AUTOMOTIVE HEAT EXCHANGER

The invention relates to an automotive heat exchanger. Heat exchangers transfer heat energy from one fluid (or gas) to another fluid (or gas) without mixing the two. Automotive radiators are a common example. Heat from the hot engine water is pumped through the radiator pipes, while air is blown through the radiator tins. The heat energy produced by the engine is transferred via the cooling water to the air, thus keeping the water at the right temperature, to keep the engine from overheating. Essentially automotive radiators are liquid-to-air heat exchangers. Other types of heat exchangers are common in everyday equipment such as boilers, furnaces, refrigerators and air conditioning systems, and are commonly used in a wide variety of industrial, chemical, and electronics processes to transfer energy and provide required heating or cooling. With an automotive heat exchanger is herein understood a heat exchanger designed to be used in automotive vehicles, also known as automobiles. The present invention relates to an automotive heat exchanger, more particular to an automotive heat exchanger of the type comprising a bundle of tubes, and a header part in which the ends of the tubes are introduced into the holes of a plate. The tubes are also known as heat exchange tubes, or heat transfer tubes, as well as cooling pipes or cooling channels. As further heat transfer elements automotive heat exchangers generally comprise fins or corrugated plates, generally made of metal. The tubes and cooling elements are generally stacked together into a larger package and welded or brazed together with the plate comprising the holes, to form a single or unitary heat exchange core. Heat exchange cores are also known under the name of cooler body and are generally made of a lightweight heat conductive metal, such as aluminum. Automotive heat exchangers also comprise manifold bodies having an open face delimited by the header part. Manifold bodies for automotive heat exchanger are also known as end-caps. The manifold body constitutes together with the header part a manifold, also named manifold housing. The end portions of the heat exchange tubes, through which tubes air or other medium (generally water or a water/glycol mixture) to be cooled is passed, are received by the aperture in the manifold body and extend into the manifold housing. An automotive heat exchanger generally comprises 2 manifolds: an inlet manifold, also known as introduction tank, or an outlet manifold, also known as discharge tank. With an inlet manifold is understood a conduit like device used to channel the medium to be cooled into the tubes. With an outlet manifold is understood a conduit like device used to channel the medium after being cooled out of the tubes.

Such a manifold is known from US patent US-5,351 ,751. This patent describes heat exchangers of the type, which are employed in automobiles, for example, as charged air coolers for turbochargers. The known heat exchanger from US-5,351,751 comprises a manifold body in the form of separate tanks, indicated in US-5,351 ,751 with the name manifold, and an heat exchange core. The heat exchange core comprises a header part and heat exchange tubes. The heat exchange tubes are connected at end portions thereof to the header part. The header part and the manifold body define together a manifold, indicated by the words manifold housing. In the heat exchanger in US-5,351 ,751 , the manifold body has side walls with an inwardly facing edge region and an outwardly facing edge region, which engage with the header part. The header part in the heat exchange core comprises a collar, which forms a channel and by which the outwardly facing edge regions of the manifold body are received. The manifold body in US-5,351 ,751 can be made of metal, preferably aluminum, and can be joined to the header part, for example by welding. According to US-5,351 ,751 , it is also possible to apply manifold bodies formed of plastic.

An alternative method for joining the manifold body to the header part is by means of a crimping operation. This method requires an automotive heat exchanger comprising a header part having a collar provided with crimping means, for example crimping claws, and a manifold body comprising a peripheral rim to be received by the crimping claws. This method can be applied for manifold bodies made of metal, and is generally applied for manifold bodies made of plastic.

As described in US-5,351 ,751 the manifold housings in automotive heat exchangers are subject to expansions arising from elevated temperatures and pressures of the medium to be heated or cooled, which render them liable to mechanical failure of the heat exchanger. In particular the pulsating pressures occurring in automotive heat exchangers cause problems. Defects that can occur are, for example, cracks and bursts in the header part, opening of crimping claws, and breakage of weld joints between the heat transfer tubes and the base plate in the header part. Conventional solutions described in US-5,351 ,751 include reinforcement of the manifold bodies or tank parts to resist this expansion by the provision of increased wall thickness, the addition of internal and/or external ribbing, or the addition of internal tie bars which extend between inner walls of the tank. An increase in the header material gauge and the use of thicker crimping claws may also be employed as a means of reinforcement. However, there are a number of problems with these means of strengthening as is also mentioned in US-5,351 ,751. The addition of extra material

for strengthening adds weight and increases the cost of the manifold. It also complicates the tooling, designs, moulds etc., which are required. Use of internal tie bars also complicates the manufacture. Increase in the thickness of the crimping claws requires a larger force and bigger machines for joining the manifold body and the header part, and also requires more space for heat exchanger in the car. In current vehicles, however, the space allocated to the equipment is increasingly limited, and it is found necessary to be able to reduce the space requirement of the heat exchangers, while retaining comparable thermal performance.

The aim of the invention is provide an automotive heat exchanger, which does not have the problems of the conventional heat exchangers, or to a lesser extent, more particularly to provide an automotive heat exchanger, which is less sensitivity to mechanical failure in the header part of the heat exchanger, and which can be produced with limited extra costs and weight, and allows for space savings. This aim has been achieved with the automotive heat exchanger according to the invention, wherein the automotive heat exchanger comprises a plastic insert plate having a plurality of openings the number of which openings is identical to the number of the heat transfer tubes comprised by the heat exchange core, and wherein i) end portions of the heat transfer tubes are received by and extend through the openings of the plastic insert plate and extreme parts of the end portions of the heat transfer tubes have been bended outwardly, thereby forming a pressure tight joint between the plastic insert plate and the header part, ii) the plastic insert plate is fastened to the side walls of the manifold body in such a way that the plastic insert plate has full contact with the side walls, and iii) the manifold body is joined to the heat exchange core only through fastening of the plastic insert plate to the manifold body.

It has surprisingly been found that the automotive heat exchanger according to the invention, wherein the end portions of the heat transfer tubes are received by and extend through the openings of the plastic insert plate and extreme parts of the end portions of the heat transfer tubes have been bended outwardly, thereby mechanically engaging the heat exchange core with the plastic insert plate by means of a pressure tight joint, and wherein the manifold body is joined to the heat exchange core only through fastening of the plastic insert plate to the manifold body is strong enough to withstand the internal pressure, while simultaneously the risk of loss

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of pressure related to mechanical failure of crimpling claws and/or of the base plate is reduced. A further advantage is that the heat exchange core is void of crimping means for joining the manifold body to the heat exchange core, thereby resulting in a significant space saving. Furthermore, the measures according to the invention do not contribute to extensive extra costs and weight, and might even reduce costs and /or weight. Due to the reduced sensitivity for mechanical failure, the increment in dimensions of other parts of the manifold or the header part for reinforcement reasons can be less, in specific cases the dimensions of such other parts may even be reduced or even completely omitted. Furthermore, the plastic insert plate itself can be light weighted and be simply produced.

The use of a plastic insert plate having a plurality of openings the number of which openings being identical to the number of the heat transfer tubes in an automotive heat exchanger is known, and described for example US-6296051-B1. The tubes in the automotive heat exchanger of US-6296051-B1 also have widened end portions. It is noted however, that in the automotive heat exchanger of US-6296051-B1 , the end portions of the heat transfer tubes thrust in and are received by, but do not extend through the openings of the plastic insert plate. More particular, the thickness of the plastic insert plate in US-6296051-B1 is mentioned to be more than the height of the ends. Moreover, the widened end portions are flush-fitted with the openings, but not for mechanically engaging the heat exchange core with the plastic insert plate, since the insertion plate is held in position by the peripheral edge of the manifold box. Furthermore, the manifold body in the automotive heat exchanger of US-6296051-B1 is joined to the header part is by means of a crimping operation. For this purpose the header part is provided with a manifold plate comprising crimping tongues, which resemble teeth and notches. The plastic insert plate in US-6296051-B1 is used as a lateral stop for the rim of the manifold body so that the rim is held lateral during the crimping operations. Otherwise the manifold body would move inward under the effect of the high pressures, which are exerted during crimping operations. US-6296051-B1 neither describes nor suggests the measures according to the present invention, and neither teaches nor suggests the effects thereof as according to the invention

With full contact is herein understood that the plastic insert plate is in contact with the side walls of the manifold body along a closed line. In other words there is no opening between the plastic insert plate and the manifold body.

Such a full contact can be achieved, for example, with a plastic insert plate having a planar cross section in plane with the plastic insert plate having an outer

circumference similar to or identical to an inner circumference of a planar cross section of the manifold body at or near the edge region of the side walls of the manifold. Where the said outer circumference of the plastic insert plate is identical to the said inner circumference of the manifold, the full contact can be accomplished, for example by insertion and clamping of the plastic insert plate in the manifold or by welding of the plastic insert plate onto the manifold. Where the said outer circumference of the plastic insert plate is similar to the said inner circumference of the manifold, the full contact can be accomplished, for example by fastening of the plastic insert plate to the manifold body by clamping and completing the full contact with the use of an adhesive. The effect according to the invention, that the inventive automotive heat exchanger can withstand the internal pressure, meanwhile reducing the risks of loss of pressure related to mechanical failure of other parts in the heat exchanger, requires that a pressure tight joint between the plastic inset plate and the header part. This pressure tight joint can be achieved in various manners, e.g. with the plastic insert plate having a sealing contact with the end portions of the tubes. It can also be achieved with a sealing agent or sealing body between the plastic insert plate and the base plate is used. Preferably, a sealing contact between the plastic insert plate and the end portions of the tubes is combined with a sealing agent or sealing body between the plastic insert plate. Suitably as the sealing agent an adhesive is used. Also suitably as a sealing body a rubber gasket is used.

In the automotive heat exchanger according to the invention, the plastic insert plate may be fastened to the side walls of the manifold body by any means that is suitable for fixing a plate-like body to a plastic body with a hollow-shape body. Suitable means are, for example, mechanical bonds, such as clamping and snapping, for example by use of a snap fit or a click mechanism using undercuts, or other seal mechanism, and chemical bonds, such as an adhesive bond, with the use of an adhesive or using a weld line, for example applied by vibration welding or laser welding, or any combination thereof. Preferably, a combination of a mechanical bond and a chemical bond is used. The advantage thereof is that the manifold is even stronger and can withstand larger pressure variations.

The mechanical bonds and/or chemical bonds are optionally combined with a sealing body or a sealing agent to provide for an even better seal of the bond or bonds.

The plastic insert plate in the automotive heat exchanger according to the invention, preferably has a peripherally located elevated circumferential rim protruding in the direction of the base wall of the manifold body. The advantage of the said rim is that the manifold gets stiffer near the edge regions of the manifold body and the heat exchanger wherein the manifold is used becomes less sensitive for mechanical failure. With the term "peripherally located" is herein understood that the rim is located near or at the edge of the plastic insert plate.

The plastic insert plate with the said rim may be fastened to the side walls of the manifold body for example, through contact of the said rim with the peripheral edge region of the side walls. In this embodiment the rim forms an extension of the side walls of the manifold body. In fact, the height of the rim may be about as high as or even higher than the height of the side walls. The plastic insert plate with such a high rim can be visualized as having a trough shape. In a particular situation the height of the rim may be such that the height of the side walls can be reduced by large, while maintaining sufficient volume for the manifold housing. In the extreme form thereof, the manifold has the form of a box, wherein the plastic insert plate with the rim forms the base part with bottom and walls and the manifold body having side walls the height of which is reduced to the minimum, forms the lid of the box. The advantage of this embodiment, in particular where the height of the rim is larger, is that the sensitivity of the heat exchanger for mechanical failure is even further reduced.

In an alternative embodiment, either the rim is received by and abutted against the inwardly facing edge regions of the side walls of the manifold body, or the side walls of the manifold body are received by the rim and the rim is abutted against the outwardly facing edge regions of the side walls. Preferably, the side walls of the manifold body are received by the rim, and the rim is abutted against the outwardly facing edge regions of the side walls. The advantage thereof is that the heat exchanger can also withstand higher pressure.

Optimally a combination of these embodiments is applied. This can be achieved with the plastic insert plate having the said rim, wherein the rim has a peripheral edge region with an inwardly or outwardly facing cut-out for receiving the edge region of the side walls of the manifold body and abutting to respectively the outwardly or inwardly edge region of the side walls. Alternatively, or in combination therewith, the side walls of the manifold body have a peripheral edge region with an inwardly or outwardly facing cut-out for receiving the edge region of the rim. Optionally, in addition an adhesive and/or a weld is used for better

engagement of the plastic insert plate with the manifold body. Also optionally, the said rim may be provided with ripple marks or other surface modifications for better engagement of the plastic insert plate with the manifold body.

The openings in the plastic insert plate preferably have a size, which fits closely around the heat transfer tubes to be received by the openings. For that purpose the openings shall have a smallest inner circumference identical or similar to the outer circumference of a cross section of the end portions of the heat transfer tubes. An advantage of the plastic insert plate with such closely fitting openings is that the heat transfer tubes are better fixed in their positions and mechanical failure due to the heat transfer tubes breaking loose out of their positions is reduced. A further advantage is that the plastic insert plate can be joined to the header part providing for an even stronger construction of the heat exchanger.

Also preferably, the openings of the plurality of openings have an at least partially tapered shape, such that the openings get wider when viewed in the direction of the base wall of the manifold body. The openings with said tapered shape have the advantage that the flow of the incoming or outgoing medium to be heated or cooled is even less disturbed, thus allowing for a reduced pressure fall inside the manifold.

The tapered shape may be any shape with which the openings get wider when viewed in the direction of the base wall. The tapered shape suitably is, for example, a shape with a linear slope having a fixed inclination, or a curved shape having a variable inclination or a combination thereof. The openings having an at least tapered shape preferably have an inner side with a fixed or variable inclination between 5 and 80°, more preferably between 20 and 70°, or 30 and 60°, most preferably around 45°.

It is also noted that the effect of the increased pressure can already be obtained with outwardly bending of the extreme parts with relative short end portions, as are used in conventional heat exchangers, for example 1-2 mm. However, it may be preferred to use longer end portions, for example 3-10, preferably 4-5 mm long, to obtain a better sealing and fastening of the plastic insert plate to the header base plate.

The effect of the outwardly bended end portions of the heat transfer tubes allowing higher internal pressure, can be further enhanced with the embodiment, wherein the openings have an inner surface and the end portions of the heat transfer

tubes have an outer surface and the plastic insert plate is sealed with a sealing agent applied between the inner surface and the outer surface. This embodiment has the advantage that an even higher internal pressure can be applied.

In the automotive heat exchanger according to the invention, the plastic insert plate and manifold body can be made of various materials. The plastic insert plate and the manifold body may be made of the same material, although these parts may also be made of different materials.

The plastic insert plate may be made of a thermoset polymer composition or a thermoplastic polymer composition, preferably a thermoplastic polymer composition. The material from which the manifold body is made may be a plastic material of the same polymer composition as the plastic insert plate or of a different polymer composition, or of another material, in particular a metal, for example, aluminum. The manifold body is also preferably made of a thermoplastic polymer composition. The thermoplastic polymer composition from which the plastic insert plate and/or the manifold body are made comprises at least one thermoplastic polymer. Suitable thermoplastic polymers that can be used in the thermoplastic polymer composition are, for example, polyesters and polyamides. Examples of suitable polyamides are aliphatic polyamides, such as polyamide-6, polyamide-6,6 and polyamide-4,6 and semi-aromatic polyamides like polyamide-6, T, polyamide-9,T, copolyamides, such as polyamide-6, 6/6,T, and polyamide-6, 6/6, 1. and blends and further copolyamides of these polyamides.

More preferably, the polyamide is a semi crystalline (aliphatic or semi- aromatic) polyamide with a melt temperature (Tm) of at least 230 ⁰ C, or an amorphous semi-aromatic polyamide with a glass transition temperature (Tg) of at least 230 ⁰ C.

Preferably the said Tm or Tg is at least 240 ⁰ C, more preferably at least 260 ⁰ C, or even 280 ⁰ C, and may be as high as 330 ⁰ C or even higher.

The thermoplastic polymer composition may comprise, next to the at least one thermoplastic polymer, one or more additives. Additives that can be used may be any additives known in the art that is suitable for use in thermoplastic polymer compositions used for manifolds. Suitable additives include, for examples, inorganic fillers, reinforcing agents, such as glass fibres, nucleating agents, stabilizers, processing aids, pigments, etc. The optimal amount of additive or combinations thereof can in principle be determined experimentally by a person skilled in the art through

systematic research. Preferably, the amount of the additives is such that the added additive or additives do not adversely affect the molding properties of the polymer.

The plastic insert plate as well as the manifold body is also preferably made of a thermoplastic polymer composition with a heat distortion temperature (HDT) of at least 240 ⁰ C. Preferably the HDT is at least 25O ⁰ C, more preferably at least 270 ⁰ C, ore even 290 ⁰ C.

The thermoplastic polymer composition also preferably is a laser- weldable composition. Fastening of the side walls of the manifold body with the plastic insert plate by means of laser welding is suitably combined with a fastening step wherein either the plastic insert plate, or the peripherally located elevational rim thereof, is inserted into the manifold body, or vice versa the edge region of the manifold body is inserted in the peripherally located elevational rim of the plastic insert plate. In this respect it is preferred that the plastic insert plate is made of a thermoplastic polymer composition with a different absorption behaviour with respect to laser light than the material used to form the manifold body, and preferably the part that is receiving the inserted part is made of a thermoplastic polymer composition that is shows a low absorption of, or is even transparent in respect of the laser light used in the laser welding process, while the part that is inserted is made of a thermoplastic polymer composition that absorbs the laser light used in the laser welding process. The advantage of combining fastening of the plastic insert plate and the manifold body by insertion and laser welding, is that the resulting automotive heat exchanger construction has a better mechanical strength and has a better resistance against pressure variations.

The thermoplastic polymer composition from which the plastic insert plate and/or the manifold body are made, suitably is an injection mouldable composition and the plastic insert plate and/or the manifold body are likewise suitably made by an injection moulding process.

The automotive heat exchanger according to the invention may be any heat exchanger that is designed for use in automobiles and comprising any medium to be cooled. Suitably the heat exchanger is an oil cooler, an air cooler, such as a charge air cooler for turbo engines, or a radiator. In the automotive heat exchanger according to the invention the manifold with the plastic insert plate may be an inlet manifold, as well as an outlet manifold, or both. Preferably, the manifold is part of a charge air cooler with the manifold being an air inlet manifold and/or an air outlet

manifold.

The invention also relates to a process for making an automotive heat exchanger comprising a heat exchange core, a plastic insert plate and a plastic manifold body as described above. The inventive process comprises first (i) inserting the end portions of the heat transfer tubes of the heat exchange core into, and extending through the openings in the plastic insert plate, (ii) bending outwardly the extreme parts of the end portions of heat transfer tubes, thereby forming a pressure tight joint between plastic insert plate and header part, and then (iii) fastening the plastic insert plate to the side walls of a manifold body at or near the edge region of the side walls.

This process has the advantages of the automotive heat exchanger according to the invention described above.

The outward bending in step (ii) may be performed, for example with a thorn.

Optionally the fastening of the plastic insert plate and header part in step (i) and (ii) in this process is combined with the use of a sealing body or sealing agent applied between the plastic insert plate and a base plate comprised by the heat exchange core. Suitably, the sealing body is a gasket, for example a rubber gasket. The fastening of the plastic insert plate to the side walls of a manifold body in step (iii) may be carried out by any process that is suitable for that purpose, for example, by clamping, snapping, adhesive bonding or welding, or any combination thereof, as described herein above.

The heat exchanger that is made with the inventive process preferably is a automotive heat exchanger according to the invention or any of the preferred embodiments thereof.

The following figures illustrate the invention. FIG. 1. Schematic 3-dimensional view of a heat exchange core. FIG. 2. Schematic 3-dimensional view of assembly components for an automotive heat exchanger according to the invention.

FIG. 3. Schematic 3-dimensional view of assembly components for an automotive heat exchanger according to the invention.

FIG. 4. Side elevational view of a manifold body for use in an automotive heat exchanger according to the invention. FIG. 5. Cross-sectional view of a manifold body for use in an automotive heat

exchanger according to the invention.

FIG. 6. Schematic 3-dimensional view of the steps of an assembly process for the assembly of an automotive heat exchanger according to the invention. FIG. 7. Side-elevational view of a manifold body with a edge region comprising a cut- out, and a plastic insert plate for receiving the same.

FIG. 8. Cross-sectional view of the manifold body and plastic insert plate of Fig. 7. FIG. 9. Cross-sectional view of the manifold body and plastic insert plate of Fig. 7 assembled according to the invention with heat transfer tubes.

FIG. 1 shows a schematic 3-dimensional view of a heat exchange core (2). The heat exchange core comprises a package of a plurality of heat exchange tubes (4) and cooling fins (6), which heat exchange tubes (4) and cooling fins (6) are alternately stacked and are held together by plates (8), which plates are known as base plates or end plates, as well as header plates. The heat exchange core (2) comprises two header parts (10), which comprise the base plates (8) and end portions (12) extending out of the base plates (8).

FIG. 2 shows a schematic 3-dimensional view of assembly components from which an automotive heat exchanger according to the invention can be assembled. The components comprise a heat exchange core (2), a sealing body (14), a plastic insert plate (16) and a manifold body (18). The manifold body (18) comprises side walls (20) and a base wall (22).

FIG. 3 shows a schematic 3-dimensional view of the same assembly components of Fig. 2, seen from a different angle. The components comprise the heat exchange core (2), which is only shown in part, the sealing body (14), the plastic insert plate (16) and the manifold (18). The plastic insert plate (16) comprises a plurality of openings (24) the number of which openings is identical to the number of the heat transfer tubes (4) comprised by the heat exchange core (2). The plastic insert plate (16) further comprises a peripherally located elevated circumferential rim (26) protruding in the direction of the base wall (22) of the manifold body (18).

FIG. 4 shows a side elevational view of a manifold body (18) for use in an automotive heat exchanger according to the invention. The manifold body (18) comprises side walls (20) and a base wall (22). The side walls (20) comprise an edge region (28), opposite to the base wall and comprising a peripheral edge region (30). The peripheral edge region (30) forms an aperture (not shown) for receiving end portions of heat transfer tubes of a heat exchanger core (not shown). FIG. 5 shows a cross-sectional view of the manifold body for use in

an automotive heat exchanger according to the invention of Fig. 4 in the plane Y-Y'. The manifold body (18) comprises side walls (20) and a base wall (22). The side walls (20) comprise an edge region (28), opposite to the base wall and comprising a peripheral edge region (30), an inwardly facing edge region (32) and an outwardly facing edge region (34).

FIG. 6 shows a schematic 3-dimensional view of the steps (Fig. 6a-6f) of an assembly process for the assembly of an automotive heat exchanger according to the invention.

Fig 6a shows part of a heat exchange core (2) comprising one header part (10), which comprises one plate (8) and end portions (12) of heat exchange tubes (4) extending out of the plate (8).

Fig 6b shows the same part of a heat exchange core (2) and a sealing body (14) to be placed around the end portions (12) of heat exchange tubes (4) and to be abutted against the plate (8). Fig. 6c shows the same part of a heat exchange core (2) with the sealing body (14) placed around the end portions (12) of heat exchange tubes (4) and abutted against the plate (8). Fig. 6c also shows a plastic insert plate (16) comprising a plurality of openings (24) and a peripherally located elevated circumferential rim (26) to be fastened to the heat exchange core (2). Fig. 6d shows the same part of a heat exchange core (2) with the sealing body (14) (not visible) of Fig. 6c, and the plastic insert plate (16) positioned against the heat exchange core (2), such that the end portions (12) of heat exchange tubes (4) are received by and extend through the openings of the plastic insert plate (16). Fig 6d also shows a number of thorns (36), by which extreme parts of the end portions (12) of the heat transfer tubes (4) can be bended outwardly.

Fig. 6e shows the part of a heat exchange core (2) with the sealing body (14) (not visible) of Fig. 6c, and the plastic insert plate (16) positioned against the heat exchange core (2), wherein the extreme parts (38) of the end portions (12) of the heat transfer tubes (4), which extend through the openings of the plastic insert plate (16), have been bended outwardly. Fig 6e also shows the manifold body (18) to be fastened to the plastic insert plate (16).

Fig. 6f shows the heat exchange core (2) with the sealing body (14) (not visible), the plastic insert plate (16) fastened to the heat exchange core (2) by means of the outwardly bended extreme parts (38) (not visible), and the manifold body (18) fastened to the plastic insert plate (16).

Fig. 7 shows a side elevational view of a manifold body (18) comprising a cut-out (40) at the side of the outwardly facing edge region (34), and a plastic insert plate (16) comprising a peripherally located elevated circumferential rim (26) with a cut-out (42) (not visible) at the inner side for receiving the same. Fig. 8 shows a cross-sectional view of the manifold body and plastic insert plate of Fig. 7 in the plane Y-Y'. The manifold body (18) comprises a cut-out (40) at the side of the outwardly facing edge region (34). The plastic insert plate (16) comprises openings (24) for receiving heat exchange tubes (4) (not shown) and a peripherally located elevated circumferential rim (26) a cut-out (42) at the inner side of the peripherally located elevated circumferential rim (26).

Fig. 9 shows a cross-sectional view of the manifold body and plastic insert plate of Fig. 7 in the plane Y-Y' and assembled according to the invention with heat transfer tubes. The manifold body (18) comprises a cut-out (40) at the side of the outwardly facing edge region (34). The plastic insert plate (16) comprises openings (24) and a peripherally located elevated circumferential rim (26) a cut-out (42) at the inner side of the peripherally located elevated circumferential rim (26). The edge region of the manifold body (18) with the cut-out (40) is received by and abutted against the peripherally located elevated circumferential rim (26) with the cut-out (42) of the plastic insert plate (16). The assembly further comprises heat exchange tubes (4), which have been received by and end portions of which extend through the openings (24), and extreme parts of the end portions have been bended outwardly (38).

The invention is further elucidated with the following examples.

Preparation of the materials For the experiments use was made of a heat exchange core of a commercial type of heat exchanger, which in its standard form comprises a sealing edge of 3.6 mm wide and crimping claws of 6.5 mm wide. Without further changing the construction of the heat exchange core, two central parts and were taken out of the heat exchange core comprising three heat transfer tubes, two intermittent layers of cooling fins, and two small parts of base plate, one at each end of the tubes. The size of the cut-out parts of base plate was about 45 x 45 mm. The heat transfer tubes had end portions of about 2 - 2.5 mm length extending out from the parts of base plate.

Four plastic insert plates were prepared by starting with plastic plates, each 80 x 80 mm and 2 mm thick. The plastic of which the plates were made was Stanyl TW200F6, a polyamide-4,6 moulding composition of DSM, The Netherlands. In

each of the plates three slit like openings with the dimensions of the heat transfer tubes were made. The openings were tapered circumferentially with a slope of 45°.

Furthermore, four aluminum plates, each 80 x 80 mm and 2 mm thick, were used. Two of these aluminum plates were provided with a centrally placed valve for connection to a pressure unit. The aluminium plates are used here as a model shape for the manifold body.

Preparation of the models

Experiment 1

Two of the plates with the tapered openings were slided over the ends of the heat transfer tubes of one of the two heat exchange core parts and positioned against the parts of base plate, one plate at each side of the part, thus forming a first assembly. This first assembly was placed in an oven at 200 ⁰ C for 30 minutes. After that the heat transfer tubes were provided with a flange by bending outwardly the extreme ends of the pipes. Against the outer side of the plastic insert plates aluminum plates, one with and one without a valve were fixed with small bolds and nuts and some sealant in the outer regions. The resulting part is herein below indicated as assembly A.

Experiment 2

The whole procedure of Experiment 1 was repeated with the second heat exchange core part, except that between the base plate and the plastic insert plate a adhesive was applied prior to the positioning of the plastic insert plate against the base plate. The adhesive that was used was Loctite 5366, a silicon based adhesive of the Henkel Group, USA. The resulting part from this procedure is herein below indicated as assembly B.

Pressure tests Assemblies A and B were subjected to two different pressure tests, first to a nitrogen pressure test, then to a water pressure tests. For these tests the valves on the aluminum plates were connected to a nitrogen pump, respectively to a water pump. The pressure in each of the tests was gradually increased and the assemblies were inspected on leakage and other forms of damages.

With assembly A, the nitrogen pressure could be raised up to 2.8 bar without any problem. At 2.8 bar some leakages occurred, but the construction of the assembly itself remained intact.

With assembly B, the nitrogen pressure could be raised up to 3 without any problem. For safety reasons, the test was continued with water pressure. The water pressure could be raised without a problem to 6 bar. At 6 bar some leakages occurred, but the construction of the assembly itself remained intact.

The results for these model experiment show that manifold comprising the model shape for the manifold body fixed to a plastic insert plate and the a plastic insert plate itself fixed to a heat exchange core part, wherein the plastic insert plate is only fixed by means of outwardly bending of the ends of the heat transfer tubes and without using crimping claws or other further means for fixing of the manifold body to the heat exchange core, already high working pressures can be attained, while maintaining the integrity of the construction. It is furthermore shown that by using a sealing agent the working pressures can be further enhanced substantially.