This invention relates to the arrangement of a connector for the inlet of first phase and the outlet of second phase of a heat exchanger, such as the evaporator or condenser of an air conditioning circuit, or a gas cooler. In particular, this invention relates to a connector for a so-called brazed heat exchanger, i.e., an exchanger manufactured from aluminium alloy and then brazed together. Such exchangers find use especially in motor vehicles, especially as evaporators of the air conditioning circuit. Prior art

Heat exchangers usually comprise an assembly of tubes or panels for heat exchange between a first medium, such as a coolant circulating in first channels of the assembly of tubes or panels, and a second medium, such as a flow of air, which flows for example through second channels of the assembly of tubes or panels.

The first channels for the first medium, such as coolant, must therefore be supplied with the first medium. For this purpose, heat exchangers may comprise one or more openings for the medium, connected to a connecting device or connector providing the so-called female part for connecting the so-called male part of the first circuit for the medium. In a known manner, the female part or interface is realized on a metal component of the exchanger in the form of a connector, having the basic shape of a block with openings, and it is adapted to receive a

complementary male part, such as a tube which is connected to the first circuit for the medium. Such connectors, also known as interfaces of the exchanger body or connecting devices, serve for the arrival and removal of gaseous and sometimes liquid first medium to and from an exchanger, and they are manufactured in various ways. Heat exchangers may comprise a connector which is located beneath the upper distributing part of the exchanger in parallel with the end panel of the exchanger. The connector is provided with openings connecting to the main part of the exchanger. A corresponding contact part is at present designed with a

complementary contiguous shape on one side of the head of the exchanger and on the other side for the connecting of tubes. The tube is inserted into the connector and may be afterwards brazed. This connector is press-fitted or seated on the main part of the exchanger from the bottom and the two parts are joined together after brazing at the contact surfaces between the connector and the head of the exchanger. The connector is also usually provided with a socket (or hollow sheath), or sockets, which are press-fitted onto the connector, and once again a connection is made by brazing on the contact surfaces, the arrangement of the connector now being ready for the attachment of tubes. The medium is carried in the connector to and from the exchanger by a circular cross section. Even so, in such a type of press fitting beneath the upper head, where the connector and the head form a junction angle of 90°, it has been found that the quality of the joint might not be stable and that it is dependent on the quality of the press fitting, with consequent failure to maintain sufficient contact between the joined parts during the brazing process.

Another connecting device or connector for direct joining of tubes is known from document EP 2 910 888. The tubes here are brought up in the axis of the head of the exchanger into which they are inserted. But such a solution is not very robust and does not provide adequate strength or resistance needed for the use of high- pressure media, such as R744 (C0 ₂ ).

Further, it has been found for a connector press-fitted directly in the axis across or into the main upper part of the exchanger that the quality of the joint also may not be stable and is dependent on the number of joined parts, where in the event of brazing three or more components together it is necessary to ensure their proper material definition, preparation, and especially thickness of the individual joined materials and their necessary manufacturing precision of the individual components, which increases for the overall connection in dependence on the number of joined parts, so that one might be limited by the manufacturing process tolerance of the part entering into the connection.

Another option is a socket pressed directly onto the connector, but this damages and weakens the fusible Al+Si layer on the socket, which lowers the quality of the brazing and increases the occurrence of porosity and leakage.

The known solutions are also often too bulky and sometimes material demanding. Moreover, the connectors need to achieve minimal pressure losses of medium being carried by the connector and for openings in the connector with cylindrical bore, with a circular transition to the head of the exchanger, this may cause increased pressure losses.

Essence of the invention

The aim of the invention is to achieve optimal conditions for connecting a connector and the head of an exchanger body, and a socket to a connector, ensuring a tight and mechanically stable connection, and this with compact dimensions and little consumption of material, as well as good pressure resistance and the least possible pressure losses in the passage of the first medium through the connector according to the invention, thereby increasing the efficiency of the exchanger.

These aims are achieved and the aforementioned drawbacks are eliminated by an arrangement of a connector for the entry of a first phase and the exiting of a second phase from the head of an exchanger, wherein the connector has the basic shape of a block with at least two arms projecting in a prolongation of its two opposite walls, whereby it is connected to the head of the exchanger by its wall located between said at least two projecting arms, and its projecting arms along their entire length are seated on the head of the exchanger such that they hold the connector in a position attached to the head of the exchanger. The head of an exchanger is sometimes also called a "tank". In the body of the connector there are formed openings to bring in the first phase and openings to take away the second phase. The connector and the head of the exchanger are made of aluminium alloy and the connector surfaces abutting the head of the exchanger are joined to it by brazing.

In this arrangement, there is a connecting or brazing of only two surfaces of the connector and the head of the exchanger, which in terms of brazing is the most simple solution as regards the coordinating of only two tolerance ranges - those of the two components. The retaining of the arms by the head of the exchanger before and during the brazing contributes to the quality and precision of the connection between the connector and the head of the exchanger, and produces a firm mechanical fixation of the two parts and a firm contact between the two brazed surfaces.

The heat exchanger may be an evaporator, the first phase being liquid and the second phase gaseous (the liquid phase may already contain small amounts of the gas phase at the inlet). But the heat exchanger may also be, e.g., a condenser, the first phase being gaseous and the second phase liquid (the gas phase may already contain small amounts of liquid phase at the inlet).

More specifically, therefore, the subject matter of the invention is an arrangement of a connector for the entry of a first liquid phase and the exit of a second gaseous phase from the upper head of an evaporator or for the entry of a first gaseous phase and the exit of a second, usually liquid phase from the lower head of a cooler, generally a condenser, characterized in that the connector has the basic shape of a block with at least two arms projecting upward or downward in a prolongation of its two opposite walls, whereby said connector is connected to the bottom side of the upper head of the evaporator or to the top side of the bottom head of the cooler by its wall located between said at least two projecting arms, and its projecting arms along their entire length are seated on the upper head of the evaporator or the lower head of the cooler,

wherein the connector comprises openings to bring in the first phase and openings to take away the second phase,

wherein the connector and the head of the evaporator or cooler are made of aluminium alloy and the connector surfaces abutting the head of the evaporator or cooler are joined to it by a joint formed by a coherent and uniform layer of nonporous material formed by brazing. The heat exchanger may also be a common gas cooler.

Although the connector is more often connected to the upper head of the heat exchanger, an embodiment is also possible with the connector connected to the bottom head of the exchanger. In such a case, as will be obvious to the skilled person, the design is a mirror image, i.e., the arms project downward and the side of the connector located between them is attached to the top side of the lower head of the exchanger.

The connector advantageously has two openings of basically square shape situated in its wall attached to the head of the exchanger, while a circular opening in the body of the connector is connected to each opening of square shape, in which there is fixed a socket for connecting a pipe to bring in the first phase or take away the second phase. Typically, the socket is made of aluminium alloy of the ABxxx series and the connector is made of aluminium alloy of the A16xxx series (such as A16061). For the brazing process in this case, the socket is provided with a flux on its surface (aluminium alloy of A14xxx series with s 10 to 12% Si), while the surface of the connector is provided only with an activating agent to remove the oxide layer (potassium aluminofluoride).

The circular openings of the connector advantageously have a bore of smaller diameter always in the first part of their length situated the furthest inside the connector and a bore of larger diameter in the outward direction of the following portion of its length, each socket for the attachment of a pipe being fixed by a positive engagement in the circular opening of the connector in its portion of the bore with smaller diameter by material deformation, while in its portion of the bore with larger diameter it is joined to the connector by a joint formed by a coherent and uniform layer of nonporous material formed by brazing. Such a design of the connector arrangement ensures an especially high-quality brazed joint between the connector proper and the socket. The difference between the radius of the bore of smaller diameter and the bore of larger diameter is advantageously less than 0.2 mm, especially less than 0.075 to 0.15 mm.

After inserting the socket, this capillary space is filled with flux between the outside of the socket and the wall of the bore with larger diameter advantageously less than 0.1 mm, especially between 0.075 and 0.1 mm. Such ratios have proven to be especially suitable for the quality of the brazed joint.

An advantageous ratio of the cross section of the opening of square shape to the internal cross section of the socket fixed in the opening of circular shape is between 1.35 and 1.75. At values of this ratio below 1.35, the pressure losses in the connector are too high and thus the exchanger has less efficiency. Values above 1.75 do not provide any added value, since the pressure loss is not diminished; on the contrary, there may be an increased risk of mechanical damage.

In one embodiment, the projecting arms of the connector are always divided into at least two teeth, which are curved basically at a right angle across the upper edge of the head, while they are seated on the head for their entire length. Advantageously, the material of the teeth of the arms at the site of the bending of the tooth into a right angle is thinned out in order to achieve a tight contact along its entire length, the thinning being advantageously done by removal of material on the side facing the head, having advantageously the cross sectional shape of an isosceles trapezoid widening toward the head in the non-bent state of the tooth. Another benefit of dividing the arms into at least two teeth is that a safety element, or projection, which is part of the head of the exchanger and assures a precise position on the head of the exchanger, can fit into the gap between two particular teeth.

In the case when the upper head of the exchanger is formed by an assembly comprising at least a distribution panel, a cover panel, and an intermediate panel arranged between the distribution panel and the cover panel, the connector for the entry of a first phase and the exiting of a second phase from the head of an exchanger is advantageously connected to the bottom surface of the distribution panel by its wall located between said at least two projecting arms, and its projecting arms along their entire length are seated on the assembly of the distribution panel, the intermediate panel, and the cover panel.

Another subject matter of this invention is a heat exchanger, especially for motor vehicles, with two heads situated opposite each other and joined by a set of heat exchange tubes for the passage of a medium between these heads, comprising a connector arrangement as defined above. This may be an evaporator of an air conditioning circuit comprising an upper head of the evaporator with an upper tube plate and with an inlet for liquid phase and an outlet for gas phase, a lower head of the evaporator with a lower tube plate, a bundle of two rows of flat heat exchange tubes arranged in parallel and at mutual spacings and joining the two heads, and heat exchange elements situated between the flat heat exchange tubes.

List of figures in the drawings

The invention will be further explained with the aid of specific exemplary embodiments illustrated in the drawings, which show:

Fig. la, a view of a portion of an assembled exchanger with attached connector arrangement according to the invention,

Fig. lb, a view of the removed connector arrangement and head of the exchanger, Fig. 2, the separated connector and socket, Fig. 3a, a view of the connector arrangement in cross section by a vertical plane passing through the axis of the socket,

Fig. 3b, a detail of Fig. 3a,

Fig. 4a, a detail view of the connector by itself,

Fig. 4b, a view of the connector as per Fig. 4a, with attached distribution panel and partly cut away,

Fig. 4c, a view of the connector from the side with the circular opening,

Fig. 4d, a top view of the connector,

Fig. 5, a detail of the tooth profile of the connector arm in an advantageous configuration,

Fig. 6a, photographs of a section of a finished brazed joint between a socket and a connector according to the prior art acquired by metallographic microscope, Fig. 6b, analogous photographs of a section of a finished brazed joint between a socket and a connector according to the invention with bore of dual diameter, Fig. 7a, an overall view of an evaporator with the connector arrangement according to the invention, and

Fig. 7b, an overall view of another exchanger with the connector arrangement according to the invention. Exemplary embodiments of the invention

In this entire document, terms relating to the orientation of the exchanger such as upper, lower, vertical, horizontal, etc., are related to its orientation as is depicted in the figures, see for example Fig. 7a and 7b. The heat exchanger 1 is in many applications installed in just such an orientation and the indicated directions thus correspond to the position of such an exchanger during its use. The height of the exchanger is its vertical direction, the length is its largest dimension (the left to right direction in Fig. 7a and 7b), and the thickness is its third and smallest dimension in the illustrated embodiment.

A first medium moves through the exchanger 1, entering by the inlet for the first phase and exiting from it by the outlet for the second phase. If the exchanger 1 is an evaporator, then the first phase is liquid and the second phase is gaseous (or also a vapour phase). The liquid phase may already contain small amounts of gaseous phase at the inlet. If the exchanger 1 is a condenser, then the first phase is gaseous and the second phase is liquid (the gaseous phase may already contain small amounts of liquid phase at the inlet).

If the exchanger 1 is a common gas cooler, the first and the second phase may be gaseous.

The exchanger 1 is formed by two heads 2, 3, situated opposite each other and joined together by two rows of heat exchange tubes 6, between which are joined together by fins - the heat exchange elements 7 - serving for the exchanging of heat with another medium, air, which passes through the exchanger transversely in the direction of its thickness.

Figure la and lb show an embodiment of an exchanger 1 whose upper head 2 is formed by an assembly of a distribution panel 21, an intermediate panel 22 and a cover panel 23, which are installed in a U-shaped profile 20. The lower head 3 is formed analogously, basically as a mirror image, by an assembly of a distribution panel 31, an intermediate panel 32 and a cover panel 33, which are installed in an inverted U-shaped profile 30.

The arrangement of the connector according to the depicted exemplary

embodiment is also realized such that the connector 4 proper is connected by its wall situated between the aforementioned at least two projecting arms 41, 42 to the bottom surface of the distribution panel 21, while its projecting arms 41, 42 are seated along their entire length on the assembly of the distribution panel 21, the intermediate panel 22 and the cover panel 23.

In the connector 4 proper are installed sockets 5 for connecting pipes to bring in the first phase and take away the second phase.

Figure lb shows these same two components (connector 4 and head 2 assembly) illustrated separately. At left are shown (not at scale) pipes connected to a circuit with the first medium. Among other things, the division of the arms 41, 42 always into two teeth can be well seen here. These teeth are shown here in the bent form, in their position on the finished product. These teeth are straightened out when the connector 4 is mounted on the head 2 of the exchanger 1, as for example in Fig. 2, 4a, 4b, 4c and 5, and only after mounting the connector 4 on the head 2 of the exchanger 1 are these teeth bent across the edge of the head 2 so that they are seated by their entire length on the head 2.

In the space between these teeth is inserted a projection 99, which is part of the head 2 of the exchanger 1 and which assures an exact position on the head 2 of the exchanger 1. These two elements (the space between the teeth of the arms 41, 42 and the projection 99) constitute elements limiting wrong installation, so-called poka yoke elements (a term coming from the Japanese designation of such elements), i.e., generally elements which when properly mounted fit together with complementary elements of other components, e.g., are flush with them, thus making it practically impossible to assemble the individual components wrong.

Figure 2 shows the connector 4 and both sockets 5 separately in the exemplary embodiment. One may also see in this figure the bore 451 of smaller diameter in the first part of the length of the circular opening 45, situated the furthest inside the connector 4, and the bore 452 of larger diameter, in the second part of the length of the circular opening 45 situated in the outward direction of the next portion of the length of the circular opening 45. The first smaller internal diameter serves for the fixation of the socket 5 and the other larger diameter serves to create a

mechanically firm and tight connection, which is produced during the brazing process.

The socket 5 has two basic parts, a cylindrical part which is fixed or forced into the round opening 45 of the connector 4 (and thus serves to centre the socket 5 in the opening 45 of the connector 4), and a second part, which in the mounted state projects beyond the body of the connector 4 and serves for attaching a pipe for supply or removal of the first medium. This second part is formed by two successive conical parts. The first, internal conical part ensures a correct seating and centring of the supply/drain pipe, which copies this same conical shape at its end in order to define the tolerance. The second conical part provides a space filled with a soldering ring and forming a mechanically firm and tight connection to the tube. This issue is discussed more closely by the document EP 2 910 888 B l. It has proven to be especially advantageous when the first centring conical part extends for a length of hi = 3 to 6 mm and makes an angle with the longitudinal axis of the socket 5 of 2 to 8 degrees. Already a 3 mm length of the centring conical part with a conicity up to 8 degrees fully ensures the desired coaxiality, seating, and stability of the tube in the socket. The second outer conical part could have a height of at least 3 mm, depending on the mechanical computations for the given pressure application and the vertex angle of this second conical part could be greater than the vertex angle of the first conical part by at least 4 degrees. This type of conical centring of a pipe and socket 5 uses a simple final assemblage and ensures a proper quality of brazed connection with optimal access of activating agent, which is released from the solder ring, eliminating any porosity.

Figure 3a and 3b show the connector arrangement with installed socket 5 in a cross section by the vertical plane passing through the axis of the circular opening 45 (coinciding with the axis of the socket 5). A capillary space (see especially Fig. 3b) must be assured between the outer diameter of the socket 5 and the second bore 452 in the connector 4, ideally with dimensions of 0.075 mm to 0.1 mm, and this space ensures the drawing or pulling of the outer melted layer of Al+Si from the socket 5 into the defined space during the brazing process. This space eliminates damage to the surface of the socket 5 and the Al+Si layer and ensures a high- quality, mechanically firm and tight joint with no porosity (Fig. 6b).

Figure 4a shows the connector 4 by itself, revealing the openings 44 for attachment to the head of the exchanger 1, the circular openings 45 for installing the sockets 5 and the projecting arms 41, 42 always separated into two teeth, whose ends after assembling the head of the exchanger with the connector 4 will be bent into a right angle across the upper edge of the head 2, so that these teeth are seated on the head 2 for their entire length. This condition with the bent teeth can be seen in Fig. la and lb. It is important to form the interior passage of the connector bounded essentially by the square opening 44 and the round opening 45 connected to it. These two openings (bores) make an angle of 90 degrees with each other inside the connector. Moreover, the cross sections of these two mutually perpendicular cylindrical and square shapes are in a ratio to each other of 1.35 to 1.75, the cross section of the square opening being larger than the cross section of the round opening.

Figure 4b shows, partly in sectional view, a detail of the assembly of the connector 4 with the distribution panel 21. One can see in this figure 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 panel 21.

For a better understanding, the enlarging of the cross section during the passage of the first medium from the supply tube through the connector to the head of the exchanger (i.e., the square opening 44 as opposed to the internal cross section of the socket) is advantageously approximately such that the square cross section circumscribes the round one, whereby we always ensure the same thickness of the connector wall, in the case when a minimal material force needs to be ensured, whether in terms of mechanical strength, pressure or corrosion resistance.

Moreover, in terms of position accuracy and maintaining the cross sections with respect to the head 2, 3 of the exchanger, it enables the use of larger manufacturing tolerances for the connector 4 and the head 2, 3 of the exchanger.

Figure 4d shows a top view of the connector 4, i.e., from the side with the square openings 44. Figure 4c shows a view of the front side of the connector 4 with round openings 45. One can see here "from the side" the arms 41, 42 or their end teeth. The detail of the profile of one tooth of an arm of the connector is shown in cross section in Fig. 5. Advantageously, the length b of the substantially level recess corresponds to its depth a. Thus, the depth a and length b may

advantageously have a dimension of approximately 0.5 to 0.7 mm, for example. The teeth of the arms 41, 42 are advantageously formed substantially the same as the teeth 201 of the U-shaped profile 20 of the head 2 of the exchanger. Figure 6a shows photographs of a section of the finished brazed connection of the socket to the connector, obtained on an exchanger according to the prior art, acquired by a metallo graphic microscope. One notices here relatively great porosity of such a joint over the entire length of the joint between socket and connector.

Figure 6b, on the other hand, shows photographs of a section of a finished brazed joint between a socket 5 and a connector 4 according to this invention. In this photograph from a metallographic microscope the joint between the socket 5 and the connector 4 in the region of the bore 451 of smaller diameter is comparable to the joint as per the prior art, but in the remaining portion of this joint in the region of the bore 452 of larger diameter according to the invention a fissure filled with flux evident, and the joint in this region exhibits much less porosity than in the case of the prior art.

The exchanger 1 in the overall view shown in Fig. 7a is an evaporator of an air conditioning circuit, especially for a motor vehicle. In this drawing, the heat exchange elements 7 are shown only at the left hand side, in order to better see the heat exchange tubes 6 leading between the two heads 2, 3 of the exchanger 1. From the standpoint of the passage of the first medium through the exchanger, Fig. 7a is an exchanger with six sections (see the division of the bulges of the cover panel 23 of the upper head 2). These sections are always formed by several adjacent heat exchange tubes 6 of one row, in which the coolant flows from one head 2 or 3 to the other head 3 or 2, respectively, in the same direction). The movement of coolant through such an exchanger is as follows: from the first head (the upper head 2 in the embodiment shown) it is taken by 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), by the second section to the first head, by the third section to the second head, in which the coolant moves across the exchanger (so-called bypass section) to the side with the second row of heat exchange tubes 6 (i.e., on the outlet side), and back by the fourth section to the first head, by the fifth section to the second head, and by the sixth section to the first head and to the outlet. Figure 7b shows another exemplary embodiment of an exchanger 1 according to the invention, namely a gas cooler, a so-called inner gas cooler. In this case, it is an exchanger with only two sections: cooled gas moves through all heat exchange tubes 6 of the row of heat exchange tubes 6 on the inlet side from the upper head 2 to the lower one 3, in which the cooled gas as a whole moves across the exchanger (the entire lower head 3 forms a bypass section), and then through all the heat exchange tubes 6 of the second row 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.