阅读说明：本技术 组装用于电机的具有改善刚度的传动系的方法 (Method for assembling a drive train with improved stiffness for an electric machine ) 是由 J·阿尔比苏亚马库亚 H·德卡洛斯阿莱格雷 M·杜兰德 P·伊里戈延埃斯科尔萨 R·雷皮索巴 于 2020-11-27 设计创作，主要内容包括：描述了一种用于电机的传动系。传动系包括轴。轴具有前端和后端,并且经由前轴承和后轴承支撑在壳体中,其中前轴承包括前轴承外环和前轴承内环,并且后轴承包括后轴承外环和后轴承内环。传动系包括：第一盖,其安装到壳体并且构造成密封前轴承的后侧,其中,第一盖通过将第一盖连接到壳体的辅助支撑件而安装到壳体；第二盖,其安装到壳体并且构造成密封后轴承的前侧；第三盖,其安装到壳体并且构造成密封后轴承的后侧,其中,后轴承外环由第二盖和第三盖压缩。壳体是单件式壳体,并且包括在第一盖与第二盖之间的进入窗。(A drive train for an electric machine is described. The drive train includes a shaft. The shaft has a forward end and a rearward end and is supported in the housing via a forward bearing and a rearward bearing, wherein the forward bearing comprises a forward bearing outer ring and a forward bearing inner ring and the rearward bearing comprises a rearward bearing outer ring and a rearward bearing inner ring. The power train includes: a first cover mounted to the housing and configured to seal a rear side of the front bearing, wherein the first cover is mounted to the housing by connecting the first cover to an auxiliary support of the housing; a second cover mounted to the housing and configured to seal a front side of the rear bearing; a third cover mounted to the housing and configured to seal a rear side of the rear bearing, wherein the rear bearing outer ring is compressed by the second cover and the third cover. The housing is a one-piece housing and includes an access window between the first cover and the second cover.)

1. A method of assembling a drive train (1) for an electric machine (18), the drive train (1) comprising a shaft (2), the shaft (2) having a front end and a rear end and being supported in a housing (3) via a front bearing (4) and a rear bearing (5), the front bearing (4) comprising a front bearing outer ring (41) and a front bearing inner ring (42), and the rear bearing (5) comprising a rear bearing outer ring (51) and a rear bearing inner ring (52), the method comprising the steps of:

a) -providing said shaft (2);

b) -mounting the front bearing (4) to the shaft (2) by temporarily heating the front bearing (4) and moving it to a forward position at the shaft (2);

c) arranging a first cover (6) and a second cover (7) at the shaft (2) from a rear end of the shaft (2), the first cover (6) being configured to seal a rear side of the front bearing (4) and the second cover (7) being configured to seal a front side of the rear bearing (5);

d) -mounting the rear bearing (5) to the shaft (2) by temporarily heating the rear bearing (5) and moving it from the rear end of the shaft (2) to a rear position at the shaft (2);

e) mounting the second cover (7) to the rear bearing outer ring (51);

f) mounting the housing (3) to the shaft (2) by temporarily heating the housing (3) and relatively moving the housing on the shaft (2) from a rear end of the shaft (2) until a housing abutment (31) abuts the second cover (7);

g) mounting the second cover (7) to the housing (3);

h) -detaching the second cover (7) from the rear bearing outer ring (51); and

i) mounting a third cover (8) to the housing (3) such that the rear bearing outer ring (51) is secured by the second cover (7) and the third cover (8), wherein the third cover (8) is configured to seal a rear side of the rear bearing (5).

2. The method according to the preceding claim, further comprising:

-connecting the first cover (6) to the housing (3) such that a first axial gap is maintained between the first cover (6) and the front bearing (4), in particular by mounting an auxiliary support (9) to the housing (3), which auxiliary support connects the first cover (6) to the housing (3).

3. The method according to the preceding claim, wherein:

the auxiliary support (9) is mounted by means of at least one access window (15) provided in the housing (3) between the first cover (6) and the second cover (7).

4. The method according to any of the preceding claims, comprising at least one of the following features:

in step e), mounting the second cover (7) to the rear bearing outer ring (51) by bolts (10), and in step h), dismounting the second cover (7) from the rear bearing outer ring (51) by releasing the bolts (10);

in step g), mounting the second cover (7) to the housing (3) by means of bolts (11);

in step i), mounting the third cover (8) to the housing (3) by means of bolts (12);

according to claim 2 or 3, the auxiliary support (9) is mounted to the housing (3) and to the first cover (6) by means of bolts (13).

5. The method of any preceding claim, further comprising:

after step i), mounting a ring (14) onto the shaft (2) such that the ring (14) is fixed and/or in contact with the rear bearing inner ring (52).

6. The method of any preceding claim, further comprising:

prior to step b), mounting a fourth cover (16) to the housing (3), the fourth cover (16) being configured to seal a front side of the front bearing (4), and in step b), moving the front bearing (4) from a rear end of the shaft (2) to a forward position at the shaft (2) such that a second axial gap is maintained between the fourth cover (16) and the front bearing (4).

7. The method of any one of the preceding claims,

at least one of the front bearing (4) and the rear bearing (5) comprises non-conical rolling elements (17), in particular spherical rolling elements.

8. The method of any one of the preceding claims,

the housing (3) is a one-piece housing.

9. The method of any preceding claim, further comprising:

a step of temporarily supporting the housing (3) by a jig between steps g) and h).

10. A drive train for an electric machine (18), the drive train (1) comprising:

a shaft (2) having a front end and a rear end and being supported in a housing (3) via a front bearing (4) and a rear bearing (5), wherein the front bearing (4) comprises a front bearing outer ring (41) and a front bearing inner ring (42), and the rear bearing (5) comprises a rear bearing outer ring (51) and a rear bearing inner ring (52);

a first cover (6) mounted to the housing (3) and configured to seal a rear side of the front bearing (4), wherein the first cover (6) is mounted to the housing (3) by an auxiliary support (9) connecting the first cover (6) to the housing (3);

a second cover (7) mounted to the housing (3) and configured to seal a front side of the rear bearing (5); and

a third cover (8) mounted to the housing (3) and configured to seal a rear side of the rear bearing (5), wherein the rear bearing outer ring (51) is fixed by the second cover (7) and the third cover (8); wherein

The housing (3) is a one-piece housing; and

the housing (3) comprises at least one access window (15) arranged between the first cover (6) and the second cover (7).

11. A power train as claimed in the preceding claim, wherein:

the first cover (6) is connected to the housing (3) such that a first axial gap is maintained between the first cover (6) and the front bearing (4).

12. A drive train according to any one of claims 10 and 11, comprising at least one of the following features:

the second cover (7) is mounted to the housing (3) by bolts (11);

the third cover (8) is mounted to the housing (3) by bolts (12);

the auxiliary support (9) is mounted to the housing (3) and the first cover (6) by bolts (13).

13. A power train as claimed in any one of claims 10 to 12, further comprising:

a ring (14) mounted to the shaft (2) such that the ring (14) secures and/or contacts the rear bearing inner ring (52).

14. A power train as claimed in any one of claims 10 to 13, further comprising:

a fourth cover (16) mounted to the housing (3) and configured to seal a front side of the front bearing (4), wherein a second axial gap is maintained between the fourth cover (16) and the front bearing (4).

15. A power train according to any one of claims 10 to 14, wherein,

at least one of the front bearing (4) and the rear bearing (5) comprises non-conical rolling elements (17), in particular spherical rolling elements.

Technical Field

The present invention relates to a method of assembling a drive train for an electric machine, and to such a drive train with improved stiffness. The electrical machine may be a generator of a wind turbine.

Background

FIG. 14 illustrates an example of a conventional configuration of a wind turbine 100. The wind turbine 100 includes a nacelle 30 and a tower 20. A nacelle 30 is mounted atop the tower 20. The nacelle 30 is rotatably mounted with respect to the tower 20 by means of a yaw bearing. The axis of rotation of the nacelle 30 with respect to the tower 20 is referred to as the yaw axis.

Wind turbine 100 also includes a hub 40 having three rotor blades 60 (two of which 60 are depicted in FIG. 14). The hub 40 is rotatably mounted with respect to the nacelle 30 by main bearings, i.e., a front bearing and a rear bearing described later. The hub 40 is mounted for rotation about a rotor axis of rotation 80.

Wind turbine 100 also includes a generator 18. The generator 18, in turn, includes a rotor that connects the generator 18 with the hub 40. Hub 40 is directly connected to generator 18, and thus wind turbine 100 is referred to as a gearless direct drive wind turbine. Such a generator 18 is referred to as a direct drive generator 18. Alternatively, the hub 40 may be connected to the generator 18 via a gearbox. This type of wind turbine 100 is referred to as a geared wind turbine. The present invention is applicable to both types of wind turbines 100.

The generator 18 is housed within the nacelle 30. The generator 18 is arranged and prepared for converting rotational energy from the hub 40 into electrical energy in the form of AC power.

The generator 18 includes a stator having at least one coil winding and a rotor having at least one permanent magnet and rotatable relative to the stator about a rotor axis by a rotor shaft 70 (fig. 15).

Fig. 15 shows a configuration of the drive train 1 including the generator 18 and connecting the generator 18 to the hub 40. The forward end of the rotor shaft 70 of the generator 18 is connected to a gearbox and a brake (both indicated by reference numeral 90, but they may be separate entities). The output shaft 2 of the gearbox 90, which is simply referred to as shaft 2, has a front end and a rear end. A hub 40 is connected at the front end of the shaft 2. The shaft 2 is supported within the housing via a front bearing 4 and a rear bearing 5. Reference numeral 33 denotes a base plate through which the drive train is supported. The base plate 33 may be part of the housing or may be connected to the housing. The front bearing 4 and the rear bearing 5 are sealed by bearing caps, thereby preventing grease in the front bearing and the rear bearing from leaking. At the same time, the bearing cap protects the front and rear bearings from dust.

Typically, the housing comprises a plurality of components which are assembled one after the other according to the assembly sequence of the bearing and the bearing cap.

Efforts have been made to achieve improved stiffness and/or reduced weight through the use of a one-piece housing. However, when a one-piece housing is used, Tapered Roller Bearings (TRB) must be used to achieve assembly. That is, in contrast to Spherical Roller Bearings (SRB), the inner and outer rings of the TRB bearing may be separated, which enables assembling a drive train for a generator. However, TRB bearings are more expensive than SRB bearings.

Disclosure of Invention

There may be a need for a drive train for an electric machine that has increased stiffness at low cost. This need may be met by the subject matter according to the independent claims. The invention is further developed as set forth in the dependent claims.

According to a first aspect of the invention, a method of assembling a drive train for an electrical machine, in particular for a generator of a wind turbine, is provided. The drive train includes a shaft having a front end and a rear end. The shaft is supported in the housing via a front bearing and a rear bearing. The front bearing includes a front bearing outer ring and a front bearing inner ring, and the rear bearing includes a rear bearing outer ring and a rear bearing inner ring. The method comprises the following steps: a) providing a shaft; b) mounting the front bearing to the shaft by temporarily heating the front bearing and moving it to a forward position at the shaft; c) providing a first cover and a second cover at the shaft from a rear end of the shaft, the first cover configured to seal a rear side of the front bearing and the second cover configured to seal a front side of the rear bearing; d) mounting the rear bearing to the shaft by temporarily heating the rear bearing and moving it from the rear end of the shaft to a rear position at the shaft; e) mounting the second cover to the rear bearing outer ring; f) mounting the housing to the shaft by temporarily heating the housing and relatively moving the housing over the shaft from the rear end of the shaft until a housing abutment abuts the second cover; g) mounting a second cover to the housing; h) removing the second cover from the rear bearing outer ring; and i) mounting the third cover to the housing such that the rear bearing outer ring is secured or compressed by the second and third covers. The third cover is configured to seal a rear side of the rear bearing.

In an embodiment, the method further comprises: the first cover is connected to the housing such that a first axial gap is maintained between the first cover and the front bearing, in particular by mounting an auxiliary support to the housing, which auxiliary support connects the first cover to the housing. In an embodiment, the auxiliary support is mounted through an access window in the housing between the first cover and the second cover.

In an embodiment, the method further comprises at least one of the following features: in step e), mounting the second cover to the rear bearing outer ring by bolts, and in step h), detaching the second cover from the rear bearing outer ring by loosening the bolts; in step g), mounting a second cover to the housing by bolts; in step i), mounting a third cover to the housing by bolts; and the auxiliary supporter is mounted to the case and the first cover by bolts.

In an embodiment, the method further comprises, after step i), mounting the ring to the shaft such that the ring is fixed and/or in contact with the rear bearing inner ring.

In an embodiment, the method further comprises, prior to step b), mounting a fourth cover to the housing, the fourth cover configured to seal a front side of the front bearing, and in step b), the front bearing is moved from a rear end of the shaft to a forward position at the shaft such that a second axial gap is maintained between the fourth cover and the front bearing.

In an embodiment, at least one of the front bearing and the rear bearing comprises non-tapered rolling elements, in particular spherical rolling elements.

In one embodiment, the housing is a one-piece housing.

In an embodiment, the method further comprises, between steps g) and h), the step of temporarily supporting the housing by means of a clamp.

According to a second aspect of the invention, a drive train for an electrical machine, in particular for a generator of a wind turbine, is provided. The power train includes: a shaft having a front end and a rear end, the shaft supported in the housing via a front bearing and a rear bearing, wherein the front bearing comprises a front bearing outer ring and a front bearing inner ring, and the rear bearing comprises a rear bearing outer ring and a rear bearing inner ring; a first cover mounted to the housing and configured to seal a rear side of the front bearing, wherein the first cover is mounted to the housing through an auxiliary support connecting the first cover to the housing; and a second cover mounted to the housing and configured to seal a front side of the rear bearing; a third cover mounted to the housing and configured to seal a rear side of the rear bearing, wherein the rear bearing outer ring is secured or compressed by the second cover and the third cover. The housing is a one-piece housing and includes an access window between the first cover and the second cover.

In an embodiment, the first cover is connected to the housing such that a first axial gap is maintained between the first cover and the front bearing.

In an embodiment, the drive train further comprises at least one of the following features: the second cover is mounted to the housing by bolts; the third cover is mounted to the housing by bolts; the auxiliary support is mounted to the housing and the first cover by bolts.

In an embodiment, the drive train further comprises a ring mounted to the shaft such that the ring is fixed and/or in contact with the rear bearing inner ring.

In an embodiment, the drive train further comprises a fourth cover mounted to the housing and configured to seal a front side of the front bearing, wherein a second axial gap is maintained between the fourth cover and the front bearing.

In an embodiment, at least one of the front bearing and the rear bearing comprises non-tapered rolling elements, in particular spherical rolling elements.

According to the invention, the stiffness of the drive train assembly may be increased compared to conventional designs of two-or multi-part bearing housings. The bolted joint connection between the casing and the main frame may also be improved.

According to the invention, the conventional or current design of the front and rear main bearings may be maintained in the shape of Spherical Roller Bearings (SRB). Also, the conventional or current design of the lid (seal) may be maintained. Further, conventional or current tools for assembly may be maintained. The access window enables access for maintainability of the drive train throughout its life.

For a four-point suspension motor, the load transfer capacity from the rotor shaft to the machine frame can be increased. The weight of the main frame may be reduced and the number of bolts in the housing/main frame interface may also be reduced.

It has to be noted that embodiments of the invention have been described with reference to different subject-matters. In particular, some embodiments have been described with reference to apparatus type claims, while other embodiments have been described with reference to method type claims. However, a person skilled in the art will gather from the above and the following description that, unless other notified, in addition to any combination of features belonging to one type of subject-matter also any combination between features relating to different subject-matters, in particular between features of the apparatus type claims and features of the method type claims, is considered to be disclosed with this application.

Drawings

The above-described and other aspects of the present invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited.

FIG. 1 illustrates a perspective view of a portion of a drive train for a generator, according to an embodiment;

FIG. 2 shows a cross-sectional view of a portion of a drive train according to an embodiment;

fig. 3 shows a perspective cross-sectional view of a front bearing of the drive train according to the embodiment;

fig. 4 shows a perspective cross-sectional view of a rear bearing of the drive train according to the embodiment;

FIG. 5 shows a schematic cross-sectional view of a drivetrain during a method of manufacturing the drivetrain, in accordance with an embodiment;

FIG. 6 shows a schematic cross-sectional view of a drivetrain during a method of manufacturing the drivetrain, in accordance with an embodiment;

FIG. 7 shows a schematic cross-sectional view of a drivetrain during a method of manufacturing the drivetrain, in accordance with an embodiment;

FIG. 8 shows a front view of the rear bearing outer ring;

FIG. 9 shows a schematic cross-sectional view of a rear bearing and a second cover according to an embodiment;

FIG. 10 shows a schematic cross-sectional view of a drivetrain during a method of manufacturing the drivetrain, in accordance with an embodiment;

FIG. 11 shows a schematic cross-sectional view of a drivetrain during a method of manufacturing the drivetrain, in accordance with an embodiment;

FIG. 12 shows a schematic cross-sectional view of a rear bearing and a second cover according to an embodiment;

fig. 13 shows a schematic cross-sectional view of a generator during a method of manufacturing the generator according to an embodiment;

FIG. 14 shows a configuration of a wind turbine and its different elements; and

fig. 15 shows a configuration including a drive train and a generator.

Detailed Description

The illustration in the drawings is schematically. Note that in different figures, similar or identical elements are provided with the same reference numerals.

Fig. 1 shows a perspective view of a part of a drive train 1 according to an embodiment; fig. 2 shows a sectional view of a part of the drive train 1 according to the embodiment; fig. 3 shows a perspective cross-sectional view of the front bearing 4 of the drive train 1 according to an embodiment; and fig. 4 shows a perspective cross-sectional view of the rear bearing 5 of the drive train 1 according to this embodiment. The drive train 1 is intended for a generator 18 of a wind turbine.

The drive train 1 comprises a shaft 2. The shaft 2 includes a flange 22 to which a hub 40 (fig. 15) may be bolted. The shaft 2 further comprises a hollow shaft portion 21 having a front end and a rear end and supported in the housing 3 via a front bearing 4 and a rear bearing 5. The hollow shaft portion 21 may be connected directly to the generator 18 or to the gearbox 90 (fig. 15). The housing 3 comprises a plurality of holder parts 32 by which the housing 3 can be fixed to a (main) frame, such as a bottom plate 33.

The front bearing 4 comprises a front bearing outer ring 41 and a front bearing inner ring 42, and the rear bearing 5 comprises a rear bearing outer ring 51 and a rear bearing inner ring 52.

The first cover 6 is mounted to the housing 3 and configured to seal the rear side of the front bearing 4. The first cover 6 is mounted to the housing 3 by an auxiliary support 9 connecting the first cover 6 to the housing 3. The auxiliary support 9 is mounted to the housing 3 and the first cover 6 by bolts 13. The first cover 6 is mounted to the housing 3 such that a first axial gap is maintained between the first cover 6 and the front bearing 4.

The second cover 7 is mounted to the housing 3 and configured to seal the front side of the rear bearing 5, wherein the second cover 7 is mounted to the housing 3 by bolts 11. The third cover 8 is mounted to the housing 3 and configured to seal the rear side of the rear bearing 5. The third cover 8 is mounted to the housing 3 by bolts 12. The rear bearing outer ring 51 is fixed (i.e., compressed) between the second and third covers 7, 8, so that the rear bearing 5 functions as a fixed bearing.

The fourth cover 16 is mounted to the housing 3 and is configured to seal the front side of the front bearing 4, with a second axial gap maintained between the fourth cover 16 and the front bearing 4, such that the front bearing 4 acts as a floating bearing. Each of the first to fourth covers 6, 7, 8, 16 includes a shaft seal at an inner circumferential portion thereof. Thereby, the front bearing 4 and the rear bearing 5 are sealed by the first to fourth covers 6, 7, 8, 16, so that the grease in the front bearing 4 and the rear bearing 5 is prevented from leaking. Meanwhile, the first to fourth covers 6, 7, 8, 16 protect the front bearing 4 and the rear bearing 5 from dust and dirt.

The housing 3 is a one-piece housing and comprises at least one access window 15 between the first cover 6 and the second cover 7. The access window 15 is used for assembling and maintaining the drive train 1. The access window 15 enables access for maintainability of the drive train 1 during the entire life of the drive train 1 and does not need to be closed during operation, since the front bearing 4 and the rear bearing 5 are well covered by the first to fourth covers 6, 7, 8, 16. The housing 3 may comprise at least two access windows 15 configured for access of the left and right arms of a user.

The drive train 1 further comprises a ring 14 (fig. 13) mounted to the shaft 2 such that the ring 14 fixes the rear bearing inner ring 52. Ring 14 may contact rear bearing inner ring 52.

As can be seen from fig. 3 and 4, the front bearing 4 and the rear bearing 5 comprise non-conical rolling elements 17, in particular spherical rolling elements. Since the drive train 1 according to the invention has the access window 15 and the auxiliary support 9, spherical rolling elements 17 (SRB) can be used instead of conical rolling elements (TRB), although the housing 3 is a one-piece housing. SRB is cheaper than TRB.

Fig. 5 shows a schematic cross-sectional view of the drive train 1 according to the embodiment during a method of manufacturing the drive train. In a first step, a shaft 2 is provided. A fourth cover 16 is mounted to the housing 3, wherein the fourth cover 16 is configured to seal the front side of the front bearing 4. Then, from the rear end of the shaft 2, the front bearing 4 is mounted to the shaft 2 by temporarily heating the front bearing 4 and moving it to a front position at the shaft 2. The front bearing 4 may be heated to 150 ℃ (max), wherein the temperature difference Δ t between the front bearing outer ring 41 and the front bearing inner ring 42 may be less than 25 ℃.

The front bearing 4 is moved from the rear end of the shaft 2 to a position forward of the shaft 2 so that a second axial gap can be maintained between the fourth cover 16 and the front bearing 4.

Fig. 6 shows a schematic cross-sectional view of a power train 1 during a method of manufacturing the power train according to an embodiment; and fig. 7 shows a schematic cross-sectional view of the drive train 1 during a method of manufacturing the drive train according to the embodiment. A first cover 6 and a second cover 7 are arranged at the shaft 2 from the rear end of the shaft 2, wherein the first cover 6 is configured to seal the rear side of the front bearing 4 and the second cover 7 is configured to seal the front side of the rear bearing 5. The rear bearing 5 is mounted on the shaft 2 by temporarily heating the rear bearing 5 and moving it from the rear end of the shaft 2 to a position rearward of the shaft 2. The rear bearing 5 may be heated to 150 c (max), wherein the temperature difference deltat between the rear bearing outer ring 51 and the rear bearing inner ring 52 may be less than 30 c. The final position of the rear bearing 5 is reached when the rear bearing 5 abuts a shoulder 23 provided at the shaft 2.

Fig. 8 shows a front view of the rear bearing outer ring 51; and fig. 9 shows a schematic cross-sectional view of the rear bearing 5 and the second cover 7 according to the embodiment. Here, the second cover 7 is mounted to the rear bearing outer ring 51 by bolts 10. Three bolts 10, for example three M16 bolts, may be used. The rear bearing outer ring 51 includes three threaded holes for receiving three bolts 10.

Fig. 10 shows a schematic cross-sectional view of the drive train 1 during a method of manufacturing the drive train according to the embodiment. The housing 3 is mounted to the shaft 2 by temporarily heating the housing 3 and causing it to move relatively on the shaft 2 from the rear end of the shaft 2 until the housing abutment 31 abuts the second cap 7. The housing abutment 31 may have the shape of a shoulder. The housing 3 may be heated to 110 ℃ (max), wherein the temperature difference Δ t between the housing 3 and the bearings 4, 5 may be more than 40 ℃. Preferably, the shaft 2 is oriented vertically in the method step of fig. 10, and more preferably also in other method steps.

Fig. 11 shows a schematic cross-sectional view of the drive train 1 according to the embodiment during a method of manufacturing the drive train. The second cover 7 is mounted to the housing 3 by bolts 11 (see fig. 2). For this purpose, the user is entered through the access window 15. Alternatively, the housing 3 may be temporarily supported by a jig (not shown), so that the weight of the housing 3 acting axially on the rear bearing outer ring 51 is reduced.

Fig. 12 shows a schematic cross-sectional view of the rear bearing 5 and the second cover 7 according to an embodiment. By loosening the bolts 10, the second cover 7 is detached from the rear bearing outer ring 51.

Fig. 13 shows a schematic cross-sectional view of the drive train 1 during a method of manufacturing the drive train according to the embodiment. The third cover 8 is mounted to the housing 3 by bolts 12 (fig. 2) such that the rear bearing outer ring 51 is fixed (i.e., compressed) by the second and third covers 7, 8, wherein the third cover 8 is configured to seal the rear side of the rear bearing 5.

The ring 14 is mounted to the shaft 2 such that the ring 14 is fixed and/or in contact with the rear bearing inner ring 52. Thereby, the rear bearing inner ring 52 is axially fixed between the ring 14 and the shoulder 23 of the shaft 2. As a result, the ring 14 and the shoulder 23 provide a form-fit fixation (form-fit fixation) of the rear bearing inner ring 52, while the rear bearing inner ring 52 is additionally held in place by a force-fit fixation (form-fit fixation) which is achieved by cooling the rear bearing 5 after the step of temporarily heating the rear bearing 5 in fig. 6. In alternative embodiments, the rear bearing 5 may be held in place by a form-fitting combination of the ring 14 and the shoulder 23 or by a force-fitting fixation achieved by cooling the rear bearing 5.

As shown in fig. 3, the first cover 6 is connected to the housing 3 such that a first axial gap is maintained between the first cover 6 and the front bearing 4, in particular by mounting an auxiliary support 9 to the housing 3, which auxiliary support 9 connects the first cover 6 to the housing 3. The auxiliary support 9 is mounted through an access window 15 (fig. 1) provided in the housing 3 between the first and second covers 6, 7. The auxiliary support 9 is mounted to the housing 3 and the first cover 6 by bolts 13. The auxiliary support 9 does not have a ring shape. Preferably, the auxiliary support 9 has the shape of a plate, more preferably a ring segment. In any case, the access window 15 is dimensioned so that the auxiliary support 9 can pass through.

In a modified embodiment, the fourth cover 16 does not have to be mounted before step b), but it can be mounted at any time, as long as there is access to the portion of the housing 3 where the fourth cover 16 is to be mounted.

In this description, the terms "front" and "rear" do not necessarily relate to the drive end, on which the flange 22 is normally arranged, and to the non-drive end of the drive train 1, on which the end of the hollow shaft portion 21 is located. Although in the illustrated embodiment the rear bearing 5 is a fixed bearing and the front bearing 4 is a floating bearing, in alternative embodiments the fixed bearing and the floating bearing may be interchanged. That is, although the depicted embodiment has the flange 22 at the forward end of the shaft 2, in an alternative embodiment, the flange 22 may be disposed at the rearward end of the shaft 2. The term "front" refers to the left-hand side of the figure, and the term "rear" refers to the right-hand side of the figure.

It should be noted that the term "comprising" does not exclude other elements or steps and the "a" or "an" does not exclude a plurality. Furthermore, elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims shall not be construed as limiting the scope of the claims.