A sensor for measuring the liquid level position in a marine fuel tank and a working method thereof

Abstract

The present invention relates to the technical field of ship fuel tank monitoring, and discloses a sensor for measuring the liquid level position in a ship fuel tank and a working method thereof, that is, the sensor comprises a mounting mechanism, a protective tube, a rectangular partition, a first capacitance measuring probe, a second capacitance measuring probe and a processing module, the second capacitance measuring probe is wrapped by an insulating layer and the bottom end position of the second capacitance measuring probe is lower than the bottom end position of the first capacitance measuring probe, so that after the sensor is installed, based on conventional capacitance detection and liquid level height measurement principles, according to the fitting function of calibration data and two capacitance measurement values ​​collected and obtained by two capacitance measuring probes of different lengths, the fuel liquid level position and the oil-water interface position corresponding to the two capacitance measurement values ​​can be determined, so as to achieve the purpose of monitoring the water intrusion on the bottom of the tank and measuring the fuel level at the same time, thereby improving the safety of ship operation and the anti-damage management capability, and is particularly suitable for use in the field of unmanned ships.

Description

Technical Field

[0001] The present invention belongs to the technical field of ship fuel tank monitoring, and relates to ship fuel application, measurement, safety assurance and an innovative product integrating them, and specifically relates to a sensor for measuring the liquid level position in a ship fuel tank and a working method thereof. Background Art

[0002] At present, the measurement of fuel in the fuel tank of a ship mainly focuses on the measurement of the fuel liquid level position. The remaining fuel can be calculated through the measured liquid level data and the tank capacity table. This is the main method and purpose of monitoring and measuring fuel tanks applied by domestic ships at present (the purpose of the measurement is to determine how much remaining fuel is the goal). However, in actual application, in addition to monitoring the fuel level, there are also some other applications for monitoring the fuel tank, such as monitoring the water accumulation at the bottom of the fuel tank. At present, in many ship applications, the monitoring of the bottom water is carried out manually, that is, by manually observing the oil-water interface position at the bottom of the tank (an observation window needs to be set at the bottom of the tank), or by regularly discharging the liquid at the bottom of the cabin and other manual identification methods. At present, there is no effective and feasible technical solution based on automatic sensing monitoring to achieve this goal.

[0003] In general ship applications, due to the presence of a certain amount of water in the fuel, the moisture in the cabin will gradually condense over a long period of time. Since condensation takes a certain amount of time and the total amount is not large, regular manual inspection or observation can eliminate the harm of these water contents to the use of fuel. However, when seawater enters the fuel tank due to other reasons (such as wartime damage, collision damage, damage to other device pipelines or human error operation, etc.), the seawater is heavier than the fuel, so the seawater gathers at the bottom of the cabin. The fuel in the fuel tank provides energy for the entire power system, and its oil outlet is close to the bilge position (generally, the oil outlet is slightly higher than the lowest position of the bilge, and the purpose of doing so is to prevent the water and impurities at the bilge from being input into the power device; but generally, this height will not be too high from the bilge position, otherwise there will be a lot of fuel that cannot be used). When the seawater gathers to a certain level, or the oil-water interface is higher than the water outlet, or due to the shaking of the ship, the seawater may enter the fuel delivery pipe, which may bring great safety risks and hidden dangers. Especially in the unmanned ship market, with the gradual development and maturity of unmanned technology and industry, unmanned ships have the characteristics of long time away from home, unmanned operation, difficult to fully control the running trajectory and relatively small size. Therefore, when problems arise, they cannot rely on people to discover and solve them in time. Therefore, the monitoring of the safety process involved in unmanned ships will become more and more important. The fuel system, as an important link, is the focus of monitoring. Once there is water in the fuel (or water accumulates to a certain extent), it is a fatal hazard to the entire fuel engine.

[0004] In view of the increasingly urgent requirements for ocean-going ships and the rapid development of the unmanned ship industry, ship fuel usage and status monitoring has become increasingly important. Therefore, it is necessary to provide a new type of sensor to achieve the purpose of monitoring bilge flooding and measuring the fuel level at the same time, so as to improve the safety of ship operation and anti-damage management capabilities. Summary of the invention

[0005] In order to solve the problem that the existing ship fuel tank monitoring technology cannot automatically monitor the bottom flooding and measure the fuel level at the same time, the purpose of the present invention is to provide a new sensor for measuring the liquid level position in the ship fuel tank and its working method, which can achieve the purpose of monitoring the bottom flooding and measuring the fuel level at the same time, thereby improving the safety of ship operation and anti-damage management capabilities, and is particularly suitable for use in the field of unmanned ships.

[0006] In the first aspect, the technical solution adopted by the present invention is:

[0007] A sensor for measuring the liquid level position in a marine fuel tank, comprising a mounting mechanism, a protective tube, a rectangular partition, a first capacitance measuring probe, a second capacitance measuring probe and a signal acquisition and calculation processing module, wherein the mounting mechanism is used to mount the entire sensor on the top of the tank or the side wall of the tank of the marine fuel tank;

[0008] The top end of the protection tube is fixedly connected to the installation mechanism, and the protection tube is located in the cabin space of the marine fuel tank after the sensor is installed;

[0009] The rectangular partition is located inside the protection tube and is parallel to the center line of the protection tube, the width of the rectangular partition is consistent with the inner diameter of the protection tube, and the length of the rectangular partition is consistent with the length of the protection tube, so as to divide the internal space of the protection tube into a first measurement space and a second measurement space;

[0010] The first capacitance measuring probe is located in the first measuring space and is spaced apart and parallel to the rectangular partition, the top end of the first capacitance measuring probe is fixedly connected to the mounting mechanism, and the first capacitance measuring probe is spaced apart from the wall of the protective tube;

[0011] The second capacitance measuring probe is located in the second measuring space and is spaced apart and parallel to the rectangular partition, the top end of the second capacitance measuring probe is fixedly connected to the mounting mechanism, the second capacitance measuring probe is wrapped by an insulating layer and spaced apart from the wall of the protective tube, and the bottom end position of the second capacitance measuring probe is lower than the bottom end position of the first capacitance measuring probe;

[0012] The signal acquisition and calculation processing module is fixed on the mounting mechanism and has two input ends electrically connected to the output end of the first capacitance measuring probe and the output end of the second capacitance measuring probe respectively.

[0013] Based on the above invention content, a new sensor for measuring the liquid level position in a marine fuel tank is provided, which includes a mounting mechanism, a protective tube, a rectangular partition, a first capacitance measuring probe, a second capacitance measuring probe and a signal acquisition and calculation processing module, wherein the second capacitance measuring probe is wrapped by an insulating layer and the bottom end position of the second capacitance measuring probe is lower than the bottom end position of the first capacitance measuring probe, so that after the sensor is installed, based on conventional capacitance detection and liquid level measurement principles, according to the fitting function of calibration data and two capacitance measurement values ​​collected and obtained by two capacitance measuring probes of different lengths, the fuel liquid level position and the oil-water interface position corresponding to the two capacitance measurement values ​​can be determined, thereby achieving the purpose of monitoring the flooding of the bottom of the tank and measuring the fuel level at the same time, thereby improving the safety of ship operation and the anti-damage management capability, and is particularly suitable for use in the field of unmanned ships.

[0014] Optimally, the rectangular partition and the first capacitance measuring probe are respectively made of metal materials, and the bottom end position of the first capacitance measuring probe is slightly lower than the fuel outlet position or is flush with the fuel outlet position after the sensor is installed.

[0015] Optimally, the installation mechanism includes an interpenetrating cylinder, a flange, a cylindrical boss and a probe fixing ring, wherein the interpenetrating cylinder is used to be inserted into a mounting through hole located on the top of the cabin or the side wall of the cabin during installation, the flange is coaxially connected to the cabin outer end of the interpenetrating cylinder and is used to dock and fix with the cabin outer flange of the mounting through hole during installation, and the cylindrical boss is coaxially arranged on the cabin inner end surface of the interpenetrating cylinder;

[0016] The diameter of the cylindrical boss matches the inner diameter of the protective tube, and the top end of the protective tube is fixedly connected to the mounting mechanism by plugging and fitting with the cylindrical boss;

[0017] A step hole is provided on the boss surface of the cylindrical boss, and the probe fixing ring is fixedly installed in the step hole. The top end of the first capacitance measuring probe and the top end of the second capacitance measuring probe are respectively fixed in the probe fixing ring through fixing joints to achieve fixed connection with the mounting mechanism.

[0018] Optimally, a fixing ring is installed at the bottom of the protection tube, and an insulating positioning frame is radially installed inside the fixing ring, wherein the insulating positioning frame is used to position the bottom of the rectangular partition and the bottom of the second capacitance measuring probe.

[0019] Optimally, the bottom end position of the protection tube is lower than the fuel outlet position of the marine fuel tank after the sensor is installed, and the elevation difference between the bottom end position of the protection tube and the bottom end position of the second capacitance measuring probe and the lowest position in the marine fuel tank after the sensor is installed is between 5 and 15 mm.

[0020] Optimally, a plurality of liquid-passing holes are provided on the cylinder walls of the first measuring space and the second measuring space and are arranged in sequence from top to bottom.

[0021] Optimally, a plurality of insulating support frames are respectively arranged on the two side surfaces of the rectangular partition in an interval from top to bottom, wherein the insulating support frames are used to fix and support the first capacitance measuring probe or the second capacitance measuring probe on the corresponding side.

[0022] Optimized, the signal acquisition and calculation processing module includes a signal acquisition circuit board, a calculation processing circuit board, and a display and a data transmission connector located outside the cabin after the sensor is installed, wherein the two input ends of the signal acquisition circuit board are respectively electrically connected to the output end of the first capacitance measuring probe and the output end of the second capacitance measuring probe, the output end of the signal acquisition circuit board is communicatively connected to the input end of the calculation processing circuit board, and the two output ends of the calculation processing circuit board are respectively communicatively connected to the display and the data transmission connector.

[0023] In the second aspect, the technical solution adopted by the present invention is:

[0024] A working method of the sensor as described in the first aspect, which is executed by a signal acquisition and calculation processing module after the sensor is installed, and includes a data calibration stage and a liquid level measurement stage;

[0025] The data calibration stage includes:

[0026] When the inner space of the marine fuel tank contains pure oil, for each of the multiple inner tank calibration liquid levels, a corresponding first capacitance calibration value is acquired by using a first capacitance measuring probe, and a corresponding second capacitance calibration value is acquired by using a second capacitance measuring probe;

[0027] A first fitting function is obtained by fitting according to a one-to-one correspondence between the plurality of calibration liquid levels in the chambers and the plurality of calibration values ​​of the first capacitance, and a second fitting function is obtained by fitting according to a one-to-one correspondence between the plurality of calibration liquid levels in the chambers and the plurality of calibration values ​​of the second capacitance;

[0028] saving the first fitting function and the second fitting function;

[0029] The liquid level measurement stage includes:

[0030] Acquiring a first capacitance measurement value through a first capacitance measurement probe, and acquiring a second capacitance measurement value through a second capacitance measurement probe;

[0031] determining a measured liquid level in a first chamber corresponding to the first capacitance measurement value based on the first fitting function, and determining a measured liquid level in a second chamber corresponding to the second capacitance measurement value based on the second fitting function;

[0032] Determining whether the absolute value of the liquid level difference between the liquid level measured in the first chamber and the liquid level measured in the second chamber is less than a preset threshold;

[0033] If it is less than, the average value of the measured liquid level in the first tank and the measured liquid level in the second tank is taken as the fuel liquid level position of the marine fuel tank, and the oil-water interface position is determined to be below the bottom end position of the second capacitance measuring probe; otherwise, the measured liquid level in the first tank is taken as the fuel liquid level position, and the oil-water interface position is determined to be between the bottom end position of the first capacitance measuring probe and the bottom end position of the second capacitance measuring probe.

[0034] Optimally, when the rectangular partition and the first capacitance measuring probe are respectively made of metal materials, and the bottom end position of the first capacitance measuring probe is slightly lower than the fuel outlet position or is level with the fuel outlet position after the sensor is installed, the working method further includes:

[0035] In the liquid level measurement stage and after the first capacitance measurement value is acquired by the first capacitance measuring probe, if it is determined that the first capacitance measurement value exceeds the capacitance calibration value range, the oil-water interface position is determined to be the bottom position of the first capacitance measuring probe, and an alarm signal is issued, wherein the capacitance calibration value range is determined by the maximum value and the minimum value of multiple first capacitance calibration values.

[0036] The beneficial effects of the present invention are:

[0037] (1) The present invention provides a novel sensor for measuring the liquid level position in a marine fuel tank, which comprises a mounting mechanism, a protective tube, a rectangular partition, a first capacitance measuring probe, a second capacitance measuring probe and a signal acquisition and calculation processing module, wherein the second capacitance measuring probe is wrapped by an insulating layer and the bottom end position of the second capacitance measuring probe is lower than the bottom end position of the first capacitance measuring probe, so that after the sensor is installed, based on conventional capacitance detection and liquid level measurement principles, according to the fitting function of calibration data and two capacitance measurement values ​​collected and obtained by two capacitance measuring probes of different lengths, the fuel liquid level position and the oil-water interface position corresponding to the two capacitance measurement values ​​can be determined, thereby achieving the purpose of monitoring the flooding of the bilge and measuring the fuel level at the same time, thereby improving the safety of ship operation and the anti-damage management capability, and is particularly suitable for use in the field of unmanned ships;

[0038] (2) The unique algorithm can accurately locate the fuel level and the oil-water interface, so that the remaining oil volume and the bilge flooding situation can be accurately monitored, which is beneficial to further improve the safety of ship operation and damage resistance and management capabilities;

[0039] (3) The material design of the baffle and the short probe and the design of the bottom installation position of the short probe can facilitate automatic identification of whether the oil-water interface approaches or rises to the fuel outlet position, so as to trigger an alarm in time to remind the user to close the fuel outlet, automatically close the fuel outlet or start the water discharge task, thereby ultimately ensuring the operational safety of the ship's power system;

[0040] (4) The sensor also has the advantages of high installation stability, reliable measurement results, splicing to extend the measurement range and simple structure, which is convenient for practical application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 It is a schematic diagram of the main structure of the sensor provided by the present invention.

[0043] Figure 2 It is a schematic diagram of the circuit structure of the sensor provided by the present invention.

[0044] Figure 3 This is an example diagram of the installation mechanism provided by the present invention for installing the sensor on the ship's fuel tank.

[0045] Figure 4 It is an example diagram of fitting curves of multiple cabin calibration liquid levels and multiple first capacitance calibration values ​​provided by the present invention.

[0046] Figure 5 It is an example diagram of fitting curves of multiple cabin calibration liquid levels and multiple second capacitance calibration values ​​provided by the present invention.

[0047] Figure 6 It is an example diagram of fitting curves of multiple calibrated liquid levels in the chambers between the bottom ends of the two probes and multiple third capacitance calibration values ​​provided by the present invention.

[0048] In the above drawings: 1-installation mechanism; 11-interpenetrating column; 12-flange; 2-protective tube; 21-first measuring space; 22-second measuring space; 23-fixing ring; 24-liquid hole; 25-insulating support frame; 3-rectangular partition; 41-first capacitance measuring probe; 42-second capacitance measuring probe; 5-signal acquisition and calculation processing module; 50-meter head; 51-signal acquisition circuit board; 53-display; 54-data transmission connector; 100-marine fuel tank; 101-fuel liquid level; 102-oil-water interface; 103-lowest position in the tank; 200-fuel outlet. DETAILED DESCRIPTION

[0049] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that although the description of these embodiments is used to help understand the present invention, it does not constitute a limitation of the present invention. The specific structures and functional details disclosed herein are only used to describe the embodiments of the present invention. However, the present invention can be embodied in many alternative forms, and it should not be understood that the present invention is limited to the embodiments set forth herein.

[0050] It should be understood that although the terms first, second, etc. may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another unit. For example, a first unit can be referred to as a second unit, and similarly, a second unit can be referred to as a first unit without departing from the scope of the exemplary embodiments of the present invention.

[0051] It should be understood that the term "and / or" that may appear in this article is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" that may appear in this article describes another type of association object relationship, indicating that two relationships may exist. For example, A / and B can represent two situations: A exists alone, and A and B exist alone. In addition, the character " / " that may appear in this article generally indicates that the previous and next associated objects are in an "or" relationship.

[0052] Embodiment 1

[0053] like Figures 1 to 3As shown, the sensor for measuring the liquid level position in a marine fuel tank provided in this embodiment includes a mounting mechanism 1, a protective tube 2, a rectangular partition 3, a first capacitance measuring probe 41, a second capacitance measuring probe 42 and a signal acquisition and calculation processing module 5, wherein the mounting mechanism 1 is used to mount the entire sensor on the top of the tank body or the side wall of the tank body of the marine fuel tank 100; the top end of the protective tube 2 is fixedly connected to the mounting mechanism 1, and the protective tube 2 is located in the cabin space of the marine fuel tank 100 after the sensor is installed; the rectangular partition 3 is located inside the protective tube 2 and is parallel to the center line of the protective tube 2, the width of the rectangular partition 3 is consistent with the inner diameter of the protective tube 2, and the length of the rectangular partition 3 is consistent with the length of the protective tube 2, so as to divide the internal space of the protective tube 2 into a first measurement space 21 and a second measurement space 22; the first A capacitance measuring probe 41 is located in the first measuring space 21 and is spaced and parallel to the rectangular partition 3. The top end of the first capacitance measuring probe 41 is fixedly connected to the mounting mechanism 1, and the first capacitance measuring probe 41 is spaced apart from the wall of the protective tube 2. The second capacitance measuring probe 42 is located in the second measuring space 22 and is spaced and parallel to the rectangular partition 3. The top end of the second capacitance measuring probe 42 is fixedly connected to the mounting mechanism 1. The second capacitance measuring probe 42 is wrapped by an insulating layer and is spaced apart from the wall of the protective tube 2, and the bottom end position of the second capacitance measuring probe 42 is lower than the bottom end position of the first capacitance measuring probe 41. The signal acquisition and calculation processing module 5 is fixed on the mounting mechanism 1 and the two input ends are electrically connected to the output end of the first capacitance measuring probe and the output end of the second capacitance measuring probe 42, respectively.

[0054] like Figure 1 and 3 As shown, in the specific structure of the sensor, the specific structure of the mounting mechanism 1 can be selected and determined according to the installation space provided by the marine fuel tank 100. If the top of the tank of the marine fuel tank 100 has an installation space, the mounting mechanism 1 can structurally adopt a top-mounted flange mounting mechanism that matches the installation space, so that the entire sensor can be inserted from the tank top installation hole, and the sensor can be fixedly installed by flange docking. Otherwise, the mounting mechanism 1 can structurally adopt a side-mounted flange mounting mechanism, so that the entire sensor can be inserted from the side wall installation hole, and the sensor can be fixedly installed by flange docking. Of course, the mounting mechanism 1 can also adopt other existing specific structures, such as a suction cup fixing structure. In addition, if the sensor is long (that is, the protective tube 2 is long), a fixed support frame (not shown in the figure) can also be installed at a position near the bottom of the sensor (that is, the bottom of the protective tube 2) on the side wall of the cabin, so as to provide a restraining effect on the bottom of the sensor after installation to prevent it from shaking around.

[0055] The protective tube 2 is used to protect the two probes inside and serve as a ground reference for capacitance measurement; the posture of the protective tube 2 after installation is preferably in a vertical state, so as to accurately obtain the one-to-one correspondence between the calibration liquid level in the cabin and the capacitance calibration value, and ensure the accuracy of the final liquid level position. The rectangular partition 3 is used to separate the inner space of the protective tube 2 into two independent vertical measurement spaces: the first measurement space 21 and the second measurement space 22, so that the corresponding capacitance measurement probes can be built in respectively; the first measurement space 21 and the second measurement space 22 are preferably semi-cylindrical spaces divided in half. In addition, the bottom port of the protective tube 2 is an open port, so that the liquid level inside and outside the tube (including the fuel level and the oil-water interface) is always consistent, and the accuracy of the final liquid level position is ensured.

[0056] The first capacitance measuring probe 41 and the second capacitance measuring probe 42 are respectively used to collect and obtain capacitance measurement signals corresponding to the liquid level in the cabin based on the existing capacitance measurement principle, so that the signal acquisition and calculation processing module 5 converts the capacitance measurement signal into a capacitance measurement value after inputting the capacitance measurement signal. The first capacitance measuring probe 41 is mainly used to collect capacitance measurement signals when the surrounding is in a pure oil state, and because the fuel has good insulation, the first capacitance measuring probe 41 can be exposed without an insulation layer. The second capacitance measuring probe 42 is mainly used to collect capacitance measurement signals when the surrounding is in a pure oil state or when the oil-water interface position is between the bottom positions of the two probes, and because water is conductive, the second capacitance measuring probe 42 needs to be wrapped by an insulation layer, wherein the insulation layer preferably uses a sealed polytetrafluoroethylene tube that can be sleeved on the outside of the second capacitance measuring probe 42 to insulate the second capacitance measuring probe 42. When the top position of the first capacitance measuring probe 41 is aligned with the top position of the protection tube 2, the length of the first capacitance measuring probe 41 needs to be shorter than the length of the protection tube 2; when the top position of the first capacitance measuring probe 41 is aligned with the top position of the second capacitance measuring probe 42, the length of the second capacitance measuring probe 42 needs to be longer than the length of the first capacitance measuring probe 41; and when the top position of the protection tube 2 is aligned with the top position of the second capacitance measuring probe 42, the length of the second capacitance measuring probe 42 can be slightly longer (e.g., 5 mm longer), equal to or slightly shorter (e.g., 5 mm shorter) than the length of the protection tube 2. In addition, the first capacitance measuring probe 41 and the second capacitance measuring probe 42 are preferably monopolar probes.

[0057] The signal acquisition and calculation processing module 5 is used as the signal processing core of the entire sensor, and is used to implement the following working principle based on the conventional capacitance detection and liquid level height measurement principle: after the sensor is installed, firstly, the calibration data including multiple voltage calibration values ​​corresponding to multiple cabin calibration liquid levels (including fuel liquid level position, pure water liquid level position and / or oil-water interface position, etc.) are acquired through the first capacitance measurement probe 41 and the second capacitance measurement probe 42, and a fitting function is determined based on the one-to-one correspondence between multiple cabin calibration liquid levels and multiple voltage calibration values ​​in the calibration data, and then two capacitance measurement values ​​are acquired through the first capacitance measurement probe 41 and the second capacitance measurement probe 42 during liquid level measurement, and finally the fuel liquid level position and the oil-water interface position of the marine fuel tank 100 corresponding to the two capacitance measurement values ​​are determined through the fitting function, so as to achieve the purpose of monitoring the bottom flooding and measuring the fuel liquid level at the same time. The signal acquisition and calculation processing module 5 can be implemented by, but not limited to, a microprocessor chip of the STM32F103 series and its peripheral circuits.

[0058] Thus, through the detailed description of the above-mentioned sensor structure and working principle, a new sensor for measuring the liquid level position in a marine fuel tank is provided, which includes a mounting mechanism, a protective tube, a rectangular partition, a first capacitance measuring probe, a second capacitance measuring probe and a signal acquisition and calculation processing module, wherein the second capacitance measuring probe is wrapped by an insulating layer and the bottom end position of the second capacitance measuring probe is lower than the bottom end position of the first capacitance measuring probe, so that after the sensor is installed, based on conventional capacitance detection and liquid level measurement principles, according to the fitting function of the calibration data and the two capacitance measurement values ​​collected and obtained by the two capacitance measuring probes of different lengths, the fuel liquid level position and the oil-water interface position corresponding to the two capacitance measurement values ​​can be determined, so as to achieve the purpose of monitoring the flooding of the bottom of the tank and measuring the fuel level at the same time, thereby improving the safety of ship operation and the anti-damage management capability, and is particularly suitable for application in the field of unmanned ships.

[0059] Optimized, in order to achieve accurate positioning of the fuel level position and the oil-water interface position, the working method of the sensor is executed by the signal acquisition and calculation processing module 5 after the sensor is installed, including but not limited to a data calibration stage and a liquid level measurement stage.

[0060] The data calibration stage includes, but is not limited to, the following steps: when the space inside the ship fuel tank 100 contains pure oil (referring to water-free fuel), for each of the multiple in-tank calibration liquid levels, the corresponding first capacitance calibration value is acquired through the first capacitance measuring probe 41, and the corresponding second capacitance calibration value is acquired through the second capacitance measuring probe 42; according to the one-to-one correspondence between the multiple in-tank calibration liquid levels and the multiple first capacitance calibration values, a first fitting function is fitted, and according to the one-to-one correspondence between the multiple in-tank calibration liquid levels and the multiple second capacitance calibration values, a second fitting function is fitted; and the first fitting function and the second fitting function are saved. The aforementioned multiple in-tank calibration liquid levels can be specifically the liquid level range scale above the fuel outlet 200, for example, each scale every 50 mm on the range of 0 to 1400 mm; the aforementioned capacitance calibration value acquisition process and fitting process can be implemented based on the existing technology, and the obtained fitting curve diagrams of the first fitting function and the second fitting function can be exemplified as follows. Figure 4 and 5 As shown, they all show an approximately linear relationship.

[0061] The liquid level measurement stage includes but is not limited to the following steps: acquiring a first capacitance measurement value through the first capacitance measuring probe 41, and acquiring a second capacitance measurement value through the second capacitance measuring probe 42; determining a first tank measured liquid level corresponding to the first capacitance measurement value according to the first fitting function, and determining a second tank measured liquid level corresponding to the second capacitance measurement value according to the second fitting function; judging whether the absolute value of the liquid level difference between the first tank measured liquid level and the second tank measured liquid level is less than a preset threshold; if so, taking the average value of the first tank measured liquid level and the second tank measured liquid level as the fuel liquid level position of the marine fuel tank 100, and judging that the oil-water interface position is below the bottom end position of the second capacitance measuring probe 42; otherwise, taking the first tank measured liquid level as the fuel liquid level position, and judging that the oil-water interface position is between the bottom end position of the first capacitance measuring probe 41 and the bottom end position of the second capacitance measuring probe 42.

[0062] Since the capacitance measurement value is closely related to the relative dielectric constant of the medium between the probe and the cylinder wall, and the relative dielectric constant of water is much larger than the relative dielectric constant of fuel, when the oil-water interface position is between the bottom position of the first capacitance measuring probe 41 and the bottom position of the second capacitance measuring probe 42, the measured liquid level in the second compartment determined according to the second fitting function and corresponding to the second capacitance measurement value will be greatly different from the measured liquid level in the first compartment determined according to the first fitting function and corresponding to the first capacitance measurement value. As long as the absolute value of the liquid level difference exceeds the preset threshold, it can be determined that the bottom position of the second capacitance measuring probe 42 has been immersed in water, and the fuel liquid level position can be accurately determined.

[0063] For further optimization, the oil-water interface can be precisely located according to the following working method:

[0064] The data calibration stage also includes but is not limited to the following steps: when the space inside the marine fuel tank 100 is filled with pure water (referring to water without fuel), for each of the multiple cabin calibration liquid levels between the bottom ends of the two probes, the corresponding third capacitance calibration value is acquired by the second capacitance measuring probe 42; according to the one-to-one correspondence between the multiple cabin calibration liquid levels between the bottom ends of the two probes and the multiple third capacitance calibration values, a third fitting function is fitted; and the third fitting function is saved;

[0065] The liquid level measurement stage also includes but is not limited to the following steps: when it is determined that the oil-water interface position is between the bottom end position of the first capacitance measuring probe 41 and the bottom end position of the second capacitance measuring probe 42, the oil-water interface position H is derived as follows: WO :

[0066] H 1,O =f 1,O (C1) = f′ 1,O (C1) C1

[0067] f 2,W (C2) = f′ 2,W (C2) C2

[0068]

[0069]

[0070] Where C1 represents the first capacitance measurement value, f 1,O (C1) represents the first fitting function whose variable is the first capacitance measurement value, f′ 1,O (C1) represents the derivative of the first fitting function, C2 represents the second capacitance measurement value, and f 2,O(C2) represents the second fitting function whose variable is the second capacitance measurement value, f′ 2,O (C2) represents the derivative of the second fitting function, f 2,W (C2) represents the third fitting function whose variable is the second capacitance measurement value, f′ 2,W (C2) represents the derivative of the third fitting function, H 1,O Indicates the measured liquid level in the first tank.

[0071] The fitting curve diagram of the third fitting function can be exemplified as follows: Figure 6 As shown, it is also an approximate linear relationship. At the same time, since the bottom end of the second capacitance measuring probe 42 has been immersed in water, the water body under the oil-water interface and the fuel on the oil-water interface will affect the measured second capacitance value, which can be regarded as the parallel effect of the first equivalent capacitance of the water body under the oil-water interface and the second equivalent capacitance of the fuel on the oil-water interface. Therefore, there is a formula: Then the oil-water interface position H can be deduced WO The exact calculation formula of .

[0072] Optimally, the rectangular partition 3 and the first capacitance measuring probe 41 are made of metal materials respectively, and the bottom end position of the first capacitance measuring probe 41 is slightly lower (for example, lower than 5mm) or level with the fuel outlet position after the sensor is installed. Therefore, when the oil-water interface 102 rises to the bottom end position of the first capacitance measuring probe 41, the first capacitance measuring probe 41 will short-circuit with the rectangular partition 3 due to the conductivity of the water body. At this time, the capacitance measurement value collected by the first capacitance measuring probe 41 will undergo a special jump, so that the signal acquisition and calculation processing module 5 can recognize that the oil-water interface has approached or risen to the fuel outlet position according to the jump, and then issue an alarm to remind to close the fuel outlet, automatically close the fuel outlet or start the water discharge task, and finally ensure the operation safety of the hull power system. That is, the working method is further optimized and includes but is not limited to: in the liquid level measurement stage and after the first capacitance measurement value is acquired by the first capacitance measurement probe 41, if it is determined that the first capacitance measurement value exceeds the capacitance calibration value range, the oil-water interface position is determined to be the bottom position of the first capacitance measurement probe 41, and an alarm signal is issued, wherein the capacitance calibration value range is determined by the maximum value and the minimum value of the plurality of first capacitance calibration values. In addition, the first capacitance measurement probe 41 can be made of, but not limited to, material 316L.

[0073] Optimally, the installation mechanism 1 includes an inserted cylinder 11, a flange 12, a cylindrical boss and a probe fixing ring, wherein the inserted cylinder 11 is used to be inserted into the installation through hole located on the top of the cabin or the side wall of the cabin during installation, the flange 12 is coaxially connected to the cabin outer end of the inserted cylinder 11 and is used to dock and fix with the cabin outer flange of the installation through hole during installation, and the cylindrical boss is coaxially arranged on the cabin inner end surface of the inserted cylinder 11; the diameter of the cylindrical boss matches the inner diameter of the protective tube 2, and the top end of the protective tube 2 is fixedly connected to the installation mechanism 1 by plugging with the cylindrical boss; a step hole is opened on the boss surface of the cylindrical boss, and the probe fixing ring is fixedly installed in the step hole, and the top end of the first capacitance measuring probe 41 and the top end of the second capacitance measuring probe 42 are respectively fixed in the probe fixing ring through fixing joints to achieve fixed connection with the installation mechanism 1. Figure 1 and 3 As shown, through the specific design of the aforementioned mounting mechanism 1, the purpose of installing the entire sensor on the top of the tank or the side wall of the tank of the marine fuel tank 100 can be achieved, and the installation stability of the protective tube 2 and the two capacitance measurement probes can be ensured. Further optimization, in order to ensure the stability of the plug-in fit, after the top of the protective tube 2 is plugged in with the cylindrical boss, the protective tube 2 and the cylindrical boss are fixed by a welding structure or a side bolt structure (that is, corresponding threaded holes are opened on the side wall of the protective tube 2 and the side of the cylindrical boss, and screws are screwed into the threaded holes to achieve the purpose of bolt fixing). And in order to facilitate the installation of the entire sensor from outside the cabin, the outer diameter of the protective tube 2 is smaller than the diameter of the interpenetrating column 11. In addition, when the mounting mechanism 1 adopts a side-mounted flange mounting mechanism, the interpenetrating column 11 needs to be bent 90 degrees to ensure that the posture of the protective tube 2 after installation is still in a vertical state.

[0074] Optimally, a fixing ring 23 is installed at the bottom of the protective tube 2, and an insulating positioning frame is radially installed inside the ring of the fixing ring 23, wherein the insulating positioning frame is used to position the bottom of the rectangular partition 3 and the bottom of the second capacitance measuring probe 42. Through the design of the fixing ring 23 and the insulating positioning frame, the bottom of the rectangular partition 3 and the bottom of the second capacitance measuring probe 42 can be positioned and stabilized to ensure the reliability of the collection of the capacitance measurement value. In addition, the insulating positioning frame can be made of, but not limited to, polytetrafluoroethylene.

[0075] Optimally, the bottom end position of the protection tube 2 is lower than the fuel outlet position of the marine fuel tank 100 after the sensor is installed, and the height difference between the bottom end position of the protection tube 2 and the bottom end position of the second capacitance measuring probe 42 and the lowest position in the marine fuel tank 100 after the sensor is installed is between 5 and 15 mm. Through the above installation design, it can be ensured that the sensor range can be extended to the bottom of the marine fuel tank 100 as much as possible, such as Figure 3 In addition, although the length of the protective tube 2 can be designed according to the measurement range, in general, for transportation and installation requirements on board ships, the maximum length of the protective tube 2 is limited to 2 meters. If the measurement range is greater than the length of the protective tube, multiple sets of sensors can be installed side by side from top to bottom to expand the measurement range.

[0076] Optimally, a plurality of liquid-passing holes 24 are provided on the walls of the first measuring space 21 and the second measuring space 22, which are arranged in sequence from top to bottom. Figure 1 and 3 As shown, the upper and lower designs of the liquid through hole 24 can improve the fluidity of the liquid inside and outside the cylinder, and further make the liquid level inside and outside the cylinder (including the fuel liquid level and the oil-water interface) always consistent, ensuring the accuracy of the final liquid level position. Figure 1 and 3 As shown, the liquid through hole 24 can be, for example, a long hole.

[0077] Optimally, a plurality of insulating support frames 25 are respectively arranged on the two side surfaces of the rectangular partition 3 and are arranged in sequence from top to bottom, wherein the insulating support frames 25 are used to fix and support the first capacitance measuring probe 41 or the second capacitance measuring probe 42 on the corresponding side. Figure 1 As shown, since the capacitance measuring probe needs to measure the entire measuring range, if it is too long, it will cause bending deformation. Therefore, by setting the insulating support frame 25, it is possible to ensure that the capacitance measuring probe is fastened and does not deform, and to ensure that there is no electrical conduction between the probe and the partition, and that it does not contact the cylinder wall. In addition, the insulating support frame 25 can be made of, but is not limited to, polytetrafluoroethylene material.

[0078] Optimized, the signal acquisition and calculation processing module 5 includes a signal acquisition circuit board 51, a calculation processing circuit board, and a display 53 and a data transmission connector 54 located outside the cabin after the sensor is installed, wherein the two input ends of the signal acquisition circuit board 51 are respectively electrically connected to the output end of the first capacitance measurement probe and the output end of the second capacitance measurement probe 42, the output end of the signal acquisition circuit board 51 is communicatively connected to the input end of the calculation processing circuit board, and the two output ends of the calculation processing circuit board are respectively communicatively connected to the display 53 and the data transmission connector 54. Figure 1 and 2 As shown, the signal acquisition circuit board 51 is arranged in the installation mechanism 1, and the calculation and processing circuit board, the display 53 and the data transmission connector 54 can be arranged on the meter head 50 fixedly connected to the flange 12 (which must be located outside the cabin), wherein the signal acquisition circuit board 51 is used to collect capacitance measurement signals based on the capacitance measurement principle in cooperation with two capacitance measurement probes, and send the capacitance measurement signals to the calculation and processing circuit board, which can be implemented by the existing signal acquisition circuit; the calculation and processing circuit board is used to implement the following working principle based on the liquid level height measurement principle: after the sensor is installed, firstly, based on the one-to-one pairing of multiple cabin calibration liquid levels and multiple voltage calibration values ​​in the calibration data, The fitting function is determined by the corresponding relationship, and then when the liquid level is measured, the fuel liquid level position and the oil-water interface position of the marine fuel tank 100 corresponding to the two capacitance measurement values ​​are determined by the fitting function, so as to achieve the purpose of monitoring the bilge flooding and measuring the fuel liquid level at the same time, which can be implemented by, but not limited to, a microprocessor chip of the STM32F103 series and its peripheral circuits; the display 53 is used to display the measurement data or working status, and can be, but not limited to, a liquid crystal display screen; the data transmission connector 54 is used to output the measurement data or the alarm signal, and can be, but not limited to, an RS485 bus interface, so as to output the measurement data or the alarm signal to the host computer based on the Modbus protocol.

[0079] In summary, the sensor for measuring the liquid level position in a marine fuel tank and the working method thereof provided in this embodiment have the following technical effects:

[0080] (1) This embodiment provides a novel sensor for measuring the liquid level position in a marine fuel tank, including a mounting mechanism, a protective tube, a rectangular partition, a first capacitance measuring probe, a second capacitance measuring probe and a signal acquisition and calculation processing module, wherein the second capacitance measuring probe is wrapped by an insulating layer and the bottom end position of the second capacitance measuring probe is lower than the bottom end position of the first capacitance measuring probe, so that after the sensor is installed, based on conventional capacitance detection and liquid level measurement principles, according to the fitting function of calibration data and two capacitance measurement values ​​collected by two capacitance measuring probes of different lengths, the fuel liquid level position and the oil-water interface position corresponding to the two capacitance measurement values ​​can be determined, thereby achieving the purpose of monitoring the flooding of the bilge and measuring the fuel level at the same time, thereby improving the safety of ship operation and the anti-damage management capability, and is particularly suitable for use in the field of unmanned ships;

[0081] (2) The unique algorithm can accurately locate the fuel level and the oil-water interface, so that the remaining oil volume and the bilge flooding situation can be accurately monitored, which is beneficial to further improve the safety of ship operation and damage resistance and management capabilities;

[0082] (3) The material design of the baffle and the short probe and the design of the bottom installation position of the short probe can facilitate automatic identification of whether the oil-water interface approaches or rises to the fuel outlet position, so as to trigger an alarm in time to remind the user to close the fuel outlet, automatically close the fuel outlet or start the water discharge task, thereby ultimately ensuring the operational safety of the ship's power system;

[0083] (4) The sensor also has the advantages of high installation stability, reliable measurement results, splicing to extend the measurement range and simple structure, which is convenient for practical application and promotion.

[0084] Finally, it should be noted that the present invention is not limited to the above optional implementations, and anyone can derive other various forms of products under the enlightenment of the present invention. The above specific implementations should not be understood as limiting the scope of protection of the present invention. The scope of protection of the present invention should be based on the definition in the claims, and the description can be used to interpret the claims.

Claims

1. A sensor for measuring the liquid level in a marine fuel tank, characterized in that: The sensor comprises a mounting mechanism (1), a protective tube (2), a rectangular partition (3), a first capacitance measuring probe (41), a second capacitance measuring probe (42) and a signal acquisition and calculation processing module (5), wherein the mounting mechanism (1) is used to mount the entire sensor on the top of a tank or a side wall of a tank of a marine fuel tank (100); The top end of the protection tube (2) is fixedly connected to the installation mechanism (1), and the protection tube (2) is located in the interior space of the marine fuel tank (100) after the sensor is installed; The rectangular partition (3) is located inside the protective tube (2) and is parallel to the center line of the protective tube (2). The width of the rectangular partition (3) is consistent with the inner diameter of the protective tube (2). The length of the rectangular partition (3) is consistent with the length of the protective tube (2), so as to divide the internal space of the protective tube (2) into a first measurement space (21) and a second measurement space (22). The first capacitance measuring probe (41) is located in the first measuring space (21) and is spaced apart and parallel to the rectangular partition (3); the top end of the first capacitance measuring probe (41) is fixedly connected to the mounting mechanism (1); and the first capacitance measuring probe (41) is spaced apart from the wall of the protective tube (2); The second capacitance measuring probe (42) is located in the second measuring space (22) and is spaced apart and parallel to the rectangular partition (3); the top end of the second capacitance measuring probe (42) is fixedly connected to the mounting mechanism (1); the second capacitance measuring probe (42) is wrapped by an insulating layer and spaced apart from the wall of the protective tube (2); and the bottom end of the second capacitance measuring probe (42) is lower than the bottom end of the first capacitance measuring probe (41); The signal acquisition and calculation processing module (5) is fixed on the mounting mechanism (1) and has two input ends electrically connected to the output end of the first capacitance measuring probe and the output end of the second capacitance measuring probe (42) respectively.

2. The sensor according to claim 1, characterized in that The rectangular partition (3) and the first capacitance measuring probe (41) are respectively made of metal material, and the bottom end position of the first capacitance measuring probe (41) is slightly lower than the fuel outlet position or is flush with the fuel outlet position after the sensor is installed.

3. The sensor according to claim 1, characterized in that The installation mechanism (1) comprises an interpenetrating column (11), a flange (12), a cylindrical boss and a probe fixing ring, wherein the interpenetrating column (11) is used to be inserted into a mounting through hole located on the top of the cabin or on the side wall of the cabin during installation, the flange (12) is coaxially connected to the cabin outer end of the interpenetrating column (11) and is used to dock and fix with the cabin outer flange of the mounting through hole during installation, and the cylindrical boss is coaxially arranged on the cabin inner end surface of the interpenetrating column (11); The diameter of the cylindrical boss matches the inner diameter of the protective tube (2), and the top end of the protective tube (2) is fixedly connected to the mounting mechanism (1) by plugging and fitting with the cylindrical boss; A step hole is provided on the boss surface of the cylindrical boss, and the probe fixing ring is fixedly installed in the step hole. The top end of the first capacitance measuring probe (41) and the top end of the second capacitance measuring probe (42) are respectively fixed in the probe fixing ring through fixing joints to achieve fixed connection with the mounting mechanism (1).

4. The sensor according to claim 1, characterized in that A fixing ring (23) is installed at the bottom of the protective tube (2), and an insulating positioning frame is radially installed inside the fixing ring (23), wherein the insulating positioning frame is used to position the bottom of the rectangular partition (3) and the bottom of the second capacitance measuring probe (42).

5. The sensor according to claim 1, characterized in that The bottom end position of the protection tube (2) is lower than the fuel outlet position of the marine fuel tank (100) after the sensor is installed, and the height difference between the bottom end position of the protection tube (2) and the bottom end position of the second capacitance measuring probe (42) and the lowest position in the marine fuel tank (100) after the sensor is installed is between 5 and 15 mm.

6. The sensor according to claim 1, characterized in that A plurality of liquid-passing holes (24) are arranged in sequence from top to bottom at intervals on the cylinder walls of the first measuring space (21) and the second measuring space (22).

7. The sensor according to claim 1, characterized in that A plurality of insulating support frames (25) are respectively arranged on the two side surfaces of the rectangular partition (3) in sequence from top to bottom, wherein the insulating support frames (25) are used to fix and support the first capacitance measuring probe (41) or the second capacitance measuring probe (42) on the corresponding side.

8. The sensor according to claim 1, characterized in that The signal acquisition and calculation processing module (5) comprises a signal acquisition circuit board (51), a calculation processing circuit board, and a display (53) and a data transmission connector (54) located outside the cabin after the sensor is installed, wherein two input ends of the signal acquisition circuit board (51) are respectively electrically connected to the output end of the first capacitance measuring probe and the output end of the second capacitance measuring probe (42), the output end of the signal acquisition circuit board (51) is communicatively connected to the input end of the calculation processing circuit board, and two output ends of the calculation processing circuit board are respectively communicatively connected to the display (53) and the data transmission connector (54).

9. A method for operating the sensor according to any one of claims 1 to 8, characterized in that: After the sensor is installed, the signal acquisition and calculation processing module (5) performs the process, including a data calibration phase and a liquid level measurement phase; The data calibration stage includes: When the space inside the marine fuel tank (100) contains pure oil, for each of the multiple in-tank calibration liquid levels, a corresponding first capacitance calibration value is acquired through a first capacitance measuring probe (41), and a corresponding second capacitance calibration value is acquired through a second capacitance measuring probe (42); A first fitting function is obtained by fitting according to a one-to-one correspondence between the plurality of calibration liquid levels in the chambers and the plurality of calibration values ​​of the first capacitance, and a second fitting function is obtained by fitting according to a one-to-one correspondence between the plurality of calibration liquid levels in the chambers and the plurality of calibration values ​​of the second capacitance; saving the first fitting function and the second fitting function; The liquid level measurement stage includes: A first capacitance measurement value is acquired through a first capacitance measurement probe (41), and a second capacitance measurement value is acquired through a second capacitance measurement probe (42); determining a measured liquid level in a first chamber corresponding to the first capacitance measurement value based on the first fitting function, and determining a measured liquid level in a second chamber corresponding to the second capacitance measurement value based on the second fitting function; Determining whether the absolute value of the liquid level difference between the liquid level measured in the first chamber and the liquid level measured in the second chamber is less than a preset threshold; If it is less than, the average value of the measured liquid level in the first tank and the measured liquid level in the second tank is used as the fuel liquid level position of the marine fuel tank (100), and the oil-water interface position is determined to be below the bottom end position of the second capacitance measuring probe (42); otherwise, the measured liquid level in the first tank is used as the fuel liquid level position, and the oil-water interface position is determined to be between the bottom end position of the first capacitance measuring probe (41) and the bottom end position of the second capacitance measuring probe (42).

10. The working method according to claim 9, characterized in that: When the rectangular partition (3) and the first capacitance measuring probe (41) are respectively made of metal materials, and the bottom end position of the first capacitance measuring probe (41) is slightly lower than the fuel outlet position or is flush with the fuel outlet position after the sensor is installed, the working method further comprises: In the liquid level measurement phase and after a first capacitance measurement value is acquired through a first capacitance measurement probe (41), if it is determined that the first capacitance measurement value exceeds a capacitance calibration value range, the oil-water interface position is determined to be the bottom end position of the first capacitance measurement probe (41), and an alarm signal is issued, wherein the capacitance calibration value range is determined by a maximum value and a minimum value among a plurality of the first capacitance calibration values.

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