Plate type heat exchanger for exhaust gas

Abstract

A heat exchanger, in particular exhaust-gas cooler, is described herein. The heat exchanger includes tubes of unipartite form or formed from two plates. The tubes form a first and a second fluid duct, and the respective fluid ducts are arranged adjacent to one another. The first fluid duct is designed to be open at at least one of its ends for the inflow and/or outflow of a first fluid. The second fluid ducts are closed at an end side of the tubes by way of an inward or outward step. The step has a greater extent T in the tube longitudinal direction in the corner regions of the tube than between the corner regions. Several non-limiting descriptive embodiments are disclosed herein.

Claims

1. A heat exchanger comprising: a plurality of tubes having a top side and a bottom side, wherein the tubes are formed from two plates, wherein each plate of the two plates forms either the top side or the bottom side, a plurality of first fluid ducts for a first fluid, wherein each tube bounds a first fluid duct of the plurality of first fluid ducts, a plurality of second fluid ducts, wherein a pair of adjacent tubes bounds a second fluid duct of the plurality of second fluid ducts such that the first and second fluid ducts are arranged adjacent to one another, wherein the second fluid duct is open at a front side and a back side for an inflow and outflow of a second fluid, wherein each tube has two opposite side walls perpendicular to a front edge and a back edge which are distinct from the top side and bottom side of the two plates, at least one tube end of each tube comprises a step, wherein the step comprises a transition between a region of relatively low height closer to the front edge and a region of relatively large height closer to the back edge, wherein the region of relatively low height has a shorter distance between the top side and bottom side compared to the region of relatively large height, wherein a distance between the top side and the bottom side increases in the step, wherein the distance increases towards the back edge, wherein the region of relatively low height has a rounded widening, wherein the rounded widening is positioned in a transition from a bottom wall to one side wall of the two opposite side walls and the rounded widening ends at the transition to the one side wall, wherein the rounded widening has a width dimension being perpendicular from the front edge, wherein the width dimension decreases in a direction of a middle region of the first fluid duct proceeding from the one side wall, wherein the heat exchanger does not comprise a tube sheet, wherein the width dimension of the rounded widening decreases in S-shaped fashion.

2. The heat exchanger according to claim 1, wherein each tube has a tube long side and a tube narrow side, wherein the tube long side has a greater length than the tube narrow side, wherein the step is arranged in the tube narrow side.

3. The heat exchanger according to claim 1, wherein the first fluid duct comprises a U-shaped cross section with an inward step or H-shaped cross section with an outward step.

4. The heat exchanger according to claim 1, wherein the tubes are formed from two plates, wherein the step is stamped, by way of stamped formations, into one or both of the two plates.

5. The heat exchanger according to claim 4, wherein the step is stamped, by way of stamped formations, into only one of the two plates.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Below, the invention will be discussed in more detail on the basis of at least one exemplary embodiment and with reference to the drawings. In the drawings:

(2) FIG. 1 shows a schematic view of two plate pairs stacked one on top of the other,

(3) FIG. 2 shows a schematic view of two alternative plate pairs stacked one on top of the other,

(4) FIG. 3 is an illustration of a front edge of a plate pair in section,

(5) FIG. 4 is an illustration of a front edge of a plate pair in section,

(6) FIG. 5 shows a plate pair in a plan view,

(7) FIG. 6 shows an enlarged view of a plate pair as per FIG. 5 in the region of the front edge,

(8) FIG. 7 is a sectional illustration of the plate pair as per FIG. 6,

(9) FIG. 8 is an enlarged illustration of a corner region of a plate pair,

(10) FIG. 9 is an enlarged illustration of a corner region of a plate pair,

(11) FIG. 10 is an illustration of a tube with a step which is uniform over the width,

(12) FIG. 11 is an illustration of a corner region of a tube with a step which is widened in the corner, and

(13) FIG. 12 is an illustration of a tube with an in each case widened step in the corners.

PREFERRED EMBODIMENT OF THE INVENTION

(14) FIG. 1 shows a schematic arrangement of two plate pairs 1 which are each formed from a first plate 2 and a second plate 3 and which form a first fluid duct 4 for a first fluid between the plates 2, 3, wherein a second fluid duct 5 for a second fluid is formed between respectively adjacent plate pairs 1. Here, the plates 2, 3 preferably have a substantially planar bottom 6, 8, and side walls 7, 9 which project from said bottom. The respective plates 2, 3 of a plate pair 1 are placed one on top of the other and are connected to one another in fluid-tight fashion, for example by brazing, at their edge in order to form the sealed fluid duct. Either on one of the side walls 7, 9 or on both side walls 7, 9 and/or on the bottom 6, 8, there are provided openings (not illustrated) for the admission of the first fluid into the first fluid duct 4 or for the discharge of said first fluid out of the first fluid duct 4 again. The second fluid ducts 5 are normally designed to be open at their end sides in order that flow can enter them substantially frontally.

(15) The plate pairs 1 are of U-shaped form in section, such that the first flow duct 4 extends not only in a plane of the bottom 6, 8 but also in the vertical direction along the plane of the side walls 7, 9. In this way, the stack of plate pairs 1 is delimited laterally by walls of the first fluid duct 4, which walls may be cooled outer walls in the case of a fluid duct 4 which conducts cooling fluid. In this way, the heat exchanger is not so hot on the outside, which is favorable with regard to the installation of the heat exchanger.

(16) FIG. 2 shows a schematic arrangement of two other plate pairs 21 which are each formed from a first plate 22 and a second plate 23 and which form a first fluid duct 24 for a first fluid between the plates 22, 23, wherein a second fluid duct 25 for a second fluid is formed between respectively adjacent plate pairs 21.

(17) Here, the plates 22, 23 preferably have a substantially planar bottom 26, 28, and side walls 27, 29 which project from said bottom. The respective plates 22, 23 of a plate pair 1 are placed one on top of the other and are connected to one another in fluid-tight fashion, for example by brazing, at their edge in order to form the sealed fluid duct 24.

(18) For the purposes of supply and/or discharge, openings (not illustrated) are provided on one of the side walls 27, 29 or on both side walls 27, 29 and/or on the bottom 26, 28. The second fluid ducts 25 are normally designed to be open at their end sides in order that flow can enter them substantially frontally.

(19) It may however alternatively also be provided that, for the supply and/or discharge of the second fluid in the second fluid duct 25, openings (not illustrated) are provided on one of the side walls 27, 29 or on both side walls 27, 29 and/or on the bottom 26, 28. The first fluid ducts 24 are then correspondingly designed to be open at their end sides in order that the first fluid can flow into them substantially frontally.

(20) The plate pairs 21 are of H-shaped form in section, such that the first flow duct 24 extends not only in a plane of the bottom 26, 28 but also in the vertical direction along the plane of the side walls 27, 29, specifically in both the upward and downward vertical directions proceeding from the bottom.

(21) From such plate pairs 1, 21 shown for example in FIG. 1 or 2, it is possible, by stacking these one on top of the other, to produce a bundle or a stack of plate pairs, by means of which a heat exchanger is produced. The heat exchanger, which is in particular in the form of an exhaust-gas cooler or charge-air cooler, preferably comprises a plate stack composed of multiple elongate plate pairs, wherein the plate pairs have a long side and a narrow side, wherein in each case two interconnected plates form a first, in particular elongate, fluid duct between them, and in each case one second, in particular elongate, fluid duct is formed between two plate pairs.

(22) In this case, the longitudinal direction or the long side defines the direction or side between two openings as inlet and outlet for a fluid, said openings being formed at the narrow sides, also referred to as end sides. It is nevertheless possible for the extent in the longitudinal direction to be longer, equal to or shorter than the extent of the narrow side.

(23) FIG. 5 shows such an elongate plate pair 1 in a plan view from above. It is possible to see the elongate form of the plate pair 1, and thus also the elongate form of the individual plates 2, 3, which have a long side 40 and a narrow side 41, wherein the inflow sides for the second fluid ducts 5 are normally formed on the narrow side, whereas the inlets and outlets (not illustrated) of the first fluid ducts may also be arranged laterally or above and/or below. Here, it may also be provided that the long side 40 is shorter than the narrow side 41. Flow passes through in the direction of the long side, that is to say in the longitudinal direction, wherein the inlets and outlets are arranged at the narrow sides.

(24) FIGS. 3 and 4 each show an exemplary embodiment of a front edge 42 of a plate pair 31 in the region of the narrow side 41 of the plate pair 31. In this case, the upper plate 32 is placed onto the lower plate 33, and the two plates 32, 33 form a step 34 at the front edge. Said step 34 is, as per FIG. 3, of S-shaped form, wherein the depth T is smaller than in the exemplary embodiment of FIG. 4. In the exemplary embodiment of FIG. 4, the front end 35 of the fluid duct 36 is of relatively pointed and long form, which locally increases the risk of boiling.

(25) FIG. 6 shows an enlarged view of the plate pair 1 as per FIG. 5, and FIG. 7 shows a section through the plate pair 1 as per FIG. 5. The plate pair 1 is designed so as to have a bottom 50 and side walls 51, 52 which project laterally from said bottom, wherein both the bottom 50 and the side walls 51, 52 are each of double-walled form. In this case, each of the plates 2, 3 has a substantially flat bottom 6, 8 and two side walls 7, 9 which, as a double-walled structure, form the plate pair 1.

(26) At the front edge 53, that is to say at the front edge of the narrow side, the plate pair 1 is formed with a step 54 as a transition from one plate 2 to the other plate 3, wherein the transition forms an edge region 55 of relatively low height h and a further region 56 of relatively large height H, wherein the region 56 adjoins the region 55.

(27) Here, the edge region 55 of relatively low height is formed with a rounded widening 58 in the corner regions 57 between the front edge 53 and the side walls 51, 52.

(28) Here, the step 54 is advantageously stamped, by way of stamped formations, into one and/or into the other of the two plates 2, 3. FIGS. 3 and 4 show that the step 54 is stamped, by way of stamped formations, into only one of the two plates, for example the upper plate, wherein the other plate, for example the lower plate, is of substantially planar form. It is however alternatively also possible for the step to be formed into the other plate, for example the lower plate, wherein then, the other plate, for example the upper plate, is planar. It is also alternatively possible for the stamped formations to be formed into each of the two plates 2, 3.

(29) FIG. 8 shows the corner region in FIG. 6 in an enlarged illustration. It can be seen that the edge region 55 has, in the transition from the bottom to the side walls, a rounded widening 58 of the edge region 55 of relatively low height. Said widening 58 is formed in the bottom such that the dimension s, measured along the long side L, of the edge region 55 of relatively low height decreases in the direction of the middle 59 of the fluid duct proceeding from the side wall. Here, it can also be seen that the dimensions of the rounded widening 58 decreases in arcuate or S-shaped fashion.

(30) In this case, the widening 58 ends at the corner at the transition to the side walls.

(31) FIG. 9 shows that the rounded widening 58 of the bottom also extends into at least one side wall 51 and preferably also into both side walls 51. The widening in the side wall 51 is in this case denoted by 60.

(32) Here, the rounded widening 60 is formed in a side wall 51 such that the dimension of the edge region 51 of relatively low height in the longitudinal direction L of the fluid duct decreases in the direction of the middle of the height of the side wall 51 proceeding from the bottom. Here, the dimension of the rounded widening 60 likewise advantageously decreases in arcuate or S-shaped form.

(33) FIGS. 10 and 12 each show tubes with their end regions, wherein the tube 100 of FIG. 10 exhibits a step 101 which is uniform over the width of the tube 100. FIG. 12 shows a tube 110 which has a step 111, wherein the step 111 is deeper, that is to say extends further inward in the longitudinal direction of the tube 110, in the corners 112 than between the corners 112. The step 113 in the corner thus forms a type of arc in order to realize a transition from the depth of the step in the corner to the depth of the step in the region between the corners 112.