CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 to French Patent Application No. 2000143, filed Jan. 9, 2020, which is incorporated by reference herein in its entirety.

FIELD

The present disclosure is directed to a method for creating a sealed connection of a connector to a coaxial tubular-type heat exchanger, as well as a fluidic connection device, in particular for an air-conditioning circuit of a vehicle.

BACKGROUND

In certain air-conditioning circuit for automotive vehicles, in particular those using carbon dioxide or R134a as refrigerating fluid, it is necessary to achieve a heat exchange or transfer between the fluid of the high-pressure portion of the circuit that is sought to cool and the same fluid coming from the low-pressure portion of this circuit which serves as a cold source and which is heated in exchange, to improve the efficiency of the circuit. To this end, a so-called “internal” heat exchanger is used, due to any exchange with the outside air of the vehicle, nor with the air of the cabin not being sought.

Generally, a heat exchanger is metallic and is connected to the corresponding pipes of the air-conditioning circuit which comprise, in particular, hoses, via connectors mounted to each of the ends of the exchanger which can be, for example, of the plate type, being constituted of a stack of flat tubes and achieving the heat exchange, both by convection with the outside air to the exchanger, and by conduction, or multi-tube type which in its simplest version, is of the counter-current coaxial tubular type, thus achieving the heat exchange without the abovementioned convection.

In the latter case, this coaxial exchanger defines generally at least one radially internal channel, delimited by a sleeve and intended to convey the fluid coming from the high-pressure portion of the circuit, and at least one radially external channel comprised between the sleeve and the casing of the exchanger and intended to convey the fluid coming from the low-pressure portion of the circuit. The sleeve and the casing are formed of one single part and connected together by longitudinal fins distributed on the circumference of the exchanger.

It is known to use two female connectors for the end concerned of such a coaxial exchanger, that is welded or brazed axially, both separated on the sleeve and on the sleeve via three welding or brazing lines, such that these connectors define respectively passage conduits for the fluid communicating in a sealed manner with these internal and external channels. For example, document WO-A1-2007/1013439 can be mentioned for the description of these connectors.

A major disadvantage of these coaxial internal exchangers equipped with female connectors resides in the mutual proximity of the welding or brazing lines generated which, in particular for successive brazing, generate refusion risks of the prior brazing, and also in the necessity of carrying out this welding or brazing in a blind manner, with risks of non-sealing to the junction and/or penetration of the brazing in the corresponding internal or external channel, which could, due to this, lead to load losses, a pollution even a blocking of these channels.

It is also known to use one single connector at the connecting end of a coaxial exchanger, as for example described in document EP-A1-1 762 806 where the connector is assembled to the external casing and to the internal sleeve by brazing via an intermediate connector, and in document EP-A1-1 128 120 (FIG. 10 et seq.) where the connector is brazed directly on the casing and on the sleeve of the exchanger via two brazing seams.

A major disadvantage of the coaxial internal exchangers presented in these two latter documents is that their assembly to a connector requires at least two brazing operations to be carried out at the same time and of which at least one, relative to the junction to be performed between the connector and the internal sleeve, is necessarily “in a blind manner” or under difficult conditions due to its location inside the connector. This results in significant risks of non-compliance with connector and therefore loss of fluid transferred. In addition, this brazing involves a production cost and a relatively high rejection rate for the connection obtained.

The Applicant proposed a solution in document EP-A1-2 199 721. This solution consists of assembling the connector to the casing by welding, and to the sleeve by at least one annular sealing lining which is mounted on an axial extension of the sleeve with respect to the casing. The axial distance between the lining and the welding line is sufficiently important, such that this lining is not altered by the welding. The exchanger being formed of one single part, the sleeve and the casing are inseparable and are therefore mounted simultaneously in the connector.

Although this solution is effective, it is not fully satisfactory, as the axial extension of the sleeve leads to an important bulk of the exchanger and of the connector.

The disclosed subject matter provides an alternative to this solution.

SUMMARY

The present disclosure provides a method of sealed connection of a connector to a coaxial tubular-type heat exchanger, in particular for a motor vehicle air-conditioning circuit,

this exchanger comprising two coaxial tubes, respectively internal and external, the external tube defining around the internal tube, a first annular channel for the circulation of a first fluid, and the internal tube defining a second internal channel for the circulation of a second fluid, the tubes being independent from one another and one of the tubes comprising projections in abutment on the other of the tubes to keep the tubes at a distance from one another, the connector comprising two passage cavities of the fluids communicating respectively with the channels of the exchanger,

characterized in that the process comprises the following successive steps:

a) a free end of the external tube is mounted in or on the connector,

b) the external tube is directly secured with the connector,

c) the internal tube is inserted in the external tube until a free end of the internal tube is mounted in or on the connector, this mounting ensuring a sealing between the internal tube and the connector, and

d) the internal and external tubes are directly secured against one another to avoid relative displacements.

Contrary to the disclosure of document EP-A1-2 199 721, the internal and external tubes of the exchanger are independent. They are thus mounted after one another in or on the connector. In particular, the external tube is mounted in step a) and secured to the connector in step b). This securing can be achieved by welding or brazing if the external tube and the connector are metallic. In a variant, in the case where the external tube and the connector would be made of other materials, their securing could be ensured by gluing, electron beam welding, etc. During this securing step b), the internal tube is not yet inserted in the external tube and therefore does not risk being altered by the securing operation, and for example, by the heating induced by a securing by welding. Then, in step c), the internal tube is inserted in the external tube, until the internal tube engages in a sealing manner with the connector. This is generally a mounting in a blind manner There is, strictly speaking, no securing of the internal tube directly to the connector. They are simply engaged in one another or on top of one another. The internal tube is indirectly secured with respect to the connector, by way of the external tube. This securing of the tubes is achieved in step d) and makes it possible to prevent any relative movement between the tubes in operation.

The method according to the present disclosure can comprise one or more of the following steps or features, taken individually from one another or in combination with one another:step d) is carried out by plastic deformation of at least one of the tube, and in particular by crimping the external tube on the internal tube, or by simultaneous bending of the internal and external tubes;the method comprises, between steps b) and c), a step of mounting at least one annular seal around the free end of the internal tube;during steps a) and c), the tubes are engaged by male-female interlocking respectively in two housings of the connector;during steps a) and c), the tubes are guided at the inlet of the housing by engagement of their free ends with the chamfers of the connector;before step c), the free end of the internal tube is plastically deformed or comprises a plastically deformed member, to achieve at least one annular recess at its external periphery, and preferably two annular recesses adjacent to its external periphery;before step c), the free end of the internal tube is plastically deformed or comprises a plastically deformed member, to modify its external diameter, at at least one end;the internal and external tubes are made of metallic material;the internal and external tubes are made of different materials;the internal tube is metallic and the external tube is made of plastic or composite material;the securing of the external tube to the connector is achieved by welding, brazing or gluing;the connector is metallic.

The present disclosure also concerns a fluidic connection device comprising a connector and a coaxial tubular-type heat exchanger, in particular for a motor vehicle air-conditioning circuit,

the connector forming two cavities for the passage of fluids communicating respectively with channels of the exchanger,

the exchanger comprising two coaxial tubes, respectively internal and external, the external tube defining around the internal tube, a first annular channel for the circulation of a first fluid, and the internal tube defining a second internal channel for the circulation of a second fluid, the tubes being independent and one of the tubes comprising projections in abutment on the other of the tubes to keep the tubes at a distance from one another,

characterized in that it is obtained by a method such as described above and in that:

the external tube comprises a free end which is engaged in or on the connector, this external tube being directly secured to the connector, and

the internal tube comprises a free end which is mounted in or on the connector, this mounting ensuring a sealing between the internal tube and the connector,

the internal and external tubes being directly secured against one another to avoid relative displacements.

Advantageously, the securing of the internal and external tubes is obtained thanks to a crimping of the external tube on the internal tube, to the simultaneous bending of the internal and external tubes, or to the welding of the ends of the internal and external tubes opposite the connector.

