EXHAUST GAS HEAT TRANSFER UNIT

Abstract

An exhaust gas heat transfer unit is disclosed having a heat exchanger including a bypass duct, an inflow diffuser with an exhaust gas inlet, and an outflow diffuser with an exhaust gas outlet. The heat exchanger and the bypass duct are assigned a control apparatus which diverts the exhaust gas flow through the heat exchanger and/or the bypass duct.

Claims

1. An exhaust gas heat transfer unit, comprising: a heat exchanger having a bypass duct; an inflow diffuser with an exhaust gas inlet; an outflow diffuser with an exhaust gas outlet; the heat exchanger and the bypass duct being assigned a control means which diverts the exhaust gas flow through the heat exchanger or the bypass duct; wherein the outflow diffuser comprises at least one guide element which separates the exhaust gas flow from the heat exchanger and the exhaust gas flow from the bypass duct as far as into the region of the exhaust gas outlet.

2. The exhaust gas heat transfer unit of claim 1, wherein the at least one guide element is a guide metal sheet.

3. The exhaust gas heat transfer unit of claim 1, further comprising a plurality of guide elements each formed by a duct.

4. The exhaust gas heat transfer unit of claim 3, wherein two ducts form the outflow diffuser.

5. The exhaust gas heat transfer unit of claim 1, wherein the outflow diffuser and the guide element are formed materially integrally as a cast part.

6. The exhaust gas heat transfer unit of claim 1, wherein the outflow diffuser is in the form of a multi-part sheet-metal component.

7. The exhaust gas heat transfer unit of claim 1, further comprising a common housing, and wherein the heat exchanger and the bypass duct are arranged in the common housing.

8. The exhaust gas heat transfer unit of claim 1, wherein the heat exchanger and the bypass duct are arranged in separate housings.

9. The exhaust gas heat transfer unit of claim 1, wherein in particular switched exhaust gas recirculation cooler (EGR cooler).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention will be described in more detail below on the basis of exemplary embodiments illustrated in the drawings, in which:

[0028] FIG. 1 is a side schematic view of an exhaust gas heat transfer unit according to one embodiment;

[0029] FIG. 2 is a side schematic view of an exhaust gas heat transfer unit according to a second embodiment;

[0030] FIG. 3 is a perspective view of an outflow diffuser of an exhaust gas heat transfer unit;

[0031] FIG. 4 is a side sectional view through the outflow diffuser illustrated in FIG. 3; and,

[0032] FIG. 5 is a perspective view of the outflow diffuser from the direction of the heat exchanger and the bypass duct.

[0033] In the figures, the same reference signs are used for identical or similar components even if a repeated description is omitted for reasons of simplicity.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0034] FIG. 1 illustrates an exhaust gas heat transfer unit 1 in form of a switched exhaust gas recirculation cooler (EGR cooler), and FIG. 2 illustrates an alternative embodiment of an exhaust gas heat transfer unit designated by reference numeral 2.

[0035] Each exhaust gas heat transfer unit 1, 2 includes a heat exchanger 3 functioning as an exhaust gas cooler, and a bypass duct 4. An inflow diffuser 5 is arranged upstream of the heat exchanger 3 and the bypass duct 4 in an exhaust gas flow direction shown by arrow EG in FIGS. 1 and 2. The exhaust gas EG enters the exhaust gas heat transfer unit 1, 2 via an exhaust gas inlet 6 in the inflow diffuser 5. In the inflow diffuser 5, the heat exchanger 3 and the bypass duct 4 are assigned a controller such as, but not limited to, a bypass flap 7. The bypass flap 7 functions as a switch for conducting the exhaust gas flow either through the heat exchanger 3 for cooling purposes or through the bypass duct 4 if no cooling of the exhaust gas EG is required. The bypass flap 7 closes the respective path through which the flow does not pass through.

[0036] The heat exchanger 3 and the bypass duct 4 are arranged in a common housing 8. The exhaust gas EG exits the exhaust gas heat transfer unit 1 or 2 via an outflow diffuser 9 positioned downstream of the heat exchanger 3 and the bypass duct 4 in a flow direction. The outflow diffuser 9 has an exhaust gas outlet 11 via which the exhaust gas is conducted out of the outflow diffuser 9 and is circulated to the intake air duct of the intake tract of the exhaust gas recirculation system.

[0037] In the exhaust gas heat transfer unit 1, a guide element 12 in the form of a guide metal sheet 13 is arranged in the outflow diffuser 9. The guide element 12 extends from the heat exchanger 3 and the bypass duct 4 as far as into the region of the exhaust-gas outlet 11. Here, the guide element 12 is configured so as to separate the exhaust-gas flow from the heat exchanger 3 and the exhaust-gas flow from the bypass duct 4 as far as into the region of the exhaust-gas outlet 11.

[0038] There are two guide elements 12 in form of separate ducts 14, 15 provided in the outflow diffuser 10 of the exhaust gas heat transfer unit 2. The first duct 14 is connected to the exhaust gas outflow side 16 of the heat exchanger 3. The second duct 15 communicates with the outlet 17 of the bypass duct 4. The two ducts 14, 15 run in the outflow diffuser 10 in the direction of the exhaust gas outlet 11 and separate the exhaust gas flow from the heat exchanger 3 and the exhaust gas flow from the bypass duct 4 as far as into the region of the exhaust gas outlet 11. The two ducts 14, 15 are merged at that point and the exhaust gas EG is conducted onward. It is contemplated for the two ducts 14, 15 to form the outflow diffuser 10, such that a separate diffuser housing is not required.

[0039] Moreover, both the outflow diffuser 9 in the first embodiment and the outflow diffuser 10 in the second embodiment together with the integrated guide elements 12 in the form of a guide metal sheet 13 or of ducts 14, 15 may be formed materially integrally as a cast part or as a multi-part sheet-metal component.

[0040] Referring to FIGS. 3 to 5, the outflow diffuser 9 shown FIG. 1 is illustrated. The outflow diffuser 9 is composed of high-grade cast steel and forms a cap-shaped diffuser housing 18. The diffuser housing 18 has an attachment section 19 of substantially rectangular configuration for coupling to the exhaust gas outflow side 16 of the heat exchanger 3.

[0041] Moreover, a connection port 20 is provided for attaching to the bypass duct 4. Depending on the operation of an exhaust gas heat transfer unit 1, exhaust gas EG flows from the heat exchanger 3 via the attachment section 19 into the outflow diffuser 9, or alternatively, via the connection port 20 from the bypass duct 4 into the outflow diffuser 9. From the outflow diffuser 9, the exhaust gas EG is discharged through the exhaust gas outlet 11 and conducted to downstream system components.

[0042] The guide element 12 in the form of the guide metal sheet 13 is formed in the outflow diffuser 9. The guide metal sheet 13 is a materially integral constituent part of the outflow diffuser 9. The guide metal sheet 13 extends from the inflow side 21 of the outflow diffuser 9, proceeding from the lower transverse web 22 of the attachment section 19, in the direction of the exhaust gas outlet 11, and ends in the region of the exhaust gas outlet 11. By means of the guide element 12 or the guide metal sheet 13, the exhaust gas flow from the heat exchanger 3 and the exhaust gas flow from the bypass duct 4 are separated as far as into the region of the exhaust gas outlet 11. It can be seen that the guide metal sheet 13 ends a short distance upstream of the exhaust-gas outlet 11. The distance A of the end 23 of the guide metal sheet 13 from the exhaust gas outlet 11 amounts to less than half of the diameter D of the exhaust gas outlet 11.

[0043] Referring more specifically to FIG. 5, the opening 24 of the exhaust gas outlet 11 has a substantially circular configuration. The guide metal sheet 13 extends inward in the outflow diffuser 9 over the width thereof and runs obliquely in the direction of the center of the opening 24 of the exhaust gas outlet 11.

[0044] The guide element 12 or the guide metal sheet 13, like the separate ducts 14, 15, prevent exhaust gas EG passing from the bypass duct 4 from flowing over or flowing back to the heat exchanger 3. The undesired or disadvantageous cooling of exhaust gas in the bypass mode is avoided, and thus a fast warm-up of the internal combustion engine is ensured by means of the optimized exhaust gas guidance in the outflow diffuser 9 of an exhaust gas heat transfer unit 1 or 2.

[0045] The foregoing description of some embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The specifically described embodiments explain the principles and practical applications to enable one ordinarily skilled in the art to utilize various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. Further, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as described by the appended claims.