Water circulation purifying device for aquaculture

Abstract

The application relates to the technical field of aquaculture and water treatment engineering, and discloses a water circulation purification device for aquaculture, which comprises a shell assembly, the shell assembly is provided with a water inlet, a water outlet and a sewage outlet, a diaphragm pulse sewage discharge assembly is arranged at the bottom of the shell assembly, the sewage outlet is connected with the feed inlet of the diaphragm pulse sewage discharge assembly through a one-way valve, an elastic suspension assembly is arranged in the shell assembly, a filter assembly is connected to the outer side of the elastic suspension assembly, the elastic suspension assembly is suspended along the axial direction of the shell assembly and generates vibration under the impact of water flow, and the vibration state generated by the elastic suspension assembly comprises a first amplitude mode and a second amplitude mode. Through the Venturi flow channel and the elastic suspension assembly, the fluid pressure difference potential energy gradually accumulated due to the blockage of filter material in the filtering process can be captured and converted into mechanical kinetic energy for driving the filter assembly to generate large amplitude stall flutter, so that self-adaptive circulating cleaning is realized without external energy input.

Description

Technical Field

[0001] This invention relates to the field of aquaculture and water treatment engineering technology, specifically to an aquaculture water circulation and purification device. Background Technology

[0002] In modern high-density recirculating aquaculture systems, the rapid removal of suspended particulate matter (including uneaten feed, fish feces, and bioflocs) from the aquaculture water is crucial for maintaining the system's ecological balance. If suspended solids are not separated in a timely manner, they will not only directly increase water turbidity and induce gill diseases in fish, but will also decompose in the system to produce toxic substances such as ammonia nitrogen and nitrite, leading to overload of the biological filter. Therefore, efficient and reliable physical filtration equipment is the "kidney" of the aquaculture system.

[0003] Currently, mainstream physical filtration technologies for aquaculture water mainly rely on rotary drum microfilters or pressure sand filters. Although these devices are relatively mature in terms of retention efficiency, their underlying design logic still has significant limitations in practical engineering applications and long-term operation. Existing technologies mainly adopt an "adversarial" cleaning strategy, which relies on an electric motor to forcefully rotate the filter screen, combined with a high-pressure backwash pump to generate a powerful water jet to remove blockages. This "energy-consuming for-cleanliness" model results in high equipment operating costs, and in remote aquaculture areas or areas with unstable power supply, the high energy consumption of the equipment has become a bottleneck for its widespread adoption.

[0004] More critically, traditional equipment is highly dependent on electronic control systems. Existing automatic backwashing logic is generally based on data collected by level or pressure sensors, which is then processed by a PLC or microcontroller to control the actuators. However, aquaculture workshops are typically located in corrosive environments with high humidity and high salt spray. Precise electronic sensors and circuit boards are highly susceptible to moisture-induced short circuits, contact oxidation, or signal drift, leading to equipment malfunctions or complete failure. Once the automatic control system fails, the filter will quickly become clogged, causing water overflow and resulting in serious water quality incidents. This "strong electronic control, weak mechanical" approach inherently reduces the system's robustness under harsh operating conditions.

[0005] Furthermore, from the perspective of the micro-dynamics of solid-liquid separation, existing backwashing mechanisms often pose a risk of secondary pollution during the wastewater discharge process. During high-pressure backwashing, the intense turbulent water flow in traditional equipment easily breaks down already aggregated organic waste into micron-sized particles. These broken particles are unlikely to settle in subsequent waste collection stages; instead, they resuspend and leak back into the aquaculture pond through the filter media, leading to a gradual increase in the concentration of dissolved organic carbon in the water and increasing the difficulty of subsequent biological treatment. At the same time, most filtration equipment lacks a synchronous mechanism for "immediate production and discharge" of waste, causing waste to remain in the tank for too long, making it highly susceptible to fermentation and decomposition, violating the principle of "rapid separation" in recirculating aquaculture systems. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a water circulation and purification device for aquaculture. This device utilizes the kinetic and potential energy of the fluid itself to achieve adaptive state switching of the filter components through fluid-structure interaction. Without the need for external power drive and electronic sensor control, it solves the problems of high energy consumption, high failure rate, and easy breakage and leakage of dirt in traditional filtration equipment.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an aquaculture water circulation and purification device, comprising a shell assembly, wherein the shell assembly is provided with an inlet, an outlet, and a drain outlet; a diaphragm pulse drain assembly is provided at the bottom of the shell assembly; the drain outlet is connected to the inlet of the diaphragm pulse drain assembly via a one-way valve; an elastic suspension assembly is provided inside the shell assembly; a filter assembly is connected to the outside of the elastic suspension assembly; the elastic suspension assembly is suspended along the axial direction of the shell assembly and vibrates under the impact of water flow; the vibration state generated by the elastic suspension assembly includes a first amplitude mode and a second amplitude mode; when acting on the filter... When the fluid resistance on the component increases to a critical threshold due to the trapping of dirt, it triggers the vibration state of the elastic suspension component to switch from the first amplitude mode to the second amplitude mode. The amplitude of the second amplitude mode is greater than that of the first amplitude mode. The vibration inertial force in the second amplitude mode is used to remove dirt attached to the surface of the filter component. The elastic suspension component is coupled to the drive part of the diaphragm pulse drainage component. The axial reciprocating motion of the elastic suspension component in the second amplitude mode directly drives the drive part of the diaphragm pulse drainage component to run, thereby changing the internal volume of the diaphragm pulse drainage component, so that the diaphragm pulse drainage component sucks in dirt from the bottom of the housing component and discharges it.

[0008] Preferably, the housing assembly includes a cylindrical body located in the upper middle part and an inverted conical sludge collection hopper integrally formed with the body and located at its bottom. A removable sealing top cover is provided on the top of the body, and an automatic air vent valve is provided on the sealing top cover to discharge the air accumulated at the top of the body. The water inlet is opened at the bottom of the body near the junction of the body and the sludge collection hopper. The water inlet is connected to the output pipe of the circulating water pump. The axial direction of the water inlet is tangential to the cross-section of the body, so that the sewage enters perpendicular to the radius of the body and cuts into the body along the tangent direction of the inner wall of the body. A Venturi constriction tube is also provided between the water inlet and the output pipe of the circulating water pump to accelerate the fluid and form a vortex at the bottom of the housing assembly.

[0009] Preferably, the inner wall of the top of the cylindrical body is provided with an annular overflow weir, and the outlet is opened at the top of the cylindrical body and connected to the annular overflow weir.

[0010] Preferably, the diaphragm pulse sewage discharge assembly includes a sewage discharge chamber, which is sealed and fixedly connected to the opening at the bottom of the sewage collection hopper via a flange, and a diaphragm is provided between the two. The outer edge of the diaphragm is embedded and fixedly connected between the sewage discharge chamber and the opening at the bottom of the sewage collection hopper. A support plate is fixedly and sealed to the middle of the diaphragm, and a connecting rod is fixedly connected to the top of the support plate. The upper inlet of the sewage discharge chamber is connected to the sewage discharge port via a one-way valve, and a discharge port is provided at the bottom of the sewage discharge chamber. A rubber duckbill valve is provided at the discharge port.

[0011] Preferably, the elastic suspension assembly includes a hollow shaft, a bellows for elastic support is fixedly connected to the bottom end of the hollow shaft, a flow stabilizer is fixedly connected to the top end of the bellows, the outer wall of the flow stabilizer is fixedly connected to the inner wall of the sludge collection hopper, the top end of the connecting rod passes through the flow stabilizer and is inserted into the bellows, and the top end of the connecting rod is fixedly connected to the bottom end of the hollow shaft.

[0012] Preferably, a moving magnetic ring is fixedly connected to the top of the hollow shaft, and a fixed magnetic ring assembly is provided on the bottom wall of the sealed top cover. The moving magnetic ring and the fixed magnetic ring assembly are arranged with the same pole facing each other. When the elastic suspension assembly is in the equilibrium position or the first amplitude mode, the nonlinear radial magnetic repulsion force generated between the moving magnetic ring and the fixed magnetic ring assembly provides positive stiffness restoring force for the elastic suspension assembly. When the displacement of the elastic suspension assembly exceeds the magnetic equilibrium critical point, the nonlinear radial magnetic repulsion force exhibits negative stiffness characteristics.

[0013] Preferably, the fixed magnetic ring assembly includes an adjusting screw, the top end of which passes through and is rotatably connected to the center of the sealing top cover, and is fixedly connected to an adjusting knob above the sealing top cover. The bottom end of the adjusting screw is rotatably connected to the center of a support frame one. The threaded end of the middle part of the adjusting screw passes through and is threadedly connected to a support frame two. The top end of the support frame one is fixedly connected to the bottom wall of the sealing top cover. The upper part of the support frame two is embedded in and slidably connected to the support frame one. The bottom end of the support frame two is fixedly connected to a fixed magnetic ring. The fixed magnetic ring is concentrically and coaxially suspended around the moving magnetic ring, and a preset radial air gap is maintained between the two.

[0014] Preferably, the filter assembly includes multiple filter blades arranged in a multi-layered staggered spiral array along a hollow shaft. Adjacent filter blades have a preset phase offset angle in the circumferential direction. The filter blades have an asymmetric airfoil cross-section. The root of the filter blade is hinged to a hinge seat fixed to the outer wall of the hollow shaft. An elastic reset element is also provided between the hinge seat and the root of the filter blade to provide a preload force to hold the filter blade in the initial angle of attack position. When the torque generated by the fluid resistance acting on the filter blade is greater than the preload torque of the elastic reset element, the filter blade rotates around the pin of the hinge seat to increase the angle of attack, thereby inducing stall flutter.

[0015] Preferably, the filter wing plate includes a rigid support frame and a flexible microporous filter membrane skin tightly wrapped around the rigid support frame. The rigid support frame defines the outer contour of the filter wing plate and multiple internal perforated windows. The flexible microporous filter membrane skin covers the perforated windows to form an actual filter surface. The root of the filter wing plate is also provided with a flexible sealing skirt, which covers the gap of the hinge seat pin.

[0016] This invention provides a water recycling and purification device for aquaculture. It has the following beneficial effects: 1. This invention utilizes a Venturi channel and an elastic suspension assembly to capture the fluid pressure differential potential energy that gradually accumulates during filtration due to filter media clogging. When the accumulation of contaminants causes the fluid resistance to cross a critical point, this accumulated energy is released instantaneously, transforming into mechanical kinetic energy that drives the filter assembly to undergo significant stall vibration. This design transforms "head loss," considered a negative factor in traditional filtration, into beneficial "cleaning power," enabling the system to self-adaptive cyclic cleaning without external energy input. Simultaneously, the elastic suspension assembly physically rigidly binds the cleaning action of the upper filter assembly to the sludge discharge action at the bottom. Only when the filter assembly enters a large-scale resonant cleaning mode will its violent axial swaying motion directly drive the diaphragm pulse pump at the bottom through a rigid connection. This synchronization mechanism ensures that the sludge cake detached from the filter screen is instantly sucked into the pump and discharged from the system upon settling, preventing the resuspension and accumulation of contaminants within the tank and achieving immediate removal of solid waste.

[0017] 2. This invention employs a variable angle of attack design with an eccentric hinge connection. The additional drag torque generated by accumulated debris forces the wing plate to rotate to a stall angle, actively inducing dynamic stall in the fluid. This stall flutter induced by structural deformation exhibits divergent characteristics, capable of extracting energy from the fluid far exceeding that of ordinary vortex-induced vibrations. This ensures that even under conditions of low circulating water pump flow, a powerful inertial force sufficient to disintegrate stubborn biofilms and sticky filter cakes can be generated. Simultaneously, the nonlinear characteristics of like-pole magnetic repulsion are utilized to construct a physical threshold switch for the system. During normal filtration, the magnetic force exhibits positive stiffness to maintain the slight flutter of the elastic suspension assembly, ensuring filtration accuracy and preventing microparticle bridging. When the blockage resistance pushes the elastic suspension assembly to displace beyond the magnetic equilibrium point, the system instantly reverses to a negative stiffness characteristic, releasing the constraint on large-amplitude oscillations. This triggering method based on the breaking of mechanical equilibrium replaces expensive and easily failed electronic sensors and control circuits in humid environments, greatly improving the reliability and durability of the equipment in harsh aquaculture environments.

[0018] 3. This invention, through its neutral buoyancy design with a central hollow shaft, dynamically decouples the component's gravity from the fluid's excitation force. This allows even minute fluid pulsations to maintain the filter's daily micro-vibration, effectively delaying biofilm aging and dead zone formation. Simultaneously, the vertical tower-like structure integrates bottom swirling centrifugal pre-separation with upper and middle precision interception functions, accomplishing the dual tasks of large particle settling and fine suspended solids removal within a single container. This significantly reduces the footprint and piping complexity of the aquaculture water treatment system. Attached Figure Description

[0019] Figure 1 This is a perspective view of the present invention; Figure 2 This is a schematic diagram of the internal structure of the housing assembly in this invention; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 for Figure 2 Enlarged view at point B in the middle; Figure 5 This is a top view of the filter component in this invention.

[0020] The components include: 1. Shell assembly; 101. Cylinder; 102. Sludge collection hopper; 103. Inlet; 104. Outlet; 105. Sludge discharge port; 106. Check valve; 107. Annular overflow weir; 2. Sealed top cover; 201. Automatic air vent valve; 3. Diaphragm pulse sewage discharge assembly; 301. Sludge discharge chamber; 302. Diaphragm; 303. Support plate; 304. Connecting rod; 305. Rubber duckbill valve; 4. Elastic suspension assembly; 401. Hollow shaft; 402. Bellows; 5. Filter wing plate; 6. Venturi constriction tube; 7. Flow stabilizer bracket; 8. Moving magnetic ring; 9. Fixed magnetic ring assembly; 901. Adjusting screw; 902. Adjusting knob; 903. Support frame one; 904. Support frame two; 905. Fixed magnetic ring. Detailed Implementation

[0021] 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see the appendix Figure 1 -Appendix Figure 5This invention provides an aquaculture water circulation and purification device, including a shell assembly 1. The shell assembly 1 has an inlet 103, an outlet 104, and a drain 105. A diaphragm pulse drain assembly 3 is provided at the bottom of the shell assembly 1. The drain 105 is connected to the inlet of the diaphragm pulse drain assembly 3 through a one-way valve 106. An elastic suspension assembly 4 is provided inside the shell assembly 1. A filter assembly is connected to the outside of the elastic suspension assembly 4. The elastic suspension assembly 4 is suspended along the axial direction of the shell assembly 1 and vibrates under the impact of water flow. The vibration state generated by the elastic suspension assembly 4 includes a first amplitude mode and a second amplitude mode. When acting on the filter... When the fluid resistance on the component increases to a critical threshold due to the trapping of dirt, it triggers the vibration state of the elastic suspension component 4 to switch from the first amplitude mode to the second amplitude mode. The amplitude of the second amplitude mode is greater than that of the first amplitude mode. The vibration inertial force in the second amplitude mode is used to remove dirt attached to the surface of the filter component. The elastic suspension component 4 is coupled with the drive part of the diaphragm pulse drainage component 3. The axial reciprocating motion of the elastic suspension component 4 in the second amplitude mode directly drives the drive part of the diaphragm pulse drainage component 3 to run, thereby changing the internal volume of the diaphragm pulse drainage component 3, so that the diaphragm pulse drainage component 3 sucks in dirt from the bottom of the housing component 1 and discharges it.

[0023] The housing assembly 1 includes a cylindrical body 101 located in the upper middle part, and an inverted conical sludge collection hopper 102 integrally formed with the body 101 and located at its bottom. A removable sealing top cover 2 is provided on the top of the body 101. An automatic air vent valve 201 is provided on the sealing top cover 2 to discharge the air accumulated at the top of the body 101. A water inlet 103 is opened at the bottom of the body 101 near the junction of the body 101 and the sludge collection hopper 102. The water inlet 103 is connected to the output pipe of the circulating water pump. The axial direction of the water inlet 103 is tangential to the cross-section of the body 101, so that the sewage enters perpendicular to the radius of the body 101 and cuts into the tangent direction of the inner wall of the body 101. A Venturi constriction tube 6 is also provided between the water inlet 103 and the output pipe of the circulating water pump to accelerate the fluid and form a vortex at the bottom of the housing assembly 1. An annular overflow weir 107 is provided on the inner wall of the top of the cylindrical body 101, and the outlet 104 is opened at the top of the cylindrical body 101 and is connected to the annular overflow weir 107.

[0024] The housing assembly 1 serves as the supporting base and fluid container for the entire device, and is installed in a vertical tower-like structure. The housing assembly 1 includes a vertical cylindrical body 101 located in the upper middle part and an inverted conical sludge collection hopper 102 integrally formed or flanged to the bottom of the cylindrical body. The body 101 is preferably made of transparent high-strength acrylic or corrosion-resistant stainless steel to facilitate observation of the internal flow field and the sludge accumulation on the filter components. The top of the housing assembly 1 is equipped with a removable sealing cap 2, which has an automatic air vent valve 201 to release air accumulated at the top during the initial water filling and operation of the device, preventing air pockets from forming and affecting flow field stability.

[0025] The fluid input system of the shell assembly 1 employs a specific flow channel shaping design to obtain driving energy. The inlet 103 is located at the junction of the cylinder 101 and the sludge collection hopper 102 or on the lower side wall of the cylinder 101. The axial direction of the inlet 103 does not intersect with the cross-section of the cylinder 101, but is arranged tangentially, that is, the water inlet direction is perpendicular to the radius of the cylinder and cuts into the inner wall of the cylinder 101.

[0026] To maximize the conversion of the static pressure potential energy of the fluid pumped by the circulating water pump into kinetic energy, a Venturi constriction tube 6 is installed at the inlet 103. The cross-sectional area of ​​this Venturi constriction tube 6 gradually decreases along the fluid flow direction. According to Bernoulli's principle, when the aquaculture circulating water flows through this constriction tube section, the flow velocity increases significantly while the static pressure decreases. The accelerated high-speed water flow enters the shell assembly 1 tangentially, inducing a strong swirling field in the sludge collection hopper 102 region.

[0027] The swirling flow field forms a centrifugal pre-separation zone at the bottom of the shell assembly 1. Large solid impurities (such as uneaten food, fish feces, and gravel) with a density greater than water carried in the water flow entering the shell assembly 1 are thrown towards the inner wall of the shell assembly 1 under the action of centrifugal force generated by high-speed rotation, and then spiral down along the wall surface, eventually collecting in the sedimentation zone at the bottom of the collection hopper 102, thereby reducing the physical load on the subsequent suspended filter components.

[0028] The pre-separated water flow forms an upward flow in the central region of the shell assembly 1 and enters the main filtration zone. To ensure that the filtered clean water flows out smoothly, an annular overflow weir 107 is provided on the top inner wall of the shell assembly 1. The annular overflow weir 107 is composed of a water collection tank surrounding the inner wall, and the outlet 104 is connected to the annular overflow weir 107. The clean water flow after being treated by the filtration assembly rises to the liquid surface, overflows evenly into the annular overflow weir 107, and then converges to the outlet 104 for discharge. This overflow weir design eliminates the local suction turbulence that may be caused by a single outlet point, ensures the uniformity of the velocity distribution of the upward flow field inside the cylinder 101, and provides a stable laminar flow working environment for the elastic suspension assembly 4.

[0029] A drain port 105 is provided at the bottom of the sludge collection hopper 102, which is connected to the high-concentration accumulation area of ​​gravity-sedimented sludge. A diaphragm pulse sludge discharge assembly 3 is installed at the bottom opening of the sludge collection hopper 102, and the drain port 105 is connected to the diaphragm pulse sludge discharge assembly 3 through a one-way valve 106. Through the above structure, the overall shell assembly 1 constructs a fluid treatment environment that integrates cyclone centrifugal separation, laminar flow upward filtration, and gravity sedimentation sludge collection.

[0030] The elastic suspension assembly 4 includes a hollow shaft 401, a bellows 402 for elastic support fixedly connected to the bottom end of the hollow shaft 401, a flow stabilizer 7 fixedly connected to the top end of the bellows 402, the outer wall of the flow stabilizer 7 fixedly connected to the inner wall of the sludge collection hopper 102, the top end of the connecting rod 304 passing through the flow stabilizer 7 and inside the bellows 402, and the top end of the connecting rod 304 fixedly connected to the bottom end of the hollow shaft 401.

[0031] The filter assembly includes multiple filter vanes 5 arranged in a multi-layered staggered spiral array along the hollow shaft 401. Adjacent filter vanes 5 have a preset phase offset angle in the circumferential direction. The filter vanes 5 have an asymmetric airfoil cross section. The root of the filter vane 5 is hinged to a hinge seat fixed to the outer wall of the hollow shaft 401. An elastic reset element is also provided between the hinge seat and the root of the filter vane 5 to provide a preload force to hold the filter vane 5 in the initial angle of attack position. When the torque generated by the fluid resistance acting on the filter vane 5 is greater than the preload torque of the elastic reset element, the filter vane 5 rotates around the pin of the hinge seat to increase the angle of attack, thereby inducing stall flutter. The filter wing plate 5 includes a rigid support frame and a flexible microporous filter membrane skin tightly wrapped around the rigid support frame. The rigid support frame defines the outer contour of the filter wing plate 5 and multiple hollow windows inside. The flexible microporous filter membrane skin covers the hollow windows to form the actual filter surface. A flexible sealing skirt is also provided at the root of the filter wing plate 5, which covers the gap of the hinge seat pin.

[0032] The main structure of the elastic suspension assembly 4 is a hollow shaft 401. To eliminate the suppressive effect of gravity on vibration modes and improve the system's response sensitivity to fluid forces, the hollow shaft 401 is made of lightweight, high-strength composite material (such as carbon fiber reinforced polymer or ABS engineering plastic), and its interior is designed as a sealed cavity structure. By precisely controlling the ratio of cavity volume to shaft mass, the average density of the hollow shaft 401 in water is made to be basically consistent with the density of the surrounding fluid medium, i.e., exhibiting neutral buoyancy or slightly positive buoyancy. This design makes the hollow shaft 401 exhibit "zero-gravity suspension" characteristics in water, where even the slightest fluid pulsation can induce displacement.

[0033] The bottom end of the hollow shaft 401 is connected to a high-fatigue-life bellows 402 as an elastic support. The lower end of the elastic support is fixed to the flow stabilizer 7 at the bottom of the housing assembly 1, and the upper end is connected to the hollow shaft 401. The bellows 402 structure gives the hollow shaft 401 multi-degree-of-freedom motion capability, enabling it not only to bend and swing laterally, but also to extend and retract (heavy motion) along the axial direction to a certain extent, providing the necessary mechanical stroke for the subsequent diaphragm pulse sewage discharge assembly 3.

[0034] Several layers of filter vanes 5 are distributed in a spiral or layered radial pattern along the axial direction of the hollow shaft 401, forming the filtration matrix of the device. The skeleton of each hollow shaft 401 adopts an asymmetrical streamlined airfoil design to optimize the lift-to-drag ratio characteristics when the fluid flows through it. The surface of the filter vane 5 skeleton is covered with microporous filter media, and the pore size of the filter media is selected according to the characteristics of the feces and uneaten feed particles of the specific aquaculture species (usually 30 micrometers to 80 micrometers).

[0035] The key improvement of this invention lies in the connection method between the filter vane 5 and the hollow shaft 401. Unlike the rigid welding in the prior art, this embodiment uses a flexible linkage mechanism with a variable angle of attack for connection. Specifically, several hinge seats are fixed on the outer wall of the hollow shaft 401, and each hinge seat is provided with a pin perpendicular to the fluid flow direction (i.e., the horizontal direction). A rotating arm is provided at the root of the filter vane, which is sleeved on the pin, so that the hollow shaft 401 can rotate freely around the pin within a certain angle range.

[0036] To maintain the orientation of the hollow shaft 401, an elastic reset element is integrated at the hinge, preferably a stainless steel torsion spring located inside the hinge seat. One end of the torsion spring is anchored to the stationary hinge seat, and the other end is connected to the rotating filter vane 5. The torsion spring is preset with a specific initial preload, which presses the filter vane 5 against a set mechanical limit block, maintaining its initial filtration angle of attack under no or low external force. This initial filtration angle of attack is typically set to a small value (e.g., 0 to 15 degrees relative to the incoming flow direction) to ensure that the fluid can flow smoothly over the surface of the filter vane 5 in normal filtration mode, forming an adhering laminar flow and maintaining a low flow resistance coefficient.

[0037] The filter vane 5 has a significant eccentric geometry. Specifically, the aerodynamic center (also known as the pressure center, i.e., the point of application of the fluid resultant force) of the filter vane 5 is designed to be located downstream of the hinge pin (i.e., the rotation center), forming a clear physical eccentricity between the two. This structure establishes a torque coupling relationship between fluid resistance and the attitude of the filter vane 5: when the positive resistance generated by the fluid flowing through the filter vane 5 acts on the aerodynamic center, a torque is generated that rotates around the pin.

[0038] This mechanical structure also includes a maximum angle limiting structure to restrict the maximum rotation amplitude of the filter vane 5, i.e., the cleaning angle of attack. This cleaning angle of attack is set to be greater than the critical stall angle of the airfoil at the corresponding Reynolds number (typically 30 to 60 degrees). This structural logic establishes the following physical response mechanism: During the normal filtration stage, due to the clean surface of the filter media and good fluid permeability, the torque generated by the resistance is less than the preload torque of the torsion spring, and the filter vane 5 maintains a stable streamlined posture; however, when the filter media surface traps dirt to form a filter cake, causing a decrease in water permeability, the fluid resistance increases sharply. Once the resistance torque overcomes the preload torque, the filter vane is forced to rotate around the pivot, rapidly increasing the angle of attack until it reaches the maximum angle limit, thereby actively changing its own hydrodynamic shape.

[0039] A moving magnetic ring 8 is fixedly connected to the top of the hollow shaft 401, and a fixed magnetic ring assembly 9 is provided on the bottom wall of the sealed top cover 2. The moving magnetic ring 8 and the fixed magnetic ring assembly 9 are arranged with the same pole facing each other. When the elastic suspension assembly 4 is in the equilibrium position or the first amplitude mode, the nonlinear radial magnetic repulsion force generated between the moving magnetic ring 8 and the fixed magnetic ring assembly 9 provides positive stiffness restoring force for the elastic suspension assembly 4. When the displacement of the elastic suspension assembly 4 exceeds the magnetic equilibrium critical point, the nonlinear radial magnetic repulsion force exhibits negative stiffness characteristics. The fixed magnetic ring assembly 9 includes an adjusting screw 901. The top end of the adjusting screw 901 passes through and is rotatably connected to the center of the sealing top cover 2, and is fixedly connected to the adjusting knob 902 above the sealing top cover 2. The bottom end of the adjusting screw 901 is rotatably connected to the center of the first support frame 903. The threaded end of the middle part of the adjusting screw 901 passes through and is threadedly connected to the second support frame 904. The top end of the first support frame 903 is fixedly connected to the bottom wall of the sealing top cover 2. The upper part of the second support frame 904 is embedded and slidably connected to the first support frame 903. The bottom end of the second support frame 904 is fixedly connected to a fixed magnetic ring 905. The fixed magnetic ring 905 is concentrically and coaxially suspended around the moving magnetic ring 8, and a preset radial air gap is maintained between the two.

[0040] The diaphragm pulse sewage discharge assembly 3 includes a sewage discharge chamber 301, which is sealed and fixedly connected to the opening at the bottom of the sewage collection hopper 102 via a flange, and a diaphragm 302 is provided between the two. The outer edge of the diaphragm 302 is embedded and fixedly connected between the sewage discharge chamber 301 and the opening at the bottom of the sewage collection hopper 102. A support plate 303 is fixedly and sealed to the middle of the diaphragm 302, and a connecting rod 304 is fixedly connected to the top of the support plate 303. The upper feed port of the sewage discharge chamber 301 is connected to the sewage discharge port 105 via a one-way valve 106. A discharge port is opened at the bottom of the sewage discharge chamber 301, and a rubber duckbill valve 305 is provided at the discharge port.

[0041] In order to achieve nonlinear control of the vibration mode of the elastic suspension component 4 and automatic removal of sediment at the bottom, the device integrates a magnetic stiffness adjustment mechanism and a diaphragm pulse sewage discharge component 3 coupled with vibration at the top and bottom of the hollow shaft 401, respectively. The two form a rigid mechanical linkage system through the central shaft.

[0042] The magnetic stiffness adjustment mechanism is located on the top inner side of the housing assembly 1. This mechanism includes a moving magnetic ring 8 fixedly fitted onto the top end of the hollow shaft 401, and a fixed magnetic ring assembly 9 fixedly installed on the inner wall of the top of the housing assembly 1 or at the center of the sealed top cover 2. Both the moving magnetic ring 8 and the fixed magnetic ring assembly 9 are made of high-performance permanent magnet materials (such as neodymium iron boron), and they are arranged in a concentric ring shape. In terms of pole configuration, the outer circumferential surface of the moving magnetic ring and the inner circumferential surface of the fixed magnetic ring assembly are set to be opposite each other with the same polarity (e.g., N pole facing N pole, or S pole facing S pole), thereby forming a radial magnetic repulsion field between them.

[0043] This magnetic mechanism adjusts the equivalent stiffness of the system through the nonlinear characteristics of the magnetic field force. When the hollow shaft 401 is in equilibrium or undergoes a small displacement, the radial magnetic repulsion force exhibits a positive stiffness restoring force, meaning it tends to push the hollow shaft 401 back to its geometric center, which helps maintain the stability of small-amplitude vibrations in the initial stage of filtration. However, when the hollow shaft 401 undergoes a large lateral or tilting displacement due to the large resistance of the fluid and crosses the preset magnetic equilibrium critical point, the direction of the horizontal component of the magnetic repulsion force changes or the nature of the force reverses, and the system instantaneously exhibits negative stiffness characteristics. This negative stiffness effect offsets part of the structural elastic stiffness, significantly reducing the natural frequency of the system, making it easier for fluid energy to excite the elastic suspension component 4 to generate large-amplitude low-frequency oscillations.

[0044] The stationary magnetic ring assembly 9, as the stationary end assembly that generates nonlinear restoring force, is concentrically and coaxially suspended around the moving magnetic ring 8, with a preset radial air gap maintained between them.

[0045] The fixed magnetic ring assembly 9 is not directly fixed to the bottom wall of the sealed top cover 2, but is installed below the sealed top cover 2 via an adjustable lifting structure. This lifting structure is made of non-magnetic material (such as austenitic stainless steel or high-strength engineering plastic) to prevent magnetic leakage from interfering with the magnetic field distribution. The main body of the fixed magnetic ring assembly 9 is composed of several high-performance neodymium iron boron arc-shaped permanent magnets, or it can directly use a radially oriented magnetic ring that is magnetized as a whole. Its inner circumferential surface is precision ground to ensure the uniformity of the air gap magnetic field.

[0046] By rotating the adjusting knob 902 located outside the sealed top cover 2, the adjusting screw 901 is driven to displace the support frame 904 in the vertical direction, thereby changing the axial overlap area between the fixed magnetic ring 905 and the moving magnetic ring 8. When the overlap area increases, the magnetic repulsion and negative stiffness effect are enhanced, the device becomes more sensitive to clogging, and the cleaning mode is triggered more easily; conversely, when the overlap area decreases, the system is more stable and the single filtration cycle is extended. This design gives the device the function of setting the critical resistance threshold for the transition from the stable filtration mode to the resonant cleaning mode, so as to adapt to the operating conditions under different breeding densities and dirt particle sizes.

[0047] At the bottom of the device, a diaphragm pulse drainage assembly 3 is installed to utilize the mechanical energy generated by the aforementioned large-amplitude oscillations. This assembly includes a drainage chamber 301, which is directly integrated into the opening at the bottom of the collection hopper 102. The bottom connecting rod 304 of the hollow shaft 401 passes through the aforementioned bellows 402 and flow stabilizer 7, extends downwards, and achieves a rigid sealing connection with the central area of ​​a highly elastic circular diaphragm 302 via a flange and nut. The edge area of ​​the diaphragm 302 is tightly pressed between the flange at the bottom of the collection hopper 102 and the upper edge of the drainage chamber 301, serving not only as a seal at the bottom of the device but also as a movable boundary of the pumping system.

[0048] The drain chamber 301, located below the diaphragm 302, is a hemispherical or conical metal cavity with a fixed volume. To control the unidirectional flow of the fluid, a precision-designed one-way valve assembly is integrated into the diaphragm 302. The one-way valve 106 at the inlet is located above the side wall of the drain chamber 301 and contains a spherical valve core. It is configured to allow concentrated fluid from the collection hopper 102 to enter the drain chamber 301 only under negative pressure, preventing backflow.

[0049] In this embodiment, a rubber duckbill valve 305 structure is used at the discharge port. This rubber duckbill valve 305 utilizes the elastic memory properties of rubber material, remaining closed in its natural state; when squeezed by internal fluid pressure, its duckbill-shaped opening opens to discharge the fluid; when the external back pressure is higher than the internal pressure, the duckbill-shaped opening closes tightly to prevent backflow. The straight-through flow channel design of the rubber duckbill valve 305 can effectively pass through sludge with a high solids content, avoiding the risk of traditional valves being easily jammed by particles.

[0050] This structural layout establishes a rigorous physical linkage logic: when the elastic suspension assembly 4 undergoes a large axial swing motion in cleaning mode, the up-and-down reciprocating motion of its shaft end is directly converted into the periodic deformation of the diaphragm 302. Specifically, when the central shaft moves downward, it forcibly presses down the diaphragm, causing the volume of the drain chamber 301 to decrease and the pressure inside the chamber to rise sharply. The one-way valve 106 closes under the action of pressure difference, while the rubber duckbill valve 305 is opened, forcefully discharging the high-concentration sludge accumulated in the drain chamber 301. When the hollow shaft 401 rebounds upward under the action of magnetic force and buoyancy, it causes the diaphragm 302 to arch upward, increasing the volume of the drain chamber 301 and creating a momentary negative pressure state. The duckbill valve closes, and the one-way valve 106 opens, sucking the newly settled sludge from the bottom of the sludge collection hopper 102 into the chamber. This cycle achieves the synchronous cleaning of the filter wing plate 5 and the sludge discharge.

[0051] In summary, in this embodiment, the operation of the device does not rely on external command control, but is based on changes in hydrodynamic load, automatically switching between a "stable filtration mode" and a "resonance cleaning and sewage discharge mode" through physical coupling between various mechanical components. This process follows a strict physical and mechanical mechanism and is divided into four continuous dynamic stages.

[0052] In the initial stable filtration stage, circulating water enters the housing assembly 1 through the tangential inlet 103 and the Venturi constrictor 6, where it forms a swirling flow at the bottom to pre-separate large particles of impurities. It then transforms into an upward flow passing through the filter vanes 5. During this stage, the fluid penetration resistance is low because the microporous filter media on the surface of the filter vanes 5 is not yet clogged by dirt. The torque generated by the fluid drag force acting on the aerodynamic center of the filter vanes 5 is less than the preset preload torque of the torsion spring, thus confining the filter vanes 5 to an initial small angle of attack position. At this time, the fluid exhibits an adhering laminar flow state on the vane surface, and the drag coefficient remains at a low level. Simultaneously, the elastic suspension assembly 4 is constrained by the magnetic repulsion of the top magnetic variable stiffness adjustment mechanism and is in the positive stiffness balance region. Under the weak Karman vortex street effect generated by the fluid flowing through the vanes, the elastic suspension assembly 4 only produces high-frequency, micro-amplitude vibrations. These micro-amplitude vibrations are insufficient to open the bottom rubber duckbill valve 305, but they effectively prevent fine particles from bridging and clogging the filter pores and promote the exchange of substances between the biofilm and the water.

[0053] As the filtration process continues, suspended particles in the water gradually accumulate on the filter media surface, forming a dense filter cake. This leads to a significant decrease in the filter media's permeability, and the pressure resistance of the fluid flowing through the filter vane 5 increases exponentially. When this resistance accumulates to a critical trigger stage, the fluid resistance acting on the aerodynamic center of the filter vane 5 overcomes the preload of the torsion spring through the torsional torque generated by the eccentricity, forcing the filter vane 5 to rotate around the hinge pin, causing its angle of attack to increase rapidly. At the same time, the increased fluid resistance drives the elastic suspension assembly 4 to displace in the horizontal and vertical directions. When this displacement exceeds the magnetic equilibrium critical point of the top magnetic variable stiffness adjustment mechanism, the nature of the magnetic repulsion changes abruptly, and the system stiffness characteristic flips from positive stiffness to negative stiffness, greatly reducing the motion restraint force of the hollow shaft 401 and creating the mechanical conditions for large-amplitude oscillations.

[0054] When the rotation angle of filter vane 5 reaches the critical stall angle, the system enters the resonant cleaning and sludge discharge stage. The large angle of attack causes severe boundary layer separation on the back surface of filter vane 5, resulting in dynamic stall and the generation of high-energy periodic shedding vortices. Under the combined influence of the negative stiffness environment and the stall flow field, the central elastic suspension assembly experiences significant divergent flutter. This intense vibration generates powerful inertial acceleration and fluid shear force, instantly disintegrating and detaching the filter cake and aging biofilm adhering to the filter media surface.

[0055] Meanwhile, the axial heave motion generated by the elastic suspension assembly 4 during flutter is directly transmitted to the diaphragm 302 at the bottom via the connecting rod 304. During the downward stroke of the hollow shaft 401, the enormous inertial force forces the elastic diaphragm 302 to deform downward, compressing the discharge chamber 301. The rapidly increasing pressure inside the chamber forces the one-way valve 106 to close and the rubber duckbill valve 305 to open, pulsatingly discharging the high-concentration sludge pre-stored in the chamber. During the upward rebound stroke of the hollow shaft 401, the diaphragm 302 is lifted and reset, creating a momentary negative pressure in the discharge chamber 301. The rubber duckbill valve 305 closes, and the one-way valve 106 opens, drawing in the newly settled sludge from the bottom of the collection hopper 102 and the dirt that has just been shaken off and settled from the filter wing plate 5 into the discharge chamber 301, completing one complete discharge cycle.

[0056] After the contaminants are removed and discharged, the device enters the self-resetting phase. As the permeability of the filter media surface is restored, the fluid resistance acting on the filter vanes 5 drops sharply. The restoring torque of the torsion spring regains dominance, pulling the filter vanes 5 back to their initial streamlined state with a small angle of attack. Simultaneously, as the external load is unloaded, the magnetic repulsion of the top magnetic variable stiffness adjustment mechanism pushes the elastic suspension assembly 4 back to its geometrically central positive stiffness equilibrium position. The bottom diaphragm 302 stops its large-amplitude pumping action, and the device returns to a stable filtration state with high-frequency, micro-amplitude vibrations, awaiting the next clogging cycle. This entire process repeats continuously, achieving fully automated, unattended operation driven entirely by fluid energy.

[0057] 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 alterations 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 water circulation and purification device for aquaculture, comprising a shell assembly (1), characterized in that, The housing assembly (1) is provided with an inlet (103), an outlet (104), and a drain (105). A diaphragm pulse drain assembly (3) is provided at the bottom of the housing assembly (1). The drain (105) is connected to the inlet of the diaphragm pulse drain assembly (3) through a one-way valve (106). An elastic suspension assembly (4) is provided inside the housing assembly (1). A filter assembly is connected to the outside of the elastic suspension assembly (4). The elastic suspension assembly (4) is suspended along the axial direction of the housing assembly (1) and vibrates under the impact of water flow. The vibration state generated by the elastic suspension assembly (4) includes a first amplitude mode and a second amplitude mode. When the fluid resistance acting on the filter assembly... When the force increases to a critical threshold due to the trapping of dirt, the vibration state of the elastic suspension assembly (4) is triggered to switch from the first amplitude mode to the second amplitude mode, wherein the amplitude of the second amplitude mode is greater than that of the first amplitude mode. The vibration inertial force in the second amplitude mode is used to remove dirt attached to the surface of the filter assembly. The elastic suspension assembly (4) is coupled with the drive part of the diaphragm pulse drainage assembly (3). The axial reciprocating motion of the elastic suspension assembly (4) in the second amplitude mode directly drives the drive part of the diaphragm pulse drainage assembly (3) to run, thereby changing the internal volume of the diaphragm pulse drainage assembly (3) so that the diaphragm pulse drainage assembly (3) sucks in the dirt at the bottom of the housing assembly (1) and discharges it.

2. The aquaculture water circulation and purification device according to claim 1, characterized in that, The housing assembly (1) includes a cylindrical body (101) located in the upper middle part, and an inverted conical sludge collection hopper (102) integrally formed with the body (101) and located at its bottom. A removable sealing top cover (2) is provided on the top of the body (101), and an automatic air vent valve (201) is provided on the sealing top cover (2) to discharge the air accumulated on the top of the body (101). The water inlet (103) is opened at the bottom of the body (101) near the bottom of the body (101). At the junction of the inlet (103) and the sludge collection hopper (102), the inlet (103) is connected to the output pipe of the circulating water pump. The axial direction of the inlet (103) is tangential to the cross-section of the cylinder (101), so that the sewage enters perpendicular to the radius of the cylinder (101) and cuts into the inner wall of the cylinder (101). A Venturi constriction tube (6) is also provided between the inlet (103) and the output pipe of the circulating water pump to accelerate the fluid and form a vortex at the bottom of the shell assembly (1).

3. The aquaculture water circulation and purification device according to claim 2, characterized in that, The inner wall of the top of the cylindrical body (101) is provided with an annular overflow weir (107), and the outlet (104) is opened at the top of the cylindrical body (101) and is connected to the annular overflow weir (107).

4. The aquaculture water circulation and purification device according to claim 2, characterized in that, The diaphragm pulse sewage discharge assembly (3) includes a sewage discharge chamber (301), which is sealed and fixedly connected to the opening at the bottom of the sewage collection hopper (102) by a flange, and a diaphragm (302) is provided between the two. The outer edge of the diaphragm (302) is embedded and fixedly connected between the sewage discharge chamber (301) and the opening at the bottom of the sewage collection hopper (102). A support plate (303) is fixedly and sealed in the middle of the diaphragm (302), and a connecting rod (304) is fixedly connected to the top of the support plate (303). The upper feed port of the sewage discharge chamber (301) is connected to the sewage discharge port (105) through a one-way valve (106). A discharge port is opened at the bottom of the sewage discharge chamber (301), and a rubber duckbill valve (305) is provided at the discharge port.

5. The aquaculture water circulation and purification device according to claim 4, characterized in that, The elastic suspension assembly (4) includes a hollow shaft (401), the bottom end of which is fixedly connected to a bellows (402) for elastic support, the top end of which is fixedly connected to a flow stabilizer (7), the outer wall of which is fixedly connected to the inner wall of the sludge collection hopper (102), the top end of which is through the flow stabilizer (7) and inside the bellows (402), and the top end of which is fixedly connected to the bottom end of the hollow shaft (401).

6. The aquaculture water recycling and purification device according to claim 5, characterized in that, A moving magnetic ring (8) is fixedly connected to the top of the hollow shaft (401), and a fixed magnetic ring assembly (9) is provided on the bottom wall of the sealed top cover (2). The moving magnetic ring (8) and the fixed magnetic ring assembly (9) are arranged opposite each other with the same pole. When the elastic suspension assembly (4) is in the equilibrium position or the first amplitude mode, the nonlinear radial magnetic repulsion force generated between the moving magnetic ring (8) and the fixed magnetic ring assembly (9) provides positive stiffness restoring force for the elastic suspension assembly (4). When the displacement of the elastic suspension assembly (4) exceeds the magnetic equilibrium critical point, the nonlinear radial magnetic repulsion force exhibits negative stiffness characteristics.

7. The aquaculture water circulation and purification device according to claim 6, characterized in that, The fixed magnetic ring assembly (9) includes an adjusting screw (901), the top end of which is rotatably connected to the center of the sealing top cover (2) and fixedly connected to the adjusting knob (902) above the sealing top cover (2). The bottom end of the adjusting screw (901) is rotatably connected to the center of the first support frame (903). The threaded end of the middle part of the adjusting screw (901) is threadedly connected to the second support frame (904). The top end of the first support frame (903) is fixedly connected to the bottom wall of the sealing top cover (2). The upper part of the second support frame (904) is embedded and slidably connected to the first support frame (903). The bottom end of the second support frame (904) is fixedly connected to a fixed magnetic ring (905). The fixed magnetic ring (905) is concentrically and coaxially suspended around the moving magnetic ring (8), and a preset radial air gap is maintained between the two.

8. The aquaculture water recycling and purification device according to claim 5, characterized in that, The filter assembly includes multiple filter blades (5) arranged in a multi-layered staggered spiral array along the hollow shaft (401). Adjacent filter blades (5) have a preset phase offset angle in the circumferential direction. The filter blades (5) have an asymmetrical airfoil cross section. The root of the filter blades (5) is hinged to a hinge seat fixed to the outer wall of the hollow shaft (401). An elastic reset element is also provided between the hinge seat and the root of the filter blades (5) to provide a preload force to keep the filter blades (5) in the initial angle of attack position. When the torque generated by the fluid resistance acting on the filter blades (5) is greater than the preload torque of the elastic reset element, the filter blades (5) rotate around the pin of the hinge seat to increase the angle of attack, thereby inducing stall flutter.

9. The aquaculture water circulation and purification device according to claim 8, characterized in that, The filter wing plate (5) includes a rigid support frame and a flexible microporous filter membrane skin tightly wrapped around the rigid support frame. The rigid support frame defines the outer contour of the filter wing plate (5) and multiple hollow windows inside. The flexible microporous filter membrane skin covers the hollow windows to form an actual filter surface. The root of the filter wing plate (5) is also provided with a flexible sealing skirt, which covers the gap of the hinge seat pin.

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