Stator vane adjusting device of a gas turbine

Abstract

A stator vane adjusting device of a gas turbine having a plurality of stator vanes each swivellable about a radial axis and arranged in at least one radial plane, as well as at least one stator vane adjusting ring which is connected to the respective stator vanes and rotatable in the circumferential direction by means of an actuating device, where the stator vane adjusting ring is braced on a centrally arranged casing in the radial direction by means of several spacers distributed about the circumference and mounted on the stator vane adjusting ring, characterized in that a bush on which the spacer is mounted is fastened to the stator vane adjusting ring for each spacer, the bush being made from a plastic material with a high thermal expansion coefficient.

Claims

1. A stator vane adjusting device of a gas turbine having a plurality of stator vanes each swivellable about a radial axis and arranged in at least one radial plane, comprising: a stator vane adjusting ring connected to the plurality of stator vanes and rotatable in a circumferential direction by an actuating device, a plurality of spacers distributed about a circumference of the stator vane adjusting ring and mounted on the stator vane adjusting ring for bracing the stator vane adjusting ring in a radial direction on a centrally arranged casing of the gas turbine, for each of the plurality of spacers, a bush for mounting the spacer, the bush being fastened to the stator vane adjusting ring at a first position of the bush, the bush being made from a plastic or composite material with a higher thermal expansion coefficient than a thermal expansion coefficient of the stator vane adjusting ring, the spacer mounted to the bush at a second position of the bush radially outwardly of the first position of the bush such that, during operation of the gas turbine, the higher thermal expansion coefficient of the bush causes the spacer to move radially outwardly with respect to the stator vane adjusting ring; the spacer including a radially outwardly facing portion positioned directly radially inwardly of an inwardly facing portion of the bush, the spacer mounted to the bush such that the radially outwardly facing portion of the spacer is spaced radially inwardly apart from the radially inwardly facing portion of the bush such that the radially outwardly facing portion of the spacer does not engage the radially inwardly facing portion of the bush and radially outward movement of the radially outwardly facing portion of the spacer is not limited by the radially inwardly facing portion of the bush during the operation of the gas turbine.

2. The stator vane adjusting device in accordance with claim 1, wherein the bush is tubular and the spacer has a shaft centrally fastened inside the bush.

3. The stator vane adjusting device in accordance with claim 2, wherein the shaft is connected to the bush by a threaded connection.

4. The stator vane adjusting device in accordance with claim 3, wherein the bush is fastened to a radially inner side of the stator vane adjusting ring.

5. The stator vane adjusting device in accordance with claim 4, wherein the shaft is adjustable relative to the bush in the radial direction.

6. The stator vane adjusting device in accordance with claim 5, wherein the shaft is made from a metallic material having a similar or same thermal expansion coefficient as at least one chosen from the casing and the stator vane adjusting ring.

7. The stator vane adjusting device in accordance with claim 6, wherein the thermal expansion coefficient of the bush is higher than a thermal expansion coefficient of at least one chosen from the spacer and the casing.

8. The stator vane adjusting device in accordance with claim 7, wherein the thermal expansion coefficient of the bush is at least double the thermal expansion coefficient of at least one chosen from the stator vane adjusting ring, the spacer and the casing.

9. The stator vane adjusting device in accordance with claim 8, wherein the bush is made of polyimide.

10. The stator vane adjusting device in accordance with claim 9, wherein the stator vane adjusting ring and the spacer and the casing are manufactured from a high-strength steel alloy or from a titanium alloy.

11. The stator vane adjusting device in accordance with claim 1, wherein the bush is fastened to a radially inner side of the stator vane adjusting ring.

12. The stator vane adjusting device in accordance with claim 2, wherein the shaft is adjustable relative to the bush in the radial direction.

13. The stator vane adjusting device in accordance with claim 2, wherein the shaft is made from a metallic material having a similar or same thermal expansion coefficient as at least one chosen from the casing and the stator vane adjusting ring.

14. The stator vane adjusting device in accordance with claim 13, wherein the thermal expansion coefficient of the bush is higher than a thermal expansion coefficient of at least one chosen from the spacer and the casing.

15. The stator vane adjusting device in accordance with claim 13, wherein the thermal expansion coefficient of the bush is at least double the thermal expansion coefficient of at least one chosen from the stator vane adjusting ring, the spacer and the casing.

16. The stator vane adjusting device in accordance with claim 1, wherein the thermal expansion coefficient of the bush is higher than a thermal expansion coefficient of at least one chosen from the spacer and the casing.

17. The stator vane adjusting device in accordance with claim 1, wherein the thermal expansion coefficient of the bush is at least double the thermal expansion coefficient of at least one chosen from the stator vane adjusting ring, the spacer and the casing.

18. The stator vane adjusting device in accordance with claim 1, wherein the bush is made of polyimide.

19. The stator vane adjusting device in accordance with claim 1, wherein the stator vane adjusting ring and the spacer and the casing are manufactured from a high-strength steel alloy or from a titanium alloy.

Description

(1) The present invention is described in the following in light of the accompanying drawing, showing an exemplary embodiment. In the drawing,

(2) FIG. 1 shows a schematic representation of a gas-turbine engine in accordance with the present invention,

(3) FIG. 2 shows a perspective partial view of a compressor with adjustable stator vanes and stator vane adjusting rings,

(4) FIG. 3 shows a detail view, by analogy with FIG. 2,

(5) FIG. 4 shows an exemplary embodiment of the inventive mounting of the spacer in a radial sectional plane, and

(6) FIG. 5 shows a further exemplary embodiment in a perspective sectional view.

(7) The gas-turbine engine 10 in accordance with FIG. 1 is an example of a turbomachine where the invention can be used. The following however makes clear that the invention can also be used in other turbomachines. The engine 10 is of conventional design and includes in the flow direction, one behind the other, an air inlet 11, a fan 12 rotating inside a casing, an intermediate-pressure compressor 13, a high-pressure compressor 14, combustion chambers 15, a high-pressure turbine 16, an intermediate-pressure turbine 17 and a low-pressure turbine 18 as well as an exhaust nozzle 19, all of which being arranged about a center engine axis 1.

(8) The intermediate-pressure compressor 13 and the high-pressure compressor 14 each include several stages, of which each has an arrangement extending in the circumferential direction of fixed and stationary guide vanes, generally referred to as stator vanes 20 and projecting radially inwards from the engine casing 21 in an annular flow duct through the compressors 13, 14. The compressors furthermore have an arrangement of compressor rotor blades 22 which project radially outwards from a rotatable drum or disk 26 linked to hubs 27 of the high-pressure turbine 16 or the intermediate-pressure turbine 17, respectively.

(9) The turbine sections 16, 17, 18 have similar stages, including an arrangement of stator vanes 23 projecting radially inwards from the casing 21 into the annular flow duct through the turbines 16, 17, 18, and a subsequent arrangement of turbine blades 24 projecting outwards from a rotatable hub 27. The compressor drum or compressor disk 26 and the blades 22 arranged thereon, as well as the turbine rotor hub 27 and the turbine rotor blades 24 arranged thereon rotate about the engine axis 1 during operation.

(10) The present invention is described in the following on the basis of a compressor, it is however also applicable to stator vanes of a turbine.

(11) FIG. 2 shows a perspective partial view of a compressor having several rows of adjustable stator vanes 20, between which compressor rotor blades 22 are arranged in each case. The individual stator vanes 20 are in each case swivellable about a radial axis 33. They are connected to a lever 34 which at its opposite end area is rotatably connected to a stator vane adjusting ring 29. Rotating the stator vane adjusting ring 29 in the circumferential direction results in swiveling of the individual levers 34. The effect of this is a rotation of the stator vanes 20 about the respective axis 33.

(12) An actuating device, not shown, which is for example designed as a piston-cylinder unit, is connected to a crankshaft 36 by one each connection rod (not shown), as is illustrated in FIG. 3. The crankshaft 36 is mounted by means of bearings 37. The crankshaft 36 is furthermore connected to the stator vane adjusting rings 29 by means of connection rods 35. Operating the actuating device thus leads to rotation or swiveling of the crankshaft 36, which in turn leads to a rotation of the respective stator vane adjusting ring 29, since the crankshaft 36 is connected to the stator vane adjusting ring 29 by a connection rod 35.

(13) FIG. 3 furthermore shows several spacers 30 arranged distributed around the circumference, which (see also FIG. 4 described in the following) have a shaft 32 settably mounted on the stator vane adjusting ring 29. The spacer is in contact with the surface of the casing 38 and is moved together with the stator vane adjusting ring 29 in the circumferential direction. The spacer centers the stator vane adjusting ring 29 in the radial direction relative to the casing 38. In the illustration of FIG. 3 the casing 38 has suitable bases or contact surfaces or similar at those areas which the spacer 30 contacts.

(14) FIG. 4 shows an exemplary embodiment of the solution in accordance with the invention in detail in a sectional view of a radial plane. The casing 38 is shown only schematically here and has a distance from the spacer 30 which is shown oversized for better illustration.

(15) A bush 31 made from a plastic or composite material is mounted on the stator vane adjusting ring 29. This bush is designed in the shape of a sleeve and has a central recess in which the shaft 32 of the spacer 30 is mounted. The shaft 32 is mounted on a radially outer area of the bush 31 by means of a thread 39. Rotating the shaft 32 thus makes it possible to adjust the radial position of the spacer 30.

(16) FIG. 4 shows a schematic view to illustrate the radial movements resulting from the thermal expansions. For example, heating up with a value of T=70 K is assumed here. With heating of this type of the casing 38 (in this example high-strength steel alloy with =10/1310.sup.6 mm/mmK, alternatively also titanium alloys with =8/1010.sup.6 mm/mmK), the casing expands in the example shown radially by 0.3 mm. The plastic or composite material of the bush 31 with =20/5010.sup.6 mm/mmK would expand by an amount of 0.42 mm. The shaft 32 and the adjusting ring 29 undergo a total length change of 0.08 mm (expansion coefficient =10/1310.sup.6 mm/mmK). This leads to a total radial outward movement of the spacer 30 of 0.34 mm, meaning that the distance between the spacer 30 and the surface of the casing 38 remains substantially constant, so that even with this increase in the temperature the stator vane adjusting ring 29 is precisely centered.

(17) FIG. 5 shows a further exemplary embodiment, where identical parts are identified with the same reference numerals. The shaft 32 has a thread at its end and is adjustably secured by means of a nut 40 which is connected to the bush 31.

LIST OF REFERENCE NUMERALS

(18) 1 Engine axis 10 Gas-turbine engine 11 Air inlet 12 Fan rotating inside the casing 13 Intermediate-pressure compressor 14 High-pressure compressor 15 Combustion chambers 16 High-pressure turbine 17 Intermediate-pressure turbine 18 Low-pressure turbine 19 Exhaust nozzle 20 Stator vanes 21 Engine casing 22 Compressor rotor blades 23 Stator vanes 24 Turbine blades 26 Compressor drum or disk 27 Turbine rotor hub 28 Exhaust cone 29 Stator vane adjusting ring 30 Spacer 31 Bush 32 Shaft 33 Axis 34 Lever 35 Connection rod 36 Crankshaft 37 Bearing 38 Casing 39 Thread 40 Nut