Compound pendulum type piezoelectric energy recovery device

Abstract

The utility model discloses a compound pendulum type piezoelectric energy recovery device which is compact, practical, higher in environmental adaptability and better in broadband response capability. The single-degree-of-freedom forced vibration device comprises a shell, a base is arranged in the shell, a first piezoelectric plate unit is obliquely installed on the base, a first mass swing block is fixed to the upper end of the first piezoelectric plate unit, when the shell is shaken and vibrated, the first mass swing block shifts, the first piezoelectric plate unit is equivalent to a spring element, and therefore a single-degree-of-freedom forced vibration system is formed; the upper end of the first piezoelectric plate unit is fixed to the lower end of one side of the first mass swing block, the lower end of the other side of the first mass swing block is vertically provided with a second piezoelectric plate unit, the lower end of the second piezoelectric plate unit is fixedly provided with a second mass swing block, the second mass swing block is suspended in the air in the initial state and is perpendicular to the base, and the second mass swing block serves as a second free swing block. Therefore, the compound pendulum type piezoelectric energy recovery device forms a two-degree-of-freedom compound pendulum system. The energy recovery device is applied to the technical field of energy recovery.

Description

Technical Field

[0001] The utility model relates to an energy recovery device, in particular to a compound pendulum type piezoelectric energy recovery device. Background Art

[0002] In recent years, with the growing demand for wireless sensor networks in areas such as environmental monitoring, home healthcare, smart homes, and urban smart transportation, how to provide continuous and stable power to these sensors has become a major challenge restricting their development. Although traditional chemical batteries are widely used as power sources, they have many problems, such as limited life, low energy density, serious environmental pollution, and high maintenance costs, which limit the application scope of wireless sensor networks. Vibration energy has become the focus of researchers due to its abundance in nature and man-made environments, and its lack of influence from geographical location and climate change. Developing technologies that can capture environmental vibration energy and convert it into electrical energy can not only solve the limitations of traditional power sources, but also promote the application of wireless sensor networks. To this end, a variety of designs have been developed, including vibration energy collection devices with nonlinear structures such as L-type, disc-type, and magnetic adjustment type, aiming to achieve wide-band resonance and efficient energy conversion; for example, the existing patent application publication number CN113507234A is a nonlinear multi-directional piezoelectric energy recovery device and energy recovery method, which uses a nonlinear method of driving the piezoelectric sheet with a magnet to generate electricity, but it needs to drive the bracket up and down through a vibration table to make the special-shaped cantilever beam start to swing, and the left bottom beam will deform during the swing, forcing the piezoelectric sheet 2 to deform and generate electricity. At present, the use of ceramic piezoelectric sheets for vibration power generation is a well-known research point in the field and is also a research hotspot at this stage. This patent also uses the vibration of ceramic piezoelectric sheets to generate electricity, but it needs to use a vibration table, and the vibration table itself needs to be driven by electricity, and the swing amplitude and frequency are limited and not very convenient, so the electricity generated is also limited.

[0003] One of the main limitations of current technology in the field of vibration energy recovery is its limitation on frequency response. Many existing devices and methods are designed to be optimized for a specific or narrow frequency range, which means that they can only effectively recover vibration energy at these frequencies. However, vibration sources in actual application environments often have a wide frequency range, including random vibrations and multi-frequency vibrations, and the energy of these vibration sources is not fully utilized. Therefore, this limitation significantly reduces the applicability and efficiency of energy recovery systems in variable application environments. To address this problem, the present invention aims to broaden the frequency response range of energy recovery systems by utilizing the nonlinear characteristics of compound pendulum systems. Utility Model Content

[0004] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and provide a compact and practical compound pendulum piezoelectric energy recovery device with higher environmental adaptability and better broadband response capability.

[0005] The technical solution adopted by the utility model is: the utility model includes a shell, a base is arranged in the shell, a piezoelectric unit is obliquely installed on the base, a mass swing block is fixed to the upper end of the piezoelectric unit, when the shell is shaken, the mass swing block is offset, and the piezoelectric unit is equivalent to a spring element, thereby forming a single-degree-of-freedom forced vibration system, and then realizing the deformation of the piezoelectric unit to generate electrical energy.

[0006] Furthermore, the upper end of the piezoelectric sheet unit 1 is fixed to the lower end of one side of the mass swing block 1, and the piezoelectric sheet unit 2 is vertically installed on the lower end of the other side of the mass swing block 1. The lower end of the piezoelectric sheet unit 2 is fixed with a mass swing block 2. The initial state of the mass swing block 2 is suspended in the air and perpendicular to the base. The mass swing block 2 serves as a second free pendulum block, so that the compound pendulum type piezoelectric energy recovery device forms a two-degree-of-freedom compound pendulum system, and the internal space of the outer shell is larger than the space required for the compound pendulum system to swing.

[0007] Furthermore, a fixing block is provided on the base, and the piezoelectric sheet unit 1 is obliquely installed on the fixing block, and the oblique installation angle between the fixing block and the piezoelectric sheet unit 1 is 5°.

[0008] Furthermore, the mass swing block 1 includes a first rectangular block and a second rectangular block that are integrally formed, the length of the first rectangular block is greater than the length of the second rectangular block, and the width of the mass swing block 1 is equal to the width of the second rectangular block, the second rectangular block is located at the lower end of one side of the first rectangular block, the upper end of the piezoelectric sheet unit 1 is embedded in the lower end of the second rectangular block, the upper end of the piezoelectric sheet unit 2 is embedded in the lower end of the other side of the first rectangular block, and the lower end of the piezoelectric sheet unit 2 is embedded in the upper end of the mass swing block 2.

[0009] Furthermore, the piezoelectric sheet unit 1 and the piezoelectric sheet unit 2 both use PZT-5H ceramic piezoelectric sheets.

[0010] Furthermore, the shell is provided with an energy storage cavity at the lower end of the base, an energy storage battery is installed in the energy storage cavity, the PZT-5H ceramic piezoelectric sheet includes a copper plate and a piezoelectric ceramic sheet attached to the surface of the copper plate, the base is provided with an opening, and the lower ends of the copper plate and the piezoelectric ceramic sheet are provided with wires, and the wires pass through the opening to be connected to the energy storage battery.

[0011] Furthermore, the simplified motion equation of the compound pendulum motion of the compound pendulum system can be described by the following formula:

[0012]

[0013] Where l1 and l2 are the lengths of the piezoelectric unit 1 and the piezoelectric unit 2, m1 and m2 are the equivalent masses of the mass swing block 1 and the mass swing block 2, θ1 and θ2 are the relative swing angles of the mass swing block 1 and the mass swing block 2, and and represents the angular velocity, and represents angular acceleration.

[0014] Furthermore, the shell is made of a lightweight material and has a cylindrical shape.

[0015] The beneficial effects of the utility model are as follows:

[0016] 1. Wide-frequency response capability: The utility model effectively expands the frequency response range of the energy harvesting device by constructing a two-degree-of-freedom compound pendulum system; compared with common single-band designs (such as L-type, disc-type, and magnetically adjustable structures), this design can capture vibration energy in a wider frequency range, thereby maintaining efficient energy conversion performance under changing environmental conditions.

[0017] 2. Environmental adaptability: Due to the nonlinear characteristics and multi-degree-of-freedom system in the design of the utility model, it can respond to vibrations of various frequencies, which enhances the adaptability of the device under different environmental conditions. Whether it is random vibration in nature or mechanical vibration in an artificial environment, this solution can effectively capture and convert it into electrical energy, thereby reducing dependence on specific vibration sources.

[0018] 3. Compact and practical design: Compared with other energy harvesting devices, this utility model provides a more compact and practical solution. This compact design makes it easier to integrate into various devices, improves the energy self-sufficiency of the device, and also reduces the size and weight burden of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the utility model;

[0020] Figure 2 It is a cross-sectional view of the utility model;

[0021] Figure 3 It is a schematic diagram of the internal structure of the utility model;

[0022] Figure 4 It is a simulation stress situation diagram of the utility model;

[0023] Figure 5This is a diagram of the simulated total voltage output of the utility model. DETAILED DESCRIPTION

[0024] like Figures 1 to 3 As shown, in this embodiment, the utility model includes a shell 1, a base 2 is arranged in the shell 1, a piezoelectric unit 3 is obliquely installed on the base 2, and a mass swing block 4 is fixed to the upper end of the piezoelectric unit 3. When the shell 1 is shaken, the mass swing block 4 is offset, and the piezoelectric unit 3 is equivalent to a spring element, thereby forming a single-degree-of-freedom forced vibration system, thereby realizing the deformation of the piezoelectric unit 3 to generate electrical energy; the upper end of the piezoelectric unit 3 is fixed to the lower end of one side of the mass swing block 4, In order to make the device structure more compact, a piezoelectric sheet unit 2 5 is further vertically installed on the lower end of the other side of the mass swing block 4, and a mass swing block 2 6 is fixed to the lower end of the piezoelectric sheet unit 2 5. The mass swing block 2 6 is initially suspended in the air and perpendicular to the base 2, and the mass swing block 1 4 and the mass swing block 2 6 are in the same direction. The mass swing block 2 6 serves as a second free pendulum block, so that the compound pendulum type piezoelectric energy recovery device forms a two-degree-of-freedom compound pendulum system, and the internal space of the housing 1 is larger than the space required for the compound pendulum of the compound pendulum system.

[0025] In this embodiment, a fixing block 21 is provided on the base 2, and the piezoelectric unit 3 is obliquely mounted on the fixing block 21, and the oblique mounting angle between the fixing block 21 and the piezoelectric unit 3 is 5°.

[0026] In this embodiment, the mass swing block 4 includes an integrally formed first rectangular block 41 and a second rectangular block 42, the length of the first rectangular block 41 is greater than the length of the second rectangular block 42, and the width of the mass swing block 4 is equal to the width of the second rectangular block 42, the second rectangular block 42 is located at the lower end of one side of the first rectangular block 41, the upper end of the piezoelectric sheet unit 1 3 is embedded in the lower end of the second rectangular block 42, the upper end of the piezoelectric sheet unit 2 5 is embedded in the lower end of the other side of the first rectangular block 41, and the lower end of the piezoelectric sheet unit 2 5 is embedded in the upper end of the mass swing block 2 6.

[0027] In this embodiment, the piezoelectric sheet unit 1 3 and the piezoelectric sheet unit 2 5 both adopt PZT-5H ceramic piezoelectric sheets.

[0028] In this embodiment, the shell 1 is provided with an energy storage cavity 7 at the lower end of the base 2, and an energy storage battery is installed in the energy storage cavity 7. The PZT-5H ceramic piezoelectric sheet includes a copper plate 51 and a piezoelectric ceramic sheet 52 attached to the surface of the copper plate 51. The base 2 is provided with an opening. The lower ends of the copper plate 51 and the piezoelectric ceramic sheet 52 are provided with wires, and the wires pass through the opening to be connected to the energy storage battery. A USB interface electrically connected to the energy storage battery may be provided outside the shell. The working principle of the ceramic piezoelectric sheet is adopted: when an external force acts on the surface of the ceramic material, it will cause its lattice structure to change, so that its charge distribution will change, and then an electric field will be formed. Because the piezoelectric ceramic sheet will undergo a very small deformation under the action of external force, it can convert mechanical vibration into an electrical signal.

[0029] In this embodiment, the shell 1 is made of lightweight material, and the shape of the shell 1 is a cylinder. The cylinder may be provided with a grip groove adapted to fingers, which further facilitates people to hold the cylinder when using it, and then shake the cylinder left and right to generate electricity.

[0030] In this embodiment, the simplified motion equation of the compound pendulum motion of the compound pendulum system can be described by the following formula:

[0031]

[0032] Where l1 and l2 are the lengths of the piezoelectric unit 1 3 and the lengths of the piezoelectric unit 2 5, m1 and m2 are the equivalent masses of the mass swing block 1 4 and the mass swing block 2 6, θ1 and θ2 are the relative swing angles of the mass swing block 1 4 and the mass swing block 2 6, and and represents the angular velocity, and represents angular acceleration.

[0033] In this embodiment, in order to further discuss the power generation of the structural device for piezoelectric energy recovery, a finite element model of the device was established in COMSOL Multiphysics 6.0, and a transient study was performed using the solid mechanics module. Figure 4 As shown, according to the initial structural design, the base 2, the mass swing block 1 4 and the mass swing block 2 6 are considered to be resin materials for simulation, and their density is 1250kg / m3, the Young's modulus is 3.8*109Pa, and the Poisson's ratio is 0.35. For the ceramic piezoelectric sheet, a conventional PZT-5H ceramic piezoelectric sheet is considered, and its density is 7500kg / m3, the Young's modulus is 56*109Pa, and the Poisson's ratio is 0.35; the parameters of the copper plate 51 attached to the piezoelectric ceramic sheet 52 are density 8960kg / m3, Young's modulus is 110*109Pa, and Poisson's ratio is 0.35.

[0034] At the same time, a uniform random excitation of ±1 gravitational acceleration is applied to the x direction of the device base 2 to consider the energy generation. The total simulation time is set to 20 seconds, the calculation step is 5*10-4, the number of degrees of freedom solved is 108666, and the voltage output of the two piezoelectric unit 1 3 and the piezoelectric unit 2 5 is recorded, and the two voltages are superimposed to obtain the total voltage output of the device under random excitation. Figure 5 As shown, under uniform random excitation of only ±1 gravitational acceleration, the total voltage amplitude is stable at ±0.3V, and the energy production effect is good.

[0035] In this embodiment, the compound pendulum system can resonate in a wider frequency range due to its dynamic characteristics, thereby capturing and converting more environmental vibration energy. The present invention enables the system to adapt to and respond to vibrations of various frequencies, including those of random and non-periodic nature, through a carefully designed nonlinear dynamic structure, thereby greatly increasing the range and efficiency of energy recovery. In addition, by utilizing the nonlinear effect, the present invention can not only expand the effective frequency range, but also adapt to changes in the vibration environment to a certain extent, and achieve efficient conversion and collection of vibration energy without the need for external adjustment or frequency tracking mechanisms. This adaptability further improves the practicality and energy recovery efficiency of the system. Therefore, the compound pendulum system constituted by the utility model, its inherent nonlinear characteristics and the characteristics of a multi-degree-of-freedom dynamic system enable the device to respond to external vibrations in a wider frequency range, and the specific reasons include the following three points: 1. Nonlinear dynamic characteristics: The motion equation of the compound pendulum system usually has nonlinear characteristics, which means that the response of the system is not a simple linear function of the input vibration frequency; nonlinear systems can exhibit rich dynamic behaviors, such as frequency-multiplied vibrations, subharmonic generation, and chaos, which allow the system to resonate in a wider frequency range than linear systems. 2. Multiple degrees of freedom: A compound pendulum system contains multiple mass elements and connected elements, which work together to form a dynamic system with multiple degrees of freedom; each degree of freedom has its own natural frequency, and the overall response of the system is a combination of these natural frequencies; therefore, a compound pendulum system can resonate near the natural frequencies of its components, thereby covering a wider frequency range. 3. Energy transfer and coupling effects: In a compound pendulum system, the dynamic coupling between the various pendulum bodies causes energy to be transferred between different components. This exchange and distribution of energy enables the system to capture and convert energy at nonlinear resonant frequencies. The coupling effect increases the flexibility and adaptability of the system in responding to external vibrations.

[0036] The utility model is applied to the technical field of energy recovery.

[0037] Although the embodiments of the present invention are described with practical solutions, they do not constitute limitations on the meaning of the present invention. For those skilled in the art, it is obvious to modify the implementation scheme and combine it with other solutions based on this description.

Claims

1. A compound pendulum type piezoelectric energy recovery device, characterized in that: It comprises a shell (1), a base (2) is arranged inside the shell (1), a piezoelectric unit (3) is obliquely mounted on the base (2), a mass swing block (4) is fixed to the upper end of the piezoelectric unit (3), when the shell (1) is shaken, the mass swing block (4) is offset, and the piezoelectric unit (3) is equivalent to a spring element, thereby forming a single-degree-of-freedom forced vibration system, and further realizing the deformation of the piezoelectric unit (3) to generate electrical energy.

2. The compound pendulum type piezoelectric energy recovery device according to claim 1, characterized in that: The upper end of the piezoelectric sheet unit 1 (3) is fixed to the lower end of one side of the mass swing block 1 (4); the lower end of the other side of the mass swing block 1 (4) is vertically mounted with a piezoelectric sheet unit 2 (5); the lower end of the piezoelectric sheet unit 2 (5) is fixed with a mass swing block 2 (6); the initial state of the mass swing block 2 (6) is suspended in the air and perpendicular to the base (2); the mass swing block 2 (6) serves as a second free pendulum block, so that the compound pendulum type piezoelectric energy recovery device forms a two-degree-of-freedom compound pendulum system; the internal space of the housing (1) is larger than the space required for the compound pendulum system to swing.

3. The compound pendulum type piezoelectric energy recovery device according to claim 1, characterized in that: The base (2) is provided with a fixing block (21), the piezoelectric sheet unit 1 (3) is obliquely mounted on the fixing block (21), and the oblique mounting angle between the fixing block (21) and the piezoelectric sheet unit 1 (3) is 5°.

4. The compound pendulum type piezoelectric energy recovery device according to claim 2, characterized in that: The mass swing block 1 (4) comprises a first rectangular block (41) and a second rectangular block (42) which are integrally formed, the length of the first rectangular block (41) being greater than the length of the second rectangular block (42), and the width of the mass swing block 1 (4) being equal to the width of the second rectangular block (42), the second rectangular block (42) being located at the lower end of one side of the first rectangular block (41), the upper end of the piezoelectric sheet unit 1 (3) being embedded in the lower end of the second rectangular block (42), the upper end of the piezoelectric sheet unit 2 (5) being embedded in the lower end of the other side of the first rectangular block (41), and the lower end of the piezoelectric sheet unit 2 (5) being embedded in the upper end of the mass swing block 2 (6).

5. The compound pendulum type piezoelectric energy recovery device according to claim 2, characterized in that: The piezoelectric sheet unit 1 (3) and the piezoelectric sheet unit 2 (5) both use PZT-5H ceramic piezoelectric sheets.

6. The compound pendulum type piezoelectric energy recovery device according to claim 5, characterized in that: The housing (1) is provided with an energy storage cavity (7) at the lower end of the base (2), an energy storage battery is installed in the energy storage cavity (7), the PZT-5H ceramic piezoelectric sheet comprises a copper plate (51) and a piezoelectric ceramic sheet (52) attached to the surface of the copper plate (51), the base (2) is provided with an opening, and the lower ends of the copper plate (51) and the piezoelectric ceramic sheet (52) are both provided with wires, and the wires pass through the opening and are connected to the energy storage battery.

7. The compound pendulum type piezoelectric energy recovery device according to claim 2, characterized in that: The simplified equation of motion of the compound pendulum motion of the compound pendulum system can be described by the following formula: Where l1 and l2 are the lengths of the piezoelectric unit 1 (3) and the lengths of the piezoelectric unit 2 (5), m1 and m2 are the equivalent masses of the mass swing block 1 (4) and the mass swing block 2 (6), θ1 and θ2 are the relative swing angles of the mass swing block 1 (4) and the mass swing block 2 (6), respectively. and represents the angular velocity, and represents angular acceleration.

8. The compound pendulum type piezoelectric energy recovery device according to claim 1, characterized in that: The shell (1) is made of a lightweight material and has a cylindrical shape.

Images