A biomimetic locust-leg piezoelectric energy harvester

Abstract

This application relates to the field of energy harvesting technology, and particularly to a biomimetic locust-leg piezoelectric energy harvester, comprising: a fixing member configured for fixing to an energy harvesting point; a main beam, which is straight and one end is fixed to the fixing member and extends in a direction away from the fixing member, wherein the extension direction of the main beam is perpendicular to the plate surface of the main beam; a connecting member fixed to the other end of the main beam; a secondary beam, which is curved or plate-like and located on the side of the connecting member away from the main beam, one end of which is fixed to the connecting member and extends in a curved or plate-like shape in a direction away from the main beam, wherein the two plate surfaces of the secondary beam face the same direction as the two plate surfaces of the main beam; and a piezoelectric sheet, which is attached to and fixed to the plate surface of the main beam. The biomimetic locust-leg piezoelectric energy harvester provided by this application embodiment can improve energy harvesting efficiency.

Description

Technical Field

[0001] This application relates to the field of energy harvesting technology, and in particular to a biomimetic locust leg-type piezoelectric energy harvester. Background Technology

[0002] A piezoelectric energy harvester is a device that uses the piezoelectric effect to convert mechanical energy into electrical energy. It does not rely on fossil fuels and does not produce greenhouse gas emissions, making it a clean energy solution. Therefore, research on piezoelectric energy harvesters helps promote sustainable energy development and reduce dependence on traditional energy sources.

[0003] Specifically, a piezoelectric energy harvester typically consists of a cantilever beam with piezoelectric elements. The piezoelectric elements are usually made of ceramics, polymers, or single crystals. When subjected to mechanical stress, their molecular structure changes, causing the separation of positive and negative charges, thus generating a voltage on the two opposing surfaces of the piezoelectric element. Based on this, when vibrations from wind, water flow, machine movement, or human movement occur in the environment and are transmitted to the cantilever beam, the piezoelectric elements on the beam are subjected to these stresses. This causes a change in the electric dipole moment inside the piezoelectric element, resulting in a voltage difference between the two surfaces. The charge generated by the piezoelectric element is then collected and output through the electrodes of the piezoelectric element by a charge collection device.

[0004] However, the piezoelectric energy harvester using the above structure (i.e., a cantilever beam with a piezoelectric element) can only collect a relatively simple type of vibration energy, resulting in low energy harvesting efficiency. Summary of the Invention

[0005] The purpose of this application is to provide a biomimetic locust leg-type piezoelectric energy harvester that can improve energy harvesting efficiency.

[0006] To achieve the above effects, this application provides a biomimetic locust-leg piezoelectric energy harvester, comprising: a fixing member configured for fixing to an energy harvesting point; a main beam, which is straight and has one end fixed to the fixing member and extends in a direction away from the fixing member, wherein the extension direction of the main beam is perpendicular to the plate surface of the main beam; a connecting member fixed to the other end of the main beam; a secondary beam, which is curved or plate-like and located on the side of the connecting member away from the main beam, and has one end fixed to the connecting member and extends in a curved or plate-like shape in a direction away from the plate surface of the main beam, wherein the two plate surfaces of the secondary beam face the same direction as the two plate surfaces of the main beam; and a piezoelectric sheet attached to and fixed to the plate surface of the main beam.

[0007] This application provides a biomimetic locust-leg-type piezoelectric energy harvester. The secondary beam is shaped like a bent plate or a plate-like bent beam, making it easier to bend and deform, thereby reducing its resonant frequency. Simultaneously, it is easily induced to vibrate under various vibration modes (such as sine waves, square waves, and triangular waves). Thus, considering the connection and relative positional relationship between the secondary beam, connectors, and the main beam, the vibration of the secondary beam at low resonant frequencies and under various vibration modes can be transmitted to the main beam via the connectors, subsequently inducing the main beam to vibrate. Furthermore, because the vibration is transmitted to the main beam via the secondary beam and connectors, the vibration energy received by the main beam is filtered by the secondary beam and connectors, making it more suitable for the vibration modes adapted to the main beam, thus increasing the energy of the main beam during vibration. In this case, combined with piezoelectric elements placed on the main beam to synchronously collect the vibration energy of the main beam, a better energy harvesting effect can be achieved. In this way, the biomimetic locust leg piezoelectric energy harvester provided in this application embodiment can not only harvest a wide range of vibration frequencies and multiple vibration modes, but also optimize the harvesting and conversion of vibration energy, thereby improving the harvesting efficiency of vibration energy.

[0008] In some embodiments, the biomimetic locust-leg piezoelectric energy harvester further includes a first mass block fixed to the end of the sub-beam away from the connector. This further reduces the resonant frequency of the sub-beam, thereby further increasing the bandwidth of the vibrational frequency collected by the biomimetic locust-leg piezoelectric energy harvester.

[0009] In some embodiments, at least a portion of the first mass block is made of a magnetic or magnetizable material; the biomimetic locust-leg piezoelectric energy harvester further includes: a mounting frame located on the side of the first mass block away from the connector, with its extension direction perpendicular to the surface of the main beam; and a magnet disposed adjacent to the first mass block and fixed to the mounting frame; wherein both the mounting frame and the magnet are spaced apart from the first mass block. When at least a portion of the first mass block is made of a magnetizable material, the portion of the first mass block made of the magnetizable material can be magnetized by the magnet and thus become magnetic. Therefore, regardless of whether at least a portion of the first mass block is made of a magnetic or magnetizable material, when the first mass block moves (equivalent to the vibration of the sub-beam), the magnetic field generated by the magnet affects the first mass block, thereby increasing the vibration energy of the sub-beam, and indirectly increasing the vibration energy of the main beam, thereby improving the energy harvesting effect of the biomimetic locust-leg piezoelectric energy harvester.

[0010] In some embodiments, the number of magnets is two; the two magnets are spaced apart and are arranged sequentially along the extension direction of the fixing frame; a surface perpendicular to the extension direction of the fixing frame and located at the midpoint between the positions of the two magnets is a preset surface, wherein the geometric center of the first mass block is located on the preset surface. Thus, combined with the fact that the extension direction of the fixing frame is perpendicular to the surface of the main beam, and the orientation of the two surfaces of the secondary beam is the same as that of the two surfaces of the main beam, meaning that when the secondary beam vibrates, the displacement of the first mass block in the extension direction of the fixing frame is larger, the aforementioned design can achieve a greater influence of the magnets on the first mass block in most cases, thereby better improving the energy harvesting effect of the biomimetic locust-leg piezoelectric energy harvester.

[0011] In some embodiments, the position of the magnet in the extension direction of the mounting frame is configured based on the vibration mode of the sub-beam. When the magnet is positioned in conjunction with the vibration mode of the sub-beam, the indirect influence of the magnet on the sub-beam via the first mass block can be maximized, thereby further improving the energy harvesting effect of the biomimetic locust-leg piezoelectric energy harvester.

[0012] In some embodiments, the mounting frame has multiple fixing positions along its extension direction; the magnet is selectively fixed to one of the fixing positions. Thus, when structures such as the sub-beam and the first mass block suffer wear or other damage, the position of the magnet in the extension direction of the mounting frame can be adjusted, thereby ensuring that the energy harvesting effect of the biomimetic locust-leg piezoelectric energy harvester remains at an optimal level.

[0013] In some embodiments, the lower surface of the first mass block is provided with a plurality of grooves. In this way, the weight and weight distribution of the first mass block can be changed by means of the grooves, thereby making it easier to adjust the resonant frequency of the sub-beam.

[0014] In some embodiments, the biomimetic locust-leg piezoelectric energy harvester further includes: an auxiliary beam, which is a straight plate with one end fixed to the connector and extends in a direction close to the connector, wherein the extension direction of the auxiliary beam is perpendicular to the plate surface of the auxiliary beam; wherein the auxiliary beam is configured to have a different resonant frequency than the main beam. Thus, when energy matching the resonant frequency of the auxiliary beam is present, the auxiliary beam resonates and transmits the vibrational energy to the main beam via the connector, thereby enhancing the vibrational energy of the main beam at that frequency, i.e., enhancing the vibrational energy that the main beam can generate at the resonant frequency of the auxiliary beam; furthermore, since the auxiliary beam and the main beam are connected to each other via the connector, and the main beam and the secondary beam are also connected via the connector, when the auxiliary beam transmits energy to the main beam, if a corresponding structure such as the aforementioned magnet is provided, the vibrational energy of the auxiliary beam will also be transmitted to the secondary beam and amplified on the secondary beam, and then transmitted to the main beam, thereby increasing the vibrational energy transmitted from the auxiliary beam to the main beam.

[0015] In some embodiments, the biomimetic locust-leg piezoelectric energy harvester further includes a second mass block fixed to the end of the auxiliary beam away from the connector. This further reduces the resonant frequency of the auxiliary beam, thereby further increasing the bandwidth of the vibrational frequency collected by the biomimetic locust-leg piezoelectric energy harvester.

[0016] In some embodiments, the connector is plate-shaped; the connector has a first plate surface and a second plate surface disposed opposite to each other, and has a first end and a second end surface disposed opposite to each other in a direction perpendicular to the main beam plate surface; the main beam is fixed to the first end surface and located on the first plate surface; the secondary beam is fixed between the first end surface and the second end surface of the connector and located on the second plate surface; the auxiliary beam is fixed to the second end surface and located on the first plate surface. Thus, when the auxiliary beam transfers energy to the main beam, it first transfers it to the secondary beam, preferentially amplifying the energy on the secondary beam; furthermore, placing the main beam and the auxiliary beam on the same side of the connector, and placing the main beam and the secondary beam on different sides of the connector, ensures that even if the secondary beam is curved or plate-like, the required distance between the main beam and the auxiliary beam will not be too large, allowing for miniaturization of the connector, thereby reducing energy loss in the connector, and also enabling the miniaturization of the biomimetic locust-leg piezoelectric energy harvester.

[0017] In some embodiments, the main beam, the connector, and the secondary beam are integrally formed; the auxiliary beam is detachably mounted on the connector. This improves the structural strength of the connection between the main beam, connector, and secondary beam, and also reduces energy loss when the secondary beam transfers energy to the main beam. Furthermore, the detachable mounting of the auxiliary beam on the connector enables modularity, allowing for the selection of energy harvesting solutions more suitable for different application scenarios.

[0018] In some embodiments, two piezoelectric elements are used, each attached and fixed to one of the two plates of the main beam; and / or, the thickness of the portion of the piezoelectric element near the fixing element is greater than the thickness of the portion away from the fixing element; and / or, the piezoelectric element is disposed adjacent to the fixing element. Thus, while keeping the vibration energy of the main beam constant, the electrical output of the biomimetic locust-leg piezoelectric energy harvester can be increased.

[0019] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0021] Figure 1 Schematic diagrams of the single-peak energy harvester provided in some embodiments of this application;

[0022] Figure 2 Another schematic diagram of the single-peak energy harvester provided in some embodiments of this application;

[0023] Figure 3 Another schematic diagram of a single-peak energy harvester provided for some embodiments of this application;

[0024] Figure 4 A schematic diagram of a single-peak energy harvester with a corresponding magnet provided in some embodiments of this application;

[0025] Figure 5 Another schematic diagram of a single-peak energy harvester with a corresponding magnet provided in some embodiments of this application;

[0026] Figure 6 This application provides schematic diagrams of the structure of a dual-peak energy harvester according to some embodiments;

[0027] Figure 7 This is another schematic diagram of the dual-peak energy harvester provided in some embodiments of this application;

[0028] Figure 8 A schematic diagram of a dual-peak energy harvester with a corresponding magnet provided in some embodiments of this application;

[0029] Figure 9 Another schematic diagram of a dual-peak energy harvester with a corresponding magnet provided in some embodiments of this application;

[0030] Figure 10 , 12 14 and 15 are simplified model diagrams of energy harvesters provided in some embodiments of this application;

[0031] Figure 11 , 13 Figures 16 and 17 show the voltage and power variations with frequency obtained from simplified calculations of an energy harvester model according to some embodiments of this application.

[0032] Figure 18-21The following graphs illustrate the voltage and power variations with frequency for energy harvesters based on finite element simulations, as shown in some embodiments of this application.

[0033] Figures 22-25 The graphs provided for some embodiments of this application show the vibration displacement and voltage variation with frequency of an energy harvester based on experimental verification, wherein the unit of vibration displacement is millimeters (mm).

[0034] The reference numerals in the detailed embodiments are as follows:

[0035] Fixing component 110, main beam 120, connecting component 130, first plate surface 131, second plate surface 132, first end 133, second end 134, secondary beam 140, piezoelectric sheet 150, first mass block 160, groove 161, fixing frame 170, fixing position 171, magnet 180, auxiliary beam 190, second mass block 200. Detailed Implementation

[0036] Currently, piezoelectric energy harvesters typically consist of a cantilever beam with piezoelectric elements. The inventors have noted that this biomimetic locust-leg piezoelectric energy harvester has a narrow frequency bandwidth for harvesting energy and can only harvest a single vibration mode.

[0037] To improve the energy harvesting efficiency of the biomimetic locust-leg piezoelectric energy harvester, the applicant discovered that by designing the secondary beam as a curved plate or plate-like curved shape, it becomes easier to bend and deform, thereby reducing the resonant frequency of the secondary beam. Simultaneously, it is also easily induced to vibrate under various vibration modes (such as sine waves, square waves, and triangular waves). Furthermore, through innovative design of the connection and relative positional relationship between the secondary beam, connector, and main beam—namely, the straight plate-like main beam extends away from the fixed component, with the extension direction perpendicular to the plate surface of the main beam; the connector is fixed to the other end of the main beam; the curved plate or plate-like curved secondary beam is located on the side of the connector away from the main beam, and its… One end is fixed to the connector and extends in a curved or near-curved shape away from the main beam's surface. The two surfaces of the sub-beam face the same direction as the two surfaces of the main beam. This allows the sub-beam to vibrate at low resonant frequencies and in various vibration modes, transmitting the vibration to the main beam via the connector, thus inducing the main beam to vibrate. Simultaneously, because the vibration is transmitted to the main beam via the sub-beam and connector, the vibration energy received by the main beam is filtered by the sub-beam and connector, making it more suitable for the vibration modes the main beam is adapted to, thereby increasing the energy of the main beam's vibration. At this point, placing piezoelectric elements on the main beam and simultaneously collecting the vibration energy of the main beam achieves a better energy harvesting effect. Therefore, the biomimetic locust-leg piezoelectric energy harvester provided in this embodiment can collect a wide range of vibration frequencies and multiple vibration modes, while also optimizing the collection and conversion of vibration energy, thereby improving the efficiency of vibration energy collection.

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been presented in the various embodiments of this application to enable readers to better understand this application. However, the technical solutions claimed in this application can also be implemented based on various changes and modifications to the following embodiments.

[0039] See Figures 1 to 9 In some embodiments, this application provides a biomimetic locust-leg-type piezoelectric energy harvester, comprising: a fixing member 110 configured for fixing to an energy harvesting point; a main beam 120, which is in the shape of a straight plate, with one end fixed to the fixing member 110 and extending in a direction away from the fixing member 110, wherein the extension direction of the main beam 120 is perpendicular to the plate surface of the main beam 120; a connecting member 130 fixed to the other end of the main beam 120; a secondary beam 140, which is in the shape of a curved plate or a plate-like curved plate, located on the side of the connecting member 130 away from the main beam 120, with one end fixed to the connecting member 130 and extending in a curved or plate-like curved shape in a direction away from the plate surface of the main beam 120, wherein the two plate surfaces of the secondary beam 140 are oriented in the same direction as the two plate surfaces of the main beam 120; and a piezoelectric sheet 150, which is attached to and fixed to the plate surface of the main beam 120.

[0040] The energy collection point refers to the location where energy needs to be collected. For example, when it is necessary to collect vibration energy from a bridge, the energy collection point refers to the location on the bridge, and in this case, the fixing part 110 is fixed to the bridge. When it is necessary to collect vibration energy from a robot, the energy collection point refers to the location on the robot, and in this case, the fixing part 110 is fixed to the robot's legs, torso, or other parts.

[0041] The term "sub-beam 140 is curved or plate-like" means that at least most of the surface of the sub-beam 140 is curved or quasi-curved. The curved surface can be a circular arc surface, a wavy curved surface, etc., that is, the cross section of the curved surface is a line segment of an arc or a wavy line. The quasi-curved surface is a shape similar to a curved surface, and the cross section of the quasi-curved surface can be a line segment of multiple broken lines that approximates an arc or a wavy line.

[0042] The design utilizes a biomimetic locust leg hip joint (fixed component 110), a biomimetic locust leg tibia (main beam 120), a biomimetic locust leg knee joint (connector 130), and a biomimetic locust leg femur (secondary beam 140). Based on the biological characteristics of the locust leg, it can operate stably under varying environmental conditions, achieving efficient vibration energy conversion. In simpler terms, the femur and tarsus of the locust leg are simplified as the secondary beam 140, serving as the main load-bearing structure, while the tibia is simplified as the main beam 120 fixed with the fixed component 110.

[0043] Specifically, since the secondary beam 140 is in the shape of a curved plate or a plate-like curved shape, the two plate faces of the secondary beam 140 are oriented in the same direction as the two plate faces of the main beam 120. This means that the two plate faces of the secondary beam 140 are roughly oriented in the same direction as the two plate faces of the main beam 120. For example, one plate face of the main beam 120 faces upward and the other plate face downward, and one plate face of the secondary beam 140 is roughly oriented upward and the other plate face is roughly oriented downward. Here, the orientation of the plate face refers to the direction in which the plate face is facing.

[0044] Based on the biomimetic locust-leg piezoelectric energy harvester provided in this embodiment, the secondary beam 140 is bent or plate-like, making it easier to bend and deform, thereby reducing the resonant frequency of the secondary beam 140. Simultaneously, it is easily induced to vibrate under various vibration modes (such as sine waves, square waves, and triangular waves). Thus, considering the connections and relative positions between the secondary beam 140, the connector 130, and the main beam 120, the secondary beam 140 can be induced to vibrate at low resonant frequencies and under various vibration modes. The vibration energy is transmitted to the main beam 120 via the connector 130, causing the main beam 120 to vibrate. Simultaneously, because the vibration is transmitted to the main beam 120 via the secondary beam 140 and the connector 130, the vibration energy received by the main beam 120 is filtered by the secondary beam 140 and the connector 130, making it more suitable for the vibration mode of the main beam 120 and increasing the energy of the main beam 120 during vibration. At this point, combined with the piezoelectric sheet 150 placed on the main beam 120, the vibration energy of the main beam 120 is collected synchronously, achieving a better energy harvesting effect. Thus, the biomimetic locust-leg piezoelectric energy harvester can collect a wide range of vibration frequencies and multiple vibration modes, while also optimizing the collection and conversion of vibration energy, thereby improving the efficiency of vibration energy collection.

[0045] The aforementioned wide vibration frequency range refers to a series of vibrational energies from low to high frequencies. In real-world environments, vibration sources exhibit diverse frequencies, including low-frequency traffic vibrations, mid-frequency industrial equipment vibrations, and high-frequency vibrations from small electronic devices. Therefore, an ideal energy harvester should be able to cover the widest possible frequency range to harvest energy from various vibration sources. Multiple vibration modes refer to the diverse frequencies of vibrational energy present in the environment, which may also include various types of vibrational modes. These different vibrational modes may coexist and superimpose, forming a complex vibrational environment. The energy harvester of this application readily responds to these different vibrational components to maximize energy harvesting efficiency.

[0046] See Figures 1 to 9In some embodiments, the biomimetic locust-leg piezoelectric energy harvester further includes a first mass block 160 fixed to the end of the sub-beam 140 away from the connector 130. This further reduces the resonant frequency of the sub-beam 140, thereby further increasing the bandwidth of the vibration frequency collected by the biomimetic locust-leg piezoelectric energy harvester. Furthermore, the characteristic of reducing the resonant frequency, i.e., small input changes leading to large output changes, is particularly pronounced in low-frequency vibrations.

[0047] See Figure 4 , 5 In some embodiments, at least a portion of the first mass block 160 is made of a magnetic or magnetizable material; the biomimetic locust-leg piezoelectric energy harvester further includes: a mounting frame 170 located on the side of the first mass block 160 away from the connector 130, and its extension direction is perpendicular to the plate surface of the main beam 120; and a magnet 180 disposed adjacent to the first mass block 160 and fixed to the mounting frame 170; wherein the mounting frame 170 and the magnet 180 are spaced apart from the first mass block 160.

[0048] When at least a portion of the first mass block 160 is made of a magnetizable material, the portion of the first mass block 160 made of the magnetizable material can be magnetized by the magnet 180 and thus become magnetic. When the first mass block 160 is made of a magnetic material, the portion of the first mass block 160 made of the magnetic material is itself magnetic.

[0049] The fixing frame 170 is located on the side of the first mass block 160 away from the connector 130 and is spaced apart from the first mass block 160. That is, the fixing frame 170 is not connected to the aforementioned fixing member 110, main beam 120, connector 130, secondary beam 140, piezoelectric sheet 150, or first mass block 160. Thus, when the main beam 120 or secondary beam 140 vibrates, the fixing frame 170 ensures that it does not affect the vibration of the main beam 120 or secondary beam 140. Furthermore, since there is a gap between the magnet 180 and the first mass block 160, the magnet 180 only exerts a magnetic force on the first mass block 160, and does not generate a force based on direct or indirect physical contact.

[0050] Thus, when at least a portion of the first mass block 160 is made of either magnetic or magnetizable material, the magnetic field generated by the magnet 180 affects the first mass block 160 when the first mass block 160 moves (equivalent to the vibration of the secondary beam 140), thereby increasing the vibration energy of the secondary beam 140 and indirectly increasing the vibration energy of the main beam 120, thereby improving the energy collection effect of the biomimetic locust-leg piezoelectric energy harvester.

[0051] See Figure 4 , 5In some embodiments, the number of magnets 180 is two; there is a gap between the two magnets 180, and the two magnets 180 are arranged sequentially along the extension direction of the fixing frame 170.

[0052] In this embodiment, the surface perpendicular to the extending direction of the fixing frame 170 and located at the midpoint between the positions of the two magnets 180 is a preset surface, wherein the geometric center of the first mass block 160 is located on the preset surface. Simply put, the orthographic projection of the geometric center of the first mass block 160 onto the fixing frame 170 is located at the midpoint between the two magnets 180.

[0053] Since the extension direction of the fixed frame 170 is perpendicular to the plate surface of the main beam 120, and the two plate surfaces of the secondary beam 140 are oriented in the same direction as the two plate surfaces of the main beam 120, when the secondary beam 140 vibrates, the first mass block 160 exhibits a reciprocating motion similar to a pendulum path. Specifically, the displacement of the first mass block 160 in the extension direction of the fixed frame 170 is relatively large, while the displacement of the first mass block 160 in the opposite direction between the two ends of the secondary beam 140 is relatively small. The opposite direction between the two ends of the secondary beam 140 refers to the direction from one end of the secondary beam 140 to the other end.

[0054] Therefore, through the design of this embodiment, combined with the large displacement of the first mass block 160 in the extending direction of the fixing frame 170, the magnet 180 can have a significant impact on the first mass block 160 in most cases; specifically, see... Figure 5 , 9 Specifically, when the first mass block 160 swings upward, the upper magnet of the two magnets 180 exerts a greater magnetic force on the first mass block 160; conversely, when the first mass block 160 swings downward, the lower magnet of the two magnets 180 exerts a greater magnetic force on the first mass block 160, thereby improving the energy harvesting effect of the biomimetic locust-leg piezoelectric energy harvester. Furthermore, since the magnetic field generated by the magnets 180 on the first mass block 160 is not limited to the magnetic force in the extension direction of the fixed frame 170, but also has a magnetic force in the opposite directions at both ends of the sub-beam 140, the two magnets 180 can further increase the energy of the sub-beam 140 during vibration by generating a magnetic force on the first mass block 160 in the opposite directions at both ends of the sub-beam 140, thus further improving the energy harvesting effect of the biomimetic locust-leg piezoelectric energy harvester.

[0055] It should be noted that the midpoint setting in this embodiment can adapt to the vibration mode of the sub-beam 140 in many cases, thereby improving the energy collection effect of the biomimetic locust leg piezoelectric energy harvester in most cases.

[0056] See Figure 4 , 5In some embodiments, the position of the magnet 180 in the extension direction of the fixture 170 is configured based on the vibration mode of the sub-beam 140.

[0057] The vibration mode of the secondary beam 140 refers to the shape of the secondary beam 140 at various points during vibration. Because the secondary beam 140 is shaped like a curved plate or a near-curved plate, its vibration mode is more complex and variable compared to the straight main beam 120. For example, the vibration mode of the secondary beam 140 will change when the degree and direction of its curvature differ. Simply put, when the secondary beam 140 vibrates, combined with… Figure 5 , 9 Due to factors such as the degree and direction of bending of the sub-beam 140, the upward displacement of the first mass block 160 differs from its downward displacement. Therefore, when the position of the magnet 180 is determined in conjunction with the vibration pattern of the sub-beam 140, the indirect influence of the magnet 180 on the sub-beam 140 via the first mass block 160 can be maximized, thereby further enhancing the energy harvesting effect of the biomimetic locust-leg piezoelectric energy harvester.

[0058] See Figure 4 , 5 In some embodiments, the mounting bracket 170 is provided with a plurality of mounting positions 171 along its extension direction; the magnet 180 is selectively fixed on one mounting position 171.

[0059] It should be noted that this application does not limit the shape or installation method of the fixing position 171. For example, in this embodiment, the fixing position 171 is a hole opened on the fixing frame 170. In this case, the magnet 180 can be fixed in a fixing position 171 by passing through the magnet 180 and screwing it into the fixing position 171 of the fixing frame 170.

[0060] Thus, when structures such as the secondary beam 140 and the first mass block 160 are damaged by wear, the position of the magnet 180 in the extension direction of the fixed frame 170 can be adjusted to maximize the energy amplification of the secondary beam 140 and the first mass block 160 by the magnet 180, thereby ensuring that the energy collection effect of the biomimetic locust leg piezoelectric energy harvester is always in a better state.

[0061] See Figure 3 In some embodiments, the lower surface of the first mass block 160 is provided with a plurality of grooves 161. In this embodiment, the lower surface of the first mass block 160 is provided with two elongated grooves, two triangular grooves, and one regular polygonal groove, and the aforementioned grooves are symmetrically distributed. In this way, the weight and weight distribution of the first mass block 160 can be changed by means of the grooves 161, thereby making it easier to adjust the resonant frequency of the sub-beam 140.

[0062] See Figures 6 to 9 In some embodiments, the biomimetic locust-leg piezoelectric energy harvester further includes: an auxiliary beam 190, which is in the shape of a straight plate and has one end fixed to the connector 130 and extends in a direction far from the fixing member 110, wherein the extension direction of the auxiliary beam 190 is perpendicular to the plate surface of the auxiliary beam 190; wherein the auxiliary beam 190 is configured to have a different resonant frequency from the main beam 120.

[0063] Thus, when energy matching the resonant frequency of the auxiliary beam 190 is present, the auxiliary beam 190 resonates and transmits the vibrational energy to the main beam 120 via the connector 130, thereby enhancing the vibrational energy of the main beam 120 at that frequency, thus achieving the effect of enhancing the vibrational energy that the main beam 120 can generate at the resonant frequency of the auxiliary beam 190.

[0064] Furthermore, since the auxiliary beam 190 is connected to the main beam 120 via the connector 130, and the main beam 120 is also connected to the secondary beam 140 via the connector 130, when the auxiliary beam 190 transmits energy to the main beam 120, in conjunction with the above-mentioned implementation with corresponding structures such as the magnet 180, the vibration energy of the auxiliary beam 190 will also be transmitted to the secondary beam 140 and amplified on the secondary beam 140, and then transmitted to the main beam 120, thereby increasing the vibration energy transmitted from the auxiliary beam 190 to the main beam 120.

[0065] See Figures 6 to 9 In some embodiments, the biomimetic locust-leg piezoelectric energy harvester further includes a second mass block 200 fixed to the end of the auxiliary beam 190 away from the connector 130. This further reduces the resonant frequency of the auxiliary beam 190, thereby further increasing the bandwidth of the vibration frequency collected by the biomimetic locust-leg piezoelectric energy harvester.

[0066] See Figures 6 to 9 In some embodiments, the connector 130 is plate-shaped; the connector 130 has a first plate surface 131 and a second plate surface 132 disposed opposite to each other, and has a first end 133 and a second end 134 disposed opposite to each other in a direction perpendicular to the plate surface of the main beam 120; the main beam 120 is fixed to the first end 133 and located on the first plate surface 131; the secondary beam 140 is fixed at a position between the first end 133 and the second end 134 of the connector 130 and located on the second plate surface 132; the auxiliary beam 190 is fixed to the second end 134 and located on the first plate surface 131.

[0067] It should be noted that, in order to facilitate understanding of the first end 133 and the second end 134, dashed lines are used to divide them in the attached drawings. That is, the dashed lines used to divide the first end 133 and the second end 134 are not the structure of the connector 130 itself.

[0068] Thus, when the auxiliary beam 190 transfers energy to the main beam 120, it will first transfer it to the secondary beam 140, and the energy will be amplified preferentially on the secondary beam 140. In addition, by placing the main beam 120 and the auxiliary beam 190 on the same side of the connector 130 and placing the main beam 120 and the secondary beam 140 on different sides of the connector 130, even if the secondary beam 140 is in the shape of a curved plate or a plate-like curved shape, the required distance between the main beam 120 and the auxiliary beam 190 will not be too large. This allows the connector 130 to be miniaturized, thereby reducing energy loss on the connector 130 and enabling the biomimetic locust-leg piezoelectric energy harvester to be miniaturized.

[0069] See Figures 1 to 9 In some embodiments, the main beam 120, connector 130, and secondary beam 140 are integrally formed; see also Figures 6 to 9 The auxiliary beam 190 is detachably mounted on the connector 130. This improves the structural strength of the connection between the main beam 120, connector 130, and secondary beam 140, and also reduces energy loss when the secondary beam 140 transfers energy to the main beam 120. Furthermore, the detachable mounting of the auxiliary beam 190 on the connector 130 enables modularity, allowing for the selection of energy harvesting solutions more suitable for different application scenarios.

[0070] See Figures 1 to 9 In some embodiments, two piezoelectric elements 150 are used, and the two piezoelectric elements 150 are respectively attached and fixed to the two plates of the main beam 120. In this way, the electrical output of the biomimetic locust-leg piezoelectric energy harvester can be increased while keeping the vibration energy of the main beam 120 constant.

[0071] In one embodiment, the thickness of the piezoelectric sheet 150 near the fixing member 110 is greater than the thickness of the portion of the piezoelectric sheet 150 away from the fixing member 110, and / or, the piezoelectric sheet 150 is disposed adjacent to the fixing member 110. Since the deformation of the main beam 120 near the fixing member 110 is larger when the main beam 120 vibrates, the electrical output of the biomimetic locust-leg piezoelectric energy harvester can be increased while keeping the vibration energy of the main beam 120 constant.

[0072] In some embodiments, the main beam 120, connector 130, and secondary beam 140 are made of 6061 aluminum alloy, which gives them high strength, light weight, good rigidity, and excellent machinability. The secondary beam 140 is fixed to the first mass block 160 with double-sided adhesive tape, avoiding the use of materials such as screws that may affect the magnet 180. The auxiliary beam 190 is fixed to the second mass block 200 with screws. The auxiliary beam 190 is also fixed to the connector 130 with screws. The auxiliary beam 190 is made of 6061 aluminum alloy, which gives it high strength, light weight, good rigidity, and excellent machinability. The piezoelectric sheet 150 can be made of PZT-5H material. The piezoelectric sheet 150 can be bonded to the main beam 120 with double-sided adhesive tape.

[0073] It should be noted that this application does not limit the circuit used for energy harvesting. A full-bridge rectifier circuit can be used as the main circuit to convert the AC power generated by the piezoelectric element 150 into DC power for use in various power systems. Specifically, the energy harvesting module of LTC3588-1 (a nanopower energy harvesting power supply) can be used, and components such as resistors and capacitors can be selected according to the characteristics of the designed device. The circuit diagram can be designed according to the datasheet of the LTC3588 module, including the connection method between the piezoelectric element 150 and the LTC3588 module, as well as necessary external components such as capacitors and rectifiers. For example, a 47uF capacitor can be connected externally to store energy, and an LED and a current-limiting resistor can be connected at the output terminal. Next, the LTC3588 module is integrated with the aforementioned energy harvester structure, and the connection terminals are soldered using DuPont wires to ensure that the piezoelectric element 150 can effectively convert vibration energy into electrical energy.

[0074] For each of the aforementioned implementation methods, a simplified model verification is performed, as follows:

[0075] I. For a single peak structure equipped with the aforementioned fastener 110, main beam 120, connector 130, secondary beam 140, piezoelectric sheet 150, and first mass block 160 (its structural diagram is shown below) Figures 1 to 3 (As shown) Perform simplified model validation:

[0076] Please refer to the simplified model diagram. Figure 10 .

[0077] The governing equations are as follows:

[0078] ,

[0079] In the formula For piezoelectric element clamping capacitors, The electromechanical coupling coefficient is... To pass The output voltage makes , Then we have:

[0080]

[0081] This yields the complex numerical expressions for voltage and power, and allows for the solution of the final solution:

[0082]

[0083]

[0084] The voltage-power curves were obtained using the Runge-Kutta method, as follows: Figure 11 As shown.

[0085] The results show that its characteristic frequency in the low-frequency range of 10-30Hz is 16.092Hz, the maximum voltage is 5.271V, and the maximum power is 0.028mW.

[0086] II. For the bipolar junction with the aforementioned fastener 110, main beam 120, connector 130, secondary beam 140, piezoelectric sheet 150, first mass block 160, auxiliary beam 190, and second mass block 200 (its structural diagram is shown below) Figure 6 , 7 (As shown) Perform simplified model validation:

[0087] Please refer to the simplified model diagram. Figure 12 .

[0088] The governing equations are as follows:

[0089]

[0090] make , , ,So

[0091]

[0092] At this time, the power and voltage are respectively

[0093]

[0094]

[0095] The voltage-power curves were obtained using the Runge-Kutta method, as follows: Figure 13 As shown.

[0096] The results show that within the 10-70Hz range, the first characteristic frequency is 16.198 Hz, and the second characteristic frequency is 42.096 Hz. The obtained voltages are 7.47 V and 1.419 V, respectively, and the electrical powers are 0.102 mW and 0.002 mW, respectively. Compared with the aforementioned single-peak method, the energy harvesting capability of the dual-peak method is improved.

[0097] III. For the single-peak structure equipped with the aforementioned fastener 110, main beam 120, connector 130, secondary beam 140, piezoelectric sheet 150, first mass block 160, fixing frame 170, and magnet 180 (its structural diagram is shown below) Figure 4 , 5 Verification was performed on a bipolar structure consisting of a fixing member 110, a main beam 120, a connector 130, a secondary beam 140, a piezoelectric sheet 150, a first mass block 160, a fixing frame 170, a magnet 180, an auxiliary beam 190, and a second mass block 200 (its structural diagram is shown below). Figure 8 , 9 Verification is performed as shown below:

[0098] For single peak values, please refer to the simplified model diagram. Figure 14 For the double peak, please refer to the simplified model diagram. Figure 15 .

[0099] The extension direction of the fixed frame 170 is taken as the Y direction, and the extension direction of the main beam 120 is taken as the X direction.

[0100] Then there is the analysis of the magnetic force formula:

[0101]

[0102] in The permeability of free space, and These are the magnetic moments of the magnet and the soft iron, respectively. For their center distance, It is the angle formed between the soft iron block and the permanent magnet during vibration.

[0103] With the advent of magnetism, the theoretical derivation underwent the following changes:

[0104]

[0105] Based on the aforementioned formula derivation, the voltage and power formulas after introducing nonlinear force can be calculated as follows:

[0106]

[0107]

[0108] The voltage and power curves were also obtained using the Runge-Kutta method, where the single peak value is shown in [reference needed]. Figure 16 Double peak Figure 17 .

[0109] It can be seen that the characteristic frequency of the single-peak pattern fluctuates within the range of 11.099 Hz, with a maximum amplitude of 12.399 Hz, a maximum voltage of 8.994 V, and a maximum power of 0.081 mW. For the double-peak pattern, the first characteristic frequency is 14.398 Hz, and the second characteristic frequency is 39.696 Hz. The resulting voltages are 19.983 V and 5.947 V, and the power is 0.200 mW and 0.018 mW, respectively. Therefore, with the introduction of magnet 180, both structures effectively expand the energy harvesting bandwidth; that is, they expand the effective energy harvesting range.

[0110] In addition, verification can also be performed based on finite element simulation, as follows:

[0111] The resonant frequency, mode shape, stress, potential, and generated electrical energy of piezoelectric element 150 were studied using finite element analysis, and the results were verified by comparison with analytical solutions. Simulations were performed on single-peak and double-peak models without and with corresponding magnet 180. The simulation analysis mainly focused on the stress distribution, voltage, and power response at different frequencies within the aforementioned biomimetic locust-leg piezoelectric energy harvester. Simulation steps: A sinusoidal excitation signal was used, and its sweep frequency was set and gradually varied at a rate of 0.1 Hz / s. The external resistor had a resistance of 106 Ω.

[0112] (a) Single peak with no corresponding magnet 180: Within the 10-30Hz range, there is only one characteristic frequency of 19.500Hz, a maximum voltage of 5.630V, and a maximum power of 0.016mW. For example... Figure 18 .

[0113] (b) Single peak value corresponds to magnet 180: within the 10-30Hz range, there is only one characteristic frequency of 19.925Hz, a maximum voltage of 12.770V, and a maximum power of 0.374mW. For example... Figure 19 .

[0114] (c) Dual-peak uncorresponding magnet 180: Within the 10-70Hz range, there are two characteristic frequencies of 17.500Hz and 50.100Hz, peak voltages of 7.042V and 1.349V, and peak powers of 0.025mW and 0.001mW. For example... Figure 20 .

[0115] (d) Dual peak values ​​correspond to magnet 180: within the 10-70Hz range, there are two characteristic frequencies of 18.100Hz and 45.000Hz, peak voltages of 13.214V and 5.394V, and peak powers of 0.132mW and 0.015mW. For example... Figure 21 .

[0116] The finite element simulation results also show that under the influence of magnetic force, the amplitude of energy harvesting increases, the bandwidth widens, and the frequency range of energy harvesting expands for both structures. Furthermore, for the double-peak structure, the distance between resonant frequencies is reduced, thereby promoting efficient energy conversion across a wider spectrum.

[0117] Alternatively, it can be verified experimentally; the experimental setup consists of an optical experimental stage, a small vibration table, a pulse generator, a power amplifier, a displacement sensor, and an external display device. The pulse generator produces sinusoidal excitation, and the small vibration table is provided by Hangzhou Yiheng Technology Co., Ltd.

[0118] Experimental results:

[0119] (a) Single peak with no corresponding magnet 180: Within the 10-30Hz range, there is only one characteristic frequency of 14.473Hz, a peak displacement of 0.165mm, and a peak voltage of 1.973V. For example... Figure 22 .

[0120] (b) Single peak value corresponds to magnet 180: Within the 10-30Hz range, there is only one characteristic frequency of 19.925Hz, a peak displacement of 1.112mm, and a peak voltage of 2.056V. For example... Figure 23 .

[0121] (c) Dual-peak without corresponding magnet 180: Within the 10-70Hz range, there are two characteristic frequencies of 12.427Hz and 43.996Hz, peak displacements of 0.871mm and 0.194mm, and peak voltages of 2.438V and 0.430V. For example... Figure 24 .

[0122] (d) Dual peak values ​​correspond to magnet 180: In the 10-70Hz range, there are two characteristic frequencies of 11.505Hz and 37.945Hz, peak displacements of 1.092mm and 0.160mm, and peak voltages of 3.104V and 1.166V. For example... Figure 25 .

[0123] The following table compares the simplified analytical solution, finite element simulation solution, and experimental results from the aforementioned model:

[0124] structure Research Content Analytical solution Finite element solution Experimental results Single peak value has no corresponding magnet; double peak value has no corresponding magnet; single peak value has a corresponding magnet. Resonant frequency (Hz) Voltage (V) Resonant frequency 1 (Hz) Resonant frequency 2 (Hz) Voltage 1 (V) Voltage 2 (V) Resonant frequency (Hz) Voltage (V) 16.0925.21716.19842.0967.4711.41912.3998.994 20.0007.17118.40049.0009.3553.69919.0007.148 12.0791.84512.42743.9962.4380.10511.6991.919 A single peak value corresponds to a magnet. Resonant frequency 1 (Hz) Resonant frequency 2 (Hz) Voltage 1 (V) Voltage 2 (V) 14.39839.69619.9835.947 18.64044.00019.6421.644 11.50537.9453.1041.166

[0125] This consistency demonstrates the rationality of the design, proving that the adopted energy harvesting structure is not only better in a non-integrated manner, but also that the integration strategy is effective. The correspondence between experimental and simulation results further confirms the accuracy and reliability of the design method, showcasing the potential and efficiency of this energy harvester in practical applications.

[0126] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present application, and that in actual applications, various changes in form and detail may be made thereto without departing from the spirit and scope of the present application. Any person skilled in the art may make changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be subject to the scope defined in the claims.

Claims

1. A biomimetic locust-leg-type piezoelectric energy harvester, characterized in that, include: A fastener, configured for attachment to the energy harvesting point; The main beam is in the shape of a straight plate, with one end fixed to the fixing member and extending in a direction away from the fixing member, wherein the extension direction of the main beam is perpendicular to the plate surface of the main beam; A connector is fixed to the other end of the main beam; A secondary beam, shaped like a bent plate or a similar bent plate, is located on the side of the connector away from the main beam, with one end fixed to the connector and extending in a bent or similar bent shape away from the main beam's plate surface. The two plate surfaces of the secondary beam face the same direction as the two plate surfaces of the main beam. The piezoelectric sheet is attached to and fixed to the surface of the main beam; An auxiliary beam is in the shape of a straight plate, with one end fixed to the connecting member and extending in a direction far from and close to the fixing member, wherein the extension direction of the auxiliary beam is perpendicular to the plate surface of the auxiliary beam; The auxiliary beam is configured to have a different resonant frequency than the main beam.

2. The biomimetic locust leg-type piezoelectric energy harvester according to claim 1, characterized in that, Also includes: The first mass block is fixed to the end of the sub-beam away from the connector.

3. The biomimetic locust leg-type piezoelectric energy harvester according to claim 2, characterized in that, At least a portion of the first mass block is made of a magnetic or magnetizable material; The biomimetic locust-leg piezoelectric energy harvester also includes: A fixing frame is located on the side of the first mass block away from the connector, and its extension direction is perpendicular to the surface of the main beam; and A magnet is disposed adjacent to the first mass block and fixed to the mounting frame; The fixing frame and the magnet are both spaced apart from the first mass block.

4. The biomimetic locust leg-type piezoelectric energy harvester according to claim 3, characterized in that, The number of magnets is two; The two magnets are spaced apart, and the two magnets are arranged sequentially along the extension direction of the fixing frame; A surface perpendicular to the extending direction of the fixing frame and located at the midpoint between the positions of the two magnets is a preset surface, wherein the geometric center of the first mass block is located on the preset surface.

5. The biomimetic locust leg-type piezoelectric energy harvester according to claim 3, characterized in that, The position of the magnet in the extension direction of the fixing frame is configured based on the vibration mode of the sub-beam; and / or, the fixing frame is provided with a plurality of fixing positions along its extension direction, and the magnet is selectively fixed in one of the fixing positions; and / or, the lower surface of the first mass block is provided with a plurality of grooves.

6. The biomimetic locust leg-type piezoelectric energy harvester according to claim 1, characterized in that, Also includes: The second mass block is fixed to the end of the auxiliary beam away from the connector.

7. The biomimetic locust leg-type piezoelectric energy harvester according to claim 1, characterized in that, The connector is plate-shaped; the connector has a first plate surface and a second plate surface that are disposed opposite to each other, and has a first end and a second end surface that are disposed opposite to each other in a direction perpendicular to the main beam plate surface; The main beam is fixed to the first end and located on the first plate surface; The sub-beam is fixed at a position between the first end and the second end of the connector and is located on the second plate surface; The auxiliary beam is fixed to the second end and located on the first plate surface.

8. The biomimetic locust leg-type piezoelectric energy harvester according to claim 7, characterized in that, The main beam, the connector, and the sub-beam are integrally formed; The auxiliary beam is detachably mounted on the connector.

9. The biomimetic locust leg-type piezoelectric energy harvester according to claim 1, characterized in that, Also includes: The piezoelectric element is two in number, and the two piezoelectric elements are respectively attached and fixed to the two plates of the main beam. And / or, The thickness of the portion of the piezoelectric sheet closest to the fixing member is greater than the thickness of the portion of the piezoelectric sheet furthest from the fixing member. And / or, The piezoelectric element is disposed adjacent to the fixing element.

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