WO2021045370A1

WO2021045370A1 - Coolant/air heat exchanger

Info

Publication number: WO2021045370A1
Application number: PCT/KR2020/008853
Authority: WO
Inventors: Jan Gregus Kollar; Josef LAPCIK; Jakub Motyka
Original assignee: Hanon Systems
Priority date: 2019-09-02
Filing date: 2020-07-07
Publication date: 2021-03-11
Also published as: DE102019123415B4; DE102019123415A1

Abstract

The present invention relates to a coolant/air heat exchanger for a motor vehicle, exhibiting multiple fluid-carrying metal pipes, whose pipe ends are arranged next to one another with spacing, at least one pipe base produced from plastic (1; 1') with mounting holes (12), into which the pipe ends can be mounted and one header (2; 2') produced from plastic with a snap-in locking device, which is formed between the pipe base (1; 1') and can be connected to the pipe base, wherein the snap-in locking device is formed with pipe base clip elements (3; 3a; 3b; 3a'; 3b') arranged on the pipe base (1; 1') and header clip elements (4; 4') arranged on the header (2; 2'), with which a snap-in connection can be created through a mechanical interaction of the individual pipe base clip elements (3; 3a; 3b; 3a'; 3b') and corresponding individual header clip elements (4; 4'), and wherein a seal (11; 11') is produced that guarantees a press fit of the pipe base (2; 2') on the pipe ends and seals off the header (2; 2') against the pipe base (1; 1'), as well as the pipe base (1; 1') against the pipe ends.

Description

COOLANT/AIR HEAT EXCHANGER

The present invention relates to a coolant/air heat exchanger for a motor vehicle.

Coolant/air heat exchangers for dissipating heat from a coolant of a coolant circuit into ambient air that are known from the state of the art are used in so-called high-temperature coolant circuits to dissipate the heat produced by an internal combustion engine. The coolant/air heat exchangers typically consist of a radiator-like core that is created using pipes, fins, side elements and pipe bases made from aluminium. The pipes, fins and side elements that are held in the pipe bases, as well as water tanks (often referred to as headers) form various elements that are combined to create the heat exchanger here. The air that absorbs the heat from the coolant flows along the outside of the pipes and thereby between the pipes. The fins arranged on the outside between the pipes serve to increase the heat transfer surface on the air side and thereby also to improve the heat exchanger performance. The headers are typically sealed against the radiator core, i.e. sealed against the pipes/pipe bases, using EPDM seals.

As is known, connections between pipe bases and headers can be brazed or take the form of plug-in connections. When using a brazing process in a controlled atmosphere, referred to as "controlled atmospheric brazing" (CAB), a matrix of pipes and fins are connected to one another, as well as to pipe bases where necessary, to create a metallic element of a header. Plug-in connections, often referred to as mechanical assembly (MA), do away with welding/brazing of adjacent metal parts and instead employ mechanical assembly of the matrix and the header.

With brazed heat exchangers, the rigid connections between the pipes and the pipe bases created by the brazing process have been proven to be detrimental, particularly in the case of rapid temperature fluctuations, since the material stresses caused by thermal expansion have a negative impact on the service life of the heat exchanger. Mechanical connections, on the other hand, allow a certain amount of play between the pipes and the pipe base, thereby making it possible to equalise the changes in length of the material caused by temperature fluctuations. However, mechanically assembled radiators deliver a lower cooling capacity than brazed units due to the force-locking connections between the pipes and the fins.

It is known from DE 10 2015 113 905 A1 that, when assembling the heat exchanger, the pipes and fins are first brazed without any pipe bases and that the pipe bases are then attached to the pipes using a press fit with seals, whereby a synergy of the production methods of a mechanically assembled radiator and a brazed radiator is used. This produces a flexible connection between the pipes and the header thanks to the nature of the seal. Heat exchangers assembled this way are very resistant to thermal shocks resulting from pronounced temperature changes, which can be attributed to their fundamental ability to equalise the thermal expansion of the pipe in a flexible way. The combination of CAB brazing and plug-in connections when assembling the heat exchanger improves its stability, although it also increases the unit price. Combinations of this kind are also referred to as CAB/MA constructions in the following.

DE 10 2018 111 556 A1 also describes a heat exchanger design that is based on a combination of CAB brazing and mechanical plug-in assembly. This heat exchanger exhibits multiple fluid-carrying metal pipes, which can be arranged next to one another longitudinally in a block. The ends of the metal pipes are arranged next to one another as spaced pipe overhangs here. In addition, this heat exchanger exhibits at least one pipe base constructed from plastic, in which multiple mounting holes are produced. The arrangement of the pipe base mounting holes corresponds to the arrangement of the pipe ends, so that the pipe base can be set down onto the pipe ends, wherein the pipe ends can be mounted in the mounting holes. Alongside the pipe base produced from plastic, a header produced from plastic also represents a key feature of the design. This plastic header can be connected to the pipe base using a snap-in locking device, which is produced between the pipe base and the header, wherein a seal can be positioned between the pipe base and the header to guarantee a press fit of the pipe base on the pipe ends and seal the header against the pipe base, as well as the pipe base against the pipe ends. Use of the plastic header facilitates a potential cost reduction. Alongside improvement in terms of the price level, use of plastic pipe bases and headers opens up new opportunities for header design and also reduces the overall weight.

The object of the invention lies in designing a coolant/air heat exchanger in such a way that, alongside a weight reduction over known coolant/air heat exchangers, a simplification of the connection and thereby the assembly process of the elements to be combined is achieved.

This task is resolved by a coolant/air heat exchanger with the characteristics of claim 1. Further beneficial embodiments are provided in the dependent claims.

The solution according to the invention is a coolant/air heat exchanger for a motor vehicle, exhibiting multiple fluid-carrying metal pipes, whose pipe ends are arranged next to one another with spacing, at least one pipe base produced from plastic with mounting holes, into which the pipe ends can be mounted and a header produced from plastic that can be connected to the pipe base using a snap-in locking device, which is formed between the pipe base and the header. The snap-in locking device is formed with pipe base clip elements arranged on the pipe base and header clip elements arranged on the header, with which a snap-in connection can be established through mechanical interaction of the individual pipe base clip elements and corresponding individual header clip elements. In addition to this, a seal is produced that guarantees a press fit of the pipe base on the pipe ends and seals the header against the pipe base, as well as the pipe base against the pipe ends. For sealing the header against the pipe base, a sealing rib inside the header that runs along the entire perimeter of the header is preferably produced which - when attaching the header to the pipe base using the flexible header clip elements - exerts pressure on the seal and guarantees the tightness of the inner chamber produced by the pipe base and the header along the entire perimeter of the header.

The approach, applied according to the invention and generally already known, of connecting the pipe base to multiple pipes without use of a brazed connection, but rather using a flexible connection comprising pipe, seal and pipe base, opens up numerous opportunities for optimisation in terms of the material and the construction of the pipe base. The plastic pipe base facilitates a significant weight reduction over a conventional pipe base produced from aluminium. However, the plastic pipe base not only opens up opportunities in terms of a new approach for designing the pipe base itself, but also for the header connected to the pipe base.

The header clip elements are preferably each designed in such a way that they exhibit a snap-in connection opening, wherein the corresponding pipe base clip elements are each produced in the form of nose-like projection. With the snap-in connection, each header clip element then wraps around the corresponding nose-like pipe base clip element with the edge of the snap-in connection opening.

According to an embodiment of the invention, the pipe base clip elements that are arranged along the long sides of a longitudinally constructed pipe base are aligned differently than the pipe base clip elements that are arranged on the shorter sides. For example, the pipe base clip elements that are arranged along the long sides of the longitudinally constructed pipe base can be constructed as nose-like projections that start from an edge of the pipe base on the longitudinal side and point inwards, while the pipe base clip elements that are arranged along the shorter sides of the longitudinally aligned pipe base can be constructed as nose-like projections that each start from an edge of the pipe base on the shorter side and point outwards.

Alternatively, the pipe base clip elements that are arranged along the long sides of a longitudinally constructed pipe base can be constructed as nose-like projections that start from a pipe base side wall on the longitudinal side and point outwards, while the pipe base clip elements that are arranged along the shorter sides of the longitudinally produced pipe base can also be constructed as nose-like projections that each start from an edge of the pipe base on the shorter side and point outwards.

According to another advantageous embodiment of the invention, pass-through openings are produced for at least some of the plurality of header clip elements in edge areas of the pipe base , into which header clip elements can be introduced, wherein the corresponding pipe base clip elements are positioned below the level of the pass-through openings. According to an advantageous embodiment, the pass-through openings are each produced exclusively on the longitudinal sides of the pipe base.

The plastic clip elements need to be sufficiently resistant to handle the operating conditions and, at the same time, exhibit enough flexibility to facilitate installation and in particular the mechanical snap-in connection. The optimum clip element length of the header clip elements is in the range from 7 to 25 mm. The optimum clip element thickness of the header clip elements is in the range from 0.4 to 2.4 mm.

The plastic pipe base and the seal do not necessarily have to produced in the form of separate components, as is the case with the familiar CAB/MA constructions. Instead, the seal can be applied to the pipe base or the header using an injection moulding process. In particular, a two-component seal can be applied directly onto the pipe base using a composite injection moulding process. Using injection moulding to produce a two-component composite seal results in lower complexity of the components and simplifies the assembly process. However, it is still possible to use a separate seal, preferably an EPDM seal, between the pipe base and the header as an alternative or additional seal.

In the compression area between the pipe base and the header, the seal should preferably be produced thinner as it gets closer to the adjacent side wall of the pipe base. This ensures that sufficient space is provided for the seal. It also prevents the force that is generated by the seal after compression from increasing unduly and thereby negatively impacting the overall stability of the mechanical connection.

The design can also be effectively combined with the idea of a purely mechanically assembled aluminium radiator, referred to as an MAAR radiator in the following. In the following, the differences between the design according to the invention and the design from DE 10 2018 111 556 A1 are explained.

Numerous differences in the design lead to optimisations that have also been confirmed by so-called finite element analyses (FEA) and mould flow analyses (MFA), as well as in component manufacturing operations. Finite element analysis (FEA) is a computerised process that is used to analyse technical applications and sealing components in order to examine their behaviour under various conditions.

The design of the snap-in connection mechanism between the pipe base and the header was changed over known designs in order to facilitate use of reciprocal mechanical connections without the need for plastic welding. The snap-in connection mechanism according to the invention is stronger in comparison with the previous snap-in connection mechanism and exhibits the necessary flexibility for the assembly process.

Yet despite this, it is still possible to incorporate plastic welding points on opposing internal surfaces of the header and the pipe base, arranged with appropriate spacing, which can be used to weld the header and the pipe base to one another.

One particular advantage of the invention lies in the fact that the coolant/air heat exchanger exhibits a plastic pipe base. This heat exchanger is capable of meeting all existing requirements of the special product. A heat exchanger can be manufactured using CAB brazing or simply through mechanical assembly of the heat exchanger (MAAR). For example, the metal pipes and (if necessary) further metallic elements of the heat exchanger can be connected to one another via brazed connections, wherein the plastic pipe base is sealed in the seal and attached to the metal pipes via a press fit. Assembly of the coolant/air heat exchanger can also be based on mechanical connections without the use of brazed connections by the pipe base being sealed off via a press fit in the seal and pressed onto the metal pipes of the coolant/air heat exchanger that are not brazed to one another. The plastic pipe base is beneficial thanks to its lower weight and a seal that can be produced as a two-component composite seal moulding directly on the surface of the pipe base through use of a composite injection moulding process. The following steps of the heat exchanger assembly process are simplified with the new components, in particular by the snap-in connection according to the invention.

Support parts are preferably arranged with spacing on the top of the header in the central section over the longitudinal side of the header. These support parts are intended for application of mounting force when assembling pipe base and header.

Alternatively or in addition, a large number of rubs is arranged at the edges on the top of the header, distributed over its perimeter. These ribs are intended for application of mounting force at the edges of the header.

Advantageously, pipe base underside supports are produced on the underside of the pipe base in order to guarantee support for the pipe base during assembly of the header.

The following effect is achieved through the design according to the invention:

- A lower heat exchanger weight thanks to the lower weight of the plastic pipe base.

- A simpler manufacturing process for the heat exchanger thanks to the two-component seal injection moulding directly on the surface of the pipe base and a simpler connection between pipe base and header using mechanical clip elements rather than the previously common forms of crimp connections.

Further details, features and benefits of embodiments of the invention result from the following description of embodiment examples with reference to the accompanying drawings.

These display the following:

Fig. 1: The design of a connection between a header and a pipe base as per the state of the art.

Fig. 2A: A pipe base and a header as separate parts prior to mechanical assembly.

Fig. 2B: The pipe base and the header as parts assembled via a snap-in connection.

Fig. 3A: A perspective view of a corner area of the pipe base.

Fig. 3B: A perspective internal view of the corner area of the header.

Fig. 3C: A perspective view of the upper side of the pipe base that faces the header.

Fig. 4: A schematic representation of the mechanical installation of the header on the pipe base.

Fig. 5A: A perspective view of the pipe base with a view of its underside.

Fig. 5B: A schematic representation of the installation of the header on the pipe base.

Fig. 6A: The cross-section of a snap-in connection between pipe base and header as per the state of the art, shown with results of an FEA analysis.

Fig. 6B: The cross-section of a snap-in connection according to the invention between pipe base and header, shown with the results of an FEA analysis.

Fig. 7A: The schematic representation of a header clip element with rectangular surface and oval hole.

Fig. 7B: A side view of the header clip element with statement of the thickness.

Fig. 8A: Assembly of the pipe base and the header with various clip elements on the long and the short side of the pipe base and the header.

Fig. 8B: A sectional view of the pipe base and the header, as well as the seal between pipe base and header.

Fig. 9: Detailed view of the snap-in connection of the pipe base and the header.

Fig. 10A: The design of the pipe base and the header according to a version I.

Fig. 10B: The design of the pipe base and the header according to a version II.

Fig. 11A: The pipe base and the header as parts assembled via a snap-in connection according to version I.

Fig. 11B: The pipe base and the header as parts assembled via a snap-in connection according to version II.

Fig. 12A: The design of the pipe base and the header according to version II,

Fig. 12B: The pipe base and the header as parts assembled via a snap-in connection according to version II.

Fig. 13A: A perspective view of the pipe base with a design according to version II with a view of its underside.

Fig. 13B: A schematic representation of the installation of the header on the pipe base using clip elements according to version II.

Fig. 14A: A perspective view of a corner area of the pipe base according to version II.

Fig. 14B: A cross-section of the snap-in connection between the pipe base and the header according to version II.

Fig. 14C: A perspective view of a corner area of the pipe base and header assembly according to version II.

Fig. 15A: Another perspective view of a corner area of the pipe base and header assembly according to version II.

Fig. 15B: Sectional view of the pipe base and the header, as well as the seal according to version II.

Fig. 1 schematically shows the design of a connection between a header A and a pipe base B that corresponds to the state of the art from DE 10 2018 111 556 A1, wherein the header A and the pipe base B are each produced from plastic. A seal C is introduced between the pipe base B and the header A and guarantees a press fit of the pipe base B on pipe ends D. It also seals the header A against the pipe base B, as well as the pipe base B against the pipe ends D. The header A is connected to the pipe base B using a snap-in locking device, which is formed with clip elements E that are arranged on the header A, as well as snap-in connection openings F that are arranged opposite these clip elements E in the pipe base B. On their lower end, the clip elements E exhibit lugs G that project out of the snap-in connection openings F when snapping into place on the underside of the pipe base B and thereby reach under the pipe base at the edges of the respective snap-in connection opening F.

The lower part of Fig. 1 also contains a detailed excerpt in the form of a cross-section that shows a section of the snap-in connection between the header A and the pipe base B, as well as the seal, with focus on an inner sealing rib H, via which the header A is sealed against the pipe base B using the seal C. The sealing rib H is produced as an inner rib H that stretches over the entire perimeter of the header A and - when attaching the header A to the pipe base B using the flexible clip elements E - exerts pressure on the seal C and thereby guarantees tightness of the inner chamber formed by the pipe base and the header A over the entire perimeter of the header A. The plastic pipe base B and the seal C take the form of separate parts here.

In contrast to this familiar design, with a new design of the heat exchanger according to the invention it was possible to achieve improvements in various areas in terms of a stronger mutual connection between the pipe base and the header, as demonstrated using finite element analyses (FEA).

Finite element analysis, referred to as FEA in the following, is a computerised process that is used to analyse technical applications and sealing components in order to examine their behaviour under various conditions.

The following figures show an improved design with a detailed description. Two different embodiments of the design according to the invention are shown, wherein both embodiments represent the same inventive solution with slightly different designs. A first embodiment also contains plastic welds in certain sections as optional characteristics.

Important dimensional parameters are described with specification of the particularly preferred ranges.

Fig. 2A shows a pipe base 1 and a header 2 as separate parts prior to mechanical assembly in a perspective view, while Fig. 2B shows the pipe base 1 and the header 2 as parts assembled via a snap-in connection in a combination of cross-section and internal view of the header 2. The pipe base 1 exhibits snap-in connection elements that are arranged with even spacing around the perimeter of the pipe base in the form of pipe base clip elements 3, while the header 2 exhibits snap-in connection elements arranged with even spacing around the perimeter of the header in the form of header clip elements 4. The pipe base clip elements 3 and the header clip elements 4 are constructed in such a way that they can interact with one another mechanically and thereby establish a reliable mechanical snap-in connection between the pipe base 1 and the header 2. Here, a new design of

clip elements

3, 4 is introduced for the snap-in connection between pipe base 1 and header 2 in comparison with the state of the art shown in Fig. 1.

As shown in Fig. 2A, the header clip elements 4 are constructed lengthwise in the vertical direction, which corresponds to the assembly direction or the direction in which the assembly force is applied, and thereby arranged around the perimeter of the header, positioned with even distribution on the underside of the header like a picket fence. Each header clip element 4 exhibits a snap-in connection opening 5 in the form of a vertically oriented oval hole 5. Corresponding to this, the pipe base clip elements 3 are produced in the form of nose-like projections. Each nose-like pipe base clip element 3 exhibits a lead-in chamfer 7 that starts from a base (in the embodiment shown from the edge of the pipe base 6) and transitions via a flattened section 8 to a lower snap-in area 9, which is aligned horizontally, i.e. approximately vertically to the base, starting from the flattened section 8. However, since the nose-like pipe base clip element 3 as per the shown embodiment clearly stretches vertically well into the section below the edge of the pipe base 6, the lower snap-in surface 9 and that of the opposite end to the flattened section 8 are also located well below the edge of the pipe base 6.

During assembly, the elastic header clip elements 4 are guided over the lead-in chamfers 7 and the flattened section 8 until they each snap into position after reaching the lower snap-in surface 9, wherein the header clip element 4 reaches around the corresponding nose-like pipe base clip element 3 with the edge of the snap-in connection opening 5.

In the embodiment shown, the pipe base clip elements 3a on the short sides of the pipe base 1 differ in terms of their positioning and alignment from the pipe base clip elements 3b on the longer side of the essentially rectangular perimeter of the pipe base 1. One thing that both forms of pipe

base clip elements

3a, 3b have in common is that they are arranged at the edge of the pipe base 6.

The pipe base clip elements 3a, which are arranged on the shorter side of the pipe base 1 with equal spacing in the embodiment shown in Fig. 2A, are produced as nose-like projections that point outwards from one of the shorter sides 6a of the edge of the pipe base 6. On the other hand, the also nose-like pipe base clip elements 3b on the longer side of the pipe base 1 point inwards, starting from the longer side 6b of the edge of the pipe base 6. In addition to this, pass-through openings 10 for routing through the header clip elements 4 arranged on the long side 2b of the header 2 are located above the pipe base clip elements 3b on the longer side of the pipe base 1. This means that one pass-through opening 10 for a header clip element 4 is located above each pipe base clip element 3b. During assembling, the header clip element 4 is first routed through the pass-through opening 10 before it can enter the snap-in connection with the pipe base clip element 3b in the way described above.

Fig. 2B shows the fitted snap-in connection between header clip elements 4 and corresponding pipe base clip elements 3b on the longer side of the pipe base 1. The header clip elements 4 reach around the pipe base clip elements 3b, which are produced as inward-facing nose-like projections. Prior to this, the elastic header clip elements 4 were each pressed with their outer side over the inward-facing lead-in chamfers and the flattened section of the corresponding pipe base clip element 3b until they snap into position.

With this kind of snap-in connection, the pipe base 1 and the header 2 rely exclusively on this mechanical connection for their assembly. However, there is also the option of establishing a connection between the pipe base 1 and the header 2 via plastic welding in certain areas.

Another optional characteristic involves injection moulding a seal 11, preferably a two-component seal 11, directly on the pipe base 1. However, it is still possible to use a separate seal, preferably an EPDM seal, between the pipe base 1 and the header 2 as an alternative or additional seal.

Fig. 3A shows a perspective view of a corner area of the pipe base 1, while Fig. 3B shows the internal view of a corner area at the transition from the shorter side to the longer side of the header 2 with the header clip elements 4 that each exhibit an oval hole as snap-in connection opening 5 and are arranged like a picket fence. Fig. 3C contains a perspective view of a part of the upper side of the pipe base that faces the header 1 with a view to the mounting holes 12 that are already visible in Fig. 3A for the pipe ends not shown, as well as with a view to the pass-through openings 10 for guiding through the header clip elements 4 on the long side of the header 2 shown in Fig. 3B.

The concept of the connection between pipe base 1 and header 2 is primarily based on a mechanical snap-in connection using the

corresponding clip elements

3, 4. As already mentioned, however, plastic welding represents an optional method for reinforcing the connection between pipe base 1 and header 2. As can be seen when examining Fig. 3A, Fig. 3B and Fig. 3C together, plastic welding points 13 that are arranged with even spacing on the pipe base 2 in the form of slots 13 and corresponding plastic welding points 14 that are arranged with even spacing on the header 2 in the form of longitudinal projections 14 that fit in the slots 13 are also provided. For the connection with plastic welding, each slot 13 is located opposite a longitudinal projection 14, so that the pipe base 1 and the header 2 can be welded to one another at precisely these points.

The slots 13, as plastic welding points 13 of the pipe base 1, are positioned in such a way that not the mounting holes 12, but rather the bridges 15 of the pipe base 1 between the mounting holes 12 for the pipe ends, are located behind them. The bridges 15 thereby guarantee the necessary hold for the welding.

Fig. 4 shows a schematic representation of the mechanical assembly of the header 2 on the pipe base 1. During assembly of the pipe base 1 and the header 2, a force is applied to the top of the header 2. Supporting parts 16 in the form of crossing ribs are formed on the top of the header. Their crossing points 17 are arranged in the central section and distributed over the longitudinal side of the header 2. The supporting parts 16 can be used for application of the mounting force, which is marked with thick arrows 18. To achieve a more even force distribution, a large number of smaller ribs 19, which are arranged at the edges on the top of the header 2 and distributed over its perimeter, are used to apply the force, wherein this mounting force application is marked by the thinner arrows 20. The mechanical assembly is completed when all

clip elements

3a, 3b, 4 have snapped into position, as described above.

Fig. 5A shows a perspective view of the pipe base 1 with a view of its underside 21. Here, pipe base underside supports 22 are provided on the underside 21 in order to guarantee support during mounting of the header 2 to the pipe base 1, which is shown schematically in Fig. 5B. A high compressive force, the mounting force 18 indicated by the arrows, must be applied here during the process of mounting to the header 2. The pipe base underside supports 22 each exhibit an essentially T-shaped profile in terms of cross-section and a T-shaped support surface 23 here.

The redesigned snap-in connection between pipe base and header with regard to the clip elements was subjected to a strength and deformation test via FEA analysis and compared in this regard with the version of the snap-in connection known from DE 10 20112 111 556 A1 and presented in Fig. 6A as a cross-section. A cross-section of a snap-in connection according to the invention between pipe base 1 and header 2 is presented in Fig. 6B. The results of the FEA analyses are graphically visualised in Figs. 6A and 6B and also included in a comparison of a snap-in connection produced according to the state of the art and a snap-in connection designed according to the invention. The numerical values displayed next to a displacement scale correspond to the respective magnitude of the displacement U in millimetres. A specific graphic design of the scales in Figs. 6A and 6B corresponds to a specific value of displacement. The snap-in connection as per Fig. 6A that is known from the state of the art is subjected to both tensile and bending stresses. The snap-in connection as per Fig. 6B is primarily subjected to tensile stress and not bending. Although the cross-section of the header clip element 4 as per Fig. 6B is significantly smaller, the clip element 4 can withstand the same load/stress as the header clip element shown in Fig. 6A. The new design makes it possible to implement a reliable mechanical connection, so that additional plastic welding can be avoided. The design of the snap-in connection and the clip elements described in DE 102018 111 556 A1 was weaker in terms of compressive strength than the design according to the invention. The clip elements according to the

invention

3, 4 offer almost three times greater stability, while maintaining the necessary degree of flexibility.

Fig. 7A and Fig. 7B schematically show the geometry of a header clip element 4 that essentially exhibits a rectangular perimeter. Fig. 7A represents a plan view of the essentially rectangular surface that is formed here. It shows that the header clip element 4 exhibits the snap-in connection opening 5 in the form of an oval hole 5 in the central section of its essentially rectangular surface, whose longer side preferably stretches towards the longer side of the essentially rectangular header clip element 4. During assembly with snap-in connection, the snap-in connection opening 5 of the header clip element 4 is used to guide through the opposite pipe base clip element in each case, wherein the edge of the snap-in connection opening 5 reaches around the pipe base clip element. The clip elements must display sufficient stability to withstand the operating conditions and sufficient flexibility to guarantee a mechanical connection. To this end, an optimum clip element length, represented in Fig. 7A by the letter L, was calculated as being in the range from 7 to 25 mm. The optimum clip element thickness d, shown in the side view in Fig. 7B, is in the range from 0.4 to 2.4 mm.

Fig. 8A shows the assembly of the plastic pipe base 1 with the pipe

base clip elements

3a and 3b and of the header 2 with the header clip elements 4, wherein it becomes clear that the pipe base clip elements 3a on the short sides of the pipe base 1 are positioned and aligned differently and engage with the header clip elements 4 from the pipe base clip elements 3b on the longer side of the essentially rectangular perimeter of the pipe base 1 or header 2 in order to facilitate easier compensation of length deviations, which are highly likely when using plastic welding. The design shown offers greater tolerance ranges for length difference compensation. This can be seen in Fig. 8B, which contains a sectional view in the longitudinal direction of the pipe base 1 and of the header 2, wherein the snap-in connection and the seal between pipe base 1 and header 2 are shown. This sectional view in particular shows how a header clip element 4 clasps a pipe base clip element 3a on the shorter side of the pipe base 1. As can be seen in Fig. 8B, a larger space for the compression area 24a of the seal 11 is provided along the shorter side of the header 2 inside the header 2. This allows for compensation of the length dimension to accommodate movement of the position of the sealing rib 25 of the header 2 that presses on the seal 11. The sealing rib 25 positioned inside the header 2 ensures that - when attaching the header 2 on the pipe base 1 using the flexible header clip elements 4 - the sealing rib 25 exerts pressure on the seal 11 and guarantees the tightness of the inner chamber formed by the pipe base 1 and the header 2 over the entire perimeter of the header 2.

Fig. 9 shows a cross-section and a detailed view of the snap-in connection of the pipe base 1 and of the header 2, which represents the compression area 24b along the longer side of the pipe base 1 and the header 2 as a sectional depiction. It can be seen here that the seal 11 gets thinner as it gets nearer to the side wall 26 of the pipe base 1. As such, sufficient space is provided for compression of the seal 11, as well as and the deformation associated with this. If insufficient space was provided for the seal 11, the force that is generated by the seal after compression could be undesirably high and thereby have a negative impact on the overall stability of the mechanical connection.

Fig. 10A and Fig. 10B describe two alternative versions I and II for the design of the pipe base and the header, while Fig. 11A and Fig. 11B each show the pipe base 1; 1' and the header 2; 2' as parts assembled via a snap-in connection in a combination of cross-section and internal view of the header 2; 2'. The description in the following focuses on the components that differ. The differences between versions I and II can be seen in the figures. The main difference is the position of the clip mechanism. In particular, the pipe base clip elements 3b on the longer side of the pipe base 1 according to version I are positioned and aligned differently from the corresponding pipe base clip elements 3b‘ according to version II. The pipe base underside supports 22‘ of version II also differ significantly from the pipe base underside supports 22 according to version I.

Both versions I and II are primarily based on a two-component seal 11; 11', which is injection moulded directly on the pipe base 1. However, it is still possible to use a separate EPDM seal between pipe base 1; 1' and header 2: 2' as an alternative or additional seal. With this kind of snap-in connection, the pipe base 1; 1' and the header 2, 2' rely exclusively on this mechanical connection for their assembly.

Fig. 12A and Fig. 12B only show version II, wherein Fig. 12A shows a pipe base 1' and a header 2' as separate parts prior to mechanical assembly and Fig. 12B shows the pipe base 1' and the header 2' as parts assembled via a snap-in connection. Version II uses an alternative clip design with the prospect of the same stability as the version I already shown in Fig. 2A and Fig. 2B.

As is already the case with the pipe base clip elements 3a in version I, the pipe base clip elements 3a', which are arranged on the shorter side of the pipe base 1 with equal spacing in the embodiment shown in Fig. 12A, are produced as nose-like projections that point outwards from one of the shorter sides 6a' of the edge of the pipe base 6'. Unlike the pipe base clip elements 3b of version I, the also nose-like pipe base clip elements 3b' on the longer side of the pipe base 1' are not arranged directly on the longer side 6b' of the edge of the pipe base 6', but rather moved physically inwards while pointing outwards. Similarly to version I, pass-through openings 10' for routing through the header clip elements 4' arranged on the long side of the header 2' are located above the pipe base clip elements 3b' on the longer side of the pipe base 1'. This means that one pass-through opening 10' for a header clip element 4' is located above each pipe base clip element 3b'. During assembly, the header clip element 4' is first routed through the pass-through opening 10' before it can enter the snap-in connection with the pipe base clip element 3b' in the way described above.

Fig. 12B shows the fitted snap-in connection between header clip elements 4' and corresponding pipe base clip elements 3b on the longer side of the pipe base 1'. The header clip elements 4', which are routed through the pass-through opening 10', reach around the pipe base clip elements 3b' which, in contrast to the pipe base clip elements 3b of version I, are produced as outward-facing nose-like projections.

With this kind of snap-in connection, the pipe base 1' and the header 2' rely exclusively on this mechanical connection for their assembly. However, there is also the option of establishing a connection between the pipe base 1' and the header 2' via plastic welding in certain areas.

Fig. 13A shows a perspective view of the pipe base 1' according to version II with a view of its underside 21'. As already shown for version I in Fig. 5A and Fig. 5B, pipe base underside supports 22' are provided on the underside 21' in order to guarantee support during mounting of the header 2' to the pipe base 1'. These are shown schematically in Fig. 13B. A high compressive force, the mounting force 18 indicated by the arrows, must be applied here during the process of attaching to the header 2'. The pipe base underside supports 22' provide support to handle the mounting force 18 here. The pipe base underside supports 22‘ differ significantly from the pipe base underside supports 22 according to version I, which are shown in Fig. 5A, in terms of the shape of their support surface 23'. The support surface 23' is pentagonal, wherein four corners are arranged in a square relative to one another and a fifth corner forms an outward-facing projection together with two concave edges.

Fig. 14A shows the positioning of the clip elements on the pipe base 1' according to version II. The pipe base clip elements 3a' on the short side of the pipe base 1' exhibit the same design as version I here. The pipe base clip elements 3b' on the long side of the pipe base 1', on the other hand, are not only positioned differently in comparison with the pipe base clip elements 3b of version I, but also produced differently.

Each nose-like pipe base clip element 3b' exhibits a lead-in chamfer 7' that starts from a base and transitions via a flattened section 8', as well as a subsequent snap-in projection 27 with a stepped offset, to a lower snap-in area 9', which is aligned horizontally, i.e. approximately vertically to the base, starting from the snap-in projection 27. According to version II, the base is a side wall 26' of the pipe base 1' that runs parallel to the longer side 6b' of the edge of the pipe base 6', but is arranged with internal offset relative to this. In contrast to the corresponding lead-in chamfer 7 of the pipe base clip elements 3b on the longer side of the pipe base 1 in version I, the lead-in chamfer 7' of the pipe base clip elements 3b' according to version II points outwards. Since the nose-like pipe base clip element 3b' according to version II also reaches significantly into the area below the edge of the pipe base 6b' in the vertical direction, the lower snap-in surface 9' is located well below the edge of the pipe base 6'.

Fig. 14B shows a cross-section of the snap-in connection between the pipe base 1' and the header 2', wherein the pipe base clip elements 3b' and the header clip elements 4' interact with one another mechanically.

Previously, the elastic header clip elements 4' were each guided with their outer side over the outward-facing lead-in chamfer 7' and a vertically oriented flattened section 8', as well as the subsequent snap-in projection 27 with a stepped offset of the corresponding pipe base clip element 3b', until they snap into place on the lower snap-in surface 9'.

Fig. 14C shows a corresponding perspective view of a corner area of the assembly of pipe base 1' and header 2' with mechanically interacting pipe base clip elements 3a' or 3b' and the header clip element 4' according to version II.

Fig. 15A also shows a perspective view of a corner area of the assembly of pipe base 1' and header 2' with mechanically interacting pipe base clip elements 3a', 3b' and header clip elements 4', wherein it is clear to see that the pipe base clip elements 3a' on the short side of the pipe base 1' exhibit the same design as the one employed in version I.

Fig. 15B is a sectional view in the longitudinal direction of the pipe base 1' and the header 2' according to version II, wherein the snap-in connection and the seal between pipe base 1' and header 2' are presented. The snap-in connection is shown on the basis of the pipe base clip elements 3a‘ and the header clip elements 4' on the short side of the pipe base 1' or the header 2'. When using plastic welding, variations in terms of length dimensions are very likely to occur. The design must therefore provide greater tolerance ranges for length dimension compensation. As shown in Fig. 15B, a larger space is provided inside the header 2' for the compression area 24a' of the seal 11'. This allows for compensation of the length dimension to accommodate movement in terms of the position of the sealing rib 25' of the header 2' that presses on the seal 11'.

List of reference numbers

A Header (state of the art)

B Pipe base (state of the art)

C Seal (state of the art)

D Pipe ends (state of the art)

E Clip elements (state of the art)

F Snap-in connection opening (state of the art)

G Lug (state of the art)

H Sealing rib (state of the art)

L Clip element length

d Clip element thickness

1 Pipe base (version I)

1' Pipe base (version II)

2 Header (version I)

2' Header (version II)

3 Clip element; pipe base clip element

3a Pipe base clip element on the shorter side of the pipe base (version I)

3a' Pipe base clip element on the shorter side of the pipe base (version II)

3b Pipe base clip element on the longer side of the pipe base (version I)

3b' Pipe base clip element on the longer side of the pipe base (version II)

4 Clip element; header clip element (version I)

4' Clip element; header clip element (version II)

5 Snap-in connection opening; oval hole (in the header clip element)

6 Edge of the pipe base (version I)

6' Edge of the pipe base (version II)

6a Edge of the pipe base (on the short side) (version I)

6a' Edge of the pipe base (on the short side) (version II)

6b Edge of the pipe base (on the long side) (version I)

6b' Edge of the pipe base (on the long side) (version II)

7 Lead-in chamfer (version I)

7' Lead-in chamfer (version II)

8 Flattened section (version I)

8' Flattened section (version II)

9 Lower snap-in surface (version I)

9' Lower snap-in surface (version II)

10 Pass-through openings for the header clip elements (version I)

10' Pass-through openings for the header clip elements (version II)

11 Seal, two-component seal (version I)

11' Seal, two-component seal (version II)

12 Mounting holes

13 Plastic welding points; slots

14 Plastic welding points; projections

15 Bridges

16 Supporting parts

17 Intersections (of the supporting parts)

18 Mounting force (on supporting parts)

19 Ribs (at the edges on the top of the header)

20 Mounting force (on ribs at the edges)

21 Underside (version I)

21' Underside (version II)

22 Pipe base underside supports (version I)

22' Pipe base underside supports (version II)

23 Support surface (version I)

23' Support surface (version II)

24a Compression area (along the shorter side of the pipe base and the header according to version I)

24b Compression area (along the longer side of the pipe base and the header according to version I)

24a' Compression area (along the shorter side of the pipe base and the header according to version II)

25 Sealing rib of the header (version I)

25' Sealing rib of the header (version II)

26 Side wall of the pipe base (version I)

26' Side wall of the pipe base (version II)

27 Snap-in projection of the pipe base clip element

Claims

Coolant/air heat exchanger for a motor vehicle, exhibiting multiple fluid-carrying metal pipes, whose pipe ends are arranged next to one another with spacing, at least one pipe base produced from plastic (1; 1') with mounting holes (12), into which the pipe ends can be mounted and one header produced from plastic (2; 2') that can be connected to the pipe base with a snap-in locking device, which is produced between the pipe base (1; 1') and the header (2; 2'), wherein the snap-in locking device is formed with pipe base clip elements (3; 3a; 3b; 3a'; 3b') arranged on the pipe base (1; 1') and header clip elements (4; 4') arranged on the header (2; 2'), which can be used to establish a snap-in connection through a mechanical interaction of the individual pipe base clip elements (3; 3a; 3b; 3a'; 3b') and corresponding individual header clip elements (4; 4'), and wherein a seal (11; 11') is produced that guarantees a press fit of the pipe base (1; 1') on the pipe ends and seals the header (2; 2') against the pipe base (1; 1'), as well as the pipe base (1; 1') against the pipe ends.
Coolant/air heat exchanger according to claim 1, characterised in that a sealing rib (25; 25') is produced inside the header (2; 2') over the entire perimeter of the header (2; 2') for sealing the header (2; 2') against the pipe base (1; 1') which - when attaching the header (2; 2') to the pipe base (1; 1') using the flexible header clip elements (4; 4') - exerts pressure on the seal (11; 11') and thereby guarantees the tightness of the inner chamber formed by the pipe base (1; 1') and the header (2; 2') over the entire perimeter of the header (2; 2').
Coolant/air heat exchanger according to claim 1 or 2, characterised in that the header clip elements (4; 4') each exhibit a snap-in connection opening (5) and that the corresponding pipe base clip elements (3; 3a; 3b; 3a'; 3b') are each produced in the form of a nose-like projection, wherein the header clip element (4; 4') reaches around the corresponding nose-like pipe base clip element (3) with the edge of the snap-in connection opening (5) when applying the snap-in connection.
Coolant/air heat exchanger according to claim 3, characterised in that the pipe base clip elements (3b), which are arranged along the longitudinal sides of an elongated pipe base (1), are constructed as projections that point inwards starting from one pipe base edge (6b) on a longitudinal side and that the pipe base clip elements (3a) that are arranged along the shorter sides of the elongated pipe base (1) are constructed as nose-like projections that start from a pipe base edge (6a) on the shorter side and face outwards.
Coolant/air heat exchanger according to claim 3, characterised in that the pipe base clip elements (3b) that are arranged along a longitudinal side of an elongated pipe base (1') are constructed as nose-like projections that point outwards starting from a pipe base side wall (26') on the longitudinal side and that the pipe base clip elements (3a') that are arranged along the shorter side of the longitudinally produced pipe base (1') are produced as nose-like projections that start from an edge of the pipe base (6a') on the shorter side and face outwards.
Coolant/air heat exchanger according to one of the claims 1 to 5, characterised in that pass-through openings (10; 10') are produced for at least some of the plurality of the header clip elements (4; 4') in edge areas of the pipe base (1; 1') , into which at least some of the plurality of the header clip elements (4; 4') can be introduced, and wherein the corresponding pipe base clip elements (3; 3a; 3b; 3a'; 3b') are positioned below the level of the pass-through openings (10; 10').
Coolant/air heat exchanger according to one of the claims 1 to 6, characterised in that the clip element length (L) of the header clip elements (4; 4‘) is in the range from 7 to 25 mm.
Coolant/air heat exchanger according to claim 7, characterised in that the clip element thickness (d) of the header clip elements (4; 4') is in the range from 0.4 to 2.4 mm.
Coolant/air heat exchanger according to one of the claims 1 to 8, characterised in that the seal (11; 11') is moulded directly on the pipe base (1; 1') using an injection moulding process, in particular a two-component composite injection moulding process.
Coolant/air heat exchanger according to one of the claims 1 to 8, characterised in that the seal is inserted as a separate seal between the pipe base (1, 1') and the header (2, 2').
Coolant/air heat exchanger according to one of the claims 1 to 10, characterised in that the seal (11; 11') is produced ever thinner in the compression area between pipe base (1; 1') and header (2; 2') the closer it gets to the side wall (26; 26') of the pipe base (1;1') adjacent to the seal (11; 11').
Coolant/air heat exchanger according to one of the claims 1 to 11, characterised in that plastic welding points (13, 14) are provided and arranged at intervals on opposing internal surfaces of the header (2) and of the pipe base (1), at which the header (2) and the pipe base (1) can be welded together.
Coolant/air heat exchanger according to one of the claims 1 to 12, characterised in that the metal pipes and, where applicable, further metallic elements of the coolant/air heat exchanger are connected to one another via brazed connections, and the pipe base produced from plastic (1; 1') is pressed onto the metal pipes and sealed in the seal (11; 11') via a press fit.
Coolant/air heat exchanger according to one of the claims 1 to 13, characterised in that the assembly of the coolant/air heat exchanger is based on mechanical connections without the use of brazed connections by the pipe base (1; 1) being pressed onto the metal pipes of the coolant/air heat exchanger that are not brazed to one another and sealed off via a press fit in the seal (11; 11').
Coolant/air heat exchanger according to one of the claims 1 to 14, characterised in that supporting parts (16) are arranged at intervals on the top of the header (2; 2') in the central section across the longitudinal side of the header (2; 2') which are intended for applying a mounting force (18) during assembly of the pipe base (1; 1') and manifold (2; 2').
Coolant/air heat exchanger according to one of the claims 1 to 15, characterised in that a large number of ribs (19) is arranged at the edges of the top of the header (2; 2') across its perimeter and are intended for application of a mounting force (20) at the edges of the header (2; 2').
Coolant/air heat exchanger according to one of the claims 1 to 16, characterised in that pipe base underside supports (22; 22') are provided on the underside (21; 21') of the pipe base (1; 1') in order to guarantee support during mounting of the header (2; 2') on the pipe base (1; 1').