COMBINED ANTI-FRICTION AND PLAIN BEARING MOUNTING FOR A GEARBOX SHAFT

Abstract

A transmission shaft (1), designed particularly for a wind turbine, which is mounted by way of a fixed bearing (2, 3) and at least one floating bearing (4). At least one gearwheel (5) is fixed onto the transmission shaft (1) and positioned in the axial direction between the fixed bearing (2, 3) and the floating bearing (4). The fixed bearing (2, 3) is formed by at least one roller bearing and the floating bearing (4) is in the form of at least one slide bearing.

Description

FIELD OF THE INVENTION

The present invention concerns the mounting of a transmission shaft, in particular a transmission shaft of a transmission of a wind turbine.

BACKGROUND OF THE INVENTION

To mount the spur gear stage of a transmission of a wind turbine, it is usual to use fixed and floating bearings. Both the fixed bearing and the floating bearing are in the form of roller bearings. The fixed bearing for absorbing radial and axial forces consists of a pair of aligned conical roller bearings. These can be prestressed, to prevent the occurrence of slip and ‘black spots’. The floating bearing is usually in the form of a cylindrical roller bearing. This is operated without prestress. Thus, the cylindrical roller bearing in particular is liable to sustain damage.

A possible means for making the mounting of shafts more resistant to damage are slide bearings. Thus solutions for wind turbine transmissions are known, in which all the shafts of the spur gear stage are mounted entirely in slide bearings. In this case slide bearings are also used for the fixed bearings. However, slide bearings that can absorb forces in both the radial and axial directions are very costly.

SUMMARY OF THE INVENTION

The purpose of the present invention is to design the mounting of a transmission shaft in such manner that the disadvantages of the solutions known from the prior art are avoided.

The invention is based on the idea of combining roller bearings with slide bearings on one and the same shaft. Roller and slide bearings each have specific advantages and disadvantages. Thus, when roller and slide bearings are combined their disadvantages are usually also combined. By virtue of the present invention, however, a mounting is produced in which the disadvantages of the individual bearing types are not noticeable. Instead, the mounting according to the invention for a transmission shaft benefits essentially from the advantages of roller bearings on the one hand and slide bearings on the other hand.

A transmission shaft according to the invention is mounted by means of a fixed bearing and at least one floating bearing. The fixed bearing can absorb radial and axial forces both in the positive and in the negative direction. Thus, all translational degrees of freedom of the shaft are restricted in the fixed bearing.

The floating bearing can absorb only radial forces, in both the positive and the negative direction. Thus, the floating bearing restricts the translational degrees of freedom of the shaft in just one direction. Together with the fixed bearing it also fixes the shaft along its rotational axis, i.e. it restricts rotational degrees of freedom of the shaft that extend perpendicularly to the rotational axis.

In the axial direction between the fixed bearing and the floating bearing is arranged at least one gearwheel fixed on the transmission shaft. The gearwheel is connected solidly to the transmission shaft. Thus, the rotational axis of the gearwheel is identical to the rotational axis of the transmission shaft. Preferably, the gearwheel is a spiral-toothed gear. The arrangement of the gearwheel in the axial direction between the fixed bearing and the floating bearing means that the gearwheel is in the intermediate space between the fixed bearing and the floating bearing. In particular, the orthogonal projections of the gearwheel on the rotational axis of the shaft are all between the orthogonal projections of the floating bearing on the rotational axis of the shaft and the orthogonal projections of the fixed bearing on the rotational axis of the shaft.

The fixed bearing is formed by at least one roller bearing. Preferably, the fixed bearing consists exclusively of roller bearings, in particular of exactly two roller bearings.

According to the invention, the floating bearing is formed by at least one slide bearing, preferably exactly one slide bearing.

In a preferred further development of the invention the fixed bearing is in the form of an in-line mounting arrangement. An in-line mounting comprises two bearings, each able to absorb forces in at least one axial direction. The two directions of the axial force absorption extend oppositely to one another, i.e. away from one another or toward one another. Preferably, the two bearings are arranged in a mirror-image configuration relative to one another. To set the desired bearing play or prestress, a bearing race—an inner or outer race—of one of the two bearings is pushed onto a seating and then fixed. Preferably two conical roller bearings are used. These can be in an O-configuration relative to one another, but are preferably in an X-configuration.

The transmission shaft according to the invention is particularly suitable for use in the spur gear stage of a transmission of a wind turbine. The transmission according to the invention can be used as an intermediate shaft. An intermediate shaft is understood to mean any shaft which is not the input or drive input shaft, or the output or drive output shaft.

Moreover, the transmission shaft according to the invention can be used as the input or drive input shaft, and/or the output or drive output shaft. In particular, use as the input or drive input shaft, and/or the output or drive output shaft in combination with use as an intermediate shaft is possible.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the invention are explained below with reference to FIG. 1.

In detail the one figure shows an intermediate shaft mounted by means of a roller bearing and a slide bearing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

On the right-hand side of the representation shown in FIG. 1, the intermediate shaft 1 is mounted by means of a fixed bearing. The fixed bearing consists of a first conical roller bearing 2 and a second conical roller bearing 3.

On the left-hand side of the figure, the intermediate shaft 1 is mounted by means of a floating bearing 4. In addition, the intermediate shaft 1 has a gearwheel 5. A further gearwheel—not shown in FIG. 1—is fixed on a shaft seating 6 by means of a keyway 7. Thus, in the axial direction the individual elements are arranged on the intermediate shaft 1—from left to right in FIG. 1—in the following order:

slide bearing 4, shaft seat 6, gearwheel 5, first conical roller bearing 2 and second conical roller bearing 3.

In the axial direction, the first conical roller bearing 2 and the second conical roller bearing 3 are fixed between a shoulder 8 in a transmission housing 9 and a bearing cover 10 bolted onto the transmission housing 9. FIG. 1 shows a fixing arrangement in which there is some play. Alternatively fixing with no play, i.e. with some prestress would be possible.

FIG. 1 shows two alternative possibilities for fixing the slide bearing 4. As shown in the upper part of FIG. 1, the transmission housing 9 can have a circular groove 11 extending around the rotational axis of the intermediate shaft 1. In this case the slide bearing 4 has on its outer surface a raised portion 12 that extends in the circumferential direction or a circumferential ridge 12 on the outer surface, which fits into the groove 11.

Alternatively, as shown in the lower portion of FIG. 1, the slide bearing 4 can be fixed by means of a radially directed, circular flange, which is part of the slide bearing 4 and extends around the rotational axis of the intermediate shaft. The flange 13 is bolted onto the transmission housing 9.

INDEXES

• 1 Intermediate shaft
• 2 Conical rover bearing
• 3 Conical roller bearing
• 4 Slide bearing
• 5 Gearwheel
• 6 Shaft seat
• 7 Keyway
• 8 Shoulder
• 9 Transmission housing
• 10 Bearing cover
• 11 Groove
• 12 Ridge
• 13 Flange

Claims

1-6. (canceled)

7. A transmission shaft (1), being mounted by at least one fixed bearing (2, 3) and at least one floating bearing (4), at least one gearwheel (5) being arranged on the transmission shaft (1) in an axial direction between the at least one fixed bearing (2, 3) and the at least one floating bearing (4),the fixed bearing (2, 3) being formed by at least one roller bearing, andthe floating bearing (4) is formed by at least one slide bearing.

8. The transmission shaft according to claim 7, wherein the at least one fixed bearing (2, 3) is in the form of an aligned mounting arrangement.

9. A transmission for a wind turbine comprising: at least one spur gear stage,the spur gear stage comprising at least one transmission shaft (1) that is mounted by at least one fixed bearing (2, 3) and at least one floating bearing (4),at least one gearwheel (5) being arranged on the transmission shaft (1) in an axial direction between the at least one fixed bearing (2, 3) and the at least one floating bearing (4), and the at least one fixed bearing (2, 3) being formed by at least one roller bearing, and the at least one floating bearing (4) being formed by at least one slide bearing.

10. The transmission according to claim 9, wherein the at least one transmission shaft is an intermediate shaft (1).

11. The transmission according to claim 9, wherein the at least one transmission shaft is an input shaft.

12. The transmission according to claim 9, wherein the at least one transmission shaft is an output shaft.

13. A bearing mounting for a transmission shaft of a wind turbine, the bearing mounting comprising: a slide bearing being axially arranged on a first side of a gearwheel that is fixed to the transmission shaft,the floating bearing being mounted to a housing and rotationally supporting the transmission shaft;a fixed bearing being axially arranged on an opposite second side of the gearwheel and mounted to the housing for rotationally supporting the transmission shaft; andthe fixed bearing comprising first and second conical roller bearings being arranged in a mirror-image configuration.