Fluid film bearing and wind turbine

Abstract

Provided is a fluid film bearing, for a rotor hub in a wind turbine, including a first and second part rotatably connected to each other, wherein the first part forms a first annular sliding surface that extends in the circumferential direction of the bearing along the first part, wherein the second part includes a support structure and first pads distributed along the circumference of the support structure, wherein a respective pad sliding surface of each of the first pads or of a first subgroup of the first pads supports the first annular sliding surface, wherein each first pad includes a mounting section that is mounted to a backside of the support structure, a contact section that is either forming the respective pad sliding surface or carrying a coating that forms the respective pad sliding surface and a connecting section that connects the contact section with the mounting section.

Claims

1. A fluid film bearing, for a rotor hub in a wind turbine, comprising a first and second part rotatably connected to each other, wherein the first part forms a first annular sliding surface that extends in the circumferential direction of the bearing along the first part, wherein the second part comprises a support structure and first pads distributed along the circumference of the support structure, wherein a respective pad sliding surface of each of the first pads or of a first subgroup of the first pads supports the first annular sliding surface, wherein each first pad comprises a mounting section that is mounted to a backside of the support structure that is facing away from the first part, a contact section that is either forming the respective pad sliding surface or carrying a coating that forms the respective pad sliding surface and a connecting section that connects the contact section with the mounting section and that allows for a tilting of the contact section with respect to the mounting section, wherein the mounting section, the connecting section and the contact section are formed as one piece, wherein the support structure comprises a through hole for each of the first pads from the backside to a frontside of the support structure that is facing the first part of the bearing, wherein the respective connecting section is arranged at least partially within the respective through hole and/or wherein the respective contact section is arranged at least partially within the respective through hole, wherein the through hole allows for a removal and mounting of the respective pad from the backside.

2. The fluid film bearing according to claim 1, wherein a diameter of the respective connecting section of the first pads in at least one direction is smaller by a factor of at least three or at least five or at least ten then the extension of the pad sliding surface of the respective first pad in the respective direction.

3. The fluid film bearing according to claim 1, wherein the connecting section is elastically deformable to allow for a tilting of the pad sliding surface by an angle of one of at least 0.5° or at least 1° or at least 3°.

4. The fluid film bearing according to claim 1, wherein the mounting section of the respective first pad extends along the backside beyond the respective through hole and closes the respective through hole.

5. The fluid film bearing according to claim 4, wherein the mounting section of the respective first pad is connected to the support structure by multiple bolts or screws spaced around the circumference of the respective through hole.

6. The fluid film bearing according to claim 1, wherein the first part forms a second annular sliding surface, arranged at an angle to the first annular sliding surface, wherein the second part comprises second pads or a second subgroup of the first pads, wherein a respective pad sliding surface of each of the second pads or of the second subgroup of the first pads supports the second annular sliding surface.

7. The fluid film bearing according to claim 6, wherein the first pads are offset in the circumferential direction of the bearing with respect to the second pads or in that the first pads of the first subgroup are offset in the circumferential direction of the bearing with respect to first pads of the second subgroup.

8. The fluid film bearing according to claim 1, wherein the first part is an outer part of the bearing, wherein the first and/or second annular sliding surface are formed on the inner circumference of the first part and/or wherein the respective pad sliding surface of the first and/or second pads or of the first and/or second subgroup of the first pads has a convex shape.

9. A wind turbine, comprising a rotor with a rotor hub that is connected to a further component of the wind turbine using a fluid film bearing according to claim 1, wherein the hub is part of the first or second part or mounted to the first or second part.

10. The wind turbine according to claim 9, wherein the hub is connected to the further component by a single bearing.

11. The wind turbine according to claim 9, wherein the hub and/or the second part and/or the further component form an interior space that allows personal to access the support structure, wherein the first and/or second pads are mounted to the support structure in such a way that they can be exchanged by personal from within the inner space.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:

(2) FIG. 1 depicts a detailed view of an embodiment of a wind turbine according to embodiments of the present invention comprising an embodiment of a fluid film bearing;

(3) FIG. 2 depicts a sectional view of the fluid film bearing shown in FIG. 1;

(4) FIG. 3 depicts a detailed view of alternate embodiments of a fluid film bearing according to embodiments of the present invention that can be used in alternate embodiments of a wind turbine;

(5) FIG. 4 depicts a detailed view of alternate embodiments of a fluid film bearing according to embodiments of the present invention that can be used in alternate embodiments of a wind turbine; and

(6) FIG. 5 depicts a detailed view of alternate embodiments of a fluid film bearing according to embodiments of the present invention that can be used in alternate embodiments of a wind turbine.

DETAILED DESCRIPTION

(7) FIG. 1 shows a detailed view of a wind turbine 1 that comprises a rotor hub 3 rotatably connected to a further component 5 of the wind turbine 1 using a fluid film bearing 2. The hub 3 is mounted to a first part 7 of the bearing 2 using a torque-prove connection. A flange connection can be used. Alternatively, the hub 3 and the first part 7 could be formed, for example cast, as a single piece.

(8) The first part 7 is also connected to the structure 4 using a torque-prove connection. The structure 4 can be used to carry a rotor of a generator of the wind turbine 1 that is not shown in FIG. 1 for reasons of simplicity and clarity.

(9) The second part 6 of the bearing has an annular shape and can be formed as one piece with the further component 5 or connected to the further component 5 using a torque-prove connection. The further component 5 can especially be or carry the stator of the generator of the wind turbine 1 that is not shown for reasons of simplicity and clarity.

(10) Since embodiments of the present invention focus on the implementation and distribution of the various pads, details concerning the lubrication of the fluid film bearing, e.g., seals and pumps that can optionally be used to transport the lubricant, are omitted in the figures.

(11) To radially support the first part 7, the second part 6 comprises first pads 8, 9 distributed along the circumference of the second part 6. Each of the pads 8, 9 has a respective pad sliding surface 10 that supports a first annular sliding surface 14 of the first part 7 in the radial direction. The sliding surfaces 10, 14 can be coated to improve the robustness of the sliding surface and/or further reduce friction. While the sliding surfaces 10, 14 are typically not in direct contact during the normal operation, since a thin lubricant film is arranged between the sliding surfaces 10, 14, contact between the sliding surfaces 10, 14 can occur at slow rotating speeds or when pumps used to transport the lubricant are not working.

(12) The first pads 8, 9 and other pads that will be described later, should allow for a certain amount of tilting of the sliding surface of the respective pad with respect to a mounting section 13 of the respective pad 8, 9 used to mount the pad 8, 9 to the support structure 11. Therefore, the sliding surface is provided by a contact section 34 that is connected to the mounting section 13 by a connecting section 35 to allow for the tilting.

(13) In the pads 8, 9 the mounting section 13, the connecting section 35 and the contact section 34 are formed as one piece, e.g., cast as one piece or machined from one piece of material. To allow for a tilting of the pad, a sufficiently small diameter 41 of the connecting section 35 is chosen to allow for an elastic deformation, especially a flexing, of the connecting section 35. This is shown in more detail in FIG. 2 that shows a sectional view of the fluid film bearing shown in FIG. 1, the sectional plane being orthogonal to the axial direction of the bearing 2.

(14) In other pads, e.g., the pads 20-23 discussed later, other mechanisms could be used to allow for a tilting, e.g., a pivot or ball-in-socket connection. Since the mounting and internal structure of these other pads 20-23 is not relevant for the further discussion, these pads are only shown as a single block in FIG. 1.

(15) The mounting section 13 of the pads 8, 9 is mounted to the backside of the support structure 11, e.g., by bolts 40 arranged around the circumference of the through hole 12. The combined connecting section 35 and contact section 34 with the coating 36 extend through the through hole 12 to the frontside 43 of the support structure. During the mounting of the pads 8, 9 they can be inserted into the through holes 12 of the support structure 11 from the backside 42 and therefore from an interior space 27 formed by the hub 3 and the second part 6 and the further component 5 or a subgroup of these components.

(16) The pad sliding surface 10 does have a convex shape, as seen in FIG. 2. The pad sliding surface 10 at least approximates the shape of a segment of a circle in a sectional plane orthogonal to the axial direction of the bearing 2. The convex shape of the pad sliding surface 10 closely matches the shape of the annular sliding surface 14 that is at least approximately circular in the same sectional plane. Another advantage of using a convex surface is an avoidance of acute angles at the edges 24, 25 of the pad sliding surface 10. This can help to reduce wear and tear of the pad sliding surface 10 and the annular sliding surface 14.

(17) In the discussed example the pad sliding surface 10 and the annular sliding surface 14 are essentially orthogonal to the radial direction and can therefore only support the first part 7 and therefore the hub 3 in the radial direction. To provide an axial support for the first part 7 and therefore the hub 3, the first part 7 has two additional annular sliding surfaces 16, 17 that are approximately orthogonal to the axial direction of the bearing 2. The annular sliding surface 17 is supported by pad sliding surfaces 19 of second pads 20, 21. The annular sliding surface 16 is supported by pad sliding surfaces 18 formed by a third pads 22, 23. Therefore the first part 7 is supported in both axial directions. The second and third pads 20-23 can have a different internal structure and be mounted differently than the first pads 8, 9.

(18) The first pads 8, 9 are offset in the circumferential direction with respect to the second and third pads 20 to 23. This allows for a shorter bearing 2 or the use of a sliding surface 10 of the pads 8, 9 that is larger in the axial direction without using a longer bearing 2.

(19) In the sectional plane orthogonal to the circumferential direction of the bearing shown in FIG. 1 the annular first part 7 has approximately the shape of the letter “I” and forms a protrusion extending in the radial direction towards the second part 6. The annular sliding surface 14 is formed on the radial end of this protrusion and the annular sliding surfaces 16, 17 are formed on the axial ends of this protrusion.

(20) The pads 20-24 can be exchanged by radially removing or inserting them through holes 26 of the support structure 11, such that they are sandwiched between the support structure 11 and the first part 7. They can also be inserted or removed from the interior space 27. As discussed later, other approaches for mounting these pads could also be used.

(21) In the previously discussed example, the pad sliding surfaces 10 providing radial support where essentially orthogonal to the radial direction. It was therefore necessary to use additional pads 20-23 to achieve an axial support of the first part 7 and therefore the hub 3. FIG. 3 shows an alternative embodiment in which the first part 7 has a tapered shape forming two annular sliding surfaces 32, 33 that are essentially parallel to the circumferential direction of the bearing 2, but arranged at an angle to the radial and the axial direction of the bearing 2. The embodiment uses two groups of pads 28, 29, each group supporting a respective one of the annular sliding surfaces 32, 33. The respective normal of the pad sliding surfaces 30, 31 for the respective group of pads 28, 29 is tilted with respect to the radial direction. Therefore, the two groups of pads 28, 29 are sufficient to provide radial and axial support at the same time.

(22) Multiple of these pairs of pads 28, 29 can be spaced along the circumference of the second part 6. To allow for easy servicing, the pads 28, 29 are mounted in through holes 38, 39 of the support structure 11 and can be removed for servicing in the direction of the arrow 37, e.g., from the interior space 27. The internal structure and mounting of the pads 28, 29 is essentially the same as already discussed for the pads 8, 9.

(23) When using two annular sliding surfaces 32, 33 that are both arranged at an angle to the radial and to the axial direction as discussed above, a reduction in the width of the bearing 2 can be achieved by the following modification described with reference to FIG. 4. FIG. 4 shows a cross section orthogonal to the circumferential direction of the bearing 2. Since the approach to supporting the first part 7 is similar as in FIG. 3, the same reference numbers are used for components serving the same or similar purposes. In this embodiment the pads 28, 29 supporting the annular sliding surfaces 32, 33 are arranged at different positions along the circumference of the support structure 11. Therefore, only one of the pads is shown in FIG. 4.

(24) The first difference to the embodiment shown in FIG. 3 is the shape of the first part 7. Instead of the tapered I-shape shown in FIG. 3, the first part 7 now has a tapered U-shape with two protrusions with tapered ends forming the two annular sliding surfaces 32, 33. Therefore the annular sliding surfaces 32, 33 face each other in the embodiment according to FIG. 4.

(25) Due to this arrangement of the annular sliding surfaces 32, 33 the two pads 28, 29 cannot be placed in the same position in the circumferential direction of the bearing 2. Instead, they are displaced by a certain distance in the circumferential direction. In an embodiment, the pads 28, 29 are arranged in such a way that pads 28 of a first group with the orientation shown in FIG. 4 and pads 29 of a second group with an orientation that is mirrored at a vertical axis in FIG. 4, such that the pad sliding surface 31 of these pads 29 can contact the annular sliding surface 33, alternates in the circumferential direction.

(26) FIG. 5 shows a further variation of the discussed fluid film bearing 2. The overall design of the bearing 2 is similar to the bearing 2 discussed with reference to FIGS. 1 and 2 with an approximately I-shaped first part 7 supported radially by a group of pads 8 and axially by two groups of pads 20, 22. In the example shown in FIG. 12 the pads 20, 22 and the pad 8 are arranged at the same circumferential position. It would also be possible to use different circumferential positions for the pad 8 and the pads 20, 22 and/or to place the pads 20, 22 for the different directions of axial support at different circumferential positions.

(27) The main difference between the embodiment discussed with reference to the FIGS. 1 and 2 and the embodiment according to FIG. 5 is the way that the pads 20, 22 for the axial support are mounted to the support structure 11 of the second part 6. Instead of radially inserting them between the first part 7 and the support structure 11, they are inserted into axial through holes of the support structure 11. The internal structure and the mounting of the pads 20, 22 can therefore be the same as for the pads 8.

(28) The second part 6 is connected to the further component 5 via a connection that lies outside of the pad 20, therefore allowing a removal of the pad 8 as well as of the pads 20, 22 from an interior space 27 as discussed with reference to FIG. 1.

(29) Obviously, the features discussed with respect to the individual embodiments can be combined in the variety of ways. Also, the connection of the first and second part 6, 7 of the bearing 2 to various other parts of the wind turbine 1 can be varied. It is possible to form the first part 7 as one piece with the hub 3 and/or the structure 4 or to connect the outer part 7 to one or both of these pieces by a different connection, e.g., by a flange connection. Correspondingly it is possible to provide the further part 5 and the second part 6 as one piece or to connect them by a flange, etc. It would also be possible to use the first part 7 as an inner part and the second part 6 as an outer part of the bearing 2.

(30) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

(31) For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.