Flat tube for an exhaust gas cooler

Abstract

A flat tube for an exhaust gas cooler including two flat wide sides and two rounded narrow sides. The flat tube further including a plurality of moulded turbulence projections arranged on the two wide sides in two flow rows and projecting from a respective one of the two wide sides toward the other of the two wide sides. The plurality of turbulence projections are respectively structured in an elongated manner and arranged at an angle relative to a longitudinal direction. The flat tube also including a plurality of moulded support projections projecting from a respective one of the two wide sides away from the other of the two wide sides. The plurality of support projections are arranged between the two flow rows. The two narrow sides each have an elongated flat region that merges into the two wide sides via a plurality of rounded corner regions.

Claims

1. A flat tube for an exhaust gas cooler, comprising: a central longitudinal axis extending in a longitudinal direction; two flat wide sides extending parallel to one another along a longitudinal direction and disposed opposite one another; two rounded narrow sides that are narrower than the two wide sides, the two narrow sides extending parallel to one another along the longitudinal direction and disposed opposite one another; the two wide sides including a plurality of moulded turbulence projections projecting from a respective one of the two wide sides toward the other of the two wide sides, the plurality of turbulence projections respectively structured in an elongated manner and arranged at an angle relative to the longitudinal direction; the plurality of turbulence projections arranged on the two wide sides in two flow rows extending parallel to the longitudinal direction; a plurality of moulded support projections projecting from a respective one of the two wide sides away from the other of the two wide sides, the plurality of support projections arranged between the two flow rows; wherein each narrow side of the two narrow sides has an elongated flat region extending in the longitudinal direction along essentially the entire length of the respective narrow side and arranged perpendicularly to the two wide sides in a respective middle of the narrow side; and wherein the flat region merges into the two wide sides via a plurality of rounded corner regions of the narrow side.

2. The flat tube according to claim 1, wherein at least one of: a length of the flat region corresponds to a length of the narrow side; and a width of the flat region perpendicular to the longitudinal direction and the two wide sides is 0.5 mm to 0.9 mm.

3. The flat tube according to claim 1, wherein the two wide sides include a plurality of nub-shaped mouldings projecting from a respective one of the two wide sides toward the other of the two wide sides, the plurality of nub-shaped mouldings arranged between the two flow rows and, in the longitudinal direction, are arranged in a row one behind the other.

4. The flat tube according to claim 3, wherein: the row of the plurality of nub-shaped mouldings on one of the two wide sides and the row of the plurality of nub-shaped mouldings on the other of the two wide sides are arranged opposite one another; and at least some of the plurality of nub-shaped mouldings in the row on the one of the two wide sides are arranged in an alternating manner with at least some of the plurality of nub-shaped mouldings in the row on the other of the two wide sides in the longitudinal direction.

5. The flat tube according to claim 3, wherein at least one of: a substantially semi-spherical base of at least some of the plurality of nub-shaped mouldings has a diameter of 0.5 mm to 2 mm; and at least some of the plurality of nub-shaped mouldings have a depth of 0.5 mm to 1.8 mm.

6. The flat tube according to claim 3, wherein: the plurality of nub-shaped mouldings and the plurality of support projections are both arranged in the row; and the row of the plurality of nub-shaped mouldings and the plurality of support projections are arranged, relative to a direction perpendicular to the longitudinal direction, in a middle of a respective wide side of the two wide sides.

7. The flat tube according to claim 3, wherein at least one of: a substantially semi-spherical base of at least some of the plurality of nub-shaped mouldings has a diameter of 0.8 mm to 1.5 mm; and at least some of the plurality of nub-shaped mouldings have a depth of 1.0 mm to 1.5 mm.

8. The flat tube according to claim 1, wherein at least one of: a base of the plurality of turbulence projections has a length of 3.5 mm to 8 mm; and the plurality of turbulence projections have a depth of 0.5 mm to 1.8 mm.

9. The flat tube according to claim 1, wherein the angle of the plurality of turbulence projections relative to the longitudinal direction is 18° to 31°.

10. The flat tube according to claim 9, wherein the plurality of turbulence projections, on a respective wide side in the longitudinal direction, are arranged in an x-shaped arrangement and in at least one o-shaped arrangement.

11. The flat tube according to claim 10, wherein: the x-shaped arrangement and the at least one o-shaped arrangement on the respective wide side are arranged in an alternating manner with one another in the longitudinal direction; and the x-shaped arrangement of one of the two wide sides is disposed opposite the at least one o-shaped arrangement of the other of the two wide sides.

12. The flat tube according to claim 11, wherein the plurality of support projections are arranged within the at least one o-shaped arrangement of the respective wide side.

13. The flat tube according to claim 1, wherein the flat tube is configured flow-symmetrically, and wherein one of the two wide sides corresponds to the other of the two wide sides that is mirrored perpendicularly to the longitudinal direction.

14. The flat tube according to claim 1, wherein the angle of the plurality of turbulence projections relative to the longitudinal direction is 22° to 25°.

15. The flat tube according to claim 1, wherein the two narrow sides each have a cross-sectional profile lying perpendicular to the longitudinal direction that is defined by the flat region and the plurality of rounded corner regions.

16. The flat tube according to claim 1, wherein the flat region merges directly into the two wide sides via the plurality of rounded corner regions.

17. A flat tube for an exhaust gas cooler, comprising: two planar wide sides respectively coupled to two rounded narrow sides defining a flow passage having a central longitudinal axis extending in a longitudinal direction, the two wide sides extending parallel to one another along the longitudinal direction and disposed opposite one another, the two narrow sides extending parallel to one another along the longitudinal direction and disposed opposite one another; a plurality of moulded turbulence projections arranged on each of the two wide sides in two flow rows extending parallel to the longitudinal direction, the plurality of turbulence projections projecting into the flow passage and respectively structured in an elongated manner extending at an angle relative to the longitudinal direction; and a plurality of moulded support projections arranged on each of the two wide sides between the two flow rows and projecting away from the flow passage; wherein each of the two narrow sides has two rounded corner regions and an elongated planar region disposed between the two rounded corner regions, the planar region extending in the longitudinal direction along essentially the entire length of the respective narrow side and lying perpendicular to the two wide sides; wherein the two narrow sides are narrower than the two wide sides; and wherein the planar region merges directly into the two wide sides via the two rounded corner regions.

18. The flat tube according to claim 17, further comprising a plurality of nub-shaped mouldings arranged in a row with the plurality of support projections between the two flow rows on each of the two wide sides and projecting into the flow passage.

19. The flat tube according to claim 17, wherein: a subset of the plurality of turbulence projections on each of the two wide sides are arranged to define a plurality of x-shaped arrangements, and another subset of the plurality of turbulence projections on each of the two wide sides are arranged to define a plurality of o-shaped arrangements; the plurality of x-shaped arrangements and the plurality of o-shaped arrangements are disposed along each of the two wide sides in an alternating relationship with one another in the longitudinal direction; and the plurality of support projections are arranged within the plurality of o-shaped arrangements.

20. The flat tube according to claim 17, wherein the two narrow sides each have a cross-sectional profile lying perpendicular to the longitudinal direction that is defined by the planar region and the two rounded corner regions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) It shows, in each case schematically

(2) FIG. 1 shows a perspective view of a flat tube according to the invention;

(3) FIG. 2 shows a frontal view of the flat tube shown in FIG. 1;

(4) FIG. 3 shows a plan view of the flat tube shown in FIG. 1;

(5) FIG. 4 shows a lateral view of the flat tube shown in FIG. 1;

(6) FIG. 5 shows a perspective view of a flat tube according to the invention with multiple nub-like mouldings;

(7) FIG. 6 shows a frontal view of the flat tube shown in FIG. 6;

(8) FIG. 7 shows a plan view of the flat tube shown in FIG. 6;

(9) FIG. 8 shows a lateral view of the flat tube shown in FIG. 6;

(10) FIG. 9 shows a detail plan view of the flat tube shown in FIG. 6 with geometrical dimensions;

(11) FIG. 10 shows a detail frontal view of the flat tube according to the invention with geometrical dimensions;

(12) FIGS. 11 and 12 show flow patterns in a flat tube that is symmetrical to the longitudinal direction with opposing flows;

(13) FIG. 13 shows a flow pattern in a flat tube with alternating nub-like mouldings;

(14) FIGS. 14 to 16 show lateral views of a flow-symmetrical flat tube;

(15) FIG. 17 shows a comparative view of wide sides of a flow-symmetrical flat tube.

DETAILED DESCRIPTION

(16) FIG. 1 shows a view of a flat tube 1 according to the invention. The flat tube 1 is suitable for an exhaust gas cooler, in particular for a motor vehicle. The flat tube 1 may comprise a central longitudinal axis extending in a longitudinal direction 5, two flat and/or planar wide sides 2a and 2b arranged opposite one another, as well as two rounded narrow sides 3a and 3b arranged opposite one another. The two rounded narrow sides 3a, 3b may be narrower than the two wide sides 2a, 2b. In the wide sides 2a and 2b, multiple turbulence projections 4 projecting into the flat tube 1 are moulded, which are arranged on the wide sides 2a and 2b in two flow rows 6a and 6b that are parallel to the longitudinal direction 5 of the flat tube 1. In an exhaust gas cooler—not shown here, the flat tubes 1 are stacked spaced on top of one another, for the purpose of which multiple support projections 7 projecting out of the flat tube 1 are moulded between the two flow rows 6a and 6b. In the wide sides 2a and 2b, the turbulence projections 4 are arranged into x-shaped arrangements 8 and into 0-shaped arrangements 9, which are formed symmetrically to the longitudinal direction 5. By way of this, a symmetrical flow pattern in the flat tube 7 can be achieved in particular. Here, the support projections 7 are arranged in the o-shaped arrangements of the respective wide side 2a and 2b. Between the two flow rows 6a and 6b, a middle flow passage 10 and on the narrow sides 2a and 2b two lateral narrow side passages 11 are formed, as shown in FIG. 2.

(17) The narrow sides 3a and 3b each have an elongated flat region 12 (e.g., a planar region), which via rounded corner regions 13 of the respective narrow sides 3a and 3b merges into the wide sides 2a and 2b. Here, the flat region 12 extends in the longitudinal direction 5 of the flat tube 1 and is arranged perpendicularly to the two wide sides 2a and 2b in the middle of the respective narrow sides 3a and 3b. A length of the respective flat region 12 corresponds to a length of the narrow sides 3a or 3b respectively to a length of the flat tube 1. The respective narrow sides 3a and 3b are consequently formed of the corner regions 13 and the flat region 12 connecting the corner regions 13. The flat tube 1 is produced from a stamped flat tube strip 14, wherein the flat tube strip 14 comprises the wide sides 2a and 2b, the narrow side 3a and on both sides a corner region 13 each and in each case a flat region part 12a or 12b of the narrow side 3b, as shown in FIG. 2.

(18) During the manufacture, the flat tube strip 14 is folded together on the narrow side 3a along the flat region 12 and the two flat region parts 12a and 12b of the narrow side 3b are fixed to one another in a firmly bonded manner—for example welded. A connecting seam 15 then connects the two flat region parts 12a and 12b in a firmly bonded manner to form the flat region 12, so that the narrow side 3b is formed of the flat region 12 and the corner regions 13 lying against the flat region 12 on both sides. The flat region parts 12a and 12b of the narrow side 3b substantially simplify the production of the flat tube 1. Furthermore, the flat tube 1 according to the invention has a high pressure stability even with large manufacturing tolerances, since in contrast with a conventional rounded flat tube the stress, during an internal pressure loading of the narrow side 3b by the exhaust gas, does not lie on the connecting seam 15 of the narrow side 3b.

(19) FIG. 5 shows a perspective view of the flat tube 1 according to the invention, which comprises multiple nub-like mouldings 16 (e.g., nub-shaped mouldings). FIG. 6 to FIG. 8 show lateral views of the flat tube 1 shown in FIG. 5. The nub-like mouldings 16 project into the flat tube 1—which is otherwise moulded as in FIG. 1 to FIG. 4—and are arranged between the two flow rows 6a and 6b of the turbulence projections 4. Furthermore, the nub-like mouldings 16 are arranged in the longitudinal direction 5 of the flat tube 1 in a row 17 with the support projections 17 one behind the other. The nub-like mouldings 16 project into the flow passage 10 and a flow cross section of the flow passage 10 is reduced. In particular, the exhaust gas cannot flow through the flow passage 10 in an unobstructed manner and is better swirled up and better cooled because of this. The cooling output in the flat tube then corresponds to the cooling output in a rectangular flat tube even without lateral projections. The advantages of the rounded flat tube 1—such as for example a lower coolant requirement for preventing boiling in the exhaust gas cooler—are advantageously retained.

(20) FIG. 9 and FIG. 10 show views of the flat tube 1—as is depicted in FIGS. 5 to 8—with geometrical dimensions. The flat tube 1 has a width B.sub.FR between 13 mm and 18 mm, preferably between 15 mm and 17 mm. A height H.sub.FR of the flat tube 1 is between 3.8 mm and 5 mm, preferably between 4 mm and 4.6 mm. Furthermore, the flat tube 1 can have a wall thickness between 0.34 mm and 0.5 mm, preferably between 0.37 mm and 0.42 mm. A width B.sub.FB of the respective flat region 12, which extends perpendicularly to the two wide sides 2a and 2b, is between 0.5 mm and 0.9 mm, preferably between 0.65 mm and 0.75 mm. A base 18 of the turbulence projections 4 has a length L.sub.TV between 3.5 mm and 8 mm, preferably between 5 mm and 6 mm. A depth Try of the turbulence projections 4 is between 0.5 mm and 1.8 mm, preferably between 1.4 mm and 1.6 mm. An angle W.sub.TV of the turbulence projections 4 to the longitudinal direction 5 of the flat tube 1 is between 18° and 31°, preferably between 22° and 25°. A substantially semi-spherical base 19 of the nub-like mouldings 16 has a diameter D.sub.NA between 0.5 mm and 2 mm, preferably between 0.8 mm and 1.5 mm. Furthermore, the nub-like mouldings 16 have a depth T.sub.NA between 0.5 mm and 1.8 mm, preferably between 1.0 mm and 1.5 mm.

(21) FIG. 11 and FIG. 12 show flow patterns in the flat tube 1 with the multiple nub-like mouldings 16—as depicted in FIG. 5 to FIG. 10—with opposing flows, which are indicated by interrupted arrows. Here, the turbulence projections 4 are arranged in the respective wide side 2a or 2b in the longitudinal direction 5 into the x-shaped arrangements 8 and into the o-shaped arrangements 9, which are formed symmetrically to the longitudinal direction 5 of the flat tube 1. The x-shaped arrangements 8 conduct the exhaust gas in an inflow direction first half from the narrow sides 3a and 3b into the middle of the flat tube 1 and in an inflow direction second half from the middle of the flat tube 1 to the narrow sides 3a and 3b. The o-shaped arrangements 9 conducts the exhaust gas in an inflow direction first half from the middle of the flat tube 1 to the narrow sides 2a and 2b and in an inflow direction second half from the narrow sides 3a and 3b into the middle of the flat tube 1. Furthermore, the nub-like mouldings 16 are specifically subjected to the onflow of exhaust gas so that the exhaust gas in the flat tube 1 is mixed through better and because of this also cooled.

(22) FIG. 13 shows a flow pattern in the flat tube 1—as is depicted in FIG. 5 to FIG. 12—through the flow passage 10. The row 17 of the nub-like mouldings 16 in the one wide side 2a and the row 17 of the nub-like mouldings 16 in the other wide side 2b are located opposite one another and the nub-like mouldings 16 of the two rows 17 alternate in the flow passage 10. In this way, the exhaust gas is conducted from the nub-like mouldings 16 in the one wide side 2a or 2b specifically to the nub-like mouldings 16 in the other wide side 2b or 2a, as shown by arrows. Here, an excessive local cross-sectional reduction of the flow passage 10 and an excessive pressure loss in the flat tube 1 are avoided. Advantageously, the cooling output is retained.

(23) FIG. 14 to FIG. 16 show lateral views of the flow-symmetrical flat tube 1, as is also depicted in FIG. 5 to FIG. 13. In FIG. 17, a comparative view of the wide sides 2a and 2b is shown. As shown in FIG. 17, the one wide side 2a or 2b corresponds to the other wide side 2b or 2a that is mirrored perpendicularly (i.e., non-reverse mirrored, flip mirrored) relative to the longitudinal direction 5. As already shown in FIG. 13, the nub-like mouldings in the wide sides 2a and 2b also alternate in the longitudinal direction 5. Furthermore, the x-shaped arrangements 8 and the o-shaped arrangements 9 also alternate on the respective wide sides 2a and 2b in the longitudinal direction 5 and are located opposite one another on the wide sides 2a and 2b. In this way, an excessive cross-sectional reduction of the flat tube 1 between the wide sides 2a and 2b and an excessive pressure loss in the flat tube 1 can be advantageously avoided. Because of the flow-symmetrical flat tube 1, the exhaust gas cooler can be produced in a simplified manner, since no additional orientation of the flat tube 1 to the exhaust gas flow in the exhaust gas cooler is necessary.

(24) Altogether, producing the flat tube 1 according to the invention can be substantially simplified. Furthermore, the flat tube 1 according to the invention has a high pressure stability even with large manufacturing tolerances. Because of the nub-like mouldings 16 in the flat tube 1, the flow passage 10 between the two flow rows 6a and 6b of the turbulence projections 4 can be reduced, furthermore, and because of this the cooling output of the exhaust gas cooler increased.