Material level sensor with zero-point self-learning function

Abstract

The utility model discloses a material level sensor with a zero point self-learning function, which comprises a circuit board, the circuit board comprises a single chip microcomputer U1, the single chip microcomputer U1 is electrically connected with a driving signal amplification module, the driving signal amplification module is electrically connected with a piezoelectric transducer, the single chip microcomputer U1 sends a signal to the driving signal amplification module, and the piezoelectric transducer is electrically connected with the piezoelectric transducer. The driving signal amplification module processes received signals and then transmits the signals to the piezoelectric transducer, the piezoelectric transducer receives the signals and then emits ultrasonic waves, the ultrasonic waves are fed back after encountering an obstacle and then are sent to the piezoelectric transducer again, the piezoelectric transducer is electrically connected with the return signal conditioning module, the return signal conditioning module is electrically connected with the single chip microcomputer U1, and the single chip microcomputer U1 is electrically connected with the single chip microcomputer U1. The return signal conditioning module processes the received signal and then feeds back the signal to the single chip microcomputer U1 again, the single chip microcomputer U1 is electrically connected with the signal output module, and the single chip microcomputer U1 processes the signal fed back by the return signal conditioning module and then transmits a distance signal to the signal output module for output.

Description

Technical Field

[0001] The utility model belongs to the technical field of level sensors and relates to a level sensor with a zero-point self-learning function. Background Technique

[0002] A sensor that can detect the level (liquid level, material level) and convert it into an available output signal is called a level sensor. Level sensors are widely used in industrial automation production. Level sensors can be divided into two categories: one is a switch-type level sensor for point measurement, i.e., a level switch, which is mainly used for thresholds, overflows, etc. in process automatic control. The other is a continuous level sensor for continuously measuring the level change, which is mainly used for continuous control and bin management, etc.

[0003] In coal mine production, a continuous level sensor can be used to detect the thickness of the transported coal on the conveyor belt. It cooperates with the belt conveyor control device to enable the belt conveyor to achieve automatic speed regulation (when the coal thickness is large, the belt running speed is increased to prevent coal overload and dropping; when the coal thickness is small, the belt running speed is reduced to reduce energy consumption), so as to improve the transportation efficiency of the belt conveyor and achieve the purpose of energy conservation and emission reduction.

[0004] The ranging principles of mine-used continuous level sensors are divided into laser type and ultrasonic type. The laser type level sensor uses laser as the ranging medium, and its penetration ability is weak. When propagating in the air, it is easily blocked by dust, affecting the detection result; the ultrasonic type level sensor uses ultrasonic as the ranging medium, and ultrasonic has the characteristic of strong penetration ability and is more suitable for underground belt transportation places with large dust.

[0005] At present, the ranging range of the current continuous level sensor is fixed at the time of factory shipment. During on-site installation, the level sensor should be hung directly above the front of the belt lap point so that the distance from its detection end to the empty belt surface is at the farthest end (zero point) of the detection range of the level sensor. In the application of coal mines, the space of many installation points is limited and cannot meet the requirements of the hoisting height. At this time, the level sensor cannot correctly identify the zero point when the belt is empty, resulting in a large ranging error and unable to realize the subsequent automatic speed regulation function of the belt conveyor. Therefore, it is extremely important to design a level sensor that can adjust the zero point according to different on-site environments for the accurate detection of the coal level transported by the belt conveyor. Summary of the Invention

[0006] In view of this, the purpose of the utility model is to provide a level sensor with a zero-point self-learning function that can solve the above problems.

[0007] To achieve the above purpose, the utility model provides the following technical solutions:

[0008] A level sensor with zero-point self-learning function includes a circuit board, which includes a single-chip microcomputer U1, a power supply module, an integrated button detection and light-emitting indication module, a drive signal amplification module, a return signal conditioning module, a signal output module, and a piezoelectric transducer. The single-chip microcomputer U1 is electrically connected to the drive signal amplification module, and the drive signal amplification module is electrically connected to the piezoelectric transducer. The single-chip microcomputer U1 sends a signal to the drive signal amplification module, and the drive signal amplification module processes the received signal and then transmits it to the piezoelectric transducer. After receiving the signal, the piezoelectric transducer emits ultrasonic waves. After the ultrasonic waves encounter an obstacle and are reflected back, they are given back to the piezoelectric transducer again. The piezoelectric transducer is electrically connected to the return signal conditioning module, and the return signal conditioning module is electrically connected to the single-chip microcomputer U1. The return signal conditioning module processes the received signal and then feeds it back to the single-chip microcomputer U1 again. The single-chip microcomputer U1 is electrically connected to the signal output module, and the single-chip microcomputer U1 processes the signal fed back by the return signal conditioning module and then transmits it to the signal output module for output.

[0009] The power supply module supplies power to the single-chip microcomputer U1 and other modules. The integrated button detection and light-emitting indication module is electrically connected to the single-chip microcomputer U1. The integrated button detection and light-emitting indication module transmits the button signal to the single-chip microcomputer U1 to control the switch of the single-chip microcomputer U1, and the single-chip microcomputer U1 controls the ring-shaped indicator light of the integrated button detection and light-emitting indication module at the same time.

[0010] Further, the drive signal amplification module includes a level shifter U21. The pins 2 and 3 of the level shifter U21 are connected and then electrically connected to the pin 18 of the single-chip microcomputer U1. The pin 4 of the level shifter U21 is electrically connected to the pin 17 of the single-chip microcomputer U1 and is also electrically connected to the signal conditioning module. The pin 7 of the level shifter U21 is electrically connected to one end of a resistor R21. The other end of the resistor R21 is electrically connected to one end of a DC-blocking capacitor C21. The other end of the DC-blocking capacitor C21 is electrically connected to the pin 1 of a medium frequency transformer U22. The pin 6 of the level shifter U21 is electrically connected to one end of a resistor R22. The other end of the resistor R22 is electrically connected to one end of a DC-blocking capacitor C22. The other end of the DC-blocking capacitor C22 is electrically connected to the pin 2 of the medium frequency transformer U22. The pin 4 of the medium frequency transformer U22 is electrically connected to one end of a capacitor C23. The other end of the capacitor C23 is electrically connected to the piezoelectric transducer. The pin 3 of the medium frequency transformer U22 is electrically connected to one end of a capacitor C24. The other end of the capacitor C24 is electrically connected to the piezoelectric transducer and then grounded.

[0011] Further, the return signal conditioning module includes a resistor R31 electrically connected to the piezoelectric converter. One end of the resistor R31 is electrically connected to the piezoelectric converter, and the other end of the resistor R31 is electrically connected to the negative electrode of the voltage regulator diode D31 and one end of the capacitor C31. The positive electrode of the voltage regulator diode D31 is grounded, and the other end of the capacitor C31 is electrically connected to one end of the resistor R32. The other end of the resistor R32 is electrically connected to pin 2 of the amplifier U31.1 and then to one end of the resistor R33. The other end of the resistor R33 is electrically connected to pin 1 of the amplifier U31.1 and then to one end of the capacitor C33. The other end of the capacitor C33 is electrically connected to one end of the resistor R34. The other end of the resistor R34 is electrically connected to pin 2 of the amplifier U31.2 and then to one end of the resistor R35. The other end of the resistor R35 is electrically connected to pin 1 of the amplifier U31.2 and then to one end of the capacitor C34. The other end of the capacitor C34 is electrically connected to the negative electrode of the diode D33 and the positive electrode of the diode D32. The negative electrode of the diode D32 is electrically connected to one end of the capacitor C35 and pin 3 of the amplifier U32.1. The other end of the capacitor C35 and the positive electrode of the diode D33 are electrically connected to pin 4 of the amplifier U31.2 and then grounded;

[0012] Pin 2 of the amplifier U32.1 is electrically connected to one end of the resistor R36, the resistor R37, and the capacitor C36 and then to pin 3 of the amplifier U31.2 and pin 3 of the amplifier U31.1. The other end of the resistor R36 is connected to the +5V power supply. The other end of the resistor R37 is electrically connected to the other end of the capacitor C36 and then grounded. Pin 1 of the amplifier U32.1 is electrically connected to one end of the resistor R38. The other end of the resistor R38 is electrically connected to pin 17 of the single-chip microcomputer U1 and pin 4 of the level shifter U21.

[0013] Further, the signal output module includes a resistor R42. One end of the resistor R42 is electrically connected to pin 9 of the single-chip microcomputer U1, and the other end of the resistor R42 is electrically connected to the base of the triode Q41. The emitter of the triode Q41 is electrically connected to the positive electrode of the diode D42 and the positive electrode of the voltage regulator diode D41. The negative electrode of the diode D42 is grounded. The collector of the triode Q41 is electrically connected to the negative electrode of the voltage regulator diode D41 and one end of the resistor R41 and then outputs a signal. The other end of the resistor R41 is connected to the power supply VCC.

[0014] Further, the power supply module includes a power supply chip U3. The positive electrode of diode D1 is connected to the power supply VCC. The negative electrode of diode D1 is electrically connected to the positive electrode of diode D2. The negative electrode of diode D2 is electrically connected to pin 2 of the power supply chip U3. After the connection between pin 2 of the power supply chip U3 and the negative electrode of diode D2, it is also electrically connected to one end of capacitor C1. The other end of capacitor C1 is connected to one end of capacitor C2 and then connected to the GND pin of the power supply chip U3. The GND pin of the power supply chip U3 is grounded. The other end of capacitor C2 is connected to pin 3 of the power supply chip U3 and then outputs a +5V power supply.

[0015] Further, the integrated button detection and light-emitting indication module includes resistors R11 and R12. One ends of resistors R11 and R12 are connected and then connected to the +5V power supply. The other end of resistor R11 is connected to the positive electrode of the light-emitting diode. The negative electrode of the light-emitting diode is electrically connected to pin 2 of the single-chip microcomputer U1. The light-emitting diode is a ring-shaped indicator light. The other end of resistor R12 is electrically connected to pin 1 of the button and one end of resistor R13. The other end of resistor R13 is connected to one end of capacitor C11 and then electrically connected to pin 1 of the single-chip microcomputer U1. The other end of capacitor C11 is electrically connected to pin 2 of the button and then grounded.

[0016] Further, the single-chip microcomputer U1 is also electrically connected to the ambient temperature detection module. The ambient temperature detection module transmits the detected ambient temperature signal to the single-chip microcomputer U1. The single-chip microcomputer U1 performs detection compensation according to the temperature information provided by the ambient temperature detection module.

[0017] Further, the model of the single-chip microcomputer U1 is PIC16F1827.

[0018] Further, the model of the piezoelectric transducer is KS105.

[0019] Further, it includes a housing with an open lower end. A lifting ring integrally provided with the housing is fixed in the middle of the outside of the upper end of the housing. A ring seat for installing a cover plate is fixed at a position inside the housing close to the open lower end of the housing. An opening corresponding to the piezoelectric transducer is opened on the cover plate. The cover plate is fixed on the ring seat through a sealing gasket. The cover plate cooperates with the piezoelectric transducer. The circuit board is connected to the piezoelectric transducer through a cable. The piezoelectric transducer detects the material level through the opening in the center of the cover plate. The circuit board is electrically connected to the cable. The cable is electrically connected to other mating devices through a gland fixedly installed on the side wall of the housing.

[0020] The beneficial effects of the present utility model are as follows:

[0021] The sensor of the present utility model can realize the zero-point self-learning function. After hoisting and through operation, the current belt surface height can be identified as the zero-point height. Therefore, the operation and installation are convenient and the accuracy is high;

[0022] The utility model linearly converts the detected material level height (0 - 2) m into a frequency quantity of (200 - 1000) Hz for output. Compared with the previous RS485 communication output form, the frequency quantity output has stronger matching performance and can be connected to belt conveyor control devices of various specifications without the need to change the RS485 protocol of the belt conveyor control device; compared with the previous current loop output form, the frequency quantity output can reduce the output power consumption while not reducing the anti-interference ability. Description of the Drawings

[0023] The drawings forming a part of the present utility model are used to provide a further understanding of the present utility model. The schematic embodiments and descriptions thereof of the present utility model are used to explain the present utility model and do not constitute an improper limitation of the present utility model. In the drawings:

[0024] Figure 1 It is a schematic structural diagram of an embodiment of the present utility model;

[0025] Figure 2 It is a principle block diagram of the present utility model;

[0026] Figure 3 It is a circuit diagram of the circuit board of the present utility model;

[0027] Figure 4 It is a circuit diagram of the power supply module of the present utility model;

[0028] Figure 5 It is a circuit diagram of the ambient temperature detection module of the present utility model;

[0029] Figure 6 It is a circuit diagram of the integrated key detection and light-emitting indication module of the present utility model;

[0030] Figure 7 It is a circuit diagram of the drive signal amplification module of the present utility model;

[0031] Figure 8 It is a circuit diagram of the return signal conditioning module of the present utility model;

[0032] Figure 9 It is a circuit diagram of the signal output module of the present utility model;

[0033] Figure 10 It is a schematic diagram of the sensor installation of the present utility model.

[0034] Description of the Reference Numerals:

[0035] 1. Housing; 11. Hoisting Ring; 2. Circuit Board; 21. Ring-shaped Indicator Light; 3. Ring Base; 4. Cover Plate; 5. Cable; 6. Cable Gland. Detailed Embodiments

[0036] It should be noted that, without conflict, the embodiments in the present utility model and the features in the embodiments can be combined with each other.

[0037] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present utility model, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0038] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood through specific circumstances.

[0039] The present utility model will be described in detail below with reference to the drawings and in combination with embodiments.

[0040] As shown in the figure, a level sensor with a zero-point self-learning function includes a housing 1 with an open lower end. A lifting ring 11 integrally provided with the housing 1 is fixed in the middle of the outside of the upper end of the housing 1. A ring seat 3 for installing a cover plate 4 is fixed at a position inside the housing 1 near the open lower end of the housing 1. An opening corresponding to the piezoelectric transducer is provided on the cover plate 4. The cover plate 4 is fixed to the lower end of the ring seat 3 through a gasket. The cover plate 4 cooperates with the piezoelectric transducer. The circuit board 2 is connected to the piezoelectric transducer through a cable. The piezoelectric transducer detects the level through the opening in the center of the cover plate 4. The circuit board 2 is electrically connected to the cable 5. The cable 5 is electrically connected to other mating devices through a gland 6 fixedly installed on the side wall of the housing 1.

[0041] An annular indicator light 21 is provided on the cover plate 4. The annular indicator light 21 is electrically connected to the circuit board 2. The annular indicator light 21 can present different flashing frequencies under the control of the circuit board 2. The flashing frequency of the annular indicator light 21 is directly proportional to the detected material level height, that is, the higher the material level, the faster the flashing frequency of the annular indicator light 21.

[0042] The circuit board 2 includes a single-chip microcomputer U1, a power supply module, an ambient temperature detection module, an integrated button detection and light-emitting indication module, a drive signal amplification module, a return signal conditioning module, a signal output module, and a piezoelectric transducer. The single-chip microcomputer U1 is electrically connected to the drive signal amplification module, and the drive signal amplification module is electrically connected to the piezoelectric transducer. The single-chip microcomputer U1 sends a signal to the drive signal amplification module, and the drive signal amplification module processes the received signal and then transmits it to the piezoelectric transducer. After receiving the signal, the piezoelectric transducer emits ultrasonic waves. After the ultrasonic waves encounter an obstacle and are reflected back, they are given back to the piezoelectric transducer again. The piezoelectric transducer is electrically connected to the return signal conditioning module, and the return signal conditioning module is electrically connected to the single-chip microcomputer U1. The return signal conditioning module processes the received signal and then feeds it back to the single-chip microcomputer U1 again. The single-chip microcomputer U1 is electrically connected to the signal output module, and the single-chip microcomputer U1 processes the signal fed back by the return signal conditioning module and then transmits it to the signal output module for output.

[0043] The single-chip microcomputer U1 is also electrically connected to the ambient temperature detection module. The ambient temperature detection module transmits the detected ambient temperature signal to the single-chip microcomputer U1, and the single-chip microcomputer U1 performs detection compensation according to the temperature information provided by the ambient temperature detection module.

[0044] The single-chip microcomputer U1 is also electrically connected to the integrated button detection and light-emitting indication module.

[0045] The power supply module supplies power to the single-chip microcomputer U1 and other modules.

[0046] The CCP module of the single-chip microcomputer U1 first works in the output comparison mode, emits 40 pulse trains of 200 kHz, and the single-chip microcomputer U1 simultaneously records the emission time t S . After the pulse train is power-amplified by the drive signal amplification module, it drives the piezoelectric transducer to oscillate and emit ultrasonic waves. When the ultrasonic waves encounter an obstacle during forward movement and are reflected, they are sensed by the piezoelectric transducer again. The return signal conditioning module filters and shapes the received sensed signal and then sends it to the input capture module in the single-chip microcomputer U1. The input capture module captures the received pulse and records the reception time t R . According to formula 1, the distance L between the sensor and the obstacle can be calculated, and then the obstacle height can be calculated according to the set zero point.

[0047] L = C * (tr - ts) / 2 (1)

[0048] C = C0 + 0.607 * T℃ (2)

[0049] In the formula, C0 is the sound wave velocity at zero degree, which is 332 m / s. T is the ambient temperature, measured by the ambient temperature detection module inside the sensor. The temperature measurement chip of the ambient temperature detection module is DS18B20.

[0050] The level height H = L0 - L. L0 is the zero-point distance learned by the sensor on-site.

[0051] This level sensor uses a 15° small wave beam angle for distance detection. The detection surface is small and concentrated, which not only minimizes the disturbance factors but also reduces the technical requirements for on-site installation and debugging (as Figure 10 shown).

[0052] The model of the single-chip microcomputer U1 is PIC16F1827. The model of the piezoelectric converter is KS105.

[0053] The power supply module includes a power supply chip U3. The positive electrode of the diode D1 is connected to the power supply VCC. The negative electrode of the diode D1 is electrically connected to the positive electrode of the diode D2. The negative electrode of the diode D2 is electrically connected to the pin 2 of the power supply chip U3. After the pin 2 of the power supply chip U3 is connected to the negative electrode of the diode D2, it is also electrically connected to one end of the capacitor C1. The other end of the capacitor C1 is connected to one end of the capacitor C2 and then connected to the GND pin of the power supply chip U3. The GND pin of the power supply chip U3 is grounded. The other end of the capacitor C2 is connected to the pin 3 of the power supply chip U3 and then outputs a +5V power supply.

[0054] The power supply chip U3 uses a low-ripple LDO type chip TLV70450. The dual reverse connection prevention diodes D1 and D2 are provided at the power supply inlet to prevent the reverse connection of the power supply line polarity. The input voltage range of the power supply module is 9 - 24V, and the output voltage is 5V.

[0055] The flight speed of ultrasonic waves in the air is affected by the ambient temperature. To reduce the error, an ambient temperature detection module is designed for temperature detection. The ambient temperature detection module includes a temperature sensor U2, and the model of the temperature sensor U2 is DS18B20. The peripheral circuit of this temperature sensor is simple and has a small volume. The single-chip microcomputer U1 can know the ambient temperature by communicating with it according to the protocol, and its accuracy can reach ±0.4°C. The pin 2 of the temperature sensor U2 is connected to the pin 8 of the single-chip microcomputer U1. The pin 1 of the temperature sensor U2 is connected to one end of the capacitor C4, and the other end of the capacitor C4 is grounded.

[0056] The integrated button detection and light-emitting indication module includes resistor R11 and resistor R12. One end of resistor R11 and resistor R12 are connected and then connected to the +5V power supply. The other end of resistor R11 is connected to the anode of the light-emitting diode. The cathode of the light-emitting diode is electrically connected to pin 2 of microcontroller U1. The light-emitting diode is the ring-shaped indicator light 21. The other end of resistor R12 is electrically connected to pin 1 of the button and one end of resistor R13. The other end of resistor R13 is connected to one end of capacitor C11 and then electrically connected to pin 1 of microcontroller U1. The other end of capacitor C11 is electrically connected to pin 2 of the button and then grounded. Microcontroller U1 detects the switch state of the button through digital pins. The circuit designs a low-pass filter circuit composed of resistor R12, resistor R13, and capacitor C11 to debounce the button. The flashing of the ring-shaped indicator light is controlled by pin RA3 of microcontroller U1.

[0057] The drive signal amplification module includes level shifter U21, and the model of level shifter U21 is SN65HVD3082. Pin 2 and pin 3 of level shifter U21 are connected and then electrically connected to pin 18 of microcontroller U1. Pin 4 of level shifter U21 is electrically connected to pin 17 of microcontroller U1 and is also electrically connected to the signal conditioning module. Pin 7 of level shifter U21 is electrically connected to one end of resistor R21. The other end of resistor R21 is electrically connected to one end of blocking capacitor C21. The other end of blocking capacitor C21 is electrically connected to pin 1 of intermediate frequency transformer U22. Pin 6 of level shifter U21 is electrically connected to one end of resistor R22. The other end of resistor R22 is electrically connected to one end of blocking capacitor C22. The other end of blocking capacitor C22 is electrically connected to pin 2 of intermediate frequency transformer U22.

[0058] Pin 4 of intermediate frequency transformer U22 is electrically connected to one end of capacitor C23. The other end of capacitor C23 is electrically connected to the piezoelectric transducer. Pin 3 of intermediate frequency transformer U22 is electrically connected to one end of capacitor C24. The other end of capacitor C24 is electrically connected to the piezoelectric transducer and then grounded. The model of the piezoelectric transducer is KS105.

[0059] Microcontroller U1 outputs a 200kHz pulse train through the output compare pin. After sending it out, microcontroller U1 turns off the output compare function of this pin and turns on the input capture function (to wait for the captured echo signal). The pulse train becomes a differential pulse train after passing through level shifter U21, and is connected to the primary side coil of step-up intermediate frequency transformer U22 through current-limiting resistor R21, resistor R22, and blocking capacitors C21, C22. After being stepped up by intermediate frequency transformer U22, the secondary side coil of intermediate frequency transformer U22 outputs a 100V amplitude pulse signal to drive the internal oscillator of the piezoelectric transducer to oscillate.

[0060] The return signal conditioning module includes a resistor R31 electrically connected to the piezoelectric transducer. One end of the resistor R31 is electrically connected to the piezoelectric transducer, and the other end of the resistor R31 is electrically connected to the negative electrode of the voltage regulator diode D31 and one end of the capacitor C31. The positive electrode of the voltage regulator diode D31 is grounded. The other end of the capacitor C31 is electrically connected to one end of the resistor R32. The other end of the resistor R32 is electrically connected to pin 2 of the amplifier U31.1 and then to one end of the resistor R33. The other end of the resistor R33 is electrically connected to pin 1 of the amplifier U31.1 and then to one end of the capacitor C33. The other end of the capacitor C33 is electrically connected to one end of the resistor R34. The other end of the resistor R34 is electrically connected to pin 2 of the amplifier U31.2 and then to one end of the resistor R35. The other end of the resistor R35 is electrically connected to pin 1 of the amplifier U31.2 and then to one end of the capacitor C34. The other end of the capacitor C34 is electrically connected to the negative electrode of the diode D33 and the positive electrode of the diode D32. The negative electrode of the diode D32 is electrically connected to one end of the capacitor C35 and pin 3 of the amplifier U32.1. The other end of the capacitor C35 and the positive electrode of the diode D33 are electrically connected to pin 4 of the amplifier U31.2 and then grounded.

[0061] Pin 2 of the amplifier U32.1 is electrically connected to one end of the resistor R36, the resistor R37, and the capacitor C36 and then to pin 3 of the amplifier U31.2 and pin 3 of the amplifier U31.1. The other end of the resistor R36 is connected to the +5V power supply. The other end of the resistor R37 is electrically connected to the other end of the capacitor C36 and then grounded. Pin 1 of the amplifier U32.1 is electrically connected to one end of the resistor R38. The other end of the resistor R38 is electrically connected to pin 17 of the single-chip microcomputer U1 and pin 4 of the level shifter U21.

[0062] The models of the amplifier U31.1, the amplifier U31.2, and the amplifier U32.1 are AD8028.

[0063] The working principle of the return signal conditioning module is that after the piezoelectric transducer emits ultrasonic waves, it enters the listening state. The monitored echo signal has its amplitude limited within 5V after passing through the resistor R31 and the voltage regulator diode D31. After the signal passes through the second-order filter circuit composed of the amplifier U31.1 and the amplifier U31.2, the high-frequency harmonics of the signal are filtered out. After the signal passes through the shaping circuit composed of the diode D32, the diode D33, and the capacitor C35, the pulse train becomes a wide pulse. This wide pulse is input to the output capture pin of the single-chip microcomputer U1 after passing through the amplitude comparison circuit composed of the amplifier U32.1.

[0064] The signal output module includes a resistor R42. One end of the resistor R42 is electrically connected to pin 9 of the single-chip microcomputer U1, and the other end of the resistor R42 is electrically connected to the base of the triode Q41. The emitter of the triode Q41 is electrically connected to the positive electrode of the diode D42 and the positive electrode of the voltage stabilizing diode D41, and the negative electrode of the diode D42 is grounded. The collector of the triode Q41 is electrically connected to the negative electrode of the voltage stabilizing diode D41 and one end of the resistor R41 and then signals are output, and the other end of the resistor R41 is connected to the power supply VCC.

[0065] The working principle of the signal output module is that the PWM output pin of the single-chip microcomputer U1 drives the triode Q41 to perform on-off switching operations. The resistor R41 raises the upper limit of the frequency output voltage to the input voltage. The voltage stabilizing diode D41 can absorb the interference harmonics on the connection wire and protect the triode Q41. The diode D42 is designed to prevent reverse wiring, so that the circuit will not be burned even if the signal wire is wrongly connected to the power supply wire.

[0066] An integrated waterproof button with a blue ring indicator 21 is installed at the bottom of the level sensor. The button is used to adjust the measuring zero point of the sensor on-site, and the ring indicator 21 is used to indicate the level height. The level sensor with the zero-point self-learning function is suspended and installed within the range of (0.5 - 2.2) m directly above the belt. After installation, empty the belt below the level sensor, power on the sensor, press and hold the zero-adjusting button for more than 5 seconds until the ring indicator 21 goes out and then release the button. After the single-chip microcomputer U1 receives this learning signal, it performs zero-point position detection, filtering, and recording. After 10 seconds, the sensor completes zero-point self-learning, identifies the current belt surface height as the zero-point height, and outputs a 200 Hz signal at the same time.

[0067] The level sensor linearly converts the detected level height of (0 - 2) m into a frequency quantity of (200 - 1000) Hz for output. Compared with the previous RS485 communication output form, the frequency quantity output has stronger compatibility and can be connected to various specifications of belt conveyor control devices without changing the RS485 protocol of the belt conveyor control device; compared with the previous current loop output form, the frequency quantity output can reduce the output power consumption while not reducing the anti-interference ability. For a mine intrinsically safe sensor, low power consumption is an important prerequisite for improving the intrinsic safety of the sensor circuit.

[0068] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A level sensor with zero point self-learning function, characterized in that: The circuit board (2) comprises a single-chip computer U1, a power module, an integrated key detection and light-emitting indication module, a drive signal amplification module, a return signal conditioning module, a signal output module and a piezoelectric converter. The single-chip computer U1 is electrically connected to the drive signal amplification module, which is electrically connected to the piezoelectric converter. The single-chip computer U1 sends a signal to the drive signal amplification module, which processes the received signal and transmits it to the piezoelectric converter. The piezoelectric converter transmits an ultrasonic wave after receiving the signal. The ultrasonic wave encounters an obstacle and is fed back to the piezoelectric converter. The piezoelectric converter is electrically connected to the return signal conditioning module, which is electrically connected to the single-chip computer U1. The return signal conditioning module processes the received signal and feeds it back to the single-chip computer U1. The single-chip computer U1 is electrically connected to the signal output module, and the single-chip computer U1 processes the signal fed back by the return signal conditioning module and transmits it to the signal output module for output. The power supply module supplies power to the single-chip microcomputer U1 and other modules. The integrated key detection and light-emitting indication module is electrically connected to the single-chip microcomputer U1. The integrated key detection and light-emitting indication module transmits a key signal to the single-chip microcomputer U1 to control the switch of the single-chip microcomputer U1. The single-chip microcomputer U1 also controls the annular indicator light (21) of the integrated key detection and light-emitting indication module.

2. The level sensor with zero point self-learning function according to claim 1 is characterized in that: The driving signal amplification module includes a level converter U21, wherein pins 2 and 3 of the level converter U21 are electrically connected to pin 18 of the single-chip microcomputer U1, pin 4 of the level converter U21 is electrically connected to pin 17 of the single-chip microcomputer U1 and is also electrically connected to the signal conditioning module, pin 7 of the level converter U21 is electrically connected to one end of a resistor R21, the other end of the resistor R21 is electrically connected to one end of a DC blocking capacitor C21, and the other end of the DC blocking capacitor C21 is electrically connected to pin 1 of an intermediate circuit U22. Connection, pin 6 of the level converter U21 is electrically connected to one end of the resistor R22, the other end of the resistor R22 is electrically connected to one end of the DC blocking capacitor C22, the other end of the DC blocking capacitor C22 is electrically connected to pin 2 of the intermediate circuit U22, pin 4 of the intermediate circuit U22 is electrically connected to one end of the capacitor C23, the other end of the capacitor C23 is electrically connected to the piezoelectric converter, pin 3 of the intermediate circuit U22 is electrically connected to one end of the capacitor C24, and the other end of the capacitor C24 is electrically connected to the piezoelectric converter and then grounded.

3. The level sensor with zero point self-learning function according to claim 1 is characterized in that: The return signal conditioning module includes a resistor R31 electrically connected to the piezoelectric converter, one end of the resistor R31 is electrically connected to the piezoelectric converter, the other end of the resistor R31 is electrically connected to the negative electrode of the voltage regulator D31 and one end of the capacitor C31, the positive electrode of the voltage regulator D31 is grounded, the other end of the capacitor C31 is electrically connected to one end of the resistor R32, the other end of the resistor R32 is electrically connected to pin 2 of the amplifier U31.1 and then to one end of the resistor R33, the other end of the resistor R33 is electrically connected to pin 1 of the amplifier U31.1 and then to one end of the capacitor C33, the other end of the capacitor C33 Electrically connected to one end of resistor R34, the other end of resistor R34 is electrically connected to pin 2 of amplifier U31.2 and then electrically connected to one end of resistor R35, the other end of resistor R35 is electrically connected to pin 1 of amplifier U31.2 and then electrically connected to one end of capacitor C34, the other end of capacitor C34 is electrically connected to the cathode of diode D33 and the anode of diode D32, the cathode of diode D32 is electrically connected to one end of capacitor C35 and pin 3 of amplifier U32.1, the other end of capacitor C35 and the anode of diode D33 are electrically connected to pin 4 of amplifier U31.2 and then grounded; Pin 2 of amplifier U32.1 is electrically connected to resistor R36, resistor R37, and one end of capacitor C36, and then electrically connected to pin 3 of amplifier U31.2 and pin 3 of U31.

1. The other end of resistor R36 is connected to a +5V power supply, and the other end of resistor R37 is electrically connected to the other end of capacitor C36 and then grounded. Pin 1 of amplifier U32.1 is electrically connected to one end of resistor R38, and the other end of resistor R38 is electrically connected to pin 17 of microcontroller U1 and pin 4 of level converter U21.

4. The level sensor with zero point self-learning function according to claim 1 is characterized in that: The signal output module includes a resistor R42, one end of which is electrically connected to pin 9 of the single-chip computer U1, the other end of which is electrically connected to the base of the transistor Q41, the emitter of the transistor Q41 is electrically connected to the positive electrode of the diode D42 and the positive electrode of the voltage-regulating tube D41, the negative electrode of the diode D42 is grounded, the collector of the transistor Q41 is electrically connected to the negative electrode of the voltage-regulating tube D41 and one end of the resistor R41 for signal output, and the other end of the resistor R41 is connected to the power supply VCC.

5. The level sensor with zero point self-learning function according to claim 1 is characterized in that: The power module includes a power chip U3, the positive electrode of the diode D1 is connected to the power supply VCC, the negative electrode of the diode D1 is electrically connected to the positive electrode of the diode D2, the negative electrode of the diode D2 is electrically connected to pin 2 of the power chip U3, pin 2 of the power chip U3 is connected to the negative electrode of the diode D2 and is also electrically connected to one end of the capacitor C1, the other end of the capacitor C1 is connected to one end of the capacitor C2 and is connected to the GND pin of the power chip U3, the GND pin of the power chip U3 is grounded, and the other end of the capacitor C2 is connected to pin 3 of the power chip U3 to output a +5V power supply.

6. The level sensor with zero point self-learning function according to claim 1 is characterized in that: The integrated key detection and light-emitting indication module comprises a resistor R11 and a resistor R12, one end of the resistor R11 and the resistor R12 are connected and then connected to a +5V power supply, the other end of the resistor R11 is connected to the positive electrode of a light-emitting diode, the negative electrode of the light-emitting diode is electrically connected to pin 2 of a single-chip computer U1, the light-emitting diode is a ring-shaped indicator light (21), the other end of the resistor R12 is electrically connected to pin 1 of the key and one end of the resistor R13, the other end of the resistor R13 is connected to one end of a capacitor C11 and then electrically connected to pin 1 of the single-chip computer U1, the other end of the capacitor C11 is electrically connected to pin 2 of the key and then grounded.

7. The level sensor with zero point self-learning function according to claim 1 is characterized in that: The single-chip microcomputer U1 is also electrically connected to the ambient temperature detection module. The ambient temperature detection module transmits the detected ambient temperature signal to the single-chip microcomputer U1. The single-chip microcomputer U1 performs detection compensation according to the temperature information provided by the ambient temperature detection module.

8. The level sensor with zero point self-learning function according to claim 1 is characterized in that: The model of microcontroller U1 is PIC16F1827.

9. The level sensor with zero point self-learning function according to claim 1 is characterized in that: The model of the piezoelectric converter is KS105.

10. The level sensor with zero point self-learning function according to claim 1, characterized in that: The invention comprises a shell (1) with an opening at the lower end, a lifting ring (11) integrally arranged with the shell (1) is fixed in the middle of the outer portion of the upper end of the shell (1), a ring seat (3) for mounting a cover plate (4) is fixed at a position close to the lower end opening of the shell (1) inside the shell (1), an opening corresponding to the piezoelectric converter is opened on the cover plate (4), the cover plate (4) is fixed to the lower end of the ring seat (3) through a sealing gasket, the cover plate (4) cooperates with the piezoelectric converter, the circuit board (2) is electrically connected to the piezoelectric converter through a cable, the piezoelectric converter detects the object level through the opening at the center of the cover plate (4), the circuit board (2) is electrically connected to the cable (5), and the cable (5) is electrically connected to other matching equipment through a cable gland (6) fixedly installed on the side wall of the shell (1).

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