Air conditioner

Abstract

In a case where a concentration of refrigeration oil detected by the concentration sensor is less than a first threshold value, the control device operates the heater such that a part of a refrigerant in a liquid state in the compressor is vaporized, and in a case where the concentration of the refrigeration oil detected by the concentration sensor exceeds a second threshold value greater than the first threshold value and a temperature of the refrigeration oil detected by the temperature sensor is less than a specified temperature, the control device operates the heater such that the refrigerant in the liquid state in the compressor is vaporized and the temperature of the refrigeration oil in the compressor is increased.

1 . An air conditioner comprising:
 a compressor;   a first heat exchanger;   a second heat exchanger;   a decompression device;   a circulation path through which a refrigerant circulates through the compressor, the first heat exchanger, the decompression device, and the second heat exchanger in this order;   a temperature sensor to detect a temperature of refrigeration oil in the compressor;   a concentration sensor to detect a concentration of the refrigeration oil in a mixture of the refrigerant in a liquid state and the refrigeration oil in the compressor;   a heater to heat the refrigeration oil in the compressor; and   a control device,   wherein   in a case where the concentration of the refrigeration oil detected by the concentration sensor is less than a first threshold value, the control device operates the heater such that a part of the refrigerant in the liquid state in the compressor is vaporized, and   in a case where the concentration of the refrigeration oil detected by the concentration sensor exceeds a second threshold value greater than the first threshold value and the temperature of the refrigeration oil detected by the temperature sensor is less than a specified temperature, the control device operates the heater such that the refrigerant in the liquid state in the compressor is vaporized and the temperature of the refrigeration oil in the compressor is increased.   
     
     
         2 . The air conditioner according to  claim 1 ,
 wherein in a case where the concentration of the refrigeration oil detected by the concentration sensor is less than the first threshold value, the control device ends heating of the refrigeration oil via the heater when the concentration of the refrigeration oil in the compressor exceeds the first threshold value.   
     
     
         3 . The air conditioner according to  claim 1 ,
 wherein the specified temperature is a temperature corresponding to a pour point of the refrigeration oil.   
     
     
         4 . The air conditioner according to  claim 3 ,
 wherein the second threshold value is a value designed assuming that an overcurrent flows in a motor of the compressor when the temperature of the refrigeration oil in the compressor is a temperature corresponding to the pour point and the concentration of the refrigeration oil in the compressor is the second threshold value.   
     
     
         5 . The air conditioner according to  claim 1 , further comprising:
 a memory to store the first threshold value,   wherein   the first threshold value is a value corresponding to a first temperature of the refrigeration oil, and   the memory further stores a third threshold value corresponding to a second temperature of the refrigeration oil.   
     
     
         6 . The air conditioner according to  claim 1 ,
 wherein the control device activates the compressor after adjusting the concentration or the temperature of the refrigeration oil in the compressor by operating the heater.   
     
     
         7 . The air conditioner according to  claim 1 ,
 wherein the control device operates the heater regardless of the concentration of the refrigeration oil in the compressor in a case where the refrigerant and the refrigeration oil in the compressor are separated and the temperature of the refrigeration oil detected by the temperature sensor is less than the specified temperature.   
     
     
         8 . The air conditioner according to  claim 7 ,
 wherein the control device stops the operation of the heater in a case where the temperature of the refrigeration oil in the compressor exceeds the specified temperature.   
     
     
         9 . The air conditioner according to  claim 1 ,
 wherein the control device operates the heater in a case where the refrigerant and the refrigeration oil in the compressor are separated, the temperature of the refrigeration oil detected by the temperature sensor exceeds the specified temperature, and the concentration of the refrigeration oil detected by the concentration sensor is less than the first threshold value.   
     
     
         10 . The air conditioner according to  claim 9 ,
 wherein the control device stops the operation of the heater in a case where the refrigerant in the liquid state in the compressor is vaporized.   
     
     
         11 . The air conditioner according to  claim 1 ,
 wherein the temperature sensor and the concentration sensor are provided in a vicinity of a shaft of the compressor.   
     
     
         12 . The air conditioner according to  claim 1 ,
 wherein the temperature sensor and the concentration sensor are provided at an end portion of a shaft of the compressor.