DE102013021567A1 - Turbine for supercharger of internal combustion engine mounted in motor vehicle, has coil segments that are formed to vary asymmetry degree by quotient of exhaust gas flow parameters by adjusting adjustment device in switching position - Google Patents

Abstract

The turbine (10) has turbine housing (12) having receiving space (14) for turbine wheel (16). The coil segments (20,22) are arranged in circumferential direction, partially and fluidly separated from each other and extended over circumference of turbine wheel, for guiding exhaust gas to receiving space. An adjustment device (24) is arranged in upstream of turbine wheel, to adjust flow rate of exhaust gas through coil segments. The coil segments are formed such that asymmetry degree is varied by quotient of flow parameters by adjusting adjustment device in switching position.

Description

The invention relates to a turbine for an exhaust gas turbocharger according to the preamble of patent claim 1.

From the serial production of passenger cars, it is known to use exhaust gas turbochargers with respective turbines to charge internal combustion engines for driving the passenger cars. In other words, the internal combustion engines are equipped with charging systems, which comprise at least one exhaust gas turbocharger. The exhaust gas turbocharger serves to utilize energy contained in the exhaust gas of the associated internal combustion engine by means of a turbine in order to compress air to be supplied to the internal combustion engine by means of a compressor of the exhaust gas turbocharger.

By means of such a supercharging system, internal combustion engines with relatively low stroke volumes, which are thus designed according to the so-called downsizing principle, can also provide very high specific powers and torques. The pursuit of the realization of particularly low emissions, in particular with regard to nitrogen oxide (NO _x ) emissions and soot emissions in the current development of supercharging systems, influences these very strongly.

Due to growing requirements with regard to charging pressure provision due to very high exhaust gas recirculation rates (EGR rates), especially over the medium load range up to the full load of the internal combustion engine, the turbines are more and more reduced in their flow cross-sections through which exhaust gas can flow. Particularly high turbine outputs are thus realized by the representation of a particularly high Aufstaufähigkeit or by reducing the absorption capacity of the turbines in interaction with the relevant internal combustion engine.

Moreover, it is known to use soot filters to at least partially filter out soot particles from the exhaust gas of the internal combustion engines. By means of such soot filters, which are arranged downstream of the turbines in an exhaust tract of the internal combustion engine, a respective inlet pressure level of the turbines due to a corresponding back pressure of the soot filters is increased, which may necessitate a further geometric reduction of the turbines to compressor side performance requirements for an air exhaust To be able to satisfy delivery. However, these geometric reductions are traditionally associated with only low efficiencies of the turbines.

It has been shown that the representation of particularly high exhaust gas recirculation rates in conjunction with a required combustion air for the internal combustion engine is problematic, especially in low to medium operating and load ranges. In the case of the usual design boundary conditions, which are also defined by the nominal point of the internal combustion engine from the charge change side or consumption side, the lower rotational speed range of the internal combustion engine can therefore only be insufficiently operated with regard to the air supply, for example in the case of an asymmetrical, double-flow, solid geometry turbine.

The DE 199 18 232 A1 discloses a multi-cylinder internal combustion engine with an exhaust gas turbocharger and with at least two different cylinders or cylinder groups associated separate exhaust pipes to the turbine of the exhaust gas turbocharger, which are fluidly connectable or separable according to the position of an actuator before entering the turbine. The actuator is designed as a wall sections of the exhaust pipes carrying slide, wherein the movable wall sections in the closed position of the slide for separating the exhaust pipes over coverage with fixed wall sections can be brought.

Of the DE 10 2008 039 085 A1 is an internal combustion engine for a motor vehicle with an exhaust gas turbocharger to take as known. The exhaust gas turbocharger comprises a turbine, with a turbine housing, which has a receiving space for a turbine wheel which can be rotated about an axis of rotation relative to the turbine housing. Furthermore, the turbine housing has at least two spiral segments extending in the circumferential direction of the turbine wheel over its circumference, at least partially fluidly separated from each other and arranged one behind the other in the circumferential direction, for guiding the exhaust gas to the receiving space. The turbine further comprises an adjustment device adjustable in an adjustment range in the form of a so-called tongue slider. By means of the adjusting device, respective flow cross-sections arranged upstream of the turbine wheel and associated with the respective spiral segments, ie respective flow cross-section of the spiral segments, via which, for example, the exhaust gas flowing through the spiral segments can be introduced into the receiving space, can be set. This means that a first of the spiral segments, a first of the flow cross sections and the second spiral segment of the second Flow cross section is assigned. The exhaust gas flowing through the first spiral segment can flow out of the first spiral segment via the first flow cross section and into the receiving space. The exhaust gas flowing through the second spiral segment can flow out of the second spiral segment via the second flow cross section and into the receiving space. The spiral segments each have a flow rate of the exhaust gas through the respective spiral segment characterizing throughput parameters.

From the US 2010/0196145 A1 a turbocharger with a turbine is known, which has a turbine housing with a receiving space for a turbine wheel. Upstream of the receiving space adjusting elements are provided, which are movable relative to the turbine housing and by means of which at least one of the exhaust gas flow-through flow cross-section of the turbine is adjustable.

Finally, the reveals US 2011/0243721 A1 a turbine for an exhaust gas turbocharger, with a turbine housing, which has a receiving space for a turbine wheel, wherein also upstream of the receiving space relative to the turbine housing movable adjusting elements are provided, by means of which at least one of exhaust gas flow-through flow cross-section of the turbine is variably adjustable.

In order to be able to advantageously set the ratio of the exhaust gas recirculation rates to the necessary air-fuel ratio numbers in a particularly large operating range, a double-flow turbine type is advantageous, which is particularly pronounced with regard to the impact charging capability, in particular in the case of a cylinder summary group. Turbines, which are designed especially for the supercharging, have very large flow cross sections for the use of the larger usable Exergieschwankungen or pressure pulsations of the exhaust gas of the internal combustion engine.

These high pressure pulsations of the internal combustion engine exist and arise on the turbine when the usually adjusting throttling and friction losses of exhaust valves of the internal combustion engine in a manifold region upstream of the turbine by a corresponding geometry design to the turbine keeps low. This reduction in throttle and friction losses upstream of the turbine promotes the achievement of the objective of realizing a particularly pronounced surge charge, thereby achieving an increase in the average overall efficiency of exhaust gas utilization despite large turbine variation over time. A so-called multi-segment turbine, with the aforementioned, in the circumferential direction successively arranged spiral segments, thereby represents a very good starting point to realize a particularly high efficiency of the turbine.

It is therefore an object of the present invention to develop a turbine for an exhaust gas turbocharger of the type mentioned in such a way that a particularly efficient operation of the turbine can be realized

This object is achieved by a turbine having the features of patent claim 1. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the remaining claims.

In order to further develop a turbine for an exhaust gas turbocharger of the kind specified in the preamble of claim 1 such that a particularly efficient operation of the turbine can be realized, it is provided according to the invention that the spiral segments are designed such that an asymmetry degree which is determined by a quotient of the flow rate parameters is formed, varies during adjustment of the adjustment at least in a part of the adjustment.

In the quotient, that is to say in the degree of asymmetry, a first of the throughput parameters in the numerator and the second throughput parameter in the denominator are therefore arranged. The first flow rate parameter characterizes the exhaust gas flow rate through a first one of the spiral segments, wherein the second flow rate parameter characterizes the exhaust gas flow rate through the second spiral segment. According to the invention, it is provided that the quotient, that is to say the degree of asymmetry, varies, that is, changes when the adjusting device is adjusted, that is, moved from a first position of the adjustment range to a second position of the adjustment range. Preferably, it is provided that the first position is an open position in which the respective flow cross-section is maximally released. This means that the open position is a first end position or end position of the adjusting device and that the flow cross-sections in any other belonging to the adjustment range position of the adjustment are more or more released, that is, have a greater value than in the open position.

Analogously, it is preferably provided that the second position is a closed position in which the respective flow cross-section is maximally reduced or narrowed. This means that the closed position is a second end position or an end position of the adjusting device and that the flow cross sections in any other, belonging to the adjustment range position of the adjustment are smaller, that is a lower value than in the closed position. The adjustment range is limited by the end positions. This means that the adjusting device can not be moved further than in the respective end positions.

Preferably, it is contemplated that the degree of asymmetry varies in a range of from 0.3 to 1.2 inclusive, and more particularly in a range from 0.3 to 0.8 inclusive.

By means of the turbine according to the invention, a compressor of the exhaust gas turbocharger can be driven particularly advantageously, so that a particularly advantageous supply of compressed air to the internal combustion engine can be realized under the boundary conditions of low emissions and fuel consumption while taking into account agility requirements for the internal combustion engine.

The turbine is designed as a two-segment turbine, preferably as a two-segment tongue slide turbine, wherein the adjusting device is preferably designed as a tongue slide. By a corresponding geometric design of the spiral segments behaves asymmetry, which is also referred to as asymmetry factor, within predeterminable limits predominantly variable in an adjustment of the tongue slider, in particular from the open position to the closed position. Due to the geometric design, in particular the size, the throughput spread and the spread of the Asymmetriegrads can be configured.

Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

The drawing shows in:

1 a schematic cross-sectional view of a turbine of an exhaust gas turbocharger for an internal combustion engine, with two spiral segments;

2 a diagram illustrating relative Flächenverläufen and thus spiral curves of different embodiments of the spiral segments;

3 a schematic representation of the internal combustion engine with the turbine;

4 a diagram in which respective cross-sectional profiles of the spiral segments are entered over the course of the spiral segments;

5 a diagram in which two curves of a degree of asymmetry of the turbine and two associated curves of a total flow rate parameter of the turbine are entered for different embodiments of the turbine; and

6 a diagram in which two profiles of the total flow rate parameter of the turbine, two profiles of a flow rate parameter of a first of the spiral segments and second curves of the second spiral segment of the turbine are entered for different embodiments of the turbine.

In the figures, the same or functionally identical elements are provided with the same reference numerals.

1 shows a turbine 10 for one out 3 recognizable and with 46 designated exhaust gas turbocharger designed as a reciprocating internal combustion engine internal combustion engine 48 a motor vehicle. The turbocharger 46 also includes a compressor 73 , by means of which the internal combustion engine 48 is to compress supplied air. Here is the compressor 73 from the turbine 10 drivable.

The turbine 10 includes a turbine housing 12 which is a recording room 14 for a turbine wheel 16 the turbine 10 having. The turbine wheel 16 is in the recording room 14 at least partially recorded and about a rotation axis 18 relative to the turbine housing 12 rotatable.

By means of the turbine housing 12 Exhaust gas from the internal combustion engine to the turbine wheel 16 guided, which is flowed by the exhaust and thereby driven. The turbine wheel 16 is with a wave 76 the exhaust gas turbocharger 46 rotatably connected. With this wave 76 is also a compressor wheel 74 of the compressor 73 connected. The compressor wheel 74 is in a compressor housing of the compressor 73 around the axis of rotation 18 rotatably received relative to the compressor housing and can due to the rotationally fixed connection with the shaft 76 from the turbine wheel 16 are driven. By means of the compressor wheel 74 becomes that of the internal combustion engine 48 compressed air to be supplied. Thus, by means of the exhaust gas turbocharger 46 in the exhaust of the internal combustion engine 48 contained energy can be used to compress the air.

The turbine 10 is presently designed as a so-called multi-segment turbine. In this case, the turbine housing 12 a first spiral segment 20 and a second spiral segment 22 on. The first spiral segment 20 extends in the circumferential direction of the turbine wheel 16 about its circumference with respect to a polar coordinate system originating O on the axis of rotation 18 over a wrap angle φ _Ages . The wrap angle φ _{Ages of} the first spiral segment 20 results from Φ _AE - Φ _A0 . In this case, Φ _{A0 is} an initial _angle at which a spiral _{inlet cross-section} A _{sA0 of} the first spiral _segment 20 is arranged. Further, φ _{AE is} an end angle at which one end of the first spiral segment 20 is arranged. In this case, the wrap angle φ _{Ages of} the first spiral segment 20 in the present case at least substantially 216 °. In other words, the first spiral segment extends 20 starting from an angle φ = φ _A0 = 0 ° up to an angle φ = φ _AE = 216 °. The wrap angle φ _Ages is thus 216 °.

Accordingly, the second spiral segment extends 22 in the circumferential direction of the turbine wheel 16 over its circumference with respect to the polar coordinate system over a wrap angle φ _Bges , which results from φ _BE - φ _B0 . In this case, φ _{B0 is} an initial _angle at which a spiral _{inlet cross-section} A _{sB0 of} the second spiral _segment 22 is arranged. Further, φ _{BE is} an end angle at which one end of the second spiral segment 22 is arranged. In other words, the second spiral segment extends 22 starting from an angle φ = φ _B0 = 216 ° up to an angle φ = φ _BE = 360 °. The wrap angle φ _Bges is thus 144 °.

The spiral segments 20 . 22 are at least partially fluidly separated from each other and arranged in the circumferential direction one behind the other, that is connected in series.

wobei A_sA ein Strömungsquerschnitt des ersten Spiralensegments 20 bei dem jeweiligen Winkel φ ist, und wobei exA ein Exponent ist, dessen Wert mindestens 2 beträgt. Vorzugsweise beträgt der Wert des Exponenten exA mindestens 4. Mit anderen Worten kann der Winkel φ Werte aus dem Bereich von einschließlich φ_A0 bis einschließlich φ_AE annehmen.Relative to the first spiral segment 20 is valid for at least one angle φ from a range of φ _A0 inclusive including φ _AE :

where A _{sA is} a flow cross-section of the first spiral _segment 20 at the respective angle φ, and where exA is an exponent whose value is at least 2. Preferably, the value of the exponent exA is at least 4. In other words, the angle φ may take values from the range of including φ _A0 to φ _AE inclusive.

wobei A_sB ein Strömungsquerschnitt des zweiten Spiralensegments 22 bei dem jeweiligen Winkel φ ist, und wobei exB ein Exponent ist, dessen Wert mindestens 2 beträgt. Vorzugsweise beträgt der Wert des Exponenten exA mindestens 4. Mit anderen Worten kann der Winkel φ Werte aus dem Bereich von einschließlich φ_B0 bis einschließlich φ_BE annehmen.Relative to the second spiral segment 22 applies to at least one angle φ from a range of including φ _B0 up to and including φ _BE :

where A _{sB is} a flow cross-section of the second spiral _segment 22 at the respective angle φ, and where exB is an exponent whose value is at least 2. Preferably, the value of the exponent exA is at least 4. In other words, the angle φ may take values from the range of including φ _B0 through φ _BE .

und somit einen jeweiligen, entsprechenden Spiralenverlauf auf, mittels welchem das Abgas besonders strömungsgünstig zum Turbinenrad 16 geführt werden kann. Ferner ist mittels der Turbine 10 eine besonders vorteilhafte Stoßaufladung durchführbar. Preferably, the respective value of the exponents exA, exB is at least 4, in particular at least 8. By this configuration of the spiral segments 20 . 22 these have a respective relative surface course

and thus a respective, corresponding spiral course, by means of which the exhaust particularly favorable flow to the turbine wheel 16 can be performed. Further, by means of the turbine 10 a particularly advantageous bump charging feasible.

The turbine 10 also has an adjustment 24 in the form of a so-called tongue slider, which two adjusting elements in the form of tongues 26 . 28 having. The tongue 26 is the first spiral segment 20 assigned while the second tongue 28 the second spiral segment 22 assigned. The tongues 26 . 28 are with a common ring 30 the tongue slider connected, the ring 30 around the axis of rotation 18 relative to the turbine housing 12 is rotatable. Because of the connection of the tongues 26 . 28 with the ring 30 become the tongues 26 . 28 when turning the ring 30 around the axis of rotation 18 relative to the turbine housing 12 around the axis of rotation 18 shifted, whereby respective, upstream of the turbine wheel 16 arranged and exhaust gas flow-through flow cross sections of the spiral segments 20 . 22 can be set variably.

About the flow cross sections, for example, that is the spiral segments 20 . 22 flowing exhaust gas into the receiving space 14 is insertable. In the present case, respective spiral inlet cross-sections of the spiral segments 20 . 22 by moving the tongues 26 . 28 set, wherein the spiral _{inlet cross sections} A _sA0 and A _sB0 refer to the maximum or maximum adjustable spiral _{inlet cross-sections} . These maximum spiral _{inlet cross-sections} A _sA0 and A _sB0 are thus set in a release position of the tongue _slide and are present by stationary, ie relative to the turbine housing 12 solid housing walls of the turbine housing 12 limited.

The tongue slider is a so-called variability of the turbine 10 created, whereby a variability of the swallowing ability and the swirl generation in front of the turbine wheel 16 is realized. This variability of Turbinenschluckfähigkeit and swirl generation in front of the turbine wheel 16 is governed by the present case simultaneously adjustable spiral inlet cross sections of the spiral segments 20 . 22 at respective tongue tips 32 . 34 the tongues 26 . 28 certainly.

The ring 30 is coupled to a controllable or controllable actuator, by means of which the ring 30 around the axis of rotation 18 can be turned. By adjusting the tongues 26 . 28 So is a spread in the spiral inlet cross section over the specified spiral course of an upper to a lower value by Flächenabgriff the tongue tips 32 . 34 accomplished.

The tongue slider or the adjustment 24 that is the tongues 26 . 28 are adjustable in an adjustment range, with the respective positions or positions of the tongues 26 . 28 is denoted or expressed by ε. The adjustment range extends from φ = ε = 0 ° to φ = ε = ε _max = ε _g .

When ε = 0 ° is the release position, which is a first end position in the form of an open position in which the respective flow cross-section is maximally released. This means that the open position is a first end position or end position of the adjusting device 24 is and that the flow cross sections in any other, belonging to the adjustment position of the adjustment 24 are released stronger or further, that is, have a greater value than in the open position.

At ε _max = ε _g is a second end position in the form of a closed position in which the respective flow cross-section is minimized or narrowed maximum. This means that the closed position has a second end position or an end position of the adjusting device 24 is and that the flow cross sections in any other, belonging to the adjustment position of the adjustment 24 are more reduced, that is, have a lower value than in the closed position. The adjustment range is limited by the end positions. This means that the adjusting device 24 no further than can be moved to the respective end positions.

Depending on the position of the tongue slider (adjusting device 24 ) results in an extension or shortening of the spiral segments 20 . 22 that are with the movement of the tongues 26 . 28 variable spiral inlet sections of the turbine 10 to lead.

The trained as a tongue slider turbine turbine 10 has a particularly high potential of relatively easy-to-modify parameters to the thermodynamic behavior of the turbine 10 targeted and manageable influence. With this feature, the tongue slide turbine is very suitable for the creation of modules or kits, which can be produced in a simple manner cost-effective series. In addition to common modifications of existing impellers in terms of TRIM (ratio of inlet diameter to the outlet diameter of the turbine wheel) and in terms of the inlet diameter provide tongue slide variations z. B. over their lengths in combination with the corresponding design of the spiral segments 20 . 22 a wide field to satisfy thermodynamic requirements advantageous and optimum adaptation of the turbine 10 to achieve the associated turbine.

aufgetragen. 2 shows a diagram 36 , on the abscissa 38 the angle φ is plotted. On the ordinate 40 is the respective above-mentioned area ratio

applied.

des ersten Spiralensegments 20 für unterschiedliche Werte des Exponenten exA, wobei die Kurve 1A den Verlauf des Flächenverhältnisses des ersten Spiralensegments 20 für den Exponenten exA = 1 veranschaulicht. Dementsprechend veranschaulicht die Kurve 2A den Verlauf des Flächenverhältnisses für den Exponenten exA = 2, die Kurve 3A für den Exponenten exA = 3, die Kurve 4A für den Exponenten exA = 4 und die Kurve 5A für den Exponenten exA = 5.Accordingly illustrate in the diagram 36 curves 42 respective courses of the area ratio

of the first spiral segment 20 for different values of the exponent exA, where the curve 1A the course of the area ratio of the first spiral segment 20 for the exponent exA = 1 illustrated. Accordingly, the curve illustrates 2A the course of the area ratio for the exponent exA = 2, the curve 3A for the exponent exA = 3, the curve 4A for the exponent exA = 4 and the curve 5A for the exponent exA = 5.

des zweiten Spiralensegments 22 für unterschiedliche Werte des Exponenten exB, wobei die Kurve 1B den Verlauf für exB = 1, die Kurve 2B den Verlauf für exB = 2, die Kurve 3B den Verlauf für exB = 3, die Kurve 4B den Verlauf für exB = 4 und die Kurve 5B den Verlauf für exB = 5 veranschaulicht. Die anhand der Kurven 42, 44 veranschaulichten, unterschiedlichen Flächenverläufe bzw. Spiralenverläufe ist zu entnehmen, wie stark auf die Sensibilität bzw. auf den Verstellbereich ε des Flächenabgriffs entlang des Spiralenverlaufs über die Spiralenflächen-Auslegung eingewirkt werden kann. Mittels der drehbaren Zungen 26, 28 über den Verstellbereich ε von beispielsweise 50°, so dass also ε_max 50° beträgt, erhält man bei einem zumindest im Wesentlichen linearen und durch die Kurve 1A veranschaulichten Standardverlauf des ersten Spiralensegments 20 eine Flächenabsenkung von etwa 22% der Spiralenquerschnittsfläche bezogen auf den Spiraleneintrittsquerschnitt A_sA0, d. h. bei maximalem Freigeben bzw. in Der Freigabestellung.Accordingly, curves illustrate 44 in the diagram 36 respective courses of the area ratio

of the second spiral segment 22 for different values of the exponent exB, where the curve 1B the course for exB = 1, the curve 2 B the course for exB = 2, the curve 3B the course for exB = 3, the curve 4B the course for exB = 4 and the curve 5B illustrates the history for exB = 5. The basis of the curves 42 . 44 illustrated, different surface curves or spiral curves can be seen how strong the sensitivity or on the adjustment range ε of the Flächenabgriffs along the spiral profile on the spiral surface design can be acted upon. By means of the rotatable tongues 26 . 28 over the adjustment range ε of, for example, 50 °, so that ε _{max is} 50 °, is obtained at an at least substantially linear and through the curve 1A illustrated standard course of the first spiral segment 20 a surface _reduction of about 22% of the spiral _{cross-sectional area} based on the spiral _{inlet cross-section} A _sA0 , ie at maximum release or in the release position.

The exponents exA and exB can be the same or different from each other. Likewise, the spiral _{inlet cross-sections} A _sA0 and A _{sB0 may be the} same or different from each other. In applications, for example for passenger cars with a high spreading requirement of the throughput parameter, exponents exA or exB of FIG. 6 can also be provided.

1A, min denotes a minimal spiral inlet cross-section, which in the end position ε _{max of} the tongue slider in the first spiral segment 20 is set with the exponent exA = 1. Correspondingly, denoted by 5A, min a minimum spiral inlet cross-section, which in the end position ε _{max of} the tongue slider (adjusting 24 ) at the first spiral segment 20 with exA = 5 is set.

Further, with 1B, min, a minimum spiral entrance cross-section of the second spiral segment 22 denotes, which in the end position ε _{max of} the tongue slider in the second spiral segment 22 is set with exB = 1. Accordingly, in 2 5B, min a minimum spiral inlet cross-section of the second spiral segment 22 designated, which in the end position ε _{max of} the tongue slider in the second spiral segment 22 with exB = 5 is set.

The described formula is preferably valid for a partial area of the extension, ie at least in a partial area of the respective wrap angle. Preferably, the respective formula is at least in a predominant partial area and in particular in the complete part of the extension of the respective spiral segment 20 . 22 realized.

3 shows a schematic representation of the internal combustion engine 48 , The internal combustion engine comprises a crankcase 11 with present six combustion chambers in the form of cylinders 13 . 15 , In the cylinders 13 . 15 is a respective piston relative to the corresponding cylinder 13 . 15 taken translationally movable. The pistons are via a respective connecting rod with an output shaft in the form of a crankshaft 17 the internal combustion engine 48 coupled so that the translational movements of the pistons in the cylinders 13 . 15 in an in 1 by a directional arrow 19 indicated rotational movement of the crankshaft 17 can be converted.

During a fired operation of the internal combustion engine 48 run in the cylinders 13 . 15 Combustion processes of a fuel-air mixture from which exhaust gas of the internal combustion engine 48 results. The exhaust gas is via an exhaust tract 21 the internal combustion engine 48 from the cylinders 13 . 15 dissipated. In the exhaust tract 21 is an exhaust element in the form of an exhaust manifold 27 arranged.

By means of the exhaust manifold 27 is the exhaust from the cylinders 13 to a first flood 23 the exhaust tract 21 merged. Further, by means of the exhaust manifold 27 the exhaust from the cylinders 15 to a second flood 25 the exhaust tract 21 merged. The floods 23 . 25 are formed, for example, by respective exhaust casings, each with the exhaust manifold 27 are fluidically connected.

In the exhaust tract 21 is also the turbine 10 as a first turbine of the exhaust gas turbocharger 46 arranged as the first exhaust gas turbocharger. Furthermore, in the exhaust tract 21 downstream of the first turbine 10 a second turbine 31 a second exhaust gas turbocharger 33 arranged. The flood 23 is fluidic with the spiral segment 20 connected, the tide 25 with the spiral segment 22 is fluidically connected. About the floods 23 . 25 can thus the turbine wheel 16 the exhaust gas are supplied so that the turbine wheel 16 can be driven by the exhaust gas.

That the turbine wheel 16 Driving exhaust gas is then the second turbine 31 the second exhaust gas turbocharger 33 fed. The second turbine 31 includes an in 3 unrecognizable, second turbine housing in which a second turbine wheel 39 the second turbine 31 around a rotation axis 41 rotatably received at least partially relative to the second turbine housing. The exhaust gas is the second turbine wheel 39 fed so that the downstream of the first turbine wheel 16 arranged, second turbine wheel 39 is driven by the exhaust gas. The turbines 10 . 31 are thus arranged one after the other, ie with respect to a flow direction of the exhaust gas through the exhaust gas tract 21 connected in series with each other.

The exhaust gas in the first tide 23 points upstream of the first turbine wheel 16 a pressure p ₃₁ which also acts as the first turbine inlet pressure or as the first total pressure at an inlet of the first turbine 10 referred to as. The exhaust gas in the second tide 25 Accordingly, has a pressure p ₃₂ , which also as the second turbine inlet pressure or as a second total pressure at the inlet of the first turbine 28 referred to as. Since the pressures p ₃₁ , p _{32 are} greater than one downstream of the turbine 10 and upstream of the turbine 31 prevailing pressure p ₄ , becomes the first turbine 10 also referred to as high-pressure turbine, while the second turbine 31 is referred to as a low-pressure turbine.

That's the first turbine wheel 16 Driving exhaust gas is due to this driving of the first turbine 10 Relaxed, leaving it downstream of the first turbine 10 and upstream of the second turbine 31 the pressure p ₄ , which with respect to the first turbine 10 Also referred to as turbine outlet pressure. Relative to the second turbine 31 the pressure p _{4 is} a turbine inlet pressure.

That the second turbine wheel 39 driving exhaust gas is released as a result of this driving, so that it is downstream of the second turbine wheel 39 has a pressure p ₅ . The pressure p ₅ is thus a turbine outlet pressure of the second turbine 31 ,

Downstream of the second turbine 31 is an exhaust aftertreatment device 62 in the exhaust tract 21 arranged. The exhaust aftertreatment device 62 may include a particulate filter and / or a catalyst such as an oxidation catalyst and / or an SCR (SCR) catalyst (Selective Catalytic Reduction).

The internal combustion engine 48 also has an intake tract 64 on, over which of the internal combustion engine 48 is supplied from this sucked air. In the intake tract 64 is an air filter 66 arranged to filter the sucked air. The in the intake tract 64 inflowing air has a pressure p ₁ .

The second turbocharger 33 has a compressor 68 with a compressor wheel 70 on. The compressor wheel 70 is non-rotatable with a shaft 72 the exhaust gas turbocharger 34 connected. With the wave 72 is also the second turbine wheel 39 rotatably connected. This allows the compressor wheel 70 from the turbine wheel 39 be driven and the internal combustion engine 48 compress air to be supplied. Due to the particularly efficient use of the energy contained in the exhaust gas through the turbine 31 can the compressor 68 be operated particularly efficiently, resulting in an efficient, fuel-efficient operation of the internal combustion engine 48 leads.

As a result of the compression of the air by the compressor 68 indicates the air downstream of the compressor 68 a pressure p _2N which is higher than the pressure p ₁ . Downstream of the compressor 68 is the compressor 73 the exhaust gas turbocharger 46 arranged. The compressor 73 includes the compressor wheel 74 , by means of which the means of the compressor 68 compressed air is to be further compressed. The compressors 68 . 73 are thus connected in series with each other.

Also the first turbine 10 allows the efficient use of energy contained in the exhaust gas, thereby also the compressor 73 can be driven efficiently. Starting from the pressure p _2N compresses the compressor 73 the air continues to a pressure p _2H .

This results in a pressure ratio π _{nd of} the compressor, which is also referred to as a low-pressure compressor 68 out:

Furthermore, this results in a pressure ratio π _{THD of} the compressor, which is also referred to as a high-pressure compressor 73 out:

As based on 3 is apparent, is downstream of the first compressor 68 and upstream of the other compressor 73 an intercooler 78 in the intake tract 64 arranged. By means of the intercooler 78 can the by means of the compressor 68 compressed and thus heated air to be cooled.

Also downstream of the other compressor 73 a radiator is arranged, which serves as intercooler 80 referred to as. The intercooler 80 is used to cool the through the compressor 68 . 72 compressed and thus heated air. By cooling the air by means of the intercooler 80 The degree of turbocharging of the air can be increased further, so that the air upstream of the cylinder 13 . 15 and downstream of the intercooler 80 has a pressure p _2s , which is also referred to as boost pressure. The air flows with this boost pressure into a charge air distributor 82 the intake tract 64 one from which the compressed air on the cylinders 13 . 15 is distributed.

Furthermore, the internal combustion engine 48 an exhaust gas recirculation device 84 with an exhaust gas recirculation line 86 on. The exhaust gas recirculation line 86 is on the one hand at a branch point 88 fluidly with the tide 23 and on the other hand at a feed point 90 fluidic with the intake tract 64 connected. This can by means of the exhaust gas recirculation line 86 at the junction 88 Exhaust from the tide 23 branched off, to the intake tract 64 recycled and at the feed point 90 in the intake tract 64 be initiated. The feeder 90 is also referred to as mixing point M, since there is the intake 64 flowing air with the recirculated exhaust gas mixes.

In the exhaust gas recirculation line 86 is an exhaust gas recirculation valve 92 arranged, by means of which a mass or amount of the recirculated exhaust gas is adjusted as needed. Downstream of the exhaust gas recirculation valve 92 is an exhaust gas recirculation cooler 94 arranged to cool the recirculating exhaust gas.

In the exhaust gas recirculation line 86 is downstream of the exhaust gas recirculation cooler 94 and upstream of the feed point 90 a pressure modulator 96 provided by means of which pressure oscillation excitations caused by exhaust pulsations of the internal combustion engine 48 , in the exhaust gas recirculation line 86 be modulated and reduced so far that in the area of the feed 90 no or only very small effective excitation intensities are no longer present. The pressure modulator 96 includes a damping volume 98 and an adapted effective and by a corresponding component, such as a diaphragm, formed Zuströmquerschnitt 100 and an adapted effective and by a corresponding component, such as a diaphragm, formed Abströmquerschnitt 102 , The inflow cross section 100 and the outflow cross section 102 cause in conjunction with the size of the damping volume 98 a strong damping of the pressure oscillation and thus the pressure pulsations at the feed point 90 ,

The first flood 23 is thus used in particular to divert exhaust from her and the intake system 64 recirculate. Therefore, the tide is 23 also known as AGR flood. In contrast, the second tide serves 25 in particular to set a predeterminable combustion air ratio λ, so that requested by the driver of the motor vehicle torques from the internal combustion engine 48 over her crankshaft 17 can be provided, so the flood 25 also referred to as λ-flood or lambda-flood. Therefore, the spiral segment belonging to the EGR flood becomes 20 Also referred to as EGR segment, where belonging to the lambda flood spiral segment 22 is called lambda segment.

The internal combustion engine 48 also has an arithmetic unit 104 for controlling and / or controlling the internal combustion engine 48 on. As in 3 indicated by dotted arrows, is the arithmetic unit 104 , which is, for example, a control unit, with the exhaust gas recirculation valve 92 connected to thereby adjust the amount or mass of the recirculated exhaust gas. The arithmetic unit 104 is also with the adjustment 24 the turbine 10 coupled.

Unlike turbine 10 in which a variable turbine geometry is created by the tongue slide, by means of which flow cross sections upstream of the turbine wheel 16 can be varied is the turbine 31 For example, designed as a solid geometry turbine, which has no variable turbine geometry. Through this by the adjustment 106 realized adjustability is an advantageous regulation or control of the internal combustion engine 48 in particular with regard to their two-stage turbocharger charge 33 . 46 realized. As a result, a very good response and thus a very good driving agility can be realized.

wobei m₃₁ den Abgasmassendurchsatz durch die Flut 24, T_t,31 die Totaltemperatur des Abgases am Eintritt der Turbine 10 und p_t,31 den Totaldruck am Eintritt der Turbine 10 bezeichnet. Der erste Durchsatzparameter Φ_T1,31 charakterisiert somit den Abgasdurchsatz durch die Flut 23 und somit durch das Spiralensegment 20.With Φ _T1.31 is in 3 a first flow rate parameter 23 designated. The first throughput _parameter Φ _T1 , ₃₁ results from:

where m _{31 is} the exhaust gas mass flow rate through the tide 24 , T _{t, 31} the total temperature of the exhaust gas at the inlet of the turbine 10 and p _{t, 31} the total pressure at the inlet of the turbine 10 designated. The first flow rate _parameter Φ _{T1, 31} thus characterizes the exhaust gas flow rate through the flood 23 and thus through the spiral segment 20 ,

wobei m₃₂ den Abgasmassendurchsatz durch die Flut 25, T_t,32 die Totaltemperatur des Abgases am Eintritt der Turbine 10 und p_t,32 den Totaldruck des Abgases in der Flut 25 am Eintritt der Turbine 10 bezeichnen. Der zweite Durchsatzparameter ΦT_1,32 charakterisiert somit den Abgasdurchsatz durch die Flut 25 und somit durch das Spiralensegment 22. Ferner ist in 1 mit Φ_T2,ATL ein dritter Durchsatzparameter der Turbine 31 bezeichnet.Correspondingly, a second throughput _parameter Φ _{T1, 32 results} :

where m _{32 is} the exhaust gas mass flow rate through the tide 25 , T _{t, 32} the total temperature of the exhaust gas at the inlet of the turbine 10 and p _{t, 32} the total pressure of the exhaust gas in the flood 25 at the entrance of the turbine 10 describe. The second flow rate parameter ΦT _1.32 thus characterizes the exhaust gas flow rate through the flood 25 and thus through the spiral segment 22 , Furthermore, in 1 with Φ _{T2, ATL} a third turbine throughput parameter 31 designated.

The throughput _parameters Φ _T1,31 , Φ _T1,32 may differ from each other especially in commercial vehicle _applications .

Order now a particularly efficient operation of the turbine 10 To create, it is provided that the spiral segments 20 . 22 are formed such that an Asymmetriegrad ASY, which is formed by a quotient of the flow rate parameters, when adjusting the adjustment 24 varies at least in a part of the adjustment. In other words, the degree of asymmetry ASY results in: ASY = PHI31 / PH132

With "PHI31" is the first flow rate _parameter Φ _{T1,31 of} the spiral _segment 20 with "PHI32" the second flow rate _parameter Φ _{T1,32 of} the flood 25 is designated.

4 shows a diagram 108 , on the abscissa 110 the wrap angle φ of the spiral segments 20 . 22 is plotted, wherein the wrap angle is also referred to as a circumferential angle. On the ordinate 112 are the respective cross-sectional areas of the spiral segments 20 . 22 applied. A course 114 illustrates the cross-sectional area profile of the lambda segment with exB, which is also referred to as ex32 and has the value 4. The tongue is related to φ 28 positioned in the open position at φ = 10 °. A Umblasebereich extends from φ = 10 ° to = 20 °. A course 116 illustrates the cross-sectional area profile of the EGR segment with exA, which is also referred to as ex31 and has the value 3. The tongue is related to φ 26 positioned in the open position at φ = 235 °. A Umblasebereich extends from φ = 245 ° to φ = 235 °.

A dashed course 118 illustrates the cross-sectional area profile of the lambda segment with exB = 6. A dashed curve 120 illustrates the cross-sectional area profile of the EGR segment with exB = 2 points 122 illustrate the center position of the tongue slider at φ = 40 ° and 265 °, respectively. Points 124 illustrate the closed position of the tongue slider at φ = 60 ° and 285 °.

5 shows a diagram 126 , on the abscissa 128 "Ε", that is the positions of the tongues 26 . 28 or the tongue slider is applied or are. A course 132 illustrates the progression of the overall turbine flow rate parameter 10 with exA = ex31 = 3 and exB = ex32 = 4 over the positions of the tongue slider. As a result, based on the history 132 be recognized how the overall flow rate parameter of the turbine 10 changed depending on the adjustment of the tongue slider. The same applies to one in the diagram 126 shown course 134 which, however, the course of the total flow rate parameter of the turbine 10 with exA = ex31 = 2 and exB = ex32 = 6 shows.

One to the course 132 belonging course 136 illustrates the course of the degree of asymmetry ASY at ex31 = 3 and ex32 = 4. In other words, based on the course 136 It can be recognized how the degree of asymmetry ASY changes when adjusting the tongue slider. Based on the course 136 It can be seen that the degree of asymmetry almost does not change at ex31 = 3 and ex32 = 4 when the tongue slider is adjusted. Out 5 It can also be seen that the adjustment range of the tongue slider is 50 degrees. The open position is thus at ε = 0 °, the closed position being ε = 50 °.

One to the course 134 belonging course 138 illustrates the course of the degree of asymmetry ASY at ex31 = 2 and ex32 = 6. Based on the course 138 It can be seen that the degree of asymmetry at ex31 = 2 and ex32 = 6 changes significantly when the tongue slider is adjusted. In the present case, the degree of asymmetry ASY increases when the tongue slider is moved in the direction of its closed position. Further, in the diagram 126 a Umblasebereich 140 registered, which extends from ε = 0 ° to ε = 10 °.

6 shows the diagram 126 with the courses 132 and 134 , Furthermore, gradients are in the diagram 142 and 144 registered, which to the course 132 belong. courses 146 and 148 belong to the course 134 , The history 142 illustrates the course of the first throughput parameter of the spiral segment 20 with ex31 = 3 depending on the adjustment of the tongue slider. The history 144 illustrates the course of the second throughput parameter PHI32 of the spiral segment 22 with ex32 = 4 depending on the Adjustment of the tongue slider. Based on the gradients 142 . 144 It can be seen that the throughput parameters PHI31 and PHI32 behave at least almost the same when adjusting the tongue slider, so that the curves 142 . 144 are parallel or their distance from each other at least almost unchanged.

The history 146 illustrates the course of the first throughput parameter of the spiral segment 20 with ex31 = 2 depending on the adjustment of the tongue slider. The history 148 illustrates the course of the second throughput parameter PHI32 of the spiral segment 22 with ex32 = 6 depending on the adjustment of the tongue slider. Based on the gradients 146 . 148 It can be seen that the throughput parameters PHI31 and PHI32 behave differently, so that when the tongue slide is moved in the direction of the closed position, the courses run towards one another and finally, in the closed position, open at a common point, that is, an intersection.

Here, the asymmetry factor ASY is proportional to As31 / As32 (spiral cross-section of the spiral segment 20 in relation to the spiral cross-section of the spiral segment 22 ). In other words:

Here, φ _31.0 denotes the beginning of the spiral segment 20 , φ _{31, E} the end of the spiral segment 20 , φ _33,0 the beginning of the spiral segment 22 , φ _{32, E} the end of the spiral segment 22 , A _s31,0 the cross-sectional area at the entrance of the spiral _segment 20 , and A _s32,0 the cross-sectional area at the entrance of the spiral _segment 22 , Further, φ is a running variable along the extent of each spiral _segment , that is, along the respective wrap angle, so that A _{s31 is} the sectional area of the spiral _{segment corresponding} to a respective value of φ 20 and A _{s32 are} the cross-sectional area of the spiral _{segment corresponding} to a respective value of φ 22 is. In other words, φ is the area tap angle of the respective tongue 26 , 28 from ε = 0 ° to ε _g .

A _s31 and A _s32 are usually tapped simultaneously when the tongues 26 . 28 be simultaneously rotated or moved, for example by means of a common actuator. Alternatively, it is conceivable that a first actuator for moving the tongue 26 and a second actuator for moving the tongue 28 is provided, so that the tongues 26 and 28 relative to each other and / or can be moved independently.

Furthermore, preferably: ΔPHI = phi3m (ε = 0 °) / phi3m (ε = ε _g)> 1.2

In particular: ΔPHI = phi3m (ε = 0 °) / phi3m (ε = ε _g)> 1.5

With "phi3m" is the overall throughput parameter of the turbine 10 designated.

Furthermore, preferably: ΔASY = ASY (ε = 0 °) / ASY (ε = ε _g ) <1.2

In particular: ΔASY = ASY (ε = 0 °) / ASY (ε = ε _g ) <0.8

The following is the turbine 10 with ex31 = 3 and ex32 = 4 as "first variant" and the turbine 10 with ex31 = 2 and ex32 = 6 referred to as "second variant". While the first variant is a high EGR capability of the internal combustion engine 48 generated, which is caused by the almost constant asymmetry factor ASY in the range 0.5, leads the second variant or the turbine housing 12 , which causes the asymmetry factor ASY to increase to a value of about 1, to a high lambda capability.

The first variant includes the turbine housing 12 which produces a nearly equal spiral area change of the EGR segment with respect to the lambda segment. Thus one becomes in the adjustment range of the turbine 10 can cause a very low NOx emission.

The turbine housing 12 on the other hand, the second variant, which performs a much stronger spiral surface taper of the lambda segment (the lambda spiral) in the closing action of the tongue slider against the relatively weak decrease of the EGR spiral surface, will cause an increase in the amount of air relative to the exhaust gas recirculation amount, thereby causing combustion the engine is favored in terms of consumption reduction. Furthermore, the use of the turbine housing of the second variant provides advantages in terms of engine agility, which will also gain in importance in commercial vehicle engines.

The exponents ex31 and ex32 represent essential geometry quantities for the asymmetry factor or degree of asymmetry and in the corresponding combinations make the desired behavior with regard to throughput parameter and asymmetry factor spreading over the course influence as the center of gravity.

It should be noted that when using the term "flow rate parameter" it is meant preferably the critical flow rate parameter, which is generally largely directly proportional to the geometric flow areas.

In the 3 The dual-segment variable-turbocharged two-stage turbocharger on the ATL high-pressure turbocharger could also be replaced with a one-stage supercharger, as the use of the spiral combination to influence the asymmetry factor is independent of this.

LIST OF REFERENCE NUMBERS

10

turbine

11

crankcase

12

turbine housing

13

cylinder

14

accommodation space

15

cylinder

16

turbine

17

crankshaft

18

axis of rotation

19

arrow

20

first spiral segment

21

exhaust tract

22

second spiral segment

23

first tide

24

tongue slide

25

second tide

26

tongue

27

exhaust manifold

28

tongue

30

ring

31

second turbine

32

tongue

33

second exhaust gas turbocharger

34

tongue

36

diagram

38

abscissa

39

second turbine wheel

40

ordinate

41

axis of rotation

42

curves

44

curves

46

turbocharger

48

Internal combustion engine

60

turbine

62

exhaust treatment device

64

intake system

66

air filter

68

compressor

70

compressor

72

wave

73

compressor

74

compressor

76

wave

78

intercooler

80

Intercooler

82

Charge-air distributor

84

Exhaust gas recirculation device

86

Exhaust gas recirculation line

88

branching point

90

induct

92

Exhaust gas recirculation valve

94

Exhaust gas recirculation cooler

96

pressure modulator

98

damping volume

100

inflow cross

102

outflow cross

104

computer unit

108

diagram

110

abscissa

112

ordinate

114

course

116

course

118

course

120

course

122

Point

124

Point

126

diagram

128

abscissa

130

ordinate

132

course

134

course

136

course

138

course

140

Umblasebereich

142

course

144

course

146

course

148

course

M

mixing point

p ₁

print

p _2N

print

p _2s

print

p ₃₁

print

p ₃₂

print

p ₄

print

p ₅

print

Φ _T1.31

first throughput parameter

Φ _T1,32

second throughput parameter

Φ _{T2, ATL}

third throughput parameter

1A

Curve

2A

Curve

3A

Curve

4A

Curve

5A

Curve

1B

Curve

2 B

Curve

3B

Curve

4B

Curve

5B

Curve

ε _max

end position

1A, min

minimum spiral inlet cross-section

1B, min

minimum spiral inlet cross-section

5A, min

minimum spiral inlet cross-section

5B, min

minimum spiral inlet cross-section

φ

angle

φ _A0

Starting angle

φ _AE

end angle

A _Ages

Wrap angle

φ _B0

Starting angle

φ _BE

end angle

_{B Bges}

Wrap angle

A _sA0

maximum spiral inlet cross section

A _sB0

maximum spiral inlet cross section

O

origin

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 19918232 A1 [0007]
• DE 102008039085 A1 [0008]
• US 2010/0196145 A1 [0009]
• US 2011/0243721 A1 [0010]

Claims (5)

Turbine ( 10 ) for an exhaust gas turbocharger of an internal combustion engine, with a turbine housing ( 12 ), which has a receiving space ( 14 ) for one about a rotation axis ( 18 ) relative to the turbine housing ( 12 ) rotatable turbine wheel ( 16 ) and at least two in the circumferential direction of the turbine wheel ( 16 ) extending over its circumference, at least partially fluidly separated from each other and circumferentially successively arranged spiral segments ( 20 . 22 ) for guiding the exhaust gas to the receiving space ( 14 ), and with an adjustable in an adjustment range ( 24 ), by means of which respective, upstream of the turbine wheel ( 16 ) and the spiral segments ( 20 . 22 ) associated flow cross sections are adjustable, wherein the spiral segments ( 20 . 22 ) each have a throughput of the exhaust gas through the respective spiral segment ( 20 . 22 ) throughput _parameters (Φ _T1 , ₃₁ , Φ _{T1, 32} ), characterized in that the spiral _segments ( 20 . 22 ) are formed such that an asymmetry _degree , which is formed by a quotient of the flow rate _parameters ((Φ _T1 , ₃₁ , Φ _{T1, 32} )), when adjusting the adjusting device ( _FIG . 24 ) varies at least in a part of the adjustment. Turbine ( 10 ) according to claim 1, characterized in that the degree of asymmetry varies in a range of from 0.3 to 1.2 inclusive. Turbine ( 10 ) according to claim 2, characterized in that the degree of asymmetry varies in a range of 0.3 to 0.8 inclusive. Turbine ( 10 ) according to any one of the preceding claims, characterized in that the part of the adjustment range extends from including a first position up to and including a second position of the adjusting device, wherein a further quotient of a first overall throughput parameter which the turbine ( 10 ) in the first position, and a second overall flow rate parameter of the turbine ( 10 ) the turbine ( 10 ) in the second position, greater than 1.2, in particular greater than 1.5, is. Turbine ( 10 ) according to one of the preceding claims, characterized in that the part of the adjustment range is a predominant part of the adjustment range, in particular the entire adjustment range.

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