Air conditioner and control method thereof

Abstract

An air conditioner that improves efficiency of an inverter compressor by injecting an intermediate pressure refrigerant to the inverter compressor during heating or cooling and a control method thereof are provided.

What is claimed is: 
     
         1 . An air conditioner comprising:
 a dual inverter compressor that includes a first inverter compressor and a second inverter compressor and compresses a refrigerant at a high temperature and at a high pressure;   an indoor heat exchanger that liquefies the refrigerant supplied from the dual inverter compressor;   an expansion valve that decompresses and expands the refrigerant supplied from the indoor heat exchanger;   an outdoor heat exchanger that vaporizes the refrigerant supplied from the expansion valve;   a bypass pipe that is bypassed in a refrigerant pipe for connecting the indoor heat exchanger and the outdoor heat exchanger, and in which an electric expansion valve is installed;   an inner heat exchanger that is provided between the indoor heat exchanger and the outdoor heat exchanger, and is connected with the bypass pipe to generate an intermediate pressure refrigerant through heat exchange of the refrigerant moved from the indoor heat exchanger to the outdoor heat exchanger and the refrigerant bypassed to the bypass pipe;   an intermediate pressure refrigerant guide pipe that guides the intermediate pressure refrigerant generated through the heat exchange in the inner heat exchanger to the dual inverter compressor, and in which an intermediate pressure refrigerant shut-off valve for controlling injection of the intermediate pressure refrigerant to the dual inverter compressor or controlling the injection to be prevented, and an intermediate pressure refrigerant spraying port for spraying the intermediate pressure refrigerant that has passed through the intermediate pressure refrigerant shut-off valve to the dual inverter compressor are installed; and   an intermediate pressure refrigerant branch pipe that is branched in the intermediate pressure refrigerant guide pipe, and in which an opening and closing valve for controlling the intermediate pressure refrigerant to be injected to the dual inverter compressor along the intermediate pressure refrigerant guide pipe is installed.   
     
     
         2 . The air conditioner according to  claim 1 , wherein the inner heat exchanger performs heat exchange between the refrigerant that is moved from the indoor heat exchanger to the outdoor heat exchanger and the refrigerant that is bypassed to the bypass pipe and enters the inner heat exchanger, so that the refrigerant moved from the indoor heat exchanger to the outdoor heat exchanger is supercooled and the refrigerant bypassed to the bypass pipe and entering the inner heat exchanger is superheated. 
     
     
         3 . The air conditioner according to  claim 1 , further comprising:
 an accumulator that is provided so as to be connected with the intermediate pressure refrigerant branch pipe, and stores the intermediate pressure refrigerant injected through the intermediate pressure refrigerant branch pipe when the opening and closing valve is opened.   
     
     
         4 . The air conditioner according to  claim 1 , wherein the intermediate pressure refrigerant branch pipe is provided so as to be connected to a refrigerant pipe, which connects the intermediate pressure refrigerant branch pipe to the dual inverter compressor, and which enables the intermediate pressure refrigerant injected through the intermediate pressure refrigerant branch pipe to be supplied to the dual inverter compressor together with a refrigerant moved from the outdoor heat exchanger to the dual inverter compressor when the opening and closing valve is opened. 
     
     
         5 . The air conditioner according to  claim 1 , wherein the intermediate pressure refrigerant shut-off valve includes a first intermediate pressure refrigerant shut-off valve for controlling injection of the intermediate pressure refrigerant to the first inverter compressor and a second intermediate pressure refrigerant shut-off valve for controlling injection of the intermediate pressure refrigerant to the second inverter compressor. 
     
     
         6 . The air conditioner according to  claim 5 , wherein a muffler is provided between the first inverter compressor and the first intermediate pressure refrigerant shut-off valve and between the second inverter compressor and the second intermediate pressure refrigerant shut-off valve. 
     
     
         7 . The air conditioner according to  claim 1 , further comprising:
 a control unit that controls the electric expansion valve, the opening and closing valve, and the intermediate pressure refrigerant shut-off valve.   
     
     
         8 . An air conditioner comprising:
 a dual inverter compressor that includes a first inverter compressor and a second inverter compressor, and compresses a refrigerant at a high temperature and at a high pressure;   an outdoor heat exchanger that liquefies the refrigerant supplied from the dual inverter compressor;   an expansion valve that decompresses and expands the refrigerant supplied from the outdoor heat exchanger;   an indoor heat exchanger that vaporizes the refrigerant supplied from the expansion valve;   a bypass pipe that is bypassed in a refrigerant pipe for connecting the outdoor heat exchanger and the indoor heat exchanger, and in which an electric expansion valve is installed;   an inner heat exchanger that is provided between the outdoor heat exchanger and the indoor heat exchanger and is connected with the bypass pipe to generate an intermediate pressure refrigerant through heat exchange of the refrigerant moved from the outdoor heat exchanger to the indoor heat exchanger and the refrigerant bypassed to the bypass pipe;   an intermediate pressure refrigerant guide pipe that guides the intermediate pressure refrigerant generated through the heat exchange in the inner heat exchanger to the dual inverter compressor, and in which an intermediate pressure refrigerant shut-off valve for controlling injection of the intermediate pressure refrigerant to the dual inverter compressor or controlling the injection to be prevented and an intermediate pressure refrigerant spraying port for spraying the intermediate pressure refrigerant that passed through the intermediate pressure refrigerant shut-off valve to the dual inverter compressor are installed; and   an intermediate pressure refrigerant branch pipe that connects the intermediate pressure refrigerant guide pipe and an accumulator, and in which an opening and closing valve for controlling the intermediate pressure refrigerant to be injected to the dual inverter compressor along the intermediate pressure refrigerant guide pipe or to be discharged to the accumulator is installed.   
     
     
         9 . The air conditioner according to  claim 8 , wherein the inner heat exchanger performs heat exchange between the refrigerant that is moved from the outdoor heat exchanger to the indoor heat exchanger and the refrigerant that is bypassed to the bypass pipe and enters the inner heat exchanger, so that the refrigerant moved from the outdoor heat exchanger to the indoor heat exchanger is supercooled and the refrigerant bypassed to the bypass pipe and entering the inner heat exchanger is superheated. 
     
     
         10 . The air conditioner according to  claim 8 , wherein the accumulator stores the intermediate pressure refrigerant injected through the intermediate pressure refrigerant branch pipe when the opening and closing valve is opened. 
     
     
         11 . The air conditioner according to  claim 8 , wherein the intermediate pressure refrigerant branch pipe is provided so as to be connected to a refrigerant pipe, which connects the intermediate pressure refrigerant branch pipe to the dual inverter compressor, and which enables the intermediate pressure refrigerant injected through the intermediate pressure refrigerant branch pipe to be supplied to the dual inverter compressor together with a refrigerant moved from the indoor heat exchanger to the dual inverter compressor when the opening and closing valve is opened. 
     
     
         12 . The air conditioner according to  claim 8 , wherein the intermediate pressure refrigerant shut-off valve includes a first intermediate pressure refrigerant shut-off valve for controlling injection of the intermediate pressure refrigerant to the first inverter compressor and a second intermediate pressure refrigerant shut-off valve for controlling injection of the intermediate pressure refrigerant to the second inverter compressor. 
     
     
         13 . The air conditioner according to  claim 12 , wherein a muffler is provided between the first inverter compressor and the first intermediate pressure refrigerant shut-off valve and between the second inverter compressor and the second intermediate pressure refrigerant shut-off valve. 
     
     
         14 . The air conditioner according to  claim 8 , further comprising:
 a control unit that controls the electric expansion valve, the opening and closing valve, and the intermediate pressure refrigerant shut-off valve.   
     
     
         15 . A method for controlling a heating operation of an air conditioner including a dual inverter compressor having a first inverter compressor and a second inverter compressor, an indoor heat exchanger, and an outdoor heat exchanger, the method comprising:
 enabling a partial refrigerant to be expanded in a bypass pipe that is bypassed from a refrigerant pipe for connecting the indoor heat exchanger and the outdoor heat exchanger by opening an electric expansion valve installed in the bypass pipe;   generating an intermediate pressure refrigerant by supplying the refrigerant of the bypass pipe to the inner heat exchanger installed in the refrigerant pipe for connecting the indoor heat exchanger and the outdoor heat exchanger;   shutting off an opening and closing valve that is provided in an intermediate pressure refrigerant branch pipe branched in an intermediate pressure refrigerant guide pipe for connecting the inner heat exchanger and the dual inverter compressor so that the intermediate pressure refrigerant is moved through the intermediate pressure refrigerant guide pipe; and   enabling the intermediate pressure refrigerant to be injected to the dual inverter compressor through the intermediate pressure refrigerant guide pipe by opening the intermediate pressure refrigerant shut-off valve provided in the intermediate pressure refrigerant guide pipe.   
     
     
         16 . The method according to  claim 15 , wherein, when the electric expansion valve is opened, the refrigerant bypassed to the bypass pipe is expanded in the electric expansion valve and then injected to the inner heat exchanger to be heat-exchanged with the refrigerant moved from the indoor heat exchanger to the outdoor heat exchanger, the refrigerant moved from the indoor heat exchanger to the outdoor heat exchanger is supercooled through heat exchange to be supplied to the outdoor heat exchanger, and the refrigerant bypassed to the bypass pipe is supplied to the dual inverter compressor in a state of absorbing heat. 
     
     
         17 . A method for controlling a heating operation of an air conditioner including a dual inverter compressor having a first inverter compressor and a second inverter compressor, an indoor heat exchanger, and an outdoor heat exchanger, the method comprising:
 preventing a refrigerant from flowing to a bypass pipe that is bypassed in a refrigerant pipe for connecting the indoor heat exchanger and the outdoor heat exchanger and is connected with an inner heat exchanger provided in the refrigerant pipe, by shutting off an electric expansion valve installed in the bypass pipe, so that an intermediate pressure refrigerant is prevented from being injected to the dual inverter compressor.   
     
     
         18 . The method according to  claim 17 , wherein, when the intermediate pressure refrigerant is prevented from being injected to the dual inverter compressor by shutting off the electric expansion valve, an opening and closing valve that is installed in an intermediate pressure refrigerant branch pipe branched in an intermediate pressure refrigerant guide pipe for connecting the inner heat exchanger and the dual inverter compressor is maintained to be opened, so that an increase in piping stress due to an internal flow of the intermediate pressure refrigerant guide pipe is prevented. 
     
     
         19 . The method according to  claim 18 , wherein, when the intermediate pressure refrigerant is prevented from being injected to the dual inverter compressor by shutting off the electric expansion valve and opening the opening and closing valve, the intermediate pressure refrigerant shut-off valve provided in the intermediate pressure refrigerant guide pipe is maintained to be opened, so that chattering that occurs when the refrigerant flows in a direction opposite to a refrigerant flow direction of the intermediate pressure refrigerant shut-off valve, and occurrence of vibration of the intermediate pressure refrigerant guide pipe are reduced. 
     
     
         20 . A method for controlling a heating operation of an air conditioner including a dual inverter compressor having a first inverter compressor and a second inverter compressor, an indoor heat exchanger, and an outdoor heat exchanger, the method that prevents injection of an intermediate pressure refrigerant to the dual inverter compressor, and controls a refrigerant moved from the indoor heat exchanger to the outdoor heat exchanger to be supercooled, the method comprising:
 enabling a refrigerant to be bypassed to a bypass pipe by opening an electric expansion valve installed in the bypass pipe that is bypassed in a refrigerant pipe for connecting the indoor heat exchanger and the outdoor heat exchanger and connected to an inner heat exchanger provided in the refrigerant pipe; and   preventing the intermediate pressure refrigerant from being injected to the dual inverter compressor by opening an opening and closing valve installed in an intermediate pressure refrigerant branch pipe branched in an intermediate pressure refrigerant guide pipe for connecting the inner heat exchanger and the dual inverter compressor so that the intermediate pressure refrigerant generated in the inner heat exchanger is moved through the intermediate pressure refrigerant branch pipe to be stored in an accumulator connected with the intermediate pressure refrigerant branch pipe.   
     
     
         21 . The method according to  claim 20 , wherein, when the intermediate pressure refrigerant is prevented from being injected to the dual inverter compressor by opening the electric expansion valve and the opening and closing valve, an intermediate pressure refrigerant shut-off valve provided in the intermediate pressure refrigerant guide pipe is maintained to be opened, so that chattering that occurs when the refrigerant flows in a direction opposite to a refrigerant flow direction of the intermediate pressure refrigerant shut-off valve, and occurrence of vibration of the intermediate pressure refrigerant guide pipe are reduced. 
     
     
         22 . A method for controlling a cooling operation of an air conditioner including a dual inverter compressor having a first inverter compressor and a second inverter compressor, an indoor heat exchanger, and an outdoor heat exchanger, the method comprising:
 enabling a partial refrigerant to be expanded in a bypass pipe that is bypassed from a refrigerant pipe for connecting the outdoor heat exchanger and the indoor heat exchanger by opening an electric expansion valve installed in the bypass pipe;   generating an intermediate pressure refrigerant by supplying the refrigerant of the bypass pipe to the inner heat exchanger installed in the refrigerant pipe for connecting the outdoor heat exchanger and the indoor heat exchanger;   shutting off an opening and closing valve that is provided in an intermediate pressure refrigerant branch pipe branched in an intermediate pressure refrigerant guide pipe for connecting the inner heat exchanger and the dual inverter compressor so that the intermediate pressure refrigerant is moved through the intermediate pressure refrigerant guide pipe; and   enabling the intermediate pressure refrigerant to be injected to the dual inverter compressor through the intermediate pressure refrigerant guide pipe by opening the intermediate pressure refrigerant shut-off valve provided in the intermediate pressure refrigerant guide pipe.   
     
     
         23 . The method according to  claim 22 , wherein, when the electric expansion valve is opened, the refrigerant bypassed to the bypass pipe is expanded in the electric expansion valve and then injected to the inner heat exchanger to be heat-exchanged with the refrigerant moved from the outdoor heat exchanger to the indoor heat exchanger, the refrigerant moved from the outdoor heat exchanger to the indoor heat exchanger is supercooled through heat exchange to be supplied to the indoor heat exchanger, and the refrigerant bypassed to the bypass pipe is supplied to the dual inverter compressor in a state of absorbing heat. 
     
     
         24 . A method for controlling a cooling operating of an air conditioner including a dual inverter compressor having a first inverter compressor and a second inverter compressor, an indoor heat exchanger, and an outdoor indoor exchanger, the method comprising:
 preventing a refrigerant from flowing to a bypass pipe that is bypassed in a refrigerant pipe for connecting the outdoor heat exchanger and the indoor heat exchanger and is connected with an inner heat exchanger provided in the refrigerant pipe, by shutting off an electric expansion valve installed in the bypass pipe, so that an intermediate pressure refrigerant is prevented from being injected to the dual inverter compressor.   
     
     
         25 . The method according to  claim 24 , wherein, when the intermediate pressure refrigerant is prevented from being injected to the dual inverter compressor by shutting off the electric expansion valve, an opening and closing valve that is installed in an intermediate pressure refrigerant branch pipe branched in an intermediate pressure refrigerant guide pipe for connecting the inner heat exchanger and the dual inverter compressor is maintained to be opened, so that an increase in piping stress due to an internal flow of the intermediate pressure refrigerant guide pipe is prevented. 
     
     
         26 . The method according to  claim 25 , wherein, when the intermediate pressure refrigerant is prevented from being injected to the dual inverter compressor by shutting off the electric expansion valve and opening the opening and closing valve, the intermediate pressure refrigerant shut-off valve provided in the intermediate pressure refrigerant guide pipe is maintained to be opened, so that chattering that occurs when the refrigerant flows in a direction opposite to a refrigerant flow direction of the intermediate pressure refrigerant shut-off valve, and occurrence of vibration of the intermediate pressure refrigerant guide pipe are reduced. 
     
     
         27 . A method for controlling a cooling operation of an air conditioner including a dual inverter compressor having a first inverter compressor and a second inverter compressor, an indoor heat exchanger, and an outdoor heat exchanger, the method that prevents injection of an intermediate pressure refrigerant to the dual inverter compressor, and controls a refrigerant moved from the indoor heat exchanger to the outdoor heat exchanger to be supercooled, the method comprising:
 enabling a refrigerant to be bypassed to a bypass pipe by opening an electric expansion valve installed in the bypass pipe that is bypassed in a refrigerant pipe for connecting the outdoor heat exchanger and the indoor heat exchanger and connected to an inner heat exchanger provided in the refrigerant pipe; and preventing the intermediate pressure refrigerant from being injected to the dual inverter compressor by opening an opening and closing valve installed in an intermediate pressure refrigerant branch pipe branched in an intermediate pressure refrigerant guide pipe for connecting the inner heat exchanger and the dual inverter compressor so that the intermediate pressure refrigerant generated in the inner heat exchanger is moved through the intermediate pressure refrigerant branch pipe to be stored in an accumulator connected with the intermediate pressure refrigerant branch pipe.   
     
     
         28 . The method according to  claim 27 , wherein, when the intermediate pressure refrigerant is prevented from being injected to the dual inverter compressor by opening the electric expansion valve and the opening and closing valve, an intermediate pressure refrigerant shut-off valve provided in the intermediate pressure refrigerant guide pipe is maintained to be opened, so that chattering that occurs when the refrigerant flows in a direction opposite to a refrigerant flow direction of the intermediate pressure refrigerant shut-off valve, and occurrence of vibration of the intermediate pressure refrigerant guide pipe are reduced.