WO2007055674A1

WO2007055674A1 - Helicopter rotor

Info

Publication number: WO2007055674A1
Application number: PCT/UA2006/000060
Authority: WO
Inventors: Volodymyr Tymofiyovych Yakovenko
Original assignee: Joint Stock Company 'yuzhmash Helicopter'
Priority date: 2005-11-08
Filing date: 2006-10-31
Publication date: 2007-05-18

Abstract

The invention can be used in aviation engineering. The inventive helicopter rotor comprises a rotor head provided with an axial channel, at least two radial projections and radially oriented blades which are provided with shanks and connected to said projections. The shank of each blade and the head projection are connected to each other by means of a connecting unit which comprises a spherical joint consisting of a ball provided with a central through hole and a housing encompassing a part of the surface thereof. The ball of the joint is rigidly connected to a jaw by a cylindrical pin which passes through the ball central hole and holes embodied in the jaw flange and is fixed therein. The connecting unit is provided with a lubricating system formed by a plurality radial channels which are embodied in the ball, connected to each other and connect a contact segment between the ball and housing surfaces, wherein a contact area between said surfaces is embodied in such a way that it is closed against environmental effects and is filled with a pressurised grease. Said invention makes it possible to form a grease film between friction surfaces of the spherical joint and ensure the permanent presence thereof, thereby increasing the service life of said connecting unit.

Description

HELICOPTER SCREW

The invention relates to rotors of helicopters with a separate connection of each blade to the sleeve through a spherical hinge and can be used in aircraft construction.

Known rotor helicopter containing a cylindrical sleeve and connected to it at least two radially directed blades with knots (USSR copyright certificate N ° 907973, B64C 27/39, publ. 1996). Each blade contains a radially directed power frame, inside of which there is a blade comet connected to the sleeve through a frame mounted along the axis of the blade, a damper in the form of an axial spherical elastomeric bearing and a spherical hinge with a sphere and a cage covering part of its surface. In this case, the elastomeric bearing is fixed inside the frame to the end of the frame adjacent to the side surface of the sleeve, and the blade comet is installed in the spherical joint sphere hole located along the axis of the blade, the housing of which is rigidly connected to the end of the elastomeric bearing. To reduce the load on the spherical hinge from the centrifugal force of the comel, the blades and the frame are equipped with fixed stops fixed to the blades and the fixed stops connected to the frame, and the movable stop is made in the form of a spherical belt with a convex spherical working surface and with an axis passing through the center of the elastomeric bearing, and the fixed emphasis - in the form of a closed belt with a concave spherical surface, the axis of which passes through the center of the elastomeric bearing, and its radius is one and a half to two times the radius of the convex spherical surface movable stopper. In addition, the blade comet is equipped with a centrifugal blade deflection limiter with a lever, a counterweight and working surfaces interacting with the working surfaces of the fixed stop. The spherical hinge allows the blades to swing around three mutually perpendicular axes, and the spherical elastomeric bearing dampens these swings. However, to reduce the load on the spherical joint from centrifugal force, which determines its rapid wear, additional structural elements are provided, i.e. stops and centrifugal stop described above. All these elements have a complex structure, which makes them difficult to manufacture, and complex connections between themselves and other elements of the blades, which makes it difficult to install these elements in the rotor and adjust its components and elements and, therefore, increases the time and cost of maintenance and repair of rotors, and also increases their cost and operating costs. Along with this, the movable and fixed stops in the process of their relative movements are under the action of large forces caused by centrifugal forces, which creates large friction forces and, consequently, leads to increased wear of the stops, which requires their frequent replacement, i.e. causes a small overhaul resource. In addition, the gap between the rubbing surfaces of the stops increases during operation, which leads to impact interaction of the nodes and elements of the screws, i.e. to the occurrence of vibration, which, in turn, can lead to various kinds of disturbances in the operation of the rotors and additionally increases the wear of their elements, i.e. reduces the reliability of the rotors, which is already reduced by the introduction of additional elements working with large variable loads, i.e. emphasis. It should also be noted that the introduction of stop screws and centrifugal stops into the screw design increases their mass and, in addition, increases the length of the blade lobe, i.e. causes either a decrease in the aerodynamic surfaces of the blades or increases their length.

The closest to the proposed rotor in terms of combination of features and properties is the rotor of the helicopter containing a sleeve with radial protrusions and at least one pair of radially doubled directed blades with knots, each of which is associated with a corresponding radial protrusion of the sleeve (UK patent JVb 1236650, IPC B64C 27/48, publ. 23.06. 71 g). In this case, the blade comel is connected with the protrusion of the sleeve by a connecting unit, in which the blade comel is formed in the form of a fork with a wall and two parallel shelves made with two coaxial holes, and the sleeve protrusion is placed inside the fork and is made with a through channel, coaxial holes in the fork shelves. Along with this, the connecting unit contains a spherical hinge composed of a sphere with a central through hole and covering part of its surface of the cage, the spherical hinge being fixed by a cage in the through channel of the protrusion of the sleeve, and a finger secured through the central opening of the sphere and the hole in the shelves of the fork in these shelves. In addition, the screw is made with a limiter for swinging the blades around three mutually perpendicular axes in the form of a protrusion of each blade of a circular belt mounted on the opposite axis of rotation of the sleeve, which is installed with circumferential and axial clearances in a circular groove in the fork wall. These limiters do not damp the swing of the blade and cause the occurrence of shock loads on the connecting elements. The screw also contains two dampers connecting the fingers in the connecting nodes of both blades, not intended for damping the swings of the blades around three mutually perpendicular axes. The fork is located relative to the axis of the sleeve so that the coaxial holes in its shelves are perpendicular to the axis of the sleeve, which limits the main movement of the blade - circumferential, and also creates additional resistance to control the angle of attack of the blade.

A centrifugal force directed radially relative to the axis of the sleeve is perceived by the finger portions that are in contact with the holes in the forks of the fork facing the axis of the sleeve. The finger transfers the force from the centrifugal force through a spherical hinge to the protrusion of the sleeve. Thus, the connecting unit perceives the entire load from centrifugal forces, which eliminates the need for a centrifugal limiter and stops, perceiving the entire load from centrifugal force in the previous analogue. Moreover, the specified connecting node consists of fewer parts, which, moreover, have a much simpler shape and therefore are simpler to manufacture. Along with this, the connecting unit is more compact, its design provides simplification of assembly and disassembly, inspection and balancing, as well as lower material consumption and cost.

However, the entire load from the centrifugal force transmitted by the finger to the sleeve is concentrated on the contact area facing the end of the blade between the surface of the sphere and the inner surface of the cage of the spherical hinge. This site occupies only a small fraction of the contacting surfaces, which leads to significant contact efforts in this area. This, in turn, leads to a large friction force between the surfaces contacting in this area and, consequently, their rapid wear, especially if we take into account the fact that the spherical hinge swings around the sphere with a high frequency and low amplitude. All this leads to a small resource of the spherical hinge. In addition, the rapid wear of the rubbing surfaces in this area of their contact leads to an increase in the gap between them and, consequently, to the occurrence of shock loads in the connecting node, to the imbalance of the rotor balance, etc., which quickly makes the connecting node inoperative and necessitates replacement of its elements. This problem for the closest analogue is supposed to be solved by such a combination of materials of the sphere and the holder of the spherical hinge, which would have good wear resistance and would minimize the need for maintenance. However, due to the high values of centrifugal force and the small size of the contact area between the friction surfaces of the spherical joint, the high contact forces in this section make it difficult to maintain the operability of the spherical joint.

Therefore, the basis of the invention the task of improving the rotor of the helicopter by creating an oil film between the rubbing surfaces of the spherical hinge with a constant presence of the oil film on the most contacted area between these surfaces with the centrifugal force, which will ensure more uniform wear of the rubbing surfaces of the spherical hinge, and also reduce its size, and therefore, increase the resource of the connector.

The problem is solved in the rotor of the helicopter containing a sleeve with an axial channel and at least two radial protrusions, as well as radially directed blades with knots associated with these protrusions. In this case, the comel of each of the blades and the protrusion of the sleeve are connected to each other by a connecting unit comprising a first element formed by a fork with an end wall and two parallel shelves protruding from it, made with two through coaxial holes, and also a second element located between the shelves of the fork and made with a through channel. In addition, the rotor contains a spherical hinge made up of a sphere with a central through hole and covering part of its surface of the cage, and the sphere of the spherical hinge is rigidly connected to the fork with a cylindrical finger passed through the central hole of the sphere and the holes in the shelves of the fork and fixed in these holes , the clip is fixed in the through channel of the second element located inside the plug, and the protrusion of the sleeve and the comel of each blade are interconnected by a limiter of swing of the blade around three mutually per pendicular axes.

According to the invention, the connecting unit is equipped with a lubrication system formed by a plurality of interconnected radial channels in the sphere connecting the contact area between the surfaces of the sphere and the cage, the contact zone between these surfaces being closed from the influence of the external environment and filled with grease having high adhesive and wetting properties abilities.

The location of the channels connecting the opposite contact areas of the surfaces of the sphere and the holder of the spherical hinge along the axis of the blade, i.e. along the line of action of centrifugal force, it can be used to constantly move the oil film in the gap between the rubbing surfaces. The centrifugal force acts on the oil film in the direction of the end of the blade, which determines its outflow through the channels in the sphere from the contact areas between the sphere and the holder of the spherical hinge facing the sleeve, to the parts of this contact facing the end of the blade, which, in turn, determines a decrease in pressure in the first section and its increase in the second. The pressure drop causes the oil film to flow against the action of centrifugal force in the direction of the contact areas facing the sleeve, and pass into the channels open to these areas. Under the action of centrifugal force, the lubricant passes through these channels towards the contact area facing the end of the blade. Thus, there is a constant circulation of lubricant through the channels in the sphere and the gap between the surface of the sphere and the inner surface of the spherical hinge in contact with it. In this case, the blades occurring with a high frequency of swing around three mutually perpendicular axes cause the spherical hinge to swing relative to its sphere with a small amplitude. Along with the high adhesive ability of the lubricant and its high wetting ability, these oscillations, as well as the differential pressure of the lubricant in the gap between the rubbing surfaces, ensure the constant penetration of the lubricant between these surfaces even in the most stressed contact area, i.e. on the plot facing the sleeve, and, therefore, a more uniform distribution of lubricant in the gap between the rubbing surfaces and the continuity of the oil film. At the same time, the high adhesive ability of the lubricant and its consistent state prevent the displacement of the lubricant from the most loaded contact area of the rubbing surfaces in a spherical joint. Closing the contact area between the surfaces of the sphere and the cage against the influence of the external environment mainly guarantee the presence of lubricant in the system, as well as protection against moisture and / or dust, which can lead to contamination of the lubricant and failure of the entire assembly, and this closure can optionally also be sealed. All this provides a more uniform wear of the rubbing surfaces of the spherical hinge, and also reduces its size and, therefore, increases the resource of the connecting node.

It is advisable to perform radial channels in the finger, coaxial to the radial channels in the sphere with the formation of through radial channels connecting the contact areas between the surfaces of the sphere and the cage of the spherical hinge, as well as an axial channel connected to these through radial channels, and the axial channel at the junction with the radial channels equip with grease filled with grease fitting with check valve.

When the main rotor is stationary, a grease gun is supplied with a grease gun to the grease gun through a non-return valve under pressure, which enters the axial channel in the finger through the radial channels in the finger and the sphere of the spherical hinge between the surfaces of the sphere and the holder. The location of the grease fitting at the end of the axial channel provides easy access to it, which makes it easy and quick to fill the system with grease, as well as replenish the supply of grease in the system by injecting the right amount of grease into it. The lubricant is circulated over the entire contact zone of the rubbing surfaces of the spherical hinge through interconnected through radial channels in the finger and the sphere.

It is also desirable to use molybdenum lubricant as a grease.

An additional embodiment of the invention provides for the location of at least two radial channels in a sphere along the axis of the blade. An additional advantage according to the invention is the execution on the outer surface of the sphere of a spherical hinge of many grooves.

The presence of grooves on the surface of the sphere contributes to the additional capture and retention of the lubricant in the most loaded contact area of the rubbing surfaces in the spherical hinge.

It is also advisable to carry out the contact zone between the indicated surfaces of the sphere and the holder closed from the influence of the external environment with the help of the packing gland located around the specified finger.

The invention is illustrated by drawings, where in FIG. 1 shows a partial diagram of a rotor of a helicopter, a plan view; in FIG. 2 is a partial diagram of a rotor hub with a blade, a side view in section; in FIG. 3 is a schematic diagram of a connecting unit on an enlarged scale, a side view in section; in FIG. 4 is a section A-A of FIG. 3; in FIG. 5 is a section BB of FIG. 2; in FIG. 6 is a diagram of a spherical hinge with another embodiment of a lubrication system, a sectional side view; in FIG. 7 is a section B-B of FIG. 6; in FIG. 8 is a partial diagram of a rotor hub with a blade with another embodiment of a hub and blade connection, a sectional side view.

The rotor of the helicopter (Fig. 1, 2) contains a sleeve 1 with an axial hole 2 and three radial protrusions 3, as well as three radially directed blades 4 with knots 5. Each protrusion 3 of the sleeve 1 is connected to the knot 5 of the corresponding blade 4 with a connecting unit, including the first element formed at the end of the protrusion 3 by a fork 6 with two parallel shelves 7 and 8, with a cylindrical section 9 and an end wall 10, and also located between the shelves 7 and 8 of the fork 6, the second element in the form of a butt 5 of the blade 4. In the shelves 7 and 8 there are two through coaxial holes, axis k toryh optionally parallel to the axis of rotation sleeves 1. The connecting unit also includes a spherical joint 11 located between the shelves 7 and 8 of the plug 6, made up of a sphere 12 with a central through hole and covering part of its surface of the sleeve 13. The spherical joint 11 is pressed into the sleeve 13 in the through channel of the inside of the fork 6 and butt 5. Through the central hole in the sphere 12 and the coaxial holes in the shelves 7, 8 of the plug 6, a pin 14 is passed, which is fixed in the shelves 7 and 8. At the end of the cylindrical section 9 of the plug 6, a connecting sleeve 1 is fixed to the butt 5 of the limiter blade 4 l swing of the blade 4 in the form of a damper 15 with a through axial channel in which the end of the butt 5 of the blade 4 is installed. The damper 15 (Fig. 2, 5) is made in the form of a body of revolution made of elastomeric material 16, fixed between the rigid outer 17 and inner 18 clips of which the outer casing 17 is pressed into the inner cylindrical surface of the fork 6, and the inner 18 is pressed onto the butt 5 of the blade 4 and is made in the form of a needle bearing 19, which reduces friction when controlling the angle of attack of the blade. On each blade 4, a lever for controlling the angle of attack of the blade 20 is fixed.

The finger 14 is made with a flange 21 (Fig. 3), with which it is supported by a radial protrusion in the flange 7, and fixed from axial movements by a washer 22 and a cotter pin 23. The outer surface of the finger 14 is covered by a stuffing box seal 24, which covers the contact area of the surfaces of the sphere 12 and the holder 13 spherical joint 11.

The connecting element is equipped with a lubrication system (Fig. 3, 4) formed by coaxially blades 4 and interconnected by several through radial channels 25 in pin 14 and channels 26 in sphere 12 on both sides of pin 14, as well as an axial channel 27 in the upper half finger 14, connected by a threaded axial channel 28 with radial channels 25 and 26, and the axial channel 27 is made of a larger diameter than the threaded axial channel 28. A grease nipple 30 filled with molybdenum grease is installed on the lower end of the channel 27 with threaded a non-flange 31 screwed into the threaded channel 28. Oiler 30 is made with a check valve for a grease gun.

The main rotor operates as follows.

When the main rotor is stationary, grease is injected into the grease fitting 30 (Fig. 1-4) through a non-return valve using a syringe, which passes through the axial channel 28 under pressure into the radial channels 25 and 26 and then to the contacting surfaces of the sphere 12 and the holder 13 of the spherical hinge 11. Molybdenum grease is capable of working under conditions of extreme pressures (7000 kg / cm ² ) and temperatures (for a long time - 160 ⁰ C, periodically - 250 ⁰ C), as well as in various weather conditions. It is also resistant to water and high humidity. Along with this, the molybdenum grease has high adhesive and wetting properties, which ensures the penetration of the lubricant into the gap between the contacting surfaces of the sphere 12 and the cage 13 even on the most contacted contact area facing the sleeve I ₅ and thereby contributes to the formation of an oil film between these surfaces. The rotation of the blade 4 creates a centrifugal force F, which is transmitted through the contact portion 32 of the holder 13 and the sphere 12 of the spherical hinge 11 to the finger 14. The finger 14 transmits forces from the centrifugal force to the shelves 7 through the sections 33 and 34 of its contact with the holes in the shelves 7 and 8 and 8 forks 6 and, therefore, on the rotor hub 1.

When the rotor rotates, the swashplate constantly changes the angle of attack of the blade 4, as a result of which it swings with an amplitude of up to 8 ° around its axis. Along with this, the blade 4 is subjected to circumferential swings up to 5 °, as well as swing movements up to 5 °. In this case, the comel 5 of the blade 4 together with the holder 13 of the spherical hinge 11 swings relative to the sphere 12 around three mutually perpendicular axes. These swings are transmitted by the butt 5 of the blade 4 through the inner ring 18 made in the form of a needle bearing to the elastomeric material 16 of the damper 15 and through its outer ring 17 to the shelves 7 and 8 of the fork 6, \ due to which these swings are damped and limited in amplitude.

The centrifugal force F acts on the oil film in the direction of the end of the blade 4, which determines its outflow through the radial channels 26 in the sphere 12 with the contact portion 32 facing the sleeve 1 between the sphere 12 and the ferrule 13 of the spherical hinge 11, to the contact portion 35 facing the end blades 4, which, in turn, causes a decrease in pressure in section 32 and its increase in section 35. The pressure drop causes the oil film to flow against the action of centrifugal force F in the direction of the contact section 32 facing the sleeve 1, and pass to p dialysis channels 26, open to section 32. Under the action of centrifugal force, the lubricant passes through the channels 26 towards the section 35 facing the end of the blade 4. Thus, there is a constant circulation of lubricant along the radial channels 26 and the gap between the surface of the sphere 12 and contacting it the inner surface of the cage 13 of the spherical hinge 11. The swing of the cage 13 of the spherical hinge 11 relative to its sphere 12 with low amplitude, along with the high adhesive ability of the molybdenum grease and its high wetting ability, as well as erepad lubricant pressure in the clearance between the friction surfaces provide a permanent penetration lubrication between these surfaces, even on the most loaded contact forces portion 32 facing towards the hub 1, and hence a more uniform distribution of lubricant in the gap between the friction surfaces and the continuity of the oil film. At the same time, the high adhesive ability of the molybdenum lubricant and its consistent state prevent the displacement of the lubricant from the most loaded contact area 32 of the friction surfaces in the spherical hinge 11, which also contributes to the presence of the oil film on the area 32, and also stabilizes its parameters. All this provides a more uniform wear of the rubbing surfaces of the spherical hinge 11, and also reduces its size and, therefore, increases the resource of the connecting node.

The lubrication system of the connecting node (Fig. 6, 7) may be formed by the circumferential groove 36 in the pin 14 and the radial channels 37 and 38 connected to it in the sphere 12 of the spherical hinge 11, as well as the grooves 29. The spherical hinge 11 is enclosed in a closed housing 39, equipped with an oiler 40 and filled under pressure with molybdenum grease. A lubricant under pressure penetrates between the sphere 12 and the holder 13 of the spherical hinge 11, forming an oil film between them. Swinging of the blade around three mutually perpendicular axes causes the grease to be captured by the grooves 29 from the closed housing 39 and provide constant penetration of the grease between the contact surfaces of the sphere 12 and the cage 13. When the rotor rotates, the centrifugal force F shifts the lubricant along the circumferential groove 36 to the portion facing the end of the blade 41 between the rubbing surfaces of the sphere 12 and the cage 13. In this section, the pressure increases, and the lubricant in the gap between these surfaces moves to the section 42 facing the sleeve, from where you again squeezed by centrifugal force along the groove 36 to section 41. Thus, the lubricant circulates in the gap between the surfaces of the sphere 12 and the holder 13. The disadvantage of this system is to reduce the cross section of the finger 14 and, therefore, to weaken it.

In another embodiment of the rotor assembly of the helicopter (Fig. 8), the fork 43 can be formed at the end of the butt 44 of the blade 45, while a protrusion 48 of the sleeve 49 is placed between its shelves 46 and 47. In this case, the load from the centrifugal force is transmitted from the blade 45 through the plug 43 onto the finger 14 and further from the finger 14 through the sphere 12 and the yoke 13 of the spherical hinge 11 to the protrusion 48 of the sleeve 49. The connecting unit may be equipped with the same lubrication systems as those shown in FIG. 3, 4. This arrangement of the rotor complicates the balancing of the blade due to the presence on the butt 44 of the blade 45 of the masses located at a distance from its axis (shelves 46 and 47 of the fork 43), and also increases the mass of the blade 45 and, therefore, the value of the centrifugal force F , which increases the load on the elements of the connecting node, including the contact load on the most loaded section 41 of the contact of the sphere 12 with the cage 13 facing the end of the blade 45. However, unlike the previous rotor arrangement, the centrifugal force F acts on the oil film in the direction of section 41, which significantly improves its lubrication conditions and, therefore, reduces the negative effect of increasing the centrifugal force F.

The execution of one of the elements (the protrusion of the sleeve or the butt of the blade) in the form of a fork and the placement of the other element (the butt of the blade or sleeve, respectively) between its shelves allows you to choose one of the two main rotor layouts, which expands the possibilities of solving various design and technological problems in the process development or improvement of rotors of helicopters.

Claims

CLAIM

1. The rotor of the helicopter, comprising a sleeve with an axial channel and at least two radial protrusions, as well as radially directed blades with knots associated with these protrusions, the comel of each of the blades and the protrusion of the sleeve are connected to each other by a connecting unit including a first element, formed by a fork with an end wall and two parallel shelves protruding from it, made with two through holes, as well as a second element located between the shelves of the fork and made with a through channel, spherically a hinge made up of a sphere with a central through hole and covering part of its surface of the cage, the sphere of the spherical hinge being rigidly connected to the fork by a cylindrical finger passed through the central hole of the sphere and the hole in the flanges of the fork and fixed in these holes, the cage is fixed in the through channel located inside the forks of the second element, and the protrusion of the sleeve and the comel of each blade are interconnected by a limiter of swing of the blade around three mutually perpendicular axes, characterized in that itelny node equipped with the lubrication system formed by a plurality of interconnected channels in the radial connecting portion between the contact surfaces of the sphere and collar, the contact area between said closed surfaces formed by influence of the environment and filled with grease, which has high adhesiveness and wetting abilities.

2. The rotor of the helicopter according to claim 1, characterized in that the finger has radial channels aligned with the radial channels in the sphere with the formation of through radial channels connecting the contact areas between the surfaces of the sphere and the holder of the spherical hinge, as well as an axial channel connected to the indicated through radial channels, and the axial channel at the junction with radial channels equipped with grease-filled grease fitting with check valve.

3. The rotor of the helicopter according to any one of p. 1 or 2, characterized in that the grease is molybdenum grease.

4. The rotor of the helicopter according to any one of paragraphs. 1 to 3, characterized in that at least two radial channels in the sphere are located along the axis of the blade.

5. The rotor of the helicopter according to any one of paragraphs. 1 to 4, characterized in that the said sphere further has a plurality of external grooves.

6. The rotor of the helicopter according to any one of paragraphs. 1 to 5, characterized in that the contact area between these surfaces is closed by a packing gland located around the finger.