HEAT EXCHANGER

Abstract

The invention relates to a heat exchanger in which a liquid coolant and a gaseous flow, for example compressed charge air, are involved in the exchange of heat, with at least two heat exchanger blocks being provided which can be traversed by the coolant and by the gaseous flow. The invention can include inventive solutions for a flat arrangement including at least one gas-side bypass arranged adjacent to or within the first heat exchanger block and/or adjacent to or within the second heat exchanger block. The present invention also provides a method for cooling that divides the gaseous flow into at least two partial flows. One partial flow can be guided past a heat exchanger block, and the other partial flow can be conducted through the other heat exchanger block before the partial flows are finally merged.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

Priority is hereby claimed to German Patent Application No. DE 10 2006 048 667.6, filed Oct. 14, 2006, the entire contents of which is incorporated herein by reference.

FILED OF THE INVENTION

The present invention relates to a heat exchanger arrangement in which a liquid coolant flow and a gaseous flow, such as, for example, compressed charge air, are involved in the exchange of heat, with at least two heat exchanger blocks being provided which can be traversed by the coolant flow and by the gaseous flow. The present invention also relates to a method for the exchange of heat between a gaseous flow and a liquid coolant flow.

SUMMARY

DE-A 2 655 017 discloses a relevant heat exchanger. DE 199 62 391 A1 discloses a further developed heat exchanger. The heat exchanger of DE-A 2 is constructed for the purpose of pre-cooling charge air. A first exchange of heat is carried out between lubricating oil of the internal combustion engine and compressed charge air in a first heat exchange block, and in a second heat exchanger block, a second exchange of heat is carried out between the cooling liquid of the internal combustion engine and the charge air leaving the first heat exchanger block. In order to obtain favorable overall conditions, this document also describes the possibility of coolant-side bypasses. In this way, the combustion air can be pre-heated at idle or in the partial-load range of the internal combustion engine (see, for example FIG. 6 and description, page 9 of said document).

DE 2 923 852 also discloses a conventional heat exchanger. EP 1 279 805 A2 discloses a further-developed design. Here, the charge air is initially cooled with liquid and subsequently by cooling air, with the two heat exchangers forming a common arrangement.

There are additionally several further disclosures in the field of charge air cooling. Also, singled out from the multitude is EP 522 471 B1 which describes and shows an air-cooled charge air cooler arrangement in which the heat exchanger block is divided into two sub-blocks, with one sub-block having been arranged for example upstream of the radiator which is acted on with cooling air, and the other sub-block having been arranged offset in height with respect to and downstream of the radiator. The charge air initially flows into the first sub-block and thereafter into the second sub-block via a connecting duct or the like. In this way, the cooling capacity of the entire cooler arrangement can be raised or at least positively influenced.

The physical configuration of the heat exchanger and its arrangement is delegated to specialists who are to implement the specifications of the user, for example of the motor vehicle manufacturer. The specifications involve inter alia the attainment of a low pressure loss with sufficient cooling power under usually restricted spatial conditions.

In particular, the charge air, which is compressed with high energy expenditure, is to be cooled and arrive at the engine under high pressure, which means that the charge air pressure may not be reduced to too great a degree before said point as a result of necessary cooling measures etc. In addition, the installation space of the heat exchanger arrangement can, for example, be situated beneath the drive unit, with it being necessary to maintain a certain degree of ground clearance. The obvious measure which a person skilled in the art would implement would possibly be that of designing the heat exchanger arrangement to be not particularly high but rather to be substantially flat, wherein the entire heat exchanger area would need to remain unchanged in order to be able to provide the demanded cooling capacity. Said measure would however not be satisfactory from the point of view of the pressure loss, which is known to increase with longer flow paths of the heat exchanger block.

Finally, EP 1 491 837 A1 discloses a heat exchanger which is embodied as a cooler for recirculated exhaust gases, but which however could be a charge air cooler. In said document, an exhaust gas bypass is provided, through which the entire exhaust gas flow approaching the heat exchanger is to flow in certain operating states of the internal combustion engine of a vehicle.

It is an object of the invention to produce and provide a heat exchanger arrangement which is of flat construction and can inter alia meet the demands for a low pressure loss. In order to solve these and other problems, a working method for cooling, for example, charge air is also to be provided.

The present invention provides improvements to exiting heat exchangers. Because in each case one gas-side bypass is arranged adjacent to the first and preferably also adjacent to the second heat exchanger block, an arrangement of flat construction is provided which is characterized by a low pressure loss, which is to be attributed to the bypasses. The bypasses are essentially relatively smooth-walled tubes through which the partial flows of the, for example, charge air can flow without experiencing noticeable pressure loss. In the present context, the term “adjacent” means either above or below, to the left-hand side or to the right-hand side or an arrangement in which the bypass and the heat exchanger block run adjacent to one another in some other manner. The bypass could also be situated within a heat exchanger block, which is likewise to be covered by the attribute or the feature “adjacent”.

The heat exchanger arrangement of the present invention can be situated entirely within a compact housing, with it then being possible, but not strictly necessary, for the bypass to run directly along a housing wall.

In contrast, it is however possible for each heat exchanger block to also be designed to be of the housingless type, with the bypass being integrated therein. Situated between the two heat exchanger blocks is then a type of partial housing or a device for carrying out a deflection of the partial flows.

The present invention also provides a heat exchanger having a single bypass arranged at one side of the first heat exchanger block, and a second bypass situated at the other side of the second heat exchanger block. It is possible, in contrast, for one bypass to be arranged at one side of the first heat exchanger block and the other bypass to be situated at the same side of the second heat exchanger block.

Here, it is expedient for the heat exchanger blocks to be arranged so as to be offset in height as viewed in the flow direction of the gaseous flow. This is favorable if one bypass is situated above the first heat exchanger block and the other bypass is situated below the second heat exchanger block. The present invention alternatively provides heat exchanger blocks which are arranged at a common height as viewed in the flow direction of the charge air.

In order to correspondingly deflect the partial flows, the present invention also provides at least one device for conducting the partial flows between the heat exchanger networks. Here, the one partial flow is to be conducted from the first bypass into the second heat exchanger block, and the second partial flow approaching from the first heat exchanger block can be deflected into the second bypass.

If only one bypass is provided, the heat exchanger blocks can have different heights. The bypass is situated on the flatter block. The as yet uncooled charge air enters into the higher second block together with the charge air which is already cooled in the first block.

In order to suppress thermal influences, the present invention can provide insulation arranged between the bypass and the heat exchanger block. The insulation can also be provided in the form of an air gap between the bypass and the heat exchanger block.

The method for cooling, for example, charge air, with a liquid coolant, with a charge air flow and a liquid coolant flow being conducted through at least two heat exchanger blocks, includes the acts of a) dividing the charge air into at least two partial flows, b) guiding one partial flow past a heat exchanger block, c) conducting one partial flow through a heat exchanger block, and d) merging the partial flows.

In some embodiments of the present invention, the sequence of the steps can be varied. It can for example be the case that the division of the flow into partial flows is carried out only after the flow passes through the first block. The merging of the partial flows can take place after the flow passes through the entire arrangement, or alternatively, even within a block. In some embodiments, it can be advantageous for the liquid coolant flow to be initially conducted into the second heat exchanger block and subsequently into the first heat exchanger block. Liquid coolant can also be a two-phase coolant.

In other embodiments, the coolant flow can initially be conducted into the first heat exchanger block and subsequently into the second heat exchanger block. This ultimately means that the two heat exchanger networks can be situated in the same cooling circuit.

Depending on the concrete requirements, however, the heat exchanger of the present invention can include a plurality of cooling circuits, with each heat exchanger network being connected into different cooling circuits or air-conditioning circuits, and thereby being operated with liquid coolant or refrigerant.

In the arrangement of the present invention, it is possible for two identically-designed heat exchanger blocks to be used, which has definite production-related advantages. It is also possible to use different heat exchanger blocks in one arrangement.

The heat exchanger blocks can be constructed from stacked plate pairs, with in each case one plate pair forming, in its interior, a flow duct for the coolant. In each case one flow duct, which is provided with turbulators, for the charge air is situated between the plate pairs. A housing can enclose the stack.

In contrast, the heat exchanger blocks can be constructed from flat tubes with or without inner inserts, and from fins or the like which are arranged between the flat tubes, similarly to a radiator block. A housing can enclose the stack.

The heat exchanger blocks can however also be constructed as plate heat exchangers with trough-shaped heat exchanger plates, or alternatively, can be of bar/plate design, with it being possible for the bypass to be designed as a bypass line past a plate heat exchanger. Finally, the blocks can also be constructed according to further known principles.

Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is perspective view of a heat exchanger according to a first exemplary embodiment of the present invention.

FIG. 2 shows a partial perspective view of the heat exchanger shown in FIG. 1.

FIGS. 3 and 4 show a heat exchanger according to a second exemplary embodiment.

FIGS. 5 and 6 show a heat exchanger according to a third exemplary embodiment.

FIG. 7 is an exploded perspective view of a heat exchanger block of the present invention.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.

The heat exchanger arrangements shown and described below could also be used in other applications, such as, for example, as an exhaust gas heat exchanger in motor vehicles. Alternatively or in addition, the heat exchanger arrangements could be used for any other desired purpose which is dependent on the lowest possible pressure loss, for example, on the gas side and which are constructed with a relatively flat design.

The depicted heat exchanger arrangements represent charge air coolers and are thus referred to as such below. In the charge air cooler, the compressed charge air is cooled by a cooling liquid of the engine of a utility vehicle. In FIG. 1, the charge air is shown by solid arrows and the cooling liquid is shown by dashed arrows. The charge air cooler is of flat construction, because it should be fastened (not shown) to the underside of the drive unit of a utility vehicle. For this purpose, the charge air cooler is equipped with a plurality of connectors 10. Illustrated are four cantilevers which have bores at their ends.

The charge air cooler has a housing G in which are situated two heat exchanger blocks A and B. The first heat exchanger block A as viewed in the flow direction of the charge air is arranged slightly lower than the second heat exchanger block B. Situated above the first heat exchanger block A is a bypass C. Situated below the second heat exchanger block B is a further bypass C.

The compressed and heated charge air entering through the inlet is, in this exemplary embodiment, divided into two partial flows. The first partial flow passes through the first bypass C and the second partial flow flows through the first heat exchanger block A. The second partial flow leaving the first heat exchanger block A has correspondingly been cooled and flows via the second bypass C in the direction of the outlet. It is possible for insulation to be provided therein in order to prevent the partial flow being heated again. The first partial flow passing from the first bypass passes through the second heat exchanger block B in order to likewise be cooled.

Downstream of the second heat exchanger block B, the two partial flows are merged and are made available as a cooled charge air flow, which has been only slightly reduced through pressure loss, for charging the internal combustion engine (not shown). A cross section which is drawn in FIG. 1 can also effectively demonstrate the above-described substantive matter with regard to the working method carried out with the arrangement. In the illustrated embodiments, the inlets and outlets are constructed as relatively smooth-walled tubes which can generate only a negligible pressure loss. The interior of the heat exchanger blocks A and B is designed so as to generate a division into partial flows.

The heat exchanger blocks A and B can be of substantially identical design. Situated between the two heat exchanger blocks A and B is a guide device D which provides the described guidance of the partial flows. The guide device D is of a flow-promoting shape. In the exemplary embodiment, both heat exchanger blocks A and B are traversed in series at the liquid side by the cooling liquid, as is intended to be indicated by the dashed lines. Because, in the exemplary embodiment, all of the inlets and outlets for the cooling liquid are situated on one side, it is clear that each heat exchanger block A and B is traversed by the cooling liquid in a U-shape, while the charge air can flow transversely with respect thereto but on a straight path through the heat exchanger blocks A and B. In FIG. 2, the U-shaped throughflow has been indicated at the heat exchanger block B. Here, only one “U” has been indicated. It is however also possible for multiple U-shaped loops, that is to say a meandering flow, to be provided.

In contrast to the described exemplary embodiment, the heat exchanger blocks A and B in FIGS. 3 and 4 are situated at a common height, and the bypasses C have been arranged at opposite ends of the heat exchanger blocks A, B. A guide device D is provided between the blocks A and B.

In the exemplary embodiment shown in FIGS. 5 and 6, three partial flows are provided on the charge air side. With the selected throughflow, the charge air passes through two bypasses C which are situated at the outside of the first heat exchanger block A, and through a bypass C which is situated at the inside of the second heat exchanger block B. The throughflow direction can be selected both on the charge air side and also on the liquid side. The first heat exchanger block A is situated approximately at a central region in the housing G in which the one bypass C is also situated. The second heat exchanger block B, which could also be composed of two heat exchanger blocks, is situated in the two outer regions in the housing G in which the two bypasses C are situated. The guide device D is composed here of two walls, as the figures show. The exemplary embodiments shown already reveal that at least some further variations of the arrangement of heat exchanger blocks and bypasses, which have all of the steps of the working method, are possible and appear to be expedient. For example, it is also possible for more than two heat exchanger blocks to be arranged in series in the flow direction of the charge air.

FIG. 7 shows a partially exploded illustration of a heat exchanger block which is suitable for the proposed arrangement. The heat exchanger block is composed of heat exchanger plates 2 which form in each case one pair. At the opposite ends, each plate pair in the exemplary embodiment shown is closed off by inserted rods 3 and 4. At the longitudinal sides, the plates 2 are provided with shaped edge flanges in order to close off the space within a plate pair.

The cooling liquid flows within each pair. The plates 2 are formed with beads 7 or similar formations in such a way that the cooling liquid must pass through a plurality of U-shaped paths in order to pass from the inlet to the outlet. Arranged between the pairs are corrugated fins 5 or similar elements, through which one partial flow of the charge air flows. The block arrow is intended to show this. The stack of plates 2 and corrugated fins 5 is provided at the top and at the bottom with one closure plate 1, 6 which are formed to be slightly more stable than the other plates 2. Blocks of this type can be arranged within the housing G which is shown. It is however also possible to use blocks of some other design, which need not strictly be situated in a housing G which is closed off at all sides. It is also possible for one block to be arranged in a housing G and for the other block to be designed to be of the housingless type.

Various features and advantages of the invention are set forth in the following claims.

Claims

1. A heat exchanger for transferring heat between a liquid coolant flow and a gaseous flow, the heat exchanger comprising:

a pair of heat exchanger blocks being traversed by the coolant flow and the gaseous flow;

a gas bypass arranged adjacent to or within the first heat exchanger block; and

a gas bypass arranged adjacent to or within the second heat exchanger block, a first partial flow of the gaseous flow being directed through the gas bypass of the first heat exchanger and a second partial flow of the gaseous flow being directed through the gas bypass of the second heat exchanger.

2. The heat exchanger of claim 1, wherein one bypass is arranged at one side of the first heat exchanger block, and wherein an other bypass is situated at an opposite side of the second heat exchanger block.

3. The heat exchanger of claim 1, wherein one bypass is arranged at a side of the first heat exchanger block and an other bypass is situated at a corresponding side of the second heat exchanger block.

4. The heat exchanger of claim 1, wherein the heat exchanger blocks are arranged so as to be offset in height with respect to a flow direction of the gaseous flow.

5. The heat exchanger of claim 1, wherein the heat exchanger blocks are arranged at a common height with respect to a flow direction of the gaseous flow.

6. The heat exchanger of claim 1, wherein the blocks are spaced apart, and wherein at least one guide for conducting the first and second partial flows extends through the space between the heat exchanger blocks.

7. The heat exchanger of claim 1, wherein the blocks bear directly against one another and have different heights, and wherein one of the bypasses is arranged at least on or in the flatter block.

8. The heat exchanger of claim 1, wherein insulation can be provided between the bypass and one of the pair of the heat exchanger blocks.

9. A method of transferring heat between a gaseous flow and a liquid coolant in a heat exchanger having at least two heat exchanger blocks, the method comprising the acts of:

dividing the gaseous flow into at least two partial flows;

directing a first partial flow through one of the two heat exchanger blocks;

directing a second partial flow through another of the two heat exchanger block; and

merging the one and the other partial flows.

10. The method of claim 9, wherein the first partial flow is guided past a first one of the pair of heat exchanger blocks, wherein the second partial flow is conducted through the first heat exchanger block, wherein the first and second partial flows are conducted through the second heat exchanger block, and wherein the first and second partial flows are merged either at the second heat exchanger block or downstream therefrom.

11. The method of claim 9, wherein the second partial flow is directed past the first heat exchange block, and wherein the first partial flow is directed past the second heat exchanger block through the second heat exchanger block, and wherein another partial flow is guided past the second heat exchanger block before being merged with the second partial flow.

12. The method of claim 9, wherein the coolant flow is initially conducted into the second heat exchanger block and subsequently into the first heat exchanger block.

13. The method of claim 9, wherein the coolant flow is initially conducted into the first heat exchanger block and subsequently into the second heat exchanger block.

14. The method of claim 9, wherein the coolant flow which flows through the one of the two heat exchanger blocks belongs to a different circuit than the coolant flow which flows through the other of the two heat exchanger blocks.

15. The method of claim 14, wherein the coolant which flows through the one of the two heat exchanger block being different than the coolant flow which flows through the other of the two heat exchanger blocks.

16. The method of claim 14, wherein the coolant which flows through the one of the two heat exchanger block being the same as the coolant flow which flows through the other of the two heat exchanger blocks.