US20140090812A1

US20140090812A1 - Heat exchanger

Info

Publication number: US20140090812A1
Application number: US14/039,052
Authority: US
Inventors: Caroline SCHMID; Michael Moser; Nikolaus Daubitzer; Holger Schroth; Heiko Neff; Dominique RAIBLE; Anton KIERIG; Thomas SCHIEHLEN
Original assignee: Behr GmbH and Co KG
Current assignee: Mahle Behr GmbH and Co KG
Priority date: 2012-09-28
Filing date: 2013-09-27
Publication date: 2014-04-03
Also published as: CN103712508A; DE102012217870A1; CN103712508B

Abstract

Heat exchanger having a first collecting box and having a second collecting box, having at least one tube arranged between the two collecting boxes, wherein a fluid inlet and a fluid outlet are provided which are arranged individually on in each case one of the collecting boxes or on a single one of the collecting boxes, wherein the tube is received at the ends in an opening in in each case one of the collecting boxes and is in fluid communication with the collecting boxes, wherein the opening is surrounded by an opening edge whose contour corresponds to the outer contour of the tube, and in that the opening is designed such that the opening cross section narrows toward the interior of the collecting box and the tube can be inserted, under preload at the circumference, into the opening.

Description

TECHNICAL FIELD

Heat exchanger having a first collecting box and having a second collecting box, having at least one tube arranged between the two collecting boxes, wherein a fluid inlet and a fluid outlet are provided which are arranged individually on in each case one of the collecting boxes or on a single one of the collecting boxes, wherein the tube is received at the ends in an opening in in each case one of the collecting boxes and is in fluid communication with the collecting boxes.

PRIOR ART

In electric vehicles, energy stores are used for operating an electric motor. As energy stores, use is often made of storage batteries based on lithium-ion technology, or of nickel-metal hybrid storage batteries. Alternatively, use is also made of high-performance capacitors, so-called super-caps.
In the case of all of the energy stores mentioned, an intense generation of heat occurs during operation, in particular during fast charging and discharging of the energy stores.
Temperatures of approximately 50° C. and higher may however damage the energy stores and significantly reduce the service life thereof. Likewise, excessively low temperatures cause lasting damage to the energy stores.
To maintain the performance of the energy stores, the temperature of these must therefore be actively controlled. Periods where cooling is required are more prevalent by far. The cooling may be realized for example by the introduction of heat exchangers through which fluid flows. In solutions according to the prior art, the heat exchangers are often elements through which fluid flows and which have, between two areal cover panels, one or more fluid ducts through which a fluid can flow.
It is advantageous here for all of the cells of the energy stores to be kept at a uniform temperature level. Likewise, intense temperature gradients within the cells should be avoided.
The panels of the heat exchangers can be traversed by a flow of a cold fluid during cooling, though they may also be traversed by a flow of a warm fluid for the purpose of heating.
To attain the highest possible energy efficiency, in particular in electric vehicles, a design which is optimized as far as possible with regard to weight is advantageous.
In the prior art, solutions are described which use heat exchangers manufactured from metallic materials. Such a solution is disclosed for example by the utility model DE 20 2012 102 349 U1.
A disadvantage of the solutions according to the prior art is in particular that the heat exchangers are often constructed entirely from aluminum. These are considerably heavier in relation to designs composed of plastic or of a mixture of aluminum and plastic. Furthermore, the assembly outlay is greater in the case of a heat exchanger manufactured entirely from metallic materials.

PRESENTATION OF THE INVENTION, PROBLEM, SOLUTION, ADVANTAGES

It is therefore the object of the present invention to provide a heat exchanger which has a weight-optimized design and the production of which is simple and inexpensive.
The object of the present invention is achieved by means of a heat exchanger having the features of claim 1.
An exemplary embodiment of the invention concerns a heat exchanger having a first collecting box and having a second collecting box, having at least one tube arranged between the two collecting boxes, wherein a fluid inlet and a fluid outlet are provided which are arranged individually on in each case one of the collecting boxes or on a single one of the collecting boxes, wherein the tube is received at the ends in an opening in in each case one of the collecting boxes and is in fluid communication with the collecting boxes, wherein the opening is surrounded by an opening edge whose contour corresponds to the outer contour of the tube, and wherein the opening is designed such that the opening cross section narrows toward the interior of the collecting box and the tube can be inserted, under preload at the circumference, into the opening.
In one exemplary embodiment, the heat exchanger according to the invention serves for controlling the temperature of an energy store.
The heat exchanger can be traversed by a flow of a fluid by means of which cooling or heating can be effected depending on the temperature of the fluid relative to the surroundings. For this purpose, the tubes must be connected to the collecting boxes in a fluid-tight manner. Owing to the configuration of the opening with an opening cross section smaller than the width of the tube, a press fit is generated between the tube and the collecting box, whereby the tube is fixed in the collecting box in a fluid-tight manner.
In one advantageous embodiment of the invention, it may be provided that the tube is in the form of a flat tube.
It is also preferable for the inner contour of the opening to be able to be deformed as a result of the tube being pushed in.
As a result of the deformation generated as a result of the tube being pushed in, the tube is acted on by forces which fix the tube in the collecting box. Said forces are generated by the forced deformation of the material of the collecting boxes. The more the material opposes a deformation, or the greater the amount of material that is deformed as a result of the pushing-in process, the greater are the forces that act on the tube.
A heat exchanger with insertable tubes which are fixed in the collecting box by means of a press fit is particularly simple to produce. Furthermore, the number of reworking steps is reduced considerably in relation to a conventional heat exchanger.
In a further exemplary embodiment of the invention, it may be provided that, in the assembled state, a groove which is accessible from outside the collecting box is formed between the tube and the opening edge.
The groove that is formed between the tube and the opening edge of the collecting box serves for receiving an adhesive, for example. The groove that is generated is open to the outside, away from the collecting box, such that an adhesive can be introduced into the groove from there. Here, the groove is formed in a fully encircling manner around the tube.
In this way, the tube can be fixed in its position within the collecting boxes not only by the press fit but also by means of an adhesive. Here, the adhesive is isolated from the fluid flowing through the heat exchanger. This is advantageous in particular because the adhesive need not be configured to be resistant to any corrosive properties of the fluid.
A preferred exemplary embodiment of the invention is characterized in that the tube and the collecting boxes can be adhesively bonded and/or welded and/or pressed together and/or insert-molded with one another.
The tube is fixed in the collecting box with a press fit simply as a result of it being inserted into the openings of the collecting boxes, which must be performed with the exertion of a certain insertion force. Furthermore, the tube may also be welded into the collecting box or adhesively bonded to said collecting box. The selection of the connecting means should be made for example depending on the material pairing that is present.
Furthermore, it may be expedient for at least one of the collecting boxes to be of multi-part form and to have a box opening, the latter being closable by means of a cover, and to have a tube plate with at least one opening for receiving a tube, wherein the box opening is arranged opposite the tube plate.
Using injection molding processes, a multi-part collecting box is considerably easier to produce than a unipartite collecting box of complex shape.
In a particularly expedient exemplary embodiment, it may be provided that the heat exchanger has a multiplicity of tubes which run parallel to and spaced apart from one another.
By means of a multiplicity of tubes, it is possible for the surface area over which heat is transferred by the heat exchanger to be considerably increased in size. Furthermore, by means of the arrangement of multiple tubes, it is possible to realize a throughflow configuration in which the fluid flows through one proportion of the tubes from the first collecting box into the second collecting box and is diverted in the second collecting box so as to flow back into the first collecting box again through another proportion of the tubes. Such a throughflow configuration has the effect that the fluid is subjected to a longer period of contact with the heat transfer surfaces within the heat exchanger.
It may also be advantageous for the tubes to lie in a common plane and/or to lie offset with respect to one another in multiple planes.
For example, it is possible here for the tubes to lie adjacent one another in parallel in one plane, such that the central axis of the tubes, which runs along the throughflow direction, lies on a common plane. It is alternatively also conceivable for the central axes of one proportion of the tubes to lie on a common plane and for the central axes of another proportion to lie on another plane. It is advantageous for all of the tubes to lie parallel to one another, regardless of which plane they are assigned to.
In one preferred embodiment, it is advantageous for the tubes to be connected to one another by an areal panel.
In this context, “connected to one another” means both mechanically and also thermally connected to one another.
As a result of the arrangement of the tubes in a common plane, the individual tubes can be connected in a particularly simple manner by means of an areal panel, such as a panel with good heat-conducting properties, composed for example of aluminum. This increases considerably the surface area over which heat can be transferred.
With corresponding configuration of the areal panel, it is also possible for tubes in different planes to be connected to one another in order to increase the heat transfer area.
A further preferred exemplary embodiment is characterized in that the fluid inlet and the fluid outlet are arranged on the same collecting box, wherein said collecting box has a partition which divides the internal volume of the collecting box into two chambers, and the fluid inlet is in fluid communication with one of the chambers and the fluid outlet is in fluid communication with the other chamber.
By means of the arrangement of the fluid inlet and of the fluid outlet in only one collecting box and also the division of the internal volume of said collecting box into two chambers, the heat exchanger can be traversed by flow as follows. The fluid flows via the fluid inlet into the first chamber of the first collecting box and flows from there via one proportion of the tubes into the second collecting box. The second collecting box does not have a partition and serves for diverting the fluid into the other proportion of the tubes. The fluid flows via said other proportion of the tubes back into the second chamber of the first collecting box, and flows out of the heat exchanger through the fluid outlet.
Advantageous refinements of the present invention are described in the subclaims and in the following description of the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in detail below on the basis of exemplary embodiments and with reference to the drawings, in which:

FIG. 1 shows a perspective view of a heat exchanger according to the invention, having two opposite collecting boxes and having flat tubes which are situated between said collecting boxes and which, at the ends, are received in in each case one of the collecting boxes,

FIG. 2 shows a detail view of the collecting box which has the fluid inlet and the fluid outlet, wherein the collecting box is of multi-part form and is illustrated in its individual parts, and

FIG. 3 shows a detail view of the opening in one of the collecting boxes, in each case one flat tube having been inserted into said opening.

PREFERRED EMBODIMENT OF THE INVENTION

FIG. 1 shows a perspective view of a heat exchanger 1. The heat exchanger 1 is composed substantially of a multiplicity of flat tubes 6 and of two collecting boxes 2, 3 which have in each case a multiplicity of openings 7 into which the flat tubes 6 are inserted. The flat tubes 6 are in fluid communication with the collecting boxes 2, 3.
The collecting box 3 shown in FIG. 1 also has a fluid inlet 4 and a fluid outlet 5. Via the fluid inlet 4 and the fluid outlet 5, the heat exchanger 1 is in fluid communication with a fluid circuit.
The heat exchanger 1 shown in FIG. 1 has a U-shaped throughflow configuration. The fluid enters the collecting box 3 via the fluid inlet 4, flows through one proportion of the flat tubes 6 and passes over into the collecting box 2. There, the fluid distributes over the entire width of the collecting box 2 and flows via the remaining flat tubes 6 back into the collecting box 3, and out of the heat exchanger through the fluid outlet 5. To make said throughflow configuration possible, the collecting box 3 has, in its interior, a partition (not shown in FIG. 1) which divides the collecting box 3 into a left-hand chamber and a right-hand chamber. This construction will be described in more detail in the further figures.
The flat tubes 6 shown in FIG. 1 have substantially two mutually opposite large surfaces. Said large surfaces are directed upward and downward in the case of FIG. 1. The two large surfaces of the flat tubes 6 are connected to one another in each case via short surfaces. As an alternative to the flat tubes 6 shown here, the use of conventional tubes with circular or rectangular cross sections is also conceivable.
Furthermore, the number of flat tubes 6 is likewise variable. In the case of a heat exchanger 1 with a U-shaped throughflow configuration, at least two flat tubes 6 must be provided in order to form at least one outward flow path between the collecting boxes 3 and 2 and one return flow path between the collecting boxes 2 and 3. In the case of a heat exchanger 1 with an I-shaped throughflow configuration, in each case one of the collecting boxes 2, 3 would have a fluid inlet, and the other would have the fluid outlet. In this case, a single flat tube would suffice.
The flat tubes 6 of the heat exchanger 1 are all arranged in a common plane. That is to say the upwardly directed large surface of the flat tubes lies in a plane with the in each case adjacent flat tubes 6 of the heat exchanger 1, whereby, in the case of structurally identical flat tubes 6, the lower large surface of the flat tubes 6 also lies in a plane. In alternative embodiments, an offset of the flat tubes in different planes is likewise conceivable.
The flat tubes 6, which lie in a plane, of the heat exchanger 1 have a panel 8 which is mounted onto the flat tubes 6 and which connects the mutually adjacent flat tubes 6 to one another. Said panel 8 serves substantially for providing a planar and closed contact surface in order that components to be cooled or to be heated can be connected to the heat exchanger 1 more effectively.
The broader the individual flat tubes 6 are, and the smaller the spacing between the individual flat tubes 6 is, the less is the need for a panel 8 of said type. In order that the thermal heat transfer is as far as possible not impeded, it is advantageous for the panel 8 to be formed from a material with the best possible heat conducting properties, for example aluminum or an aluminum alloy. It is likewise advantageous for the panel 8 to be connected to the flat tubes 6 as cohesively as possible, such that no unnecessary air cushions, which would constitute an insulation layer, are formed between the flat tubes 6 and the panel 8.
The collecting boxes 2, 3 may be produced either from a material that exhibits good thermal conductivity, such as a metallic material, or from a plastic or a fiber-reinforced plastic.
The flat tubes 6 are advantageously produced from a material that exhibits good thermal conductivity, for example aluminum. The embodiment of the flat tubes 6 is however not restricted to said material. Alternatively, an embodiment of the flat tubes composed of a plastic is also conceivable.
The fluid inlet 4 and the fluid outlet 5 are arranged on the collecting box 3 such that they point upward, away from the collecting box 3. This illustration is merely an exemplary illustration of the fluid inlet 4 and of the fluid outlet 5 and should in no way be regarded as being of a limiting nature. The arrangement of the fluid inlet and/or fluid outlet 4, 5 on some other side surface of the collecting box 3 is likewise conceivable. The arrangement of the fluid inlet and/or fluid outlet on the opposite collecting box 2, or the provision of a fluid inlet on one of the two collecting boxes and the provision of the fluid outlet on the respective other one of the collecting boxes, is also conceivable.
By means of such an arrangement of the fluid inlet and/or fluid outlet, the heat exchanger would be traversed by flow either with an I-shaped throughflow configuration or, if a multiplicity of partitions is arranged within the collecting boxes, with a multiply diverted flow configuration.
FIG. 2 shows a detail view of the collecting box 3 of the heat exchanger 1, as has already been shown in FIG. 1. It can be seen particularly clearly that the collecting box 3 is of multi-part construction and is composed of a main body 14 which is closed off laterally by a cover 10. The main body 14 has both the fluid inlet 4 and also the fluid outlet 5. The internal volume 15 of the main body 14 is divided into two chambers 11, 12 by a partition 13. In the exemplary embodiment shown in FIG. 2, the chamber 11 is in fluid communication with the fluid inlet 4. The second chamber 12 is in fluid communication with the fluid outlet 5.
The main body 14 is formed substantially by a box which is closed on five sides and open on one side. The open side, which can be closed by means of the cover 10, is situated opposite the side which has the openings 7 into which the flat tubes 6 are inserted.
The production of the collecting box 3 in a multi-part embodiment is advantageous in particular because the individual components can be produced more easily, for example by injection molding techniques. The connection of the main body 14 to the cover 10 is possible through the use of a welding process. Since ideally both the main body 14 and also the cover 10 are produced from the same material, this use of a welding process is particularly advantageous.
In alternative embodiments, as already indicated with regard to the description of FIG. 1, a division of a collecting box into more than two chambers is also conceivable. By means of a division of the collecting box into more than two chambers, it would be possible to realize a situation in which the fluid is diverted multiple times within the heat exchanger 1. This would have the effect that the fluid covers an altogether longer flow path within the heat exchanger. This may be advantageous in particular in order to increase the heat transfer.
The panel 8 which is shown both in FIG. 1 and also in FIG. 2 serves to provide a closed planar contact surface for the connection of components to be cooled or to be heated to the heat exchanger 1. A further advantage of the panel 8 is that the panel 8 can have for example an electrically insulating coating or a foil applied to it already before an assembly process, which prevents for example the formation of short circuits between the components to be cooled or to be heated and the heat exchanger 1.
The application of a coating to the panel 8 already before the assembly process has the effect of considerably simplifying the assembly of the heat exchanger 1, and thus contributes to a reduction in costs of the production process.
A particular advantage of a heat exchanger 1 as shown in FIGS. 1 and 2 is that the overall structural length of the heat exchanger 1 can be easily adapted at any time through corresponding variation of the length of the flat tubes 6. It is thus ensured that, by means of the basic structural form of the heat exchanger 1, it is possible for components of different sizes to be cooled or heated, without it being necessary to fundamentally change the construction of the heat exchanger 1.
FIG. 3 shows a detail view of the connecting point between a flat tube 21 and a collecting box 20. The flat tube shown in FIG. 3 is divided, in its interior, into multiple chambers 22. The flat tube 21 likewise has two substantially opposite large surfaces which are connected to one another at the sides by two short surfaces. Here, the two large surfaces of the flat tube 21 lie parallel to the top side and bottom side, respectively, of the collecting box 20.
The collecting box 20 has in each case one opening 23 for each flat tube 21. Said opening 23 has an opening edge 28 which tapers conically. The opening cross section of the opening 23 narrows toward the internal volume 26 of the collecting box 20 as viewed from the outer edge 27 of the collecting box 20. Here, the opening 23 is dimensioned such that the clear width of the opening cross section of the opening 23 is smaller than the width of the outer contour of the tube 21.
This has the effect that the flat tube 21 can be pushed into the opening 23 of the collecting box 20 only with the exertion of a certain force. Owing to the opening cross section of the openings 23 being smaller than the cross section of the flat tube 21, a deformation of the collecting box 20 takes place as the flat tube is pushed into the opening 23. As a result of such a deformation, forces are generated which act on the outer surfaces of the flat tube 21 and which fix the latter in the opening 23 of the collecting box 20.
In FIG. 3, the reference sign 25 denotes two regions which are each deformed as a result of the flat tube 21 being pushed in. The regions denoted by the reference sign 25 form the location of the smallest opening cross section of the openings 23. Said regions simultaneously form the clear width of the openings 23. Said regions are deformed and displaced by the flat tube 21.
Said deformed region 25, which in FIG. 3 is illustrated at the top side and at the bottom side of the flat tube 21, ideally runs around the entire circumference of the openings 23 in order to produce an altogether fluid-tight connection between the flat tube 21 and the collecting box.
As a result of the conical design of the opening edge 28, there is formed between the flat tube 21 and the collecting box 20 a groove 29 which, in FIG. 3, has a triangular basic shape. Said groove 29 is open in an outward direction, away from the collecting box.
The groove 29, which is formed in an encircling manner around the entire flat tube 21, serves for example for receiving an adhesive 24. The flat tube 21 can thus be fixed on the collecting box 20 not only by the press fit in the opening 23 but also by means of an adhesive 24. It is advantageous here in particular that the adhesive 24 is isolated in an effective manner so as to be prevented from coming into contact with the fluid that flows within the flat tube 21 or the collecting box 20. In this way, the adhesive need not be configured so as to be resistant to any corrosive effects of the fluid or other detrimental influences of the fluid on the adhesive 24.

Claims

1. Heat exchanger having a first collecting box and having a second collecting box, having at least one tube arranged between the two collecting boxes, wherein a fluid inlet and a fluid outlet are provided which are arranged individually on in each case one of the collecting boxes or on a single one of the collecting boxes, wherein the tube is received at the ends in an opening in in each case one of the collecting boxes and is in fluid communication with the collecting boxes, wherein the opening is surrounded by an opening edge whose contour corresponds to the outer contour of the tube, and in the opening is designed such that the opening cross section narrows toward the interior of the collecting box and the tube can be inserted, under preload at the circumference, into the opening.

2. Heat exchanger according to claim 1, wherein the tube is in the form of a flat tube.

3. Heat exchanger according to claim 1, wherein the inner contour of the opening can be deformed as a result of the tube being pushed in.

4. Heat exchanger according to claim 1, wherein, in the assembled state, a groove which is accessible from outside the collecting box is formed between the tube and the opening edge.

5. Heat exchanger according to claim 1, wherein the tube and the collecting boxes can be adhesively bonded and/or welded and/or pressed together and/or insert-molded with one another.

6. Heat exchanger according to claim 1, wherein at least one of the collecting boxes is of multi-part form and has a box opening, the latter being closable by means of a cover, and has a tube plate with at least one opening for receiving a tube wherein the box opening is arranged opposite the tube plate.

7. Heat exchanger according to claim 1, wherein the heat exchanger has a multiplicity of tubes which run parallel to and spaced apart from one another.

8. Heat exchanger according to claim 7, wherein the tubes lie in a common plane and/or lie offset with respect to one another in multiple planes.

9. Heat exchanger (1) according to claim 7, wherein an areal panel is mounted onto the tubes, by means of which panel said tubes are connected to one another.

10. Heat exchanger according to claim 1, wherein the fluid inlet and the fluid outlet are arranged on the same collecting box, wherein said collecting box has a partition which divides the internal volume of the collecting box into two chambers, and the fluid inlet is in fluid communication with one of the chambers and the fluid outlet is in fluid communication with the other chamber.