EP1869390A1

EP1869390A1 - Heat exchanger, in particular for a motor vehicle

Info

Publication number: EP1869390A1
Application number: EP06723989A
Authority: EP
Inventors: Dieter BÄCHNER
Original assignee: Behr GmbH and Co KG
Current assignee: Mahle Behr GmbH and Co KG
Priority date: 2005-04-05
Filing date: 2006-04-04
Publication date: 2007-12-26
Also published as: US20080190596A1; WO2006105925A1; CN101166945A

Abstract

The invention relates to a heat exchanger, in particular for a motor vehicle, having tubes and if appropriate corrugated fins through which a first, hot medium can flow and which are arranged between collecting boxes, and having at least one side part (1) which is arranged laterally between two collecting boxes, a second medium which flows around the tubes and if appropriate corrugated fins being colder than the first, hot medium during operation, the side part (1) absorbing at least some of the tensile stresses which act at least on the outermost tube as a result of different thermal expansions of the tubes and if appropriate corrugated fins, and the side part (1) having slots (2) and/or openings (4) which change the spring constant of the side part (1) in relation to a side part without slots and/or openings such that, in the event of a different longitudinal expansion of the central tubes relative to the outermost tube which is arranged adjacent to the side part (1), the tensile stress which acts on the outermost tube is reduced.

Description

Heat exchanger, in particular for a motor vehicle

The invention relates to a heat exchanger, in particular for a motor vehicle and in particular a charge air cooler, according to the preamble of claim 1.

Heat exchangers generally have two headers, between which pipes, such as flat tubes, and corrugated fins are arranged. In order to connect the headers and protect the outer corrugated ribs, side panels are often placed between the headers.

The problem with such heat exchangers, especially in intercoolers, is that the outermost tubes are relatively cold in comparison with the middle tubes and the corresponding corrugated fins, so that during operation, especially at start of operation, due to the different temperatures and the associated different thermal expansion of the individual heat exchanger parts in the heat exchanger voltages arise. In this case, the outer tubes are colder, ie shorter, than the inner tubes and the corrugated ribs, so that the solder joints of the outer tubes are heavily loaded with the tubesheets. Due to the stresses, undesirable cracking occurs, in particular in the case of the outer tubes in the area of the solder joints with the tubesheets. From DE 197 53 408 A1, a heat exchanger for a motor vehicle is known, which has a rib / tube block with a plurality of interconnected in the manner of a network structure tubes and corrugated fins. In order to stabilize the rib / tube block, in particular during a manufacturing process, it is enclosed on opposite sides of two side parts. For reasons of strength, such a side part has an approximately U-shaped profile in cross-section, wherein the two upturned legs serve as reinforcing ribs. For an improved distribution of the thermal stresses during operation of the heat exchanger, these reinforcing ribs according to DE 197 53 408 A1 can have expansion regions which are designed as fold-like beads.

According to DE 103 55 123 A1, in addition to reinforcing ribs, expansion sections are also provided, formed by openings in the side part, which correspond to the reinforcing ribs. The reinforcing ribs are formed by a reshaped center section of the base plate of the side part, wherein for the production of the side part, an edge of the Flächenmit- telstücks section precut and then the center section from the plane of the base plate is formed out. In addition to the expansion sections, the side part may have projections at its longitudinal ends, which serve to seal the collecting boxes. To reduce mechanical loads, the side part has two expansion areas, which are formed essentially by openings. These extend transversely to the longitudinal extent of the side parts over almost the entire plane, i. not bent surface of the side part.

From US Patent 3,939,908 A is the provision of openings with

Noses are known in the side part, which form a means for distributing the solder, so that not the entire surface of the side part is soldered to the tubes / corrugated fins, whereby the function of elements for balancing the different thermal expansion coefficient and the associated different longitudinal extent of side member and pipes / corrugated fins, such as a pleat-like bead, is secured. In such wrinkle-like beads that compensate for a portion of the stresses that arise as a result of different linear expansion of the tubes, however, there is often a rupture of the bead due to an overload.

In order to avoid the tensile loads on the pipes and thereby protect the pipes, split side parts are known transversely to the longitudinal extent. Such heat exchangers thus leave nothing to be desired, in particular with regard to the load on the solder joints of the outer tubes with the tubesheets.

It is an object of the invention to provide an improved heat exchanger available.

This object is achieved by a heat exchanger with the features of claim 1. Advantageous embodiments are the subject of the subclaims.

According to the invention, a heat exchanger is provided, in particular for a motor vehicle, arranged between collecting boxes, through which flows through a first, hot medium pipes and possibly corrugated fins and with at least one laterally disposed between two headers side part, wherein the tubes and possibly corrugated ribs flowing around second medium When operating colder than the first, hot medium is, the side part receives at least a portion of the tensile stresses acting at least on the outermost tube in operation due to different thermal expansion of the tubes and corrugated ribs during operation, and the side part slots and / or openings having, which the spring constant of the side part opposite a side part without slots and / or openings changed such that at a different longitudinal extent of the middle tubes in comparison to the outermost, adjacent to the side part disposed tube, the tensile stress acting on the outermost tube is reduced. The fact that the tensile stresses are deliberately reduced during operation, the solder joint between the outermost tube and the tube sheets is protected from overloads, whereby cracks and therefore leakage of the heat exchanger can be avoided. In this case, the spring constant of the side part by means of slots and / or openings in connection with the supporting cross-section and its effective length can be fixed.

Slots are provided in the side part, so they are preferably at least partially transverse to the longitudinal extent of the side part, so that the supporting cross-section is reduced accordingly. The arrangement may be symmetrical or asymmetrical.

Preferably, the slots are formed to extend only over a portion of the length of the side member, whereby the effective length of the supporting cross section is determined.

The slots are preferably H- or T-shaped, wherein they are preferably arranged in the longitudinal direction and / or perpendicular thereto. In particular, an H-shaped configuration of the slots is preferred, wherein the "H" is aligned in the longitudinal direction of the side part.

If openings are provided in the side part, then the openings are preferably circular and / or oval and / or elliptical and / or slot-like. Other shapes are possible. The side part is preferably flat in its cross-section, ie rectangular, or U-shaped. Such side parts can be easily produced from a sheet by punching and optionally forming.

Preferably, the side part has at least one rib, the same preferably extending perpendicular to the surface of the side part. The ribs may be formed integrally with the side part or be placed. In the case of a one-piece embodiment, the rib may be formed by bending, possibly also by means of stretching.

The side part may consist of at least two parts which are firmly connected to each other. In particular ribs may be attached to the side part, for example by means of welding, optionally also by means of soldering, riveting.

The side part preferably has a spring constant of 1000 N / mm to 40,000 N / mm in its longitudinal extent. Spring constants of this order of magnitude provide optimum stress reduction, especially in the case of heat exchangers made of aluminum or aluminum alloys.

The heat exchanger is preferably stress-free with a uniform temperature distribution and room temperature. Alternatively, the side part can be at room temperature under a predetermined compressive stress in the direction of its longitudinal extension, i. the outermost tube is slightly biased.

In the following the invention will be explained with reference to an embodiment with several variants with reference to the drawings in detail. In the drawing show: 1a-d schematic, partial plan views of side parts with different slot patterns,

2a-d schematic sections of side parts with different cross-sections,

3a-f schematic, partial plan views of side parts with further slot patterns,

Fig. 4a-e schematic, partial plan views of side parts with other opening patterns, and

Fig. 5a-5j representations of another variant.

A heat exchanger, in this case an intercooler of a motor vehicle, of which only parts of side parts 1 are shown in the drawing, according to the present embodiment, two manifolds formed by trough-shaped box elements and tube sheets, a plurality of tubes whose ends protrude into openings in the tube sheets are provided, and corrugated fins which are arranged between the tubes. The side parts 1 are arranged on the outside between the collecting boxes, for which they are firmly connected to the collecting boxes, but not directly to the pipes and / or corrugated fins. The parts of the heat exchanger are soldered together in a known per se, which preferably takes place in a single soldering process, or otherwise firmly connected to each other.

To keep stresses between the tubesheets and in particular the outer tubes as low as possible at the start of operation or at the beginning of an increased load on the charge air cooler, the side parts are designed accordingly in their spring constants. That is, when the heat exchanger, a difference in length of the middle, hot tubes and the outer, cold and therefore short tubes occurs, which leads to tensions, especially in the outer tubes in the field of solder joints with the tubesheets, the side parts compensate for these stresses at least partially, by at a temperature and thus length difference of the middle and outer tubes as a kind Tie rod act and thereby counteract the tensile stress on the outermost tubes, which is caused by the adjacent, inner / middle tubes. Here are - in contrast to the fold-like beads, which are provided in conventional side panels - slots 2 or other openings provided in the side part 1, which ensure that the spring characteristic, ie the force on the difference in length of the (especially outermost and second outermost) pipes , the lateral part 1 in each case equalizes the tensile stress through the inner to the second outermost tubes to the outermost tube essentially by a corresponding, oppositely directed tensile stress (that is to say a corresponding pressure on the respective outermost tube).

Here, the spring constant D in a heat exchanger of aluminum or an aluminum alloy is preferably in a range of 1000 N / mm to 40,000 N / mm, and the spring constant in the normal operating range does not necessarily have to be constant, i. that the spring characteristic must be linearly increasing. The determination of the spring constant (s) is made by the choice of the supporting cross section and its effective length. It is necessary to ensure the function of a tie rod that over the entire operating range a purely elastic deformation of the side part takes place.

In the side part 1, according to the embodiment, H-shaped slots 2 are provided to optimize the spring constant D in the longitudinal extent of the side part 1 such that the tension of the side part 1 with a corresponding difference in length of the adjacent outermost tubes equalizes the same, ie that the force of the side part 1 on the outermost tube the tension acting on the outermost tube is compensated due to the difference in length of the tubes, so that the solder joints between the outermost tube and the tubesheets arranged at both ends of the tube, through which the flow of force passes, are protected. The legs of the H run in the direction of the longitudinal extent of the side part 1 and the cross-connection perpendicular thereto.

According to a first, shown in Fig. 1b variant T-shaped slots 2 are provided, wherein both legs of the T perpendicular to the longitudinal extension of the side part 1 and aligned with each other on the side thereof and the two transverse lines in the longitudinal extension of the side part 1 and parallel to each other, where they end at the same height, are arranged. According to a second variant, only a T-shaped slot 2 is provided, the leg of which is arranged perpendicular to the longitudinal extension of the side part 1 on one side thereof and the transverse line in the longitudinal extension of the side part 1 off the same. According to a third variant, a plurality of H-shaped slots 2 are provided, which are formed according to the embodiment and arranged at the same height.

As can be seen from FIGS. 1a-d, the cross-sectional profile of the side part 1 does not necessarily have to be constant over the entire longitudinal extension thereof. This also applies to the thickness and overall width of the side part 1. The side part 1 according to the embodiment is substantially, i. apart from the end areas in which it is soldered to the headers, just trained. FIG. 2 a shows a section through the same in the region of the legs of the H-shaped slots 2.

According to a first variant, which is shown in FIG. 2b, the two edges are bent in the longitudinal extent of the side part by 90 °, so that the side part 2 is U-shaped. The slots 2 run - according to the representation of Fig. 2b - in the corner areas. Alternatively, the slots 2 may also extend in the bottom region, as shown in FIG. 2c, and / or possibly also in the region of the legs.

According to further variants, ribs or edges of a side part are bent by less than or more than 90 °, so that the ribs or edges are formed in cross-section as oblique legs.

2 d shows a variant of a side part 1, in which a rib 3 rising vertically from the surface thereof is provided approximately centrally next to a slot 2 extending in the longitudinal extent of the side part. This rib 3 is presently fixed by welding on the side part 1. An edge is - according to the previous variant - bent by 90 ° in Fig. 2d, wherein the edge and rib 3 extend in the same direction.

Figures 3a to 3f show various other variants of slots 2, which are arranged obliquely or perpendicular to the longitudinal extent of the side part 1 of one or both sides. As shown, the slots 2 are provided at equidistant intervals, however, changing distances and / or changing angles to the longitudinal extension of the side part 1 may also be provided.

According to the representations of the FIGS. 4a to 4g, instead of slots, opening 4 is provided in the side part 1, with a single, circular opening 4 (see FIG. 4c), a plurality of circular openings 4 (see FIGS 4a, 4b) or, for example, oval openings 4 with the most varied arrangements of the longitudinal axis (cf., FIGS. 4d to 4e) can be provided. The longitudinal axes can also be arranged obliquely. Any combinations or other shapes of the openings and / or slots are possible, depending on the desired spring characteristic of the side part. 1

FIGS. 5a to 5j show a variant of the first exemplary embodiment with a side part 1, in which three slots 2 arranged in an H-shape are provided. Here, the slots 2 each have the same width, which in the present case corresponds approximately to one twentieth of the width of the side part. The two, the legs of the "H" forming slots 2 extend - with respect to the length of the side part 1 arranged centrally - over a little more than a third of the total length of the side part 1. The two legs connecting slot 2 is with respect to the length of the side part. 1 arranged in the middle and ends in the legs forming slots 2. The edge width of the side part 1 is on the outside of the slot 2, which is closest to the edge, about one sixth of the total width of the side part.

Along the central longitudinal axis of the side part 1, there are eight V-shaped beads 5 extending in the longitudinal direction, the depth of which is slightly less than the material thickness of the side part 1. In the present case, the length of the beads 5 is only about one third of the length of the short, transverse to the longitudinal extent of the side part 1 slot 2. In addition to the eight in the longitudinal direction of the side part 1 extending beads 5 are arranged two further, correspondingly formed and parallel thereto aligned beads 5 in the edge region of the side part 1 in the height of the transverse leg 2.

Further, in the central longitudinal axis of the side part 1 in the end region of the legs of the formed by the slots 2 "H" centered between the leg ends each have an opening 4 in the form of a bore having an inner diameter which is greater than the width of the slots 2 is provided.

Claims

Patent claims

1. Heat exchanger, in particular for a motor vehicle, arranged between collecting tanks, by a first, hot medium flowable tubes and with at least one laterally arranged between two headers side part (1), wherein a flowing around the tubes second medium in operation colder than the first, is hot medium, the side part (1) receives at least a portion of the tensile stresses acting as a result of different thermal expansions of the tubes during operation at least on the outermost tube, and the side part (1) slots (2) and / or openings (4) which varies the spring constant of the side part (1) with respect to a side part without slots and / or openings such that at a different longitudinal extent of the middle tubes compared to the outermost, adjacent to the side part (1) arranged pipe reduces the tensile stress acting on the outermost tube is.

2, heat exchanger after. Claim 1, characterized in that the slots (2) at least partially extend transversely to the longitudinal extent of the side part (1).

3. Heat exchanger according to claim 1 or 2, characterized in that the slots (2) are formed extending over only part of the length of the side part (1).

4. Heat exchanger according to one of the preceding claims, characterized in that the slots (2) are H- or T-shaped.

5. Heat exchanger according to one of the preceding claims, characterized in that the openings (4) are circular and / or oval and / or elliptical and / or slot-like.

6. Heat exchanger according to one of the preceding claims, characterized in that the side part (1) is flat or U-shaped.

7. Heat exchanger according to one of the preceding claims, character- ized in that the side part (1) has at least one rib.

8. Heat exchanger according to one of the preceding claims, characterized in that the side part (1) consists of at least two parts len, which are fixedly connected to each other.

9. Heat exchanger according to one of the preceding claims, characterized in that the side part (1) in its Längserstre- ckung a spring constant D of 1000 N / mm to 40000 N / mm up has.

10. Heat exchanger according to one of the preceding claims, characterized in that the heat exchanger with uniform temperature distribution and room temperature is free of stress.