FR2933015A1 - Assembling a first part and a second part by brazing, comprises applying an assembling agent on the first part, placing the two parts against one another, and transferring the agent through the first part for assembling the two parts - Google Patents

Abstract

The process comprises applying an assembling agent on a first part, placing two parts against one another, and transferring the agent through the first part for assembling the two parts. The first part is assembled to a second part along a length of an assembling surface, and comprises a first side (9) and a second side (10), which is intended to be assembled to the second part and openings for the passage of assembling agent towards the second side. The assembling agent is a flow of brazing, and discharges at a level of the assembling surface after the transfer through the first part. The process comprises applying an assembling agent on a first part, placing two parts against one another, and transferring the agent through the first part for assembling the two parts. The first part is assembled to a second part along a length of an assembling surface, and comprises a first side (9) and a second side (10), which is intended to be assembled to the second part and openings for the passage of assembling agent towards the second side. The assembling agent is a flow of brazing, discharges at a level of the assembling surface after the transfer through the first part, and is applied on the first side. The first side of the first part is assembled with a third part. Once the parts are fixed, the first side is intended to be in contact with a first fluid and the second side is intended to be in contact with a second fluid. An independent claim is included for a part to be assembled to a second part by brazing.

Description

The invention relates to a method for assembling two parts.

A "blade" heat exchanger may comprise metal plates (or blades), fixed in pairs to each other, each pair of plates forming passage channels for a first fluid, for example by means of ribs, stamped on each plate, coming into contact and leaving between them said channels. The pairs of plates can be separated by spacers between which flows a second fluid. Both fluids exchange heat through the plates.

The plates can be attached to each other by soldering. Brazing is the assembly of two metal parts using a filler metal, referred to as solder. The solder, which has a melting temperature lower than that of the metals to be assembled, is heated and forms by melting a metallurgical bond with the metal of each piece; the two pieces are thus bonded to one another via the solder, which forms an alloy with the metal of each plate. Quality fixation is achieved in terms of fluid tightness as well as mechanical strength or thermal conduction, which are important features of a heat exchanger.

The brazing can be implemented, either under vacuum or "under flow". In the latter case, a "soldering flux" is applied to the parts to be assembled, the function of which is to facilitate the brazing reaction. The soldering flux is a product which makes it possible to remove impurities from the surface of the parts to be assembled which could adversely affect the brazing reaction, to protect these parts from oxidation for the duration of the soldering operation or else to lower the surface tension of metals for a better reaction; it therefore increases the wettability of the metals to be assembled. Thus, in general, the brazing flux comprises a reducing agent which removes oxides which may be on the surface of the metal. The flux may be in the form of agglomerate, powder, paste, liquid or gas.

During the brazing process, the parts to be assembled are heated. The first element to act is the soldering flux. Then the solder melts and forms a link between the parts to be assembled.

When all the plates of a heat exchanger are brazed, the flux is previously applied to the entire surface of the plates. Once the soldering process is completed, there may remain flow residues on the plates, in particular on their portions of surfaces not fixed to another plate. Since the plates form passageways for fluids (for cooling or cooling) between them, these flow residues may be entrained by the fluids and / or react with them. In particular, if a fluid is water, there is a high risk of corrosion by reaction between the water and the solder flux on the metal (which reaction is for example an acidification reaction); such corrosion causes an alteration of the metal which can have consequences as serious as the piercing of a plate and thus the leakage of water in a channel which is not dedicated to it, for example in the gas circulation channel. engine or exhaust gas supply. The presence of flux residues may also result in the formation of deposits, which may be entrained by a fluid to other locations of the fluid circuit, for example to fluid flow control valves or valves, causing malfunctions of said valves or said valves. Moreover, the presence of flux residues in the fluid circulation channels may result in a decrease in the efficiency of the heat exchanges.

The invention aims to overcome these disadvantages.

The invention has been presented in connection with problems related to the brazing of the plates of a heat exchanger of a motor vehicle and it is particularly applicable to the resolution of these problems for this particular application. The invention nevertheless applies more generally to the assembly of parts.

Thus, the invention relates to a method of assembling a first piece and a second piece, comprising: - the application of a bonding agent on the first piece, - the application of both pieces against each other and - migration of the agent through the first piece to assemble the two pieces.

Thanks to the invention, it is not necessary to apply the bonding agent on the side of the first piece to be joined to the second piece, since the assembling agent migrates through the first piece to allow the assembly of the two parts. Thus, there are no residues of the assembly flow between the assembled parts.

According to a preferred embodiment, the parts are assembled by soldering and the assembly agent is a soldering flux.

According to a preferred embodiment, the first part being assembled to the second part along at least one assembly surface, the assembly agent opens, after its migration through the first part, at said surface. assembly. For this purpose, the first piece comprises means for passage of the assembly agent for its migration through it at the assembly surfaces.

Thus, there are no residues of the bonding agent outside this assembly surface. By the expression "at said assembly surface", it is understood that the agent migrates along this assembly surface, but not necessarily all along this surface; the agent can migrate on a discrete series of surfaces contained in the assembly surface or along the entire surface thereof; in any case, it does not migrate outside this surface.

According to a preferred embodiment, the first part comprising at least a first face and a second face, which is intended to be assembled to the second part, and means, for example orifices, for the passage of the assembly agent. from the first face to the second face, the bonding agent is applied to the first face.

According to a preferred embodiment, the first face of the first piece being assembled to a third piece, the assembling agent migrates only partially from the first face to the second face.

According to a preferred embodiment, once the parts are fixed, the first face is intended to be in contact with a first fluid and the second face is intended to be in contact with a second fluid.

According to a preferred embodiment in this case, the parts are plates arranged to form fluid circulation channels in a heat exchanger. The invention further relates to a part intended to be assembled to a second part with a fastening agent applied to it, said part comprising means of passage of the assembling agent for its migration through it for its assembly to the second room. Such a part allows the implementation of the method presented above and thus provides the advantages thereof.

According to a preferred embodiment, the part comprising at least a first face and a second face, which is intended to be assembled to the second part, and means, for example orifices, for the passage of the assembly agent. from the first face to the second face.

According to a preferred embodiment, the part being intended to be assembled to the second part along at least one assembly surface, in which the means of passage of the coupling agent open on the surface of the assembly. assembly.

According to a preferred embodiment, the part having joining surfaces to the second part symmetrical with respect to each other with respect to an axis, the second part being similar to the first part and intended to be assembled therewith vis-à-vis, the passage means of the assembly agent are distributed asymmetrically with respect to said axis.

According to a preferred embodiment, the part is a plate of a heat exchanger, having brazing attachment surfaces to another plate, at which are provided openings for the passage of a brazing flux.

According to one embodiment, the plate is a flat plate of a so-called flat-plate heat exchanger. The plate may comprise stamped ribs, attachment to another flat plate, orifices being drilled in the plate at the ribs, in their area of contact with another flat plate.

According to one embodiment, the plate is a shaped plate of a heat exchanger said interlaced blades. The plate may comprise a raised edge and stamped grooves for attachment to another shaped plate, holes being drilled in the plate at the edge and grooves, in their areas of contact with another shaped plate.

The invention also relates to a heat exchanger, comprising a plurality of plates such as that presented above.

The invention will be better understood with the aid of the following description of the preferred embodiments of the method and exchanger of the invention, with reference to the attached drawing plates, in which: FIG. sectional view of a blade heat exchanger according to a first embodiment of the invention; FIG. 2 represents a perspective view of a flat plate of the heat exchanger of FIG. 1; FIG. 3 represents a sectional view, in the plane III-III of FIG. 2, of a plate of the type of that of FIG. 2 facing a plate to which it is intended to be brazed; - Figure 4a shows a partial schematic top view of the plate of Figure 2; FIG. 4b shows a partial diagrammatic sectional view, corresponding to the view of FIG. 4a, at orifices, of the plates of FIG. 3; FIG. 5a shows another partial schematic view from above of the plate; of Figure 2; FIG. 5b shows a partial schematic sectional view, corresponding to the view of FIG. 5a, at the level of orifices, of the plates of FIG. 3; FIG. 6 represents an enlarged view of zone Z of the plate of FIG. 2; Figure 7 shows a sectional view of a blade heat exchanger according to a second embodiment of the invention; FIG. 8 represents a view from above of a first blade shape that can be used in an exchanger of the type of that of FIG. 7; FIG. 9 represents a view from above of a second blade shape that can be used in an exchanger of the type of FIG. 7; and FIG. 10 represents a schematic sectional view of a contact zone between four plates. successive stages of the exchanger of FIG.

Referring to Figure 1, a heat exchanger 1 according to a first embodiment comprises substantially planar plates 2, which we will name later, for the sake of simplification, flat plates 2; the person skilled in the art usually speaks, for such flat plates 2, of blades 2; for this reason, exchangers of this type are called planar exchangers. The flat plates 2 are assembled in pairs, the plates 2 of each pair forming between them a channel 3 for circulation of a fluid, here a cooling liquid, for example glycol water. The pairs of plates 2 are separated from each other by interleaves 4, which are in this case corrugated plates 4; the spacers 4 extend between two flat plates 2 (of two different pairs) and provide a circulation channel 5 for a fluid, here a gas to be cooled, for example air. The heat exchanger 1 is here a charge air cooler for a motor vehicle. Intercalated corrugated plates 4 impose on the air circulating between them a turbulent flow, facilitating heat exchange with the coolant flowing in the channels 3 formed between the flat plates 2. The general structure and operation of a Such heat exchangers are well known to those skilled in the art and therefore do not need to be described in more detail. The plates may for example be in an alloy type 3003.

With reference to FIG. 2, each flat plate 2 is of generally rectangular shape; it extends along a principal axis A, parallel to the direction of the lengths of the rectangle of which it has the shape and forming median widths of this rectangle. The plate 2 is pressed to form ribs 6 which, by contact with corresponding ribs 6 of another plate 2, form walls of the channel 3 for circulating the coolant; the channel 3 has in this case generally the shape of a coil, formed by rectilinear channel portions parallel to the lengths of the rectangle whose plate has the shape, connected by portions forming a half-turn at the ends. The plate 2 comprises, at one of its ends, two bores 7a, 7b respectively of liquid inlet and outlet in the brine circulation channel 3 formed by the plate 2.

The ribs 6 of the plate 2 are symmetrical with each other with respect to the main axis A of the plate 2. Thus, the channels 3 can be formed between two identical plates 2, one being returned around its main axis A to face to face with each other, so that their ribs 6 come in contact. The plates 2 are fixed to each other along the ribs 6, which thus form fixing surfaces.

There is shown in Figure 3 a first plate 2a and a second plate 2b arranged to form a pair of plates; in Figure 3, they are vis-à-vis one another but not yet in contact with each other. These are two plates 2a, 2b identical to each other and to the other plates 2 of the pairs of plates 2 of the exchanger 1; as a result, the various elements of these plates 2a, 2b (in particular their ribs 6, their main axis A, etc.) are designated by the same references. Furthermore, in the remainder of the description, references 2a, 2b and 2 will be used interchangeably, being in fact references for identical plates.

Due to the symmetry of the ribs 6 of each plate 2a, 2b with respect to its main axis A, the ribs 6 of the two plates 2a, 2b are vis-à-vis each other when the two plates 2a, 2b are put face to face. The plates 2a, 2b are fixed to one another along their ribs 6. The surfaces 10 'of the plates 2a, 2b situated on either side of the ribs 6 form, with the ribs 6, when the ribs 6 are in contact and fixed to each other, the channel 3 for circulating the coolant.

The ribs 6 of the plates 2a, 2b are pierced with orifices 8, in particular represented in FIGS. 4 and 5, allowing the migration of the assembling agent of the plates 2a, 2b with each other. In this case, the plates 2a, 2b are arranged to be soldered, in particular along their grooves 6 (more exactly, along the upper surfaces of their grooves 6, the upper position corresponding to the upper position in FIG. 2). .

This is a so-called "flux" brazing, that is to say with prior application of a brazing flux, to allow the wetting and stripping of the metals to be assembled, as explained above in the introduction of the description. The bonding agent is a soldering flux.

Each plate 2a, 2b has a first face 9 and a second face 10, on either side of the thickness of the plate 2a, 2b. By convention, the ribs 6 projecting from one side of each plate 2a, 2b, will be designated, in the following description, by first face 9, the face extending from the opposite side to the side where the ribs 6 are protruding, by the second face 10, the side extending on the side where the ribs 6 are projecting. The plates 2a, 2b being assembled along their ribs 6, it is therefore their respective second faces 10 which are fixed to each other (and which are vis-à-vis in Figure 2).

The orifices 8 are pierced through each plate 2a, 2b and open on either side of the plate 2a, 2b, that is to say that they open on each face 9, 10 of the plate 2a, 2b . Each orifice 8 thus forms a channel for passing the soldering flux from the first face 9 to the second face 10. The orifices 8 are pierced only at the level of the ribs 6. The orifices 8 are moreover distributed over the plates 2a, 2b so that, when the plates 2a, 2b are applied against each other, the orifices 8 of a plate 2a, 2b are not opposite the orifices 8 of the other plate 2b, 2a; the distribution of the orifices 8 will be detailed later.

The method of assembling two plates 2a, 2b is implemented as follows.

A filler metal (solder) is applied to the plates 2a, 2b, on their second face 10, in a known manner. It is possible, for example, to use a filler metal of the type 4045 or 4343. In this case, the filler metal is present in the form of a laminate in the plate 2a, 2b: for this purpose, when it is stamped , the plate 2a, 2b is stamped with a sheet of the filler metal, which thus directly forms the outermost layer (on the side of the second face 10) of the laminate of the plate 2a, 2b. In this case, solder is also present, in this case in the form of a laminate, on the first face 9 of each plate 2a, 2b, for fixing the spacers 4 to the flat plates 2a, 2b.

For fixing the first plate 2a to the second plate 2b, the brazing flux is applied to the first faces 9 of the plates 2a, 2b and only on these first faces 9. The two plates 2a, 2b are applied against one the other and are heated to a first temperature. The solder flux, whose melting temperature is lower than that of the filler metal (the first temperature being between them), is the first element to be melted.

When it is in the molten state, the soldering flux partially migrates from the first face 9 of each plate 2a, 2b towards the second face 10 of the plate 2a, 2b, through the orifices 8 provided for this purpose . A portion of the solder flux is thus found at the interface between the second faces 10 of the first plate 2a and the second plate 2b, at the openings 8 through which it has migrated.

By capillarity (or any other phenomenon such as gravity or migration to the hot spots), the brazing flux spreads around each orifice 8, in this interface, exerting its action on the solder present on the plates 2a, 2b. Thus, the flow is present and exerts its action only in the zone where it has migrated, that is to say the fixing area (the ribs 6 of fixing) plates 2a, 2b between them. The portions 10 'of the second surface 10 of the plates 2a, 2b are thus not contaminated by the soldering flux.

The plates 2a, 2b are heated to a second temperature, higher than the first temperature (and the melting temperature of the solder), to melt the solder and allow the brazing reaction along the surfaces (the ribs 6) of fixing the plates 2a, 2b.

In this way, the plates 2a, 2b are fixed to one another along their ribs 6.

The surface portions 10 'of the second faces 10 of the plates 2a, 2b situated around the ribs 6, that is to say the portions of surfaces 10' delimiting the channels 3 with the ribs 6, have not been in contact with the soldering flux, since the latter could migrate through the plates 2a, 21) only through the orifices 8, which are located at the ribs 6. These portions of surfaces 10 'are therefore not polluted by soldering flux residues, which solves the problems presented in the introduction, related to a possible residual presence of solder flux in an area in which a fluid is intended to flow.

In the case presented, it has been chosen to apply soldering flux only on the first face 9 of the plates 2a, 2b because this face 9 is intended to be in contact with air, while the second face 10 is intended to be in contact with water. Of course, the choice of the face on which is applied the brazing flow brought to migrate to the other side depends on the application and constraints of the skilled person in this application.

The method of manufacturing a heat exchanger such as that of Figure 1 is as follows. Brazing flux is applied to the first face 9 of each flat plate 2, as well as to the surfaces of the spacers 4. The flat plates 2 are applied, in pairs, against each other face to face, while the intermediate plates 4 are applied to the first surfaces 9 of the flat plates 2. When the assembly is heated, a portion of the solder flux applied to the first faces 9 of the flat plates 2 migrates to the corresponding second faces 10 for soldering to the other flat plates 2, while the remainder of the brazing flux allows the soldering of the flat plates 2 to the spacers 4. The brazing of all the elements of the exchanger 1 is obtained in a single step, that is to say that all the elements of the exchanger 1 are brazed at the same time to each other. Thanks to brazing, the connections between the plates 2 fulfill functions of sealing, mechanical resistance and thermal conduction.

The distribution of the orifices 8 for passage of the soldering flux will now be detailed.

FIG. 4a shows two ribs 6 symmetrical with respect to the principal axis A (or major axis A) of a flat plate 2. The orifices 8 of these ribs 6 are distributed so as not to be symmetrical with each other but offset, for example staggered, relative to each other in a direction parallel to the main axis A.

We denote by the reference A 'the small axis of the flat plate 2. It is recalled that the main axis A of the plate A is the axis extending in the direction of the large dimension of the plate 2; in the presence of a rectangular plate 2, it is therefore the axis parallel to the lengths of the rectangle whose plate 2 has the shape and passing through the center of this rectangle. The small axis A 'is an axis perpendicular to the main axis A, parallel to the widths of the rectangle whose plate 2 has the shape and passing through the center of this rectangle.

In this case, the successive orifices 8 of a rib 6 are spaced from each other by a pitch "p". The orifices 8 of a rib 6 are here offset relative to the orifices 8 of the rib 6 which is symmetrical with respect to the main axis A by a distance equal to half the pitch, that is to say p / 2. Another value can be provided. The advantage of an offset equal to half the pitch is a more uniform overall distribution of the orifices 8 on the plate 2.

It is noted that the closer the orifices 8 are, the more the distribution of the brazing flux can be dense at the interface between two plates.

FIG. 4b shows a sectional view of the first and second flat plates 2a, 2b of FIG. 3, the section being made at the level of orifices 8. The various parts of the plates 2a, 2b of FIG. 4b (ribs 6 , main axis A) are aligned with the corresponding parts of the plate 2 of Figure 4a, for ease of understanding. Due to the distribution of the orifices 8 and in particular the asymmetry of the orifices 8 belonging to the ribs 6 symmetrical to each other, the orifices 8 of the first plate 2a are not opposite the orifices of the second plate 2b, and vice -versa, when these plates 2a, 2b are put face to face. In other words, each orifice 8 of a plate 2a, 2b is necessarily in front of a solid part of the plate 2 facing it, that is to say of a non-pierced part of this plate 2. , to put the plates 2a, 2b face to face for their attachment, one of the two plates 2a, 2b is rotated 180 ° about its major axis A. Due to the symmetry of the ribs 6 and the asymmetry of the 8 of these ribs 6 relative to the major axis A, the consequence of this pivoting is that the ribs 6 of the two plates 2a, 2b are found face to face and abut, while the orifices 8 of these ribs 6 are not face to face.

FIG. 5a shows another view of the plate of FIG. 4a, on which the central rib 6 'of the plate 2 appears, as well as the ribs 6 of FIG. 4a. The central rib 6 'is the rib whose axis is collinear with the main axis of the plate 2. If such a central rib 6' had a single row of orifices 8, these orifices 8 would face one another. others when two plates 2 would be placed face to face, since, as explained above, the application of two plates 2a, 2b face to face involves the pivoting of one of the two around its main axis A.

This is why the central rib 6 'has a width which is substantially equal to twice the width of the other ribs 6 and has two rows of orifices 8. The orifices 8 of a row are offset relative to the orifices of the Another row for, once two identical plates 2 applied face to face, do not extend against each other. In this case, the successive openings 8 of a row being spaced from each other by a distance (of a pitch) "p", the orifices 8 of a row are offset with respect to the orifices 8 of the another row a distance p / 2.

Figure 5b is a sectional view of the flat plates 2a, 2b of Figure 3 at the level of orifices 8; the parts of the plates 2a, 2b of FIG. 5b, (ribs 6, 6 ', main axis A) are aligned with the corresponding parts of the plate 2 of FIG. 5a for a better readability of these figures. FIG. 5b shows that, because of their distribution on the central ribs 6 'of the plates 2a, 2b, the orifices 8 of the first and second plates 2a, 2b are not facing each other when the plates 2a, 2b are placed face to face. On the contrary, the orifices 8 of a plate 2a, 2b are opposite solid portions of the opposite plate 2b, 2a.

Thanks to the distribution of the orifices 8 on the various ribs 6, 6 ', avoiding them face to face, the migration of the brazing flux from the first face 9 of the plates 2a, 2b to their second face 10 is optimized to ensure a better distribution of this flow on the ribs 6, 6 '. Indeed, if orifices 8 were face to face, the brazing flow would pass from one orifice to another and migrate with difficulty in the interface between the two plates 2a, 2b. On the contrary, in the present case, the brazing flux which migrates through an orifice 8 opens on a solid surface of the opposite plate 2 and is thus caused to be distributed at the interface between the two plates 2a, 2b.

The distribution of the orifices in relation with plates 2 placed face to face by pivoting about their major axis A is explained. Of course, the plates could be placed face to face by pivoting about their minor axis A ', or by pivoting both around their minor axis A 'and their major axis A. The symmetry relations of the ribs 6 and asymmetry of the orifices 8 are adapted accordingly. In particular, it may be necessary, in addition to asymmetry with respect to the major axis A, to provide asymmetry or misalignment of the orifices 8 relative to the minor axis A 'of the plate 2; by offsetting the orifices 8, it will be understood that the minor axis A 'of the plate 2 does not cut any orifice 8. Whatever the case may be, the distribution of the orifices 8 is determined geometrically, as a function of the pivoting to be performed, and of the arrangement of the ribs 6; the definition of this distribution as a function of the geometry of the plate 2 and the nature of the pivoting possibly to be performed for its attachment to an identical plate (or not) is accessible to those skilled in the art.

Referring to Figure 6, the flat plate 2 further comprises curved protrusions stamped in its surfaces 10 'extending between the ribs 6; the person skilled in the art generally speaks, concerning such protrusions, of picks or pins. These are portions of curved surfaces, circular base.

There are two types of pimples. 11 referred to as "turbulation" or turbulence pins and 11 'said bracing.

The turbulence pins 11 are pins whose function is to generate turbulence in the flow between the plates 2. These turbulence pins 11 are not distributed symmetrically with respect to the main axis A of the plate 2. Their height (that is to say the dimension perpendicular to the surface 10 'out of which they are projecting) is generally less than the height of the ribs 6. These turbulence pins 11 are not arranged to come into contact with one another. with the turbulence pins 11 of a plate with which the plate 2 is brazed and are therefore not brazed with other pins 11 when the plates are assembled. Their function is to locally reduce the cross section of the fluid, in order to change the type of flow (which for example laminar becomes turbulent) to improve the heat exchange coefficient.

The bracing pins 11 'are pins whose function is to maintain the gap between two plates 2a, 2b brazed to each other and to stiffen the assembly. The braces II 'of a plate 2a, 2b are brazed to corresponding spacer pins 11' of the other plate 2a, 2b. For this purpose, the bracing pins 11 'are distributed symmetrically with respect to the major axis A of the plates 2a, 2b. Their height is equal to that of the ribs 6, so that when the two plates 2a, 2b are applied face to face against each other, the bracing pins 11 'abut on each other, in pairs. To improve their contact, the pins 11 'have a flattened free end surface; the pins 11 'are thus in contact with one another along flat surfaces. The bracing pins 11 'form, after soldering, a rigid connection between the two plates and allow mechanical reinforcement of the water circulation channel 3, notably improving its resistance to pressure.

As well as the ribs 6, 6 ', the bracing pins 11' are pierced with orifices (not shown) for passing the brazing flux. As previously, to avoid that orifices are found face to face, the orifices are distributed on the pins 11 'asymmetrically. Thus, for example, only the pins 11 'of the right part of a plate 2a, 2b (with respect to its main axis A) are pierced with orifices; thus, once a first plate 2a returned to be placed facing a second plate 2b to which it must be brazed, the pierced pins 11 'of the right part of the first plate 2a end up facing undrilled pins 11' of the left part of the second plate 2b.

A heat exchanger 12 according to a second embodiment is described with reference to FIGS. 7 to 10. It is a so-called interlaced exchanger, that is to say an exchanger 12 comprising plates 13 which are not not planar but shaped to perform a dual function, forming fluid circulation channels to cool and cooling, and forming the housing of the exchanger 12.

It can be seen on the left-hand part of FIG. 7 that the edge 14 of the plates 13 is raised to form an outer casing, by contact of these raised edges 14 between them. In their central part, the plates 13 comprise embossed grooves 15 whose shape is arranged to form fluid circulation channels between the plates 13.

Figures 8 and 9 show two different forms of plates 13 ', 13 "can be used in a exchanger 12 with interlaced blades.

The plate 13 'of FIG. 8 comprises grooves 15' in the shape of a V-shape. It also has a raised edge 14 'arranged to form, with the edges of the other identical plates stacked with it, the housing of the exchanger 12. The plate 13 'furthermore comprises, on the left side (in FIG. 8), a water inlet bore 16a and a water outlet bore 16b, on the right side, an air inlet bore 16c. and an air outlet bore 16d. An exchanger 12 is formed by a stack of such plates 13 'on each other, the orientations of the grooves 15' of the plates 13 'being alternated in one direction and the other from one plate to another; in other words, the exchanger 12 comprises plates 13 'of a first type, not shown, the grooves 15' are V-shaped oriented to the left as in Figure 8, and plates 13 'of a second type, whose grooves 15 'are V-shaped oriented to the right, these plates being stacked one on the other, alternating plates of the first type and plates of the second type. The grooves 15 'come into contact with each other sporadically and create a tormented and irregular flow volume that generates turbulence in the flow of fluids, improving the heat exchange coefficient; when it is said that the grooves 15 'contact one-offly, it is understood that they come into contact in portions of discrete surfaces, that is to say that they do not come into contact along a continuous surface of the grooves 15 'but on portions of discrete surfaces of these grooves 15'. Each plate 13 'is arranged so that different fluids flow on either side of it. It is for this reason that each plate 13 'is pierced with four bores 16a-16d input or output; the bores operate in pairs (16a, 16b), (16c, 16d), each pair of bores (16a, 16b), (16c, 16d) allowing entry and exit of a fluid (here, either water, or oil, respectively) on one side of the plate 13 '.

The plate 13 "of FIG. 9 comprises rectilinear oblique grooves 15 parallel to each other. It also comprises a raised edge 14 "arranged to form, with the edges of the other identical plates stacked with it, the housing of the exchanger 12. The plate also comprises a bore 17a of water inlet and a bore 17b a water inlet bore 17c and an oil outlet bore 17d, as previously, an exchanger 12 is formed by a stack of plates 13 "of a first type and a second type, the orientations of the oblique grooves 15 "of the plates 13 'being alternated in one direction and the other from one type of plate to another, thus forming, once in contact with the grooves 15" d' another plate 13 ", a disturbed volume for the flow of the fluid As before, each plate 13 'is arranged so that different fluids flow on either side of it, each pair of bores (17a, 17b), (17c, 17d) allowing the flow of fluid on one side of the plate 13 "considered.

Such wound heat exchangers 12 are well known to those skilled in the art. It is therefore not necessary to describe their structure in more detail. Such a heat exchanger is illustrated, for example, in EP 0 623 798. Only the specificities will be detailed.

As for the first embodiment presented above (exchanger with flat blades), the plates 13 ', 13 "of an exchanger with reeded blades are pierced with orifices, not shown, allowing the passage of the soldering flux of one side of the blades towards the other.

More specifically, if the exchanger is formed of a stack of blades 13 ', 13 "of a first type and a second type, only the blades 13', 13" of a particular type, for example the blades 13 ', 13 "of the first type, are pierced with orifices for passage of the solder flux, it is recalled that the blades 13', 13" of the first type and the blades of the second type 13 ', 13 "are blades 13' 13 "whose shape of grooves 15 ', 15" is different, typically grooves with inverted oblique segments (it can include straight or V-shaped grooves).

There is shown in Figure 10 a sectional view of a portion of a stack of plates 13a of a first type (which appear greyed) and plates 13b of a second type (which appear hatched); here we see two plates 13a of the first type and two plates 13b of the second type. Only the plates 13a of the first type are pierced with orifices 18 for the passage of the soldering flux, in this case at the level of grooves 15.

A first fluid, for example oil, flows between the lower surfaces of the plates 13a of the first type and the upper surfaces of the plates 13b of the second type (the lower and upper notions correspond to the lower and upper positions in FIG. do not prejudge the orientation of the plates in the exchanger). A second fluid, for example water, circulates between the upper surfaces of the plates 13a of the first type and the lower surfaces of the plates 13b of the second type.

For the manufacture of the exchanger 12, the brazing flux is applied only on the lower faces of the plates 13a of the first type. During the brazing process, part of this flow migrates from the lower faces of the plates 13a of the first type to the upper faces of the plates 13a of the first type, at the orifices 18. The soldering flux can thus migrate into the interface between the plates 13a of the first type and the plates 13b of the second type. Thus, there are solder flux residues only on the lower surfaces of the plates 13a of the first type, that is to say on the air side, while there is none on the upper surfaces of the plates 13a of the first type, that is to say the side of the water (the flow having migrated at the level of the attachment zones to the plates 13b of the second type).

Orifices 18 for passing the brazing flux can be drilled in all the zones of the plates 13a of the first type likely to be in contact with zones of the plates 13b of the second type. In particular, openings 18 are pierced through the raised edges 14 of the plates 13a and at the top of the grooves 15, at the regions of contact with grooves of the plates 13b of the second type. For this purpose, the grooves 15 are preferably arranged to present flattened upper and lower surfaces, which increases the contact surface and therefore the surface in which the orifices 18 may be formed. Only one plate in two being pierced, it In this embodiment, there is no problem of symmetry for the orifices 18.

Note that, in the case of a stack of plates of a first type 13a and a second type 13b, each plate of the first type 13a is fixed on either side to a plate of the second type 13b, the brazing flux being applied only on one side. This is actually a variant of the case, mentioned for the first embodiment of the exchanger of the invention, wherein the first part is attached to a second and a third part; in this case, the second and third parts are identical and consist of a plate of the second type 13b. The plates of the second type 13b are thus fixed to those of the first type 13a on the application side of the brazing flux for their upper surface and the migration side of the brazing flux for their lower surface.

The invention has been presented in connection with a brazing process in which the brazing flux is migrated through a first piece for attachment to a second piece; the brazing flux is an assembly agent in the generic sense of the term, the function of which is in this case to facilitate the action of a fixing agent (solder). The principle of the invention extends to other assembly agents. It may in particular be directly a fixing agent (a filler metal, an adhesive, or other) that migrates through the first piece for attachment to the second piece.

The invention has been presented in connection with a charge air cooler in which the charge air is cooled by a coolant. Of course, the invention applies more generally to any heat exchanger, whatever the cooled fluids and cooling.

As stated above, the invention moreover applies more generally to the assembly of two parts.

As regards the applications to the heat exchangers, the cooled and / or cooling fluids may in particular be air, gases, water or oil, all the possible combinations between these liquids may be envisaged. For the application of the assembly agent, the person skilled in the art chooses the face in contact with the fluid for which the presence of the agent is the least problematic. This choice depends on the application considered.

In the embodiments presented, a first part must be fixed to a second part and to a third part, respectively by its second and first faces; the bonding agent is applied to the first face for attachment to the third piece, a portion of the bonding agent migrating through the first piece to its second face for attachment to the second piece. According to another embodiment, the first part can be fixed only to a second part, the assembly agent being applied to the first face of the first part only in view of its migration towards the second face for its attachment to the second room.

In the case where the first part must be fixed to a second and a third part, the flow can be applied, on the first face of the first part, either on the entirety of the surface of this face, or on a part only . Thus, assuming that the first part is fixed on both sides to the second and third parts along corresponding attachment areas, the soldering flux can be applied to the first face of the first part only on its zone attachment to the third piece, the flow migrating from this attachment area to the third piece to the attachment area to the second piece. This migration is done through the first piece; it can be done perpendicularly to the first and second faces (if they are parallel and their attachment areas are in line with each other) or follow a more complex trajectory if the fixing areas are not at right the one of the other.

Applying the bonding agent over the entire surface of the first face of the part has the advantage of simplicity because it is easier to apply an agent in a manner that is not localized but evenly distributed. If the presence of residues of the assembly agent on the first face, on its surface portions not used for example for fixing to a third part, is not problematic for the fluid in contact with it, the process is implemented simply and effectively; the agent is applied over the entire first face and migrates partly to the second face only at the passage holes, which are located on the attachment areas, the second part, the second surface; thus, there are no flux residues on the other portions of the second surface but only on the portions of the first surface, for which this is not problematic.

Claims (13)

Claims1- A method of assembling a first part (2a, 13a) and a second part (2b, 13b), comprising: - the application of a bonding agent on the first part (2a, 13a) - the application of the two pieces (2a, 13a), (2b, 13b) against each other and - the migration of the agent through the first piece (2a, 13a) to assemble the two pieces ( 2a, 13a), (2b, 13b). 2- Assembly method according to claim 1, wherein the assembly of the parts (2a, 13a), (2b, 13b) is soldered and the bonding agent is a soldering flux. 3- assembly method according to one of claims 1 or 2 wherein the first part (2a, 13a) being assembled to the second part (2b, 13b) along at least one surface (6, 6 '). , 14, 15), the joining agent opens, after its migration through the first part (2a, 13a), at said assembly surface (6, 6 ', 14, 15). 4- assembly method according to one of claims 1 to 3 wherein the first part (2a, 13a) comprising at least a first face (9) and a second face (10), which is intended to be assembled at the second piece (2b, 13b), and means (8, 18), for example orifices (8, 18), for passing the assembling agent from the first face (2a, 13a) to the second face (2b, 13b), the bonding agent is applied to the first face (2a, 13a). 5. Assembly method according to claim 4 wherein, the first face (9) of the first piece (2a, 13a) being assembled to a third piece (4, 13b), the assembling agent migrates for part only from the first face (9) to the second face (10). 6- assembly method according to one of claims 1 to 5 wherein, once the parts (2a, 13a), (2b, 13b) fixed, the first face (9) is intended to be in contact with a first fluid and the second face (10) is intended to be in contact with a second fluid. 7- The assembly method according to claim 6, wherein the parts are plates (2, 13) arranged to form channels (3) for circulating fluids in a heat exchanger (1, 12). 8- piece intended to be assembled by soldering to a second piece with a fastening agent applied to it, said part comprising means (8, 18) for passage of the assembling agent for its migration through it for its assembly to the second piece. 9- part according to claim 8, comprising at least a first face (9) and a second face (10), which is intended to be assembled to the second piece (2b, 13b), and means (8, 18), for example, openings (8, 18) for passing the assembly agent from the first face (2a, 13a) to the second face (2b, 13b). 10- part according to one of claims 8 or 9, intended to be assembled to the second part (2b, 13b) along at least one surface (6, 6 ', 14, 15) assembly, wherein the means (8, 18) for passing the fastening agent open on the joining surface (6, 6 ', 14, 15). 11- part according to claim 10 wherein the part having surfaces (6, 6 ') of assembly to the second part symmetrical relative to each other with respect to an axis (A), the second part being similar to the first piece and intended to be assembled vis-à-vis, the means (8, 18) for the passage of the assembly agent are distributed asymmetrically with respect to said axis (A). 12- part according to one of claims 8 to 11, which is a plate (2, 13) of a heat exchanger, having surfaces (6, 6 ', 14, 15) for fixing by brazing to another plate, at which are formed orifices (8, 18) for the passage of a flow of brazing. 13- heat exchanger comprising a plurality of plates such as that of claim 12.