Internal Heat Exchanger for Air Conditioning System of Motor Vehicle and Such a Circuit

Abstract

The present invention relates to an internal heat exchanger of the coaxial tubular type for a motor vehicle air-conditioning circuit, comprising two, low-pressure and high-pressure, portions through which a coolant flows, and to a corresponding air-conditioning circuit incorporating same. This exchanger (E), of the coaxial tubular type, defines at least one radially internal passage ( 11 ), preferably for the low-pressure fluid inside an internal tube ( 10 ) and a radially external passage ( 21 ), preferably for the high-pressure fluid, formed between this internal tube and an external tube ( 20 ). According to the invention, spacer means ( 30 ) of a thermal conductivity lower than that of the internal and external tubes are movably mounted at least in translation between these two tubes and extend over just part of the length of the external passage, at least one region of this passage which is devoid of such means being intended to be connected to a tapping ( 40 ), such as a valve body or a sensor mounting nozzle, by a connecting orifice ( 23 ) formed in the external tube at right angle with this region.

1 . Internal heat exchanger of the coaxial tubular type for a motor vehicle air-conditioning circuit comprising two, low-pressure and high-pressure (LP and HP) portions through which a coolant flows, the exchanger defining at least one radially internal passage preferably for the low-pressure fluid inside an internal tube and a radially external passage, preferably for the high-pressure fluid formed between this internal tube and an external tube, characterized in that spacer means of a thermal conductivity lower than that of the internal and external tubes are movably mounted at least in translation between these two tubes and extend over just a part of the length of the external passage, at least one region of this passage which is devoid of such means being intended to be connected to a tapping, such as a valve body or a sensor mounting nozzle, by a connecting orifice formed in the external tube at right angle with this region. 
     
     
         2 . Exchanger according to  claim 1 , characterized in that said spacer means are mounted in contact with the internal and external tubes so as to act as radial distance pieces between these tubes to keep them concentric. 
     
     
         3 . Exchanger according to  claim 2 , of the type having at least one bent or curved section, characterized in that said spacer means are inserted at least at the site of this (these) section(s). 
     
     
         4 . Exchanger according to  claim 1 , characterized in that said spacer means extend axially continuously or discontinuously over said part of the external passage, ending set back from at least one connecting end of the external tube. 
     
     
         5 . Exchanger according to  claim 4 , characterized in that said spacer means are formed of a plurality of longitudinal ribs connected circumferentially between their respective bases by a substantially cylindrical wall capable of matching the internal tube so that the overall radial height of this wall and of each rib is substantially equal to that of the external passage. 
     
     
         6 . Exchanger according to  claim 4 , characterized in that said spacer means are formed of at least one spiral rib able to match the internal tube, extending in a helix around the latter with a pitch that is either constant or variable. 
     
     
         7 . Exchanger according to  claim 1 , characterized in that it incorporates said tapping at right angle with said region of the external passage devoid of said spacer means, which region is situated near one end of the external tube, this tapping being formed of a connecting nozzle of the exchanger which nozzle is intended to carry the fluid coming from or toward the external passage. 
     
     
         8 . Exchanger according to  claim 7 , characterized in that the internal tube at least one of its ends has a protruding portion which protrudes axially beyond the corresponding end of the external tube being secured to the latter end and which alone forms another connecting nozzle of the exchanger intended to carry the fluid from or toward the or each internal passage. 
     
     
         9 . Exchanger according to  claim 8 , characterized in that said end of the external tube is secured to the internal tube by a sinking of this end obtained, for example, by knurling, followed by circumferential attachment of this end to this internal tube performed by welding, brazing, magnetoforming or bonding. 
     
     
         10 . Exchanger according to  claim 7 , characterized in that at one of its ends at least, the external tube is secured to the internal tube by crimping with previous push-fitting of one end of a flexible hose for connecting to the air-conditioning circuit between the respective ends of these tubes, which hose is optionally mounted so that it butts axially against a ring flange of the internal tube. 
     
     
         11 . Exchanger according to  claim 7 , characterized in that it is devoid of any high-pressure/low-pressure female connector for connecting the internal passage(s) and external passage(s) to the air-conditioning circuit. 
     
     
         12 . Motor vehicle air-conditioning circuit, characterized in that it comprises an internal heat exchanger as defined in  claim 1  and which is preferably connected to this circuit without any high-pressure/low-pressure female connector.