Heat exchanger

Abstract

The present invention relates to a heat exchanger, in particular for an automotive vehicle, more particularly to electric vehicle, comprising: - a core with a plurality of tubes for carrying a fluid, the tubes extending in a first direction, (each preferably having a center region allowing heat exchange with outside environment), - a tank extending over a tank length along a second direction and to which said heat exchanger tubes are fluidly connected, wherein the tank comprises a body defining a cavity for said fluid, a tank opening of said cavity being delimited by a peripheral border extending in the first direction, the peripheral border comprising a distal end portion defining an annular end face and a fixing portion adjacent the distal end portion; - a header plate closing said tank opening, said header plate having a rear side facing the cavity, an opposite front side and peripheral fixation flanges bent rearwardly toward the tank, wherein the header plate is made from a flat metal sheet and comprises in a central region, header slots (also sometimes referred to as through holes) surrounded by respective collars extending from the rear side toward the tank, the through-holes receiving end portions of said heat exchanger tubes, and a peripheral edge portion surrounding the central region and facing the annular end face of the tank, the fixation flanges extending from the peripheral edge portion; - fixing features in the fixing portion configured to cooperate with the fixation flanges; - an annular gasket arranged on the rear side of the header plate along the peripheral edge portion. According to the present invention, the heat exchanger presents the following features: - a variation in thickness along the first direction between the distal end portion and the fixing portion is not greater than + / - 25%, preferably not greater than 20 %, more preferably not greater than 10 % or 5%; - the peripheral edge portion is coplanar with the central region; - the annular gasket is compressed along the first direction between the annular end face and the peripheral edge portion, rests inwardly against the collars at least in the second direction, and is outwardly maintained by the bent fixation flanges.

Description

FIELD OF THE INVENTION

[0001] The present invention generally relates to the field of heat exchangers and particularly relates to fluid-air heat exchangers as arranged in automotive vehicles.BACKGROUND OF THE INVENTION

[0002] A heat exchanger such as a radiator, charge air cooler (CAC), condenser or evaporator, for use in an automotive vehicle, includes usually an inlet tank, an outlet tank and a plurality of flat tubes extending between the tanks. The tubes connect fluidly the two tanks and enable a fluid flow between them. The connection of the tubes to a respective tank is established by means of a header plate comprising oblong apertures in which the tubes are fitted, and which closes the tank cavity.

[0003] According to one prior art design, such as e.g. US 5,327,959 A, tanks and header plates are respectively made of metal such as aluminum and assembled by brazing. While providing for a uniform sealing of plate to tank, such full metal heat exchangers are difficult to manufacture, limited to some conventional shapes and expensive.

[0004] According to another conventional design, tanks are made by plastic molding, thereby decreasing productions costs and allowing for a wider variety of designs / shapes. Such a heat exchanger with plastic tanks are known e.g. from US 2002 / 134529 A1 or US 2013 / 264039 A1.

[0005] In order to fix the header plate to the plastic tank, a plurality of deformable metallic tabs, often referred to as crimping tabs or (single) clinch tabs, are usually provided at the periphery of the header plate, and deformed to grab / engage around a protruding portion of the tank body, known as "tank foot".

[0006] However, due to the need for the plate to be fixed to the tank by clinching, there is a significant increase in the dimensions of the tank at the tank foot, and thus in the overall dimensions of the heat exchanger. In addition, in an industrial setting such as an assembly line, the process of crimping or clamping of each tab is considered rather time and resource consuming.

[0007] Moreover, in plastic tanks, a circumferential gasket is arranged between the header plate and tank opening, such as below or against the tank foot. The gasket is usually received in a dedicated groove surrounding the tube openings in the header plate, and often offset forward, as disclosed in US 2002 / 134529 A1 and US 2013 / 264039 A1, which further increases dimensions of the header plate and of the heat exchanger.OBJECT OF THE INVENTION

[0008] The object of the present invention is to provide an alternative, improved design of heat exchanger, which avoids the above-mentioned drawbacks.

[0009] This object is achieved by a heat exchanger as claimed in claim 1.SUMMARY OF THE INVENTION

[0010] The present invention relates to a heat exchanger, in particular for an automotive vehicle, comprising: a core with a plurality of tubes for carrying a fluid, the tubes extending in a first direction, (each preferably having a center region allowing heat exchange with outside environment); a tank extending over a tank length along a second direction and to which said heat exchanger tubes are fluidly connected, wherein the tank comprises a body defining a cavity for said fluid, a tank opening of said cavity being delimited by a peripheral border extending in the first direction, the peripheral border comprising a distal end portion defining an annular end face and a fixing portion adjacent the distal end portion; a header plate closing said tank opening, said header plate having a rear side facing the cavity, an opposite front side and peripheral fixation flanges bent rearwardly toward the tank, wherein the header plate is made from a flat metal sheet and comprises in a central region, header slots (also sometimes referred to as through holes) surrounded by respective collars extending from the rear side toward the tank, the through-holes receiving end portions of said heat exchanger tubes, and a peripheral edge portion surrounding the central region and facing the annular end face of the tank, the fixation flanges extending from the peripheral edge portion; fixing features in the fixing portion configured to cooperate with the fixation flanges; an annular gasket arranged on the rear side of the header plate along the peripheral edge portion.

[0011] According to the present invention, the heat exchanger presents the following features: a variation in thickness along the first direction between the distal end portion and the fixing portion is not greater than + / - 25%, preferably not greater than 20 %, more preferably not greater than 10 % or 5%; the peripheral edge portion is coplanar with the central region; the annular gasket is compressed along the first direction between the annular end face and the peripheral edge portion, rests inwardly against the collars at least in the second direction, and is outwardly maintained by the bent fixation flanges.

[0012] As apparent to the skilled person, the annular gasket is arranged for sealing purpose between the header plate and the tank, and may be manufactured in any suitable manner. The gasket may adopt any desired shape or configuration and can be fabricated from any suitable material or combination of materials, depending on the use case. The gasket may have a round or square / rectangular cross-section.

[0013] It shall be appreciated that, as the thickness variation between the distal end portion and the fixing portion of the peripheral border of the tank body is not greater than + / - 25%, preferably not greater than + / - 20 %, more preferably not greater than + / - 10 % or + / - 5%, the peripheral border is substantially straight, i.e. extends in one direction only (being the first direction). One could also say that the peripheral border has a substantially constant thickness along its direction of extension, a variation in thickness along said direction being not greater than ±25%. This is true over the entire continuous length of the peripheral border.

[0014] In other words, the peripheral border does not comprise a conventional so-called tank foot nor does it present a portion forming a (sharp) bend, i.e. there is no section change. That is to say, the peripheral border of the present heat exchanger might be considered as I-shaped while conventional (plastic tank) heat exchangers rather have a tank comprising a L-shaped or a Z-shaped peripheral border, the smaller arm of the L-shape or middle part of the Z providing an outwardly protruding clinching / crimping surface for attachment of the header plate due to a change in thickness or to a bend, respectively.

[0015] To recap, the peripheral border extends continuously and substantially straight in the first direction, the thickness of the peripheral border (including the distal end portion and the fixing portion) along the entire continuous length thereof in said first direction varying by not more than ±25%.

[0016] Typically, each of the distal end portion and the fixing portion have predetermined thickness. It should also be understood that since the distal end portion and the fixing portion are adjacent, there is no intermediate section. Also, since the distal end portion and the fixing portion extend along the same direction (first direction), there is no intermediate bend interrupting the peripheral border along the first direction.

[0017] Advantageously, by having a rather straight tank foot region, the proposed design of the peripheral border thus allows to significantly reduce dimensions of the tank body in the second direction (length of the body) and a third direction being a direction of a tank width (i.e. substantially perpendicular to both the first and second direction). It is considered that the present design improves the packaging compactness, and specifically permits a reduction of 25% of the thickness of the tank peripheral border in the second and third directions.

[0018] In the present text, the expression "a thickness variation between A and B is not greater than + / - C %" or "a variation in thickness between A and B is not greater than + / - C %" means that the thickness of A is neither greater nor smaller than C % of the thickness of B and conversely that the thickness of B is neither greater nor smaller than C % of the thickness of A.

[0019] Moreover, it shall also be appreciated that the annular gasket is arranged on a plane coplanar with the rear side of the header plate, i.e. there is no dedicated groove (or recess) to receive the gasket. This advantageously allows to reduce dimensions of the tank - header plate assembly in the first direction, and to reduce material requirements for the header plate, thereby saving weight and costs.

[0020] Furthermore, as the annular gasket rests inwardly against the collars at least in the second direction it is maintained by (i.e. leans on / rests on / presses down on) the, preferably chamfered, respective portion of the collars proximal to the header plate rear side, so that it is advantageously positioned to ensure a tight, leak-free connection between header plate and tank, and the collars prevent movements / displacements of the gasket (during and after assembly of the header plate and tank) which may result in a non-continuous sealing. In other words, due to the annular gasket being compressed along the first direction between the annular end face and the peripheral edge portion, resting inwardly against the collars at least in the second direction, and being outwardly maintained by the bent fixation flanges, it is always in contact so as to ensure the leak-free connection between tank and header plate.

[0021] The peripheral edge portion is dimensioned so as to provide a sufficient contact surface with the gasket for ensuring a leak-free and tight assembly. Preferably, the thickness of the distal end portion (and hence the width of the annular end face) of the tank substantially corresponds to the diameter of the gasket in a rest (i.e. uncompressed) state. Furthermore, a width of the peripheral edge portion may substantially correspond to a diameter of the gasket in its uncompressed state.

[0022] In summary, the inventive heat exchanger presents the (main) following advantages: reduction of packaging in the third direction, typically of 6 to 10 mm, such as e.g. width reduction of 8 mm. weight savings, typically of about 50 weight saving on header plate, 12 % weight saving on tank, 10 % weight saving on assembled heat exchanger (around e.g. 200 g). cost savings.

[0023] Depending on the application, the fluid circulated in the heat exchanged (from one tank to the other though the core) may be a fluid, namely a liquid, a gas, or a mixture thereof. For example, the fluid may be water, air, oil, or a given coolant fluid. In embodiments, the heat exchanger is used to cool the coolant fluid; but it could also be used to warm-up or heat the fluid.

[0024] The tank may be conventionally made from a plastic material (e.g. by plastic molding), and the heat exchanger thus combines advantages of a low packaging and corresponding weight gain, with low costs and easier manufacturing process related to a plastic tank.

[0025] In embodiments, the annular end face of the tank may be curved to better accommodate the gasket, i.e. the annular end face of the tank may present an outer profile matching an outer profile of the annular gasket. This advantageously facilitates positioning of the tank upon assembly, while further ensuring a correct position of the gasket in the (assembled) heat exchanger and increase sealing performances by reducing risks of gasket displacement.

[0026] In embodiments, a distance in the first direction on the front side of the header plate between the central region and the peripheral edge portion is no greater than 1.0 mm, preferably lower than 0.5 mm. In other words, the header plate front side is essentially planar, i.e. the header plate does not comprise a groove extending away from the tank in the first direction, nor any other feature protruding from the front side in the first direction. Advantageously, in such embodiments, there is no so-called lost portion of the tubes in the first direction, i.e. no portion of the tubes being neither inserted / received in a collar nor in unimpeded contact with ambient air. In turns, either the heat exchange capacity may be increased with respect to conventional heat exchanger with plastic tanks having tubes of the same length (increase of useful length of tubes for heat exchange surface by about 12 mm), or the tubes may be shortened while maintaining the heat exchange capacity, thereby reducing material requirement and thus resulting in weight savings and production costs savings.

[0027] In embodiments, the peripheral border of the tank body further comprises a plurality of recesses facing the cavity and arranged for receiving a respective portion of a collar, that is to say recesses inside the cavity to accommodate therein respective collar portions.

[0028] Advantageously the dimensions of the tank - header plate assembly can be further reduced in the third direction. Indeed, as part of the collars is received in the thickness of the peripheral border (i.e. in a dedicated recess), inner width of the tank (namely width of the cavity) may be reduced. Further advantageously, the recesses facilitate alignment between tank and header plate upon assembly.

[0029] In embodiments, the central region of the header plate further comprises linear ribs protruding rearwardly (i.e. toward the cavity of the tank) and arranged between header slots pairs (i.e. through holes pairs), in a direction parallel to the main extension of the header slots (i.e. through holes). Advantageously, such ribs enhance rigidity (i.e. strengthen) the header plate while further maintaining the gasket. Indeed, in such embodiments, the gasket is further directly maintained by (i.e. contacts / rests against) the ribs, thereby preventing the gasket from being deformed / displaced / misaligned toward a center line of the central region.

[0030] The gasket may either be a conventional, pre-formed gasket or a so-called cured in place gasket, i.e. a gasket that is formed directly onto the header plate by applying and then hardening (i.e. curing) a liquid or gel sealing material, or an over-molded gasket (over-molded on the annular end face of the tank, preferably made form a thermoplastic elastomer). Preferably, the gasket is cured in place or over-molded, as such gasket advantageously can be tailored to any desired shape and directly adhere to the rear surface of the header plate, further minimizing risk of undesired gasket displacement upon assembly of the heat exchanger and thus lessening risks of failure (such as e.g. leakage).

[0031] Preferably, the annular gasket presents (i.e. has) a diameter of strictly less than 3 mm, preferably between 1.2.0 and 2.8 mm, more preferably between 1.5 and 2.7 mm, even more preferably between 1.8 and 2.5 mm and most preferably of about 2.0 mm. In other words, with respect to conventional (plastic tank) heat exchangers, the gasket diameter is reduced, as a consequence of the increased compactness / reduced dimensions of the tank-header plate assembly. Advantageously, less material is required for the gasket, further reducing production costs.

[0032] In embodiments, the peripheral fixation flanges each extend along a respective edge and are disconnected from one another, separated by a gap. Advantageously, the gaps may facilitate positioning of a conventional gasket / help holding a conventional gasket in place during assembly of the header plate to the tank.

[0033] The header plate may have any appropriate shape, which may be selected by the skilled person. Conventionally, the header plate may have a square or rectangular shape and comprise four fixation flanges, one along each edge (one per longitudinal edge, one per transversal edge). Alternatively, the fixation flange along one edge could be split into two or more sub-sections.

[0034] In embodiments, the fixing features comprise a plurality of rigid tabs protruding laterally from the fixing portion of the peripheral border of the tank, the tabs laterally extending generally in a direction parallel to the plane of the header plate, and the fixation flanges of the header plates comprise a plurality of apertures arranged for engaging the tabs therein, wherein the tabs comprise a locking surface on a side facing away from the header plate, the locking surface virtually extending in a first plane crossing a second plane parallel to a rear surface of the flat metal sheet with a sharp angle (α), whereby the tabs and apertures provide for a self-closing engagement.

[0035] It shall be appreciated that the proposed fixing features allows a safe and simple assembly, by means of the self-closing engagement, which advantageously results in a uniform compression of the gasket. The self-closing engagement may represent a form-fit or force-fit connection between the rigid tabs and the corresponding apertures of the fixation flanges. In addition to that, the proposed heat exchanger may be manufactured cost efficiently and may provide a particularly long service life.

[0036] During assembly, by pressing, e.g. in a clinching machine, the header plate onto the gasket, a compressive force is exerted on the gasket, which leads to an over compression of the gasket which endures merely a short time period. During this time, a bending of the deformable fixation flanges occurs, such that the apertures of the fixation flanges engage with the tabs. When the engagement has taken place, the pressure applied by the clinching machine is released which ends the over-compression and leads to a slight forward movement of the header plate in relation to the peripheral border of the tank body. This slight forward movement is caused by the decompressing gasket. As a consequence of this decompression, the peripheral border of the tank body is pushed away from the header plate. However, the movement of the header is limited by the tabs coming into abutment in the apertures: in this configuration the gasket is still partially compressed so as to keep the assembly in tension. This further strengthens the connection between apertures of the fixation flanges and the tabs and further contributes to an enhanced stability and robustness of the heat exchanger arrangement.

[0037] In other words, the proposed heat exchanger allows to control the gasket compression by the arrangement of its different constructional elements, whereby influences from the clinch process are reduced or entirely avoided. Since the assembly process for the proposed heat exchanger may need only to bend the sides (the rim) of the header plate in the right position - and not also the plurality of tabs - the assembly process itself is simplified and an over or irregular compression of the gasket is prevented. This may lead in turn to an estimated time of the clinch process that may be reduced at least by half. Furthermore, the scrap rate will be less dependent on the clinching process. The arrangement thus allows a faster assembly process whilst providing a fixed compression rate for the gasket. It should be noted that this may also lead to reduced production costs as well.

[0038] In embodiments, the tabs present a hook-like cross-sectional shape. Tabs with a hook-like cross-sectional shape may be particularly advantageous for achieving a quick closure. It should be noted that such a cross-section shape may be viewed when referring to a section along a plane defined by the first direction and a second direction perpendicular to the first direction.

[0039] In embodiments, each tab has an outwardly tapering cross-sectional profile. A tapered profile may be inserted particularly quickly into a corresponding aperture, such that the assembly time may be further reduced. It should be noted that such a cross-sectional profile may be viewed when referring to a section along a plane defined by the first direction and a second direction perpendicular to the first direction.

[0040] In embodiments, each aperture of the plurality of apertures has a trapezoidal cross-sectional profile. Due to the trapezoidal shape, one opening side of the aperture facing the tabs can be larger than the opposing opening side. This results in a further simplified and quick engagement. It should be noted that such a cross-sectional profile may be viewed when referring to a section along a plane defined by the first direction and a second direction perpendicular to the first direction.

[0041] In embodiments, the tabs present a chamfer adjacent to the locking surface and a front surface of a respective tab. The chamfer may thus be present at a front corner section of each tab. The chamfer may have an angle in a range of 15° to 85°, preferably 45°. The chamfer allows the tab to slide through the aperture of the fixation flange accurately and particularly quickly during an assembly.

[0042] In embodiments, the sharp angle is an angle within a range of 3° to 40°, preferably from 5° to 20°. The sharp angle prevents the (respective) fixation flange from slipping off the tab. Instead, the inclined locking surface of the tab even causes the fixation flange to move along a direction pointing towards the tank body. The locking surface may refer to an "upper" surface of a tab, respectively a side facing away from the header plate. The locking surface may thus be situated in the first plane, which virtually crosses, respectively cuts, the second plane parallel to a rear surface of the flat metal sheet.

[0043] In embodiments, wherein a lateral extension of each tab is at most equal to a wall thickness of the fixation flanges. In other words, the tabs are not longer than a thickness of the respective aperture engaging said tab, the thickness being defined between one opening side of the aperture facing the tabs and the opposing opening side. That is to say, the tabs do not protrude / extend outside the fixation flanges and the thickness required for fixing / securing the header plate to the tank is provided by the header plate itself, reducing the overall dimensions (in the second and third directions) of the heat exchanger.

[0044] The present invention can be used for any configurations of a heat exchanger, be it for I-flow configuration (inlet and outlet tanks at opposite ends of the tubes) or U-flow configuration (inlet and outlet tanks on the same side).

[0045] The present heat exchanger may generally be used as radiator or charge air cooler in automotive vehicles, however other applications are possible. Moreover, while the present heat exchanger has been designed for preferred use in a battery electric vehicle, it may however be used in any kind of electrical vehicle, such as a mild hybrid, full hybrid or plug-in hybrid vehicle.BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1A is an exploded view of the present heat exchanger; Fig. 1B is a perspective view of the present heat exchanger in assembled configuration; Fig. 2 is a perspective view of the header plate; Fig. 3A is a partial perspective view of the tank of the heat exchanger of Fig.1, wherein the tank is fixed to the header plate; Fig. 3B is a partial perspective view of another embodiment of a tank of a heat exchanger according to the invention, wherein the tank is fixed to the header plate; Fig. 4 is a detail cross-sectional view through the tank and header plate along section A-A; Fig. 5 is a detail cross-sectional perspective view through the tank and header plate along section B-B; Fig. 6 is a schematic front view of the peripheral border of the tank of Fig.3A, wherein the tank and the header plate are engaged with each other (final assembly configuration); Fig. 7 is a schematic front view of the peripheral border of the tank of Fig.3A, wherein the tank and the header plate are disengaged from each other (intermediate assembly configuration DESCRIPTION OF PREFERRED EMBODIMENTS

[0047] In reference to Fig.1A and Fig.1B, an embodiment of the present fluid-air heat exchanger 10 is shown in exploded and assembled configurations. The heat exchanger 10 conventionally has a plurality of tubes 14 (forming a core 12) for conveying the fluid between two tanks 20.

[0048] A tank 20 having a tank body 22 extends along direction Z. The tank body 22 has an inner cavity 24. The tank body 22 further has an opening 24.1 allowing access to the inner cavity 24. The cavity 24 is configured to hold the fluid when the heat exchanger is in operation. The cavity 24 is delimited by a peripheral border 26 of the tank body 22 that defines the tank opening 24.1. In reference to Fig.3, the tank body 22 of a tank 20 is seen from its outer side. The tank body 22 is typically manufactured by plastic injection molding and typically comprises on its outer side series of parallel reinforcing ribs (not shown).

[0049] A header plate 40 is used to close the tank opening 24.1, wherein the header plate 40 has a plurality of slots 46 (i.e. openings or oblong through holes, also referred to as header slots)for receiving respective end portions of the tubes 14.

[0050] The plurality of tubes 14 extend between the opposite tanks 20. The tubes 14 are substantially straight and comprise at least one inner channel, wherein a fluid is conducted. In addition, the tubes may also be provided with fins on the outer surface of said tubes. The fins improve the thermal transfer. Generally, the tubes may be flat and may have a substantially rounded-off rectangular cross section. It should however be noted that tubes may also present cross-sections of different forms. The tubes may be arranged in a parallel and aligned manner in order to form a single row. However, other configurations are likewise possible. The flat tubes 14 extend along direction Y.

[0051] Fig.1B shows the assembled configuration of the heat exchanger 10. The tubes 14 and header plates 40 are typically made from metal, i.e. aluminum alloy, and can thus be assembled by brazing. A seal component (i.e. seal member), or annular gasket, 60 is conventionally arranged between the header plate 40 and tank opening 24.1.

[0052] As apparent from the drawings, the shown embodiments pertain to a vertical I-flow type heat exchanger: the fluid flows vertically (here axis Y) and is distributed by the top tank into the core and then collected by the lower tank. This is only a design option and the heat exchanger could be designed for horizontal flow (with vertically extending tanks).

[0053] Turning now to Figs. 2 to 7, various views of the tank and header plate assembly are shown. As is known, each tube 14, at both ends, communicates fluidly with a respective tank 20. More precisely the tube ends are engaged, in a fluid tight manner, in respective openings slots 46 of the header plates 40, which in turn closes the cavity 24 of the tank 20 to which it is mounted.

[0054] Each header slot (or through hole) 46 is surrounded by a respective slot collar 46.1 that extends from the rear side toward the tank cavity. These collars, typically stamped by metal cutting, punching,... receives an end portion of a respective tube. A brazed assembly between tube and header slot collar provides a secure and leak proof junction of the tubes to the header plate.

[0055] The header plate 40 is fixed to the peripheral border 26 of the tank body 22 by means of fixing features 30. The peripheral border 26 extends along direction Y thus forming an end region of the tank body 22 adjacent to the header plate 40, and which defines the tank opening 24.1. The peripheral border 26 comprises a distal end portion 26.1 (being proximal to the header plate) that defines an annular end face 26.2 and a fixing portion 26.3 adjacent to the distal end portion 26.1 (opposite the annular end face 26.2). The fixing portion 26.3 is thus arranged above the distal end portion 26.1 and connects the tank body 22. As will be further described below, the fixing features 30 for securing the header plate 40 to the tank body 22 are arranged in the fixing portion 26.3 of the peripheral border 26 and are configured to cooperate with fixation flanges 50 of the header plate 40 (see below).

[0056] The distal end portion 26.1 has a thickness T D , measured in a direction perpendicular to the extension direction of the peripheral border 26 and the fixing portion 26.3 has a thickness T F , measured in the same direction. As displayed on e.g. Fig. 4 and 5, the peripheral border 26 is substantially straight, i.e. T D = T F and can be described as being I-shaped. In other, not shown, embodiments T D might be slightly greater and / or smaller than T F however the following conditions are always fulfilled: 0.75*T F ≤ T D ≤ 1.25*T F , preferably 0.80*T F ≤ T D ≤ 1.20*T F , more preferably 0.90*T F ≤ T D ≤ 1.10*T F , even more preferably 0.95*T F ≤ T D ≤ 1.05*T F 0.75*T D ≤ T F ≤ 1.25*T D , preferably 0.80*T D ≤ T F ≤ 1.20*T D , more preferably 0.90*T D ≤ T F ≤ 1.10*T D , even more preferably 0.95*T D ≤ T F ≤ 1.05*T D

[0057] It shall be appreciated that the annular end face 26.2 is presented as being flat, other profiles are however still within the scope of the present disclosure, such as e.g. a slightly (concavely) curved profile.

[0058] The peripheral border 26 thus extends substantially straight along its direction of extension (i.e. axis Y), a variation in thickness along the entire length of the peripheral border 26 in said direction being not greater than ±25%. As indicated by the arrows T D and T F , the thickness is measured in a direction perpendicular to the direction of extension of the peripheral border 26, i.e. here along axis X.

[0059] The peripheral border 26 may further comprise a plurality of recesses 27 arranged on the inner side of the tank body 22 (i.e. within the cavity 24) and designed to receive the end portions of the collars 46.1. The recesses 27 are arranged at least in the distal end portion 26.1 of the peripheral border 26; they extend from the annular end face 26.2 in direction Y. Accordingly, locally, the distal end portion 26.1 is thinner than the fixing portion 26.3. However, a thickness variation between the distal end portion 26.1 (at the level of the recess - thickness T D-R ) and the fixing portion 26.3 (thickness T F ) is still lower than + / - 25%, e.g. between + / - 15% and + / - 5%. Each recess 27 is shaped so as to accommodate a portion of a collar 46.1, i.e. the collar portion and recess are correspondingly shaped. Recesses 27 may present any suitable shape such as e.g. an arched (with a rounded top) or semicircular (with the flat side being the bottom and the curved side being the top) shape.

[0060] The header plate 40 is a plate-like metallic element of a substantially rectangular shape. In Fig.3A and 3B, the header plate 40 is attached to the tank 20, while Fig.2 shows the header plate 40 separate from the tank 20. The header plate 40 may generally be made from sheet metal (e.g. aluminum alloy) by using a deformation process, such as stamping, cutting, punching or other metal-working processes.

[0061] As best seen in Fig.2, the header plate 40 has a rear side 40.1 facing the tank 20 and the peripheral border 26 of the tank body 22, hence facing the cavity 24, and an opposite front side 40.2. As can be observed, the header slots 46 for receiving the end portions of the tubes 14 are arranged in a central region 42 of the flat metal sheet and are surrounded by their respective collars 46.1 extending from the rear side 40.1 toward the tank 20 and being in joined with the tube ends, whereby the tube ends are fixed in a sealed manner to the header plate 40 upon brazing of the tube / header assembly. Referring to the orientation of the Figs, the header plate 40 may generally extend along a main extension plane ZX, i.e. where the header length is along axis Z and the header width along axis X. The tubes 14 extend along axis Y, which is also the tubes' insertion direction. It is understood, that the three direction X, Y and Z perpendicular to one another.

[0062] The header plate 40 further comprises peripheral fixation flanges 50 bent rearwardly toward the tank 20. The fixation flanges 50 extend rearwardly from a peripheral edge portion 44 of the header plate 40, the peripheral edge portion 44 surrounding the central region 42 and facing the annular end face 26.2 of the peripheral border 26 of the tank body 22. The peripheral edge portion 44 thus forms a kind of outer frame of the header plate. As will be understood, the term "central region" is used in relation to the peripheral annular region 44 that surrounds it. In other words, the central portion of the header is the portion comprising the slots (i.e. through holes receiving an extremity of the tubes) and is delimited by the peripheral edge portion. That is to say, the central portion faces and corresponds (shape- and size-wise) to the tank opening while the peripheral edge portion faces and corresponds (shape- and size-wise) to the annular end face of the tank.

[0063] It may be noted that the metal sheet portion corresponding to the peripheral edge portion 44 is substantially coplanar with the metal sheet portion corresponding to central region.

[0064] In Fig.2 the header plate 40 is in the as-produced configuration, before assembly to the tank body 22, i.e. this is the header plate configuration before bending of the fixation flanges 50 onto the fixing features 30, whereby the fixation flanges 50 are outwardly inclined.

[0065] One may further note from Fig.3A that the fixation flanges 50 are disconnected from one another at the corner of the header plate. That is to say, there are four fixation flanges 50, each extending along one of the edges of the header plate 40 (two longitudinal edges and two transversal edges). As can further be seen, the four fixation flanges 50 are not connected at the four corners 52, i.e. there is a small gap 52 between adjacent fixation flanges 50.

[0066] Alternatively, the fixation flange 50 may be continuous over the whole periphery of the header plate (as shown on Fig. 3B).

[0067] The figures also show a circumferential gasket 60, which is arranged on the rear side 40.1 of the header plate 40 along the peripheral edge portion 44. The gasket 60 provides a fluid-tight assembly of the header 40 on the tank opening 24.1. The annular gasket 60 is compressed along the first direction between the annular end face 26.2 of the peripheral border 26 of the tank body 22 and the peripheral edge portion 44 of the header plate 40. Furthermore, gasket 60 rests inwardly against the collars 46.1 at least in the second direction (i.e. lean on the lateral ends of the collars), and its outward displacement (i.e. opposite the collars) is limited by the bent fixation flanges 50. As the gasket 60 is arranged on the rear side of the peripheral edge portion 44, it lies on a plane coplanar with the rear side 40.1 of the header plate 40, i.e. with the central region. That is, there is no dedicated groove or recess for receiving the gasket 60 that is offset in direction Y from the central region.

[0068] As will be appreciated from Fig. 4 and 5, the gasket 60 directly contacts the collars 46.1 of the header slots 46 receiving the tubes 14, the header plate rear side 40.1, the annular end face 26.2 of the tank body 22 and, preferably, the fixation flanges 50 of the header plate 40. It is however also possible and within the scope of the present disclosure that a space or gap be formed between the gasket 60 and the fixation flange 50 in the assembled state of the heat exchanger 10, e.g. to better accommodate shape / size variation upon compression of the gasket (during assembly), and also due to the preferably advantageously reduced diameter of the gasket with respect to conventional plastic tank heat exchangers.

[0069] The central region 42 of the header plate 40 may further comprise linear bumps (or ribs) - not shown - protruding rearwardly (i.e. toward the cavity of the tank) and arranged between the openings 46, in a direction parallel to the main extension of the through-holes (header slots). Hence one rib is provided between a pair of neighboring openings 46. The gasket 60 rests inwardly, in the second direction i.e. in the Z direction, against the ribs. Such ribs hence improve the stiffness of the header plate and further prevent any inward displacement of the gasket 60.

[0070] According to the same or other embodiments, the front side 40.2 of the header plate 40 may present bumps (or protrusions) between the header slots.

[0071] As can be further derived from Figs. 4, 6 and 7, a plurality of rigid tabs 30 (as fixing features) protrudes laterally on the outer side of tank body, from the fixing portion 26.3 of the peripheral border 26. The tabs 30 may have a substantially cuboid-like or prismatic basic shape. As can be seen from the drawings, the fixing portion 26.3 is generally perpendicular to plane XZ, and the tabs 30 extend globally perpendicularly to the fixing portion 26.3.

[0072] In other words, the tabs 30 may generally extend in a direction parallel to the main extension plane of the header plate 40. Since the peripheral border 26 of the tank 20 conventionally has four edges (providing a substantially rectangular opening 24.1), the rigid tabs 30 protrude from the fixing portion 26.3 generally along direction Z (on small / width edges) or along direction X (on longitudinal edges), and hence generally perpendicularly to axis Y.

[0073] As can be derived from Fig. 4, the tabs 30 protrude in a manner allowing to form a sharp angle α between an upper surface, referred to as locking surface 32 of a tab 30, and direction Y. This angle α may e.g. vary between 3 to 40°, e.g. 5 to 20°. In other words, each tab 30 of the plurality of tabs comprises a locking surface 32 on a side facing away from the header plate 40, wherein the locking surface 32 extends virtually in a first plane A that crosses, respectively cuts, a second plane B parallel to the rear side 40.1 of the header plate 40 with a sharp angle α.

[0074] It will be appreciated that the fixation flanges 50 of the header plate 40 include a plurality of apertures 54. The apertures 54 are configured to be engaged with corresponding tabs 30. In doing so, a self-closing engagement is formed quickly during the assembly due to the hook-like cross-sectional shape of the tabs 30 with the sharp angle α which, due to the orientation of locking surface 32, brings the fixation flanges 50 of the header plate towards the peripheral border 26 (fixing portion 26.3) of the tank body 22 when the header plate 40 and tank 20 tend to be pulled apart. Indeed, as a consequence of the sharp angle α the tabs 30 and apertures 54 on the bent fixation flanges 50 of the header plate thereby provide for a self-closing engagement. The "upper surface", respectively the locking surface 32, of a tab refers to a surface 32 which is also substantially opposed to the direction facing the tubes 14. In addition, each tab 30 preferably has a chamfer 34 connecting the locking surface 32 and a front surface 38 of the tab 30. The "front surface" 38 is a surface of the tab 30 extending along the direction Y at a distal end of the tab 30. The front surface 38 connects the locking surface 32 to the opposite surface 36. As can be further seen in Fig. 4, each tab 30 may be provided with a slightly tapering cross-sectional profile. That is, surface 36 is not parallel to locking surface 32 but inclined such that the front portion 38 of tab 30 has a reduced thickness (in direction Y) compared to the rear portion joining the tank body 22.

[0075] Fig. 6 and 7 respectively schematically illustrate the final assembled state and an intermediate assembled state of the tank body 22 and header plate 40. In an assembled state (Fig. 6) the fixation flanges 50, which are plastically deformable, curve over, respectively bend over, a corner portion 28 of the peripheral border 26, in particular a corner portion 28 of the distal end portion 26.1 / annular end face 26.2. In a pre-assembled state, the mounting flanges 50 curve less steep, as can be derived from Fig. 7, so that the tank body 22 may be positioned / inserted between the fixation flanges 50. During the assembly process, the fixation flanges 50 are deformed and brought to their final form, which can be seen best in Fig. 4-6. That is, fixation flanges 50 are bent towards the peripheral border 26 and meanwhile plastically deformed.

[0076] During assembly, the peripheral border 26 of the tank 20 and the header plate 40, respectively the annular end face 26.2 and the peripheral edge region 44, are aligned in front of one another and moved toward each other along the first direction Y. This forward movement may be caused by a pressure applied to the header plate 40 and / or the tank body 22. The pressure forces the flat (or in embodiments slightly curved) annular end face 26.2 of the peripheral border 26 into contact with the gasket 60.

[0077] Then, the fixation flanges 50, which are initially in a rest position away from the peripheral border 26 of the tank, as illustrated in Fig.7, are bent - by application of an external force, towards the peripheral border 26 of the tank in order to curve over a corner 28 of the annular end face 26.2 and bring the tabs 30 in engagement into the apertures 54. As can be seen in Fig. 4, the aperture 54 has a trapezoidal cross-sectional profile when viewed in an YX plane.

[0078] The dimensions of tabs 30 and apertures 54 are designed to rather narrow gaps / clearance and hence obtain tight engagement, however still permitting the bending / folding of the fixation flanges 50. Fixation flanges 50 are bent to be proximal to the peripheral border 26 and until the tabs 30 are fully engaged into apertures 54. Consequent to this bending, the fixation flanges 50 are plastically deformed and thus remains in the bent configuration, extending somewhat perpendicularly to the central region 42 / peripheral edge portion 44 of the header plate 40 and hence parallel to direction Y. As apparent e.g. from Fig. 4, the tabs 30 are preferably dimensioned such that in the assembled state of the heat exchanger 10, they do not protrude / extend outside the fixation flange 50.

[0079] When the fixation flanges 50 are in their respective final position, the pressure applied on the tank body 22 and header plate 40 may be released, such that the gasket 60 decompresses. Due to the decompression, the gasket 60 applies a force onto the rear side 40.1 of the header plate 40 along the peripheral edge portion 44 as well as to the annular end face 26.2 of the tank body 22, which forces both to move opposite from each other along the first direction Z. This movement may take place as long as the upper surface 32 of the tab 30 is not in contact with the top surface 56 of the aperture 54. As soon as the upper surface 32 contacts surface 56, a retaining force is established between the tab 30 and the fixation flange 50. It may be noted that the configuration is such that even when locking surface 32 abuts against the surface 56 in the aperture 54, the gasket 60 is still in a partially compressed state, so ensure the sealing function at the interface. At the same time the reaction force opposed by gasket 60 pushes apart the header plate 40 and the tank body 22, which maintains the contact between locking surface 32 and surface 56. While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

Claims

1. A heat exchanger (10), in particular for an automotive vehicle, comprising - a core (12) with a plurality of heat exchanger tubes (14) for carrying a fluid, the tubes extending in a first direction, - a tank (20) extending over a tank length along a second direction and to which said heat exchanger tubes (14) are fluidly connected, wherein the tank (20) comprises a body (22) defining a cavity (24) for said fluid, a tank opening (24.1) of said cavity (24) being delimited by a peripheral border (26) extending in the first direction, the peripheral border (26) comprising a distal end portion (26.1) defining an annular end face (26.2) and a fixing portion (26.3) adjacent the distal end portion; - a header plate (40) closing said tank opening, said header plate (40) having a rear side facing the cavity, an opposite front side and peripheral fixation flanges (50) bent rearwardly toward the tank, wherein the header plate is made from a flat metal sheet and comprises, in a central region (42), through-holes (46) surrounded by respective collars (46.1) extending from the rear side toward the tank, the through-holes (46) receiving end portions of said heat exchanger tubes (14), and a peripheral edge portion (44) surrounding the central region (42) and facing the annular end face (26.2) of the tank, the fixation flanges (50) extending from the peripheral edge portion (44); - fixing features (30) in the fixing portion (26.3) configured to cooperate with the fixation flanges (50); - an annular gasket (60) arranged on the rear side of the header plate along the peripheral edge portion (44); characterized in that a variation in thickness along said first direction between the distal end portion (26.1) and fixing portion (26.3) being not greater than + / -25%; the peripheral edge portion (44) is coplanar with the central region (42); the annular gasket (60) is compressed along the first direction between the annular end face (26.2) and the peripheral edge portion (44), rests inwardly against the collars (46.1) at least in the second direction, and is outwardly maintained by the bent fixation flanges (50).

2. The heat exchanger (10) according to claim 1, wherein a distance in the first direction on the front side between the central region (42) and the peripheral edge portion (44) is no more than 1.0 mm, preferably lower than 0.5 mm.

3. The heat exchanger (10) according to claim 1 or 2, wherein the peripheral border (26) further comprises a plurality of recesses (27) inside the cavity to accommodate therein respective header collar portions.

4. The heat exchanger (10) according to any one of the preceding claims, wherein the central region (42) of the header plate (40) further comprises linear ribs protruding rearwardly and arranged between header through-holes.

5. The heat exchanger (10) according to any one of the preceding claims, wherein the annular gasket (60) is cured in place or over-molded on the annular end face of the tank.

6. The heat exchanger (10) according to the previous claim, wherein the peripheral fixation flanges (50) each extend along a respective edge and are disconnected from one another.

7. The heat exchanger (10) according to any one of the preceding claims, wherein the annular gasket (60) has a diameter of less than 3 mm, preferably between 1.0 and 2.8 mm, more preferably between 1.5 and 2.7 mm, and most preferably between 1.8 and 2.5 mm.

8. The heat exchanger (10) according to any one of the preceding claims, wherein the fixing features (30) comprise a plurality of rigid tabs protruding laterally from the fixing portion (26.3) of the peripheral border of the tank, the tabs (30) laterally extending generally in a direction parallel to the plane of the header plate (40), and the fixation flanges (50) of the header plates comprise a plurality of apertures (54) arranged for engaging the tabs therein, wherein the tabs (30) comprise a locking surface (32) on a side facing away from the header plate, the locking surface virtually extending in a first plane crossing a second plane parallel to a rear surface of the peripheral border (26) with a sharp angle (α), whereby the tabs (30) and apertures (54) provide for a self-closing engagement.

9. The heat exchanger (10) according to the preceding claim, wherein the tabs (30) present a hook-like cross-sectional shape; and / or wherein each tab (30) has an outwardly tapering cross-sectional profile.

10. The heat exchanger (10) according to any one of claims 8 to 9, wherein each aperture (54) of the plurality of apertures has a trapezoidal cross-sectional profile.

11. The heat exchanger (10) according to any one of claims 8 to 10, wherein each of the tabs (30) of the plurality of tabs presents a chamfer (34) adjacent to the locking surface and a front surface of a respective tab.

12. The heat exchanger (10) according to any one of claims 8 to 11, wherein the sharp angle (α) is an angle within a range of 3° to 40°, preferably from 5° to 20°.

13. The heat exchanger (10) according to any one of claims 8 to 12, wherein a lateral extension of each tab (30) is at most equal to a wall thickness of the fixation flanges (50).

14. The heat exchanger (10) according to any one of the preceding claims, wherein the tank (20) is made of plastic.

15. The heat exchanger (10) according to any one of the preceding claims, wherein the heat exchanger (10) is a radiator or a charge air cooler.

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