Air conditioner and control method thereof

Abstract

An air conditioner comprises: an outdoor unit including a compressor; a plurality of indoor units supplied with the refrigerant and performing cooling and heating operations; a mode switching unit connected between the outdoor unit and the indoor units and switches operation modes of the indoor units; a high-pressure gas pipe connected to the outlet side of the compressor and the mode switching unit; a low-pressure gas pipe connected to the inlet side of the compressor and the mode switching unit; a hot gas valve provided in a hot gas pipe connecting the high-pressure gas pipe and the low-pressure gas pipe; and a control unit which determines whether a mixed cooling and heating operation is possible, based on the indoor temperature and the cooling operation rates of the plurality of indoor units, and controls the hot gas valve based on whether the mixed cooling and heating operation is possible.

What is claimed is: 
     
         1 . An air conditioner comprising:
 an outdoor unit including a compressor configured to compress a refrigerant;   a plurality of indoor units configured to perform at least one of a cooling operation or a heating operation by receiving the refrigerant from the outdoor unit;   a mode switching unit comprising circuitry connected between the outdoor unit and the plurality of indoor units and configured to switch an operation mode of the plurality of indoor units;   a high-pressure gas pipe connected to an outlet side of the compressor and the mode switching unit;   a low-pressure gas pipe connected to an inlet side of the compressor and the mode switching unit;   a hot gas valve provided on a hot gas pipe connecting the high-pressure gas pipe and the low-pressure gas pipe; and   a controller including at least one processor, comprising processing circuitry, individually and/or collectively, configured to: determine whether a combined cooling and heating operation is possible based on an indoor temperature and a cooling operation rate of the plurality of indoor units, and control the hot gas valve based on whether the combined cooling and heating operation is possible.   
     
     
         2 . The air conditioner of  claim 1 , wherein
 the controller is configured to determine that the combined cooling and heating operation is possible based on the indoor temperature being less than or equal to a threshold value and the cooling operation rate being less than or equal to a reference value.   
     
     
         3 . The air conditioner of  claim 2 , wherein
 the controller is configured to, based on a determination that the combined cooling and heating operation is possible, close the hot gas valve and maintain pressure of the high-pressure gas pipe based on closing of the hot gas valve.   
     
     
         4 . The air conditioner of  claim 1 , further comprising:
 a liquid pipe connected to the inlet side of the compressor and the mode switching unit;   a bypass pipe connected to the high-pressure pipe and the liquid pipe; and   a high-pressure valve provided on the bypass pipe.   
     
     
         5 . The air conditioner of  claim 4 , wherein
 the bypass pipe is provided in any of the outdoor unit or the mode switching unit.   
     
     
         6 . The air conditioner of  claim 4 , wherein
 the controller is configured to, based on the indoor temperature being less than or equal to the threshold value or the cooling operation rate being less than or equal to the reference value, close the hot gas valve and increase pressure of the high-pressure gas pipe based on closing of the hot gas valve.   
     
     
         7 . The air conditioner of  claim 6 , wherein
 the controller is configured to, based on reception of a heating operation signal from at least one of the plurality of indoor units, open the high-pressure valve and increase the pressure of the high-pressure gas pipe.   
     
     
         8 . The air conditioner of  claim 7 , wherein
 the controller is configured to increase the pressure of the high-pressure gas pipe by opening the high-pressure valve in stages.   
     
     
         9 . The air conditioner of  claim 8 , wherein
 the controller is configured to switch the plurality of indoor units from the cooling operation to the combined operation after the pressure of the high-pressure gas pipe increases.   
     
     
         10 . A method of controlling an air conditioner, the air conditioner including an outdoor unit including a compressor configured to compress a refrigerant, a plurality of indoor units configured to perform at least one of a cooling operation or a heating operation, a mode switching unit configured to switch an operation mode of the plurality of indoor units, a high-pressure gas pipe, a low-pressure gas pipe, and a hot gas valve provided on a hot gas pipe, the control method comprising:
 receiving an indoor temperature and a cooling operation rate of the plurality of indoor units;   determining whether a combined cooling and heating operation is possible based on the indoor temperature and the cooling operation rate of the plurality of indoor units; and   controlling the hot gas valve based on whether the combined cooling and heating operation is possible.   
     
     
         11 . The method of  claim 10 , wherein
 the determining of whether the combined cooling and heating operation is possible comprises:   based on the indoor temperature being less than or equal to a threshold value or the cooling operation rate being less than or equal to a reference value, determining that the combined cooling and heating operation is possible.   
     
     
         12 . The method of  claim 11 , further comprising:
 based on determination that the combined cooling and heating operation is possible, closing the hot gas valve and maintaining pressure of the high-pressure gas pipe based on closing of the hot gas valve.   
     
     
         13 . The method of  claim 10 , further comprising:
 based on the indoor temperature being less than or equal to the threshold value or the cooling operation rate being less than or equal to the reference value, closing the hot gas valve and increasing pressure of the high-pressure gas pipe based on closing of the hot gas valve.   
     
     
         14 . The method of  claim 13 , wherein:
 the increasing of the pressure of the high-pressure gas pipe comprises:   opening the high-pressure valve based on reception of a heating operation signal from at least one of the plurality of indoor units and increasing the pressure of the high-pressure gas pipe before the plurality of indoor units are switched to the combined operation.   
     
     
         15 . The method of  claim 14 , further comprising:
 increasing the pressure of the high-pressure gas pipe by opening the high-pressure valve in stages.