The balancing of a core assembly which is formed by the bearing housing and by all of the parts mounted therein is work-intensive and expensive in particular owing to the adaptation of the devices of the balancing system to the large number of variants of the bearing housing ports and oil ports of an exhaust-gas turbocharger, and constitutes a time-consuming working step during the assembly process of the exhaust-gas turbocharger because every core assembly, after balancing, enters with the physically identical parts into the final assembly process of the exhaust-gas turbocharger.

It is therefore an object of the present invention to provide a standard bearing unit which makes it possible for the rotor to be balanced with little outlay in order thereby to simplify the assembly process for an exhaust-gas turbocharger.

Said object is achieved by means of the features of claim 1.

According to the invention, a standard bearing unit is formed which is independent of the respective application (geometry of the bearing housing), because the rotor to be balanced, composed of shaft, shaft nut, bearing bushings, seal and spacer elements, compressor wheel and turbine wheel, can be mounted in a standardized bearing sleeve with fixedly predefined outer dimensions (diameter and length) and balanced in a bearing housing which is a constituent part of the balancing machine. In this way, it is possible firstly for a standard bearing unit which is predefined with fixed dimensions to be combined with different customer-specific bearing housings at the final assembly stage, specifically independently of their oil port position and water cooling arrangement outlet position and independently of the compressor housing and turbine housing connections. To allow for all possible applications, it is secondly also possible for the standard bearing unit, while having the same outer dimensions, to be provided with different rotor components.

Claims 2 to 4 specify advantageous refinements of the invention.

Claim 5 defines a method for mounting a standard bearing unit according to the invention into an exhaust-gas turbocharger bearing housing.

Further details, features and advantages of the invention will emerge from the following description of exemplary embodiments of the invention on the basis of the drawing, in which:

Figure 1 shows a diagrammatic illustration of an exhaust-gas turbocharger, Figure 2 shows a perspective illustration of a standard bearing unit according to the invention, Figure 3 shows the standard bearing unit as per Figure 2 in a longitudinal section, Figure 4 shows two bearing housing halves in the unprocessed state, and

Figure 5 shows the bearing housing halves 11 as per Figure 4 in the finished machined state.

Figure 1 illustrates an exhaust-gas turbocharger 8 which can be provided with a standard bearing unit according to the invention, which will be described below. The exhaust-gas turbocharger 8 has a turbine 9 with a turbine wheel 5 in a turbine housing 10. The turbine wheel 5 is connected to a shaft 2 which, at its opposite end, bears a compressor wheel 3 of a compressor 11 which is arranged in a compressor housing 13.

The shaft 2 is mounted in a bearing housing 12 which is illustrated merely in very schematically highly simplified form in Figure 1.

Viewing Figures 2 and 3 together, it is possible to see the design of an embodiment of a standard bearing unit 1 according to the invention which can be used in the exhaust-gas turbocharger 8 as per Figure 1. The standard bearing unit 1 has the shaft 2 which is provided at a first end 4 with the compressor wheel 3 and which is connected at its second end 6 to the turbine wheel 5.

The shaft 2 is arranged in a standardized bearing sleeve 7 in which, as per the illustration of Figures 2 and 3, is arranged at least one bearing bushing 9 for guiding the shaft 2. Furthermore, the sectional illustration of Figure 3 shows two seal devices 14 and 15 for sealing off the bearing sleeve 7.

As a result of said design, a uniform standard bearing unit 1 is provided which can be mounted into a split bearing housing of a balancing machine (not illustrated) and balanced. Consequently, a balanceable standard bearing unit is provided which has the respective wheel pairs 3 and 5 which can be balanced independently of the final assembly process and respective application.

Figures 4 and 5 illustrate bearing housing halves 16 and 17 of the bearing housing 12 according to the invention. Here, Figure 4 shows the unprocessed state of the bearing housing halves 16 and 17, whereas Figure 5 shows the finished machined state of the bearing housing halves 16 and 17.

In addition to the vertical division of the bearing housing 12 as illustrated in

Figures 4 and 5, horizontal division is also possible.

If the standard bearing unit 1 described in detail with regard to Figures 2 and 3 is to be mounted in the bearing housing 12, the two bearing housing halves 16 and 17 are firstly produced.

Before or after said production process, the shaft 2, the compressor wheel 3, the turbine wheel 5 and the bearing sleeve 7, if appropriate with the bearing bushing 9 arranged therein, are preassembled to form a balanceable standard bearing unit. Said standard bearing unit can be balanced and subsequently mounted into the two housing halves 16 and 17, whereafter the housing halves 16 and 17 are subsequently sealed off.

In addition to the written disclosure of the invention above, reference is hereby made explicitly to the diagrammatic illustration of the invention in Figures 1 to 5.

LIST OF REFERENCE SYMBOLS

1 Standard bearing unit

2 Shaft

3 Compressor wheel

4 First end of the shaft 2

5 Turbine wheel

6 Second end of the shaft 2

7 Bearing sleeve

8 Exhaust-gas turbocharger

9 Bearing bushing

10 Turbine

10A Turbine housing

11 Compressor

12 Bearing housing

13 Compressor housing

14, 15 Sealing devices

16, 17 Bearing housing halves

18 Shaft nut

19 Outer diameter of the bearing sleeve

20 Bore diameter of the bearing sleeve

21, 22 Compressor wheel / turbine wheel diameter

23 Length of the bearing sleeve