RU2808602C1 - Connection between pitch control rocker and blade rotary lever - Google Patents

Abstract

FIELD: aviation.

SUBSTANCE: invention is related to designs of helicopter tail rotors. The detachable connection between the rocker (5) of the pitch control unit and the blade rotation lever (8) of the blade holder (7) in the head (3) of the tail rotor (1) of the rotorcraft contains a pin connecting the blade rotation lever (8) attached to the holder (7) the blades with the rocker (5) of the pitch control unit (4) and passing through the through hole (50) of the rocker of the control unit and the other end through the through hole (80) of the blade rotation lever. The pin is made in form of a sliding pin (9) passing between the blade rotation lever (8) and the rocker (5) of the pitch control unit, and passes along its entire length through a ball-shaped spherical bearing (6) with a central through hole (61). The ball (6) and the sliding pin (9) portion are surrounded by an outer cage (60) of the spherical bearing so that the sliding pin (9) can slide and rotate within the spherical bearing.

EFFECT: ensures reduced material wear and simpler maintenance of the tail rotor head and the rotorcraft as a whole.

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Description

TECHNICAL FIELD

The present invention describes a detachable connection between a pitch control arm and a blade mount arm in a tail rotor head of a rotary-wing aircraft, comprising a pin connecting a blade arm attached to the blade holder to a pitch control arm by passing through a through hole in the assembly arm. pitch control and at the other end, through a through hole in the blade rotation lever, a tail rotor head of a rotary-wing aircraft, containing a pitch control unit with a plurality of pitch control unit rockers, with a plurality of blade holders connected to the tail rotor blades, with each blade holder connected to each lever of the pitch control assembly by connecting and using a sliding pin containing a pin locking washer, a castle nut and a threaded end with a spherical bearing, and a tail rotor for a rotorcraft.

BACKGROUND OF THE ART

US 7,604,460 discloses a helicopter tail rotor or tail rotor comprising a tail rotor head and a plurality of rotor blades attached by a corresponding rotor blade holder and torsion bars. Each of the propeller blade holders contains a blade rotation lever, which is to be connected to the pitch control unit rocker or control rod. As disclosed in US Pat. No. 7,604,460, the fixation uses a screw that extends between the blade rotation arm and the pitch control arm through a through hole in the blade rotation arm and the pitch control arm. The result is a rigid connection between the propeller and the blade turning arm to absorb centrifugal forces during operation, which means turning the tail rotor's axis of rotation. The through hole of the pitch control rocker actually moves in a special screw tip. It is a cylinder, i.e. bushing in the rocker of the pitch control unit for the ball, tip of the screw connection. As the pitch control assembly rotates the pitch control assembly rockers, and with them the blade rotation arms of each blade holder, the propeller is subjected to high forces, increasing the need for maintenance on this component. This screw can be considered a weak point of the fastening, requiring special attention. In practice, this propeller is already broken, so that uniform rotation of all blades is no longer guaranteed. Until now, this connection has not been given much importance. The spherical surface of the sleeve, fixed with a screw, experiences friction against the cylindrical surface of the pipe in the cross. This creates point or line contact causing severe wear.

Also, other prior art documents have not taken any special precautions to ensure a sufficiently stable connection between the blade rotation lever and the pitch control assembly rocker of the corresponding pitch control assembly. The result is a connection that is susceptible to mechanical damage and requires frequent maintenance for safety reasons. To make matters worse, maintenance, or replacement of the propeller between the blade steering arm and the pitch control assembly rocker, involves the removal of other parts and is still not a simple task, requiring extensive disassembly, including disassembly of the tail rotor.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a rotorcraft tail rotor head and an optimized connection between the pitch control rocker and the blade rotation lever of the tail rotor blade holder, thereby reducing material wear, reducing maintenance intervals, and achieving simplified maintenance of mechanically stronger components.

By introducing sliding pins and spherical bearings, easier maintenance of the tail rotor head and thus the rotorcraft can be achieved. To simplify and speed up maintenance work on the rotorcraft anti-torque device, a special type of sliding pin is provided.

No other components, such as propeller blades, propeller hubs or control spiders, need to be removed or disassembled for inspection or replacement of the sliding pin, which is accessible at any time from the outside of the tail rotor head or tail rotor hub.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention is described in detail below with reference to the accompanying drawings. Essential features, details and advantages of the invention will be apparent from the following description, which describes in detail the preferred embodiment of the invention and certain additional or optional features.

Options for combinations of features or minor changes to the invention can be found in the detailed description, illustrated in the drawings and included in the dependent claims. One skilled in the art will appreciate that any combination of features of the claims presented herein may be used.

In FIG. Figure 1 shows a general perspective view of the tail rotor with the tail rotor blades attached and the optional shroud removed.

In FIG. Figure 2a shows an exploded view of a tail rotor with the tail rotor head, tail rotor blade, blade holder, pitch control assembly, and torsion bar partially disassembled, while

In FIG. Figure 2b shows a partially cut-out perspective view of the tail rotor head and details of the connection between the blade steering lever and the pitch control arm.

In FIG. 3a shows part of the top view of the tail rotor head, and

In FIG. 3b is an enlarged top view with a partial cut-out of the connection between the blade holder and the pitch control assembly.

In FIG. 4a shows a side view of the blade rotation lever in various states, with the pitch control arm unattached in the background, while

In FIG. 4b shows another top view with a partial cut-out of the connection between the blade rotation lever and the pitch control unit rocker with a different sectional plane, and

In FIG. 4c shows a top view of the inside of the tail rotor head on the pitch control assembly, showing the indicated axes, angles, and displacements of the sliding pin relative to the pitch control assembly rocker that are possible during operation.

IMPLEMENTATION OF THE INVENTION

The rotor 1 of the rotorcraft is shown in FIG. 1 as an example of a tail rotor 1 without a common peripheral female casing located at a distance from the axis L of rotation. At the center of the tail rotor 1, a tail rotor head 3 containing a plurality of parts is shown. In this case, only the sleeve 10 is visible without the closing cap. A plurality of tail rotor blade holders are connected to the tail rotor head 3. The tail rotor blades 2 are directly connected to the blade holders and thus indirectly to the tail rotor head 3.

Exploded view of FIG. 2a shows the components of the propeller hub 3 in more detail, whereby in this case, by way of example, only one propeller blade 2 is shown mounted by one blade holder 7 on top of the tension and torsion torsion bar TT on the propeller hub 10 and the pitch control assembly 4. The tail rotor head 3 is at least formed by the hub 10, the pitch control unit 4, a plurality of TT torsion bars working in tension and torsion with the corresponding blade holder 7 and the tail rotor blades 2 attached later. During operation, the signal from the control system of the rotorcraft is transmitted through the unit 4 pitch controls and many rockers 5 pitch control units through holders 7 of the propeller blades to the blades 2 of the tail rotor. Each of the TT torsion bars, working in tension and torsion, is attached by one of their connecting ears to the bushing 10 and passes through a hole intended for it in the bushing 10. The bushing 10 provides support for a plurality of blade holders 7.

The pitch control unit 4 will be placed with partial passage inside the sleeve 10, leaving the pitch control unit rockers 5 open for connection with the tail rotor blade holder 7 part. The pitch control unit 4 also has holes or recesses so that the blade holder 7 can protrude in the radial direction.

Each blade holder 7 is configured to be connected to a TT torsion bar assigned to it, working in tension and torsion, and to a rocker 5 assigned to the pitch control unit 4. After attaching the blade holder 7 indirectly to the hub 10, the hub cap can be used to close the hub 10. A portion of the blade holder 7 protrudes from the hub 10. Each tail rotor blade 2 is secured with two bolts in its assigned blade holder 7, with at least one required bolt. The connection between the blade holder 7 and the sleeve 10 is achieved by means of TT torsion bars operating in tension and torsion.

Here, the blade holder 7 includes a torsion bar holding portion and a blade holding portion, which are molded together at a linear distance from each other. But the holder design can also be implemented in other ways. The TT torsion bar, which works in tension and torsion, is detachably connected to the blade holder 7. The connection between the blade holder 7 and the pitch control unit 4 is achieved by connecting the blade rotation lever 8 to each rocker 5 of the pitch control unit using at least one sliding pin 9 and a pin-locking washer 90, with the sliding pin 9 extending to the rocker 5 of the control unit . This connection makes it possible to subsequently pivot the blade 2, as indicated by the double arrow, around the axis of the blade, allowing rotational movements to be transmitted from the pitch control unit 4 to the blade holder 7. The washer 90 is optionally a removable component and can equally be formed integrally with the blade rotation lever 8.

In the partially cutaway view of FIG. 2b the assembled tail rotor head 3 is shown without the tail rotor blades 2. To reduce material wear, create stronger parts and increase service intervals, the disconnectable connection between the pitch control unit rocker 5 and the blade rotation lever 8 of the blade holder 7 is optimized, as described in more detail below.

To obtain a releasable connection, the sliding pin 9 is held by a spherical bearing containing a ball 6 in each rocker 5 of the pitch control unit. Each rocker 5 of the pitch control unit has a through hole 50 into which a spherical bearing in the form of a ball 6 with a through hole 61 and a ring-like outer race 60 of the spherical bearing are inserted.

This spherical bearing in another embodiment can also be placed in the through hole 80 of the blade rotation arm, whereby this solution should be understood in accordance with the solution described in this case.

In FIG. 3a shows a top view of the tail rotor 1 with a plurality of tail rotor blades 2 connected to the tail rotor head 3. And in FIG. 3b shows a top view with a partial cutout of the connection between the blade rotation lever 8 and the rocker 5 of the pitch control unit. As can be seen from the drawing, the blade rotation lever 8 is designed to be removably connected to the rocker 5 of the pitch control unit by means of a sliding pin 9.

The sliding pin 9 can be held by the pin-fixing washer 90 between the blade rotation lever 8 and the control unit rocker 5. The sliding pin 9 passes between these components through the through hole 80 of the blade rotation lever 8, passes through the through hole 61 of the ball in the spherical bearing 6 and exits the ball 6 towards the pitch control unit 4. The ball 6 is located centrally in the through hole 50 of the rocker and is surrounded in it by the outer race 62 of the spherical bearing. The outer ring 62 is fixed in the through hole 50 of the control unit rocker. Thus, the sliding pin 9 is installed in a detachable manner, completely intersecting the through hole 80 of the blade rotation lever and the through hole 50 of the control unit rocker.

On one side, the sliding pin 9 includes a threaded end 92 that can be effectively coupled to a nut 91, such as a castle nut 91, for attachment to a releasable pin connection. Through the pin release hole 93 provided in the sliding pin 9, a release pin connection can be made using a pin that is not shown in FIG. 3b. Also, a self-locking nut can be used instead of a 91 castle nut, since the latter often creates difficulty and time-consuming maintenance to install and remove the cotter pins required for 91 castle nuts.

The sliding pin 9, after it is fixed, can be rotated within a small range relative to the rocker 5 of the pitch control unit, as indicated by the double arrow. The sliding pin 9 and ball 6 may slide as the ball 6 moves along a first sliding surface 62 on the outer surface of the ball 6 that is in contact with the inner surface of the outer race 60 of the spherical bearing, resulting in swivel or rotational movement of the sliding pin 9 and ball 6 relative to the rocker. 5 pitch control nodes. The inner surface of the outer race 60 is a surface pointing to the center of the through hole 50 of the control unit rocker.

If a spherical bearing could be placed in the through hole 80 of the blade pivot arm, a similar hinged pivot motion would occur.

Due to the second sliding surface 63 on the inner surface of the ball through hole 61 and the outer surface of the sliding pin 9, the sliding pin 9 can linearly slide in the ball through hole 61 to a small extent in the direction of the longitudinal axis of the sliding pin 9. Axial movement of the sliding pin 9 inside the through hole 61 the ball is provided due to the centrifugal force pulling the rocker 5 of the pitch control unit. Sliding must be ensured because relative displacement between the pin and the ball occurs whenever yaw input is received from the pilot.

Sufficient fastening of the sliding pin 9 is always ensured. The sliding pin 9 cannot slip out of the through hole 80 of the blade rotation lever 8 and the through hole 50 of the rocker 5 of the pitch control unit after being fixed in this case using the described detachable pin connection.

The first sliding surface 62 between the ball 6 and the outer race 60 allows rotation in accordance with the swivel movement of the ball 6 in the outer race 60. Both parts, i.e. ball 6 and outer race 60 are components of a spherical bearing.

Instead of being placed on the outer surface of the sliding pin 9, the second sliding surface 63 may also be attached to the hole 61 in the spherical bearing ball 6. The second sliding surface 63 allows axial displacement between the sliding pin 9 and the ball 6 of the spherical bearing. The second sliding surface 63 may be integral to the sliding pin 9 or may be associated with or attached to the sliding pin 9. It may be a separate material, a fiber-reinforced matrix, a sintered material, or a substance applied to the outer surface of the sliding pin 9. A special friction agent must be used.

To accurately fit the sliding pin 9 to the blade rotation lever 8, in this case, a conical locking pin washer 90 was used, however, there are also other possibilities for matching the sliding pin 9. Fixation of the sliding pin 9 can be ensured by means of a corresponding external threaded end 92 and a nut 91, in In this case, the castle nut 91, while ensuring the possibility of linear movement of the sliding pin 9 relative to the ball 6 in the through hole 50 of the control unit rocker. The release pin prevents the castle nut 91 from coming loose.

The illustrated sliding pin 9 may comprise two tapered outer regions and a central thickened internal region in which a second sliding surface 63 is located, attached or formed. The cross-section of the sliding pin 9 in the two narrowed outer regions is smaller than in the central thickened inner region. It is also possible to design the sliding pin 9 with one narrowed outer region and a thickened outer region including a central region.

Below in FIG. 4 shows and explains in general terms the movement diagram of the blade rotation lever 8, the blade holder 7 and the sliding pin 9 inside the spherical bearing.

In use, when the pilot provides a yaw input signal, the signal is transmitted through the control system to the pitch control unit 4, which moves a distance Z. The direction of movement of the distance Z depends on the direction of the yaw signal. Since the pitch control unit 4 is connected through a sliding pin 9 to the blade rotation lever 8, which rotates freely around its axis C1, the blade holder 7 rotates or rotates through an angle α1 or α2, depending on the direction and amount of movement over a distance Z.

By rotating or turning by an angle α1 or α2, a displacement of the axis of the sliding pin 9 by a distance Y is induced. This also causes the pitch control unit 4 to rotate about its axis C2, which is the longitudinal axis L, as shown in FIG. 4c, generating a rotation angle β and a displacement X between the pitch control arm 5, i.e., thus between the ball 6 and the blade rotation lever 8 with the sliding pin 9 attached to the blade rotation lever 8.

The relative movement between the sliding pin 9 and the rocker 5 of the pitch control unit due to the spherical bearing and the sliding of the sliding pin 9 is implemented as follows:

The rotation through angle α1 or α2 is implemented on either of these two sliding surfaces: the first sliding surface 62 and the second sliding surface 63. The rotation or rotation β is implemented in the spherical bearing or ball 6 on the first sliding surface 62, while the displacement X is implemented on the second sliding surface 63. When rotating the pitch control unit 4 in the operating mode in FIG. 4c shows the rotation of the sliding pin 9 through a small angle β, which is less than 30°.

In FIG. 4c shows only rotation without axial displacement along the longitudinal axis of the pin. This axial movement must be free when this movement occurs. The prior art documents attempt to solve this problem by using parts that are flexible in this direction so as not to overload said parts by the forced displacement which is caused by the centrifugal force slightly pulling the blade 2 and also by the rotation of the blade holder 7 which changes the true distance from the propeller axis to the point of contact with a cross. The cross rotates slightly relative to the propeller hub when the blade pitch changes slightly.

The sliding surfaces 62, 63 are surfaces that provide sufficient sliding ability for the sliding pin 9 relative to the ball 6 or the outer race 60 or the through hole 61 of the ball. The sliding surfaces 62, 63 must be sufficiently prepared to provide antifriction properties. A coating may be used as the sliding surfaces 62, 63, or the material used has sufficient properties.

The sliding surfaces 62 and 63 should be special low-friction, high-wear surfaces, which may include, but are not limited to, the following: special low-friction coatings applied to at least one of the interacting moving parts; a liner (fiber-reinforced matrix) associated with or applied to at least one of the moving parts; a layer of plastic material or sintered material that can be mounted between the moving parts or associated with or applied to at least one of the moving parts.

The sliding surfaces 62 and 63 must withstand the loading pressure and must have a low coefficient of friction, with coatings or pairs of materials typically having coefficients of friction below 0.15 or preferably below 0.1. The advantage of the present invention is that the load is applied to a surface rather than a point/line, allowing a much wider range of coatings to be used. Expensive, complex and very hard coatings such as tungsten carbide are known and used in industry to withstand locally very high contact pressures, providing sufficient but suboptimal service life due to wear.

LIST OF ELEMENTS

1 - Tail rotor

2 - Tail rotor blade

3 - Tail rotor head

4 - Pitch control unit (transmitting a rotation signal relative to the vertical axis from the control system to head 3)

5 - Pitch control unit rocker

50 - Through hole of rocking chair

spherical bearing

6 - Ball (in the through hole of rocker 5 or lever 8)

60 - Outer race of spherical bearing

61 - Ball through hole

62 - First sliding surface

63 - Second sliding surface

7 - Blade holder

8 - Blade rotation lever

80 - Through hole of the blade rotation lever

9 - Sliding pin

90 - Pin washer/preferably conical washer

91 - Castle nut

92 - Threaded end

93 - Hole for disconnection with pin

10 - Bushing, part of the assembly (4), providing support for the holder (7)

C1, C2 - Axes

α1, α2 - Angles

X, Y, Z – Offsets.

Claims (18)

1. A detachable connection between the rocker (5) of the pitch control unit and the blade rotation lever (8) of the blade holder (7) in the head (3) of the tail rotor (1) of the rotary-wing aircraft, containing a pin connecting the blade rotation lever (8), attached to the blade holder (7), with the rocker (5) of the pitch control unit (4) by passing through the through hole (50) of the control unit rocker and at the other end through the through hole (80) of the blade rotation lever, characterized in that the pin is made in the form of a sliding pin (9) passing between the blade rotation lever (8) and the rocker (5) of the pitch control unit, which passes in the direction of its length through a spherical bearing made in the form of a ball (6), with a central through hole (61) in the ball, wherein the ball (6) and part of the sliding pin (9) are surrounded by the outer race (60) of the spherical bearing to allow sliding movement and rotary movement of the sliding pin (9) inside the spherical bearing. 2. A detachable connection between the rocker (5) of the pitch control unit and the blade rotation lever (8) according to claim 1, in which the first sliding surface (62) is formed on the outer ball surface and/or the inner surface of the outer race (60), and/ or the second sliding surface (63) is formed on the outer surface of the sliding pin (9) and/or the inner surface of the through hole (61) of the ball, thereby ensuring sliding movement along the first sliding surface (62) of the ball (6) relative to the outer race (60) and/or a second sliding surface (63) of the sliding pin (9) relative to the through hole (61) of the ball. 3. A detachable connection between the rocker (5) of the pitch control unit and the blade rotation lever (8) according to claim 1 or 2, in which the sliding pin (9) has a threaded end (92) and is fixed with a threaded end (92) in the lever (8) rotating the blade using the pin-fixing washer (90) and nut (91). 4. A detachable connection between the rocker (5) of the pitch control unit and the blade rotation lever (8) according to claim 3, in which, in particular, a castle nut (91) and a cotter pin retainer are used. 5. A detachable connection between the rocker (5) of the pitch control unit and the lever (8) for rotating the blade according to one of the previous paragraphs, in which the ball (6) and the outer race (60) are fixed in the through hole (50) of the rocker (5) of the control unit step. 6. Disconnectable connection between the rocker (5) of the pitch control unit and the lever (8) for rotating the blade according to one of paragraphs. 1-4, in which the ball (6) and the outer race (60) are fixed in the through hole (80) of the blade rotation lever (8), allowing rotation and sliding movement of the sliding pin (9). 7. Disconnectable connection between the rocker (5) of the pitch control unit and the lever (8) for rotating the blade according to one of paragraphs. 2-6, wherein the first sliding surface (62) is attached to or embedded in the outer ball surface and the second sliding surface (63) is attached to or embedded in the outer surface of the sliding pin (9). 8. Disconnectable connection between the rocker (5) of the pitch control unit and the lever (8) for rotating the blade according to one of paragraphs. 2-7, in which the second sliding surface (63) is associated with or applied to the outer surface of the sliding pin (9) and contains a separate material, a fiber-reinforced matrix or a sintered material. 9. Disconnectable connection between the rocker (5) of the pitch control unit and the lever (8) for rotating the blade according to one of paragraphs. 3-8, in which the pin fixing washer (90) is made in the form of a conical washer (90). 10. Head (3) of the tail rotor of a rotary-wing aircraft, containing a pitch control unit (4) with a plurality of rockers (5) of the pitch control unit, a plurality of blade holders (7) with tail rotor blades (2) connected to them, each holder (7) the blades are connected to each rocker (5) of the pitch control unit through a detachable connection according to one of the previous paragraphs. 11. The use of a sliding pin (9) containing a pin fixing washer (90), a nut (91), in particular a castle nut (91) and a threaded end (92) with a spherical bearing containing a ball (6) with a through hole ( 61) and the surrounding ball (6) outer race (60) of the spherical bearing, for the detachable connection of the lever (8) for rotating the blade on the holder (7) of the blade with the rocker (5) of the pitch control unit on the unit (4) of the pitch control inside the head (3 ) tail rotor (1) of a rotary-wing aircraft, wherein the sliding pin (9) is attached with the possibility of linear movement and articulated rotation, completely passing through the through hole (80) of the blade rotation lever with passage through the through hole (61) of the ball (6), passing through the through hole (50) of the rocker (5 ) control unit for the step and exit from the specified hole. 12. Application according to claim 11, in which a spherical bearing with a ball (6) and an outer race (60) is fixed in the through hole (50) of each rocker (5) of the pitch control unit (4). 13. A tail rotor (1) for a rotorcraft, wherein the sliding pin (9) is removable and replaceable on a tail rotor (1) fully installed on the rotorcraft without removing any other part except the nut (91) .

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