Turbine wheel including a turbine disk, turbine blades, and seal plates

Abstract

In a turbine wheel, each of seal plates is formed from an elastic plate member whose radially intermediate portion is curved projecting toward one axial end surfaces of turbine blades and a turbine disk. The seal plate includes: an assembly recessed portion recessed in a direction getting closer to the one axial end surfaces, near a radially outer end of the plate; and a disassembly protrusion projecting in a direction getting away from the one axial end surfaces, near a radially inner end of the plate. When the recessed portion is pressed for attaching the plate, a tip end of the recessed portion comes into contact with the one axial end surface of each turbine blade or the disk. The plate is accordingly inhibited from being excessively deformed. Thus, the plate is blocked from being plastically deformed, and is precluded from coming off the wheel.

Claims

1. A turbine wheel comprising: a turbine disk including a plurality of groove portions which are formed in its outer periphery; a plurality of turbine blades respectively including protrusions which are formed on their base ends, and fixed to the turbine disk by fitting the protrusions into the groove portions in an axial direction; outer annular grooves each formed in one axial end surface of a corresponding turbine blade, and each opened inward in a radial direction; an inner annular groove formed in one axial end surface of the turbine disk, and opened outward in the radial direction; and seal plates for sealing gaps between the groove portions and the protrusions, each seal plate being fixed to the one axial end surface of a respective one of the plurality of turbine blades and the one axial end surface of the turbine disk with a radially outer end portion of the seal plate in contact with a groove bottom of the outer annular groove of the respective one of the plurality of turbine blades, and with a radially inner end portion of the seal plate in engagement with a step portion in the inner annular groove, wherein each seal plate is formed from an elastic plate member whose radially intermediate portion is curved projecting in a first direction toward the one axial end surface of the respective one of the plurality of turbine blades and the one axial end surface of the turbine disk, and each seal plate includes an assembly recessed portion, which is recessed in a direction getting closer to the one axial end surface of the respective one of the plurality of turbine blades and the one axial end surface of the turbine disk, in a position near a radially outer end of the seal plate, the assembly recessed portion being adapted to receive a tip end of a tool and being formed in a part of the seal plate that is continuously curved with the radially intermediate portion to project in the first direction, and a disassembly protrusion, which projects in a direction getting away from the one axial end surface of the respective one of the plurality of turbine blades and the one axial end surface of the turbine disk, in a position near a radially inner end of the seal plate, wherein each seal plate is adapted to elastically deform to flatten a curve of the radially intermediate portion when the tool, with the tip end received in the assembly recessed portion, is moved in the first direction.

2. The turbine wheel according to claim 1, wherein the assembly recessed portion is formed from a groove extending in a peripheral direction of the seal plate, and a section of the assembly recessed portion is arcuate.

3. The turbine wheel according to claim 1, wherein the assembly recessed portion is formed from a first groove in the seal plate, the first groove defining a first recess in a first side of the seal plate, the first side of the seal plate facing in a second direction away from the one axial end surface of the respective one of the plurality of turbine blades and the one axial end surface of the turbine disk, and a first projection on a second side of the seal plate, the second side of the seal plate facing in the first direction.

4. The turbine wheel according to claim 3, wherein the disassembly protrusion is formed from a second groove in the seal plate, the second groove defining a first projection in the first side of the seal plate, and a second recess on the second side of the seal plate.

5. The turbine wheel according to claim 1, wherein each seal plate is adapted to elastically deform to flatten the curve of the radially intermediate portion so that the radially inner end portion of the seal plate disengages from the step portion in the inner annular groove, when the tool is pressed against the disassembly protrusion in the first direction.

6. The turbine wheel according to claim 5, wherein the assembly recessed portion is formed from a first groove in the seal plate, the first groove defining a first recess in a first side of the seal plate, the first side of the seal plate facing in a second direction away from the one axial end surface of the respective one of the plurality of turbine blades and the one axial end surface of the turbine disk, and a first projection on a second side of the seal plate, the second side of the seal plate facing in the first direction.

7. The turbine wheel according to claim 6, wherein the disassembly protrusion is formed from a second groove in the seal plate, the second groove defining a first projection in the first side of the seal plate, and a second recess on the second side of the seal plate.

8. The turbine wheel according to claim 5, wherein each seal plate is adapted to elastically deform to flatten the curve of the radially intermediate portion to allow the radially outer end portion of the seal plate, during assembly, to be received in the outer annular groove of the respective one of the plurality of turbine blades, when the radially inner end portion of the seal plate is in engagement with a groove bottom of the inner annular groove and the tool received in the assembly recessed portion is moved in the first direction.

9. The turbine wheel according to claim 8, wherein the assembly recessed portion is formed from a first groove in the seal plate, the first groove defining a first recess in a first side of the seal plate, the first side of the seal plate facing in a second direction away from the one axial end surface of the respective one of the plurality of turbine blades and the one axial end surface of the turbine disk, and a first projection on a second side of the seal plate, the second side of the seal plate facing in the first direction.

10. The turbine wheel according to claim 9, wherein the disassembly protrusion is formed from a second groove in the seal plate, the second groove defining a first projection in the first side of the seal plate, and a second recess on the second side of the seal plate.

11. The turbine wheel according to claim 1, wherein each seal plate is adapted to elastically deform to flatten the curve of the radially intermediate portion to allow the radially outer end portion of the seal plate, during assembly, to be received in the outer annular groove of the respective one of the plurality of turbine blades, when the radially inner end portion of the seal plate is in engagement with a groove bottom of the inner annular groove and the tool received in the assembly recessed portion is moved in the first direction.

12. The turbine wheel according to claim 11, wherein the assembly recessed portion is formed from a first groove in the seal plate, the first groove defining a first recess in a first side of the seal plate, the first side of the seal plate facing in a second direction away from the one axial end surface of the respective one of the plurality of turbine blades and the one axial end surface of the turbine disk, and a first projection on a second side of the seal plate, the second side of the seal plate facing in the first direction.

13. The turbine wheel according to claim 12, wherein the disassembly protrusion is formed from a second groove in the seal plate, the second groove defining a first projection in the first side of the seal plate, and a second recess on the second side of the seal plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view showing an overall structure of a twin-spool turbofan engine.

(2) FIG. 2 is a view showing a main part of a low-pressure turbine in a direction indicated with an arrow 2 in FIG. 1.

(3) FIG. 3 is a view of a part shown in a direction indicated with an arrow 3 in FIG. 2, corresponding to a condition in which a seal plate is removed from the part.

(4) FIG. 4 is a perspective view of the seal plate.

(5) FIGS. 5A to 5C are views for explaining a procedure for attaching the seal plate.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(6) Descriptions will be hereinbelow provided for an embodiment of the present invention on the basis of FIGS. 1 to 5C.

(7) As shown in FIG. 1, a twin-spool turbofan engine for an aircraft to which the present invention is applied includes an outer casing 11 and an inner casing 12. Front and rear portions of a low-pressure system shaft 15 are rotatably supported by an inside of the inner casing 12 via front and rear first bearings 13, 14, respectively. A tubular high-pressure system shaft 16 is fitted to an outer periphery of an axial-direction intermediate portion of the low-pressure system shaft 15 in a relatively rotatable manner. A front portion of the high-pressure system shaft 16 is rotatably supported by the inner casing 12 via a front second bearing 17, while a rear portion of the high-pressure system shaft 16 is supported by the low-pressure system shaft 15 in a relatively rotatable manner via a rear second bearing 18.

(8) A front fan 19 having blade ends which face an inner surface of the outer casing 11 is fixed to a front end of the low-pressure system shaft 15. Part of air sucked by the front fan 19 passes through stator vanes 20 disposed between the outer casing 11 and the inner casing 12. Part of the air having passed through the stator vanes 20 thereafter passes through an annular bypass duct 21 formed between the outer casing 11 and the inner casing 12, and is jetted rearward. Other part of the air is supplied to an axial low-pressure compressor 22 and a centrifugal high-pressure compressor 23 which are disposed inside the inner casing 12.

(9) The low-pressure compressor 22 includes: stator vanes 24 fixed to the inside of the inner casing 12; and a low-pressure compressor wheel 25 having compressor blades on its outer periphery, and fixed to the low-pressure system shaft 15. The high-pressure compressor 23 includes stator vanes 26 fixed to the inside of the inner casing 12; and a high-pressure compressor wheel 27 having compressor blades on its outer periphery, and fixed to the high-pressure system shaft 16.

(10) A reverse-flow combustion chamber 29 is disposed in a rear of a diffuser 28 connected to an outer periphery of the high-pressure compressor wheel 27. Fuel injection nozzles 30 inject fuel into the reverse-flow combustion chamber 29. The fuel and the air are mixed together and combusted inside the reverse-flow combustion chamber 29. The generated combustion gas is supplied to a high-pressure turbine 31 and a low-pressure turbine 32.

(11) The high-pressure turbine 31 includes: nozzle guide vanes 33 fixed to the inside of the inner casing 12; and a high-pressure turbine wheel 34 having turbine blades on its outer periphery, and fixed to the high-pressure system shaft 16. The low-pressure turbine 32 includes: nozzle guide vanes 35 fixed to the inside of the inner casing 12; and low-pressure turbine wheels 36 each having turbine blades on its outer periphery, and fixed to the low-pressure system shaft 15.

(12) For this reason, once the high-pressure system shaft 16 is driven by a starter motor (not illustrated), air sucked by the high-pressure compressor wheel 27 is supplied to the reverse-flow combustion chamber 29, and mixed with the fuel to be combusted. The generated combustion gas drives the high-pressure turbine wheel 34 and the low-pressure turbine wheels 36. As a result, the low-pressure system shaft 15 and the high-pressure system shaft 16 rotate. Accordingly, the front fan 19, the low-pressure compressor wheel 25 and the high-pressure compressor wheel 27 compress air, and supply the compressed air to the reverse-flow combustion chamber 29. Thereby, even after operation of the starter motor is stopped, the turbofan engine continues its operation.

(13) While the turbofan engine is in operation, part of air sucked by the front fan 19 passes through the bypass duct 21, and is jetted rearward so as to, particularly during low-speed flight, generate main thrust. The remaining part of the air sacked by the front fan 19 is supplied to the reverse-flow combustion chamber 29, and is mixed with the fuel to be combusted. The combusted gas drives the low-pressure system shaft 15 and the high-pressure system shaft 16, and is thereafter jetted rearward, generating thrust.

(14) As shown in FIG. 2, the low-pressure turbine 32 of the embodiment includes the two low-pressure turbine wheels 36. However, the two low-pressure turbine wheels 36 have substantially the same structure. For this reason, descriptions will be hereinbelow provided for one low-pressure turbine wheel 36.

(15) As shown in FIGS. 2 and 3, the low-pressure turbine wheel 36 includes: an annular turbine disk 43 fixed, with bolts 42, to an outer periphery of a boss 41 which is spline-connected to an outer periphery of the low-pressure system shaft 15; and multiple turbine blades 44 radially fixed to an outer periphery of the turbine disk 43. In order to withstand centrifugal force, the turbine blades 44 are supported by the turbine disk 43 with the assistance of a so-called Christmas-tree structure in which protrusions 44a projectingly provided to base end portions of the turbine blades 44 are respectively fitted into groove portions 43a formed in the outer periphery of the turbine disk 43 from the rear in the axial direction. Seal plates 45 are attached to a rear surface of the turbine disk 43 in a way that one seal plate 45 is provided to each two turbine blades 44 for the purpose of: preventing the protrusions 44a of the turbine blades 44 coming out of the respective groove portions 43a in the turbine disk 43 in the axial direction: and sealing gaps between the protrusions 44a and the groove portions 43a which are fitted to each other.

(16) To this end, an inner annular groove 43b opened outward in the radial direction is formed in a radially inner portion of the rear surface of the turbine disk 43, while outer annular grooves 44b opened inward in the radial direction are formed in rear surfaces of portions of the turbine blades 44 which face the protrusions 44a. The outer annular grooves 44b have a constant width in a front-rear direction. On the other hand, a step portion 43c is formed at a radially intermediate position of the inner annular groove 43b. The inner annular groove 43b is greater in front-rear width at its outer portion beyond the step portion 43c in the radial direction.

(17) As shown in FIG. 4, each seal plate 45 is formed from an elastic metal plate having a substantially rectangular shape. A radially intermediate portion of the seal plate 45 is curved and projects further toward rear end surfaces of the turbine blades 44 and the turbine disk 43 than opposite radial end portions of the seal plate 45. A groove-shaped assembly recessed portion 45c recessed in the axial direction toward the rear end surfaces of the turbine blades 44 and the turbine disk 43 is formed in a peripheral direction along a radially outer end portion 45a of the seal plate 45. In addition, a ridge-shaped disassembly protrusion 45d projecting in the axial direction in a way to get away from the rear end surfaces of the turbine blades 44 and the turbine disk 43 is formed in the peripheral direction along a radially inner end portion 45b.

(18) Next, descriptions will be provided for an operation of the embodiment of the present invention including the foregoing configuration.

(19) One seal plate 45 is attached to each two turbine blades 44 in order that with the protrusions 44a of the turbine blades 44 fitted into the groove portions 43a in the turbine disk 43 in the axial direction, the gaps between the groove portions 43a and the turbine blades 44 can be sealed with the seal plate 45.

(20) FIGS. 5A to 5C show a procedure for attaching the seal plate 45. As shown in FIG. 5A, first of all, the radially inner end portion 45b of the seal plate 45 is inserted into the inner annular groove 43b in the turbine disk 43 with a projecting-portion side of the arc-shaped curving seal plate 45 faced to the rear end surfaces of the turbine blades 44 and the turbine disk 43.

(21) Subsequently, as shown in FIG. SB, with the radially inner end portion 45b of the seal plate 45 held in contact with a groove bottom of the inner annular groove 43b, the assembly recessed portion 45c of the seal plate 45 is pressed with a tip end of a tool 46, and is thereby elastically deformed in a way that its curvature diminishes. By this the radially outer end portion 45a is faced to openings of the outer annular grooves 44b of the turbine blades 44.

(22) Thereafter, as shown in FIG. 5C, when the radially outer end portion 45a of the seal plate 45 is brought into contact with a groove bottom of the outer annular grooves 44b of the turbine blades 44 by moving the tip end of the tool 46 outward in the radial direction, the seal plate 45 starts to return to its original curving shape due to its own elasticity. Thereby, the radially inner end portion 45b comes into engagement with the step portion 43c in the inner annular groove 43b of the turbine disk 43, and is accordingly prevented from moving inward in the radial direction. Thus, the seal plate 45 is fixed onto the rear end surfaces of the turbine blades 44 and the turbine disk 43.

(23) Detachment of the seal plate 45 is achieved as follows. As indicated with dot-dash lines in FIG. 5C, the radially inner end portion 45b is released from its engagement with the step portion 43c in the inner annular groove 43b of the turbine disk 43 by pressing a portion of the seal plate 45 outward of the disassembly protrusion 45d in the radial direction with the tip end of the tool 46. Thereafter, the radially inner end portion 45b of the seal plate 45 is brought into contact with the groove bottom of the inner annular groove 43b of the turbine disk 43 by moving the tip end of the tool 46 inward in the radial direction. Thereby, the radially outer end portion 45a of the seal plate 45 comes out of the outer annular grooves 44b of the turbine blades 44. Thus, the seal plate 45 is detached from the turbine blades 44 and the turbine disk 43.

(24) Meanwhile, if the seal plate 45 formed from the elastic plate member would be excessively deformed when as shown in FIG. 5B, the assembly recessed portion 45c is pressed with the tool 46 for the purpose of attaching the seal plate 45, the seal plate 45 would lose its elasticity due to its plastic deformation. As a result, while in the attached state shown in FIG. 5C, the radially inner end portion 45b may come out of engagement with the step portion 43c in the inner annular groove 43b of the turbine disk 43 so that the seal plate 45 may accordingly come off.

(25) In contrast, according to the embodiment, when the assembly recessed portion 45c is pressed with the tool 46, a tip end of the assembly recessed portion 45c comes into contact with the rear end surface of each turbine blade 44 or the turbine disk 43, and the seal plate 45 is accordingly blocked from being excessively deformed (see FIG. 5B). For this reason, the seal plate 45 is prevented from being plastically deformed, and is precluded from coming off the turbine blades 44 and the turbine disk 43.

(26) Furthermore, the assembly recessed portion 45c is formed from the groove extending in the peripheral direction of the seal plate 45, and the section of the assembly recessed portion 45c is gently arc-shaped (see FIG. 4). The gently arc-shaped section not only makes it easier to control a thickness of the assembly recessed portion 45c and secures strength of the assembly recessed portion 45c more reliably while the seal plate 45 is being manufactured than in a case where the assembly recessed portion 45c is formed from a protrusion whose section is, for example, quadrangular box-shape. But also, the gently arc-shaped section makes stress less likely to concentrate on the assembly recessed portion 45c when the assembly recessed portion 45e is pressed for the purpose of fitting the seal plate 45 into the outer annular grooves 44b of the turbine blades 44, and makes the assembly recessed portion 45c and its vicinity come into contact with the rear end surface of each turbine blade 44 or the turbine disk 43 with a wider area. This makes it possible to prevent the plastic deformation of the seal plate 45 more securely.

(27) The foregoing descriptions have been provided for the embodiment of the present invention. Various design changes, however, can be made to the present invention within the scope not departing from the gist of the present invention.

(28) For example, although one seal plate 45 is attached to each two turbine blades 44 in the embodiment, the present invention is not limited to this.