DE102012016984B4 - Turbine for an exhaust gas turbocharger and internal combustion engine with such a turbine - Google Patents

Abstract

Turbine (10) for an exhaust gas turbocharger of an internal combustion engine, having a turbine housing (12) which has a receiving space (14) for a turbine wheel (16) which can be rotated about an axis of rotation (18) relative to the turbine housing (12) and at least two Spiral segments (20, 22) extending around the circumference of the turbine wheel (16) with respect to a polar coordinate system with origin (O) on the axis of rotation (18) in each case over a wrap angle (φAges, φBges)φE-φ0, which are fluidically separated from one another at least in some areas and are arranged one behind the other in the circumferential direction. for guiding the exhaust gas to the receiving space (14), wherein φ0 is a starting angle at which a respective spiral entry cross section As0 of the spiral segments (20, 22) is arranged, and φE is an end angle at which a respective end of the spiral segments (20, 22) is arranged , characterized in thatin relation to at least one of the spiral segments (20, 22) for all angles φ au s a range from φ0 to φE inclusive: AsAs0≤(1−(φ−φ0)(φE−φ0))exwhere- Ais a flow cross section of the at least one spiral segment (20, 22) at the respective angle φ, and- ex is an exponent is whose value is at least 2.

Description

The invention relates to a turbine for an exhaust gas turbocharger according to the preamble of patent claim 1 and an internal combustion engine with such a turbine.

It is known from the series production of passenger cars to use exhaust gas turbochargers with respective turbines in order to charge internal combustion engines for driving the passenger cars. In other words, the internal combustion engines are equipped with charging systems that include at least one exhaust gas turbocharger. The exhaust gas turbocharger is used to use 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, even internal combustion engines with relatively small stroke volumes, which are designed according to the so-called downsizing principle, can provide very high specific power and torque. Striving for the realization of particularly low emissions, in particular with regard to nitrogen oxide emissions (NO _x emissions) and soot emissions in the current development of charging systems, has a very strong influence on them.

Due to growing demands regarding the provision of boost pressure due to very high exhaust gas recirculation rates (EGR rates) to be realized, especially above the medium load range up to full load of the internal combustion engine, the flow cross sections through which exhaust gas can flow are becoming smaller and smaller in the turbines. Particularly high turbine outputs are thus realized by the representation of a particularly high accumulation capacity or by reducing the intake capacity of the turbines in interaction with the relevant internal combustion engine.

In addition, it is known to use soot filters in order to at least partially filter out soot particles from the exhaust gas of internal combustion engines. Such soot filters, which are arranged downstream of the turbines in an exhaust tract of the internal combustion engine, increase a respective inlet pressure level of the turbines as a result of a corresponding back pressure of the soot filters, which can make it necessary to further reduce the geometry of the turbines in order to meet the performance requirements on the compressor side for an air-exhaust gas - To be able to satisfy delivery. However, these geometric reductions are usually associated with only low efficiencies of the turbines.

It has been shown that the production of particularly high exhaust gas recirculation rates in connection with a necessary combustion air to be supplied for the internal combustion engine is problematic, particularly in the lower to medium operating or load ranges. With the usual design boundary conditions, which are also defined from the nominal point of the internal combustion engine on the gas exchange side or consumption side, the lower speed range of the internal combustion engine can only be served insufficiently in terms of air delivery in an asymmetric, double-flow fixed-geometry turbine, for example.

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 assigned separate exhaust gas lines to the turbine of the exhaust gas turbocharger, which can be fluidically connected or disconnected depending on the position of an actuator before entering the turbine. The actuator is designed as a slide bearing wall sections of the exhaust gas lines, with the movable wall sections being able to be brought into the closed position of the slide to separate the exhaust gas lines so that they cover fixed wall sections.

Of the DE 10 2008 039 085 A1 an internal combustion engine for a motor vehicle with an exhaust gas turbocharger can be seen as known. The exhaust gas turbocharger includes a turbine with a turbine housing, which has a receiving space for a turbine wheel that can rotate about an axis of rotation relative to the turbine housing. The turbine housing also has at least two spiral segments, which extend in the circumferential direction of the turbine wheel over its circumference with respect to a polar coordinate system originating on the axis of rotation, each over a wrap angle φ _E - φ ₀ , are fluidically separated from one another at least in some areas and are arranged one behind the other in the circumferential direction for guiding the exhaust gas to the has receiving space. In this case, φ ₀ is an initial angle at which a respective spiral entry cross section A _s0 of the spiral segments is arranged. Furthermore, φ _E is an end angle at which a respective end of the spiral segments is arranged.

From the U.S. 2010/0196145 A1 a turbocharger with a turbine is known, which has a turbine housing with a receiving space for a turbine wheel. Adjusting elements are provided upstream of the receiving space, which can be moved relative to the turbine housing and by means of wel At least one flow cross section of the turbine through which exhaust gas can flow is adjustable.

Furthermore, the DE 10 2010 053 951 A1 a turbine for an exhaust gas turbocharger can be seen as known. In addition, the DE 11 2010 003 626 T5 an exhaust gas supply device of a turbine wheel of an exhaust gas turbocharger.

Finally revealed the US 2011/0243721 A1 a turbine for an exhaust gas turbocharger, with a turbine housing, which has a receiving space for a turbine wheel, adjustment elements that can be moved relative to the turbine housing being provided upstream of the receiving space, by means of which at least one flow cross section of the turbine through which exhaust gas can flow can be variably adjusted.

In order to be able to advantageously set the ratio of the exhaust gas recirculation rates to the necessary air-fuel ratios in a particularly large operating range, a double-flow turbine type is advantageous, which is particularly pronounced in terms of shock charging capability, especially in a cylinder combination group. Turbines, which are designed in particular for pulse charging, have very large flow cross sections for using the greater usable exergy fluctuations or pressure pulsations of the exhaust gas of the internal combustion engine.

These high pressure pulsations of the internal combustion engine exist and occur at the turbine if the throttle and friction losses that usually occur at exhaust valves of the internal combustion engine in a manifold area upstream of the turbine are kept low by appropriate geometry design up to the turbine. This reduction in throttling and friction losses upstream of the turbine promotes the achievement of the objective of realizing a particularly pronounced impact charging, whereby an increase in the average overall efficiency of the exhaust gas exergy utilization is achieved despite large fluctuations in the turbine efficiency over time. A so-called multi-segment turbine, with the spiral segments mentioned at the outset arranged one behind the other in the circumferential direction, represents a very good starting point for realizing a particularly high degree of efficiency of the turbine.

It is therefore the object of the present invention to further develop a turbine for an exhaust gas turbocharger and an internal combustion engine for a motor vehicle with a turbine of the type mentioned at the outset in such a way that a particularly high degree of efficiency of the turbine can be achieved.

This object is achieved by a turbine having the features of patent claim 1 and by an internal combustion engine with such a turbine having the features of patent claim 7 . Advantageous configurations with expedient and non-trivial developments of the invention are specified in the remaining claims.

In order to create a turbine for an exhaust gas turbocharger of the type specified in the preamble of claim 1, in which a particularly high degree of efficiency can be achieved, it is provided according to the invention that, based on at least one of the spiral segments, for all angles φ from a range from φ ₀ to inclusive including φ _E applies: $$\frac{A_{\mathrm{<figure-callout\; id="0"\; label="s\; A\; s"\; filenames="DE102012016984B4\_0015.png"\; state="\{\{state\}\}">s</figure-callout>}}}{A_s}\le {\left(1-\frac{\left(\phi -{\phi }_0\right)}{\left({\phi }_E-{\phi }_0\right)}\right)}^{ex}$$

gehorcht. Weiterhin ist ex ein Exponent, dessen Wert mindestens 2 beträgt.In this case, A _s is a flow cross section of the at least one spiral segment at the respective angle φ. This means that the at least one spiral segment has an associated flow cross-section A _s at all angles φ from the range mentioned, through which exhaust gas can flow and the above-specified formula or condition $\frac{A_{\mathrm{<figure-callout\; id="0"\; label="s\; A\; s"\; filenames="DE102012016984B4\_0015.png"\; state="\{\{state\}\}">s</figure-callout>}}}{A_s}\le {\left(1-\frac{\left(\phi -{\phi }_0\right)}{\left({\phi }_E-{\phi }_0\right)}\right)}^{ex}$

obeys. Furthermore, ex is an exponent whose value is at least 2.

Due to the design of the at least one spiral segment according to the formula or condition given above, the at least one spiral segment has a corresponding surface profile and thus spiral profile starting from φ ₀ to φ _E , the exhaust gas flowing through the at least one spiral segment with regard to the realization of advantageous flow conditions is particularly advantageous. In other words, the exhaust gas flowing through the at least one spiral segment can be routed to the turbine wheel in a particularly advantageous manner in terms of flow technology, so that the exhaust gas can drive the turbine wheel very well. This results in efficient and therefore particularly efficient operation of the turbine.

Furthermore, the turbine according to the invention is designed particularly advantageously for carrying out pulse charging, so that high turbine outputs can be achieved by means of the turbine even at lower and medium speed and/or load ranges of the internal combustion engine. As a result, for example, a compressor of the exhaust gas turbocharger can be driven via the turbine with high power and the internal combustion engine thus supply a very high mass flow of compressed air even in the lower and middle speed and/or load ranges. As a result, the internal combustion engine can have a low swept volume and, at the same time, particularly high specific power and/or torques, so that the internal combustion engine can also be operated particularly efficiently and efficiently with only very low emissions and with only very low fuel consumption. In addition, the turbine according to the invention also makes it possible to realize particularly high exhaust gas recirculation rates, so that in particular the nitrogen oxide emissions (NO _x emissions) can be kept low.

It has proven particularly advantageous if the value of the exponent ex is at least 4, in particular at least 8. This leads to the realization of particularly high efficiencies of the turbine. Furthermore, as a result, a particularly high throughput spread can be realized, which is advantageous in particular in internal combustion engines for passenger cars and in particular in Otto engines. However, the turbine according to the invention can also easily be used in internal combustion engines for commercial vehicles and in diesel engines, diesel gasoline engines and/or other internal combustion engines.

The value of the exponent ex can advantageously also be 7 or 8, which is particularly advantageous when the turbine is used in passenger cars. Such high values of the exponent ex make it possible to achieve a particularly high level of efficiency and a particularly high spread of throughput.

In a further advantageous embodiment of the invention, the above formula or condition applies to both spiral segments. In other words, both spiral segments or both spiral courses of the spiral segments are designed according to the above formula, as a result of which a particularly high level of efficiency can be achieved.

It has proven to be advantageous if the respective exponents ex of the spiral segments differ from one another, with both exponents having at least the value 2, in particular at least the value 4 and in particular the value 8. As a result, the spiral segments can be designed as required and, for example, adapted to different purposes. One of the spiral segments can be designed, for example, to provide a predeterminable combustion air ratio A, while the other spiral segment is designed, for example, to realize particularly high exhaust gas recirculation rates (EGR rates).

Accordingly, it can advantageously be provided that the respective spiral entry cross sections A _s0 of the spiral segments differ from one another, so that the spiral segments can be designed as required. As a result of the configuration of the spiral segments according to the above formula, the exhaust gas can flow through them in a particularly advantageous manner.

In a particularly advantageous embodiment of the invention, at least one adjusting device is provided, by means of which at least one flow cross section of the turbine through which exhaust gas can flow and which is arranged upstream of the turbine wheel can be adjusted. As a result, the turbine can be adapted as required to different mass flows of the exhaust gas, which occur, for example, in different speed and/or load ranges of the internal combustion engine, and can thus be operated particularly efficiently.

It has been shown to be particularly advantageous if at least one adjustment element of the adjustment device is assigned to the spiral segments, by means of which at least one respective flow cross section through which the exhaust gas can flow of the respective spiral segment can be adjusted. As a result, particularly high throughput spreads of the turbine can be achieved. Furthermore, the respective flow cross sections of the spiral segments can be adjusted as required.

In order to achieve particularly high throughput spreads of the turbine in a particularly cost-effective manner, it is provided in a further embodiment of the invention that the adjusting elements are displaceable in the circumferential direction of the turbine wheel over its circumference at least in regions relative to the turbine housing about a pivot axis, in particular about the axis of rotation. The turbine or the adjusting device therefore also has a very high level of robustness.

The adjusting device is thus designed as a so-called tongue slide, the adjusting elements of which are blocking bodies which can be designed at least essentially in the shape of a wing in their cross section. As a result, the respective inlet cross section A _s and/or a respective nozzle cross section of the spiral segments can be adjusted, for example, by moving the adjustment elements relative to the turbine housing.

The invention also includes an internal combustion engine for a motor vehicle with a Exhaust tract, in which a turbine according to one of the preceding claims is arranged. Advantageous configurations of the turbine according to the invention are to be regarded as advantageous configurations of the internal combustion engine according to the invention and vice versa. By means of the turbine, the internal combustion engine can be charged particularly efficiently by pulse charging, so that on the one hand energy contained in the exhaust gas of the internal combustion engine can be used particularly well by the turbine and on the other hand a compressor of the exhaust gas turbocharger can also be used in the lower and middle speed and/or load ranges to drive high performance. As a result, the internal combustion engine can also be very well supplied with compressed air in the lower and middle speed and/or load ranges and can therefore be operated efficiently.

Further advantages, features and details of the invention result from the following description of a preferred exemplary embodiment and from the drawing. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and/or shown alone in the figures can be used not only in the combination specified in each case, but also in other combinations or on their own, without going beyond the scope of the leave invention.

• 1 eine schematische Querschnittsansicht einer Turbine eines Abgasturboladers für eine Verbrennungskraftmaschine, mit zwei Spiralensegmenten;
• 2 ein Diagramm zur Veranschaulichung von relativen Flächenverläufen und somit von Spiralenverläufen unterschiedlicher Ausführungsformen der Spiralensegmente.

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 to illustrate relative surface courses and thus spiral courses of different embodiments of the spiral segments.

1 shows a turbine 10 for an exhaust gas turbocharger of a motor vehicle internal combustion engine designed as a reciprocating piston internal combustion engine. The exhaust gas turbocharger also includes an in 1 not recognizable compressor, by means of which the internal combustion engine to be supplied air is to be compressed. In this case, the compressor can be driven by the turbine 10 .

The turbine 10 includes a turbine housing 12 which has a receiving space 14 for a turbine wheel 16 of the turbine 10 . The turbine wheel 16 is accommodated at least in regions in the accommodation space 14 and is rotatable about an axis of rotation 18 relative to the turbine housing 12 .

By means of the turbine housing 12, exhaust gas from the internal combustion engine is conducted to the turbine wheel 16, which the exhaust gas flows against and is driven by. The turbine wheel 16 is equipped with an in 1 not shown shaft of the exhaust gas turbocharger rotatably connected. A compressor wheel of the compressor is also connected to this shaft. The compressor wheel is accommodated in a compressor housing of the compressor so as to be rotatable about the axis of rotation 18 relative to the compressor housing and can be driven by the turbine wheel 16 as a result of the non-rotatable connection to the shaft. The air to be supplied to the internal combustion engine is compressed by means of the compressor wheel. Energy contained in the exhaust gas of the internal combustion engine can thus be used by means of the exhaust gas turbocharger in order to compress the air.

In the present case, the turbine 10 is designed as a so-called multi-segment turbine. In this case, the turbine housing 12 has a first spiral segment 20 and a second spiral segment 22 . The first spiral segment 20 extends in the circumferential direction of the turbine wheel 16 over its circumference with respect to a polar coordinate system with the origin O on the axis of rotation 18 over a wrap angle φ _Ages . The angle of wrap 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 entry cross section A _sA0 of the first spiral segment 20 is arranged. Furthermore, φ _AE is an end angle at which an end of the first spiral segment 20 is located. The angle of wrap φ _Ages of the first spiral segment 20 is at least essentially 216° in the present case. In other words, the first spiral segment 20 extends from an angle φ=φ _A0 =0° to an angle φ=φ _AE =216°. The wrap angle φ _Ages is therefore 216°.

Correspondingly, the second spiral segment 22 extends 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 entry cross section A _sB0 of the second spiral segment 22 is arranged. Further, φ _BE is an end angle at which an end of the second spiral segment 22 is located. In other words, the second spiral segment 22 extends from an angle φ=φ _B0 =216° to an angle φ=φ _BE =360°. The wrap angle φ _Bges is therefore 144°.

The spiral segments 20, 22 are at least partially fluidic from each other arranged separately and one behind the other in the circumferential direction, ie 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. Mit anderen Worten kann der Winkel φ Werte aus dem Bereich von einschließlich φ_A0 bis einschließlich φ_AE annehmen.In relation to the first spiral segment 20, the following applies to all angles φ from a range from φ _A0 inclusive to φ _AE inclusive: $$\frac{A_s}{A_{s\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="DE102012016984B4\_0015.png"\; state="\{\{state\}\}">A</figure-callout>}0}}\le {\left(1-\frac{\left(\phi -{\phi }_{A0}\right)}{\left({\phi }_{AE}-{\phi }_{A0}\right)}\right)}^{exA}$$

where A _sA is a flow area of the first volute segment 20 at the respective angle φ, and where exA is an exponent whose value is at least 2. In other words, the angle φ can assume values from the range from φ _A0 inclusive 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. Mit anderen Worten kann der Winkel φ Werte aus dem Bereich von einschließlich φ_B0 bis einschließlich φ_BE annehmen.In relation to the second spiral segment 22, the following applies to all angles φ from a range from φ _B0 inclusive to φ _BE inclusive: $$\frac{A_{sB}}{A_{s\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="DE102012016984B4\_0015.png"\; state="\{\{state\}\}">B</figure-callout>}0}}\le {\left(1-\frac{\left(\phi -{\phi }_{AB0}\right)}{\left({\phi }_{BE}-{\phi }_{B0}\right)}\right)}^{exAB}$$

where A _sB is a flow area of the second volute segment 22 at the respective angle φ, and where exB is an exponent whose value is at least 2. In other words, the angle φ can assume values from the range from φ _B0 inclusive to φ _BE inclusive.

bzw. $\frac{A_{sB}}{A_{sB0}}$

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.The respective value of the exponents exA, exB is preferably at least 4, in particular at least 8. Due to this configuration of the spiral segments 20, 22, they each have a relative surface profile $\frac{A_{sA}}{A_{s\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="DE102012016984B4\_0015.png"\; state="\{\{state\}\}">A</figure-callout>}0}}$

or. $\frac{A_{sB}}{A_{s\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="DE102012016984B4\_0015.png"\; state="\{\{state\}\}">B</figure-callout>}0}}$

and thus a respective, corresponding spiral course, by means of which the exhaust gas can be guided to the turbine wheel 16 in a particularly streamlined manner. Furthermore, a particularly advantageous impact charging can be carried out by means of the turbine 10 .

The turbine 10 also has an adjusting device 24 in the form of what is known as a tongue slide, which has two adjusting elements in the form of tongues 26 , 28 . The tongue 26 is assigned to the first spiral segment 20 while the second tongue 28 is assigned to the second spiral segment 22 . The tongues 26, 28 are connected to a common ring 30 of the tongue slide 24, the ring 30 being rotatable about the axis of rotation 18 relative to the turbine housing 12. Due to the connection of the tongues 26, 28 to the ring 30, the tongues 26, 28 are displaced relative to the turbine housing 12 about the axis of rotation 18 when the ring 30 rotates about the axis of rotation 18, as a result of which flow cross-sections that are arranged upstream of the turbine wheel 16 and through which exhaust gas can flow the spiral segments 20, 22 can be variably adjusted. In the present case, the respective spiral entry cross-sections of the spiral segments 20, 22 are adjusted by moving the tongues 26, 28, the spiral entry cross-sections A _sA0 and A _sB0 relating to the maximum or maximum adjustable spiral entry cross-sections. These maximum spiral entry cross sections A _sA0 and A _sB0 are thus set in a release position of tongue slide 24 and are presently delimited by stationary housing walls of turbine housing 12 , ie fixed housing walls relative to turbine housing 12 .

A so-called variability of the turbine 10 is created by the tongue slide 24 , as a result of which a variability of the intake capacity and the generation of swirl in front of the turbine wheel 16 is realized. This variability of the turbine absorption capacity and swirl generation in front of the turbine wheel 16 is decisively determined by the simultaneously adjustable spiral entry cross sections of the spiral segments 20, 22 at the respective tongue tips 32, 34 of the tongues 26, 28.

The ring 30 is coupled to an adjustable or controllable actuator, by means of which the ring 30 can be rotated about the axis of rotation 18 . By adjusting the tongues 26, 28, a spread in the spiral entry cross-section over the fixed course of the spiral from an upper to a lower value is brought about by surface tapping of the tongue tips 32, 34.

The tongues 26, 28 can be adjusted in an adjustment range ε, which extends from φ=0° to φ=ε _max . ε _max is therefore an end position in which the tongue slide 20 is in a maximum closed position. In this maximum closed position, the respective spiral entry cross sections are narrowed to the maximum.

Depending on the position of the tongue slide 24, the volute segments 20, 22 are lengthened or shortened, which leads to the volute inlet cross-sections of the turbine 10, which can be changed with the movement of the tongues 26, 28.

The turbine 10 designed as a tongue valve turbine has a particularly high potential for parameters that are relatively easy to modify in order to influence the thermodynamic behavior of the turbine 10 in a targeted and manageable manner. With this property, the tongue valve turbine is very suitable for the creation of modules or construction kits with which inexpensive series can be easily produced. In addition to common modifications of existing wheels with regard to TRIM (ratio of one outlet diameter to the outlet diameter of the turbine wheel) and with regard to the inlet diameter, tongue slide variations, e.g. over their lengths in combination with the corresponding design of the spiral segments 20, 22, offer a wide range to advantageously satisfy thermodynamic requirements and an optimal adaptation of the turbine 10 to the associated turbine achieve.

und $\frac{A_{sB}}{A_{sB0}}$

aufgetragen. 2 shows a diagram 36, on whose abscissa 38 the angle φ is plotted. On the ordinate 40 is the respective area ratio mentioned above $\frac{A_{sA}}{A_{s\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="DE102012016984B4\_0015.png"\; state="\{\{state\}\}">A</figure-callout>}0}}$

and $\frac{A_{sB}}{A_{s\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="DE102012016984B4\_0015.png"\; state="\{\{state\}\}">B</figure-callout>}0}}$

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.Correspondingly, curves 42 in diagram 36 illustrate the respective courses of the area ratio $\frac{A_{sA}}{A_{s\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="DE102012016984B4\_0015.png"\; state="\{\{state\}\}">A</figure-callout>}0}}$

of the first spiral segment 20 for different values of the exponent exA, the curve 1A illustrating the course of the area ratio of the first spiral segment 20 for the exponent exA=1. Accordingly, curve 2A illustrates the course of the area ratio for the exponent exA = 2, curve 3A for the exponent exA = 3, curve 4A for the exponent exA = 4 and 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.Correspondingly, curves 44 in diagram 36 illustrate respective courses of the area ratio $\frac{A_{sB}}{A_{s\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="DE102012016984B4\_0015.png"\; state="\{\{state\}\}">B</figure-callout>}0}}$

of the second spiral segment 22 for different values of the exponent exB, curve 1B showing the profile for exB=1, curve 2B the profile for exB=2, curve 3B the profile for exB=3, curve 4B the profile for exB= 4 and curve 5B illustrates the course for exB=5. The different surface courses or spiral courses illustrated by the curves 42, 44 show how strongly the sensitivity or the adjustment range ε of the surface tap along the course of the spiral can be influenced by the spiral surface design. By means of the rotatable tongues 26, 28 over the adjustment range ε of, for example, 50°, so that ε _max is 50°, a surface reduction of about 22% is obtained with an at least essentially linear standard course of the first spiral segment 20 illustrated by curve 1A. the spiral cross-sectional area related to the spiral entry 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 entry cross sections A _sA0 and A _sB0 can be the same or different from one another. In the case of applications, for example for passenger cars, with a high spread requirement for the throughput parameter, exponents exA or exB of 6 can also be provided.

1A, min denotes a minimum spiral entry cross section, which is set in the end position ε _max of the tongue slide 24 in the first spiral segment 20 with the exponent exA=1. Correspondingly, 5A, min designates a minimum spiral entry cross section, which is set in the end position ε _max of the tongue slide 24 in the first spiral segment 20 with exA=5.

Furthermore, 1B,min denotes a minimum spiral entry cross section of the second spiral segment 22, which is set in the end position ε _max of the tongue slide 24 in the second spiral segment 22 with exB=1. Accordingly, in 2 5B, min designates a minimum spiral entry cross section of the second spiral segment 22, which is set in the end position ε _max of the tongue slide 24 in the second spiral segment 22 with exB=5.

The formula described is preferably valid for a portion of the extension, i.e. at least in a portion of the respective angle of wrap. The respective formula is preferably implemented at least in a predominant part area and in particular in the complete part of the extension of the respective spiral segment 20, 22.

Reference List

10

turbine

12

turbine housing

14

recording room

16

turbine wheel

18

axis of rotation

20

first spiral segment

22

second spiral segment

24

tongue shifter

26

Tongue

28

Tongue

30

ring

32

tongue tip

34

tongue tip

36

diagram

38

abscissa

40

ordinate

42

curves

44

curves

1A

Curve

2A

Curve

3A

Curve

4A

Curve

5A

Curve

1B

Curve

2 B

Curve

3B

Curve

4B

Curve

5B

Curve

ε max

final position

1A, minimum

minimum spiral entry cross-section

1B, min

minimum spiral entry cross-section

5A, minimum

minimum spiral entry cross-section

5B, min

minimum spiral entry cross-section

φ

angle

φA0

starting angle

φAE

end angle

φAges

Wrap angle

φB0

starting angle

φBE

end angle

φBtotal

Wrap angle

AsA0

maximum spiral entry cross-section

AsB0

maximum spiral entry cross-section

O

origin

Claims (7)

Turbine (10) for an exhaust gas turbocharger of an internal combustion engine, having a turbine housing (12) which has a receiving space (14) for a turbine wheel (16) which can be rotated about an axis of rotation (18) relative to the turbine housing (12) and at least two turbine wheel (16) over its circumference with respect to a polar coordinate system with origin (O) on the axis of rotation (18) each extending over a wrap angle (φ _Ages ,φ _Bges )φ _E -φ ₀ , at least in some areas fluidically separated from one another and arranged one behind the other in the circumferential direction (20, 22) for guiding the exhaust gas to the receiving space (14), where φ ₀ is an initial angle at which a respective spiral entry cross section A _s0 of the spiral segments (20, 22) is arranged, and φ _E is an end angle at which a respective end of the spiral segments (20, 22) is arranged, characterized in that based on at least one of the spiral segments (20, 22) for all angles φ from a range from φ ₀ up to and including φ _E applies: $$\frac{A_s}{A_{s0}}\le {\left(1-\frac{\left(\phi -{\phi }_0\right)}{\left({\phi }_E-{\phi }_0\right)}\right)}^{ex}$$

where - A _s is a flow area of the at least one spiral segment (20, 22) at the respective angle φ, and - ex is an exponent whose value is at least 2. Turbine (10) after claim 1 , characterized in that the value of the exponent ex is at least 4, in particular at least 8. Turbine (10) according to one of Claims 1 or 2 , characterized in that both spiral segments (20, 22) according to the condition $\frac{A_s}{A_{s0}}\le {\left(1-\frac{\left(\phi -{\phi }_0\right)}{\left({\phi }_E-{\phi }_0\right)}\right)}^{ex}$

are configured, the respective exponents ex of the spiral segments (20, 22) differing from one another and/or the respective spiral entry cross sections A _s0 of the spiral segments (20, 22) differing from one another. Turbine (10) according to one of the preceding claims, characterized in that at least one adjustment device (24) is provided, by means of which at least one flow cross section of the turbine (10) through which exhaust gas can flow and which is arranged upstream of the turbine wheel (16) can be adjusted. Turbine (10) after claim 4 , characterized in that the spiral segments (20, 22) are each assigned at least one adjusting element (26, 28) of the adjusting device (24), by means of which at least one respective flow cross section through which exhaust gas can flow of the respective spiral segment (20, 22) can be adjusted. turbine after claim 5 , characterized in that the adjusting elements (26, 28) in the circumferential direction of the turbine wheel (16) on the sen circumference are at least partially displaceable relative to the turbine housing (12) about a pivot axis, in particular about the axis of rotation (18). Internal combustion engine for a motor vehicle, with an exhaust tract in which at least one turbine (10) according to one of the preceding claims is arranged.

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