Refrigerating and air-conditioning apparatus

Abstract

A refrigerating and air-conditioning apparatus includes an outdoor unit; a plurality of indoor units each including an indoor expansion valve and an indoor heat exchanger; a relay unit connected between the outdoor unit and the plurality of indoor units and including a plurality of three-way valves; and a controller. The plurality of indoor units each include an indoor-side pressure sensor configured to detect an indoor-side pressure, the indoor-side pressure being a pressure of refrigerant that passes through the indoor heat exchanger. The controller is configured to control, with reference to the indoor-side pressure of each of ones of the plurality of indoor units that perform cooling operations, an opening degree of a corresponding three-way valve of the plurality of three-way valves such that the controller is configured to adjust a flow rate of refrigerant passing through the corresponding three-way valve.

1 . A refrigerating and air-conditioning apparatus comprising:
 an outdoor unit including a compressor and an outdoor heat exchanger;   a plurality of indoor units each including an indoor expansion valve and an indoor heat exchanger;   a relay unit connected between the outdoor unit and the plurality of indoor units and including a plurality of three-way valves, the plurality of three-way valves each being configured to switch flows of refrigerant and to adjust a flow rate of the refrigerant that passes through the three-way valve, the plurality of three-way valves being provided in number relative to the number of the plurality of indoor units, the relay unit being configured to distribute the refrigerant in a low-temperature state to each of ones of the plurality of indoor units that perform cooling operations and the refrigerant in a high-temperature state to each of ones of the plurality of indoor units that perform heating operations; and   a controller configured to control switching and opening degrees of the plurality of three-way valves,   the plurality of indoor units each including an indoor-side pressure sensor configured to detect an indoor-side pressure, the indoor-side pressure being a pressure of the refrigerant that passes through the indoor heat exchanger,   the controller being configured to control, with reference to the indoor-side pressure of each of ones of the plurality of indoor units that perform cooling operations, the opening degree of a corresponding three-way valve of the plurality of three-way valves such that the controller is configured to adjust the flow rate of the refrigerant passing through the corresponding three-way valve.   
     
     
         2 . The refrigerating and air-conditioning apparatus of  claim 1 ,
 wherein the controller is configured to   derive from the indoor-side pressure of each of ones of the plurality of indoor units that perform cooling operations an evaporating temperature of the corresponding indoor heat exchanger,   increase the opening degree of the corresponding three-way valve when the evaporating temperature exceeds a set evaporating temperature, which is predetermined, and   reduce the opening degree of the corresponding three-way valve when the evaporating temperature is below the set evaporating temperature.   
     
     
         3 . The refrigerating and air-conditioning apparatus of  claim 1 ,
 wherein the outdoor unit further includes   an outdoor expansion valve configured to depressurize and expand the refrigerant,   an outdoor-side pressure sensor configured to detect a suction pressure, the suction pressure being a pressure of the refrigerant that is sucked into the compressor, and   an outdoor-side temperature sensor configured to detect a suction temperature, the suction temperature being a temperature of the refrigerant that is sucked into the compressor, and   wherein the controller is configured to   derive an evaporating temperature from the suction pressure,   calculate a degree of superheat from the suction temperature and the evaporating temperature, and   control an opening degree of at least one of the corresponding three-way valve, the outdoor expansion valve, and the corresponding indoor expansion valve when the degree of superheat is lower than or equal to a set degree of superheat, which is predetermined.   
     
     
         4 . The refrigerating and air-conditioning apparatus of  claim 3 , wherein the controller is configured to, in a heating main operation or in a heating only operation, reduce, when the degree of superheat is lower than or equal to the set degree of superheat, the opening degree of the three-way valve corresponding to each of ones of the plurality of indoor units that perform cooling operations. 
     
     
         5 . The refrigerating and air-conditioning apparatus of  claim 4 , wherein the controller is configured to reduce the opening degree of the outdoor expansion valve when the degree of superheat is lower than or equal to the set degree of superheat after the opening degree of the corresponding three-way valve is reduced. 
     
     
         6 . The refrigerating and air-conditioning apparatus of  claim 3 , wherein the controller is configured to, in a cooling main operation or in a cooling only operation, reduce, when the degree of superheat is lower than or equal to the set degree of superheat, the opening degree of the indoor expansion valve of each of ones of the plurality of indoor units that perform heating operations. 
     
     
         7 . The refrigerating and air-conditioning apparatus of  claim 6 , wherein the controller is configured to reduce, when the degree of superheat is lower than or equal to the set degree of superheat after the opening degree of the indoor expansion valve is reduced, the opening degree of the three-way valve corresponding to each of ones of the plurality of indoor units that perform cooling operations. 
     
     
         8 . The refrigerating and air-conditioning apparatus of  claim 1 , wherein at least one of the plurality of indoor units is configured to take in outdoor air and blow conditioned air to a corresponding one of the indoor spaces.