EP0981035A2 - Heat exchanger for exhaust gases - Google Patents

Abstract

The heat exchanger plates (6) have extending areas (7) forming the distribution and collection spaces for cooling water. The flow channels (14) for exhaust gas extend in a straight path through the heat exchanger, issuing at opposing ends in the pipe bases (13). At least one of the two types of flow channels (9,14) has a surface structure, whereby the full-surface contact between the flow channels is excluded. The flow channels for cooling water have a somewhat corrugated surface structure.

Description

The invention relates to an exhaust gas heat exchanger with pairs of bowl-shaped, Heat exchanger plates, each pair of bowl-shaped heat exchanger plates forms a flow channel for the one agent, by the circumferential edge flange are mirrored assembled and connected so that the edge flange the one heat exchanger plate on one side and the edge flange of the another heat exchanger plate is directed to the opposite side, as well with openings in the heat exchanger plates that are on a common line lie to form the collecting and distribution channel for the one agent and with further arranged between the flow channels mentioned Flow channels for the other medium.

This exhaust gas heat exchanger is known from EP 677 715. The well-known exhaust gas heat exchanger can be regarded as disadvantageous because Corrosion caused breakthroughs on the exhaust side to mix the exhaust gas with the cooling water. Since the exhaust gases contain very aggressive substances, the possibility of rusting through is not far away. That's why in that mentioned document the heat exchanger plates, the corrugated fins and the connecting piece made of stainless steel, but this increases the costs. In addition comes that despite this measure there is no guarantee that not mixing occurs because even the stainless steel sheets, if not the the highest quality are attacked, at least in the vicinity of the solder connections can be. Especially since one is constantly striving to achieve the sheet thickness of the heat exchanger plates to reduce. Furthermore, cost and weight are required by the Housing increased, which surrounds the heat exchanger. Furthermore there are manufacturing difficulties in correctly positioning the two bowl-shaped heat exchanger plates to each other.

If the engine's cooling water is to be used as the coolant, this is the Exhaust gas heat exchanger in the document mentioned in a so-called rod-plate construction constructed and has an outer housing. This otherwise advantageous Construction has the disadvantage that the number of individual parts and the number and length of the solder connections are quite large, which increases the risk that soldering errors can occur.

From DE 44 03 144 C2, for example, it is also known to have no housing Plate heat exchangers (oil coolers) which are described as non-mixing can produce, so to speak, in mixed construction, in which the one kind of tube plates in Rod-plate construction and the other type of tube plates made from half-shells are. However, here is the freedom of mixing by arranging one Additional safety partition has been achieved, reducing the overall weight is relatively high. Furthermore, this heat exchanger would act as an exhaust gas heat exchanger generate too great a pressure loss on the exhaust side, which is caused in of the multitude of diversions. Especially the pressure loss on the exhaust side is particularly disadvantageous because the cooled exhaust gas with the highest possible pressure downstream turbocharger should be fed.

The disadvantage of the excessive pressure drop must also be that from DE 296 16 354 U1 known liquid-cooled exhaust gas heat exchanger can be assigned.

The object of the invention is in the specified in the preamble Exhaust gas heat exchanger to further reduce manufacturing costs and also one higher security against mixing of the exhaust gas with the cooling water guarantee, with at the same time low pressure loss on the exhaust side.

The solution according to the invention results from the patent claims.

The task is solved by the clever combination of im Heat exchanger construction may have individually known features, the inventors have recognized that their novel interaction to an inventive Exhaust gas heat exchanger leads in which the exhaust gas is cooled with liquid becomes.

According to the invention it is proposed that the exhaust gas heat exchanger in a housing less Construction is carried out that the shell-shaped heat exchanger plates formed flow channels are provided for the cooling water and that the intermediate flow channels for the exhaust gas are approximately straight Are flat tubes that open into tube sheets at opposite ends, to which the exhaust pipe is connected.

The tube sheets have a diameter that is at least partially larger than the subsequent cross-sectional dimension of the heat exchanger. The Tube sheets are preferably circular parts, which means that the manufacture and also the connection of the round exhaust pipe can be done more easily.

The exhaust pipe can be connected to the heat exchanger using screws, Brackets or tension rings are made.

At least one type of flow channel has a corrugated or similarly structured one Surface on. The corrugated surface structure ensures sufficient Way that in the event of rusting the exhaust gas to the atmosphere can escape and not easily get into the cooling water.

The pressure loss on the exhaust side is extremely low because of the associated Flow channels have no deflections and because of the tube sheets are large that this requirement can be met. Furthermore are the distributor - and the collecting room for the cooling water in overhanging areas the bowl-shaped heat exchanger plates arranged outside of the cross section of the flat tubes. This also makes a contribution to Lowered the pressure loss on the exhaust side, because this means the distributor and the collecting space are not in the flow area of the exhaust gases and don't hinder their flow.

The manufacturing costs are reduced by the fact that what the invention cooled exhaust gas heat exchangers only on the exhaust side - i.e. the flat tubes and the tube sheets - must be made of stainless steel while everyone else Parts can be made of aluminum. The water-cooled exhaust gas heat exchanger EP 677 715, on the other hand, consists entirely of stainless steel. The proposed exhaust gas heat exchanger therefore also has a lower one Weight on.

Furthermore, a contribution to reducing manufacturing costs can be seen in that the water-cooled exhaust gas heat exchanger, as stated above, in a case less Execution is provided. The external flow channels are cooling water channels so that the radiant heat of the heat exchanger is reduced is what with exhaust gas heat exchangers because of the high exhaust gas temperatures is not insignificant.

The bowl-shaped heat exchanger plates that the flow channels for the Form cooling water, have inwardly corrugated surface Support studs that are at their apex with the same support studs neighboring heat exchanger plate are soldered. This training, known per se ensures better heat transfer and higher strength of the exhaust gas heat exchanger.

Another advantageous feature of the heat exchanger plates is that protruding and angled sections at certain intervals on the edge flange are provided, with the help of two heat exchanger plates position each other, d. H. they cannot slip. It will therefore no auxiliary devices when stacking and preparing for Soldering required.

The flat pipes that carry the exhaust gas can either be drawn or with a Longitudinally welded flat tubes, as well as formed from two half-shells be soldered together on the peripheral flange. In the flat tubes punched or rolled inner inserts can be arranged with the tubes are soldered to promote heat exchange and stability to increase. However, one embodiment completely dispenses with such internal inserts, to further reduce the pressure drop. The wall has the Flat tubes have a wave-like structure. The wave peaks and valleys run in Longitudinal direction of the flat tubes.

In the case of flat tubes which are formed from two half-shells, are located on their Edge flange protruding and angled sections that interlock and the correct positioning of two half-shells to form a flat tube.

These sections are comparable to sections on the edge flange of the heat exchanger plates.

Openings are punched out in the tube sheets, which correspond to the cross-section of the flat tubes are adapted and have the passages that either to the exhaust pipe are directed towards or to the inside of the heat exchanger. With a view to reduction of pressure loss, it is cheaper to use the passages to the heat exchanger to be provided because this prevents the tube protrusion into the tube sheet is. These passages form a suitable soldering edge for the flat tubes in the tube sheets. Furthermore, the connection is made so that the pressure loss remains extremely low.

The invention will now be described with reference to the accompanying drawings described in exemplary embodiments.

Fig. 1

Gesamtansicht eines Abgaswärmetauschers

Fig. 2

Seitenansicht von Fig. 1

Fig. 3

Gesamtansicht einer anderen Ausführungsform

Fig. 4

Schnitt IV - IV in Fig. 2

Fig. 5

Ansicht auf einen Abgaswärmetauscher aus Richtung des An schlußflansches

Fig. 6

Ähnlich Fig. 4 bei einem anderen Ausführungsbeispiel

Fig. 7

Ähnlich Fig. 5

Fig. 8

Längsschnitt gemäß VIII - VIII in Fig. 6

Fig. 9

Querschnitt einer anderen Ausführungsform

Fig. 10

Ansicht des Abgaswärmetauschers nach Fig. 9 aus Richtung des Anschlußflansches

Fig. 11

Gesamtansicht einer weiteren Ausführungsform

Fig. 12

Teillängsschnitt

The figures show in detail:

Fig. 1

General view of an exhaust gas heat exchanger

Fig. 2

Side view of Fig. 1st

Fig. 3

General view of another embodiment

Fig. 4

Section IV - IV in Fig. 2

Fig. 5

View of an exhaust gas heat exchanger from the direction of the connection flange

Fig. 6

Similar to Fig. 4 in another embodiment

Fig. 7

Similar to FIG. 5

Fig. 8

Longitudinal section according to VIII - VIII in Fig. 6

Fig. 9

Cross section of another embodiment

Fig. 10

9 from the direction of the connecting flange

Fig. 11

General view of another embodiment

Fig. 12

Partial longitudinal cut

Fig. 1 shows a cooling water-cooled exhaust gas heat exchanger 1 with a Exhaust gas inlet 2 and an exhaust gas outlet arranged on the opposite side 3. Inlet 2 and outlet 3 are each provided with a connecting flange, around the exhaust pipe (not shown), for example by means of clamping rings 26 to fix. The cooling water connections 4 and 5 are on the top Heat exchanger plate 6, also at opposite ends, the connections 4 and 5 in projecting areas 7 of the heat exchanger plates 6 are provided, which are outside the area of the straight There are flat tubes 8 through which the exhaust gases (arrows 19) flow. Two completely identical shell-shaped heat exchanger plates 6 each form a flow channel 9, through which the cooling water flows (arrows 10). On the top heat exchanger plate 6 knobs 11 are indicated, which are in contact with the knobs 11 of the heat exchanger plate 6 located underneath, because in each case one of the two Identical heat exchanger plates 6 are used to form the flow channel 9 180 ° around the transverse axis or around the longitudinal axis or around the vertical axis rotated and assembled with the other heat exchanger plate 6. 4 some of these knobs 11 have been drawn.

The heat exchanger plates 6 also have a wave-shaped structure, the duch transverse lines 22 were indicated in FIG. 3. There were only a few Lines 22 are drawn. The wave structure extends over the entire area of Heat exchanger plates 6.

The heat exchanger plates 6 have protruding and angled sections 12 on its edge flange 23. After turning and assembling the heat exchanger plates 6 these sections 12 intermesh and comb thereby ensure the positioning of the plates 6.

From Fig. 2 it can be seen that the flat tubes 8 in this embodiment are formed from two halves that are joined and soldered together. Advantageous However, it is also when ordinary welded or drawn flat tubes be used. If the flat tubes 8 and the tube sheets made of stainless steel exist, but the heat exchanger plates are made of aluminum, must be a two-fold soldering process in the manufacture of such heat exchangers occur. First, the flat tubes 8 with the inner inserts 24 and the tube sheets 13 assembled and in the soldering furnace a correspondingly high Exposed to temperature at which these parts form a solder joint. The Outer surfaces of the flat tubes 8 are made without solder coating, so that they make no connection, for example with an auxiliary device used for soldering. Then this prefabricated unit is passed through the heat exchanger plates 6 made of aluminum and in a second soldering process accordingly lower temperature combined into a compact unit. Here connect both the pairs of heat exchanger plates 6 and these the flat tubes 8 because the heat exchanger plates 6 with solder on both sides are coated.

From Fig. 2 and from Fig. 4, which shows the section IV - IV in Fig. 2 go Pot-like depressions 15 on each heat exchanger plate 6 and also the Openings 16 in each recess 15. The openings 16 have an edge 17. An these edges 17, the heat exchanger plates 6 are also connected to one another, so that the collection and distribution channels 20 and 21 are formed.

Sleeves that serve as individual parts between the heat exchanger plates also serve the same purpose 6 can be inserted and connected.

With the reference number 13 in Fig. 1; 2 and 4 the tube sheets have been designated, which are circular and essentially over the periphery of the heat exchanger 1 protrude when the protruding areas 7 of the heat exchanger plates 6 is disregarded.

5 shows the view from the direction of the clamping ring 26 of the embodiment 1, 2 and 4. One can see the collecting space 21 and the on the edge flange 23 connected heat exchanger plates 6. In addition, the a tube sheet 13 and the flow channels 14 ending there from this illustration forth.

In the exemplary embodiment according to FIG. 6, inserts 24 in were used entirely the flat tubes 8 dispensed with. Instead, the walls became two Half shells 8/1 and 8/2 existing flat tubes 8 with a clear wave-like Structure 22 formed. The wave crests and the wave valleys run here however, in contrast to the undulating structure 22 of the before and on End of the embodiment described (on the heat exchanger plates 6), in Longitudinal direction of the flat tubes 8 or the flow channels 14. In this embodiment are the heat exchanger plates 6 preferably with a smooth Surface formed, apart from the embossed knobs 11. This Embodiment is particularly suitable for exhaust gas heat exchangers because of the danger the blockage of the flat tubes 8 by deposits much less is.

FIG. 7 shows the view belonging to the exemplary embodiment in FIG. 6 from the direction of the clamping ring 26. The longitudinal wave-like structure 22 of the Flow channels 14 can also be seen from this illustration.

The longitudinal section also belonging to this embodiment in FIG. 8 shows that the undulating structure 22 ends in front of the tube sheet 13. The passages 25 on the tube sheet 13 were carried out to the heat exchanger and the Flat tubes 8 have been plugged with their ends onto these passages 25

It should also be noted that Fig. 8 is a different connection to the exhaust pipe, not shown.

FIG. 9 can be interpreted as a cross section in FIG. 3. It makes a difference 4 in that here welded or drawn flat tubes 8th have been used. Furthermore, the attachment was made using a connecting flange 27 selected, as is also shown in Fig. 3.

10 differs from the exemplary embodiment in FIG. 9 in that that in Fig. 10 the passages 25 on the tube sheet 13 to the exhaust pipe are directed, while in Fig. 9 show the passages 25 to the heat exchanger.

Fig. 11 shows an embodiment in which the overhanging Areas 7 in which the collecting and distribution spaces 20, 21 are arranged, are on opposite sides of the heat exchanger. Therefore have to two different types of heat exchanger plates 6 are used here.

Angled arms made of sheet steel are provided as brackets 28 the tube sheets 13 have been soldered.

Fig. 12 shows a partial longitudinal section, similar to Fig. 8, but in which the heat exchanger plates 6 have a corrugated surface structure 22, thereby to achieve a higher security against mixing exhaust gas and cooling water. In contrast to Fig. 8 here are also the flat tubes 8 in the Passages 25 of the tube sheet 13 have been used.

Claims (9)

Exhaust gas heat exchanger (1) with pairs of bowl-shaped heat exchanger plates (6), each pair of bowl-shaped heat exchanger plates (6) forms a flow channel (9) for the one means by being joined and connected in mirror image on the peripheral edge flange in such a way that the edge flange of the one heat exchanger plate ( 6) to one side and the edge flange of the other heat exchanger plate (6) is directed to the opposite side, and with openings in the heat exchanger plates, which lie on a common line to form the collecting and the distribution channel for the one agent and with between the above-mentioned flow channels arranged further flow channels for the other agent,
characterized in that the liquid-cooled exhaust gas heat exchanger (1) is designed without a housing, that the heat exchanger plates (6) have projecting areas (7) and in these areas (7) form the distributor and the collecting space for the cooling water, that the flow channels (14) for the exhaust gas extend approximately in a straight path through the heat exchanger and open into tube plates (13) at opposite ends, and that at least one of the two types of flow channels (9; 14) has a surface structure (22) such that full-area contact between the flow channels (9 and 14) is excluded. Exhaust gas heat exchanger according to claim 1, characterized in that the flow channels (9) for the cooling water have an approximately corrugated surface structure. Exhaust gas heat exchanger according to claims 1 and 2, characterized in that that the flat tubes (8) forming the flow channels (14) are preferably for the exhaust gas consist of stainless steel and have wave-like inner inserts (24) and are either drawn or welded flat tubes (8) or two Half shells (8/1; 8/2) are made and connected to each other at the edge flange. Exhaust gas heat exchanger according to claim 1, characterized in that the Flat tubes (8) or flow channels (14) have undulating walls, the wave crests and troughs in the direction of the longitudinal axis of the flat tubes (8) are arranged. Exhaust gas heat exchanger according to one of the preceding claims, characterized characterized in that at the edge flange of the flat tubes (8) forming Half shells (8/1; 8/2) and / or on the edge flange (23) of the shell-shaped heat exchanger plates (6) projecting and angled sections (12) are arranged are which interlock when the heat exchanger plates (6) are joined together and the correct positioning of two half shells to each other. Exhaust gas heat exchanger according to one of the preceding claims, characterized characterized in that the tube sheets (13) consist of stainless steel and preferably are circular parts, with a diameter such that the tube sheets (13) at least partially over the subsequent cross-sectional dimension of the Protrude heat exchanger. Exhaust gas heat exchanger according to claim 1, characterized in that the projecting areas (7) are arranged outside the cross section of the flat tubes (8). Exhaust gas heat exchanger according to one of the preceding claims, characterized characterized in that the heat exchanger plates (6) are preferably made of aluminum exist and have support knobs (11), which after assembly touch and are connected at the points of contact. Exhaust gas heat exchanger according to one of the preceding claims, characterized characterized in that the center line of the in the direction of the flat tubes (8) Exhaust gas heat exchanger (1) and the exhaust pipe at least in the vicinity of the inlet and outlet Exit lie on an approximately straight or slightly curved line.

Images