Air conditioning system

Abstract

In an air conditioning system of an embodiment, flow path switching valves are switched by a first step and a second step step by step, switched based on a threshold value of either a high pressure or a pressure difference between the high pressure and a low pressure in the first step, and switched based on a threshold value of an elapsed time after the first step is performed in the second step.

What is claimed is: 
     
         1 . An air conditioning system comprising:
 an outdoor unit including three refrigerant flow paths, the outdoor unit including a compressor, a plurality of flow path switching valves, an outdoor heat exchanger, an outdoor-side electric expansion valve, and an outdoor fan;   a plurality of indoor units each having an indoor-side electric expansion valve and an indoor heat exchanger; and   one or more branch units each having a high/low-pressure gas regulating valve and a low-pressure gas regulating valve installed therein,   wherein the branch unit and the outdoor unit are connected by the high/low-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe,   wherein the branch unit and the indoor unit are connected by a gas pipe and a liquid pipe,   wherein at least one of the plurality of flow path switching valves provided in the outdoor unit is connected so that the outdoor heat exchanger selectively communicates with a discharge side or a suction side and at least one thereof is connected so that the high/low-pressure gas pipe selectively communicates with the discharge side or the suction side, and   wherein the flow path switching valves are switched by a first step and a second step step by step, switched based on a threshold value of either a high pressure or a pressure difference between the high pressure and a low pressure in the first step, and switched based on a threshold value of an elapsed time after the first step is performed in the second step.   
     
     
         2 . The air conditioning system according to  claim 1 ,
 wherein the flow path switching valve provided in the outdoor heat exchanger is switched in the first step when the high/low-pressure gas pipe becomes a high-pressure side after switching based on the second step, and   wherein the flow path switching valve provided in the high/low-pressure gas pipe is switched in the first step when the high/low-pressure gas pipe becomes a low-pressure side after switching based on the second step.   
     
     
         3 . The air conditioning system according to  claim 2 ,
 wherein a plurality of outdoor heat exchangers each having the flow path switching valve are provided,   wherein, when all flow path switching valves provided in the plurality of outdoor heat exchangers are switched, the flow path switching valves provided in all outdoor heat exchangers are switched simultaneously in the first step or the second step, and   wherein, when any one of the flow path switching valves provided in the plurality of outdoor heat exchangers is switched, only the flow path switching valve provided in a target outdoor heat exchanger is switched in the first step or the second step.   
     
     
         4 . The air conditioning system according to  claim 1 , wherein the second step is performed within at least 3 sec after the first step is performed. 
     
     
         5 . The air conditioning system according to  claim 1 ,
 wherein a threshold value that is a reference in the first step is different when the compressor is activated and while the compressor is in operation,   wherein, if a switching operation of the flow path switching valve is performed during activation of the compressor, the first step is performed when any one of pressure differences between the high and low pressures is greater than or equal to a predetermined value, and   wherein, if the flow path switching valve is switched while the compressor is in operation, the first step is performed when either the high pressure or the pressure difference between the high pressure and the low pressure is less than or equal to a predetermined value.