EP3601739A1

EP3601739A1 - Turbocharger for an internal combustion engine, and turbine housing

Info

Publication number: EP3601739A1
Application number: EP18718704.2A
Authority: EP
Inventors: Ivo Sandor; Sebastian WITTWER; Michael Klaus; Ralf Böning
Original assignee: Vitesco Technologies GmbH
Current assignee: Vitesco Technologies GmbH
Priority date: 2017-03-30
Filing date: 2018-03-22
Publication date: 2020-02-05
Anticipated expiration: 2038-03-22
Also published as: US20200003079A1; US11002154B2; CN110520598B; CN110520598A; WO2018177864A1; EP3601739B1; DE102017205457A1

Abstract

The invention relates to a turbocharger (1) for an internal combustion engine, comprising - a bearing housing (41), in which a rotor shaft (14) is mounted rotatably about a rotor axis of rotation (15); - an exhaust gas turbine (20) having a turbine wheel (12), which is arranged non-rotatably on the rotor shaft (14) and which has an impeller blading (121) comprising a plurality of turbine blades (122), and comprising a turbine housing (21), which is mechanically fixed to the bearing housing (41) and which surrounds the turbine wheel (12); wherein the turbine housing (21) and the turbine wheel (12), in respect of a meridional view of the exhaust gas turbine (20), are formed and coordinated with one another in such a way that the following condition is met (I).

Description

description

Turbocharger for an internal combustion engine and turbine housing The invention relates to a turbocharger for an internal combustion engine.

Exhaust gas turbochargers are increasingly used to increase performance in automotive internal combustion engines. This happens more and more often with the aim of reducing the internal combustion engine with the same or even increased performance in size and weight while reducing consumption and thus the CO ₂ emissions, in view of ever stricter legal requirements in this regard. The operating principle is to use the energy contained in the exhaust gas flow to increase a pressure in an intake tract of the internal combustion engine and thus to effect a better filling of a combustion chamber of the internal combustion engine with air-oxygen. Thus, more fuel, such as gasoline or diesel, per combustion process can be implemented, so the performance of the engine can be increased.

For this purpose, the exhaust gas turbocharger has an exhaust gas turbine arranged in the exhaust tract of the internal combustion engine, a fresh air compressor arranged in the intake tract and a rotor bearing arranged therebetween. The exhaust gas turbine has a turbine housing and a turbine runner, which is arranged therein and driven by the exhaust gas mass flow. The fresh air compressor has a compressor housing and a compressor impeller which is arranged therein and builds up a boost pressure. The turbine runner and the compressor runner are rotatably mounted on the opposite ends of a common shaft, the so-called rotor shaft, and thus form the so-called turbocharger rotor. The rotor shaft extends axially between the turbine runner and the compressor runner through the rotor bearing arranged between the exhaust gas turbine and the fresh air compressor and is radially and axially rotatably mounted therein, with respect to the rotor shaft axis. According to this structure drives driven by the exhaust gas mass flow turbine wheel on the rotor shaft to the compressor impeller, whereby the pressure in the intake of the engine, based on the

Fresh air mass flow behind the fresh air compressor, and thus increased filling of the combustion chamber with

Air-oxygen is effected.

An object of the invention is to provide a concept for a turbocharger which contributes to the safe operation of a turbocharger.

A turbocharger for an internal combustion engine is disclosed. The turbocharger has a bearing housing in which a rotor shaft is rotatably mounted about a rotor axis of rotation, wherein the rotor shaft is mounted in the bearing housing via at least two radial bearings. The turbocharger has an exhaust gas turbine with a turbine wheel, which is arranged rotationally fixed on the rotor shaft and which has a impeller Beschau felung with a plurality of turbine blades, and with a turbine housing, which is mechanically fixed to the bearing housing and which surrounds the turbine wheel on. Regarding a meridionalansieht the exhaust gas turbine applies:

- At least one turbine blade of the turbine wheel has a flow inlet edge and a flow outlet edge for the exhaust gas mass flow.

The flow inlet edge has a maximum inlet radius R _in and the flow outlet edge has a maximum outlet radius R _out , in each case relative to the rotor axis of rotation.

- The at least one turbine blade has a the

Turbine housing facing outer contour, which extends from the flow inlet edge to the flow _{outlet edge} and an axial extension length L _axTlp has.

- The turbine housing has a housing contour, which is opposite to the outer contour.

- The outer contour of the at least one turbine blade has an axial length portion L _cover the axial extent L _axTip , in which the at least one turbine blade is axially covered by the turbine _housing .

- Between the housing contour and the outer contour ferdrehachse with respect to the Läu a smallest radial distance tip _{clr is} formed.

The turbine housing and the turbine wheel are designed and tuned to one another such that the following condition resp. Equation is satisfied:

It has been recognized that turbocharger failure may occur during operation of the turbocharger, such as in turbocharger design test stands or turbocharger and rotor components. For example, there may be a component failure of the rotor shaft or the wheels, such as a shaft break.

In the case of a shaft breakage of the rotor shaft, for example, the turbine wheel can no longer be held axially by a thrust bearing in its intended position. In this case, the turbine wheel would be moved in the direction of a turbine housing outlet for the exhaust gas mass flow mainly by aerodynamic forces, for example due to prevailing gas pressures. In this case, the proportion of the turbine blades of the turbine wheel, which has a larger diameter than an outlet diameter of the turbine housing at the downstream end of the turbine wheel, abuts against the turbine housing and obstructs the turbine wheel in its axial movement in the direction of the turbine housing outlet. It has further been recognized that if this fraction of turbine blades is not sufficiently large, the turbine blades will be plastically deformed in the event of a shaft fracture such that the turbine wheel may undergo another unintentional axial displacement.

A disadvantage in such a case would be, inter alia, that piston rings of Oldichtungen could leave their original axial position and so a sealing effect would be lost. This One of the negative consequences of this would be that oil could escape in such quantities that the internal combustion engine, into which the turbocharger is connected, must be shut down immediately in order to prevent damage. However, oil leakage should absolutely or largely be avoided in order to ensure at least emergency running properties of the system. In addition, it was recognized that a shaft break between the oil seals, such as the piston rings of both seals, is disadvantageous because in addition to the wheels and the remaining Len lenstummein also the seals could leave the turbocharger, which would further favor the negative oil loss described.

The turbocharger described provides that the turbine wheel and turbine housing are designed and arranged according to the above formulated condition (equation). The condition specifies that a contour profile of the turbine housing and / or the at least one turbine wheel blade are transformed in a targeted manner in comparison to known turbines. In particular, a length portion (L _cover ) of the turbine wheel blade, which is covered axially by the housing, such increased that in the case of Wel lenbruchs a larger proportion of the turbine wheel blades would be formed plastically ver with an axial displacement, so that a further axial movement of the Turbine wheel is hampered or limited with respect to the rotor axis of rotation. For example, starting from a conventional len housing contour in the region of the turbine wheel alone by the transformation of the length proportion of the turbine wheel blade, which is covered axially by the housing increases. In other words, the condition defines a minimum value of the length fraction of the turbine blade that is axially covered.

Such a design based on the given equation contributes to the fact that the turbine wheel, after a shaft break, that is to say in the event of a damage of the turbocharger, provides greater resistance to further axial displacement in collision with the housing. The equation thus makes possible an optimal design for different parameters Turbine wheel and turbine housing. Depending on the basic conditions for the turbocharger such as purpose, use or other purpose, certain parameters may be given the same, with one or more remaining parameters mithi 1 fe can be determined by the equation. Thus, a meaningful adjustment of the parameters can always be achieved in accordance with the basic conditions. In particular, it is possible by means of the equation to determine the necessary for the above Vortei le and functions axial overlap length L _cover in a simple manner.

A turbocharger designed according to the conditions helps to avoid the disadvantages mentioned above in the event of damage, in particular the shaft breakage mentioned, in particular if the turbine wheel is only radially mounted. It is not absolutely necessary to constructively reinforce a back plate and / or the Turbinenradschaufein. In other words, thanks to the above condition, it is not necessary to thicken the turbine wheel blade accordingly. Also, thanks to the above condition, it is not necessary to have a low trim ratio, ie a ratio between the maximum exit radius R _out

and the maximum entry radius R _in . As a result, among other material costs can be saved. Both such measures would be detrimental to the performance of the turbocharger, for example due to higher inertia.

Meridionalansieht means, for example, a planar, two-dimensional view, in which an outermost contour of the turbine wheel is shown, the turbine wheel at a

Rotation about the rotor axis of rotation, which also corresponds to a rotational axis of the turbine, moves off. The view may also relate to or include at least Tei le of the turbine housing, in particular an inner contour with minimal radius relative to the rotational axis in the region of the turbine wheel is dargestel lt, which would leave the turbine housing during rotation about the axis of rotation. The outer contour of the opposite housing contour of the turbine housing (English: shroud) is formed corresponding to the outer contour. At the lowest radial distance tip. _: I, with respect to the rotor axis of rotation may be by a distance which is constant over the entire axial region between the leading edge and the trailing edge. However, it is also conceivable that the distance is present only in sections, in a single area or point with respect to the axis of rotation.

By the axial length portion is meant the axial extent of the outer contour in which a radius resp. a diameter of the turbine wheel with respect to the rotor axis of rotation is greater than a minimum diameter / radius of the turbine housing in the region of a downstream end of the turbine wheel. In other words, in this area, the diameter of the turbine wheel is larger than a smallest diameter of the turbine housing. In other words, it is Denj enigen axial region of a turbine wheel, which would be the turbine wheel and the Turbi ^¬ nengehäuse in a plane normal to the rotor axis of rotation pro- j izieren, is covered or overlapped by the turbine housing. In other words, it is denj enigen area, which in the shadow of the turbine housing 1 iegt related to the rotor axis of rotation. In other words, the outer contour of the at least one blade has an axial overlap _{portion which} has the axial length _portion L _{cover of} the axial extent L _axTip .

The following embodiments all contribute to the above advantages and functions, wherein the above condition is advantageously developed further by the specification of one or more limit values.

According to one _embodiment , for the ratio Tip _clr to R _in :

According to one embodiment, for the ratio Tip _clr to R _in :

The ratio R _out to R _in is also referred to as trim or trim ratio.

According to forms of execution, the trim ratio is between 0, 8 and one of the other limits specified above. Furthermore, a turbine wheel for an exhaust gas turbocharger according to one of the preceding embodiments is disclosed. The turbine wheel has impeller inspection with multiple turbine blades. The turbine wheel is configured such that the following

Condition is fulfilled:

In this case, with respect to a Meridionalansieht the turbine wheel that applies

- At least one turbine blade of the turbine wheel has a flow inlet edge and a flow outlet edge for the exhaust gas mass flow;

- R step edge _in a maximum entry radius of the flow inlet and R _out a maximum outlet radius of the flow trailing edge describes in each case on an axis of rotation of the turbine wheel;

L _{axTip describes} an axial extension length of an outer contour of the at least one turbine blade, wherein the outer contour extends from the flow inlet edge to the flow outlet edge and, in normal operation, faces a surrounding turbine housing;

- L _{cover describes} an axial length _portion of the axial extent L _axTip the outer contour, in which the turbine blade is axially covered by the turbine _housing ;

- Tip _clr a minimum radial distance between a housing contour of the turbine housing, which in the normal operation of the outer contour opposite, and describes the outer contour with respect to the rotor axis of rotation.

The above statements apply analogously.

The turbine wheel allows the above advantages and features.

Further, a method of manufacturing a turbocharger according to any one of the above embodiments is disclosed. The method comprises the steps: Determining and / or determining the parameters of the maximum entry _radius R _in , the maximum exit _radius R _out , the axial extension length L _axTip , the axial length _portion L _cover and the minimum radial distance tip _clr such that for the turbine wheel and the turbine _housing the following Condition is fulfilled:

- Manufacture of the turbine wheel and the turbine housing based de the determined by means of the condition parameters.

The above statements apply analogously.

The method allows the above advantages and functions.

In the following, embodiments of the invention will be described without any restriction of generality.

The exemplary embodiments are described below with reference to the appended figures. Similar or equivalent elements are provided figurenübergrei fend with the same reference numerals. show the figures

FIG. 1 shows a schematic sectional view of a turbocharger,

FIGS. 2 and 3 are two diagrammatic sectional views of exhaust turbines of a turbocharger;

Figure 4 is a schematic sectional view of an exhaust gas turbine of a turbocharger according to an exemplary embodiment, Figure 5 is an equation for the interpretation of the exhaust gas turbine according to the imple mentation game and FIG. 6 shows a diagram representation of the equation of FIG. 5 with three exemplary parameter selections.

FIG. 1 schematically shows an exemplary exhaust gas turbocharger 1 in a sectional view, which has an exhaust gas turbine 20, a

Fresh air compressor 30 and a rotor bearing 40 has. The exhaust gas turbine 20 is equipped with a Wastegateventi 129 and an exhaust gas mass flow AM is indicated by arrows. Of the

Fresh air compressor 30 has a thrust recirculation valve 39 and a fresh air mass flow FM is also indicated by arrows. A so-called turbocharger rotor 10 of the exhaust gas turbocharger

1 has a turbine wheel 12 (also turbine wheel referred to), a compressor wheel 13 (also called Verdi chterrad) and a rotor shaft 14 (also called shaft). The turbocharger rotor 10 rotates in operation about a rotor axis of rotation 15 of the rotor shaft 14. The rotor axis of rotation 15 and at the same time the turbocharger axis

2 (also called longitudinal axis) are represented by the drawn center line and indicate the axial orientation of the exhaust gas turbocharger. 1

As a rule, a common exhaust-gas turbocharger 1, as shown in FIG. 1, has a multi-part construction. In this case, a turbine housing 21 which can be arranged in the exhaust tract of the internal combustion engine, a compressor housing 31 which can be arranged in the intake tract of the internal combustion engine and between turbine housing 21 and compressor housing 31 a bearing housing 41 are arranged side by side with respect to the common turbocharger axle 2 and are connected to one another by assembly technology. The bearing housing 41 is disposed axially between the turbine housing 21 and the compressor housing 31. In the bearing housing 41, the rotor shaft 14 of the turbocharger rotor 10 and the required LageranOrdnung for axial bearing and for pivotal mounting of the rotor shaft 14 is added.

Another structural unit of the exhaust gas turbocharger 1 is the turbocharger rotor 10, the Läuferwel le 14, which is arranged in the turbine housing 21 turbine wheel 12 with a Impeller blading 121 and arranged in the compressor housing 31 compressor impeller 13 having an impeller blading 131 has. In other words, the turbine wheel 12 and the compressor wheel 13 have a plurality of blades arranged on a corresponding hub. The turbine runner 12 and the compressor wheel 13 are arranged on the gegenüber1 legend ends of the common Läuferwel le 14 and rotatably connected thereto. The Läuferwel le 14 extends axially in the direction of the turbocharger 2 through the bearing housing 41 and is rotatably mounted in this axially and radially about its longitudinal axis, the rotor axis of rotation 15, wherein the rotor axis of rotation 15 coincides with the turbocharger axis 2. The turbocharger rotor 10 is supported by its rotor shaft 14 by means of two radial bearings 42 and an axial bearing disk 43. Both the radial bearing 42 and the axial bearing disc 43 are supplied via oil supply channels 44 of an oil connection 45 with lubricant.

Turbine housing 21 has one or more exhaust gas annular channels, so-called exhaust gas passages 22, which are arranged annularly around turbocharger axis 2 and turbine runner 12 and taper in the shape of a helix toward turbine runner 12. These exhaust gas flutes 22 have a common or common, tangentially outwardly directed Abgaszuführkanal 23 with a manifold connecting piece 24 for connection to an exhaust manifold (not shown) of an internal combustion engine through which the exhaust gas mass flow AM into the j eweilige exhaust flute 22 and then flows on the turbine runner 12. The turbine housing 21 further includes an exhaust discharge passage 26 extending from the axial end of the turbine runner 12 toward the turbocharger shaft 2 and having an exhaust port 27 for connection to the exhaust system (not shown) of the engine. About this Abgasabführkanal 26 exiting the turbine wheel 12 exhaust gas mass flow AM is discharged into the exhaust system of the engine.

Further details of the turbocharger 1 are not explained in detail at this point. It should be noted that the turbocharger 1 described in Figure 1 is to be understood as an example and Alternatively, it may also have other embodiments, without any limitations for the following description of imple mentation of the invention with reference to Figures 4 to 6 result.

FIGS. 2 and 3 each show in a meridional manner exhaust gas turbines 20 of a turbocharger 1, which respectively comprise a turbine housing 21 and a turbine wheel 12 with a plurality of turbine blades 122. FIG. 2 shows a radial-axial turbine wheel and FIG. 3 shows a radial turbine wheel in a schematic half section. The rotor rotation axis 15, which corresponds to a rotation axis 123 of the turbine wheel 12, is indicated in each case. In the illustrations of FIGS. 2 and 3, one of a plurality of turbine blades 122 is shown, which are typically arranged on the hub of the turbine wheel 12.

The turbines 20 of the two FIGS. 2 and 3 are described by way of example with reference to FIG.

The turbine wheel 12 has an upstream, axial end 124 and a downstream, axial end 125. As can be seen in the meridional view, the illustrated turbine blade 122, like all other turbine blades, has a flow inlet edge 126 for the exhaust gas mass flow AM and a flow exit edge 127 for the exhaust gas mass flow AM after exiting the turbine wheel 12 or. from the turbine blades 122. The flow inlet edge 126 and / or the flow outlet edge 127 can run obliquely or otherwise, for example, parallel to the rotor axis of rotation 15, as can be seen with reference to FIGS. 2 and 3. The flow inlet edge 126 and the flow outlet edge 127 are connected via an outer contour 128 (English Tip). The outer contour 128 lies directly opposite a housing contour 211 of the turbine housing 21, which surrounds the turbine wheel 12. The housing contour 211 is formed corresponding to the outer contour 128, wherein a course of the two contours 128 and 211 in the view shown in wesentl paral lel to each other with respect to the Rotation axis 123. The further turbine housing 21 is not shown for reasons of clarity.

It has been recognized that the shown exhaust gas turbines 20 of FIGS. 2 and 3 can be defined by a plurality of parameters, which will be explained below.

The flow inlet edge 126 has a maximum inlet radius R _in and the flow outlet edge 127 has a maximum outlet radius R _out . The outer contour 128 has relative to the axis of rotation 123 and. the rotor _{axis of} rotation 15 has an axial extension _length L _axTlp . The outer contour 128 has an axial length _portion L _{cover of} the axial extent L _axTlp , in which the turbine blades 122 are covered axially by the turbine _housing 21. In other words, this means the axial region in which a diameter of the turbine wheel 12 is greater than a smallest diameter DA of the turbine housing 21 at the turbine exhaust outlet 129 for the exhaust gas mass flow AM. Furthermore, the housing contour 211 and the outer contour 128 are spaced from one another in such a way that a minimal gap is formed, wherein a smallest radial distance tip _clr between the housing contour 211 and the outer contour 128 prevails.

As mentioned above, turbochargers can lead to damage with various adverse consequences. On the basis of Figures 4 to 6 are described from management examples of turbines 20, which allow in the event of damage of the turbocharger 1, the aforementioned functions and Vortei le.

FIG. 4 shows a turbine 20, which essentially corresponds to the turbines of FIGS. 2 and 3. The above parameter definitions apply analogously. In contrast to the described turbines of Figures 2 and 3, the turbine 20 is formed so that the equation shown in Figure 5 is satisfied. The condition is:

As a result, the advantages and functions mentioned above are achieved. It should be mentioned at this point that the ratio R _out to R _in can be referred to as trim (see FIG. 5). The design and manufacture of the turbine 2 0 is carried out, for example, such that certain parameters are given and by the conditions remaining parameters are determined in order to obtain a minimum required value for L _Cover . It is advantageous, as can also be seen in FIG. 4, in contrast to the examples of FIGS. 2 and 3, that the axial length component L _{cover is} enlarged and tuned to the turbine housing 21. As a result, the turbine wheel 12 has an enlarged portion, which is covered by the turbine housing 21.

FIG. 6 shows a diagram in which the trim value is plotted on the X axis and the ratio of L _cover to L _axT ip is plotted on the Y axis. By way of example, three curves of the equation according to FIG. 5 are shown, which differ by the percentage _{values shown} to the right of the diagram, which result from the ratio of tip _clr to R _in .

Claims

claims

1. Turbocharger (1) for an internal combustion engine, comprising

- A bearing housing (41) in which a rotor shaft (14) is rotatably mounted about a rotor axis of rotation (15); and

- An exhaust gas turbine (20) with a turbine wheel (12) which is non-rotatably mounted on the rotor shaft (14) and which has an impeller blading (121) with a plurality of turbine blades (122), and with a turbine housing (21), which mechanically on the Bearing housing (41) is fixed and which surrounds the turbine wheel (12);

with regard to a meridional, the exhaust gas turbine looks on

(20)

- At least one turbine blade (122) of the turbine wheel (12) has a flow inlet edge (126) and a flow outlet edge (127) for the exhaust gas mass flow (AM),

- The flow inlet edge (126) has a maximum inlet radius R _in and the flow outlet edge (127) has a maximum outlet radius R _out , in each case with respect to the rotor axis of rotation (15);

- The at least one turbine blade (122) has an outer contour (128) facing the turbine housing (21), which extends from the flow inlet edge (126) to the flow exit edge (127) and has an axial extension length L _axTip ;

- The turbine housing (21) has a housing contour (211) which is opposite to the outer contour (128);

- The outer contour (128) of the at least one turbine blade (122) has an axial length _portion L _cove the axial extent L _axTip , in which the at least one turbine blade (122) is axially covered by the turbine _housing (21); and

- Between the housing contour (211) and the outer contour (128) with respect to the rotor axis of rotation (15) a lowest radial distance tip _{cl r is} ausgebi LOD;

and wherein the turbine housing (21) and the turbine wheel (12) are so designed and matched to each other that the following condition is met:

9. Turbine wheel (12) for an exhaust gas turbocharger (1) according to one of the preceding claims, comprising an impeller blade (121) with a plurality of turbine blades (122), wherein the turbine wheel (12) is formed such that the following condition is met :

wherein with respect to a Meridionalans icht the turbine wheel (12) - at least one turbine blade (122) of the turbine wheel (12) has a flow inlet edge (126) and a flow ^¬ outlet edge (127) for the exhaust gas mass flow (AM); - R, "a maximum inlet radius of the flow inlet edge (126) and R _{out describes} a maximum outlet radius of the flow outlet edge (127), each related to a rotational axis (123) of the turbine wheel (12);

- L _axTip an axial extension _{length of} an outer contour

(128) which describes at least one turbine blade (122), the outer contour (128) extending from the flow inlet edge (126) to the flow outlet edge (127) and facing a surrounding turbine housing (21) in normal operation;

- L _{cover describes} an axial length _portion of the axial extent L _{axTip of} the outer contour (128), in which the at least one turbine blade (122) is covered axially by the turbine housing (21);

- Tip _clr a minimum radial distance between a

Housing contour (211) of the turbine housing (21), which in the normal operation of the outer contour (128) opposite, and the outer contour (128) relative to the rotation axis (123) describes.

10. A method of manufacturing a turbocharger (1) according to any one of claims 1 to 8, comprising the steps of:

Determining and / or determining the parameters of the maximum entry radius R _{± n} , the maximum exit radius R _ou t, the axial extension length L., _xT , _p , the axial length component L _cover and the

lowest radial distance Tip, _{:! r} such that the following condition is satisfied for the turbine wheel (12) and the turbine housing (21):

- Manufacture of the turbine wheel (12) and the turbine housing (21) based on the parameters determined by the condition.