided with a third channel thereon; the upper end cover is provided with a fourth channel thereon; a power cavity is formed between the piston and the upper end cover; and a buffer cavity is formed between the piston and the valve body. The present invention has no impact during operation, and has good stability, high reliability and long service lift, thus greatly improving the heating efficiency of an air-conditioner.

Disclosed in the present invention is a defrosting valve, characterized by comprising a valve body provided with a valve core therein and an upper cover thereon; a push piston is disposed in the valve core; the push piston is in a T-shape; the upper part of the push piston is inserted in the cavity of the upper cover; a return tension spring is sleeved at the lower part of the upper cover; the upper end of the return tension spring is connected to the upper cover, and the lower end is connected to the lower end of the push piston; a lower table top is disposed at the lower part in the valve body; a flow channel inlet is disposed on the upper cover; a bidirectional flow channel opening is disposed on the side wall of the valve body; and a flow channel outlet is disposed at the lower end of the valve body. Compared to the prior art, the present invention has the following positive effects: the present invention has a simple and reasonable structure and a long service life, and can sectionally defrost an evaporator, thus greatly improving the heating efficiency of an air-conditioner.

A hot gas bypass circuit that connects a discharge side of the compressor and a portion between the heat source side heat exchanger and the expansion valve, an on-off valve that opens and closes a channel of the hot gas bypass circuit, and a control device performing control to select one of hot gas bypass defrosting and reverse cycle defrosting according to a frosting amount on the heat source side heat exchanger and perform defrosting. The control device controls to open the on-off valve of the hot gas bypass circuit such that a part of a refrigerant discharged from the compressor is supplied to the heat source side heat exchanger via the hot gas bypass circuit and, the control device switches switch the four-way valve such that the refrigerant discharged from the compressor is supplied to the heat source side heat exchanger after passing through the four-way valve.