Patent Application
20140090811
Heat exchanger having a housing, having a first fluid port and having a second fluid port, wherein the housing is in fluid communication with a fluid source via the first fluid port and the second fluid port and can be traversed by a flow of a fluid.
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 hydride 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 plates, one or more fluid ducts through which a fluid can flow.
It is advantageous here for all of the cells of the energy store to be kept at a uniform temperature level. Likewise, intense temperature gradients within the cells should be avoided.
The plates of the heat exchangers can be traversed by a flow of a cold fluid during cooling, though 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 composed entirely from aluminum. These are considerably heavier in relation to designs composed of plastic or of a mixture of aluminum and plastic. Also, owing to the electrical conductivity of the aluminum, there is a need for electrical insulation and for potential equalization means for the heat exchangers. Furthermore, the production of heat exchangers from aluminum is energy-intensive and expensive. Furthermore, as a result of the use of brazing materials such as flux, for example, reworking steps are often necessary.
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 less energy-intensive and less expensive. Furthermore, the heat exchanger should be formed without additional electrical insulation.
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 housing, having a first fluid port and having a second fluid port, wherein the housing is in fluid communication with a fluid source via the first fluid port and the second fluid port, wherein the housing can be traversed by a flow of a fluid, wherein the housing is of multi-part design and is formed substantially by a planar housing upper part and a substantially trough-like housing lower part, wherein the housing lower part has a base region and encircling edge regions, wherein the housing upper part or the housing lower part is formed from a plastic and the respective other housing part is formed from a plastic, a metallic material or a fiber composite material.
In one exemplary embodiment, the heat exchanger according to the invention serves for controlling the temperature of an energy store.
The construction of the housing of the heat exchanger from elements composed of plastic and elements composed of a metallic material, in particular of aluminum or an aluminum alloy, is particularly advantageous with regard to the weight of the heat exchanger. Through the use of plastics, the weight can be reduced in relation to a heat exchanger manufactured entirely from a metallic material. At the same time, by means of the elements composed of metallic materials, it remains possible to achieve good thermal conductivity.
The formation of the housing lower part as a trough-like element is particularly advantageous because a stabilizing action is realized by means of the at least partially encircling turned-up edge regions. At the same time, the housing lower part forms, in the interior of the housing, a cavity which can be traversed by a flow of a fluid. The housing lower part can be closed off in the upward direction by means of the housing upper part. In this way, a space is generated which is closed off in a completely fluid-tight manner and which can be traversed by a flow of a fluid.
Both the housing lower part and also the housing upper part are simple and inexpensive to produce and can be connected to one another by means of numerous connecting methods. Aside from the use of thermal joining processes, the two elements may also be connected to one another by mechanical or chemical connecting means.
It is furthermore advantageous for at least one flow-guiding element to be arranged in the interior of the housing. By means of a flow-guiding element in the interior of the housing, the fluid flow can be influenced in a targeted manner.
It is also preferable for the housing lower part to be formed from a plastic.
The housing lower part may advantageously be manufactured from a plastic. This reduces the weight in relation to an embodiment composed of a metallic material. Furthermore, the production of the housing lower part from a plastic is simpler and involves fewer working steps than the production of a housing lower part from a metallic material.
The housing lower part may for example be produced in unipartite form in an injection-molding process. A housing lower part produced in an injection-molding process has no joints, which need to be sealed off in a fluid-tight manner by way of additional working steps, at the turned-up edge regions.
Furthermore, the housing lower part composed of plastic can be connected to other elements in a simple manner through the use of an adhesive.
In a further embodiment of the invention, it may be provided that the housing upper part is formed from a metallic material, in particular from aluminum or an aluminum alloy.
The formation of the housing upper part from a metallic material is advantageous because a greater coefficient of heat transfer can be obtained by means of the metallic material than by means of a plastics component. The elements to be cooled or to be heated are therefore advantageously in thermal contact with the metallic housing upper part.
Furthermore, a stabilizing action can be imparted by the metallic housing upper part, which makes the heat exchanger less sensitive to the action of external mechanical loads.
Furthermore, elements to be cooled, which are for example composed of metallic material, can be attached to the housing upper part in a simple manner using known methods such as brazing or welding.
It is also advantageous for the housing to have a multiplicity of flow-guiding elements in its interior. The fluid flow in the housing can be influenced in an advantageous manner by means of a multiplicity of flow elements.
It is furthermore preferable if the flow-guiding elements are in the form of webs or walls or studs, and form between them at least one flow duct for the fluid.
In a further alternative embodiment, it may be provided that the flow-guiding element runs parallel to at least one of the turned-up edge regions of the housing lower part.
By means of a configuration of a flow-guiding element or of multiple flow-guiding elements as described above, it is possible to generate a multiplicity of flow ducts which extend through the housing substantially parallel to one of the outer edges thereof. This may be advantageous for the distribution of the fluid. By means of such a configuration of the flow-guiding elements, the fluid can for example be conducted in a targeted manner from one fluid port to a further fluid port.
By means of the generation of flow ducts, it is also possible for the distribution of the fluid within the housing to be influenced.
Here, the flow-guiding elements may for example be formed from rectilinear walls or webs or by means of individual nipple-like elevations. Other configurations of the flow-guiding elements may also be provided.
Aside from flow guidance, said elements may also be used for changing a laminar flow into a turbulent flow in order to achieve more intense mixing of the fluid, and thereby improve the heat transfer.
In a particularly expedient refinement of the invention, it may also be provided that, in the fully assembled state, the flow-guiding element or the flow-guiding elements are in contact with the housing upper part and with the housing lower part.
By means of contact of the flow-guiding element or of the flow-guiding elements with both the housing upper part and also the housing lower part, it can be achieved that the fluid flows only around and not over the flow-guiding elements, because said flow-guiding elements, at their top side and bottom side respectively, are in direct contact with the housing lower part and with the housing upper part. If at least some of the flow-guiding elements are in the form of walls, contact both with the housing upper part and also with the housing lower part can serve to form flow ducts which can be traversed by a flow of the fluid.
Furthermore, in an advantageous refinement, it may be provided that the housing upper part or the housing lower part has the first fluid port and the second fluid port, or that the housing upper part and the housing lower part have in each case one of the two fluid ports.
It is also expedient for the first fluid port and/or the second fluid port to be formed by an opening on one of the turned-up edge regions of the housing lower part.
By means of an arrangement of one fluid port or both fluid ports on one of the turned-up edge regions, it is possible for the fluid to be supplied and discharged laterally. This is particularly advantageous because, in this way, the substantially planar main surfaces of the housing upper part and of the housing lower part can be used entirely as heat transfer surfaces. Said solution is also advantageous if only a very small amount of installation space is available.
In a further preferred exemplary embodiment, it may be provided that the housing has, in its interior, a partition which divides the internal volume of the housing into a first chamber and a second chamber which are in fluid communication with one another via a break in the partition.
The division of the internal volume into a first chamber and a second chamber is particularly advantageous because, in this way, it is possible to generate an ordered flow of the fluid within the housing.
A preferred exemplary embodiment may be characterized in that one of the fluid ports is in fluid communication with the first chamber and the respective other fluid port is in fluid communication with the second chamber.
By means of such an assignment of the fluid ports to in each case one of the chambers, a flow path is predefined for the fluid. Here, the fluid flows through one fluid port into one of the chambers and passes over, along the break in the partition, into the second chamber. There, the fluid flows along the second chamber to a second fluid port and out of the housing. Furthermore, by means of such a guided flow, the generation of flow build-up points, which can lead to local excessive increases in temperature, is prevented.
Advantageous refinements of the present invention are described in the subclaims and in the following description of the figures.
The invention will be explained in detail below on the basis of exemplary embodiments and with reference to the drawings, in which:
The housing upper part 3 has a substantially planar extent. The housing lower part 2 is formed substantially from a trough-like base region with turned-up edge regions. The housing upper part 3 is dimensioned so as to close off the housing lower part 2 with an accurate fit. A fluid-tight connection can thus be generated between the housing upper part 3 and the housing lower part 2. The internal volume that is formed between the housing lower part 2 and the housing upper part 3 corresponds to the volume of the housing 9 which can be traversed by a flow of a fluid.
The housing lower part 2 has a multiplicity of flow-guiding elements 4, 5. Furthermore, the housing lower part 2 has a partition 8 which runs in the interior and which divides the internal volume of the housing 9 of the heat exchanger 1 into a first chamber and a second chamber. The first chamber is in fluid communication with the second chamber at at least one location in the interior of the heat exchanger 1. Said location at which the fluid communication between the first chamber and the second chamber takes place is advantageously situated in a region as far remote from the fluid ports 6, 7 as possible.
The flow-guiding elements 4 shown in
In the front region of the heat exchanger 1, which also has the fluid ports 6, 7, the flow-guiding elements 5 are provided instead of the flow-guiding elements 4. The flow-guiding elements 5 are individual studs which are arranged in the interior of the housing lower part 2. Said flow-guiding elements 5 serve primarily for controlling the flow of the fluid that can flow into the heat exchanger 1 through the fluid port 6 or fluid port 7. The individual studs allow the fluid to distribute over the width of the respective chamber before the fluid flows into the flow ducts formed by the flow-guiding elements 4.
Flow-guiding elements 5 are likewise arranged in the rear region of the heat exchanger 1 situated substantially opposite the fluid ports 6, 7. In said region, the fluid flows out of the flow ducts between the flow-guiding elements 4, and there, flows over from one chamber into the respective other chamber. In this case, the flow-guiding elements 5 serve for generating turbulence in the fluid in order to generate a more uniform distribution of heat. The respective other chamber of the heat exchanger 1 is of corresponding construction to the first chamber. The second chamber likewise has flow-guiding elements 5 in the region in which the flow passes out of the first chamber, and has flow-guiding elements 4 in the form of walls along the second chamber. Likewise, below the fluid port 7, the second chamber again has the stud-like flow-guiding elements 5 which allow the fluid from the individual flow ducts to be collected and conducted to the fluid port 7.
Here, both the flow-guiding elements 4 and also the flow-guiding elements 5 are illustrated merely by way of example. Designs which differ from these may also be provided in alternative embodiments. For example, walls which run in a zigzag pattern or walls which follow an undulating shape may also be provided for the flow-guiding elements 4. Instead of the studs, there may also be provided embossed elevations and depressions, or for example spherical elements that serve to generate turbulence in the flow.
The fluid ports 6, 7 may be arranged on the housing upper part 3 as shown in
The heat exchanger 1 shown in
Both the housing upper part 3 and also the housing lower part 2 may be produced from metallic materials, for example aluminum or an aluminum alloy. Alternatively, both the housing upper part 3 and also the housing lower part 2 may be produced from a plastic or a fiber-reinforced plastic. In one particularly advantageous embodiment, the housing lower part 2 is formed from a plastic and the housing upper part 3 is formed from a metallic material.
It is possible to particularly clearly see the flow-guiding elements 4 which are designed as rectilinear walls running parallel to the outer edges and parallel to the partition 8. In the front and rear edge regions, stud-like flow-guiding elements 5 are provided instead of the rectilinear walls of the flow-guiding elements 4.
In an alternative embodiment, the flow-guiding elements 5 may also be omitted. It is a task of the flow-guiding elements 5 to generate a distribution of a fluid transversely with respect to the main flow direction predefined for the fluid between the flow-guiding elements 4. In particular in conjunction with the fluid ports 6, 7 shown in
The connection of the housing lower part 2, which is advantageously formed from plastic, and of the housing upper part 3, which is formed from an aluminum material, may advantageously be realized by welding. The advantage that arises through the use of a metal material for the housing upper part 3 lies in the fact that a metallic material generally exhibits a better coefficient of thermal conductivity, whereby the heat transfer from the heat exchanger 1 to components arranged outside the heat exchanger 1 is improved. At the same time, the formation of the housing lower part 2 from a plastic offers the advantage that electrical insulation is provided by the housing lower part 2 itself. Furthermore, the housing lower part 2 can be produced in a simple method such as injection molding, for example. It is thus possible for not only the basic shape of the housing lower part 2 but also the flow-guiding elements 4, 5 to be produced in one working step, whereby process steps can be eliminated, and thus cheaper production is attained.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2012 217 872.4 | Sep 2012 | DE | national |
