Intrinsically safe liquid level detection device and method and application

Abstract

The invention relates to an intrinsically safe liquid level detection device and method and application, and belongs to the technical field of liquid level measurement and safety monitoring. The device comprises a mechanical sensing assembly, a magnetic floater assembly and an electrical processing assembly. The mechanical sensing assembly is provided with a non-metal tube body which is internally encapsulated and sealed, and a circuit substrate with a plurality of magnetic control switch elements is arranged in the non-metal tube body. The magnetic floater assembly comprises an annular floater which is sleeved outside the pipe and is internally provided with a magnet. The electrical processing assembly is electrically connected with the mechanical sensing assembly and comprises an isolation power supply module, a signal acquisition module, a controller, a signal output module and a power supply management module. During working, the floater moves along with the liquid level to drive the magnet to trigger the magnetic control switch at the corresponding position in the pipe, and after signals are isolated, collected and processed, the controller drives the signal output module to generate 4-20 mA standard current signals. Through integral sealing and intrinsic safety circuit design, the explosion-proof requirement of an explosive environment is fundamentally met, and the explosion-proof device has the advantages of being high in reliability, high in environmental adaptability and standard in output.

Description

Technical Field

[0001] This invention belongs to the field of electronic equipment, specifically relating to an intrinsically safe liquid level detection device, method, and application. Background Technology

[0002] In the coal mining industry, hydraulic control systems are widely used in various types of mechanical equipment. To meet the explosion-proof and safety requirements underground, these systems often use a mixed emulsion with water as the main component as the hydraulic fluid. The liquid level in the reservoir or tank is a key parameter for ensuring the stable operation of the hydraulic system; therefore, the liquid level measuring device becomes an indispensable monitoring component in the system. This device not only needs to have high measurement reliability to ensure the normal operation and early warning function of the system, but also must meet the stringent intrinsic safety explosion-proof standards in underground coal mines, that is, the circuit design and structure must ensure that no electrical sparks or thermal effects sufficient to ignite an explosive atmosphere will be generated under any fault condition.

[0003] Currently, traditional technologies used for liquid level detection mainly include radar detection, float detection, and Hall sensor detection. However, in the special application scenario of underground coal mines, these traditional technologies all have limitations to varying degrees: their electrical performance does not meet intrinsic safety requirements, their structures are at risk of failure, they have low environmental adaptability, and they require strict calibration. Summary of the Invention

[0004] The purpose of this invention is to provide an intrinsically safe liquid level detection device, method, and application to overcome the above-mentioned technical defects.

[0005] To solve the above-mentioned technical problems, the present invention provides an intrinsically safe liquid level detection device, comprising: The mechanical sensing assembly includes a non-metallic sealed tube, a circuit board disposed inside the sealed tube, and a plurality of magnetically controlled switching elements spaced apart along the length of the circuit board. A magnetic float assembly includes a float movable along the outside of the sealed tube and a magnet disposed within the float, the float being adapted to float on the surface of the liquid to be tested; An electrical processing component, electrically connected to the mechanical sensing component, is used to receive the switching status signals of each of the magnetically controlled switching elements, and output an electrical signal related to the liquid level based on the position information of the triggered magnetically controlled switching elements. When the magnet moves with the float, it can trigger the magnetically controlled switch element at the corresponding position inside the sealed tube to generate a corresponding switching signal.

[0006] According to an intrinsically safe liquid level detection device, the mechanical sensing component further includes: A multi-core wire harness, one end of which is electrically connected to each of the magnetically controlled switching elements, and the other end of which passes through the opening of the sealed tube and is connected to the electrical processing assembly; And a sealing potting compound, which is filled into the sealing tube to wrap and fix the circuit board, the magnetic switch element, and the end connection points of the multi-core wire harness located in the sealing tube.

[0007] According to an intrinsically safe liquid level detection device, the electrical processing component includes: An isolated power supply module has its input connected to a power management module, and its output provides electrically isolated operating power to the input side of the mechanical sensing component and the signal acquisition module. The signal acquisition module includes multiple optocouplers, each with its input connected to a corresponding magnetically controlled switch element and receiving power from the isolated power supply module. It acquires the switching states of each magnetically controlled switch element and performs electrical isolation conversion. The output of each optocoupler outputs a switching level signal corresponding to the switching state. A controller, connected to the output of the signal acquisition module, receives and processes the switching level signals from each magnetically controlled switch element to determine the liquid level of the liquid under test and generate control commands. A signal output module, connected to the controller, outputs a standard current signal proportional to the liquid level of the liquid under test according to the control commands. The power management module provides operating power to the controller and the signal output module, and also supplies power to the isolated power supply module.

[0008] According to an intrinsically safe liquid level detection device, the standard current signal is a 4-20mA current signal; The signal output module is a current output circuit based on a digital-to-analog converter and is connected to the controller via a digital communication interface.

[0009] According to an intrinsically safe liquid level detection device, the sealing tube is made of flame-retardant engineering plastic; The magnetically controlled switch element is a normally open reed switch; The float is an annular float, which is fitted outside the sealing tube.

[0010] According to an intrinsically safe liquid level detection device, a plurality of reed switches are arranged at equal intervals on a circuit board, the circuit board being a long strip-shaped printed circuit board.

[0011] This invention also provides a method for measuring liquid level using an intrinsically safe liquid level detection device, comprising: vertically setting the mechanical sensing assembly in the container to be measured, so that the float of the magnetic float assembly floats on the surface of the liquid to be measured; the liquid level change causes the float and the magnet to move along the sealed tube of the mechanical sensing assembly; triggering the magnetic control switch element corresponding to its position in the sealed tube to change its state through the magnet; collecting the state of all the magnetic control switch elements through the electrical processing assembly, identifying the position of the triggered magnetic control switch element; determining the current liquid level height based on the position information of the triggered magnetic control switch element, and generating an output electrical signal corresponding to the liquid level height.

[0012] According to a method for measuring liquid level using an intrinsically safe liquid level detection device, the step of generating an output electrical signal corresponding to the liquid level height includes: The liquid level information is converted into a control command, which is then sent by the controller to the signal output module to drive the signal output module to generate a 4-20mA standard current signal corresponding to the liquid level.

[0013] The present invention also provides an application of an intrinsically safe liquid level detection device in a hydraulic system, wherein the intrinsically safe liquid level detection device is applied to a coal mine underground hydraulic control system that uses water-based emulsion as the working medium to measure the liquid level in its storage tank or water tank. The mechanical sensing components of the device are vertically submerged and fixed in the water storage tank or the water tank, the magnetic float component floats on the liquid surface, and the electrical processing components are located in a safe area or an intrinsically safe enclosure. The device monitors or controls the hydraulic control system through the liquid level-related electrical signals output by the device.

[0014] The beneficial effects of this invention are as follows: (1) The present invention provides strict electrical isolation between the sensing part (mechanical sensing component) and the processing part (electrical processing component) through an optocoupler, and provides an independent isolated power supply for the sensing part. At the same time, the mechanical structure adopts fully sealed potting and flame-retardant materials, eliminating the risk of electric sparks and overheating from both the circuit energy and physical structure levels, and fully meeting the mandatory requirements of "intrinsically safe" in explosive environments such as underground coal mines.

[0015] (2) Multiple discrete reed switches are used as sensing elements and triggered by a magnetic float. This is a non-contact sensing method without mechanical wear, which avoids the jamming and wear problems of traditional float-type level gauges. The sensor is completely encapsulated in a robust sealed tube, which is waterproof, moisture-proof, and corrosion-proof. It is not sensitive to environmental dust, humidity, and vibration, which significantly improves the long-term reliability and lifespan in harsh industrial environments.

[0016] (3) This invention eliminates the need for precise calibration and signal processing algorithms required by complex detection technologies such as radar and ultrasound. Its liquid level judgment is based on the on / off state of the reed switch, and the signal processing is simple and reliable. At the same time, the modular design (mechanical sensing components, magnetic float components, electrical processing components) is clear, and it is easy to diagnose and replace parts in case of failure, reducing maintenance difficulty and cost.

[0017] To make the above description of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of an intrinsically safe liquid level detection device.

[0019] Figure 2 This is a schematic diagram of the electrical processing components.

[0020] Figure 3 This is a flowchart of a method for measuring liquid level using an intrinsically safe liquid level detection device.

[0021] Explanation of reference numerals in the attached figures: 10. Mechanical sensing components; 11. Sealed tubes; 12. Circuit boards; 13. Magnetic switching elements; 14. Multi-core wire harnesses; 20. Magnetic levitation assembly; 21. Float; 22. Magnet; 30. Electrical processing components; 31. Isolated power supply module; 32. Signal acquisition module; 33. Controller; 34. Signal output module; 35. Power management module. Detailed Implementation

[0022] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0023] It should be noted that, in this invention, the top, bottom, left, and right in the figure are considered to be the top, bottom, left, and right of the intrinsically safe liquid level detection device described in this specification.

[0024] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0025] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0026] This embodiment relates to an intrinsically safe liquid level detection device (hereinafter referred to as the device). Please refer to Figure 1 It includes a mechanical sensing component 10, a magnetic levitation component 20, and an electrical processing component 30.

[0027] The mechanical sensing component 10 is the sensing part of the device, responsible for converting the liquid level height into a detectable electrical signal. It includes a non-metallic sealed tube 11 made of flame-retardant engineering plastic.

[0028] In some embodiments, the sealing pipe 11 is a straight pipe made of flame-retardant nylon fiber reinforced material with a diameter of 30 mm, an inner diameter of 20 mm, and a length of 1600 mm. It has good mechanical strength, corrosion resistance and flame retardant properties, and meets the safety requirements of downhole.

[0029] The mechanical sensing assembly 10 also includes a circuit board 12 disposed inside the sealed tube 11.

[0030] In some embodiments, a long strip-shaped circuit board 12, such as a printed circuit board 1500 mm long and 19 mm wide, is disposed inside the sealed tube 11 along its axial direction.

[0031] On the circuit board 12, a plurality of magnetically controlled switching elements 13 are arranged along its length at predetermined intervals (e.g., equal spacing of 100 mm). In this embodiment, these magnetically controlled switching elements 13 are preferably normally open reed switches of model GPS-14A, totaling 15. As a type of magnetically sensitive switch, the state (closed or open) of the reed switch is controlled by an external magnetic field.

[0032] To ensure long-term stable operation in a liquid environment, the mechanical sensing assembly 10 also includes a sealing potting compound encapsulated within the sealing tube 11. Figure 1 (Not separately indicated, but can be considered as filler). This sealing potting compound, such as flame-retardant resin, is used to wrap and fix the circuit board 12, all magnetically controlled switching elements 13, and related electrical connection points, achieving sealing and waterproofing of the entire sensing assembly. In addition, the mechanical sensing assembly 10 also includes a multi-core wire bundle 14 ( Figure 1(The part leading out from the tube). One end of the multi-core wire bundle (the end inside the tube) is electrically connected to each magnetic switch element 13 by welding or other means; the other end passes through the opening of the sealed tube 11 and is used to connect to the external electrical processing assembly 30. The sealing potting compound also seals and fixes the connection points of this multi-core wire bundle 14 inside the tube.

[0033] In some embodiments, the multi-core wire harness 14 uses high-temperature Teflon wires, and the harness has 16 strands, which are respectively connected to each magnetic control switch element 13. The opening or closing of the magnetic control switch element 13 can form a switch signal that is output through each wire harness.

[0034] "15 reed switches" refers to the number of sensing units, which determines the measurement resolution of the device (one detection point per 100mm). "16 wires" refers to the minimum and optimal number of electrical channels required to transmit these 15 switch signals. The 15 wires correspond to 15 independent signal channels, and the 16th wire is a common loop.

[0035] The magnetic float assembly 20 is the liquid level driving and magnetic triggering part of the device. It includes an annular float 21, which is sleeved on the outside of the sealing tube 11 of the mechanical sensing assembly 10 and can move freely vertically up and down along the outer wall of the sealing tube 11. The float 21 contains a strong magnet 22, such as a permanent magnet. The float 21 floats on the surface of the liquid to be measured, and its position changes with the liquid level. When the liquid level changes, the float 21 drives the internal magnet 22 to move synchronously along the sealing tube 11.

[0036] The electrical processing component 30 is the circuit part of the device for signal processing and output. It is electrically connected to the mechanical sensing component 10 via the aforementioned multi-core wire harness 14. The electrical processing component 30 is used to receive the switching status signal from each magnetic control switching element 13, and to process and analyze all signals according to the position information of the triggered magnetic control switching element 13, and finally output a standard electrical signal related to the current liquid level height.

[0037] When the magnet 22 moves with the float 21, it can trigger the magnetic control switch element 13 at the corresponding position in the sealed tube 11 to generate a corresponding switch signal.

[0038] The intrinsically safe liquid level detection device operates on the following principle: When the magnetic float assembly 20 moves with the liquid level, the magnetic field generated by the magnet 22 inside it can penetrate the wall of the sealed tube 11 made of non-metallic material and act on the internal magnetic control switching element 13. When the magnet 22 moves to the vicinity of a corresponding position of a magnetic control switching element 13 (e.g., a reed switch), the reed switch closes under the action of the magnetic field; when the magnet 22 moves away, the reed switch opens again. The closing or opening of each reed switch generates a corresponding switching signal, which is transmitted to the electrical processing assembly 30 through its independent wire. The electrical processing assembly 30 can accurately determine the current position of the magnet 22, i.e., the liquid level height, by identifying the element in the highest closed position among all the reed switches. Finally, the electrical processing assembly 30 converts this position information into a standard 4-20mA current signal output for use by subsequent monitoring or control systems.

[0039] The electrical processing component 30 is the circuit part of the device that performs signal processing and output. It is responsible for receiving switching signals from the mechanical sensing component 10, isolating, analyzing, converting, and ultimately outputting standard industrial signals. Please refer to... Figure 2 It specifically includes the following functional modules: (1) Isolation power supply module 31, whose input end is connected to power management module 35, and whose output end provides electrically isolated working power to the input side of mechanical sensing component 10 and signal acquisition module 32.

[0040] Specifically, the isolated power supply module 31 is a key module ensuring the entire device meets the "intrinsic safety" requirements. Its input is connected to the power management module 35 to obtain initial power. Its function is to generate an output voltage that is completely electrically isolated from the input, through an internal isolation conversion circuit (e.g., based on a B2424S-1WR2 power chip design). This isolated output is dedicated to powering the mechanical sensing components 10 (i.e., all reed switches) on the hazardous side and the input side of the signal acquisition module 32 (i.e., the circuit containing the LEDs inside the optocoupler). This design ensures that even if a short circuit or fault occurs in the sensing circuit, the released energy is far below the minimum energy required to ignite an explosive mixture, thus achieving intrinsic safety at the circuit level.

[0041] (2) The signal acquisition module 32 includes multiple optocouplers. The input terminal of each optocoupler is connected to the corresponding magnetic control switch element 13 and receives power from the isolation power supply module 31. It is used to acquire the switching state of each magnetic control switch element 13 and perform electrical isolation conversion. The output terminal of each optocoupler outputs the switching level signal corresponding to the switching state.

[0042] Specifically, the signal acquisition module 32 is responsible for safely and reliably reading the state of each magnetically controlled switch element 13. It includes multiple optocouplers (e.g., TLP2301 model optocouplers), with the number corresponding to the number of magnetically controlled switch elements 13. The two pins of the input terminal (i.e., the LED side) of each optocoupler are connected to the two ends of the corresponding reed switch (e.g., through the corresponding lines in the aforementioned 16-strand wire bundle), thus forming an independent sensing circuit powered by the isolation power supply module 31. When a reed switch closes under the action of the magnet 22, its circuit is activated, driving the LED inside the corresponding optocoupler to emit light, completing the "electro-optical" conversion; when the reed switch opens, the circuit is broken, and the LED turns off. The output terminal of the optocoupler (i.e., the phototransistor side) generates a corresponding high or low level switching signal depending on whether light is received. This process enables the switching state of the dangerous side to be transmitted to the safe side without electrical connection through the insulating medium of "light," completing the crucial electrical isolation and signal conversion.

[0043] (3) The controller 33 is connected to the output terminal of the signal acquisition module 32 to receive and process the switching level signals of each magnetic control switch element 13 to determine the liquid level of the liquid to be measured and generate control commands.

[0044] The controller 33 is the information processing center of the device. In this embodiment, a low-power microcontroller, such as an MSP430F4152 digital signal processor (MCU), can be used. It is connected to the output terminals of all optocouplers in the signal acquisition module 32, scanning and reading these switching level signals in real time. By analyzing these signals, the controller 33 identifies the highest-positioned reed switch (or reed switch combination) that is currently in the closed state, and then calculates the precise liquid level height value based on the known installation spacing and position of the reed switches. Then, the controller 33 generates corresponding digital control commands based on this liquid level value.

[0045] (4) The signal output module 34 is connected to the controller 33 and is used to output a standard current signal proportional to the liquid level of the liquid to be measured according to the control command.

[0046] Specifically, the signal output module 34 is responsible for converting the digital commands of the controller 33 into standard analog signals recognizable in the industrial environment. In this embodiment, the module is specifically designed as a 4-20mA current output circuit, which can be a digital-to-analog converter chip, such as the DAC161P997CISQ. The controller 33 sends control commands to this chip via a digital communication interface (such as an SPI bus). Based on the commands, the signal output module 34 generates a DC current signal that is linearly proportional to the current liquid level and varies between 4mA and 20mA. This 4-20mA standard current signal has the advantages of strong anti-interference capability and long transmission distance, and can be directly connected to a PLC, DCS, or mine monitoring system.

[0047] (5) The power management module 35 is used to provide working power to the controller 33 and the signal output module 34, and to supply power to the isolation power module 31.

[0048] Specifically, the power management module 35 provides a stable operating power supply for all circuits on the safety side. It receives external DC power input and, through voltage regulation and filtering circuits (e.g., based on the TPS7A1601DGN power chip design), generates the various voltages required by the output sides of the controller 33, the signal acquisition module 32, and the signal output module 34. Simultaneously, it also provides input power to the isolated power supply module 31.

[0049] In some implementations, the standard current signal is a 4-20mA current signal. This current signal is less susceptible to line resistance and electromagnetic interference during transmission, enabling reliable long-distance transmission.

[0050] To achieve accurate output of this standard signal, in a preferred embodiment of the present invention, the signal output module 34 is specifically designed as a current output circuit based on a digital-to-analog converter (DAC). This circuit can be a dedicated current-output type DAC chip, such as the DAC161P997CISQ. This chip can receive digital commands and directly output a proportional current.

[0051] The signal output module 34 and the controller 33 are connected and exchange data via a digital communication interface. Specifically, the controller 33 (MCU) sends digital control commands representing the target liquid level or target current value to the digital-to-analog converter chip at high speed and reliably via a synchronous serial communication bus such as SPI (Serial Peripheral Interface). Compared with traditional parallel bus or voltage control methods, this digital interface connection method has advantages such as simple wiring, strong anti-interference ability, and easy implementation of electrical isolation (e.g., through digital isolators), further enhancing the system's reliability and the flexibility of intrinsically safe design.

[0052] After receiving the digital command, the digital-to-analog converter activates its internal circuitry, driving the output stage to generate the required current. The entire current output circuit is designed to ensure that its output current remains stable within the specified load range and maintains a linear relationship with the command value given by the controller 33, thereby accurately mapping the liquid level information into a standard 4-20mA current signal.

[0053] This embodiment also provides a method for measuring liquid level using an intrinsically safe liquid level detection device. Please refer to [link to relevant documentation]. Figure 3 The process includes: Step 100, vertically setting the mechanical sensing component 10 in the container to be tested, so that the float 21 of the magnetic float component 20 floats on the surface of the liquid to be tested.

[0054] The mechanical sensing assembly 10 is vertically fixed inside the container to be tested, such as a water tank or reservoir. During installation, it must be ensured that the axis of its sealing tube 11 is parallel to the direction of gravity, and that the effective measuring section with the magnetically controlled switching element 13 completely covers the possible range of changes in the liquid level to be measured. Subsequently, the annular float 21 of the magnetic float assembly 20 is placed outside the sealing tube 11, allowing it to float on the initial surface of the liquid to be measured inside the container. The electrical processing assembly 30 is typically installed outside the container or in a dedicated intrinsically safe junction box, and is reliably connected to the mechanical sensing assembly 10 via a multi-core wire harness 14 to complete system power-on and initialization.

[0055] Step 200: The change in liquid level causes the float 21 and magnet 22 to move along the sealed tube 11 of the mechanical sensing component 10.

[0056] When the liquid level in the container being measured changes, the float 21 floating on the liquid surface moves synchronously with the liquid surface under the action of buoyancy. The float 21 drives the magnet 22 embedded inside it to move vertically along the outer wall of the sealed tube 11 of the mechanical sensing component 10.

[0057] Step 300: The magnet 22 triggers the magnetically controlled switch element 13 inside the sealed tube 11, which corresponds to its position, to change its state.

[0058] As the magnet 22 moves, the magnetic field it generates penetrates the wall of the non-metallic sealed tube 11 and acts on the internal circuit board 12. When the magnet 22 moves close enough to a magnetically controlled switch element 13, the reed switch's internal spring is attracted by the magnetic field, changing from a normally open state to a closed state. When the magnet 22 moves away from the reed switch, the spring returns to its original position under its own elastic force, and the reed switch returns to the open state. Therefore, at any given time, only one or a few adjacent reed switches inside the sealed tube 11 are in a closed state triggered by the magnet 22, and the position of the closed reed switch uniquely corresponds to the instantaneous height of the magnet 22 (i.e., the liquid level).

[0059] Step 400: The electrical processing component 30 collects the status of all magnetic control switching elements 13 and identifies the position of the triggered magnetic control switching element 13.

[0060] The electrical processing component 30 operates continuously. Its signal acquisition module 32 acquires the real-time on / off status of all magnetically controlled switching elements 13 in parallel via a multi-core wire bundle 14. The on / off signal of each reed switch is electrically isolated and level-converted by the corresponding optocoupler before being sent to the controller 33. The controller 33 performs a cyclic scan or interrupt response to all these discrete switching inputs, and through logical judgment (e.g., finding the reed switch with the highest address in the closed state), uniquely identifies the magnetically controlled switching element 13 currently triggered by the magnet 22 (or the two in the boundary state) from all the reed switches, thereby determining the discrete position coordinates of the magnet 22 in the axial direction of the sealing tube 11.

[0061] Step 500: Determine the current liquid level height based on the position information of the triggered magnetic switch element 13, and generate an output electrical signal corresponding to the liquid level height.

[0062] The controller 33 converts the identified position number of the triggered magnetic switch element 13 into a specific, continuous liquid level height value based on pre-stored device parameters (such as the installation zero point height of the first reed switch and the fixed spacing between reed switches). Then, the controller 33 generates a corresponding digital control command based on this liquid level height value according to a predetermined mapping relationship (such as linear proportional or lookup table method). This control command is sent to the signal output module 34 via a digital communication interface. The signal output module 34 (its current output circuit) is driven by the control command and generates a 4-20mA standard current signal corresponding to the current liquid level height. Finally, this standard electrical signal representing the liquid level is output to the subsequent monitoring system, completing a full liquid level measurement and transmission process.

[0063] The steps for generating an output electrical signal corresponding to the liquid level height include: converting the liquid level height information into a control command, sending the control command from the controller 33 to the signal output module 34, and driving the signal output module 34 to generate a 4-20mA standard current signal corresponding to the liquid level height.

[0064] Specifically, after calculating the liquid level, the controller 33 converts the liquid level information into specific digital control commands. Then, the controller 33 sends these control commands to the signal output module 34 via its built-in digital communication interface (such as the SPI bus). This transmission process is high-speed and precise digital communication, ensuring the real-time performance and accuracy of the command transmission. Upon receiving the control commands from the controller 33, the signal output module 34's internal circuitry (such as the current output circuit based on the digital-to-analog converter described above) is driven and begins operation. The digital-to-analog converter parses the commands, and its internal reference source, digital-to-analog conversion core, and output drive circuit work together to generate a stable 4-20mA standard current signal that strictly corresponds to the current liquid level.

[0065] This invention also provides an application of an intrinsically safe liquid level detection device in a hydraulic system. The intrinsically safe liquid level detection device is applied to a coal mine underground hydraulic control system that uses water-based emulsion as the working medium to measure the liquid level in its reservoir or tank.

[0066] The device's mechanical sensing component 10 is vertically submerged and fixed in a water storage tank or reservoir, the magnetic float component 20 floats on the liquid surface, and the electrical processing component 30 is located in a safe area or intrinsically safe enclosure. The device monitors or controls the hydraulic control system through the liquid level-related electrical signals output by the device.

[0067] In this application scenario, the installation and deployment of the device are as follows: The mechanical sensing component 10 is vertically submerged and securely fixed inside a water storage tank or reservoir. Typically, the top of its sealing pipe 11 is connected to the top of the tank via a flange or bracket, ensuring that its measuring section remains within the range of possible liquid level changes throughout. The magnetic buoy component 20 floats naturally on the surface of the water-based emulsion and is fitted over the mechanical sensing component 10. The critical electrical components 30, in accordance with coal mine safety regulations, are located in a safe area underground or installed within an intrinsically safe explosion-proof enclosure, thereby ensuring that the electrical components are in an absolutely safe state in potentially hazardous environments.

[0068] After the above installation, the device begins operation. It monitors the water level in the tank in real time and ultimately transmits the water level information to the control section of the hydraulic control system or the mine's centralized monitoring center via an electrical signal (specifically a 4-20mA standard current signal) output by the device, which is strictly corresponding to the water level height. This system can use this signal to monitor the hydraulic control system in real time, thereby ensuring the stable, safe, and efficient operation of the underground hydraulic power system in the coal mine.

[0069] This invention, through its fully sealed structure and intrinsically safe circuit design, thoroughly meets the inherent safety requirements of underground coal mines. Employing a non-contact magnetic trigger and discrete switch array, it overcomes the problems of traditional level gauges such as jamming and the need for calibration, significantly improving long-term reliability, measurement accuracy, and maintenance convenience in harsh environments. The output standard 4-20mA signal has excellent system compatibility, providing a highly safe, reliable, and easy-to-implement solution for level monitoring in high-risk industrial environments.

[0070] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. An intrinsically safe liquid level detection device, characterized in that, include: The mechanical sensing assembly (10) includes a non-metallic sealed tube (11), a circuit board (12) disposed inside the sealed tube (11), and a plurality of magnetically controlled switching elements (13) arranged at intervals along the length of the circuit board (12). The magnetic float assembly (20) includes a float (21) movable along the outside of the sealed tube (11) and a magnet (22) disposed within the float (21), the float (21) being adapted to float on the surface of the liquid to be tested; The electrical processing component (30) is electrically connected to the mechanical sensing component (10) and is used to receive the switching status signals of each of the magnetic control switching elements (13) and output an electrical signal related to the liquid level according to the position information of the triggered magnetic control switching element (13). When the magnet (22) moves with the float (21), it can trigger the magnetic control switch element (13) at the corresponding position in the sealed tube (11) to generate a corresponding switch signal.

2. The intrinsically safe liquid level detection device according to claim 1, characterized in that, The mechanical sensing component (10) further includes: A multi-core wire harness (14) is provided, one end of which is electrically connected to each of the magnetic control switch elements (13), and the other end of which passes through the opening of the sealing tube (11) and is connected to the electrical processing assembly (30). And a sealing potting compound filled in the sealing tube (11) for wrapping and fixing the circuit board (12), the magnetic switch element (13) and the end connection points of the multi-core wire harness located in the sealing tube (11).

3. The intrinsically safe liquid level detection device according to claim 1, characterized in that, The electrical processing component (30) includes: An isolated power supply module (31) has its input end connected to a power management module (35), and its output end provides electrically isolated operating power to the input side of the mechanical sensing component (10) and the signal acquisition module (32). The signal acquisition module (32) includes multiple optocouplers, the input end of each optocoupler is connected to the corresponding magnetic control switch element (13), and receives power from the isolated power supply module (31). It is used to acquire the switching state of each magnetic control switch element (13) and perform electrical isolation conversion. The output end of each optocoupler outputs a signal corresponding to the switching state. The corresponding switching level signal; the controller (33), connected to the output terminal of the signal acquisition module (32), is used to receive and process the switching level signals of each of the magnetic control switching elements (13) to determine the liquid level of the liquid to be tested and generate control commands; the signal output module (34), connected to the controller (33), is used to output a standard current signal proportional to the liquid level of the liquid to be tested according to the control commands; the power management module (35) is used to provide working power to the controller (33) and the signal output module (34), and to power the isolated power module (31).

4. The intrinsically safe liquid level detection device according to claim 3, characterized in that, The standard current signal is a 4-20mA current signal; The signal output module (34) is a current output circuit based on a digital-to-analog converter and is connected to the controller (33) through a digital communication interface.

5. The intrinsically safe liquid level detection device according to claim 4, characterized in that, The sealing tube (11) is made of flame-retardant engineering plastic; The magnetically controlled switch element (13) is a normally open reed switch; The float (21) is an annular float, which is sleeved on the outside of the sealing tube (11).

6. The intrinsically safe liquid level detection device according to claim 5, characterized in that, The plurality of reed switches are arranged at equal intervals on the circuit board (12), which is a long strip printed circuit board.

7. A method for measuring liquid level using an intrinsically safe liquid level detection device as described in any one of claims 3 to 6, characterized in that, include: The mechanical sensing component (10) is vertically placed in the container to be tested, so that the float (21) of the magnetic float component (20) floats on the surface of the liquid to be tested; the change in liquid level causes the float (21) and the magnet (22) to move along the sealed tube (11) of the mechanical sensing component (10); the magnet (22) triggers the magnetic control switch element (13) in the sealed tube (11) corresponding to its position to change its state; the electrical processing component (30) collects the state of all the magnetic control switch elements (13) and identifies the position of the triggered magnetic control switch element (13); based on the position information of the triggered magnetic control switch element (13), the current liquid level height is determined, and an output electrical signal corresponding to the liquid level height is generated.

8. The method for measuring liquid level using an intrinsically safe liquid level detection device according to claim 7, characterized in that, The step of generating an output electrical signal corresponding to the liquid level height includes: The liquid level information is converted into a control command, which is then sent by the controller (33) to the signal output module (34) to drive the signal output module (34) to generate a 4-20mA standard current signal corresponding to the liquid level.

9. The application of an intrinsically safe liquid level detection device in a hydraulic system, characterized in that, The intrinsically safe liquid level detection device according to any one of claims 1 to 6 is applied to a coal mine underground hydraulic control system that uses water-based emulsion as the working medium to measure the liquid level in its storage tank or water tank. The mechanical sensing component (10) of the device is vertically submerged and fixed in the water storage tank or the water tank, the magnetic float component (20) floats on the liquid surface, and the electrical processing component (30) is set in a safe area or an intrinsically safe enclosure. The device outputs an electrical signal related to the liquid level to monitor or control the hydraulic control system.

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