Rotor disk for an exhaust turbocharger, exhaust turbocharger and method for balancing a rotor assembly for an exhaust turbocharger

Abstract

A rotor disk for an exhaust turbocharger is mounted in a housing of the exhaust turbocharger so as to be able to rotate about an axis of rotation. The rotor disk has a disk hub including a disk back and a disk front facing away from the disk back. A plurality of rotor disk blades are formed on the disk hub in a manner extending between the disk back and the disk front. A balancing mark is arranged in a blade channel formed between a first blade of the plurality of rotor disk blades and a second blade, arranged adjacent to the first blade, of the plurality of rotor disk blades. The balancing mark is triangle-like. The disclosure also relates to an exhaust turbocharger comprising such a rotor disk and to a method for balancing a rotor assembly for such an exhaust turbocharger.

Claims

1.-8. (canceled)

9. A rotor disk for an exhaust turbocharger, wherein the rotor disk (1) is mounted in a housing of the exhaust turbocharger (3) so as to be able to rotate about an axis of rotation, and wherein the rotor disk (1) has a disk hub (5) comprising a disk back (6) and a disk front facing away from the disk back (6), and wherein a plurality of rotor disk blades (4) are formed on the disk hub (5) in a manner extending between the disk back (6) and the disk front, and wherein a balancing mark (11) is arranged in a blade channel (9) formed between a first blade (7) of the plurality of rotor disk blades (4) and a second blade (8), arranged adjacent to the first blade (7), of the plurality of rotor disk blades (4), and wherein the balancing mark (11) is triangle-like, and wherein a limb (12) of the balancing mark (11) is arranged extending in a circumferential direction.

10. The rotor disk as claimed in claim 9, wherein a mark base (18) of the balancing mark (11) is smaller than a free surface (20) of the balancing mark (11).

11. The rotor disk as claimed in claim 9, wherein the rotor disk (1) is a compressor wheel.

12. An exhaust turbocharger comprising a rotor assembly (2) which is rotatably mounted in a housing of the exhaust turbocharger (3) and comprises a shaft and at least one rotor disk (1) as claimed in claim 9 which is connected to the shaft for conjoint rotation therewith.

13. A method for balancing a rotor assembly (2) which is mounted rotatably in a housing of an exhaust turbocharger (3), wherein the rotor assembly (2) comprises a rotor disk (1) as in claim 9 and wherein the balancing mark (11) is produced using high speed balancing.

14. The method as claimed in claim 13, wherein the balancing mark (11) is produced by material removal.

15. The method as claimed in claim 13, wherein the balancing mark (11) is formed using a milling method.

16. The method as claimed in claim 13, wherein the balancing mark (11) is formed using a milling method with a ball head-like tool.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 shows a perspective view of a detail of a rotor disk according to the prior art.

[0023] FIG. 2 shows a perspective view of a detail of a further rotor disk according to the prior art.

[0024] FIG. 3 shows a perspective view of a detail of a rotor disk in a first exemplified embodiment.

[0025] FIG. 4 shows a perspective view of a detail of a rotor disk in a second exemplified embodiment.

[0026] FIG. 5 shows a perspective view of a detail of a rotor disk in a third exemplified embodiment.

[0027] FIG. 6 shows a perspective view of a detail of a rotor disk in a fourth exemplified embodiment.

DETAILED DESCRIPTION

[0028] A rotor disk 1 of a rotor assembly 2 for an exhaust turbocharger 3 according to the prior art is formed as shown in FIG. 1. The rotor disk 1 is designed in the form of a compressor wheel. The rotor assembly 2 comprises the compressor wheel 1 and a turbine wheel, not illustrated in greater detail, which is connected via a shaft, not illustrated in greater detail, to the compressor wheel 1 for conjoint rotation therewith.

[0029] The rotor assembly 2 is mounted in a bearing portion, not illustrated in greater detail, of the exhaust turbocharger 3 so as to be able to rotate about an axis of rotation, not illustrated in greater detail, of the rotor assembly 2. The turbine wheel is accommodated in a rotatable manner in an exhaust gas conducting section, not illustrated in greater detail, of the exhaust turbocharger 3, said exhaust gas conducting section being capable of having a flow pass therethrough. Exhaust gas from an internal combustion engine, which is not illustrated in greater detail and is connected to the exhaust turbocharger 3 so as to be capable of having a flow pass therethrough, is supplied via an inlet channel, not illustrated in greater detail, of the exhaust gas conducting section, to the turbine wheel, causing said turbine wheel to rotate.

[0030] By means of the rotationally-fixed connection, established with the aid of the shaft, to the compressor wheel 1, the compressor wheel 1 which is rotatably accommodated in an air conducting section, not illustrated in greater detail, is likewise caused to perform a rotational movement, wherein it takes in air and compresses it. The compressed air is supplied to the internal combustion engine via an outlet channel, not illustrated in greater detail, of the air conducting section.

[0031] The compressor wheel 1 comprises a plurality of rotor disk blades 4, by means of which it takes in air, which blades are arranged on a disk hub 5 of the compressor wheel 1. The disk hub 5 has a disk back 6 and a disk front, not illustrated in greater detail and facing away from the disk back 6, of the disk hub 5. The plurality of rotor disk blades 4 are arranged on the disk hub 5 in a manner extending from the disk front to the disk back 6. Formed between in each case two blades of the plurality of rotor disk blades 4, a first blade 7 and a second blade 8, is a blade channel 9 comprising a channel base 10, along which the air flows. The rotor disk 1 can be rotated about an axis of rotation not illustrated in greater detail.

[0032] In order to produce a particularly calm rotational movement of the rotor assembly 2, a balancing mark 11 is formed on the channel base 10 of the compressor wheel 1. The balancing mark 11 of the rotor disk according to the prior art, as illustrated in FIG. 1, is point-shaped.

[0033] FIG. 2 illustrates a further rotor disk according to the prior art. The formed balancing mark 11 is elongate and slightly curved.

[0034] A balancing mark 11 as illustrated according to a first exemplified embodiment in FIG. 3 is triangle-like. The balancing mark 11 has a first limb 12, a second limb 13 and a third limb 14 which are connected to one another with the aid of connecting elements 15. The connecting elements 15 are curved, whereas the limbs 12, 13, 14 are substantially linear relative to the connecting elements 15.

[0035] The triangle-like balancing mark 11 is triangle-like predominantly in relation to its periphery. However, it could likewise be triangle-like in relation to its depth extension T. Or it could likewise be triangle-like, i.e. tetrahedron-like in all three dimensions. They can also be equilateral, scalene or isosceles triangles.

[0036] In order to produce the balancing mark 11 using so-called high-speed balancing, on the one hand the material-removing tool can be moved or on the other hand the rotor disk 1 or the rotor assembly 2 itself can be moved. A linear balancing mark 11 can be produced preferably by a moved tool, whereas the balancing mark 11 in accordance with the disclosure can be produced preferably with a moved rotor disk 1 or moved rotor assembly 2 and moved tool.

[0037] In the so-called high speed balancing machine, the rotor assembly is installed in the bearing housing and is clamped in the high speed balancing machine, thus allowing access for material removal at the disk hub 5 in the axial direction. If other machines are used, radial-axial machining can be effected at specific angles. This provides access to regions of the disk hub 5 which are located radially further inwards in the direction of the disk back 6 where the stresses are not so high. In this case, e.g. more material could also be removed.

[0038] In order to effect sufficient removal of a rotor disk mass which reduces, in particular eliminates, the imbalance, the depth extension T of the balancing mark 11 can likewise be increased. In comparison with the typical balancing marks, a sufficient amount of material can be removed in order to eliminate the imbalance because material is removed in three dimensions by reason of the triangle-like balancing mark 11.

[0039] The first limb 12 which can also be considered to be a base side of the balancing mark 11 is arranged extending in the circumferential extension direction U. Therefore, a tip 16 of the balancing mark 11 is positioned facing away from a disk outer edge 17 and facing towards a disk centre of the rotor disk. Therefore, the balancing mark 11 is arranged adapted virtually to an elongation of the channel base 10 which is formed so as to taper starting from the disk outer edge 17 in the direction of the disk centre.

[0040] The first limb 12 of the balancing mark 11 illustrated in FIG. 3 in a first embodiment is slightly curved, whereby the balancing mark 11 can adapt to a curvature of the disk outer edge 17. However, the curvature of the first limb 12 is substantially shallower than the curvature of the connecting elements 15. Likewise, the two other limbs 13, 14 could have a slight curvature which, however, is substantially reduced in comparison with the curvature of the connecting elements 15.

[0041] FIG. 4 illustrates the balancing mark 11 in accordance with the disclosure in a second exemplified embodiment. In comparison with the balancing mark 11 of the first exemplified embodiment, the limbs 12, 13, 14 are linear, wherein an extension is increased in the circumferential direction U of the balancing mark 11 of the second exemplified embodiment.

[0042] The curvatures of the connecting elements 15 are provided in order to reduce a notch stress between the converging limbs 12, 13, 14.

[0043] A further reduction in the notch stress is achieved by virtue of the fact that a transition 19 formed between the limbs 12, 13, 14 and a mark base 18 of the balancing mark 11 is rounded. In other words, this means that the mark base 18 is smaller than a free surface 20 of the balancing mark 11, as is evident in particular from the balancing mark 11 according to a third exemplified embodiment as illustrated in FIG. 5. The free surface 20 of the balancing mark 11 corresponds to the surface in the plane of the channel base 10, said surface extending between the limbs 12, 13, 14.

[0044] In order to produce the balancing mark 11, basically any material-removing method can be used, in other words any material removal process. In particular, grinding is feasible if the rotor disk 1 is designed in the form of a turbine wheel. Likewise, the material removal could also be achieved with the aid of a laser method. The balancing mark 11 could also be produced on an outer edge of the rotor disk 1 with the aid of a cutting method. The advantage of milling can be seen in terms of a possible surface treatment and a cost advantage over other methods because milling is cost-effective and flexible to use.

[0045] The rotor disk 1 illustrated in particular in FIG. 6 and being in the form of a compressor wheel has the balancing mark 11 which has been produced with a ball head milling tool In other words, this means that the balancing mark 11 has been formed by a milling method, in particular with a ball head-like tool. As a result, the rounded connecting elements 15 and the rounded transition 19 can be produced in a simple manner without a further machining step during the formation of the balancing mark 11 by means of material removal.