Control circuit of electrode type liquid level gauge, electrode type liquid level gauge and control method thereof

Abstract

The present invention relates to the technical field of liquid level meters, and in particular to a control circuit of an electrode type liquid level meter and an electrode type liquid level meter and a control method thereof, comprising: at least one electrode switching module, the electrode switching module including two input terminals for obtaining electrode signals of a first electrode and a second electrode, the electrode signals being converted into input signals of a control circuit by the electrode switching module; the electrode switching module transmitting the input signal to an MCU control module, the MCU control module timing and processing the transmission time of the input signal, and when the transmission time of the input signal is within a first threshold time set by the MCU control module, the MCU control module outputs a control signal to the electrode switching module, the electrode switching module receives and executes the control signal, and switches the properties of the first input terminal and the second input terminal; a power supply module for supplying power to each block. The control circuit of the electrode type liquid level meter provided by the present invention controls each electrode to be free of oxidation, scaling or less scaling, and the control circuit itself is safe.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid level gauges, and in particular to a control circuit of an electrode type liquid level gauge, an electrode type liquid level gauge and a control method thereof. Background Art

[0002] Existing electrode-type liquid level gauges are generally subject to severe deterioration in the quality of sampled water during use, resulting in electrical corrosion of the electrode metal rod tip, and defects such as scaling and creepage. When the circuit uses the electrode principle for water level detection, the electrode metal rod carries an electric charge, which will produce water electrolysis on the surface of the electrode metal rod. The positively charged electrode metal rod produces oxygen, and the negatively charged electrode metal rod produces hydrogen. The volume ratio of hydrogen to oxygen is 1:2, which is an imbalance. In addition, oxygen has an oxidizing effect on metals, causing the electrode metal rod to easily oxidize and scale during use, making the electrode-type liquid level gauge measurement unstable. To ensure that the electrode data collection is not affected and the electrode can be used normally, the critical water resistance needs to be frequently adjusted. The adjustment of the critical water resistance shortens the service life of the electrode, so the electrode needs to be disassembled. The electrode metal rod is installed in the electrode container, which is not convenient for disassembly. The electrode is immersed in the conductive liquid for a long time. There are few electrode-type liquid level measurement devices on the market that do not oxidize the electrode surface or do not produce scale or produce little scale on the surface.

[0003] In addition, after a period of use, electrode-type liquid level gauges can produce bubbles that wrap around the metal rod of the detection electrode, causing large measurement errors and even complete failure of the detection equipment, posing a certain safety hazard. This is because the current circuit design does not have anti-reverse polarity function, energy limiting function, and overcurrent, overvoltage, short circuit and other protection functions. The circuit design does not guarantee the reliability and safety of the circuit and cannot meet the requirements of a safety circuit. In the event of misoperation or failure, the electrode-type liquid level gauge itself cannot be safe. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: in order to solve the technical problem that the electrodes of an electrode-type liquid level gauge are easily oxidized and scaled when immersed in water for a long time, and the electrode-type liquid level gauge itself is unsafe in the event of misoperation or failure, the present invention provides an electrode switching circuit, an electrode-type liquid level gauge and an electrode switching control method, which control each electrode to prevent oxidation, scale or less scale, effectively solve the problem of unstable electrode signal acquisition caused by ion adsorption, impurity adsorption and bubble generation by the electrode, and the circuit itself is safe.

[0005] The technical solution adopted by the present invention to solve its technical problem is: a control circuit of an electrode-type liquid level gauge, the control circuit comprising: at least two electrodes; at least one electrode switching module, the electrode switching module comprising two input ends, namely a first input end and a second input end, the first input end being connected to the first electrode, and the second input end being connected to the second electrode, for obtaining electrode signals of the first electrode and the second electrode, the electrode signals being converted into input signals of the control circuit by the electrode switching module; an MCU control module connected to the electrode switching module, the electrode switching module transmitting the input signal to the MCU control module, the MCU control module timing and processing the transmission time of the input signal, when the transmission time of the input signal is within a first threshold time set by the MCU control module, the MCU control module outputting a control signal to the electrode switching module, the electrode switching module receiving and executing the control signal, and the electrode switching module switching the attributes of the first input end and the second input end; a power supply module, the electrode switching module and the MCU control module are both electrically connected to the power supply module, the power supply module being used to supply power to the electrode switching module and the MCU control module.

[0006] Further, specifically, the power supply module includes: an anti-reverse unit, at least one level of overcurrent and overvoltage protection unit, an energy consumption limiting unit and a power conversion unit; the anti-reverse unit, the overcurrent and overvoltage protection unit, the energy consumption limiting unit and the power conversion unit are connected in sequence.

[0007] Furthermore, specifically, the control circuit further includes:

[0008] A door dog module is connected to the MCU control module and is used to periodically detect the MCU control module. When the MCU control module is in a dead loop, the door dog module sends a restart signal to the MCU control module. A relay output module is connected to the MCU control module. When the MCU control module processes the transmission time of the input signal, the MCU control module controls the output of the relay output module. A communication module is used. The MCU control module is connected to an external device through a communication module signal.

[0009] Further, specifically, the power supply module further includes a power isolation unit, one end of the power isolation unit is connected to the power conversion unit, and the other end is connected to the electrode switching module.

[0010] Further, specifically, the electrode switching module includes: a switching switch unit, a comparison unit, a first optocoupler isolation unit and a second optocoupler isolation unit; the switching switch unit, the comparison unit and the first optocoupler isolation unit are connected in sequence; the switching switch unit is respectively connected to the first input end and the second input end, and the switching switch unit obtains the electrode signal and transmits it to the comparison unit, and the comparison unit compares the electrode signal; if the conditions are met after comparison, the electrode signal is transmitted to the first optocoupler isolation unit, and the first optocoupler isolation unit receives the electrode signal and performs optocoupler isolation processing on the electrode signal, and the processed electrode signal is the input signal; on the contrary, if the conditions are not met after comparison, the electrode signal continues to be obtained; the second optocoupler isolation unit is respectively connected to the MCU control module and the switching switch unit, and the MCU control module transmits the control signal to the second optocoupler isolation unit for optocoupler isolation processing, and transmits the processed control signal to the switching switch unit, and the switching switch unit executes the control signal to switch the properties of the first input end and the second input end.

[0011] Further, specifically, the control circuit includes two electrode switching modules and three electrodes; the two electrode switching modules are respectively a first electrode switching module and a second electrode switching module, and the structures and circuit connections of the first electrode switching module and the second electrode switching module are the same; the three electrodes are respectively a first electrode, a second electrode and a third electrode, and the two input ends of the first electrode switching module are respectively connected to the first electrode and the second electrode, and the two input ends of the second electrode switching module are respectively connected to the second electrode and the third electrode.

[0012] Further, specifically, the power supply module includes two levels of overcurrent and overvoltage protection units, the positive terminal of the output end of the previous level overcurrent and overvoltage protection unit is connected to the positive terminal of the input end of the next level protection circuit, and the output negative terminal of the previous level protection circuit is connected to the input negative terminal of the next level protection circuit.

[0013] An electrode-type liquid level gauge comprises: a control box body and a cover body detachably assembled to the control box body, wherein a circuit board is provided in the control box body, and the circuit board includes the control circuit of the electrode-type liquid level gauge as described above; at least two electrodes are installed at the bottom of the control box body, and through holes are provided at the bottom of the control box body, the number of the through holes is the same as the number of the electrodes, an electrode fixing seat is coaxially provided in each through hole, the top end of the electrode fixing seat passes through the through hole into the control box body, the top end of the electrode fixing seat is connected to the circuit board via a connector, the bottom end of the electrode fixing seat is connected to one end of the electrode, and the other end of the electrode is a collection end.

[0014] Further, specifically, the connecting part includes a support column and a fixing component, the interior of the support column is a hollow structure, the top of the electrode fixing seat is connected to the hollow structure at the bottom end of the support column, the circuit board is installed on the support column, and a through hole is provided on the circuit board. The fixing component passes through the through hole to the top of the support column, and the fixing component is connected to the hollow structure at the top end of the support column.

[0015] Further, specifically, the top end of the electrode fixing seat is detachably connected to the hollow structure at the bottom end of the support column, and the fixing assembly is detachably connected to the hollow structure at the top end of the support column.

[0016] Further, specifically, an insulating tube is provided in the through hole, an insulating positioning ring is extended outward from the outer ring of the upper surface of the insulating tube, the central axis of the insulating positioning ring is coaxially arranged with the central axis of the insulating tube, and the bottom end of the support column is tightly fitted with the insulating positioning ring.

[0017] Further, specifically, the electrode fixing seat forms a wedge-shaped portion at the lower surface of the through hole and close to the bottom of the control box body, and an insulating gasket is provided between the wedge-shaped portion and the lower surface of the bottom of the control box body.

[0018] A control method for an electrode type liquid level gauge, the control method using the control circuit of the electrode type liquid level gauge as described above, the control method comprising:

[0019] Step S1: placing an electrode-type liquid level meter in a test environment, and when liquid in the test environment contacts a first electrode and a second electrode, transmitting electrode signals of the first electrode and the second electrode to an electrode switching module;

[0020] Step S2: the electrode switching module compares the electrode signals between the first electrode and the second electrode to determine whether the height of the liquid contacted by the second electrode meets a preset threshold;

[0021] If the conditions are met, the electrode signal is converted into an input signal of the control circuit by the electrode switching module, and the electrode switching module transmits the input signal to the MCU control module;

[0022] If not, the electrode switching module continues to collect the electrode signal;

[0023] Step S3: the MCU control module receives the input signal, obtains the transmission time of the input signal, and determines and controls the electrode switching module whether to switch electrodes according to the transmission time of the input signal;

[0024] If the transmission time of the input signal is less than or equal to the second threshold time, the MCU control module will not output the control signal;

[0025] If the transmission time of the input signal is greater than the second threshold time, the MCU control module times the transmission time of the input signal. When the transmission time of the input signal meets the first threshold time set by the MCU control module, the MCU control module outputs a control signal, and the control signal controls the electrode switching module to switch the properties of the first input end and the second input end.

[0026] Further, specifically, the step S3 also includes if the transmission time of the input signal is greater than a second threshold time, the MCU control module controls the output of the relay output module.

[0027] The beneficial effects of the present invention are:

[0028] (1) The control circuit of the electrode type liquid level meter provided by the present invention transmits the acquired electrode signal to the MCU control module through the electrode switching module. The MCU control module controls the switching of the input terminal properties of the electrode switching module according to the electrode signal, controls each electrode to be non-oxidized, non-scaled or less scaled, effectively solves the problem of unstable electrode signal acquisition caused by ion adsorption, impurity adsorption and bubble generation by the electrode, and the circuit itself is safe.

[0029] (2) The present invention provides the circuit with anti-reverse connection function, energy limiting function and overcurrent, overvoltage, short circuit and other protection functions through circuit design, thereby ensuring the reliability and safety of the circuit and improving the safety of the control circuit in the event of misoperation or failure.

[0030] (3) The present invention outputs a switching signal and a communication signal according to the high and low levels of the measured liquid level, thereby achieving the purpose of detecting and monitoring the liquid level and having a self-checking function.

[0031] (4) The present invention is suitable for detecting the liquid level of small water holes and liquid detection in coal mines through further improvement.

[0032] (5) The electrode type liquid level gauge provided by the present invention has good sealing performance, which ensures that the circuit board is not affected by water vapor and at the same time ensures the safety of the electrode type liquid level gauge. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below with reference to the accompanying drawings and examples.

[0034] Figure 1 2 is a schematic diagram of the control circuit structure of Example 1 of the present invention.

[0035] Figure 2It is a structural diagram of the power supply module of Example 1 of the present invention.

[0036] Figure 3 It is a structural diagram of the electrode switching module of Example 1 of the present invention.

[0037] Figure 4 4 is a circuit diagram of the anti-reverse unit according to embodiment 1 of the present invention.

[0038] Figure 5 This is a circuit diagram of the overcurrent and overvoltage protection unit and the energy consumption limiting unit of Example 1 of the present invention.

[0039] Figure 6 4 is a circuit diagram of a power conversion unit according to embodiment 1 of the present invention.

[0040] Figure 7 This is a circuit diagram of a power isolation unit according to embodiment 1 of the present invention.

[0041] Figure 8 1 is a circuit diagram of a switching unit according to embodiment 1 of the present invention.

[0042] Figure 9 4 is a circuit diagram of a comparison unit according to the first embodiment of the present invention.

[0043] Figure 10 4 is a circuit diagram of the first optocoupler isolation unit according to embodiment 1 of the present invention.

[0044] Figure 11 4 is a circuit diagram of the second optocoupler isolation unit according to embodiment 1 of the present invention.

[0045] Figure 12 This is a detailed circuit diagram of another preferred embodiment of the electrode switching module of Example 1 of the present invention.

[0046] Figure 13 This is a circuit diagram of the MCU control module of Example 1 of the present invention.

[0047] Figure 14 Schematic diagram of the structure of the electrode type liquid level meter according to embodiment 2 of the present invention.

[0048] Figure 15 It is a schematic diagram of the assembled structure of the electrode type liquid level gauge according to embodiment 2 of the present invention.

[0049] Figure 16 This is a flow chart of the control method of embodiment 3 of the present invention.

[0050] In the figure, 1 is an electrode switching module; 11 is a switching switch unit; 12 is a comparison unit; 13 is a first optical coupling isolation unit; 14 is a second optical coupling isolation unit;

[0051] 2. MCU control module;

[0052] 3. Power supply module; 31. Anti-reverse unit; 32. Overcurrent and overvoltage protection unit; 33. Energy consumption limiting unit; 34. Power conversion unit; 35. Power isolation unit;

[0053] 4. Door dog module; 5. Relay output module; 6. Communication module;

[0054] 700, control box body; 701, circuit board; 702, cover; 703, electrode; 705, electrode fixing seat; 7051, wedge-shaped portion; 706, connector; 7061, support column; 7062, fixing assembly; 707, insulating tube; 708, insulating gasket; 709, sealing ring. DETAILED DESCRIPTION

[0055] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0056] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0057] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0058] Example 1

[0059] like Figure 1As shown, it is a control circuit of an electrode type liquid level gauge according to the first embodiment of the present invention, the control circuit includes: at least two electrodes; at least one electrode switching module 1, the electrode switching module 1 includes two input terminals, namely a first input terminal and a second input terminal, the first input terminal is connected to the first electrode, and the second input terminal is connected to the second electrode, for obtaining electrode signals of the first electrode and the second electrode, and the electrode signals are converted into input signals of the control circuit by the electrode switching module 1; an MCU control module 2, connected to the electrode switching module 1, the electrode switching module 1 transmits the input signal to the MCU control module 2, the MCU control module 2 processes the transmission time of the input signal, when the transmission time of the input signal is within the first threshold time set by the MCU control module 2, the MCU control module 2 outputs a control signal to the electrode switching module 1, the electrode switching module 1 receives and executes the control signal, and the electrode switching module 1 switches the properties of the first input terminal and the second input terminal; a power supply module 3, the electrode switching module 1 and the MCU control module 2 are both electrically connected to the power supply module 3, and the power supply module 3 is used to supply power to the electrode switching module 1 and the MCU control module 2.

[0060] In the prior art, electrode-type liquid level gauges use the conductivity of liquids to detect liquid levels. The liquid height is detected by electrodes in contact with the measured liquid. The electrodes transmit the detection results to a processing circuit for processing. The processing circuit determines the water level based on the probe detection results and issues an action indication signal. When the electrode-type liquid level gauge is in use, if the electrodes are immersed in water for a long time, the first electrode will be negatively charged during detection and will decompose water to produce hydrogen, with two elements. The second electrode will be positively charged during detection and will decompose water to produce oxygen, with one element. This makes the electrodes prone to oxidation and scaling during use. In an embodiment of the present invention, the electrode switching module 1 processes the acquired electrode signal and transmits it to the MCU control module 2. The MCU control module 2 can control the switching of the input properties of the electrode switching module 1 according to the processed electrode signal. After the input properties of the electrode switching module 1 are switched, the first electrode will be positively charged during detection and will decompose water to produce oxygen, with one element. The second electrode will be negatively charged during detection and will decompose water to produce hydrogen, with two elements. The control circuit of the present invention controls the switching of electrodes so that each electrode is not oxidized, does not scale or scales less, effectively solving the problem of unstable electrode signal acquisition caused by ion adsorption, impurity adsorption and bubble generation at the electrode. In addition, the control circuit itself is safe in the event of misoperation or failure.

[0061] In an embodiment, the control circuit also includes: a door dog module 4, which is connected to the MCU control module 2 and is used to periodically detect the MCU control module 2. When the MCU control module 2 is in a dead loop, the door dog module 4 sends a restart signal to the MCU control module 2; a relay output module 5, which is connected to the MCU control module 2. When the MCU control module 2 processes the transmission time of the input signal, the MCU control module 2 controls the output of the relay output module 5; a communication module 6, which connects the MCU control module 2 with the external device through the communication module 6 signal. The external device can be a gate valve controller, but is not limited to this.

[0062] In some embodiments, the communication module may be an RS485 communication module, an RS232 communication module, or a CAN communication control module, but is not limited thereto.

[0063] In an embodiment, Figure 2 As shown, the power supply module 3 includes: an anti-reverse unit 31, at least one level of overcurrent and overvoltage protection unit 32, an energy consumption limiting unit 33, and a power conversion unit 34. The anti-reverse unit 31, the overcurrent and overvoltage protection unit 32, the energy consumption limiting unit 33, and the power conversion unit 34 are connected in sequence. Specifically, the anti-reverse unit 31 prevents the input power signal from being reversed. The anti-reverse unit 31 also provides current limiting protection for the input power signal. After the input power signal passes through the anti-reverse unit 31, it outputs a 12V voltage and is then transmitted to the overcurrent and overvoltage protection unit 32. The overcurrent and overvoltage protection unit 32 performs overcurrent and overvoltage protection on the output 12V voltage and then transmits it to the energy consumption limiting unit 33. The energy consumption limiting unit 33 limits the output 12V voltage to an energy range and then transmits it to the power conversion unit 34. After the power conversion unit 34 processes the output 12V voltage, the output of the power conversion unit 34 can be 5V or 3.3V. Through circuit design, the circuit has anti-reverse connection function, energy limitation function, and overcurrent, overvoltage, short circuit and other protection functions to ensure the reliability and safety of the circuit.

[0064] like Figure 4As shown, the anti-reverse unit 31 includes a diode VD1, a diode VD2, a fuse F1, a chip U1, and a capacitor C1. The diode VD1, diode VD2, and fuse F1 are connected in series, with one end connected to the input power signal and the other end connected to pin 2 of the chip U1. Pin 1 of the chip U1 is connected to the GND terminal. One end of the capacitor C1 is connected to pin 3 of the chip U1, and the other end is connected to pin 5 of the chip U1. After the input power signal passes through the chip U1, the chip U1 pin 3 outputs a 12V voltage. After the GND terminal passes through the chip U1, the chip U1 pin 5 becomes the GND_12V terminal. To prevent the input power signal from being connected in reverse, the input power signal is transmitted to fuse F1 after passing through two levels of reverse connection protection, diode VD1 and diode VD2. Fuse F1 provides current limiting protection for the input power signal before transmitting it to chip U1. The model of chip U1 includes but is not limited to IB2405. Chip U1 converts the input power signal into 12V, and chip U1 is also used for power isolation, thereby enhancing the anti-interference ability of the circuit and improving the reliability and safety of the circuit.

[0065] like Figure 5As shown, the overcurrent and overvoltage protection unit 32 includes a resistor R58, a resistor R60, a resistor R48, a resistor R53, a resistor R62, a resistor R30, a resistor 51, an adjustable resistor R12, a capacitor C14, a capacitor C30, a capacitor C2, a diode VD3, a diode VD4, a voltage regulator diode VD19, a MOS tube V4 and a chip N1. The resistor R53, the resistor R48 and the adjustable resistor R12 are connected in parallel, and one end of the parallel connection is connected to pin 1 of the chip N1, and the other end is connected to pin 2 of the chip N2. The resistor R58 and the resistor R60 are connected in series and then connected in parallel with the capacitor C14. One end of the parallel connection and the pin 2 of the chip N1 are both connected to a 12V voltage, and the other end of the parallel connection is connected to the GND_12V terminal. Pin 3 of the chip N1 is also connected to the capacitor C14, and pin 4 of the chip N1 is connected to the resistor 58. The connection end connected in series with resistor 60 is connected, one end of resistor R62 is connected to pin 7 of chip N1, one end of capacitor C30 is connected to pin 6 of chip N1, diode VD3 is connected in parallel with resistor R30, one end after connection is connected to the gate of the MOS tube, and the other end and the negative end of the Zener diode VD19 are both connected to pin 10 of chip N1, the drain of the MOS tube is also connected to pin 1 of chip N1, the source of the MOS tube and the positive end of the Zener diode VD19 are both connected to pin 9 of chip N1, diode VD4 and resistor R51 are connected in parallel, one end after connection is connected to the gate of the MOS tube V4, and the other end is connected to one end of capacitor C2, the other end of capacitor C2, the other end of capacitor C30, the other end of resistor R62 and pin 5 of chip N1 are all connected to the GND_12V end. Resistors R58 and R60 are used for resistive voltage division to detect the power signal input by the anti-reverse unit 31. The detected power signal is filtered by capacitor C14 and transmitted to chip N1. Chip N1 detects the filtered input power signal. Resistors R12, 48, and R53 are used to adjust the overcurrent of the input power signal. When the input power signal is abnormal, diodes VD3 and VD19 implement rapid discharge protection. Chip N1 implements overcurrent and overvoltage protection by controlling MOS tube V4 to open or cut off the corresponding circuit. Capacitor C30 is used to set the power-off time of control chip N1.

[0066] The model of chip N1 includes but is not limited to LM5069. The maximum input voltage of LM5069 is 80V. In the embodiment of the present invention, the overvoltage protection value calculation formula is:

[0067] U lim =U ovlo *((R58+R60) / R60))=13.5V;

[0068] Among them, U ovlo is the internal voltage of the chip N14 pin, U ovlo=2.5V, the resistance value of R48 is preferably 220kΩ, and the resistance value of R53 is preferably 50kΩ.

[0069] The calculation formula for overcurrent protection value is:

[0070] I lim =Vref / R SNS =Vref / (R48 / / R53 / / R12)=55 / 34.375=1.6A;

[0071] Among them, the resistance value of R48 is preferably 0.11Ω, the resistance value of R53 is preferably 0.05Ω, and the resistance value of the adjustable resistor R12 is preferably 1Ω±1%.

[0072] According to the 1.5 times margin, the maximum input voltage U=13.5*1.5=20.25V<80V, and the power value of the current limiting resistor P=I lim *I lim *R SNS *1.5=1.6*1.6*0.034*1.5=0.13W<2W. The overcurrent and overvoltage protection unit 32 complies with the requirements of the GB3836.4-2010 standard for equipment in explosive environments of level Ga, and is suitable for use in coal mines.

[0073] In some embodiments, the power supply module 3 includes a two-stage overcurrent and overvoltage protection unit 32. The positive terminal of the output terminal of the first-stage overcurrent and overvoltage protection unit 32 is connected to the positive terminal of the input terminal of the second-stage protection circuit, and the negative terminal of the output terminal of the first-stage protection circuit is connected to the negative terminal of the input terminal of the second-stage protection circuit. The structures and circuit connections of the first-stage overcurrent and overvoltage protection unit 32 and the second-stage overcurrent and overvoltage protection unit 32 are identical. When the first-stage overcurrent and overvoltage protection unit 32 fails, the second-stage overcurrent and overvoltage protection unit 32 begins to operate. The second-stage overcurrent and overvoltage protection unit 32 provides overcurrent and overvoltage protection for the power supply module 3, has higher stability and safety, and forms intrinsically safe protection. The control circuit of the electrode-type liquid level gauge has two-stage overcurrent and overvoltage protection units 32, which is suitable for use in coal mine scenarios.

[0074] like Figure 5As shown, the energy consumption limiting unit 33 includes a diode VD8, a diode VD18, a diode VD21, a diode VD22, a resistor R29, a resistor R50, a resistor R55, a resistor R56, a resistor R57 and an inductor L2. The diode VD8 and the diode VD21 are connected in parallel, the diode VD18 and the diode VD22 are connected in parallel, the positive terminal of the parallel connection of the diode VD8 and the diode VD21 is connected to the negative terminal of the parallel connection of the diode VD18 and the diode VD22, the negative terminal of the parallel connection of the diode VD8 and the diode VD21 is connected to one end of the inductor L2, the positive terminal of the parallel connection of the diode VD18 and the diode VD22 is connected to the other end of the inductor L2, the resistor R29, the resistor R50, the resistor 55, the resistor 56 and the resistor 57 are connected in parallel, one end of the connected end is connected to the other end of the inductor L2, and the other end is connected to the power conversion unit 34. The power signal after passing through the overvoltage protection unit 32 is transmitted to the energy consumption limiting unit 33. The diode VD8 and the diode VD21 in the energy consumption limiting unit 33 are connected in parallel to increase the current value flowing through the overvoltage protection unit 32. VD18 and VD22 are connected in parallel to increase the current value flowing through the overvoltage protection unit 32. Resistors R29, R50, R55, R56, and R57 are connected in parallel to disperse the current flow path and increase the current. When the power supply increases instantaneously, an internal loop is formed inside the power supply through the inductor L2, which can suppress the sudden change of the power supply, play a stable soft start role, and further improve the safety of the circuit.

[0075] like Figure 6 As shown, power conversion unit 34 includes capacitor C34, capacitor C32, capacitor C33, and chip U4. One end of capacitor C34 and pin 4 of chip U4 are both connected to the output voltage of energy consumption limiting unit 33, and the other end and pin 1 of chip U4 are both connected to GND_12V. After the output voltage of energy consumption limiting unit 33 is processed by chip U4, pin 5 of chip U4 outputs 5V, and pin 7 of chip U4 outputs 3.3V. One end of capacitor C32 is connected to 5V and the other end is connected to GND_12V. One end of capacitor C33 is connected to 3.3V and the other end is connected to GND_12V. Capacitor C34 filters the power signal output by energy consumption limiting unit 33 and transmits the filtered power signal to chip U4. Chip U4 converts the 12V voltage into the supply voltage required by each module. Capacitors C32 and C33 filter the converted supply voltage to further improve circuit stability.

[0076] In the embodiment, the power supply module 3 further includes a power isolation unit 35, one end of the power isolation unit 35 is connected to the power conversion unit 34, and the other end is connected to the electrode switching module 1. Figure 7As shown, the power isolation unit 35 includes a chip U2 and a capacitor C5. Pin 2 of chip U2 is connected to a 5V voltage, and pin 1 of chip U2 is connected to a GND_12V terminal. After chip U2 isolates the input 5V voltage, pin 4 of chip U2 outputs a 5V voltage. Pin 4 of chip U2 is the voltage output terminal of the power isolation unit 35, and pin 3 of chip U2 is the GND1 terminal. The two ends of capacitor C5 are connected to pins 4 and 3 of chip U2, respectively. The model of chip U2 includes but is not limited to B0505, and the preferred model is B0505. Using an isolated power supply B0505 ​​for isolation, when the power supply module 3 supplies power to the electrode switching module 1, it can ensure that the electrode switching module 1 can be isolated from the internal circuit when collecting electrode signals, thereby improving the safety of the control circuit and reducing circuit noise interference.

[0077] In an embodiment, Figure 3 As shown, the electrode switching module 1 includes: a switching switch unit 11, a comparison unit 12, a first optocoupler isolation unit 13 and a second optocoupler isolation unit 14; the switching switch unit 11, the comparison unit 12 and the first optocoupler isolation unit 13 are connected in sequence; the switching switch unit 11 is respectively connected to the first input end and the second input end, and the switching switch unit 11 obtains the electrode signal and transmits it to the comparison unit 12, the comparison unit 12 compares the electrode signal, and if the conditions are met after comparison, the electrode signal is transmitted to the first optocoupler isolation unit 13, and the first optocoupler isolation unit 13 receives the electrode signal and performs optocoupler isolation processing on the electrode signal, and the processed electrode signal is the input signal; on the contrary, if the conditions are not met after comparison, the electrode signal continues to be obtained; the second optocoupler isolation unit 14 is respectively connected to the MCU control module 2 and the switching switch unit 11, the MCU control module 2 transmits the control signal to the second optocoupler isolation unit 14 for optocoupler isolation processing, and transmits the processed control signal to the switching switch unit 11, and the switching switch unit 11 executes the control signal to switch the properties of the first input end and the second input end.

[0078] In some embodiments, the electrode switching module 1 further includes a display unit 15 , which is connected to the first optocoupler isolation unit 13 . When the first optocoupler isolation unit 13 transmits an input signal to the display unit, the display unit receives the input signal and displays it.

[0079] Specifically, such as Figure 8As shown, the switching opening unit includes a diode VD5, a resistor R3, a resistor R5 and a chip N6. One end of the resistor R3, one end of the resistor R5 and pin 12 of the N6 chip are all connected to the voltage output end of the power isolation unit 35. The other end of the resistor R3 is connected to pin 1 of the chip N6. Pins 2 and 5 of the chip N6 are both connected to the TP1 end. Pins 7 and 14 of the chip are both connected to the TP2 end. The negative pole of the diode VD5 is connected to the TP1 end, and the positive pole is connected to the TP2 end. Pins 3, 4 and 13 of the chip N6 are all connected to the GND1 end. Pin 5 of the chip N6 is connected to the TP1 end. The other end of the resistor R5 is connected to pin 15 of the chip N6. Pin 6 of the chip N6 is the output end of the switching opening unit. Pins 8 and 16 of the chip N6 are both connected to the output end of the second optocoupler isolation unit 14. Diode VD5 is a transient suppression diode that protects the voltage signal collected by the electrode. Resistors R3 and R5 are pull-up resistors. The power signal output by the power isolation unit 35 is pulled up by resistors R3 and R5 and then transmitted to chip N6. Chip N6 collects electrode signals and receives control signals from the MCU control module to realize electrode switching. Chip N6 models include but are not limited to RS2099XTSS16.

[0080] like Figure 9 As shown, the comparison unit 12 includes a resistor R4, a resistor R9, a potentiometer VR1, a capacitor C7 and a comparator N3. Pin 3 of the comparator N3 is connected to the output end of the switching unit to receive the electrode signal collected by the switching unit. Pins 1 and 2 of the comparator N3 are connected to one end of R4, and the other end of R4 and one end of the capacitor C7 are both connected to pin 6 of the comparator N3. Pins 1 and 2 of the potentiometer VR1 are connected to the voltage output end of the power isolation unit 35. Pin 3 of the potentiometer VR1 and one end of the resistor R9 are both connected to pin 5 of the comparator N3. Pin 4 of the comparator N3, the other end of the capacitor C7 and the other end of the resistor R9 are all connected to the GND1 end. Pin 7 of the comparator N3 is the output end of the comparison unit 12. Resistor R4, resistor R9, potentiometer VR1, capacitor C7 and comparator N3 compare the electrode signals to determine whether the liquid height contacted by the electrode meets the preset threshold, and then control whether the input signal is transmitted to the MCU control module to adjust the electrode sensitivity and prevent the electrode from being easily oxidized and scaled during long-term use.

[0081] like Figure 10As shown, the first optical coupling isolation unit 13 includes a resistor R7, a photocoupler N2, and a resistor R10. One end of the resistor R7 is connected to the output terminal of the comparison unit 12, and the other end is connected to pin 1 of the photocoupler N2. Pin 2 of the photocoupler is connected to GND1. One end of the resistor R10 is connected to pin 3 of the photocoupler N2, and the other end is connected to GND. Pin 3 of the photocoupler N2 is the output terminal, and pin 4 of the photocoupler N2 is connected to a 3.3V voltage. Resistor R7, photocoupler N2, and resistor R10 isolate the signal output by the comparison unit 12, reducing interference signals during signal transmission and improving circuit stability.

[0082] like Figure 11 As shown, the second optocoupler isolation unit 14 includes a resistor R26, a resistor R27, a resistor R31, a transistor V2, and a photocoupler N9. One end of resistor R26 is connected to a 3.3V voltage, and the other end is connected to pin 1 of the photocoupler N9. One end of resistor R31 is connected to the MCU control unit, and the other end is connected to the base of the transistor V2. The emitter of the transistor V2 is connected to the GND terminal, and the collector of the transistor V2 is connected to pin 2 of the photocoupler N9. One end of resistor R27 is connected to pin 3 of the photocoupler N9, and the other end is connected to GND1. Pin 3 of the photocoupler N9 is the output terminal of the second optocoupler isolation unit 14, and pin 4 of the photocoupler N9 is connected to the voltage output terminal of the power isolation unit 35. Resistor R26, resistor R27, resistor R31, transistor V2, and photocoupler N9 isolate the signal output by the MCU control unit, reducing interference signals during signal transmission and improving circuit stability.

[0083] In some embodiments, as Figure 12 As shown, the control circuit includes two electrode switching modules and three electrodes; the two electrode switching modules are respectively a first electrode switching module and a second electrode switching module, and the first electrode switching module and the second electrode switching module have the same structure and circuit connection; the three electrodes are respectively a first electrode, a second electrode, and a third electrode, and the two input terminals of the first electrode switching module are respectively connected to the first electrode and the second electrode, and the two input terminals of the second electrode switching module are respectively connected to the second electrode and the third electrode. The metal rods of the three electrodes are of different lengths, with the metal rod of the first electrode being longer than the metal rod of the second electrode, and the metal rod of the second electrode being longer than the metal rod of the third electrode.

[0084] In an embodiment, Figure 13 As shown, the chip model of the MCU control module 2 is a single chip microcomputer of the STM32L431R series, but is not limited to this.

[0085] The control circuit of the electrode type liquid level meter provided by the present invention transmits the acquired electrode signal to the MCU control module through the electrode switching module. The MCU control module controls the input terminal attribute switching of the electrode switching module according to the electrode signal, controls each electrode to be non-oxidized, non-scaling or less scaling, and effectively solves the problem of unstable electrode signal acquisition caused by ion adsorption, impurity adsorption and bubble generation by the electrode. Through circuit design, the circuit has anti-reverse connection function, energy limitation function and overcurrent, overvoltage, short circuit and other protection functions, ensuring the reliability and safety of the circuit, and improving the safety of the control circuit in the event of misoperation or failure. In addition, the present invention outputs switching signals and communication signals according to the height of the measured liquid level, achieves the purpose of detecting and monitoring the liquid level, and has a self-test function.

[0086] Example 2

[0087] like Figure 14 and 15 As shown, it is the second embodiment of the present invention, an electrode type liquid level gauge, comprising: a control box body 700 and a cover body 702 detachably assembled on the control box body 700, a circuit board 701 is arranged in the control box body 700, and the circuit board 701 includes the control circuit of the electrode type liquid level gauge as described above; at least two electrodes are installed at the bottom of the control box body 700, and the bottom of the control box body 700 is provided with through holes, the number of through holes is the same as the number of electrodes, and an electrode fixing seat 705 is coaxially arranged in each through hole, the top end of the electrode fixing seat 705 passes through the through hole to the control box body 700, the top end of the electrode fixing seat 705 is connected to the circuit board 701 through a connector 706, the bottom end of the electrode fixing seat 705 is connected to one end of the electrode, and the other end of the electrode is the collection end.

[0088] In an embodiment, the connector 706 includes a support column 7061 and a fixing assembly 7062. The interior of the support column 7061 is a hollow structure. The top of the electrode fixing seat 705 is connected to the hollow structure at the bottom of the support column 7061. The circuit board 701 is mounted on the support column 7061. The circuit board 701 is provided with a via. The fixing assembly 7062 passes through the via to the top of the support column 7061. The fixing assembly 7062 is connected to the hollow structure at the top of the support column 7061. Preferably, the top of the electrode fixing seat 705 is detachably connected to the hollow structure at the bottom of the support column 7061, and the fixing assembly 7062 is detachably connected to the hollow structure at the top of the support column 7061, thereby facilitating assembly and disassembly of the electrode-type liquid level gauge.

[0089] In the embodiment, an insulating tube 707 is provided in the through hole, and an insulating positioning ring is extended outward from the outer ring of the upper surface of the insulating tube 707. The central axis of the insulating positioning ring is coaxially arranged with the central axis of the insulating tube 707. The bottom of the support column 7061 is tightly fitted with the insulating positioning ring, thereby improving the sealing performance of the electrode-type liquid level gauge.

[0090] In the embodiment, the electrode fixing seat 705 forms a wedge-shaped portion 7051 at the lower surface of the through hole and close to the bottom of the control box body 700, and an insulating gasket 708 is provided between the wedge-shaped portion 7051 and the lower surface of the bottom of the control box body 700 to further improve the sealing of the electrode type liquid level gauge.

[0091] In some embodiments, a sealing ring 709 is further provided between the insulating gasket 708 and the lower surface of the bottom of the control box body 700. The sealing ring 709 reduces the friction between the insulating gasket 708 and the control box body 700, prevents loosening or disperses pressure. The sealing ring can be a flat gasket, but is not limited to this.

[0092] The electrode type liquid level gauge circuit board of the present invention adopts the control circuit as described above to control each electrode to prevent oxidation, scaling or less scaling, effectively solving the problem of unstable electrode signal acquisition caused by ion adsorption, impurity adsorption and bubble generation by the electrode. It also has good sealing performance, ensuring that the circuit board is not affected by water vapor, while ensuring the safety of the electrode type liquid level gauge.

[0093] Example 3

[0094] A control method for an electrode type liquid level gauge, the control method adopts the control circuit of the electrode type liquid level gauge as described above, such as Figure 16 As shown, the control method includes:

[0095] Step S1: placing the electrode-type liquid level meter in the environment to be measured, and when liquid in the environment to be measured contacts the first electrode and the second electrode, transmitting the electrode signals of the first electrode and the second electrode to the electrode switching module 1;

[0096] Step S2: The electrode switching module 1 compares the electrode signals between the first electrode and the second electrode to determine whether the height of the liquid contacted by the second electrode meets a preset threshold. If so, the electrode signal is converted into an input signal of the control circuit by the electrode switching module 1, and the electrode switching module 1 transmits the input signal to the MCU control module 2. If not, the electrode switching module 1 continues to collect electrode signals.

[0097] Step S3: MCU control module 2 receives the input signal, MCU control module 2 obtains the transmission time of the input signal, and MCU control module 2 determines and controls whether the electrode switching module 1 needs to switch the electrode based on the transmission time of the input signal; if the transmission time of the input signal is less than or equal to the second threshold time, the MCU control module 2 will not output the control signal; if the transmission time of the input signal is greater than the second threshold time, the MCU control module 2 times the transmission time of the input signal, and when the transmission time of the input signal meets the first threshold time set by the MCU control module 2, the MCU control module 2 outputs a control signal, and the control signal controls the electrode switching module 1 to switch the properties of the first input end and the second input end. Specifically, the second threshold time is preferably 1 second. When the transmission time of the input signal is less than or equal to 1 second, the input signal is caused by liquid water waves or other interference signals, and the MCU control module 2 will not output a control signal. When the transmission time of the input signal is greater than 1 second, it is considered that the liquid level exists, and the MCU control module 2 will time the transmission time of the input signal. When the transmission time of the input signal meets the first threshold time set by the MCU control module 2, the MCU control module 2 outputs a control signal, which controls the electrode switching module 1 to switch the properties of the first input end and the second input end. The first threshold time is preferably 5 minutes.

[0098] In an embodiment, step S3 also includes if the transmission time of the input signal is greater than the second threshold time, the MCU control module 2 controls the relay output module 5 to output for use by the drainage pump or other control equipment.

[0099] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A control method for an electrode type liquid level gauge, characterized in that: An electrode type liquid level gauge is used, and the electrode type liquid level gauge includes a control circuit, and the control circuit includes: at least two electrodes; At least one electrode switching module (1), the electrode switching module (1) comprising two input terminals, namely a first input terminal and a second input terminal, the first input terminal being connected to a first electrode, the second input terminal being connected to a second electrode, and being used to obtain electrode signals of the first electrode and the second electrode, the electrode signals being converted into input signals of the control circuit by the electrode switching module (1); An MCU control module (2) is connected to the electrode switching module (1), the electrode switching module (1) transmits the input signal to the MCU control module (2), the MCU control module (2) processes the timing of the transmission time of the input signal, and when the transmission time of the input signal is within a first threshold time set by the MCU control module (2), the MCU control module (2) outputs a control signal to the electrode switching module (1), the electrode switching module (1) receives and executes the control signal, and the electrode switching module (1) switches the attributes of the first input end and the second input end; A power supply module (3), the electrode switching module (1) and the MCU control module (2) are both electrically connected to the power supply module (3), and the power supply module (3) is used to supply power to the electrode switching module (1) and the MCU control module (2); The control method includes: Step S1: placing an electrode-type liquid level meter in a test environment, and when liquid in the test environment contacts a first electrode and a second electrode, transmitting electrode signals of the first electrode and the second electrode to an electrode switching module (1); Step S2: the electrode switching module (1) compares the electrode signals between the first electrode and the second electrode to determine whether the height of the liquid contacted by the second electrode meets a preset threshold; If the conditions are met, the electrode signal is converted into an input signal of the control circuit via the electrode switching module (1), and the electrode switching module (1) transmits the input signal to the MCU control module (2); If not, the electrode switching module (1) continues to collect the electrode signal; Step S3: the MCU control module (2) receives the input signal, the MCU control module (2) obtains the transmission time of the input signal, and the MCU control module (2) determines and controls the electrode switching module (1) whether to switch electrodes according to the transmission time of the input signal; If the transmission time of the input signal is less than or equal to the second threshold time, the MCU control module (2) will not output the control signal; If the transmission time of the input signal is greater than a second threshold time, the MCU control module (2) times the transmission time of the input signal; when the transmission time of the input signal meets the first threshold time set by the MCU control module (2), the MCU control module (2) outputs a control signal, and the control signal controls the electrode switching module (1) to switch the properties of the first input end and the second input end.

2. The control method of the electrode type liquid level gauge according to claim 1, characterized in that: The power supply module (3) comprises: an anti-reverse unit (31), at least one level of overcurrent and overvoltage protection unit (32), an energy consumption limiting unit (33) and a power conversion unit (34); The anti-reverse unit (31), the overcurrent and overvoltage protection unit (32), the energy consumption limiting unit (33) and the power conversion unit (34) are connected in sequence.

3. The control method of the electrode type liquid level gauge according to claim 1, characterized in that: The control circuit further includes: A door dog module (4) is connected to the MCU control module (2) and is used to regularly detect the MCU control module (2). When the MCU control module (2) is in an endless loop, the door dog module (4) sends a restart signal to the MCU control module (2); A relay output module (5) is connected to the MCU control module (2), and when the MCU control module (2) processes the transmission time of the input signal, the MCU control module (2) controls the output of the relay output module (5); A communication module (6) is provided, wherein the MCU control module (2) is connected to an external device by signals via the communication module (6).

4. The control method of the electrode type liquid level gauge according to claim 3, characterized in that: Step S3 also includes: if the transmission time of the input signal is greater than a second threshold time, the MCU control module (2) controls the output of the relay output module (5).

5. The control method of the electrode type liquid level gauge according to claim 2, characterized in that: The power supply module (3) further comprises a power isolation unit (35), one end of the power isolation unit (35) being connected to the power conversion unit (34) and the other end being connected to the electrode switching module (1).

6. The control method of the electrode type liquid level gauge according to claim 1, characterized in that: The electrode switching module (1) comprises: a switching unit (11), a comparison unit (12), a first optical coupling isolation unit (13) and a second optical coupling isolation unit (14); The switching unit (11), the comparison unit (12) and the first optical coupling isolation unit (13) are connected in sequence; The switching unit (11) is connected to the first input end and the second input end respectively, and the switching unit (11) obtains the electrode signal and transmits it to the comparison unit (12), and the comparison unit (12) compares the electrode signal; If the condition is met after comparison, the electrode signal is transmitted to the first optical coupling isolation unit (13); the first optical coupling isolation unit (13) receives the electrode signal and performs optical coupling isolation processing on the electrode signal; the processed electrode signal is the input signal; On the contrary, if the condition is not met after comparison, then continue to obtain the electrode signal; The second optical coupling isolation unit (14) is connected to the MCU control module (2) and the switching switch unit (11) respectively; the MCU control module (2) transmits the control signal to the second optical coupling isolation unit (14) for optical coupling isolation processing, and transmits the processed control signal to the switching switch unit (11); the switching switch unit (11) executes the control signal and switches the properties of the first input end and the second input end.

7. The control method of the electrode type liquid level gauge according to claim 6, characterized in that: The control circuit includes two electrode switching modules and three electrodes; The two electrode switching modules are respectively a first electrode switching module and a second electrode switching module, and the structures and circuit connections of the first electrode switching module and the second electrode switching module are the same; The three electrodes are respectively a first electrode, a second electrode and a third electrode. The two input ends of the first electrode switching module are respectively connected to the first electrode and the second electrode. The two input ends of the second electrode switching module are respectively connected to the second electrode and the third electrode.

8. The control method of the electrode type liquid level gauge according to claim 2, characterized in that: The power supply module (3) comprises two stages of overcurrent and overvoltage protection units (32), wherein the positive terminal of the output end of the first stage overcurrent and overvoltage protection unit (32) is connected to the positive terminal of the input end of the second stage overcurrent and overvoltage protection unit (32), and the negative terminal of the output end of the first stage overcurrent and overvoltage protection unit (32) is connected to the negative terminal of the input end of the second stage overcurrent and overvoltage protection unit (32).

9. The control method of the electrode type liquid level gauge according to claim 1, characterized in that: The electrode type liquid level gauge also includes: A control box body (700) and a cover body (702) detachably assembled on the control box body (700), wherein a circuit board (701) is provided in the control box body (700), and the circuit board (701) includes the control circuit; At least two electrodes (703) are installed at the bottom of the control box body (700), and a through hole is provided at the bottom of the control box body (700), the number of the through holes being the same as the number of the electrodes, and an electrode fixing seat (705) is coaxially provided in each through hole, the top end of the electrode fixing seat (705) passes through the through hole into the control box body (700), the top end of the electrode fixing seat (705) is connected to the circuit board (701) via a connector (706), the bottom end of the electrode fixing seat (705) is connected to one end of the electrode (703), and the other end of the electrode (703) is a collection end.

10. The control method of the electrode type liquid level gauge according to claim 9, characterized in that: The connecting member (706) includes a support column (7061) and a fixing component (7062), the interior of the support column (7061) is a hollow structure, the top of the electrode fixing seat (705) is connected to the hollow structure at the bottom of the support column (7061), the circuit board (701) is installed on the support column (7061), and a through hole is provided on the circuit board (701), the fixing component (7062) passes through the through hole to the top of the support column (7061), and the fixing component (7062) is connected to the hollow structure at the top of the support column (7061).

11. The control method of the electrode type liquid level gauge according to claim 10, characterized in that: The top end of the electrode fixing seat (705) is detachably connected to the hollow structure at the bottom end of the support column (7061), and the fixing assembly (7062) is detachably connected to the hollow structure at the top end of the support column (7061).

12. The control method of the electrode type liquid level gauge according to claim 10, characterized in that: An insulating tube (707) is provided in the through hole, an insulating positioning ring is extended outward from the outer ring of the upper surface of the insulating tube (707), the central axis of the insulating positioning ring is coaxially arranged with the central axis of the insulating tube (707), and the bottom end of the support column (7061) is tightly fitted with the insulating positioning ring.

13. The control method of the electrode type liquid level gauge according to claim 12, characterized in that: The electrode fixing seat (705) forms a wedge-shaped portion (7051) at the lower surface of the through hole and close to the bottom of the control box body (700), and an insulating gasket (708) is provided between the wedge-shaped portion (7051) and the lower surface of the bottom of the control box body (700).

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