U.S. patent application number 12/352732 was filed with the patent office on 2009-09-24 for method of servicing a power generator.
This patent application is currently assigned to SIEMENS ENERGY, INC.. Invention is credited to David T. Allen, Craig P. Notarange.
Application Number | 20090235516 12/352732 |
Document ID | / |
Family ID | 41087473 |
Filed Date | 2009-09-24 |
United States Patent
Application |
20090235516 |
Kind Code |
A1 |
Notarange; Craig P. ; et
al. |
September 24, 2009 |
Method of Servicing a Power Generator
Abstract
A method of servicing a stator frame of a power generator. The
method includes removing a first stator core from a main housing of
the stator frame, removing a plurality of first dove-tail shaped
keybars that extend axially within and are coupled to a main
support structure forming part of the main housing, and installing
a plurality of second keybars in the main support structure. The
second keybars are adapted to support a second stator core. Each of
the second keybars has a generally rounded engagement surface and
the second stator core includes recesses with shapes corresponding
to the generally rounded engagement surfaces of the second keybars
such that the second stator core can be securely supported in the
main support structure by the second keybars.
Inventors: |
Notarange; Craig P.;
(Orlando, FL) ; Allen; David T.; (Longwood,
FL) |
Correspondence
Address: |
SIEMENS CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
170 WOOD AVENUE SOUTH
ISELIN
NJ
08830
US
|
Assignee: |
SIEMENS ENERGY, INC.
Orlando
FL
|
Family ID: |
41087473 |
Appl. No.: |
12/352732 |
Filed: |
January 13, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61037887 |
Mar 19, 2008 |
|
|
|
Current U.S.
Class: |
29/596 |
Current CPC
Class: |
H02K 1/185 20130101;
H02K 15/0006 20130101; Y10T 29/49009 20150115; H02K 15/06
20130101 |
Class at
Publication: |
29/596 |
International
Class: |
H02K 15/06 20060101
H02K015/06 |
Claims
1. A method of servicing a stator frame of a power generator
comprising: removing a first stator core from a main housing of the
stator frame; removing a plurality of first dove-tail shaped
keybars that extend axially within and are coupled to a main
support structure forming part of the main housing; and installing
a plurality of second keybars in the main support structure adapted
to support a second stator core, each of the second keybars having
a generally rounded engagement surface, the second stator core
having recesses with shapes corresponding to the generally rounded
engagement surfaces of the second keybars such that the second
stator core can be securely supported by the main support structure
via the second keybars.
2. The method according to claim 1, wherein the main support
structure comprises a plurality of stator bore rings and a
plurality of frame beams, the second keybars being coupled to the
frame beams.
3. The method according to claim 2, wherein said step of installing
a plurality of second keybars in the main support structure
comprises bolting the second keybars to the frame beams.
4. The method according to claim 3, wherein said step of bolting
the second keybars to the frame beams comprises installing bolts
into counter-bored holes formed in the second keybars.
5. The method according to claim 3, further comprising installing
the second stator core onto the second keybars.
6. The method according to claim 5, wherein said step of installing
the bolts into counter-bored holes formed in the second keybars
comprises installing the bolts into the counter-bored holes until
end portions of the bolts are inserted past a radially inner
surface of the second keybars.
7. The method according to claim 2, further comprising servicing
the frame beams such that the second stator core can be more easily
axially slid onto the second keybars without the second stator core
contacting the frame beams.
8. The method according to claim 7, wherein said step of servicing
the frame beams comprises removing radially inner corner edges of
the frame beams to create a radial clearance for a radial outer
edge of the second stator core.
9. The method according to claim 8, wherein a portable milling
machine is utilized to remove the radially inner corner edges of
the frame beams.
10. A kit for servicing a stator frame of a power generator, the
stator frame having dove-tail keybars installed therein supporting
a first stator core within a main support structure of a main
housing, said kit comprising: a plurality of second keybars each
having a generally rounded engagement surface and adapted to
replace the dove-tail shaped keybars installed in the main support
structure, said second keybars being adapted to support a second
stator core in the main support structure, the second stator core
having recesses with shapes corresponding to the generally rounded
engagement surfaces of the second keybars; and fasteners to couple
said second keybars to the main support structure of the main
housing.
11. The kit according to claim 10, wherein the main support
structure comprises a plurality of stator bore rings and a
plurality of frame beams, said second keybars being coupled to said
frame beams with said fasteners.
12. The kit according to claim 11, wherein said fasteners comprise
bolts.
13. The kit according to claim 12, wherein said bolts are installed
through counter-bored holes in said second keybars.
14. The kit according to claim 13, wherein end portions of said
second keybars extend further radially inwardly than a radial end
of said bolts.
15. The kit according to claim 10, further comprising a portable
milling machine for removing radially inner corner edges of said
frame beams to create a radial clearance for a radial outer edge of
said second stator core.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 61/037,887, entitled CORE TO FRAME ATTACHMENT
IN A UNIT WITHOUT BUILDING BOLTS, filed Mar. 19, 2008, the entire
disclosure of which is incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates to power generators, and more
particularly, to a method of servicing stator frames in power
generators.
BACKGROUND OF THE INVENTION
[0003] U.S. Pat. No. 5,875,540, the entire disclosure of which is
incorporated by reference herein, discloses a process for forming a
stator core in a stator frame. The process involves forming a
plurality of core modules or donuts, each of which comprises a
plurality of stator core rings laminated together. The stator frame
is placed in an upright position. A predefined number of the core
modules are then lowered into the upright stator frame. For a power
generator which has been in operation for some time and is in need
of a new stator core, turning its stator frame upright to receive a
new stator core can be very difficult.
[0004] U.S. Pat. Nos. 7,302,754; 7,353,586; and 7,395,594, the
entire disclosures of which are incorporated by reference herein,
are directed at installing stator cores into stator frames without
placing the stator frame in an upright position. U.S. Pat. No.
7,202,587, the entire disclosure of which is also incorporated by
reference herein, discloses mounting stator core donuts having
enlarged grooves in a stator frame using wedges that disperse
forces to the donuts in a circumferential manner. The enlarged
grooves make installing the donuts less difficult, while the wedges
ensure a tight fit of the laminations within the stator frame.
[0005] FIG. 1 illustrates a known stator frame 10 for a power
generator. The stator frame 10 comprises a main housing 11 for
supporting a stator core, not shown in FIG. 1. The main housing 11
comprises an outer structure 13 and a main support structure 15
coupled to the outer structure 13. The main support structure 15
comprising a plurality of stator bore or support rings 18 coupled
to the outer structure 13 and a plurality of frame beams 16 coupled
to the stator bore rings 18. The main housing 11 further comprises
a plurality of dove-tail shaped building bolts or keybars 12
coupled to the frame beams 16. The stator core, not shown in FIG.
1, is supported in the stator frame 10 via the keybars 12.
[0006] FIG. 2 illustrates a stator core lamination or donut 14
comprising a plurality of stator core rings (also referred to as
laminations) laminated or otherwise coupled together and configured
to be supported on the keybars 12 illustrated in FIG. 1. It is
noted that a plurality of the stator core donuts 14 are stacked
together within the stator frame 10 to form the stator core.
Referring now to FIG. 2, each stator core donut 14 includes a
plurality of slots or grooves 20 (see FIG. 3) along its outer
periphery to receive the keybars 12. The grooves 20 have a
dove-tail shape corresponding to the shape of the keybars 12 to
ensure a secure and tight fit within the stator frame 10, as more
clearly shown in FIG. 3. It is noted that small radial gaps 21 are
formed between the periphery of each stator core donut 14 and the
inner diameter of the support rings 18, as shown in FIG. 2. It is
also noted that one or more mounting assist structures 23A, 23B,
23C may be disposed in each groove 20 between the stator core donut
14 and the corresponding keybar 12. The mounting assist structures
23A, 23B, 23C assist in securing a tight fit between the stator
core donut 14 and the keybars 12.
SUMMARY OF THE INVENTION
[0007] In accordance with a first aspect of the present invention,
a method of servicing a stator frame of a power generator is
provided. The method comprises removing a first stator core from a
main housing of the stator frame, removing a plurality of first
dove-tail shaped keybars that extend axially within and are coupled
to a main support structure forming part of the main housing, and
installing a plurality of second keybars in the main support
structure. The second keybars are adapted to support a second
stator core. Each of the second keybars has a generally rounded
engagement surface and the second stator core includes recesses
with shapes corresponding to the generally rounded engagement
surfaces of the second keybars such that the second stator core can
be securely supported by the main support structure via the second
keybars.
[0008] The main support structure may comprise a plurality of
stator bore rings and a plurality of frame beams, wherein the
second keybars are coupled to the frame beams.
[0009] Installing a plurality of second keybars in the main support
structure may comprise bolting the second keybars to the frame
beams.
[0010] Bolting the second keybars to the frame beams may comprise
installing bolts into counter-bored holes until end portions of the
bolts are inserted past a radially inner surface of the second
keybars.
[0011] The method may further comprise installing the second stator
core onto the second keybars.
[0012] The method may further comprise servicing the frame beams
such that the second stator core can be more easily axially slid
onto the second keybars without the second stator core contacting
the frame beams.
[0013] Servicing the frame beams may comprise removing radially
inner corner edges of the frame beams to create a radial clearance
for a radial outer edge of the second stator core.
[0014] A portable milling machine may be utilized to remove the
radially inner corner edges of the frame beams.
[0015] In accordance with a second aspect of the present invention,
a kit for servicing a stator frame of a power generator is
provided, wherein the stator frame includes dove-tail keybars
installed therein supporting a first stator core within a main
support structure of a main housing. The kit comprises a plurality
of second keybars and fasteners to couple the second keybars to the
main support structure of the main housing. Each of the second
keybars has a generally rounded engagement surface and is adapted
to replace the dove-tail shaped keybars installed in the main
support structure. The second keybars are adapted to support a
second stator core in the main support structure. The second stator
core includes recesses with shapes corresponding to the generally
rounded engagement surfaces of the second keybars.
[0016] The main support structure may comprise a plurality of
stator bore rings and a plurality of frame beams, wherein the
second keybars are coupled to the frame beams with the
fasteners.
[0017] The fasteners may comprise bolts, which may be installed
through counter-bored holes in the second keybars.
[0018] End portions of the second keybars may extend further
radially inwardly than a radial end of the bolts.
[0019] The kit may further comprise a portable milling machine for
removing radially inner corner edges of the frame beams to create a
radial clearance for a radial outer edge of the second stator
core.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] While the specification concludes with claims particularly
pointing out and distinctly claiming the present invention, it is
believed that the present invention will be better understood from
the following description in conjunction with the accompanying
Drawing Figures, in which like reference numerals identify like
elements, and wherein:
[0021] FIG. 1 is a cut-away perspective view of a prior art
generator frame including an annular array of dove-tail shaped
keybars;
[0022] FIG. 2 is a cross sectional view of an inner portion of the
prior art generator frame illustrated in FIG. 1 and further
including a prior art stator core donut;
[0023] FIG. 3 is an enlarged cross sectional view of a portion of
the prior art generator frame and a portion of the stator core
donut illustrated in FIG. 2;
[0024] FIG. 4 is a cross sectional view of a portion of a generator
frame including a replacement donut after the generator frame has
been serviced according to embodiments of the invention;
[0025] FIG. 5 is an enlarged cross sectional view of a portion of
the replacement donut illustrated in FIG. 4 and a replacement
keybar installed in the generator frame illustrated in FIG. 4
during the servicing thereof; and
[0026] FIG. 6 is an exploded perspective view of a portion of the
replacement keybar illustrated in FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
[0027] In the following detailed description of the preferred
embodiments, reference is made to the accompanying drawings that
form a part hereof, and in which is shown by way of illustration,
and not by way of limitation, specific preferred embodiments in
which the invention may be practiced. It is to be understood that
other embodiments may be utilized and that changes may be made
without departing from the spirit and scope of the present
invention.
[0028] After periods of electrical power generator use, it may
become necessary to replace a stator core within a stator core
frame of the power generator. As mentioned above, U.S. Pat. Nos.
7,302,754; 7,353,586; and 7,395,594 are directed at installing
stator cores into stator frames without placing the stator frame in
an upright position. Typically, the systems, structures, and
methods disclosed by these patents are utilized with keybars having
rounded engagement surfaces, i.e., the keybars are generally
rounded in shape. This is because replacement of a stator core onto
rounded keybars using a horizontal replacement process is believed
to be easier and more efficient as compared to replacement of a
stator core onto dove-tail shaped keybars.
[0029] As shown in FIG. 1, a power generator stator frame 10 may
comprise a main housing 11 for supporting a stator core, not shown
in FIG. 1. The main housing 11 comprises an outer structure 13 and
a main support structure 15 coupled to the outer structure 13. The
main support structure 15 comprising a plurality of stator bore
rings 18 fixedly coupled to the outer structure 13 and a plurality
of frame beams 16 fixedly coupled to the stator bore rings 18. The
main housing 11 further comprises a plurality of building bolts or
keybars 12, which are dove-tail shaped in FIG. 1, and coupled to
the frame beams 16. The stator core, not shown in FIG. 1, is
supported in the stator frame 10 via the keybars 12.
[0030] In accordance with the present invention, after a stator
core mounted to dove-tail shaped keybars 12 of a stator frame 10 is
removed, the dove-tail shaped keybars 12 are then removed and
replaced with generally rounded or cylindrical-shaped keybars
followed by the installation of a new stator core onto the rounded
keybars. By replacing the dove-tail shaped keybars 12 with rounded
keybars, it is believed that installation of the new stator core
within the stator core frame having rounded keybars will be
accomplished in a more efficient manner.
[0031] Donuts 14 mounted on dove-tail shaped keybars 12, see FIGS.
1-3, and defining a stator core to be replaced, are removed
according to any traditional method(s) for removing such a stator
core from a corresponding stator frame. For example, the stator
core donuts 14 may be individually removed one by one by axially
sliding the stator core donuts 14 along the dove-tail shaped
keybars 12 until all stator core donuts 14 are removed from the
stator frame 10. It is noted that donuts 14 comprise two or more
stator core rings laminated together. Instead of using donuts 14 in
the present invention, individual stator core rings or laminations
may be used instead.
[0032] Once the stator core donuts 14 are removed from the stator
frame 10, the dove-tail shaped keybars 12 are removed from the
frame beams 16 by removing fasteners 22, such as bolts, extending
through counter-bored holes 24 (see FIG. 3) formed in the keybars
12 and through corresponding holes 25 formed in the frame beams 16.
Removing the fasteners 22 frees each keybar 12 from its respective
frame beam 16.
[0033] In order for a replacement donut 30 (see FIG. 4) to be more
easily installed in the stator frame 10 and in accordance with the
present invention, one or more of the frame beams 16 are serviced
by removing radially inner corner edges 16A.sub.1, 16B.sub.1 (see
FIG. 3) of the frame beams 16, such that the modified frame beams
16' comprise beveled radially inner corner edges 16A.sub.2,
16B.sub.2 (see FIG. 5). The beveled radially inner corner edges
16A.sub.2, 16B.sub.2 provide an amount of radial clearance between
the frame beams 16' and a radial outer edge 30A of each of the
replacement donuts 30. The beveled radially inner corner edges
16A.sub.2, 16B.sub.2 may be formed in the frame beams 16', for
example, by grinding the radially inner corner edges 16A.sub.1,
16B.sub.1 using a portable milling machine (not shown), such as,
for example, a TKF1500-0 model adjustable angle beveller
manufactured by Trumpf Inc. of Farmington, Conn.
[0034] Replacement building bolts or keybars 32 are then installed
on the frame beams 16' in generally the same locations as the
previously removed keybars 12. As shown in FIG. 5, the replacement
keybars 32 are generally rounded in shape and comprise a generally
rounded engagement surface 34 instead of the dove-tail shape of the
removed keybars 12.
[0035] The replacement keybars 32 include counter-bored holes 36
formed therein, as shown in FIGS. 5 and 6, which counter-bored
holes 36 may be substantially aligned with the holes 25 formed in
the frame beams 16', although it is understood that new holes (not
shown) may be formed in the frame beams 16' and aligned with the
counter-bored holes 36 in the replacement keybars 32 if desired.
Fasteners 38, depicted in FIGS. 5 and 6 as bolts, are then inserted
into the counter-bored holes 36 in the replacement keybars 32 and
threaded into the corresponding holes 25 in the frame beams 16' to
secure the replacement keybars 32 to the frame beams 16'. The
fasteners 38 may be inserted into the counter-bored holes 36 until
a radially inner surface 32A of the corresponding replacement
keybar 32 extends further radially inwardly than an end portion 38A
of each of the fasteners 38, i.e., until the fasteners 38 are not
extending out past the radially inner surfaces 32A of the
replacement keybars 32. Thus, the replacement donuts 30 can be
axially slid on the replacement keybars 32 without contacting the
fasteners 38.
[0036] As shown in FIG. 5, the replacement donuts 30 include
grooves 50. Each replacement donut 30 is positioned relative to the
stator frame 10 such that each groove 50 is aligned with a
corresponding replacement keybar 32. Thereafter, the replacement
donut 30 is horizontal moved into the stator frame such that the
replacement keybars 32 are received in a corresponding one of the
grooves 50 in the replacement donut 30. The replacement donuts 30
may be installed into the stator frame using the structures and
methods set out in U.S. Pat. Nos. 7,302,754, 7,353,586, and
7,395,594. Alternatively, any other suitable structures and methods
can be used to install the replacement donuts 30 into the stator
frame 10. A plurality of donuts 30 are installed in this fashion
until a predetermined number have been installed so as to define a
replacement stator core.
[0037] In the illustrated embodiment, the grooves 50 are slightly
oversized to allow for easier installation of the donuts 30 onto
the replacement keybars 32. So as to create a tight fit between
each donut 30 and the replacement keybars 32, first and second
wedge structure assemblies 54 and 56 are provided in each groove 50
between the donut 30 and the corresponding keybar 32, see FIG. 5.
Each of the first and second wedge structure assemblies 54, 56 in
the embodiment shown comprises a filler member 54A, 56A, and first
and second wedges 54B, 54C and 56B, 56C. In the illustrated
embodiment, six donuts 30, each having a width of about six inches,
are set in position. Thereafter, the first and second wedges 54B,
54C and 56B, 56C and filler members 54A, 56A, each about 36 inches
long, are installed. The first and second wedge structure
assemblies 54 and 56 are utilized to aid in mounting the
replacement donuts 30 on the replacement keybars 32 and to secure a
tight fit between the replacement donuts 30 and the replacement
keybars 32. It is understood that other types of mounting assist
structures may be used as desired.
[0038] As noted above, the replacement of a stator core onto
rounded keybars using a horizontal replacement process is believed
to be easier and more efficient as compared to replacement of a
stator core onto dove-tail shaped keybars. Hence, replacing the
dove-tail shaped keybars 12 with the replacement keybars 32
facilitates an easier replacement of a stator core within the
stator frame 10. In particular, since tooling, methods, and
structure have been developed to replace stator cores within stator
frames using horizontal processes and cylindrical-shaped keybars,
these developed tooling, methods, and structure can be utilized in
the stator frames 10 once the replacement keybars 32 are installed.
For example, the use of the replacement donuts 30 and the first and
second wedge structure assemblies 54, 56 with the replacement
cylindrical-shaped keybars 32 avoids developing new tooling,
methods, and structure that would be required to use a horizontal
process to replace a stator core in a stator frame that includes
dove-tail shaped keybars.
[0039] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *