JPH0349799B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a rotor for a helicopter.

More particularly, the present invention relates to a rotor having an elastomeric flap bearing, a lead-lag bearing, and twin composite tension-torsion beams formed by curved continuous loops. This rotor is also unique in that it does not have pitch bearings.

BACKGROUND OF THE INVENTION Conventional systems for mounting and supporting the blades of rotorcraft, such as helicopters, are extremely complex. For example, in the case of fully articulated rotor blades, the blade is required to move through several different, but related, trajectories during rotation.

That is, each blade must flap in a conical or oblique manner about a horizontal axis relative to the rotor blades. Also, when changing the blade pitch, each blade must undergo a twisting or rotational movement about its longitudinal axis. Furthermore, the flap motion and air lugs caused by the rotation of the blades cause each blade to have a leading or lagging motion, with each blade moving in the horizontal plane at the point of attachment of the blade to the vertical axis. Have to move around slightly.

Furthermore, separate bearing assemblies are required for each of these movements. That is, conventional blade attachment/assembly methods require multiple lubricated bearings to provide the various motions of the blade. For example, conventionally, in order to attach a blade to a central rotor hub, lead/lug bearings,
Flap bearings and pitch bearings were required, as well as a torsion and tension strap for the fixed end.

However, these bearings require lubrication, so
A tank and piping for lubricating oil must be provided, and these bearings wear out each time the helicopter is operated, and oil leaks from the seal, making it necessary to constantly refill the oil tank. It was hot. Furthermore, there were other problems such as clogging of pipes. In order to ensure stable operation, these maintenance must be performed frequently, but such maintenance results in a large loss of time.

Furthermore, in the case of the conventional type rotor described above, a heavy steel casting product or aluminum casting product is used as the housing for the roll bearing or ball bearing of each of the above-mentioned lubricated bearings. However, the overall dimensions of the central rotor hub device are
Due to the required dimensions of the bearings and oil tank, the conventional type of rotor described above has a large central rotor hub cross-sectional area and also has a large detrimental drag force. This increase in drag means that more force must be applied to overcome it, resulting in less force being needed to move the aircraft.

The tension/torsion member of the above conventional method is
It is constructed from a steel laminate that is capable of twisting and bending while at the same time transmitting centrifugal forces from the blade mounting housing to the central rotor hub. However, attempting to provide the desired amount of blade pitch movement with this construction would result in additional weight, larger overall dimensions, and increased drag. Furthermore, the connection points of the tension-torsion members are subject to large stresses, which require periodic inspection.

In conclusion, the conventional central rotor hub and blade mounting assemblies described above are complex, heavy, require frequent maintenance and inspection, and suffer from high detrimental drag forces.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low drag center rotor hub for a helicopter.

Another object of the invention is to provide a central rotor hub with bearings that do not require lubricating oil.

Yet another object of the present invention is to curve an endless belt made of one composite material to have two inwardly curved parts and two outwardly curved parts to support the centrifugal force of the rotor. It is an object of the present invention to provide a central rotor hub assembly using a tension torsion member (hereinafter referred to as a curved tension torsion belt; however, the term belt is intended to include any endless loop-like member).

Still another object of the present invention is to eliminate pitch changing bearings.

Still another object of the present invention is to provide a central rotor hub assembly that utilizes elastomeric flap hinge bearings and elastomeric lead and lug bearings.

SUMMARY OF THE INVENTION As detailed in the preferred embodiments of the present invention below, the curved tension torsion belt rotor apparatus of the present invention has a curved central portion for supporting the centrifugal force of the rotor. It includes a curved tension-torsion belt made of composite material constructed of continuous loops. The curved tension torsion belt has its inwardly curved portion wrapped curved in a vertical plane around a flap hinge whose axis is generally horizontal, and from which it extends radially outwardly from its outwardly curved portion. is curved and wrapped in a horizontal plane around a vertical hinge pin forming an axis for folding the lead lug and blade.

OPERATION All of the necessary articulation provided by prior art metal center hub constructions is provided by the curved tension and torsion belt rotor arrangement of the present invention. That is, since the curved tension/torsion belt constituted by the above-mentioned curved endless loops is made of a flexible material, pitch movement of the blades is possible, and pitch bearings are not required. . Eliminating this pitch bearing and its associated housing substantially reduces the size of the central hub and reduces detrimental drag.

Furthermore, the present invention does not require flap bearings, lead/lag bearings, folding bearings, or pitch arm bearings that require lubrication; in other words, dry bearings can be used. By changing to these bearing structures, the dimensions of the housing can be further reduced and maintenance can be facilitated, thereby increasing the actual operating time.

The curved tension and torsion belt rotor arrangement of the present invention allows for a 50% reduction in central rotor hub cross-sectional profile and deleterious drag when compared to prior art constructions. Furthermore, by eliminating multistage bearings and pitch bearings, maintenance and inspection problems such as oil leakage and seal damage are eliminated, improving reliability. Additionally, the curved tension and torsion belt rotor device of the present invention eliminates the need for steel lamination packs, thereby increasing durability, thereby reducing overall weight and ease of maintenance. . Furthermore, the curved tension and torsion belt rotor device of the present invention is easy to design, so the total number of parts is greatly reduced and the structure is extremely simple.

While the novel features of the curved tension and torsion belt rotor arrangement according to the invention are set forth in the claims, to aid in a thorough understanding of the invention, reference will now be made to the accompanying drawings in which the invention will be described. A preferred embodiment will be described.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, there is shown a preferred embodiment of a curved tension and torsion belt rotor arrangement 10 according to the present invention applied to a three-blade helicopter.

As can be seen from Figure 1, three blades 12
is fixed to the central rotor hub and is adapted to rotate with the central rotor hub 14 when the central rotor hub 14 is driven by the drive shaft 16 . The drive shaft 16 is rotated by the helicopter's engine.

In the present invention, each blade is connected to a central rotor hub 1.
It is secured to the central rotor hub 14 by a horizontal flap hinge 18 supported at 4 and a tension torsion member 20 comprising a curved tension torsion belt. Each blade also has a suitable folding actuator/lead lug absorber 22, as is generally known.

As is known, in operation, each blade 12 is rotated by the drive shaft 16 and undergoes multiple movements in various directions. As will be explained in detail below, the curved tension and torsion belt rotor system of the present invention has a drag angle and number of parts that are much smaller than the rotor systems of prior art machines, and the above-mentioned complex components are applied to each blade during rotation. Moreover, complex movements can be performed, and the number of maintenance operations can be significantly reduced.

Reference is now made to FIGS. 2 and 3, which illustrate in detail the curved tension and torsion belt rotor arrangement of the present invention for a single blade.

A central rotor hub 14 is supported by a drive shaft 16 and is secured thereto by a hub nut 24 in a conventional manner. The central rotor hub 14 is a generally planar member and, in the preferred embodiment shown, includes three sets of spaced apart mounting supports 26. These three sets of mounting supports 26 are identical and equally spaced around the central rotor hub 14. Each mounting support 26 is comprised of three legs 28, 30 and 32 that project outwardly apart from each other, between legs 28 and 30 and between legs 30 and 32.
Spaces 34 and 36 are provided between them, respectively. The three legs 28, 30 and 32 are formed with coaxial bores in which a flap hinge pin 38 is housed, surrounded by an elastomeric flap bearing 40. There is. The flap hinge pin 38 extends through each leg 28, 30, and 32, and further through the gaps 34 and 36. The elastic flap bearing 40 is arranged in legs 28, 3 so as to surround a portion of the flap hinge pin 38 in each leg.
Supported only by 0 and 32. The elastic flap bearing 40 is made of well-known materials, typically a multilaminate of rubber and metal that does not require lubrication. The flap hinge pin 38 is shown as a hollow body and is made of as light a metal as possible with the necessary strength. The horizontal flap hinge 18 described above is constituted by each mounting support 26 and a mounting 42 supporting the associated curved tension/torsion belt.

This fixture 42 is shown in detail in FIGS. 6 and 7. The fixture 42 has a pair of inwardly extending legs 44 and 46 that are received in the spaces 34 and 36 described above. A hole 48 is formed in the inner end of each leg 44, 46, and the flap hinge pin 38 described above extends through the hole 48.
The aperture 48 in each leg 44, 46 is sized to accommodate the flap hinge pin 38, but not the resilient flap bearing 40.

As is clear from FIG. 4, each mounting support 2
The outer end surface of the central leg 30 of 6 has a convex shape, and this convex surface 50 has the above-mentioned leg 44,
fittings 42 extending inwardly between 46;
are opposed by concave surfaces 52 . These two surfaces 50 and 52 cooperate with each other to form a joint around which the blade 12 can flap or pivot vertically during operation. There is. The center of rotation of this flap movement is the flap hinge pin 38.
is the horizontal axis of

Also, as is clear from FIG. 4, the droop stop pin 54, which is actuated by centrifugal force, is supported by the fixture 42. The droop stop pin 54 is cylindrical and is housed in a suitable bore 56 formed in the leg 30. This bore 56 opens towards the concave surface. When the helicopter is stationary, blade 12
is kept substantially horizontal by a droop stop pin 54. On the other hand, during operation, when the central rotor hub 14 and the blades 12 rotate, the droop stop pin 54 is moved by centrifugal force against the force of the coil spring 58 held by the cover plate 60. It is moved radially outward to a position such that it exits the bore 56. As a result, the blade 12 is allowed to pivot up and down about the horizontal axis of the flap hinge pin 38.
Lower outer portion 62 of said convex surface 50 of leg 30
and the lower inner portion 64 of the concave surface 52 of the fixture 42 are generally planar and spaced apart to provide an in-flight drop loop stop for the blade 12 relative to the central rotor hub 14 during flight.

The pitch of the blade 12 is 2nd, 3rd, 4th and 5th.
It is controlled by a pitch arm 66 that constitutes a blade pitch changing lever shown in the figure.
The pitch arm 66 is rotated about its second end 70 by connecting a first end 68 of the pitch arm 66 to a swash plate (not shown) via a pitch link (not shown) in a known manner. be able to. As shown in FIG. 4, this second end 70 has a dry bearing 72 that is fitted into a bearing housing 74 formed at the lower outer edge of the fixture 42 that supports the curved tension/torsion belt. is supported by The preferred embodiment of this dry bearing 72 is a metal sleeve coated with a Teflon-impregnated woven fabric. As is clear from FIG. 2, the rotation of the pitch arm 66 by the swash plate is transmitted to the pitch clevis 78 via the torque tube 76. As is known,
When changing the pitch of the blade 12, the pitch clevis 7 is changed via the torque tube 76.
Rotate 8.

The folding actuator/lead lug absorber 22 is best shown in FIGS. 2 and 3. Folding the blade 12 about a folding pin 82 having a vertical axis is desirable, such as when storing a helicopter. This folding pin 82 also serves as a rotor blade fixing pin.
When folding the blade 12, a hydraulic cylinder 84 that serves as a folding actuator and part of the lead/lug absorber 22 can be used. The inner first end 8 of this hydraulic cylinder 84
6 is pivotally mounted to a mounting plate 88. 6th
As shown, the mounting plate 88 is secured to the fixture 42 by four spaced apart bolts 90.
It is bolted to the rear side of the Each bolt 9
0 is a screw hole 9 drilled in the rear side of the fixture 42 that supports the curved tension/torsion belt.
It is screwed together with 2. A second outer end 94 of the hydraulic cylinder 84 is secured to an actuator arm 96 of a blade folding ring 98 . Blade folding ring 98 is connected to blade 12 such that blade 12 pivots about folding pin 82 in a generally horizontal plane when hydraulic cylinder 84 is extended. When the helicopter is in operation, this hydraulic cylinder 84 compensates for the minute horizontal (in-plane) movements of the blade 12 caused by acceleration and deceleration, as well as the frictional forces of air on the blade as it rotates. Acts as a lead/lag absorber. In the conventional technology, when each blade rotates and performs various movements such as the above-mentioned flap movement, pitch movement, and lead-lag movement, a bearing suitable for handling these complex movements is required. It was hot. However, as already mentioned, in the curved tension-torsion belt type rotor device of the present invention, these movements are doubled in the inwardly curved portion and the outwardly curved portion, as can be seen from FIGS. It is provided by a curved tension torsion belt 20 constructed of composite material attached.

The composite curved tension torsion belt 20 is made of unidirectionally aligned glass fibers, such as Kevlar or graphite, held together by a suitable binder (resin matrix). An endless loop curved composite belt made of flexible material. As can be seen in FIGS. 2 and 3, the inwardly curved portion 10 of this curved tension torsion belt 20
0 through the gaps 34, 36 to the outer circumferential surfaces 20a, 20b of the circular thin-walled portion 102 around the holes 48 of the legs 44 and 46 of the fixture 42 supporting the curved tension torsion belt. It is hung. On the other hand, the outwardly curved portion 104 of the curved tension/torsion belt 20 is wrapped around circular groove portions 106 formed at the outer end of the clevis 78 and spaced apart from each other in the vertical direction 20c and 20d. The above-mentioned folding pin/rotor blade fixing pin 82 passes through the center of the circular groove portion 106 of this clevis 78.

The curved tension/torsion belt 20 extends between the curved portions 100 and 104 at both ends along a groove 110 formed in a fairing 112 (FIG. 5) and a groove 108 in the legs 44 and 46. It is extending.

Therefore, for example, when the blade 12 flaps during flight, the elastic flap bearing 4
A flap movement is performed around the flap hinge pin 38 via the bending tension torsion belt 2 as the blade 12 pitches.
0 rotates and twists. Additionally, as the blade leads or lags about the vertical folding pin 82, this lead-lag motion is absorbed by the absorber 22 and counteracted through the mount 42. Generally, the above-mentioned movements of the blade all occur at the same time and change with each revolution of the blade, so that the curved tension-torsion belt 20 is in continuous motion. However, by appropriately selecting the material of the curved tension/torsion belt 20,
These movements experienced by the beam 20 during rotation of the blades 12 may ensure that the curved tension torsion belt is not adversely affected.

Effects of the invention As already mentioned, the horizontal flap hinge pin 3
8, the elastic bearing 40, the pitch arm 66, its dry bearing 72, and the curved tension/torsion belt 20, it is possible to eliminate the need to use conventional roller bearings and lubricating oil. No central rotor hub arrangement can be constructed. By adopting such a structure, the weight of each component is significantly lighter than that of conventional roller bearings, oil tanks, and housings, and the dimensions of the housing are also surprisingly small. Accordingly, the durability and reliability of the central rotor hub arrangement can be increased while weight and deleterious drag can be substantially reduced.

Although the preferred embodiments of the curved tension/torsion belt type rotor device of the present invention have been described above, the present invention is not limited thereto and can be modified in various ways. For example, the material of the bearing, the material used to construct the double-wound curved tension/torsion belt, the number of blades, the structure of the reed/agu absorber, etc., are within the spirit and scope of the invention. It will be apparent to those skilled in the art that various modifications may be made without departing from this. The invention is limited only by the scope of the claims.

[Brief explanation of drawings]

FIG. 1 is a conceptual perspective view showing the entire curved tension/torsion belt type rotor device of the present invention, with some parts removed for clarity. FIG. 2 is a plan view of the curved tension and torsion belt type rotor device of the present invention, with some parts removed for clarity. FIG. 3 is a side view of the curved tension/torsion belt type rotor device taken along line 3--3 in FIG. 2. 4 is a side view of the flap hinge and tubular pitch bearing of the curved tension and torsion belt rotor apparatus of the present invention taken along line 4--4 of FIG. 2; FIG. FIG. 5 is a cross-sectional view of the curved tension torsion belt rotor apparatus of the present invention taken along line 5--5 in FIG. FIG. 6 is a side view of a fixture supporting the central curve of the curved tension-torsion belt of the present invention. FIG. 7 is a plan view of the fixture of FIG. 6. (Main reference number), 10: Curved tension/torsion belt type rotor device, 12: Blade,
14: Center rotor hub, 18: Horizontal flap hinge, 20: Curved tension/torsion belt,
22: Folding actuator/lead lug absorber, 26: Mounting support part, 28, 3
0, 32: Mounting support leg, 38: Flap hinge pin, 42: Fixture, 44, 46: Fixture leg, 66: Pitch arm, 76: Torque tube, 78: Clevis, 82: Rotor blade fixing Pin and folding pin.

Claims (1)

Claims: 1. A central rotor hub 14 with at least two mounting supports 26, each of which includes a plurality of adjacent legs 28, 30, 3.
2, each leg 28, 30, 32 has a hole formed therein, each mounting support 26 has a respective fixture 42 attached thereto, and each fixture 42 has a plurality of adjacent legs. Each of the legs 44, 46 has a hole 48 formed therein, and the holes in the legs 28, 30, 32 of the mounting support 26 and the holes in the legs 44, 46 of the fixture 42 are connected to each other. 48 are aligned with each other, a flap hinge pin 38 is received in these holes to form a flap hinge, and each fixture 42 has a blade pitch changing lever 6.
A clevis 78 is connected to this blade pitch changing lever 66, and a rotor blade fixing pin 82 which also serves as a folding pin is pivotally connected to the other end of this clevis 78. Each fixture 42 and each rotor blade fixing pin 82
An endless tension/torsion belt 20 is stretched between the two. The two inwardly curved portions 100 are curved to have two mutually spaced legs 4 of the fixture 42.
A rotor for attaching a rotor blade 12 to a helicopter, characterized in that the two outwardly curved portions 104 are hung around the upper and lower ends of the rotor blade fixing pin 82. Device. 2 One leg 30 of each mounting support 26 has a convex surface 50, and a portion between two adjacent legs 44, 46 of each fixture 42 corresponds to said convex surface 50. A concave surface 52 is formed, and the combination of the convex surface 50 and the concave surface 52 forms a flap hinge about the axis of the flap hinge pin 38. The rotor device described. 3. A centrifugally driven droop stop pin 54' is supported in each fixture 42, and the droop stop pin 54' is a bore formed on the convex surface 50 of the mounting support 26. The rotor device according to claim 2, wherein the rotor device is pressed by a spring 58 toward the inside of the rotor device 54 . 4. One leg 30 of the mounting support 26 has a flat lower outer portion 62 in the lower extension of the convex surface 50, and the mount 42 has a lower inner surface flat in the lower extension of the concave surface 52. 3. A rotor arrangement according to claim 2, having a lower outer portion 62 and a lower inner surface 64 serving as an in-flight droop stop. 5. The two inwardly curved portions 100 of the tension torsion belt 20 rest on the outer circumferential surface of the circular thin-walled portion 102 around each hole 48 of the two adjacent legs 44, 46 of each fixture 42. The two outwardly curved portions 104 of the tension/torsion belt are hung over two upper and lower circular groove portions 106 formed at the other end of the clevis 78, and these two circular groove portions 106 are The rotor device according to claim 1, which engages with the upper and lower ends of a rotor blade fixing pin 82. 6 Two inwardly curved portions 100 and two outwardly curved portions 1 of the tension torsion belt 20
6. The rotor device according to claim 5, wherein the portion between 04 and 04 is accommodated in mutually parallel upper and lower grooves 110 formed in the fairing 112. 7. The upper and lower grooves 108 extend from each circular thin-walled portion 102 of the two adjacent legs 44, 46 of the fixture 42 so as to be aligned with the upper and lower grooves 110 of the fairing 112. The rotor device according to item 6. 8 Two mutually adjacent legs 4 of the fixture 42
8. The rotor apparatus of claim 7, wherein each of the circular thin-walled portions 102 of the clevis and each of the circular groove portions 106 of the clevis are oriented substantially perpendicular to each other. 9 A bearing accommodating portion 74 is formed in each fixture 42, and the blade pitch changing lever is a pitch arm 66 rotatably supported by a dry bearing 72 disposed in the bearing accommodating portion 74. The rotor device according to scope 1. 10. The pitch arm 66 is coupled to the clevis 78 via a torque tube 76, such that the motion of the pitch arm 66 is transmitted to the clevis 78 via the torque tube 76. rotor device. 11. The rotor device according to claim 1, wherein the tension/torsion belt 20 is made of unidirectionally aligned glass fibers. 12 The flap hinge pin 38 is connected to the plurality of mutually adjacent legs 28, 3 of the mounting support 26.
2. A rotor arrangement according to claim 1, wherein the rotor arrangement is surrounded by a resilient flap bearing (40) housed in each bore of 0.32. 13. The rotor device according to claim 1, wherein the folding actuator/lead lug absorber 22 connects the attachment 42 and the rotor blade fixing pin 82 which also serves as a folding pin. 14. The rotor device according to claim 13, wherein the folding actuator/lead/lug absorber 22 is constituted by a hydraulic piston/cylinder.