Dielectric matrix moisture sensor

Abstract

The utility model belongs to the technical field of moisture sensors, and particularly relates to a dielectric matrix moisture sensor which comprises a sensor shell, a bottom cover is mounted at one end of the sensor shell, two copper ring electrodes are mounted on the outer side of the sensor shell, and a nylon ring is arranged on the outer side of the sensor shell and located between the two copper ring electrodes. A top cover is installed at the other end of the sensor shell, a cable is fixed in the sensor shell and penetrates through the top cover, a PVC pipe body is arranged on the outer side of the sensor shell, sealing structures are installed at the two ends in the PVC pipe body and used for sealing the sensor shell, and a 100 MHz oscillator is further installed in the sensor shell. The 100MHz oscillator is used for generating a high-frequency oscillation signal with the frequency of 100MHz. The water content of the soil matrix can be detected, water can be effectively prevented from entering the sensor, the long-term stable operation of the sensor is ensured, and meanwhile, the accuracy and reliability of measurement are improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of water content sensor, specifically relates to a dielectric matrix water content sensor. BACKGROUND

[0002] In the field of modern agriculture, horticulture and environmental monitoring, accurate measurement of the water content of the substrate is of great significance to the growth management of crops, the rational allocation and utilization of water resources. Traditional soil water content measurement methods include weight method, tension meter method, time domain reflectometry (TDR) and the like. However, these methods often have the disadvantages of complex operation, high cost and slow measurement speed, and are not suitable for substrate moisture detection. Therefore, it is particularly important to develop a simple, fast and low-cost method for measuring the water content of the substrate.

[0003] As a new type of water content measurement tool, the dielectric water content sensor is based on the relationship between the dielectric constant and the water content. The dielectric constant of the substrate increases with the increase of the water content. Therefore, by measuring the dielectric constant of the substrate, the water content of the substrate can be indirectly measured. However, the existing dielectric substrate moisture sensor has some problems in actual application, such as limited detection range, easy water entry into the sensor, inaccurate measurement results, and even damage to the sensor.

[0004] In view of the deficiencies of the prior art, the utility model provides an improved dielectric substrate moisture sensor. UTILITY MODEL CONTENT

[0005] The utility model aims at providing a dielectric substrate moisture sensor which can detect the water content of the substrate and effectively prevent water from entering the sensor, ensuring the long-term stable operation of the sensor and improving the measurement accuracy and reliability.

[0006] The technical scheme adopted by the utility model is as follows:

[0007] A dielectric substrate moisture sensor comprises a sensor shell, a bottom cover is installed at one end of the sensor shell, two copper ring electrodes are installed on the outer side of the sensor shell, a nylon ring is arranged between the two copper ring electrodes on the outer side of the sensor shell, and a top cover is installed at the other end of the sensor shell.

[0008] A cable is fixed in the sensor shell, and the cable passes through the top cover.

[0009] A PVC pipe body is arranged on the outer side of the sensor shell, sealing structures are installed at both ends in the PVC pipe body, and the sealing structures are used to seal the sensor shell.

[0010] The sensor shell is further provided with:

[0011] 100MHz oscillator, for generating a high-frequency oscillation signal with a frequency of 100MHz, which is used for interacting with the matrix and generating a corresponding induction signal;

[0012] Impedance matcher, for matching the impedance between the 100MHz oscillator and the subsequent circuit;

[0013] Band-pass filter, for filtering the signal after the impedance matcher;

[0014] Micro-signal amplifier, for linearly amplifying the electrical signal, improving the amplitude of the signal, while keeping the waveform and frequency characteristics of the signal unchanged;

[0015] Two high-frequency analog signal detectors, for detecting the amplified high-frequency signal;

[0016] Signal processing module, for further processing and analyzing the signals output by the two high-frequency analog signal detectors, and converting the detected signals into actual measurement values.

[0017] The waterproof terminal is fixed on the bottom cover and the top cover in the direction away from each other, and the cable line passes through the waterproof terminal and extends to the outside of the sensor shell.

[0018] The rubber ring is arranged on the outside of the sensor shell and on the two sides of the two copper ring electrodes.

[0019] The sealing structure comprises two sealing sheets arranged inside the PVC pipe body, the cable line passes through the sealing sheets and extends to the outside of the PVC pipe body, and the inner wall of the PVC pipe body is provided with a sealing groove at a position corresponding to the sealing sheets, and the sealing sheets are clamped into the sealing groove.

[0020] Two second rubber balls are arranged on the two sides of the sealing sheet and close to the edge position, a first rubber ball is arranged on the inner wall of the sealing groove and between the two second rubber balls, and the first rubber ball and the second rubber ball abut each other.

[0021] The utility model discloses the technical effect achieved is:

[0022] The utility model discloses can detect the water content of soil matrix, and can effectively avoid the water in the sensor, ensure the long -term stable operation of sensor, improve the accuracy and reliability of measurement simultaneously. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic view of the utility model;

[0024] Figure 2 is a sectional view of the PVC pipe body in the utility model;

[0025] Figure 3 is a structural schematic view among the waterproof terminal, nylon ring and rubber ring in the utility model;

[0026] Figure 4 is a structural schematic view among the PVC pipe body, cable line and sealing sheet in the utility model;

[0027] Figure 5 is a structural schematic view among the first rubber ball, second rubber ball and sealing groove in the utility model.

[0028] In the drawings, the component list represented by each sign is as follows:

[0029] 1, bottom cover;2, top cover;3, waterproof terminal;4, cable line;5, sensor shell;6, copper ring electrode;7, nylon ring;8, rubber ring;9, PVC pipe body;10, sealing sheet;11, sealing groove;12, first rubber ball;13, second rubber ball. DETAILED DESCRIPTION

[0030] In order to make the purpose and advantages of the utility model more clear and explicit, the following specific description of the utility model is combined with examples. It should be understood that the following text is only used to describe one or several specific embodiments of the utility model, and does not strictly limit the protection scope of the utility model.

[0031] As Figures 1-5 Indicated, a kind of dielectric matrix moisture sensor, including sensor shell 5, one end of sensor shell 5 is equipped with bottom cover 1, the outside of sensor shell 5 is equipped with two copper ring electrodes 6, with reference to the drawings Figure 3 The outside of sensor shell 5 and located between two copper ring electrodes 6 is provided with nylon ring 7, the nylon ring 7 can also be arranged between two rubber rings 8, the other end of sensor shell 5 is equipped with top cover 2;

[0032] The two copper ring electrodes 6 can be regarded as a capacitor, by the setting of two copper ring electrodes 6, by nylon ring 7, the edge field generated by two copper ring electrodes 6 enters into surrounding matrix, and the dielectric constant of surrounding matrix is measured, and finally converted into the volume moisture content of matrix;

[0033] The cable 4 is fixed inside the sensor shell 5 and passes through the top cover 2. The waterproof terminal 3 is fixed on the bottom cover 1 and the top cover 2 away from each other, and the cable 4 passes through the waterproof terminal 3 and extends to the outside of the sensor shell 5. The waterproof terminal 3 can block the gap through which the cable 4 passes through the sensor shell 5, preventing water from entering the sensor shell 5. Figure 3 The waterproof terminal 3 is fixed on the bottom cover 1 and the top cover 2 away from each other, and the cable 4 passes through the waterproof terminal 3 and extends to the outside of the sensor shell 5. The waterproof terminal 3 can block the gap through which the cable 4 passes through the sensor shell 5, preventing water from entering the sensor shell 5.

[0034] The PVC pipe 9 is arranged outside the sensor shell 5, and sealing structures are arranged at both ends of the PVC pipe 9. The sealing structures are used to seal the sensor shell 5.

[0035] The PVC pipe 9 can protect the sensor, and the edge field generated by the two copper ring electrodes 6 can pass through the PVC pipe 9 and enter the matrix.

[0036] The sensor shell 5 further comprises:

[0037] A 100MHz oscillator is arranged inside the sensor shell 5. The 100MHz oscillator is used as a signal source to generate a high-frequency oscillation signal with a frequency of 100MHz. The signal is used to interact with the matrix and generate a corresponding induction signal. The high-frequency signal can better interact with the medium such as water in the matrix, and has high resolution and sensitivity, and is suitable for measuring the dielectric properties of the matrix.

[0038] An impedance matcher is arranged between the 100MHz oscillator and the subsequent circuit. Different circuit elements and the sensor itself have different input and output impedances. If not matched, signal reflection, attenuation and other problems will occur, affecting the measurement accuracy. By adjusting the parameters of the impedance matcher, the signal output by the oscillator can be efficiently transmitted to the sensor, and the signal sensed by the sensor can also be effectively transmitted to the subsequent circuit for processing.

[0039] A band-pass filter is arranged to filter the signal after the impedance matcher. The band-pass filter only allows signals with a specific frequency range of about 100MHz to pass, and suppresses other frequency interference signals. There may be various electromagnetic interferences in the matrix environment, such as power frequency interference and radio wave interference. These interference signals will affect the measurement results. The band-pass filter can effectively filter out these unwanted interference signals, improving the purity and stability of the measurement signal.

[0040] Since the signal sensed by the sensor is usually very weak, amplification is needed for subsequent signal processing and analysis. A micro-signal amplifier is provided to solve this problem. The micro-signal amplifier is used for linear amplification of electrical signals, improving the amplitude of the signals while keeping the waveform and frequency characteristics of the signals unchanged.

[0041] Two high-frequency analog signal detectors are used to detect and process the amplified high-frequency signals. The function of the detector is to extract the low-frequency component or direct current component related to the sensor sensing impedance ZP from the high-frequency modulated signal. By comparing and analyzing the signals output by the two detectors, information about the sensor sensing impedance ZP can be obtained. Different detection and measurement parameters can be achieved by different detection methods and circuit designs, such as amplitude detection and phase detection. The specific measurement requirements can be selected and designed accordingly.

[0042] A signal processing module is used to further process and analyze the signals output by the two high-frequency analog signal detectors, and convert the detected signals related to the sensing impedance ZP into actual measurement values. This module can be implemented using a microcontroller or a digital signal processor, and has functions such as data processing, storage, communication, etc. It can display the measurement results to the user in an intuitive form, or transmit the data to other devices for further analysis and processing through a communication interface.

[0043] For the detection of water in the matrix, we choose the following several matrices:

[0044]

[0045] When making the calibration device, a PVC pipe with an outer diameter of 31.5 cm and a height of 20 cm is selected. A bottom tray is sealed at the bottom, and a PVC sleeve with the same inner diameter as the sensor outer diameter is embedded in the center of the PVC pipe. The sleeve is sealed and connected to the bottom tray with glue. Before starting the matrix water content calibration, the soil water content calibration is performed to test and ensure the availability of the sensor;

[0046] The calibration process first dries the matrix in a drying oven (105℃, 48h). When mixing water with the dry matrix, the water content is increased by 5% of the mass until a certain water content (the bulk density of different matrices varies greatly, and the voltage value that can be measured by the device also has a certain range, so the final water content measured for each matrix is different). Then, the water-mixed matrix is sealed and covered with a film for 48h to allow the internal water to fully and uniformly distribute. The calibration process is carried out at room temperature (25℃). During calibration, each water content matrix is measured three times, and the arithmetic mean is taken.

[0047] Using this device to detect the moisture content of different substrates within a certain range, the errors between the moisture content of different substrates indicated by the sensors and the actual moisture content vary. The calibration curves obtained from the output voltage of the three sensors and the moisture content of coconut coir, vermiculite, peat moss, and mushroom residue, including the mixed substrate, within a certain range all show a one-to-one linear relationship and have good correlation coefficients.

[0048] We recorded the equation of the calibration curve obtained from the calibration and conducted experimental verification. In the subsequent experimental verification process, the root mean square error (RMSE) between the measured mass moisture content and the actual moisture content of the matrix was small. This proves that the device has a good effect in the detection of moisture content in these matrices and has great potential for application in matrix moisture detection.

[0049] In summary, this device shows great potential in substrate applications. It is applicable to a wide range of substrates with minimal error. This experiment fills a gap in the detection of substrate moisture content.

[0050] like Figure 4 As shown, the sealing structure includes two sealing plates 10 disposed inside the PVC pipe body 9. These sealing plates 10 are made of plastic. The cable 4 passes through the sealing plates 10 and extends to the outside of the PVC pipe body 9. A sealing groove 11 is provided on the inner wall of the PVC pipe body 9 at a position corresponding to the sealing plate 10. The sealing plate 10 is inserted into the sealing groove 11, allowing it to seal both ends of the PVC pipe body 9. A rubber ring is provided at the center of the sealing plate 10, through which the cable 4 passes. The tight fit between the rubber ring and the cable 4 prevents moisture from entering from the cable 4. Figure 5 As shown, two second rubber balls 13 are provided on both sides of the sealing sheet 10 and near the edge. A first rubber ball 12 is provided on the inner wall of the sealing groove 11 between the two second rubber balls 13, and the first rubber ball 12 and the second rubber ball 13 abut against each other. With this arrangement, after the sealing sheet 10 is inserted into the sealing groove 11, the two second rubber balls 13 are located on the upper and lower sides of the first rubber ball 12. Thus, through the tight fit of the first rubber ball 12 and the second rubber ball 13, the PVC pipe body 9 and the sealing sheet 10 can be further sealed.

[0051] The above description is merely a preferred embodiment of this utility model. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model. Structures, devices, and operating methods not specifically described or explained in this utility model, unless otherwise specified or limited, shall be implemented using conventional methods in the field.

Claims

1. A dielectric matrix moisture sensor comprising a sensor housing (5), characterized in that: One end of the sensor shell (5) is provided with a bottom cover (1), the outer side of the sensor shell (5) is provided with two copper ring electrodes (6), the outer side of the sensor shell (5) and between the two copper ring electrodes (6) is provided with a nylon ring (7), the other end of the sensor shell (5) is provided with a top cover (2); The inside of the sensor shell (5) is fixedly provided with a cable (4), and the cable (4) penetrates through the top cover (2); The outer side of the sensor shell (5) is provided with a PVC pipe body (9), both ends of the inside of the PVC pipe body (9) are provided with sealing structures, and the sealing structures are used for sealing the sensor shell (5).

2. A dielectric matrix moisture sensor according to claim 1, characterized in that: The inside of the sensor shell (5) is further provided with: A 100MHz oscillator is used to generate a high-frequency oscillation signal with a frequency of 100MHz, which is used to interact with the matrix and generate a corresponding induction signal; An impedance matcher is used to match the impedance between the 100MHz oscillator and the subsequent circuit; A band-pass filter is used to filter the signal after the impedance matcher; A micro-signal amplifier is used to linearly amplify the electrical signal, improve the amplitude of the signal, and keep the waveform and frequency characteristics of the signal unchanged; Two high-frequency analog signal detectors are used to detect the amplified high-frequency signal; A signal processing module is used to further process and analyze the signals output by the two high-frequency analog signal detectors, and convert the detected signals into actual measurement values.

3. A dielectric matrix moisture sensor according to claim 1, wherein: The waterproof terminal (3) is fixed in the direction away from each other of the bottom cover (1) and the top cover (2), and the cable (4) penetrates through the waterproof terminal (3) and extends to the outside of the sensor shell (5).

4. The dielectric matrix moisture sensor of claim 1, wherein: The rubber ring (8) is arranged on the outer side of the sensor shell (5) and on both sides of the two copper ring electrodes (6).

5. The dielectric matrix moisture sensor of claim 1, wherein: The sealing structure includes two sealing sheets (10) arranged in the inside of the PVC pipe body (9), the cable (4) penetrates through the sealing sheets (10) and extends to the outside of the PVC pipe body (9), and the inner wall of the PVC pipe body (9) is provided with a sealing groove (11) at a position corresponding to the sealing sheets (10), and the sealing sheets (10) are clamped into the sealing groove (11).

6. A dielectric matrix moisture sensor according to claim 5, wherein: The two second rubber balls (13) are arranged on both sides of the sealing sheet (10) and close to the edge position, the first rubber ball (12) is arranged on the inner wall of the sealing groove (11) and between the two second rubber balls (13), and the first rubber ball (12) and the second rubber ball (13) abut each other.

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