Turbocharger arrangement

Abstract

Turbocharger arrangement of an internal combustion engine with a first turbocharger (10), wherein the first turbocharger (10) provides a high-pressure compressor and a high-pressure turbine (12), each in radial design, and with a second turbocharger (11), wherein the second turbocharger (11) provides a low-pressure compressor and a low-pressure turbine (13), each in axial configuration, and with a flow body (14), wherein the flow body (14) supplies exhaust gas leaving the radial high-pressure turbine (12) of the first turbocharger (10) to the axial low-pressure turbine (13) of the second turbocharger (11), characterized in that the flow body (14) is rotationally symmetrical in the direction of flow of the exhaust gas and has a flow channel with an annular cross-section through which flow occurs in the axial direction of the flow body (14), wherein an inner contour (19) of the annular flow channel (14) is defined by an inner radius Ri which changes in the axial direction, wherein an outer contour (20) of the annular flow channel (14) is defined by an outer radius Ra which changes in the axial direction, wherein at each axial position of the flow body (14) an annular area of ​​the flow body (14) between the inner radius Ri of the inner contour (19) and the outer radius Ra of the outer contour (20) of the relationship F = π / 4 × ((2Ra) 2 -(2Ri) 2 ) = constant follows, so that the exhaust gas in the area of ​​the flow body (14) is subject to virtually no change in velocity in the axial direction of the same.

Description

[0001] The invention relates to a turbocharger arrangement according to the preamble of claim 1.

[0002] From DE 10 2007 017 843 A1, a turbocharger arrangement for an internal combustion engine is known in which two turbochargers are connected in series. A first turbocharger provides a high-pressure compressor and a high-pressure turbine, and a second turbocharger provides a low-pressure compressor and a low-pressure turbine. It is already known from this prior art to design the high-pressure turbine of the first turbocharger in a radial configuration and the low-pressure turbine of the second turbocharger in an axial configuration. According to this prior art, exhaust gas leaving the radial high-pressure turbine can be fed to the axial low-pressure turbine via a flow element provided by a flow casing.

[0003] DE 10 2007 046 667 A1 discloses a multi-stage charging unit with a radial turbine and an axial turbine, wherein the radial turbine provides a high-pressure turbine and the axial turbine a low-pressure turbine. A calming section for the exhaust gas extends between the radial high-pressure turbine and the axial low-pressure turbine to feed the exhaust gas from the radial high-pressure turbine to the axial low-pressure turbine.

[0004] WO 2004 / 101971 A1 discloses a turbocharger arrangement with two turbochargers, wherein a high-pressure turbocharger comprises a radially designed high-pressure turbine and a low-pressure turbocharger comprises an axially designed low-pressure turbine. A flow element is positioned between the high-pressure turbine and the low-pressure turbine, the flow element being arranged in a tube, with an annular flow channel formed between the flow element and the tube.

[0005] Further state of the art is known from WO 2007 / 061 339 A1 and from BOHL, Willi: Technical Fluid Mechanics: Material Properties of Liquids and Gases, Hydrostatics, Aerostatics, Incompressible Flows, Compressible Flows, Flow Measurement Technology. 5th, revised edition. Würzburg: Vogel-Buchverlag, 1982 (Kamprath Series Technology). pp. 171, 172. - ISBN 3-8023-0036-X.

[0006] Based on this, the invention aims to create a novel turbocharger arrangement with improved efficiency. This objective is achieved by a turbocharger arrangement according to claim 1.

[0007] The invention allows flow losses between the radial high-pressure turbine and the axial low-pressure turbine to be almost completely avoided. The flow body of the turbocharger arrangement according to the invention enables virtually loss-free guidance of the exhaust gas from the radial high-pressure turbine towards the axial low-pressure turbine.

[0008] Preferably, the flow body is designed such that the exhaust gas undergoes virtually no change in velocity when passing from the radial high-pressure turbine into the flow body and when passing from the flow body into the axial low-pressure turbine. If the exhaust gas also undergoes no change in velocity when passing from the radial high-pressure turbine into the flow body and when passing from the flow body into the axial low-pressure turbine, the efficiency can be further increased, since flow losses can then be avoided during these transitions as well.

[0009] Preferred embodiments of the invention are described in the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being limited thereto. The drawing shows: Fig. 1: a schematic section of a turbocharger arrangement.

[0010] The present invention relates to a turbocharger arrangement for an internal combustion engine, for example, for a marine diesel engine powered by heavy fuel oil. Such a turbocharger arrangement comprises a first turbocharger and a second turbocharger connected in series.

[0011] Fig. Figure 1 shows a section of a turbocharger arrangement according to the invention in the area of ​​a high-pressure turbine 12 provided by a first turbocharger 10 and a low-pressure turbine 13 provided by the second turbocharger 11, wherein the flow direction of the exhaust gas in the area of ​​the high-pressure turbine 12 and the low-pressure turbine 13 is visualized by arrows A.

[0012] In the area of ​​the high-pressure turbine 12 of the first turbocharger 10, exhaust gas A is expanded and the energy gained in this process is used to drive a Fig. 1 high-pressure compressor of the first exhaust gas turbocharger 10, not shown.

[0013] The energy gained by the further expansion of the exhaust gas A in the area of ​​the low-pressure turbine 13 of the second exhaust gas turbocharger 11 is used to drive a low-pressure compressor of the second exhaust gas turbocharger 11, which is also not shown.

[0014] According to Fig. The high-pressure turbine 12 of the first exhaust gas turbocharger 10 is of radial design and is therefore configured as a radial high-pressure turbine 12. The low-pressure turbine 13 of the second turbocharger 11 is of axial design and is therefore configured as an axial low-pressure turbine 13.

[0015] The high-pressure compressor of the first turbocharger 10, not shown, is of radial design, for example. The low-pressure compressor of the second turbocharger 11, also not shown, is of radial design, for example.

[0016] The exhaust gas A, which exits the radial high-pressure turbine 12 of the first turbocharger 10, can be fed to the axial low-pressure turbine 13 of the second turbocharger 11 via a flow element 14, which is positioned between the radial high-pressure turbine 12 and the axial low-pressure turbine 13. The flow element 14 is designed such that the exhaust gas A is subject to virtually no change in velocity within the flow element 14. Any change in velocity can only occur due to frictional losses of the exhaust gas flow within the flow element 14. For this purpose, the flow element 14 is designed such that a flow channel within it, viewed in the direction of exhaust gas flow, exhibits no change in cross-section.

[0017] According to an advantageous embodiment of the invention, the flow body 14 is further configured such that the exhaust gas A undergoes virtually no change in velocity both when passing from the radial high-pressure turbine 12 into the flow body 14 and when passing from the flow body 14 into the axial low-pressure turbine 13. For this purpose, the flow body 14 is configured such that the cross-sectional area of ​​an inlet region 15 of the flow channel of the flow body 14 corresponds to the cross-sectional area of ​​an outlet region 16 of a flow channel of the radial high-pressure turbine 12. Likewise, the cross-sectional area of ​​an outlet region 17 of the flow channel of the flow body 14 corresponds to the cross-sectional area of ​​an inlet region 18 of the flow channel of the axial low-pressure turbine 13.

[0018] The flow body 14 is a rotationally symmetrical flow body that has a ring-shaped flow channel in cross-section, through which flow occurs in the axial direction of the flow body 14. This shows Fig. 1, that an inner contour 19 of an annular flow channel of the flow body 14 is defined by an inner radius Ri which changes in the axial direction or flow direction of the exhaust gas A, wherein an outer contour 20 of the annular flow channel of the flow body 14 is defined by an outer radius Ra which changes in the flow direction or axial direction.

[0019] The flow body 14 is designed to be rotationally symmetric such that at every axial position of the same, the annular area of ​​the flow body 14 between the radius Ri of the inner contour 19 and the radius Ra of the outer contour 20 of the relationship: F=π / 4×((2Ra)2−(2Ri)2)=constant approximately follows.

[0020] A uniform velocity field of the exhaust gas flow A is ensured throughout the entire flow body 14, during the transition of the exhaust gas flow A from the radial high-pressure turbine 12 into the flow body 14, and during its transition from the flow body 14 into the axial low-pressure turbine 13. The exhaust gas flow A is therefore subject to neither deceleration nor acceleration. This can positively influence the efficiency of a turbocharger arrangement. Reference symbol list 10 first turbocharger 11 second turbocharger 12 Radial high-pressure turbine 13 Axial low-pressure turbine 14 flow bodies 15 Inlet area of ​​the flow body 16 Exit area of ​​the radial high-pressure turbine 17 Outlet area of ​​the flow body 18 Inlet area of ​​the axial low-pressure turbine 19 Inner contour of the flow body 20 Outer contour of the flow body

Claims

[1] Turbocharger arrangement of an internal combustion engine with a first turbocharger (10), wherein the first turbocharger (10) provides a high-pressure compressor and a high-pressure turbine (12), each in radial design, and with a second turbocharger (11), wherein the second turbocharger (11) provides a low-pressure compressor and a low-pressure turbine (13), each in axial configuration, and with a flow body (14), wherein the flow body (14) supplies exhaust gas leaving the radial high-pressure turbine (12) of the first turbocharger (10) to the axial low-pressure turbine (13) of the second turbocharger (11), characterized by , that the flow body (14) is rotationally symmetrical in the direction of the exhaust gas flow and has a ring-shaped flow channel in cross-section through which flow occurs in the axial direction of the flow body (14), wherein an inner contour (19) of the annular flow channel (14) is defined by an inner radius Ri which changes in the axial direction, wherein an outer contour (20) of the annular flow channel (14) is defined by an outer radius Ra which changes in the axial direction, wherein at each axial position of the flow body (14) an annular area of ​​the flow body (14) between the inner radius Ri of the inner contour (19) and the outer radius Ra of the outer contour (20) of the relationship F = π / 4 × ((2Ra) 2 -(2Ri) 2 ) = constant follows, so that the exhaust gas in the area of ​​the flow body (14) is subject to virtually no change in velocity in the axial direction of the same. [2] Turbocharger arrangement according to claim 1, characterized by , that the flow body (14) is designed such that a cross-sectional area of ​​an inlet region (15) of a flow channel of the flow body (14) corresponds to a cross-sectional area of ​​an outlet region (16) of a flow channel of the radial high-pressure turbine (12), a cross-sectional area of ​​an outlet region (17) of a flow channel of the flow body (14) corresponds to a cross-sectional area of ​​an inlet region (18) of a flow channel of the axial low-pressure turbine (13), so that the exhaust gas is subject to virtually no change in velocity when passing from the radial high-pressure turbine (12) into the flow body (14) and when passing from the flow body (14) into the axial low-pressure turbine (13). [3] Turbocharger arrangement according to claim 1 or 2, characterized by that it is a turbocharger arrangement of a marine diesel engine.

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