EP1726780B1 - Gas turbine engine comprising a precision balancing assembly of the turbine rotor - Google Patents

Description

The invention relates to a gas turbine engine with an arrangement for fine balancing the surrounded in the fully assembled state of an outer and an inner housing rotor.

The rotors of the compressors and turbines of a gas turbine engine are rotating at a very high speed. Incorrectly balanced rotors therefore cause the shaft to flex, which can lead to backlashes in the rotor and static contact with the rotor. However, the resulting high clearance gaps lead to a loss of efficiency. Furthermore, unwanted vibrations are caused resulting in premature bearing wear or acute bearing damage. The service life of the rotor components is considerably limited. The balancing is known to be done by adding weights or material removal to the rotating components.

The balancing of the high-speed rotating rotors of a gas turbine engine initially takes place during the production of the rotating individual parts of the engine by material removal from the individual drums. Subsequently, the rotor is balanced in the assembled state a second time. After the engine with the housed in an inner and an outer housing rotor is completely mounted, only minor corrections to the low pressure wave are possible while a Fine balancing, that is, the elimination of residual unbalance at the hard to reach in the assembled state of the gas turbine engine high pressure shaft with surrounded by an outer casing and an inner casing rotors is practically impossible or causes considerable difficulties. Even a residual imbalance on the high pressure shaft can still lead to significant vibration and the associated consequential damage.

The US 5,545,010 describes an apparatus for balancing a gas turbine engine, wherein the access to the rotating components with the required balancing weights in a surrounded by an outer casing state. The device comprises a ring additionally attached to or integrally formed on an outer surface on the input side of the compressor with radially equidistant tapped holes for screwing in or out of balance weights. The access to the ring with the threaded holes or balance weights takes place here via an opening provided in the wall of the air inlet channel to the compressor and aligned with the threaded bores. The arrangement disclosed herein is disadvantageous in that the ring has a relatively high weight and accessibility via the gas path is possible only at the first rotor stage on the compressor. The balance weights are located near the bearing and in a small diameter area. This is not very effective in terms of rotor dynamics and requires correspondingly large weights.

Further, the US 6279420 a gas turbine engine with a system for fine balancing according to the prior art.

The invention is based on the object, an arrangement for fine balancing the fully assembled state of an outer and inner housing Specify surrounded rotor of a gas turbine engine, which allows for low net weight and only small balancing weights effective fine balancing of the rotor.

According to the invention the object is achieved with a trained according to the features of claim 1 arrangement. From the dependent claims, advantageous developments of the invention.

The gist of the invention is the regularly spaced array of insert bodies provided with an internally threaded through-bore in the circumferential groove of the rotor blades receiving blade roots of the compressor or turbine rear rotor writings. The through hole of the respective insertion body is in alignment in a certain rotor position, each with a provided in the inner and outer housing of the rotor opening, followed by the balancing a guide tube for feeding and screwing a balancing screw and for guiding a tool to the through hole. Thus, it is possible with little effort, in the assembled state of the engine, that is, after final assembly or after repairs, to eliminate remaining residual imbalances and thus extend the life of the engine. The balancing also takes place in a rotor dynamic optimal range, that is, it can - with little additional weight - far out on the rotor discs and in a central part of the rotor can be performed. Due to the use of the existing circumferential grooves, the balancing system can be installed with little effort into existing engines. Compared with known weight compensation systems, the cost and weight is low.

In a further embodiment of the invention, the insert body is formed so that the through hole is oriented perpendicular or at an acute angle to the rotor axis and the openings in the inner and outer housing are arranged vertically above the circumferential groove or offset accordingly to this. With an oblique orientation of the through hole, an air extraction slot provided in the inner housing can also act as an opening.

In an embodiment of the invention, the insert bodies consist of a base section adapted to the groove cross section and an adjoining threaded part for receiving the balancing screw.

The outer peripheral surface of the insert body is covered by the recesses of adjacent blade platforms. The balancing screw is equipped with a self-locking device to prevent its loosening during operation.

Fig. 1

eine detaillierte Schnittansicht einer von einem Innen- und Außengehäuse umgebenen hinteren Rotorstufe des Kompressors eines Gasturbinentriebwerks während des Einsetzens eines Auswuchtgewichtes;

Fig. 2

eine Ansicht nach Fig. 1, jedoch im Betriebszustand des Triebwerks nach Abschluss des Auswuchtens;

Fig. 3

eine vergrößerte Darstellung eines in die Umfangsnut einer Rotorscheibe des Kompressors eingefügten Einsetzkörpers;

Fig. 4

einen Längsschnitt mit einem zwischen zwei Rotorschaufeln in der Umfangsnut angeordneten Einsetzkörper; und

Fig. 5

eine Schnittdarstellung einer anderen Rotorstufe, bei der das Auswuchtgewicht über einen im Innengehäuse vorhandenen Schlitz in einen schräg angeordneten Einsetzkörper eingebracht wird.

An embodiment of the invention will be explained in more detail with reference to the drawing. Show it:

Fig. 1

a detailed sectional view of a surrounded by an inner and outer housing rear rotor stage of the compressor of a gas turbine engine during the insertion of a balancing weight;

Fig. 2

a view Fig. 1 but in the operating condition of the engine after completion of balancing;

Fig. 3

an enlarged view of an inserted into the circumferential groove of a rotor disk of the compressor insert body;

Fig. 4

a longitudinal section with an arranged between two rotor blades in the circumferential groove insert body; and

Fig. 5

a sectional view of another rotor stage, in which the balancing weight is introduced via a slot present in the inner housing in an obliquely arranged insert body.

In the drawing figures, the reference numeral 1 in an engine designate the outer housing, 2 the inner housing and 3 the rotor, here a rear rotor stage of the compressor. In this rear rotor stage, the rotor blades 4 are inserted into a circumferential groove 6 provided on the outer circumference of the rotor disk 5. The insert body 7 comprises a base part 8 adapted to the cross-sectional shape of the peripheral groove 6, a threaded part 9 which projects into opposite recesses of two adjoining platforms 10 of respectively adjacent rotor blades 4 is included, and a bore 11 with an internally threaded portion 12 a. Part of the arrangement for fine balancing is further a first opening 13 in the inner housing 2 and a first opening 13 perpendicularly aligned second opening 14 in the outer housing 1. In a certain rotational position of the rotor 3, the holes 11 are aligned with the first and second openings 13, 14, so that a penetrating guide tube 15 on the bore 11 of the respective insert body 7 can be placed. The guide tube 15 is fixed in the opening 14 of the outer housing, for example via a fit or by fastening screws. About the guide tube 15 can now for the purpose of fine balancing of fully assembled, surrounded by the inner and outer casings 1, 2 rotor 3 a balancing screw 16 passed to the jewieligen bore 11 in the insert body 7 and introduced into the guide tube 15 tool 17 in the insert body 7 are screwed.

In another - in Fig. 5 shown embodiment, the insert body 7 'with an obliquely arranged, on a in the inner housing 2 already existing air extraction slot 18 aligned bore 11' is formed. In a certain position of the rotor 3 is the bore 11 'with the staggered air extraction slot 18 and the further offset second opening 14 in the outer housing 1 in alignment. In this case, can be dispensed with the above-mentioned first opening 13 in the inner housing. The guide tube 15 is - guided in alignment with the angularly arranged bore 11 '- obliquely through the outer housing 1 and the inner housing 2 and placed on the insert body 7', then the balancing screw 16 supply and with the tool 17 in the female threaded portion of the bore 11 ' of the insert body 7 'screw.

After screwing the balancing screw 16, the tool 17 and the guide tube 15 is pulled out and the first and second openings in the inner and outer housing are with a - in Fig. 2 illustrated - double plug 19, which is bolted to the outer housing 1, closed.

With the embodiments described above, after complete assembly or after repairs of the engine, imbalances or residual imbalances in the assembled state can be compensated. The balancing takes place - optimally rotor rotor dynamic - in a far outboard diameter range of the rotor disk 5, so that the additional weight required for balancing is low. The arrangement of the insert body 7, 7 'at a predetermined regular distance between two rotor blades 4 in the existing circumferential grooves 6 of rotor disks 5 of the compressor or the turbine is possible with little effort and at the same time low weight.

LIST OF REFERENCE NUMBERS

1

outer casing

2

inner housing

3

rotor

4

rotor blade

5

rotor disc

6

circumferential groove

7, 7 '

insert body

8th

Base part v. 7, 7 '

9

Threaded part v. 7, 7 '

10

Platform v. 4

11, 11 '

Bore v. 7

12a

Female thread section v. 11, 11 '

12b

extended diameter range v. 11, 11 '

13

first opening in 2

14

second opening in 1

15

guide tube

16

balancing screw

17

Tool

18

Air extraction slot

19

double-bud

Claims (4)

1. Gas-turbine engine with an arrangement for precision balancing of the rotor (3) that in the fully assembled state is surrounded by an outer casing (1) and an inner casing (2), with the arrangement (4) including fixed inserts (7, 7') each having a radial bore (11, 11') provided with a female threaded section (12a), with the respective bore (11, 11') being in line with a first opening (13) in the inner casing (2) and a second opening (14) in the outer casing (1) at a certain rotational position of the rotor (3), and with a temporarily installed guide tube (15) for guiding a tool (17) passing through the two openings (13, 14) up to the bore (11, 11'), characterized in that the inserts (7, 7') for receiving a balancing screw (16) are inserted at an even spacing into the circumferential groove (6) provided for installing the rotor blades (4) of at least one of the rotor disks (5) of the compressor or the turbine, and fixed between adjacent platforms (10) of the rotor blades (4), with the inserts (7, 7') each having a base part (8) that matches the cross-sectional shape of the circumferential groove (6) and a threaded part (9) encompassed by recesses in the adjacent platforms (10) of the rotor blades (4), and with the guide tube (15) also being used for inserting the balancing screw (16).
2. Gas-turbine engine in accordance with Claim 1, characterized in that the first and the second openings (13, 14) are positioned vertically one above the other and in line with one of the bores (11) and that the openings (13, 14) after balancing can be closed using a twin plug (19).
3. Gas-turbine engine in accordance with Claim 1, characterized in that the bore (11') is positioned at an acute angle to the axial direction and in line with an offset air bleeding slot (18) acting as first opening in the inner casing and with an even farther offset second opening (14) in the outer casing (1), where the second opening (14) provided in the outer casing (1) can be closed using a single plug.
4. Gas-turbine engine in accordance with Claim 1, characterized in that the bore (11, 11') in the insert (7, 7') is provided with a female threaded section (12a).

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