An origami variable stiffness magnetic suspension-piezoelectric coupling energy harvesting device

Abstract

The present invention belongs to the intersection of vibration power generation and new energy. The purpose is to provide an origami variable stiffness magnetic suspension-piezoelectric coupling energy capture device to achieve the efficient energy capture function of mechanical power systems such as vehicle bodies operating in complex dynamic environments. The technical solution is: an origami variable stiffness magnetic suspension-piezoelectric coupling energy capture device, characterized in that: the device includes a mounting base that can be fixedly connected to an external power device, an electromagnetic induction coil located at the top or bottom of the mounting base, permanent magnets positioned at the top and bottom of the mounting base, respectively, and a magnetic suspension component that can slide linearly between the top and bottom of the mounting base.

Description

Technical Field

[0001] The present invention belongs to the intersection field of vibration power generation and new energy, and in particular relates to an origami variable stiffness magnetic suspension-piezoelectric coupling energy capture device. Background Art

[0002] With the widespread application of wireless sensors and microelectronic components in the era of the Internet of Things, their energy supply has become a key research direction. In addition to clean energy in the natural environment such as solar energy and tidal energy, vibration energy is also widely present in the environment. For this reason, the development of devices that use external environmental vibrations to capture energy can not only provide new means for clean energy generation, but also provide new ideas for the development of vibration health monitoring, which has important research value and broad application prospects. For example, the random response generated by vehicles during driving, the random and simple harmonic response of wind power equipment under wind load and motor excitation, can be converted into electrical energy and captured and utilized by installing efficient electromechanical coupling devices to power micro wireless sensor nodes, and vibration analysis can be performed through energy capture devices installed at key locations to complete the initial screening of fault diagnosis, which can realize the digital transformation and upgrading of complex equipment systems.

[0003] According to the above background analysis, it is urgent to propose a new type of vibration energy capture device that can adapt to different external environment excitations and achieve efficient energy capture characteristics. Most of the existing nonlinear piezoelectric cantilever beams use permanent magnets to achieve nonlinearity, and the vibration energy capture method is single; there are problems such as stiffness, potential barriers and equilibrium position that are difficult to adjust during steady-state conversion, and a large initial vibration excitation amplitude is required for energy capture operation; therefore, it is particularly important to design an origami variable stiffness magnetic suspension-piezoelectric coupling energy capture device that can achieve multi-mode high power density energy capture. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned background technology and provide an origami variable stiffness magnetic suspension-piezoelectric coupling energy capture device to achieve efficient energy capture function of mechanical power systems such as vehicle bodies operating in complex dynamic environments.

[0005] The technical solution provided by the present invention is:

[0006] An origami variable stiffness magnetic levitation-piezoelectric coupling energy capture device, characterized in that the device includes a mounting base that can be fixedly connected to an external power device, an electromagnetic induction coil located at the top or bottom of the mounting base, permanent magnets located at the top and bottom of the mounting base respectively, and a magnetic levitation component that can slide linearly between the top and bottom of the mounting base.

[0007] The mounting seat comprises a top connection cover, a guide shaft whose top end is fixed to the top connection cover and whose axis is coaxial with the center line of the top connection cover.

[0008] The magnetic levitation assembly includes a middle permanent magnet slidably positioned on a guide shaft, a plurality of cantilever beams radially arranged on the middle permanent magnet, a plurality of cantilever beams radially arranged at the bottom end of a mounting seat, and a plurality of origami structures; the plurality of cantilever beams at the bottom end of the mounting seat are the same in number as the plurality of cantilever beams on the middle permanent magnet and correspond one to one up and down, and the origami structure cells stacked in a linear array in the origami structure are installed in series one by one between each corresponding cantilever beam up and down.

[0009] The middle permanent magnet is wrapped and clamped by two fixed clamps from top to bottom; the multiple cantilever beams on the middle permanent magnet are evenly arranged in the circumference of the fixed clamps; the lower permanent magnet positioned at the bottom end of the mounting seat is wrapped and clamped by a fixed clamp and a bottom fixed clamp from top to bottom; the multiple cantilever beams at the bottom end of the mounting seat are evenly arranged in the circumference of the fixed clamp.

[0010] A plurality of bosses are radially arranged around the two fixing clamps, and a cantilever beam is clamped and fixed between each upper and lower corresponding boss of the two fixing clamps through fasteners.

[0011] The upper permanent magnet positioned at the top of the mounting seat is mounted in the coil frame through hole of the electromagnetic induction coil.

[0012] The magnetization direction of the upper permanent magnet is the same as that of the lower permanent magnet and opposite to that of the middle permanent magnet, thereby realizing the function of the middle magnetic suspension component to suspend and move on the guide shaft.

[0013] A flexible piezoelectric layer is fixed on one side surface of the cantilever beam; the width of the flexible piezoelectric layer is the same as that of the cantilever beam, and the length direction covers the side surface of the cantilever beam.

[0014] The cantilever beam at the bottom end of the mounting seat has its outer overhanging end fixed to the base bracket; the origami structure is connected in series between the base bracket and the overhanging end of the cantilever beam on the middle permanent magnet to increase the deformation of the cantilever beam.

[0015] In the linear array stacked origami structure, each origami structure cell is realized by Miura origami method to realize two states: convex and inset.

[0016] The beneficial effects of the present invention are:

[0017] 1. The energy harvester of the present invention utilizes a magnetic levitation structure and an origami structure to further amplify external excitation, and simultaneously applies electromagnetic induction and piezoelectric effect to vibration energy capture, thereby achieving multiple energy capture effects of vehicle body motion energy.

[0018] 2. The piezoelectric energy harvesting structure in the present invention is composed of multiple pairs of cantilever beam circular arrays, which can achieve high power density of the overall energy harvester.

[0019] 3. The present invention has a simple structure, high integration, safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a main structural schematic diagram of the present invention.

[0021] Figure 2 It is an overall schematic diagram of the present invention.

[0022] Figure 3 It is an exploded view of the electromagnetic induction coil structure of the present invention.

[0023] Figure 4 It is a schematic diagram of the magnetic suspension structure of the present invention.

[0024] Figure 5 It is a cross-sectional schematic diagram of the guide structure of the present invention.

[0025] Figure 6 It is a schematic diagram of the origami variable stiffness magnetic suspension piezoelectric coupling cantilever beam structure of the present invention.

[0026] Figure 7 It is a schematic diagram of the construction process of the origami structure cell of the present invention.

[0027] Figure 8 It is a schematic diagram of three motion states of the origami structure cell in the present invention.

[0028] Fig. 9 Schematic diagrams of two stable states of the origami structure of the present invention.

[0029] Reference numerals:

[0030] 1. Top connecting cover; 2. Coil frame; 3. Upper permanent magnet; 4. Coil; 5. Guide shaft; 6. Fixed clamp; 7. Bottom fixed clamp; 8. Middle permanent magnet; 9. Lower permanent magnet; 10. Base bracket; 11. Origami structure; 12. Cantilever beam; 13. Flexible piezoelectric layer; 14. Bolt; 15. Nut; 16. Set screw. DETAILED DESCRIPTION

[0031] The following is a further description with reference to the embodiments shown in the accompanying drawings.

[0032] In the origami variable stiffness magnetic suspension-piezoelectric coupling energy capture device shown in the accompanying drawings, the mounting seat includes a top connection cover and a guide shaft whose top end is fixed to the top connection cover, and the axis of the guide shaft is coaxial with the center line of the top connection cover; the electromagnetic induction coil is composed of a coil frame 2 (preferably a circular groove type nylon coil frame) and a coil 4 (the coil 4 is tightly and evenly wound on the coil frame 2); the coil frame 2 is fixedly mounted on the lower surface of the top connection cover (see Figure 1). Two permanent magnets (upper permanent magnet and lower permanent magnet) are positioned at the top and bottom of the mounting seat respectively; wherein, the upper permanent magnet 3 is fixedly mounted in the groove of the coil frame 2, ensuring that the top surface of the upper permanent magnet 3 contacts the lower surface of the top connection cover. The winding direction of the coil is determined according to the law of electromagnetic induction to maximize the induced current. The magnetic suspension assembly can slide linearly between the top and bottom of the mounting seat.

[0033] The magnetic suspension assembly includes three fixed clamps 6 with through holes in the center, a bottom fixed clamp 7, and a middle permanent magnet 8. The middle permanent magnet 8 is sleeved on the guide shaft through a sliding hole opened in the middle, and the upper and lower parts of the middle permanent magnet are wrapped and clamped by two fixed clamps 6 (the through hole in the middle of the fixed clamp is larger than the diameter of the guide shaft), and can slide freely along the guide shaft. The lower permanent magnet 9 is wrapped and clamped by a fixed clamp 6 and a bottom fixed clamp 7, and the bottom fixed clamp 7 is also fixedly connected to the bottom end of the guide shaft 5. The upper permanent magnet 3, the middle permanent magnet 8 and the lower permanent magnet 9 are preferably cylindrical permanent magnets. The upper permanent magnet 3 and the lower permanent magnet 9 have the same magnetization direction when arranged, and the upper permanent magnet 3 and the middle permanent magnet 8 should ensure that the magnetization direction is opposite when arranged, so as to ensure that the middle permanent magnet 8 can achieve a magnetic suspension effect along the guide shaft 5, and can vibrate along the axial direction of the guide shaft 5 within a certain range when subjected to external excitation.

[0034] like Figure 2 , 5 As shown in Figure 6, the magnetic suspension assembly also includes a plurality of cantilever beams radially arranged on the middle permanent magnet through two upper and lower fixed clamps, and a plurality of cantilever beams radially arranged on the bottom of the mounting seat through a fixed clamp and a bottom fixed clamp; the number of cantilever beams at the bottom of the mounting seat is the same as the number of cantilever beams on the middle permanent magnet and they correspond one to one. The outer circumference of the fixed clamp is evenly distributed with 6 bosses protruding in the outer diameter direction, and bolt countersunk holes are respectively provided on the table top; the two fixed clamps used to clamp the middle permanent magnet can clamp a cantilever beam between each of the upper and lower corresponding bosses and fix the cantilever beam by a fastener (bolt). A fixed clamp and a bottom fixed clamp used to clamp the lower permanent magnet can also clamp a cantilever beam between each of the upper and lower corresponding bosses and fix the cantilever beam by a fastener (bolt).

[0035] A flexible piezoelectric layer 13 is also bonded and fixed on the cantilever beam 12 to form a piezoelectric cantilever beam. As shown in the figure, the flexible piezoelectric layer is bonded to the upper surface (or lower surface) of the cantilever beam 12 using electrosilver glue; the cantilever beam material is selected from one of aluminum and copper, and the flexible piezoelectric layer is selected from one of PVDF, PZT and ZnO. The piezoelectric cantilever beam can be arranged in a 60° array (preferably six array groups) along the circumference of the fixed clamping plate 6 to increase the power density of the energy harvester.

[0036] The magnetic levitation assembly also includes a number of origami structures; in each origami structure, origami structure cells stacked in a linear array are installed in series between corresponding upper and lower cantilever beams. As can be seen from the figure: the cantilever beam located at the bottom of the mounting seat has its outer overhanging end fixed to the base bracket 10; the origami structure is connected in series between the base bracket (optionally a triangular columnar shape made of bent aluminum sheet) and the overhanging end of the cantilever beam on the middle permanent magnet; the base bracket 10 and the origami structure 11 are connected by glue, and the origami structure and the cantilever end of the cantilever beam on the middle permanent magnet are also connected by glue.

[0037] like Figure 7 and 8 As shown, the origami structural cell is composed of origami A1 and origami B1 (the origami paper is selected according to needs). The origami A1 (the origami is a rectangle with a length of 2a and a width of 2b; the middle part is a long crease D formed after folding, and the length is also 2a) and origami B1 (the origami is a rectangle with a length of 2a and a width of 2c; the middle part is a long crease E formed after folding, and the length is also 2a) are both folded using the Miura origami method, in which the solid folded line is the ridge line and the dotted folded line is the valley line; the short side c of the origami B1 should be smaller than the short side b of origami A1; α in origami A1 and β in origami B1 satisfy the relationship bcosα=ccosβ. Among them: origami A1 can be regarded as one state after folding (i.e., origami A2), and origami B1 has two states (i.e., origami B2 and origami B3). The long sides of origami A1 and origami B1 are equal and can be connected by gluing and other processes (the connection relationship is shown in Figure 7 As shown: the two long sides of origami A2 are glued to the two long sides of origami B2 / B3 in a one-to-one correspondence) to obtain an origami structural cell, which has two stable equilibrium positions (convex state C1 and embedded state C2); several ( Fig. 9 The origami structure is obtained by stacking the linear array of origami cells ( Fig. 9 As shown: the long folds D and E in two adjacent origami structure cells are glued together).

[0038] Working principle of the present invention:

[0039] The system is installed at the bottom of the mechanical power device, such as the bottom of the vehicle body, and the vertical vibration direction of the vehicle body is consistent with the axial direction of the guide shaft.

[0040] When the vehicle body is driven on an uneven and concave surface, the magnetic suspension structure is acted upon by inertial force, and the balance point of the middle permanent magnet 8 changes, prompting it to move toward one end of the guide shaft 5. After the repulsive force in the opposite direction of the movement of the permanent magnet 8 increases to a certain extent, it moves in the opposite direction along the axial direction toward the other end, and this cycle repeats. As a result, the permanent magnet 8 swings along its axis within a certain range, causing the magnetic flux in the coil 4 to change continuously, thereby generating an induced current in the coil 4 to achieve electromagnetic power generation. At the same time, the root of the piezoelectric cantilever beam structure installed at the middle permanent magnet 8 and the lower permanent magnet 9 continuously deviates from the stable equilibrium position, and the origami structure at the end of the piezoelectric cantilever beam will also form a deformation when subjected to an external force. The coupling and superposition of the two dynamic motions can form a large displacement, thereby achieving a large bending deformation of the piezoelectric cantilever beam and achieving an ideal vibration energy capture effect. Figure 8 The three-state structure diagram of the origami structure cell, where C0 is an unstable state, and the deformation cycle of the origami structure cell is: C1→C0→C2→C0→C1. Fig. 9 The figure shows a comparison of the two maximum deformation states of the origami structure (D1 and D2; the height difference between the two states is L2-L1). It can be seen that the origami structure has a large adjustable travel range. After coupling with the piezoelectric cantilever beam structure, it can greatly increase the deformation degree of the cantilever beam to achieve an ideal vibration energy capture effect.

[0041] In the present invention, the origami structure cell adopts the Miura origami method, and a two-dimensional plane paper is folded into a three-dimensional model. The multi-stable variable stiffness characteristics can be realized by the design of the creases, and the vibration energy harvesting structure can move between two or even multiple equilibrium positions. The origami structure is used at the end of a pair of cantilever beams instead of the permanent magnetic nonlinearity, which can realize the large deformation of the piezoelectric cantilever beam on the basis of lightweight structure, and greatly improve the working performance of the energy harvester. In addition, the combination of the piezoelectric cantilever beam and the magnetic suspension structure can not only realize the micro-vibration energy capture capability of the energy harvesting device, but also provide a hybrid electromagnetic-piezoelectric coupling vibration energy capture design method, and lay the foundation for the design of the local vibration sensor monitoring system in the mechanical system. In summary, the rational use of magnetic suspension characteristics and origami structure characteristics can not only make the vibration energy harvester meet the working requirements in a complex dynamic environment, but also coordinate the coupling characteristics between the two energy capture modes, and can also meet the health monitoring management of complex equipment systems. Provide renewable energy supply for micro and small low-power electronic devices, wireless sensor nodes, etc. in the fields of extraterrestrial probes, special military off-road equipment, wind power equipment, etc., to achieve real-time monitoring of health status and realize the interconnection of all things.

[0042] Finally, it should be noted that the above examples are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples, and many variations are possible. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. An origami variable stiffness magnetic suspension-piezoelectric coupling energy harvesting device, characterized in that: The device comprises: a mounting seat fixedly connected to an external power device, an electromagnetic induction coil located at the top or bottom of the mounting seat, permanent magnets located at the top and bottom of the mounting seat respectively, and a magnetic suspension assembly capable of linearly sliding between the top and bottom of the mounting seat; The mounting seat comprises a top connection cover (1), and a guide shaft (5) whose top end is fixed to the top connection cover and whose axis is coaxial with the center line of the top connection cover; The magnetic suspension assembly comprises a middle permanent magnet (8) slidably positioned on the guide shaft, a plurality of cantilever beams (12) radially arranged on the middle permanent magnet, a plurality of cantilever beams radially arranged at the bottom end of the mounting seat, and a plurality of origami structures (11); the plurality of cantilever beams at the bottom end of the mounting seat are the same in number as the plurality of cantilever beams on the middle permanent magnet and correspond one to one up and down, and the origami structure cells stacked in a linear array in the origami structure are serially mounted one to one between each of the corresponding cantilever beams up and down; A flexible piezoelectric layer (13) is fixed to one side surface of the cantilever beam; the flexible piezoelectric layer has the same width as the cantilever beam and covers the side surface of the cantilever beam in the length direction.

2. The origami variable stiffness magnetic suspension-piezoelectric coupling energy harvesting device according to claim 1, characterized in that: The middle permanent magnet is wrapped and clamped by two fixed clamping plates (6) from top to bottom; a plurality of cantilever beams on the middle permanent magnet are evenly arranged in the circumference of the fixed clamping plates; the bottom end of the mounting seat is wrapped and clamped by a fixed clamping plate and a bottom fixed clamping plate (7) from top to bottom; and a plurality of cantilever beams at the bottom end of the mounting seat are evenly arranged in the circumference of the fixed clamping plates.

3. The origami variable stiffness magnetic suspension-piezoelectric coupling energy harvesting device according to claim 2 is characterized in that: A plurality of bosses are radially arranged around the two fixing clamps, and a cantilever beam is clamped and fixed between each upper and lower corresponding boss of the two fixing clamps through fasteners.

4. The origami variable stiffness magnetic suspension-piezoelectric coupling energy harvesting device according to claim 3 is characterized by: The upper permanent magnet positioned at the top of the mounting seat is mounted in a through hole of the coil frame (2) of the electromagnetic induction coil.

5. The origami variable stiffness magnetic suspension-piezoelectric coupling energy harvesting device according to claim 4, characterized in that: The magnetization direction of the upper permanent magnet is the same as that of the lower permanent magnet and opposite to that of the middle permanent magnet, thereby realizing the function of the middle magnetic suspension component to suspend and move on the guide shaft.

6. The origami variable stiffness magnetic suspension-piezoelectric coupling energy harvesting device according to claim 5, characterized in that: The cantilever beam at the bottom end of the mounting seat has its outer overhanging end fixed to the base bracket; the origami structure is connected in series between the base bracket and the overhanging end of the cantilever beam on the middle permanent magnet to increase the deformation of the cantilever beam.

7. The origami variable stiffness magnetic suspension-piezoelectric coupling energy harvesting device according to claim 6, characterized in that: The origami structure cell is realized by Miura origami method to achieve two stable states: convex and inset.

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