Internal heat exchanger with calibrated coil-shaped fin tube

Abstract

An internal heat exchanger unit for use in refrigerant circuits of automotive air conditioning systems. The internal heat exchanger includes a casing within which is located an accumulator, spaced thereapart so as to define a gap between the two components. Located within the gap is a coil-shaped fin tube. The fins of the fin tube include bend end portions at spaced apart locations about the fins, and the bent end portions defining an outer dimension of the fins that substantially corresponds to the gap width.

1 . An internal heat exchanger unit for use in refrigerant circuits of air conditioning systems in automotive vehicles, comprising: 
 a casing having a casing side wall limited by top and bottom cover plates;    an accumulator located in the casing, the accumulator having an accumulator side wall spaced apart from the casing side wall and defining a gap therebetween having a gap width x, the accumulator configured to receive liquid refrigerant at low pressure;    a coil-shaped fin tube located in the gap between the casing and the accumulator and configured to receive refrigerant at high pressure, the coil-shaped fin tube including a tube and a plurality of fins located thereon, the fins including bend end portions at spaced apart locations about the fins, the bent end portions defining an outer dimension of the fins that substantially corresponds to the gap width x, the bent end portions further defining a bent length z.    
     
     
         2 . The internal heat exchanger of  claim 1  wherein the bent end portions of the fins are bent in an axial direction relative to the tube.  
     
     
         3 . The internal heat exchanger of  claim 1  wherein the bent end portions define bearing surfaces.  
     
     
         4 . The internal heat exchanger of  claim 3  wherein the bearing surfaces are bearing surfaces between the casing and the bent end portions and the accumulator and the bent end portions.  
     
     
         5 . The internal heat exchanger of  claim 3  wherein the coil-shaped fine tube has a plurality of coils and the bearing surfaces are bearing surfaces between the adjacent coils, the bearing surfaces defining surfaces configured to permit sliding of one coil relative to the adjacent coil.  
     
     
         6 . The internal heat exchanger of  claim 1  wherein the fins include at least two bent end portions.  
     
     
         7 . The internal heat exchanger of  claim 1  wherein the fins include four bent end portions.  
     
     
         8 . The internal heat exchanger of  claim 1  wherein the fins are arranged concentric on the tube.  
     
     
         9 . The internal heat exchanger of  claim 1  wherein the fins are generally annular in shape.  
     
     
         10 . The internal heat exchanger of  claim 1  wherein the fins have a height h from an exterior surface of the tube, the height h being about 5% of the gap width x.  
     
     
         11 . The internal heat exchanger of  claim 1  wherein the fins are dimensioned such that a distance between an exterior surface of the tube and an interior surface of the casing and/or an exterior surface of the accumulator is about 5% of the gap width x.  
     
     
         12 . The internal heat exchanger of  claim 1  wherein the bent length z is at least equal to half of a length L 1 , where L 1  is the distance between adjacent fin surfaces.  
     
     
         13 . The internal heat exchanger of  claim 1  wherein the fins are spaced apart on the tube by a distance t, whereby a ratio of the distance t to the fin height h is in the range of about 1 to 4.  
     
     
         14 . The internal heat exchanger of  claim 1  wherein the bent ends of the fins are generally T-shaped.  
     
     
         15 . The internal heat exchanger of  claim 1  wherein the bent ends of the fins are upset ends.  
     
     
         16 . The internal heat exchanger of  claim 1  wherein the side wall of the casing includes an insulating layer.  
     
     
         17 . The internal heat exchanger of  claim 1  wherein the side wall of the accumulator includes an insulating layer.  
     
     
         18 . The internal heat exchanger of  claim 1  wherein the top and bottom cover plates of casing are provided with connections for the refrigerant at low pressure and high pressure.  
     
     
         19 . The internal heat exchanger of  claim 1  wherein the fins are arranged on the tube so as to define passageway between the fins for refrigerant vapor at low pressure that is cross-countercurrently to the refrigerant at high pressure within the tubes.