Information
-
Patent Grant
-
6520743
-
Patent Number
6,520,743
-
Date Filed
Thursday, July 19, 200123 years ago
-
Date Issued
Tuesday, February 18, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Look; Edward K.
- McAleenan; James M
Agents
-
CPC
-
US Classifications
Field of Search
US
- 416 220 R
- 416 221
- 416 204 A
- 416 244 A
-
International Classifications
-
Abstract
An apparatus for axially retaining rotor blades to an annular radially extending disk having a recess and a flange. An annular retaining ring is disposed in the recess and includes an axially extending lip and an axially outer side forming an annular bevel surface along a radially outer edge. A retaining plate having an axially extending base, a radially extending outward arm and a radially extending inward leg having an annular bevel surface along an axially inner, radially inner edge is affixed to the disk and the leg cooperates with the lip of the ring. Wherein, the bevel surfaces of the retaining plate and retaining ring are arranged outwardly opposite to one another so that the bevel surfaces are radially compressed along each other as the base slidably engages with the recess walls.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for retaining an annular plate against the radial surface of a disk for retaining rotor blades.
2. Description of the Prior Art
Boltless rotor blade retainers have been developed to reduce problems related to localized stress concentration in a rotor disk rim and blade retainers, reduce installation time and complications, and weight. Furthermore, they require additional tools.
One type of design is known in French Patent 2,485,117. It employs an annular retaining plate that is retained against a radial disk surface. The disk includes an annular recess formed along the radial surface that is bounded by several walls of which one is constituted by one side of a radially outwardly extending flange. The plate includes an axially extending base that is adapted to slidably engage with a radially outer wall of the recess. The plate also includes a leg extending radially inward to engage with the recess. The apparatus further includes an annular retaining ring that is disposed in the recess of the disk and is shaped to receive a portion of the leg which is also disposed within the recess to secure the blade retainer to the disk.
In order to install the retaining plate, the split annular retaining ring is inserted into the disk recess and compressed radially inward into the recess using compression tools disposed along the peripheral ring wall. Compression occurs until the tools come to rest against the flange. Next the base and the leg are inserted into the recess until a portion of the arm abuts the side of the disk. An axial force is applied to the retaining plate in order to urge the base and the leg to deflect inwardly, clearing the radially inner wall. A clamping tool is used to accomplish the deflection. At this point, the compression tools that compressed the annular ring are released. The ring then expands radially outward and the axial force applied to the retaining plate is released. Thereupon, the plate leg comes to rest against the two walls bounding the lip of the annular ring.
Accordingly, the use of the plate retaining device of the said French patent 2,485,117 entails special tools including the compression and clamping tools to compress the retaining ring when assembling the plate.
SUMMARY OF THE INVENTION
The objective of the present invention is an apparatus that axially engages the retaining plate and permits simple installation.
Another object of the invention is to enable assembling the retaining plate onto the disk without special tools that compress the retaining ring and deflect the retaining plate.
Still another objective of the invention is an apparatus that axially retains the plate and enhances the disk service life.
The invention attains its objectives in that the plate leg and the retaining ring form annular and mutually facing bevels to compress the ring previously placed in the recess when the base was made to slide axially in the recess as the plate was assembled to the disk.
Preferably the following design steps also shall be observed:
the bevels slant by an angle between 10 and 60° relative to the disk axis,
the lip is bounded by a surface radially resting on the leg end and by a radial surface resting on the leg's side which faces the recess aperture, the radial surface leading to the retaining ring's bevel,
the part of the leg received in the lip is fitted with notches,
the lip comprises protrusions which will be inserted into the leg's notches,
The notch depth is larger than the protrusion height.
The last design step allows slipping a tool into the space subtended between the protrusion peaks and the notch bottoms for the purpose of compressing the retaining ring when the plate is disassembled during maintenance operations. However, no special tool is used when reassembling the plate.
The geometry of the notches and protrusions allows keeping the retaining ring irrotational relative to the plate. This plate is thereby fixed in position relative to the disk at the level of the blade roots. With regard to the French patent 2,485,117, the retaining ring is affixed to the disk at a recess in the flange bounding the recess. Accordingly, such a recess is not required in the present invention and thereby disk construction is simplified and disk service life is extended.
Other features and advantages of the invention are elucidated in the illustrative description below which relates to the attached drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1
is a cross-sectional view of a rotor disk designed in the manner of the present invention,
FIGS. 2
a
-
2
f
are schematic, sequential steps of an installation operation employing the blade retainer structure of the invention,
FIG. 3
is a cross-sectional view of
FIG. 1
in the first plate dismantling stage, and
FIG. 4
is an enlarged cross-sectional view showing the base and leg of the retaining plate and the retaining ring in the recess.
DETAILED DESCRIPTION OF THE INVENTION
The drawings show an annular radially extending, rotor disk
1
of a gas-turbine engine with an axis of rotation
2
. This disk
1
is fitted on its radial side
3
with a recess
10
bounded by a radially outer wall
4
, an axially inner wall
5
, a radially inner wall
6
and the axially outer wall
7
of a radially outwardly extending flange
8
. The upper end
9
of the flange
8
is radially spaced away from the radially outer wall
4
in order to subtend an annular aperture
11
to access the recess
10
. The disk
1
is fitted at its periphery with axial notches receiving omitted blade roots. These blade roots are axially held in place by the outside portion
12
of an annular plate
13
of which the radially inner portion
14
comprises an annular base
15
axially extending into the outside side of the recess
10
and a leg
16
radially extending from the inner end of the annular base
15
into the recess
10
.
The outside diameter of the annular base
15
is substantially equal to the diameter of the radially outer wall
4
of the recess
10
, and the annular base
15
rests for instance in sliding manner against this outside wall
4
. The inside diameter of the leg
16
is larger than the outside diameter of the flange
8
to allow inserting both the annular base
15
and the leg
16
through the annular aperture
11
into the recess
10
. When the radially inside part
14
of the plate
13
is inserted into the cavity
10
, the plate
13
is radially kept in place relative to the disk
1
because the annular base
15
will rest for instance in sliding manner against the radially outer wall
4
.
The plate
13
is axially held in place at the disk
1
by a split annular retaining ring
20
. The retaining ring
20
comprises an axial front wall
21
resting against the inside surface
7
of the flange
8
, further a rear wall
22
configured near the axially inside wall
5
of the recess
10
, an outer peripheral wall
23
leading through a bevel
24
to the front wall
21
and by means of a lip
25
which is bounded by a radial surface
26
and a cylindrical surface
27
to the rear wall
22
, and lastly an axially inside recess wall
6
of a size allowing compressively moving the retaining ring
20
behind the flange
8
when the plate
13
is put in place.
In the assembly position shown in
FIG. 4
, the radial surface
26
bounding the lip
25
is compressed by the side of the leg
16
which is opposite the annular aperture
11
.
The diameter of the cylindrical surface
27
bounding the lip
25
is substantially equal to the inside diameter of the leg
16
in the rest position of the retaining ring
20
. However when the retaining ring
20
is subjected to centrifugal forces during the rotation of the disk
1
, the cylindrical surface
27
presses against the inside end
17
of the leg
16
.
The inside diameter of the leg
16
also is substantially equal to the outside diameter of the front wall
21
of the retaining ring at rest.
Furthermore the inner end
17
of the leg
16
also leads through a bevel
19
to the rear side
18
of the leg
16
configured opposite the axially inner wall
5
of the recess
10
.
This bevel
19
and the bevel
24
of the retaining ring
20
exhibit identical angles relative to the axis of rotation
2
of the disk
1
. The angles are between a range of 10 and 45°.
The axially inside wall
28
of the retaining ring
20
also leads through a second bevel
29
to the rear wall
22
. The bevel
29
allows the retaining ring
20
to expand when it is inserted into the recess
10
.
FIGS. 2
a
through
2
f
show the different assembly stages of the plate
13
onto the disk
1
. The split angular retaining ring
20
is inserted into the recess
10
wherein it assumes its rest position shown in FIG.
2
.
Next the plate
13
is positioned in such a way that the end
17
of the leg
16
is situated in the aperture
11
of the recess
10
. Thereupon, the bevel
19
of the leg
16
rests against the bevel
24
of the retaining ring
20
which thus can be centered relative to the axis of rotation
2
of the disk
1
. Next, an axial force F is applied to the inside portion
14
of the plate
13
. This manoeuver compresses the retaining ring
20
in the manner shown in
FIGS. 2
b
,
2
c
and
2
d
and forces the annular base
15
to slide on the radially outer wall
4
of the recess
10
.
FIG. 2
d
shows that the leg end
17
rests in sliding manner against the outer peripheral wall
23
of the retaining ring. An axial force F is further applied to the inside portion
14
of the plate
13
. The outside portion
12
of the plate
13
comes to rest against the radial side
3
of the disk
1
and against the blades, and the end
17
of the leg
16
moves above the lip
25
(see
FIG. 4
for details of the lip). As a result, the retaining ring
20
is relieved of compression and it resumes its intrinsic diameter. The cylindrical surface
27
of the lip
25
comes to rest against end
17
of the leg
16
and the radial surface
26
moves between the leg
16
and the aperture
11
. When the axial force F applied to the inside portion
14
of the plate
13
is relaxed, the plate compresses the radial surface
26
bounding the lip
25
and the front surface
21
of the retaining ring
20
rests against the inside surface
7
of the flange
8
.
It should be noted that the plate
13
is mounted in axially prestressed manner on the disk
1
.
As described above, the axial displacement of the plate
13
when assembled to the disk
1
entails compressing the retaining ring
20
by means of the bevels
19
and
24
.
On the other hand, to retract the plate
13
, the retaining ring
20
must be compressed beforehand in order that its outer peripheral wall
23
move from beneath the end
17
of the leg
16
.
In order to make this operation easier, the leg
16
is fitted with a plurality of notches
40
of which the bottom is directed away from the axis of rotation
2
by a distance larger than the diameter of the outer peripheral wall
23
of the retaining ring
20
. In this manner the end of a suitable tool
41
can be slipped through the interstice in the manner shown in
FIG. 3
in order to compress the retaining ring
20
.
Advantageously, the retaining ring
20
is fitted with protrusions
42
formed along the leg
25
and corresponding to the notches
40
. The protrusions
42
are inserted into the notches
40
and their outer surfaces are flush with the outer peripheral wall
23
of the retaining ring
20
. The protrusions
42
improve the support to the tools
41
and further retain the retaining ring
20
irrotational relative to the plate
13
. The outside portion
12
of the plate
13
in this instance is fixed in a position relative to the disk
1
using appropriate means, for instance studs
43
, which enter between two blade roots.
The design of notches
40
, protrusions
42
and studs
43
allows rotational affixation of each other to the disk
1
, plate
13
and retaining ring
20
in the absence of a direct device blocking relative rotation between the retaining ring
20
and the disk
1
. This design circumvents the presence of stresses entailed by the splits in the flange
8
of the disk
1
. In this manner the mechanical strength of the disk
1
is preserved and its service life is extended.
Claims
- 1. An apparatus for axially retaining rotor blades carried by an annular disk of a turbine engine, the disk extending radially outward relative to a longitudinal axis of the engine, said disk forming an annular recess defined by radial inner and outer walls radially spaced from one another relative to the engine axis, and axial inner wall and outer walls axially spaced from one another relative to the center of the disk perpendicular to the engine axis, the axial outer wall defined by a side of a radially outwardly extending flange formed by said disk, said apparatus comprising:an annular retaining plate forming an axially extending base generally parallel to the engine axis, an arm extending radially outward from said engine axis from an outer side of said base directed away from the disk center, and a leg extending radially inward towards said engine axis from an inner side of said base directed towards the disk center, said leg having an annular bevel surface along an inner edge directed towards the disk center and the engine axis, said base and said leg disposed in said recess, and said base configured and dimensioned to slidably engage with said radial outer wall of said recess; and an annular retaining ring disposed in said recess and configured and dimensioned to abut the axial outerwall thereof, said retaining ring having an axial outer end with an outer side positioned generally parallel to and axially away from the disk center, and forming an annular bevel surface along a radial outer edge directed away from the disk center and the engine axis, said retaining ring also forming a lip extending generally parallel to the engine axis and bounded by the outer end of the ring, and an axial inner end wedged against said axial inner wall of the disk, said lip configured and dimensioned to receive a radial inner portion of said leg directed towards the engine axis for thereby securing said retaining plate to said disk; wherein said bevel surfaces of said retaining plate and said retaining ring are configured and dimensioned such that said bevel surfaces cooperate to compress the retaining ring in the recess when the bevel surface of the retaining plate slidably presses against the bevel surface of the retaining ring as the base is inserted into the recess.
- 2. The apparatus according to claim 1 wherein the bevel surfaces of said retaining plate and said retaining ring are positioned at an angle in a range between about 10 and 60 degrees relative to the axis of rotation of the disk.
- 3. The apparatus according to claim 1 wherein the lip is defined by an axial surface extending parallel to the engine axis and an intermediate radially extending surface forming an inner side of the outer end of the retaining ring, the radial inner portion of said leg directed towards the engine axis being retained by said axial surface of said lip and said inner side of the outer end of the ring when disposed in said recess.
- 4. The apparatus according to claim 1 wherein said leg forms a plurality of notches the radial inner portion of said leg directed towards the engine axis.
- 5. The apparatus according to claim 4 wherein said lip forms a plurality of protrusions adapted to engage with said plurality of notches of the radial inner portion of said leg.
- 6. The apparatus according to claim 5 wherein the depth of said notches is greater than the width of said protrusions.
Priority Claims (1)
Number |
Date |
Country |
Kind |
00 10503 |
Aug 2000 |
FR |
|
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Oct 1973 |
A |
4192633 |
Herzner |
Mar 1980 |
A |
4304523 |
Corsmeier et al. |
Dec 1981 |
A |
4890981 |
Corsmeier et al. |
Jan 1990 |
A |
5018943 |
Corsmeier et al. |
May 1991 |
A |
5525429 |
Mannava et al. |
Jun 1996 |
A |