Exhaust gas cooler and exhaust gas recirculation system with an exhaust gas cooler

Abstract

An exhaust gas cooler comprises at least one exhaust gas pipe for exhaust gas being cooled and is characterized in that at least one gap is provided between the wall of the exhaust gas pipe and laterally adjacent components at the inlet of at least one exhaust gas pipe in the direction of extension of at least one wall perpendicular to the flow direction of the exhaust gas.

Claims

1. An exhaust gas cooler comprising: at least one exhaust gas pipe configured to receive an exhaust gas flowing through an interior of the at least one exhaust gas pipe, wherein the at least one exhaust gas pipe is a flat tube having a wall with a substantially rectangular cross-section with two opposing short sides and two opposing long sides, wherein an inlet end of the at least one exhaust gas pipe is surrounded by each of a housing and a flange, wherein a first gap is provided between a first one of the short sides of the wall of the at least one exhaust gas pipe and each of the housing and the flange at the inlet end of the at least one exhaust gas pipe, wherein the at least one exhaust gas pipe includes a fastening point at which the first one of the short sides of the wall of the at least one exhaust gas pipe is coupled to the housing at a position downstream of the inlet end of the at least one exhaust gas pipe with respect to a flow direction of the exhaust gas through the interior of the at least one exhaust gas pipe.

2. The exhaust gas cooler as claimed in claim 1, wherein the first gap extends between 5 mm and 2 cm in the flow direction of the exhaust gas between the inlet end of the at least one exhaust gas pipe and the fastening point.

3. The exhaust gas cooler as claimed in claim 1, wherein the first gap extends between 1 mm and 5 mm in a direction perpendicular to the flow direction of the exhaust gas.

4. The exhaust gas cooler as claimed in claim 1, wherein the at least one exhaust gas pipe has fins on an inside thereof.

5. The exhaust gas cooler as claimed in claim 1, wherein the wall has a thickness of 0.3 to 0.5 mm.

6. The exhaust gas cooler as claimed in claim 1, wherein the housing has at least one wall with a thickness of 1 to 1.5 mm and the flange has a thickness of 5 to 8 mm.

7. The exhaust gas cooler as claimed in claim 1, wherein the exhaust gas cooler is an exhaust gas recirculation cooler.

8. An exhaust gas recirculation system with at least one exhaust gas cooler as claimed in claim 7.

9. The exhaust gas cooler as claimed in claim 1, wherein the housing circumscribes the at least one exhaust gas pipe at the inlet end thereof.

10. The exhaust gas cooler as claimed in claim 9, wherein the flange circumscribes the housing at the inlet end of the at least one exhaust gas pipe.

11. The exhaust gas cooler as claimed in claim 1, wherein the fastening point of the at least one exhaust gas pipe is located downstream of the flange with respect to the flow direction of the exhaust gas.

12. The exhaust gas cooler as claimed in claim 1, wherein an exterior of the at least one exhaust gas pipe is exposed to the exhaust gas upstream of the fastening point with respect to the flow direction of the exhaust gas while the exterior of the at least one exhaust gas pipe is exposed to a coolant downstream of the fastening point with respect to the flow direction of the exhaust gas.

13. The exhaust gas cooler as claimed in claim 1, wherein a second gap is provided between a second one of the short sides of the wall of the at least one exhaust gas pipe and each of the housing and the flange at the inlet end of the at least one exhaust gas pipe.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, a sample embodiment of the invention as shown in the figures shall be explained more closely. There is shown:

(2) FIG. 1 is a perspective partial view of an exhaust gas cooler according to the invention; and

(3) FIG. 2 is a fragmentary cross sectional view of the inlet region of an exhaust gas cooler according to the invention

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

(4) As can be seen from FIG. 1, an exhaust gas cooler 10 according to the invention has a substantially rectangular cross section and an elongated extension (upward to the left in FIG. 1) in the illustrated case. By means of a flange 22, the exhaust gas cooler 10 may be attached to an exhaust gas (recirculation) line, which is not shown, or connected to a valve housing, especially an AGR valve (or to an AGR module). The flange 22 may be cast, for example, and the following described walls of exhaust gas pipes 12, ribs 18 provided in them, and a housing 26 may be formed from appropriately bent sheet metal. On an inside of the exhaust gas cooler 10, there are numerous exhaust gas pipes 12, which are formed substantially by metal plates 20 oriented parallel to each other, relatively flat side walls, and the ribs or fins 18 arranged between them, which can be better seen in the cross sectional top view of FIG. 2. The plates 20 thus form walls of the exhaust gas pipes 12, designed as flat tubes, and may therefore experience damage on account of the expansion and contraction as described above.

(5) It can be seen from FIG. 2 that the housing 26 is provided between the flange 22 and the exhaust gas pipes 12, surrounding the numerous exhaust gas pipes 12, so that the exhaust gas pipes 12 closed at the sides can be bathed in a liquid coolant, such as water, in order to cool the exhaust gas flowing through the exhaust gas pipes 12.

(6) The housing 26 is respectively connected on an outside to the massive flange 22, but according to the invention a gap 16 is situated at an inlet 14 of a respective one of the exhaust gas pipes 12 and at a side thereof, which is visible at the left and right side in FIG. 2, advantageously making possible an expansion of the respective one of the exhaust gas pipes 12 when heated as a result of the flow of the hot exhaust gas through it. The lateral extension, in other words the extension perpendicular to the flow direction (from bottom to top in FIG. 2) can be seen at left and right in FIG. 2. The extension of the gaps 16 in the flow direction up to a fastening point 28 of the exhaust gas pipes 12 to the housing 26 likewise runs from bottom to top in FIG. 2 and preferably amounts to 5 mm to 2 cm. Further gaps 24 are provided in the further course of the connection between the housing 26 and the exhaust gas pipe 12.

(7) FIG. 2 moreover shows a wave shape of the ribs running in the flow direction in the embodiment shown.

(8) The fastening point 28 in the sample embodiment shown extends for at least a few millimeters, such as 5 millimeters and/or up to 2 cm in the flow direction. Accordingly, the following is evident: if the fastening point 28 in such an embodiment were provided directly at the upstream end of the plate or the wall 20, and thus at the inlet, it is not possible to supply coolant here on account of the extension of the fastening point 28 in the flow direction. Accordingly, the above described problem arises, which is solved by the gap 16 according to the invention, which shifts the fastening point 28 to a certain extent downstream in the flow direction.

(9) In the embodiment shown, the flange 22 has a thickness, measured in the flow direction, which is larger than the extension of the gap 16, in order to achieve an overall stable configuration.

(10) According to the sample embodiment, the exhaust gas cooler 10 has two inlets arranged alongside each other and adjacent to these, stacked groups of exhaust gas pipes 12, but the exhaust gas cooler according to the invention may likewise have a single inlet and an adjacent group of exhaust gas pipes 12, as well as more than two inlets and correspondingly provided exhaust gas pipes 12.