External device and air conditioner having freezing function

Abstract

An air conditioner having a freezing function includes an external device, an expansion valve, a condenser, a compressor, and an evaporator. The compressor, the condenser, the expansion valve, the external device, and the evaporator are sequentially connected to form a loop. The external device includes a capillary tube and a cut-off valve. The capillary tube is spirally disposed. The cut-off valve is connected in parallel to the capillary tube. A tube coupling is disposed at each of two ends of the capillary tube. The tube couplings are separately fixedly connected to a conduit extending from the expansion valve and a conduit extending from the evaporator. A spiral capillary tube is connected between an expansion valve and an evaporator in an air conditioner, so that the pressure of a liquid refrigerant is reduced when entering the capillary tube, thereby lowering the lowest refrigeration temperature to implement quick cooling.

We claim: 
     
         1 . An external device, comprising
 a capillary tube and   a cut-off valve, wherein the capillary tube is spirally disposed, the cut-off valve is connected in parallel to the capillary tube, and a tube coupling is disposed at each of two ends of the capillary tube.   
     
     
         2 . The external device according to  claim 1 , wherein the tube coupling is a copper tube coupling. 
     
     
         3 . The external device according to  claim 1 , wherein the capillary tube comprises an inlet section, an outlet section, and a middle section, and wherein inner tube diameters of the inlet section and the outlet section are greater than an inner tube diameter of the middle section, and inner tube walls between the inlet section and the middle section and between the middle section and the outlet section have smooth transition. 
     
     
         4 . The external device according to  claim 3 , wherein the inner tube diameters of the inlet section and the outlet section are in a range of 5 mm to 7 mm, and the inner tube diameter of the middle section is in a range of 1 mm to 3 mm. 
     
     
         5 . The external device according to  claim 3 , wherein a total length of the capillary tube is in a range of 250 mm to 600 mm. 
     
     
         6 . The external device according to  claim 3 , wherein the inlet section and the outlet section are fixedly provided with the tube couplings, and the periphery of the middle section is sleeved with a heat insulating cover. 
     
     
         7 . The external device according to  claim 1 , wherein the cut-off valve comprises a solenoid valve. 
     
     
         8 . An air conditioner having a freezing function, comprising
 an external device comprising a capillary tube and a cut-off valve,   an expansion valve,   a condenser,   a compressor, and   an evaporator, wherein the compressor, the condenser, the expansion valve, the external device, and the evaporator are sequentially connected to form a loop.   
     
     
         9 . The air conditioner according to  claim 8 , wherein tube couplings are separately fixedly connected to a conduit extending from the expansion valve and a conduit extending from the evaporator. 
     
     
         10 . The air conditioner according to  claim 8 , wherein the capillary tube is spirally disposed, the cut-off valve is connected in parallel to the capillary tube, and a tube coupling is disposed at each of two ends of the capillary tube. 
     
     
         11 . The air conditioner according to  claim 8 , wherein the tube coupling is a copper tube coupling. 
     
     
         12 . The air conditioner according to  claim 8 , wherein the capillary tube comprises an inlet section, an outlet section, and a middle section, and wherein inner tube diameters of the inlet section and the outlet section are greater than an inner tube diameter of the middle section, and inner tube walls between the inlet section and the middle section and between the middle section and the outlet section have smooth transition. 
     
     
         13 . The air conditioner according to  claim 8 , wherein the inner tube diameters of the inlet section and the outlet section are in a range of 5 mm to 7 mm, and the inner tube diameter of the middle section is in a range of 1 mm to 3 mm. 
     
     
         14 . The air conditioner according to  claim 8 , wherein a total length of the capillary tube is in a range of 250 mm to 600 mm. 
     
     
         15 . The air conditioner according to  claim 8 , wherein the inlet section and the outlet section are fixedly provided with the tube couplings, and the periphery of the middle section is sleeved with a heat insulating cover. 
     
     
         16 . The air conditioner according to  claim 8 , wherein the cut-off valve comprises a solenoid valve.