Axial hinge structure of rotor hub

Abstract

The invention belongs to the field of rotor systems, and particularly relates to an axial hinge structure of a rotor hub. Comprising a four-point contact ball bearing (1), a thrust ball bearing (2), a torque transmission pin (3), a blade root (4), a lubricating grease sealing ring (5), a connecting screw (6), a variable pitch rocker arm (8) and a small anti-rotation stop block (9). The combined design can meet the bearing requirement of rotor wing loads under the working condition of a wide rotating speed range; the four-point contact ball bearing is pressed through the variable pitch rocker arm, and the outer ring structure of the bearing is additionally provided with a small stop dog and a lubricating check ring, so that the bearing is conveniently circumferentially positioned and the lubricating effect is improved; and the thrust ball bearing adopts a split combined mounting mode, so that the structure is very convenient to dismount and mount, and the structure is convenient to maintain.

Description

Technical Field

[0001] The invention belongs to the field of rotor systems, and in particular relates to an axial hinge structure of a rotor hub. Background Art

[0002] The axial hinge of the rotor hub bears the centrifugal force of the rotating blades and the complex flapping and swinging bending moments. For the axial hinge structure with high speed and relatively large centrifugal force, a combination of thrust ball bearings and needle roller bearings is often used. The thrust ball bearing bears most of the centrifugal force and the flapping and swinging bending moments, and the needle roller bearing bears the radial force and has a centering effect. However, for low speed and relatively small centrifugal force usage scenarios, the thrust ball bearing is insufficient to bear the bending moment, and the bending moment load will be transmitted to the needle roller bearing, causing the needle roller bearing to be easily damaged. At the same time, the hub axial hinge also has strict requirements on the compactness of the structure and the ease of installation. Summary of the invention

[0003] Purpose of the invention: To provide a rotor hub axial hinge structure to meet the bearing requirements of the rotor load under a wide speed range.

[0004] Technical solution:

[0005] A rotor hub axial hinge structure, comprising: a four-point contact ball bearing 1, a thrust ball bearing 2, a torque transmission pin 3, a blade root 4, a grease seal 5, a connecting screw 6, a pitch rocker arm 8, and a small anti-rotation stopper 9, wherein the outer ring of the four-point contact ball bearing 1 is clearance-matched with an annular groove on a hub shell; the outer ring structure of the four-point contact ball bearing 1 contains a chamfered groove for cooperating with the small anti-rotation stopper 9 fixed on the hub shell to prevent the outer ring of the bearing from circumferentially rotating; the inner ring of the four-point contact ball bearing 1 is pressed against the shoulder side of the blade root 4 by the connecting screw 6; the inner ring of the thrust ball bearing 2 is The inner ring and the outer ring are both split in half and the split surfaces are arranged with a 90° offset when installed; the inner ring of the thrust ball bearing 2 is arranged on the other side of the shoulder of the blade root 4, the end face of the outer ring of the thrust ball bearing 2 is in contact with the hub shell and is pressed by the hub shell under the action of centrifugal force; the pitch rocker arm 8 is pressed against the blade root 4 by the connecting screw 6, and the pitch rocker arm 8 is connected to the blade root 4 by the torque transmission pin 3 to transmit the pitch torque; a grease sealing ring 5 is arranged between the four-point contact ball bearing 1 and the pitch rocker arm 8, and the inner ring of the four-point contact ball bearing 1 is tightly attached to the metal grease sealing ring 5.

[0006] Furthermore, the outer ring of the four-point contact ball bearing 1 is matched with the hub housing with a small clearance.

[0007] Furthermore, the torsion transmission pin 3 and the blade root 4 are in a small clearance fit, and the torsion transmission pin 3 and the pitch-changing rocker arm 8 are in a transition fit.

[0008] Furthermore, a vent hole is designed on the end surface of the torque transmission pin hole on the variable pitch rocker arm 8.

[0009] Furthermore, there is a small clearance fit between the grease seal ring 5 and the hub housing, which can prevent the grease from leaking out after grease injection.

[0010] Furthermore, the thickness of the thrust ball bearing 2 on the side away from the blade root axis is greater than the thickness on the side close to the blade root axis, so that the bearing has a greater ability to withstand bending moments.

[0011] Furthermore, the length of the thrust ball bearing 2 along the blade root axis on the side away from the blade root axis is greater than the length along the blade root axis on the side close to the blade root axis, preventing the bearing from being subjected to radial force.

[0012] Furthermore, the rolling element and the retaining frame 15 of the thrust ball bearing 2 are of a half-split structure, and the split surfaces of the rolling element and the retaining frame 15 and the outer ring are arranged at an interval of 45°, and the split surfaces of the rolling element and the retaining frame 15 and the inner ring are also arranged at an interval of 45°.

[0013] Beneficial effects:

[0014] 1. The thrust ball bearing and four-point contact bearing combined support design configuration uses the thrust bearing to bear all centrifugal forces, and the thrust ball bearing and four-point contact bearing combination bears the swing array bending moment. This combined design can meet the load-bearing requirements of the rotor load under a wide speed range, and the bearing life is longer;

[0015] 2. The four-point contact ball bearing is pressed by a variable pitch rocker arm, and the outer ring structure of the bearing is designed with a small block structure, which can effectively facilitate the circumferential positioning of the bearing;

[0016] 3. The grease retaining ring is pressed and fixed by the inner ring of the four-point contact ball bearing and the variable pitch rocker arm to prevent the grease from overflowing and improve the lubrication effect;

[0017] 4. The thrust ball bearing is installed in a split combination, which greatly facilitates the disassembly and installation of the structure and the maintenance of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a three-dimensional schematic diagram of the axial hinge structure;

[0019] Figure 2 is a cross-sectional view of the axial hinge structure;

[0020] Figure 3 It is a schematic diagram of a split thrust ball bearing;

[0021] Figure 4 This is a schematic diagram of the outer ring anti-rotation stopper and grease leakage prevention of a four-point contact ball bearing;

[0022] Figure 5It is a schematic diagram of the vent hole for easy disassembly and installation of the twist pin;

[0023] Figure 6 It is a schematic diagram of the blade root connection;

[0024] Figure 7 It is a schematic diagram of the integral rubber structure and the plastic split structure.

[0025] Among them, 1. Four-point contact ball bearing, 2. Thrust ball bearing, 3. Torque transmission pin, 4. Blade root, 5. Grease sealing ring, 6. Connecting screws, 7. Fuse, 8. Pitch rocker arm, 9. Anti-rotation block, 10. Pitch rocker arm bushing, 11. Left half outer ring, 12. Right half outer ring, 13. Upper half inner ring, 14. Lower half outer ring, 15. Rolling element and retainer, 16 integral rubber structure, 17 plastic split structure. DETAILED DESCRIPTION

[0026] The axial hinge structure supported by a thrust ball bearing and a four-point contact bearing in combination of the present invention utilizes the thrust bearing to bear all centrifugal forces, and the thrust ball bearing and the four-point contact bearing in combination bear the flapping bending moment. This combined design can meet the load-bearing requirements of the rotor load under a wider speed range. The four-point contact ball bearing is clamped by a variable pitch rocker arm, and the outer ring structure of the bearing is provided with a small block and a lubricating retaining ring, which facilitates the circumferential positioning of the bearing and improves the lubrication effect. The thrust ball bearing is installed in a split combined manner, which greatly facilitates the disassembly and installation of the structure and is easy to maintain.

[0027] like Figure 1-7 , a rotor hub axial hinge structure, comprising: a four-point contact ball bearing 1, a thrust ball bearing 2, a torque transmission pin 3, a blade root 4, a grease seal 5, a connecting screw 6, a pitch rocker arm 8, and a small anti-rotation block 9, wherein the outer ring of the four-point contact ball bearing 1 is clearance-matched with the annular groove on the hub shell; the outer ring structure of the four-point contact ball bearing 1 contains a chamfered groove for cooperating with the small anti-rotation block 9 fixed on the hub shell to prevent the outer ring of the bearing from circumferential rotation; the inner ring of the four-point contact ball bearing 1 is pressed against the shoulder side of the blade root 4 by the connecting screw 6; the inner ring of the thrust ball bearing 2 The inner ring and the outer ring are both split in half and the split surfaces are arranged with a 90° offset when installed; the inner ring of the thrust ball bearing 2 is arranged on the other side of the shoulder of the blade root 4, the end face of the outer ring of the thrust ball bearing 2 is in contact with the hub shell and is pressed by the hub shell under the action of centrifugal force; the pitch rocker arm 8 is pressed against the blade root 4 by the connecting screw 6, and the pitch rocker arm 8 is connected to the blade root 4 by the torque transmission pin 3 to transmit the pitch torque; a grease sealing ring 5 is arranged between the four-point contact ball bearing 1 and the pitch rocker arm 8, and the inner ring of the four-point contact ball bearing 1 is tightly attached to the metal grease sealing ring 5.

[0028] The outer ring of the four-point contact ball bearing 1 is matched with the hub housing with a small clearance.

[0029] The torque transmission pin 3 is matched with the blade root 4 in a small clearance, and the torque transmission pin 3 is matched with the variable pitch rocker arm 8 in a transitional manner. The end face of the torque transmission pin hole on the variable pitch rocker arm 8 is designed with a vent hole.

[0030] The grease seal ring 5 and the hub housing are matched with a small gap to prevent the grease from leaking out after grease injection. The thickness of the thrust ball bearing 2 on the side away from the blade root axis is greater than the thickness on the side close to the blade root axis, so that the bearing has a greater ability to withstand bending moments.

[0031] The length of the thrust ball bearing 2 along the blade root axis on the side away from the blade root axis is greater than the length along the blade root axis on the side close to the blade root axis, preventing the bearing from being subjected to radial force.

[0032] The rolling element and the retainer 15 of the thrust ball bearing 2 are of a half-split structure, with the rolling element and the retainer 15 and the split surfaces of the outer ring arranged at an interval of 45°, and the rolling element and the retainer 15 and the split surfaces of the inner ring also arranged at an interval of 45°.

[0033] In order to improve the sealing performance of the structure under the action of centrifugal force, a sealing structure is arranged between the hub shell and the blade root 4, and the sealing structure includes an integral rubber structure 16 and a plastic split structure 17. The plastic split structure 17 is composed of a left half ring of the plastic split structure and a right half ring of the plastic split structure. The two half-ring supporting plastics are concave and convex and are embedded in each other, which can prevent the supporting plastic from axial misalignment. This can effectively support the integral rubber structure 16, and can directly cross over the blade root shaft of the combined installation stepped shaft configuration, which is convenient for disassembly and installation.

[0034] When installing the sealing structure, first directly fit the left half ring of the plastic split structure 17 and the right half ring together to install the blade root shaft with the stepped shaft configuration, then stretch the integral rubber structure 16 across the convex shoulder passing through the blade root shaft, and put it on the two half ring supporting plastics of the plastic split structure merged with the blade root shaft. The integral rubber structure 16 will seal the blade root shaft and the two sides of the sealing groove of the hub shell securely due to the elastic tension force, and finally merge the upper and lower shells of the hub to complete the installation of the sealing assembly. When disassembling, the steps are opposite to the installation steps. When the blade root shaft rotates with variable pitch, it will drive the integral rubber structure 16 and the plastic split structure 17 to rotate relative to the sealing groove of the hub shell, and the sealing structure will effectively seal the cylindrical surface of the blade root shaft and the two sides of the sealing groove of the hub shell securely. It isolates dust and rain from the outside, and also prevents grease from leaking along the blade root shaft.

[0035] Compared with conventional sealing structures, the sealing structure is composed of an integral rubber structure 16 superimposed on a plastic split structure 17, and can be used for stepped shaft structures with high ends and low middle where conventional sealing structures cannot be installed, and is easy to install, disassemble and maintain.

[0036] The plastic split structure 17 of the sealing structure is composed of a plastic split structure left half ring and a plastic split structure right half ring, and the two half rings support the plastic concave and convex inlay. When supporting the integral rubber structure 16, it can effectively prevent the axial dislocation of the supporting half ring, thereby improving the supporting stiffness of the rubber structure and the reliability of the sealing structure.

[0037] Due to the use of plastic split support, the sealing rubber structure has stronger rigidity, is not easy to deform, and the sealing is firm and reliable.

[0038] The inner diameter of the integral rubber structure 16 is smaller than the inner diameter of the shaft fitting at the root of the blade.

[0039] Example

[0040] An axial hinge structure supported by a thrust ball bearing and a four-point contact bearing in combination. The root of the blade is fixed to a hub shell by using two bearings, a four-point contact ball bearing 1 and a thrust ball bearing 2. The inner and outer rings of the two bearings are clearance-matched. The thrust ball bearing 2 is compressed by the centrifugal force during the rotation of the rotor. The inner ring of the four-point contact ball bearing 1 is compressed to the shoulder position of the root of the blade by four connecting screws 6. The outer ring and the hub shell have a small clearance fit, which allows the outer ring of the four-point contact ball bearing to slide axially in a small range in the hub shell to release the effect of the centrifugal force and also to bear part of the swinging moment load. A pitch rocker arm 8 is compressed to the root 4 of the blade by four connecting screws 6, which mainly plays an axial fixing role. Axial positioning and torque transmission are mainly transmitted by a torque transmission pin 3 connecting the pitch rocker arm 8 and the root 4 of the blade. The torque transmission pin 3 is matched with the blade root 4 with a small gap, and is a transition match with the pitch rocker arm 8. The end face of the torque transmission pin hole on the pitch rocker arm 8 is designed with a vent to facilitate the later installation and removal of the torque transmission pin; the inner ring of the four-point contact ball bearing 1 is tightly attached to the metal grease sealing ring 5, and the sealing ring and the hub are matched with a small gap to prevent the leakage of grease after grease injection; the outer ring structure of the four-point contact ball bearing 1 contains a chamfered groove, which can be matched with the small anti-rotation block 9 fixed on the hub shell to facilitate the circumferential positioning of the four-point contact ball bearing; the thrust ball bearing 2 adopts a split combined installation method, which consists of a left half outer ring 11, a right half outer ring 12, an upper half inner ring 13, a lower half outer ring 14, rolling elements and a retaining frame 15, and can be directly placed and installed between the blade root 4 and the hub shell, which greatly facilitates the disassembly and installation of the structure.

[0041] The structure has the following characteristics:

[0042] 1. This axial hinge bearing arrangement can use the thrust bearing 2 to bear all centrifugal forces, and use the thrust ball bearing 1 and the four-point contact bearing 2 to bear the flapping and swing bending moment loads. It can effectively avoid the problems of insufficient clamping force and weak bending resistance of the thrust ball bearing under low speed and small centrifugal force, and can meet the load-bearing requirements of the eVTOL rotor load under a wide speed range.

[0043] 2. The torque transmission pin 3 is matched with the blade root 4 with a small gap, and is transitionally matched with the pitch rocker arm 8. The end face of the torque transmission pin hole on the pitch rocker arm 8 is designed with a vent hole to facilitate the installation and removal of the torque transmission pin in the later stage;

[0044] 3. The inner ring of the four-point contact ball bearing 1 is in close contact with the metal grease seal ring 5, and there is a small gap between the seal ring and the propeller hub, which can effectively prevent the leakage of grease after grease injection;

[0045] 4. The outer ring structure of the four-point contact ball bearing 1 contains a chamfered groove, which can cooperate with the small anti-rotation block 9 fixed on the hub shell to facilitate the circumferential positioning of the four-point contact ball bearing;

[0046] 5. The thrust ball bearing 2 is installed in a split assembly manner and can be directly placed and installed between the blade root and the hub housing, making it easy to disassemble and install the structure.

Claims

1. A rotor hub axial hinge structure, characterized in that: include: Four-point contact ball bearing (1), thrust ball bearing (2), torque transmission pin (3), blade root (4), grease seal (5), connecting screw (6), pitch rocker arm (8), anti-rotation small stopper (9), The outer ring of the four-point contact ball bearing (1) is loosely matched with the annular groove on the hub shell; the outer ring structure of the four-point contact ball bearing (1) contains a chamfered groove for matching with a small anti-rotation block (9) fixed on the hub shell to prevent the outer ring of the bearing from rotating in the circumferential direction; the inner ring of the four-point contact ball bearing (1) is pressed against the shoulder side of the blade root (4) by a connecting screw (6); the inner ring and the outer ring of the thrust ball bearing (2) are both split in half and the split surfaces are arranged with a 90° offset when installed; the inner ring of the thrust ball bearing (2) is arranged The end face of the outer ring of the thrust ball bearing (2) is arranged on the other side of the shoulder of the blade root (4), and is in contact with the hub shell and is pressed by the hub shell under the action of centrifugal force; the pitch rocker arm (8) is pressed against the blade root (4) by a connecting screw (6), and the pitch rocker arm (8) and the blade root (4) are connected by a torque transmission pin (3) to transmit the pitch torque; a grease seal ring (5) is arranged between the four-point contact ball bearing (1) and the pitch rocker arm (8), and the inner ring of the four-point contact ball bearing (1) is tightly attached to the metal grease seal ring (5).

2. The rotor hub axial hinge structure according to claim 1, characterized in that: The outer ring of the four-point contact ball bearing (1) is matched with the propeller hub shell with a small clearance.

3. The rotor hub axial hinge structure according to claim 1, characterized in that: The torque transmission pin (3) and the blade root (4) are in a small clearance fit, and the torque transmission pin (3) and the pitch-changing rocker arm (8) are in a transition fit.

4. The rotor hub axial hinge structure according to claim 1, characterized in that: The end surface of the torque transmission pin hole on the pitch-changing rocker arm (8) is designed with a vent hole.

5. The rotor hub axial hinge structure according to claim 1, characterized in that: The grease seal ring (5) and the propeller hub housing are matched with a small gap, which can prevent the grease from leaking out after grease injection.

6. The rotor hub axial hinge structure according to claim 1, characterized in that: The thickness of the thrust ball bearing (2) on the side away from the blade root axis is greater than the thickness on the side close to the blade root axis, so that the bearing has a greater ability to withstand bending moments.

7. The rotor hub axial hinge structure according to claim 1, characterized in that: The length of the thrust ball bearing (2) along the blade root axis on the side away from the blade root axis is greater than the length along the blade root axis on the side close to the blade root axis, thereby preventing the bearing from bearing radial force.

8. The rotor hub axial hinge structure according to claim 1, characterized in that: The rolling element and the retaining frame (15) of the thrust ball bearing (2) are of a half-split structure, the rolling element and the retaining frame (15) and the split surface of the outer ring are arranged at an interval of 45 degrees, and the rolling element and the retaining frame (15) and the split surface of the inner ring are also arranged at an interval of 45 degrees.

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