Self-adaptive ocean micro-plastic trawl net

Abstract

The present application relates to the technical field of ocean micro-plastic trawl, and specifically discloses a self-adaptive ocean micro-plastic trawl, which comprises a filtering device and a self-adaptive adjusting device.The self-adaptive device comprises a trawl frame, a floating tube and a sliding hammer.The trawl frame is used for mounting the filtering device and constitutes a netting tool with a net opening.The floating tube comprises a first floating tube and a second floating tube which are symmetrically installed on the left and right sides of the trawl frame.The first floating tube and the second floating tube can slide on the two sides of the trawl frame in parallel, and the sliding direction is parallel to the plane where the net opening is located.The sliding hammer comprises a first sliding hammer and a second sliding hammer which are symmetrically installed on the left and right sides of the trawl frame.The first sliding hammer can slide in parallel relative to the first floating tube, and the second sliding hammer can slide in parallel relative to the second floating tube.The floating tube and the sliding hammer slide to either end under the action of buoyancy and gravity to achieve dynamic balance, thereby realizing the functions of 'throwing without direction and self-correcting when entering water'.

Description

Technical Field

[0001] This invention relates to the technical field of marine microplastic trawls, and specifically discloses an adaptive marine microplastic trawl. Background Technology

[0002] Marine microplastic trawls are specialized sampling tools used to collect microplastic particles (less than 5 mm in diameter) from water bodies. They are widely used in marine environmental monitoring, microplastic pollution assessment, and ecotoxicological research. Currently, the most common method for surface microplastic sampling is the trawl method. This involves using a ship to tow a net, filtering a certain volume of seawater through the net and trapping microplastics inside the net or in a collector. Laboratory analysis then yields data on the type, particle size distribution, and concentration of microplastics. Due to its large sampling area and high representativeness, the trawl method has become one of the standard methods for marine microplastic surveys.

[0003] Depending on the water layer sampled, trawls can be divided into surface trawls (typically collecting samples from the 0-50 cm depth below the sea surface) and deep-water trawls. Commonly used surface trawls in current technology mainly include Müller nets and plankton nets (such as WP2 nets). Müller nets typically use nylon or polyester fiber netting with a pore size of 333 μm, primarily used to capture large microplastics with a particle size of 1-5 mm. Their openings are mostly rectangular or circular, and by towing, they cover a large area of ​​surface water, making them suitable for quickly assessing the distribution of microplastic pollution in open sea areas. Plankton nets (such as WP2 nets) have even smaller pore sizes (50-200 μm), capable of capturing small microplastics (1 μm-1 mm) and some plankton, and are often used for fine-grained particle size classification sampling. These nets are usually used in conjunction with auxiliary equipment such as current meters and stainless steel sample vials to calculate the volume of the sampled water and avoid sample contamination.

[0004] However, existing marine microplastic trawls still have significant shortcomings in practical applications. Mueller nets typically provide buoyancy through their side "wings," ensuring the net opening is just below the water surface. Sampling requires strict control over the net opening's orientation; the vertical direction cannot be reversed (see [reference]). Figure 1 When deploying the net from the ship, operators must confirm the net's orientation. If the net is upside down, sampling will fail, requiring the net to be retrieved by crane, cleaned, and deployed again. In rough seas, this operation is not only extremely difficult and risky but also severely reduces sampling efficiency. Therefore, a new type of marine microplastic trawl is urgently needed to address the shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an adaptive marine microplastic trawl net.

[0006] This invention discloses an adaptive marine microplastic trawl net, which adopts the following technical solution: An adaptive marine microplastic trawl net includes a filtration device and an adaptive adjustment device; the adaptive device includes: A trawler frame is used to install a filtration device and form a net with mesh openings; The floats include a first float and a second float symmetrically installed on the left and right sides of the trawl frame. The first float and the second float can slide parallel to each other on both sides of the trawl frame, and their sliding direction is parallel to the plane where the net opening is located. The sliding hammer includes a first sliding hammer and a second sliding hammer symmetrically installed on the left and right sides of the trawl frame. The first sliding hammer can slide parallel to the first buoy, and the second sliding hammer can slide parallel to the second buoy. The buoy and the sliding hammer slide to either end under the action of buoyancy and gravity to achieve dynamic equilibrium.

[0007] Preferably, the trawl frame includes a front frame, a rear frame, and a connecting rod for connecting the front frame and the rear frame. An installation frame is formed between the left and right sides of the front frame and the rear frame for sliding connection between the float and the sliding hammer. The filter device is connected to the rear frame.

[0008] Preferably, each of the two mounting frames is provided with parallel sliding shafts for the counterweights. The counterweights are cylindrical structures with both ends open, and the two counterweights are mounted on the corresponding sliding shafts for the counterweights.

[0009] Preferably, the two mounting frames are respectively provided with parallel float sliding shafts, and the float sliding shafts are equipped with pulley groups that slide along their axial direction, and the two floats are mounted on the corresponding pulley groups.

[0010] Preferably, the pontoon includes a mounting section and buoy sections symmetrically connected in front of and behind the mounting section, and the pulley assembly is connected to the mounting section.

[0011] Preferably, it also includes a counterweight cone and a traction cable, the traction cable being connected to the trawl frame, the counterweight cone being connected to the traction cable, and the counterweight cone and the traction cable cooperating to control the angle of the trawl frame opening.

[0012] Preferably, the counterweight cone has a cone-shaped head and a plurality of radially extending stabilizing tail fins at its tail.

[0013] Preferably, the float and / or sliding hammer are detachably mounted on the trawl frame.

[0014] Preferably, a flow meter is installed on the trawl frame.

[0015] Preferably, the filtration device includes a mesh and a collection component, wherein the head of the mesh is connected to the trawl frame and the collection component is connected to the tail of the mesh.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: This invention utilizes symmetrically sliding buoys and sliding hammers mounted on both sides of the trawl net frame. By leveraging the balance between the buoyancy of the buoys and the gravity of the sliding hammers, the buoys automatically slide parallel to the net opening plane. Regardless of the trawl net's orientation when deployed (opening upwards, downwards, or tilted), the relative movement of the buoys and sliding hammers upon entry forces the net opening to automatically rotate to face the current and be positioned at a preset water surface location, achieving "directionless deployment and self-correction upon entry." This design relies entirely on the passive balance of gravity and buoyancy, requiring no motors, sensors, or active control systems. It completely eliminates the operational risks and efficiency losses associated with traditional Müller nets, which require re-washing and re-deployment due to net inversion, significantly reducing reliance on human experience and weather conditions for marine sampling, and greatly improving sampling success rate and data reliability. Attached Figure Description

[0017] Figure 1 A schematic diagram showing the correct and inverted orientations of a trawl net in existing technology; Figure 2 This is a schematic diagram of the adaptive adjustment device for trawl nets according to the present invention; Figure 3 This is a schematic diagram of the adaptive adjustment device for trawl nets of the present invention from another angle. Figure 4 This is a schematic diagram of the overall structure of the trawl net of the present invention.

[0018] Explanation of icon numbers: 1. Trawl frame; 11. Float sliding shaft; 12. Counterweight sliding shaft; 2. Float; 21. Mounting part; 211. Pulley block; 22. Buoy part; 3. Sliding hammer; 4. Netting; 5. Collection part; 6. Flow meter; 7. Counterweight cone; 8. Traction cable. Detailed Implementation

[0019] To make the above-mentioned objects, features and advantages of the invention more apparent and understandable, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] An adaptive marine microplastic trawl, referring to Figure 2-4 The system includes a filtration device and an adaptive adjustment device. The filtration device includes a mesh 4 and a collection component 5 connected to the tail of the mesh 4. The mesh 4 is responsible for trapping microplastic particles in the water, and the tail collection component 5 can collect and store the trapped samples for subsequent laboratory analysis. Preferably, the mesh 4 is made of silk, which does not release its own plastic particles, thus solving the secondary pollution problem caused by traditional PP mesh and ensuring the authenticity of sample data.

[0021] Reference Figure 1-2The adaptive device of this scheme includes a trawl frame 1, floats 2, and sliding hammers 3. The trawl frame 1 is used to install the filter device and form a net with a mesh opening. The floats 2 include a first float and a second float symmetrically installed on the left and right sides of the trawl frame 1. The first float and the second float can slide parallel to each other on both sides of the trawl frame 1, and their sliding direction is parallel to the plane where the mesh opening is located. The sliding hammers 3 include a first sliding hammer and a second sliding hammer symmetrically installed on the left and right sides of the trawl frame 1. The first sliding hammer can slide parallel to the first float, and the second sliding hammer can slide parallel to the second float. The floats 2 and the sliding hammers 3 slide towards either end under the action of buoyancy and gravity to achieve dynamic equilibrium. When the hull rises or waves cause the net to tilt, the relative positions of the float 2 and the sliding hammer 3 will automatically adjust, so that the trawl net can automatically adjust to the correct posture. The entire adjustment process does not require any motors, sensors or active control systems. It relies entirely on the passive balance of gravity and buoyancy to achieve "gravity self-adaptation". This purely mechanical structure not only greatly improves the reliability of marine sampling, but also avoids the risk of electronic component failure in the marine environment. It provides a low-cost, maintenance-free technical solution for long-term monitoring of microplastics in complex sea conditions.

[0022] The adaptive device designed in this scheme has an ingenious structure. Its working principle is as follows: after the trawl net enters the water, the float 2 tends to slide upward (towards the sea surface) due to its own buoyancy, while the sliding hammer 3 tends to slide downward (towards the depth of the sea) due to its own gravity. The two automatically adjust their positions along a sliding axis parallel to the plane of the net opening until buoyancy and gravity reach dynamic equilibrium. During this process, regardless of the initial attitude of the trawl net frame 1 at the time of deployment, the relative movement of the float 2 and the sliding hammer 3 will force the net opening to automatically face the horizontal direction (i.e., the plane of the net opening is perpendicular to the direction of gravity), thereby ensuring that the sampling net opening is always in the correct attitude facing the current and that the net opening is at the preset water surface position. Compared to existing trawlers such as Mueller nets, which require strict distinction between up and down directions and necessitate re-washing and re-casting if the net is inverted during deployment, this invention cleverly utilizes the self-balancing properties of gravity and buoyancy. This eliminates the need to distinguish between up and down directions or observe whether the net opening is correctly positioned when the net is cast from the ship into the sea. Even if the net opening is downward or enters the water at any angle, the float 2 and sliding hammer 3 will automatically slide and correct themselves after entry, ensuring the net opening always adjusts to the correct upward orientation. This design completely eliminates the risk of sampling failure due to net inversion under rough sea conditions, significantly reduces the technical requirements and workload for operators, and substantially improves sampling success rate and data reliability.

[0023] Specifically, the trawl frame 1 includes a front frame, a rear frame, and connecting rods for connecting the front and rear frames. Both the front and rear frames are rectangular frames with an aspect ratio of approximately 2:1. A mounting frame is formed between the left and right sides of the front and rear frames for sliding connection of the floats 2 and sliding hammers 3. The sliding direction of the floats 2 and sliding hammers 3 is the width direction of the frame. The head of the net 4 is connected to the rear frame. This frame structure provides independent sliding space for the floats 2 and sliding hammers 3, while ensuring a firm connection between the filter device and the frame. This helps maintain the stable shape of the net 4 during dynamic equilibrium and reduces the impact deformation of the water flow on the net opening.

[0024] Reference Figure 2-3 Each of the two mounting frames has a parallel float sliding shaft 11, and a pulley assembly 211 that slides along its axial direction is mounted on the float sliding shaft 11. The two floats 2 are mounted on the corresponding pulley assemblies 211. The pulley assembly 211 can significantly reduce the frictional resistance when the floats 2 slide, allowing the floats 2 to initiate sliding under small changes in buoyancy, improving the sensitivity of adaptive adjustment, and avoiding adjustment lag caused by friction jamming, ensuring that the net opening always maintains a stable attitude under complex sea conditions.

[0025] As a preferred embodiment, the float 2 includes a mounting section 21 and buoy sections 22 symmetrically connected to the front and rear of the mounting section 21. A pulley block 211 is connected to the mounting section 21. The symmetrical buoy section 22 structure ensures that the float 2 experiences uniform force during sliding, preventing the float 2 from deflecting or jamming due to excessive buoyancy on one side. Simultaneously, it increases the buoyancy application area, allowing the float 2 to obtain sufficient lifting force at the sea surface, ensuring the trawl net can be stably maintained at the target sampling water layer.

[0026] Reference Figure 2-3 Each of the two mounting frames has parallel sliding shafts 12 for the counterweights. The counterweights are cylindrical structures with two ends that pass through them, and the two counterweights are mounted on the corresponding sliding shafts 12. Guided by the sliding shafts 12, the sliding hammers 3 can move smoothly along the axial direction, and the cylindrical structure can evenly distribute the gravity, avoiding jamming caused by uneven loading. This ensures the sensitivity and accuracy of gravity self-adjustment, allowing the net to respond quickly and restore balance when the waves are rising and falling.

[0027] As a preferred embodiment, in this embodiment, each of the left and right mounting frames is provided with two buoy sliding shafts 11 and one counterweight sliding shaft 12. The two buoy sliding shafts 11 are located on the front and rear sides of the counterweight sliding shaft 12, respectively. The symmetrical arrangement of the buoy sliding shafts 11 can make the sliding load of the buoy 2 and the sliding hammer 3 evenly distributed along the towing direction, so that the front and rear orientation of the mounting frame is more balanced, avoiding the bending or jamming of the sliding shaft caused by uneven front and rear force, which helps to reduce the impact of tilted force on the dynamic adjustment response speed, and further improves the adaptive dynamic adjustment effect of the net when the waves rise and fall or the ship speed changes.

[0028] Furthermore, in this embodiment, both the float 2 and the sliding hammer 3 are detachably mounted on the trawl frame 1. This detachable design allows users to quickly replace the float 2 or sliding hammer 3 with different buoyancy or weights according to different sampling water depths, flow velocities, or microplastic particle size requirements. Individual replacements are also possible after component wear, reducing maintenance costs and improving the applicability and service life of the device.

[0029] As a preferred option, a flow meter 6 is installed on the trawl frame 1. The flow meter 6 can record the total volume of water flowing through the net 4 in real time. Combined with the number of microplastic particles collected, the concentration of microplastics in a unit volume of water can be accurately calculated. This is a key quantitative indicator for assessing the degree of pollution in the area, avoiding data deviations caused by inaccurate flow velocity estimation.

[0030] In addition to addressing the trawl net's attitude using the aforementioned methods, this solution also considers the dynamic deviation of the net opening angle during towing. In microplastic and plankton sampling, the stability of the net's attitude directly affects data accuracy, and "net opening tilting" is the most common source of deviation in towed sampling. Essentially, this is caused by an imbalance between the water flow impact, cable tension, and the net's own weight, leading to net opening tilting. This results in a shallower actual sampling depth, a smaller filtered water volume, and even deviation from the target sampling layer. To address this issue, as a preferred embodiment, this solution also includes a counterweight cone 7 and a traction cable 8. The traction cable 8 is connected to the front frame, and the counterweight cone 7 is connected to the traction cable 8. The counterweight cone 7 and the traction cable 8 work together to control the net opening angle of the trawl net frame 1, stabilizing the sampling system, preventing excessive drift, and assisting in locating the sampling area. Specifically, the counterweight cone 7 in this solution has a conical head and several radially extending stabilizing tail fins. The conical head reduces water resistance, keeping the counterweight cone 7 stable during towing. The tail fin acts like arrow fletching, preventing the counterweight cone 7 from rotating or swinging in the water, thereby further stabilizing the cable angle and ensuring that the net mouth attitude does not shift for a long time. It is especially suitable for high-speed towing or strong current environments.

[0031] By designing a sliding buoy 2, a sliding hammer 3, and a structure that complements the counterweight cone 7 and traction cable 8, a collaborative working system of "automatic orientation upon entry into the water + anti-interference during towing" is achieved. The adaptive adjustment device addresses the initial attitude uncertainty of the net upon entry into the water. Regardless of the net's orientation when cast into the sea, the buoy 2 and sliding hammer 3 automatically slide to force the net opening to face the current direction and be in a preset position, completely eliminating the operational risks associated with traditional Müller nets, which require distinguishing between up and down and restarting if a throw is incorrect. The counterweight cone 7 and traction cable 8 address the issue of the net opening tilting upwards during towing. Additional gravity lowers the cable angle, preventing the net opening from tilting upwards due to current impact or changes in boat speed. The organic combination of these two components ensures that the net opening "quickly adjusts from any initial state to the correct orientation," further enhancing its performance. The counterweight cone 7 ensures that the net opening "maintains a stable correct orientation under towing interference," jointly guaranteeing that the net always faces the current in the optimal posture. When the adaptive adjustment device is used alone, the success rate of water entry correction is close to 100%, but a slight upward movement may still occur during high-speed towing. When using a traditional trawl net structure with the counterweight cone 7, although upward movement can be suppressed, it is completely ineffective if the net is initially upside down. When the two are used together, not only is the convenient operation of "no direction of casting and self-correction upon water entry" achieved, but the pitch angle fluctuation of the net opening under high-speed towing or large wave conditions is also significantly reduced, significantly reducing sampling volume error, and truly achieving high robustness and high precision sampling under complex sea conditions.

[0032] The technical solution provided by the invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the invention. Therefore, the content of this specification should not be construed as a limitation of the invention.

Claims

1. An adaptive marine microplastic trawl net, characterized in that, It includes a filtration device and an adaptive adjustment device; the adaptive device includes: A trawler frame is used to install a filtration device and form a net with mesh openings; The floats include a first float and a second float symmetrically installed on the left and right sides of the trawl frame. The first float and the second float can slide parallel to each other on both sides of the trawl frame, and their sliding direction is parallel to the plane where the net opening is located. The sliding hammer includes a first sliding hammer and a second sliding hammer symmetrically installed on the left and right sides of the trawl frame. The first sliding hammer can slide parallel to the first buoy, and the second sliding hammer can slide parallel to the second buoy. The buoy and the sliding hammer slide to either end under the action of buoyancy and gravity to achieve dynamic equilibrium.

2. The adaptive marine microplastic trawl net according to claim 1, characterized in that, The trawl frame includes a front frame, a rear frame, and a connecting rod for connecting the front frame and the rear frame. An installation frame is formed between the left and right sides of the front frame and the rear frame for the buoy and the sliding hammer to slide together. The filter device is connected to the rear frame.

3. The adaptive marine microplastic trawl net according to claim 2, characterized in that, The two mounting frames are respectively provided with parallel sliding shafts for the counterweights. The counterweights are cylindrical structures with both ends open, and the two counterweights are mounted on the corresponding sliding shafts for the counterweights.

4. The adaptive marine microplastic trawl net according to claim 3, characterized in that, The two mounting frames are respectively provided with parallel float sliding shafts, and the float sliding shafts are equipped with pulley groups that slide along their axial direction. The two floats are installed on the corresponding pulley groups.

5. The adaptive marine microplastic trawl net according to claim 4, characterized in that, The pontoon includes a mounting section and buoy sections symmetrically connected to the front and rear of the mounting section, and the pulley assembly is connected to the mounting section.

6. The adaptive marine microplastic trawl net according to claim 1, characterized in that, It also includes a counterweight cone and a traction cable. The traction cable is connected to the trawl frame, and the counterweight cone is connected to the traction cable. The counterweight cone and the traction cable work together to control the angle of the trawl frame opening.

7. The adaptive marine microplastic trawl net according to claim 6, characterized in that, The counterweight cone has a cone-shaped head and several radially extending stabilizing tail fins at its tail.

8. The adaptive marine microplastic trawl net according to any one of claims 1-8, characterized in that, The buoy and / or sliding hammer are detachably mounted on the trawl frame.

9. The adaptive marine microplastic trawl net according to any one of claims 1-8, characterized in that, A flow meter is installed on the trawler frame.

10. The adaptive marine microplastic trawl net according to any one of claims 1-8, characterized in that, The filtration device includes a mesh and a collection component. The head of the mesh is connected to the trawl frame, and the collection component is connected to the tail of the mesh.

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