DE102012014189A1 - Internal combustion engine has exhaust conduits to provide lower and higher pressure drop for flowing exhaust gas, and exhaust turbine whose first cross-section of flow passage is smaller than second cross-section of flow passage - Google Patents

Abstract

The internal combustion engine (1) has an exhaust conduit (18,19) that is configured to pass an exhaust gas from cylinder (Z1,Z4) to an exhaust gas turbine (8) of a turbocharger (6). The exhaust gas turbine is provided with flow passage (9,11) with first and second cross-sections (10,12). The exhaust conduits configured to provide lower and higher pressure drop for the flowing exhaust gas. The first cross-section of the flow passage (9) of the exhaust turbine is smaller than the second cross-section (12) of the flow passage (11).

Description

The invention relates to an internal combustion engine with an exhaust gas turbocharger having a dual-flow exhaust gas turbine with the features of the preamble of claim 1.

Exhaust gas turbochargers with twin-flow exhaust gas turbines are usually used in internal combustion engines with surge charging. This exhaust gases of those cylinders are summarized, which amplify from the firing order. In an internal combustion engine with six cylinders, the exhaust gases of three cylinders are combined in a first exhaust pipe. The exhaust gases of the remaining three cylinders are combined in a second exhaust pipe. Thus, the exhaust gases are routed separately in the exhaust pipes to the exhaust gas turbine. In operating ranges of the internal combustion engine with strongly pulsating exhaust gas mass flows, the exhaust gas energy can be better utilized with such a turbine.

From the publications DE 101 52 804 A1 . DE 103 57 925 A1 . DE 10 2005 021 172 A1 . DE 10 2005 021 173 A1 . DE 2006 022 181 A1 . DE 2006 022 182 A1 and DE 10 2009 010 516 A1 are known double-flow exhaust gas turbines. Both flow flows have different sized cross sections at the entrance to the exhaust gas turbines. In this case, the smaller cross section of the two flow passages serves to accumulate exhaust gas in an associated exhaust gas line in order to lead a part of the exhaust gas via an exhaust gas recirculation line to an inlet side of the internal combustion engine. The aim is to realize exhaust gas recirculation in these publications in order to reduce the emissions of the internal combustion engine.

The disadvantage here is that the damming of the exhaust gas in a first flow and first exhaust pipe, the associated cylinders are hindered in the gas exchange. Where, however, an unimpeded gas exchange can take place in the associated cylinders to form a second flow passage and second exhaust passage. A disabled gas change manifests itself, for example, in increased Ausschubarbeit the piston or in excessive fate of residual gas in the cylinder. On the one hand, this leads to an incomplete cylinder filling, on the other hand to an increase in the temperature of the cylinder and the components surrounding it with the known harmful effects, and thermodynamically to a loss of efficiency of the internal combustion engine.

The object of the invention is to achieve a symmetrical Aufstauverhalten and thus the same turbine flow rate parameters of the exhaust gas in the two exhaust pipes and their associated flow passages of the exhaust gas turbine to the exhaust gas turbine.

The solution is carried out with an internal combustion engine with the features of claim 1. Advantageous embodiments of the invention are illustrated in the subclaims.

According to the invention, an internal combustion engine is provided which comprises a first and second exhaust pipe, wherein an exhaust gas flows through at least one cylinder through the first exhaust pipe and flows through the second exhaust pipe, the exhaust gas from at least one second cylinder and both exhaust pipes to an exhaust gas turbine of an exhaust gas turbocharger Internal combustion engine are arranged, wherein the exhaust gas turbine having a first flow passage having a first cross section, and a second flow passage having a second cross section and the first flow passage fluidly connected to the first exhaust passage, and the second flow passage is fluidly connected to the second exhaust passage, wherein During operation of the internal combustion engine, the first exhaust pipe has a first, lower pressure drop than the second exhaust pipe for the exhaust gas flowing through it and the second exhaust pipe has a second, higher pressure loss than the first Abga The first cross section of the first flow passage of the exhaust gas turbine is smaller than the second cross section of the second flow passage. Relevant correlations of fluidic and geometrical characteristics are explained in more detail in the description of the figures. Based on an internal combustion engine with different pressure losses in the exhaust pipes so that a total symmetrical Aufstauverhalten can be achieved for the exhaust gas. This results in the same turbine flow rate parameters for both flow passages of the exhaust gas turbine. From the symmetrical Aufstauverhalten result in addition equal back pressures for all cylinders. As a result, the individual cylinders simultaneously reach their thermodynamic limits, which is overall thermodynamically advantageous for the internal combustion engine.

According to a preferred embodiment of the invention, the pressure losses in the exhaust pipes caused by internal resistance, friction and flow deflections in the exhaust pipes.

According to a further preferred embodiment of the invention is in the internal combustion engine compared to two equal-sized, symmetrical cross sections and resulting symmetrical ratios of cross-sectional areas to radius (A / R ratio) of a symmetrical first and second flow in the present invention, the first Cross section designed so that the first A / R ratio of the first flow trough in a range of 90% to 100% of the symmetrical A / R ratio corresponds to and the second cross-section is designed so that the second A / R ratio of the second flow passage in a range of 100% to 110% of the symmetrical A / R ratio corresponds. Advantageously, therefore, the cross sections of the flow passages can be adapted to the pressure losses of the respective associated exhaust pipe in order to achieve the same turbine flow rate parameters for both flow passages of the exhaust gas turbine. This means that the exhaust line with the higher pressure loss is combined with the larger cross-section of the flow passages, ie smaller pressure loss. Conversely, the smaller pressure loss exhaust gas line is combined with the smaller cross section of the flow passages, ie larger pressure drop.

According to a further preferred embodiment of the invention, the first cross section of the first flow trough is designed so that the first A / R ratio of the first flow trough corresponds to 96% of the symmetrical A / R ratio of 100% and the second cross section of the second flow trough is so stated that the second A / R ratio of the second flow trough corresponds to 104% of the symmetrical A / R ratio of 100%.

According to a further preferred embodiment of the invention, the exhaust gas turbocharger is arranged asymmetrically to the cylinders and their connections to the exhaust pipes. The cylinders are arranged symmetrically and thus form a plane of symmetry. Usually lies in this plane of symmetry of the exhaust gas turbocharger, which requires restrictions in the arrangement of other components. According to the invention can be reacted to a space-related conditions with a single-ended arrangement. Thus, the exhaust gas turbocharger can be placed so that it is technically the cheapest.

According to a further preferred embodiment of the invention, the exhaust gas turbocharger is arranged at a power end of the internal combustion engine. In some applications, there is little room for their installation radially to the engine. Therefore, it is of great advantage if larger normally radially arranged components, for example the exhaust gas turbocharger, can be arranged axially on the internal combustion engine. On the one hand, the force side, d. H. output side, end of the engine on. On the other hand, the arrangement of the exhaust gas turbocharger at the free end, d. H. the power-side opposite end of the engine possible. The consequence of this are exhaust pipes with different pressure losses for the exhaust gas.

According to a further preferred embodiment of the invention, the exhaust gas turbocharger is arranged at a free end of the internal combustion engine.

According to a further preferred embodiment of the invention, the exhaust pipes are after the connections to the cylinders predominantly parallel to a crankshaft of the internal combustion engine and have different lengths. In installation situations with an arrangement of the exhaust gas turbocharger, for example at a power-side or free end of the internal combustion engine, a space-saving arrangement of the exhaust pipes is close fitting to the internal combustion engine and parallel to the crankshaft possible. This results in different lengths of the exhaust pipes with different pressure losses.

An embodiment of the invention is illustrated in the drawing and will be described in more detail below.

Show it:

1 a schematic diagram of an internal combustion engine with a dual-flow exhaust gas turbine

2 a schematic diagram of an exhaust gas turbine with constructive sizes

3 a schematic diagram of a twin-flow exhaust gas turbine with constructive sizes

4 Diagrams with a qualitative representation of turbine throughput parameters in symmetrical and asymmetrical cross sections of the flow passages of an exhaust gas turbine

1 shows a schematic diagram of an internal combustion engine 1 with a twin-flow exhaust gas turbine 8th , The internal combustion engine 1 is here as a series arrangement of cylinders Z1 to Z6 with an associated crankshaft 2 and a flywheel arranged thereon 3 shown. This forms the power end 4 the internal combustion engine. Opposite this is the free end 5 the internal combustion engine. At this free end 5 is an exhaust gas turbocharger shown in principle 6 arranged. He has a compressor 7 and the above-mentioned twin-flow exhaust gas turbine 8th in partial view. As known in the art, the compressor compacts 7 Charge air and promotes this via a charge air cooler 16 and charge air lines 17 in the cylinders of the internal combustion engine 1 , The twin-flow exhaust gas turbine 8th includes a first 9 and a second 11 Flow tide and an exhaust gas turbine wheel 13 that around an axis 14 the exhaust gas turbocharger is rotatably mounted. The first flow tide 9 has a first cross section 10 on, which is smaller than the second cross-section 12 the second flow tide 11 , In the first flow tide 9 flows over a first exhaust pipe 18 Exhaust gas of the cylinders Z1 to Z3. In the second flow tide 11 flows over a second exhaust pipe 19 Exhaust gas of the cylinders Z4 to Z6. Depending on the firing order and thermodynamic conditions, another fluidic summary of the exhaust gases of the cylinders is possible. The exhaust gas turbine wheel 13 gets out of both flow tides 9 and 11 flowed by the exhaust gas and set in rotation before the exhaust gas, the exhaust gas turbine 8th through an exhaust outlet 15 leaves in the direction of the arrow. The first exhaust pipe 18 is shorter than the second 19 and therefore has a smaller pressure loss than the second one for the exhaust gas flowing through it 19 longer exhaust pipe. Assuming two symmetrical flow flows with the same cross sections, this would result in different turbine throughput parameters for the exhaust gas turbine 8th and give different exhaust back pressures for the cylinders. This is thermodynamic for both the exhaust gas turbine 8th , as well as for the cylinder unfavorable and is inventively with a first cross section 10 corrected, which is smaller than a cross section at two symmetrical flow flows with the same cross sections. To the extent that the first cross section 10 is reduced, becomes the second cross section 12 increased. This results in a greater pressure loss in the first flow trough 9 and smaller pressure loss in the second flow 11 compared to symmetrical flow. This results in different geometric A / R ratios, as in the 2 and 3 is explained in more detail. The goal of the asymmetrical distribution of the cross sections of the flow tides 9 and 11 is in connection with different pressure losses in the exhaust pipes 18 and 19 , same backflow behavior and equal turbine flow rate parameters for both flows 9 and 11 to reach (see 4 ).

2 shows a schematic diagram of an exhaust gas turbine with constructive sizes A and R in the general case. The size A indicates the cross-sectional area at the entrance 20 a flow tide of an indicated spiral 21 a single-flow exhaust gas turbine. To clarify the cross-sectional area is the entrance 20 the flow tide is shown in perspective. The size R is the radius of one axis 22 of the exhaust turbine wheel (not shown here) to the centroid of the cross section A. Both set in relation to give the so-called A / R ratio of a spiral of a turbomachine, especially an exhaust gas turbine. This A / R ratio is proportional to the turbine flow rate parameter Φ, which is to be determined from the exhaust gas mass flow, the exhaust gas temperature and the exhaust gas pressure in the region of the plugging limit of the exhaust gas turbine. As a deeper reading here GP Merker et al. (Ed.), Fundamentals of Internal Combustion Engines, Springer Fachmedien Wiesbaden (2012) p. 204ff , called.

3 shows a schematic diagram of the dual-flow exhaust gas turbine according to the invention 8th with constructive sizes A ₁ and R ₁ and A ₂ and R ₂ . Here, A _{1 is} the area of the first cross section 10 and R _{1 is} the radius from the axis 14 of the exhaust gas turbine wheel to the centroid of A ₁ at. This results in an A ₁ / R ₁ ratio for the first flow tide 9 , This A ₁ / R ₁ ratio is proportional to a first turbine flow rate parameter Φ _{1 of} the first flow trough 9 , Accordingly, A ₂ and R _{2 result in} an A ₂ / R ₂ ratio and a second turbine flow rate parameter Φ ₂ for the second flow trough 11 ,

4 shows diagrams with a qualitative representation of turbine flow rate parameters over a pressure ratio across an exhaust gas turbine. The left diagram shows different turbine flow rate parameters Φ ₁ and Φ ₂ in a design of the exhaust gas turbine with two symmetrical cross sections of the flow passages. The pressure ratio p ₁ / p ₂ is the known from the usual turbine design ratio of pressure before (p ₁ ) to pressure to (p ₂ ) turbine. The right-hand diagram shows an approximation of the turbine flow rate parameters Φ ₁ and Φ ₂ according to the invention in combination with the different pressure losses in the exhaust gas lines 18 and 19 , as well as the asymmetrical cross sections of the flow tides 9 and 11 the exhaust gas turbine 8th results. As an advantage, this results in a uniform flow of the exhaust gas turbine 13 with an improved efficiency of the exhaust gas turbine 8th , Another thermodynamic advantage for the internal combustion engine 1 results from an equal exhaust back pressure for all cylinders.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine

Z1, Z2, Z3, Z4, Z5, Z6

Cylinder 1 to 6

2

crankshaft

3

flywheel

4

power end of the internal combustion engine

5

free end of the internal combustion engine

6

turbocharger

7

compressor

8th

exhaust turbine

9

first flow tide

10

first cross-section

11

second flow tide

12

second cross section

13

exhaust turbine wheel

14

Axle exhaust gas turbocharger

15

exhaust outlet

16

Intercooler

17

Turbo pipe

18

first exhaust pipe

19

second exhaust pipe

20

Entrance flow tide

21

spiral

22

Axle exhaust turbine wheel

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10152804 A1 [0003]
• DE 10357925 A1 [0003]
• DE 102005021172 A1 [0003]
• DE 102005021173 A1 [0003]
• DE 2006022181 A1 [0003]
• DE 2006022182 A1 [0003]
• DE 102009010516 A1 [0003]

Cited non-patent literature

• GP Merker et al. (Ed.), Fundamentals of Internal Combustion Engines, Springer Fachmedien Wiesbaden (2012) p. 204ff [0022]

Claims (8)

Internal combustion engine ( 1 ) with a first ( 18 ) and a second ( 19 ) Exhaust pipe, wherein through the first exhaust pipe ( 18 ) an exhaust gas from at least one first cylinder (Z1) flows, and through the second exhaust pipe ( 19 ) the exhaust gas from at least one second cylinder (Z4) flows and both exhaust pipes ( 18 . 19 ) on an exhaust gas turbine ( 8th ) of an exhaust gas turbocharger ( 6 ) of the internal combustion engine ( 1 ), wherein the exhaust gas turbine ( 8th ) a first flow torrent ( 9 ) with a first cross section ( 10 ) and a second flow ( 11 ) with a second cross section ( 12 ) and the first flow ( 9 ) with the first exhaust pipe ( 18 ) is fluidically connected, and the second flow ( 11 ) with the second exhaust pipe ( 19 ) is fluidically connected, characterized in that during operation of the internal combustion engine ( 1 ) the first exhaust pipe ( 18 ) a first, lower pressure loss than the second exhaust pipe ( 19 ) for which it has exhaust gas flowing through and the second exhaust pipe ( 19 ) a second, higher pressure loss than the first exhaust pipe ( 18 ) for which it has exhaust gas flowing through and the first cross-section ( 10 ) of the first flow tide ( 9 ) of the exhaust gas turbine ( 8th ) is smaller than the second cross section ( 12 ) the second flow tide ( 11 ). Internal combustion engine ( 1 ) according to claim 1, characterized in that the pressure losses in the exhaust pipes ( 18 . 19 ) by internal resistance, friction and flow deflections in the exhaust pipes ( 18 . 19 ) are caused. Internal combustion engine ( 1 ) according to claim 2, characterized in that compared to two equal-sized, symmetrical cross sections and resulting symmetrical ratios of cross-sectional areas to radius of a symmetrical first and second flow trough, the first cross section ( 10 ) is designed so that the first A / R ratio of the first flow trough ( 9 ) in a range of 90% to 100% of the symmetrical A / R ratio and the second cross section ( 12 ) is designed so that the second A / R ratio of the second flow ( 11 ) in a range of 100% to 110% of the symmetrical A / R ratio. Internal combustion engine ( 1 ) According to claim 3, characterized in that the first cross-section ( 10 ) of the first flow tide ( 9 ) is designed so that the first A / R ratio of the first flow trough ( 9 ) Corresponds to 96% of the symmetrical A / R ratio of 100% and the second cross-section ( 12 ) the second flow tide ( 11 ) is designed so that the second A / R ratio of the second flow ( 11 ) Corresponds to 104% of the symmetrical A / R ratio of 100%. Internal combustion engine ( 1 ) according to one of claims 1 to 4, characterized in that the exhaust gas turbocharger ( 6 ) asymmetrically to the cylinders (Z1, Z2, Z3, Z4, Z5, Z6) and their connections to the exhaust pipes ( 18 . 19 ) is arranged. Internal combustion engine ( 1 ) according to one of claims 1 to 5, characterized in that the exhaust gas turbocharger ( 6 ) at a power end ( 4 ) of the internal combustion engine is arranged. Internal combustion engine ( 1 ) according to one of claims 1 to 5, characterized in that the exhaust gas turbocharger ( 6 ) at a free end ( 5 ) of the internal combustion engine is arranged. Internal combustion engine ( 1 ) according to one of claims 1 to 7, characterized in that the exhaust pipes ( 18 . 19 ) after the connections to the cylinders (Z1, Z2, Z3, Z4, Z5, Z6) predominantly parallel to a crankshaft ( 2 ) of the internal combustion engine ( 1 ) and have different lengths.

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