WO2012069274A1

WO2012069274A1 - Double row bearing assembly

Info

Publication number: WO2012069274A1
Application number: PCT/EP2011/068859
Authority: WO
Inventors: Steffen Soerensen
Original assignee: Siemens Aktiengesellschaft
Priority date: 2010-11-22
Filing date: 2011-10-27
Publication date: 2012-05-31
Also published as: DE112011103863T5

Abstract

A double row bearing assembly (10, 20, 30, 40 50) comprising a first portion (2) and a second portion (3) is described. The first portion (2) comprises a first ring (4) and a second ring (5). The first ring (4) is connected with the second portion (3) by means of at least one row of tapered rollers (6) or at least one row of balls and the second ring (5) is connected with the second portion (3) by means of at least one row of tapered rollers (7) or at least one row of balls. The bearing assembly (10, 20, 30, 40 50) comprises at least one spacing means (8, 18, 28, 29, 38, 48) which is located between the first ring (4) and the second ring (5). The contact surfaces (17, 25, 26, 27,36, 37, 47) between the spacing means (8, 18, 28, 29, 38, 48) and the first ring (4) and between the spacing means (8, 18, 28, 29, 38, 48) and the second ring (5) have a higher frictional coefficient than a direct contact surface between the first ring (4) and the second ring (5).

Description

DOUBLE ROW BEARING ASSEMBLY The present invention relates to a double tapered bearing as^¬ sembly, to a wind turbine and to a method for manufacturing a spacing means for placing between to components of a double tapered bearing assembly. During extreme loading on the wind turbine rotor there is a risk that the internal bearing forces will cause the two in^¬ ner rings of a double tapered roller bearing to slide rela^¬ tive to each other. This is often referred to as cone shift^¬ ing. When the load is reduced the two inner rings will then end up in a position of relative out of roundness. This geo^¬ metric deviation will increase the hertzian stress level in the contact area between roller and raceway, which will in^¬ crease the probability of bearing failure. A sliding of the two inner rings relatively to each other can be reduced by shrink fitting a reinforcement tube inside the two inner rings. A difficulty with this solution is that it relies on high accuracy of the diameter of the shrink fitted tube. Moreover, the assembly is very difficult. Another al- ternative is to provide a T- or I-shaped ring between the two inner rings. A difficulty with this solution is that it re^¬ lies on a high accuracy of the diameter of the rings.

It is a first objective of the present invention to provide a double tapered bearing assembly which effectively reduces cone shifting by reducing the previously mentioned difficul^¬ ties. It is a second objective of the present invention to provide an advantageous wind turbine. It is a third objective of the present invention to provide a method for manufactur- ing a spacing means for placing between two components of a double tapered bearing assembly. The first objective is solved by the double tapered roller bearing assembly as claimed in claim 1. The second objective is solved by a wind turbine as claimed in claim 10. The third objective is solved by a method for manufacturing a spacing means as claimed in claim 11. The depending claims define further developments of the present invention.

The inventive double tapered bearing assembly comprises a first portion and a second portion. The first portion com- prises a first ring and a second ring. The first ring is con^¬ nected with the second portion by means of at least one row of tapered rollers or at least one row of balls. The second ring is connected with the second portion by means of at least one row of tapered rollers or at least one row of balls. Moreover, the bearing assembly comprises at least one spacing means which is located between the first ring and the second ring. The contact surface between the spacing means and the first ring and the contact surface between the spac^¬ ing means and the second ring have a higher frictional coef- ficient than a direct contact surface between the first ring and the second ring.

For example, the spacing means, which may be a spacer ring, can comprise an engineered surface providing a high coeffi- cient of friction between the neighboring parts without the risk of degradation of the friction. The increased frictional coefficient reduces or avoids a radial sliding movement be^¬ tween the rings of the first portion of the bearing as the friction between the spacing means and the first ring and the friction between the spacing means and the second ring of the bearing is maintained very high.

The inventive double tapered bearing assembly may comprise a rotation axis. The first portion can be located radially in- side of the second portion. In case that the first portion and the second portion have the shape of a ring, than the first portion may have an outer radius which is smaller than the outer radius of the second portion. Alternatively, the second portion may be located radially inside of the first portion. In case of a ring shaped first portion and a ring shaped second portion, the inner radius of the first portion can be smaller than the inner radius of the second portion.

Generally, the spacing means can comprise at least one spacer ring, for example a flat spacer ring or spacing segment.

Moreover, the spacing means can comprise a number of segments. This simplifies assembly and disassembly of the bear- ing. For example, the spacing means may comprise a number of radial and/or axial segments.

Advantageously, the spacing means comprises a mechanically or chemically deformed surface. The spacing means or the spacer ring can have an engineered surface that ensures a high coef^¬ ficient of friction between the neighbouring parts, i.e. between the spacing means and the first ring and the spacing means and the second ring, without the risk of degradation of the friction. This is generally difficult due to high yield strength of the companion structures. Generally, an elevated friction can be obtained by chemical deposition, electroplat^¬ ing vapour phase deposition, diffusion, thermal spray and/or welding. The mentioned methods can make use of advanced heat sources like plasma, laser, ion, electron, microwave, solar beams, pulsed arc, pulsed combustion, spark, friction and/or induction .

The elevated friction can also be obtained by mechanical de^¬ formation of the spacer surface such as by grit blasting, shot peening or laser peening. The more advanced two latter methods are likely required as the spacer needs to be of a significant hardness in order to enable the coefficient of friction when compressed against the bearing steel. One or more of the mentioned heat treating methods like friction and/or induction heat treating may locally increase the surface hardness of the spacer ring to avoid degradation of the friction of the spacer ring. The influence of shot peening and laser peening can e.g. be seen in the article "Laser peening and shot peening effects on fatigue life and surface roughness of friction stir welded 7075-T7351 aluminum", Omar Hatamle, Jed Lyons and Royce For- man from the journal "Fatigue & Fracture of Engineering Mate^¬ rials & Structures", Volume 30, Issue 2, pages 115-130, Feb^¬ ruary 2007. Especially fig. 11 in the article showing 3D con^¬ tours of plate specimens illustrating the differences in sur^¬ face roughness (peaks measurements) between an unpeened, a shot peened and a laser peened plate specimen. The unpeened milled plate comprises an average surface roughness Ra=0.24 micrometer and a peak surface roughness Rt=3.97 micrometer, where the shot peened plate comprises an average surface roughness Ra=3.86 micrometer and a peak surface roughness Rt=44.83 micrometer and where the laser peened plate comprises an average surface roughness Ra=0.347 micrometer and a peak surface roughness Rt=5.5375 micrometer (see Table 2 in the article) . Preferably the surfaces of the spacing means which are in contact with the first and/or the second ring have an average roughness of at least 0.3 μπι and/or a peak surface roughness of at least 5 μπι. For example, the surfaces of the spacing means which are in contact with the first and/or second ring may have an average roughness of at least 3 μπι and/or a peak surface roughness of at least 40 μπι. This effectively in^¬ creases the frictional coefficient between the neighbouring surfaces . Moreover, the surface of the spacing means may comprise addi^¬ tional particles, for example small hard particles like for instance industrial diamonds. The additional particles can be deposit on the surface. The elevated friction can be obtained by deposition of small hard particles, for example industrial diamonds, on the surfaces of the spacer, although such hard particles need to be kept far away from the raceway. Moreover diamond knurling may be used to create an elevated friction of the spacer surface. Especially in combination with a hardening of the surface of the spacer this can ensure a high friction with low degradation of the surface friction of the spacer ring.

A further development is to have spacers in a number of dis^¬ crete thicknesses in order to use the spacers to control the clearance of the bearing.

Furthermore, the spacing means may comprise at least one sealing means, for example one or more O-rings. The sealing means may provide a sealing against the second portion of the bearing. This ensures that oil from the bearing is kept away from all or nearly all of the frictional areas between the spacing means and the two rings of the first portion of the bearings .

The spacing means can comprise at least one radially outer spacer ring and at least one radially inner spacer ring. The at least one radially outer and/or the at least one radially inner spacer ring can comprise a sealing means. For example, the bearing may comprise one outer flat spacer ring and one or more inner flat spacer rings located between the first ring and the second ring of the first portion of the bearing. In this case the outer flat spacer ring may comprise a seal^¬ ing means. By dividing the flat spacer ring into an outer flat spacer ring comprising a sealing means and one or more inner flat spacer rings without sealing means the sealing means is less be influenced by the forces put on the inner rings of the bearing. In this way only the one or more inner flat spacer rings need a high coefficient of friction to en^¬ sure a good frictional coefficient between the inner flat spacer rings and the inner rings of the bearing.

Moreover, the spacer means may comprise a segmented ring, preferably having two or more segments. The spacing means may have a thickness in axial direction of at least 0.5 mm, for example at least 50 mm. The spacing means may have a thickness in axial direction of less than 100 mm. Preferably, the spacing means may comprise a number of spacer rings with a thickness between 0.5 mm and 50 mm. The flat spacer ring may comprise a width or thickness of 50 mm or more though preferably less than 100 mm. Also one or more thin flat spacer rings, for instance with a thickness of 0.5 to 5 mm, may be used in combination with a thicker flat spacer ring, for instance with a thickness of 20 to 50 mm. In general one or more of the flat spacer rings may comprise a different thickness than one or more of the other flat spacer rings that are located between the two inner rings . It is also be possible to use a thin spacing ring (segmented or not segmented) with a thickness of e.g. 0.2 mm up to 0.5 mm or more. A thin spacing ring ensures a thinner bearing which may be easier to build in to an application like e.g. a wind turbine. Thicker spacing rings with a thickness

less than 50 mm may also be useful in some applications as well as even thicker spacer rings to ensure a stable and strong spacer ring or spacer segments.

Advantageously the spacing means comprises metal material, for example steel. Advantageously, the spacing means com^¬ prises steel which is able to harden like high or medium carbon steel. By hardening at least the surface of the spacing means degradation of the friction of the surface of the spacer rings can be avoided.

The inventive spacing means with one or more engineered sur^¬ faces to avoid cone shifting of a bearing may be used in other types of bearings having two or more rows of rollers, preferably tapered rollers, and/or balls and having two or more inner rings and one or more outer rings were one or more flat spacer rings can be located between each pair of inner rings of the bearing. If more than one outer ring is present one or more flat spacer rings may also be located between each pair of outer rings of the bearing.

The inventive wind turbine comprises a double tapered bearing assembly as previously described. The inventive wind turbine can comprise a generator with a rotor and a stator. The rotor or the stator may be supported by the inventive double ta^¬ pered bearing assembly. Generally, the inventive wind turbine may be a gearless direct drive wind turbine. The inventive wind turbine has the same advantages as the previously de^¬ scribed bearing assembly.

The inventive method for manufacturing a spacing means for placing between two components, for example between two rings, of a double tapered bearing assembly is characterized in deforming the surface of the spacing means which is facing the two components. The surface of the spacing means can be mechanically or chemically deformed. For example, the surface of the spacing means can be deformed by chemical deposition and/or electroplating vapour phase deposition and/or diffusion and/or thermal spraying and/or welding and/or grit blasting and/or shot peening and/or laser peening and/or friction heat treating and/or induction heat treating. The welding can be performed using advanced heat sources like plasma, laser, ion, electron, microwave, solar beams, pulsed arc, pulsed combustion, spark, friction and/or induction. Also diamond knurling may be used to create an elevated fric^¬ tion of the spacer surface. The double tapered bearing assembly may be a double tapered roller or ball bearing assembly.

The inventive method may further comprise the step of harden^¬ ing the surface of the spacing means. Furthermore, additional particles can be deposit on the surface of the spacing means. For example, small hard particles, like industrial diamonds, can be deposit on the surface of the spacing means. Espe^¬ cially in combination with a hardening of the surface of the spacing means a high friction with low degradation of the surface friction of the spacing means can be ensured.

Further features, properties and advantages of the present invention will become clear from the following description of an embodiment in conjunction with the accompanying drawings. All mentioned features are advantageous separate or in any combination with each other. Figure 1 schematically shows part of a double tapered roller bearing in a sectional view.

Figure 2 schematically shows part of an inventive double ta^¬ pered roller bearing in a sectional view.

Figure 3 schematically shows a variant of part of an inven^¬ tive double tapered roller bearing in a sectional view . Figure 4 schematically shows part of a further variant of an inventive double tapered roller bearing in a sec^¬ tional view.

Figure 5 schematically shows an additional variant of part of an inventive double tapered roller bearing in a sectional view.

Figure 6 schematically shows a wind turbine. Figure 1 schematically shows part of a known double tapered roller bearing 1 in a sectional view. The bearing 1 comprises a first portion 2 and a second portion 3. The first portion 2 comprises a first ring 4 and a second ring 5. Between the first ring 4 and the second portion 3 a first row of rollers 6 is located. Between the second ring 5 and the second por^¬ tion 3 a second row of rollers 7 is located. The rotation axis of the bearing 1 is indicated by reference numeral 9. Moreover, a spacer ring 8 is placed between the first ring 4 and the second ring 5. The spacer ring 8 has an I-shape with a number of protrusions to avoid a radial movement of the first ring 4 and the second ring 5 relatively to each other. To effectively avoid a radial movement the rings 4, 5 and 8 have a diameter of high accuracy.

A first embodiment of the present invention will now be de^¬ scribed with reference to Figure 2. Figure 2 schematically shows part of an inventive double tapered roller bearing 10 in a sectional view.

Elements corresponding to elements of previously described figures will be designated with the same reference numerals and will not be described again in detail.

The spacing means or spacer ring 18 in Figure 2 comprises a number of contact surfaces 17 which are in direct contact with a surface of the first ring 4 or with a surface of the second ring 5. The contact surfaces 17 have a frictional co^¬ efficient which is higher than the frictional coefficient of a direct contact surface between the first ring 4 and the second ring 5. This has the effect, that by means of the spacer ring 18 the frictional coefficient between the first ring 4 and the second ring 5 is increased. Consequently, a radial movement between the first ring 4 and the second ring 5 is avoided or at least reduced.

The flat spacer ring 18 may comprise a number of radial seg- ments.

In Figure 2 the first ring 4, the second ring 5 and the spacer ring 18 comprise a hole 16 for fixing the rings 4, 5, 18 to each other. The hole 16 comprises a centre line 15 which runs parallel to the rotation axis 9.

By providing a force of a specific size in axial direction on the rings 4 and 5 and on the flat spacer ring 18 sliding movement between the first ring 4 and the second ring 5 in transverse or radial direction is avoided by having a larger frictional force between the flat spacer ring 18 and the first ring 4 or second ring 5 than the transverse forces put on the first ring 4 and the second ring 5 of the bearing 10. The force on the rings 4, 5, 18 can be provided via the hole 16.

A second embodiment will now be described with reference to Figure 3. Figure 3 schematically shows part of an inventive double tapered roller bearing 20 in a sectional view. In Figure 3 the spacing means between the first ring 4 and the sec^¬ ond ring 5 comprises two axial segments 28 and 29. The spacer rings 28 and 29 have a different thickness in axial direc- tion. Generally the flat spacer rings 28, 29 may comprise a width or thickness of 55 mm or more though preferably less than 100 mm. One or more thin flat spacer rings 28, for instance with a thickness between 0.2 and 5 mm, may be used in combination with a thicker flat spacer ring 28, for instance with a thickness between 20 and 50 mm. In general, one or more of the flat spacer rings 28 and 29 may comprise a dif^¬ ferent thickness than one or more of the other flat spacer rings that are located between the two rings 4 and 5. A third embodiment of the present invention will now be de^¬ scribed with reference to Figure 4. Figure 4 schematically shows part of an inventive double tapered roller bearing 30 in a sectional view. In Figure 4 the spacer ring 38, which is located between the first ring 4 and the second ring 5, com- prises two sealing means 39, for example o-rings. The sealing means 39 provide a sealing between the first ring 4 and the second ring 5. The surface 37 of the flat spacer ring 38 at the area of the sealing means 39 may be treated differently with a different surface roughness and friction than the other surface area 36 away from the sealing means 39. This ensures that a less transverse force put on the sealing area of the flat spacer ring 38 than on the surface area 36 away from the sealing area avoiding strength and/or fatigue fracture risks of the flat spacer ring 38.

The fourth embodiment of the present invention will now be described with reference to Figure 5. Figure 5 schematically shows part of an inventive double tapered roller bearing 40 in a sectional view. In Figure 5 the spacing means between the first ring 4 and the second ring 5 comprises a radially inner spacer ring 46 and a radially outer spacer ring 48. The radially outer spacer ring 48 comprises a sealing means 39, for example at least one o-ring, sealing against the rings 4 and 5. The surface 45 of the radially outer flat spacer ring 48 may be treated differently with a different surface rough^¬ ness and friction than the surface area 47 of the radially inner flat spacer ring 46. The contact surface between the radially outer spacer ring 48 and the first ring 4 and the second ring 5 is indicated by reference numeral 45. The con^¬ tact surface between the first ring 4 and the second ring 5 and the radially inner spacer ring 46 is indicated by refer- ence numeral 47.

By providing a force of a specific size on the rings 4 and 5 and the flat spacer ring 46 and the flat spacer ring 48 slid^¬ ing movement between the first ring 4 and the second ring 5 in transverse or radial direction is avoided, especially due to a larger frictional force between the inner spacer ring 46 and the inner rings 4 and 5 than the transverse or radial forces acting on the inner rings 4 and 5 of the bearing 40. Generally, all contact surfaces of a spacing means can be en^¬ gineered such that they ensure a high coefficient of friction between the neighbouring parts without the risk of degrada^¬ tion of the friction. This elevated friction can be obtained by chemical deposition, electroplating vapour phase deposi- tion, diffusion, thermal spray and/or welding, for example using advanced heat sources like plasma, laser, ion, elec^¬ tron, microwave, solar beams, pulsed arc, pulsed combustion, spark, friction and/or induction. The elevated friction can also be obtained by mechanical de^¬ formation of the spacer surface such as by grit blasting, shot peening or laser peening, the more advanced two latter methods are likely required as the spacer needs to be of a significant hardness in order to enable the coefficient of friction when compressed against the bearing. The bearing may comprise steel. One or more of the mentioned heat treating methods like fric^¬ tion and/or induction heat treating may locally increase the surface hardness of the spacer ring to avoid degradation of the friction of the spacer ring. Also diamond knurling may be used to create an elevated friction of the spacer surface. Especially in combination with a hardening of the surface of the spacer this could ensure a high friction with low degra^¬ dation of the surface friction of the spacer ring. The elevated friction can also be obtained by deposition of small hard particles (e.g. industrial diamantes) on the surfaces of the spacer, although such hard particles need to be kept far away from the raceway.

Generally, the present invention reduces a radial sliding movement between the first ring 4 and the second ring 5 by means of a spacer ring which provides contact surfaces with an increased frictional coefficient.

Figure 6 schematically shows a wind turbine 51. The wind tur^¬ bine 51 comprises a tower 52, a nacelle 53 and a hub 54. The nacelle 53 is located on top of the tower 52. The hub 54 com^¬ prises a number of wind turbine blades 55. The hub 54 is mounted to the nacelle 53. Moreover, the hub 54 is pivot- mounted such that it is able to rotate about a rotation axis 59. A generator 56 is located inside the nacelle 53. The gen- erator may instead be attached to a structure part of the na^¬ celle in such a way that it is located on one end part of the nacelle and further attached to a rotor hub. The wind turbine 51 is a direct drive wind turbine. The generator 56 comprises rotor and a stator and an inventive double tapered bearing, previously described, supporting the rotor or the stator.

Reference listing

1 double tapered roller bearing

2 first portion

3 second portion

4 first ring

5 second ring

6 first row of rollers

7 second row of rollers

8 spacer ring

9 rotation axis

10 double tapered roller bearing

16 hole for fixation

17 contact surface

18 spacer ring

20 double tapered roller bearing

25 contact surface

26 contact surface

27 contact surface

28 spacer ring

29 spacer ring

30 double tapered roller bearing

36 contact surface

37 contact surface

38 spacer ring

39 sealing means

40 double tapered roller bearing

45 contact surface

46 radially inner spacer ring

47 contact surface

48 radially outer spacer ring

51 wind turbine

52 tower

53 nacelle

54 hub

55 blade

56 generator

59 rotation axis

Claims

1. A double tapered bearing assembly (10, 20, 30, 40 50) comprising a first portion (2) and a second portion (3), the first portion (2) comprising a first ring (4) and a second ring (5), the first ring (4) being connected with the second portion (3) by means of at least one row of tapered rollers (6) or at least one row of balls and the second ring (5) being connected with the second portion (3) by means of at least one row of tapered rollers (7) or at least one row of balls,

the bearing assembly (10, 20, 30, 40 50) comprising at least one spacing means (8, 18, 28, 29, 38, 48) which is located between the first ring (4) and the second ring (5),

characterised in that

the contact surfaces (17, 25, 26, 27,36, 37, 47) between the spacing means (8, 18, 28, 29, 38, 48) and the first ring (4) and between the spacing means (8, 18, 28, 29, 38, 48) and the second ring (5) have a higher frictional coefficient than a direct contact surface between the first ring (4) and the second ring (5) .

2. The double tapered bearing assembly (10, 20, 30, 40 50) as claimed in claim 1,

characterised in that

the spacing means (8, 18, 28, 29, 38, 48) comprises a number of segments.

3. The double tapered bearing assembly (10, 20, 30, 40 50) as claimed in claim 1 or claim 2,

characterised in that

the surfaces of the spacing means (8, 18, 28, 29, 38, 48) which are in contact with the first ring (4) and/or second ring (5) have an average roughness of at least 0.3 micrometre and/or a peak surface roughness of at least 5 micrometre.

4. The double tapered bearing assembly (10, 20, 30, 40 50) as claimed in claim 3, characterised in that

the surfaces of the spacing means (8, 18, 28, 29, 38, 48) which are in contact with the first ring (4) and/or second ring (5) have an average roughness of at least 3 micrometre and/or a peak surface roughness of at least 40 micrometre.

5. The double tapered bearing assembly (10, 20, 30, 40 50) as claimed in any of the claims 1 to 4,

characterised in that

the surface of the spacing means (8, 18, 28, 29, 38, 48) comprises additional particles which are deposit on the surface.

6. The double tapered bearing assembly (10, 20, 30, 40 50) as claimed in any of the claims 1 to 5,

characterised in that

the spacing means (8, 18, 28, 29, 38, 48) comprises at least one sealing means (39) .

7. The double tapered bearing assembly (10, 20, 30, 40 50) as claimed in any of the claims 1 to 6,

characterised in that

the spacing means (8, 18, 28, 29, 38, 48) comprises at least one radially outer spacer ring (48) and at least one radially inner spacer ring (46) .

8. The double tapered bearing assembly (10, 20, 30, 40 50) as claimed in any of the claims 1 to 7,

characterised in that

the spacing means (8, 18, 28, 29, 38, 48) has a thickness in axial direction of at least 0.2 mm and/or the spacing means

(8, 18, 28, 29, 38, 48) has a thickness in axial direction of less than 100 mm.

9. The double tapered bearing assembly (10, 20, 30, 40 50) as claimed in any of the claims 1 to 7,

characterised in that

the spacing means (8, 18, 28, 29, 38, 48) comprises metal ma^¬ terial .

10. A wind turbine (51) comprising a double tapered bearing assembly (10, 20, 30, 40 50) as claimed in any of the claims 1 to 9.

11. A method for manufacturing a spacing means (8, 18, 28, 29, 38, 48) for placing between two components (4, 5) of a double tapered bearing assembly (10, 20, 30, 40 50),

characterised in

deforming the surface of the spacing means (8, 18, 28, 29, 38, 48) which is facing the two components (4, 5) .

12. The method as claimed in claim 11,

characterised in

mechanically or chemically deforming the surface of the spac^¬ ing means (8, 18, 28, 29, 38, 48) .

13. The method as claimed in claim 12,

characterised in

deforming the surface of the spacing means (8, 18, 28, 29, 38, 48) by chemical deposition and/or electroplating vapour phase deposition and/or diffusion and/or thermal spraying and/or welding and/or grit blasting and/or shot peening and/or laser peening and/or friction heat treating and/or in- duction heat treating.

14. The method as claimed in any of the claims 11 to 13, characterised in

hardening the surface of the spacing means (8, 18, 28, 29, 38, 48) .

15. The method as claimed in any of the claims 11 to 14, characterised in

deposing additional particles on the surface of the spacing means (8, 18, 28, 29, 38, 48) .