The invention relates to heat exchangers and particularly to plate heat exchangers. In particular, the invention will be applicable in the field of thermal systems for motor vehicles.

A plate heat exchanger comprises a plurality of plates disposed parallel to each other and spaced apart so as to together alternately delimit a first series of ducts for a first fluid and a second series of ducts for a second fluid. The two fluids are thus in contact, by means of the plates, without mixing together and exchange calories from the hottest fluid to the coldest fluid. The plate heat exchanger can be used to exchange calories between two liquids, a liquid and a gas and even between two gases. It is also known for one or more corrugations to be formed on the faces of the plates so that the fluids undergo a turbulent flow in order to maximise the thermal transfer.

A motor vehicle comprises at least one thermal system, such as a heating or air- conditioning system. Such a system normally comprises at least one exchanger that can be a plate exchanger.

One of the main challenges faced by the motor industry involves reducing the energy consumption of a vehicle. Thus, improving the efficiency of the various systems of the vehicle, particularly the thermal systems, is continuously researched.

Thus, an aim of the invention is to provide a heat exchanger in which heat transfers are more efficient.

To this end, a heat exchanger is provided according to the invention that comprises a plurality of plates together alternately delimiting a first series of ducts for a first fluid and a second series of ducts for a second fluid, characterised in that the first series of ducts comprises means for dividing the first fluid flowing therein into at least two distinct branches that meet at their ends and for causing the first fluid flowing in each branch to undergo a change of direction in a main plane of the first series of ducts.

Thus, by dividing the first fluid into two branches that are caused to undergo a change of direction, the turbulent nature of the flow of these two branches is enhanced. Furthermore, the two branches can be in close contact with the second fluid. Each branch is thus surrounded by the second fluid. Therefore, the thermal transfer between the first fluid and the second fluid is more efficient.

Advantageously, the means for dividing the first fluid are adapted to cause the first fluid flowing in each branch to undergo at least one change of direction in a direction normal to the main plane of the first series of ducts.

Therefore, the first fluid approaches the second fluid, which allows the efficiency of the thermal transfer between the first and the second fluid to be enhanced.

Preferably, the means for dividing the first fluid are adapted to cause the first fluid flowing in each branch to undergo a change of direction in the main plane and in the direction normal to the main plane of the first series of ducts in respectively the same zone of each branch. Therefore, the flow of the first fluid is even more turbulent.

According to one embodiment, the means for dividing the first fluid are adapted to cause the first fluid flowing in each branch to undergo at least two changes of direction in the main plane of the first series of ducts.

Therefore, the thermal transfer between the first fluid and the second fluid is even more efficient.

Advantageously, the means for dividing the first fluid are adapted so that at least one of the two branches comprises a plurality of elementary patterns, preferably the elementary pattern is in the shape of an "F" or a "C".

These patterns allow the flow of the first fluid to be provided with an even more turbulent nature.

Preferably, the means for dividing the first fluid are adapted so that the two branches comprise a plurality of elementary patterns, preferably the two branches comprise the same elementary pattern.

Therefore, the heat exchanger is easier to manufacture and its thermal performance is simpler to model.

According to one embodiment, the means for dividing the first fluid are adapted so that the two branches are symmetrically disposed relative to a plane of symmetry, which is preferably perpendicular to the main plane of the first series of ducts.

Advantageously, the means for dividing the first fluid comprise a plurality of grooves supported by internal walls of the ducts of the first series of ducts.

Preferably, the second series of ducts comprises means for ensuring that the second fluid occupies a volume at least partly having a shape that matches a volume occupied by the first fluid.

Therefore, the thermal transfer between the first and the second fluid is improved.

According to one embodiment, the means for ensuring that the second fluid occupies a volume at least partly having a shape that matches a volume occupied by the first fluid comprise a plurality of ribs.

Advantageously, at least one rib of the second series of ducts forms a groove of the first series of ducts.

Thus, the heat exchanger is lighter.

Preferably, at least one rib of the plurality of ribs is in the shape of an "F" or a "C".

Therefore, the heat exchanger is simpler to manufacture.

According to one embodiment, the means for ensuring that the second fluid occupies a volume at least partly having a shape that matches a volume occupied by the first fluid comprise a plurality of deflectors. Advantageously, the means for ensuring that the second fluid occupies a volume at least partly having a shape that matches a volume occupied by the first fluid comprise a component dividing the second fluid into two branches that meet at one of their ends.

The invention also provides for a thermal system for a motor vehicle comprising a heat exchanger as previously described. It is to be noted that the thermal system particularly can be an air-conditioning system or a heating system of the motor vehicle.

Of course, the various features, variations and/or embodiments of the invention can be associated with each other according to various combinations insofar as they are not incompatible with or exclusive of each other.

The invention will be better understood, and further features and advantages will become more clearly apparent, upon reading the following detailed description of two embodiments, which are provided by way of an illustration, with reference to the following perspective figures:

- figure 1 is an exploded view of a heat exchanger according to a first embodiment of the invention;

figures 2 to 5 show plates of the heat exchanger;

figures 6 to 8 show components of the heat exchanger;

figures 9 and 10 show volumes occupied by the first and second fluids in the heat exchanger; and

figures 1 1 A and 1 1 B are views of a branch of a first fluid flowing in the heat exchanger according to variations of the first embodiment;

figures 12 and 13 show plates of an exchanger according to a second embodiment of the invention; and

- figures 14 and 15 show volumes occupied by the first and second fluids in the heat exchanger according to the second embodiment.

First embodiment Figure 1 shows a heat exchanger 10 according to a first embodiment of the invention.

The heat exchanger 10 is intended to form part of a thermal system, such as an air- conditioning or heating system of a motor vehicle.

The heat exchanger 10 comprises four plates successively disposed one under the other in a direction (Z) : an upper closure plate 12, an upper intermediate plate 14, a lower intermediate plate 16 and a lower closure plate 18. In order to simplify the description of the heat exchanger 10, said exchanger comprises a single upper intermediate plate 14 and a single lower intermediate plate 16. It is to be noted that, according to the invention, the heat exchanger 10 always comprises an upper closure plate 12 and a lower closure plate 18. However, it can comprise an identical and variable number of upper intermediate 12 and lower intermediate 16 plates. Plates of the heat exchanger 10

The shape of the four plates 12, 14, 16 and 18 is generally flat and they extend in a main plane (XY) perpendicular to the direction (Z) for stacking the plates one on top of the other. The main plane (XY) comprises a longitudinal direction (X) and a transverse direction (Y) for the four plates 12, 14, 16 and 18. Furthermore, the four plates 12, 14, 16 and 18 are connected to each other via their peripheral edges, relative to the main plane (XY), in a sealed manner. This seal can be obtained by any means and particularly using a brazing method.

As will be described in further detail hereafter, when the heat exchanger 10 is assembled, a free space between the upper closure plate 12 and the upper intermediate plate 14 defines a first duct 20. Similarly, a free space between the upper intermediate plate 14 and the lower intermediate plate 16 defines a second duct 22. Finally, a free space between the lower intermediate plate 16 and the lower closure plate 18 defines a third duct 24.

The first 20 and third 24 ducts form a first series of ducts and the third duct 24 forms a second series of ducts. The first and third ducts 20, 24 are intended to receive a first fluid and the second duct 22 is intended to receive a second fluid. Thus, if there are N upper intermediate plates 14 and N lower intermediate plates 16, the heat exchanger 10 comprises a first series of N+1 ducts, intended to receive the first fluid, and a second series of N ducts, intended to receive the second fluid. The ducts of the first series and the ducts of the second series are alternately disposed one on top of the other.

In general, the heat exchanger 10 comprises a plurality of plates that together alternately delimit a first series of ducts for the first fluid and a second series of ducts for the second fluid. The first and second fluids can be, in an undifferentiated manner, two liquids, two gases or a liquid and a gas. The first fluid can be hotter than the second fluid or vice versa.

In figure 1 , the plates 12, 14, 16 and 18 are shown in a simplified manner to avoid overcomplicating the figure. Therefore, they do not include, on their main surfaces, the grooves and ribs that are shown in figures 2 to 5 and that will be described hereafter.

The upper closure plate 12 is shown in figures 1 and 2. In figure 2, the upper closure plate 12 is shown in an opposite position, in the direction (Z), to that shown in figure 1 . Thus, the direction (Z) points downwards in figure 2. An upper surface, in the direction (Z), of the upper closure plate 12 is smooth, unlike a lower surface, as will be described in detail hereafter. Furthermore, the upper closure plate 12 comprises, at a first longitudinal end, a through hole 26 that forms a fluid inlet and a through hole 28 that forms a fluid outlet for the first fluid. These two through holes 26 and 28 are aligned in the transverse direction (Y). Similarly, the upper closure plate 12 comprises, at a second longitudinal end opposite the first end, a through hole 30 that forms a fluid inlet and a through hole 32 that forms a fluid outlet for the second fluid. These two through holes 30 and 32 are also aligned in the transverse direction (Y). However, the through hole 26 that forms an inlet for the first fluid and the through hole 32 that forms a fluid outlet for the second fluid are aligned in the longitudinal direction (X). The same is the case for the through holes 26 and 32.

The upper intermediate plate 14 is shown in figures 1 and 3. It comprises four holes: 26A, 28A, 30A and 32A that are respectively facing the holes 26, 28, 30 and 32. Similarly, the lower intermediate plate 16 comprises four holes 26B, 28B, 30B and 32B respectively facing the holes 26A, 28A, 30A and 32A. Thus, in the direction (Z), the holes 26, 26A and 26B that are respectively arranged in the upper closure plate 12, the upper intermediate plate 14 and the lower intermediate plate 16 are aligned. The same is the case for the holes 28, 28A, 28B, the holes 30, 30A and 30B and the holes 32, 32A and 32B. However, the lower closure plate 18 does not comprise any through holes.

As can be particularly seen in figure 1 , the outlines of the holes 30A and 32A of the upper intermediate plate 14 are shaped so as to be in contact with the outlines of the holes 30 and 32 of the upper closure plate 12. Similarly, the holes 30B and 32B of the lower intermediate plate 16 are shaped so as to be in contact with the lower closure plate 18. Furthermore, the outlines of the holes 26A and 28A of the upper intermediate plate 14 are shaped to be in contact with the outlines of the holes 26B and 28B of the lower intermediate plate 16, but so as not to be in contact with the outlines of the holes 26 and 28 of the upper closure plate 12 and with the lower closure plate 18. All the aforementioned points of contact are sealed. This seal can be obtained by any means, for example, with a seal or using a brazing method.

Thus, when the first fluid is introduced into the heat exchanger 10 via the hole 26 of the upper closure plate 12, it spreads into the first 20 and third 24 ducts, then leaves the heat exchanger 10 through the orifice 28 of the upper closure plate 12. When the second fluid is introduced into the heat exchanger 10 via the orifice 30 of the upper closure plate 12, it spreads into the second duct 22 and leaves the heat exchanger 10 through the orifice 32 of the upper closure plate 12.

First 20, second 22 and third 24 ducts

The first 20, second 22 and third 24 ducts will now be described in further detail. The first duct 20 is delimited by the upper closure plate 12 and by the upper intermediate plate 14. In the direction (Z), a lower surface of the upper closure plate 12 faces an upper surface of the upper intermediate plate 14. As can be seen in figure 2, the thickness of the upper closure plate 12, at its longitudinal end having the holes 30, 32, is slightly greater than that of a main portion of the upper closure plate 12. A boundary between this longitudinal end and this main portion is formed by a shoulder 21 that extends in the transverse direction (Y). Thus, the first and second fluids do not mix.

As can be particularly seen in figures 2 and 3, the two surfaces facing these two plates 12 and 14 comprise a plurality of "F"-shaped grooves 34, 36, respectively. A longitudinal direction of these grooves 34, 36 is parallel to the longitudinal direction (X) of the plates 12, 14, 16, 18. Similarly, a transverse direction of the grooves 34, 36 is parallel to the transverse direction (Y) of the plates 12, 14, 16, 18.

The grooves 34 of the upper closure plate 12 are evenly disposed in the longitudinal direction (X), between the longitudinal ends respectively having the holes 26, 28 and 30, 32. However, in the transverse direction (Y), the grooves 34 are symmetrically disposed relative to an axis of symmetry (X1 ) that is parallel to the longitudinal direction (X) and that passes between the holes 26 and 28, on the one hand, and the holes 30 and 32, on the other hand. The same is the case for the grooves 36 of the upper intermediate plate 14. It is also to be noted that the axis (X1 ) and the direction (Z) form a plane of symmetry (X1 Z) for the heat exchanger 10. It is to be noted that this plane of symmetry is perpendicular to the main plane (XY).

Furthermore, as can be seen in figures 2 and 3, when the upper closure plate 12 and the upper intermediate plate 14 are facing each other, the opposing grooves 34 and 36 are disposed so that their respective "F"-shapes are oriented in opposite directions and mirror- wise. Thus, an "F"-shaped groove 34 faces an "d"-shaped groove 36, and vice versa. Furthermore, the longitudinal branches of the two "F" shapes are facing each other. Consequently, the transverse branches of the two respective "F" shapes of the grooves 34 and 36 are not facing each other and are symmetrically disposed mirror-wise.

The grooves 34, 36 define a free space for receiving the first fluid. However, between two pairs of grooves 34, 36 disposed side-by-side in the transverse direction (Y), the facing surfaces of the upper closure plate 12 and the upper intermediate plate 14 are in contact so that no free space remains in which the first fluid could flow.

The second duct 22 is delimited by the upper intermediate plate 14 and the lower intermediate plate 16. In the direction (Z), a lower surface of the upper intermediate plate 14 faces an upper surface of the lower intermediate plate 16. As can be seen in figure 4, the upper surface of the lower intermediate plate 16 has a plurality of "F"-shaped ribs 38. Furthermore, the lower surface of the upper intermediate plate 14 also has a plurality of "F"- shaped ribs. The plurality of "F"-shaped ribs forms the plurality of grooves 34 for the upper surface of the upper intermediate plate 14.

Indeed, the flat portion of the upper intermediate plate 14 is 0.4 millimetres thick, for example, whereas the depth of the grooves 34 or ribs 38 can be 1 .25 millimetres. Thus, a groove 34 for the upper surface of the upper intermediate plate 14 is a rib 38 for the lower surface of this plate 14.

Thus, as previously described, as can be seen by juxtaposing figures 3 and 4, when the upper intermediate plate 14 and the lower intermediate plate 16 are facing each other, the respective ribs that are facing each other are disposed so that their respective "F" shapes are oriented in opposite directions and mirror-wise. Thus, an "F"-shaped rib of the upper intermediate plate 14 faces an "d"-shaped rib 38 of the lower intermediate plate 16, and vice versa. Furthermore, the longitudinal branches of the two "F" shapes are facing each other. Consequently, the two transverse branches of the two respective "F" shapes of the ribs 38 and those on the upper intermediate plate 14 are not facing each other and are symmetrically disposed mirror-wise.

Furthermore, as can be seen in figures 1 and 6 to 8, the second duct 22 comprises a separating component 40, a first series of deflectors 42 and a second series of deflectors 44.

The separating component 40, shown in figure 6, is longilineal and extends along the axis of symmetry (X1 ) and its dimensions are adapted to be in contact with the opposite surfaces of the upper intermediate plate 14 and of the lower intermediate plate 16. Furthermore, the lower intermediate plate 16 comprises a matching shape 40A allowing a longitudinal end of the separating component 40 to be accommodated.

The first series of deflectors 42, shown in figure 7, comprises a plurality of longilineal deflectors 42A, which extend in the longitudinal direction (X). Each deflector 42A comprises, in the longitudinal direction (X), a plurality of projecting portions 42B, 42C, that extend slantwise in the main plane (XY). The portions 42B and 42C are disposed at different heights, in the direction (Z), and extend slantwise in opposite directions.

Similarly, the second series of deflectors 44, shown in figure 8, comprises a plurality of longilineal deflectors 44A, which extend in the longitudinal direction (X). Each deflector 44A comprises, in the longitudinal direction (X), a plurality of projecting portions 44B, 44C, that extend slantwise. The portions 44B and 44C are disposed at different heights, in the direction (Z), and extend slantwise in opposite directions.

Furthermore, as can be seen in figure 1 , the first and second series 42, 44 of deflectors are disposed either side of the separating component 40, symmetrically relative to the plane of symmetry (X1 Z) of the heat exchanger 10.

The third duct 24 is delimited by the lower intermediate plate 16 and the lower closure plate 18. As previously described, the lower surface, in the direction (Z), of the upper intermediate plate 14 comprises a plurality of "F"-shaped grooves that are ribs 38 for the upper surface of this lower intermediate plate 16. Similarly, the upper surface, in the direction (Z), of the lower closure plate 18 comprises a plurality of "F"-shaped ribs 46 disposed in a similar manner to those of the upper surface of the upper intermediate plate 14. Thus, the first 20 and third 24 ducts have substantially similar shapes.

Flow of the first and second fluids

The flow of the first and second fluids in the first 20, second 22 and third 24 ducts will now be described in further detail, particularly with reference to figures 9 and 10.

Figure 9 shows a volume occupied by the first fluid 48 in the third duct 24. The arrows show the direction of circulation of this first fluid 48. Its shape in the first duct 20 is substantially identical. Thus, the description relating to the volume occupied by the first fluid 48 is valid for the volume occupied in the first duct 20.

The first fluid 48 flowing in the third duct 24 occupies the volume particularly defined by the grooves 46 of the lower closure plate 18 and the grooves of the lower intermediate plate 16. Furthermore, as previously indicated, between two pairs of grooves 34, 36 disposed side- by-side in the transverse direction (Y), the surfaces facing the upper closure 12 and the upper intermediate 14 plates are in contact.

Thus, the first fluid divides into a plurality of pairs of distinct branches 48A, 48B that are evenly distributed in the transverse direction (Y) and flow in the longitudinal direction (X). The branches 48A, 48B of a pair of branches are symmetrically disposed relative to the plane of symmetry (X1 Z) of the heat exchanger 10. Furthermore, all the branches 48A, 48B meet at their longitudinal ends.

Thus, the first fluid 48 that flows in the aforementioned grooves undergoes at least two changes of direction in the main plane (XY), namely at least for reaching the two transverse branches of the "F" shape, and at least one change of direction in the direction (Z), namely at least for occupying the volume defined by two ribs of the facing lower intermediate plate 16 and lower closure plate 18. Thus, each branch 48A, 48B of the first fluid 48 undergoes the changes of direction in the main plane (XY) and in the direction (Z) normal to the main plane (XY) in the same zone, namely between two "F"-shaped grooves.

Consequently, the first and third ducts 20 and 24 that form the first series of ducts for the first fluid 48 comprise means for dividing the first fluid 48 flowing therein into at least two distinct branches, which meet at their ends. Furthermore, these means are adapted to cause the first fluid 48 flowing therein to undergo at least two changes of direction in the main plane (XY) of the first series of ducts and at least one change of direction in the direction (Z) normal to the main plane (XY). Furthermore, these means are adapted so that each branch 48A, 48B of the first fluid 48 comprises a plurality of elementary patterns that are identical for each branch 48A, 48B, which in this case are an "F"-shape, as shown in figure 10. These means particularly comprise the grooves 34, 36 and 46 supported by the internal walls of the first 20 and the third 24 ducts delimited by the upper closure plate 12, the upper intermediate plate 14, the lower intermediate plate 16 and the lower closure plate 18.

Of course, it is to be noted that an upper surface, in the direction (Z), of the first fluid 48 has an elementary "F"-shaped pattern in two orientations, namely those of the elementary patterns of the branches 48A and those of the elementary patterns of the branches 48B. Furthermore, a lower surface, in the direction (Z), of the first fluid 48 has an "F"-shaped elementary pattern in two other orientations due to the fact that two facing grooves are oriented mirror-wise, as previously described.

Figure 1 1 shows a volume occupied by the second fluid 50 in the second duct 22. The arrows show the direction of circulation of this first fluid 50.

The separating component 40 divides the second fluid 50 into two branches 50A, 50B, which meet at their longitudinal end opposite the holes 30A, 32A. Furthermore, the shape of the second fluid 50 flowing in the second duct 22 matches that of the volume occupied by the first fluid 48. Indeed, the ribs 38 supported by the surfaces facing the upper intermediate plate 14 and the lower intermediate plate 16, which also form grooves for the first 20 and third 24 ducts, force the second fluid 50 to follow a path complementary to the path followed by the first fluid 48. Furthermore, the first 42 and second 44 series of deflectors, and particularly the portions 42B, 42C and 44B, 44C, direct the second fluid 50 towards the ribs 38 of the second duct 22.

Thus, the second duct 22 comprises means for ensuring that the second fluid 50 occupies a volume at least partly having a shape that matches the volume occupied by the first fluid 48, and particularly a shape matching the branches 48A, 48B of the first fluid 48. These means particularly comprise the separating component 40, the first 42 and second 44 series of deflectors and the ribs 38 supported by the upper intermediate 14 and the lower intermediate 16 plates.

Manufacturing method

A method for manufacturing the heat exchanger 10 will now be described.

The method comprises at least one step of stamping upper closure plates 12, an upper intermediate plate 14, a lower intermediate plate 16 and a lower closure plate 18 so as to form the ribs and grooves on each of these plates.

The method further comprises at least one step of brazing the peripheral edges, in the main plane (XY), of the four plates 12, 14, 16 and 18 so as to form the first 20, second 22 and third 24 ducts.

The shape of the branches 48A, 48B of the first fluid 48 is not a limiting feature of the invention. To this end, figures 1 1 A and 1 1 B show possible shapes of the branches 48A, 48B. Figure 1 1 A shows a branch 48A comprising a "C"-shaped elementary pattern. Figure 12A shows a branch 48A comprising an "X"-shaped elementary pattern. Second embodiment

A second embodiment of the invention will now be described with reference to figures 12 to 14. Only differences with the first embodiment will be described.

A basic difference between the heat exchanger according to this embodiment and the heat exchanger 10 according to the first embodiment is the fact that the volumes occupied by the first 148 and second 150 fluids, shown in figures 14 and 15, in the first series of ducts and the second series of ducts partly have shapes as described in figures 9 and 10.

Plates of the heat exchanger

Figure 12 shows an upper intermediate plate 1 14 of the heat exchanger according to the second embodiment. The upper intermediate plate 1 14 comprises a first portion 1 14A and a second portion 1 14B. The first 1 14A and second 1 14B portions are disposed one after the other in the longitudinal direction (X). Thus, a longitudinal end 1 10 of the first portion 1 14A forms a longitudinal end for the upper intermediate plate 1 14. A longitudinal end 1 12 of the second portion 1 14B forms another longitudinal end for the upper intermediate plate 1 14. However, a longitudinal end 1 13 of the first portion 1 14A opposite the longitudinal end 1 10 is in direct contact with a longitudinal end 1 15 of the second portion 1 14B opposite the longitudinal end 1 12.

On its upper face, in the vertical direction (Z), the first portion 1 14A comprises a plurality of "F"-shaped ribs 136 that have a similar function to the previously described grooves 34. Thus, the first portion 1 14A has a substantially identical shape to the upper face, in the vertical direction (Z), of the lower intermediate plate 16. It is also to be noted that for the lower face, in the vertical direction (Z), the "F"-shaped ribs 136 form grooves. The "F"- shaped ribs 136 are evenly disposed one after the other in the longitudinal direction (X) so as to form, in this direction, rows of "F" shapes that are side-by-side in the transverse direction (Y).

Furthermore, the first portion 1 14A comprises, at its longitudinal end 1 10, two through holes 126A, 128A each disposed at a transverse end. The longitudinal end 1 13 comprises a hole 132A that is aligned, in the longitudinal direction (X), with the hole 126A. The function of these holes will be described hereafter.

The upper face of the second portion 1 14B comprises a plurality of ribs 136A and of grooves 136B that extend linearly as a diagonal in the plane (XY). With reference to the plane (XZ), the ribs 136A are disposed mirror-wise relative to the grooves 136B. Furthermore, the second portion 1 14B comprises two through holes 130A and 132C disposed at the longitudinal end 1 12. Furthermore, the two holes 130A and 132C are disposed at two opposite transverse ends. The second portion 1 14B also comprises a through hole 133A disposed at the longitudinal end 1 15. The hole 133A is aligned in the longitudinal direction (X) with the holes 132C, 132A and 126A. Furthermore, the hole 130A is aligned, in the longitudinal direction (X), with the hole 128A. Likewise, the function of these holes will be described hereafter.

Figure 13 shows a lower intermediate plate 1 16 of the heat exchanger according to the second embodiment.

Like the upper intermediate plate 1 14, the lower intermediate plate 1 16 comprises a first portion 1 16A and a second portion 1 16B. The first 1 16A and second 1 16B portions are disposed one after the other in the longitudinal direction (X). Thus, a longitudinal end 1 10A of the first portion 1 16A forms a longitudinal end for the lower intermediate plate 1 16. A longitudinal end 1 12A of the second portion 1 16B forms another longitudinal end for the lower intermediate plate 1 16. However, a longitudinal end 1 13A of the first portion 1 16A opposite the longitudinal end 1 1 OA is in direct contact with a longitudinal end 1 15A of the second portion 1 16B, opposite the longitudinal end 1 12A.

For the upper face, in the vertical direction (Z), the first portion 1 16A comprises a plurality of "F"-shaped grooves 138. As for the upper intermediate plate 1 14, the "F"-shaped grooves 138 are evenly disposed one after the other in the longitudinal direction (X) so as to form, in this direction, rows of "F" shapes that are side-by-side in the transverse direction (Y).

However, as can be seen by comparing figures 12 and 13, the respective "F" shapes facing a rib 136 and a groove 138 are oriented in the opposite direction in the longitudinal (X) and transverse (Y) directions. Thus, an "F"-shaped rib 136 faces an "d"-shaped groove 138.

Furthermore, between two pairs of ribs 136 and of grooves 138 disposed side-by-side in the transverse direction (Y), the surfaces facing the upper intermediate plate 1 14 and the lower intermediate plate 1 16 are in contact.

Moreover, the first portion 1 16A comprises two through holes 126B, 128B disposed at the longitudinal end 1 10A. The two holes 126B, 128B respectively face the holes 126A, 128A of the upper intermediate plate 1 14. Similarly, the first portion 1 16A comprises a third hole 132B that faces the hole 133A.

The upper face of the second portion 1 16B comprises a plurality of grooves 138A and ribs 138B that diagonally extend in the plane (XY). With reference to the plane (XZ), the grooves 138A are disposed mirror-wise relative to the grooves 138B. Furthermore, the grooves 138A are facing the ribs 136A and the ribs 138B are facing the grooves 136B. Moreover, a facing groove 138A and rib 136A extend in different directions in order to form, when they are superposed, an "X"-shaped cross. The same is the case for a groove 138A facing a rib 136A. Furthermore, the second portion 1 16B comprises three through holes 133B, 132D and 130B that are respectively facing the holes 133A, 132C and 130A.

The function of the holes 126A, 128A, 132A, 133A, 130A, 132C, 126B, 128B, 132B, 133B, 130B and 132D will now be described.

The outlines of the holes 126A, 132A, 133A and 132C of the upper intermediate plate 1 14 are in contact with the upper closure plate.

Furthermore, the outlines of the holes 128A and 130A of the upper intermediate plate 1 14 are respectively in contact with the outlines of the holes 128B and 130B of the lower intermediate plate 1 16.

Moreover, the outlines of the holes 126B, 132B, 133B and 132D of the lower intermediate plate 1 16 are in contact with the lower closure plate. First, second and third ducts

A space between the upper closure plate and the upper surface of the upper intermediate plate 1 14 forms a first duct. Similarly, a space between the lower surface, relative to the vertical direction (Z), of the lower intermediate plate 1 16 and the lower closure plate forms a third duct. These two ducts receive a second fluid.

Furthermore, a space between the lower surface, relative to the vertical direction (Z), of the upper intermediate plate 1 14 and the upper surface of the lower intermediate plate 1 16 forms a second duct for receiving the first fluid. In this second embodiment, the second duct does not comprise the separating component 40 and the first 42 and second 44 series of deflectors.

Thus, the second duct forms a first series of ducts for receiving the first fluid and the first and third ducts form a second series of ducts for receiving the second fluid.

It is to be noted that, relative to the first embodiment, the designations of the first and second series of ducts have been reversed so as to maintain consistency with respect to the vocabulary of the set of claims.

Flow of the first and second fluids

The flow of the first and second fluids will now be described in further detail.

Figure 14 shows a volume occupied by the first fluid 148 in the second duct.

The first fluid 148 enters the heat exchanger via a hole of the facing upper closure plate, the outlines of which hole are in contact with the hole 126A of the upper intermediate plate 1 14. The first fluid 148 reaches the second duct by passing through the hole 126A. It spreads in the second duct in a space between the first respective portions 1 14A, 1 16A of the upper 1 14 and lower 1 16 intermediate plates. Subsequently, it leaves this space by passing through the hole 132A of the upper intermediate plate 1 14 and a hole of the upper closure plate facing the hole 132A. Then, the first fluid 148 returns to the second duct by passing through the hole 133A. It spreads in the second duct in a space between the second respective portions 1 14B, 1 16B of the upper 1 14 and lower 1 16 intermediate plates. Subsequently, it leaves this space by passing through the hole 132C of the upper intermediate plate 1 14 and a hole of the facing upper closure plate.

Thus, the first fluid 148 comprises two distinct portions 148A and 148B in the second duct.

The portion 148A of the first fluid 148 is disposed between the first respective portions 1 14A, 1 16A of the upper 1 14 and lower 1 16 intermediate plates. The portion 148B of the first fluid 148 is disposed between the second respective portions 1 14B, 1 16B of the upper 1 14 and lower 1 16 intermediate plates.

Furthermore, the portion 148A of the first fluid 148 divides into a plurality of pairs of distinct branches 149 evenly distributed in the transverse direction (Y) and flowing in the longitudinal direction (X). All the branches 149 meet at their longitudinal ends. The shape of the portion 148A of the first fluid 148 is substantially similar to that of the first fluid 48, as shown in figure 9. A difference resides in the fact that the portion 148A of the first fluid 148 does not include the plane (XZ) as a plane of symmetry.

Figure 15 shows a volume occupied by the second fluid 150 in the first duct. The volume occupied in the third duct is substantially identical.

Thus, the second fluid 150 enters the heat exchanger via a hole in the upper closure plate that is facing the hole 128A of the upper intermediate plate 1 14. The second fluid 150 reaches the third duct by passing through the holes 128A and 128B that only form a single hole. Thus, the second fluid 150 fills the first and third ducts.

Furthermore, the second fluid 150 leaves the first and third ducts in order to leave the heat exchanger by passing through the holes 130B, 130A, which also only form a single hole, and a hole of the upper closure plate facing these two holes. The shape of the second fluid 150 thus matches that of the first fluid 148.

Of course, various modifications can be made to the invention without departing from the scope of the invention.

In particular, the fluid inlet and outlets can be disposed on the lower closure plate 18.

The first 48 and second 50 fluids can have different directions of circulation in the ducts 20, 22, 24.