A passive frequency self-tuning device and method

Abstract

This invention relates to the field of vibration control technology, specifically providing a passive frequency self-tuning device and method. The device includes a base, a sliding constraint assembly, an elastic rod, a limiting device, and a mass block. The sliding constraint assembly is fixedly mounted on the base. A sliding constraint channel is provided on the sliding constraint assembly, and the elastic rod passes through the sliding constraint channel and the base, allowing it to slide along the sliding constraint channel. The limiting device is disposed on the elastic rod to limit its sliding stroke. The mass block is disposed at the end of the elastic rod furthest from the base. The passive frequency self-tuning device provided by this invention has a simple structure, requires no external power supply, and achieves effective wideband self-tuning through a purely mechanical structure.

Description

Technical Field

[0001] This invention relates to the field of vibration control technology, and in particular to a passive frequency self-tuning device and method. Background Technology

[0002] In fields such as civil engineering, mechanical engineering, and aerospace, vibration control and energy recovery of structures are of great significance. Traditional vibration energy harvesting (such as piezoelectric energy harvesters) or control devices (such as tuned mass dampers, TMDs) are usually based on the principle of linear resonance, with a fixed natural frequency. While they have the advantage of simple structure, they have an extremely narrow operating bandwidth, only working efficiently near their natural resonant frequency. However, vibrations in actual engineering environments often have time-varying, random, or broadband characteristics. Once the environmental excitation frequency deviates from the device's natural frequency, a "detuning" phenomenon occurs, the output power of the energy harvesting device decays rapidly, the vibration damping effect of the dynamic vibration absorber fails, and environmental adaptability is poor.

[0003] To address the frequency "detuning" problem, researchers have primarily developed three technical approaches. Multimodal methods broaden the response bandwidth by integrating multiple vibrating elements with different resonant frequencies into the system. Nonlinear methods introduce nonlinear forces (such as magnetic repulsion, mechanical collisions, or spring preload) to induce multistable characteristics or hardening / softening effects, thereby extending the high-energy response to a specific frequency range. Self-tuning methods aim to enable the device to actively or passively adjust its own resonant frequency to match the ambient vibration frequency in real time. However, active and semi-active tuning rely on sensors, actuators, and external power supplies, resulting in high maintenance costs and limited system reliability.

[0004] In contrast, passive self-tuning relies on purely mechanical components, using the vibration of the main structure as the driving energy. When the response exceeds a set threshold, it automatically adjusts damping, stiffness, or equivalent mass. Such devices require no external power supply, have a simple structure, and are highly robust. However, research on existing related devices remains limited.

[0005] Therefore, there is an urgent need to develop a passive frequency self-tuning device and method to improve the efficiency and practicality of vibration energy harvesting and vibration control. Summary of the Invention

[0006] The purpose of this invention is to provide a passive frequency self-tuning device and method, the specific technical solution of which is as follows: A passive frequency self-tuning device includes a base, a sliding constraint assembly, an elastic rod, a limiting device, and a mass block; The sliding constraint component is fixedly mounted on the base; the sliding constraint component is provided with a sliding constraint channel, and the elastic rod passes through the sliding constraint channel and the base, and can slide along the sliding constraint channel; The limiting device is disposed on the elastic rod and is used to limit the sliding stroke of the elastic rod; The mass block is positioned at the end of the elastic rod furthest from the base.

[0007] Furthermore, the sliding constraint assembly includes a slide rail frame and multiple sets of pulleys; The slide rail frame is vertically mounted on the base. Two rows of pulleys are symmetrically arranged along the axial direction of the slide rail frame. The pulleys are connected to the slide rail frame via a mounting shaft and are rotatably mounted on the mounting shaft. A sliding constraint channel is formed between the two rows of pulleys; the elastic rod is located at the center of the sliding constraint channel and is tactilely connected to the two rows of pulleys; The base is provided with mounting holes for inserting elastic rods, and the mounting holes are correspondingly provided with sliding constraint channels.

[0008] Furthermore, the limiting device includes a first limiting plate and a second limiting plate; The first limiting plate is located at one end of the elastic rod that protrudes from the base, and is used to prevent the elastic rod from coming out of the base or the sliding constraint channel; The second limiting plate is positioned between the sliding constraint component and the mass block.

[0009] Furthermore, the horizontal projected area of ​​the first limiting plate is larger than the area of ​​the mounting hole; the horizontal projected area of ​​the second limiting plate is larger than the top opening area of ​​the sliding constraint channel.

[0010] Furthermore, it also includes a piezoelectric element, which is attached to the elastic rod for energy harvesting.

[0011] A passive frequency self-tuning method, using the passive frequency self-tuning device described above for tuning, includes the following steps; The passive frequency self-tuning device is placed in a vibration environment, causing the base to vibrate laterally with external excitation; Lateral vibration is used to induce bending deformation of the elastic rod at the top opening of the sliding constraint assembly, generating a sectional bending moment. This generates a configurational force along the axis of the elastic rod; Adjust the installation direction of the passive frequency self-tuning device and the mass of the mass block to make the configuration force and the gravitational component along the axis of the elastic rod form a balance relationship with opposite directions; When the external excitation frequency or amplitude changes, the configuration force changes with the lateral response amplitude of the elastic rod. The difference between the configuration force and the gravity component drives the elastic rod to slide axially within the sliding constraint assembly, thus increasing the effective length of the elastic rod. The system automatically adjusts until a dynamic balance is achieved between the configuration force and the gravitational component, thereby causing the natural frequency of the passive frequency self-tuning device to passively approach the external excitation frequency, thus realizing passive frequency self-tuning.

[0012] Furthermore, the magnitude of the configuration force is related to the section bending moment generated by the elastic rod at the top opening of the sliding constraint assembly. The squares are positively correlated.

[0013] Furthermore, the effective length of the elastic rod Regulation is expressed through the following relationship: ; in, For the equivalent mass of the device, These are the equivalent damping parameters of the device. For configurational forces, For the amplitude of the elastic rod, Indicates the curvature of the elastic rod. For the bending stiffness of the elastic rod, The angle between the axis of the elastic rod and the horizontal line. This represents the first derivative of the effective length with respect to time. It represents the second derivative of the effective length with respect to time.

[0014] Furthermore, by adjusting the angle between the axis of the elastic rod and the horizontal line... To realize the gravitational component The size is adjusted, thereby adjusting the effective operating bandwidth of the passive frequency self-tuning device.

[0015] Furthermore, during the self-tuning process, the piezoelectric element placed on the surface of the elastic rod converts the mechanical energy generated by the bending deformation of the elastic rod into electrical energy.

[0016] The application of the technical solution of the present invention has at least the following beneficial effects: (1) This invention provides a passive frequency self-tuning device, comprising a base, a sliding constraint assembly, an elastic rod, a limiting device, and a mass block; the sliding constraint assembly is fixedly disposed on the base; a sliding constraint channel is provided on the sliding constraint assembly, the elastic rod passes through the sliding constraint channel and the base, and can slide along the sliding constraint channel; the limiting device is disposed on the elastic rod to limit the sliding stroke of the elastic rod; the mass block is disposed at the end of the elastic rod away from the base. The passive frequency self-tuning device provided by this invention has a simple structure, requires no external power supply, and achieves effective self-tuning over a wide frequency range through a purely mechanical structure, making it highly practical.

[0017] (2) The passive frequency self-tuning device provided by the present invention can automatically adjust the effective length of the elastic rod according to the environmental vibration frequency, so that the passive frequency self-tuning device can always maintain a large oscillation state close to resonance in a wide frequency band, which significantly improves the efficiency of vibration control and energy harvesting in the variable frequency environment.

[0018] (3) In this invention, to address the problem that the elastic rod of the passive frequency self-tuning device is prone to slippage failure during startup, vibration, or non-operation, a limiting device is added to the elastic rod, namely a first limiting plate and a second limiting plate. The size of the first limiting plate is larger than the size of the mounting hole on the base, and the size of the second limiting plate is larger than the top opening size of the sliding constraint channel. When the elastic rod slides down or up to its limit position or the device stops vibrating, the first limiting plate and the second limiting plate form a mechanical stop. This not only effectively prevents the elastic rod from accidentally falling off and ensures the structural safety of the entire device, but also provides a stable initial placement position for the elastic rod.

[0019] (4) In this invention, the sliding constraint assembly forms a low-friction sliding constraint channel through two rows of pulleys. The elastic rod is connected to the two rows of pulleys in a rolling manner, which converts the sliding friction during the movement of the elastic rod into rolling friction, greatly reducing the resistance. This allows the configuration force generated by the passive frequency self-tuning device to overcome the frictional resistance and drive the elastic rod to slide even under weak environmental vibration excitation, thereby reducing the start-up threshold of the passive frequency self-tuning device and expanding the applicability of the passive frequency self-tuning device in vibration environments.

[0020] (5) The present invention provides a passive frequency self-tuning method. The method is based on the bending deformation of the elastic rod at the top opening of the sliding constraint channel caused by external lateral vibration, thereby generating a configuration force along the axis of the elastic rod. By constructing a dynamic balance mechanism between the configuration force and gravity, the elastic rod is driven to slide spontaneously in the sliding constraint channel according to the change of excitation frequency, and the effective length of the elastic rod is adjusted in real time to realize the passive tracking and self-tuning of the frequency to the external excitation frequency.

[0021] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the passive frequency self-tuning device in an embodiment of the present invention; Figure 2 This is a schematic diagram showing the passive frequency self-tuning device tilted in an embodiment of the present invention; Figure 3 This is a schematic diagram of the sliding constraint component in an embodiment of the present invention; Figure 4 This is a schematic diagram showing the limiting device and mass block provided for the elastic rod in an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the operating principle of the passive frequency self-tuning device in an embodiment of the present invention. Figure 6 The vibration time history curve of the passive frequency self-tuning device in this embodiment of the invention; Figure 7 This is a schematic diagram of the tuning result of the passive frequency self-tuning device in an embodiment of the present invention; The reference numerals in the attached diagram are as follows: 1. Base; 2. Sliding constraint assembly; 2.1. Slide frame; 2.2. Pulley; 3. Elastic rod; 4. Limiting device; 4.1. First limiting plate; 4.2. Second limiting plate; 5. Mass block. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "front", "back", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0026] Example: See Figures 1-4 This embodiment proposes a passive frequency self-tuning device, including a base 1, a sliding constraint component 2, an elastic rod 3, a limiting device 4, and a mass block 5; The base 1 serves as the supporting foundation for the entire passive frequency self-tuning device, used to receive external vibrations (such as those from bridges and buildings) and transmit the vibrations to the elastic rod 3, the limiting device 4, and the mass block 5. The sliding constraint assembly 2 is fixedly mounted on the base 1 by bolts to ensure that the sliding constraint assembly 2 will not loosen or twist when subjected to severe lateral vibrations, thus ensuring vibration transmission.

[0027] The sliding constraint component 2 is provided with a sliding constraint channel, and the elastic rod 3 passes through the sliding constraint channel and the base 1, and can slide along the sliding constraint channel; like Figure 1 and Figure 3 As shown, the sliding constraint assembly 2 includes a slide rail frame 2.1 and multiple sets of pulleys 2.2. The slide rail frame 2.1 is vertically mounted on the base 1 and is a vertical metal support with a slide rail in its middle. Two rows of pulleys 2.2 are symmetrically arranged along the slide rail axis. The pulleys 2.2 are connected to the slide rail frame 2.1 via a mounting shaft and are rotatably mounted on the mounting shaft via bearings. Preferably, each row of pulleys contains at least three sets of pulleys 2.2 to ensure effective linear constraint of the elastic rod 3. In this embodiment, see [reference needed]. Figure 3 Each column is provided with 5 sets of pulleys 2.2; more preferably, multiple sets of pulleys 2.2 are evenly arranged along the axial direction of the slide groove.

[0028] A sliding constraint channel is formed between the two rows of pulleys 2.2; the elastic rod 3 is disposed at the center of the sliding constraint channel, and the elastic rod 3 is rolledly connected to the two rows of pulleys 2.2; in this embodiment, a gap of 0.1-0.2mm is reserved between the sliding constraint channel and the elastic rod 3 to form a low-friction sliding channel, which not only restricts the horizontal displacement and rotation of the elastic rod 3, but also allows it to slide with low resistance along the axial direction by utilizing rolling friction.

[0029] The base 1 is provided with mounting holes for inserting elastic rods 3, and the mounting holes are provided in correspondence with the sliding constraint channels.

[0030] In this embodiment, preferably, see [reference needed]. Figure 4 The elastic rod 3 is flat with a rectangular cross-section, and is preferably made of aluminum alloy or low-carbon steel to balance high strength and low damping characteristics.

[0031] See Figure 4 The mass block 5 is located at the end of the elastic rod 3 away from the base 1. In this embodiment, the mass block 5 is a cubic metal block, which is fixed to the end of the elastic rod 3 by a threaded connection. The function of the mass block 5 is to provide inertial force, causing the elastic rod 3 to bend and deform, and to adjust the fundamental frequency range of the passive frequency self-tuning device.

[0032] See Figure 2 The elastic rod 3 passes through the sliding constraint channel and exits the base 1 through the mounting hole. The sliding stroke of the elastic rod 3 is limited by the limiting device 4 set on it.

[0033] See Figure 1 , Figure 2 and Figure 4 The limiting device 4 includes a first limiting plate 4.1 and a second limiting plate 4.2; the first limiting plate 4.1 is disposed at one end of the elastic rod 3 that protrudes from the base 1, and is used to prevent the elastic rod 3 from coming out of the base 1 or the sliding constraint channel; the second limiting plate 4.2 is disposed between the sliding constraint assembly 2 and the mass block 5.

[0034] In this embodiment, both the first limiting plate 4.1 and the second limiting plate 4.2 are rectangular rigid plates; the horizontal projected area of ​​the first limiting plate 4.1 is larger than the area of ​​the mounting hole to prevent the elastic rod 3 from coming off the base 1; the horizontal projected area of ​​the second limiting plate 4.2 is larger than the top opening area of ​​the sliding constraint channel. When the passive frequency self-tuning device stops working or the elastic rod 3 slides down to the limit position, the second limiting plate 4.2 contacts the top of the sliding constraint component 2 to form a mechanical stop and prevent the elastic rod 3 from sliding down excessively.

[0035] For specific applications, please refer to Figure 5 When the base 1 is subjected to lateral vibration perpendicular to the axis of the elastic rod 3, the elastic rod 3 bends at the top opening of the sliding constraint channel and generates a bending moment there. Based on the configuration mechanics principle of the elastic system, this bending deformation will generate a configuration force along the axis of the elastic rod 3 at the top opening of the sliding constraint channel. The elastic rod 3 is driven to move in the sliding constraint channel by the resultant force of the configuration force and the gravity (including the gravity provided by the elastic rod 3, the limiting device 4 and the mass block 5) along the axial direction of the elastic rod 3. The length of the elastic rod 3 extending out of the sliding constraint component 2 is adjusted, that is, the effective length of the elastic rod 3, until the natural frequency of the passive frequency self-tuning device matches the external excitation frequency, forming a stable self-tuning state of passive negative feedback without external control.

[0036] In this embodiment, a piezoelectric element is also included. The piezoelectric element is attached to the surface of the elastic rod 3. Preferably, the piezoelectric element is located on the surface of the elastic rod 3 between the second limiting plate 4.2 and the mass block 5. In this embodiment, the piezoelectric element is a piezoelectric sheet. When the elastic rod 3 swings, the piezoelectric sheet generates high strain, converting mechanical energy into electrical energy and realizing energy harvesting.

[0037] The passive frequency self-tuning device provided by this invention can design the weight of mass block 5 according to the modal mass of the controlled main structure. When the passive frequency self-tuning device is installed on the main structure, it can automatically track the vibration frequency of the main structure and always generate an inertial force opposite to the vibration direction of the main structure, thereby efficiently suppressing the vibration of the main structure. Compared with previous devices, it is more adaptable to vibration control needs in complex environments.

[0038] The passive frequency self-tuning device of the present invention has a wide range of applications. It does not require external power supply and has a simple structure. It achieves self-tuning through a purely mechanical structure and can control and harvest energy from broadband and even low-frequency vibrations.

[0039] The present invention also provides a passive frequency self-tuning method, which uses the passive frequency self-tuning device described above for tuning, and includes the following steps; The passive frequency self-tuning device is placed in a vibration environment, so that the base 1 vibrates laterally with external excitation; Lateral vibration is used to cause the elastic rod 3 to bend at the top opening of the sliding constraint assembly 2, generating a sectional bending moment. This generates a configuration force along the axial direction of the elastic rod 3; the magnitude of this configuration force is related to the section bending moment generated by the elastic rod 3 at the top opening of the sliding constraint assembly 2. The squares are positively correlated; Adjust the installation direction of the passive frequency self-tuning device and the mass of the mass block 5 so that the configuration force and the gravitational component along the axis of the elastic rod 3 form a balance relationship with opposite directions; When the external excitation frequency or excitation amplitude changes, the configuration force changes with the lateral response amplitude of the elastic rod 3. The difference between the configuration force and the gravity component (including the gravity provided by the elastic rod 3, the limiting device 4, and the mass block 5) along the axial direction of the elastic rod 3 drives the elastic rod 3 to slide axially within the sliding constraint assembly 2, thus increasing the effective length of the elastic rod 3. The system automatically adjusts until a dynamic balance is achieved between the configuration force and the gravitational component, thereby causing the natural frequency of the passive frequency self-tuning device to passively approach the external excitation frequency, thus realizing passive frequency self-tuning.

[0040] In this embodiment, the effective length of the elastic rod is... Considered as the axial degree of freedom of a passive frequency self-tuning device, the elastic rod is mainly subjected to the following forces in the axial direction: configuration force. The gravitational component of the mass block at the end and the equivalent damping force generated by sliding According to Newton's second law, axial inertial force If the resultant force is equal to the axial force, then: ; For the equivalent mass of the device, These are the equivalent damping parameters of the device. For configurational forces, For the amplitude of the elastic rod, Indicates the curvature of the elastic rod. For the bending stiffness of the elastic rod, The angle between the axis of the elastic rod and the horizontal line. This represents the first derivative of the effective length with respect to time. It represents the second derivative of the effective length with respect to time.

[0041] When the effective length of the elastic rod 3 increases or decreases due to external disturbances, the resultant force of the configuration force and the gravity component along the axial direction of the elastic rod 3 (i.e., the difference between the configuration force and the gravity component) always drives the elastic rod 3 to slide in the direction that restores the effective length to its original stable position, thereby forming a stable self-tuning state with passive negative feedback without the need for external control.

[0042] The bending stiffness of the pre-set elastic rod 3 Mass of the mass block, tilt angle (i.e., the angle between the axis of the elastic rod and the horizontal line). The geometric parameters of the passive frequency self-tuning device are adjusted to ensure a stable effective length range within the target excitation frequency range, thereby achieving continuous passive tracking of external frequency changes. In this embodiment, the angle between the axis of the elastic rod and the horizontal line is adjusted. To realize the gravitational component The size is adjusted, thereby adjusting the effective operating bandwidth of the passive frequency self-tuning device.

[0043] When tuning using the passive frequency self-tuning device of the present invention, the elastic rod 3, under the action of gravity and configuration force, requires the configuration force to overcome the gravity component. The response amplitude of the passive frequency self-tuning device (i.e., the amplitude of the elastic rod) The magnitude depends on the external excitation frequency. The degree of closeness to the current natural frequency of the passive frequency self-tuning device. If the elastic rod 3 is too long, the natural frequency is low, it deviates from the resonance point, and the bending moment is small. At this time, the configuration force is insufficient to support the gravity / gravitational component, and the elastic rod 3 slides down (the effective length decreases). If the elastic rod 3 is too short, the natural frequency is high, and it also deviates from the resonance point, so the elastic rod 3 will also slide to find equilibrium. When the external vibration frequency increases / amplitude increases, the elastic rod 3 spontaneously shortens its effective length to increase the natural frequency; when the frequency decreases / amplitude decreases, the elastic rod 3 spontaneously lengthens, increasing its effective length to decrease the natural frequency, ultimately making the frequency of the passive frequency self-tuning device approach the external excitation frequency, thus achieving passive self-tuning.

[0044] Under the action of the self-tuning mechanism, regardless of the fluctuations in the external excitation frequency, it will eventually stabilize at the position where the configuration force and gravity are in dynamic equilibrium. At this point, the effective length of the elastic rod is... This precisely puts the passive frequency self-tuning device in a near-resonance state, and the natural frequency of the passive frequency self-tuning device is exactly the same as the external excitation frequency. match.

[0045] When the external vibration stops and the configuration force disappears, the elastic rod 3 falls naturally under the action of gravity. At this time, the second limiting plate 4.2 contacts the top of the slide frame 2.1, preventing the elastic rod 3 from falling further and keeping the passive frequency self-tuning device in its initial state.

[0046] During the self-tuning process, the piezoelectric element on the surface of the elastic rod 3 converts the mechanical energy generated by the bending deformation of the elastic rod 3 into electrical energy. During the above-mentioned tuning process, regardless of the fluctuation of the external excitation frequency, the elastic rod 3 always maintains a large-amplitude resonant oscillation state. The piezoelectric sheet attached to the surface of the elastic rod then generates high strain, efficiently converting mechanical energy into electrical energy. Its power generation efficiency is far higher than that of traditional piezoelectric cantilever beam energy harvesting devices.

[0047] In one specific embodiment, the elastic rod 3 of the passive frequency self-tuning device of the present invention is made of low-carbon steel, with an effective length of 0.18m~0.28m (variable length of 0.1m), a width of 0.02m, a thickness of 0.0006m, and an end mass of 5g. The tuning of the passive frequency self-tuning device was investigated using a frequency of 10Hz and an acceleration of 4m / s². 2 The device is excited by an external load. The changes in the end amplitude and effective length of the passive frequency self-tuning device are recorded and processed.

[0048] Figure 6 The vibration time history curve of the passive frequency self-tuning device corresponds to the vibration displacement of the free end of the elastic rod. Figure 7 This represents the tuning result of the passive frequency self-tuning device, corresponding to the change in the effective length of the elastic rod. The initial effective length of the elastic rod is set when the external main structure vibrates. With an initial length of 0.28m, after being excited, the elastic rod 3 begins to vibrate from rest (initial state is zero), with a very small initial amplitude, remaining in a small-amplitude vibration state. At this time, the elastic rod 3 is subjected to gravity and begins to slide from the free end (i.e., the end where the mass block 5 is installed) towards the sliding constraint assembly. When the effective length of the elastic rod decreases by 0.043m (effective length is 0.237m), the elastic rod 3 exhibits an upward jump phenomenon, obtaining a larger amplitude. Simultaneously, this increased amplitude provides the elastic rod 3 with a sufficiently large configuration force, allowing it to maintain equilibrium at this position. At this point, the vibration of the elastic rod 3 is also greatly amplified, completing the tuning. See also... Figure 7The final results show that the present invention can realize the function of passive self-tuning, so that the passive frequency self-tuning device can maintain the frequency vibration consistent with the external excitation.

[0049] The above description is only a preferred embodiment of the present invention and does not limit the scope of the present invention. All equivalent structural transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the protection scope of the present invention.

Claims

1. A passive frequency self-tuning device, characterized in that, It includes a base (1), a sliding constraint assembly (2), an elastic rod (3), a limiting device (4), and a mass block (5); The sliding constraint component (2) is fixedly mounted on the base (1); the sliding constraint component (2) is provided with a sliding constraint channel, and the elastic rod (3) passes through the sliding constraint channel and the base (1) and can slide along the sliding constraint channel; The limiting device (4) is disposed on the elastic rod (3) to limit the sliding stroke of the elastic rod (3); The mass block (5) is located at the end of the elastic rod (3) away from the base (1).

2. The passive frequency self-tuning device as described in claim 1, characterized in that, The sliding constraint assembly (2) includes a slide frame (2.1) and multiple sets of pulleys (2.2); The slide frame (2.1) is vertically mounted on the base (1). Two rows of pulleys (2.2) are symmetrically arranged along the axial direction of the slide frame (2.1). The pulleys (2.2) are connected to the slide frame (2.1) via a mounting shaft. The pulleys (2.2) are rotatably mounted on the mounting shaft. A sliding constraint channel is formed between the two rows of pulleys (2.2); the elastic rod (3) is set at the center of the sliding constraint channel, and the elastic rod (3) is rolledly connected to the two rows of pulleys (2.2); The base (1) is provided with mounting holes for inserting elastic rods (3), and the mounting holes are provided in correspondence with the sliding constraint channels.

3. The passive frequency self-tuning device as described in claim 2, characterized in that, The limiting device (4) includes a first limiting plate (4.1) and a second limiting plate (4.2). The first limiting plate (4.1) is located at one end of the elastic rod (3) that protrudes from the base (1) to prevent the elastic rod (3) from coming off the base (1) or the sliding constraint channel; The second limiting plate (4.2) is disposed between the sliding constraint component (2) and the mass block (5).

4. The passive frequency self-tuning device as described in claim 3, characterized in that, The horizontal projected area of ​​the first limiting plate (4.1) is greater than the area of ​​the mounting hole; the horizontal projected area of ​​the second limiting plate (4.2) is greater than the top opening area of ​​the sliding constraint channel.

5. The passive frequency self-tuning device as described in any one of claims 1-4, characterized in that, It also includes a piezoelectric element, which is attached to the elastic rod (3) for energy harvesting.

6. A passive frequency self-tuning method, wherein the passive frequency self-tuning device as described in any one of claims 1-5 is used for tuning, characterized in that, Includes the following steps; The passive frequency self-tuning device is placed in a vibration environment, so that the base (1) vibrates laterally with external excitation; Lateral vibration is used to cause the elastic rod (3) to bend at the top opening of the sliding constraint assembly (2), and generate a section bending moment. This generates a configuration force along the axis of the elastic rod (3); Adjust the installation direction of the passive frequency self-tuning device and the mass of the mass block (5) so that the configuration force and the gravity component along the axis of the elastic rod (3) form a balance relationship with opposite directions; When the external excitation frequency or excitation amplitude changes, the configuration force changes with the lateral response amplitude of the elastic rod (3). The difference between the configuration force and the gravity component drives the elastic rod (3) to slide axially within the sliding constraint assembly (2), thus reducing the effective length of the elastic rod (3). The system automatically adjusts until a dynamic balance is achieved between the configuration force and the gravitational component, thereby causing the natural frequency of the passive frequency self-tuning device to passively approach the external excitation frequency, thus realizing passive frequency self-tuning.

7. The passive frequency self-tuning method as described in claim 6, characterized in that, The magnitude of the configuration force is related to the section bending moment generated by the elastic rod (3) at the top opening of the sliding constraint assembly (2). The squares of the numbers are positively correlated.

8. The passive frequency self-tuning method as described in claim 6, characterized in that, Effective length of elastic rod Regulation is expressed through the following relationship: ； in, For the equivalent mass of the device, These are the equivalent damping parameters of the device. For configurational forces, For the amplitude of the elastic rod, Indicates the curvature of the elastic rod. For the bending stiffness of the elastic rod, The angle between the axis of the elastic rod and the horizontal line. This represents the first derivative of the effective length with respect to time. It represents the second derivative of the effective length with respect to time.

9. The passive frequency self-tuning method as described in claim 8, characterized in that, By adjusting the angle between the axis of the elastic rod and the horizontal line To realize the gravitational component The size is adjusted, thereby adjusting the effective operating bandwidth of the passive frequency self-tuning device.

10. The passive frequency self-tuning method as described in claim 6, characterized in that, During the self-tuning process, the piezoelectric element set on the surface of the elastic rod (3) converts the mechanical energy generated by the bending deformation of the elastic rod (3) into electrical energy.

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