A wave energy converter based on air spring nonlinear variable stiffness

Abstract

The application discloses a wave energy conversion device based on a nonlinear variable stiffness air spring, and relates to the technical field of ocean engineering equipment, which comprises an air spring module, a wave energy collection module and a gas pressure control module. The air spring module is provided with a main cylinder and an auxiliary cylinder, which are communicated through a communication pipe. A first piston is arranged in the main cylinder and connected with a wave energy collection module push rod. A second piston is arranged in the auxiliary cylinder and separates left and right air chambers. The first piston is provided with an upper limit A, a stroke midpoint B and a lower limit C. When the first piston moves from A to B, the lower air chamber of the main cylinder and the left air chamber of the auxiliary cylinder are synchronously compressed to store energy. The application can dynamically adjust the stiffness amplitude, the change rate and the adjustment range, widen the wave capture bandwidth, adapt to complex nonlinear sea conditions, simultaneously have the function of emergency pressure relief and buffer in a huge wave, reduce the impact loss of equipment, effectively improve the wave energy capture efficiency, prolong the service life of the device, and be suitable for offshore and deep sea oscillating buoy wave energy development.

Description

Technical Field

[0001] This invention relates to the field of marine engineering equipment technology, specifically to a wave energy conversion device based on air springs with nonlinear variable stiffness. Background Technology

[0002] Wave energy conversion technologies mainly include the following types: nodding duck type, oscillating water column type, push-pendulum type, wave-focusing energy storage type, oscillating float type, and raft type. Among them, the oscillating float type wave energy device has advantages such as relatively low cost, insensitivity to wave direction, and convenient deployment. At the same time, the energy conversion efficiency of the oscillating float type wave energy device is affected by the randomness of waves (mainly wavelength variation). The oscillating float type wave energy device reaches its optimum when the wave frequency is close to the natural frequency of the float. The natural frequency of the float is mainly controlled by stiffness and mass. Stiffness can be divided into linear stiffness and nonlinear stiffness. In complex sea states and deep-sea areas dominated by nonlinear waves, wave energy devices with nonlinear stiffness have better energy capture effect.

[0003] Existing oscillating float-type wave energy devices mostly use constant stiffness elastic elements. Traditional metal springs have non-adjustable stiffness, and simple single-chamber pneumatic springs only have a single non-linear characteristic, making it impossible to dynamically adjust the stiffness amplitude and rate of change according to real-time sea conditions. In nearshore waters, wave periods and wave heights vary randomly, with high-frequency small waves and low-frequency large waves alternating. Fixed-stiffness systems can only produce a resonant energy-harvesting effect for waves of a specific period. After deviating from the optimal frequency, the energy harvesting efficiency decreases significantly, and the effective operating bandwidth of the device is extremely narrow. For the small, weak waves that occur daily, the system stiffness is too high, limiting the amplitude of the float's movement with the waves. A large amount of wave kinetic energy cannot be transferred to the power generation end, resulting in low utilization of wave resources in the sea area and significantly reducing the overall annual power generation of the equipment and the economic benefits of the project.

[0004] Existing rigidity-unadjustable elastic mechanisms have serious shortcomings in adaptability to deep-sea and stormy sea conditions: when faced with high wave height and strong impact wave loads, fixed stiffness buffer structures cannot adaptively reduce stiffness to achieve flexible force relief. Huge instantaneous impact loads are directly transmitted to the float, transmission push rod and power generation unit, which can easily cause component fatigue deformation and sealing failure. Conventional single-chamber air springs rely on compression and energy storage in a single chamber. The stiffness change curve of the piston throughout its entire stroke is simple and smooth, and it is impossible to adjust the elastic resistance in stages. Under complex nonlinear wave loads, resonance impact and piston overtravel impacting the cylinder are likely to occur.

[0005] In summary, a wave energy conversion device based on nonlinear variable stiffness of air springs is proposed to solve the above problems. Summary of the Invention

[0006] 1. The technical problem to be solved by the present invention

[0007] This invention proposes a method to increase the wave energy capture efficiency of an oscillating float device. The main purpose is to design an oscillating float device with "a nonlinear air spring based on variable stiffness to obtain higher wave energy extraction efficiency and bandwidth".

[0008] 2. Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a wave energy conversion device based on air spring with nonlinear variable stiffness, comprising an air spring module, a wave energy acquisition module, and an air pressure control module; The air spring module includes a main cylinder and an auxiliary cylinder. A connecting pipe is fixedly connected to the auxiliary cylinder, and the end of the connecting pipe away from the auxiliary cylinder is fixedly connected to the middle of the main cylinder. The auxiliary cylinder is fixedly connected to the air pressure control module, which is used to control the air pressure regulation of the main cylinder and the auxiliary cylinder.

[0009] Preferably, a first piston is slidably connected to the inner wall of the main cylinder, and a push rod is fixedly connected to the middle of the upper surface of the first piston. The outer surface of the push rod is slidably installed in the main cylinder, and the end of the push rod away from the first piston is fixedly connected to the wave energy acquisition module.

[0010] Preferably, a second piston is slidably installed in the auxiliary cylinder, and the auxiliary cylinder is divided into a left air chamber and a right air chamber by the second piston. The left air chamber is located on the side of the second piston closer to the connecting pipe, and the right air chamber is located on the side away from the connecting pipe.

[0011] Preferably, the main cylinder has an upper air chamber near the top of the first piston and a lower air chamber near the bottom of the first piston.

[0012] Preferably, the air pressure control module includes an air pump, a solenoid valve, and an air tank; the air pressure control module controls the intake and exhaust of the left and right air chambers respectively through the solenoid valve, thereby adjusting the amplitude of the total stiffness change, the rate of stiffness period change, and the stiffness adjustment range of the air spring, and widening the wave capture bandwidth.

[0013] Preferably, the first piston has three limiting positions A, B, and C in the main cylinder, where B is the midpoint of the main cylinder stroke, A is the upper limit of the upper air chamber, and C is the lower limit of the lower air chamber.

[0014] Preferably, when the first piston moves from A to B, the gas in the lower air chamber of the main cylinder and the left air chamber of the auxiliary cylinder are compressed synchronously to store elastic potential energy; when the first piston moves from B to C, the lower air chamber of the main cylinder is continuously compressed, and the left air chamber is connected to the upper air chamber of the main cylinder to achieve air pressure balance, so that the stiffness of the air spring changes continuously and nonlinearly within the reciprocating stroke of the first piston, adapting to nonlinear and complex sea conditions and waves.

[0015] Compared with the prior art, the wave energy conversion device based on air springs with nonlinear variable stiffness provided by the present invention has the following advantages: (1) This device adopts a linkage air chamber structure formed by the main and auxiliary cylinders and connecting pipes. It achieves segmented differential air pressure coupling by relying on the three-stage limiting and partitioning motion of the first piston: when the piston moves from A to B, the lower air chamber and the left air chamber compress and store energy synchronously, and the stiffness increases rapidly; when the piston moves from B to C, the left air chamber and the upper air chamber of the main cylinder are connected to balance the air pressure, and the stiffness growth rate slows down, forming a smooth and continuous nonlinear stiffness curve within the complete reciprocating stroke of the piston. Unlike the single linear stiffness of traditional metal springs and the abrupt nonlinear characteristics of single-chamber air springs, the stiffness change law of this invention can fit the irregular wave load of the real ocean. Whether it is a small high-frequency wave or a large strong wave, it can match the real-time motion state of the floating body, greatly improving the wave energy capture capability under variable mixed sea conditions, and solving the pain point of traditional devices that only have a narrow band of efficient energy capture.

[0016] (2) The device is equipped with an integrated air pump, solenoid valve and air tank air pressure control module, which can independently and precisely control the intake and exhaust of the left and right air chambers of the auxiliary cylinder, and can change the amplitude of the air spring stiffness change, the rate of stiffness period change and the overall stiffness adjustment range in real time. Under normal and stable sea conditions, it can maintain a fixed stiffness range to adapt to standard period waves; under high-frequency small-amplitude waves, it can quickly switch the air chamber pressure difference to shorten the stiffness response period; under giant wave conditions, it can increase the reference air pressure to increase the upper limit of stiffness; under extreme sea conditions, it can simultaneously depressurize to reduce stiffness and buffer the impact. Compared with traditional elastic structures with completely unadjustable stiffness, this device can actively adapt to waves of different periods and wave heights, effectively broadening the device's high-efficiency operating bandwidth and improving the utilization rate of wave resources in all time periods and all sea areas.

[0017] (3) This invention relies on multi-chamber collaborative energy storage and buffering to distribute wave impact loads to the upper and lower chambers of the main cylinder and the dual chambers of the auxiliary cylinder, thus dispersing the force and avoiding a single component bearing the instantaneous peak load. At the same time, the air pressure control module is equipped with pressure monitoring and emergency exhaust logic. When the sensor detects that the air pressure in the chamber exceeds the standard, the solenoid valve can quickly open the pressure relief circuit, actively reduce the stiffness of the air spring, and flexibly buffer the strong impact brought by the giant waves. Traditional fixed stiffness devices do not have an adaptive force relief structure. Strong wave impacts can easily lead to fatigue damage to the push rod, piston, and cylinder seals. This solution, through pneumatic adaptive buffering and active pressure relief dual protection, significantly reduces the damage of impact loads to transmission and pneumatic core components under extreme sea conditions, reduces failures such as sealing leakage and structural deformation, reduces the frequency and cost of maintenance and repair of marine equipment, and significantly extends the service life of the device at sea. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2This is a schematic diagram of the three-dimensional structure of the present invention in a semi-section state.

[0019] In the picture: 1. Main cylinder; 11. Auxiliary cylinder; 12. Bracket; 13. Push rod; 14. Connecting pipe; 15. Solenoid valve; 16. First piston; 17. Second piston; 21. Left chamber; 22. Right chamber; 31. Upper chamber; 32. Lower chamber. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0022] Example 1, please refer to Figures 1 to 2 As shown: To address the problems mentioned in the technical solutions, this application provides a device comprising three core components: an air spring module, a wave energy harvesting module, and an air pressure control module. The air spring module serves as a variable stiffness elastic buffer and potential energy storage unit, the wave energy harvesting module is responsible for capturing the kinetic energy of ocean waves and transmitting force, and the air pressure control module is used to regulate the air pressure inside the air chamber in real time, thereby achieving dynamic adjustment of the air spring stiffness.

[0023] The air spring module includes a main cylinder 1 and an auxiliary cylinder 11. A connecting pipe 14 is fixedly connected to the side wall of the auxiliary cylinder 11, with one end of the connecting pipe 14, away from the auxiliary cylinder 11, sealed and fixed to the middle of the main cylinder 1. A bracket 12 is mounted on the outside of the main cylinder 1, and the bracket 12 is fixedly connected to the outer wall of the auxiliary cylinder 11, achieving overall support and positioning of the auxiliary cylinder 11 and ensuring the stability of the relative installation position of the two cylinders. The air passage end of the auxiliary cylinder 11 is sealed and connected to the air pressure control module, which independently adjusts and coordinates the air pressure in each chamber of the main cylinder 1 and the auxiliary cylinder 11.

[0024] The first piston 16 is slidably assembled in the inner cavity of the main cylinder 1. The push rod 13 is vertically fixed at the center of the upper surface of the first piston 16. The push rod 13 slides through the top cover of the main cylinder 1 and maintains a dynamic sealing fit with the cylinder wall. The push rod 13 extends out of the top end of the main cylinder 1 and is fixedly connected to the wave energy acquisition module. The reciprocating force generated by the wave impact can be completely transmitted to the first piston 16 through the push rod 13, driving the piston to slide back and forth along the axial direction of the main cylinder 1.

[0025] The second piston 17 is slidably mounted inside the auxiliary cylinder 11. The second piston 17 divides the inner cavity of the auxiliary cylinder 11 into two independent left air chambers 21 and right air chambers 22. The left air chamber 21 is located on the side of the second piston 17 closer to the connecting pipe 14, and the right air chamber 22 is located on the other side of the second piston 17 away from the connecting pipe 14. The second piston 17 can slide along the axial direction of the auxiliary cylinder 11 according to the pressure difference between the two sides, thereby changing the volume ratio of the left and right air chambers.

[0026] With the first piston 16 as the dividing line, the inner cavity of the main cylinder 1 is divided into two sealed air chambers: the upper air chamber 31 is formed above the first piston 16 and below the top cover of the main cylinder 1, and the lower air chamber 32 is formed below the first piston 16 and above the bottom cover of the main cylinder 1. The upper air chamber 31 and the lower air chamber 32 form a linkage air pressure circuit with the connecting pipe 14 and the left air chamber 21 of the auxiliary cylinder 11, respectively. The volume of each air chamber is changed by the movement of the piston, generating elastic restoring force.

[0027] The air pressure control module integrates an air pump, a solenoid valve 15, and an air tank. The air tank is used to store high-pressure backup gas, and the air pump is responsible for replenishing the air source for the entire air circuit. The solenoid valve 15 is connected to the air circuit interfaces of the left air chamber 21 and the right air chamber 22 respectively. The solenoid valve 15 controls the air intake and exhaust actions of the left air chamber 21 and the right air chamber 22 in a time-division manner, thereby precisely adjusting the overall stiffness change amplitude, the periodic change rate of stiffness, and the effective stiffness adjustment range of the air spring, widening the capture bandwidth of the device for waves of different periods, and improving the wave energy capture efficiency.

[0028] The first piston 16 has three limit positions for axial movement inside the main cylinder 1, which are marked as A, B and C respectively. Position B is the midpoint of the effective stroke of the main cylinder piston, position A is the upper limit of the first piston 16, that is, the upper limit of the upper air chamber 31 compressed to the minimum volume, and position C is the lower limit of the first piston 16, that is, the lower limit of the lower air chamber 32 compressed to the minimum volume. The three limits define the safe reciprocating movement range of the piston and avoid the piston from overtraveling and hitting the end of the cylinder, which would cause structural damage.

[0029] When the first piston 16 moves downward from limit A to the midpoint B of its stroke, the volume of the lower air chamber 32 inside the main cylinder 1 continuously decreases and the internal gas is compressed. At the same time, the left air chamber 21 of the auxiliary cylinder 11 is compressed synchronously with the air pressure. The two sealed air chambers synchronously store the elastic potential energy of the gas, providing elastic driving force for the piston's return stroke. When the first piston 16 continues to move downward from the midpoint B to limit C, the lower air chamber 32 of the main cylinder 1 continues to compress and store energy. At this time, the left air chamber 21 and the upper air chamber 31 of the main cylinder 1 are connected through the connecting pipe 14, and the gas in the two air chambers flows freely to achieve air pressure balance. The above-mentioned staged air chamber linkage can enable the air spring to output continuously nonlinear stiffness characteristics within the complete reciprocating stroke of the first piston 16, which can adapt to the changing wave loads and wave frequencies under complex nonlinear sea conditions.

[0030] Example 2: Based on Embodiment 1, but with some differences, the wave energy conversion device based on nonlinear variable stiffness of an air spring proposed in this invention will be described below with reference to specific examples and accompanying drawings. The specific content is as follows: Before the formal assembly and construction of this wave energy air spring variable stiffness device, all core components must be processed and specially pre-treated. All components are manufactured with precision in accordance with marine working condition standards and are equipped with protective treatment.

[0031] First, the bracket (12) is welded and fixed to the outer side of the middle part of the main cylinder (1) to ensure that the welded structure is firm and without deformation. Second, the connecting pipe (14) is sealed and installed. One end is sealed and welded to the pre-reserved opening in the middle of the main cylinder (1), and the other end is sealed and connected to the side wall interface of the auxiliary cylinder (11) to ensure that there is no gas leakage in the pipeline. Third, the auxiliary cylinder (11) is precisely fixed above the bracket (12), the coaxiality of the two cylinders is calibrated, and installation defects such as pipeline pulling and structural deformation are avoided to ensure that the piston movement trajectory is not deviated. After the external structure is installed, the internal components are assembled. The second piston (17) is installed into the auxiliary cylinder, and the inner cavity of the auxiliary cylinder is divided into the left air chamber (21) and the right air chamber (22). The end caps of the cylinder are sealed as a whole. Then the first piston (16) is installed into the main cylinder. The push rod (13) is vertically fixed at the center of the upper surface of the first piston. The push rod passes through the sealing cap at the top of the main cylinder and can slide axially without jamming. Finally, the inner cavity of the main cylinder is divided into the upper air chamber (31) and the lower air chamber (32) with the first piston as the dividing line, and the basic air circuit of the device is fully constructed.

[0032] After the basic air circuit is built, the air circuit connection, signal wiring, and overall sealing pressure resistance test of the air pressure control module are carried out to ensure the stability and reliability of the pneumatic control system. In terms of air circuit connection, the outlet of the high-pressure air tank is connected to the air pump. The main output pipeline of the air pump is divided into two paths, which are respectively connected to a two-position three-way solenoid valve (15). The two independent output pipelines of the solenoid valve are then sealed and connected to the left air chamber (21) and right air chamber (22) of the auxiliary cylinder, respectively, so as to realize the independent control of the air intake and exhaust of the two air chambers by the solenoid valve. In terms of signal acquisition, pressure acquisition sensors are installed in the independent air chambers of the main and auxiliary cylinders. The air pressure data collected by all sensors in real time is uniformly transmitted to the marine control industrial control unit to realize all-weather online monitoring of air chamber pressure. After all air lines and connectors are installed, a pressure resistance and sealing performance test is conducted on the whole machine. The pressure is uniformly increased to 1.2 times the rated working air pressure and maintained for 30 minutes. If there is no drop in air pressure and no air leakage in the lines and cylinders during the pressure holding process, the air line sealing test is qualified and the machine can proceed to the final assembly stage.

[0033] After the gas path inspection is qualified, the overall assembly and docking with the offshore external equipment are carried out. At the same time, a mechanical protection structure is added to avoid structural damage caused by piston overtravel. First, the power end connection is completed. The top of the push rod (13) is rigidly fixed to the wave energy harvesting float to ensure that the float can follow the waves and move up and down, and transmit the mechanical energy of the waves to the piston inside the cylinder without loss. Second, the overall device is fixed. The bottom of the main cylinder is rigidly fixed to the offshore platform base to realize the all-round limit of the whole machine and avoid the overall displacement and shaking of the device caused by the impact of the waves. Then, the unified wiring of the electrical control system is completed. All electrical control components such as solenoid valves, pressure sensors, and air pumps are connected to the offshore control cabinet to realize remote air pressure parameter adjustment on shore and remote start and stop control of the device. Finally, three key operating limits of the piston are defined, namely the upper limit A, the midpoint of the stroke B, and the lower limit C. At the same time, mechanical buffer blocks are added at the corresponding positions of the cylinder to limit the maximum stroke of the piston and prevent the piston from directly hitting the end caps of the cylinder due to overtravel, thus protecting the core structure of the cylinder and piston.

[0034] After the device is put into actual operation at sea, it relies on the undulation of the waves to drive the float, push rod, and first piston to reciprocate. The nonlinear variable stiffness function of the air spring is achieved through three stages of motion. The piston's upward reset stage is the wave return stage, and the motion path is C→B→A. As the waves gradually recede, the downward wave pull on the float completely disappears, and the elastic potential energy of the gas stored in each air chamber is released in a concentrated manner, pushing the first piston upward slowly from the lower limit C to reset. As the first piston 16 moves from C to the midpoint B, the volume of the lower chamber (32) of the main cylinder 1 gradually increases, and the internal air pressure decreases accordingly. At the same time, the connecting pipe drives the left chamber (21) of the auxiliary cylinder 11 to expand synchronously. The second piston slides to the side of the connecting pipe, and the volume of the right chamber (22) is continuously compressed. As the first piston 16 moves from B to the upper limit A, the volume of the upper chamber (31) of the main cylinder 1 continuously shrinks, and the internal gas is compressed and pressurized. At the same time, the left chamber 21 and the upper chamber 31 are connected to release pressure, and the overall stiffness of the air spring gradually decreases until the first piston 16 reaches the upper limit A, completing a single complete upward reset action. The device enters the standby state, waiting for the next wave impact load.

[0035] After a new wave lifts the buoy, the push rod moves downward under the pressure of the buoy, driving the first piston 16 to compress downward from A to C. This downward movement is divided into two stages: compression and energy storage before the midpoint and nonlinear variable stiffness after the midpoint, completing wave energy acquisition and adaptive stiffness adjustment. The first stage is the compression and energy storage stage before the midpoint from A to B. The first piston 16 directly compresses the lower chamber (32) of the main cylinder 1. The volume of the lower chamber 32 decreases rapidly, and the internal air pressure increases sharply. At the same time, the connecting pipe (14) in the middle of the main cylinder 1 directly connects to the left chamber (21) of the auxiliary cylinder 11. The high-pressure gas in the lower chamber 32 synchronously squeezes the left chamber 21, realizing the synchronous compression of the lower chamber 32 and the left chamber 21, and coordinating the storage of gas elastic potential energy. During this stage, the two chambers are under pressure together, and the air spring stiffness rises rapidly, which can perfectly adapt to small and medium wave loads at sea and efficiently capture wave mechanical energy. The second stage is the nonlinear variable stiffness stage from the midpoint of B→C to the lower limit. The piston continues to move downward after passing the midpoint B of the stroke. The lower air chamber 32 continues to compress and increase pressure, providing constant basic elastic resistance. At the same time, the left air chamber (21) and the upper air chamber (31) of the main cylinder are fully connected through the connecting pipe. The gas in the two chambers is interconnected and the air pressure is automatically balanced. The left air chamber 21 exits independent pressure-bearing work. The overall pressure-bearing air chamber volume of the device changes abruptly, and the rate of increase of air spring stiffness slows down significantly, forming a continuous and smooth nonlinear stiffness curve. When the piston reaches the lower limit C, the volume of the lower air chamber 32 is compressed to the minimum value, the gas elastic potential energy storage reaches the peak value, and the single wave energy acquisition process ends.

[0036] In response to the varying wave cycles and heights in different sea areas and at different times, the device uses an air pump, a high-pressure air tank, and a two-position three-way solenoid valve (15) to work together to adjust the air pressure in the dual air chambers in real time and dynamically switch the air spring stiffness range to adapt to all types of sea conditions. Under stable and normal sea conditions, the basic pressure stabilization mode is activated, the air tank outputs a constant working air pressure, the solenoid valve starts and stops intermittently, maintaining a fixed pressure difference between the left and right air chambers, and the device stiffness range remains stable, adapting to normal cycle waves; when facing large wave heights and strong wave loads, the system activates the stiffness amplitude increase mode, the air pump works continuously, the solenoid valve 15 opens the left air chamber intake circuit and simultaneously opens the right air chamber 22 exhaust circuit, increasing the reference air pressure in the left air chamber, raising the dual air chamber compression limit pressure, increasing the maximum stiffness of the spring, resisting the impact of large waves, and preventing the device structure from being overloaded and damaged; when facing short-cycle high-frequency small-amplitude waves, the system adjusts the stiffness change rate, and the solenoid valve 15 quickly alternates between the left and right air chambers. The intake and exhaust circuits alter the sliding response speed of the second piston 17, shortening the stiffness switching cycle to match the motion patterns of high-frequency waves and broadening the wave capture bandwidth of the device. Facing complex mixed sea conditions with alternating large and small waves, the air tank, in conjunction with the air pump, dynamically replenishes high-pressure gas, expanding the pressure difference adjustment range between the left and right air chambers and enabling continuous, wide-range switching of spring stiffness from low to high stiffness. In the event of extreme giant waves, the pressure sensor monitors in real-time if the air chamber pressure exceeds the limit, and the solenoid valve 15 automatically opens the emergency exhaust circuit, simultaneously and rapidly depressurizing the left and right air chambers, reducing the overall stiffness of the air spring, buffering the strong impact load of giant waves, and providing comprehensive protection for the cylinder, piston, and other core precision pneumatic structures. Please refer to the above working process. Figures 1 to 2 .

[0037] It should be noted that the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A wave energy conversion device based on air springs with nonlinear variable stiffness, characterized in that, Includes an air spring module, a wave energy acquisition module, and an air pressure control module; The air spring module includes a main cylinder (1) and an auxiliary cylinder (11). A connecting pipe (14) is fixedly connected to the auxiliary cylinder (11), and one end of the connecting pipe (14) away from the auxiliary cylinder (11) is fixedly connected to the middle of the main cylinder (1). The auxiliary cylinder (11) is fixedly connected in the air pressure control module, which is used to control the air pressure regulation of the main cylinder (1) and the auxiliary cylinder (11).

2. The wave energy conversion device based on an air spring with nonlinear variable stiffness according to claim 1, characterized in that, The inner wall of the main cylinder (1) is slidably connected to a first piston (16), and a push rod (13) is fixedly connected to the middle of the upper surface of the first piston (16). The outer surface of the push rod (13) is slidably installed in the main cylinder (1), and the end of the push rod (13) away from the first piston (16) is fixedly connected to the wave energy acquisition module.

3. The wave energy conversion device based on an air spring with nonlinear variable stiffness according to claim 2, characterized in that, The auxiliary cylinder (11) is slidably mounted with a second piston (17). The auxiliary cylinder (11) is divided into a left air chamber (21) and a right air chamber (22) by the second piston (17). The left air chamber (21) is located on the side of the second piston (17) closer to the connecting pipe (14), and the right air chamber (22) is located on the side away from the connecting pipe (14).

4. The wave energy conversion device based on an air spring with nonlinear variable stiffness according to claim 1, characterized in that, The main cylinder (1) has an upper air chamber (31) near the top of the first piston (16) and a lower air chamber (32) near the bottom of the first piston (16).

5. A wave energy conversion device based on an air spring with nonlinear variable stiffness according to claim 1, characterized in that, The air pressure control module includes an air pump, a solenoid valve (15), and an air storage tank. The air pressure control module controls the intake and exhaust of the left air chamber (21) and the right air chamber (22) respectively through the solenoid valve (15), thereby adjusting the amplitude of the change in the total stiffness of the air spring, the rate of change of the stiffness period, and the stiffness adjustment range, and widening the wave capture bandwidth.

6. A wave energy conversion device based on an air spring with nonlinear variable stiffness according to claim 4, characterized in that, The first piston (16) has three limit positions in the main cylinder (1), namely A, B and C. B is the midpoint of the main cylinder stroke, A is the upper limit of the upper air chamber (31) and C is the lower limit of the lower air chamber (32).

7. A wave energy conversion device based on an air spring with nonlinear variable stiffness according to claim 6, characterized in that, When the first piston (16) moves from A to B, the gas in the lower air chamber (32) of the main cylinder (1) and the left air chamber (21) of the auxiliary cylinder (11) are compressed synchronously to store elastic potential energy. When the first piston (16) moves from B to C, the lower air chamber (32) of the main cylinder (1) is continuously compressed, and the left air chamber (21) is connected to the upper air chamber (31) of the main cylinder (1) to achieve air pressure balance, so that the stiffness of the air spring changes continuously and nonlinearly within the reciprocating stroke of the first piston (16) to adapt to nonlinear complex sea wave conditions.

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