Wave energy generation method and device based on nonlinear vibration

Abstract

The application belongs to the technical field of new energy power generation, and relates to a wave energy power generation method and device based on nonlinear vibration. A gravity pendulum is hinged to a sliding block and a suspension rod. A rack gear is arranged in the up-down sliding direction of the gravity pendulum to mesh with a gear transmission, so as to convert heave ocean energy into mechanical energy. An inner ring gear is arranged in the reciprocating swinging direction of the gravity pendulum to mesh with a gear transmission, so as to convert pitch ocean energy into mechanical energy. Then, the two-way mechanical energy torque is coupled through a planetary gear train and used for power generation. The application uses repulsion of a magnet and an inclined spring to construct a nonlinear restoring force, combines a one-way bearing to realize conversion of reciprocating motion into one-way rotation, and combines the rotation speeds of pitch and heave motion through a epicyclic gear train, so as to effectively broaden the frequency bandwidth of wave energy capture and significantly improve the utilization efficiency of wave energy with constantly changing frequency and amplitude.

Description

Technical Field

[0001] This invention belongs to the field of new energy power generation technology, specifically relating to a wave energy power generation method and device based on nonlinear vibration. Background Technology

[0002] Wave energy, as a type of mechanical energy within ocean energy, is one of the highest quality energy sources in the ocean. The motion of an object floating on the sea surface under the influence of waves can be decomposed into six forms: rolling, pitching, yaw, heaving, swaying, and undulating. Heaving, swaying, and undulating are reciprocating motions in a straight line, while pitching, rolling, and yaw are oscillating motions around a rotational axis. Research in wave energy power generation devices primarily focuses on the heaving and pitching motions.

[0003] Wave periods typically range from 0.5 to 25 seconds, with wave heights generally ranging from a few centimeters to 20 meters. If the force exerted by waves on floating objects is considered equivalent to an excitation force, then the wave period can be equated to the frequency of this excitation force, and the wave height to its amplitude. The amplitude and frequency of the excitation force exerted by waves on objects are variables with relatively large ranges. Wave energy generation devices operating in linear resonance mode cannot effectively capture wave energy with constantly changing frequencies and amplitudes, resulting in low power generation efficiency. In contrast, nonlinear vibration systems have a significantly wider operating bandwidth than linear vibration systems, giving wave energy generation devices based on nonlinear vibration modes a greater advantage in capturing wave energy with constantly changing frequencies and amplitudes.

[0004] However, existing wave energy generation devices include various types such as oscillating floats, pendulums, and rafts. These devices all utilize the principle of relative motion and employ hydraulic or mechanical transmission to convert wave energy into electrical energy. In the conversion process from wave energy to mechanical / hydraulic energy, these devices typically use rotating or sliding joints to achieve relative motion between components. Due to the relatively high corrosiveness of seawater, even with protective measures, existing wave energy generation devices are prone to oil leaks or seawater intrusion in their various moving parts after long-term immersion in seawater. This can lead to loss of function or malfunction of the moving parts, increasing the maintenance costs of the wave energy generation device.

[0005] Therefore, a wave energy generation device or method with better sealing, lower cost, and higher power generation efficiency is needed to solve the above-mentioned technical problems. Summary of the Invention

[0006] This invention provides the following technical solution: a wave energy generation method based on nonlinear vibration, comprising: a gravity pendulum, wherein the gravity pendulum is hinged to a slider and a suspension rod to achieve a composite motion of heave sliding and pitching; a rack and pinion gear transmission is provided in the vertical sliding direction of the gravity pendulum to convert heave ocean energy into mechanical energy, and an internal gear ring transmission is provided in the reciprocating oscillation direction of the gravity pendulum to convert pitching ocean energy into mechanical energy; then, the two mechanical energies are torque-coupled through a planetary gear system for power generation. A spring assembly is provided in the vertical sliding direction of the gravity pendulum to provide a nonlinear restoring force; a pair of repulsive magnets are provided in the reciprocating oscillation direction of the gravity pendulum to provide a nonlinear restoring force; the gravity pendulum, planetary gear system, and power generation device are sealed within a housing. By converting the combined heave and pitch motion of the gravity pendulum into mechanical energy through rack and pinion and internal gear ring gear respectively, and by using spring groups and magnetic repulsion to provide nonlinear restoring force, the operating bandwidth of the system is widened, which can more efficiently adapt to changes in wave frequency and amplitude. At the same time, the sealed shell design effectively avoids seawater corrosion of internal moving parts, reduces maintenance costs, and improves the long-term stability and power generation efficiency of the device in the marine environment.

[0007] Preferably, the magnetic repulsion force of the magnet is:

[0008] (1)

[0009] in, Indicates magnetic repulsion. Represents the permeability of free space. , These represent the magnetization intensities of the two magnets, respectively. , Let represent the volumes of the two magnets respectively. Indicates the distance between the centers of the two magnets. This indicates the distance from the magnet to the center of rotation of the internal gear ring. This represents the distance between the stable and unstable equilibrium positions of the magnet. express A higher-order infinitesimal raised to the power of 5.

[0010] The restoring force of the spring is:

[0011] (3)

[0012] in, This represents the vertical component of the force on the spring. Indicates the spring stiffness. This indicates the distance from the top of the spring to the pendulum rod of the gravity pendulum. Indicates the tilt angle of the spring. Indicates the original length of the spring. This represents the displacement of the gravity pendulum along the length of the pendulum rod. By precisely quantifying the mathematical relationship between magnetic repulsion and spring restoring force, a theoretical basis is provided for the design of nonlinear restoring force, ensuring that the system can stably output nonlinear characteristics under different wave excitations, and further optimizing energy conversion efficiency. Specifically, the magnetic repulsion formula (1) considers key parameters such as the magnetization intensity, volume, center distance, and rotation center distance of the magnet, and the magnet parameters can be adjusted according to the actual working conditions to obtain the required nonlinear force characteristics; the spring restoring force formula (3) achieves precise control of the nonlinear restoring force in the swaying direction through variables such as spring stiffness, installation position, and tilt angle, so that the gravity pendulum can broaden the resonance frequency band through nonlinear restoring force in both swaying and pitching motions, thereby more fully capturing wave energy of different frequencies and amplitudes.

[0013] This invention also discloses a wave energy generation device based on nonlinear vibration. This wave energy generation device employs the aforementioned wave energy generation method and includes: a housing, which is a sealed cavity. Inside the housing are a pitch energy harvesting mechanism, a heave energy harvesting mechanism, an energy synthesis mechanism, and a generator. The pitch energy harvesting mechanism converts the pitch of the gravity pendulum into torque on a rotating shaft via an internal gear ring. The heave energy harvesting mechanism converts the heave of the gravity pendulum into torque on another rotating shaft via a rack and pinion gear. Each rotating shaft is equipped with a one-way bearing to ensure unidirectional torque transmission. The energy synthesis mechanism combines the torques from the two rotating shafts through a planetary gear system and then transmits them to the generator for power generation. The pitching and heaving energy harvesting mechanisms capture the pitching and heaving motion energy of the gravity pendulum, respectively. The one-way bearings prevent energy loss when the direction of motion changes, ensuring that both mechanical energies can be transferred unidirectionally and efficiently to the energy synthesis mechanism. The planetary gear train, as the core of energy synthesis, can coordinate and couple the two mechanical energies with different speeds and torques to achieve optimized energy integration and drive the generator to generate electricity stably. The sealed shell provides a protective space for the internal mechanisms to isolate them from seawater corrosion, enabling the device to maintain long-term reliable operation in complex marine environments.

[0014] Preferably, the pitch energy harvesting mechanism includes: a first shaft, a first gear ring, a sixth gear, and a connecting frame. The first shaft is rotatably connected to the inner cavity of the housing. The first gear ring and the sixth gear are coaxially connected to the first shaft and rotate synchronously. The inner teeth of the first gear ring mesh with the first gear, and the sixth gear meshes with the second gear. The second gear and the first gear are coaxially fitted onto the outer cylindrical surface of the third shaft through one-way bearings. The one-way bearings of the first gear and the one-way bearings of the second gear have the same driving direction. The third shaft is rotatably connected to the inner cavity of the housing and is parallel to the first shaft. The third shaft transmits torque to the energy synthesis mechanism.

[0015] The connecting frame is inverted T-shaped. The first gear ring is fixed to the vertical part of the connecting frame, and the horizontal part of the connecting frame is elastically connected to the weight at both ends via linear springs. The horizontal part of the connecting frame is parallel to the end face of the first gear ring. The inverted T-shaped connecting frame elastically connects the first gear ring and the weight, allowing the pitching motion of the weight under the action of waves to drive the first gear ring to rotate synchronously through the connecting frame, thereby driving the first gear and the sixth gear to rotate. The linear springs at both ends of the horizontal part provide elastic restoring force during the swing of the weight, which works in conjunction with the magnetic repulsion to form a nonlinear restoring force in the pitching direction, effectively widening the operating bandwidth of the pitching energy harvesting mechanism and improving the efficiency of harvesting pitching energy from waves of different frequencies. At the same time, the structural design of the connecting frame ensures the stable transmission of the weight's motion and the gear ring's rotation, avoiding jamming or energy loss during the motion process, and providing structural support for the efficient conversion of pitching mechanical energy.

[0016] More preferably, a first magnet is fixed to the outer circumference of the first gear ring, and a second magnet is fixed to the inner cavity of the housing. When the weight is in an unstable equilibrium position in the vertical direction, the first and second magnets are opposite each other with the same poles. The linear spring is in a freely extended state when in the unstable equilibrium position. When the weight deviates from the unstable equilibrium position and oscillates, the distance between the first and second magnets changes. The magnetic repulsion force generated by the opposite poles changes nonlinearly with the distance, which, together with the elastic restoring force generated by the linear spring during the oscillation, constitutes a composite nonlinear restoring force in the oscillation direction. This composite nonlinear restoring force enables the oscillation energy harvesting mechanism to produce a resonance effect over a wider frequency range. When the wave excitation frequency is close to the system's natural frequency, the oscillation amplitude of the weight increases significantly, thereby increasing the rotational speed of the first gear ring and transmitting more oscillation mechanical energy to the third shaft through gear transmission. Meanwhile, the unstable equilibrium position setting allows the weight to be triggered to swing when disturbed by small waves, which improves the device's response sensitivity to weak wave signals and ensures that the energy conversion process can be effectively started even when the wave energy is weak. This further enhances the adaptability of the pitch energy harvesting mechanism to waves of different intensities and the energy harvesting efficiency.

[0017] More preferably, a torsion spring is coaxially sleeved on the first shaft, with one end of the torsion spring fixed to the inner cavity of the housing and the other end fixed to the first shaft. When the first gear ring rotates with the connecting frame, the torsion spring will undergo elastic deformation due to the rotation of the first shaft, thereby providing a torsional restoring force opposite to the direction of rotation. This torsional restoring force can assist the pitch energy harvesting mechanism in quickly resetting after completing one swing, reducing the decay time of the weight's swing and ensuring that the mechanism can respond to subsequent wave excitations more promptly. At the same time, the torsion spring can adjust the natural frequency of the pitch energy harvesting mechanism. By changing the stiffness coefficient of the torsion spring, the natural frequency of the system can be better matched to the common wave frequency range, further widening the operating bandwidth of the device and improving the ability to capture pitch energy of waves of different frequencies. In addition, when the wave excitation is weak or the wave frequency is unstable, the elastic potential energy of the torsion spring can also compensate for energy loss to a certain extent, maintaining the continuous and stable swing of the mechanism, thereby ensuring the continuity and stability of the mechanical energy transmitted to the third shaft in the pitch direction.

[0018] More preferably, the connecting frame is provided with a sliding pair along the vertical direction. The sliding pair includes a slider and a vertical slide rail. A vertical connecting rod is connected to the upper part of the weight, and the connecting rod is hinged to the slider. This allows the weight to slide freely in the vertical direction while swaying with the connecting frame, thereby decoupling the swaying motion and the pitching motion of the weight. When waves act on the device, the swaying motion of the weight in the vertical direction drives the slider to slide up and down along the slide rail through the connecting rod, while the pitching motion is transmitted to the first gear ring through the connecting frame. This allows the swaying and pitching motions to occur independently, avoiding motion interference. This structural design ensures that the swaying energy harvesting mechanism and the pitching energy harvesting mechanism can independently capture the corresponding wave energy without affecting each other, thereby improving the independence and efficiency of energy conversion between the two motion forms. At the same time, the sliding pair provides stable guidance for the swaying motion of the weight, reduces friction and energy loss during the motion process, ensures the smooth transmission of mechanical energy in the swaying direction, and further improves the overall wave energy capture effect of the entire device.

[0019] Preferably, the heave energy harvesting mechanism includes: a first rack and a second rack. The first rack meshes with a fourth gear, and the second rack meshes with a third gear. The third and fourth gears are coaxially mounted on the outer cylindrical surface of the fourth shaft via one-way bearings. The fourth shaft is rotatably connected to the inner cavity of the housing. The one-way bearings of the third and fourth gears drive in opposite directions, and the meshing surfaces of the first and second racks are parallel to each other. A vertical connecting rod is connected to the lower end of the first and second racks, and a weight is connected to the lower end of the connecting rod. The fourth shaft transmits torque to the energy synthesis mechanism. Through the meshing of the first and second racks with the third and fourth gears respectively, the vertical reciprocating motion of the weight during the heave motion is converted into the one-way rotational motion of the fourth shaft. When the weight moves upward, the first rack drives the fourth gear to rotate. At this time, the one-way bearing of the fourth gear is in a driving state, transmitting torque to the fourth shaft. Simultaneously, the second rack moves upward with the weight, driving the third gear to rotate in the opposite direction. Its one-way bearing is in an idle state and does not transmit torque. As the weight moves downwards, the second rack drives the third gear to rotate, and the one-way bearing of the third gear enters the driving state, transmitting torque to the fourth shaft. Meanwhile, the first rack moves downwards with the weight, driving the fourth gear to rotate in the opposite direction, while its one-way bearing idles. This design of a double-sided rack and gear with a one-way bearing ensures that the reciprocating motion of the weight in the helical direction is converted into continuous unidirectional rotation of the fourth shaft, avoiding energy loss due to changes in the direction of motion and significantly improving the efficiency of helical mechanical energy collection. Furthermore, the parallel meshing surfaces ensure the stability of the rack's motion, and the rigid connection between the connecting rod and the weight ensures efficient energy transfer during helical motion, providing a stable power input for the torque coupling of the subsequent energy synthesis mechanism.

[0020] Preferably, the energy synthesis mechanism includes: a planetary gear, a second gear ring, a connecting rod, and a small sun gear. The second gear ring, the connecting rod, and the small sun gear are on the same rotation axis. The second gear ring, the connecting rod, and the small sun gear are rotatably connected to the inner cavity of the housing. The inner ring of the second gear ring meshes with the small sun gear simultaneously with the planetary gear. The planetary gear is rotatably connected to the planetary gear shaft of the connecting rod.

[0021] The planetary gears and the small sun gear are respectively torque-connected to the torque output shafts of the pitch and heave energy harvesting mechanisms, while the connecting rod or the second gear ring is torque-connected to the generator. This efficiently integrates and coordinates the two different mechanical energy sources transmitted by the pitch and heave energy harvesting mechanisms for output. Specifically, when the pitch energy harvesting mechanism transmits torque to the small sun gear via the third shaft, and the heave energy harvesting mechanism transmits torque to the planetary gears via the fourth shaft, the planetary gears, constrained by the internal teeth of the second gear ring, rotate on their own axis and revolve around the small sun gear with the connecting rod. This motion characteristic of the planetary gear system allows the two input torques to be dynamically distributed and coupled according to their respective speeds and torque magnitudes. When one input torque is larger, the planetary gear system can drive the other to work collaboratively, avoiding the impact of fluctuations in a single energy source on the overall output. The connecting rod, as the final torque output end (or, depending on the design, the second gear ring output), can transmit the coupled stable torque to the generator, ensuring that the generator maintains a relatively stable speed and power output under different wave excitation conditions, thereby achieving efficient and continuous conversion of wave energy into electrical energy. Meanwhile, the compact structure of the planetary gear train also saves installation space within the housing, making miniaturization of the device possible.

[0022] Preferably, a speed increaser is connected in series between the energy synthesis mechanism and the generator. This speed increase boosts the torque output of the energy synthesis mechanism to the rated operating speed range of the generator, matching the generator's high-efficiency power generation requirements. Due to the low frequency and small amplitude characteristics of wave energy, the mechanical energy captured by the pitch and heave energy harvesting mechanisms, after coupling through planetary gear systems, often results in a low output speed, making it difficult to directly drive the generator to achieve optimal power generation efficiency. The speed increaser, through gear transmission or other speed-changing structures, converts low-speed, high-torque mechanical energy into high-speed, low-torque power output, enabling the generator to operate stably at its designed rated speed, thereby significantly improving energy conversion efficiency. Furthermore, the speed increaser also acts as a buffer and matcher. When wave excitation causes fluctuations in input torque, the speed increaser can absorb these fluctuations to a certain extent, reducing the impact on the generator, protecting it from instantaneous overload damage, and extending the equipment's service life. Simultaneously, by rationally selecting the speed increaser's transmission ratio, it can be adaptively adjusted according to the wave characteristics of different sea areas, further optimizing the generator's operating state and ensuring that the entire power generation system maintains efficient and stable power output in complex and ever-changing marine environments.

[0023] The beneficial effects of this invention are:

[0024] 1. The present invention adopts a fully enclosed structure, which effectively avoids the corrosion of the internal power generation device by seawater and effectively reduces maintenance costs.

[0025] 2. This invention adopts an integrated gravity pendulum structure with variable suspension length, which can directly realize two movements: the reciprocating swing of the weight around the rotation center and the up-and-down movement along the length of the connecting rod. At the same time, it realizes the energy capture of heave and pitch, directly simplifying the difficulty of designing heave energy capture devices and pitch energy capture devices separately.

[0026] 3. This invention employs a two-degree-of-freedom planetary gear train to achieve the direct synthesis of heave-captured energy and pitch-captured energy, thereby improving the wave energy capture power.

[0027] 4. This invention adds nonlinear restoring forces in the reciprocating swing direction of the gravity pendulum and along the length of the connecting rod, respectively, upgrading the linearly vibrating gravity pendulum to a nonlinearly vibrating gravity pendulum, thus broadening the working bandwidth of pitch energy harvesting and heave energy harvesting, and improving the energy harvesting efficiency of wave energy in the pitch and heave directions. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the magnetic repulsion between two magnets in a wave energy generation method and device based on nonlinear vibration according to the present invention.

[0029] Figure 2 This is a schematic diagram of the nonlinear potential energy function of the present invention;

[0030] Figure 3 This is a comparison diagram of the nonlinear frequency response function and the linear frequency response function of the present invention;

[0031] Figure 4 This is a diagram showing the arrangement of the tilting springs of the present invention;

[0032] Figure 5 This is a schematic diagram of the internal structure of the present invention;

[0033] Figure 6 This is a schematic diagram illustrating the synthesis of pitching and heaving motions according to the present invention;

[0034] Figure 7 This is a schematic diagram of a three-dimensional model of the present invention;

[0035] Figure 8 This is a schematic diagram of the internal transmission structure of the three-dimensional model of the present invention.

[0036] The components are as follows: 1. First shaft; 2. Sliding pair; 3. First gear ring; 4. One-way bearing; 5. First gear; 6. Second gear; 7. Third gear; 8. Fourth gear; 9. First rack; 10. Third shaft; 11. Planetary gear; 12. Second gear ring; 13. Connecting rod; 14. Coupling; 15. Speed ​​increaser; 16. Generator; 17. Second rack; 18. Fifth gear; 19. Small sun gear; 20. Second magnet; 21. First magnet; 22. First rack limiter. 23. Connecting frame; 24. Shell; 25. Linear spring; 26. Counterweight; 27. Weight; 28. Connecting rod; 29. ​​Wave; 30. Second rack limiter; 31. Sixth gear; 32. First support frame; 33. Rack connecting plate; 34. Torsion spring; 35. Second shaft; 36. Second support frame; 37. Third support frame; 38. Fourth support frame; 39. Fifth support frame; 40. Sixth support frame; 41. Anchor chain; 42. Anchor body; 43. Seabed. Detailed Implementation

[0037] The related technologies of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] The wave energy generation device based on nonlinear vibration in this embodiment consists of two main parts: an internal power generation device and a shell 24, which is a sealed shell. The internal power generation device is fixed to the central space of the shell 24 by a first support frame 32, a second support frame 36, a third support frame 37, a fourth support frame 38, a fifth support frame 39, and a sixth support frame 40. The bottom of the shell 24 is connected to an anchor chain 41, and the anchor body 42 fixes the anchor chain 41 to the seabed 43.

[0039] The internal power generation device mainly consists of a pitch / heave integrated energy harvesting mechanism, an energy synthesis mechanism, a speed increaser 15, and a generator 16. The pitch / heave integrated energy harvesting device comprises a weight 27, a connecting rod 28, a linear spring 25, a connecting frame 23 with a sliding pair 2, a torsion spring 34, a first gear ring 3, a first magnet 21, a second magnet 20, a one-way bearing 4, a first gear 5, a second gear 6, a third shaft 10, a fifth gear 18, a sixth gear 31, a first shaft 1, a third gear 7, a fourth gear 8, a first rack 9, a second rack 17, a first rack limiter 22, a second rack limiter 30, and a fourth shaft 35. The function of the torsion spring 34 is to pull the weight 27, which has swung away from its equilibrium position, back to the equilibrium position.

[0040] The energy synthesis mechanism employs a two-degree-of-freedom planetary gear train, enabling the synthesis of pitch and heave energy. This two-degree-of-freedom planetary gear train consists of a planetary gear 11, a second ring gear 12, a connecting rod 13, and a small sun gear 19. The mechanical torque converted from pitch energy is transmitted to the second ring gear 12 via the meshing of the third shaft 10, the fifth gear 18, and the second ring gear 12. The mechanical torque converted from heave energy is transmitted to the small sun gear 19 via the fourth shaft 35. The two-degree-of-freedom planetary gear train synthesizes the mechanical torques of the second ring gear 12 and the small sun gear 19, and transmits them to the speed increaser 15 and the generator 16 via the connecting rod 13, thus realizing the conversion of mechanical energy into electrical energy.

[0041] The axis of the first shaft 1 is collinear with the rotation axis of the third shaft 35, the tie rod 13, and the second gear ring 12.

[0042] Modeling of nonlinear restoring force in nonlinear pitch energy harvesting:

[0043] In the gravity pendulum structure, the first magnet 21 is fixedly connected to the first toothed ring 3, which is an internal toothed ring. The second magnet 20 is fixedly connected to the first support frame 32, which is fixedly connected to the shell 24. The S poles of the two magnets are placed face-to-face with a certain distance d. Figure 1 As shown. A magnetic repulsion force is formed between the S pole of the first magnet 21 and the S pole of the second magnet 20. The simplified expression for the magnetic repulsion force between the magnets is:

[0044] (1)

[0045] in, It is a magnetic repulsion force. The permeability of free space, The magnetization intensity of the first magnet 21 The volume of the first magnet 21, The magnetization intensity of the second magnet 20 The volume of the second magnet 20 The horizontal distance between the centers of the two magnets. Let be the horizontal distance from the center of the first magnet 21 to the center of rotation. From equation (1), we can see the magnetic repulsion force. Vibration displacement Nonlinear functions.

[0046] Apply equation (1) to By integrating, we obtain the potential energy function corresponding to the nonlinear restoring force between the first magnet 21 and the second magnet 20. ,like Figure 2 As shown, the potential energy function The expression is:

[0047] (2)

[0048] in, and is a coefficient.

[0049] from Figure 2 As can be seen, this potential energy function has two potential wells (corresponding to the concave part in the curve) and one potential barrier (corresponding to the convex part in the curve). This type of potential energy function is usually called a bistable potential energy function. Each of the two potential wells has two minimum points, which are the two stable equilibrium points, corresponding to... Figure 1 The stable equilibrium positions I and II correspond to each other. The highest point of the potential barrier corresponds to the unstable equilibrium point, and... Figure 1 The unstable equilibrium position corresponds to this. Therefore, the addition of the first magnet 21 and the second magnet 20 realizes wave pitching energy capture based on nonlinear vibration. The frequency response function curve of the nonlinear bistable pitching gravity pendulum exhibits nonlinear resonance behavior. Compared with the frequency response function of the linear vibration system, the nonlinear vibration system has a wider operating bandwidth. The schematic diagrams of the frequency response function curves of the two systems are shown in the figure. Figure 3 As shown. From Figure 3 It can be seen that the working bandwidth of the nonlinear frequency response function is significantly wider than that of the linear vibration system, and the pitch energy harvesting mechanism based on nonlinear vibration is more suitable for capturing wave energy with constantly changing frequency and amplitude.

[0050] Modeling of nonlinear restoring force in nonlinear heave energy harvesting:

[0051] The weight 27 is fixedly connected to the connecting rod 28 and slides freely with the connecting rod 28 in the connecting frame 23 with the sliding pair 2. The inclined linear spring 25 returns the weight 27 to the equilibrium position along the length of the connecting rod 28 (defined in this invention). Direction) provides resilience, such as Figure 4 As shown, the expression for the restoring force is:

[0052] (3)

[0053] in, For tilting linear spring 25 in Component of force in direction, The stiffness of a linear spring of size 25. This is the distance between one end of the spring and the sliding pair of the weight. The tilt angle of the linear spring 25. , This is the original length of the linear spring 25.

[0054] Expanding equation (3) using Taylor series, we can simplify it to:

[0055] (4)

[0056] It can be seen from equation (4) that the inclined linear spring 25 in The component of the force applied to the weight in the direction Vibration displacement of the weight 27 The nonlinear function. For equation (4) Integrating, we can also obtain a potential energy function expression similar to equation (2). ,Right now:

[0057] (5)

[0058] in, and For coefficients. Similarly, the vibration system of this invention in the heave aspect is also a nonlinear bistable vibration system, and also has and Figure 3 With the same nonlinear frequency response function curve, the heave energy harvesting mechanism based on nonlinear vibration is also more suitable for capturing wave energy with constantly changing frequency and amplitude.

[0059] The connection relationships of the various components of the wave energy generation device in this embodiment are as follows:

[0060] To ensure the floating wave energy generator remains vertical, a counterweight 26 is fixed to the bottom of the housing 24. A second support frame 36 is fixed to the housing 24. The first shaft 1 rotates freely within the second support frame 36 and is fixed to the first gear ring 3 and the sixth gear 31. One end of the torsion spring 34 is connected to the second support frame 36, and the other end is connected to the first gear ring 3. A first magnet 21 is fixed to the outside of the first gear ring 3, and a second magnet 20 is fixed to the first support frame 32. When the weight 27 is in an unstable vertical equilibrium position, the S pole of the first magnet 21 is directly opposite the S pole of the second magnet 20, and the torsion spring 34 is also in a free state. A connecting frame 23 with a sliding pair 2 is fixed to the outside of the first gear ring 3. The upper end of the linear spring 25 is connected to a fixed point on the connecting frame 23, and the lower end of the linear spring 25 is connected to a fixed point on the connecting rod 28. The weight 27 is fixedly connected to the lower end of the connecting rod 28, and the upper end of the connecting rod 28 is fixedly connected to the first rack 9 and the second rack 17.

[0061] The first rack 9 meshes with the fourth gear 8, and the second rack 17 meshes with the third gear 7. The inner holes of both the fourth gear 8 and the third gear 7 are connected to the outer cylindrical surfaces of two one-way bearings 4 via flat keys. The inner holes of the two one-way bearings 4 are also connected to the outer cylindrical surface of the fourth shaft 35 via flat keys. The first rack limiter 22 and the second rack limiter 30 have a central aperture, within which the fourth shaft 35 can rotate freely. Both the first rack limiter 22 and the second rack limiter 30 have sliding guide grooves to ensure that the first rack 9 and the second rack 17 can slide freely within these guide grooves.

[0062] The first gear ring 3 meshes with the first gear 5, and the sixth gear 31 meshes with the second gear 6. The inner holes of the first gear 5 and the second gear 6 are connected to the outer cylindrical surfaces of the two one-way bearings 4 by a flat key. The inner holes of the two one-way bearings 4 are connected to the outer cylindrical surface of the third shaft 10 by a flat key. The third shaft 10 is fixedly connected to the fifth gear 18.

[0063] The fifth gear 18 meshes with the second ring gear 12. The second shaft 35 is fixedly connected to the small sun gear 19, which meshes with the planetary gear 11. The planetary gear 11 rotates freely on the connecting rod 13 and meshes with the second ring gear 12. Both the second ring gear 12 and the connecting rod 13 can rotate freely in the fifth support frame 39. The connecting rod 13 is connected to the speed increaser 15 via a coupling 14, and the speed increaser 15 is connected to the generator 16 via a coupling 14. Both the speed increaser 15 and the generator 16 are fixed on the sixth support frame 40, which is fixedly connected to the housing 24.

[0064] The lower ends of the first rack 9 and the second rack 17 are fixedly connected to the upper ends of the connecting rod 28, and the upper ends of the first rack 9 and the second rack 17 are fixedly connected to the rack connecting plate 33. The center distance between the third gear 7 and the second rack 17 is equal to the center distance between the fourth gear 8 and the first rack 9. The distance between the sliding guide groove of the first rack 9 in the first rack limiter 22 and the second rack limiter 30 and the center line of the fourth shaft 35 is also equal to the center distance between the fourth gear 8 and the first rack 9. The distance between the sliding guide groove of the second rack 17 in the first rack limiter 22 and the second rack limiter 30 and the center line of the second shaft 35 is also equal to the center distance between the third gear 7 and the second rack 17.

[0065] When the wave energy generation device based on nonlinear vibration of the present invention is excited by waves, it will simultaneously undergo heaving and pitching motions. The weight 27, connecting rod 28, linear spring 25, first rack 9, second rack 17 and rack connecting plate 33 not only slide freely up and down along the length of the connecting rod 28 in the connecting frame 23 with sliding pair 2, but also the weight 27, connecting rod 28, connecting frame 23, linear spring 25, first rack 9, second rack 17, rack connecting plate 33, first gear ring 3, first shaft 1, first rack limiter 22 and second rack limiter 30 all reciprocate around the axis of the first shaft 1 and the second shaft 35.

[0066] During the vertical linear motion of the weight 27, connecting rod 28, linear spring 25, first rack 9, second rack 17 and rack connecting plate 33 in the sliding pair 2 of the connecting frame 23, the first rack 9 and second rack 17 mesh with the fourth gear 8 and third gear 7 respectively. Due to the action of the one-way bearing 4, the reciprocating linear motion of the weight 27 in the vertical direction is transformed into the one-way rotational motion of the second shaft 35. At the same time, the small sun gear 19 also rotates in one direction with the second shaft 35.

[0067] When the weight 27, connecting rod 28, connecting frame 23, linear spring 25, first rack 9, second rack 17, rack connecting plate 33, first gear ring 3, first shaft 1, first rack limiter 22 and second rack limiter 30 reciprocate around the axis of the first shaft 1 and the second shaft 35, due to the meshing of the first gear ring 3 with the first gear 5, the meshing of the sixth gear 31 with the second gear 6, and the action of the one-way bearing 4, the reciprocating swing of the weight 27 in the longitudinal direction is transformed into the one-way rotational motion of the third shaft 10. At the same time, the fifth gear 18 also rotates in one direction with the third shaft 10. The fifth gear 18 meshes with the second gear ring 12, so the second gear ring 12 also rotates in one direction.

[0068] When the weight 27 undergoes counterclockwise / clockwise longitudinal oscillation, the motion path of each gear and shaft is analyzed as follows:

[0069] When the weight 27 undergoes a counterclockwise pitching motion, this motion is transmitted from the first shaft 1 to the first gear ring 3. After the first gear ring 3 meshes with the first gear 5, and since the one-way bearing 4 is in counterclockwise engagement mode, this motion is directly transmitted to the third shaft 10, transforming into the counterclockwise rotational motion of the third shaft 10. Simultaneously, this counterclockwise pitching motion is also transmitted from the first shaft 1 to the sixth gear 31. After the sixth gear 31 meshes with the second gear 6, it transforms into the clockwise rotational motion of the second gear 6. Since the one-way bearing 4 is in clockwise non-meshing mode, the second gear 6 idles and cannot transmit the motion of the sixth gear 31 to the third shaft 10.

[0070] When the weight 27 undergoes a clockwise pitching motion, this motion is transmitted from the first shaft 1 to the sixth gear 31. After the sixth gear 31 meshes with the second gear 6, it is transformed into a counterclockwise rotational motion of the second gear 6. Since the one-way bearing 4 is in counterclockwise engagement mode, this motion is directly transmitted to the third shaft 10, transforming into a counterclockwise rotational motion of the third shaft 10. Simultaneously, this clockwise pitching motion is also transmitted from the first shaft 1 to the first gear ring 3. After the first gear ring 3 meshes with the first gear 5, it is transformed into a clockwise rotational motion of the first gear 5. Since the one-way bearing 4 is in clockwise non-engaging mode, the first gear 5 idles and cannot transmit the motion of the first gear ring 3 to the third shaft 10.

[0071] Therefore, regardless of whether the weight 27 swings clockwise or counterclockwise, the third shaft 10 rotates counterclockwise. To ensure that the same rotational speed is transmitted along both paths, the transmission ratio between the first gear ring 3 and the first gear 5 must be equal to the transmission ratio between the sixth gear 31 and the second gear 6. That is:

[0072] (6)

[0073] in, This represents the number of teeth on the first gear ring 3. This represents the number of teeth on the first gear, 5. The number of teeth on the sixth gear, 32. The number of teeth is the number of teeth on the second gear 6. Furthermore, to ensure the feasibility of transmission, the center distance between the meshing of the first gear ring 3 and the first gear 5 is equal to the center distance between the meshing of the sixth gear 31 and the second gear 6.

[0074] When the weight 27 moves up / down in a straight line, the motion path of each gear and shaft is analyzed as follows:

[0075] When the weight 27 swings downwards in a straight line, the first rack 9 moves downwards. Since the first rack 9 meshes with the fourth gear 8, the fourth gear 8 rotates counterclockwise. At the same time, the second rack 17 also moves downwards. Since the second rack 17 meshes with the third gear 7, the third gear 7 rotates clockwise. Since the one-way bearing 4 is in the counterclockwise meshing working mode, the third gear 7 idles. The fourth gear 8 converts the downward straight swing motion of the weight into the counterclockwise one-way rotational motion of the second shaft 35, so the small sun gear 19 also rotates in one direction with the second shaft 35.

[0076] When the weight 27 swings upward in a straight line, the first rack 9 moves upward. Since the first rack 9 meshes with the fourth gear 8, the fourth gear 8 rotates clockwise. At the same time, the second rack 17 also moves upward. Since the second rack 17 meshes with the third gear 7, the third gear 7 rotates counterclockwise. Since the one-way bearing 4 is in the counterclockwise meshing working mode, the fourth gear 8 idles. The third gear 7 transforms the upward straight swing motion of the weight into the counterclockwise one-way rotational motion of the second shaft 35. As a result, the small sun gear 19 also rotates in one direction with the second shaft 35.

[0077] Therefore, regardless of whether the weight 27 is swinging upwards or downwards in a straight line, the second axis 35 rotates counterclockwise.

[0078] The rotational speeds of pitch and heave in this embodiment are combined as follows:

[0079] The pitching motion of the weight 27 is transmitted to the third shaft 10, fifth gear 18, and second gear 12 via the first shaft 1, first ring gear 3, and first gear 5, or via the sixth gear 31 and second gear 6, forming one power input to the planetary gear train. The swaying motion of the weight 27 is transmitted to the second shaft 35 and small sun gear 19 via the first rack 9 and fourth gear 8, or via the second rack 17 and third gear 7, forming another power input to the planetary gear train. Based on the kinematic relationship between the second ring gear 12, small sun gear 19, planetary gears 11, and connecting rod 13 in the planetary gear train, the expression for the rotational speed of the connecting rod 13 when it is providing power output can be obtained as follows:

[0080] (7)

[0081] in, The rotational speed of tie rod 13. The rotational speed of the first shaft 1, The rotational speed of the second shaft is 35. The number of teeth on the small sun gear is 19. This refers to the number of teeth on the second gear ring 12. The number of teeth on the fifth gear (18). This represents the number of teeth on the first gear ring 3. This represents the number of teeth on the first gear, 5.

[0082] As can be seen from equation (7), the speed of the tie rod 13 is the combined rotational speed of the first shaft 1 and the second shaft 35. After the speed increase effect of the speed increaser 15, the heave kinetic energy and pitch kinetic energy generated by the wave-induced floating body are directly converted into electrical energy under the action of the generator 16.

[0083] In summary, this invention, through the ingenious design of a nonlinear bistable pitch and heave energy harvesting mechanism, utilizes the repulsive force of magnets and the tilting spring to construct a nonlinear restoring force, combines a one-way bearing to realize the conversion of reciprocating motion into unidirectional rotation, and synthesizes the rotational speeds of pitch and heave motions through a planetary gear train. This effectively broadens the frequency bandwidth of wave energy harvesting, significantly improves the utilization efficiency of wave energy with constantly changing frequency and amplitude, and provides an efficient and feasible solution for the practical application of wave energy power generation technology.

[0084] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A wave energy generation method based on nonlinear vibration, characterized in that, include: A gravity pendulum, wherein the gravity pendulum is hinged to a slider and a suspension rod to achieve a composite motion of heave sliding and longitudinal swaying. A rack and pinion gear transmission is set up in the up-and-down sliding direction of the gravity pendulum to convert the heaving ocean energy into mechanical energy, and an internal gear ring transmission is set up in the reciprocating swing direction of the gravity pendulum to convert the pitching ocean energy into mechanical energy; then the two mechanical energies are torque-coupled through a planetary gear system and used for power generation. The gravity pendulum is provided with a spring assembly in the up-and-down sliding direction to provide a non-linear restoring force; the gravity pendulum is provided with a pair of repulsive magnets in the reciprocating swing direction to provide a non-linear restoring force. The gravity pendulum, planetary gear system, and power generation device are sealed inside the housing.

2. The wave energy generation method based on nonlinear vibration according to claim 1, characterized in that, The magnetic repulsion force of the magnet is: （1） in, Indicates magnetic repulsion. Represents the permeability of free space. , These represent the magnetization intensities of the two magnets, respectively. , Let represent the volumes of the two magnets respectively. Indicates the distance between the centers of the two magnets. This indicates the distance from the magnet to the center of rotation of the internal gear ring. This represents the distance between the stable and unstable equilibrium positions of the magnet. express A higher-order infinitesimal raised to the power of 5; The restoring force of the spring is: （3） in, This represents the vertical component of the force on the spring. Indicates the spring stiffness. This indicates the distance from the top of the spring to the pendulum rod of the gravity pendulum. Indicates the tilt angle of the spring. Indicates the original length of the spring. This represents the displacement of the gravity pendulum along the length of the pendulum rod.

3. A wave energy generation device based on nonlinear vibration, characterized in that, The wave energy power generation device adopts the wave energy power generation method according to claim 1 or 2. The wave energy power generation device includes: a shell (24), the shell (24) is a sealed cavity, and the shell (24) is provided with a pitching energy harvesting mechanism, a heave energy harvesting mechanism, an energy synthesis mechanism, and a generator (16). The pitching energy harvesting mechanism converts the pitching of the gravity pendulum into the torque of the rotating shaft through the meshing gear of the internal gear ring; the swaying energy harvesting mechanism converts the swaying of the gravity pendulum into the torque of another rotating shaft through the meshing gear of the rack and pinion; each rotating shaft is provided with a one-way bearing to ensure unidirectional torque transmission; the energy synthesis mechanism combines the torque of the two rotating shafts through the planetary gear system and then transmits it to the generator (16) to generate electricity.

4. A wave energy generation device based on nonlinear vibration according to claim 3, characterized in that, The pitch energy harvesting mechanism includes: a first shaft (1), a first gear ring (3), a sixth gear (31), and a connecting frame (23). The first shaft (1) is rotatably connected to the inner cavity of the housing (24). The first gear ring (3) and the sixth gear (31) are coaxially connected to the first shaft (1) and the three rotate synchronously. The inner teeth of the first gear ring (3) mesh with the first gear (5), and the sixth gear (31) meshes with the second gear (6). The second gear (6) and the first gear (5) are coaxially fitted onto the outer cylindrical surface of the third shaft (10) through one-way bearings. The third shaft (10) is rotatably connected to the inner cavity of the housing (24) and is parallel to the first shaft (1). The third shaft (10) transmits torque to the energy synthesis mechanism. The connecting frame (23) is in the shape of an inverted T. The first toothed ring (3) is fixed to the vertical part of the connecting frame (23). The two ends of the horizontal part of the connecting frame (23) are elastically connected to the weight (27) by a linear spring (25). The horizontal part of the connecting frame (23) is parallel to the end face of the first toothed ring (3).

5. A wave energy generation device based on nonlinear vibration according to claim 4, characterized in that, A first magnet (21) is fixed to the outer circumferential surface of the first gear ring (3), and a second magnet (20) is fixed to the inner cavity of the housing (24); when the weight (27) is in an unstable equilibrium position in the vertical direction, the first magnet (21) and the second magnet (20) are opposite each other with the same pole.

6. A wave energy generation device based on nonlinear vibration according to claim 4, characterized in that, A torsion spring (34) is coaxially sleeved on the first shaft (1). One end of the torsion spring (34) is fixed to the inner cavity of the housing (24), and the other end of the torsion spring (34) is fixed to the first shaft (1).

7. A wave energy generation device based on nonlinear vibration according to claim 4, characterized in that, The connecting frame (23) is provided with a sliding pair (2) along the vertical direction. The sliding pair (2) includes a slider and a vertical slide rail. The upper part of the weight (27) is connected to a vertical connecting rod (28), which is hinged to the slider.

8. A wave energy generation device based on nonlinear vibration according to claim 3, characterized in that, The heave energy harvesting mechanism includes: a first rack (9) and a second rack (17), the first rack (9) meshing with a fourth gear (8), the second rack (17) meshing with a third gear (7), the third gear (7) and the fourth gear (8) being coaxially fitted onto the outer cylindrical surface of a fourth shaft (35) via one-way bearings, the fourth shaft (35) being rotatably connected to the inner cavity of the housing (24); the meshing surfaces of the first rack (9) and the second rack (17) are parallel to each other; the lower ends of the first rack (9) and the second rack (17) are connected to a vertical connecting rod (28), the lower end of the connecting rod (28) being connected to a weight (27); the fourth shaft (35) transmits torque to the energy synthesis mechanism.

9. A wave energy generation device based on nonlinear vibration according to claim 3, characterized in that, The energy synthesis mechanism includes: a planetary gear (11), a second gear ring (12), a connecting rod (13), and a small sun gear (19). The second gear ring (12), the connecting rod (13), and the small sun gear (19) are on the same rotation axis. The second gear ring (12), the connecting rod (13), and the small sun gear (19) are rotatably connected to the inner cavity of the housing (24). The inner ring of the second gear ring (12) meshes with the small sun gear (19) at the same time with the planetary gear (11). The planetary gear (11) is rotatably connected to the planetary gear shaft of the connecting rod (13). The planetary gear (11) and the small sun gear (19) are respectively torque-connected to the torque output shafts of the pitch energy harvesting mechanism and the sway energy harvesting mechanism, and the connecting rod (13) or the second gear ring (12) is torque-connected to the generator (16).

10. A wave energy generation device based on nonlinear vibration according to claim 3, characterized in that, A speed increaser (15) is connected in series between the energy synthesis mechanism and the generator (16).

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