JPS61257398A - Hub structure of rotor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hub structure for a rotary wing used in a rotary wing aircraft, and particularly to an unarticulated hub structure for a rotary wing.

(Prior art) The hub structure of rotor blades used in conventional rotor-wing aircraft uses needle roller bearings and bearings made of a laminated structure of elastomer and metal plates to control the flap direction of the rotor blades, the lead direction, Although the hub is articulated and configured to allow movement in the lug direction and the pitch direction, recently a non-articulated hub has been developed using a composite material made of fiber-reinforced resin with high fatigue strength. These jointless hubs have all or part of the bearings to allow movement in the flap direction, lead-lag direction, and pitch direction replaced with a flexible girder made of composite material, and this flexible girder The structure allows movement in each direction by bending.

In unarticulated hubs, torsionally rigid cylindrical pitch housings or torque tubes are provided surrounding or parallel to these composite flexure spars to control the pitch angle of the rotor blades. It is being The pitch housing or torque tube has an outer end fixed to the rotor blade, an inner end supported by a flexure girder via a spherical bearing, and an inner end of the pitch housing or torque tube. , a pitch horn is provided and the pitch horn is connected to the swashplate via a pitch link.

In this way, jointless hubs have many advantages such as simple structure, high reliability, and easy weight reduction, but it is difficult to provide damping in the lead and lug directions. However, there are few hubs that have been put into practical use.

An example of a non-articulated hub that solves the problem of damping in the lead-lag direction is the non-articulated rotor blade disclosed in Japanese Patent Application No. 58-61489 (Japanese Patent Application Laid-Open No. 59-186798). The structure disclosed in this patent publication is that the pitch housing is divided into an outer part and an inner part when viewed in the radial direction, and the outer part and the inner part are connected by a pair of bearings or flexible parts provided at the upper and lower parts, respectively. Further, the outer part and the inner part are connected to each other at the front or rear part in the rotational direction.
They are connected via a lag damper. In this structure, when the rotor blade moves in the lead-lag direction, the pitch housing swings around the bearing or flexible part, which causes a tensile or compressive force to be applied to the lead-lag damper. is added to obtain the necessary damping.

(Problems to be Solved by the Invention) In the hub structure described in the above-mentioned published patent application, in an example in which a pair of bearings is used, there are two bearings at the connection part of the pitch housing, and two bearings at the joint part of the pitch housing, and a lead lug. Two pieces are required at the damper mounting part. The purpose of jointless hubs is to improve reliability and maintainability by replacing bearings with flexures.
The aim is to reduce costs, and one pitch/
The need for four bearings in the housing offsets the original aim. In addition, in a structure in which the inner and outer ends of the pitch/nosing are connected to each other by a pair of flexible parts instead of a pair of bearings, the flexible part must not be bent and deformed in the lead/lug direction. However, in order to withstand this bending deformation with strength, the flexible portion needs to be thin in the lead/lug direction and also have a certain length in the radial direction. On the other hand, in addition to the rigidity and strength in the lead-lag direction as described above, this flexible part has the necessary rigidity to withstand the torsional moment transmitted from the pitch link and the load in the flap direction transmitted from the rotor blade. required to have one. These requirements in each direction contradict each other, and designing a flexible portion that satisfies these requirements is extremely difficult and poses complex structural strength problems. Furthermore, in addition to these serious problems, if one flexible part is damaged, it is impossible to support the load with only the remaining flexible part, leading to a catastrophic accident. is inevitable,
Lacking reliability. Furthermore, this structure also requires two bearings at the lead-lug-damper mounting portion.

Therefore, an object of the present invention is to reduce the number of bearings used, allow the pitch housing to be easily bent in the lead-lug direction, and yet maintain sufficient rigidity and strength against torsional and flap-direction loads. The purpose of the present invention is to provide a rotary blade hub structure that allows easy installation of lead, lug, and dampers.

(Means for Solving the Problems) In order to solve the above problems, the present invention comprises a hub body fixed to a rotating shaft and a pitch housing, and the hub body extends radially and rotates at the tip. The blade has a plurality of flexible girders supporting the wing blades, the flexible girders are capable of deflecting at least in the lead lug direction, and a pitch housing is provided to surround the flexible girders at intervals. In the hub structure of a rotor blade, the pitch housing is constituted by an inner end portion disposed radially inwardly and an outer end portion disposed radially outwardly, and the inner end portion is arranged in a radially outward direction. The pitch housing is supported by a hub via a spherical bearing near the inner end, the outer end is rigidly fixed to the inner end of the rotor blade, and the inner and outer ends of the pitch housing are mutually connected. At the front and rear in the direction of rotation, a pair of flexible members with low rigidity in the lead/lug direction and high rigidity in the flap direction are provided to sandwich the flexible girders of the knob, and at the same time, the flexible girders of the hub are connected. It is characterized by being joined at the top and bottom positions by lead-lug-dampers formed into plate shapes.

(Function) A pair of flexible members connecting the inner and outer ends of the pitch housing are arranged parallel to each other or at a slight angle, and when the blade performs a lead-lag motion, this flexible member bends and deforms. This causes a deviation in the rotational direction between the inner end and the outer end.

This misalignment is due to the lead connecting the inner and outer ends at the top and bottom.
It acts as a shearing force on the lug damper, and the damper generates a damping force.

(Effects) The most important part of the present invention is to pitch a pair of flexible members.
This is because they are provided at the center of the housing and at the front and rear of the rotational direction. For example, by forming this flexible material to have an I-shaped cross section, it is possible to set the rigidity in the lead/lug direction to be low and the rigidity in the flap direction to be high, and the rigidity in the torsional direction to be set to be high in the flap direction. Since the stiffness can be increased in proportion to the stiffness, the flexible material can be designed with consistent strength and stiffness in each direction.

Furthermore, by providing a pair of flexible members at the front and rear in the rotation direction, each flexible member undergoes bending deformation as the rotor blades move in the lead and lug, causing the inner and outer ends of the pitch housing to bend. In between, parallel movement with relatively little rotational displacement occurs.

For this reason, the lead-lag dampers that are attached to the upper and lower parts of the pitch housing can be flat-shaped dampers, such as dampers with a viscoelastic material sandwiched between plates. The inner end and the outer end can be directly connected to each other without using a bearing.

That is, it is possible to obtain the necessary damping without using any bearings, including the flexible portions, and it is possible to reduce costs and improve reliability.

In addition, the damper itself can be structured to restrain displacement in the flap direction, and means for restraining displacement in the flap direction can be provided in the upper and lower parts of the pitch housing in parallel with the damper. In such a case, the damper or flap direction restraint means and the flexible material will provide four load transmission paths in the flap direction, so even if one of the flexible materials is damaged, the remaining three locations will be temporarily protected. This makes it possible to support the load, making the structure highly reliable. This is of utmost importance in aircraft construction.

(Description of Embodiments) Referring to FIG. 1, the jointless hub structure 100 has a rotating shaft 1
It has a rigid hub body 3 fixed to its upper end, and integrally molded into this hub body 3 are radially extending flexure beams 2 at 90'' intervals. As can be seen, it is elongated and has sufficient flexibility in the flap and lead lug directions.

A pitch housing 4 is provided to surround the flexible girder 2. The pitch housing 4 includes an inner end 5, an outer end 7, and a pair of flexible members 6 that connect the inner end and the outer end in the front and back of the rotation direction. The pitch housing inner end 5 has a hollow cylindrical shape, and is connected to a flexible member 6 by a bolt 12 at the outer end in the radial direction, and is fixed to the spherical bearing 10 by a bolt 13 at the inner end in the radial direction. . The spherical bearing 10 is disposed in an opening 20 formed at the root of the flexible girder 2 of the hub water pair 3, that is, at the radially inner end. 2 is rotatably supported. As shown in FIG. 2, the spherical bearing 10 has a housing 31, and a spherical lining 34 is provided on the inner surface of the housing 31, and balls 33 that come into contact with the lining 34 and transfer.
is arranged within the housing 31. A shaft 32 is provided through the ball 33 and is attached to the flexible girder 2 at its radially inner and outer ends. bolt 1
3 attaches the housing 31 to the pitch housing inner end 5. The flexure 6 is further rigidly connected to the pitch housing outer end 7 by bolts 14. Further, the pitch housing outer end portion 7 is rigidly fixed at the outer end in the radial direction to the tip portions of the rotor blade 11 and the flexible spar 2 by bolts 8 and 9, respectively. FIG. 4 shows the connection between the pitch housing outer end 7 and the flexible girder 2. FIG.

It is desirable that the flexible member 6 is formed into an I-shaped cross section as shown in FIG. 3. According to this shape, it is possible to design the flexible member 6 to have low rigidity in the lead/lug direction and high rigidity in the flap direction. can. Since the flexible members 6 are arranged to extend in the radial direction at the front and rear in the rotational direction, when the rotor blade moves in the lead-lag direction as shown in FIG. Bending deformation occurs as shown in the figure. Flexible material 6 of pitch housing
The movement of points 61, 62, 63 and 64 at both ends of is shown in Figure 6, where point 62 is 62a and point 63 is 63.
Move to a. As is clear from Fig. 6, the relationship between the four points is such that the quadrilateral is transformed into a parallelogram, so the points 61.64 at the inner end and the points 62.63 at the outer end are , causing parallel movement without rotational movement. A lead-lag damper 17 for applying a damping force to this parallel movement is arranged between the inner end 5 and the outer end 7 at the upper and lower parts of the pitch housing 4.

As is clear from the foregoing, the parallel movement caused by the deformation of the flexible member 6 purely transmits only a shearing force to the damper 17 that connects the inner end 5 and the outer end 7 at the top and bottom.

That is, the inner end portion 5 and the outer end portion 7 do not rotate relative to each other but move in parallel due to the lead-lag motion of the rotor blades. Therefore, the bearings conventionally required to absorb the rotational movement of the damper attachment point are no longer necessary, and the damper 17 can be rigidly attached to each of the inner end 5 and the outer end 7.

In addition, since the flexible member 6 is provided at the center of the pitch housing 4 in the radial direction, the flexible member 6
It must withstand the steering forces transmitted to the rotor blades 11 via the rotor blades 11. This steering force is applied to the pitch housing as a torsional moment. Figure 8 shows the deformation of the flexible members 6 when this torsional moment is applied.As is clear from the figure, by providing the flexible members 6 before and after the rotation direction, the torsional moment is reduced by each flexible member. Converted to flap direction target. As mentioned above, the flexible material 6 is
Since the flap direction rigidity can be made sufficiently high, the torsional direction rigidity can also be made sufficiently high, and the function of transmitting the steering force of the pitch housing can be fully satisfied.

As shown in FIGS. 3 and 7, the lead lug damper 17 includes a damper fitting 51 attached to the inner end 5 of the pitch housing, a damper fitting 52 attached to the outer end 7, and a fitting 51. .52 and a viscoelastic body 53 disposed between the two. The damper fitting 51 is divided into two parts, upper and lower, and is bonded to the fitting 52 via a viscoelastic body 53 bonded to the inner surface. The damper fitting 51 is tightened by a bolt 55 passing through the center, and this compressive force can apply a preload in the compression direction to the viscoelastic body, and prevents the viscoelastic body 53 from being loaded in the peeling direction. It can be prevented.

The bolt 55 is attached to the fitting 51 without any gaps, and is attached to the fitting 52 through the elongated hole 54 of the fitting 52. As shown in FIG. 7, the elongated portion 54 is dimensioned so that there is a gap between it and the bolt 55 in the lead-lag direction A, and a slight gap in the radial direction. When the lead/lug angle reaches the required angle, bolt 55
The gap 54 comes into contact with the damper, and further deformation of the damper can be prevented. In addition, by making the radial gap between the bolt 55 and the gap 54 very small, even if the flexible member 6 is damaged due to some accident and it becomes difficult to transmit the load in the flap direction, the fitting 52) bolt 5
5 and the fitting 51, the load in the flap direction can be transmitted via the damper. Of course, the gap between fitting 51 and fitting 52 is 5.
It is also possible to provide the movement limiting mechanism in the lead/lug direction and the load transmission mechanism in the flap direction, which are constituted by the four bolts 55, separately from the damper. In addition, the lead
It is desirable that the movement limiting mechanism in the lug direction be provided as close to the spherical bearing 10 as possible. The reason for this is to reduce the load applied to the flexible member 6, which will be explained in detail below.

As shown in FIG. 9, in the upper and lower parts of the pitch housing 4, a protrusion 71 that projects outward is formed at the radially outer end of the inner end 5, and a notch is formed at the radially inner end of the outer end 7. A recess 72 is formed to form a movement limiting mechanism in the lead/lug direction. When an excessive load in the lead-lag direction is applied to the rotor blade 11, a movement limiting mechanism in the lead-lag direction is activated, and a load P acts on the protrusion 71 of the inner end portion 5. This load is applied to the flexible girder 2 of the hub via the spherical bearing 10.
The shear force of the spherical bearing 10 is transmitted as a shear force of the spherical bearing 10.
There remains a rotational moment around the load P1 multiplied by the distance e. This moment generates a tensile force P3 in the front flexible member 6 and a compressive force P4 in the rear flexible member 6. Since the flexible member 6 has a lower rigidity in the lead/lug direction, buckling may occur when compressive force is applied, which is not preferable. In order to reduce the compressive force applied to the flexible member 6, the value of the rotational moment may be reduced, and the distance e may be reduced. That is, it is necessary to provide a movement limiting mechanism in the lead/lug direction as close as possible to the spherical bearing 10. Figure 10 shows
For this purpose, an example will be shown in which the distance e is set to zero so that no rotational moment is generated.

In this example, the damper fitting 52 fixed to the pitch housing outer end 7 is divided into upper and lower parts, and a cutout part 83 is formed at the lower inner end 181 of the damper fitting 52 . Through this notch 83, the shaft 82 of the spherical bearing 10 is fixed to the pitch housing inner end 5 with a pole 13. The gap between the notch portion 83 and the shaft portion 82 in the lead-lag direction is set to a size that allows the damper to move by a required lead-lag amount. As a result, the shaft portion 82 and the notch portion 83 constitute a lead/lug direction movement restriction mechanism, and the load applied to this restriction mechanism is directly transmitted to the bearing 10 via the shaft portion 82. , bending material 6
It is possible to avoid applying compressive force to the Furthermore, instead of the viscoelastic material 53, it is also possible to use a damper made of a friction plate.

As previously mentioned with respect to FIG. It can move radially within a range of 20. This is because as the vanes lead lug, the radial distance between the pitch housing inner and outer ends becomes slightly shorter, allowing the inner ends to move radially outward. Depends on need.

As shown in FIG. 2, the pitch housing inner end 5 is provided with a pitch arm 15, and the pitch arm 15 is connected to a swash plate of a known type via a pitch link 16 attached to its tip. (not shown) to receive the steering force. As is clear from FIG. 2, the distance between the spherical bearing 10 and the pitch link 16 is kept mechanically constant, so there is no risk of aerodynamic coupling.

Furthermore, since the spherical bearing 10 is directly fixed to the pitch housing inner end 5, the thickness of the pitch housing inner end 5 must be such that an appropriate clearance can be obtained between it and the flexible girder 2. It can be made thinner and lighter, making it easier to reduce weight.
And it is beneficial in reducing air resistance.

The pitch housing described above is sufficiently safe against damage. For example, even if one of the flexible members 6 breaks and loses its load-bearing capacity, sufficient safety is guaranteed. In other words, since the damper 17 has the ability to transmit load in the flap direction, the torsional strength and torsional rigidity essential for controlling the rotor blades are maintained.
As shown in the figure, a steering torque h can be generated by a pair of couple e and flg. One couple component e
is transmitted by the flexible member 6 that remains undamaged, and the other couple component, g, is transmitted by the upper and lower lead-lag dampers 17, respectively. The damper with the viscoelastic body 53 is sufficiently soft in the shear direction (lateral direction), but stiff in the vertical and thickness directions, so it not only transmits force but also has torsional rigidity as a pitch housing. This is sufficient, and unstable phenomena such as flutter do not occur.

Regarding the bending force in the flap direction, as shown in FIG. The shear force component m is the flexible material 6
transmitted by. As explained in Fig. 10, the force in the cord direction can be supported without the front and rear flexible members, but the lead/lag/damping necessary to prevent ground resonance and air resonance cannot be supported by the flexible members. If one of the parts 6 breaks, the inner end 5 of the pitch housing will rotate and the lead-lag damper will no longer work, resulting in insufficient operation.

However, ground resonance and air resonance in a helicopter are the interaction of the four rotor blades, and each lead-lag-damper is mounted with sufficient margin to prevent such instability. Therefore, even if the damper attached to one rotor blade runs out, the dampers of the remaining three rotor blades can usually sufficiently prevent the problem.

The above discussion has been about the destruction of the flexible member, which is the weakest structural part of the pitch housing, but even if one lead lug damper were destroyed, it would be safe for the reasons mentioned above. Also, the rest of the pitch housing is
Since it has a large cross-sectional shape and low stress, there is no problem in terms of strength and rigidity even if partial damage occurs. The pitch housing described above has fail-safe properties against unexpected damage, is structurally reliable, and is said to be equipped with the most important elements for aircraft. be able to.

Note that the flexible member 6 is desirably made of a composite material with high fatigue strength, and in practice, it is also preferable that the flexible member 6 be molded integrally with the pitch housing. An example of such integral molding is shown in FIG.

In this example, the rotor blades and the inner end of the pitch housing are also integrally molded. As mentioned above, the present invention is characterized in that the flexible material provided at the center of the pitch housing deforms in the front and rear parts of the rotation direction, but in order to achieve this effect, the other parts must be deformed as much as possible. It is desirable that it be rigid and not deformed.

If the connection between the pitch housing and the rotor blade is a bolt connection, play at the connection cannot be avoided, and this play has the effect of apparently reducing the rigidity of the packed portion. As a result, the rotor blades
During lug movement, in addition to the flexure girders and flexures, the rotor blades and pitch housing mounting portions also undergo apparent deformation in accordance with the amount of play, reducing damping.

In order to prevent this, it is preferable to integrally mold the rotor blades and the pitch housing as shown in Figure 13. This also reduces the number of parts and eliminates the need for complicated machining of the joints, thereby reducing costs. It is possible to measure the reduction of Such integral molding can be easily realized using recent composite material technology.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of essential parts of a rotor blade according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line a-a in FIG. 1, and FIG. 3 is a cross-sectional view taken along line b-b in FIG. , FIG. 4 is a sectional view taken along the line C-C in FIG. 1,
Figure 5 is a plan view of the rotor blades when they are in lead-lag motion;
Figure 6 is a plan view showing the function of the pitch housing flexure, Figure 7 is a perspective view of the lead lug damper, and Figure 8 is a perspective view of the lead lug damper.
The figures are a perspective view showing the deformation of the pitch housing flexible member when a torsional moment is applied to the pitch housing, Fig. 9 is a plan view showing the function of the lead-lug direction shear movement limiting mechanism, and Fig. 10. 11 is a perspective view showing an embodiment of the lead/lug direction movement limiting mechanism; FIG. 11 is a cross-sectional view showing the transmission of steering force when one of the flexible portions is broken; and FIG.
The figure is a perspective view showing the flapping reaction force, and FIG. 13 is a perspective view showing one implementation in which the pitch housing is integrally molded. 1... Rotating shaft 2... Deflection girder 4... Pitch housing 5... Pitch housing inner end 6...
・Pitch・Housing flexible material 7・・・・Pitch・
Housing outer end 10... Spherical bearing 11... Rotor blade 16... Pitch link 17... Lead lug damper 100...
...Rotor hub structure Fig. 5 Fig. 1 Fig. 8 7. −7'

Claims (6)

[Claims] (1) Consisting of a hub body fixed to a rotating shaft, a plurality of deflection girders provided on the hub body and extending in the radial direction, and a pitch housing arranged to surround the deflection girders at intervals, In a rotary wing hub structure for a rotary wing aircraft, in which the spar is provided with a flexible portion having low bending rigidity at least in the lead lug direction, the pitch housing has an inner end portion disposed radially inward and a radially inwardly disposed flexible portion. an outer end portion disposed outward in the radial direction, the inner end portion being supported by the hub body via a spherical bearing near the radially inner end portion of the flexible girder, and the outer end portion being a flap with low rigidity in the lead/lug direction, which is rigidly fixed to the inner end, and the inner end and the outer end are provided at the front and rear of each other in the rotational direction so as to sandwich the flexible girder; The rotation is characterized in that the inner end portion and the outer end portion are connected by a lead lug damper at upper and lower positions of the flexible girder. Wing hub structure. (2) The hub structure according to claim (1), characterized in that the inner and outer ends of the pitch housing and a flexible member that connects the two are integrally molded. (3) The hub structure according to claim (1) or (2), wherein the flexible member of the pitch housing has an I-shaped cross section. (4) In claim (1) or (2), when the deflection of the flexible member of the pitch housing reaches a predetermined value, the inner end and the outer end are coupled so as to transmit a pressing load. A hub structure characterized in that a support element is provided. (5) In claim (1) or (2), the pitch housing inner end portion and outer end portion have a mounting portion having an elongated hole in the lead lug direction at the upper and lower positions thereof, and a mounting portion having an elongated hole in the lead lug direction. A hub structure characterized in that the hub structure is connected to each other by inserted bolts such that they are movable in the lead/rack direction but not movable in the flat tip direction. (6) The hub structure according to claim (5), wherein the mounting portion and the lead lug damper are integrally molded.