Air conditioner

Abstract

An air conditioner may be provided that includes a plurality of compressors compressing a refrigerant, a first heat exchanger for condensing the refrigerant compressed in the compressors, a first expansion valve for expanding the condensed refrigerant, a second expansion valve for expanding the refrigerant emerging from the first expansion valve, and a second heat exchanger for evaporating the refrigerant emerging from the second expansion valve. The refrigerant from the first expansion valve may be guided such that a portion of the refrigerant is introduced into one of the compressors after bypassing the second expansion valve and the second heat exchanger, and a remaining portion of the refrigerant may be introduced into another one of the compressors after passing through the second expansion valve and second heat exchanger.

1 . An air conditioner comprising:
 a first compressor;   a second compressor provided in parallel to the first compressor by a refrigerant suction line and a refrigerant discharge line;   a first heat exchanger to evaporate a refrigerant in a cooling mode, and to condense the refrigerant in a heating mode;   a second heat exchanger to condense the refrigerant in the cooling mode, and to evaporate the refrigerant in the heating mode;   a first expansion valve between the first heat exchanger and the second heat exchanger;   a second expansion valve between the first expansion valve and the second heat exchanger;   a bypass device connected between a branching point of the refrigerant suction line and the second compressor, to guide a portion of the refrigerant that is output from the first expansion valve to bypass the second expansion valve and the second heat exchanger and to flow to a point between the branching point of the refrigerant suction line and the second compressor; and   a one-way valve between the branching point of the refrigerant suction line and a connecting point of the bypass device to the refrigerant suction line, the one-way valve to prevent the refrigerant that is output from the bypass device from flowing to the branching point of the refrigerant suction line.   
     
     
         2 . The air conditioner according to  claim 1 , wherein the second compressor has a smaller displacement than the first compressor. 
     
     
         3 . The air conditioner according to  claim 2 , wherein the first compressor is a variable displacement compressor, and the second compressor is a constant speed compressor. 
     
     
         4 . The air conditioner according to  claim 1 , wherein the air conditioner operates in a first and second compressor simultaneous operation mode and operates in a second compressor operation mode,
 wherein the second compressor operation mode is a mode in which the second compressor operates alone without the first compressor, and the refrigerant that is output from the first expansion valve flows to the second compressor after passing through the second expansion valve and the second heat exchanger, and   wherein the first and second compressor simultaneous operation mode is a mode in which the first compressor and the second compressor operate simultaneously, and a first portion of the refrigerant that emerges from the first expansion valve bypass the second expansion valve and the second heat exchanger and flows to the second compressor, whereas a second portion of the refrigerant that emerges from the first expansion valve passing through the second expansion valve and the second heat exchanger and flows to the first compressor.   
     
     
         5 . The air conditioner according to  claim 4 , wherein the air conditioner selectively performs the second compressor operation mode and the first and second compressor simultaneous operation mode. 
     
     
         6 . The air conditioner according to  claim 4 , wherein the air conditioner further operates in a first compressor operation mode in which the first compressor operates alone without the second compressor, and the refrigerant that emerges from the first expansion valve passes through the second expansion valve and the second heat exchanger and flows to the first compressor. 
     
     
         7 . The air conditioner according to  claim 6 , wherein the air conditioner selectively performs the second compressor operation mode, the first and second compressor simultaneous operation mode, and the first compressor operation mode. 
     
     
         8 . The air conditioner according to  claim 1 , wherein the bypass device comprises:
 an inner heat exchanger having a first passage for guiding the refrigerant to flow between the first expansion valve and the second expansion valve, and a second passage through which the refrigerant passes while exchanging heat with the refrigerant that passes through the first passage;   a first bypass passage having a first end connected between the first passage of the inner heat exchanger and the first expansion valve, and a second end connected to the second passage of the inner heat exchanger; and   a second bypass passage having a first end connected to the second passage, and a second end connected to a suction line of the second compressor.   
     
     
         9 . The air conditioner according to  claim 8 , wherein the bypass device further comprises a third expansion valve provided at the first bypass passage. 
     
     
         10 . The air conditioner according to  claim 9 , wherein the third expansion valve has a smaller capacity than the first expansion valve and the second expansion valve. 
     
     
         11 . The air conditioner according to  claim 9 , wherein:
 at a partial heating load, the second compressor operates, the first compressor is in a stopped state, and the third expansion valve is closed; and   at a full heating load, the first compressor and the second compressor operate, and the third expansion valve are opened.   
     
     
         12 . The air conditioner according to  claim 1 , wherein the bypass device comprises:
 a gas/liquid separator provided between the first expansion valve and the second expansion valve; and   a gas/liquid separator connecting passage having a first end connected to the gas/liquid separator, and a second end connected to a suction line of the second compressor, and the gas/liquid separator to guide a gas portion of the refrigerant from the gas/liquid separator to flow to the suction line of the second compressor.   
     
     
         13 . The air conditioner according to  claim 12 , wherein the bypass device further comprises a third expansion valve provided at the gas/liquid separator connecting passage. 
     
     
         14 . The air conditioner according to  claim 13 , wherein the third expansion valve has a smaller capacity than the first expansion valve and the second expansion valve. 
     
     
         15 . The air conditioner according to  claim 13 , wherein:
 at a partial heating load, the second compressor operates, the first compressor is in a stopped state, and the third expansion valve is closed; and   at a full heating load, the first compressor and the second compressor operate, and the third expansion valve are opened.   
     
     
         16 . An air conditioner comprising:
 a plurality of compressors each to compress a refrigerant;   a first heat exchanger to condense the refrigerant compressed by at least one of the compressors;   a first expansion valve to expand the refrigerant condensed by the first heat exchanger;   a second expansion valve to expand the refrigerant that is output from the first expansion valve; and   a second heat exchanger to evaporate the refrigerant that is output from the second expansion valve,   wherein a first portion of the refrigerant that is output from the first expansion valve is provided to a first one of the plurality of compressors after bypassing the second expansion valve and the second heat exchanger, and a second portion of the refrigerant that is output from the first expansion valve is provided to a second one of the plurality of compressors after passing through the second expansion valve and the second heat exchanger, or an entirety of the refrigerant that is output from the first expansion valve is provided to one of the plurality of compressors after passing through the second expansion valve and the second heat exchanger.   
     
     
         17 . The air conditioner according to  claim 16 , further comprising a bypass device to guide the first portion of the refrigerant and the second portion of the refrigerant. 
     
     
         18 . The air conditioner according to  claim 17 , wherein the bypass device includes:
 a gas/liquid separator between the first expansion device and the second expansion device;   a gas/liquid separator connection passage having a first end connected to the gas/liquid separator and a second end connected to a suction line of one of the compressors.   
     
     
         19 . The air conditioner according to  claim 18 , wherein the gas/liquid separator receives the refrigerant expanded by the first expansion valve and separates liquid phase refrigerant and gas phase refrigerant. 
     
     
         20 . The air conditioner according to  claim 20 , wherein the bypass device further includes a third expansion device provided at the gas/liquid separator connecting passage to adjust an amount of the refrigerant flowing through the gas/liquid separator connecting passage. 
     
     
         21 . The air conditioner according to  claim 20 , wherein:
 at a partial heating load, the second one of compressor operates, the first compressor is in a stopped state, and the third expansion valve is closed; and   at a full heating load, the first compressor and the second compressor operate, and the third expansion valve are opened.   
     
     
         22 . The air conditioner according to  claim 16 , further comprising:
 at least one of a gas/liquid separator and an inner heat exchanger provided between the first expansion valve and the second expansion valve, to guide only a gas portion of the refrigerant that is output from the first expansion valve to the first one of the plurality of compressors.   
     
     
         23 . The air conditioner according to  claim 16 , wherein the first one of the plurality of compressors is a constant speed compressor, and the second one of the plurality of compressors is a variable displacement compressor having a greater displacement than the constant speed compressor. 
     
     
         24 . The air conditioner according to  claim 23 , wherein an operation frequency of the variable displacement compressor is adjusted to vary a volume ratio between the variable displacement compressor and the constant speed compressor, an intermediate pressure is controlled at which an efficiency is obtained in accordance with operating conditions.