Shaft bearing assembly for a turbomachine shaft and turbomachine

Abstract

A shaft bearing assembly (10) for a turbomachine shaft (11) is described. The shaft bearing assembly (10) includes a shaft (11) having a radial step (111) provided by the shaft or a separate element fixed to the shaft. The shaft bearing assembly (10) further includes a bearing bush (12) supporting the shaft (11). At least one of an axial surface (121) of the bearing bush (12) facing the radial step (111) and an axial segment of the bearing bush (12) has at least one groove (122) opening into a bore (123), the radial outer side of the at least one groove (122) being bounded by a radial sidewall (124), the radial inner side of the groove (122) being open, and the radial cross-sectional area of ​​the at least one groove (122) increasing toward the bore (123).

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present disclosure relate to a shaft bearing assembly for a shaft of a turbomachine, such as a turbocharger, turbocompound, and electric turbomachine. [Background technology]

[0002] It is known that air intake systems such as exhaust gas turbochargers are used to increase the power demand of internal combustion engines or fuel cell systems. In such exhaust gas turbochargers, a turbine is provided in the exhaust gas path of the internal combustion engine or fuel cell, and a compressor is arranged upstream of the internal combustion engine or fuel cell and connected to the turbine via a common shaft. Typically, the shaft is supported by a shaft bearing supported in a bearing housing. Therefore, an exhaust gas turbocharger generally comprises a rotor, a bearing assembly for the shaft, flow-guiding housing sections (compressor housing and turbine housing), and a bearing housing. The rotor includes the shaft and both the compressor wheel and the turbine wheel.

[0003] Charging an internal combustion engine or fuel cell with an exhaust gas turbocharger increases the volume of the fuel mixture in the cylinder or fuel cell, thereby significantly increasing the power output of the internal combustion engine or fuel cell. Optionally, the energy stored in the exhaust gas of the internal combustion engine or fuel cell can be converted into electrical or mechanical energy by a power turbine. In this case, instead of a compressor, as in the case of an exhaust gas turbocharger, a generator or mechanical consumer is connected to the turbine shaft.

[0004] Due to the high process pressure in the turbine-side and compressor-side flow regions, the exhaust gas turbocharger shaft is sealed in a bearing housing cavity with a suitable sealing concept. Normally, the internal pressure in the bearing housing cavity corresponds to atmospheric pressure. However, the gas pressure in the compressor-side and turbine-side flow paths depends on the current operating point of the exhaust gas turbocharger and, at most operating points, is higher than the pressure in the bearing housing cavity. However, in certain cases, it is also necessary to take into account the vacuum during part-load operation or when shut down.

[0005] The rotating shaft of an exhaust gas turbocharger is usually supported by hydrodynamic fluid film bearings, and the required oil is taken from the oil supply of the internal combustion engine or, in the case of fuel cells, from an external oil source. In addition to supplying oil to the bearings, depending on the application, oil may also be used for cooling the air intake system or the power turbine. The lubricating oil supplied to the bearings and cooling holes (typically splash oil bores) accumulates inside the bearing housing and flows out of the bearing housing through a drain.

[0006] Shaft seals between bearing housings and turbines or compressors are used to prevent oil leakage into the gas paths of these components. Idle or partial load conditions of internal combustion engines are particularly important in terms of the oil's gas-tight behavior, since slight overpressures of only a few millibars can occur in the bearing housings at these operating conditions. These overpressures are often sufficient to create a positive pressure gradient across the shaft seal, meaning that the pressure in the bearing housing is higher than the pressure on the compressor or turbine side. Positive pressure gradients are often a major cause of oil leaks, as air and oil are drawn from the bearing housing through the seal and into the gas paths of these components. Oil in the seal area risks coking, resulting in increased wear and, in the worst case, can lead to failure of the seal and, therefore, the entire air intake system or the power turbine. Therefore, constant care must be taken to ensure that shaft seals function properly and seal efficiently. Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above, therefore, there exists a need for an improved shaft bearing assembly for a turbomachine shaft that at least partially overcomes the problems of the prior art. [Means for solving the problem]

[0008] In view of the above, there is provided a shaft bearing assembly according to independent claim 1. Further aspects, advantages and features are apparent from the dependent claims, the description and the accompanying drawings.

[0009] More specifically, according to one aspect of the present disclosure, a shaft bearing assembly for a turbomachine shaft is provided. The shaft bearing assembly includes a shaft having a radial step provided by the shaft or a separate element fixed to the shaft. The shaft bearing assembly further includes a bearing bush supporting the shaft. At least one of an axial surface of the bearing bush facing the radial step and an axial segment of the bearing bush has at least one groove opening into the bore. A radially outer side of the at least one groove is bounded by a radial sidewall, a radially inner side of the at least one groove is open, and a radial cross-sectional area of ​​the at least one groove increases toward the bore.

[0010] Thus, an improved shaft bearing assembly is provided compared to the prior art. In particular, the shaft bearing assembly beneficially provides improved oil tightness. Furthermore, embodiments of the shaft bearing assembly described herein allow for redirection of oil flow exiting the bearing, thereby helping to reduce internal oil loads on the shaft sealing within the bearing housing of the air supply system. Additionally, compared to the state of the art, the shaft bearing assembly described herein allows for a more compact design, particularly in the axial direction.

[0011] According to another aspect of the present disclosure, there is provided a turbomachine including a shaft bearing assembly according to any embodiment described herein. In particular, the turbomachine may be a turbocharger, a turbocompound, or an electric turbomachine.

[0012] So that the foregoing features of the present disclosure can be understood in detail, a more particular description of the disclosure briefly summarized above can be understood by reference to embodiments, the accompanying drawings of which relate to embodiments of the present disclosure. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic cross-sectional view of a shaft bearing assembly according to an embodiment described herein. [Figure 2] 1 is a schematic cross-sectional view of a shaft bearing assembly according to a further embodiment described herein. [Figure 3] 1 is a schematic perspective view of a bearing bushing according to an embodiment described herein; [Figure 4] An enlarged portion of FIG. 3 is shown. [Figure 5] 1 is a schematic cross-sectional view of a bearing bushing according to an embodiment described herein, showing an axial segment of the bearing bushing having at least one groove opening into a bore. [Figure 6] FIG. 6 is a cross-sectional front view taken along line AA shown in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0014] Reference will now be made in detail to various embodiments of the invention, one or more examples of which are illustrated in the drawings. Within the following description of the drawings, like reference numerals refer to like elements. Generally, only the differences relative to individual embodiments will be described. Each example is provided by way of explanation of the disclosure and not as a limitation thereof. Furthermore, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield still further embodiments. It is intended that the present invention include all such modifications and variations.

[0015] Within the following description of the drawings, the same reference numerals refer to the same or similar components. Generally, only differences relating to individual embodiments are described. Unless otherwise specified, the description of a part or aspect in one embodiment may also apply to the corresponding part or aspect in another embodiment.

[0016] 1 to 6, a shaft bearing assembly 10 for a turbomachine shaft 11 according to an embodiment of the present disclosure will be described.

[0017] According to an embodiment that can be combined with other embodiments described herein, the shaft bearing assembly 10 includes a shaft 11 having a radial step 111. The radial step 111 can be provided by the shaft or by a separate element fixed to the shaft. In particular, the radial step 111 can be an integral part of the shaft, or the radial step can be provided by a separate element attached to the shaft, such separate element rotating with the shaft during operation. For example, the separate element fixed to the shaft can be a sleeve. FIGS. 1 and 2 illustrate an example in which the radial step 111 is an integral part of the shaft 11. As shown in FIGS. 1 and 2, the radial step 111 is typically provided by a step from a first radius R1 to a second radius R2, where the second radius R2 is greater than the first radius R1. Typically, the second radius R2 is such that R2≧1.22×R1, particularly R2≧1.4×R1, and more particularly R2≧1.6×R1.

[0018] 1 and 2, the shaft bearing assembly 10 further includes a bearing bush 12 that supports the shaft 11. At least one of an axial surface 121 of the bearing bush 12 facing the radial step 111 and an axial segment 16 of the bearing bush 12 has at least one groove 122 that opens into a hole 123. In other words, the axial surface 121 of the bearing bush 12 facing the radial step 111 and / or the axial segment 16 of the bearing bush 12 has at least one groove 122 that opens into the hole 123. It should therefore be understood that only the axial surface 121 of the bearing bush 12 facing the radial step 111 can have at least one groove 122 opening into the bore 123, that only the axial segment 16 of the bearing bush 12 can have at least one groove 122 opening into the bore 123, or that both the axial surface 121 of the bearing bush 12 facing the radial step 111 and the axial segment 16 of the bearing bush 12 can each have at least one groove 122 opening into the bore 123. Figures 1 and 2 show exemplary embodiments in which at least one groove 122 is provided on the axial surface 121 facing the radial step 111. Figures 5 and 6 show exemplary embodiments in which at least one groove 122 is provided on the axial segment 16 of the bearing bush 12. The descriptions of the at least one groove 122 and the bore 123 in relation to Figures 3 and 4 can be applied to each of the embodiments in relation to Figures 1, 2, 5 and 6. Although not explicitly shown, it should be understood that two or more axial segments of the bearing bushing may be provided with at least one groove 122 as described herein in connection with axial segment 16.

[0019] Typically, the bearing bushing 12 has an axial width W x The radial height H of the bearing bush 12 relative to r The aspect ratio AR of the bearing bush is AR<1. The radial height H of the bearing bush is r can be understood as the difference between the outer radius of the bearing bush and the inner radius of the bearing bush. As can be seen for example in Figure 3, the axial width W xcan be understood as the extent of the bearing bush in the axial direction. Therefore, typically, the radial height H of the bearing bush r corresponds to the radial extent of the axial surface 121, as exemplarily shown in FIG. r typically corresponds to the radial wall thickness of the bearing bushing.

[0020] In the present disclosure, the at least one groove 122 may also be referred to as a conveyor groove. Additionally, the holes 123 may also be referred to as drain holes or drain bore holes. Thus, the phrase "at least one groove 122 opening into the holes 123" can be rephrased as "at least one conveyor groove opening into a drain hole." In this regard, it should be noted that the "conveyor groove" is configured to convey oil toward the drain hole. The drain hole is configured to drain oil from the conveyor groove, particularly toward the opposite axial surface of the bearing bushing. Furthermore, it should be understood that in operation, the shaft 11 rotates in a direction from the beginning of the at least one conveyor groove toward the drain hole of the at least one conveyor groove. For better understanding, in the case of the exemplary bearing bushing 12 shown in FIG. 3, the shaft (not shown in FIG. 3) extending through the central opening of the bearing bushing will rotate clockwise in operation.

[0021] In the present disclosure, an "axial segment of the bearing bushing" can be understood as a portion of the bearing bushing along the axial direction x. As exemplarily shown in Figures 1, 2, 3 and 5, it should be understood that the axial direction x is a direction extending along the central axis 17. Typically, the central longitudinal axes of the shaft 11 and the bearing bushing 12 coincide and correspond to the illustrated central axis 17.

[0022] 3 and 4 , according to an embodiment that may be combined with other embodiments described herein, the radially outer side of the at least one groove 122 is bounded by a radial sidewall 124. Typically, the radial sidewall 124 extends circumferentially along the length of the at least one groove 122. Typically, the radially inner side of the groove 122 is open. In particular, the radially inner open side of the groove 122 extends circumferentially along the length of the at least one groove 122. In other words, as shown in FIG. 4 , the radially outer side of the bottom 122B of the groove 122 is bounded by the radial sidewall 124, but the radially inner side of the bottom 122B of the groove 122 is not bounded.

[0023] According to an embodiment, which may be combined with other embodiments described herein, the radial cross-sectional area of ​​the at least one groove 122 increases towards the bore 123. It should be understood that the radial cross-sectional area of ​​the at least one groove 122 at a selected angular position relative to the central axis 17 of the bearing bush 12 is given by multiplying the radial width W of the at least one groove 122 by the depth D of the at least one groove 122 at the selected angular position. Thus, the radial cross-sectional area of ​​the at least one groove 122 can be changed by changing the radial width W of the at least one groove 122 and / or by changing the depth D of the at least one groove 122.

[0024] According to an embodiment, which may be combined with other embodiments described herein, the width W of the at least one groove 122 increases toward the hole 123. It should be understood that the width W of the at least one groove 122 may increase at least partially in the circumferential direction toward the hole 123. In other words, at least a circumferential segment of the at least one groove 122 may have a width W that increases in the direction toward the hole 123. Alternatively, the width W of the at least one groove 122 may increase in the circumferential direction toward the hole 123 over the entire circumferential extension of the at least one groove 122.

[0025] According to an embodiment, which may be combined with other embodiments described herein, the depth D of the at least one groove 122 increases towards the holes 123. It should be understood that the depth D of the at least one groove 122 may at least partially increase in the circumferential direction towards the holes 123. In other words, at least a circumferential segment of the at least one groove 122 may have a depth D that increases in the direction towards the holes 123. Alternatively, the depth D of the at least one groove 122 may increase in the circumferential direction towards the holes 123 over the entire circumferential extension of the at least one groove 122. It should be understood that according to an alternative embodiment, the depth D of the at least one groove 122 may be constant in the circumferential direction towards the holes 123, in particular over the entire circumferential extension of the at least one groove 122.

[0026] According to an embodiment, which can be combined with other embodiments described herein, the bore 123 extends from the bottom 122B of the at least one groove 122 through the bearing bush 12 to the opposite axial surface of the bearing bush 12. Typically, the bore 123 extends in the axial direction x of the shaft 11. It should be understood that the bore 123 can therefore extend parallel to the central axis 17 of the bearing bush 12.

[0027] According to an embodiment, which may be combined with other embodiments described herein, the at least one groove 122 extends in the circumferential direction over at least 10%, in particular at least 20%, of at least one of the axial surface 121 and the axial segment 16. In other words, the axial surface 121 facing the radial step 111 may comprise at least one groove 122 extending in the circumferential direction around the central axis 17 of the bearing bush 12 over at least 10%, in particular at least 20%, of the axial surface 121. Additionally or alternatively, the axial segment 16 may comprise at least one groove 122 extending in the circumferential direction around the central axis 17 of the bearing bush 12 over at least 10%, in particular at least 20%, of the axial segment 16.

[0028] According to embodiments that may be combined with other embodiments described herein, the at least one groove 122 comprises two or more grooves, in particular three or four or more grooves, more particularly four or five or more grooves. Typically, the grooves are evenly distributed circumferentially in the axial surface 121 of the bearing bush 12 facing the radial step 111 and / or in the axial segment 16 of the bearing bush 12. It should be understood that each of the features described in relation to the at least one groove 122 can also be applied to embodiments having two or more grooves. Each of the two or more grooves can therefore open into a respective discharge hole.

[0029] 3, according to an embodiment that can be combined with other embodiments described herein, the bearing bush 12 comprises at least one radial oil supply hole 126. Typically, the at least one radial oil supply hole 126 comprises two or more radial oil supply holes, in particular three or four or more radial oil supply holes. Typically, the two or more radial oil supply holes are evenly distributed in the circumferential direction.

[0030] 3, it should be understood that typically, the angular position of the radial oil supply holes 126 will be located between the angular positions of the discharge holes 123. It should be understood that the angular positions refer to angular positions about the central axis 17. In particular, the angular position of the radial oil supply holes 126 may be located between the discharge holes 123 of a first conveyor groove and the beginning of an adjacent second conveyor groove.

[0031] According to an embodiment that can be combined with other embodiments described herein, the bearing bush 12 is a fully floating bearing bush. Alternatively, the bearing bush 12 can be a semi-floating bearing bush. In particular, as exemplarily shown in FIG. 3 , a semi-floating bearing bush can have receiving portions 127 on the radially outer surface of the bearing bush 12 for receiving blocking elements that prevent the bearing bush 12 from rotating relative to the bearing flange 13. Typically, the radially outer surface of the bearing bush 12 can be provided with two or more receiving portions 127, for example, three or four or more receiving portions 127, each for receiving a blocking element. The two or three or more receiving portions 127 can be evenly distributed circumferentially around the central axis 17 of the bearing bush 12.

[0032] It should be understood that radial bearing bushings can therefore be designed as so-called full-floating or semi-floating bearings, depending on the rotordynamic requirements of the turbomachine. The difference is that full-floating bearing bushings rotate in the same manner as the shaft, at approximately half the shaft speed. In semi-floating bearings, the bearing bushing is fixed in position, and the lubrication gap between the bearing support and the bearing bushing functions purely as a squeeze film damper, with no oil film rotation. Full-floating bearings therefore have a nearly equal oil share between the inner and outer lubrication gaps. In contrast, semi-floating bearings exhibit a significantly unequal oil share, with up to 90% of the radial bearing's total oil consumption being carried by the inner lubrication gap.

[0033] 1 , according to an embodiment that may be combined with other embodiments described herein, the radially inner side of the axial surface 121 may include a chamfer 128. Typically, the chamfer 128 is provided around the entire radially inner periphery. Providing a chamfer as described herein is particularly beneficial for improving oil transport away from the radial step 111.

[0034] According to an embodiment that can be combined with other embodiments described herein, the shaft bearing assembly 10 includes a radial gap G1 between the shaft 11 and a bearing flange 13 that supports the bearing bushing 12. Alternatively, the radial gap G1 can be provided between a separate element 14 attached to the bearing flange 13 and the shaft 11. Typically, the gap G1 provides a throttle gap between the shaft seal side 101 and the shaft bearing side 102 of the shaft bearing assembly 10. As exemplarily shown in FIGS. 1 and 2, the axial position of the radial step 111 may correspond to the boundary between the shaft seal side 101 and the shaft bearing side 102. As schematically shown in FIGS. 1 and 2, a shaft seal 15 can be provided on the shaft seal side 101.

[0035] According to an embodiment that can be combined with other embodiments described herein, the radial gap G1 is 0.05 mm≦W G1 Radial width W ≦ 0.5 mm G1 It has.

[0036] According to an embodiment, which can be combined with other embodiments described herein, the radial width W G1 The ratio of the axial length L1 of the gap G1 to L1 / W G1 is 10≦L1 / W G1 ≦20, see L1 / W for details G1 =15±2.5.

[0037] 2, according to an embodiment that can be combined with other embodiments described herein, the bearing bush 12 has a radially outer, axially extending protrusion 129 that extends at least partially over the radial step 111 in order to provide a radial gap G2 between the axially extending protrusion 129 and a separate element (not shown) fixed to the shaft 11 or the shaft that provides the radial step 111. Typically, an axial gap G4 is provided between the protrusion 129 of the bearing bush and a separate element 14 attached to the bearing flange (configuration not shown) or the bearing flange 13 (configuration shown in FIGS. 1 and 2). However, it should be understood that if the axially extending protrusion 129 is implemented, the radial gap G1 and the axial gap G4 can be omitted.

[0038] According to an embodiment, which can be combined with other embodiments described herein, the radial width W G2 The ratio of the axial length L2 of the gap G2 to L2 / W G2 is 45≦L2 / W G2 ≦105, see L1 / W for details G2 =70±15.

[0039] According to an embodiment, which can be combined with other embodiments described herein, the ratio (R1-R2) / W G3 is 20≦(R1-R2) / W G3 ≦40, in detail (R1-R2) / W G3 = 30 ± 6, where R1 - R2 is the radial length of the axial gap G3 between the surface 121 of the bearing bush 12 facing the radial step 111 and the radial step 111, and W G3 is the axial width of the gap G3.

[0040] According to an embodiment that can be combined with other embodiments described herein, the radial gap G2 between the axially extending protrusion 129 and the shaft 11 is 0.025 mm≦W G2 Radial width W ≦ 0.5 mm G2 It has.

[0041] Providing one or more of the gaps G1, G2, G3 and G4 in accordance with the configuration described herein is beneficial in improving oil tightness at the interface between the bearing bushing 12 and the shaft 111.

[0042] It should be understood that the shaft bearing assembly embodiments described herein may be applied to any type of turbomachine, for example, turbocharger, turbocompound, or electric turbomachine.

[0043] Thus, according to another aspect of the present disclosure, there is provided a turbomachine, particularly at least one of a turbocharger, a turbocompound, and an electric turbomachine, including a shaft bearing assembly according to any embodiment described herein. For example, the electric turbomachine may be connected to a fuel cell.

[0044] In view of the above, it should therefore be appreciated that the embodiments described herein beneficially provide an improved shaft bearing assembly and an improved turbomachine. In particular, the embodiments of the present disclosure beneficially provide improved oil tightness. Furthermore, the embodiments described herein facilitate redirecting oil flow exiting the bearing, thereby helping to reduce internal oil loads on shaft seals within the bearing housing of the air charge system. Additionally, compared to the prior art, the embodiments of the present disclosure facilitate a more compact design, particularly in the axial direction.

[0045] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, which scope is determined by the following claims. [Explanation of symbols]

[0046] 10 Shaft bearing assembly 101 Shaft seal side 102 shaft bearing side 11 Shaft 111 Radial step 12 Bearing bush 121 Axial surface of bearing bush 122 Groove / Conveyor Groove 122B Bottom of groove 123 holes / discharge holes 124 Radial sidewall of groove 126 Oil supply hole 127 Reception Department 128 Chamfered part 129 Protrusion 13 Bearing flange 14 Separate Elements 15 Shaft seal 16 axis segments 17 Center axis 18 Entrance hole x-axis direction r radial direction R1 First radius R2 Second radius G1 Radial clearance between oil catch plate and shaft G2 Radial clearance between the bearing bush protrusion and the shaft G3 Axial clearance between the axial surface of the bearing bush facing the radial step of the shaft and the axial step surface G4 Axial clearance between the bearing bushing projection and the bearing flange or between the bearing bushing projection and a separate element attached to the bearing flange L1 Length of G1 L2 Length of G2 W groove width D Groove depth

Claims

1. A shaft bearing assembly (10) for a turbomachine shaft (11), comprising: The shaft (11) has a radial step (111) provided by the shaft or by a separate element fixed to the shaft, a bearing bush (12) supporting the shaft (11); Equipped with 1. A shaft bearing assembly (10), wherein at least one of an axial surface (121) of the bearing bush (12) facing the radial step (111) and an axial segment (16) of the bearing bush (12) has at least one groove (122) opening into a hole (123), wherein a radially outer side of the at least one groove (122) is bounded by a radial side wall (124), a radially inner side of the at least one groove (122) is open, and a radial cross-sectional area of ​​the at least one groove (122) increases towards the hole (123).

2. The shaft bearing assembly (10) of claim 1, wherein a width W of said at least one groove (122) increases toward said hole (123).

3. 3. A shaft bearing assembly (10) according to claim 1 or 2, wherein the hole (123) extends from a bottom of the at least one groove through the bearing bush (12) to an opposite axial surface of the bearing bush (12), in particular the hole (123) extends in the axial direction x of the shaft (11).

4. 4. A shaft bearing assembly (10) according to any one of claims 1 to 3, wherein the at least one groove (122) extends circumferentially over at least 10%, particularly at least 20%, of at least one of the axial surface (121) and the axial segment.

5. 5. The shaft bearing assembly (10) according to claim 1, wherein the at least one groove (122) comprises two or more grooves, particularly three or four or more grooves, more particularly four or five or more grooves, the grooves being evenly distributed in the circumferential direction in at least one of the axial surface (121) of the bearing bush (12) facing the radial step (111) and the axial segment of the bearing bush (12).

6. 6. A shaft bearing assembly (10) according to any one of claims 1 to 5, wherein the bearing bush (12) comprises at least one radial oil supply hole (126).

7. 7. A shaft bearing assembly (10) according to any one of claims 1 to 6, wherein the bearing bush (12) is a full-floating bearing bush or a semi-floating bearing bush, in particular the semi-floating bearing bush having a receiving portion (127) on the radial outer surface of the bearing bush (12) for receiving a blocking element for blocking rotation of the bearing bush (12) relative to the bearing flange (13).

8. A shaft bearing assembly (10) according to any one of the preceding claims, wherein the radially inner side of the axial surface (121) comprises a chamfer (128).

9. 9. The shaft bearing assembly (10) according to claim 1, further comprising a radial gap (G1) between the shaft (11) and a bearing flange (13) or a separate element (14) attached to the bearing flange (13) supporting the bearing bush (12), in particular the radial gap (G1) providing a throttle gap between a shaft seal side (101) and a shaft bearing side (102) of the shaft bearing assembly (10).

10. The radial gap (G1) is 0.05 mm≦W G1 Radial width W ≦0.5 mm G1 10. The shaft bearing assembly (10) of claim 9, comprising:

11. 11. The shaft bearing assembly (10) of claim 1, wherein the bearing bush (12) has a radially outer, axially extending protrusion (129) that extends at least partially over the radial step (111) to provide a radial gap (G2) between the axially extending protrusion (129) and the shaft (11).

12. The radial gap (G2) between the axially extending protrusion (129) and the shaft (11) is 0.025 mm≦W G2 Radial width W ≦0.5 mm G2 The shaft bearing assembly (10) of claim 11, comprising:

13. The bearing bush (12) has an axial width W x The radial height H of the bearing bush (12) relative to r and the radial height H of the bearing bush (12) is r 13. A shaft bearing assembly (10) according to any one of claims 1 to 12, wherein: is the difference between the outer radius of the bearing bush and the inner radius of the bearing bush.

14. A turbomachine, in particular at least one of a turbocharger, a turbocompound and an electric turbomachine, comprising a shaft bearing assembly (10) according to any one of claims 1 to 13.

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