WO2010063518A1

WO2010063518A1 - Geometric design of rotor blades of a turbocharger

Info

Publication number: WO2010063518A1
Application number: PCT/EP2009/064141
Authority: WO
Inventors: Andre Kaufmann; Michael Klaus; Florian Kronschnabl
Original assignee: Continental Automotive Gmbh
Priority date: 2008-12-01
Filing date: 2009-10-27
Publication date: 2010-06-10
Also published as: DE102008059874A1

Abstract

The invention relates to a blade (16) of a rotor (14) of a turbocharger: wherein the blade has a non-linear reduction of the axial length at least in one or more sections on the trailing edge (24, 30) thereof in the meridional view in the case of a turbine blade, or the leading edge thereof in the case of a compressor blade, and wherein the respective section and the reduction of the axial length of the blade is selected such that the blade has a predetermined ratio of natural frequencies and an efficiency loss of the blade or rotor.

Description

description

Geometrical design of the impeller blades of a turbocharger

The invention relates to a blade or the blading for an impeller of a turbocharger, for example for a turbine impeller or a compressor impeller.

A turbocharger generally has a turbine and a turbine

Compressor on. The impeller of the turbine is in this case driven by the exhaust gas mass flow and in turn drives an impeller of the compressor, which compresses fresh air and an internal combustion engine feeds. Both wheels are arranged here on a common shaft. For example, if the wheels are not precisely balanced, unwanted vibrations may occur.

Furthermore, for example, turbine blades in turbochargers are subject to excitation by pressure pulsations or periodic pressure fluctuations due to a non-symmetrical inflow geometry. In order to prevent failure due to blade fractures, it is therefore necessary to design the impellers in a turbocharger so that the natural frequencies are well above the excitation frequencies. One way to increase the natural frequency is to reduce the axial extent of the blades on the housing contour.

From the prior art, it has hitherto been known to provide turbines with a linearly recessed trailing edge (in the meridional view).

Accordingly, it is the object of the present invention to provide an improved blade geometry for a turbocharger.

This object is achieved by a blade having the features of patent claim 1 or 2. According to the invention, a blade of an impeller of a turbocharger is provided, wherein the blade in the meridional view at a turbine blade at its trailing edge and at a compressor wheel blade at its leading edge at least in one or more sections or areas a non-linear reduction of the axial Length, and wherein the respective portion and the extent of the reduction of the axial length of the blade is selected such that the blade has a predetermined ratio between natural frequencies and the efficiency loss of the blade or the impeller from the axial reduction of the Shovel results, preferably with the highest possible natural frequencies at the lowest possible loss of efficiency of the blade or the impeller are sought.

So far, only blades are known from the prior art whose trailing edge in the meridional view either perpendicular (see Fig. 1), resulting in low natural frequencies, or blades with a linear reduction of the axial length over the entire trailing edge, such as in the following Fig. 2 is shown. Although such blades have higher natural frequencies but for a worse efficiency of the associated impeller. The blade according to the invention has the advantage over that it provides a blade with an optimal ratio of natural frequencies and efficiency of the blade or the impeller by suitably adjusting the trailing edge in the turbine blade or the leading edge of the compressor blade and the axial length of the blade at the exit edge or entry edge in at least one or more suitable sections or areas nonlinear reduced. In other words, the exit edge of a turbine wheel blade runs in the section in the form of a curve backwards against the flow direction in order to increase the natural frequencies without excessively reducing the efficiency, as in the example in the following FIG A compressor impeller, the leading edge in the section in the form of a curve runs rearwardly in the flow direction in order to increase the natural frequencies without reducing the efficiency too much.

Furthermore, according to the invention, there is provided a blade of an impeller of a turbocharger, wherein the blade of the impeller, i. the turbine wheel blade is reduced at its outlet edge or the compressor wheel blade at its inlet edge in a first, upper region in the axial length and wherein the outlet edge in a second, lower region perpendicular, substantially perpendicular or rearward, against the flow direction runs or in which the leading edge extends in a second, lower region perpendicular, substantially perpendicular or rearward, in the flow direction, so that the loss of efficiency of the impeller does not exceed a predetermined limit value or is within a predetermined tolerance range.

The blade of an impeller of a turbocharger has the advantage, in contrast to the blades, as they are known from the prior art, that the blade according to the invention is shortened in the first axial length in the first, upper area, in order hereby the Natural frequencies of the impeller suitable to increase. In the second, lower area, on the other hand, there is no shortening of the axial length of the blade, for the purpose of increasing its natural frequencies. In other words, either no reduction of the axial length of the blade takes place in the second, lower region, so that the outlet edge or inlet edge runs vertically here. Alternatively, only a relatively slight reduction of the axial length of the blade takes place, with the reduction of the axial length of the blade taking place only to such an extent that the efficiency loss of the impeller is restricted or preferably minimized to a predetermined permissible range. It is generally desirable to To keep the loss of efficiency as small as possible and at the same time to obtain sufficiently high natural frequencies of the impeller to counteract harmful resonances.

By dividing the blade into, for example, at least two regions or the configuration of these two regions, the invention allows a suitable optimum for the ratio of natural frequencies and efficiency of the impeller to be achieved. The upper and / or lower area can be shortened so that at most a certain loss of efficiency occurs. In this case, for example, the lower region can be shortened less than the upper region in order to minimize the loss of efficiency. Both the upper region and the lower region are relevant for the loss of efficiency.

For example, a reduction of the axial length in the lower region and / or upper region can only take place as far as there is no loss of efficiency of the impeller of, for example, greater than 1%. This value of 1% is exemplary and the invention is not limited thereto. Basically, any other value can be selected which is greater or less than 1%, depending on the function and purpose of the impeller or its blades.

Advantageous embodiments and modifications of the invention will become apparent from the dependent claims and the description with reference to the drawings.

In one embodiment according to the invention, the trailing edge (turbine wheel blade) of the blade within the first, upper region and / or the second, lower region is continuously curved or at least partially curved back against the flow direction. In the compressor blade, the leading edge within the first, upper, and / or second, lower regions is continuously curved or at least partially curved rearwardly in the flow direction. Due to the curvature or partly curved tion of the trailing edge or leading edge in the first, upper region to the rear against the flow direction or to the rear in the flow direction, the natural frequencies of the blade or the impeller can be increased. A curvature or partial curvature of the trailing edge or leading edge in the second, lower region also leads to an additional, albeit minor, increase in the natural frequencies, but the curvature or partial curvature is limited to such an extent that the efficiency of the associated impeller does not decreases over a predetermined amount.

In a further embodiment according to the invention, the trailing edge (turbine wheel blade) of the blade within the first, upper region and / or the second, lower region is bent back towards the direction of flow. In the compressor impeller, the leading edge within the first, upper region and / or the second, lower region is bent backwards in the flow direction. In this case, the trailing edge or leading edge has the form of a continuous straight line in the first, upper region or second, lower region, for example, or has at least one or more rectilinear sections. Similarly as described above, the bending of the trailing edge towards the rear, contrary to the flow direction or at the entry edge to the rear in the direction of flow, causes an increase in the natural frequencies of the blade or the impeller. In this case, however, the second, lower region is bent less or curved in the direction of the turbine blade back against the flow direction or in the Verdichterrad- geschaufei curved backwards in the flow direction than the first, upper region in order not to reduce the efficiency of the impeller too strong or to a predetermined extent.

According to a further embodiment of the invention, at least the transition between the first, upper region and the second, lower region of the outlet edge (turbine wheel blade) or the leading edge (compressor wheel blade) preferably rounded. This is both thermodynamic and structural-mechanical as well as from a manufacturing point of view more advantageous over a sharp bend as a transition.

In one embodiment according to the invention, the trailing edge (turbine wheel blade) or leading edge (compressor wheel blade) of the blade has an S-shape or the first, upper region and the second, lower region of the outlet edge or inlet edge together form an S-shape , The S-shape is advantageous especially with respect to mechanical stresses which can occur in the blade. In the embodiment according to the invention, the upper part of the S-shape is, for example, convex or arched outwards, and the lower part of the S-shape is concave or arched inwards. As a result, higher natural frequencies of the blade or the impeller can be achieved, in comparison to a blade having a vertical trailing edge or leading edge.

According to a further embodiment of the invention, the blade is a blade of a turbine wheel and / or a compressor wheel, for example a radial turbine or a radial compressor. The blade can be produced by casting (metal casting) and / or milling. In other words, a casting mold can be produced in which the trailing edge (turbine wheel blade) or leading edge (compressor wheel blade) of the blade already has the finished or substantially finished shape. Alternatively, the blade can also be milled as a whole or by means of

Milling the contour of the trailing edge or the leading edge are formed according to the invention.

In the case of a turbine wheel or compressor wheel of a turbocharger, in this case at least one, several or all blades may be formed according to the blade according to the invention. This has the advantage that due to the high natural frequencies of the respective impeller, which are higher than the excitation frequency of the impeller, the occurrence of unwanted, harmful resonances can be prevented.

The invention is explained in more detail below with reference to the exemplary embodiments indicated in the schematic figures of the drawings. Show it:

1 is a meridional view of a turbine comprising the turbine housing and the turbine runner, which has prior art blades;

FIG. 2 is a meridional view of a turbine comprising the turbine housing and the turbine runner having rotor blades according to another embodiment of the prior art; FIG.

3 shows a meridional view of a turbine comprising the turbine housing and the turbine runner, which has rotor blades according to a first embodiment of the invention, compared to an embodiment according to the prior art;

4 is a meridional view of a turbine comprising the turbine housing and the turbine runner having blades according to a second embodiment of the invention compared to the embodiment described in FIG. 3; and

5 is a meridional view of a turbine comprising the turbine housing and the turbine runner having blades according to a third embodiment of the invention compared to a prior art embodiment.

In all figures, identical or functionally identical elements and devices have been provided with the same reference numerals, unless stated otherwise. The following figures depict a turbine with a turbine housing and a turbine wheel and its rotor blade in a meridional view. The meridional view of the turbine and its turbine housing and turbine wheel, as well as the rotor blade, are greatly simplified and purely schematic. In particular, the course of the trailing edge of the turbine wheel blade shown here is greatly simplified and purely schematic in order to explain and clarify the difference between the prior art and the invention. The illustrations are not to scale.

The present invention will be explained in more detail with reference to the example of a turbine wheel blade and the adaptation of the trailing edge. However, the invention also applies accordingly to a compressor impeller. In the case of the compressor impeller, however, instead of the trailing edge, the leading edge is adapted accordingly. The comments on the turbine blade and its trailing edge therefore apply substantially corresponding to the compressor impeller and its leading edge and are therefore not repeated.

1 shows a meridional view of a turbine of a turbocharger having a turbine housing and a turbine wheel. In the turbine housing 10, the turbine runner 14 of the turbine is arranged on a shaft 12. The turbine runner 14 in this case has blades 16 according to the prior art. As can be seen from the detail in FIG. 1 of a blade 16 of the turbine runner 14, this has a continuous vertical exit edge 18. This means that the blade 16 has no reduction of the axial length over its entire outlet edge 18. In this way, although a good efficiency of the turbine can be achieved, but the natural frequencies of this blade 16 and thus of the turbine runner 14 are comparatively low. Due to the low natural frequencies, it may therefore come to unwanted resonances, which can lead to a blade fracture in the worst case. 2, a further meridional view of a turbine of a turbocharger is shown, which has a turbine housing and a turbine wheel. In this case, a rotor blade 16 of the turbine runner 14 of a turbocharger is shown. In this case, the turbine runner 14 of the turbine is arranged in the turbine housing 10 on a shaft 12. The blades 16 of the turbine runner 14 in this case represent a further embodiment, as is known from the prior art.

In the meridional view in FIG. 2, one of the rotor blades 16 of the turbine runner 14 is shown. However, in contrast to the first embodiment according to the prior art, the rotor blade 16 does not have a vertical exit edge 18, but rather a rectilinear outlet edge 20 which is inclined towards the rear or against the flow direction. The flow direction of the exhaust gas mass flow is shown by arrows in all figures.

In FIG. 2, the vertical exit edge 18 according to the embodiment in FIG. 1 is initially drawn by a solid line for comparison. The inclined exit edge 20 according to the second embodiment of the prior art is drawn in FIG. 2 with a dashed line. Compared to the embodiment in FIG. 1, in the second embodiment of the prior art, a triangular section 22 has been removed, so to speak, in order to provide the rearward or backward inclined edge 20 of the moving blade 16. In other words, in the second embodiment, there is a linear reduction (in the meridional view) of the axial length of the blade 16.

In the following embodiments according to the invention, however, a non-linear reduction of the axial length of the blade (in the meridional view) takes place at least in a section of the trailing edge, in order to optimize the ratio of natural frequencies and efficiency of the blade or of the impeller, so that the highest possible gene frequencies at the lowest possible loss of efficiency of the blade or the impeller result.

Although the linear reduction of the axial length in the second embodiment of the prior art rotor 16 increases the natural frequencies of the turbine blade 14, the linear reduction has the disadvantage that the flow is conducted less in the entire outlet region of the turbine blade 14. As a result, the efficiency of the turbine is lowered.

In Fig. 3 is a meridional view of a turbine of a turbocharger is shown, which has a turbine housing and a turbine runner 14. In this case, a rotor blade 16 of the turbine runner 14 according to a first embodiment of the

Invention shown. In this case, first of all the rotor 16 of the second embodiment according to the prior art, as shown in FIG. 2, is shown for comparison with a solid line 20.

The trailing edge 24, 30 of the rotor blade 16 according to the invention is now composed, for example, of two regions 26, 28. In the lower region 26, the exit edge 24, 30 runs initially perpendicularly or substantially vertically. In the subsequent upper region 28, the course of the trailing edge 24 is directed back or the trailing edge 24, 30 is bent backwards or counter to the flow direction. In this case, the course of the exit edge 24, 30 is bent in the upper region 26 to the rear against the flow direction.

In FIG. 3, two examples of a trailing edge 24, 30 of a rotor blade 16 according to the first embodiment of the invention are shown. The first exit edge 24 according to the invention is shown with a dashed line in FIG. 3 and the second exit edge 30 according to the invention with a dotted line. The two exit edges 24, 30 according to the invention both have a The lower region 26, in which the exit edge 24, 30 of the rotor blade 16, for example, is perpendicular. The lower region 26 can extend, for example, up to half the blade height, as indicated in FIG. 3, or up to a first third or second third of the blade

Bucket height or even up to a quarter or even up to three quarters of the blade height. However, this is merely exemplary and the invention is not limited to these sizes of the lower portion 26. Basically, the upper portion 28 and the corresponding corresponding lower portion 26 can be chosen arbitrarily large, depending on the function and purpose. The aforementioned sizes for the lower region 26 are purely exemplary.

In any case, according to the first embodiment of the invention, the blade 16 whose trailing edge 24, 30 in the lower portion 26 perpendicular, substantially perpendicular or slightly against the flow direction bent back or curved. In the upper region 28, the trailing edge 24, 30 is further bent off or curved in the opposite direction to the flow direction. In this case, the exit edge 24, 30 in the upper region 28 more towards the rear, directed against the flow direction than in the lower region 26 in order to increase the natural frequencies of the impeller 14. The fact that the lower portion 26 is less curved backwards, an excessive reduction of the efficiency of the impeller 14 is avoided.

The two illustrated exit edges 24, 30 differ from each other, as shown in Fig. 3, that the second exit edge 30 in the upper region 28 is directed more towards the rear or against the flow direction than the first inventive exit edge 24. Furthermore extends the trailing edge 24 of the first embodiment of the invention the blade 16 in its upper portion 28 in an arc towards the rear against the flow direction. The trailing edge 30 of the second embodiment of the invention is the blade 16 again in its upper portion 28 bent back linearly, wherein the transition of the trailing edge 30 between the lower portion 26 and the upper portion 28 is preferably rounded.

If one now compares all three possible curves of the outlet edge 20, 24, 30 of the turbine blade 16 with one another, then one can ascertain the following.

The first and second inventive outlet edge 24, 30 each have a better or higher efficiency of the turbine than the outlet edge 20 according to the prior art, as shown in Fig. 2. This is because the first and second exit edges 24, 30 of the invention in the lower portion 26 are, for example, perpendicular, i. the respective blade 16 is not reduced in length in the axial direction, in contrast to the exit edge 20 according to the prior art, as shown in Fig. 2. As a result, better flow guidance is achieved both in the upper and lower regions of the outlet edge, as a result of which the efficiency increases.

Furthermore, the first exit edge 24 according to the invention, which is drawn with a dashed line, has slightly lower natural frequencies than the exit edge 20 according to the prior art, as is also shown in FIG. 2. However, the natural frequencies of the first exit edge 24 according to the invention are higher than the natural frequencies of the other exit edge 18 according to the prior art, as shown in Fig. 1, which is unabridged in length in the axial direction.

Furthermore, the natural frequencies of the second outlet edge 30 according to the invention, which is drawn in with a dotted line, are greater than the natural frequencies of the first outlet edge 24 according to the invention, since the second outlet edge 30 according to the invention continues further counter to Flow direction runs. However, this somewhat reduces the efficiency.

The moving blades 16 according to the invention, as shown in the example in FIG. 3, are preferably reduced substantially only in the region in their axial length, which leads substantially to an enlargement of the natural frequencies, here in the upper region 28 ,

4, another meridional view of a turbine of a turbocharger is shown having a turbine housing and a turbine runner 14. More specifically, the turbine runner 14 is shown having blades 16 according to a second embodiment of the invention, with a blade 16 shown in a meridional view. For comparison, the first, inventive exit edge 24 according to FIG. 3 is shown with a solid line in FIG. 4 and furthermore an example of an exit edge 32 of a rotor blade 16 according to the second embodiment according to the invention with a dashed line.

The trailing edge 32 of the rotor blade 16 of the turbine runner 14 according to the second embodiment of the invention has an S-shape or substantially an S-shape. In this case, the outlet edge 32 is, for example, curved inward in the lower region 26, curved in an arc against the direction of flow, or concave. In contrast, the first exit edge 30 of the invention, as shown in solid line in FIG. 4 and also shown in FIG. 3, is perpendicular in the lower region 26. Subsequently, the trailing edge 32 according to the second embodiment of the invention in the upper portion 28 is curved outward or convex. The division of the two regions 26 and 28 can be varied as desired. This applies to all embodiments of the invention. Furthermore, the trailing edge can also be divided into more than two areas. This also applies to all embodiments. The S-shape of the Exit edge 32 of the blade 16 is particularly advantageous for the occurring mechanical stresses in the blade 16. Due to the S-shape of the trailing edge 32 of the blade 16, the stress due to the centrifugal force in the lower region or lower point A of the blade 16 can be reduced.

Furthermore, FIG. 5 shows a meridional view of a turbine of a turbocharger, which has a turbine housing 10 and a turbine runner 14. The illustrated turbine runner 14 hereby comprises moving blades 16 according to a third embodiment of the invention, wherein a moving blade 16 is shown in a meridional view.

In the illustration of the blade 16, the first embodiment of the trailing edge 18 of a blade 16 according to the prior art is shown as a solid line for comparison. This rotor blade 16 has already been shown in FIG. 1 and is characterized in that the outlet edge 18 is designed to be continuous vertically.

Furthermore, FIG. 5 shows three examples of exit edges 34, 36, 38 for a rotor blade 16 according to the invention of a turbine wheel 14 in the form of a dashed line 34, a dot-dash line 36 and a dotted line 38. The three curves for the exit edge 34, 36, 38 are characterized in that they are curved backwards, against the direction of flow. In contrast to the second embodiment of the trailing edge 20 of a running shoe 16 according to the prior art, the trailing edge 34, 36, 38 according to the invention is not formed in the form of a straight line 20, which is simply inclined backwards, as in the prior art in FIG 2 is shown. Instead, the trailing edge 34, 36, 38 of the blade 16 according to the invention describes a curve or a curve which is curved backwards against the flow direction, wherein the outlet edge 34, 36, 38 itself no continuous straight line forms, but no or at most only at least one or more straight line sections.

The stronger the trailing edge 34, 36, 38 of the rotor blade 16 according to the invention swings towards the rear, the higher the natural frequencies of the rotor blade 16 and the more, however, the efficiency of the rotor 14 can decrease. In other words, the blade 16 with the outer, inventive trailing edge 34, which is drawn with a dashed line, has lower natural frequencies and a higher efficiency than, for example, the blade 16 with the innermost, inventive trailing edge 38, the Fig. 5 is shown with a dotted line.

However, the natural frequencies of the rotor blades 16 with the three exit edges 34, 36, 38 according to the invention each have higher natural frequencies than the rotor blade 16 with the exit edge 18 according to the prior art. The turbine efficiency of the rotor blades 16 with the three exit edges 34, 36, 38 according to the invention is less than the efficiency of the rotor blade 16 with the exit edge 18 according to the prior art. For this purpose, the blades 16 counteract the occurrence of unwanted resonances counter to the direction of flow according to the invention with the freely curved backward profile of the respective outlet edge 34, 36, 38 in contrast to the blades 16 according to the prior art, such as e.g. in Figs. 1 and 5 is shown.

In the geometry according to the invention, the loss of efficiency due to the reduction of the axial length is preferably minimized only in a certain, selected area or areas. Furthermore, the natural frequencies in a desired range or ranges can be increased and the loading of the blades by resonances can be avoided. This applies to all embodiments of the invention. The present invention can be used with both turbine runners and compressor runners. The above-described embodiments of the present invention have been explained with reference to a turbine runner and its blades. However, the embodiments apply, as described above, also substantially corresponding to a compressor impeller and its blades or blades and are therefore not repeated for this purpose.

For the wheels, i. Turbine wheels or compressor wheels (for example, radial turbine wheels or radial compressor wheels), at least one, two, several or all blades can be formed according to the blade or rotor blade according to the invention. Furthermore, the impeller, i. a turbine runner or a compressor runner, for example cast and / or milled, to name two manufacturing methods as examples.

Although the present invention has been described above with reference to the preferred embodiments, it is not limited thereto, but modifiable in a variety of ways. The embodiments described above can be combined with one another, in particular individual features thereof.

Claims

claims

A blade (16) of an impeller (14) of a turbocharger: wherein the blade (16) in the meridional view at its trailing edge (24, 30, 32, 34, 36, 38) at a

Turbine wheel blade or at its leading edge in a Verdichterradschaufel at least in one or more sections has a non-linear reduction of the axial length, and wherein the respective section and the reduction of the axial length of the blade (16) is selected such that the blade ( 16) has a predetermined ratio of natural frequencies and a loss of efficiency of the blade or the impeller.

2. Blade (16) of a rotor (14) of a turbocharger: wherein the blade (16) of the impeller (14) in the meridional view at its trailing edge (24, 30, 32, 34, 36, 38) at a turbine blade or its leading edge in a compressor impeller is reduced in axial length in a first, upper region (28), and wherein the trailing edge (24, 30, 32, 34, 36, 38) is perpendicular in a second, lower region (26); is substantially perpendicular or rearward, runs counter to the flow direction, or the leading edge in a second, lower region perpendicular, substantially perpendicular or rearward, in the flow direction, so that the loss of efficiency of the impeller (14) in a predetermined range is limited.

3. A blade according to claim 1, characterized in that the blade (16) in a first, upper region

(28) has at least one section with a non-linear reduction of the axial length, wherein the trailing edge of the blade (16) or turbine wheel blade in a second, lower region (26) perpendicular, substantially perpendicular or rearward, runs counter to the flow direction, or wherein the leading edge of the blade (16) or compressor wheel blade in a second, lower region (26) perpendicular, substantially perpendicular or rearward, in the flow direction, so that the loss of efficiency of the impeller (14) is limited in a predetermined range.

4. A blade according to claim 2 or 3, characterized in that the trailing edge (24, 30, 32, 34, 36, 38) of the blade (16) or turbine blade within the first, upper region (28) and / or the second , the lower region (26) runs backwards against the direction of flow continuously curved or at least partially curved, or the leading edge of the blade (16) or Verdichterradschaufel within the first, upper region (28) and / or the second, lower region (26) extends continuously curved backwards in the flow direction or at least partially curved.

5. A blade according to claim 2, 3 or 4, characterized in that the trailing edge (24, 30, 32, 34, 36, 38) of the blade (16) or turbine blade within the first, upper region (28) and / or the second, lower region (26) bent backwards against the flow direction in the form of a continuous straight line or at least has a rectilinear section, or the leading edge of the blade (16) or Verdichterradschaufel within the first, upper region (28) and / or the second, lower region (26) bent backwards in the flow direction in the form of a continuous straight line or at least has a rectilinear section.

Bucket according to one of claims 2 to 5, characterized in that the trailing edge (24, 30, 32, 34, 36, 38) of the blade (16) or turbine wheel blade in the first, upper region (28) stronger or continues to the rear against the flow direction than in the second, lower region (26), or the leading edge of the blade (16) or Verdichterradschaufel in the first, upper region (28) is stronger or further backward in the flow direction than in the second, lower area (26).

7. Blade according to one of claims 2 to 6, characterized in that at least the transition between the first, upper region (28) and the second, lower region (26) of the trailing edge (24, 30, 32, 34, 36 , 38) or inlet edge is preferably rounded.

8. A blade according to at least one of claims 1 to 7, characterized in that the outlet edge (32) or the leading edge of the blade (16) has an S-shape or the first, upper region (28) and the second, lower region (26) of the trailing edge or the leading edge together form an S-shape.

9. A blade according to at least one of claims 1 to 8, characterized in that an S-shape of the trailing edge (32) or the leading edge of the blade (16) is convex above convex and convex at the bottom.

10. Blade according to at least one of claims 1 to 9, characterized in that the blade (16) is a blade of a turbine wheel (14) and / or a compressor wheel, for example a radial turbine impeller or a radial compressor impeller.

11. A blade according to at least one of claims 1 to 10, characterized in that the blade (16) is cast and / or milled.

12. A blade according to at least one of claims 1 to 11, characterized in that the size of the second, lower region (26), for example, at least in a range of 1/6, 1/5, 1/4, 1/3, 1 / 2, 2/3 to 3/4 of the blade height is.

Shovel according to at least one of claims 1 to 12, characterized in that the trailing edge or leading edge of the blade (16) at least in one, two, three, four or more areas (26, 28) is divisible, wherein at least one area (26, 28) has a nonlinear reduction in axial length, wherein the size of at least two, more or all regions (26, 28) is the same or different.

14. An impeller of a turbocharger, wherein the impeller (14) has at least one, several or all blades (16) according to one of claims 1 to 13.

15. Impeller according to claim 14, characterized in that the impeller (14) is a turbine impeller or a compressor impeller, for example a radial turbine impeller or radial compressor impeller.

16. Impeller according to claim 14 or 15, characterized in that the impeller (14) is cast and / or milled.