EP2998675A1 - Heat exchanger - Google Patents

Abstract

The invention relates to a heat exchanger, in particular exhaust gas cooler or intercooler, comprising a disk stack (2) consisting of a plurality of elongated disk pairs (32), two disks (18, 18 ') connected to each other forming a first fluid channel (4) between them and between them two disc pairs a second fluid channel (30) is formed, wherein the discs of a disc pair U-shaped with bottom and raised side walls are formed and each other to limit the first flow channel, wherein one of the discs of a pair of discs on its front side has a tab, which serves for beading around the front side of the other disc, characterized in that the flanging of the tab is made at the bottom of the disc and the flanging of the tab also continues into the side walls of the discs.

Description

Technical area

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

State of the art

Exhaust coolers have the task of cooling hot exhaust gas from internal combustion engines, so that this cooled exhaust gas can be added to the intake air again. In this case, to increase the thermodynamic efficiency of an internal combustion engine, the cooling to a very low level. This principle is generally known as cooled exhaust gas recirculation and is used to achieve a reduction of pollutants, in particular nitrogen oxides, in the exhaust gas.

From the DE 100 24 389 A1 , of the DE 10 2005 034 137 A1 and from the WO 2014/040797 A1 Such heat exchangers have become known, which are formed from a stack of disc pairs, wherein between a pair of discs, a first flow channel is formed and between two stacked disc pairs a second flow channel is formed.

In this case, the first flow channel is usually closed to the outside and can be fluidly connected to a fluid channel only via inlet and outlet openings in the stack or on a housing comprising the stack, in order to introduce or dispense a first fluid into the first flow channel. In this case, the first fluid is usually a cooling fluid, such as cooling water.

The second flow channel is also usually designed to be open on its narrow side in order, for example, to distribute a second fluid to or from the plurality of second flow channels via an intended connection element, which are arranged adjacent to one another and stacked. In this case, a gas is used as the second fluid, such as air, exhaust gas or an exhaust gas-air mixture.

In these heat exchangers, the inflowing second fluid is usually very hot, so that the leading edge of the pairs of discs on the inflow side of the second fluid in the heat exchanger is exposed to very high thermal stress.

The temperature transition from the very hot uncooled gas inlet region of the second flow channel to the region of the heat exchanger in communication with the coolant leads to high stresses due to the different thermal expansion due to the different temperatures.

Furthermore, the gas flow in the inlet region of the hot gas is usually carried out with relatively thick-walled diffusers to withstand the high pressures and temperatures, the heat-transmitting discs of the heat exchanger from efficiency, cost and Weight reasons are designed as thin as possible. As a result of the different temperatures occurring, the diffuser and the disks expand differently and high stresses result on the thin-walled disks of the disk stack, in particular in the corners of the disks at the hot gas inlet.

Most of the discs or pairs of discs are inserted into a bottom of the heat exchanger, which is connected to a housing and / or the gas inlet diffuser. The bottom is usually thick-walled formed as the discs themselves, so that the risk of failure is reduced by thermal stresses in the transition region to the hot diffuser.

For cost, weight and manufacturing process reasons, however, increasingly seeking to dispense with a bottom and to achieve the sealing of the coolant channels formed as flow channels between a pair of discs by a suitable shaping of the discs. In the WO 2014/040797 A1 the heat exchanger is constructed without coolant housing from substantially U-shaped flow channels.

This results in no straight front edge of the disk pairs, but the channel geometry corresponding to a likewise U-shaped front edge. The channels are plugged into a diffuser and thereby a narrow solder gap is achieved laterally, which leads to a dense soldering of the flow channel. On the remaining front edge, however, there is a risk that the two sheet metal layers of the two discs of a disc pair, which form the top and bottom of the flow channel, not fit snugly together and so soldering and leaks can arise.

To ensure a tight soldering, therefore, the flat front edge of the lower disc of a pair of discs around the leading edge of the upper

Disc of disc pair folded, as flanged. This also increases the strength of the disc leading edge on the flattened flat regions of the flow channel, because there are three layers of material instead of just two layers of material. However, the flanging ends in the corners of the flow channels, ie at the window corners. This results in a notch, at which the thickness of the front edge of three layers or sheet thickness decreases to two layers or sheet thicknesses. It has been shown that exactly in this corner region, however, particularly strong tensile stresses occur due to the heated diffuser and, due to the notch effect, thermally induced failures of the disk pair and thus of the heat exchanger occur.

Presentation of the invention, object, solution, advantages

It is the object of the invention to provide a heat exchanger which is improved over the prior art and has a longer life.

This is achieved with the features of claim 1.

An embodiment of the invention relates to a heat exchanger, in particular exhaust gas cooler or intercooler, comprising a, consisting of a plurality of elongated disc pairs disc stacks, each two interconnected discs form a first fluid channel between them and between two disc pairs a second fluid channel is formed, wherein the disc pair U- is formed with base and raised sidewalls and the discs are superimposed so that they limit the first flow channel, wherein one of the discs of a disc pair at the edge in the inlet and / or outflow for the second fluid, which is usually on the front side of the disc pair is and therefore referred to here as the front side or front edge, has a tab, which for beading around the Front side of the other disc is used, characterized in that the flanging of the tab is made at the base of the disc and the flanging of the tab also continues into the side walls of the discs. As a result, reinforcement is achieved, in particular in the corners between the base and the side walls of the disk pair, which promotes the longevity of the heat exchanger. The base is essentially the bottom of a disc or a disc pair. The front side can also be referred to as a narrow side.

It may be advantageous if the flanging on the side walls is made only up to a height that corresponds to only a part of the total height of the side wall.

According to the invention, it is expedient if the disc has a wall thickness and the height corresponds at least to the wall thickness of the disc, preferably between 3 and 5 wall thicknesses or more. As a result, the corner region is advantageously reinforced, wherein beading around the tab is facilitated at a reduced height.

Alternatively, the flanging on the side walls to reach the total height of the side wall.

It is particularly advantageous if the flanging is made at the base over the entire width of the base. This advantageously reinforces the narrow side of the disk pair over its entire width exposed to the hot fluid flow.

It is also advantageous if the beading on the base is made only partially over the entire width of the base. This makes it easier to flare and save weight.

Further advantageous embodiments are described by the following description of the figures and by the subclaims.

Brief description of the drawings

Fig. 1

eine schematische Ansicht eines erfindungsgemäßen Wärmeübertragers,

Fig. 2

eine Gesamtansicht der unteren Scheibe des Scheibenpaares,

Fig. 3

eine detaillierte Darstellung der unteren Scheibe des Scheibenpaares,

Fig. 4

eine Gesamtansicht der oberen Scheibe des Scheibenpaares,

Fig. 5

eine detaillierte Darstellung der oberen Scheibe des Scheibenpaares,

Fig. 6

eine detaillierte Darstellung einer Scheibe des erfindungsgemäßen Wärmeübertragers,

Fig. 7

eine detaillierte Darstellung einer Scheibe des erfindungsgemäßen Wärmeübertragers,

Fig. 8

eine detaillierte Darstellung einer Scheibe des erfindungsgemäßen Wärmeübertragers, und

Fig. 9

eine detaillierte Darstellung einer Scheibe nach dem Stand der Technik.

The invention will be explained in more detail on the basis of at least one embodiment with reference to the drawings. Show it:

Fig. 1

a schematic view of a heat exchanger according to the invention,

Fig. 2

an overall view of the lower disc of the disc pair,

Fig. 3

a detailed representation of the lower disc of the disc pair,

Fig. 4

an overall view of the upper disc of the disc pair,

Fig. 5

a detailed representation of the upper disc of the disc pair,

Fig. 6

a detailed representation of a disc of the heat exchanger according to the invention,

Fig. 7

a detailed representation of a disc of the heat exchanger according to the invention,

Fig. 8

a detailed illustration of a disc of the heat exchanger according to the invention, and

Fig. 9

a detailed view of a disc according to the prior art.

Preferred embodiment of the invention

The FIG. 1 shows a representation of a heat exchanger 1 according to the invention, which is designed as an exhaust gas cooler or as intercooler. Alternatively, the heat exchanger 1 can also be used elsewhere. It is advantageous if a gaseous fluid is used as a second fluid. In this case, exhaust gas, air, such as charge air, or an exhaust air-air mixture can be used as the second gaseous fluid. It is also advantageous if a liquid fluid is used as the first fluid. For this purpose, water or a water-based mixture can be used as a coolant or another coolant or a refrigerant. Furthermore, the first fluid may, for example, be oils, for example in an oil cooler or heater for preheating the oil during a cold start.

Such a heat exchanger 1 can be used advantageously as an exhaust gas heat exchanger in a motor vehicle. In the context of a so-called exhaust gas recirculation system (EGR system), exhaust gas emitted by the internal combustion engine of the motor vehicle can be cooled at least partially by a liquid coolant of a coolant circuit in the heat exchanger and returned to the intake tract of the internal combustion engine. Such a heat exchanger 1 can also be used advantageously as a charge air cooler in a motor vehicle. The charge air is cooled by coolant.

The heat exchanger 1 consists of a stack 2 of elongated disk pairs 32, wherein in each case two superimposed disks 18, 18 'along their longitudinal extent are soldered together at their edge in the longitudinal direction.

In this case, the longitudinal direction or the longitudinal side defines the direction or side between two openings as inlet 5 and outlet 6 for a second fluid, which are formed on the narrow sides 21, also called end faces. Nevertheless, the extension in the longitudinal direction may be longer, equal or shorter than the extension of the narrow side.

If the disk pairs 32, which are formed from the discs 18, 18 'stacked on top of each other, then a second fluid channel 30 is formed between the respective disc pairs 32. In this case, the second fluid channel 30 between an upper disc 18' of a lower disc pair 32 and lower disc 18 of an upper disc pair 32 formed. In this case, a first fluid channel 4 is formed between the two disks 18, 18 'of a disk pair 32. The second fluid channel 30 serves to flow through the gaseous second fluid, wherein the first fluid channel 4 serves for the flow through of the first liquid fluid.

On the narrow side 21 of the disc assembly of the two discs 18, 18 'designed to be open, whereby an inlet 5 and an outlet 6 is formed for the second fluid of the second fluid channel. In this case, the two disks are connected to the narrow sides such that the first fluid channel between the two disks 18, 18 'is completed by a soldering.

The disc pair of discs 18, 18 'has an approximately U-shaped contour with a rectangular-like outer shape, wherein the discs 18, 18' at two longitudinal edges and / or on two longitudinal sides are soldered together, the discs in the soldered state in a central region spaced from each other are formed.

In the interior of each disk pair 32 of the disks 18, 18 'may be integrally formed on the floor or the base of the lower disk 18 or surface-mounted coolant guide assembly 3. Alternatively, you can to be dispensed with. This coolant guide arrangement 3 can be embossed as an embossing or impressions in the base 60 of the disc 18 and / or in the base 61 of the disc 18 ', so that the fluid flowing through the fluid channel 4 formed in the interior of the disc pair 18, 18' Guidance and possibly a channeling learns. For this purpose, for example, web-shaped indentations are provided, which protrude into the second fluid channel 4 between the two disks 18, 18 '. Alternatively, the coolant guide arrangement 3 can also be arranged as a separate component between the disks 18, 18 ', which has the indentations or structures. The definition of the base 60, 61 of the disc 18 or 18 'is the essentially flat or flat area between any raised edges of a disc 18, 18'.

The second fluid channel 30 is arranged between an upper disk 18 'of one disk pair 32 and a disk 18 of another adjacent disk pair 32 adjacent thereto. For example, exhaust gas or charge air flows through this fluid channel 30 as a second fluid. The first fluid channel 4 is arranged between the two disks 18, 18 'of a disk pair 32. For example, a liquid coolant flows through this fluid channel 4.

The supply of the second fluid to the second fluid channels 30, that is, for example, exhaust gas, via the inlet 5 of the disk stack 2, which is formed by an open end of the narrow side portions 21 of the disk pairs 32 of the discs 18, 18 '. The second fluid flows through the second fluid channel 30 and leaves the disk stack 2 of the disk pairs 32 with the disks 18, 18 'via the outlet 6, which is formed opposite to the inlet 5.

The coolant channel arrangement 3 has a plurality of coolant-carrying webs 7 extending parallel to one another in the longitudinal direction of the disks 18 and which form individual sub-channels whose open ends are guided running near the inlet 5 and the outlet 6 of the second fluid in a direction perpendicular to the inlet 5 and outlet 6, respectively. These webs lead the subchannels arranged between them to the inlet or outlet of the first fluid, which are provided as openings 9, 10 in the side walls or edges 8 of the disc 18.

Each disc 18 has in its longitudinal extent on both sides of a highly curved edge 8 in the form of a fold, which extends perpendicularly in the direction of the overlying, identically formed adjacent disc 18.

The disc 18 'also has a mutually elevated respective edge 40, which is bent up in the manner of a fold, which is bent laterally outwardly back down. As a result, the edge 40 is quasi double-layered, wherein between the two layers a distance is provided. The disc 18 'is located on the disc 18 and the edges 40 are located between the edges 8. Advantageously, the outer walls of the edges 40 and 8 touch.

Depending on the required cooling capacity, a plurality of such connected pairs of discs 32 with the discs 18, 18 'as a stack of discs 2 are stacked.

In the longitudinal direction of the pairs of discs 32 in the end region of the respective merged ends of the discs 18, 18 'in the edge 8 of the disc 18 each have an opening 9 or 10 incorporated. These openings 9, 10 serve for the exit or entry of the first fluid, such as the coolant. The openings of the respective disk pairs are arranged one above the other in the disk stack 2. The superimposed openings 9 and 10 of a plurality of pairs of disks 32 of the discs 18, 18 'are each of a coolant collection channel 11, 12 completely covered and fluidly connected. In this case, the respective coolant collection channel 11, 12 have a recess, not shown, which covers the openings 9 and 10 sealingly. The coolant collection channel 11, 12 is advantageously designed as a deep-drawn part or pipe segment and is pushed over the openings 9 or 10 of the discs 18.

On the narrow side 21 of the disk stack 2 is taken in each case by a frame 13, 14. On the narrow sides 21 of the disk stack 2, the discs 18 are further formed so that without or optionally together with the frame 13, 14, a continuous circumferential contour is formed, via which in each case a diffuser, a flange or an adapter can be plugged and soldered leak-free.

The heat exchanger 1 terminates at the top with a rimless or bordered cover 19 from. This cover 19 may be on the edge 8 or between the edges of the uppermost disc 18 and both discs 18, 18 'on or lie between. By means of the cover 19, the uppermost fluid channel 30, in particular as a coolant channel, closed, without additional components are necessary.

Bottom side also serves a rimless base plate for stabilizing the last lower disc 18th

The first fluid channel 4 between the two discs 18, 18 'is approximately U-shaped. In this case, the fluid channel 4 assumes a first partial area, which is quasi-planar and extends substantially parallel to the bottom 60 of the disc 18. Furthermore, the fluid channel 30 occupies two lateral portions, which are aligned substantially perpendicular to the plane of the bottom 60 of the disc 18. The subareas are designed so that the fluid channel 30 is aligned higher at the edges than in the central portion of the base 60 of the disc 18th

If another disk pair 32 of the same type is applied to this disk pair 32 configured in this way, the lower disk 18 of the upper disk pair 32 closes the second fluid channel 30 between the lower and the upper disk pair 32 by contacting the edges 8 of the lower disks 18 and /. or the upper disc 18 'of the lower disc pair 32 sets.

The FIGS. 2 and 3 show a lower disc 18 of the disc pair. In this case, the disc has an approximately rectangular elongated contour. At the two opposite lateral sides of the disc 18, a rim 8 is bent up, which is approximately at right angles from the ground or base or from the plane of the bottom or base 60 high. At the ends or adjacent to the ends of the disc 8 openings 10 are introduced in an edge for the inflow or outflow of a fluid. The openings 10 are formed substantially rectangular.

In the base 60 3 webs 7 are embossed as a coolant guide assembly, which serve the formation of sub-channels and which form a flow path between the openings 10. In this case, individual of the webs 7 or the webs 7 are formed such that they have a rectangular course from one opening 10 to the other opening 10. In a first section, they are perpendicular to the main orientation 90 of the disc 18, in a central portion they are parallel to the main orientation 90 of the disc 18 and in another portion they are again perpendicular to the main orientation 90 of the disc 18th

Between the thus formed webs 7 and second webs 7 'may be arranged, which have only one orientation parallel to the main alignment 90.

The FIGS. 4 and 5 show an upper disc 18 'of the disc pair. In this case, the disc 18 'has an approximately rectangular elongated contour. At the two opposite lateral sides of the disc 18 ', an edge 8' is bent up, which is approximately at right angles from the ground or from the plane of the bottom 61 high. In this case, the edge 8 'is double-walled. At the ends or adjacent to the ends of the disc 18 'are the outer edge plate of the edge 8' openings 10 'introduced to the inflow or outflow of a fluid. The openings 10 'are formed substantially rectangular.

The base 61 is flat or it may have downwardly into the first fluid channel reaching webs or other impressions.

At the front and at the rear end portion of the disc 18 ', both the base and the edges are embossed such that when the disc 18' is placed on the disc 18, a sealed end portion is formed.

If the disk 18 'is placed on the disk 18, the first fluid channel 4 is formed between the two disks 18, 18'. The two disks 18, 18 'are sealed to one another except for the openings 10.

The FIG. 6 shows a lower disc 18 which is formed on its narrow side 100 forwardly such that a U-shaped circumferential tab 101 protrudes from the bottom 102 and the side walls 103, which after placing the second disc of the disc pair in the U-shaped portion of Bodens 102 and the side walls 103, which are also called edges, is flanged.

The FIGS. 7 and 8 each show a pair of discs 110 in which a disc 18 'is mounted on a lower disc 18, wherein the tab 101 of the lower disc 18 on both the base 102 and on the side walls 103 via the base 102' and the side walls 103 'of Disk 18 'was flanged. As a result, the broken line 111 results as the edge of the bent tab 101.

The flange is guided at the leading edge from the base over the corners in the side wall. Preferably, the entire U-shaped front edge is completely flanged. For manufacturing reasons, however, it may be necessary not to carry the bead over the entire lateral height of the side wall, as in FIG. 8 is shown. The FIG. 7 shows, however, a representation in which the beading is made over the full lateral height.

It is advantageous if a beading over the area which is soldered to the frame or diffuser is continued at least over a wall thickness of the disc in order to benefit on the one hand from the increased material thickness and on the other hand, the notch area in a non-critical To lay the area of the side wall. Advantageously, an overlap area is provided by flanging at a height of at least about three to about five disk wall thicknesses.

The FIG. 9 shows a prior art pair of discs 210 in which a disc 18 'is mounted on a lower disc 18, wherein the tab 201 of the lower disc 18 has been crimped on both the base 202 and the base 202' of the disc 18 '. This results in the broken line 211 as the edge of the bent tab 201. It can be seen that the flanged tab 201 terminates exactly in the corner between the base and side wall, resulting in significant notch effect and greater risk of failure.

Claims (6)

Heat exchanger, in particular exhaust gas cooler or intercooler, comprising one, consisting of a plurality of elongated disc pairs (32) disc stack (2), wherein each two interconnected discs (18,18 ') form a first fluid channel (4) between them and between two disc pairs a second Fluid channel (30) is formed, wherein the discs of a disc pair U-shaped with bottom and raised side walls (8,8 ') are formed and lie on each other to limit the first flow channel, wherein one of the discs (18,18') of a disc pair (32) has on its front side a tab (101) which serves for beading around the end face of the other disc (18 ', 18), characterized in that the flanging of the tab (101) made on the bottom (102) of the disc is and the flanging of the tab (101) also continues into the side walls (103) of the discs. Heat exchanger according to claim 1, characterized in that the flanging on the side walls (103) only up to a height (h) is made, which corresponds to only a part of the total height (H) of the side wall. Heat exchanger according to claim 2, characterized in that the disc has a wall thickness (d) and the height (h) at least the wall thickness of the disc (18,18 ') corresponds, preferably between 3 and 5 wall thicknesses or more Heat exchanger according to claim 1, characterized in that the beading on the side walls (103) extends to the total height (H) of the side wall. Heat exchanger according to one of claims 1 to 4, characterized in that the flanging on the bottom (102) over the entire width of the bottom is made. Heat exchanger according to one of claims 1 to 4, characterized in that the beading on the bottom (102) over the entire width of the bottom is made only partially.

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