FR3109210A1 - HEAT EXCHANGER, ESPECIALLY FOR MOTOR VEHICLES - Google Patents

Abstract

Heat exchanger, in particular for a motor vehicle, comprising a bundle (2) configured to allow heat exchange between a heat transfer fluid and a flow of air, said bundle (2) comprising tubes (4) for circulating the heat transfer fluid and fins (6) defining at least in part an exchange surface with the air, the fins (6) being crossed by said tubes (4) for circulating the heat transfer fluid, said tubes (4) extending between two sides (8) of the bundle, said bundle comprising two free edges (10) connecting said sides (8), said exchanger further comprising a longitudinal reinforcing element (30) disposed near one of the free edges (10) of the beam (2) and passing through at least one of said fins (6). Figure for the abstract: 1

Description

HEAT EXCHANGER, IN PARTICULAR FOR MOTOR VEHICLES

The invention relates to an exchanger, in particular for a motor vehicle. This is in particular a cooling radiator, intended to be positioned on the front of the vehicle, at the rear of the grille.

In this field, so-called mechanical type heat exchangers are known. Such exchangers comprise a beam configured to allow heat exchange between a heat transfer fluid and an air flow passing through the grille. Said bundle comprises heat transfer fluid circulation tubes and fins defining an exchange surface with the air. The fins are traversed by said heat transfer fluid circulation tubes, the fins being flat and oriented substantially perpendicular to said tubes. These exchangers also include header boxes made up of a header plate and a cover. The tubes open into the boxes through the collector plates.

Assembly is carried out as follows. The tubes are inserted into orifices provided in the fins and undergo a first radial expansion making it possible, by material deformation, to fix the fins to the tubes. The ends of the tubes are then inserted into the orifices provided in the collector plates and undergo a first flare to compress a seal located between said plates and the end of the tubes to seal the boxes. The ends of the tubes still undergo a second flare to block them against the collector plates. The collector boxes are then closed by fixing the lids on the collector plates.

Such exchangers are particularly advantageous because of their simplicity of manufacture as opposed to exchangers, known as brazed, in which the tubes, the fins, then in the form of corrugated inserts, and the collector plates, or even the covers, are assembled by brazing. , which requires the use of more complex materials and means of production.

However, in known mechanical exchangers, the end tubes of the bundle, that is to say the tubes located on either side of the bundle, can crack. This failure is particularly highlighted during mechanical endurance tests, in particular during tests, known as cycled pressure, during which the exchanger is subjected to low and high pressure cycles of the heat transfer fluid, in this case cooling liquid.

Under the effect of the stresses caused by these pressure cycles of the liquid flowing through them, the tubes of the exchanger swell. These successive swellings of the tubes bring about a mechanical deformation of the wall of the tubes.

It was noted by the applicant that, for the end tubes, this deformation is greater than for the other tubes of the bundle. Without this necessarily being a complete explanation, the applicant has hypothesized that this may be explained by a less good maintenance of the tubes in question. Indeed, this deformation is only contained by the longitudinal edges of the fins, which are free, whereas, for the other tubes of the bundle, this deformation is contained by parts of the fins themselves held by the neighboring tubes then being on either side of each tube. For the end tubes, these successive deformations, of greater amplitude than for the other tubes in the bundle, can go so far as to cause a break in the wall of the tubes, the final consequence of which is a leak from the radiator.

The object of the invention is to at least partially overcome the aforementioned drawbacks and to this end proposes a heat exchanger, in particular for a motor vehicle, comprising a beam configured to allow heat exchange between a heat transfer fluid and an air flow. , said bundle comprising heat transfer fluid circulation tubes and fins defining at least in part an air exchange surface, said fins being traversed by said heat transfer fluid circulation tubes, said tubes extending between two sides opposite sides of the bundle, said bundle comprising two free edges connecting said sides, said exchanger further comprising a longitudinal reinforcing element arranged close to one of the free edges of the bundle and passing through at least one of said fins.

In this way, the forces undergone by the end circulation tube of the bundle, that is to say, the neighboring circulation tube of said longitudinal reinforcing element, are transmitted to said longitudinal reinforcing element by the common fin(s) . The deformations of the end circulation tube of the bundle are thus contained by a part of the fins themselves held on either side of said end circulation tube, on the one hand by the neighboring circulation tube and on the other hand by the reinforcing element.

The exchanger in accordance with the invention may also have the following characteristics, taken alone or according to any technically possible combinations which form as many embodiments of the invention:

- all the fins are crossed by the reinforcing element(s),

- the fins comprise first passage orifices for the tubes and second passage orifices for the reinforcing element(s),

- said longitudinal reinforcing element is formed by a so-called reinforcing tube, said exchanger being configured to prevent the circulation of the heat transfer fluid in said reinforcing tube,

- said circulation tubes and said reinforcement tube have a first end flare,

- said circulation tubes have a second end flare, complementary to the first end flare, with the exception of the circulation tube adjacent to the reinforcement tube,

- the reinforcement tube and said neighboring circulation tube are identical,

- the said reinforcement tube(s) and all of the said circulation tubes are identical, before the said second widening is made,

- said exchanger further comprises header boxes arranged along the sides of the bundle,

- said circulation tubes open into said boxes,

- the said reinforcing tube or tubes open into the said boxes,

- the said reinforcing tube or tubes are plugged and/or closed by a cap,

- said boxes comprise a partition delimiting a first chamber inside which said circulation tubes open and a second chamber inside which said reinforcing tube opens, said exchanger being configured to allow circulation of the coolant in the first chamber and to isolate the second chamber from said circulation of the heat transfer fluid,

- said partition comprises a stop for the neighboring circulation tube of the reinforcement tube,

- said box comprises a collector plate through which the circulation tubes pass, or even the said reinforcing tube or tubes,

- said collector box comprises a cover fixed to said collector plate,

- said partition is formed by continuity of material with said lid,

- said box includes a gasket fitting on the collector plate to ensure sealing at an interface between the circulation tubes and the collector plate,

- said partition comprises a free edge compressing said seal,

- said seal comprises a groove accommodating said free edge,

- said partition extends from a bottom of the lid,

- said partition extends from a longitudinal end edge of the cover,

- the said reinforcing tube(s) open outside the said boxes,

- the tubes have a cross section with a small radius,

- a material thickness of the tubes is less than 0.3 mm.

Other characteristics and advantages of the invention will appear during the reading of the detailed description which will follow for the understanding of which reference will be made to the appended drawings in which:

- FIG. 1 partially illustrates, in sectional view, a first embodiment of a heat exchanger according to the invention, this at the level of a longitudinal end zone of a header box of said exchanger,

- FIG. 2 partially illustrates, in sectional view, a second embodiment of a heat exchanger according to the invention, this at the level of a longitudinal end zone of a header box of said exchanger,

- FIG. 3 partially illustrates, in sectional view, a third embodiment of a heat exchanger according to the invention, this at the level of a longitudinal end zone of a header box of said exchanger,

- FIG. 4 partially illustrates, in sectional view, a fourth embodiment of a heat exchanger according to the invention, this at the level of a longitudinal end zone of a header box of said exchanger.

As illustrated in Figures 1 to 4, the invention relates to a heat exchanger, in particular for a motor vehicle. Said exchanger is in particular configured to be fixed on a motor vehicle chassis, for example behind a grille of said vehicle so as to be crossed by a flow of air having previously passed through the grille. Said exchanger is integrated, in particular, in a cooling loop of an engine of said vehicle.

Said exchanger comprises, for example, a bundle 2 configured to allow heat exchange between a heat transfer fluid and said air flow. Said air flow is oriented, for example, perpendicular to the plane of the figures. Said bundle comprises heat transfer fluid circulation tubes 4 and fins 6 defining at least in part an exchange surface with the air, the fins being in contact with the circulation tubes 4.

The tubes 4 extend longitudinally along an axis X situated in the plane of the figures. In other words, they are parallel to each other. They may be grouped into one or more rows, each row being arranged one behind the other according to the direction of the air flow intended to cross the beam.

The tubes 4 have, for example, a rounded cross section, in particular round, oval or other. Advantageously, they have a cross section having a major axis, representing a width of the tubes and intended to be oriented substantially in the direction of the air flow, and a minor axis Z, representing a height of the tubes and intended to be oriented perpendicular to the air flow and the major axes of the tubes. On either side of their major axis, the tubes 4 have large curved faces connected at each end by small radii forming the lateral sides of the tubes.

Said tubes are, for example, made of metal or metal alloy, in particular stainless steel and/or aluminum alloy. A material thickness of the tubes 4 is, for example, less than 0.3 mm. With such a thickness, the tubes have the advantage of being particularly light and of reduced cost. However, they have limited mechanical strength, particularly at their small radii.

The fins 6 are preferably flat and perpendicular to the longitudinal axis X of the tubes 4. They have, for example, a rectangular shape, the long sides of the fins being oriented parallel to the minor axis Z of the tubes 4 and the short sides of the fins being oriented parallel to the airflow. They are crossed by said circulation tubes 4 of the heat transfer fluid. For this, said fins 6 advantageously comprise first orifices 7 for passage of tubes 4, said first orifices 7 having an outline corresponding to the cross section of tubes 4. Said fins 6 are, for example, made of metal or metal alloy, in particular stainless steel and/or aluminum alloy.

Said beam 2 has a substantially parallelepiped shape defined by all of the fins 6 and the tubes 4 which pass through them, the beam 2 extending in width along the longitudinal direction X of the tubes 4, in height along the long sides of the fins, that is to say along the Z axis, and in depth along the small side of the fins and parallel to the air flow.

Still in other words, said tubes 4 extending between two opposite sides of the bundle, said bundle comprising two free edges connecting said sides.

In the figures, only a part forming a corner of the exchanger is visible. In this way, only part of one 8 of the sides of the beam and only part of one 10 of its edges are visible. Similarly, only a few circulation tubes 4 and only a few fins 6 are visible. In figures 3 and 4, the fins have not been illustrated so as not to weigh down the figures.

Said exchanger further comprises header boxes 12 arranged along the sides 8 of bundle 2. Said circulation tubes 4 open into said header boxes 12.

Said collector box 12 advantageously comprises a collector plate 14, through which flow tubes 4 pass, for example at the level of first passage orifices 20. Said first orifices are here bordered by first collars 21 defined by a local deformation of the collector plate 14 .

Said collector box 12 further comprises a seal 18 fitting on the collector plate to ensure sealing at the level of an interface between the circulation tubes 4 and the collector plate 14, that is to say at the level of the first orifices passage 20. Preferably, said seal is formed from a single piece, said piece extending over the header plate, inside the box and having first protrusions in the form of a chimney, each chimney enclosing one of the circulation tubes 4, at the first passage orifice 20 corresponding. Here said first growths are sandwiched between the circulation tubes 4 and the first collars 21.

Said header box 12 further comprises a cover 16 fixed to said header plate 14. Said seal 18 may comprise a peripheral bead ensuring a seal between header plate 14 and cover 16 by being compressed in a groove located at the periphery of the collector plate 14, this by a peripheral part of the cover 16.

Collector plate 14 is, for example, made of metal or metal alloy, in particular stainless steel and/or aluminum alloy. The cover 16 is, for example, made of plastic material.

The circulation of the heat transfer fluid takes place, for example, as follows. The heat transfer fluid enters the exchanger through one of the manifolds inside which it is distributed in the circulation tubes 4. It then travels through the circulation tubes 4 and emerges from each of the circulation tubes 4 into the collector box located at the level of the opposite side and exits the exchanger. At the beam 2, a heat exchange takes place between the heat transfer fluid and the air flow by heat conduction through the walls of the circulation tubes 4 and the fins 6.

Assembly is carried out as follows. The tubes 4 are inserted into the first orifices provided in the fins 6 and undergo a first radial expansion making it possible, by material deformation, to fix the fins to the tubes. The ends of the tubes are then inserted into the first orifices 20 provided in the collector plates 14 and undergo a first flare 40 to compress the seal 18. The ends of the tubes 2 still undergo a second flare 42 to block them against the collector plates 14, this with the exception of some of the circulation tubes 4, as will be developed later. The collector boxes 12 are then closed by fixing the covers 16 on the collector plates 14.

According to the invention, said exchanger further comprising a longitudinal reinforcing element 30 disposed close to one of the free edges 10 of the bundle and passing through at least one of said fins 6. Preferably, the exchanger has such an element of reinforcement 30 along each of its free edges. Said reinforcing elements are then advantageously parallel to each other on either side of the beam 2.

Such an element stiffens the structure of the beam 2 and, in the event of expansion of the neighboring circulation tube 4, it provides, via the fins 6 that the said longitudinal reinforcing element 30 also passes through, a counter reaction making it possible to limit the deformation of tube 4 in question.

The said longitudinal reinforcing element(s) 30 are, for example, substantially parallel to the circulation tubes 4.

Preferably, said longitudinal reinforcing element(s) 30 pass through all of the fins 6. The counter-reaction is thus optimized. For this, here, the fins 6 comprise second orifices 32 for passage of the reinforcing element(s) 30. In other words, the fins 6 are provided with first passage orifices 7 and, at each end, on either side of said first orifices 7, of one of the second passage orifices 32.

As illustrated, said longitudinal reinforcing element 30 is formed by a so-called reinforcing tube, said exchanger being configured to prevent the circulation of heat transfer fluid in said reinforcing tube. By “preventing” is meant prohibiting any passage of fluid or at the very least at a very low flow rate, for example less than 1/10 or even 1/100 of the flow rate circulating in the tubes 4 for the circulation of fluid. By using a tube, we have a longitudinal element adapted to stiffen the bundle. In addition, by preventing circulation of the fluid in such a tube, it is prevented that it is itself subjected to expansion, in particular in the event of a test under cycled pressure.

According to a first variant, corresponding to the illustrated embodiments, the collector plates 14 are crossed by the said reinforcing tube or tubes 30. They are here for this provided with second passage orifices 34, optionally lined with second collars, identical to those of the first orifices 20 for passage of the circulation tubes 4. In other words, the collector plates 14 are provided with first passage orifices 20 and, at each end, on either side of said first orifices 20, with one of the second orifices of pass 34.

Said gasket 18 extends at this end portion of the plates 14 comprising said second orifices 34. It may also have second protrusions in the shape of a chimney identical to those surrounding the circulation tubes 4. As will be developed further far, the presence of the joint at such a place is not necessary from the point of view of the sealing of the collector box 12 but makes it possible to have a joint of more standard configuration and easier to install.

Like said circulation tubes 4, said reinforcing tube(s) 30 advantageously have a first end flare 37. It allows compression of seal 18 at the level of the second protrusions of said seal.

As mentioned above, the circulation tubes 4 adjacent to the reinforcing tubes 30 do not have a second widening 42. The same applies to the reinforcing tubes 30 themselves. This makes it possible to enlarge the space between the reinforcement tubes 30 and the neighboring circulation tubes 4.

Advantageously the reinforcing tubes 30 and their neighboring circulation tubes 4 are identical. In addition, before making said second flare 42, the reinforcing tubes 30 and all of said circulation tubes 4 are identical. More precisely, before deformation, the reinforcing tubes 30 and the set of circulation tubes 4 are identical and the reinforcing tubes 30 as well as the set of circulation tubes 4 undergo the first widening 40 while only the circulation tubes 4 distinct from the neighboring circulation tubes of the reinforcement tubes 30 undergo the second flare 42. Starting from identical tubes allows high standardization of the components of the bundle 2. For the same purpose as well as for good mechanical strength, the fins 6 are fixed to the reinforcement tubes 30 by radial expansion, at their second orifices 32, as for the circulation tubes 4 at the level of the first orifices 7 of said fins 6.

Preferably, said reinforcing tube or tubes 30 open into said boxes 12. Said boxes 12 then comprise here a partition 44 delimiting a first chamber 46 inside which said circulation tubes 4 open and a second chamber 48 inside from which said reinforcement tube 30 emerges, said exchanger being configured to allow circulation of the heat transfer fluid in the first chamber 46 and to isolate the second chamber 48 from said circulation of the heat transfer fluid. Thus, the heat transfer fluid does not circulate in the reinforcing tubes 30. It is understood that the space, mentioned above, between the circulation tubes 4 adjacent to the reinforcing tubes 30 and said reinforcing tubes 30 themselves facilitates the positioning of said partition 44. Indeed, said partition 44 is inserted between them. Said partition is formed, for example, by continuity of material with said cover 16.

Said partition here comprises a free edge 50 compressing said seal 18. Said seal 18 optionally comprises a groove 52 accommodating said free edge 50. This makes it possible to reinforce the tightness offered by the partition 44.

Advantageously, as illustrated in Figures 1 and 2, said partition 44 comprises a stop 54 for the circulation tubes 4 adjacent to the reinforcing tubes 30. Thus, although said circulation tubes 4 adjacent to the reinforcing tubes 30 do not have a second widening , they are also blocked with respect to the collector plate 14. Said abutment 54 extends over only part of the width of the boxes 12 so that it only blocks in a limited way the circulation of the heat transfer fluid in the said heat transfer tubes. circulation 4 against which it is resting.

As is the case in Figure 1, the partition 44 has, in cross section, a T shape, the abutment 54 forming the vertical bar of the T.

As is the case in Figure 2, the abutment 54 is in the form of a protrusion of material positioned at the median level of a distal part of the partition 44.

Alternatively, as illustrated in Figures 3 and 4, it can be seen that said partition 44 has a substantially planar shape and is not provided with a stop for blocking the tubes.

In Figures 1, 3 and 4, said partition 44 extends from a bottom of cover 16. In Figure 2, said partition 44 extends from a longitudinal end edge of cover 16.

According to a first variant, not shown, the said reinforcing tube or tubes are plugged and/or closed by a cap. The presence of the partition separating the collector box into two chambers is then not necessary.

According to another variant, not shown, the said reinforcing tube or tubes 30 open outside of the said boxes 12.

In each of these variants, it is understood that the heat transfer fluid does not circulate in the reinforcing tubes 30.

Claims (10)

Heat exchanger, in particular for a motor vehicle, comprising a bundle (2) configured to allow heat exchange between a heat transfer fluid and an air flow, said bundle (2) comprising tubes (4) for circulation of the heat transfer fluid and fins (6) defining at least in part an exchange surface with the air, the fins (6) being traversed by said tubes (4) for circulating the heat transfer fluid, said tubes (4) extending between two sides (8) opposite the beam, said beam comprising two free edges (10) connecting said sides (8), said exchanger further comprising a longitudinal reinforcing element (30) arranged close to one of the free edges (10) of the beam (2) and passing through at least one of said fins (6). Exchanger according to Claim 1, in which the set of fins (6) is crossed by the longitudinal reinforcing element (30). Exchanger according to any one of the preceding claims, in which the longitudinal reinforcing element (30) is formed by a so-called reinforcing tube, the said exchanger being configured to prevent the circulation of the heat transfer fluid in the said reinforcing tube (30). Exchanger according to the preceding claim further comprising header boxes (12) arranged along the sides (8) of the bundle (2), said circulation tubes (4) and said reinforcing tube (30) opening into said boxes (12) . Exchanger according to the preceding claim, in which said boxes (12) comprise a partition (44) delimiting a first chamber (46) inside which said circulation tubes (4) open out and a second chamber (48) inside from which the reinforcing tube (30) emerges, said exchanger being configured to allow circulation of the heat transfer fluid in the first chamber (46) and to isolate the second chamber (48) from said circulation of the heat transfer fluid. Exchanger according to the preceding claim, in which the said partition (44) comprises a stop (54) for the circulation tube (4) adjacent to the reinforcement tube (30). Exchanger according to any one of Claims 5 or 6, in which the said box (12) comprises a header plate (14) through which the said circulation tubes (4) and the said reinforcement tube (30) pass, the said header box (12) comprising a cover (16) fixed to said collector plate (14), said partition (44) being formed by continuity of material with said cover (16). Exchanger according to the preceding claim, in which the said box (12) comprises a seal (18) fitting on the collector plate (14) to ensure sealing at the level of an interface between the circulation tubes (4) and the collector plate (14), said partition (44) comprising a free edge (50) compressing said seal (18). Exchanger according to any one of Claims 3 to 8, in which the said reinforcing tubes (30) are plugged and/or closed by a cap. Exchanger according to any one of claims 1 to 3 further comprising header boxes (12) arranged along the sides (8) of the bundle (2), said circulation tubes (4) in said boxes (12), exchanger in which said reinforcement tube (30) opens outside manifolds (12).