Heat Exchanger Having A Reinforced Collector
Disclosed is a heat exchanger comprising a heat exchange body 2, at least one cover 4 and a manifold 3 connecting the cover 4 to the heat exchange body 2 with the aid of a crimping device that projects from the manifold 3 and is folded over the cover 4, the heat exchange body 2 comprising a plurality of tubes 6a, 6b that are able to channel a first fluid, the manifold 3 comprising a base plate 24 surrounded by an edge 13 for fixing the cover 4, wherein the base plate 24 and the fixing edge 13 delimit a housing 26 for receiving a heel 15 of the cover 4, the fixing edge 13 being formed by a double-thickness wall 16, one end 17 of which is fixed to at least one tube 6a, 6b.
The technical field of the present invention is that of heat exchangers which are configured to implement an exchange of heat between a first fluid and a second fluid and are more particularly intended to be installed in a motor vehicle. Such a heat exchanger is, for example, a charge air cooler.
A motor vehicle can conventionally be equipped with an internal combustion engine combined with a turbocharger. The latter increases the temperature of the intake gases, thereby impairing proper filling of the combustion chambers of the engine. For this reason, it is known to supplement this configuration with the addition of a heat exchanger, the function of which is to cool the intake gases before they enter these combustion chambers, thereby making it possible to increase the density of the intake gases and thus to improve the stoichiometric ratio in the combustion chambers.
Such a heat exchanger conventionally comprises a plurality of tubes through which the intake gases flow, the spaces between the tubes being for their part flowed through by a cooling fluid. At the inlet or at the outlet of this exchanger, the intake gases are channeled through a cover secured to a manifold, the latter being configured to receive, in a sealed manner, the end of each tube through which the intake gases enter.
New supercharging techniques are emerging. It is thus known to combine the internal combustion engine with two or three turbochargers. This combination is accompanied by an increase in the pressure and temperature of the intake gases. The mechanical stresses to which supercharger exchangers are subjected become extremely large, since the pressure of the intake gases can reach 4 bar. The heat exchangers that are currently known are thus not suitable for resisting such pressure or temperature levels, and leaks can arise in particular at the joint that connects the cover to the manifold.
Document US2003/0217838A1 discloses a solution for reinforcing a peripheral edge of the manifold. Although it improves the situation, such a solution is not suitable for air/air exchanger designs that are subjected to a high internal pressure and where a cover is held on the manifold by means of mechanical crimping. Fixing by crimping has a number of advantages, but it is more sensitive to the phenomena of deformation of the cover and thermal expansion, these phenomena being less problematic in the case of the cover being fixed to the manifold by welding. There is thus a need to improve the management of the sealing between the internal volume of the heat exchanger and its environment for heat exchangers having a crimped cover.
The aim of the present invention is thus to solve the above-described drawback mainly by reinforcing the peripheral edge of the manifold, the latter being very particularly designed to receive a cover and fix it by crimping. The invention proposes providing means for absorbing forces on a component of the heat exchange body, in particular on the tube or tubes through which the intake gases that are subjected to high pressure pass.
The subject of the invention is thus a heat exchanger comprising a heat exchange body, at least one cover and a manifold connecting the cover to the heat exchange body with the aid of a crimping device that projects from the manifold and is folded over the cover, the heat exchange body comprising a plurality of tubes that are able to channel a first fluid, the manifold comprising a base plate surrounded by an edge for fixing the cover, characterized in that the base plate and the fixing edge delimit a housing for receiving a heel of the cover, the fixing edge being formed by a double-thickness wall, one end of which is fixed to at least one constituent tube of the heat exchange body. The fixing of the end of the double-thickness wall to at least one tube thus ensures absorption of mechanical forces, this helping significantly to increase the mechanical strength of the fixing edge with respect to stresses generated by the pressure or the temperature of the first fluid that is able to flow inside the heat exchanger according to the invention.
It will be noted that the heat exchange body can also comprise a multiplicity of dissipation devices that are interposed between the tubes and are in contact with a second fluid that is able to pass through the heat exchange body.
According to a first feature of the invention, the end of the double-thickness wall is fixed to a plurality of tubes. The case in which the end extends along a longitudinal face of the exchanger is targeted here, the end then being brazed to a lateral wall of a plurality of tubes bordering the longitudinal face.
According to a second feature of the invention, a tube comprises two longitudinal walls that are joined together by two lateral walls, the fixing edge comprising a band transverse to the base plate and fixed to at least one of the lateral walls of at least one tube over a length of at least 1 mm.
According to another, alternative or supplementary feature of the invention the end is fixed to a longitudinal wall of an end tube of the heat exchange body.
One or the other of the abovementioned solutions makes it possible to provide a means for absorbing mechanical forces along the face in question of the exchanger, and advantageously on all the faces which delimit the heat exchange body.
According to a further feature of the invention, the heat exchange body is laterally terminated by a plate installed at a distance of at least 0.1 mm from the double-thickness wall, this distance being a minimum to avoid brazing between the two elements in question.
According to a further feature of the invention, a dissipation device is interposed between the plate and the end tube, the dissipation device being at a distance of at least 0.1 mm from the double-thickness wall, this distance being a minimum to avoid brazing between the two elements in question.
The two technical solutions presented above make it possible to thermally decouple the manifold from the plate and/or from the dissipation device, this affording the possibility of avoiding mechanical stresses as a result of differences in thermal expansion between the manifold in contact with the first fluid and the plate and/or dissipation device in contact with the second fluid.
The exchanger according to the invention may be configured such that a distance of at least 2 mm is provided between the base plate and the end of the double-thickness wall. Such a distance makes it possible to form a strut by means of the end brazed to the tube. A strut of this type opposes an opening phenomenon of the fixing edge under the effect of the pressure in the cover, this making it possible to increase the level of reliability of the sealing by crimping.
Advantageously, the base plate comprises at least one opening in which one end of a tube is housed, said opening being bordered by a collar turned toward the heat exchange body. Such an arrangement makes it possible to obtain a substantially flat face of the base plate that is turned toward the cover, thereby helping to improve the mechanical strength of the heat exchanger.
Such an exchanger may comprise a seal fitted in the receiving housing, at least between the heel of the cover and the fixing edge.
The double-thickness wall is formed by a first wall and a second wall brazed to the first wall. According to a first alternative, the first and second wall are produced from one and the same metal sheet and connected together by a fold. According to a second alternative, the second wall is separated beforehand from the first wall and then attached to the latter prior to a brazing step.
The double-thickness wall may comprise at least one corner at which a mechanical reinforcement device is formed. The latter avoids an increase, under the effect of the pressure, in the angular inclination formed between the two parts of the double-thickness wall which border the corner.
According to one exemplary embodiment, the mechanical reinforcement device is in particular a chamfer formed at the corner of the first wall. Alternatively, this mechanical reinforcement device is advantageously a fillet formed at the corner of the second wall.
It will be noted that this reinforcement device may also be formed by the combination of the chamfer and the fillet, formed on one or the other of the walls. Such an arrangement makes it possible to generate forms which combine in order to oppose the mechanical stresses to which the manifold is subjected.
The first wall may comprise a first strip forming a base of the housing and a first side wall laterally delimiting the housing, the first strip and the first side wall being connected by the chamfer.
According to a further feature of the invention, the second wall may comprise a second strip brazed to the first strip and a second side wall brazed to the first side wall, the second strip and the second side wall being connected by a fillet at a distance from the chamfer. The fillet and the chamfer form in this case the mechanical reinforcement device, and such a distance between this fillet and this chamfer helps significantly to increase the mechanical integrity of the fixing edge.
Advantageously, the end comprises a bend positioned such that one face of the second wall is brazed to the tube. Such an arrangement makes it possible to increase the fixing area, in particular for brazing, between the double-thickness wall and the tube or tubes, at the end.
According to one exemplary embodiment, the crimping device may comprise a plurality of crimping tabs projecting from the first wall, said crimping tabs being folded over the heel of the cover in the final manufactured state of the heat exchanger.
The invention can also cover a system for cooling intake gases of an internal combustion engine of a motor vehicle, comprising a heat exchanger incorporating any one of the above-described features, in which the first fluid is formed by the intake gases of the internal combustion engine while the second fluid is formed by a stream of air external to the vehicle.
One advantage of the invention lies in the possibility of increasing the mechanical strength of the manifold, in particular of its fixing edge, in a simple manner. The fixing of the end produces an additional point of contact with the tubes, thereby forming a means of taking up forces, the latter significantly limiting the deformations of the fixing edge when the heat exchanger is subjected to a high internal pressure and/or a high internal temperature. In this way, a heat exchanger provided with a manifold with a double-thickness wall, the end of this wall being secured to at least one tube that channels the first fluid, can resist high pressures and temperatures.
Further features, details and advantages of the invention will become more clearly apparent from reading the description given hereinbelow by way of illustration and with reference to the drawings, in which:
The heat exchanger 1 according to the invention is configured to implement an exchange of heat between a first fluid and a second fluid. In a particular manner, the heat exchanger is designed not only to channel a first gaseous fluid such as a charge air stream, but also to be passed through by a second gaseous fluid such as a stream of air surrounding the exchanger. Thus, the heat exchanger 1 can be an air/air exchanger installed in a motor vehicle, the second fluid being a stream of dynamic air set in motion by the movement of the vehicle or by a motor-fan unit mounted on the vehicle.
The heat exchanger 1 according to the invention comprises a heat exchange body 2 which forms the site of the heat exchange between the first fluid and the second fluid. Located at each end of the heat exchange body 2 there is a manifold 3 covered by a cover 4.
The manifold 3 distributes the first fluid through a plurality of constituent tubes 6 of the heat exchange body 2, this first fluid being channeled through the cover 4 to or from the manifold 3. The heat exchange body 2 also comprises a multiplicity of dissipation devices 7. Each of these is interposed between two adjacent tubes 6 so as to form a space between the tubes, the second fluid, that is to say the stream of dynamic air, flowing in said space.
According to one exemplary embodiment, a dissipation device is formed by an insert, in particular in the form of a zigzag, each peak of which is secured to two adjacent tubes. This insert may have louvers. This dissipation device 7 may also be formed by a substantially flat metal sheet on which a multiplicity of louvers are formed.
The cover 4 comprises at least one opening 5 through which the first fluid enters or exits the heat exchanger 1. The manifold 3 is thus on one side brazed to the heat exchange body 2 and on the other side secured to the cover 4 by a device 8 for crimping the manifold 3 to the cover 4. Such a crimping device 8 is formed overall by a set of crimping tabs that are folded over an edge of the cover, referred to as heel below.
The heat exchange body 2 has a rectangular section. It is thus delimited by an inlet face for the second fluid and by an outlet face for this second fluid, referred to as the first longitudinal face 9 and second longitudinal face 10, respectively, of the heat exchange body 2. The latter is also delimited by a first lateral face 11 and by a second lateral face 12 which are disposed between the first longitudinal face 9 and the second longitudinal face 10. The latter are perpendicular to the direction of movement of the second fluid, while the first lateral face 11 and the second lateral face 12 extend in planes parallel to this direction.
The heat exchange body 2 comprises the plurality of tubes 6 secured to the manifold 3 by brazing. These tubes are produced, for example, from a metal sheet folded on itself so as to delimit an internal volume in which the first fluid, in particular the charge air stream, flows.
A tube 6 is delimited by two parallel longitudinal walls that are joined by two lateral walls. The longitudinal walls of the tubes are parallel to at least one of the lateral faces 11 or 12 which border the heat exchange body 2. The lateral walls of the tubes thus extend in the plane of the first and/or second longitudinal face 9, 10 of the heat exchange body 2.
The longitudinal wall or walls of the tubes 6 extend in a plane OX-OY, while the lateral walls of the tubes 6, although having a rounded shape, extend generally in a plane OX-OZ.
It will be noted that the structure of each tube 6 is identical, the two tubes immediately adjacent to the lateral faces 11 and 12 of the heat exchange body 2 being referred to as end tubes 6a and 6b below.
A turbulator may be installed inside the internal volume of each tube 6. This turbulator (not shown) disrupts the flow of the first fluid in the tube 6 so as to maximize the transfer of heat between the first fluid and the walls delimiting the tube 6. This turbulator may also be fixed to the two longitudinal walls of the tube so as to increase the mechanical integrity of such a tube.
The heat exchange body 2 comprises its plurality of tubes 6, between which the heat dissipation device 7, for example an insert, is disposed. The first lateral face 11 of the heat exchange body 2 is formed by a plate 14, that is to say a metal sheet which is in particular rectilinear. Located between the end tube 6b and this plate 14 there is a dissipation device 7 brazed to the plate and to the longitudinal wall of the end tube 6b.
The edge 13 for fixing the cover receives a heel 15 of the cover 4, formed on a peripheral edge delimiting the opening of this cover 4. Such a heel has the shape of a shoulder produced by increasing the thickness of the cover in the region of this opening.
The fixing edge 13 is formed by a double-thickness wall 16, the latter extending all around the heat exchanger 1, that is to say along both lateral faces and both longitudinal faces that define the heat exchange body 2. However, the absence of double thickness of the fixing edge in the region of at least one corner, and advantageously of all the corners between the lateral faces and the longitudinal faces of the heat exchange body 2 will be noted.
The particular shape of this double-thickness wall will be addressed in detail with reference to
The double-thickness wall 16 comprises at least one end 17 fixed to at least one constituent tube 6, 6a, 6b of the heat exchange body 2. Such fixing can take place either only along one or more lateral faces 11, 12 delimiting the heat exchange body 2, or only along one or more longitudinal faces 9, 10 delimiting the heat exchange body 2, or along both one or more lateral and one or more longitudinal faces of the heat exchange body 2.
In the exemplary embodiment illustrated in
With regard to the first longitudinal face 9, the end 17 of the double-thickness wall 16 is brazed to the lateral wall 18 of at least one tube 6 and preferably to the lateral wall of each constituent tube 6 of the heat exchange body 2.
At the first lateral face 11, the end 17 of the double-thickness wall 16 is brazed to the longitudinal wall 19 of the end tube or tubes 6a, 6b of the heat exchange body 2. Such brazing is carried out on this longitudinal wall in the plane OX-OY illustrated in
The manifold 3 comprises a base plate 24 surrounded by the edge 13 for fixing the cover 4. The base plate 24 is provided with openings, having an elongate shape, which receive one end of each tube 6. These openings can be provided with a collar 25 which is oriented for example toward the heat exchange body 2 or toward the cover 4.
The fixing edge 13 forms a peripheral belt around the base plate 24, this fixing edge preferably being formed integrally from the material of the base plate 24.
According to the invention, this edge 13 for fixing the cover 4 is formed by the double-thickness wall 16, the latter ending at the end 17 at least partially fixed to one or more tubes, in particular to one and/or the other of the constituent end tubes 6a, 6b of the heat exchange body 2.
The term “double-thickness” means that the fixing edge 13 is reinforced by the provision of two thicknesses of walls pressed against one another. The double-thickness wall 16 is thus formed by a first wall 21 and by a second wall 22 immediately adjacent to the first wall 21, following the contours thereof. The second wall 22 is at least partially secured to the first wall 21 by a braze between these two walls.
According to the exemplary embodiment shown in this figure, the first wall 21 is also secured to the second wall 22 by means of a fold 23. In such a case, the first wall 21 and the second wall 22 are produced from one and the same metal sheet which has been folded through 180° at the fold 23 in order to press the second wall 22 against the first wall 21. Thus, the second wall 22 is considered to be formed integrally from the material of the first wall 21.
Alternatively, the second wall 22 may be a part previously separate from the first wall 21 and attached before being brazed to the latter, so as to form the double-thickness wall 16 once they have been secured together, in particular by brazing.
In order to simplify the way in which the manifold 3 is manufactured, a thickness of the double-thickness wall 16 is at least twice as large as a thickness of the base plate 24. In one particular embodiment, the thickness of the double-thickness wall 16 is strictly equal to twice the thickness of the base plate 24. The thickness of the double-thickness wall 16 is measured in the direction OX, while the thickness of the base plate 24 is measured in a direction OZ, these two directions being shown in this figure.
According to the exemplary embodiment in
The band 27 is in this case separated from the longitudinal wall 19 of the end tube 6a, 6b on account of the presence of a collar 25.
In addition to receiving the heel 15 of the cover 4, this housing 26 can receive a seal 35 that provides sealing between the first fluid and the surroundings of the heat exchanger according to the invention. This seal 35 thus bears against the heel 15, against the band 27 and against the first wall 21 in the region of the housing 26.
According to the exemplary embodiment in
Located between the first strip 28 and the first side wall 29 there is a mechanical reinforcement device of the double-thickness wall 16. According to one exemplary embodiment, the mechanical reinforcement device is in the form of a chamfer 30, that is to say a substantially flat edge that is inclined with respect to the first strip 28 and with respect to the first side wall 29. This chamfer 30 thus connects the first strip 28 to the first side wall 29, this chamfer being an element involved in the mechanical reinforcement of the edge 13 for fixing the cover 4.
The second wall 22 of the double-thickness wall 16 comprises a second strip 31 extended by a second side wall 32. The second strip 31 extends in a plane parallel to the plane of extension of the first strip 28, these two strips being secured together by a brazed connection.
The second side wall 32 extends in a plane parallel to the plane of extension of the first side wall 29 and is brazed to the latter.
The second strip 31 is joined to the second side wall 32 by a fillet 33, that is to say an edge with a rounded section. This fillet 33, as such, forms a second exemplary embodiment of the mechanical reinforcement device of the double-thickness wall 16.
This fillet 33 is opposite the chamfer 30 and is configured so as to be separated from the chamfer 30, such an arrangement helping to increase the mechanical strength of the double-thickness wall 16. The second strip 31 and the second side wall 32 are for example flat.
This combination of the chamfer 30 and the fillet 33 forms a third variant embodiment of the mechanical reinforcement means of the double-thickness wall 16.
It will thus be understood that this mechanical reinforcement device can be formed either only by the chamfer 30, or only by the fillet 33, or by the combination of this chamfer 30 with the fillet 33, such a combination also making it possible to increase the mechanical strength of the double-thickness wall 16.
In a general manner, this reinforcement means may also be formed as soon as the first wall 21 and the second wall 22 each have a corner, the corner formed on the first wall 21 having a different shape, in cross section, than the corner formed on the second wall 22, these two corners facing one another.
The end 17 of the double-thickness wall 16 is formed by an end part of the second strip 31. According to an exemplary embodiment that is not shown, it is one edge of the second strip 31 which is brazed to the end tube 6a, 6b.
In the example in
At the fold 23, the double-thickness wall 16 comprises a number of crimping tabs 20 formed by portions which extend the first wall 21. In this figure, these crimping tabs 20 are shown before being folded over the heel 15 of the cover 4. In the final assembly position, these crimping tabs are pressed against the heel 15 of the cover 4 so as to exert a compressive force against the seal 35.
The end 17 of the double-thickness wall 16 is fixed to the longitudinal wall 19 of the end tube 6a, 6b of the heat exchange body 2. On the other hand, the heat exchanger is designed such that the double-thickness wall 16 is not in contact with the plate 14 and/or with the dissipation device 7. To this end, the plate 14 is installed in the heat exchange body 2 so as to form a distance of at least 0.1 mm from the double-thickness wall 16. In the example in
Advantageously, the dissipation device 7 is interposed between the plate 14 and the end tube 6a, 6b. The dissipation device 7 is fixed in the heat exchange body 2 so as to maintain a separation distance D2 from the double-thickness wall 16, including its end 17, of at least 0.1 mm. This distance D2 is measured, for example, between a last peak of the dissipation device 7 and the second strip 31, or the edge of the end 17. Advantageously, the distance D2 is at most 10 mm.
The end of each tube 6 is connected to the base plate 24 by a braze provided in the region of the collar 25. The edge 13 for fixing the cover is in particular reinforced when a distance with the reference D3 is provided between the base plate 24 and the end 17 of the double-thickness wall 16 brazed to the end tube 6a, 6b. Such a distance is at least 2 mm. This distance D3 is measured, for example, between a face of the base plate turned toward the heat exchange body 2 and a plane passing through a face of the second wall 22 brazed to the first wall 21. Advantageously, the distance D3 is at most 6.5 mm.
The band 27 disposed perpendicularly to the base plate 24 is brazed to the lateral wall 18 delimiting at least one tube 6 of the heat exchange body 2. Advantageously, such brazing is carried out to the lateral wall of each tube 6, including the end tubes 6a, 6b.
This brazing is produced over a distance with the reference D4 which is at least 1 mm and at most 7.5 mm. This distance D4 is measured, for example, between an edge delimiting the opening of the tubes at the base plate 24 and a straight line passing through the base of the housing 26 delimited by the first constituent strip 28 of the first wall 21.
The end 17 of the double-thickness wall 16 is also fixed to the lateral wall 18 of at least one tube 6, in a similar manner to the solutions described with respect to
It will be noted that the heat exchange body 2 and the manifold 4 can be produced from an aluminum alloy. For its part, the cover 4 can be produced from an aluminum alloy or a synthetic material.
The above-described heat exchanger 1 can be incorporated into a system for cooling intake gases or exhaust gases of an internal combustion engine. In such a case, the first fluid is formed by the intake gases, in particular a charge air stream, while the second fluid is formed by an air stream, for example external to the vehicle which holds such a cooling system.
The heat exchanger 1 is thus designed such that the second fluid passes through the heat exchange body 2, dissipating the heat generated by the first fluid into the second fluid, by means of the tubes and the dissipation devices. The second fluid passes through the heat exchange body 2 in a direction perpendicular, or substantially perpendicular, to the direction of movement of the first fluid in the tubes 6.
Claims
1. A heat exchanger comprising a heat exchange body, at least one cover and a manifold connecting the cover to the heat exchange body with the aid of a crimping device that projects from the manifold and is folded over the cover, the heat exchange body comprising a plurality of tubes configured to channel a first fluid, the manifold comprising a base plate surrounded by an edge for fixing the cover, wherein the base plate and the fixing edge delimit a housing for receiving a heel of the cover, the fixing edge being formed by a double-thickness wall, one end of which is fixed to at least one tube.
2. The exchanger as claimed in claim 1, wherein the end of the double-thickness wall is fixed to a plurality of tubes.
3. The heat exchanger as claimed in claim 2, wherein a tube comprises two longitudinal walls that are joined together by two lateral walls, the fixing edge comprising a band transverse to the base plate and fixed to at least one of the lateral walls of at least one tube over a length of at least 1 mm.
4. The exchanger as claimed in claim 1, wherein the end is fixed to a longitudinal wall of an end tube of the heat exchange body.
5. The exchanger as claimed in claim 4, wherein the heat exchange body is laterally terminated by a plate installed at a distance of at least 0.1 mm from the double-thickness wall.
6. The exchanger as claimed in claim 5, wherein a dissipation device is interposed between the plate and the end tube, the dissipation device being at a distance of at least 0.1 mm from the double-thickness wall.
7. The exchanger as claimed in claim 6, wherein a distance of at least 2 mm is provided between the base plate and the end of the double-thickness wall.
8. The exchanger as claimed in claim 1, wherein the base plate comprises at least one opening in which one end of a tube is housed, said opening being bordered by a collar turned toward the heat exchange body.
9. The exchanger as claimed in claim 1, comprising a seal fitted in the receiving housing at least between the heel of the cover and the fixing edge.
10. The exchanger as claimed in claim 1, wherein the double-thickness wall is formed by a first wall and a second wall brazed to the first wall.
11. The exchanger as claimed in claim 10, wherein the double-thickness wall comprises at least one corner at which a mechanical reinforcement device is formed.
12. The exchanger as claimed in claim 11, wherein the mechanical reinforcement device is a chamfer formed at the corner of the first wall.
13. The exchanger as claimed in claim 11, wherein the mechanical reinforcement device is a fillet formed at the corner of the second wall, the fillet being formed opposite the chamfer.
14. The exchanger as claimed in claim 12, wherein the first wall comprises a first strip forming a base of the housing and a first side wall laterally delimiting the housing, the first strip and the first side wall being connected by the chamfer.
15. The exchanger as claimed in claim 14, wherein the second wall comprises a second strip brazed to the first strip and a second side wall brazed to the first side wall, the second strip and the second side wall being connected by a fillet at a distance from the chamfer.
16. The exchanger as claimed in claim 10, wherein the end comprises a bend positioned such that one face of the second wall is brazed to the tube.
17. The heat exchanger as claimed in claim 10, wherein the crimping device comprises a plurality of crimping tabs projecting from the first wall.
Type: Application
Filed: May 16, 2013
Publication Date: May 14, 2015
Inventor: Alan Day (Reims)
Application Number: 14/402,789
International Classification: F28F 9/02 (20060101); F28F 1/10 (20060101);
