U.S. patent application number 09/794050 was filed with the patent office on 2001-09-06 for fastening rotor blades in a turbomachine.
Invention is credited to Knorr, Manfred, Mueller, Michael, Pross, Jorg.
Application Number | 20010019697 09/794050 |
Document ID | / |
Family ID | 8174578 |
Filed Date | 2001-09-06 |
United States Patent
Application |
20010019697 |
Kind Code |
A1 |
Mueller, Michael ; et
al. |
September 6, 2001 |
Fastening rotor blades in a turbomachine
Abstract
The rotor blades of a turbomachine are fastened to the rotor (3)
of the machine by means of blade roots (1) by the blade roots (1)
being anchored in peripheral grooves (2). According to the
invention, the blade roots (1) have at least one recess or opening
(4), which extends in the peripheral direction and in each of which
a connecting piece (5) is arranged. This connecting piece (5)
connects at least two blade roots (1) to form a blade pack. By
means of the connection, the blade roots (1) are secured against
twisting and falling out of the peripheral groove (2). The
connecting piece (5) consists of a shaped piece, which is laid with
little clearance into the recess or opening (4), a displacement of
a blade root (1) and of the connecting piece (5) relative to one
another still being possible. The blade root of the last blade of a
blade row which is assembled in a peripheral groove is locked to
the adjacent blade roots by a final connecting piece.
Inventors: |
Mueller, Michael; (Ulm,
DE) ; Pross, Jorg; (Albbruck, DE) ; Knorr,
Manfred; (Waldshut-Tiengen, DE) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Family ID: |
8174578 |
Appl. No.: |
09/794050 |
Filed: |
February 28, 2001 |
Current U.S.
Class: |
416/218 ;
416/221 |
Current CPC
Class: |
F01D 5/32 20130101; F01D
5/3038 20130101 |
Class at
Publication: |
416/218 ;
416/221 |
International
Class: |
F01D 005/32 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 1, 2000 |
EP |
00 810 175.0 |
Claims
1. A fastening arrangement for rotor blades on the rotor (3) of a
turbomachine, the rotor blades each having a blade root (1) which
is anchored in a peripheral groove (2), characterized in that the
blade roots (1) each have at least one recess (4) or opening, the
recess or opening extending in the peripheral direction, and in
that a connecting piece (5), which is matched to the shape of the
recess (4) or opening, is arranged in each recess or opening, and
in that the connecting piece connects at least two blade roots (1)
to form a blade root pack.
2. The fastening arrangement for rotor blades as claimed in claim
1, characterized in that the blade roots (1) each have two recesses
(4) or openings, in each of which a connecting piece is
arranged.
3. The fastening arrangement for rotor blades as claimed in claim 1
or 2, characterized in that the at least one recess (4) is
respectively arranged on the side of the blade root (1) facing the
bottom of the groove of the peripheral groove (2) and has a
rectangular cross section, and in that the connecting piece (5),
which is laid in each case into the at least one recess (4), is a
shaped piece of the same rectangular cross section.
4. The fastening arrangement for rotor blades as claimed in claim 1
or 2, characterized in that the opening on the blade root (1) is a
bore opening and in that the connecting piece consists of a wire of
the same diameter which is pushed into the bore opening.
5. The fastening arrangement for rotor blades as claimed in one of
claims 1 to 4, characterized in that the connecting pieces (5)
extend over almost the complete periphery of the groove and connect
almost all the blade roots (1) to form one blade pack.
6. The fastening arrangement for rotor blades as claimed in one of
claims 1 to 4, characterized in that the connecting pieces (5)
extend over two or more blade roots (1) and connect the latter to
form a plurality of blade packs.
7. The fastening arrangement for rotor blades as claimed in claim
6, characterized in that each of the blade roots (2) has two
recesses (4) or openings and the connecting pieces (5) each extend
over two blade roots (1) and in that the connecting pieces, which
are arranged parallel to one another, are arranged offset by one
blade root.
8. The fastening arrangement for rotor blades as claimed in one of
claims 1 to 7, characterized in that each of the blade roots (1)
has a round recess (6) in which a contact pressure spring (7) is
arranged.
9. The fastening arrangement for rotor blades as claimed in one of
claims 1 to 7, characterized in that the last blade root (1)
assembled into the peripheral groove (2) is locked to the adjacent
blade roots by displacing one or two connecting pieces (5d, 5e).
Description
[0001] The invention relates to rotor blades with blade roots,
which are fastened in peripheral grooves on the rotor of a
turbomachine. It relates, in particular, to fastening them and
securing them against twisting and falling out of the groove.
[0002] A known way of assembling rotor blades on a rotor of a
turbomachine is anchoring by means of blade roots in T-shaped
peripheral grooves. In order to permit the assembly of the blades
in a peripheral groove, in particular the last blades, a certain
assembly clearance in the peripheral direction is necessary. During
operation of the machine, it can happen that the rotor blades are
displaced and a gap forms which is large enough for a blade root to
rotate and fall out of the groove. This problem is solved by
reducing the assembly clearance by tightly fitting intermediate
pieces between the blade roots so that the assembly clearance is
filled up. After fitting of the intermediate pieces, however, the
remaining clearance between the blade roots is often too small to
permit free thermal expansions. Because of the expansions, forces
then occur which can interfere with the smooth running of the rotor
and finally cause vibrations.
[0003] The object of the invention is, therefore, to provide a
fastening arrangement for rotor blades with blade roots in
peripheral grooves on the rotor of a turbomachine, which
arrangement prevents the blade roots from twisting and falling out
and, at the same time, ensures a sufficiently large clearance for
free thermal expansions.
[0004] This object is achieved by means of a blade fastening
arrangement in accordance with claim 1. The blade roots, which are
anchored in peripheral grooves, each have, according to the
invention, at least one recess or opening which extends in the
peripheral direction and in each of which is arranged a connecting
piece which connects at least two blade roots to one another to
form a blade pack. Thereby the blade roots connected in this way
are prevented from twisting. A connecting piece consists of a
shaped piece of an arbitrary cross section and it is arranged in a
recess or opening whose cross section is matched to the shaped
piece. In this arrangement, the recess or opening and the shaped
piece are dimensioned in such a way that the shaped piece lies with
little clearance in the recess or opening and that a displacement
of a blade root and of the shaped piece relative to one another is
still possible.
[0005] According to the invention, the rotational freedom of the
blade roots about the blade longitudinal axis is reduced by the
connection of blade roots to such an extent that they are secured
against twisting and falling out. Intermediate pieces are fitted
between the blade roots in order to partially fill up the assembly
gap. They no longer, however, incorporate the function of securing
the blade roots against twisting and they do not now need to be so
tightly fitted. By this means, free thermal expansion of the blade
roots is ensured.
[0006] In a first embodiment of the invention, the connecting piece
consists of a shaped piece of rectangular cross section, which is
laid into a similarly rectangular recess on the surface of the
blade root which faces toward the rotor and bottom of the groove.
In a second embodiment of the invention, the connecting piece
consists of a round wire, which is pushed into a bore opening in
the blade root. Here again, the diameter of the opening and that of
the wire are dimensioned in such a way that a displacement of the
blade root along the wire is possible.
[0007] In one variant, each of the blade roots has a recess or
opening which extends in the peripheral direction. In a further
variant of the invention, each of the blade roots has two recesses
or openings, which extend parallel to one another in the peripheral
direction and into each of which a connecting piece is laid or
pushed.
[0008] In consideration of the thermal expansions of the turbine
parts and assembly of the blade roots, various lengths of the
connecting piece can be embodied. In one embodiment, there is an
arrangement of a single connecting piece for this purpose, which
connecting piece extends over almost the complete periphery of a
groove and connects almost all the blade roots in this groove to
one another. In a further embodiment, shorter connecting pieces are
arranged in the recesses or openings, each of which connecting
pieces connects two or more adjacent blade roots together to form a
blade pack.
[0009] In a further embodiment with two recesses or openings
extending parallel to one another, there is an arrangement of short
connecting pieces, each of which connect two blade roots to one
another to form a blade root pair. Connecting pieces which are
arranged adjacent and parallel to one another are then offset by
one blade root relative to one another, a first connecting piece
being laid into a first recess or opening and connecting a first
blade root and an adjacent, second blade root. A second, parallel
connecting piece is laid into the second, adjacent recess or
opening and connects the second blade root and the adjacent, third
blade root, and so on.
[0010] The root of the last blade is rotated into an assembly gap
provided for it in the groove and, to secure it against twisting,
is locked to the adjacent blade roots by a final connecting piece,
by a connecting piece being pulled into the recess or opening of
the last blade root.
[0011] In a further embodiment of the blade fastening arrangement
according to the invention, a contact pressure spring is arranged
in each recess on the surface of the blade root facing toward the
bottom of the groove, which contact pressure spring further reduces
a displacement of the blade on the rotor so that a gap formation,
and aerodynamic disadvantages resulting from it, are avoided.
[0012] In order to realize the fastening arrangement according to
the invention, work is only necessary on the blade roots, whereas
the rotor remains unaltered. This fastening arrangement is
therefore particularly suitable for retrofitting to existing
machines.
[0013] FIG. 1 shows a longitudinal section through a blade root
which is anchored in a peripheral groove with a connecting piece
according to the invention,
[0014] FIG. 2 shows a view II of a plurality of blade roots and an
example of securing against twisting by connecting a plurality of
adjacent blade roots,
[0015] FIG. 3 shows, in the same view as that of FIG. 2, a further
example of securing against twisting according to the invention, by
connecting a plurality of blade roots,
[0016] FIGS. 4a-e show, in the same view as that of FIG. 2, a
procedure for assembling and locking the last blade root with
connecting pieces according to the invention.
[0017] FIG. 1 shows a blade root 1, which is anchored in an
inverted T-shaped peripheral groove 2 in a rotor 3 of a
turbomachine. On the surface facing toward the bottom of the
groove, the blade root 1 has a recess 4 with a rectangular cross
section. A connecting piece 5 with a similarly rectangular cross
section is laid into the recess with a small clearance. The cross
section of the recess in the blade root and of the associated
connecting piece is, fundamentally, arbitrary. Elliptical or round
shapes, for example, can also be embodied instead of the
rectangular cross section for the recess and the connecting piece.
A round recess 6, in which there is laid a pressure spring 7 which
additionally prevents displacements of the blade root, is arranged
in the center of the surface of the blade root facing toward the
bottom of the groove. FIG. 2 shows a view II of a plurality of
adjacent blade roots 1, which are anchored in the peripheral groove
and which are connected by a connecting piece 5. They form a pack
of blade roots which, because of its larger length, cannot twist in
the peripheral groove even if an assembly gap occurs due to
displacement of the blade roots during operation. The connecting
piece therefore ensures securing against twisting and this makes it
impossible for the blades to fall out. In this way, the blade roots
along the total periphery of the groove are connected to one
another to form a plurality of such blade root packs. A connection
of almost all the blade roots, with the exception of the last or
the last two blades, by means of a single connecting piece can
likewise be embodied.
[0018] FIG. 3 shows a plurality of blade roots anchored in a
peripheral groove by means of a further arrangement, according to
the invention, of connecting pieces. On their side facing toward
the bottom of the groove, the blade roots 1, 1a, 1b, 1c, 1d each
have two parallel recesses, which are arranged on both sides of the
center of the blade root. Short connecting pieces 5a, 5b, 5c are
laid in both recesses. Each connecting piece connects one pair of
blade roots, the connecting pieces arranged parallel and adjacent
to one another being respectively offset by one blade root. A
connecting piece 5a is, for example, laid into the first recess of
the two blade roots 1a and 1b, connecting them and securing them
against twisting. A second connecting piece 5d is laid into the
second parallel recess of the blade roots 1b, 1c so that it
connects this pair of blade roots. The next connecting piece 5c is,
in turn, laid into the recess on the first side of the blade roots
and connects the blade roots 1c and 1d. The assembly of the last
blade of the peripheral groove and the locking of its blade root to
the adjacent blade roots by means of the connecting pieces
according to the invention is shown in FIGS. 4a to 4e. FIG. 4a
shows blade roots 11 and 12, which are located at a distance from
the blade roots 13 and 14 due to an assembly gap in the peripheral
groove 2. The blade roots 11 and 12 are connected to one another by
connecting pieces 5d and 5e. They both extend, for example, over a
plurality of blade roots. The blade roots 13 and 14 are connected
to one another and secured by means of connecting pieces 5f and 5g.
FIG. 4b shows the same peripheral groove 2 with the last blade,
whose blade root 15 has been anchored in the assembly gap of the
groove 2. The recesses 4 of the blade root 15 are still empty in
this case and the blade root is, therefore, not yet secured against
twisting. The locking of this last blade root takes place as
follows, in accordance with FIGS. 4c-e: the blade root 12 is first
pushed over the remaining gap close to the blade root 15 so that
the ends of the connecting pieces 5d and 5e become visible. The
connecting piece 5d is then pulled in the same direction until its
end comes to rest in the recess 4 of the blade root 12. The
assembly and locking is completed by the gaps between all the blade
roots in the peripheral groove being slightly increased so that the
gap which has remained after the assembly of the last blade is
distributed over the complete peripheral groove. These remaining
gaps are filled by means of intermediate pieces. The result is that
almost all the blade roots are secured against twisting by two
parallel-extending connecting pieces and the remaining blade roots
are at least secured by one connecting piece. This ensures that
none of the blades can twist and fall out of the groove. The
intermediate pieces are a known component and are not shown here.
They are dimensioned in such a way that they reduce the assembly
clearance and, during operation of the turbine, no larger gap can
form which could interfere with the smooth-running of the rotor.
Because of the arrangement for securing against twisting, however,
they no longer need to fill the assembly clearance completely, so
that a sufficiently large free space, in which thermal expansions
can be freely ensured, remains between the blade roots.
List of Designations
[0019] 1, 1a-1d, 11-15 Blade root
[0020] 2 Peripheral groove
[0021] 3 Rotor
[0022] 4 Recess
[0023] 5, 5a-g Connecting piece
[0024] 6 Recess
[0025] 7 Contact pressure spring
* * * * *