U.S. patent application number 13/504487 was filed with the patent office on 2012-08-23 for gas turbine engine component.
This patent application is currently assigned to VOLVO AERO CORPORATION. Invention is credited to Robert Reimers, Rickard Samuelsson.
Application Number | 20120213634 13/504487 |
Document ID | / |
Family ID | 43922323 |
Filed Date | 2012-08-23 |
United States Patent
Application |
20120213634 |
Kind Code |
A1 |
Samuelsson; Rickard ; et
al. |
August 23, 2012 |
GAS TURBINE ENGINE COMPONENT
Abstract
In a gas turbine engine at least one vanes is made of a
composite material and an end part of the vane is fastened to the
ring element by at least a first bracket member arranged in a
corner region formed by the vane and a ring element. The first
bracket member is fastened to the vane by a first fastening device
arranged in association with a first hole extending through the
vane. The first bracket member is fastened to the ring element by a
second fastening device arranged in association with a second hole
extending through the ring element. An opening is arranged in the
ring element. A second bracket member at least partly has an
angular cross section. The second, angled bracket member is
arranged through the opening such as to be positioned on an
opposite side of both the vane and the ring element in relation to
the first bracket member. The second, angled bracket member is
fastened to the first bracket member by the first and second
fastening devices.
Inventors: |
Samuelsson; Rickard;
(Trollhattan, SE) ; Reimers; Robert; (Uddevalla,
SE) |
Assignee: |
VOLVO AERO CORPORATION
Trollhattan
SE
|
Family ID: |
43922323 |
Appl. No.: |
13/504487 |
Filed: |
October 27, 2009 |
PCT Filed: |
October 27, 2009 |
PCT NO: |
PCT/SE2009/000476 |
371 Date: |
May 4, 2012 |
Current U.S.
Class: |
415/209.3 |
Current CPC
Class: |
F01D 9/042 20130101;
Y02T 50/673 20130101; Y02T 50/672 20130101; F05B 2260/301 20130101;
Y02T 50/60 20130101; F05D 2300/603 20130101 |
Class at
Publication: |
415/209.3 |
International
Class: |
F01D 9/04 20060101
F01D009/04 |
Claims
1. Gas turbine engine component, comprising a ring element and a
plurality of circumferentially spaced load carrying vanes extending
in a radial direction of the ring element, wherein at least one of
the vanes is made of a composite material and wherein an end part
of the at least one composite vane is fastened to the ring element
by means of at least a first bracket member arranged in a corner
region formed by the composite vane and the ring element, wherein
the first bracket member is fastened to the composite vane by means
of a first fastening device arranged in association with a first
hole extending through the composite vane, and wherein the first
bracket member is fastened to the ring element by means of a second
fastening device arranged in association with a second hole
extending through the ring element, wherein an opening is arranged
in the ring element and that the component comprises a second
bracket member that at least partly has an angular cross section,
wherein the second, angled bracket member is arranged through the
opening such as to be positioned on an opposite side of both the
composite vane and the ring element in relation to the first
bracket member, and wherein the second, angled bracket member is
fastened to the first bracket member by means of the first and
second fastening devices.
2. Gas turbine engine component according to claim 1, wherein a
first insertion member is arranged in the first hole, wherein the
relative dimensions of the first insertion member and the first
hole are such as to provide a tight radial fit for the first
insertion member in the first hole, and wherein the first insertion
member is fixed in relation to both the first and the second
bracket member.
3. Gas turbine engine component according to claim 1, wherein the
first fastening device is configured to press the first and second
bracket members towards each other from opposite sides of the
composite vane when tightened, wherein the component is arranged in
such a way that each of the first and second bracket members exerts
a pressure directly or indirectly onto its corresponding side of
the composite vane when the first fastening device is
tightened.
4. Gas turbine engine component according to claim 2, wherein the
first fastening device is configured to press the first and second
bracket members towards each other from opposite sides of the
composite vane when tightened, wherein the component is arranged in
such a way that each of the first and second bracket members exerts
pressure directly or indirectly onto its corresponding side of the
composite vane when the first fastening device is tightened, and
the component is arranged in such a way that each of the first and
second bracket members exerts a pressure directly or indirectly
onto opposite sides of the first insertion member, as seen in an
axial direction of the first hole, when the first fastening device
is tightened.
5. Gas turbine engine component according to claim 2, wherein the
first insertion member extends in the first hole along an axial
direction thereof.
6. Gas turbine engine component according to claim 2, wherein the
first insertion member is a bushing member.
7. Gas turbine engine component according to claim 6, wherein the
first fastening device comprises a first fastening member that
extends in an axial direction through the first hole and that the
bushing member extends at least partly around and along the
fastening member.
8. Gas turbine engine component according to claim 1, wherein a
second insertion member is arranged in the second hole, wherein the
relative dimensions of the second insertion member and the second
hole are such as to provide a tight radial fit for the second
insertion member in the second hole, and wherein the second
insertion member is fixed in relation to both the first and the
second bracket member.
9. Gas turbine engine component according to claim 1, wherein the
second fastening device is configured to press the first and second
bracket members towards each other from opposite sides of the ring
element when tightened, wherein the component is arranged in such a
way that each of the first and second bracket members exerts a
pressure directly or indirectly onto its corresponding side of the
ring element when the second fastening device is tightened.
10. Gas turbine engine component according to claim 8, wherein the
second fastening device is configured to press the first and second
bracket members towards each other from opposite sides of the ring
element when tightened, wherein the component is arranged in such a
way that each of the first and second bracket members exerts a
pressure directly or indirectly onto its corresponding side of the
ring element when the second fastening device is tightened, and the
component is arranged in such a way that each of the first and
second bracket members exerts a pressure directly or indirectly
onto opposite sides of the second insertion member, as seen in an
axial direction of the second hole, when the second fastening
device is tightened.
11. Gas turbine engine component according to claim 8, wherein the
second insertion member extends in the second hole along an axial
direction thereof.
12. Gas turbine engine component according to claim 8, wherein the
second insertion member is a bushing member.
13. Gas turbine engine component according to claim 12, wherein the
second fastening device comprises a second fastening member that
extends in an axial direction through the second hole and that the
second bushing member extends at least partly around and along the
fastening member.
14. Gas turbine engine component according to claim 8, wherein the
second insertion member forms an integrated part of the first
bracket member.
15. Gas turbine engine component according to claim 1, wherein the
first bracket member has a third hole and a fourth hole and is
arranged such that the third and fourth holes coincide with the
first and second holes, respectively.
16. Gas turbine engine component according to claim 15, wherein the
third hole is arranged in a first part of the first bracket member,
which first part extends in a plane that is substantially in
parallel with a radial direction of the ring element, and that the
fourth hole is arranged in a second part of the first bracket
member, which second part extends in a plane that is substantially
in parallel with a circumferential direction of the ring
element.
17. Gas turbine engine component according to claim 1, wherein the
second, angled bracket member is provided with a fifth hole and a
sixth hole, wherein the fifth hole coincides with the first hole
and the sixth hole coincides with the second hole.
18. Gas turbine engine component according to claim 17, wherein the
fifth hole is arranged in a radially directed part of the second,
angled bracket member, which radial part extends in a plane that is
substantially in parallel with a radial direction of the ring
element, and that the sixth hole is arranged in a circumferentially
directed part of the second, angled bracket member, which
circumferentially part extends in a plane that is substantially in
parallel with a circumferential direction of the ring element.
19. Gas turbine engine component according to claim 1, wherein the
first and second bracket members are made of a metallic
material.
20. Gas turbine engine component according to claim 2, wherein the
first insertion member is made of a metallic material.
21. Gas turbine engine component according to claim 8, wherein the
second insertion member is made of a metallic material.
22. Gas turbine engine component according to claim 2, wherein the
tight radial fit corresponds to a radial play of <0.1 mm.
23. Gas turbine engine component according to claim 1, wherein the
component comprises an inner ring element and an outer ring element
connected by the plurality of circumferentially spaced load
carrying vanes.
24. Gas turbine engine component according to claim 1, wherein the
component is configured to define a gas flow in a gas turbine
engine, such as a turbo-jet engine.
25. Gas turbine engine component according to claim 1, wherein the
component comprises a further set of bracket members, fastening
devices, holes and opening according to claim 1 for fastening the
end part of the at least one composite vane to the ring element,
wherein the further set is positioned at a distance from the set
according to claim 1 as seen in an axial direction of the ring
element.
26. Gas turbine engine component according to claim 24, wherein a
further bracket member (51) of the further set, which further
bracket member corresponds to the first bracket member, is arranged
on an opposite side of the composite vane in relation to the first
bracket member.
27. Gas turbine engine, wherein it comprises a component according
to claim 1.
Description
BACKGROUND AND SUMMARY
[0001] This invention relates to a gas turbine engine component. In
particular, the invention relates to fastening of load carrying
composite vanes to a ring element. The invention also relates to a
gas turbine engine comprising such a component.
[0002] Turbojet engines often comprise a fan part with a gas/air
channel defined by an outer ring (outer casing) and an inner ring
(inner mine) connected by a plurality of air-guiding vanes and
structural, load-carrying vanes that extend in a radial direction
between the two rings. An engine mount is usually also provided by
means of which the engine can be suspended in a frame, such as a
wing of an aircraft. The engine mount is commonly attached to the
above-mentioned outer ring. A structure of the type described above
will be subjected to large mechanical forces upon operation of the
engine and must be designed to withstand such conditions.
[0003] Conventionally, the vanes and the ring elements have been
made of metal and fastening of the vanes to the ring elements has
been achieved by means of bolt or rivet friction joints. However,
for the purpose of saving weight there is an increasing interest of
making use of vanes and ring elements made of a composite material
such as a fibre-reinforced polymer.
[0004] Fastening of composite components by bolts is generally more
complex than fastening of metal components. One reason is that
composite materials have a tendency to relax mechanically during
its lifetime, which results in that an initially applied clamping
friction force is likely to decrease with time. Another reason is
that a fibre-reinforced composite material usually exhibits
different mechanical properties in different directions, which
requires certain considerations regarding the transmission of
forces through the fastening arrangement. Conventional bolted
friction joints are therefore normally not suitable for fastening
e.g. a load-carrying composite vane to a ring element.
[0005] WO 2008/121047 discloses an arrangement for fastening a load
carrying composite vane to a ring element using a ring element
stiffening structure and an angled bracket member, wherein
particular attention is paid to the subject of direction of
forces.
[0006] There is still a need for improvements in this field, for
instance regarding the problem related to the tendency of composite
materials to relax mechanically during its lifetime.
[0007] It is desirable to provide a gas turbine engine component
and gas turbine engine that exhibit improved properties concerning
fastening of composite load-carrying vanes to a ring element
compared to conventional gas turbine engines and components.
[0008] The invention concerns, according to an aspect thereof, a
gas turbine engine component comprising a ring element and a
plurality of circumferentially spaced load carrying vanes extending
in a radial direction of the ring element, wherein at least one of
said vanes is made of a composite material and wherein an end part
of the at least one composite vane is fastened to the ring element
by means of at least a first bracket member arranged in a corner
region formed by the composite vane and the ring element, wherein
the first bracket member is fastened to the composite vane by means
of a first fastening device arranged in association with a first
hole extending through the composite vane, and wherein the first
bracket member is fastened to the ring element by means of a second
fastening device arranged in association with a second hole
extending through the ring element.
[0009] The invention, according to an aspect thereof, is
characterized in that an opening is arranged in the ring element
and that the component comprises a second bracket member that at
least partly has an angular cross section, wherein the second,
angled bracket member is arranged through said opening such as to
be positioned on an opposite side of both the composite vane and
the ring element in relation to the first bracket member, and
wherein the second, angled bracket member is fastened to the first
bracket member by means of said first and second fastening
devices.
[0010] Thus, the inventive component according to an aspect of the
present invention comprises a double-bracket arrangement where a
conventional first, inner-corner bracket member, via first and
second through holes, is connected to a second, angled outer-corner
bracket member that extends through the first opening in the ring
element. Such a double bracket arrangement for fastening the vane
to the ring element provides for a rigid structure and makes it
possible to transmit a load from the vane to the ring element by
bearing stress which is advantageous for composite material.
Further, by using metallic material in the bracket members and
fastening devices it provides a possibility to clamp metal to metal
when fastening the brackets, for instance by including a metallic
bushing in the first and second holes. Thereby, the creeping
problem of clamped composite material can be avoided, even in case
also the ring element is made of a composite material.
[0011] An additional advantage of the inventive design according to
an aspect of the present invention is, in case the ring element is
an outer ring element that e.g. forms part of an outer casing, that
the second bracket member provides an attachment point on the outer
side of ring element for other devices, such as oil tanks. To
provide such attachment points is normally a problem for composite
ring elements.
[0012] In an advantageous embodiment of the invention a first
insertion member is arranged in the first hole, wherein the
relative dimensions of the first insertion member and the first
hole are such as to provide a tight radial fit for the first
insertion member in the first hole, and wherein the first insertion
member is fixed in relation to both the first and the second
bracket member.
[0013] Such a design provides for a tight fit between the vane and
the bracket members and prevents sliding of one part in relation to
the other. A load can thereby be transmitted from the vane to the
bracket members by bearing stress. This is an advantage for a
composite vane since no clamping force is needed for the purpose of
establishing a rigid load path.
[0014] In a further embodiment of the invention is the first
fastening device configured to press the first and second bracket
members towards each other from opposite sides of the composite
vane when tightened, wherein the component is arranged in such a
way that each of the first and second bracket members exerts a
pressure directly or indirectly onto its corresponding side of the
composite vane when the first fastening device is tightened.
[0015] That the bracket members exert a pressure/force onto
opposite sides of vane has the effect that they become fixed to the
vane as seen in axial direction of the first hole. In practice this
normally means that the composite vane becomes at least slightly
compressed, which enhances the bearing strength. It also means that
any insertion member does not prevent this fixation, e.g. by
bearing against the two bracket members and preventing them from
exerting a pressure onto the sides of the vane
[0016] In a further embodiment of the invention the component is
arranged in such a way that each of the first and second bracket
members exerts a pressure directly or indirectly onto opposite
sides of the first insertion member, as seen in an axial direction
of the first, hole, when the first fastening device is
tightened.
[0017] Thus, the insertion member has a position, shape and axial
length that allow the insertion member to bear directly or
indirectly against the first and second bracket members when the
first fastening device is tightened, but that at the same time
still allow the bracket members to exert a pressure/force onto
opposite sides of vane as explained above. Thus, the insertion
member is exposed to a clamping force between the bracket members,
which preferably results in a slight axial compression and radial
expansion of the insertion member. This has in turn the effect that
the already tight fitting of the insertion member in the first hole
becomes even tighter.
[0018] A further effect is that the first insertion member forms a
bridge between the first and second bracket members through the
composite material in the vane. By using brackets, insertion member
etc. made of metallic material it is possible to clamp metal to
metal when fastening the brackets to the vane. This way creeping
problem of clamped composite material (vane) is avoided.
[0019] In a further embodiment of the invention the first insertion
member extends in the first hole along an axial direction thereof.
Preferably, the first insertion member is a bushing member.
Preferably, the first fastening device comprises a first fastening
member that extends in an axial direction through the first hole
and that the bushing member extends at least partly around and
along the fastening member. The fastening member is preferably a
bolt or a rivet or another type of elongated fastening member.
[0020] In a further embodiment of the invention a second insertion
member is arranged in the second hole, wherein the relative
dimensions of the second insertion member and the second hole are
such as to provide a tight radial fit for the second insertion
member in the second hole, and wherein the second insertion member
is fixed in relation to both the first and the second bracket
member.
[0021] In similarity with what is described above in relation to
the vane, this provides a tight fit with no sliding and allows a
load to be transmitted between the bracket members and the ring
element by bearing stress. No application of clamping force on the
ring element is thereby required for the purpose of establishing a
rigid load path. Thus, this design allows also the ring element to
be made of composite material or at least to comprise composite
material in an area where the vane is fastened.
[0022] In a further embodiment of the invention the second
fastening device is configured to press the first and second
bracket members towards each other from opposite sides of the ring
element when tightened, wherein the component is arranged in such a
way that each of the first and second bracket members exerts a
pressure directly or indirectly onto its corresponding side of the
ring element when the second fastening device is tightened.
[0023] The advantageous effects of these features with regard to a
composite ring element are similar to what is described above with
regard to the composite vane.
[0024] In a further embodiment of the invention the component is
arranged in such a way that each of the first and second bracket
members exerts a pressure directly or indirectly onto opposite
sides of the second insertion member, as seen in an axial direction
of the second hole, when the second fastening device is
tightened.
[0025] Again, the advantageous effects of these features with
regard to a composite ring element are similar to what is described
above with regard to the composite vane.
[0026] In a further embodiment of the invention the second
insertion member extends in the second hole along an axial
direction thereof. Preferably, the second insertion member is a
bushing member. Preferably, the second fastening device comprises a
second fastening member that extends in an axial direction through
the second hole and that the bushing member extends at least partly
around and along the fastening member.
[0027] In a further embodiment of the invention the second
insertion member forms an integrated part of the first bracket
member.
[0028] In a further embodiment of the invention the first bracket
member has a third hole and a fourth hole and is arranged such that
the third and fourth holes coincide with said first and second
holes, respectively.
[0029] In a further embodiment of the invention the third hole is
arranged in a first part of the first bracket member, which first
part extends in a plane that is substantially in parallel with a
radial direction of the ring element, and that the fourth hole is
arranged in a second part of the first bracket member, which second
part extends in a plane that is substantially in parallel with a
circumferential direction of the ring element.
[0030] In a further embodiment of the invention the second, angled
bracket member is provided with a fifth hole and a sixth hole,
wherein the fifth hole coincides with the first hole and the sixth
hole coincides with the second hole.
[0031] In a further embodiment of the invention the fifth hole is
arranged in a radially directed part of the second, angled bracket
member, which radial part extends in a plane that is substantially
in parallel with a radial direction of the ring element, and that
the sixth hole is arranged in a circumferentially directed part of
the second, angled bracket member, which circumferentially part
extends in a plane that is substantially in parallel with a
circumferential direction of the ring element.
[0032] In a further embodiment of the invention the first and
second bracket members are made of a metallic material.
[0033] In a further embodiment of the invention the first insertion
member is made of a metallic material.
[0034] In a further embodiment of the invention the second
insertion member is made of a metallic material.
[0035] In a further embodiment of the invention the tight radial
fit corresponds to a radial play of <0.1 mm.
[0036] In a further embodiment of the invention the component
comprises an inner ring element and an outer ring element connected
by said plurality of circumferentially spaced load carrying
vanes.
[0037] In a further embodiment of the invention the component is
configured to define a gas flow in a gas turbine engine, such as a
turbo jet engine.
[0038] In a further embodiment of the invention the component
comprises a further set of bracket members, fastening devices,
holes and opening for fastening the end part of the at least one
composite vane to the ring element, wherein said further set is
positioned at a distance from the set as seen in an axial direction
of the ring element.
[0039] In a further embodiment of the invention a further bracket
member of said further set, which further bracket member
corresponds to the first bracket member, is arranged on an opposite
side of the composite vane in relation to the first bracket
member.
[0040] The invention also concerns a gas turbine engine comprising
a component of the above type.
BRIEF DESCRIPTION OF DRAWINGS
[0041] In the description of the invention given below reference is
made to the following figure, in which:
[0042] FIG. 1 shows, in a schematic view, a turbo-jet engine
provided with a component according to the invention,
[0043] FIG. 2 shows, in a perspective view, an embodiment of the
inventive component,
[0044] FIGS. 3-6 show an enlarged view of a fastening arrangement
that forms part of the component shown in FIG. 2.
DETAILED DESCRIPTION
[0045] FIG. 1 shows a turbojet engine. The turbojet engine
comprises a central body 1, an annular outer casing 2 (fan casing),
an annular inner casing 3 (engine casing), a fan or blower 4, a low
pressure compressor 5, a high pressure compressor 6, a combustion
chamber 7, a high pressure turbine 8 and a low pressure turbine 9.
It further comprises a set of arms 10 extending in a radial
direction from the inner casing 3 to an outer ring element 14
forming part of the outer casing 2. The arms 10 comprise
aerodynamic vanes 11 primarily provided to act as guide vanes for
air passing through the annular channel between the inner casing 3
and the outer casing 2 in an axial direction, i.e. a longitudinal
direction, of the engine. The arms 10 further comprise structural
arms or load carrying vanes 12 primarily provided to guarantee a
certain mechanical strength of the construction. Here, the
aerodynamic vanes 11 and the load carrying vanes 12 are arranged in
axially separated sets of arms. However, they could as well be
arranged in an interleaving relation in one and the same set of
arms. Further, a single arm may have both an aerodynamic function
and a load carrying function.
[0046] The flow through the turbojet engine is divided into two
major streams, a first one of which passes through an annular
channel between the central body 1 and the inner casing 3, and
passes the compressors 5, 6, the combustion chamber 7 and the
turbines 8, 9. A second stream passes through the annular channel
between the inner casing 3 and the outer casing 2. A temperature of
the second stream is in operation lower than a temperature of the
first stream, but the second stream substantially increases the
thrust of the turbojet engine. An engine mount (not shown) is
arranged onto the outer ring element 14 by means of which the
turbojet engine is attached to and held in position in relation to
an aircraft.
[0047] FIGS. 2-6 show an embodiment of a gas turbine engine
component 15 according to the invention. As shown in FIG. 2, the
component 15 comprises an outer ring element 14 that forms part of
the outer casing 2, an inner ring element 27 that forms part of the
inner casing 3, and a plurality of circumferentially spaced load
carrying vanes 12 that extend in a radial direction of the outer
and inner ring elements 14, 27 and that connects the two ring
elements 14, 27. The outer ring 14 comprises a wall structure in
the form of a sheet with main surfaces facing in a radial
direction.
[0048] In the embodiment shown the extension direction of the load
carrying vanes 12 coincides with a radial direction of the
component 15. However, according to an alternative, the load
carrying vanes may be arranged with an inclination (preferably
<30.degree. in relation to the radial direction of the
component.
[0049] The load carrying vanes 12 are made of a fibre-reinforced
light weight polymer material, i.e. a composite material, with a
density below that of, for example, light weight metals such as
aluminum and titanium. Vanes of this type are, as such, well known
to a person skilled in the art. Further, the load carrying vanes 12
have an aerodynamically adapted cross-section, with a leading
upstream edge and a trailing downstream edge as seen in the axial
direction, i.e. the flow direction through the channel between the
outer ring 14 and the inner casing 3. It is not necessary for the
invention that all vanes are made of a composite material; some
vanes may be made of metal. Neither is it necessary that the load
carrying vanes 12 have an aerodynamically adapted
cross-section.
[0050] Also the outer ring element 14 is in this embodiment made of
a composite material, i.e. a material made of a fibre-reinforced
light weight polymer material.
[0051] FIGS. 3-6 show, in an enlarged view of a part of the
component shown in FIG. 2, a fastening arrangement configured to
fasten the composite vane 12 to the outer ring element 14. The
fastening arrangement comprises two separate double-bracket
arrangements 30, 50 that are positioned at a distance from each
other as seen in an axial direction of the ring element 14, wherein
one is nearer and the other farther in the figures (see FIG. 3).
The two bracket arrangements 30, 50 are similar in structure but
are facing in different directions. FIG. 3 shows a perspective view
of the fastening arrangement, FIG. 4 shows a perspective view with
the ring element 14 made transparent, FIG. 5 is similar to FIG. 4
but with the farther bracket arrangement 50 shown in an exploded
view; and FIG. 6 shows a sectional view of the nearer bracket
arrangement 30. That the two bracket arrangements 30, 50 are
arranged in different directions is clearly shown in e.g. FIG. 4.
Since the structures of the two bracket arrangements 30, 50 are
similar some details of the bracket arrangements 30, 50 are shown
more clearly for the first bracket arrangement 30, whereas some
details are shown more clearly for the second bracket arrangement
50. In general, the description below refers to a single bracket
arrangement but with figure references to both bracket arrangements
30, 50.
[0052] As shown in FIGS. 3-6, each bracket arrangement 30, 50
comprises a first bracket member 31, 51 arranged in a corner region
formed by the composite vane 12 and the ring element 14. Such a
corner region is formed on both sides of the vane 12 when arranged
with an end part thereof in the vicinity of the ring element 14. In
this example the first bracket member 31, 51 is angled and has a
first part that extends in a plane that is substantially in
parallel with a radial direction of the ring element 14 and a
second part that extends in a plane that is substantially in
parallel with a circumferential direction of the ring element 14
(see FIG. 6).
[0053] The first bracket member 31, 51 is fastened to the composite
vane 12 by means of a first fastening device 33, 53 arranged in
association with a first hole 16, 17 (see FIGS. 5 and 6) extending
through the composite vane 12. The first fastening device 33, 53 is
a clamping device and comprises a first bolt member 41, 61 and a
first screw member 42, 62. Further, the first bracket member 31, 51
is fastened to the ring element 14 by means of a second fastening
device 34, 54 arranged in association with a second hole 18, 19
(see FIGS. 5 and 6) that extends through the ring element 14. Also
the second fastening device 34, 54 is a clamping device and
comprises a second bolt member 43, 63 and a second screw member 44,
64.
[0054] The first bracket member 31, 51 is provided with a third
hole 46, 66 extending through the first part thereof and a fourth
hole 47, 67 extending through the second part thereof. The first
bracket member 31, 51 is arranged such that the third and fourth
holes 46, 66, 47, 67 coincide with said first and second holes
16-19, respectively.
[0055] The component 15, and also the fastening arrangement and
each of the bracket arrangements 30, 50, further comprises a second
bracket member 32, 52 that at least in a portion thereof has an
angular cross section. This second, angular bracket member 32, 52
is arranged through an opening 40, 60 arranged through the ring
element 14 such as to be positioned on an opposite side of both the
composite vane 12 and the ring element 14 in relation to the first
bracket member 31, 51. Further, the second, angled bracket member
32, 52 is fastened to the first bracket member 31, 51 by means of
said first and second fastening devices 33, 53, 34, 54.
[0056] The second, angled bracket member 32, 52 has a radially
directed part that extends in a plane that is substantially in
parallel with a radial direction of the ring element 14 and a
circumferentially directed part that extends in a plane that is
substantially in parallel with a circumferential direction of the
ring element 14. The radial part is the part inserted through the
opening 40, 60, which opening 40, 60 is arranged to provide a
clearance for the radial part so that positioning of the second,
angled bracket member 32, 52 becomes easy.
[0057] The second bracket member 32, 52 is provided with a fifth
hole 48, 68 extending through the radial part thereof and a sixth
hole 49, 69 extending through the circumferential part thereof. The
second bracket member 32, 52 is arranged such that the fifth and
sixth holes 48, 68, 49, 69 coincide with said first and second
holes 16-19, respectively.
[0058] All bracket members 31, 51, 32, 52 and fastening devices 33,
53, 34, 54 are made of metallic material.
[0059] The first bolt member 41, 61 extends through the third hole
46, 66, the first hole 16, 17 (in the vane 12) and the fifth hole
48, 68. The first screw member 42, 62 is screwed onto the first
bolt member 41, 61 as to tighten and clamp the first and second
bracket member 31, 51, 32, 52 together around the vane 12 and to
lock the first fastening device 33, 53. Similarly, the second bolt
member 43, 63 extends through the sixth hole 49, 69, the second
hole 18, 19 (in the ring element 14) and the fourth hole 47, 67.
The second screw member 44, 64 is screwed onto the second bolt
member 43, 63 as to tighten and clamp the first and second bracket
member 31, 51, 32, 52 together around the ring element 14 and to
lock the second fastening device 34, 54.
[0060] Thus, each of the first and second fastening devices is
configured to press the first and second bracket members towards
each other from opposite sides of the composite vane 12 and the
ring element 14, respectively, when tightened. Further, the
component 15 is arranged in such a way that each of the first and
second bracket members exerts a pressure directly or indirectly
onto its corresponding side of the composite vane 12 and the ring
element 14, respectively, when the first and second fastening
device, respectively, is tightened. In practice this means that the
vane 12 and the ring element 14 will be at least slightly
compressed when the first and second fastening devices 33, 53, 34,
54 are tightened.
[0061] A first insertion member in the form of a first tubular
bushing member 35, 55 made of a metallic material is arranged in
the first hole 16, 17 as to extend along an axial direction of the
first hole 16, 17. The relative dimensions of the first bushing
member 35, 55 and the first hole 16, 17 are such as to provide a
tight radial fit for the first insertion member 35, 55 in the first
hole 16, 17. The first bushing member 35, 55, which in this example
is a separate part, extends in an axial direction through the third
hole 46, 66 and has a flange positioned on an outer side of the
first bracket member 31, 51. The first bushing member 35, 55
extends around and partly along the first bolt member 41, 61. When
the first fastening device 33, 53 is tightened the first bushing
member 35, 55 becomes fixed in relation to both the first and the
second bracket member 31, 51, 32, 52.
[0062] The relative dimensions of the first bushing member 35, 55
and the third hole 46, 66 are such as to provide a fit that can
take up tolerances. The magnitude of the tolerances to take up
depends e.g. on the tolerances of the first bracket member 31, 51.
With close tolerances of the first bracket member 31, 51 (around
.+-.0.05 mm) a suitable radial play between the first bushing
member 35, 55 and the third hole 46, 66 is around 0.2 mm. The
smaller the radial play, the more rigid the structure. A larger
radial play between the first bushing member 35, 55 and the third
hole 46, 66 may be used to reduce or eliminate fitting problems
during assemblage.
[0063] The position of the first bushing member 35, 55 in the axial
direction is such that, before tightening of the first fastening
device 33, 53, it will not extend through the entire length of the
first hole 16, 17 but instead end a small distance from the surface
of the side of the vane 12 where the second bracket member 32, 52
is (to be) positioned. That is, a small annular gap is created
between the first bushing member 35, 55 and the second bracket
member 32, 52 when the first bushing member 35, 55 and the second
bracket member 32, 52 are placed in position but before tightening
of the first fastening device 33, 53.
[0064] When the first fastening device 33, 53 is tightened the vane
12 will compress so that the small annular gap disappears. At this
point the first bushing member 35, 55 bears against the second
bracket member 32, 52 at one end and against a head of the first
bolt member 41, 61 at its other, flanged end. By tightening the
first fastening device 33, 53 further, preferably a predetermined
further tightening verified by a torque indicator, the first
bushing member 35, 55 becomes clamped between the second bracket
member 32, 52 and the head of the first bolt member 41, 61. This
results in a slight compression and radial expansion of the first
bushing member 35, 55 which is useful for reducing or eliminating
any radial play between the first bushing member 35, 55 and the
first hole 16, 17. Another result of this is that the first bushing
member 35, 55 forms a metallic bridge between the first and second
(metallic) bracket members 31, 51, 32, 52 through the composite
vane 12. This is useful since metal can be clamped to metal when
fastening the bracket members 31, 51, 32, 52 to the composite vane
12, which means that the creeping problem associated with clamped
composite material is avoided.
[0065] Accordingly, the component 15 is arranged in such a way that
each of the first and second bracket members 31, 51, 32, 52 exerts
a pressure directly or indirectly onto opposite sides of the first
insertion member 35, 55, as seen in an axial direction of the first
hole 16, 17, when the first fastening device 33, 53 is
tightened.
[0066] If the first bushing member 35, 55 has an end part
positioned too close to the second bracket member 32, 52 before
tightening of the first fastening device 33, 53, for instance
because it is too long in its axial direction, it is likely that
the first bushing member 35, 55 will interfere when the first and
second bracket member 31, 51, 32, 52 are to be pressed together
around the vane 12 during tightening of the first fastening device
33, 53. As a result of this, the first and second bracket members
31, 51, 32, 52 will not be properly fixed to the vane 12 in the
axial direction of the first hole 16, 17.
[0067] If the first bushing member 35, 55 has an end part
positioned too far away from the second bracket member 32, 52
before tightening of the first fastening device 33, 53, for
instance because it is too short in its axial direction, it may be
that the first bushing member 35, 55 will not be compressed and not
form any metallic bridge as described above. In some occasions this
may anyway be acceptable because the load can still be transmitted
between the vane 12 and the bracket members 31, 51, 32, 52 by means
of bearing stress due to the tight fit between the first bushing
member 35, 55 and the first hole 16, 17.
[0068] The optimum axial position of the first bushing member 35,
55 that provides an optimum size of the annular gap, i.e. the
position of the first bushing member 35, 55 that provides both a
proper axial fixation and a proper metallic bridge, depends on a
number of factors, such as the dimensions of the vane, the bracket
members, the holes etc, as well as which materials that are used.
An optimum position can be achieved by using close tolerances of
the parts involved. It is also possible to adjust the axial
position of the first bushing member 35, 55 before tightening of
the first fastening device 33, 53, for instance by using shims
placed under the flange of the first bushing member 35, 55.
[0069] A second insertion member in the form of a second tubular
bushing member 36, 56 is arranged in the second hole 18, 19 as to
extend along an axial direction of the first hole 18, 19. The
second bushing member 36, 56 has in principal the same function
with regard to the ring element 14 as the first bushing member 35,
55 with regard to the vane 12.
[0070] The second bushing member 36, 56 forms an integrated,
metallic part of the first bracket member 31, 51. The relative
dimensions of the second bushing member 36, 56 and the second hole
18, 19 are such as to provide a tight radial fit in the second hole
18, 19. The second bushing member 36, 56 protrudes from the first
bracket member 31, 51 as to form an elongation of the fourth hole
47, 67. The second bushing member 36, 56 extends around and partly
along the second bolt member 43, 63. When the second fastening
device 34, 54 is tightened the second bushing member 36, 56 becomes
fixed in relation to both the first and the second bracket member
31, 51, 32, 52.
[0071] The length of the second bushing member 36, 56 in the axial
direction is such that, before tightening of the second fastening
device 34, 54, it will not extend through the entire length of the
second hole 18, 19 but instead end a small distance from an outer
surface of the ring element 14 where the second bracket member 32,
52 is (to be) positioned. That is, a small annular gap is created
between the second bushing member 36, 56 and the second bracket
member 32, 52 when the first bracket member 31, 51 (including the
integrated second bushing member 36, 56) and the second bracket
member 32, 52 are placed in position but before tightening of the
second fastening device 34, 54.
[0072] When the second fastening device 34, 54 is tightened the
composite ring element 14 will compress so that the small annular
gap disappears. At this point the second bushing member 36, 56
bears against the second bracket member 32, 52. By tightening the
second fastening device 34, 54 further, preferably a predetermined
further tightening verified by a torque indicator, the second
bushing member 36, 56 becomes clamped between the first an second
bracket members 31, 51, 32, 52. This results in a slight
compression and radial expansion of the second bushing member 36,
56 which is useful for reducing or eliminating any radial play
between the second bushing member 36, 56 and the second hole 18,
19. Another result of this is that the second bushing member 36, 56
forms a metallic bridge between the first and second (metallic)
bracket members 31, 51, 32, 52 through the composite ring element
14. This is useful since metal can be clamped to metal when
fastening the bracket members 31, 51, 32, 52 to the composite ring
element 14, which means that the creeping problem associated with
clamped composite material is avoided.
[0073] Accordingly, the component 15 is arranged in such a way that
each of the first and second bracket members 31, 51, 32, 52 exerts
a pressure directly or indirectly onto opposite sides of the second
insertion member 36, 56, as seen in an axial direction of the
second hole 18, 19, when the second fastening device 34, 54 is
tightened.
[0074] If the second bushing member 36, 56 has an end part
positioned too close to the second bracket member 32, 52 before
tightening of the second fastening device 34, 54, for instance
because it is too long in its axial direction, it is likely that
the second bushing member 36, 56 will interfere when the first and
second bracket member 31, 51, 32, 52 are to be pressed together
around the ring element 14 during tightening of the second
fastening device 34, 54. As a result of this, the first and second
bracket members 31, 51, 32, 52 will not be properly fixed to the
ring element 14 in the axial direction of the second hole If the
second bushing member 36, 56 has an end part positioned too far
away from the second bracket member 32, 52 before tightening of the
second fastening device 34, 54, for instance because it is too
short in its axial direction, it may be that the second bushing
member 36, 56 will not be compressed and not form any metallic
bridge as described above. In some occasions this may anyway be
acceptable because the load can still be transmitted between the
ring element 14 and the bracket members 31, 51, 32, 52 by means of
bearing stress due to the tight fit between the second bushing
member 36, 56 and the second hole 18, 19.
[0075] The optimum axial position of the second bushing member 36,
56 that provides an optimum size of the annular gap, i.e. the
position of the second bushing member 36, 56 that provides both a
proper axial fixation and a proper metallic bridge, depends on a
number of factors, such as the dimensions of the ring element, the
bracket members, the holes etc, as well as which materials that are
used. An optimum position can be achieved by using close tolerances
of the parts involved. It is also possible to adjust the position
of the circumferential part of the second bracket member 32, 52
before tightening of the second fastening device 34, 54, for
instance by using shims placed between the second bracket member
32, 52 and the second bushing member 36, 56.
[0076] That the fit is tight means in principle that the diameter
of the hole is as small as possible without making it (too)
difficult to insert the corresponding insertion member, i.e. in
this case the corresponding bushing member. A small radial play
will normally be present in a tight fit. A typical tight fit radial
play is in this application <0.1 mm, typically within the
interval 0.015-0.1 mm. The radial play may be further reduced by
cooling/shrinking the insertion member before insertion.
[0077] The tight fittings provide in this case a fixed position of
the vane 12 in relation to the bracket members 31, 51, 32, 52 and
further to the ring element 14. This provides for a rigid load path
between the vane 12 and the ring element 14. Since the parts that
are clamped together are made of metallic material there is no
problem related to the tendency of composite materials to relax
mechanically during its lifetime.
[0078] The outer ring 14 may comprise metallic material in addition
to the fibre-reinforced composite light weight material. The outer
ring 14 may, as in the shown embodiment, be of annular shape and
may have a length in the longitudinal, i.e. axial direction of the
engine corresponding to the extension of each of the arms 12 in
said axial direction. The ring 14 may further be configured for
transferring axial loads between upstream and downstream gas
turbine components.
[0079] The invention has above been described for a static
application in a gas turbine engine. However, the invention may
also be applied in a rotational component, such as a fan and
wherein there are provided aerodynamic guide vanes for the guiding
of gases in a by pass channel of the engine. The invention may be
used for any assembled/fabricated metal/composite structure.
[0080] In a broad sense, the invention relates to all kinds of
structures in turbojet engines wherein there is a plurality of
arms, typically vanes or load carrying vanes, connected to a ring
element. For example, such structural vanes may be arranged in an
engine core gas channel, but also in a fan section of an engine
type where the fan section is arranged in a common gas channel
upstream of a division into a core gas channel and a bypass gas
channel.
[0081] The term "ring element", as referred to herein, may comprise
only a part, i.e. a sector, of a ring, or a continuous full ring.
Further, the ring element may form part of a housing, casing, or
other similar component.
[0082] The first hole 16, 17 extends through the composite vane 12
from a suction side to a pressure side thereof. The second hole 18,
19 extends through the ring element 14 from an outer side to an
inner side thereof.
[0083] The invention is not limited by the embodiments described
above but can be modified in various ways within the scope of the
claims. For instance, either of the first and second insertion
members 35, 55, 36, 56 can be an integrated part of one of the
bracket members. Further, both insertion members can be separate
parts. In principle both bushings can form integrated parts of any
of the bracket members, but this likely leads to fitting problems
during assemblage of the component.
[0084] Moreover, the first bracket member 31, 51 does not
necessarily have to be angled; it can e.g. have a rectangular cross
section. The second, angled bracket member 32, 52 can have a number
of different shapes; it can e.g. extend in an axial and/or
circumferential direction of the ring element 14 and provide
attachment points for auxiliary equipment that is to be mounted to
the ring element 14. With regard to the present invention it is
only required that a portion thereof is angled and adapted to be
inserted through the opening in the ring element for attachment to
the first bracket member 31, 51.
[0085] In the embodiment described the inventive fastening
arrangement has been used to fasten load carrying vanes 12 to the
outer ring element 14 of the gas turbine component 5. However, the
invention is applicable also for fastening the load carrying vanes
12 to the inner ring element 27, i.e. it can be used on the inner
and/or the outer ring element.
[0086] It is not required that the component 15 comprises two
double-bracket arrangements 30, 50. If more than one point of
attachment is needed for fastening the vane 12 to the ring element
14 a single inventive double-bracket arrangement can be
complemented with a further inventive double-bracket arrangement or
with another type of attachment point.
* * * * *