A broadband stable vibration isolation device for a helicopter gearbox

Abstract

The present invention relates to the field of vibration isolation technology, and particularly to a broadband stable vibration isolation device for a helicopter gearbox, comprising a frame; a quasi-zero stiffness vibration isolator installed on the frame; a metamaterial support rod, which is a mass-amplified nonlinear metamaterial structure, one end of which is rigidly connected to the gearbox and the other end of which is rigidly connected to the quasi-zero stiffness vibration isolator. The metamaterial support rod includes a housing, a support rod column, and a plurality of unit cells; the housing covers the support rod column, and the unit cells are arranged along the axial direction of the support rod column and extend radially to be connected to the housing. The present invention realizes a mid-high frequency broadband vibration isolation band gap through the design of the metamaterial support rod, and can achieve broadband vibration isolation through the low-frequency stable vibration isolation of the quasi-zero stiffness.

Description

Technical Field

[0001] The invention relates to the technical field of vibration isolation, and in particular to a wide-frequency-domain stable vibration isolation device for a helicopter gearbox. Background Art

[0002] With the promotion of application fields, helicopter technology has made great progress, but high vibration levels are still a problem that plagues its development. Reducing helicopter vibration has always been one of the most critical issues that need to be solved in the process of helicopter development.

[0003] There are a large number of vibration sources in the flight of a helicopter, such as the rotor and tail rotor system, transmission system, engine, hydraulic device, aerodynamic force, etc., which make the helicopter dynamic environment relatively harsh, resulting in poor ride comfort, fatigue damage of parts, affecting the function of parts and onboard equipment, reducing the reliability of helicopter parts and equipment, and increasing the cost of use and maintenance.

[0004] In terms of helicopter vibration reduction technology, measures such as rotor vibration absorption, fuselage vibration absorption, and vibration isolation have been developed. Compared with the vibration absorption method, vibration isolation has a higher vibration reduction efficiency in theory and is taken into consideration during the design. According to the structural characteristics of the helicopter, vibration isolation is a method of installing a corresponding vibration isolation system between the helicopter main reducer and the fuselage to isolate the exciting force from the helicopter fuselage to reduce the vibration level of the helicopter.

[0005] However, the existing vibration isolation system can isolate vibrations in a narrow frequency domain and the vibration isolation is unstable, and cannot achieve stable vibration isolation in a wide frequency domain. Summary of the invention

[0006] The purpose of the present invention is to provide a wide-frequency stable vibration isolation device for a helicopter gearbox to solve the problem that the existing vibration isolation system can isolate vibrations in a narrow frequency range and the vibration isolation is unstable. In order to achieve the above purpose, the present invention solves the problem through the following technical solutions:

[0007] The present invention provides a wide-frequency stable vibration isolation device for a helicopter gearbox, comprising:

[0008] frame;

[0009] A quasi-zero stiffness vibration isolator mounted on the frame;

[0010] The metamaterial support rod is a mass-amplified nonlinear metamaterial structure, one end of which is rigidly connected to the gearbox, and the other end of which is rigidly connected to the quasi-zero stiffness isolator. The metamaterial support rod includes a shell, a support rod column and a plurality of cells.

[0011] The shell covers the support rod column, and the cells are arranged axially along the support rod column and radially extend to be connected to the shell.

[0012] As a further technical solution, a plurality of the metamaterial support rods are provided and distributed around the gearbox, and each of the metamaterial support rods is configured with one of the quasi-zero stiffness vibration isolators.

[0013] As a further technical solution, the metamaterial support rods are uniformly arranged around the gearbox.

[0014] As a further technical solution, the unit cell is composed of a plurality of oscillators and a plurality of rubber beams, and the oscillators are connected by the rubber beams to form a mass amplification structure.

[0015] As a further technical solution, the thickness and stiffness of the rubber beams on the outer side and the diagonal of the unit cell are greater than those of the remaining rubber beams.

[0016] As a further technical solution, the unit cells are radially distributed along the support rod column at a set angle.

[0017] As a further technical solution, the housing is in a cylindrical shape.

[0018] As a further technical solution, the quasi-zero stiffness vibration isolator is realized by connecting a negative stiffness mechanism in parallel to a positive stiffness mechanism.

[0019] As a further technical solution, the negative stiffness mechanism includes two negative stiffness elastic members, the positive stiffness mechanism includes a positive stiffness elastic member, the positive stiffness elastic member is rigidly connected to the end of the metamaterial support rod, and the two negative stiffness elastic members are connected to the side of the end of the metamaterial support rod.

[0020] As a further technical solution, the negative stiffness elastic member is configured with a piezoelectric actuator for adjusting its stiffness, and a controller for driving the piezoelectric actuator to act.

[0021] The beneficial effects of the present invention are as follows:

[0022] (1) The metamaterial support rod of the present invention is a mass amplification type nonlinear metamaterial structure, which can significantly increase the effective mass of the system during vibration to achieve the purpose of reducing the frequency. Utilize the characteristics of the metamaterial to isolate medium and high frequency vibrations to achieve medium and high frequency broadband vibration isolation. Utilize the mass amplification type nonlinear metamaterial structure to realize a wider bandgap with a smaller additional mass, thereby improving the vibration isolation performance; the positive stiffness and negative stiffness of the quasi-zero stiffness vibration isolator cancel each other out, making the dynamic stiffness of the system at the equilibrium position zero, thereby realizing low-frequency stable vibration isolation.

[0023] (2) In the present invention, the unit cell is composed of a plurality of oscillators and a plurality of rubber beams, and the oscillators are connected by the rubber beams to form a mass amplification structure, so that the metamaterial support rod forms a mass amplification type nonlinear metamaterial structure. The specific arrangement form of the oscillators is designed according to the vibration isolation frequency requirements to realize vibration isolation in different medium and high frequency domains.

[0024] (3) The negative stiffness elastic member of the present invention is configured with a piezoelectric actuator for adjusting its stiffness, and a controller for driving the piezoelectric actuator to act. The controller controls the piezoelectric actuator to adjust the stiffness of the negative stiffness elastic member, so as to achieve stable vibration isolation at low frequencies. Description of the Drawings

[0025] The attached drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute a limitation to the present invention. It should also be understood that these drawings are shown for simplicity and clarity and are not necessarily drawn to scale. The present invention will now be described and explained with additional features and details by using the drawings, wherein:

[0026] Figure 1 Shows a schematic structural diagram of the vibration isolation device in an embodiment of the present invention;

[0027] Figure 2 Shows a sectional view of the metamaterial support rod along the axial direction in an embodiment of the present invention;

[0028] Figure 3 Shows a top view schematic diagram of the metamaterial support rod in an embodiment of the present invention;

[0029] Figure 4 Shows a schematic diagram of the unit cell structure inside the metamaterial support rod in an embodiment of the present invention;

[0030] Figure 5 Shows a schematic internal structure diagram of the quasi-zero stiffness vibration isolator in an embodiment of the present invention;

[0031] Figure 6 Shows the schematic principle diagram of the quasi-zero stiffness vibration isolator.

[0032] In the figure: 1, gearbox; 2, metamaterial support rod; 3, quasi-zero stiffness vibration isolator; 4, frame; 21, housing; 22, unit cell; 23, support rod column; 221, rubber beam; 222, oscillator; 31, positive stiffness spring; 32, negative stiffness elastic member; 33, piezoelectric actuator; 5, negative stiffness element; 6, positive stiffness element. Detailed Embodiments

[0033] Next, the technical solutions in the typical embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention.

[0034] As described in the background art, the traditional vibration isolation system can isolate vibrations in a relatively short frequency domain. When facing complex vibration conditions in a wide frequency domain, it is difficult to ensure the vibration isolation effect. To solve the above technical problems, the embodiments of the present invention propose a wide-frequency domain stable vibration isolation device for a helicopter gearbox, as Figure 1As shown, it includes a frame 4, a quasi-zero stiffness vibration isolator 3, and a metamaterial support rod 2.

[0035] The frame 4 is a plate-like structure for mounting the quasi-zero stiffness vibration isolator 3.

[0036] As Figure 2 and Figure 3 shown, the metamaterial support rod 2 is a mass-amplified nonlinear metamaterial structure. There are multiple metamaterial support rods 2, four in this embodiment, evenly distributed around the gearbox 1. In some other embodiments, it is not limited to the four in this embodiment. One end of the metamaterial support rod 2 is rigidly connected to the gearbox 1, and the other end is rigidly connected to the quasi-zero stiffness vibration isolator 3. The metamaterial support rod 2 includes a housing 21, a support rod column 23, and a number of unit cells 22;

[0037] The housing 21 covers the support rod column 23. The unit cells 22 are arranged along the axial direction of the support rod column 23 and extend radially to connect with the housing 21.

[0038] The metamaterial support rod 2 is a mass-amplified nonlinear metamaterial structure, which can significantly increase the effective mass of the system during vibration, achieving the purpose of reducing the frequency. Utilizing the characteristics of the metamaterial to isolate medium and high-frequency vibrations to achieve medium and high-frequency broadband vibration isolation. By using the mass-amplified nonlinear metamaterial structure, a wider bandgap can be achieved with a smaller additional mass, thereby improving the vibration isolation performance.

[0039] As Figure 3 shown, the unit cells 22 are distributed radially along the support rod column 23 at a set angle. The set angle in this embodiment is 60°. The unit cells in the same radial direction are grouped. Since the set angle is 60°, there are six groups of unit cells. In some other embodiments, it is not limited to the 60° in this embodiment.

[0040] As Figure 2 shown, in this embodiment, there are nine unit cells arranged axially along the support rod column 23 in each group, and the unit cells are closely arranged up and down. Both sides of each unit cell are connected to the support rod column 23 and the housing 21 respectively.

[0041] As Figure 4 shown, the unit cell 22 is composed of a number of oscillators 222 and a number of rubber beams 221. The oscillators 222 are connected by the rubber beams 221 to form a mass-amplified structure. In this embodiment, the housing 21 is cylindrical, the cross-section of the unit cell is a square structure, including nine oscillators. The specific arrangement form of the oscillators, the shape of the housing, and the angle between the unit cells can be designed according to the vibration isolation frequency requirements.

[0042] The rubber beams on the outside and the diagonals of the unit cell are thicker and have a greater stiffness, while the other rubber beams are thinner and have a smaller stiffness. The mass of the unit cell is concentrated on the oscillators, and the unit cell as a whole forms a mass-amplified structure.

[0043] As shown Figure 1 in Figure 1 , each metamaterial support rod 2 is configured with a quasi-zero stiffness vibration isolator 3. Therefore, the number of quasi-zero stiffness vibration isolators 3 is also four, which are respectively installed on the frame 4.

[0044] The quasi-zero stiffness vibration isolator 3 is realized by connecting a negative stiffness mechanism in parallel to a positive stiffness mechanism. As shown Figure 6 in Figure 6 , the principle of the quasi-zero stiffness vibration isolator is shown. The quasi-zero stiffness vibration isolator includes two negative stiffness elements 5 and a positive stiffness element 6. One end of the two negative stiffness elements is rigidly connected to the side of the block, and the other end is fixed on the frame. One end of the positive stiffness element is rigidly connected to the bottom of the block, and the other end is fixed on the frame. The positive stiffness cancels out the negative stiffness, making the dynamic stiffness of the system zero at the equilibrium position, thereby achieving low-frequency stable vibration isolation.

[0045] As shown Figure 5 in Figure 5 , in this embodiment, the negative stiffness mechanism includes two negative stiffness elastic members 32, and the positive stiffness mechanism includes a positive stiffness elastic member. The positive stiffness elastic member is a positive stiffness spring 31. The positive stiffness elastic member is rigidly connected to the end of the metamaterial support rod 2, and the two negative stiffness elastic members 32 are connected to the side of the end of the metamaterial support rod 2.

[0046] The negative stiffness elastic member 32 can adopt the structure in the prior art, and is configured with a piezoelectric actuator 33 for adjusting its stiffness, and a controller for driving the piezoelectric actuator 33 to act. One end of the piezoelectric actuator 33 is rigidly connected to the housing of the negative stiffness elastic member 32, and one end of the negative stiffness elastic member 32 is rigidly connected to the metamaterial support rod 2. The quasi-zero stiffness vibration isolator can achieve low-frequency stable vibration isolation. At the same time, the sensor installed on the gearbox transmits the signal to the controller, and the controller controls the piezoelectric actuator to adjust the stiffness of the negative stiffness elastic member 32.

[0047] When the helicopter gearbox is working, the vibration generated by the gearbox 1 is transmitted to the metamaterial support rod 2. The characteristics of the metamaterial for isolating medium and high frequency vibrations are utilized to achieve medium and high frequency wide-band vibration isolation. The vibration is transmitted downward to the quasi-zero stiffness vibration isolator 3. The quasi-zero stiffness vibration isolator 3 can achieve low-frequency stable vibration isolation. At the same time, the sensor installed on the gearbox 1 transmits the signal to the controller, and the controller controls the piezoelectric actuator 33, and then adjusts the stiffness of the negative stiffness elastic member 32 to achieve stable vibration isolation in the low-frequency domain.

[0048] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and decorations made to the above embodiments based on the technical essence of the present invention without departing from the technical solutions of the present invention all belong to the protection scope of the technical solutions of the present invention.

Claims

1. A broadband stable vibration isolation device for a helicopter gearbox, characterized in that, it includes: a frame; a quasi-zero stiffness vibration isolator installed on the frame; a metamaterial support rod, which is a mass-amplified nonlinear metamaterial structure, one end of which is rigidly connected to the gearbox and the other end is rigidly connected to the quasi-zero stiffness vibration isolator. The metamaterial support rod includes a housing, a support rod column and a number of unit cells; the unit cells are composed of a number of oscillators and a number of rubber beams, and the oscillators are connected by the rubber beams to form a mass-amplified structure; the housing covers the support rod column, the unit cells are arranged along the axial direction of the support rod column and extend radially to connect with the housing.

2. The broadband stable vibration isolation device for a helicopter gearbox according to claim 1, characterized in that, a plurality of the metamaterial support rods are provided and distributed around the gearbox, and each of the metamaterial support rods is configured with a quasi-zero stiffness vibration isolator.

3. The broadband stable vibration isolation device for a helicopter gearbox according to claim 2, characterized in that, the metamaterial support rods are evenly arranged around the gearbox.

4. The broadband stable vibration isolation device for a helicopter gearbox according to claim 1, characterized in that, the thickness and stiffness of the rubber beams on the outer side and the diagonal of the unit cell are greater than those of the remaining rubber beams.

5. The broadband stable vibration isolation device for a helicopter gearbox according to claim 1, characterized in that, the unit cells are radially distributed along the support rod column at a set angle.

6. The broadband stable vibration isolation device for a helicopter gearbox according to claim 5, characterized in that, the housing is in a cylindrical shape.

7. The broadband stable vibration isolation device for a helicopter gearbox according to claim 1, characterized in that, the quasi-zero stiffness vibration isolator is realized by connecting a negative stiffness mechanism in parallel to a positive stiffness mechanism.

8. The broadband stable vibration isolation device for a helicopter gearbox according to claim 7, characterized in that, the negative stiffness mechanism includes two negative stiffness elastic members, the positive stiffness mechanism includes a positive stiffness elastic member, the positive stiffness elastic member is rigidly connected to the end of the metamaterial support rod, and the two negative stiffness elastic members are connected to the side of the end of the metamaterial support rod.

9. The broadband stable vibration isolation device for a helicopter gearbox according to claim 8, characterized in that, the negative stiffness elastic member is configured with a piezoelectric actuator for adjusting its stiffness, and a controller for driving the piezoelectric actuator to act.

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