A self-powered ocean current sensor with ultra-low flow rate measurement capability

Abstract

This invention discloses a self-powered ocean current sensor with ultra-low current velocity measurement capability, belonging to the field of marine environmental monitoring. The sensor includes a pressure-resistant sealed housing, a rotary drive unit, a magnetic coupling transmission unit, a triboelectric sensing unit, and a signal processing unit. The rotary drive unit rotates under the influence of the ocean current, and the torque is transmitted non-contactly to the internal triboelectric sensing unit via the magnetic coupling transmission unit. The triboelectric sensing unit adopts a rolling friction structure, utilizing triboelectric charging and electrostatic induction to generate an alternating electrical signal; the frequency of the output signal is linearly related to the current velocity. This invention requires no external power supply, can stably measure at ultra-low current velocities in the centimeter-per-second range, can withstand hydrostatic pressures of 126.5 MPa, and features a compact structure, self-powered operation, high sensitivity, and long-term stability, making it suitable for long-term autonomous observation in all ocean depth environments.

Description

Technical Field

[0001] This invention relates to the field of marine environmental monitoring technology, and more specifically to a self-powered ocean current sensor with ultra-low current velocity measurement capability. Background Technology

[0002] The ocean covers 71% of the Earth's surface and contains abundant energy and complex dynamic processes, making it a vital component of the Earth's climate system and ecological cycles. Deep-sea current field parameters (especially velocity and direction) are of significant scientific importance in revealing the dynamics of the Earth's interior, seafloor geological activity, material transport, and biological distribution patterns, forming a crucial foundation for understanding the evolution of the deep-sea environment and global climate change. However, in the 10,000-meter-deep ocean environment, due to extremely high hydrostatic pressure, increased water viscosity, and generally low flow velocities (typically below 1 cm / s), achieving high-precision, long-term stable monitoring of ultra-low-speed fluid motion remains a significant technical challenge.

[0003] In the prior art, mechanical current meters remain the most widely used measuring devices for deep-sea current field observation. For example, Chinese Patent Publication No. CN112345678A discloses a deep-sea current velocity measuring device based on a propeller structure, which uses the rotation of an impeller to drive a Hall sensor to output a current velocity signal. However, this device suffers from high start-up current velocity and insufficient sensitivity. In ultra-low current velocities (<1 cm / s), the output signal fluctuates greatly and the accuracy is unstable. Furthermore, due to the use of a mechanical bearing structure, it is prone to jamming and corrosion in high-pressure seawater, resulting in poor long-term reliability. Another Chinese Patent Publication No. CN113987524A discloses a mechanical current velocity sensor for deep-sea observation, which uses a gear transmission structure to achieve current velocity conversion and has a certain degree of adaptability to flow fields. However, its overall structure is complex, the manufacturing cost is high, and the pressure resistance of the packaging is limited, making it unsuitable for long-term deployment in deep-sea environments at depths of tens of thousands of meters.

[0004] In addition, existing mechanical and electromagnetic current meters generally rely on external power sources or batteries for power, and the power consumption of signal processing and data acquisition circuits is relatively high, making it difficult to achieve long-term unattended self-sustaining operation, which is not conducive to continuous observation and distributed deployment in deep-sea environments.

[0005] Therefore, there is an urgent need to develop a flow velocity sensor that can be self-powered, has a wide range, high sensitivity, and low power consumption in the full ocean depth environment, so as to support long-term autonomous observation and scientific exploration in the deep sea. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing mechanical current meters, such as complex structure, high starting flow velocity, poor pressure resistance, and inability to operate under self-powered conditions. It provides a self-powered current velocity sensor capable of detecting ultra-low current velocities, operating under self-powered conditions, and providing long-term stable observation in all ocean depth environments. Specifically, it includes the following features: 1) By employing a high-sensitivity triboelectric sensing structure, it effectively captures weak deep-sea flow information, achieving ultra-low current velocity detection; 2) Utilizing the principle of triboelectric nano-power generation, it integrates sensing and energy acquisition, eliminating dependence on external power sources and batteries, achieving self-powered operation, and meeting the needs of long-term unattended observation; 3) Through a double-sealing structure design of a titanium alloy shell and O-rings, it improves pressure resistance and environmental adaptability, ensuring long-term operation in deep-sea environments at depths of tens of thousands of meters; 4) By optimizing the friction layer material and electrode structure, it significantly improves measurement accuracy and system reliability.

[0007] The technical solution adopted by this invention to solve the technical problem is: a self-powered ocean current sensor with ultra-low current velocity measurement capability, the sensor comprising: Pressure-resistant sealed housing; A rotary drive unit is disposed outside the pressure-resistant sealed housing and is used to generate rotary motion when driven by fluid; A magnetic coupling transmission unit is disposed inside the pressure-resistant sealed housing and is used to transmit the torque of the rotary drive unit to the interior of the pressure-resistant sealed housing in a non-contact manner. A triboelectric sensing unit is disposed inside the pressure-resistant sealed housing and is used to generate an alternating electrical signal from the fluid kinetic energy transmitted by the magnetic coupling transmission unit through triboelectric effect and electrostatic induction. The signal processing unit, electrically connected to the triboelectric sensing unit, is used to process the alternating electrical signal to output information characterizing the flow velocity.

[0008] Furthermore, the triboelectric sensing unit adopts a rolling friction structure, including a friction layer assembly, at least one rolling element, and a rotating body; the friction layer assembly and the rolling element are both mounted on the rotating body, and the rotating body is driven to rotate by the magnetic coupling transmission unit; the surface of the rolling element is in contact with the outer surface of the friction layer assembly.

[0009] Furthermore, the rolling element is positioned and mounted on the rotating body; the rolling element continuously generates alternating charge transfer signals on the surface of the friction layer assembly through a combined motion of revolving with the rotating body and rotating on its own axis.

[0010] Furthermore, the friction layer assembly includes a negative friction material, several electrodes, and a flexible substrate; the electrodes are arranged in an arc-shaped, symmetrical pattern, with adjacent electrodes evenly distributed on the flexible substrate in an alternating manner to form an electrode layer; the negative friction material is fixed on the electrode layer; the flexible substrate side of the friction layer assembly is tightly fitted to the rotating body.

[0011] Furthermore, the thickness of the electrode is 0.08~0.12 mm, and the spacing between adjacent electrodes is 0.15~0.25 mm; the thickness of the negative friction material is 0.04~0.06 mm.

[0012] Furthermore, the triboelectric sensing unit is electrically connected to the energy storage unit, which stores the electrical energy generated by the triboelectric sensing unit and enables the sensor to be self-powered through rectification and voltage regulation circuits.

[0013] Furthermore, the transmission ratio of the magnetic coupling transmission unit is 8:1.

[0014] Furthermore, the frequency of the signal output by the signal processing unit is linearly related to the flow rate.

[0015] Furthermore, the pressure-resistant sealing housing includes a coupling housing, a sealing end cap, and a cylindrical housing; the pressure-resistant sealing housing is made of titanium alloy or polyether ether ketone (PEEK); the connections of the pressure-resistant sealing housing are all sealed by O-rings and epoxy encapsulation.

[0016] The beneficial effects of this invention are as follows: Compared with the prior art, the self-powered ocean current sensor with ultra-low flow velocity measurement capability provided by this invention has advantages such as compact structure, high sensitivity, and strong long-term stability. This sensor adopts a design combining magnetic coupling non-contact transmission with a flexible FPC triboelectric sensing unit, avoiding the leakage and failure problems caused by seal wear in traditional mechanical current meters. It achieves a fully sealed, high-pressure resistant structure, and can operate stably under hydrostatic pressures exceeding 100 MPa. The sensor utilizes ocean current energy to directly drive the triboelectric sensing unit for energy acquisition and signal output, achieving self-powered operation without an external power source, significantly reducing maintenance frequency and energy consumption. Through optimized design of the electrode structure, friction material, and transmission module, the device can maintain a high signal-to-noise ratio output even in ultra-low flow velocity environments at the centimeter-per-second level. The output signal frequency exhibits a highly linear relationship with the flow velocity, significantly improving measurement accuracy and response sensitivity. This sensor can achieve long-term autonomous observation in complex deep-sea environments such as strong corrosion, high pressure, and low flow velocities, providing a highly reliable new solution for deep-sea current field distribution monitoring and the construction of self-powered marine sensor networks. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the invented sensor.

[0018] Figure 2 This is a schematic diagram of the electrode arrangement in the friction layer assembly.

[0019] Figure 3 This is a schematic diagram illustrating the working principle of triboelectric sensing unit for generating electricity.

[0020] Figure 4 The figures show the current and voltage curves output by the present invention at different rotational speeds; where a is the current curve at different rotational speeds and b is the voltage curve at different rotational speeds.

[0021] Figure 5 The curves show the charging of different capacitors at 360 rpm according to the present invention.

[0022] Figure 6 This is the flow rate-frequency curve calibrated for this invention.

[0023] Figure 7 This is the pressure test data curve for this invention.

[0024] Figure 1 In the middle, 1-magnetic coupling transmission unit; 2-sealed end cap; 3-electronic compass; 4-cylindrical housing; 5-coupling housing; 6-signal processing unit; 7-friction layer assembly; 8-rolling element; 9-drive shaft; 10-rotation drive unit. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0026] It should be noted that all directional indications (such as upper, lower, outer, surface, side, etc.) in the specification and claims of this application are only used to explain the relative spatial positions and movements of the components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indications will also change accordingly. In addition, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0027] Figure 1 A schematic diagram of the structure of the self-powered ocean current sensor with ultra-low current velocity measurement capability proposed in this invention. Figure 1As shown, the sensor includes: a pressure-resistant sealed housing; a rotary drive unit 10 disposed outside the pressure-resistant sealed housing for generating rotational motion when driven by fluid; a magnetic coupling transmission unit 1 disposed inside the pressure-resistant sealed housing for non-contactly transmitting the torque of the rotary drive unit 10 to the interior of the pressure-resistant sealed housing; a triboelectric sensing unit disposed inside the pressure-resistant sealed housing for generating an alternating electrical signal from the fluid kinetic energy transmitted by the magnetic coupling transmission unit 1 through triboelectric effect and electrostatic induction; and a signal processing unit 6 electrically connected to the triboelectric sensing unit for processing the alternating electrical signal to output information characterizing the flow velocity.

[0028] The triboelectric sensing unit employs a rolling friction structure, comprising a friction layer assembly 7 and at least one rolling element 8. Both the friction layer assembly 7 and the rolling element 8 are mounted on a rotating body (such as a cylindrical aluminum alloy rotor), which is driven by the magnetic coupling transmission unit 1 to revolve around a central axis. The surface of the rolling element 8 contacts the outer surface of the friction layer assembly 7. Further, the rolling element is secured to the rotating body by high-precision bearings at both ends. During the rotation of the rotating body, the rolling element is driven to rotate autonomously by the frictional force of its contact surface with the friction layer assembly 7. Through the combined motion of revolving with the rotating body and its own rotation, the rolling element continuously generates alternating charge transfer signals on the surface of the friction layer assembly, thereby achieving flow velocity detection.

[0029] The friction layer assembly includes a negative friction material, several electrodes, and a flexible substrate. In this embodiment, the negative friction material is a 0.05 mm thick fluorinated ethylene propylene (FEP) film, which has excellent electronegativity and stable surface charge retention, making it a commonly used negative friction material in triboelectric nanogenerators (TENGs). The positive friction material is a 0.1 mm thick copper foil, serving as both the positive and negative electrodes. It exhibits good conductivity, wear resistance, and seawater corrosion resistance, significantly improving output signal stability and reducing manufacturing costs. The flexible substrate is a flexible polyimide (PI) substrate to form a stable flexible printed circuit board (FPC) structure, giving the friction layer assembly flexibility and good mechanical compliance.

[0030] It should be noted that the negative friction material used in this invention is not limited to FEP film. Other materials with strong electron-accepting ability are also applicable, such as polytetrafluoroethylene (PTFE), polydimethylsiloxane (PDMS), polyimide (PI), chlorinated polyethylene, fluorinated ethylene propylene copolymer, etc.

[0031] It should be noted that the electrode material used in this invention is not limited to copper. In addition, conductive materials known in the art, including conductive metals, alloys or conductive oxides, are also applicable.

[0032] Furthermore, to improve output signal stability, the electrodes are designed with an arc-shaped, symmetrical partitioning to optimize the electric field distribution and ensure a linear relationship between the output signal and the flow velocity. To increase output power per unit area, the electrodes are uniformly arranged in an alternating pattern on the flexible substrate to form an electrode layer, such as... Figure 2 As shown. The electrodes are connected in parallel by flexible wires to reduce internal resistance; the spacing between adjacent electrodes is preferably 0.2 mm. The negative friction material is bonded to the electrode layer with an adhesive backing; the flexible substrate side of the friction layer assembly is tightly pressed to the rotating body by a hot-pressing process, thereby forming a stable triboelectric sensing unit.

[0033] like Figure 3 The diagram illustrates the working principle of this invention. Its energy conversion is based on the triboelectric effect and electrostatic induction. Initially, both the rolling element (e.g., a copper rod) and the FEP film are electrically neutral. As the copper rod rolls on the FEP film surface, friction occurs, causing the copper rod to become positively charged and the FEP film surface to become negatively charged, creating a static charge distribution of opposite polarities. Due to the asymmetrical charge distribution on the FEP film surface, a potential difference is generated between the electrode pairs below it, causing electrons to flow in the external circuit. As the copper rod continues to roll, it overlaps with different electrode regions. As the copper rod moves from the negative electrode region to the positive electrode region, electrostatic induction causes electrons to flow from the negative electrode to the positive electrode through the external circuit, generating a positive current. When the copper rod returns to the negative electrode region, the electron flow reverses, generating a reverse current. Through this periodic contact and separation motion, charge continuously transfers back and forth in the external circuit, forming a stable alternating current, thus continuously converting the mechanical energy of the ocean current into electrical energy. Simultaneously, the frequency of the sensing voltage signal achieves the effect of monitoring the flow velocity.

[0034] Furthermore, the triboelectric sensing unit is electrically connected to an energy storage unit, which stores the electrical energy generated by the triboelectric sensing unit and enables the sensor to be self-powered through rectification and voltage regulation circuits. To verify that the electrical energy generated by the triboelectric sensing unit can be stored in a capacitor element (energy storage unit), such as... Figure 5 As shown in the figure, the charging curves for different capacitors were tested, demonstrating that a 6.8μF capacitor can be charged to 4V within 100s. Deep-sea tests show that this device operates successfully on the external platform of a manned submersible and can work continuously for more than 12 hours.

[0035] In this embodiment, the transmission ratio of the magnetic coupling transmission unit is 8:1; this transmission ratio can achieve low torque transmission and high energy utilization efficiency.

[0036] The output performance was tested by controlling the rotary drive unit with a rotary motor to generate different speeds. The output voltage and current were tested at different speeds of 5 rpm, 10 rpm, 20 rpm, 30 rpm, 50 rpm, 100 rpm, 200 rpm, and 300 rpm. Figure 4 As stated in section a, the output current clearly increases with increasing rotational speed. The faster the rotational speed, the higher the frequency of the copper rod rolling on the FEP film, the faster the contact separation speed, and the higher the charge transfer rate generated by triboelectricity, thus increasing the output current. This aligns with the basic characteristics of triboelectric nanogenerators. Figure 4 As shown in b, the output voltage remains essentially unchanged with rotational speed. For contact-separation mode triboelectric nanogenerators, the open-circuit voltage depends primarily on the surface charge density of the friction material and the electrode spacing, and is largely independent of the rotational speed. Once the material becomes saturated with charge, the voltage tends towards its saturation value; therefore, the voltage in the figure does not change with rotational speed, indicating that the sensor operates stably. Furthermore, the minimum test rotational speed of 5 rpm corresponds to an ultra-low current velocity in actual ocean currents (approximately 0.87 cm / s), verifying the ability to measure ultra-low current velocities.

[0037] Furthermore, such as Figure 6 As shown, under laboratory testing, the rotational speed and voltage signal frequency of the triboelectric sensing unit showed a considerable correspondence. 2 =0.999. This indicates that the sensor output signal strength is linearly positively correlated with the flow velocity, and can be used for velocity measurement. In the deep-sea environment, noise such as electromagnetic interference and water pressure changes mainly affect the signal amplitude, while having a minimal impact on the frequency. Therefore, estimating the flow velocity by measuring the frequency is much more reliable than measuring the voltage / current amplitude.

[0038] Furthermore, this embodiment also discloses the specific structure of the sensor, including a pressure-resistant sealed housing, which comprises upper and lower coupling housings, a sealing end cap, and a cylindrical housing; the magnetic coupling transmission unit 1 includes two pairs of magnetic couplings, the lower pair of magnetic couplings being connected to a rotary drive unit 10 via a drive shaft 9, the rotary drive unit preferably being a rotary cup. A triboelectric sensing unit is disposed between the two pairs of magnetic couplings, including an aluminum alloy rotor with a friction layer assembly 7 attached to it, and a rolling element 8 copper rod in contact with the friction layer assembly 7. An electronic compass 3 and a signal processing unit 6 are also disposed inside the pressure-resistant sealed housing, the signal processing unit 6 being electrically connected to the triboelectric sensing unit, and the final sensing signal can be transmitted to an external platform through the signal processing unit.

[0039] The manufacturing process of the sensor is as follows: First, the triboelectric sensing unit is fabricated. Using a 27.82 mm diameter flexible FPC material as a substrate, several pairs of 0.1 mm thick copper electrodes are uniformly arranged on its surface in an alternating pattern (0.2 mm interval between adjacent electrodes) to enhance the symmetry of the electrical signal and output stability. An FEP negative friction layer is bonded to the electrode layer surface using adhesive. The substrate side is then tightly pressed with an aluminum alloy rotor using a hot-pressing process to form a stable triboelectric sensing unit. Second, a magnetic coupling drive unit is constructed. An external rotary drive unit generates rotational motion under the action of ocean currents, transmitting torque to the internal triboelectric sensing unit through a non-contact magnetic coupling structure, achieving low-torque drive and high energy transfer efficiency. The internal triboelectric sensing unit is supported by a high-precision bearing, enabling it to maintain smooth rolling under fluid conditions, thereby generating a periodic alternating electrical signal whose output frequency is linearly related to the flow velocity. Finally, the system is packaged and integrated with the circuit. The signal processing unit and energy storage unit are electrically connected to the triboelectric sensing unit, and energy management and self-powering functions are achieved through rectification and voltage regulation circuits. The pressure-resistant sealed housing is made of titanium alloy or PEEK, giving the sensor high strength and excellent pressure resistance and corrosion resistance. Furthermore, all connections of the pressure-resistant sealed housing are sealed using O-rings and epoxy encapsulation, ensuring leak-free operation of the sensor under 126.5 MPa hydrostatic pressure (e.g., Figure 7 (As shown).

[0040] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. A self-powered ocean current sensor with ultra-low flow rate measurement capability, characterized in that, The sensor includes: Pressure-resistant sealed housing; A rotary drive unit is disposed outside the pressure-resistant sealed housing and is used to generate rotary motion when driven by fluid; A magnetic coupling transmission unit is disposed inside the pressure-resistant sealed housing and is used to transmit the torque of the rotary drive unit to the interior of the pressure-resistant sealed housing in a non-contact manner. A triboelectric sensing unit, disposed inside the pressure-resistant sealed housing, is used to generate an alternating electrical signal from the fluid kinetic energy transmitted by the magnetic coupling transmission unit through triboelectric effect and electrostatic induction. The triboelectric sensing unit adopts a rolling friction structure, including a friction layer assembly, at least one rolling element, and a rotating body. The friction layer assembly and the rolling element are both mounted on the rotating body, which is driven to rotate by the magnetic coupling transmission unit. The surface of the rolling element is in contact with the outer surface of the friction layer assembly. The rolling element is positioned and mounted on the rotating body. The rolling element continuously generates an alternating charge transfer signal on the surface of the friction layer assembly through a combined motion of revolving with the rotating body and rotating on its own axis. The signal processing unit, electrically connected to the triboelectric sensing unit, is used to process the alternating electrical signal to output information characterizing the flow velocity.

2. A self-powered ocean current sensor with ultra-low flow rate measurement capability as claimed in claim 1, wherein: The friction layer assembly includes a negative friction material, several electrodes, and a flexible substrate; the electrodes are arranged in an arc-shaped, symmetrical pattern, with adjacent electrodes evenly distributed on the flexible substrate in an alternating manner to form an electrode layer; the negative friction material is fixed on the electrode layer; the flexible substrate side of the friction layer assembly is tightly fitted to the rotating body.

3. A self-powered ocean current sensor with ultra-low flow rate measurement capability as claimed in claim 2, wherein: The electrode has a thickness of 0.08~0.12 mm, and the spacing between adjacent electrodes is 0.15~0.25 mm; the negative friction material has a thickness of 0.04~0.06 mm.

4. A self-powered ocean current sensor with ultra-low current velocity measurement capability as described in claim 1, characterized in that: The triboelectric sensing unit is electrically connected to the energy storage unit, which stores the electrical energy generated by the triboelectric sensing unit and enables the sensor to be self-powered through rectification and voltage regulation circuits.

5. A self-powered ocean current sensor with ultra-low flow rate measurement capability as claimed in claim 1, wherein: The transmission ratio of the magnetic coupling transmission unit is 8:

1.

6. A self-powered ocean current sensor with ultra-low flow rate measurement capability as claimed in claim 1, wherein: The frequency of the signal output by the signal processing unit is linearly related to the flow rate.

7. A self-powered ocean current sensor with ultra-low flow rate measurement capability as claimed in claim 1, wherein: The pressure-resistant sealing housing includes a coupling housing, a sealing end cap, and a cylindrical housing; the pressure-resistant sealing housing is made of titanium alloy or polyetheretherketone; the connections of the pressure-resistant sealing housing are all sealed by O-rings and epoxy encapsulation.

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