Segmented sliding bearing

Abstract

A segmented sliding bearing (1) comprises multiple groups (4, 5) of axial bearing segments (3) which are intended for absorbing axial forces acting in a shaft (10) and are offset from one another in the axial direction of the shaft (10). Operating conditions cause the shaft (10) to curve, with the result that a shaft centre line (WM) deviates from a prevailing axis of rotation (RA) of the shaft (10) when free of load. The maximum deviation of the curved shaft centre line (WM) from the axis of rotation (RA) prevails between the different groups (4, 5) of axial bearing segments (3).

Description

[0001] Segmented sliding bearing

[0002] The invention relates to a segmented plain bearing which is suitable, among other things, for use in a wind turbine.

[0003] A plain bearing device, which is designed in particular for supporting a rotor hub of a wind turbine, is known, for example, from DE 10 2017 006 957 A1. The known plain bearing device comprises plain bearing pads positioned at an angle to their central axis, which are radially and / or axially resiliently attached to a ring element.

[0004] Another segmented plain bearing, i.e., one comprising individual bearing segments, is disclosed in DE 10 2017 223 370 A1. This is an adjustable plain bearing, which is said to be characterized by a variable lubrication gap thickness.

[0005] A wind turbine described in EP 2 474 733 B1 comprises a blade bearing assembly designed as a plain bearing assembly. Several arcuate plates define fluid cavities of the bearing.

[0006] WO 2019 / 120870 A1 describes a plain bearing assembly intended for use in a wind turbine, including a sensor system. The sensor system may include an oil level sensor or an ultrasonic sensor that detects any air inclusions in the oil.

[0007] DE 10 2016 203 147 A1 concerns a hydrodynamic plain bearing whose outer ring, like its inner ring, has a spherical surface. This allows tilting of the inner ring relative to the outer ring. DE 2 045 675 A describes a plain bearing designed as a thrust bearing for rotors of heavy turbomachinery, particularly for steam turbine rotors. It is assumed that changes in the operating deflection lines of the rotors can occur during operation of such machines. To accommodate such geometric changes, it is proposed to design parts of a bearing housing with elastic springs.

[0008] DE 10 2016 209 206 A1 deals with a wind turbine in which a rotor hub and a generator rotor share a common main bearing. The main bearing comprises two bearing sections offset from each other in the axial direction, with each bearing section comprising an axial plain bearing and a radial plain bearing.

[0009] The invention is based on the object of specifying a segmented plain bearing which is particularly suitable for applications in which operational deformations are to be expected.

[0010] This object is achieved according to the invention by a segmented plain bearing having the features of claim 1. According to claim 9, the plain bearing is particularly suitable for use in a wind turbine.

[0011] The plain bearing assembly according to the application comprises several groups of axial bearing segments, which are designed to absorb axial forces acting on a shaft and are offset from one another in the axial direction of the shaft. During operation of the plain bearing assembly, the shaft is bent at least minimally, but to a technically relevant extent, due to the forces acting on it, so that the actual shaft centerline deviates from a theoretical axis of rotation of the shaft in the load-free state. The maximum deviation of the curved shaft centerline from the axis of rotation occurs between the various groups, in particular two groups, of axial bearing segments. Conversely, this means that each group of axial bearing segments is located on a section of the shaft in which the operationally curved shaft is not maximally deflected from its theoretical ideal position.In particular, each group of axial bearing segments is arranged in a section of the shaft in which the deflected shaft centerline intersects the axis of rotation.

[0012] The invention is based on the idea that bearing segments, i.e., pads intended for axial support, can be sensitive to tilting of the mounted shaft. This circumstance is addressed in the prior art by mounting the individual pads in a tiltable manner. This also applies to plain bearing segments used in conventional bearing arrangements that are intended for radial support of a shaft.

[0013] In a departure from such common concepts, the solution according to the application considers the deformed shape of the mounted shaft during real operation. Put simply, it is proposed to place the axial bearing segments, which are grouped together in a plane perpendicular to the shaft, in areas of a bending line that can be considered a neutral axis. Measures that allow tilting of the individual axial bearing segments can thus be simplified or even completely eliminated compared to older concepts.

[0014] According to various possible embodiments, one of the groups of axial bearing segments is arranged on one end face of the shaft, while another group of axial bearing segments is spaced apart from both end faces of the shaft. The number of groups of axial bearing segments is not limited to two. For example, three, four, or more such groups of axial bearing segments are arranged along the shaft. Possible further developments provide for the plain bearing to comprise a radial bearing in addition to the axial bearing segments. The radial bearing, like the axial bearing, can be designed as a hydrodynamic plain bearing, in particular in the form of a segmented bearing.

[0015] Regardless of the presence of radial bearing elements, especially in the form of individual pads, several axial bearing segments belonging to one and the same group of bearing segments can be arranged at the level of the rotation axis. This positioning of the axial bearing segments allows for particularly small deformations to be accommodated during actual operation of the system, for example, a wind turbine, which includes the segmented plain bearing. In this case, the axial bearing segments are referred to as being arranged in the 3 o'clock and 9 o'clock positions.

[0016] In a slightly modified design, there are two pairs of thrust bearing pads belonging to one and the same group of bearing pads. One of the two pairs of pads is positioned above a horizontally aligned plane in which the axis of rotation lies, and the other pair of thrust bearing pads is positioned below this plane. Thus, the first pair of thrust bearing pads is located slightly above the 3 or 9 o'clock position, and the other pair of pads is located slightly below the 3 or 9 o'clock position.

[0017] All axial bearing segments intended for axial support and belonging to a specific group of bearing segments, for example, two or four, can engage in the same circumferential groove formed in the shaft. The individual axial bearing segments belonging to the same group of bearing segments can have a uniform or non-uniform shape.

[0018] In all embodiments, the segmented plain bearing can include devices for supplying lubricant, particularly in the form of a lubricant pump, which supplies the sliding contacts between the axial bearing segments, and possibly also the radial bearing segments, and the shaft via connected lubricant channels. Optionally, measuring devices are also provided, for example, for temperature or force measurement or for measuring the composition of the lubricant.

[0019] Several embodiments of the invention are explained in more detail below with reference to a drawing. In the drawings:

[0020] Fig. 1 shows a first embodiment of a segmented plain bearing in side view,

[0021] Fig. 2 Components of a segmented plain bearing modified compared to Figure 1 in front view,

[0022] Fig. 3 shows another segmented plain bearing in a representation analogous to Fig. 2.

[0023] Unless otherwise stated, the following explanations apply to all embodiments. Corresponding or essentially equivalent parts are identified by the same reference numerals in all figures.

[0024] A segmented plain bearing, designated overall by the reference numeral 1, is designed as a hydrodynamic plain bearing and is intended for use in a wind turbine (not shown in detail). The plain bearing 1 always comprises an axial bearing 2, and in the case according to Fig. 2, additionally a radial bearing 8. A shaft 10 supported by the plain bearing 1 is supported in the axial direction on a housing element 7. Overall, the plain bearing 1 is designed as a main rotor bearing. The axial bearing 2 comprises a plurality of axial bearing segments 3, which are also referred to as pads for short. This consists of a first group 4 of axial bearing segments 3 and a second group 5 of axial segments 3. The two groups 4, 5 are offset from one another in the axial direction of the plain bearing 1, i.e. in the longitudinal direction of the axis of rotation of the shaft 10, designated RA.The rotation axis RA refers to the ideal, unloaded situation of the sliding bearing 1. During actual operation of the wind turbine, including the sliding bearing 1, the shaft 10 undergoes deformation, particularly due to wind forces and gravity, which is exaggerated in Fig. 1. Wil denotes the non-curved, ideal shaft contour. The dashed shaft contour WK exaggerates the actual, curved shape of the shaft 10. WM denotes the curved shaft centerline belonging to the shaft contour WK. In the exemplary embodiments, the shaft centerline WM approximately describes a sinusoidal shape.

[0025] As can be seen from Fig. 1, but also applies to the embodiments according to Figs. 2 and 3, each group 4, 5 of bearing segments 3 is located at a point where the curved shaft centerline WM intersects the geometrically ideal rotational axis RA. This ensures that the pads 3 of the axial bearing 2 are exposed almost exclusively to the axial loads to be absorbed, while further, undesirable loads are largely avoided.

[0026] The first group 4 of axial bearing segments 3 is located on an end face of the shaft 10, contacting the housing element 7. In contrast, the second group 5 of axial bearing segments 3 is spaced apart from the aforementioned end face of the shaft 10 and also from the opposite end face (not shown). The pads 3 of the second group 5 of the axial bearing 2 engage in a circumferential groove 6 of the shaft 10. The point of maximum deviation, designated MA, between the shaft centerline WM and the rotational axis RA lies - viewed in the longitudinal direction of the shaft 10 - centrally between the two groups 4, 5 of axial bearing segments 3. dM denotes the maximum distance, given at point MA, between the shaft centerline WM and the rotational axis RA. In Fig. 2, in addition to the axial bearing segments 3, several radial bearing segments 9 are indicated, which are attributable to the radial bearing 8 already mentioned.Since in the present case it is primarily weight forces that need to be supported, the radial bearing segments 9, which are also generally referred to as pads, are located below the axis of rotation RA. Such radial bearing segments 9, also at other points on the circumference of the shaft 10, can also be present in the embodiments according to Figs. 1 and 3. As can be seen from Fig. 2, both axial bearing segments 3 present in this configuration are located at the level of the axis of rotation RA. This keeps changes in the geometric conditions resulting from the deflection of the shaft 10 particularly small. For the sake of simplicity, the axial bearing segments 3 are arranged in the region of the neutral axis of the deflected shaft 10.

[0027] In contrast to the arrangement according to Fig. 2, in the embodiment according to Fig. 3, a total of four axial bearing segments 3 are assigned to the same group 5 of pads 3. In this case, one pair of axial bearing segments 3 is located slightly below the rotational axis RA, and another pair of axial bearing segments 3 is located slightly above the rotational axis RA. Thus, in this case, too, influences resulting from the deflection of the shaft 10 on the axial bearing 2 are minimized. In each of the embodiments according to Figs. 1 to 3, the plain bearing 1 can be equipped with sensors, in particular force measurement technology.

[0028] List of reference symbols

[0029] 1 plain bearing

[0030] 2 axial bearing

[0031] 3 Axial bearing segment, pad

[0032] 4 first group of axial bearing segments

[0033] 5 second group of axial bearing segments

[0034] 6-round groove

[0035] 7 Housing element

[0036] 8 Radial bearing

[0037] 9 Radial bearing segment, pad

[0038] 10 Shaft dM maximum distance between shaft centerline and rotation axis

[0039] MA Point of maximum deviation of the shaft center line from the rotation axis

[0040] RA rotation axis

[0041] WK wave contour, curved

[0042] WU wave contour, uncurved

[0043] WM wave centerline

Claims

Patent claims 1. Segmented plain bearing (1), comprising several groups (4, 5) of axial bearing segments (3) which are provided for absorbing axial forces acting in a shaft (10) and are offset from one another in the axial direction of the shaft (10), wherein - the shaft (10) is bent due to operation, so that a shaft center line (WM) deviates from a rotation axis (RA) of the shaft (10) given in the load-free state, - the maximum deviation of the curved shaft center line (WM) from the axis of rotation (RA) is given between the different groups (4, 5) of axial bearing segments (3).

2. Plain bearing (1) according to claim 1, characterized in that each group (4, 5) of axial bearing segments (3) is arranged in a section of the shaft (10) in which the bent shaft center line (WM) intersects the axis of rotation (RA).

3. Plain bearing (1) according to claim 1 or 2, characterized in that one of the groups (4) of axial bearing segments (3) is arranged on one end face of the shaft (10), whereas a further group (5) of axial bearing segments (3) is spaced from both end faces of the shaft (10).

4. Plain bearing (1) according to one of claims 1 to 3, characterized in that it comprises a radial bearing (8) in addition to the axial bearing segments (3).

5. Plain bearing (1) according to claim 4, characterized in that the radial bearing (8) is also designed as a segmented plain bearing.

6. Plain bearing (1) according to one of claims 1 to 5, characterized in that several axial bearing segments (3), which are assigned to one and the same group (4, 5) of bearing segments (3), are arranged at the level of the axis of rotation (RA).

7. Plain bearing (1) according to one of claims 1 to 5, characterized in that two pairs of axial bearing segments (3), which are to be assigned to one and the same group (4, 5) of bearing segments (3), in one case above a horizontally aligned plane in which the axis of rotation (RA) lies, and in the other case are placed below the said plane.

8. Plain bearing (1) according to claim 6 or 7, characterized in that all axial bearing segments (3) provided for axial bearing and assigned to a specific group (4, 5) of bearing segments (3) engage in one and the same circumferential groove (6) formed in the shaft (10).

9. Use of a plain bearing (1) according to claim 1 in a wind turbine.

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