CN110683049B - Hub device for small-sized tilt rotor aircraft - Google Patents

Abstract

The embodiment of the invention discloses a hub device for a small-sized tilt rotor aircraft, relates to the technical field of rotor aircrafts, and can realize the pitch change of each blade and improve the operation reliability. The invention includes: the hub device is formed by assembling an upper part and a lower part which are separated from each other, and the upper part and the lower part are restrained by a circular ring; the lower part of the hub device is connected with the rotor shaft through a bolt; the Y-shaped shaft is arranged between the upper portion and the lower portion of the propeller hub, wherein a first gasket, a deep groove ball bearing, a sleeve, a deep groove ball bearing, a thrust bearing, a second gasket and a screw are sequentially arranged on the Y-shaped shaft from the propeller hub portion (the central position) to the outside; the inner side of the blade clamp is provided with a boss structure, and the boss structure is positioned between the second deep groove ball bearing and the thrust bearing. And a variable pitch rocker is arranged outside the root part of the blade clamp, wherein the size of the variable pitch rocker is matched with the relative position of the operating node. The invention is suitable for operation of small tiltrotor aircraft.

Description

A propeller hub device for a small tilt-rotor aircraft

technical field

The invention relates to the technical field of rotorcraft, in particular to a propeller hub device for a small tiltrotor.

Background technique

Helicopter has the advantages of vertical take-off and landing and hovering in the air, and fixed-wing aircraft has the characteristics of high flight speed. Tilt-rotor is a new type of aircraft that integrates fixed-wing aircraft and helicopter. It has both vertical take-off and landing, air hovering functions and high-speed cruise flight capabilities. When the tiltrotor is in helicopter mode (vertical flight and low-speed flight), the flight speed is low, and the fixed wing surface is difficult to provide the lift required for flight, so the rotor should be used as the main lifting surface, so the control of the aircraft needs to be automatically tilted by the helicopter In the fixed-wing aircraft mode (high-speed flight), it is operated in the way of a propeller aircraft, and the fixed wing is used to generate lift, which is more efficient, and the flight speed can be changed by changing the propeller speed and adjusting the size of the thrust; tilt transition In the state, stable flight is achieved by adjusting the collective pitch and rotational speed.

In helicopter mode, in order to ensure the control requirements of the tilt-rotor, if the control is performed in a variable speed mode, it will cause asymmetric lift of the rotors on both sides, thus generating a rolling moment on the fuselage, and the requirements for ground control are relatively high. high, and cannot quickly achieve yaw and side flight control. In the fixed-wing mode, if the automatic tilter is used for manipulation, on the one hand, the characteristics of the high-speed airfoil at the tip of the blade cannot be fully utilized, and on the other hand, the coupling vibration problem caused by the rotor manipulation is relatively large.

Therefore, how to meet the requirements of maneuvering and strength conditions, especially the maneuvering reliability of the tiltrotor in the helicopter mode, has become an urgent research topic.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a propeller hub device for a small tilt-rotor aircraft, which can realize the pitch change of each propeller blade and improve the maneuvering reliability.

In the first aspect, in a propeller hub device for a small tiltrotor aircraft provided by an embodiment of the present invention, the propeller hub device is formed by assembling two parts separated from the upper and lower parts, and the upper part and the lower part are constrained by a circular ring. ;

The lower part of the propeller hub device is connected with the rotor shaft (7) through bolts (3);

The Y-shaped shaft is installed between the upper and lower parts of the propeller hub, wherein the outer side of the Y-shaped shaft and the part close to the propeller hub are installed with the first washer, the deep groove ball bearing (6), the sleeve in order from the inside to the outside. barrel, deep groove ball bearing (6), thrust bearing (4), second washer and screw;

The inner side of the blade clamp (1) is a boss structure, and the boss structure is located between the second deep groove ball bearing (6) and the thrust bearing (4), and the thrust bearing (4) is used to bear the rotation of the rotor When the centrifugal force is generated by each blade, the boss structure is used to transmit the centrifugal force load to the thrust bearing (4);

A pitch-changing rocker arm (2) is installed on the outer side of the root of the blade clip (1), wherein the size of the pitch-changing rocker arm (2) matches the relative position of the control node.

In combination with the first aspect, in a first possible implementation manner of the first aspect, the end of the blade clip (1) is connected to the blade through a bolt (3), while the other end of the blade clip (1) is connected through the middle The shaft is connected to the propeller hub, and the bolt (3) is used to fix the parts on the intermediate connecting shaft; one end of the variable pitch rocker arm (2) is connected to the blade clamp (1) through the bolt (3), and the pitch is changed. The other end of the rocker arm (2) is connected with the variable pitch rod, and is tilted through the automatic tilter.

In combination with the first possible implementation manner of the first aspect, in the second possible implementation manner, the deep groove ball bearings (6) are installed in pairs, and a sleeve is installed in the middle of the deep groove ball bearings (6) to The form of a force couple in the structure bears the moment that the lift force generated by the blade is transmitted to the hub; a specially designed spacer (5) is installed on the shaft end.

In combination with the first aspect, in a third possible implementation manner of the first aspect, the components of the automatic tilter include a movable ring (8) and a stationary ring (12), and the stationary ring (12) is divided into upper and lower parts , and connected with screws, the fixed ring (12) is nested on the spherical hinge, and the rollers are installed between the moving ring (8) and the fixed ring (12).

Specifically, a motor is connected below the rotor shaft (7) for transmitting the torque output by the motor; the moving ring (8), the first harpoon-shaped member (9) and the second harpoon-shaped member (10) of the automatic tilter A torsion arm is formed, and the torsion arm is used to drive the moving ring (8) to rotate together with the rotor.

In this embodiment, the three separation shafts are combined into a Y-shaped shaft, the centrifugal force can be balanced in the structure, and the torque transmitted from the rotor shaft (7) is mainly transmitted by the two bolts (3) at the propeller hub. 7) The upper shape requirements are lower. The parts and assembly diagram of the propeller hub are shown in Figure 6. In order to install the Y-shaped shaft, the shape of the head of the rotor shaft (7) needs to be designed to fit with it, and the propeller hub is divided into upper and lower parts. Connect the upper and lower parts of the propeller hub with a circular connecting ring. The circular connecting ring is designed in a tapered form, and the displacement and deformation at the propeller hub are limited by the structural geometry. Thus, the pitch change of each blade is realized, so that the rotational speed is driven and input by the motor.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

Fig. 1 is a structural exploded view of a propeller hub system provided by an embodiment of the present invention;

2 is a three-dimensional view and a three-dimensional axonometric view of a propeller hub system provided by an embodiment of the present invention;

3 is a schematic diagram of a connection relationship between a blade clip and a hub provided by an embodiment of the present invention;

4 is a schematic diagram of a torsion arm and a follower device provided by an embodiment of the present invention;

5 is a schematic diagram of an automatic tilter provided by an embodiment of the present invention;

FIG. 6 is a diagram of components and an assembly of a propeller hub according to an embodiment of the present invention.

Detailed ways

In order to make those skilled in the art better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Hereinafter, embodiments of the present invention will be described in detail, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but not to be construed as a limitation of the present invention. It will be understood by those skilled in the art that the singular forms "a", "an", "the" and "the" as used herein can include the plural forms as well, unless expressly stated otherwise. It should be further understood that the word "comprising" used in the description of the present invention refers to the presence of stated features, integers, steps, operations, elements and/or components, but does not exclude the presence or addition of one or more other features, Integers, steps, operations, elements, components and/or groups thereof. It will be understood that when we refer to an element as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Furthermore, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as herein, are not to be taken in an idealized or overly formal sense. explain.

An embodiment of the present invention provides a propeller hub device for a small tilt-rotor aircraft, as shown in Figs. 1 and 2 , which are schematic diagrams of the tilt-rotor propeller hub and the control mechanism. The propeller hub device is formed by assembling two parts that are separated up and down. , the upper part and the lower part are constrained by a ring.

The lower part of the propeller hub device is connected with the rotor shaft (7) through bolts (3).

The ring (15) is used to connect the upper part (13) and the lower part (14), and its specific shape parameters depend on the specific parameters and load conditions of the propeller hub. When the load on the propeller hub is large, the ring should have a large cross-sectional area and a small inclination of the inner wall surface; in addition, the roughness of the inner wall surface is large enough to limit the deformation of the propeller hub. Roughness is positively related to the ability to limit deformation. Due to the existence of the ring, there is no need for openings on the Y-axis for connection, and there is no weakening of the strength, so the structural weight can be greatly reduced.

The Y-shaped shaft is installed between the upper and lower parts of the propeller hub, wherein the Y-shaped shaft is sequentially installed with a first washer, a deep groove ball bearing (6), a sleeve, Deep groove ball bearing (6), thrust bearing (4), second washer and screw.

The Y-shaped shaft is installed between the upper and lower parts of the propeller hub, wherein the outer side of the Y-shaped shaft and the part close to the propeller hub are installed with the first washer, the deep groove ball bearing (6), the sleeve in order from the inside to the outside. barrel, deep groove ball bearing (6), thrust bearing (4), second washer and screw.

The inner side of the blade clamp (1) is a boss structure, and the boss structure is located between the second deep groove ball bearing (6) and the thrust bearing (4), and the thrust bearing (4) is used to bear the rotation of the rotor When the centrifugal force is generated by each blade, the boss structure is used to transmit the centrifugal force load to the thrust bearing (4).

A pitch-changing rocker arm (2) is installed on the outer side of the root of the blade clip (1), wherein the size of the pitch-changing rocker arm (2) matches the relative position of the control node.

At present, the development of propeller hubs at home and abroad is also relatively rapid. At present, the configuration of the elastic bearing to provide the freedom of flapping and swaying deformation of the blade is relatively advanced. host. Dong Linghua et al. designed a constant velocity universal hinge propeller hub for tilt rotors, which mainly solved the problem of rotational speed fluctuations. The tiltrotor has specific and better control methods in different modes. If it is operated in a single mode, the control performance will be limited. Aiming at this feature, based on the light tiltrotor, a design scheme of the propeller hub and control system that can realize different control modes in different flight states is proposed, so as to realize the control of the tiltrotor in different flight states. need. In this embodiment, based on the propeller-hub structure of a conventional helicopter, a propeller-hub system suitable for a small tilt-rotor aircraft is designed according to the manipulation requirements of the tilt-rotor aircraft, which is used to realize the operation of the tilt-rotor aircraft during flight. The tilt-rotor hub designed in this case has a simple structure and fast response, which can meet the control of pitch and speed changes, and is suitable for small tilt-rotor aircraft with rigid blades. Taking a scaled model of a tiltrotor as an example, the strength is checked. The calculation results show that the propeller hub configuration can meet the control requirements and strength conditions under various flight conditions, and has high reliability. At the same time, a flow cover can be designed and installed on the outside of the propeller hub, thereby reducing the resistance caused by the separation of airflow in the propeller hub during flight.

In order to solve the control problem of the tiltrotor in the helicopter mode, the control quantities that each propeller hub and control mechanism need to provide are: collective pitch, lateral cyclic pitch change, longitudinal cyclic pitch change, and rotational speed. The purpose of the propeller hub device designed in this embodiment is to realize the pitch change of each propeller blade.

Specifically, for a conventional two-blade rotor, an optical axis runs through the rotor shaft (7), and the centrifugal force of the rotor is balanced on the shaft. For a three-blade rotor, three separate shafts are generally used to connect the blades. However, this configuration relies on bolts (3) to connect the shaft and the propeller hub, and the opening of the shaft has a great influence on the mechanical properties of the shaft. Therefore, in this embodiment, three separate shafts are combined into a Y-shaped shaft, and the centrifugal force It can be balanced in the structure, and the torque transmitted from the rotor shaft (7) is mainly transmitted by the two bolts (3) at the propeller hub, which has lower requirements on the shape above the rotor shaft (7). The parts and assembly diagram of the propeller hub are shown in Figure 6. In order to install the Y-shaped shaft, the shape of the head of the rotor shaft (7) needs to be designed to fit with it, and the propeller hub is divided into upper and lower parts. Connect the upper and lower parts of the propeller hub with a circular connecting ring. The circular connecting ring is designed in a tapered form, and the displacement and deformation at the propeller hub are limited by the structural geometry. The part above the rotor shaft (7) protruding from the hub is used to connect and install the fairing.

The connection between the blade clip (1) part and the propeller hub is specifically shown in Figure 3, the end of the blade clip (1) is connected to the blade through the bolt (3), and the other part of the blade clip (1) is connected to the blade. One end is connected to the propeller hub through an intermediate connecting shaft, and the bolt (3) is used to fix the parts on the intermediate connecting shaft.

One end of the variable pitch rocker arm (2) is connected to the blade clamp (1) through the bolt (3), and the other end of the variable pitch rocker arm (2) is connected to the variable pitch pull rod, and is tilted by the automatic tilter, In order to transfer the control to the blades, realize the pitch control of each blade.

The deep groove ball bearings (6) are installed in pairs, and a sleeve is installed in the middle of the deep groove ball bearings (6), in the form of a force couple, in the structure, it bears the moment that the lift force generated by the blade is transmitted to the propeller hub. A specially designed spacer (5) is installed on the shaft end.

The main parameters of this part are the diameter D _z of the Y-shaped shaft and the distance l _qz between the two deep groove ball bearings (6). The size of D _z affects the centrifugal force limit that the intermediate connecting shaft can withstand and the selection of deep groove ball bearings (6) and thrust bearings (4), and the size of l _qz affects the deep groove ball bearings (6) can withstand The size of the propeller hub moment.

In this embodiment, as shown in FIG. 5 , the components of the automatic tilter include a moving ring (8) and a stationary ring (12), and the stationary ring (12) is divided into two parts, the upper and lower parts, which are connected by screws, The stationary ring (12) is nested on the spherical hinge to ensure the continuity of movement. Rollers are installed between the movable ring (8) and the stationary ring (12) to realize relative rotation. Among them, the automatic tilter part is composed of two parts: a moving ring and a non-moving ring. The two are connected by cylindrical rollers to achieve relative rotation. The fixed ring is divided into upper and lower parts, and a small screw necklace is placed between the two parts, and is nested on the spherical hinge to realize the rotation with the spherical hinge.

The main parameters of the automatic tilter are the radius R of the central spherical hinge, and the half height h. The relationship between the two needs to be satisfied

In order to ensure that the automatic tilter has a control space of ±15°.

Further as shown in Figure 4, a motor is connected below the rotor shaft (7) for transmitting the torque output by the motor. The moving ring (8), the first harpoon-shaped member (9) and the second harpoon-shaped member (10) of the automatic tilter form a torsion arm, which is used to drive the moving ring (8) to rotate together with the rotor. Since the variable pitch rod is a two-force rod, it cannot bear the torque, which shows the necessity of this mechanism. The essence of the torsion arm is a crank-rocker mechanism. As can be seen from Figure 4(b), when the rotor shaft (7) rotates, the torsion arm retains the rotational freedom of the moving ring around the spherical hinge in addition to transmitting torque. In the design of the mechanism, the main parameters are the lengths of the four sections: l ₁ , l ₂ , l ₃ , l ₄ . When designing and selecting four rod lengths, the manipulation requirements should be determined: the manipulation amount of the automatic tilter is generally ± ₁₅ °, so the angle range between l3 and _l4 is (75°, 105°); Transmission efficiency, the included angle (acute angle) between l ₁ and l ₂ is the transmission angle, which should be at least 40°; the length of l ₄ determines the overhang of the control node, which should be reasonably selected according to the size of the propeller hub; l ₁ The lengths of the three rods , l ₂ and l ₄ indirectly reflect the quality of the mechanism. The smaller the length, the lower the quality. Therefore, the length of the four-section rod should be comprehensively selected according to the design parameters of the propeller hub and the manipulation requirements.

As shown in Figure 6, in the design process of the propeller hub, the main basis is the load, working environment, safety factor, etc. when the rotor is working. Because the rotor aerodynamic environment is complex and the alternating load is serious, the safety factor is between 1.5 and 2.0. The rotor shaft (7) has a simple structure, but the load is complex. In the helicopter mode and the fixed-wing mode of the tiltrotor, the main loads on the rotor shaft (7) are tensile force and torque. During the tilt transition process, the bending moment affects the rotor. The influence of the shaft (7) is also large. At the same time, considering that the connection between the propeller hub and the rotor shaft (7) is connected by bolts (3), the weakening of the shaft performance by the hole must be taken into consideration. The main loads of the propeller hub part are the propeller hub force, the propeller hub moment and the centrifugal force transferred by the rotor rotation, as well as the torque transferred from the rotor shaft (7). According to the rotor slip flow theory, the aerodynamic load is estimated, and the hub force, the hub moment and the centrifugal force are calculated. The size of the propeller hub is designed according to the torsion and bending at the same time, and the result with the larger size is selected as the design result. The load situation of the intermediate connecting shaft is relatively simple, but there are many influencing factors in the design process. The main load of the intermediate connecting shaft is the pulling force (rotor centrifugal force) and the shearing action at the connection with the hub. The influencing factors are the weight of the connecting shaft, the inner diameter of the bearing, and the material. The part of the blade clamp (1) is mainly designed for function, and enough space is required to install the ball bearing and thrust bearing (4) inside, and the outside is connected to the pitch-changing rocker arm (2) and the pitch-changing pull rod to realize the pitch-changing function.

Check the strength of the propeller hub through the test experiment:

Assuming that a certain type of tiltrotor has a take-off weight of 90kg and a blade radius of 0.7m, the concentrated load of the blade is estimated according to the aerodynamic model of the momentum theory:

Table 1 Basic parameters and load prediction results of propeller blades

The selection of propeller hubs is shown in the table below:

Table 2 Propeller hub material selection parameter table

Under the load conditions described in Table 1, the static strength of the most complex part of the propeller hub is checked. According to the check results, the most serious position of the load is on the Y-shaped shaft, and the maximum stress is 143.28Mpa. Considering the safety factor of 2 and 10 materials Use 45 steel for safety. The outer side of the blade clip (1) has a maximum displacement of 0.35mm.

It can be seen from the second time that in this embodiment: first, since the tiltrotor combines two lift systems of the rotor and the fixed wing, the aerodynamic environment is complicated during the flight, especially in the transition state, the amount of manipulation that the whole aircraft can provide exceeds Ten, more than 6 control quantities of ordinary trim, ensure the attitude controllability during flight.

Secondly, due to the limitation of design space, it is difficult for conventional propeller hubs to ensure strength and limit weight under large loads. Due to the use of the Y-shaped shaft, the connection method of the bolt (3) is cancelled, the performance of the shaft is weakened and the diameter of the connecting shaft can be effectively reduced. Correspondingly, such as deep groove ball bearing (6), thrust bearing (4) The models of other standard parts are correspondingly reduced, which is very helpful for the overall weight reduction of the propeller hub.

After that, the conical ring at the propeller hub has obvious restraint effect on the structural displacement. When the propeller is swung and each isolated axis of the Y-shaped shaft is bent upward, the upper and lower parts of the propeller hub tend to be separated. Due to the existence of the taper This will move the ring to the outside, pushing the blade clamp (1) back to its original position. Or it can be understood that when the shaft is bent upwards, the existence of the taper prevents the ring from sliding inwardly, which limits the separation of the upper and lower propeller hubs.

Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the various embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, as for the device embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and for related parts, please refer to the partial descriptions of the method embodiments. The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical scope disclosed by the present invention can easily think of changes or substitutions. All should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (5)

1. A propeller hub device for a small tilt-rotor aircraft, characterized in that, the propeller hub device is assembled and formed by two parts that are separated up and down, and a circular ring is formed between the upper part (13) and the lower part (14). (15) For restraint, it can be supplemented by gluing; A circular ring (15) is used to connect the upper part (13) and the lower part (14); The lower part (14) of the propeller hub device is connected with the rotor shaft (7) through bolts (3); The Y-shaped shaft is installed between the upper and lower parts of the propeller hub, wherein the Y-shaped shaft is sequentially installed with a first washer, a first deep groove ball bearing, a sleeve, Two deep groove ball bearings, thrust bearings (4), second washers and screws; The inner side of the blade clip (1) is a boss structure, and the boss structure is located between the second deep groove ball bearing and the thrust bearing (4). The centrifugal force generated by each blade, the boss structure is used to transmit the centrifugal force load to the thrust bearing (4); A pitch-changing rocker arm (2) is installed on the outside of the root of the blade clip (1), wherein the size of the pitch-changing rocker arm (2) matches the relative position of the control node. 2. The propeller hub device for a small tilt-rotor aircraft according to claim 1, characterized in that the end of the blade clip (1) is connected to the blade through a bolt (3), and the blade clip (1) The other end of the propeller is connected to the propeller hub through an intermediate connecting shaft, and the bolt (3) is used to fix the parts on the intermediate connecting shaft; One end of the pitch-changing rocker arm (2) is connected to the blade clamp (1) through a bolt (3), and the other end of the pitch-changing rocker arm (2) is connected to the pitch-changing pull rod, and is tilted by the automatic tilter. 3 . The propeller hub device for a small tiltrotor aircraft according to claim 2 , wherein the first deep groove ball bearing and the second deep groove ball bearing are installed in pairs, and the first deep groove ball bearing is installed in a pair. 4 . A sleeve is installed in the middle of a deep groove ball bearing and the second deep groove ball bearing, in the form of a force couple, it bears the moment that the lift generated by the blade is transmitted to the propeller hub in the structure; A specially designed spacer (5) is installed on the outboard end of the Y-shaft. 4. The propeller hub device for a small tilt-rotor aircraft according to claim 1, wherein the components of the automatic tilter include a moving ring (8) and a fixed ring (12), and the fixed ring (12) ) is divided into upper and lower parts and connected with screws, the fixed ring (12) is nested on the spherical hinge, and the rollers are installed between the moving ring (8) and the fixed ring (12). 5. The propeller hub device for a small tilt-rotor aircraft according to claim 4, wherein a motor is connected below the rotor shaft (7) for transmitting the torque output by the motor; The moving ring (8), the first harpoon-shaped member (9) and the second harpoon-shaped member (10) of the automatic tilter form a torsion arm, and the torsion arm is used to drive the moving ring (8) to rotate together with the rotor.

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