U.S. patent application number 12/833569 was filed with the patent office on 2012-01-12 for compressible supports for turbine engines.
This patent application is currently assigned to General Electric Company. Invention is credited to Kenneth Damon Black, Donald Earl Floyd, II.
Application Number | 20120009058 12/833569 |
Document ID | / |
Family ID | 45372726 |
Filed Date | 2012-01-12 |
United States Patent
Application |
20120009058 |
Kind Code |
A1 |
Floyd, II; Donald Earl ; et
al. |
January 12, 2012 |
COMPRESSIBLE SUPPORTS FOR TURBINE ENGINES
Abstract
A system is provided that includes a first turbine alignment
component for a turbine engine; and a shim comprises a metal foam.
The shim mounts between a first surface of the first turbine
alignment component and a second surface of a second turbine
alignment component.
Inventors: |
Floyd, II; Donald Earl;
(Greenville, SC) ; Black; Kenneth Damon;
(Travelers Rest, SC) |
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
45372726 |
Appl. No.: |
12/833569 |
Filed: |
July 9, 2010 |
Current U.S.
Class: |
415/213.1 ;
415/232 |
Current CPC
Class: |
F01D 25/28 20130101 |
Class at
Publication: |
415/213.1 ;
415/232 |
International
Class: |
F01D 25/28 20060101
F01D025/28; F01D 25/00 20060101 F01D025/00 |
Claims
1. A system, comprising: a turbine engine comprising a turbine
shell; a support assembly configured to support the turbine engine,
wherein the support assembly comprises a keyway defined by at least
first and second protrusions; a gib extending from the turbine
shell and configured to mate with the keyway; and a first shim
disposed between the gib and the first protrusion, wherein the
first shim comprises a metal foam.
2. The system of claim 1, wherein the metal foam comprises at least
one of FeCrAlY, stainless steel, copper, nickel or aluminum.
3. The system of claim 1, wherein the metal foam comprises a
relative density of at least equal to or greater than approximately
5%.
4. The system of claim 1, wherein the support assembly reduces or
blocks lateral movement of the turbine shell.
5. The system of claim 1, comprising a second shim disposed between
the gib and the second protrusion, wherein the second shim
comprises the metal foam.
6. The system of claim 1, wherein the support assembly comprises at
least one of a bearing, a lubrication system, and a rotor, at an
end portion of a turbine stage of the turbine engine.
7. A system, comprising: a first turbine alignment component for a
turbine engine; and a shim comprising a metal foam, wherein the
shim mounts between a first surface of the first turbine alignment
component and a second surface of a second turbine alignment
component.
8. The system of claim 7, comprising a wear pad, wherein the shim
is disposed between the first surface and the wear pad.
9. The system of claim 8, wherein the wear pad comprises stellite
or stainless steel.
10. The system of claim 8 comprising a fastener coupling the wear
pad to the shim.
11. The system of claim 8, comprising a keeper plate configured to
hold the shim and the wear pad in position along the first
surface.
12. The system of claim 7, wherein the first turbine alignment
component comprises a protrusion and the second turbine alignment
component comprises a gib.
13. The system of claim 7, wherein the first turbine alignment
component comprises a gib and the second turbine alignment
component comprises a protrusion.
14. A system, comprising: a support feature for a turbine engine,
comprising: a keyway having a bottom, a first side, and a second
side opposite from the first side; a key configured to insert in
the keyway and provide lateral alignment of a turbine shell of the
turbine engine; and a first shim disposed in the keyway between the
key and the first side, and a second shim disposed in the keyway
between the key and the second side, wherein the first shim and the
second shim comprise a metal foam.
15. The system of claim 14, wherein the first side comprises a
first recess configured to receive the first shim and the second
side comprises a second recess configured to receive the second
shim.
16. The system of claim 15, comprising a first keeper plate
configured to retain the first shim in the first recess and a
second keeper plate configured to retain the second shim in the
second recess.
17. The system of claim 15, comprising a first wear pad disposed
between the first shim and the key and a second wear pad disposed
between the second shim and the key.
18. The system of claim 15, wherein first pad and the second pad
are configured to receive shear forces exerted by the key in the
keyway.
19. The system of claim 15, wherein the first pad is coupled to the
first shim and the second pad is coupled to the second shim.
20. The system of claim 15, wherein the metal foam comprises
FeCrAlY, stainless steel, copper, nickel, or aluminum.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to turbine
engines and, more specifically, to assembly, support, and alignment
of components of the turbine engines.
[0002] In certain applications, turbines may include various
sections designed to be assembled during installation. Each turbine
may be encased by a turbine shell and its bearings supported by a
"standard" (also referred to as a "pedestal) or exhaust frame. The
turbine shells may include arms or other extensions that may be
supported by the standard, such as through a vertical support on
the standard itself. The turbine shells may also be vertically
supported by legs that attach to ground.
[0003] A bearing housing generally covers and protects the bearings
of the turbine. During installation, the bearing housing is
positioned such that the rotor is concentric with the turbine shell
to avoid interference with the other components. Supports on the
exhaust frame may engage a support part on the bearing housing to
vertically and/or horizontally align and support the bearing
housing. Clearances may increase or decrease during operation
depending on the support of the exhaust frame and the bearing
housing support part. These changes in clearance may introduce
uncertainty in the position of the bearing relative to the
stationary components and may result in rubbing or interference
between such components.
[0004] The turbine shell generally covers and protects the rotary
components of the turbine. During installation, the turbine shell
is generally aligned with rotary components to avoid interference
with the components. Supports to ground may engage a support part
on the turbine shell to vertically and/or horizontally align and
support the turbine shell. Achieving desired clearances may be
difficult due to thermal expansion of the support part and/or the
support of the standards. For example, clearances may increase or
decrease during operation depending on the configuration of the
support of the standard and the support part. These changing
clearances may introduce uncertainty in the position of the turbine
shell relative to the rotary components and may eventually result
in rubbing or interference between such components.
BRIEF DESCRIPTION OF THE INVENTION
[0005] Certain embodiments commensurate in scope with the
originally claimed invention are summarized below. These
embodiments are not intended to limit the scope of the claimed
invention, but rather these embodiments are intended only to
provide a brief summary of possible forms of the invention. Indeed,
the invention may encompass a variety of forms that may be similar
to or different from the embodiments set forth below.
[0006] In a first embodiment, a system includes a turbine engine
having a turbine shell, a support assembly configured to support
the turbine engine, wherein the support assembly comprises a keyway
defined by at least first and second protrusions, a gib extending
from the turbine shell and configured to mate with the keyway and a
first shim disposed between the gib and one of the first
protrusion, wherein the first shim comprises a metal foam.
[0007] In a second embodiment, a system a first turbine alignment
component for a turbine engine and a shim comprising a metal foam,
wherein the shim mounts between a first surface of the first
turbine alignment component and a second surface of a second
turbine alignment component.
[0008] In a third embodiment, a system includes a support feature
for a turbine engine having a keyway having a bottom, a first side,
and a second side opposite from the first side; a key configured to
insert in the keyway and provide lateral alignment of a turbine
shell of the turbine engine, and a first shim disposed in the
keyway between the key and the first side, and a second shim
disposed between the key and the second side, wherein the first
shim and the second shim comprise a metal foam.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] These and other features, aspects, and advantages of the
present invention will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
[0010] FIG. 1 is a schematic flow diagram of an embodiment of a
combined cycle power generation system having a gas turbine, a
steam turbine, and a heat recovery steam generation (HRSG)
system;
[0011] FIG. 2 is a perspective view of a turbine standard and a
turbine shell in accordance with an embodiment of the present
invention;
[0012] FIG. 3 is a schematic front view of a turbine support
feature in accordance with an embodiment of the present
invention;
[0013] FIG. 4 is a stress/strain curve of a metal foam in
accordance with an embodiment of the present invention;
[0014] FIG. 5 is a perspective view of a keyway protrusion of the
turbine support feature of FIG. 3 in accordance with an embodiment
of the present invention; and
[0015] FIG. 6 is a perspective view of a keyway protrusion of the
turbine support feature of FIG. 3 in accordance with an embodiment
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0016] One or more specific embodiments of the present invention
will be described below. In an effort to provide a concise
description of these embodiments, all features of an actual
implementation may not be described in the specification. It should
be appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation-specific decisions must be made to achieve the
developers' specific goals, such as compliance with system-related
and business-related constraints, which may vary from one
implementation to another. Moreover, it should be appreciated that
such a development effort might be complex and time consuming, but
would nevertheless be a routine undertaking of design, fabrication,
and manufacture for those of ordinary skill having the benefit of
this disclosure.
[0017] When introducing elements of various embodiments of the
present invention, the articles "a," "an," "the," and "said" are
intended to mean that there are one or more of the elements. The
terms "comprising," "including," and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements.
[0018] Embodiments of the present invention include a compliant
shim (e.g., a metal foam shim) for aligning turbine components,
e.g., turbine shells, of a steam or gas turbine, that are supported
on a turbine support, e.g., a standard. The metal foam shim may be
installed as a shim between a keyway of a turbine component and a
gib of a turbine support. During operation, the metal foam shim may
compress in response to thermal expansion of the hot turbine
component to ensure that the desired clearances remain between the
keyway and the gib. In some embodiments, a wear pad, e.g., a
stellite wear pad, may be provided between the metal foam shim and
the keyway to support any shear load exerted by the gib and/or the
keyway. In certain embodiments, the thickness, relative density,
and material for the metal foam shim may be chosen to ensure that
the metal foam shim provides desired linear elasticity and long
operating life.
[0019] FIG. 1 is a schematic flow diagram of an embodiment of a
combined cycle power generation system 10 having a gas turbine 12,
a steam turbine 22, and a heat recovery steam generation (HRSG)
system 32. System 10 may employ one or more support features to
align various components in the gas turbine 12, the steam turbine
22, and/or the HRSG 12. As discussed below, the support features
include one or more compliant shims (e.g., metal foam shims) to
maintain suitable clearances despite thermal expansion of hot
turbine components.
[0020] The system 10 may include the gas turbine 12 for driving a
first load 14. The first load 14 may, for instance, be an
electrical generator for producing electrical power. The gas
turbine 12 may include a turbine 16, a combustor or combustion
chamber 18, and a compressor 20. The system 10 may also include the
steam turbine 22 for driving a second load 24. The second load 24
may also be an electrical generator for generating electrical
power. However, both the first and second loads 14, 24 may be other
types of loads capable of being driven by the gas turbine 12 and
steam turbine 22. In addition, although the gas turbine 12 and
steam turbine 22 may drive separate loads 14 and 24, as shown in
the illustrated embodiment, the gas turbine 12 and steam turbine 22
may also be utilized in tandem to drive a single load via a single
shaft. In the illustrated embodiment, the steam turbine 22 may
include one low-pressure section 26 (LP ST), one
intermediate-pressure section 28 (IP ST), and one high-pressure
section 30 (HP ST). However, the specific configuration of the
steam turbine 22, as well as the gas turbine 12, may be
implementation-specific and may include any combination of
sections.
[0021] Each section of the steam turbine 22, e.g., the low pressure
section 26, the intermediate pressure section 28, and the
high-pressure section 30, may be generally supported and separated
by mid standards 29 (e.g., pedestals). Similarly, end standards 31
(e.g., pedestals) may be generally support the ends of the high
pressure section 30 and the low pressure section 26. The standards
29 and 31 may be disposed along the axis of the turbine 22, and may
include various components such as supports, pickups, and piping
between the turbine sections 26, 28, and 30. As described in detail
below, the standards 29 and 31 may also provide for lateral (i.e.,
horizontal) alignment of the turbine shells of the sections 26, 28,
and 30, though engagement of a gib and keyway. The engagement
between the gib and the keyway may be adjusted through the use the
metal foam shims described herein. It should be appreciated that
the gas turbine 12 may also include a similar arrangement of one or
more sections and standards, and the gas turbine 12 may also
utilize a gib, keyway, and metal foam shims for lateral alignment,
as discussed below.
[0022] The system 10 may also include the multi-stage HRSG 32. The
components of the HRSG 32 in the illustrated embodiment are a
simplified depiction of the HRSG 32 and are not intended to be
limiting. Rather, the illustrated HRSG 32 is shown to convey the
general operation of such HRSG systems. Heated exhaust gas 34 from
the gas turbine 12 may be transported into the HRSG 32 and used to
heat steam used to power the steam turbine 22. Exhaust from the
low-pressure section 26 of the steam turbine 22 may be directed
into a condenser 36. Condensate from the condenser 36 may, in turn,
be directed into a low-pressure section of the HRSG 32 with the aid
of a condensate pump 38.
[0023] The condensate may then flow through a low-pressure
economizer 40 (LPECON), a device configured to heat feedwater with
gases, which may be used to heat the condensate. From the
low-pressure economizer 40, a portion of the condensate may be
directed into a low-pressure evaporator 42 (LPEVAP) while the rest
may be pumped toward an intermediate-pressure economizer 44
(IPECON). Steam from the low-pressure evaporator 42 may be returned
to the low-pressure section 26 of the steam turbine 22. Likewise,
from the intermediate-pressure economizer 44, a portion of the
condensate may be directed into an intermediate-pressure evaporator
46 (IPEVAP) while the rest may be pumped toward a high-pressure
economizer 48 (HPECON). Steam from the intermediate-pressure
evaporator 46 may be sent to the intermediate-pressure section 28
of the steam turbine 22. Again, the connections between the
economizers, evaporators, and the steam turbine 22 may vary across
implementations as the illustrated embodiment is merely
illustrative of the general operation of an HRSG system that may
employ unique aspects of the present embodiments.
[0024] Finally, condensate from the high-pressure economizer 48 may
be directed into a high-pressure evaporator 50 (HPEVAP). Steam
exiting the high-pressure evaporator 50 may be directed into a
primary high-pressure superheater 52 and a finishing high-pressure
superheater 54, where the steam is superheated and eventually sent
to the high-pressure section 30 of the steam turbine 22. Exhaust
from the high-pressure section 30 of the steam turbine 22 may, in
turn, be directed into the intermediate-pressure section 28 of the
steam turbine 22. Exhaust from the intermediate-pressure section 28
of the steam turbine 22 may be directed into the low-pressure
section 26 of the steam turbine 22.
[0025] An inter-stage attemperator 56 may be located in between the
primary high-pressure superheater 52 and the finishing
high-pressure superheater 54. The inter-stage attemperator 56 may
allow for more robust control of the exhaust temperature of steam
from the finishing high-pressure superheater 54. Specifically, the
inter-stage attemperator 56 may be configured to control the
temperature of steam exiting the finishing high-pressure
superheater 54 by injecting cooler feedwater spray into the
superheated steam upstream of the finishing high-pressure
superheater 54 whenever the exhaust temperature of the steam
exiting the finishing high-pressure superheater 54 exceeds a
predetermined value.
[0026] In addition, exhaust from the high-pressure section 30 of
the steam turbine 22 may be directed into a primary re-heater 58
and a secondary re-heater 60 where it may be re-heated before being
directed into the intermediate-pressure section 28 of the steam
turbine 22. The primary re-heater 58 and secondary re-heater 60 may
also be associated with an inter-stage attemperator 62 for
controlling the exhaust steam temperature from the re-heaters.
Specifically, the inter-stage attemperator 62 may be configured to
control the temperature of steam exiting the secondary re-heater 60
by injecting cooler feedwater spray into the superheated steam
upstream of the secondary re-heater 60 whenever the exhaust
temperature of the steam exiting the secondary re-heater 60 exceeds
a predetermined value.
[0027] In combined cycle systems such as system 10, hot exhaust gas
34 may flow from the gas turbine 12 and pass through the HRSG 32
and may be used to generate high-pressure, high-temperature steam.
The steam produced by the HRSG 32 may then be passed through the
steam turbine 22 for power generation. In addition, the produced
steam may also be supplied to any other processes where superheated
steam may be used. The gas turbine 12 cycle is often referred to as
the "topping cycle," whereas the steam turbine 22 generation cycle
is often referred to as the "bottoming cycle." By combining these
two cycles as illustrated in FIG. 1, the combined cycle power
generation system 10 may lead to greater efficiencies in both
cycles. In particular, exhaust heat from the topping cycle may be
captured and used to generate steam for use in the bottoming
cycle.
[0028] FIG. 2 is a perspective view of a turbine standard 70, e.g.,
a mid standard 29 or end standard 31, supporting a turbine shell
72, e.g., a shell of the low pressure section 26, the intermediate
pressure section 28, or the high-pressure section 30. The standard
70 may include an upper half 74 and a lower half 76, and the
turbine shell 72 may include an upper half turbine shell 78 or a
lower half turbine shell 80. The turbine shell 72 may be generally
supported and aligned by a support feature disposed on the standard
70, such as in the region indicated by arrow 79. The support
feature may laterally align and support the turbine shell 72 along
the x-axis, such as in the directions indicated by arrows 81,
through engagement of a gib and keyway and adjustment of one or
more metal foam shims. As noted above, the gas turbine 12 may also
use a support feature to laterally align one or shells of the gas
turbine with standards in a similar manner.
[0029] FIG. 3 is a schematic view of a turbine support feature 82
in accordance with an embodiment of the present invention. As shown
in FIG. 3, the turbine support feature 82 may include a keyway 84
on the standard 70 and a protrusion, e.g., gib 86 (also referred to
as a "key"), extending from the lower turbine shell half 80. They
keyway 84 may be defined by protrusions 88 extending from the
standard 70. The space 83 between the protrusions 88 may define the
keyway 84. In some embodiments, the protrusions may be machined
from the standard 70, welded onto the standard 70, or manufactured
by any suitable technique. The gib 86 is configured to mate with
the keyway 84 and provide alignment and support of the turbine
shell 72 along the x-axis.
[0030] The clearance between the keyway 84 and the gib 86 may be
set during "cold" conditions, e.g., when the turbine section is not
in operation and is below operating temperatures. For example, some
lateral clearance may be provided between the protrusions of the
keyway 84 and the gib 86 to prevent damage to the gib 86. During
operation, as the turbine section and the turbine shell 72 heat,
the gib 86 may thermally expand inside the keyway 84. To ensure the
desired fit between the gib 86 and the keyway 84, one or more
compliant shims (e.g., metal foam shims) 90 may be disposed between
the gib 86 and each protrusion 88 that define the keyway 84. For
example, as shown in FIG. 3, a first metal foam shim 90A may be
inserted between one side of the gib 86 and the protrusion 88, and
a second metal foam shim 90B may be inserted between a second side
of the gib 86 and the protrusion 88. As the turbine shell 70 heats
and the gib 86 grows within the keyway 84, the metal foam shims 90
may be compressed to maintain the desired clearances between the
gib 86 and the sides of the keyway 84.
[0031] As described further below, the metal foam shims 90 may
include FeCrAlY foams, stainless foams, copper foams, Inconel
foams, nickel foams, aluminum foams, or any suitable foam, and the
thickness, relative density, and material for the metal foam may be
selected to ensure that the metal foam maintains linear elasticity
in response to the forces exerted by the expanding gib 86. Further,
the metal foam shims 90 may be compliant enough to prevent damage
to the gib 86 and/or the keyway 84 during thermal expansion of gib
86, yet retain enough stiffness to maintain a desired lateral
alignment between the gib 86 and the keyway 84 and, thus, maintain
alignment of the turbine shell 70. Advantageously, the metal foam
enables adjustment of the support feature when cold to provide
easier assembly. Additionally, the metal foam shim 90 in the
support feature eliminates or minimizes any cold or hot lateral
position uncertainty and enables achievement of tighter clearances
between static and rotating parts of the turbine.
[0032] As mentioned above, the metal foam may be selected to
provide the desired linear elasticity, such as by selecting a metal
foam having a desired yield strength or Young's modulus. As will be
appreciated, both the yield strength and the Young's modulus may be
a function of the relative density. FIG. 4 depicts a stress/strain
curve 94 for an exemplary metal foam, e.g., an FeCrAlY metal foam
having a 15% relative density. As shown in FIG. 4, the y-axis
corresponds to the stress (lbf/in.sup.2) of the metal foam for a
given strain (in/in) on the x-axis. The linear region 96
corresponds to those portion of the stress/strain curve of the
FeCrAlY metal foam that exhibit a linear elasticity. For example,
in the linear region depicted in FIG. 4, the Young's modulus of a
FeCrAlY metal foam may be approximately 61259 psi. Other regions
may include a plateau region 98 in which the stress of the metal
foam does not change with respect to the strain, and a
densification region 99 in which the metal foam increases in
density and stress rapidly increases in response to strain.
[0033] Thus, when selecting a metal foam for use as a shim in the
manner described above, the metal foam may be selected to ensure
that the metal foam provides linear elasticity up to the strain
expected to be induced in the metal foam shim during operation of
the turbine and expansion of the turbine shell 70. As mentioned
above, the metal foam may include FeCrAlY foams, stainless foams,
copper foams, Inconel foams, nickel foams, aluminum foams, or any
suitable metal foam. Further, the metal foam may be include open
cell metal foams or closed cell metal foams. Additionally, the
metal foams used may have a relative density of greater than about
5%, such as at least approximately 5%, 10%, 15%, 20%, 25%, 30%,
35%, 40%, or greater.
[0034] For example, referring to the gib 86 and keyway 84 described
above in FIG. 3, for a gib 86 having a width of approximately 6
inches, a height of approximately 8 inches, and a length of
approximately 20 inches, and for a steady-state gib temperature of
600.degree. F. and 300.degree. F., the stress generated in a 15%
relative density FeCrAlY metal foam, is about 860 psi and within
the linear elastic region 96 depicted in FIG. 4. In addition, for
such an embodiment, the total lateral force generated on the metal
foam is 137,600 lbf.
[0035] In some embodiments, the metal foam shim 90 may be used with
additional components. FIG. 5 depicts a perspective view of an
embodiment of the keyway protrusion 88 having a wear pad 100 and a
keeper plate 102, and FIG. 6 depicts a perspective view of the
keyway protrusion 88 without the keeper plate 102. As shown in FIG.
5, the wear pad 100 may absorb some or all of the shear load,
indicated by arrow 104, exerted by the gib 86 on the keyway
protrusion 88. As shown in FIG. 6, the wear pad 100 may be disposed
between the metal foam shim 90 and the gib 86. In some embodiments,
the wear pad 100 may be stellite, steel, or any other suitable
material or combination thereof. The keeper plate 102 may be used
to retain the metal foam shim 90 and the wear pad 100 in alignment
with the keyway protrusion 88. For example, the keeper plate 102
may retain the wear pad 100 against any shear load exerted on the
pad in the direction illustrated by arrow 104. As also shown in
FIGS. 5 and 6, the wear pad 100 may be mechanically secured to the
metal foam shim 90 by one or more fasteners 106, such as nails,
screws, bolts, rivets, or any other suitable fastener. In other
embodiments, the wear pad 100 may be joined to the metal foam shim
90 with a braze, a weld, an adhesive, or any other suitable
process. Thus, in some embodiments, the wear pad 100 and metal foam
shim 90 may be joined together to form a single component, while in
other embodiments the wear pad 100 may be a separate component from
the metal foam shim 90. In other embodiments, the wear pad 100 may
be omitted and the metal foam shim 90 may be the only component
disposed between the gib 86 and the keyway protrusion 88.
Similarly, the keeper plate 102 may be mechanically secured to the
keyway protrusion 88 by one or more fasteners 108, such as nails,
screws, or any other suitable fastener. As also shown in FIG. 6,
the protrusion 88 may include a recess 110 configured to position
and/or receive the shim 90 in a specific area of the protrusion 88.
This recess 110 may be defined by one or more indentations in or
extensions of the inner surface of the protrusion 88. In some
embodiments, one or more protrusions 88 defining the keyway 84 may
include a recess.
[0036] It should be appreciated that in other embodiments, the
keyway may be located on the turbine shell 70 and the gib 86 may be
located on the turbine standard. In such embodiments, the metal
foam shim 90 may be used to provide desired clearances between the
gib and keyway in the manner described above. Further, it should be
appreciated that the compliant shims (e.g., metal foam shims)
described above may be used in other support features having, for
example, a first and second alignment feature, male and female
alignment features, etc.
[0037] 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 have 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 language of the claims.
* * * * *