JOURNAL BEARING HOUSING AND SHAFT FOR A WIND TURBINE
DRIVETRAIN HAVING CORRESPONDING DEFORMATION
FIELD
[0001] The present disclosure relates in general to wind turbines, and more
particularly to journal bearing housings and the respective shafts for a wind turbine
drivetrain having a corresponding deformation.
BACKGROUND
[0002] Generally, a wind turbine includes a tower, a nacelle mounted on the
tower, and a rotor coupled to the nacelle. The rotor generally includes a rotatable hub
and a plurality of rotor blades coupled to and extending outwardly from the hub.
Each rotor blade may be spaced about the hub so as to facilitate rotating the rotor to
enable kinetic energy to be converted into usable mechanical energy, which may then
be transmitted to an electric generator disposed within the nacelle for the production
of electrical energy. Typically, a gearbox is used to drive the electric generator in
response to rotation of the rotor. For instance, the gearbox may be configured to
convert a low speed, high torque input provided by the rotor to a high speed, low
torque output that may drive the electric generator.
[0003] The drivetrain generally includes a plurality of bearings arranged with the
rotor shaft (also referred to herein as the low-speed shaft), the pin shafts, and/or the
high-speed shaft of the generator. Moreover, lubrication is generally provided
between the various bearing(s) and the rotating components. Such bearings may
include, for example, journal bearings that require compliance to counter the
deformation which occurs due to the deformation of the parts surrounding the
bearings.
[0004] For conventional journal bearings, extra components are added thereto so
as to increase the flexibility thereof. For example, conventional journal bearings
include gliding pads, pivot joints, steel springs, and/or flexible geometry designs to
compensate for misalignment, dynamic movements, and/or deflection of the rotating
shafts versus the deflecting housing structure of the bearing. Without this flexibility,
high edge loading and seizure of the bearings can occur. Such components, however,
add to the complexity of the bearing design.
[0005] Accordingly, a drivetrain for a wind turbine having one or more journal
bearings that address the aforementioned issues would be welcomed in the art.
BRIEF DESCRIPTION
[0006] Aspects and advantages of the invention will be set forth in part in the
following description, or may be obvious from the description, or may be learned
through practice of the invention.
[0007] In one aspect, the present disclosure is directed to a bearing assembly for a
drivetrain of a wind turbine. The bearing assembly includes a shaft having a
circumferential outer surface. The bearing assembly also includes a bearing housing
arranged circumferentially around the circumferential outer surface of the shaft. The
bearing housing has at least deformation such that the bearing housing and the shaft
have a corresponding deformation around a toroidal axis such that interfacing surfaces
of the bearing housing and the shaft flex together and remain parallel during operation
of the drivetrain, thereby distributing operational loads of the drivetrain. The bearing
assembly further includes a bearing housed at least partially within the bearing
housing and engaging the circumferential outer surface of the shaft.
[0008] In an embodiment, the deformation(s) may be caused by at least one
flexible hinge. In such embodiments, the flexible hinge allows the bearing housing to
tilt as a whole or locally. Further, the bearing housing may have a base portion and a
bearing contacting portion adjacent to the bearing. In another embodiment, the
bearing housing may include symmetrical opposing flexible hinges.
[0009] In several embodiments, the bearing assembly may include a cavity on the
circumferential outer surface of the shaft that receives and secures the bearing in
place, the cavity defining a base wall and opposing side walls. In one embodiment,
one or more of the opposing side walls of the cavity may integral with the shaft. In
alternative embodiments, at least one of the opposing side walls may be formed via a
removable ring secured to the circumferential outer surface of the shaft.
[0010] In further embodiments, a lengthwise cross-section of the bearing may be
curved prior to being secured into the cavity so as to provide a desired preload over a
length of the bearing.
[0011] In another embodiment, the bearing assembly may include one or more
bearing pads within the cavity on one or more sides of the bearing.
[0012] In an embodiment, the opposing side walls may include, for example, a
rotor-side wall and a generator-side wall. In such embodiments, if an angular
misalignment of the shaft occurs during operation of the drivetrain, the flexible hinge
is configured to tilt to define an axial gap between an upper rotor-side portion of the
bearing and an upper portion of the rotor-side wall such that only lower bearing pads
and a lower portion of the rotor-side wall carry a load.
[0013] In additional embodiments, the shaft may also include at least one flexible
hinge adjacent to the bearing. In particular embodiments, the bearing housing and/or
the shaft may be constructed, at least in part, of a compliant material.
[0014] In further embodiments, the bearing may be a journal bearing, a thrust
bearing, an axial bearing, and/or a radial bearing. In an embodiment, for example, the
shaft may be a low-speed shaft of the drivetrain.
[0015] In another embodiment, where the bearing is the journal bearing and the
shaft is the low-speed shaft coupling a rotor to a gearbox of the wind turbine, the
bearing assembly may also include one or more flexible components mounted in an
offset location around the gearbox so as to offset a weight-load and thrust of the rotor
such that a nominal load is taken at a neutral misalignment position.
[0016] In still further embodiments, due to the corresponding deformation
described herein, the bearing assembly may be absent of bearing pads.
[0017] In another aspect, the present disclosure is directed to a drivetrain
assembly. The drivetrain assembly includes a rotor, a low-speed shaft rotatably
coupled to the rotor. The low-speed shaft includes at least a circumferential outer
surface. The drivetrain assembly also includes a gearbox rotatably coupled to the
low-speed shaft and a bearing assembly. The bearing assembly includes a bearing
housing arranged circumferentially around the circumferential outer surface of the
low-speed shaft. The bearing housing has at least deformation such that the bearing
housing and the low-speed shaft have a corresponding deformation around a toroidal
axis such that interfacing surfaces of the bearing housing and the low-speed shaft flex
together and remain parallel during operation of the drivetrain assembly, thereby
distributing operational loads of the drivetrain assembly. The bearing assembly also
includes a journal bearing housed at least partially within the bearing housing and
engaging the circumferential outer surface of the low-speed shaft. It should also be
understood that the drivetrain assembly may further include any of the additional
features described herein.
[0018] These and other features, aspects and advantages of the present invention
will become better understood with reference to the following description and
appended claims. The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate embodiments of the invention and,
together with the description, serve to explain the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] A full and enabling disclosure of the present invention, including the best
mode thereof, directed to one of ordinary skill in the art, is set forth in the
specification, which makes reference to the appended figures, in which:
[0020] FIG. 1 illustrates a perspective view of one embodiment of a wind turbine
according to the present disclosure;
[0021] FIG. 2 illustrates a detailed, internal view of one embodiment of a nacelle
of a wind turbine according to the present disclosure;
[0022] FIG. 3 illustrates a side view of one embodiment of a rotor shaft of a wind
turbine according to the present disclosure, particularly illustrating a bearing assembly
engaged with the rotor shaft;
[0023] FIG. 4 illustrates a side view of the rotor shaft of FIG. 3 during operation
to depict an angular misalignment of the shaft according to the present disclosure,
wherein an axial gap is defined between an upper rotor-side portion of the bearing and
an upper portion of the rotor-side wall such that only lower bearing pads and the
rotor-side wall carry the load;
[0024] FIG. 5 illustrates a side view of another embodiment of a rotor shaft of a
wind turbine according to the present disclosure, particularly illustrating a bearing
assembly engaged with the rotor shaft;
[0025] FIG. 6A illustrates a cross-sectional view of one embodiment of a bearing
housing of a bearing assembly according to the present disclosure, particularly
illustrating a bearing housing having a flexible hinge;
[0026] FIG. 6B illustrates a cross-sectional view of the bearing housing of FIG.
6A, particularly illustrating the flexible hinge being tilted;
[0027] FIG. 6C illustrates a front view of another embodiment of a bearing
housing of a bearing assembly according to the present disclosure, particularly
illustrating a bearing housing having a flexible hinge;
[0028] FIG. 7A illustrates a partial, cross-sectional view of one embodiment of a
cavity receiving a bearing or a part with a running surface according to the present
disclosure, particularly illustrating the bearing having a curved lengthwise crosssection prior to being secured into a cavity on a circumferential outer surface of the
shaft;
[0029] FIG. 7B illustrates a cross-sectional view of the curved bearing of FIG. 7A
according to the present disclosure, particularly illustrating the bearing secured within
the cavity of the shaft so as to provide a desired preload over a length of the bearing
during operation of the drivetrain;
[0030] FIG. 8A illustrates a side view of one embodiment of a rotor shaft of a
wind turbine according to the present disclosure, particularly illustrating a bearing
assembly engaged with the rotor shaft and flexible components mounted in an aligned
location around the gearbox;
[0031] FIG. 8B illustrates a side view of one embodiment of a rotor shaft of a
wind turbine according to the present disclosure, particularly illustrating a bearing
assembly engaged with the rotor shaft and flexible components mounted in an offset
location around the gearbox so as to offset a weight-load and thrust of the rotor such
that a nominal load is taken at a neutral misalignment position;
[0032] FIG. 9 illustrates a partial, cross-sectional, exploded view of one
embodiment the bearing assembly according to the present disclosure, particularly
illustrating a bearing housing and a rotor shaft thereof having a flexible hinge;
[0033] FIG. 10A illustrates a partial, cross-sectional view of one embodiment the
bearing assembly according to the present disclosure;
[0034] FIG. 10B illustrates a partial, cross-sectional view of another embodiment
the bearing assembly according to the present disclosure; and
[0035] FIG. 10C illustrates a partial, cross-sectional view of yet another
embodiment the bearing assembly according to the present disclosure.
DETAILED DESCRIPTION
[0036] Reference now will be made in detail to embodiments of the invention,
one or more examples of which are illustrated in the drawings. Each example is
provided by way of explanation of the invention, not limitation of the invention. In
fact, it will be apparent to those skilled in the art that various modifications and
variations can be made in the present invention without departing from the scope or
spirit of the invention. For instance, features illustrated or described as part of one
embodiment can be used with another embodiment to yield a still further
embodiment. Thus, it is intended that the present invention covers such modifications
and variations as come within the scope of the appended claims and their equivalents.
[0037] Generally, the present disclosure is directed to a drivetrain assembly that
includes a shaft and one or more journal bearings and associated housing mounted
thereon, with the shaft and the housing having substantial flexibility. Thus, the shaft
and bearing housing are flexible around a toroidal axis, allowing both running
surfaces to flex in full coordination. By providing the matching flexibility, the
running surfaces remain substantially parallel to each during operation of the
drivetrain, thereby allowing full contact between the bearing and the shaft so as to
build hydrodynamic pressure or in the case of mixed friction, to share the load to
minimize peak loads.
[0038] Referring now to the drawings, FIG. 1 illustrates a perspective view of one
embodiment of a wind turbine 10 according to the present disclosure. As shown, the
wind turbine 10 includes a tower 12 extending from a support surface 14, a nacelle 16
mounted on the tower 12, and a rotor 18 coupled to the nacelle 16. The rotor 18
includes a rotatable hub 20 and at least one rotor blade 22 coupled to and extending
outwardly from the hub 20. For example, in the illustrated embodiment, the rotor 18
includes three rotor blades 22. However, in an alternative embodiment, the rotor 18
may include more or less than three rotor blades 22. Each rotor blade 22 may be
spaced about the hub 20 to facilitate rotating the rotor 18 to enable kinetic energy to
be transferred from the wind into usable mechanical energy, and subsequently,
electrical energy. For instance, the hub 20 may be rotatably coupled to an electric
generator 24 (FIG. 2) positioned within the nacelle 16 to permit electrical energy to be
produced.
[0039] Referring now to FIG. 2, a simplified, internal view of a nacelle 16 of the
wind turbine 10 according to conventional construction is illustrated. As shown, the
generator 24 may be disposed within the nacelle 16. In general, the generator 24 may
be coupled to the rotor 18 of the wind turbine 10 for producing electrical power from
the rotational energy generated by the rotor 18. For example, as shown in the
illustrated embodiment, the rotor 18 may include a rotor shaft 28 coupled to the hub
20 for rotation therewith. The rotor shaft 28 may, in turn, be rotatably coupled to a
drivetrain assembly that includes the generator 24 and a gearbox 26. More
specifically, the rotor shaft 28 may, in turn, be rotatably coupled to a generator shaft
34 of the generator 24 through the gearbox 26.
[0040] As is generally understood, the rotor shaft 28 may provide a low speed,
high torque input to the gearbox 26 in response to rotation of the rotor blades 22 and
the hub 20. Thus, the gearbox 26 may include a gear assembly (not shown) that
converts the low speed, high torque input to a high speed, low torque output to drive
the generator shaft 34 and, thus, the generator 24. In alternative embodiments, the
rotor shaft 28 may be eliminated and the rotatable hub 20 may be configured to turn
the gears of the gearbox 26, rather than requiring a separate rotor shaft 28.
[0041] Referring now to FIGS. 3 and 4, side views of one embodiment of a
bearing assembly 30 according to the present disclosure are illustrated. More
specifically, as shown, the bearing assembly 30 includes the rotor shaft 28 having an
outer circumferential surface 36. The bearing assembly 30 also includes a bearing
housing 32 arranged circumferentially around the circumferential outer surface 36 of
the shaft 28. The bearing assembly 30 further includes a bearing 38, such as a journal
bearing, housed at least partially within the bearing housing 32 and engaging the
circumferential outer surface 36 of the shaft 28. As will be described in more detail
herein, the bearing housing 32 and the shaft 28 have a corresponding deformation
around a toroidal axis such that interfacing surfaces of the bearing housing 32 and the
shaft 28 flex together and remain parallel during operation of the drivetrain, thereby
distributing operational loads thereof.
[0042] Referring to FIGS. 3-5, 7A, and 7B, the bearing assembly 30 may include
a cavity 48 on the circumferential outer surface 36 of the shaft 28 that receives and
secures the bearing 38 in place. For example, as shown particularly in FIGS. 7A and
7B, the cavity 48 may define a base wall 50 and opposing side walls 52, 54. More
specifically, as shown, the opposing side walls 52, 54 may include, for example, a
rotor-side wall 52 and a generator-side wall 54.
[0043] In several embodiments, as shown particularly in FIGS. 3 and 4, one or
more of the opposing side walls 52, 54 of the cavity 48 may integral with the shaft 28.
In alternative embodiments, as shown in FIGS. 5, 7A, and 7B, at least one of the
opposing side walls 52, 54 may be formed via a removable ring 56 secured to the
circumferential outer surface 36 of the shaft 28. In such embodiments, the removable
ring 56 can assist with easy installation of the bearing 38. For example, the bearing
38 can be placed around the shaft 28 within the cavity 48 and the removable ring 56
may be subsequently secured around the shaft to secure the bearing 38 in place. In
particular embodiments, as shown in FIGS. 7A and 7B, a lengthwise cross-section of
the bearing 38 (e.g. along a lengthwise axis 68) may be curved prior to being secured
into the cavity 48 (see e.g. FIG. 7A) so as to provide a desired preload over a length
of the bearing 38 after installation (See e.g. FIG. 7B).
[0044] Referring to FIGS. 3-5, 7A, and 7B, in another embodiment, the bearing
assembly 30 may also include one or more bearing pads 60 (axial or radial) within the
cavity 48 on one or more sides of the bearing 38 and/or the bearing housing 32. For
example, in the illustrated embodiment, the bearing assembly 30 includes a bearing
pad 60 within the cavity 48 on each side of the bearing 38/bearing housing 32. It
should be understood that the bearing pads 60 may be secured in place using any
suitable means, such as for example, adhesive (FIGS. 3 and 4), form closed features
such as tilting-pad hinges and/or fasteners 70 (FIG. 5).
[0045] Referring particularly to FIGS. 3-6C, the bearing housing 32 described
herein may have a base portion 40, a bearing contacting portion 42 adjacent to the
bearing 38 and at least one deformation formed therein. For example, as shown, the
deformation may include at least one flexible hinge 44, 46 (FIGS. 6A-6C).
Accordingly, the base portion 40 may be secured to, for example, a bedplate 25 (FIG.
2) of the wind turbine 10. In such embodiments, as shown particularly in FIGS. 6A6C, the flexible hinge(s) 44, 46 provides flexibility to the bearing housing 32, for
example, by allowing the bearing housing 32 to tilt, e.g. by a certain angle 58. Thus,
the flexible hinge(s) 44, 46 allow the flexibility of the bearing housing 32 and the
shaft 28 to be substantially the same around a toroidal axis, allowing both running
surfaces thereof to flex in full coordination. By providing the matching flexibility, the
running surfaces remain substantially parallel to each during operation of the
drivetrain, thereby allowing full contact between the bearing 38 and the shaft 28 so as
to build hydrodynamic pressure or in the case of mixed friction, to share the load to
minimize peak loads. The bearing 38 could also have a soft running surface to
accommodate uneven counter surfaces and/or particles in the oil.
[0046] In such embodiments, if an angular misalignment of the shaft 28 occurs
during operation of the drivetrain (See e.g. FIG. 4), the flexible hinge(s) 44, 46 is
configured to tilt to define an axial gap 62 between an upper rotor-side portion 64 of
the bearing 38 and an upper portion 66 of the rotor-side wall 52 such that only lower
bearing pads 60 and a lower portion 67 of the rotor-side wall 52 carry a load.
[0047] Referring now to FIGS. 8A and 8B, the bearing assembly 30 may also
include one or more flexible components 68 mounted around the gearbox 26. More
specifically, FIG. 8A illustrates a side view of one embodiment of the rotor shaft 28
of the wind turbine 10 according to the present disclosure, particularly illustrating the
bearing assembly 30 engaged with the rotor shaft 28 and the flexible components 68
mounted in an aligned location around the gearbox 26. Alternatively, as shown in
FIG. 8B, a side view of one embodiment of the rotor shaft 28 according to the present
disclosure is illustrated, particularly illustrating the bearing assembly 30 engaged with
the rotor shaft 28 and the flexible components 68 mounted in an offset location
around the gearbox 26 so as to offset a weight-load and thrust of the rotor such that a
nominal load is taken at a neutral misalignment position.
[0048] Referring now to FIGS. 9 and 10A-10C, the rotor shaft 28 may also
include at least one flexible hinge 76 adjacent to the bearing 38. For example, as
shown, the flexible hinge 76 may provide toroidal flexibility to the shaft 28 (similar to
the flexible hinges 44, 46 of the bearing housing 32. Further, as shown, the center of
toroidal rotation of the shaft 28 and the bearing housing 32 are illustrated at points 72
and 74, respectively. FIGS. 10A-10C provide further example embodiments of
shaft/bearing housing configurations according to the present disclosure. More
specifically, as shown, FIG. 10A illustrates the shaft 28 having a single flexible hinge
76. In such an embodiment, the flexible hinges 44, 76 may be positioned on opposing
sides of the center 80 of the bearing assembly. In another embodiment, as shown in
FIGS. 10B and 10C, the shaft 28 has opposing flexible hinge 76, 78.
[0049] In additional embodiments, the bearing housing 32 and/or the shaft 28
may be constructed, at least in part, of a compliant material so as to provide a desired
flexibility thereto.
[0050] In still further embodiments, due to the corresponding deformation
described herein, the bearing assembly 30 may be absent of bearing pads such that the
design is simplified over conventional bearing designs.
[0051] It should be understood that the bearing(s) of the drivetrain assembly
described herein may correspond to any type of bearing, including but not limited to
journal bearings, thrust bearings, axial bearings, and/or radial bearings. Accordingly,
in certain embodiments, the bearing(s) may be placed (e.g. by sliding, securing,
mounting, or printing) or otherwise added onto the various shafts described herein. In
another embodiment, the bearing(s) may be constructed of a metal or metal alloy,
including, for example, a copper alloy (e.g. bronze) and/or polyetheretherketone
(PEEK). Thus, the bearing(s) may provide improved wear characteristics under
loading (especially at startup and shutdown, when an oil film may be insufficient to
separate the rotating and non-rotating surfaces).
[0052] This written description uses examples to disclose the invention, including
the best mode, and also to enable any person skilled in the art to practice the
invention, including making and using any devices or systems and performing any
incorporated methods. The patentable scope of the invention is defined by the claims,
and may include other examples that occur to those skilled in the art. Such other
examples are intended to be within the scope of the claims if they include structural
elements that do not differ from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from the literal languages
of the claims.

We claim:
1. A bearing assembly for a drivetrain of a wind turbine, the bearing
assembly comprising:
a shaft comprising a circumferential outer surface;
a bearing housing arranged circumferentially around the circumferential outer
surface of the shaft, the bearing housing comprising at least deformation such that the
bearing housing and the shaft have a corresponding deformation around a toroidal
axis such that interfacing surfaces of the bearing housing and the shaft flex together
and remain parallel during operation of the drivetrain, thereby distributing operational
loads of the drivetrain; and,
a bearing housed at least partially within the bearing housing, the bearing
engaging the circumferential outer surface of the shaft.
2. The bearing assembly of claim 1, wherein the at least deformation is
caused by a flexible hinge, the bearing housing further comprising a base portion and
a bearing contacting portion adjacent to the bearing, the at least one flexible hinge
allowing the bearing housing to tilt.
3. The bearing assembly of claim 2, wherein the bearing housing
comprises symmetrical opposing flexible hinges.
4. The bearing assembly of claim 2, further comprising a cavity on the
circumferential outer surface of the shaft that receives and secures the bearing in
place, the cavity defining a base wall and opposing side walls.
5. The bearing assembly of claim 4, wherein at least one of the opposing
side walls is formed via a removable ring secured to the circumferential outer surface
of the shaft.
6. The bearing assembly of claim 4, wherein a lengthwise cross-section
of the bearing is curved prior to being secured into the cavity so as to provide a
desired preload over a length of the bearing.
7. The bearing assembly of claim 4, further comprising one or more
bearing pads within the cavity on one or more sides of the bearing.
8. The bearing assembly of claim 4, wherein the opposing side walls
comprise a rotor-side wall and a generator-side wall, wherein, if an angular
misalignment of the shaft occurs during operation of the drivetrain, the flexible hinge
is configured to tilt to define an axial gap between an upper rotor-side portion of the
bearing and an upper portion of the rotor-side wall such that only lower bearing pads
and a lower portion of the rotor-side wall carry a load.
9. The bearing assembly of any of the preceding claims, wherein the shaft
comprises at least one flexible hinge adjacent to the bearing.
10. The bearing assembly of any of the preceding claims, wherein the
bearing housing and the shaft are constructed, at least in part, of a compliant material.
11. The bearing assembly of any of the preceding claims, wherein the
bearing comprises at least one of a journal bearing, a thrust bearing, an axial bearing,
or a radial bearing, and the shaft comprises a low-speed shaft of the drivetrain.
12. The bearing assembly of claim 11, wherein the bearing comprises the
journal bearing, the shaft comprising the low-speed shaft coupling a rotor of the wind
turbine to a gearbox of the wind turbine, the bearing assembly further comprising one
or more flexible components mounted in an offset location around the gearbox so as
to offset a weight-load and thrust of the rotor such that a nominal load is taken at a
neutral misalignment position.
13. The bearing assembly of any of the preceding claims, wherein the
bearing assembly is absent of bearing pads.
14. A drivetrain assembly, comprising:
a rotor;
a low-speed shaft rotatably coupled to the rotor, the low-speed shaft
comprising a circumferential outer surface;
a gearbox rotatably coupled to the low-speed shaft; and,
a bearing assembly comprising:
a bearing housing arranged circumferentially around the
circumferential outer surface of the low-speed shaft, the bearing housing
comprising at least deformation such that the bearing housing and the lowspeed shaft have a corresponding deformation around a toroidal axis such that
interfacing surfaces of the bearing housing and the low-speed shaft flex
together and remain parallel during operation of the drivetrain assembly,
thereby distributing operational loads of the drivetrain assembly; and,
a journal bearing housed at least partially within the bearing housing,
the journal bearing engaging the circumferential outer surface of the lowspeed shaft.
15. The drivetrain assembly of claim 14, wherein the at least deformation
is caused by a flexible hinge, the bearing housing further comprising a base portion
and a bearing contacting portion adjacent to the bearing, the at least one flexible hinge
allowing the bearing housing to tilt.