A piezoelectric negative stiffness collaborative vibration absorption strut for dynamic load of a helicopter rotor

Abstract

The present application relates to a kind of piezoelectric negative stiffness collaborative vibration-absorbing strut for helicopter rotor dynamic load, including upper strut and lower strut, and the vibration-absorbing component for vibration isolation between upper strut and lower strut;The vibration-absorbing component includes auxiliary ring for bearing static load, lever spring and disc spring for realizing providing negative stiffness, adjustable precompression are equipped in the auxiliary ring, mass for absorbing and dissipating vibration energy is equipped below the disc spring; Lever spring side is contacted with piezoelectric ceramic stack, piezoelectric ceramic stack connects multiple mode external circuit module, forms multiple mode piezoelectric shunt damping effect, while controlling multiple mode component of system;When vibration is larger, store electric energy, when vibration is smaller, switch to multiple mode RLC circuit dissipating mode, convert mechanical vibration energy into electric energy and consume by circuit.The present application couples negative stiffness dynamic low-frequency broadband vibration-absorbing and piezoelectric shunt multiple mode suppression, realizes the effect of high-efficiency vibration isolation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vibration control, and particularly relates to a piezoelectric negative stiffness collaborative vibration absorption strut for helicopter rotor dynamic load. BACKGROUND

[0002] The helicopter has strong carrying capacity and strong adaptability to complex environments, and has obvious advantages in heavy transportation, long-distance emergency rescue, urban air traffic and other fields. However, the rotor aerodynamic load of the helicopter in flight will produce severe vibration, which is transmitted to the machine body through the hub-main reducer-strut path, resulting in that the machine body is in a poor vibration environment for a long time. Excessive vibration not only accelerates the fatigue damage of the structure and causes the failure of the key components, but also significantly reduces the safety of the helicopter and the comfort of the passengers. The flight state of the helicopter is variable, and the rotor is subjected to asymmetric and unsteady aerodynamic excitation, resulting in elastic and rigid body motion of the blade; and the alternating force and torque are synthesized at the hub and transmitted to the machine body to produce low-frequency high-amplitude multi-harmonic vibration (12-30 Hz) dominated by the blade frequency (kNΩ, N is the number of blades, and Ω is the rotor speed).

[0003] In view of the above low-frequency vibration problem, various vibration isolators are generally installed between the main reduction and the machine body to reduce the force transmission rate transmitted to the machine body. If a traditional dynamic vibration absorber is used, there are disadvantages such as large additional mass, narrow frequency band, single vibration isolation frequency, etc. If active vibration isolation is used, a corresponding controller, power amplifier, etc. need to be equipped, and the stability of the control algorithm needs to be considered, which increases the complexity of the system.

[0004] Patent ZL202210435412.2 introduces a negative stiffness element in the dynamic vibration absorber, which significantly improves the vibration suppression effect of low-frequency wide amplitude while ensuring static stability; but it only controls a certain modal frequency, and the vibration caused by the rotor dynamic load of the helicopter is low-frequency high-amplitude multi-harmonic vibration, so the vibration suppression effect is limited. In view of this, the present application proposes a new piezoelectric negative stiffness vibration absorption strut on the basis of the original strut. The strut increases an auxiliary ring at the lower part to bear the static load of the machine body; then the auxiliary ring is connected with the negative stiffness dynamic vibration absorber-piezoelectric ceramic stack piezoelectric shunt resistance. When the piezoelectric negative stiffness vibration absorption strut is working, on the one hand, when the natural frequency of the negative stiffness vibration absorber is near the main modal frequency, the vibration absorption block will generate a large resonance inertial reaction force to achieve vibration isolation. On the other hand, during the transmission of vibration, a part of the energy is consumed through the piezoelectric ceramic stack-multiple branch piezoelectric shunt circuit to form an electric damping, realizing multi-modal vibration absorption. Through the coordinated action of the inertial reaction force and the piezoelectric shunt damping, multiple resonance peaks can be controlled at the same time, and multi-modal vibration suppression is realized. SUMMARY

[0005] The present application aims at the problems in the background art and proposes a piezoelectric negative stiffness collaborative vibration absorption strut for helicopter rotor dynamic load.

[0006] The technical scheme of the present application:

[0007] A piezoelectric negative stiffness collaborative vibration-absorbing strut for helicopter rotor dynamic load, comprising upper and lower struts, and a vibration-absorbing assembly arranged between the upper and lower struts for vibration isolation;

[0008] The vibration-absorbing assembly comprises an auxiliary circular ring for bearing static load, a lever spring and a disc spring for providing negative stiffness and adjustable pre-compression are arranged in the auxiliary circular ring, and a mass block for absorbing and dissipating vibration energy is arranged below the disc spring.

[0009] The lever spring is in contact with a piezoelectric ceramic stack on both sides, the piezoelectric ceramic stack is connected to a multi-modal external circuit module, a multi-modal piezoelectric shunt damping effect is formed, and multiple modal components of a control system are controlled.

[0010] When the vibration is large, the electric energy is stored, when the vibration is small, the multi-modal RLC circuit dissipation mode is switched, the mechanical vibration energy is converted into electric energy and consumed through the circuit. An RLC (R represents resistance, L represents inductance, and C represents parallel negative capacitance) network is added to the shunt circuit of the piezoelectric ceramic stack, the parameters of the R are dynamically adjusted through the vibration frequency feedback signal, and the maximum mechanical energy-electric energy conversion efficiency is realized.

[0011] Optionally, a rubber block is arranged in the mass block, a connecting rod is arranged at the central part of the rubber block, and the top end of the connecting rod sequentially penetrates the mass block, the disc spring and the auxiliary circular ring.

[0012] Optionally, a thread is arranged at the top end of the connecting rod, one end of the upper strut is movably connected to the threaded end of the connecting rod, and the negative stiffness value can be adjusted in real time by rotating the connecting rod.

[0013] Optionally, the multi-modal external circuit module is an external energy consumption circuit, the external energy consumption circuit is designed in a bidirectional energy management mode, and the external energy consumption circuit comprises a super capacitor circuit and a variable multi-modal RLC circuit; when the vibration energy is large, the energy consumption circuit cannot dissipate the vibration energy in time, and the vibration energy is stored in the super capacitor; when the vibration energy is small, the dissipation mode is switched.

[0014] Optionally, the vibration-absorbing strut is mounted on a machine body, a main reduction gear is arranged above the machine body, two upper struts for transmitting vibration are arranged on both sides of the main reduction gear, and two groups of lower struts for transmitting vibration are arranged at the top of the machine body.

[0015] Optionally, a protective structure for protecting the vibration-absorbing assembly is arranged outside the auxiliary circular ring.

[0016] Compared with the prior art, the present application has the following beneficial technical effects:

[0017] 1. The present application realizes low-frequency vibration isolation by setting an adjustable pre-compression disc spring module, rubber, a mass block, a lever spring, a piezoelectric ceramic stack and an external circuit module, wherein the disc spring can serve the purpose of negative stiffness, and the rubber and the mass block form a negative stiffness dynamic vibration absorber, so that low-frequency vibration isolation can be realized.

[0018] 2. The present application couples negative stiffness dynamic low-frequency broadband vibration absorption and piezoelectric shunt multi-modal suppression damping by means of a piezoelectric ceramic stack and an external circuit module, so as to realize the effect of efficient vibration isolation.

[0019] 3. The disc spring can realize real-time adjustment of stiffness through a connecting rod, so as to improve the frequency adaptability of the traditional device, and bidirectional energy distribution improves energy efficiency, and the device is good in post-maintenance controllability. DETAILED DESCRIPTION

[0020] Figure 1 A perspective structural schematic diagram of the present application is given;

[0021] Figure 2 A perspective schematic diagram of the present application after removing the protective structure is given;

[0022] Figure 3 A front view structural schematic diagram of the vibration absorption assembly in the present application is given;

[0023] Figure 4 An exploded schematic diagram of the protective structure in the present application is given;

[0024] Figure 5 A separation schematic diagram of the connecting rod, rubber block and mass block in the present application is given;

[0025] Figure 6 An enlarged structural schematic diagram of A in the present application is given;

[0026] Figure 7 An enlarged structural schematic diagram of B in the present application is given;

[0027] Figure 8 An enlarged structural schematic diagram of C in the present application is given;

[0028] Figure 9 A running flowchart of the present application is given;

[0029] Figure 10 A piezoelectric ceramic stack matching multi-modal energy dissipation circuit diagram of the present application is given;

[0030] Figure 11A damping effect diagram of the present application is given.

[0031] Reference signs:

[0032] 1, body;

[0033] 2, main reduction;

[0034] 3, connecting frame;

[0035] 4, upper support rod;

[0036] 5, lower support rod;

[0037] 6, vibration absorbing assembly; 601, auxiliary ring; 602, lever spring; 603, piezoelectric ceramic stack; 604, connecting rod; 605, rubber block; 606, mass block; 607, disc spring;

[0038] 7, protection structure; 701, shell one; 702, shell two; 703, slot; 704, positioning hole; 705, plugboard; 706, storage hole; 707, cylindrical spring; 708, guide plate; 709, positioning rod; 710, heat dissipation hole. DETAILED DESCRIPTION

[0039] The technical solutions of the present disclosure will be described clearly and completely below in combination with the drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all the embodiments.

[0040] The components of the embodiments of the present disclosure generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the claimed present disclosure, but only represents selected embodiments of the present disclosure.

[0041] Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present disclosure.

[0042] In the description of the present disclosure, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0043] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific circumstances.

[0044] Example:

[0045] like Figures 1-11 As shown, the present invention proposes a piezoelectric negative stiffness cooperative vibration-absorbing strut for helicopter rotor dynamic loads, including an upper strut 4 and a lower strut 5, and a vibration-absorbing assembly 6 for vibration isolation disposed between the upper strut 4 and the lower strut 5. The system includes a fuselage 1, a main damper 2 located on the top of the fuselage 1, two upper struts 4 for transmitting vibration on both sides of the main damper 2, and two sets of lower struts 5 for transmitting vibration on the top of the fuselage 1.

[0046] The vibration damping assembly 6 includes an auxiliary ring 601 for bearing the static load of the body 1. The main reducer 2 is provided with two connecting brackets 3. The two connecting brackets 3 are respectively movably connected to two upper support rods 4 on their opposite sides. The upper end of the lower support rod 5 passes through the bottom of the auxiliary ring 601 and is movably connected to the inner wall of the bottom of the auxiliary ring 601. The auxiliary ring 601 is provided with a lever spring 602 and an adjustable pre-compression disc spring 607 for achieving the negative stiffness effect.

[0047] The electric negative stiffness collaborative vibration absorption strut also includes a piezoelectric shunt control system. The piezoelectric shunt control system includes a piezoelectric ceramic stack 603 and a variable RLC circuit set on the inner walls of both sides of the auxiliary ring 601. An RLC network is added to the shunt circuit of the piezoelectric ceramic stack 603. The parameters of RL are dynamically adjusted through the vibration frequency feedback signal to maximize the mechanical energy to electrical energy conversion efficiency. The piezoelectric ceramic stack 603 converts mechanical energy into electrical energy and consumes it, thereby effectively reducing vibration and noise in the mechanical system and improving the stability and reliability of the equipment. Below the disc spring 607, there is a mass block 606 for absorbing and dissipating vibration energy. The piezoelectric ceramic stack 603 and the mass block 606 are connected in series or in parallel, and multiple sets are set to form a graded vibration absorption structure.

[0048] The lever spring 602 is in contact with the piezoelectric ceramic stack 603 on both sides. The piezoelectric ceramic stack 603 is connected to the multi-mode external circuit module to form a multi-mode piezoelectric shunt damping effect, and at the same time control multiple modal components of the system.

[0049] When the vibration is large, electrical energy is stored; when the vibration is small, the circuit switches to a multi-mode RLC circuit dissipation mode to convert mechanical vibration energy into electrical energy and consume it through the circuit.

[0050] The multi-modal external circuit module takes three branches as an example, and controls three modal peaks simultaneously; each branch includes a filtering and energy consumption part; that is, each branch controls only one modal component.

[0051] In the shock absorption effect diagram, the frequency response curve comparison of the machine body vibration transmission rate before and after using the device is shown. In the range of 12-30Hz (typical blade frequency vibration band of the helicopter), the vibration amplitude is significantly reduced, and the low-frequency suppression effect is good.

[0052] Multi-modal peak control: multiple resonance peaks are suppressed simultaneously, verifying the synergistic effect of negative stiffness vibration absorption and piezoelectric shunt damping. In addition, the vibration absorption frequency band is widened, covering the main harmonic components of the rotor dynamic load, solving the problem of narrow frequency band of traditional vibration absorbers. Therefore, the application realizes efficient low-frequency vibration isolation and multi-modal energy dissipation, and improves the flight stability and comfort of the helicopter.

[0053] Specifically, the mass block 606 cooperates with the disc spring 607, lever spring 602 and rubber block 605 and other accessories to produce motion opposite to the main vibration when the system is excited by vibration, thereby consuming vibration energy and achieving the purpose of vibration absorption. The rubber block 605 is arranged in the mass block 606, and the rubber block 605 can achieve the purpose of positive stiffness. When subjected to external force, a restoring force opposite to the direction of the external force will be generated, thereby achieving the effect of vibration absorption and isolation. The center part of the rubber block 605 is provided with a connecting rod 604, the top end of the connecting rod 604 sequentially penetrates the mass block 606, the disc spring 607 and the auxiliary circular ring 601. In order to adjust the negative stiffness of the disc spring 607, the top end of the connecting rod 604 is externally provided with threads, and the bottom end of the upper support rod 4 is movably connected with the connecting rod 604. The rotation of the connecting rod 604 can adjust the negative stiffness value of the disc spring 607 in real time.

[0054] In addition to the above-mentioned method of adjusting the negative stiffness value of the disc spring 607, another method can also be provided, such as an electromagnetic adjusting assembly. The electromagnetic adjusting assembly is a coil of electromagnetic coil arranged on the outer side of the bottom of the disc spring 607, and an electromagnet structure is formed in the gap of the upper part. According to the vibration size, the electromagnetic force is automatically adjusted, thereby changing the negative stiffness of the disc spring 607. By changing the magnetic field strength dynamically, the pre-compression amount of the disc spring 607 is adjusted, which is used to adjust the negative stiffness value in real time.

[0055] In order to further protect the device, the outer part of the auxiliary circular ring 601 is provided with a protective structure 7 for protecting the vibration absorbing assembly 6, the protective structure 7 comprises a shell one 701 and a shell two 702, the shell one 701 and the shell two 702 can play a protection role, thereby prolonging the service life of the vibration absorbing assembly 6, the side close to each other of the shell one 701 and the shell two 702 is respectively provided with a plurality of plug boards 705 and plug slots 703, the inner wall of the plug slot 703 is provided with a positioning hole 704, the top of the plug board 705 is provided with a receiving hole 706, a positioning rod 709 is movably arranged in the receiving hole 706, the bottom of the positioning rod 709 is fixedly provided with a guide plate 708, the guide plate 708 and the receiving hole 706 are movably connected, the inner wall of the receiving hole 706 is provided with two limiting grooves, the bottom of the guide plate 708 is fixedly provided with a cylindrical spring 707, the bottom of the cylindrical spring 707 is fixedly connected with the inner wall of the bottom of the receiving hole 706, the outer part of the guide plate 708 is fixedly provided with two limiting blocks, the limiting blocks and the limiting grooves are movably connected, the positioning rod 709 and the positioning hole 704 are matched, and the cooperation of the positioning rod 709, the positioning hole 704, the plug slot 703 and the cylindrical spring 707 can quickly disassemble the shell one 701 and the shell two 702, thereby facilitating the maintenance of the internal elements of the vibration absorbing assembly 6 in the future, and the inner walls of the shell one 701 and the shell two 702 are both provided with a plurality of heat dissipation holes 710, the heat dissipation holes 710 can ensure the heat dissipation performance of the vibration absorbing assembly 6.

[0056] In the embodiment, the upper support rod 4 is used for transmitting vibration, the upper support rod 4 transmits the vibration to the connecting rod 604, the connecting rod 604 transmits the vibration to the disc spring 607, the lever spring 602, the rubber block 605 and the mass block 606, the disc spring 607 and the lever spring 602 can play a negative stiffness role, the mass block 606 cooperates with the above-mentioned accessories, generates a motion opposite to the main vibration when the system is excited by vibration, thereby consuming vibration energy, and achieves the purpose of vibration absorption, the rubber block 605 can play a positive stiffness role, when subjected to an external force, a restoring force opposite to the direction of the external force is generated, thereby playing a vibration absorption and isolation effect, when the piezoelectric ceramic stack 603 transmits vibration, the piezoelectric ceramic stack 603 can convert mechanical energy into electrical energy and consume the electrical energy, thereby effectively reducing vibration and noise in a mechanical system, improving stability and reliability of equipment, and realizing the effect of high-efficiency vibration isolation through negative stiffness dynamic low-frequency wideband vibration absorption and piezoelectric shunt multi-modal resistance damping coupling.

[0057] In the experiment, Figure 1 All the materials of the parts in the system are stainless steel, the density is 7850, and the Poisson's ratio is 0.3; the mass of the main reducer is 950 kg, the mass of the machine body is 2280 kg; the stiffness of the support rod is 3.2e7 N / m, the stiffness of the auxiliary circular ring is 9.2e6 N / m; the rubber stiffness is 7.5e6 N / m, the rubber damping is 150 N·s / m, and the disc spring negative stiffness is -2e6 N / m 2, the mass of the vibration absorber is 15 kg; in addition, the lever spring is 6e6 N / m, the piezoelectric ceramic stack d 33 piezoelectric strain constant 593e-12 m / V, elastic compliance 20.7e-12 m 2 / N), piezoelectric sheet thickness 0.1mm, piezoelectric sheet number 500, piezoelectric sheet area 2.5e-5 m 2 .

[0058] A vertical sweep excitation is applied above the main reducer, and the response is obtained at the machine body. Figure 11 The frequency response function curves of the piezoelectric negative stiffness and the vibration absorber are obtained, and the results show that the installation of the vibration absorber can control the main modes of the first several orders of the vertical vibration of the system, thereby realizing vibration isolation.

[0059] The above specific embodiments are only several optional embodiments of the present application, and based on the technical solutions of the present application and the related inspirations of the above embodiments, those skilled in the art can make various alternative improvements and combinations on the above specific embodiments.

Claims

1. A piezoelectric negative stiffness synergistic vibration-absorbing strut for helicopter rotor dynamic loads, characterized in that: It includes an upper support rod (4) and a lower support rod (5), and a vibration-absorbing assembly (6) for vibration isolation disposed between the upper support rod (4) and the lower support rod (5). The vibration absorption assembly (6) includes an auxiliary ring (601) for bearing static loads. The auxiliary ring (601) contains a lever spring (602) and a disc spring (607) for providing negative stiffness and adjustable pre-compression. Below the disc spring (607) is a mass block (606) for absorbing and dissipating vibration energy. The lever spring (602) is in contact with the piezoelectric ceramic stack (603) on both sides. The piezoelectric ceramic stack (603) is connected to the multi-mode external circuit module to form a multi-mode piezoelectric shunt damping effect, and at the same time control multiple modal components of the system. When the vibration is large, electrical energy is stored; when the vibration is small, the circuit switches to multi-mode RLC circuit dissipation mode to convert mechanical vibration energy into electrical energy and consume it through the circuit. The vibration-absorbing strut is installed on the machine body (1). The main damper (2) is provided on the top of the machine body (1). Two upper struts (4) for transmitting vibration are provided on both sides of the main damper (2). Two sets of lower struts (5) for transmitting vibration are provided on the top of the machine body (1). The mass block (606) contains a rubber block (605), and a connecting rod (604) is provided at the center of the rubber block (605). The top end of the connecting rod (604) passes through the mass block (606), the disc spring (607), and the auxiliary ring (601) in sequence. The multimodal external circuit module is an external energy dissipation circuit. The external energy dissipation circuit is designed with a bidirectional energy management mode, including a supercapacitor circuit and a variable multimodal RLC circuit. When the vibration energy is large, the energy dissipation circuit cannot dissipate the vibration energy in time and store it in the supercapacitor; when the vibration energy is small, it switches to the dissipation mode.

2. The piezoelectric negative stiffness cooperative vibration-absorbing strut for helicopter rotor dynamic load as described in claim 1, characterized in that, The top of the connecting rod (604) is threaded, and one end of the upper support rod (4) is movably connected to the threaded end of the connecting rod (604). The negative stiffness value can be adjusted in real time by rotating the connecting rod (604).

3. The piezoelectric negative stiffness cooperative vibration-absorbing strut for helicopter rotor dynamic load as described in claim 1, characterized in that, The auxiliary ring (601) is provided with a protective structure (7) for protecting the vibration absorption assembly (6).

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