JPH0229560B2 - MUKANSETSUGATAKAITENYOKU - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an unarticulated rotary wing for use in a rotorcraft.

In recent years, rotor blade hubs have been manufactured using fiber-reinforced composite materials with high fatigue strength, and jointless rotor blades that allow rotor blade pitch changes, flap movements, and lead-lag movements by bending and torsional deflection of the hub arms. is being developed. The well-known forms of such rotary blades are roughly as follows. In other words, a hub fixed to a rotating shaft is provided with the same number of arms in the form of flexible girders with a nearly rectangular cross section as the rotor blades, and these are arranged at equal intervals in the radial direction. Attach rotor blades rigidly to the outer end. This flexure girder exhibits very large flexibility against torsional and vertical bending deflections in order to accommodate pitch changes and flapping deviations of the rotor blades, while it exhibits very large flexibility in the plane that causes lead-lag movement of the blades. Adjusted to exhibit small flexibility. By the way, in the case of the main rotor blade of a helicopter, in order to provide the necessary flexibility, the deflection spar needs to be extremely long, reaching more than 30% of the radius of the rotor blade. For comparison, in a fully articulated rotor blade, the hub is approximately 10% of the rotor radius. To provide the desired pitch variation in the rotor blades located at the outer ends of the long flexure spar, pitch housings in the form of long, bending and torsionally rigid torque tubes are provided surrounding the flexure spar. The pitch housing is fixed at its outer end to the rotor blade, and its inner end is connected to the flexure spar inside the pitch housing via a spherical bearing with an elastomer damper for centering the flexure spar, and A pitch horn provided outside the inner end is connected to the swash plate via a pitch link.

By the way, when a non-articulating rotor blade is used as the main rotor blade, it is desirable to install a lead lag damper in order to dampen the instability of the blade, but as mentioned above, the lead lag movement of the blade is caused by the deflection deformation of the flexure girder. However, since the deflection occurs gently over the entire length of the long girder, it is difficult to determine the effective mounting position of the damper, and since the circumference of the deflecting girder is wrapped in a long pitch housing, it is even more difficult to install a lead-lag damper. It becomes difficult to find a place. In addition, there is a problem of so-called "pitch-lag coupling" in which the lead-lag motion of the blade affects the pitch angle of the blade and changes the pitch angle. One solution to these problems has been proposed in Japanese Patent Application Laid-open No. 89200/1983.
This structure uses the relative displacement between the pitch housing and the flexible girder caused by lead-lag motion to operate the damper, so the damper is forced to be installed between the inner end of the pitch housing and the root of the flexible girder, and There is an inconvenience that the vicinity of the rotating shaft attachment part of the girder becomes particularly complicated due to the concentration of many parts. In addition, in order to separate the lead-lag motion from the pitch motion, the sphere of the centering spherical bearing is divided into upper and lower halves and placed separately on the upper and lower surfaces of the flexible girder. On the other hand, since it is configured to perform double sliding on a spherical surface, this centering bearing not only has a complex structure, but if the centers of both hemispheres are not aligned, there is a risk of uneven wear or seizure. , very precise positioning of the hemisphere is required. Furthermore, the sliding surfaces of the hemisphere and the flexible girder must be flat and parallel, and the spacing between them must be extremely precise. Such centering bearings naturally have the disadvantage that they are very expensive. In addition, when a large load is applied to this bearing in the lead-lag direction, the outer race of the bearing receives a force that is pushed out in the vertical direction due to the wedge effect, so an extremely rigid pitch housing is required to support this. This greatly increases the weight of the pitch housing. Furthermore, in order to secure the swing angle of a spherical bearing, it is necessary to increase the dimensions of the sphere in proportion to the plate thickness of the flexure girder, which leads to an increase in the size of the bearing and, therefore, the width of the flexure girder. The disadvantage is that it imposes restrictions on the dimensions of the

In general, a rotary wing is a device that is difficult to design because it compiles requirements from various aspects such as aerodynamics, aeroelasticity, fatigue strength, and vibration, and is similar to the main wing of a fixed-wing aircraft. It is an important part that determines all the maneuvering characteristics of a rotary wing aircraft, and the thickness and width of the deflection girder are particularly important near the rotary shaft attachment part. Therefore, it is desirable to have a structure in which secondary requirements such as constraints from the structure of the centering bearing and constraints from the mounting position of the damper are not added to the design conditions of the flexible girder.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a non-articulated rotor blade that has a wide range of damper attachment positions and can avoid pitch-lug coupling with a centering bearing having a simple structure.

That is, the jointless rotor blade according to the present invention includes a rotating shaft and a hub fixed to the rotating shaft,
The hub has a plurality of flexible girder members that extend radially and support rotor blades at the tip, and pitch housings are provided to surround the flexible girder members at intervals, and the pitch housings are arranged at outer ends. is in a rigid relation to, or integrally or rigidly connected to, the inner end of the rotor blade, the inner end being flexible in the torsional direction and rigid in the lead-lag direction by a spherical bearing on the hub. The pitch housing has a flexible portion having low bending rigidity in the lead-lag direction, and the pitch housing can be bent in accordance with the lead-lag movement of the rotor blade at the flexible portion. shall be.

In the present invention, the pitch housing is provided with a flexible portion having low bending rigidity in the lead-lag direction, and the pitch housing is configured to be able to bend in this flexible portion in accordance with the lead-lag movement of the rotor blade. Most of the deflection occurs only in this flexible section, and if a damper is provided across this section, the effect of damping the lead-lag motion can be sufficiently exerted. Furthermore, various methods can be used to determine the position of the flexible portion and to reduce the rigidity, which is very advantageous in terms of design.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, in FIGS. 1 to 6, the rotor blade has a hub 1 fixed to the upper end of the rotating shaft 6, and the hub 1 is integrally formed with flexible beam members 5 extending in the radial direction at 90° intervals. has been done. Deflection girder member 5
As is clear from the figure, is a plate spring shape with a rectangular cross section that is flat in the horizontal direction, and is easily deflected in the vertical direction, that is, the flap direction, and is relatively rigid against deflection in the rotational direction, that is, the lead-lag direction. . Further, this flexible girder member has relatively low rigidity against torsion.

A hollow pitch housing 103 is arranged on the outside of the flexible girder member 5 and spaced apart from the member 5. As shown in FIG. 7, the pitch housing 103 has a hollow cylindrical shape as a whole, and has a large notch 3 near the inner end facing forward and backward in the rotational direction.
7 and 38 are formed. This notch 37,3
8 is the outer part 103a of the pitch housing 103.
and an inner part 103b, and an outer part 1
03a and the inner part 103b have cutouts 37, 38
They are connected by two upper and lower connecting parts 83 and 84 left behind. As shown in FIG. 7, the connecting portions 83 and 84 have a substantially rectangular cross-sectional shape that is long in the vertical direction.
Although it can be relatively easily bent in the lead lug direction at these notches 37 and 38, it maintains sufficient rigidity against torsion, so that it can fully serve its purpose as a pitch housing.
A portion of pitch housing 103 having these notches 37 and 38 forms a flexible portion with low bending rigidity in the lead-lag direction. Ear fittings 134 and 135 for attaching a lead lug damper are formed on the outer part 103a and the inner part 103b with the notch 38 in between, and the pitch horn 13 is formed on the inner part 103b.
6 is formed. In the structure of this example, the connecting portion 8
3 and 84 are subjected to large bending stress, it is preferable to manufacture the pitch housing from a composite material with high fatigue strength, and in that case, the blades are installed at the connection part so that the direction of the fibers is in the direction of the bending stress. Preferably, they are arranged in the longitudinal direction. This structure does not use a hinge mechanism, so there are drawbacks to the hinge mechanism, such as wear and play, and the need for maintenance and inspection.
There are no problems such as a large number of parts,
There is an advantage.

The outer part 103a of the pitch housing 103 is
At its outer end, on the one hand, the flexible girder member 5;
On the other hand, it is rigidly connected to the inner end of the rotor blade 2. Therefore, the flexible girder member 5 is connected to the blade 2 via the outer part 103a of the pitch housing 103.
is rigidly coupled to. The inner member 103b of the pitch housing 103 is supported by the flexible girder member 5 via the spherical bearing 7 at its inner end. That is, as shown in FIGS. 2 and 3, the flexible girder member 5
An opening 51 is formed at the inner end of the opening 51.
A support shaft 71 is fixed to the flexible girder member 5 so as to protrude, and a spherical bearing member 72 is supported on this support shaft 71. A support member 74 having a spherical seat 73 at its inner end is attached to the inner member 32 of the pitch housing 3, and is supported by a bearing member 72 at the seat 73. Therefore, the inner end of the pitch housing 3 has a flexible girder member 5 in the lead lug direction and the flapping direction.
The flexible girder member 5 is rigidly supported and rotatable about the longitudinal axis of the flexible girder member 5.

A lead-lag damper 4 is arranged between the outer part 103a and the inner part 103b of the pitch housing 103. That is, the outer part 103a is formed with a mounting ear fitting 134, the inner part 103b is formed with a mounting ear fitting 135, and the clevis fittings 41, 42 at both ends of the lead lug damper 4 are attached to these ear fittings 34, 35. It will be done. Further, a pitch horn 136 is formed near the inner end of the inner portion 103b of the pitch housing 3, and a pitch link 8 is connected to the pitch horn 136 to provide a steering force via a known type of swash plate (not shown). is now being given. Therefore, the steering force transmitted from the pitch link 8 is transmitted to the rotor blade 2 via the pitch housing 103, causing a pitch angle change to the blade 2 while causing twisting of the flexible spar member 5. In response to flapping caused by aerodynamic forces during flight, the inner end of the pitch housing 103 is supported by the spherical bearing 7, so the vertical deflection of the flexible girder member 5 is not restrained. Furthermore, with respect to movement in the lead-lag direction, the pitch housing 103 can be bent at the notches 37 and 38 forming the flexible portion, and the deflection of the flexible girder member 5 is not restricted. Further, since the bending of the pitch housing 3 at this time always occurs at the notches 37 and 38 constituting the flexible portion, the lead-lag damper 4 can provide a sufficient damping force against the lead-lag movement.

In this structure, there is a large degree of freedom in the mounting position of the lead-lag damper, and the rotor blade structure is also a simple structure, especially in the vicinity of the hub. Furthermore, considering the relationship between the lead-lag motion and the pitch angle motion, for example, in the case of the lug motion shown in FIG. 6, when the blade sweeps back angle α, the pitch housing 1
The inner part 103b of 3 rotates forward by an angle β around the spherical bearing 7, causing the pitch link 8 to tilt, but the inner part 32 at the attachment point of the pitch link 8 rotates forward by an angle β.
Since the amount of movement is small and therefore the inclination of the pitch link 8 is also very small, changes in the pitch angle of the blades 2 occur only to a negligible extent.

8 to 10 show another embodiment of the present invention, in which pitch housing 2 in this embodiment is shown.
03 has a wave-shaped flexible portion 204 near the inner end. As shown in the horizontal cross section in FIG. 9, this flexible portion 204 is formed only at the front and rear parts when viewed in the rotational direction.
The pitch housing 203 can be easily bent in the lead-lag direction. Further, as shown in the vertical cross section of FIG. 10, the wall thickness of the upper and lower parts of the flexible portion 204 is increased to increase bending rigidity in the vertical direction. The pitch housing 203 is provided with ear fittings 234 and 235 for attaching a lead-lag damper with the flexible portion 204 in between, and a pitch horn 236 is provided near the inner end. The structure of this example has the advantage that it is continuous within the structure and can be easily reduced in weight compared to each of the embodiments described above. Furthermore, there is no variation in plate thickness as a whole, making it suitable for manufacturing from composite materials. When the pitch housing of this embodiment is manufactured using a composite material, a torsion member 93 with the fiber direction oriented at ±45° with respect to the longitudinal direction is arranged around the entire circumference, and the upper and lower parts, as well as the lead-lag damper Mounting bracket 34
On the outer side of the blade in the longitudinal direction, also in the front and rear of the rotation direction,
It is preferable to arrange the bending members 94, 95 using unidirectional members. It is thought that it is good for this unidirectional material to have its fiber direction oriented in the longitudinal direction of the blade.

FIG. 11 shows an example in which another type of damper is used instead of the lead-lag damper 4, and as shown in FIG. 12, a rigid damper support member 40 with a U-shaped cross section
8 are notches 37 and 38 of pitch housing 103
One end is fixed to the pitch housing 103 on the outer side, and the other end is on the inner side of the notches 37 and 38,
The pitch housing 103 is adhesively bonded to the upper and lower surfaces of the pitch housing 103 via elastomer pieces 412 each having a rectangular cross section. Therefore, when the pitch housing 103 bends at the notch, a relative displacement occurs between the inner end of the damper support member 408 and the pitch housing, and the elastomer piece 412 produces a damping action. Furthermore, it is of course possible to install a damper between the inner end of the pitch housing and the hub, if necessary.

In addition, in the present invention, it is also possible to integrate the pitch housing and the hub including the blades, and it is also possible to divide or combine the hub at parts other than those shown in the embodiments. Furthermore, the present invention is fully applicable to tail rotors as well as main rotors.

Since the present invention is configured as described above, it has the following effects.

First, since the pitch housing bends at a desired position due to the lead-lag movement of the blades, it becomes possible to handle the problem of installing a lead-lag damper in the same way as in the case of a fully articulated rotor blade, and in particular, It is also possible to mount the damper without the use of a flexure spar, eliminating problems associated with damper mounting on unarticulated main rotors. In addition, since the inner part of the pitch housing simply swings around the centering bearing due to the lead lug movement of the blades, the centering bearing has a function that allows displacement in the lead lug direction as in the conventional case. is completely unnecessary, and therefore the structure of the centering bearing can be significantly simplified, and the change in pitch angle of the blade due to lead-lag motion can be made extremely small, completely ignoring the problem of pitch-lag coupling in non-articulated rotor blades. Become something you can do. As described above, according to the present invention, a practical unarticulated rotor blade having a simple structure and easy maintenance and inspection can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view of essential parts of a rotor blade according to an embodiment of the present invention, FIG. 2 is a perspective view showing details of the pitch housing, FIG. 3 is a cross-sectional view taken along line a-a in FIG. The figure is a sectional view taken along the line b-b in Fig. 2, FIG. 8 is a perspective view of a pitch housing showing another embodiment of the present invention; FIG. 9 is a horizontal sectional view of the pitch housing of FIG. 8; FIG. 10 is a vertical sectional view thereof; The figure is a cross-sectional view showing another example of damper installation, and Figure 12 is a line ee of Figure 11.
FIG. DESCRIPTION OF SYMBOLS 1... Hub, 2... Rotor blade, 3... Pitch housing, 4... Damper, 5... Flexible girder member, 6... Rotating shaft, 7... Spherical bearing, 31... Pitch housing outer part, 32... Pitch housing inner part, 71 ...Support axis.

Claims (1)

[Scope of Claims] 1. Consisting of a rotating shaft and a hub fixed to the rotating shaft, the hub has a plurality of flexible girder members extending radially and supporting the rotor blades at the tip, and having a plurality of flexible girder members spaced apart at intervals. A pitch housing is provided to surround the flexible girder member, and the pitch housing has an outer end in a rigid relationship with an inner end of the rotor blade and an inner end that is connected to a spherical surface on the hub. The pitch housing is supported by a bearing to be soft in the torsional direction and rigid in the lead-lag direction, and the pitch housing has a flexible portion with low bending rigidity in the lead-lag direction, and in this flexible portion, the pitch housing resists the lead-lag movement of the rotor blade. A non-articulated rotor blade that is characterized by being able to bend according to the 2. The jointless rotation type according to claim 1, wherein the pitch housing has a notch at the front and rear in the rotational direction in a part of the pitch housing, and the flexible portion is formed by the notch. Wings. 3. The pitch housing is made of reinforcing fibers and resin, and the fibers are arranged in the longitudinal direction of the blade in the connection portion left by the notch. Wings. 4. The invention as set forth in claim 1, wherein the pitch housing has a cylindrical shape and has wavy uneven parts at the front and rear in the rotational direction, and the flexible part is formed by the uneven parts. Articulated rotor blade. 5 The pitch housing is made of reinforcing fibers and resin, and the entire surface including the uneven portion is arranged with the fibers oriented at ±45° with respect to the longitudinal direction of the blade, and the upper and lower portions including the flexible portion are arranged in a band shape. The jointless rotor blade according to claim 4, characterized in that a unidirectional material is arranged, and the unidirectional material has its fiber direction directed in the longitudinal direction of the blade.