Air conditioner and method of controlling the same

Abstract

An air conditioner includes a compressor; a flow switching part disposed at an outlet side of the compressor to switch a flow direction of a refrigerant according to whether a cooling operation or heating operation is performed; an outdoor heat exchanger connected to the flow switching part and having a plurality of the refrigerant pipes to guide the refrigerant which heat-exchanges with outdoor air; and a main expansion valve connected to one side of the outdoor heat exchanger. A first inlet/outlet pipe connects the flow switching part to the outdoor heat exchanger; and a second inlet/outlet pipe connects the outdoor heat exchanger to the main expansion valve, where the outdoor heat exchanger includes a header to form a flowing space of the refrigerant and having an upper header and a lower header; a check valve disposed between the upper header and the lower header to guide the refrigerant to flow one way; and a bypass pipe connecting the lower header to the second inlet/outlet pipe and guiding a discharge of a liquid refrigerant located in the lower header, and a bypass pipe valve controlling an amount of the liquid refrigerant flowing through the bypass pipe.

What is claimed is: 
     
         1 . An air conditioner comprising:
 a compressor;   a flow switching part disposed at an outlet side of the compressor to switch a flow direction of a refrigerant according to whether a cooling operation or heating operation is performed;   an outdoor heat exchanger connected to the flow switching part and having a plurality of the refrigerant pipes to guide the refrigerant which heat-exchanges with outdoor air;   a main expansion valve connected to one side of the outdoor heat exchanger;   a first inlet/outlet pipe connecting the flow switching part to the outdoor heat exchanger; and   a second inlet/outlet pipe connecting the outdoor heat exchanger to the main expansion valve,   wherein the outdoor heat exchanger comprises:
 a header to form a flowing space of the refrigerant and including an upper header and a lower header; 
 a check valve disposed between the upper header and the lower header to guide the refrigerant to flow one way; 
 a bypass pipe connecting the lower header to the second inlet/outlet pipe and to guide a discharge of a liquid refrigerant located in the lower header; and 
 a bypass pipe valve that is installed on the bypass pipe and controls an amount of the liquid refrigerant flowing through the bypass pipe. 
   
     
     
         2 . The air conditioner according to  claim 1 , further comprising a detector disposed in the refrigerant flowing space of the header to detect the amount of the liquid refrigerant in the lower header. 
     
     
         3 . The air conditioner according to  claim 2 , wherein the detector comprises a liquid level sensor disposed in the refrigerant flowing space of the header to detect a level of the liquid refrigerant introduced into the lower header. 
     
     
         4 . The air conditioner according to  claim 3 , wherein the liquid level sensor comprises a first liquid level sensor disposed at a lower side of the lower header such that a plurality of liquid level sensors are disposed above the first liquid level sensor. 
     
     
         5 . The air conditioner according to  claim 2 , wherein the detector comprises a temperature sensor disposed in the refrigerant flowing space of the header to detect a temperature of the liquid refrigerant introduced into the lower header. 
     
     
         6 . The air conditioner according to  claim 5 , wherein the temperature sensor comprises a first temperature sensor disposed at a lower side of the lower header such that a second temperature sensor is disposed above the first temperature sensor. 
     
     
         7 . The air conditioner according to  claim 2 , wherein, when the amount of the liquid refrigerant measured by the detector is more than a set range, the bypass pipe valve is opened, and the liquid refrigerant stored in the outdoor heat exchanger is discharged from the outdoor heat exchanger, and
 when the amount of the liquid refrigerant measured by the detector is less than the set range, the bypass pipe valve is closed.   
     
     
         8 . The air conditioner according to  claim 1 , wherein the outdoor heat exchanger further comprises a first refrigerant pipe connected to the upper header; a connection pipe to guide the refrigerant flowing through the first refrigerant pipe to the lower header; and a refrigerant introduction pipe connecting the lower header to a second refrigerant pipe, and
 the refrigerant introduction pipe located higher than the connection pipe.   
     
     
         9 . The air conditioner according to  claim 8 , wherein the refrigerant introduction pipe comprises a lower introduction pipe disposed at a lower side of the lower header such that a plurality of upper introduction pipes is disposed above the lower introduction pipe, and
 a height of the lower introduction pipe is higher than a height of the connection pipe with respect to a bottom of the outdoor heat exchanger.   
     
     
         10 . The air conditioner according to  claim 1 , wherein the bypass pipe extends from a surface of the lower header. 
     
     
         11 . The air conditioner according to  claim 1 , wherein the bypass pipe valve comprises an electronic expansion valve of which a degree of opening is controllable. 
     
     
         12 . The air conditioner according to  claim 1 , further comprising:
 first and second distribution pipes branching from the second inlet/outlet pipe; and   a first and second distributors connected to the respective first and second distribution pipes to branch and introduce the refrigerant into the plurality of refrigerant pipes.   
     
     
         13 . The air conditioner according to  claim 12 , wherein the first distributor is connected to the first distribution pipe and in communication with the upper header; and
 the second distributor is connected to the second distribution pipe and in communication with the lower header.   
     
     
         14 . The air conditioner according to  claim 12 , further comprising:
 a first valve device disposed at the first distribution pipe; and   a second valve device disposed at the second distribution pipe.   
     
     
         15 . The air conditioner according to  claim 8 , further comprising a third valve device disposed at the connection pipe. 
     
     
         16 . A method of controlling an air conditioner, comprising:
 driving a cooling operation in an indoor unit to allow refrigerant discharged from a compressor to be introduced into the outdoor heat exchanger;   detecting an amount of a liquid refrigerant introduced into the outdoor heat exchanger by a detector; and   controlling a degree of opening of a valve disposed at a bypass pipe to discharge the liquid refrigerant from the outdoor heat exchanger, by a controller based on the detected amount of the liquid refrigerant.   
     
     
         17 . The method according to  claim 16 , wherein the controller controls by opening the bypass pipe valve when the amount of the liquid refrigerant detected by the detector is more than a set range, and closes the bypass pipe valve when the amount of the liquid refrigerant is less than the set range. 
     
     
         18 . The method according to  claim 16 , wherein the detector comprises a temperature sensor disposed at a refrigerant path of the outdoor heat exchanger to detect a temperature of the refrigerant, and
 the controller determines the amount of the liquid refrigerant introduced into the outdoor heat exchanger based on a temperature value of the refrigerant detected by the temperature sensor.   
     
     
         19 . The method according to  claim 18 , wherein the temperature sensor comprises:
 a first temperature sensor disposed at a lower side of the lower header; and   a second temperature sensor disposed above the first temperature sensor.   
     
     
         20 . The method according to  claim 16 , wherein the detector comprises a liquid level sensor disposed at a refrigerant path of the outdoor heat exchanger to detect a level of the liquid refrigerant, and
 the controller determines the amount of the liquid refrigerant introduced into the outdoor heat exchanger based on a level value of the liquid refrigerant detected by the liquid level sensor.