JP2001342993A - Fan for turbofan engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and surely resolve unbalance in a fan of a turbofan engine. SOLUTION: The fan 13 of the turbofan engine is provided with a fan disc 31 mounted on the front end of a rotation shaft 11, and a plurality of fan blades 32 radially provided in the outer periphery of this fan disc 31. Annular balance weights 31d and 31e are integrally formed in the front part and the rear part of the outer periphery part 31c of the fan disc 31 in advance, parts of these balance weights 31d and 31e are cut out, cutouts a and b are formed, and the unbalance in the fan 13 can thereby be resolved. Since the balance weights 31d, 31e and the fan disc 31 are integrally formed, there is no possibility of dropping out of the balance weights 31d and 31e.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fan for a turbofan engine having a fan disk provided on a rotating shaft of a turbofan engine, and a plurality of fan blades radially provided on an outer periphery of the fan disk. .

[0002]

2. Description of the Related Art Since a fan disk provided on a rotating shaft of a turbofan engine is larger than a compressor wheel or a turbine wheel, there is a problem that an imbalance in the fan disk causes vibration. Therefore, conventionally, imbalance has been solved by mounting a balance weight on the fan disk.

FIG. 5 shows a conventional balance weight mounting method. The fan 02 attached to the front end of the rotating shaft 01 has a fan disk 03 and a fan blade 0
, And annular balance weight mounting flanges 03a, 03b extending inward in the radial direction are integrally formed on the front and rear portions of the fan disk 03. The cross-section of the balance weight mounting flanges 03a and 03b is U
The letter-shaped balance weights 05 and 06 are fitted and fixed with bolts (not shown).

[0004]

In the above-mentioned conventional method, since the balance weights 05 and 06 are fixed with bolts or rivets, there is no possibility that the balance weights 05 and 06 fall off due to loosening of the bolts or rivets. could not. Further, since concave portions 03c and 03d are formed on the inner side of the annular balance weight mounting flanges 03a and 03b extending radially inward, the concave portions 03c and 03d are formed.
There was a problem that machining of c and 03d was troublesome and the machining cost increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to easily and surely eliminate imbalance between fans of a turbofan engine.

[0006]

According to the first aspect of the present invention, there is provided a fan disk provided on a rotating shaft of a turbofan engine, and a radially extending outer periphery of the fan disk. In a fan for a turbofan engine provided with a plurality of fan blades provided in the above, an annular balance weight is formed integrally with at least a part of the fan disk, and the balance weight is partially cut to adjust the balance. A fan for a turbofan engine, characterized in that it is performed, is proposed.

According to the above configuration, since the annular balance weight is formed integrally with at least a part of the fan disk, the unbalance of the fan can be effectively eliminated only by partially cutting the balance weight. it can. Moreover, since the balance weight is formed integrally with the fan disk, there is no possibility that the balance weight will fall off. Further, since there is no particular limitation on the cross-sectional shape of the balance weight, the processing is easier as compared with a case where a mounting flange for mounting a separate balance weight is integrally formed with the fan disk.

According to the invention described in claim 2,
In addition to the configuration of claim 1, there is proposed a fan for a turbofan engine, wherein the balance weights are formed at an axial front portion and an axial rear portion of a fan disk, respectively.

According to the above configuration, since the balance weights are formed at the axial front portion and the axial rear portion of the fan disk, not only the static imbalance but also the dynamic imbalance of the fan can be effectively eliminated. .

According to the third aspect of the present invention,
In addition to the configuration of claim 1 or 2, a nose cone mounting member is provided at the tip of the rotating shaft, and a nose cone is mounted on the nose cone mounting member. A fan for a turbofan engine is proposed.

According to the above construction, since the nose cone is attached to the nose cone attachment member provided at the tip of the rotating shaft, the nose cone is directly attached to a fan disk made of a material such as titanium which is difficult to machine. Processing cost can be reduced.

The inner shaft 11 of the embodiment corresponds to the rotating shaft of the present invention, and the front balance weight 31d and the rear balance weight 31e correspond to the balance weight of the present invention.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 4 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a turbofan engine, FIG. 2 is a view taken in the direction of arrow 2 in FIG. 1, and FIG. -3 line sectional view, FIG. 4
FIG. 4 is an enlarged view of a part of FIG.

First, the overall structure of the turbofan engine E will be described with reference to FIG. The turbofan engine E includes an inner shaft 11 and an outer shaft 12 that is rotatably fitted to the outer periphery of the inner shaft 11. An axial fan 13 is provided at the front end of the inner shaft 11, and a first-stage low-pressure turbine wheel 14 and a second-stage low-pressure turbine wheel 15 are provided at the rear end of the inner shaft 11. A centrifugal compressor wheel 16 is provided at the front end of the outer shaft 12 shorter than the inner shaft 11, and an axial-flow high-pressure turbine wheel 17 is provided at the rear end.

The fan 1 sucked from the front of the engine E
3 is discharged from the rear of the engine E through a bypass passage 18 disposed along the outer periphery of the engine E, and the remainder of the air is
8 is led to the compressor wheel 16 via a compressed air passage 19 arranged radially inside. The air further compressed by the compressor wheel 16 is supplied to an annular type combustor 20, where the air is mixed with fuel supplied from a fuel injection nozzle 21 and burned. The combustion gas generated in the combustor 20 is supplied to a high-pressure turbine wheel 17 provided at an upstream end of the combustion gas passage 22 and first and second-stage low-pressure turbine wheels 14 and 1 provided at an intermediate portion of the combustion gas passage 22.
5 and is discharged from the rear of the engine E.

As apparent from FIGS. 2 to 4, the fan 13 made of, for example, titanium includes a fan disk 31 and a plurality of fan blades 32 extending radially from the outer peripheral surface of the fan disk 31. The fan disk 31 has an inner peripheral portion 31b and an outer peripheral portion 31c connected via a thin portion 31a. The inner peripheral portion 31b is spline-fitted 33 on the front outer periphery of the inner shaft 11, and further, for example, The nose cone attachment member 34 made of iron is fitted and fastened together with the nut 40. Nose cone 35 smoothly connected to the outer surface of outer peripheral portion 31c of fan disk 31
Are fixed to the nose cone mounting member 34 by four bolts 36 which penetrate through four mounting recesses 35a formed at the rear end thereof.

The outside of the fan 13 in the radial direction is covered with a cylindrical fan case 37, and the tips of the fan blades 32 are opposed to the inner peripheral surface of the fan case 37 with a slight gap. A plurality of fan outlet blades 38 extending inward in the radial direction are provided on the rear inner peripheral surface of the fan case 37, and the inner ends of the fan outlet blades 38 are smooth on the outer surface of the outer peripheral portion 31 c of the fan disk 31. Is connected to the fairing 39 connected to the.

A front balance weight 31d having a triangular cross section is integrally formed at the front end of the outer peripheral portion 31c of the fan disk 31, and a rear balance weight 31e having a triangular cross section is integrally formed at the rear inner surface of the outer peripheral portion 31c. . The front balance weight 31d is covered by the rear end of the nose cone 35 and is not visible from the outside. The rear balance weight 31e is provided on the inner surface of the outer peripheral portion 31c of the fan disk 31 and is not visible from the outside. It is.

In order to adjust static imbalance and dynamic imbalance of the fan 13, a notch a (see FIG. 2) is formed in an annular front balance weight 31d, and an annular rear balance weight 31e is formed. Has notches b and c
(See FIG. 3) is formed. The notches a to c are fans 1
3 is not formed at the time of completion, and the completed fan 13
It is machined by cutting when adjusting the balance.

There are static imbalance and dynamic imbalance of the rotating body that causes vibration, and the static imbalance occurs when the center of gravity of the rotating body does not exist on the rotating shaft. Accordingly, static imbalance can be eliminated by mounting the balance weight and moving the center of gravity of the rotating body on the rotating shaft. In addition, even if the static imbalance of the entire rotating body has been eliminated, if there are unbalanced parts at a plurality of places separated in the axial direction of the rotating body, the rotating body is rotated by centrifugal force acting on the plurality of unbalanced parts. A bending moment is generated in the shaft, resulting in a state of dynamic imbalance. This dynamic imbalance can be eliminated by mounting balance weights in the two rotating surfaces separated from each other in the axial direction of the rotating shaft.

Therefore, according to the present embodiment, the front balance weight 31d and the rear balance weight 31e provided at the front and rear portions of the fan disk 31, respectively, are appropriately cut and adjusted to adjust the weight.
, The static imbalance and the dynamic imbalance can both be eliminated, and the vibration during rotation can be effectively suppressed.

Moreover, since the balance adjustment is performed by cutting a part of the front balance weight 31d and the rear balance weight 31e which are formed integrally with the fan disk 31 in advance, there is no possibility that the balance weight will fall off. Further, since the front balance weight 31d and the rear balance weight 31e are directly exposed on the front and rear surfaces of the fan 13, the cutting process is extremely easy. Further, since there are no special restrictions on the cross-sectional shapes of the front balance weight 31d and the rear balance weight 31e, the number of processing steps is smaller than that in the case of forming the balance weight mounting flanges 03a and 03b having a complicated cross-sectional shape shown in FIG. Can be greatly reduced.

A nose cone mounting member 34 is fixed to the tip of the inner shaft 11 with a nut 40, and a nose cone 35 is bolted to the nose cone mounting member 34.
, The processing cost can be reduced as compared with a case where a nut is attached to the fan disk 31 formed of a material such as titanium which is difficult to process by caulking or a female screw is processed.

Although the embodiments of the present invention have been described in detail above, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the first aspect of the present invention, the number of balance weights is arbitrary, and a sufficient effect can be obtained only by providing one balance weight. Further, the size and number of the cutouts a to c formed in the front balance weight 31d and the rear balance weight 31e are not limited to those of the embodiment, and can be appropriately changed according to the unbalance state of the fan 13.

[0027]

As described above, according to the first aspect of the present invention, since the annular balance weight is formed integrally with at least a part of the fan disk, it is only necessary to partially cut the balance weight. The imbalance between fans can be effectively eliminated. Moreover, since the balance weight is formed integrally with the fan disk, there is no possibility that the balance weight will fall off. Further, since there is no particular limitation on the cross-sectional shape of the balance weight, the processing is easier as compared with a case where a mounting flange for mounting a separate balance weight is integrally formed with the fan disk.

According to the invention described in claim 2,
Since the balance weights are formed at the front portion and the rear portion in the axial direction of the fan disk, not only static imbalance but also dynamic imbalance of the fan can be effectively eliminated.

According to the third aspect of the present invention,
Since the nose cone is attached to the nose cone attachment member provided at the tip of the rotating shaft, machining costs can be reduced compared to the case where the nose cone is directly attached to a fan disk made of a material that is difficult to process such as titanium. .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a turbofan engine.

FIG. 2 is a view in the direction of arrows in FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1;

FIG. 4 is an enlarged view of part 4 of FIG.

FIG. 5 is a diagram showing a method of attaching a conventional balance weight.

[Explanation of symbols]

11 inner shaft (rotating shaft) 31 fan disk 31d front balance weight (balance weight) 31e rear balance weight (balance weight) 32 fan blade 34 nose cone attachment member 35 nose cone E turbo fan engine

Claims (3)

[Claims] 1. A fan disk (31) provided on a rotating shaft (11) of a turbofan engine (E), and a plurality of fan blades (32) radially provided on an outer periphery of the fan disk (31). In a fan for a turbofan engine having: (1) annular balance weights (31d, 31e) are integrally formed on at least a part of the fan disk (31);
A fan for a turbofan engine, wherein a balance is adjusted by partially cutting the balance weights (31d, 31e). 2. The balance weights (31d, 31d).
2. The fan disk according to claim 1, wherein said e) is formed at an axial front portion and an axial rear portion, respectively.
A fan for a turbofan engine according to the item. 3. The nose cone mounting member (34) is provided at the tip of the rotating shaft (11), and the nose cone (35) is mounted on the nose cone mounting member (34). Or a fan for a turbofan engine according to item 2.