Arrangement of a connecting piece

Abstract

Arrangement of a connecting piece (4) for the entry of a first phase and the exit of a second phase from the head (2, 3) of a heat exchanger (1), characterized in that the connecting piece (4) has the form of a block with at least two arms (41, 42) projecting from the block, which extend in line with the two opposite walls of the block, whereby the connecting piece (4) is connected to the head (2, 3) of the heat exchanger (1) via its wall located between the at least two projecting arms (41, 42) and its projecting arms (41, 42) are located on the head (2, 3) of the heat exchanger (1) along their entire length. wherein the connecting piece (4) has openings for introducing the first phase and openings for removing the second phase, wherein the connecting piece (4) and the head (2, 3) of the heat exchanger (1) are made of an aluminium alloy and the surfaces of the connecting piece (4) adjacent to the head (2, 3) of the heat exchanger (1) are attached to it by soldering.

Description

[0001] The present invention relates to the arrangement of a connecting piece for the inlet of the first phase and the outlet of the second phase of a heat exchanger, such as the evaporator or condenser of an air conditioning system or a gas cooler. The present invention relates in particular to a connecting piece for a so-called brazed heat exchanger, i.e., an exchanger made of an aluminum alloy and then brazed together. Such exchangers are used primarily in motor vehicles, especially as evaporators in the air conditioning system.

[0002] Heat exchangers typically comprise an assembly of tubes or plates for heat exchange between a first medium, such as a coolant, circulating in first channels of the assembly of tubes or plates, and a second medium, such as an airflow, flowing through second channels of the assembly of tubes or plates.

[0003] The first channels for the first medium, such as coolant, must therefore be supplied with the first medium. For this purpose, heat exchangers can have one or more openings for the medium, which are connected to a connecting device or fitting that provides the so-called socket part for connecting the so-called plug part of the first circuit for the medium. In a known manner, the socket part or interface on a metal component of the exchanger is designed in the form of a fitting that has the shape of a block with openings and is suitable for receiving a complementary plug part, such as a pipe, that is connected to the first circuit for the medium.

[0004] Such connecting pieces, also known as interfaces of the exchanger body or connecting devices, serve to introduce and remove a gaseous and sometimes liquid first medium to or from an exchanger and are manufactured in various ways.

[0005] Heat exchangers may have a connecting piece located below the upper manifold of the exchanger, parallel to the end plate. This connecting piece has openings that connect to the main body of the exchanger. A corresponding contact element is provided on one side of the exchanger head with a complementary, continuous shape and on the other side for connecting pipes. The pipe is inserted into the connecting piece and can then be soldered. This connecting piece is press-fitted to the main body of the exchanger from below, and the two parts are joined together after soldering at the contact surfaces between the connecting piece and the exchanger head.The connector is typically also equipped with a bushing (or a hollow sleeve) or with bushings that are press-fitted to the connector, with a connection again being made by soldering at the contact surfaces, whereby the connector assembly is now ready for the attachment of pipes. The medium is guided to and from the heat exchanger through a circular cross-section in the connector.

[0006] Nevertheless, with this type of press fit below the upper head, where the connector and the head form a connection angle of 90°, it has been found that the quality of the connection point may not be stable and depends on the quality of the press fit, so that sufficient contact between the joined parts cannot be maintained during the soldering process.

[0007] US Patent 8,276,401 B2 discloses a connecting piece for the inlet of a first phase and the outlet of a second phase from the head of an evaporator, wherein the connecting piece has openings for introducing a first phase and openings for removing a second phase, and wherein the connecting piece is attached to the head of the heat exchanger by soldering.

[0008] DE 697 10 232 T2 shows both an inlet connector and an outlet connector on a heat exchanger, each of which includes a snap-on bracket for connecting the connector to a head tube of the heat exchanger.

[0009] Another connecting device or fitting for the direct connection of pipes is known from document EP 2 910 888 B1. Here, the pipes are aligned with the axis of the heat exchanger head into which they are inserted. However, such a solution is not very robust and does not offer adequate strength or resistance required for the use of high-pressure media such as R744 (CO2).

[0010] US Patent 3,869,153 A shows an arrangement for connecting pipes with the flat connection surface of associated accessories, such as a pipe block or the head of a refrigerant compressor.

[0011] US Patent 6,154,960 A discloses a method for improving the quality of a solder joint, wherein a pipe is connected to a manifold block by soldering.

[0012] FR 2 807 153 A1 shows a method for mounting a connection block on a manifold of a heat exchanger, such as a condenser or a radiator.

[0013] DE 692 07 485 T2 discloses a heat exchanger suitable for use as a condenser or evaporator in the cooling system of a motor vehicle or as an air conditioning system for rooms or as an oil cooler.

[0014] Furthermore, it was found that for a connecting piece directly press-fitted into the axis above or into the upper main part of the exchanger, the quality of the connection point may not be stable and may depend on the number of parts joined. When soldering three or more components together, it is necessary to ensure the correct material definition, preparation, and especially the thickness of the individual materials being joined, as well as the necessary manufacturing accuracy for each component. This accuracy increases for the overall connection depending on the number of parts joined, so that limitations may exist due to the manufacturing process tolerance of the part entering the connection.

[0015] Another option is a socket that is pressed directly onto the connector, but this damages and weakens the fusible Al+Si layer on the socket, which impairs the quality of the soldering and increases the occurrence of porosity and leakage.

[0016] The existing solutions are often too bulky and sometimes require a lot of material. Furthermore, the fittings must achieve minimal pressure losses for the medium they carry, and openings in the fitting with a cylindrical bore and a circular transition to the heat exchanger head can lead to increased pressure losses.

[0017] The aim of the invention is to create optimal conditions for the connection of a connecting piece and the head of a heat exchanger body as well as a bushing on a connecting piece in order to ensure a tight and mechanically stable connection, with compact dimensions and low material consumption as well as good pressure resistance and minimal pressure losses when the first medium passes through the connecting piece according to the invention, thereby increasing the efficiency of the heat exchanger.

[0018] These objectives are achieved and the aforementioned disadvantages eliminated by an arrangement of a connecting piece for the entry of a first phase and the exit of a second phase from the head of an exchanger. The connecting piece has the form of a block with at least two arms projecting from the block, extending from the two opposite walls of the block. It is thus connected to the head of the exchanger via the wall located between the at least two projecting arms, and its projecting arms rest along their entire length on the head of the exchanger, holding the connecting piece in a position fixed to the head of the exchanger. The head of an exchanger is sometimes also referred to as a "boiler." The body of the connecting piece has openings for introducing the first phase and openings for removing the second phase.The connecting piece and the head of the heat exchanger are made of an aluminum alloy, and the surfaces of the connecting piece adjacent to the head of the heat exchanger are attached to it by soldering.

[0019] In this arrangement, only two surfaces of the connector and the heat exchanger head are joined or soldered, which, in terms of soldering, is the simplest solution for coordinating just two tolerance ranges—those of the two components. Holding the arms with the heat exchanger head before and during soldering contributes to the quality and precision of the connection between the connector and the heat exchanger head, ensuring a firm mechanical connection of the two parts and secure contact between the two soldered surfaces.

[0020] The heat exchanger can be an evaporator, where the first phase is liquid and the second phase is gaseous (the liquid phase may already contain small amounts of the gas phase at the inlet). However, the heat exchanger can also be, for example, a condenser, where the first phase is gaseous and the second phase is liquid (the gas phase may already contain small amounts of the liquid phase at the inlet).

[0021] The invention therefore relates in particular to an arrangement of a connecting piece for the inlet of a first, liquid phase and the outlet of a second, gaseous phase from the upper head of an evaporator or for the inlet of a first, gaseous phase and the outlet of a second, usually liquid, phase from the lower head of a cooler, generally a condenser, characterized in that the connecting piece has the form of a block with at least two arms projecting from the block, which extend upwards or downwards in extension of the two opposite walls of the block, whereby the connecting piece is connected via its wall arranged between the at least two projecting arms to the underside of the upper head of the evaporator or to the top of the lower head of the cooler and its projecting arms are located along their entire length on the upper head of the evaporator or on the lower head of the cooler. wherein the connecting piece has openings for introducing the first phase and openings for removing the second phase, wherein the connecting piece and the head of the evaporator or cooler are made of an aluminum alloy and the surfaces of the connecting piece adjacent to the head of the evaporator or cooler are attached to it via a joint formed by a continuous and uniform layer of non-porous material formed by soldering.

[0022] The heat exchanger can also be a standard gas cooler.

[0023] Although the connecting piece is more commonly attached to the upper head of the heat exchanger, an embodiment is also possible in which the connecting piece is attached to the lower head of the exchanger. As is obvious to those skilled in the art, in this case the construction is a mirror image, i.e., the arms extend downwards and the intermediate side of the connecting piece is attached to the top of the lower head of the exchanger.

[0024] The connector advantageously has two substantially square openings located in its wall attached to the head of the exchanger, while a circular opening in the body of the connector is connected to each square opening, in which a socket is fitted for connecting a conduit for introducing the first phase or for carrying away the second phase.

[0025] Typically, the socket is made of an Al3xxx series aluminum alloy and the connector of an Al6xxx series aluminum alloy (e.g., Al6061). For the soldering process, the socket is coated with a flux (Al4xxx series aluminum alloy with 10 to 12% Si) on its surface, while the surface of the connector is only coated with an activator to remove the oxide layer (potassium aluminum fluoride).

[0026] The circular openings of the connector advantageously always have a smaller-diameter bore in the first part of their length, which lies furthest inside the connector, and a larger-diameter bore in the outward direction of the subsequent section of their length. Each socket for attaching a conductor is secured by material deformation with a positive fit in the circular opening of the connector in its section of the smaller-diameter bore, while in its section of the larger-diameter bore it is joined to the connector by a connection formed from a continuous and uniform layer of non-porous material created by soldering. Such a design of the connector assembly ensures a particularly high-quality soldered connection between the connector itself and the socket.

[0027] The difference between the radius of the smaller diameter bore and that of the larger diameter bore is advantageously less than 0.2 mm, in particular less than 0.075 mm to 0.15 mm.

[0028] After the bushing is inserted, the capillary space between the outer surface of the bushing and the wall of the larger diameter bore, which is advantageously less than 0.1 mm, and in particular between 0.075 mm and 0.1 mm, is filled with flux. Such conditions have proven to be particularly suitable for the quality of the solder joint.

[0029] An advantageous ratio of the cross-sectional area of ​​the square opening to the inner cross-sectional area of ​​the bushing mounted in the circular opening lies between 1.35 and 1.75. Values ​​below 1.35 result in excessive pressure losses in the fitting, and the heat exchanger therefore has a lower efficiency. Values ​​above 1.75 offer no added benefit, as the pressure loss is not reduced; on the contrary, there may be an increased risk of mechanical damage.

[0030] In one embodiment, the projecting arms of the connecting piece are always divided into at least two teeth, which are bent substantially at right angles over the upper edge of the head while sitting on the head along their entire length. Advantageously, the material of the teeth of the arms is thinned at the point of the bend at a right angle to achieve tight contact along its entire length, the thinning being advantageously achieved by removing material on the side facing the head, which advantageously has the cross-sectional shape of an isosceles trapezoid that widens towards the head when the tooth is not bent.

[0031] Another advantage of dividing the arms into at least two teeth is that a safety element or projection, which is part of the head of the diver and ensures a precise position on the head of the diver, can fit into the gap between two specific teeth.

[0032] In the event that the upper head of the heat exchanger is formed by an assembly comprising at least one distributor plate, a cover plate and an intermediate plate arranged between the distributor plate and the cover plate, the connecting piece is advantageously connected to the underside of the distributor plate via its wall located between the at least two projecting arms, and its projecting arms are attached along their entire length to the assembly consisting of the distributor plate, the intermediate plate and the cover plate.

[0033] Another object of the present invention is a heat exchanger, particularly for motor vehicles, with two heads facing each other and joined together by a group of heat exchange tubes for the passage of a medium between these heads, and which has a connecting piece arrangement as defined above. This can be an evaporator of an air conditioning circuit, comprising an upper evaporator head with an upper tube plate and an inlet for the liquid phase and an outlet for the gas phase, a lower evaporator head with a lower tube plate, a bundle of two rows of flat heat exchange tubes arranged parallel and spaced apart from each other and connecting the two heads, and heat exchange elements arranged between the flat heat exchange tubes.

[0034] The invention is further explained with reference to specific exemplary embodiments illustrated in the drawings. These show: Fig. 1a a view of a section of a composite exchanger with attached connecting piece arrangement according to the invention, Fig. 1b a view of the removed connecting piece assembly and the exchanger head, Fig. 2 the connector and the socket, which are separate from each other, Fig. 3a a cross-sectional view of the connecting piece arrangement through a vertical plane passing through the axis of the bushing, Fig. 3b an excerpt from Fig. 3a, Fig. 4a a detailed view of the connector itself, Fig. 4b a view of the connecting piece made of Fig. 4a with attached distribution board and partially cut off, Fig. 4c a side view of the connector with the circular opening, Fig. 4d a top view of the connector, Fig. 5 a section of the tooth profile of the connecting piece arm in an advantageous embodiment, Fig. 6a Photographs of a section of a finished solder joint between a socket and a connector from the prior art, obtained using a metallographic microscope, Fig. 6b Analog photographs of a section of a finished soldered joint between a socket and a connector according to the invention having a bore with twice the diameter, Fig. 7a an overall view of an evaporator with the connecting piece arrangement according to the invention and Fig. 7b an overall view of another exchanger with the connecting piece arrangement according to the invention.

[0035] Throughout this document, terms relating to the orientation of the exchanger, such as top, bottom, vertical, horizontal, etc., refer to its orientation as illustrated in the figures, see e.g. Fig. 7a and Fig. 7b. The heat exchanger 1 is installed in precisely one such orientation in many applications, and the directions given thus correspond to the position of such an exchanger during its use. In the illustrated embodiment, the height of the exchanger is its vertical direction, and the length is its greatest dimension (the left-to-right direction). Fig. 7a and Fig. 7b) and the thickness is its third and smallest dimension.

[0036] A first medium moves through the heat exchanger 1, entering through the inlet for the first phase and exiting through the outlet for the second phase. If the heat exchanger 1 is an evaporator, the first phase is liquid and the second phase is gaseous (or a vapor phase). The liquid phase may already contain small amounts of the gas phase at the inlet. If the heat exchanger 1 is a condenser, the first phase is gaseous and the second phase is liquid (the gas phase may already contain small amounts of the liquid phase at the inlet).

[0037] If exchanger 1 is a conventional gas cooler, the first and second phases can be gaseous.

[0038] The heat exchanger 1 consists of two heads 2, 3, which are opposite each other and are connected to each other by two rows of heat exchange tubes 6, which are connected to each other by fins - the heat exchange elements 7 - which serve to exchange heat with another medium, air, which flows transversely through the heat exchanger in the direction of its thickness.

[0039] The Fig. 1a and Fig. Figure 1b shows an embodiment of a heat exchanger 1, the upper head 2 of which is formed by an assembly consisting of a distributor plate 21, an intermediate plate 22, and a cover plate 23, which are installed in a U-shaped profile 20. The lower head 3 is formed analogously, essentially as a mirror image, by an assembly consisting of a distributor plate 31, an intermediate plate 32, and a cover plate 33, which are installed in an inverted U-shaped profile 30.

[0040] The arrangement of the connecting piece according to the exemplary embodiment shown is also realized in such a way that the connecting piece 4 itself is connected to the underside of the distributor panel 21 via its wall, which is located between the aforementioned at least two protruding arms 41, 42, while its protruding arms 41, 42 are attached along their entire length to the assembly consisting of the distributor panel 21, the intermediate plate 22 and the cover plate 23.

[0041] The connecting piece 4 itself has sockets 5 for connecting lines to introduce the first phase and to remove the second phase.

[0042] Fig. Figure 1b shows the same two components (assembly consisting of connector 4 and head 2), depicted separately. On the left are (not to scale) lines connected to the first medium via a circuit. Among other things, the division of arms 41 and 42 into two teeth is clearly visible. These teeth are shown here in their curved form, in their position on the final product. These teeth are straight when connector 4 is mounted on the head 2 of the heat exchanger 1, as, for example, in Fig. 2, Fig. 4a, Fig. 4b, Fig. 4c and Fig. 5, and only after the connecting piece 4 has been mounted on the head 2 of the exchanger 1 are these teeth bent over the edge of the head 2 so that they sit on the head 2 along their entire length.

[0043] A projection 99, which is part of the head 2 of the diver 1 and ensures a precise position on the head 2 of the diver 1, is inserted into the space between these teeth. These two elements (the space between the teeth of arms 41, 42 and the projection 99) represent elements that restrict incorrect assembly, so-called Poka-Yoke elements (a term derived from the Japanese name for such elements), i.e., generally elements that, when correctly assembled, fit together with complementary elements of other components, e.g., flush with them, so that it is practically impossible to assemble the individual components incorrectly.

[0044] Fig. Figure 2 shows the connecting piece 4 and both bushings 5 ​​separately in an exemplary embodiment. This figure also shows the smaller-diameter bore 451 in the first part of the length of the circular opening 45, which is located furthest inside the connecting piece 4, and the larger-diameter bore 452 in the second part of the length of the circular opening 45, which is located outwards from the next section of the length of the circular opening 45. The first, smaller inner diameter serves to secure the bushing 5, and the second, larger diameter serves to create a mechanically strong and tight connection that is formed during the soldering process.

[0045] The bushing 5 has two main parts: a cylindrical part that is fitted or pressed into the round opening 45 of the connector 4 (thus serving to center the bushing 5 in the opening 45 of the connector 4), and a second part that, when assembled, projects beyond the body of the connector 4 and serves to secure a line for supplying or discharging the first medium. This second part is formed by two successive conical sections. The first, inner conical section ensures a proper fit and centering of the supply / discharge line, which has the same conical shape at its end to define the tolerance. The second conical section provides a space filled with a solder ring, forming a mechanically tight and secure connection with the pipe. This topic is further explained in document EP 2 910 888 B1.It has proven particularly advantageous if the first, centering conical section extends over a length of h1 = 3 to 6 mm and forms an angle of 2 to 8 degrees with the longitudinal axis of the bushing 5. A length of just 3 mm for the centering conical section, with a taper of up to 8 degrees, fully ensures the desired coaxiality, fit, and stability of the tube in the bushing. Depending on the mechanical calculations for the given pressure application, the second, outer conical section could have a height of at least 3 mm, and the apex angle of this second conical section could be at least 4 degrees greater than the apex angle of the first conical section.This type of conical centering of a conductor and a socket 5 is achieved with a simple final assembly and ensures a flawless quality of the solder joint with optimal access of the activating agent that is released from the solder ring and eliminates any porosity.

[0046] The Fig. 3a and Fig. Figure 3b shows the connecting piece arrangement with attached bushing 5 in a cross-section through the vertical plane passing through the axis of the circular opening 45 (which coincides with the axis of the bushing 5). Ideally, a capillary space with dimensions of 0.075 mm to 0.1 mm must be provided between the outer diameter of the bushing 5 and the second bore 452 in the connecting piece 4 (see in particular Figure 3b). Fig. 3b) be ensured, wherein this space ensures the pulling or extraction of the outer molten Al+Si layer from the socket 5 into the defined space during the soldering process. This space prevents damage to the surface of the socket 5 and the Al+Si layer and ensures a high-quality, mechanically strong and tight connection without porosity ( Fig. 6b).

[0047] Fig. Figure 4a shows the connecting piece 4 itself and reveals the openings 44 for attachment to the head of the exchanger 1, the circular openings 45 for mounting the bushings 5, and the projecting arms 41, 42, which are always divided into two teeth. After the head of the exchanger is assembled with the connecting piece 4, the ends of these arms are bent at a right angle over the upper edge of the head 2, so that these teeth are in contact with the head 2 along their entire length. This condition with the bent teeth is shown in Fig. 1a and Fig. 1b can be seen.

[0048] It is important to form the inner passage of the connector, which is essentially bounded by the square opening 44 and the associated round opening 45. These two openings (bores) form a 90-degree angle with each other within the connector. Furthermore, the cross-sections of these two mutually perpendicular cylindrical and square shapes are in a ratio of 1.35 to 1.75, with the cross-section of the square opening being larger than the cross-section of the round opening.

[0049] Fig. Figure 4b shows a section of the assembly consisting of the connecting piece 4 with the distribution board 21, partially in sectional view. This figure shows how the openings 44 and 45 communicate with each other, and also how the openings 44 are flush with the corresponding openings of the distribution board 21.

[0050] For better understanding, the increase in cross-section at the point where the first medium passes from the supply pipe through the connector to the heat exchanger head (i.e., the square opening 44 relative to the inner cross-section of the bushing) is advantageously such that the square cross-section surrounds the round one, ensuring a constant thickness of the connector wall whenever minimal material stress is required, whether in terms of mechanical strength, pressure resistance, or corrosion resistance. Furthermore, this allows for larger manufacturing tolerances for the connector 4 and the heat exchanger head 2, 3 with regard to positional accuracy and adherence to the cross-sectional dimensions.

[0051] Fig. Figure 4d shows a top view of the connecting piece 4, i.e. from the side with the square openings 44. Fig. Figure 4c shows a view of the front of the connecting piece 4 with round openings 45. The arms 41, 42, or their end teeth, can be seen "from the side." The section of the profile of a tooth of an arm of the connecting piece is shown in Fig. Figure 5 is shown in cross-section. Advantageously, the length b corresponds to the substantially planar recess of its depth a. Thus, the depth a and the length b can advantageously have, for example, a dimension of approximately 0.5 to 0.7 mm. The teeth of the arms 41, 42 are advantageously designed essentially the same as the teeth 201 of the U-shaped profile 20 of the head 2 of the exchanger.

[0052] Fig. Figure 6a shows photographs taken with a metallographic microscope of a section of the finished solder joint between the socket and the connector, obtained on a state-of-the-art heat exchanger. A relatively high porosity of such a joint can be seen along its entire length.

[0053] Fig. Figure 6b, however, shows photographs of a section of a finished soldered joint between a socket 5 and a connector 4 according to this invention. In this photograph taken with a metallographic microscope, the joint between the socket 5 and the connector 4 in the region of the smaller diameter bore 451 is comparable to the joint according to the prior art, but in the remaining section of this joint in the region of the larger diameter bore 452 according to the invention, a flux-filled gap is visible, and the joint in this region exhibits a significantly lower porosity than in the prior art.

[0054] The exchanger 1 in the in Fig. The overall view shown in Figure 7a is an evaporator of an air conditioning system, particularly for a motor vehicle. In this drawing, the heat exchange elements 7 are shown only on the left side to better illustrate the heat exchange tubes 6 leading between the two heads 2, 3 of the exchanger 1. From the perspective of the passage of the first medium through the exchanger, Fig. 7a A heat exchanger with six sections (see the division of the bulges of the cover plate 23 of the upper head 2). These sections are always formed by several adjacent heat exchange tubes 6 of a row, in which the coolant flows in the same direction from one head 2 or 3 to the other head 3 or 2, respectively. The movement of the coolant through such a heat exchanger is as follows: from the first head (the upper head 2 in the embodiment shown), it flows via the first section on the inlet side (i.e., on the side with the first row of heat exchange tubes 6) to the other head (the lower head 3 in the embodiment shown), via the second section to the first head, via the third section to the second head, in which the coolant flows via the heat exchanger (so-called bypass section) to the side with the second row of heat exchange tubes 6 (i.e.,on the outlet side) and taken back via the fourth section to the first head, via the fifth section to the second head and via the sixth section to the first head and to the outlet.

[0055] Fig. Figure 7b shows another exemplary embodiment of an exchanger 1 according to the invention, namely a gas cooler, a so-called internal gas cooler. In this case, the exchanger has only two sections: cooled gas moves through all heat exchange tubes 6 of the series of heat exchange tubes 6 on the inlet side from the upper head 2 to the lower head 3, in which the cooled gas moves as a whole over the heat exchanger (with the entire lower head 3 forming a bypass section), and then through all heat exchange tubes 6 of the second series of heat exchange tubes 6 on the outlet side from the lower head 3 to the upper head 2 and to the outlet of the first medium from the exchanger 1.

Claims

[1] Arrangement of a connecting piece (4) for the entry of a first phase and the exit of a second phase from the head (2, 3) of a heat exchanger (1), characterized by , that the connecting piece (4) has the form of a block with at least two arms (41, 42) projecting from the block, extending in line with the two opposite walls of the block, whereby the connecting piece (4) is connected to the head (2, 3) of the heat exchanger (1) via its wall located between the at least two projecting arms (41, 42) and its projecting arms (41, 42) are located on the head (2, 3) of the heat exchanger (1) along their entire length, wherein the connecting piece (4) has openings for introducing the first phase and openings for removing the second phase, wherein the connecting piece (4) and the head (2, 3) of the heat exchanger (1) are made of an aluminium alloy and the surfaces of the connecting piece (4) adjacent to the head (2, 3) of the heat exchanger (1) are attached to it by soldering. [2] Arrangement of a connecting piece (4) according to claim 1, wherein the connecting piece (4) has two square openings (44) located in a wall attached to the head (2) of the heat exchanger (1), while a circular opening (45) in the body of the connecting piece (4) is connected to each square opening (44) in which a socket (5) for connecting a line for introducing the first phase or for removing the second phase is attached. [3] Arrangement of a connector (4) according to claim 2, wherein the circular openings (45) of the connector (4) always have a bore (451) with a smaller diameter in the first part of their length, which is furthest inside the connector (4), and a bore (452) with a larger diameter in the outward direction of the following section of their length, wherein each bushing (5) for attaching a conduit is secured by material deformation with a positive fit in the circular opening (45) of the connector (4), in its section of the bore (451) with a smaller diameter, wherein in its section of the bore (452) with a larger diameter it is joined to the connector (4) by a connection formed from a continuous and uniform layer of non-porous material formed by soldering. [4] Arrangement of a connecting piece (4) according to claim 3, wherein the difference between the radius of the bore (451) with smaller diameter and that of the bore (452) with larger diameter is less than 0.2 mm, advantageously between 0.075 mm and 0.15 mm. [5] Arrangement of a connecting piece (4) according to one of claims 2 to 4, wherein the ratio of the cross-section of the square opening (44) to the inner cross-section of the bushing (5) fixed in the circular opening (45) is between 1.35 and 1.

75. [6] Arrangement of a connecting piece (4) according to any one of claims 1 to 5, wherein the protruding arms (41, 42) of the connecting piece (4) are always divided into at least two teeth which are bent at a right angle over the edge of the head (2), sitting on the head (2) along their entire length. [7] Arrangement of a connecting piece (4) according to claim 6, wherein the material of the teeth of the arms (41, 42) is thinned at the point of bending the tooth at a right angle, so that close contact is achieved along its entire length, wherein the thinning is advantageously carried out by removing material on the side facing the head (2), which in the unbent state of the tooth advantageously has in cross-section the shape of an isosceles trapezoid that is flared towards the head (2). [8] Arrangement of a connecting piece (4) according to one of the preceding claims, wherein the upper head (2) of the heat exchanger (1) is formed by an assembly comprising at least one distributor plate (21), a cover plate (23) and an intermediate plate (22) arranged between the distributor plate (21) and the cover plate (23), wherein this connecting piece (4) is connected to the underside of the distributor plate (21) via its wall located between the at least two projecting arms (41, 42) and its projecting arms (41, 42) are attached along their entire length to the assembly consisting of the distributor plate (21), the intermediate plate (22) and the cover plate (23). [9] Heat exchanger (1), in particular for motor vehicles, with two heads (2, 3) which are opposite each other and are connected via a group of heat exchange tubes for the passage of a medium between the heads, characterized bythat it has an arrangement of a connecting piece (4) according to one of the preceding claims. [10] Evaporator of an air conditioning circuit, in particular for a motor vehicle, comprising an upper head (2) with an upper tube plate and an inlet for a liquid phase and an outlet for a gas phase, a lower head (3) with a lower tube plate, a bundle of two rows of flat heat exchange tubes (6) arranged parallel and spaced apart from each other and connecting the two heads (2, 3), and heat exchange elements (7) located between the flat heat exchange tubes (6), characterized by , that it has an arrangement of a connecting piece (4) for the entry of a liquid phase and the exit of a gas phase according to any one of the preceding claims 1 to 8.

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