Shear piezoelectric energy collection device with forked structure

Abstract

The invention relates to the technical field of piezoelectric energy collection. The invention provides a shearing piezoelectric energy collecting device with a forked structure. The shearing piezoelectric energy collecting device comprises a base, a shearing type piezoelectric unit, a supporting piece, a vibrating beam and a force transmission arm. The whole device is of a symmetrical structure relative to the middle of the vibrating beam, the vibrating beam is transversely arranged on the upper portion of the center of the device, the two ends of the vibrating beam are connected with the force transmission arms respectively, the other ends of the force transmission arms are connected to the upper surface of the bearing piece, the bearing piece is arranged on the shear type piezoelectric unit, and the shear type piezoelectric unit is arranged on the base. The force transmission arm comprises a main transmission section and a bifurcated structure, one end of the main transmission section is connected with the vibrating beam, the other end of the main transmission section is connected with the bifurcated structure, the bifurcated structure comprises a plurality of branch sections, one ends of the plurality of branch sections are converged and connected to the end part of the main transmission section, and the other ends of the plurality of branch sections are connected to different positions of the supporting sheet. According to the piezoelectric energy collecting device, the force transmission arm is arranged to be of a forked structure, multi-frequency modal linkage is achieved, the responsiveness of the piezoelectric energy collecting device is improved, and the frequency coverage range of the piezoelectric energy collecting device is widened.

Description

Technical Field

[0001] The present application relates to the technical field of piezoelectric energy harvesting, and in particular to a shear piezoelectric energy harvesting device with a bifurcated structure. Background Art

[0002] With the rapid development of wireless sensing systems, edge computing devices, and wearable electronic devices, micro-vibration energy harvesting technology is becoming an important means of supporting distributed self-powered systems. Piezoelectric energy harvesting, due to its compact structure, sensitive response, flexible deployment, and high energy density, has broad application prospects for harvesting micro-energy from environmental vibrations. It is particularly suitable for complex scenarios involving non-sustained micro-vibrations, such as bridge structures, mechanical equipment, and human motion.

[0003] Existing piezoelectric energy harvesting devices typically use cantilever beams, curved beams, or bridge structures as energy coupling units, relying on the structure's vibration response in a specific direction to drive the piezoelectric element to deform. Real-world vibrations often exhibit complex frequency components, dynamic directional variations, and unstable excitation modes. As a result, traditional structures are unable to fully stimulate effective deformation of the piezoelectric element, significantly reducing energy conversion efficiency. To expand the frequency response range, some existing solutions increase adaptability by adding multiple piezoelectric elements. However, such designs are often limited to a specific frequency range and cannot maintain efficient energy conversion across a wider frequency range. Another approach is to increase the frequency response range by adjusting the structural flexibility. While this method can improve response in certain frequency bands, it often increases structural complexity, potentially reducing overall stability, and increasing manufacturing costs. Additionally, some designs have attempted to expand the frequency response by introducing different vibration modes, but these solutions still rely on a single directional vibration response path, making it difficult to maintain consistent energy conversion efficiency across a wide range of excitation frequencies.

[0004] Although existing technologies have made various attempts to extend the frequency response, they often result in increased device complexity, higher manufacturing costs, and reduced stability. Therefore, there is an urgent need to develop a piezoelectric energy harvesting device that is easy to manufacture, structurally stable, and capable of maintaining efficient energy conversion performance over a wide frequency range, adapting to more complex vibration environments, and improving the overall energy harvesting efficiency of the device. Summary of the Invention

[0005] The purpose of the present invention is to provide a shear piezoelectric energy harvesting device with a bifurcated structure to address the deficiencies in the above-mentioned prior art, so as to solve the problems of insufficient coupling capability and limited frequency response range of the piezoelectric energy harvesting device in the prior art.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: The present application provides a shear piezoelectric energy collection device with a bifurcated structure, comprising a vibration beam, a force transmission arm, a support plate, a shear-type piezoelectric unit, and a base. The device as a whole is a bilaterally symmetrical structure with the middle of the vibration beam as the symmetry axis. The vibration beam is laterally arranged at the upper part of the center of the device, and its two ends are respectively connected to the force transmission arm. The other end of the force transmission arm is connected to the upper surface of the corresponding support plate. The support plate is arranged on the upper surface of the shear-type piezoelectric unit, and the shear-type piezoelectric unit is arranged on the upper surface of the base. The force transmission arm includes a main transmission section and a bifurcated structure. One end of the main transmission section is connected to the vibration beam, and the other end of the main transmission section is connected to the bifurcated structure. The bifurcated structure includes multiple branch sections. One end of the multiple branch sections converges and is connected to the end of the main transmission section, and the other ends of the multiple branch sections are respectively connected to different positions on the support plate.

[0007] In this device, the left and right structures are arranged symmetrically with the vertical plane where the midpoint of the vibration beam is located as the reference. Two sets of force transmission arms are mirror-imaged at both ends of the vibration beam and are respectively connected to the corresponding support plates, piezoelectric units and bases, forming a symmetrical coupling structure with bridge-type characteristics. When external excitation acts on the entire device, the vibration beam located in the middle produces periodic displacement in the vertical direction due to its suspended setting, driving the force transmission arms at both ends to respond synchronously. In the process of moving with the vibration beam, the force transmission arm causes the forked structure at its end to deviate, pulling the support plate and the piezoelectric unit to form a relative displacement, thereby generating shear deformation at the position of the piezoelectric unit. This shear deformation acts concentratedly on the shear-type piezoelectric unit installed between the base and the support plate, triggering a strain response in its polarization direction, thereby generating charge accumulation between the electrodes and forming an output electrical signal, thereby realizing the effective collection of mechanical vibration energy.

[0008] The device of the present application adopts a symmetrically arranged bifurcated structure transmission arm to decompose the process of force transmission from the vibration beam downward into multiple paths. This structure enables the device to have richer natural modal forms by introducing multiple combined areas of stiffness distribution and boundary response modes. When the external excitation frequency changes, the bifurcated structure of the transmission arm causes the support plate to produce relative displacement, thereby generating shear strain inside the shear-type piezoelectric unit. Different branch paths can trigger corresponding modal responses. The main transmission section dominates the low-frequency excitation, while each branch section adapts to high-frequency excitation, forming a multi-frequency excitation response mechanism with modal complementarity, path separation, and deformation coordination, which effectively avoids the problem of frequency band narrowing caused by energy concentration in a single mode, thereby expanding the excitation frequency band of shear strain and improving the electrical signal output coverage and response stability of the device under broadband excitation conditions.

[0009] Furthermore, the number of branch segments is 2 to 6. Introducing multiple branches provides the structure with more response channels, which helps to stimulate richer modal behaviors, thereby expanding the response frequency band.

[0010] Furthermore, the bifurcated structure includes a first branch segment and a second branch segment.

[0011] Furthermore, a flexible connection is provided between the main transmission section and the bifurcated structure. The flexible connection provides local rotational freedom, alleviates the limitation of the rigid coupling of the structure on the shear path, and improves the modal adaptability.

[0012] Furthermore, the angle between any two adjacent branch segments in the plurality of branch segments is 10°-30°. Setting an appropriate angle range between the plurality of branch segments can effectively control the degree of structural deflection and strain amplitude, and balance structural stability and response sensitivity.

[0013] Furthermore, the cross-sectional dimensions of the main transmission section are smaller than those of the bifurcated structure. This geometric difference introduces a change in stiffness distribution, making the main transmission section more sensitive to low-frequency excitations while the bifurcated structure, due to its higher stiffness, is more suitable for responding to high-frequency excitations, thereby expanding the frequency response range of the structure.

[0014] Furthermore, the main transmission section and the bifurcated structure are made of materials with different elastic moduli. These different materials further enhance the structure's adaptability to excitations of varying frequencies, thereby improving its response efficiency under wide-band input conditions.

[0015] Furthermore, the main transmission section utilizes a material with a high elastic modulus, while the bifurcated structure utilizes a material with a low elastic modulus. The higher elastic modulus material in the main transmission section provides strong rigid support under vibration beam excitation, ensuring clear transmission direction and efficient force transmission. The lower elastic modulus material in the bifurcated structure is more susceptible to deformation, contributing to the formation of effective shear strain. This combination of rigidity and flexibility improves the structure's adaptability to broadband excitation and enhances the sensitivity and sustainability of the shear response.

[0016] Furthermore, two bases are respectively arranged outside the two ends of the vibration beam, so that the force transmission arm is arranged obliquely, enhancing the shear relative displacement between the support plate and the piezoelectric unit, and improving the shear strain strength and energy conversion efficiency of the device.

[0017] Furthermore, a mass block is installed on the vibration beam. The mass block can adjust the resonant frequency of the structure by adjusting the inertia parameters, which helps to increase the low-frequency response amplitude and thus improve the energy harvesting capability in low-frequency environments.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The device of the present application has multiple force transmission paths by setting a bifurcated structure on the force transmission arm. When the external excitation frequency changes, the bifurcated structure can form multiple independent response paths, which expands the frequency response range of the device and improves the performance stability under broadband excitation. Unlike traditional designs that rely on a single response path, this structure ensures that the device can maintain efficient shear strain output under different frequency conditions through reasonable geometric arrangement and stiffness differences, thereby effectively avoiding the problem of reduced energy conversion efficiency under frequency fluctuations in traditional designs, broadening the operating frequency band of the device and improving its adaptability under broadband excitation.

[0019] (2) This application optimizes the device's adaptability to frequency changes by introducing a bifurcated structure. This structure improves the device's responsiveness to frequency fluctuations or changes in the excitation environment without increasing the overall volume and complexity, ensuring that it can still operate efficiently under broadband excitation. At the same time, the overall structure adopts a symmetrical layout, is highly integrated and manufacturing-friendly, and is suitable for micro-energy harvesting scenarios with limited space and structural constraints. It exhibits excellent stability and adaptability, especially in application conditions with large frequency changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of a shear piezoelectric energy harvesting device with a bifurcated structure provided by the present invention; Figure 2 A schematic diagram of the structure of a force transmission arm on one side of another shear piezoelectric energy harvesting device with a bifurcated structure provided by the present invention; Figure 3 A schematic diagram of a side bifurcated structure of another shear piezoelectric energy harvesting device with a bifurcated structure provided by the present invention.

[0021] Icon: 1-vibration beam; 2-force transmission arm; 3-support plate; 4-shear type piezoelectric unit; 5-base; 21-main transmission section; 22-first branch section; 23-second branch section; 24-third branch section; 25-fourth branch section. DETAILED DESCRIPTION

[0022] In order to make the implementation process of the present invention clearer, it will be described in detail below with reference to the accompanying drawings.

[0023] The present invention provides a shear piezoelectric energy harvesting device with a bifurcated structure, such as Figure 1As shown, it includes a vibration beam 1, a force transmission arm 2, a support plate 3, a shear-type piezoelectric unit 4, and a base 5. The device as a whole is a bilaterally symmetrical structure with the middle part of the vibration beam 1 as the symmetry axis. The vibration beam 1 is horizontally arranged at the upper part of the center of the device, and its two ends are respectively connected to the force transmission arm 2. The other end of the force transmission arm 2 is connected to the upper surface of the corresponding support plate 3. The support plate 3 is arranged on the upper surface of the shear-type piezoelectric unit 4, and the shear-type piezoelectric unit 4 is arranged on the upper surface of the base 5. The force transmission arm 2 includes a main transmission section 21 and a forked structure. One end of the main transmission section 21 is connected to the vibration beam 1, and the other end of the main transmission section 21 is connected to the forked structure. The forked structure includes multiple branch sections. One end of the multiple branch sections converges and is connected to the end of the main transmission section 21, and the other ends of the multiple branch sections are respectively connected to different positions on the support plate 3.

[0024] The base 5 is made of aluminum alloy and has good rigidity, corrosion resistance and processing performance. The base 5 is a rectangular flat plate structure with a length and width dimension usually between 15-60 mm and a thickness of 1-3 mm. The specific dimensions can be designed to match the area of ​​the shear-type piezoelectric unit 4 and the deformation amplitude of the vibration beam 1 to ensure that the device has sufficient mounting support surface and overall structural stability. In order to enhance the interface bonding strength with the adhesive, the surface of the base 5 can be anodized or roughened. The two symmetrical bases 5 can be structurally separated, with the force transmission structure composed of the vibration beam 1, the force transmission arm 2 and the support plate 3 and the shear-type piezoelectric unit 4 connected in the middle. The horizontal position of the base 5 is on the outside of the two ends of the vibration beam 1, so that the force transmission arm 2 is arranged obliquely outward, and the two bases 5 are at the same horizontal height to maintain the symmetry of the response path of the force transmission arm 2 and the balanced distribution of the shear load. The fixing method of the base 5 can be selected according to the actual application environment, including screw fixing, structural adhesive bonding or magnetic adsorption. At the same time, in order to improve the overall vibration resistance and long-term stability of the structure, a damping pad or elastic gasket can be added to the bottom surface of the base 5 to absorb high-frequency interference and reduce the inhibitory effect of the rigidity of the base 5 on the free vibration of the force-conducting structure, thereby enhancing the frequency response sensitivity of the device under actual installation conditions.

[0025] The shear-type piezoelectric unit 4 can be a shear-type piezoelectric element. Common materials include piezoelectric ceramics (such as PIC255 and PZT-5H), piezoelectric single crystals (such as PMN-PT), and flexible piezoelectric polymers (such as PVDF). The shear-type piezoelectric unit 4 is typically a rectangular or square sheet structure, with dimensions comparable to or smaller than the corresponding base 5, allowing the base 5 to protect the shear-type piezoelectric unit 4. Its side length is preferably in the range of 8-15 mm, and its thickness is 0.5-2 mm. This size range ensures a good shear strain response within the limited structural space, while ensuring the output signal has sufficient amplitude and matches the area of ​​the support plate 3 and the modal deformation characteristics of the force-conducting structure. The shear direction of the piezoelectric element is set within its plane, with the polarization direction perpendicular to the surface of the support plate 3. The operating directions of the two shear-type piezoelectric units 4 are kept consistent or arranged in mirror-symmetric fashion, ensuring coordinated excitation response directions and a stable and efficient electrical signal output. The shape of the support sheet 3 is consistent with that of the shear-type piezoelectric unit 4, and its thickness is usually 0.5-2 mm. It is necessary to ensure its elastic coordination during the deformation process and have sufficient structural integrity to prevent bonding failure or partial detachment of the shear-type piezoelectric unit 4 due to excessive deformation.

[0026] The device's core force transmission structure consists of a vibration beam 1, force transmission arms 2, and support plates 3. They are arranged bilaterally symmetrically, with the vertical plane at the midpoint of the vibration beam 1 serving as the plane of symmetry. This structure achieves directional dispersion and response diversity through multi-path force transmission, helping to improve energy harvesting efficiency under excitation at different frequencies. The vibration beam 1 is suspended horizontally above the center of the device structure, elevated above the plane of the support plates 3. It receives external excitation and transmits it to the structures on either side. Force transmission arms 2 are connected at each end of the vibration beam 1. These arms extend diagonally downward to the surface of the support plates 3 to enhance the relative shear displacement between the support plates 3 and the shear-type piezoelectric elements 4. Support plates 3 are mounted on the upper surfaces of the shear-type piezoelectric elements 4 on either side to guide structural deformation to the shear-type piezoelectric elements 4, achieving shear coupling. This symmetrical structural arrangement enables the force transmission structure to maintain a stable force path and structural modal equilibrium when subjected to vibration excitation, thereby improving the response consistency and output stability of the piezoelectric elements and avoiding energy loss caused by excitation bias.

[0027] The transmission arm 2 is composed of a main transmission section 21 and a bifurcated structure. Figure 1As shown, the bifurcated structure includes a first branch segment 22 and a second branch segment 23. One end of the main transmission segment 21 is fixedly connected to the end of the vibration beam 1, and the other end is connected to the bifurcated structure; the bifurcated structure is arranged radially, and one end of the first branch segment 22 and the second branch segment 23 converges to a point fixedly connected to the lower end of the main transmission segment 21, and the other radial ends of the first branch segment 22 and the second branch segment 23 are fixed at different positions on the support plate 3, forming a non-collinear multi-path connection mode. This geometric configuration can form an automatic selective response between different paths according to the difference in external excitation, thereby enhancing the structure's adaptability to changes in excitation frequency. Among them, the main transmission segment 21 is tilted downward from the vibration beam 1 and away from the center of the device. The tilted setting of the main transmission segment 21 not only optimizes the force distribution of the support plate 3, making it more balanced under multi-point connection, but also enables the end of the force transmission arm 2 to generate more horizontal displacement components during the vibration process, which helps to form an effective shear path at the shear-type piezoelectric unit 4, thereby improving the strain excitation efficiency.

[0028] The direction of the bifurcation structure can be changed according to the design requirements to adapt to the excitation conditions of different frequencies. The first branch section 22 can be arranged along the extension direction of the main transmission section 21, forming an approximately collinear structural relationship with the main transmission section 21, forming a force transmission path with a continuous direction, which is conducive to the stable conduction of force. The second branch section 23 is tilted relative to the first branch section 22, extending outward and forming a certain angle with it, thereby forming a three-dimensional divergent bifurcation structure, which helps to guide the device to produce an effective response under non-vertical excitation. Figure 2 As shown, the first and second branch segments 22, 23 of the branch structure can also be arranged in an inclined direction relative to the main transmission segment 21, extending toward either side thereof, forming an overall divergent configuration with either asymmetric or symmetrical expansion. This type of arrangement can provide a richer force transmission path in working environments with uncertain excitation directions, helping to stimulate shear strain in different directions, further enhancing the device's adaptability to complex excitation conditions and output stability.

[0029] Furthermore, in the force transmission arm 2, a flexible connection portion is provided between the main transmission section 21 and the bifurcated structure. The flexible connection portion is an elastic connection structure, preferably in the form of an elastic sheet, a flexible joint or a variable cross-section transition section, the elastic modulus of its material is in the range of 0.5-5GPa, and the thickness is preferably 0.1-0.5mm. The setting of the flexible connection portion allows a small relative rotation angle of 1°-5° between the main transmission section 21 and each branch section while ensuring basic support stiffness, thereby realizing a multi-directional shear response path and improving the modal decoupling characteristics and frequency adaptation range of the device. The flexible connection portion can be connected to the main transmission section 21 and the bifurcated structure respectively by means of screw clamping, adhesive adhesion or embedded snap connection. Preferably, when the flexible connection portion adopts an elastic sheet, it can be fixed between the main transmission section 21 and the bifurcated structure by a mechanical pressure plate or screws; when a flexible hinge connection is adopted, it can be surface-bonded with industrial adhesives or fixed with embedded slots; if it is a variable cross-section transition section structure, it can be integrally formed or connected by heat press fitting.

[0030] On the basis of the above structure, the bifurcated structure may further include a third branch segment 24, a fourth branch segment 25, etc., one end of each branch segment is connected to the connection area between the main transmission segment 21 and the bifurcated structure, and the other end extends to multiple different positions on the support sheet 3, such as Figure 3 shown. Figure 3 This is a four-branch structure, with each branch segment arranged in different spatial directions, corresponding to multiple connection points on support plate 3. Angular spacing can be set between the multiple branches, providing the structure with more shear response paths to accommodate more complex excitation conditions. This multi-branch configuration introduces more independently responsive deformation channels during the vibration response process, expanding the structure's effective frequency response range.

[0031] Specifically, if Figure 3 As shown, the angles between the first branch segment 22 to the fourth branch segment 25 are 15°, 20° and 30°, respectively, presenting a gradually increasing angle arrangement. This non-uniform distribution is conducive to breaking the phenomenon of response frequency between branch segments, enhancing the directional separation of modal response, and introducing richer response mode combinations through asymmetric configuration, thereby improving the recognition ability and stability of the system under multi-frequency excitation. Preferably, the angle between any two adjacent branch segments in the multiple branch segments is 10°-30°. This angle range helps to balance the structural stability and directional response capability without weakening the connection stiffness. If the angle is set too small, less than 10°, the branch segments tend to be collinear, the response directions overlap, and it is difficult to excite effective directional differentiation modes; if the angle is set too large, exceeding 30°, the structure is too wide in the transverse direction, which may cause stress concentration and inconsistent response, and may also cause uneven force on the ends of the branch segments, affecting the stability of the structure.

[0032] On this basis, based on the actual installation space of the support plate 3 and the angle arrangement range of each branch segment, the number of branch segments ranges from 2 to 6, so as to maintain the diversity of the shear path distribution while taking into account structural stability and spatial adaptability. The total expansion angle of multiple branch segments does not exceed 120° to avoid excessive expansion of the structure to both sides, resulting in uneven response or interference risks. Through the above-mentioned asymmetric angle design and reasonable control of the number of branch segments, it is possible to effectively suppress structural deflection, improve strain excitation efficiency, and achieve richer response patterns and more stable energy output in a multi-frequency and multi-directional excitation environment.

[0033] To enhance the structure's adaptability to multi-frequency excitation, the main transmission section 21 and the bifurcated structure of the force transmission arm 2 have different geometric dimensions and materials. Specifically, the cross-sectional dimensions of the main transmission section 21 are smaller than those of the bifurcated structure. The cross-section of the main transmission section 21 is preferably rectangular, with a length of 6-12 mm and a width of 1-1.5 mm, while the cross-sectional dimensions of the bifurcated sections are preferably rectangular, with a length of 6-12 mm and a width of 2-4 mm. This structure achieves stiffness differentiation by maintaining a consistent cross-sectional length and varying the width (i.e., the thickness of each section of the force transmission arm 2). This allows the main transmission section 21 to deform more easily under low-frequency or large-displacement excitation, leading to a rapid structural response. The stiffer bifurcated sections provide complementary response channels under high-frequency or directional excitation, guiding external excitations of different frequency components to couple along distinct structural paths, thereby improving the overall frequency response bandwidth and response diversity of the structure. Specifically, the main transmission section 21 has a narrow thickness range, primarily for sensitive response to the starting mode, while the bifurcated sections have a wide thickness range, providing high-frequency steady-state support. The two sections complement each other in terms of functional positioning. If the broadband response capability needs to be further improved, the thickness ratio between the main transmission section 21 and the branch section can be fine-tuned, such as a thickness ratio of 1:2-1:3, or a partial step-type thickness change can be introduced on the bifurcated structure to adjust the response intensity and duration of the bifurcated structure to vibrations of different frequencies.

[0034] Specifically, the main transmission section 21 and the bifurcated structure are made of materials with different elastic moduli to further expand the response frequency range of the structure. Among them, the main transmission section 21 adopts a material with a higher elastic modulus to provide a main conduction path, and the bifurcated structure adopts a material with a relatively low elastic modulus to introduce a multi-modal response channel. The main transmission section 21 can be made of stainless steel, glass fiber reinforced composite material or metal matrix composite material, and its elastic modulus is preferably 100-150GPa. It has strong rigid support performance and can stably transmit force to the branch connection area under vibration input, ensuring that the structural response direction is clear and the force transmission efficiency is high. The bifurcated structure can use different materials according to the functional differences of the branch segments. Among them, at least one branch segment with the shortest force transmission path in the structure is preferably made of medium-to-high stiffness materials with an elastic modulus of 60-120GPa, such as spring steel, titanium alloy or aluminum alloy, to provide support and enhance the effective transmission of the main shear force; the remaining branch segments can use flexible materials with an elastic modulus of 10-40GPa, such as polyurethane, thermoplastic elastomer (TPE), flexible polymer-based composite materials, etc., which have good directional deformation capabilities, facilitate effective response under high-frequency excitation conditions, stimulate shear strain and expand the modal participation path. For example, in Figure 2 In the double-branch structure shown, the first branch segment 22 can be made of medium-to-high stiffness materials to construct a relatively stable force conduction path; the second branch segment 23 can be made of flexible materials or materials with a low elastic modulus to improve the response sensitivity of the structure under non-axial excitation and enhance its deformation coordination ability and frequency response range.

[0035] By introducing a collaborative configuration of geometric size differences and material stiffness differences in the force transmission arm 2, the structure constructs a multi-path coupling mechanism with complementary response characteristics during the force transmission process. The main transmission section 21 uses a rigid material with a high elastic modulus to provide stable support, and the cross-sectional design maintains a relatively small thickness to enhance its deformation sensitivity, allowing it to respond preferentially under low-frequency or large displacement excitation conditions and quickly stimulate shear strain. The bifurcated structure uses a flexible material and is geometrically equipped with a larger cross-sectional size to enhance structural stiffness, thereby gradually participating in the response under high-frequency excitation conditions, forming an auxiliary shear path and stimulating differential modes. The above design achieves response separation and coupling optimization of the structure under multi-frequency excitation conditions through a collaborative strategy of material rigidity and flexibility configuration and dimensional thickness control, thereby constructing a multi-path decoupled shear force transmission mechanism. This structure effectively expands the adaptability range to multi-frequency excitation, improves the triggering efficiency of shear strain and the coverage capability of modal response, and enables the shear-type piezoelectric unit 4 to be continuously and effectively excited under complex excitation environments.

[0036] On the basis of the above-mentioned bifurcated structure, the force transmission arm 2 can also be designed with a multi-stage bifurcated structure, that is, a secondary or multi-stage branch segment is further arranged on the basis of the primary branch segment, so that the force conduction path forms a layered radial structure in space. This configuration has advantages in structural response characteristics, and is particularly suitable for dealing with vibration scenarios with a wide excitation frequency distribution and complex directional components. In the multi-stage bifurcated arrangement, the primary branch segment acts as the dominant channel to bear the main modal response, while the secondary branch segment can form a supplementary response path in different directions or local high-frequency modes, thereby expanding the structural modal response form, increasing the number and distribution area of ​​the force transmission path, and helping to stimulate effective local strains at different frequencies. The effectiveness of the multi-stage bifurcated structure depends on the coupling of multiple factors, including the material configuration of the branch segments at each level, the structural stiffness distribution, the branch angle setting, and the connection method.

[0037] The force transmission structure of the device of the present invention can be made of metal materials. Suitable materials include stainless steel, aluminum alloy, or titanium alloy. The specific material can be selected based on the device's requirements for elastic modulus, fatigue resistance, structural rigidity, or weight control. The structure can be integrally fabricated from sheet metal by laser cutting and then bending, making it suitable for rapid integrated manufacturing of the continuous structure of the vibration beam 1 and the main transmission section 21 in the device. This process effectively ensures structural continuity and rigidity consistency in key areas, improves the stability of the force transmission path, and reduces modal misalignment and stress concentration caused by assembly errors or improper connections. The vibration beam 1 is typically a rectangular strip-shaped structure. Its length and width can be adjusted to match the layout dimensions of the shear-type piezoelectric unit 4 and the required structural symmetry. The thickness is preferably within the range of 0.5-3 mm to balance modal response sensitivity and structural support rigidity. The force transmission arm 2, the key load-transmitting component connecting the vibration beam 1 and the support plate 3, can be manufactured using methods such as sheet metal stamping, CNC milling, laser cutting, or powder metallurgy. The specific process can be flexibly selected based on mass production needs, precision requirements, and the type of material being processed. For bifurcated structures with more complex structures, high-precision integrated preparation can be achieved by three-dimensional forming, sheet metal bending, laser additive manufacturing (such as metal 3D printing) or multi-cavity injection molding to ensure good mechanical stability and geometric accuracy in the bifurcated connection area. If the force transmission structure in the device is manufactured by assembly, the various connection parts can be connected by welding, screw fastening, mechanical snap fastening, riveting or structural adhesive bonding, among which the connection area between the vibration beam 1 and the force transmission arm 2 is preferably continuous welding or forming and bending transition to maintain the rigid consistency of the load path. The connection between the support plate 3 and the bifurcated structure of the force transmission arm 2 is preferably surface bonding or precision positioning press fitting to ensure the strain transfer consistency and response balance of the contact interface. In order to improve the surface contact bonding effect, the support plate 3 can be pre-set with fine texture or coating treatment to improve the adhesion between the structural adhesive and the metal surface. After the initial forming and assembly of the device is completed, in order to improve the weather resistance and mechanical stability of the structure in long-term operation, its surface can be subjected to anti-corrosion and fatigue enhancement treatments, such as anodizing, electroplating, coating or heat treatment, to adapt to energy collection application requirements under working conditions such as high humidity, high temperature, vibration or long-term fatigue loads.

[0038] In order to enhance the response capability of the structure under low-frequency excitation conditions, a mass block can be set on the vibration beam 1, and the modal frequency can be lowered by introducing additional inertia, thereby improving the sensitivity of the structure to low-frequency input. The mass block is preferably arranged on the upper surface of the vibration beam 1 and is set at the geometric center position in the length direction of the vibration beam 1, that is, at the symmetry axis of the device structure, to adjust the structural response distribution and improve the excitation efficiency of the shear-type piezoelectric unit 4. The mass block can be rigidly connected to the vibration beam 1 by welding, screw fixing or structural adhesive bonding, and preferably adopts surface-mount installation to improve the connection stability and ensure the consistency of deformation conduction. The shape of the mass block can be block-shaped, and its size can be selected according to the structural layout and frequency response range. Preferably, the size range of the long side direction is 8-20mm, taking into account the inertia adjustment effect and structural integration. The mass block is preferably made of a material with a higher density to introduce an effective inertial effect in a limited space. Specifically, the material can be selected from tungsten alloy, brass, stainless steel or high-density polymer composite material, and its mass is preferably 3g-20g.

[0039] Furthermore, when the mass block is coordinated with the bifurcated structure in the force transmission arm 2, the frequency response characteristics of the structure can be adjusted. The mass block introduces concentrated inertia, making the structure more resonant under low-frequency excitation, thereby enhancing the response sensitivity of the main transmission section 21. The bifurcated structure, by establishing multiple force transmission paths, enables the structure to effectively deform even when the excitation direction is offset, improving its adaptability to excitation at different angles. The two work together to form distinguishable shear response paths under different frequency and angle conditions. Through the combined action of inertial drive and geometric guidance, multimodal excitation and multi-channel coupling are achieved, thereby expanding the structure's operating frequency bandwidth, improving the shear strain response efficiency and the sustainability of energy harvesting.

[0040] Furthermore, the upper surface of the shear-type piezoelectric unit 4 and the support sheet 3, as well as the lower surface and the base 5, are fixed by surface contact. Preferably, the support sheet 3 and the base 5 are bonded to the upper and lower surfaces of the shear-type piezoelectric unit 4, respectively, by adhesion, to form a large-area, high-strength bonding interface. Compared with the traditional point contact method, this surface contact connection structure performs better in terms of shear coupling effect, strain conduction efficiency, and electrical connection stability. Through this structural arrangement, the device can enable the piezoelectric element to obtain uniform and sufficient strain input when shear deformation occurs, thereby improving the consistency and amplitude stability of the signal output. To ensure the effective response of the shear-type piezoelectric unit 4, its installation accuracy has a significant impact on the overall performance. During the installation process, the thickness of the bonding layer between the shear-type piezoelectric unit 4 and the support plate 3 and the base 5 should be controlled to not exceed 0.1 mm to avoid strain transfer attenuation or coupling lag due to excessive thickness of the adhesive layer. It is preferred to use an adhesive material with conductivity and low-temperature curing properties, such as a two-component conductive epoxy adhesive or conductive silicone, to ensure that during the bonding process, both firm fixation and electrical connection are achieved without damaging the polarization direction and performance stability of the piezoelectric material.

[0041] Furthermore, the electrical connection method of the two shear-type piezoelectric units 4 in the device can be flexibly configured according to the application scenario and output requirements. The two shear-type piezoelectric units 4 can be connected to the same energy collection circuit or respectively connected to independent collection channel circuits. When the shear-type piezoelectric units 4 are connected to the same collection circuit, the centralized output and unified rectification of the signal can be realized, which is convenient for wiring simplification and module integration, and the system structure is more compact. It is suitable for synchronous response devices under symmetrical excitation, which is conducive to the integrated design of the energy management module; and when the shear-type piezoelectric units 4 are respectively connected to independent collection channels, they are used to respond to the vibration states of different supporting structures respectively, and have higher functional scalability and asynchronous response recognition capabilities, which are suitable for differential detection, multi-frequency response recognition or multi-modal monitoring needs. The device of the present invention is a symmetrical structure, the external excitation is applied to the center position of the vibration beam 1, and the force transmission path is relatively balanced. It is preferred to connect the two shear-type piezoelectric units 4 in parallel to the same rectification circuit to enhance the response consistency and output stability during the energy collection process. The specific connection method can be selected in series or parallel mode according to the voltage and current characteristics of the piezoelectric element, and connected to a rectifier bridge, charge amplifier or energy storage module to achieve steady-state signal conditioning and energy storage functions.

[0042] The polarization direction of the piezoelectric element is preferably perpendicular to the surface of the support plate 3, and the shear direction is within the plane of the piezoelectric element, with the two directions orthogonal. The polarization directions of the two shear-type piezoelectric units 4 can be consistent, with their polarization axes perpendicular to the surface of the support plate 3 and pointing in the same direction, and the electrode leads connected with the same polarity. Alternatively, a mirror-symmetric arrangement can be used, with the electrodes reversed to ensure that the output charge directions of the two piezoelectric elements are aligned. These two polarization and wiring configurations ensure that the phase direction of the electrical signals output by the two piezoelectric elements is consistent during the structural vibration response, thereby avoiding charge cancellation or signal interference and improving the overall power conversion efficiency and response consistency of the system. Furthermore, to enhance system stability and long-term operational reliability, the piezoelectric elements can be equipped with a flexible encapsulation structure, such as an epoxy resin layer, silicone rubber, or polyurethane insulating protective layer, to prevent oxidation of the conductive interface, aging of the piezoelectric element, or adhesive separation. The lead-out electrodes can be encapsulated with copper foil, a flexible printed circuit board (FPC), or a micro-connector, guiding stable signal output and adapting to system integration wiring or modular design requirements.

[0043] In practical applications, the shear piezoelectric energy harvesting device is suitable for a variety of complex structural environments with unstable low-frequency vibrations or wide-frequency excitations, including but not limited to mechanical equipment housings, bridge guard plates, pipe supports, human-machine interface panels, and wearable device support modules. When in use, the base 5 can be reliably mounted on the surface of the target structure or the vibration-sensitive part of the internal frame by means of screw fastening, structural adhesive fixation, or elastic snap fastening, so that it is placed on the effective vibration transmission path under actual working conditions. Preferably, the two bases 5 are arranged in a symmetrical area of ​​the structure or an estimated vibration energy concentration area to ensure that the excitation load can be effectively coupled to the force transmission arm 2 and transmitted to the shear-type piezoelectric unit 4, thereby improving the energy collection efficiency. After the device is installed, when the external vibration excitation is transmitted to the vibration beam 1, the force transmission arm 2 generates bending, shearing or compound deformation, and the resulting structural response acts on the surface of the shear-type piezoelectric unit 4 through the support plate 3, inducing shear strain inside the shear-type piezoelectric unit 4 and outputting a charge signal. The main transmission section 21 in the structure is responsible for conducting low-frequency components, preferentially stimulating the primary modal response. The bifurcated structure forms an auxiliary path under high-frequency excitation, stimulating secondary modes, thereby improving the consistency and bandwidth coverage of energy harvesting in complex multi-frequency environments. The electrical signal output by the shear-type piezoelectric unit 4 can be connected to the energy management module via a wire, flexible circuit, or micro-connector, and then connected to a rectifier circuit, charge amplifier, capacitor energy storage unit, or micro-power supply circuit to achieve stable conditioning and storage of electrical energy. This device has excellent functional scalability and is suitable not only for energy supply scenarios, but also for integrated intelligent systems such as structural health monitoring, vibration source identification, and multi-axis state sensing. Furthermore, the entire device features a compact structure and flexible packaging, making it suitable for deployment in work environments with limited space, lack of continuous power supply, or requiring wireless self-drive, enabling self-harvesting, conversion, and utilization of vibration energy in micro-power scenarios. For example, it can be integrated into bridge gaps, inside equipment housings, human joint brackets, or smart watchbands to achieve real-time energy harvesting and response control to environmental vibrations. The device can also be combined with a wireless transmission module (such as BLE, LoRa) or an edge computing unit to achieve completely self-powered operation of data collection and wireless transmission, supporting the application of micro-energy systems in industrial Internet of Things, adaptive sensor networks and wearable electronic platforms.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A shear piezoelectric energy harvesting device with a bifurcated structure, comprising a vibration beam, a force transmission arm, a support plate, a shear-type piezoelectric unit, and a base. The device as a whole is bilaterally symmetrical with the middle of the vibration beam as the axis of symmetry. The vibration beam is laterally arranged at the upper part of the center of the device, and its two ends are respectively connected to the force transmission arm. The other end of the force transmission arm is connected to the corresponding upper surface of the support plate. The support plate is arranged on the upper surface of the shear-type piezoelectric unit, and the shear-type piezoelectric unit is arranged on the upper surface of the base. It is characterized in that: The force transmission arm includes a main transmission section and a forked structure, one end of the main transmission section is connected to the vibration beam, and the other end of the main transmission section is connected to the forked structure, and the forked structure includes multiple branch sections, one end of the multiple branch sections converges and is connected to the end of the main transmission section, and the other ends of the multiple branch sections are respectively connected to different positions on the support plate.

2. The shear piezoelectric energy harvesting device according to claim 1, characterized in that: The number of the branch segments is 2-6.

3. The shear piezoelectric energy harvesting device according to claim 2, characterized in that: The bifurcated structure includes a first branch segment and a second branch segment.

4. The shear piezoelectric energy harvesting device according to claim 3, characterized in that: A flexible connection portion is provided between the main transmission section and the bifurcated structure.

5. The shear piezoelectric energy harvesting device according to claim 4, characterized in that: The angle between any two adjacent branch segments among the plurality of branch segments is 10°-30°.

6. The shear piezoelectric energy harvesting device according to claim 5, characterized in that: The cross-sectional size of the main transmission section is smaller than the cross-sectional size of the bifurcated structure.

7. The shear piezoelectric energy harvesting device according to claim 6, characterized in that: The main transmission section and the bifurcated structure are made of materials with different elastic moduli.

8. The shear piezoelectric energy harvesting device according to claim 7, characterized in that: The main transmission section is made of a material with a high elastic modulus, and the bifurcated structure is made of a material with a low elastic modulus.

9. The shear piezoelectric energy harvesting device according to claim 8, characterized in that: The two bases are respectively arranged on the outer sides of both ends of the vibration beam.

10. The shear piezoelectric energy harvesting device according to claim 9, characterized in that: A mass block is provided on the vibration beam.

Images