Intelligent liquid level monitoring and early warning device for rail transit vehicle

Abstract

The utility model relates to the technical field of water supply systems of rail transit vehicles, in particular to an intelligent liquid level monitoring and early warning device for a rail transit vehicle, which comprises a liquid level acquisition plate and a liquid level display plate. The liquid level acquisition plate comprises a capacitance induction electrode, a multi-channel digital capacitance processing chip, a microprocessor, a temperature sensor and a communication interface circuit which are arranged along the length direction of the plate, and the multi-channel digital capacitance processing chip is connected with the capacitance induction electrode; the microprocessor processes the capacitance signal and the temperature signal to obtain liquid level information and sends the liquid level information to an external bus through the communication interface circuit. The liquid level display panel is provided with a bus interface, a display drive circuit, a liquid crystal display unit, an acousto-optic early warning unit and a parameter setting key, and the liquid level of the water tank can be displayed and early warned in a grading mode. According to the utility model, non-contact accurate detection and multi-stage acousto-optic intelligent early warning of the liquid level of the water supply tank of the rail transit vehicle are realized, and the device has the advantages of compact structure, convenience in installation and maintenance and strong anti-interference capability.

Description

TECHNICAL FIELD

[0001] The utility model relates to rail transit vehicle water supply system technical field, concretely relates to a rail transit vehicle intelligent liquid level monitoring and early warning device. BACKGROUND

[0002] Rail transit vehicles are usually provided with water supply tanks for toilets, dining cars and air conditioning systems, and the liquid level of the water tank needs to be monitored in real time to ensure the safety of vehicle operation and the comfort of passengers. Currently, mechanical float switches, pressure type liquid level transmitters or plug-in electrode liquid level meters are used to realize liquid level detection in engineering. These devices generally need to be installed on the water tank with a hole, and the sensing element is in contact with water for a long time, which is prone to fouling, corrosion or jamming, resulting in unresponsive or false or missed reports. Patent CN211855508U discloses a liquid level detection device using a mechanical float switch. The device needs to install a float ball mechanism on the water tank, and the float ball is prone to scale attachment and mechanical jamming when immersed in water for a long time, resulting in switch malfunction. In addition, the rail vehicle operates in a large vibration environment and has strong electromagnetic interference. The traditional analog liquid level signal is easily distorted during long-distance transmission and is difficult to achieve fine liquid level display and remote centralized monitoring. It also lacks the ability to intelligently analyze and provide early warning for liquid level changes. Patent CN207907999U discloses a pressure type liquid level transmitter with analog output. The device measures the liquid level through a pressure sensor, and the analog signal is easily disturbed in the complex electromagnetic environment of the rail vehicle, affecting the measurement accuracy and system stability.

[0003] The existing rail transit vehicle liquid level monitoring device has the following disadvantages: first, most of them are contact type structures that need to damage the integrity of the water tank, have leakage risks and high maintenance and replacement costs; second, they use single-point switches or low-resolution analog output, making it difficult to reflect the continuous change of the liquid level in the water tank and providing accurate percentage display; third, the electrical interface is mostly non-isolated, which easily introduces interference into the control network in the complex electromagnetic environment of the vehicle, affecting the system stability; fourth, most products only output a simple alarm signal when the liquid level is low to the limit, and cannot provide early warning prompts in combination with the liquid level change rate, which may affect operation due to water shortage on the way. UTILITY MODEL CONTENTS

[0004] The utility model aims to provide a rail transit vehicle intelligent liquid level monitoring and early warning device with compact structure, non-contact installation, isolated communication and multi-level early warning function to improve the reliability and intelligent level of liquid level monitoring.

[0005] To solve the above technical problems, the utility model adopts the following technical scheme:

[0006] The liquid level acquisition board is a strip-shaped circuit board arranged along the height direction of the water tank and fixedly installed on the outer wall of the non-metal tank body, and one side of the liquid level acquisition board is provided with a capacitive sensing electrode extending along the length direction of the board.

[0007] The multi-channel digital capacitive processing chip is arranged on the liquid level acquisition board, and the capacitive measuring channels of the multi-channel digital capacitive processing chip are electrically connected with the capacitive sensing electrode, for collecting the capacitive signal reflecting the liquid level and outputting the corresponding digital signal.

[0008] The microprocessor is arranged on the liquid level acquisition board, and the data input end of the microprocessor is electrically connected with the data output end of the multi-channel digital capacitive processing chip, for processing the digital signal to obtain the current liquid level information.

[0009] In the technical scheme, the capacitive sensing electrode includes a plurality of electrode segments arranged in sequence along the height direction of the water tank, each electrode segment is electrically connected with a different capacitive measuring channel of the multi-channel digital capacitive processing chip, and the output end of the microprocessor outputs the liquid level percentage signal.

[0010] In the technical scheme, the liquid level acquisition board is further provided with a temperature sensor, the temperature sensor is electrically connected with the temperature signal input end of the microprocessor, and the microprocessor performs temperature compensation processing on the liquid level information according to the temperature signal.

[0011] In the technical scheme, the liquid level acquisition board is provided with a memory electrically connected with the microprocessor, and the memory stores the calibration capacitance data corresponding to different liquid level heights and the temperature compensation coefficient.

[0012] In the technical scheme, the liquid level acquisition board is fixed to the outer wall of the non-metal tank body through a slot type mounting structure, the outer wall of the non-metal tank body is provided with a mounting slot matching the size of the liquid level acquisition board, the liquid level acquisition board is inserted into the mounting slot and fixed through a limiting structure, and the circuit surface of the liquid level acquisition board is provided with an insulating protective layer.

[0013] In the technical scheme, the liquid level acquisition board is further provided with a communication interface circuit, the signal end of the communication interface circuit is electrically connected with the communication end of the microprocessor, and the communication interface circuit is used for sending the liquid level information to an external bus.

[0014] In the technical scheme, the communication interface circuit is an isolation type serial communication interface circuit, which includes a serial communication chip connected with the microprocessor, an isolation device electrically connected with the serial communication chip, and an isolation power module, the serial communication chip is used for realizing communication with an external RS485 bus, and the isolation device and the isolation power module are used for realizing electrical isolation between the liquid level acquisition board and the control network of the rail transit vehicle.

[0015] With the technical scheme, the liquid level display board is arranged in the vehicle equipment cabinet, the liquid level display board is in communication connection with the communication interface circuit of the liquid level collecting board through the external bus, the liquid level display board is provided with a bus interface connected with the external bus, a display drive circuit electrically connected with the bus interface, a digital display unit electrically connected with the display drive circuit and an audible and light warning unit, and is used for displaying the water tank liquid level information and controlling the audible and light warning unit to output a warning signal when the liquid level reaches a preset warning condition.

[0016] With the technical scheme, the audible and light warning unit includes at least two indicator lights of different colors and a buzzer, the indicator lights and the buzzer are electrically connected with the display drive circuit respectively, the indicator lights of different colors are used for indicating different liquid level states, and the buzzer is used for outputting a warning sound.

[0017] With the technical scheme, the digital display unit is a liquid crystal display, and is used for displaying the current water tank liquid level in percentage form; the liquid level display board is further provided with a parameter setting button, the parameter setting button is electrically connected with the display drive circuit, and is used for setting a liquid level warning threshold.

[0018] With the technical scheme, the technical progress achieved by the utility model relative to the prior art is:

[0019] The intelligent liquid level monitoring device for rail transit vehicles is fixedly installed on the outer wall of the nonmetallic tank body of the water tank, the non-contact liquid level detection is realized by the mode that the capacitive sensing electrode forms a capacitor with the liquid through the outer wall of the nonmetallic tank body, the sensing element does not need to be directly contacted with the liquid, the problems that the traditional contact type sensor is easy to be corroded, scaled and polluted by the liquid are effectively avoided, the reliability and service life of the device are remarkably improved, and the maintenance cost is reduced. The capacitive signal is collected and the digital signal is directly output by using the multi-channel digital capacitive processing chip, the defects that the analog signal is easy to be disturbed and attenuated in the transmission process are avoided, the precision of liquid level measurement and the anti-interference ability of the system are improved. The capacitive sensing electrode, the digital capacitive processing chip and the microprocessor are integrated on the liquid level collecting board, the design is compact and reasonable, the device is convenient to install and use in the limited space of the rail transit vehicle, and has good engineering application value. BRIEF DESCRIPTION OF DRAWINGS

[0020] The utility model will be further described in connection with the drawings.

[0021] Figure 1 It is the whole principle schematic view of the utility model's intelligent liquid level monitoring and early warning device for rail transit vehicles;

[0022] Figure 2 It is the circuit structure schematic view of the utility model's liquid level collecting board;

[0023] Figure 3 The utility model discloses a circuit structure schematic drawing of liquid level display board.

[0024] Figure 4 The utility model discloses a work flow chart.

[0025] In the drawing: 1, liquid level acquisition board;11, capacitive sensing electrode;12, multichannel digital capacitive processing chip;13, temperature sensor;14, microprocessor;15, communication interface circuit;2, liquid level display board. DETAILED DESCRIPTION

[0026] The utility model will be further explained in detail in connection with the embodiment:

[0027] Embodiment 1

[0028] As Figures 1-4 Indicated, the utility model provides a kind of intelligent liquid level monitoring and early warning device for rail transit vehicle, comprising:

[0029] Liquid level acquisition board 1 installed on the outer wall of feed water tank and liquid level display board 2 installed in vehicle equipment cabinet.Liquid level acquisition board 1 installed on the outer wall of feed water tank and liquid level display board 2 installed in vehicle equipment cabinet.Liquid level acquisition board 1 installed on the outer wall of feed water tank and liquid level display board 2 installed in vehicle equipment cabinet.

[0030] Liquid level acquisition board 1 is strip printed circuit board, its length is slightly less than the length of mounting groove, and the width is matched with mounting groove.A row or multiple rows of copper foil electrodes are arranged on the board body of liquid level acquisition board 1 along one side of long side, and the electrodes are covered with insulating coating, and the whole forms capacitive sensing electrode 11.Capacitive sensing electrode 11 is divided into several equal-length electrode segments along the height direction on the board, and each electrode segment is connected to the corresponding input end of multichannel digital capacitive processing chip 12 by wire.Liquid level acquisition board 1 board surface faces the outer wall of tank, and capacitive sensing electrode 11 is tightly attached to the outer surface of tank, and a thin air layer required by design can be maintained in the middle.

[0031] Multichannel digital capacitive processing chip 12 is welded in the circuit area of liquid level acquisition board 1, and the power supply end VDD thereof is connected to +3.3V power bus, and the ground end is connected to common ground wire GND.The chip provides a plurality of independent capacitive measurement channels CH1~CHn, and the input electrodes of each channel are connected to the corresponding capacitive sensing electrode 11 through printed wires.The chip internally contains excitation signal generation, sample and hold, A / D conversion and digital filter circuit, and can convert the capacitive change of each channel into digital output.Its digital interface end SDA / SCL or MOSI / MISO / SCK is connected to the corresponding communication pin of microprocessor 14 through bus.

[0032] A microprocessor 14 is also mounted on the liquid level acquisition board 1, with its power supply pin VDD connected to the +3.3V power bus and its grounding pin VSS connected to the common ground. The communication pin of the microprocessor 14 is connected to the digital interface of the multi-channel digital capacitance processing chip 12 through a wire. A non-volatile memory is also welded on the liquid level acquisition board 1, with its communication terminal connected to the microprocessor 14 through an SPI bus, for storing the calibration capacitance data of each electrode segment and the temperature compensation coefficient.

[0033] To obtain temperature information, a temperature sensor 13 is arranged on the liquid level acquisition board 1. The temperature sensor 13 adopts a digital temperature sensor 13 chip, with its power supply end connected to +3.3V and GND, and its data end connected to the digital input pin of the microprocessor 14. The temperature sensor 13 is arranged at a position close to the outer wall of the water tank, for accurately reflecting the ambient temperature around the water tank.

[0034] A power supply and protection circuit is also arranged on the liquid level acquisition board 1. The input end of the power supply and protection circuit is connected to the DC power supply provided by the rail vehicle through a terminal. The power supply and protection circuit internally has a reverse connection protection diode, a fuse resistor and a surge absorbing device, and then the input voltage is converted into stable +5V and +3.3V outputs through a DC-DC module. The +5V is mainly used for the power supply of the transceiver of the isolated communication interface circuit 15, and the +3.3V is used for the power supply of the multi-channel digital capacitance processing chip 12, the microprocessor 14, the memory and the temperature sensor 13.

[0035] The communication interface circuit 15 adopts an isolated RS485 serial interface structure, including a digital isolation device connected to the serial port pin of the microprocessor 14 and an RS485 transceiver chip located on the bus side. One side of the power supply end of the digital isolation device is connected to +3.3V, and the other side of the power supply end is connected to +5V through an isolated DC-DC power supply module, realizing double isolation of signals and power supply. The A and B ends of the RS485 transceiver chip are led out through a terminal seat and connected to the liquid level display board 2 in the vehicle equipment cabinet or the RS485 bus of the whole vehicle control network. Through this isolated structure, the surge, electromagnetic interference and common mode voltage on the side of the rail vehicle control system will not directly act on the weak current circuit of the liquid level acquisition board 1.

[0036] The liquid level display board 2 is installed in the vehicle equipment cabinet, with a bus interface, a display board microprocessor, a display driving circuit, a liquid crystal display unit, an indicator light assembly, a buzzer and parameter setting buttons arranged thereon. The A and B ends of the RS485 transceiver chip on the bus interface are connected to the communication interface circuit 15 of the liquid level acquisition board 1 through a cable, with its transceiver control pin connected to the serial port pin of the display board microprocessor. The power supply end of the display board microprocessor is connected to the +3.3V output by the DC-DC power supply on the board, and the ground end is connected to the common ground.

[0037] The display driving circuit can adopt a segment code type liquid crystal special driving chip or a general I / O scanning circuit, a control port of which is connected to a plurality of I / O pins of the display panel microprocessor, and an output end is connected to each segment electrode and a common electrode of the liquid crystal display unit, so that the display of the liquid level percentage number and simple symbols is realized. The indicator light assembly includes a green LED for indicating a normal state, a yellow LED for indicating a low liquid level pre-warning, and a red LED for indicating a low liquid level alarm, each LED is connected to an output end of the display panel microprocessor through a current limiting resistor and grounded at the other end. The buzzer adopts an active or passive buzzer, one end of which is connected to a power supply, and the other end is connected to a control pin of the display panel microprocessor through a driving triode, and the display panel microprocessor controls the buzzer to sound intermittently or continuously by outputting high and low levels. The parameter setting button sets a plurality of contacts, one end of which is grounded, and the other end is connected to an input end of the display panel microprocessor, and the user can set the liquid level pre-warning threshold, alarm threshold and device communication address and other parameters by pressing the button for a short time or a long time.

[0038] The working process of the device is as follows:

[0039] After the vehicle is powered on, the power supply and the protection circuit obtain power from the DC power supply of the rail vehicle, and provide stable DC power to the liquid level acquisition panel 1 and the liquid level display panel 2 after passing through the protection element and the DC-DC module. After the microprocessor 14 on the liquid level acquisition panel 1 completes the power-on self-test, the current capacitance data of each channel of the multi-channel digital capacitance processing chip 12 is read through the SPI bus, and the temperature value of the temperature sensor 13 is read through the digital interface.

[0040] The microprocessor 14 converts the capacitance data of each channel into corresponding segmented liquid levels according to the calibrated capacitance-liquid level corresponding relationship and the temperature compensation coefficient in the memory, and then combines the liquid level height and the liquid level percentage of the entire water tank through interpolation or weighting. The specific liquid level calculation algorithm is as follows: first, read the capacitance measurement values C1, C2,..., Cn corresponding to each electrode segment; then, according to the pre-calibrated capacitance-liquid level mapping table in the memory, the liquid level height h1, h2,..., hn of each segment is calculated through the linear interpolation method; finally, the total liquid level height H is obtained by weighted summation of the liquid level height of each segment, and is converted into the liquid level percentage P=H / Hmax*100%.

[0041] The temperature compensation processing adopts the temperature coefficient correction method in the prior art: reading the current temperature T, correcting the capacitance measurement value according to the temperature compensation coefficient a stored in the memory, and the correction formula is C'=C* [1+ a* (T-T0)], wherein T0 is the calibration temperature. The temperature compensation method is a conventional technical means in the field of capacitance measurement.

[0042] During operation, microprocessor 14 continuously samples the data of each channel at a preset sampling period (e.g. 100 ms), and stores the percentage of liquid level values of the last several periods (e.g. 10 periods) in the internal RAM, from which the rate of change of liquid level is calculated. The calculation method of the rate of change of liquid level is: ΔP / Δt = (Pn-Pn-k) / (k×T), where Pn is the current percentage of liquid level, Pn-k is the percentage of liquid level k sampling periods ago, and T is the sampling period.

[0043] Microprocessor 14 compares the current percentage of liquid level with the low liquid level warning threshold (e.g. 30%) and the low liquid level alarm threshold (e.g. 10%), and estimates whether the liquid level will be lower than the safety threshold within a preset prediction time (e.g. 30 minutes) based on the rate of change of liquid level. The prediction algorithm uses linear extrapolation method: predicted liquid level P_prediction = P_current + ΔP / Δt × t_prediction. If P_prediction is lower than the safety threshold, a warning flag is generated in advance. The prediction algorithm is a basic method in the field of time series analysis.

[0044] Microprocessor 14 periodically sends data frames including the percentage of liquid level, status flags, device address, etc. to liquid level display panel 2 through isolated RS485 communication interface circuit 15 according to the communication protocol. The communication protocol uses the standard Modbus RTU protocol, and the data frame format includes: device address (1 byte), function code (1 byte), data area (N bytes), and CRC check (2 bytes).

[0045] The display panel microprocessor on liquid level display panel 2 receives data frames from liquid level acquisition panel 1 through RS485 bus, and extracts the current percentage of liquid level and warning state information after verification and analysis. The display panel microprocessor generates corresponding digital data according to the percentage of liquid level, and controls the liquid crystal display unit to display the real-time percentage of liquid level through the display driving circuit.

[0046] For the warning state, if the liquid level is in the normal interval (higher than the warning threshold), the green indicator light is lit, the yellow and red indicator lights are turned off, and the buzzer remains silent; when the liquid level approaches the warning threshold or is predicted to be lower than the warning threshold within a certain time according to the rate of change of liquid level, the display panel microprocessor lights up the yellow indicator light and drives the buzzer to beep in an intermittent manner (e.g. 1 Hz frequency), prompting the driver or maintenance personnel to pay attention to water replenishment; when the liquid level is lower than the alarm threshold, the red indicator light is lit, and the buzzer is driven to beep in a continuous manner or with a higher duty cycle (e.g. 5 Hz frequency), prompting immediate action. The above warning grading processing method is a conventional technical means in the field of industrial control.

[0047] When the early warning threshold needs to be adjusted, the maintenance personnel can press the parameter setting button in the equipment cabinet, the display board microprocessor enters the setting mode, the parameters are modified and saved through the combination action of the button, the new parameters are written into the memory of the liquid level acquisition board 1 through the bus for subsequent operation. During the long-term operation of the vehicle, if the water tank is replaced or the size of the water tank is modified, the calibration curve in the memory can also be updated through the same interface during the factory debugging stage to adapt to water tanks of different structures.

[0048] The utility model ensures the integrity of the water tank structure and does not directly contact with the liquid, realizes the continuous and accurate monitoring of the liquid level of the water supply tank of the rail transit vehicle, realizes the remote liquid level display and multi-stage sound and light early warning through the isolation communication structure and the liquid level display board 2 arranged in the equipment cabinet, and the overall structure of the device is clear and convenient to popularize and apply in the rail transit vehicle.

[0049] The above has made a detailed description of the utility model, but some modifications or improvements can be made on the basis of the utility model, which is obvious to those skilled in the art. Therefore, the modifications or improvements without departing from the spirit of the utility model are within the protection scope of the utility model.

Claims

1. An intelligent liquid level monitoring and early warning device for rail transit vehicles, characterized in that, include: Liquid level acquisition plate (1), the liquid level acquisition plate (1) is a strip circuit board arranged along the height direction of the water tank, and is fixedly installed on the non-metallic outer wall of the water tank. A capacitive sensing electrode (11) extending along the length direction of the plate is provided on one side of the liquid level acquisition plate (1). The capacitive sensing electrode (11) forms a capacitor with the liquid in the water tank through the non-metallic outer wall of the tank. The multi-channel digital capacitance processing chip (12) is disposed on the liquid level acquisition plate (1). The capacitance measurement channel of the multi-channel digital capacitance processing chip (12) is electrically connected to the capacitance sensing electrode (11) and is used to acquire the capacitance signal reflecting the liquid level and output the corresponding digital signal. The microprocessor (14) is mounted on the liquid level acquisition board (1). The data input terminal of the microprocessor (14) is electrically connected to the data output terminal of the multi-channel digital capacitor processing chip (12) to process the digital signal to obtain the current liquid level information.

2. The intelligent liquid level monitoring and early warning device for rail transit vehicles according to claim 1, characterized in that: The capacitance sensing electrode (11) includes several electrode segments arranged sequentially along the height direction of the water tank. Each electrode segment is electrically connected to a different capacitance measurement channel of the multi-channel digital capacitance processing chip (12). The output terminal of the microprocessor (14) outputs a liquid level percentage signal.

3. The intelligent liquid level monitoring and early warning device for rail transit vehicles according to claim 1, characterized in that: The liquid level acquisition plate (1) is also equipped with a temperature sensor (13), which is electrically connected to the temperature signal input terminal of the microprocessor (14). The microprocessor (14) performs temperature compensation processing on the liquid level information according to the temperature signal.

4. The intelligent liquid level monitoring and early warning device for rail transit vehicles according to claim 3, characterized in that: The liquid level acquisition plate (1) is provided with a memory that is electrically connected to the microprocessor (14). The memory stores calibration capacitance data and temperature compensation coefficients corresponding to different liquid level heights.

5. The intelligent liquid level monitoring and early warning device for rail transit vehicles according to claim 1, characterized in that: The liquid level acquisition plate (1) is fixed to the outer wall of the non-metallic box through a slot-type installation structure. The outer wall of the non-metallic box is provided with an installation groove that matches the size of the liquid level acquisition plate (1). The liquid level acquisition plate (1) is inserted into the installation groove and fixed by a limiting structure. The circuit surface of the liquid level acquisition plate (1) is provided with an insulating protective layer.

6. The intelligent liquid level monitoring and early warning device for rail transit vehicles according to claim 1, characterized in that: The liquid level acquisition board (1) is also provided with a communication interface circuit (15). The signal end of the communication interface circuit (15) is electrically connected to the communication end of the microprocessor (14) and is used to send the liquid level information to the external bus.

7. The intelligent liquid level monitoring and early warning device for rail transit vehicles according to claim 6, characterized in that: The communication interface circuit (15) is an isolated serial communication interface circuit, including a serial communication chip connected to the microprocessor (14), an isolation device electrically connected to the serial communication chip, and an isolation power supply module. The serial communication chip is used to realize communication with an external RS485 bus, and the isolation device and the isolation power supply module are used to realize electrical isolation between the liquid level acquisition board (1) and the rail transit vehicle control network.

8. The intelligent liquid level monitoring and early warning device for rail transit vehicles according to claim 1, characterized in that: It also includes a liquid level display panel (2), which is installed in the vehicle equipment cabinet. The liquid level display panel (2) is connected to the communication interface circuit (15) of the liquid level acquisition board (1) via an external bus. The liquid level display panel (2) is provided with a bus interface connected to the external bus, a display driving circuit electrically connected to the bus interface, a digital display unit electrically connected to the display driving circuit, and an audible and visual warning unit, which are used to display the water tank liquid level information and control the audible and visual warning unit to output a warning signal when the liquid level reaches the preset warning condition.

9. The intelligent liquid level monitoring and early warning device for rail transit vehicles according to claim 8, characterized in that: The audible and visual warning unit includes at least two different colored indicator lights and a buzzer. The indicator lights and the buzzer are electrically connected to the display driving circuit. The different colored indicator lights are used to indicate different liquid level states, and the buzzer is used to output a warning sound.

10. The intelligent liquid level monitoring and early warning device for rail transit vehicles according to claim 8, characterized in that: The digital display unit is a liquid crystal display used to display the current water tank level as a percentage; the liquid level display panel (2) is also provided with a parameter setting button, which is electrically connected to the display driving circuit and used to set the liquid level warning threshold.

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