Non-contact fertilizer liquid sensor based on positive and negative alternating electrode array

Abstract

The utility model relates to a non-contact fertilizer liquid sensor based on a positive and negative alternating electrode array. The non-contact fertilizer liquid sensor based on the positive and negative alternating electrode array comprises a first shielding shell, first external threads are arranged at the two ends of the first shielding shell, and the non-contact fertilizer liquid sensor based on the positive and negative alternating electrode array further comprises an even number of electrode plates annularly arrayed in the first shielding shell, the electrode plate comprises a receiving electrode plate and an exciting electrode plate which are alternately distributed in the first shielding shell; wherein the outer walls of the receiving electrode plate and the exciting electrode plate are connected through a copper foil, and a gap is formed between the receiving electrode plate and the exciting electrode plate. By designing the positive and negative alternating array type electrode plates, non-contact detection of the fertilizer liquid is realized, and the service life of the sensor is effectively prolonged; meanwhile, the fringe electric field can sense the change of a pF-level capacitance value, and the detection precision of the sensor can be improved.

Description

Technical Field

[0001] The present application relates to the field of sensor technology, and in particular to a non-contact fertilizer liquid sensor based on a positive and negative alternating electrode array. Background Art

[0002] The rapid and accurate detection of fertilizer liquid information is a difficult problem that restricts the realization of intelligent water-fertilizer integration, and it is also a hot research topic. Intelligent water-fertilizer integration technology integrates fertilization and irrigation, and supplies fertilizer and water evenly, quantitatively, and regularly according to the growth needs of crops, thereby saving water and fertilizer, improving the yield and quality of agricultural products, and reducing the occurrence of diseases and pests. This technology is of great significance to improving agricultural production efficiency and resource utilization.

[0003] In traditional technologies, EC / pH-based sensors can only reflect the overall concentration of fertilizer solution, but cannot detect the concentration of specific nutrient elements; sensors based on ion selective electrodes have cross-sensitivity problems, resulting in inaccurate detection results; and sensors based on spectroscopy can only detect fertilizer solution containing hydrogen groups, but cannot detect fertilizer solution without hydrogen groups. The above problems lead to a decrease in the detection accuracy of the sensor. Utility Model Content

[0004] In order to solve or partially solve the problems existing in the related art, the present application provides a non-contact fertilizer liquid sensor based on a positive and negative alternating electrode array.

[0005] To achieve the above objectives, this application is implemented through the following technical solutions:

[0006] A non-contact fertilizer liquid sensor based on a positive and negative alternating electrode array comprises a first shielding shell, both ends of which are provided with first external threads, and the non-contact fertilizer liquid sensor based on a positive and negative alternating electrode array further comprises:

[0007] An annular array of electrode plates is arranged inside the first shielding shell, and an even number of electrode plates are provided. The electrode plates include receiving electrode plates and excitation electrode plates, and the two are alternately arranged inside the first shielding shell;

[0008] The outer walls of the receiving electrode plate and the excitation electrode plate are connected by copper foil, and there is a gap between the receiving electrode plate and the excitation electrode plate, and the gap generates an electric field;

[0009] The annularly distributed electrode plates divide the space into two areas, the inner and outer sides of the ring. The outer side of the ring generates an outer edge electric field, and the inner side of the ring generates an inner edge electric field. The electric field generated by the gap and the outer edge electric field are shielded by the first shielding shell.

[0010] Optionally, the receiving electrode plate, the excitation electrode plate and the first shielding shell constitute a single-stage sensor, and three of the single-stage sensors are connected via a first external thread to form a multi-stage sensor.

[0011] Optionally, a second shielding shell is provided on the outer periphery of the multi-segment sensor, and the second shielding shell is connected to the first shielding shell by screws.

[0012] Optionally, the first shielding shell and the second shielding shell are provided with wiring holes, countersunk copper nails are inserted into the wiring holes, one end of the countersunk copper nail contacts the electrode plate, and the other end is connected to the signal conditioning circuit through a radio frequency line.

[0013] Optionally, mounting grooves for mounting the electrode plate are distributed in an annular pattern on the inner wall of the first shielding shell, and the depth of the mounting grooves is 1.5 mm.

[0014] Optionally, there are eight electrode plates in total, four receiving electrode plates and four excitation electrode plates respectively, each of the electrode plates has a length of 61.88 mm, a width of 22.28 mm, a gap of 1.5 mm, a thickness of 0.12 mm, and an angle between adjacent electrode plates of 135.35°.

[0015] Optionally, the outer radius of the first shielding shell is 35 mm, and the inner radius is 30 mm.

[0016] Optionally, two ends of the second shielding shell are provided with second external threads, the outer radius of the second external threads is 41 mm, and the inner radius is 32.5 mm.

[0017] Beneficial effects of the present application: The present application realizes non-contact detection of fertilizer liquid by designing an array electrode plate with alternating positive and negative electrodes, which effectively prolongs the service life of the sensor; at the same time, the edge electric field can sense the change of capacitance value at the pF level, which can improve the detection accuracy of the sensor. Both ends of the sensor are provided with threads, which can be easily embedded in the intelligent irrigation and fertilization pipeline to detect the component information of the fertilizer liquid. One section of the sensor is responsible for the detection of a specific type and concentration of fertilizer. By connecting three sections of sensors in series, the detection of the type and concentration of single-element fertilizer liquid and mixed fertilizer liquid can be realized, which improves the working efficiency of the detection of fertilizer liquid component information. Finally, in order to eliminate the influence of bubbles in the pipeline, the present application defines the bubble-containing interval as the basis for whether the sensor is detecting normally, and establishes a corresponding mathematical model to determine the component information of the fertilizer liquid through the change trend of the frequency curve gain ratio voltage-frequency curve, which effectively guarantees the detection accuracy of the sensor and realizes the online rapid detection of multiple types of fertilizer liquid component information.

[0018] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the present application will become more apparent through a more detailed description of exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present application.

[0020] Figure 1 This is a schematic diagram of the structure of a single-stage sensor tilted at 45° shown in an embodiment of the present application;

[0021] Figure 2 This is a schematic diagram of the structure of a single-stage sensor at 90° according to an embodiment of the present application;

[0022] Figure 3 is a schematic structural diagram of the electrode plate array distribution shown in an embodiment of the present application;

[0023] Figure 4 is a schematic diagram of the structure of a multi-stage sensor shown in an embodiment of the present application;

[0024] Figure 5 is a sensor signal conditioning circuit diagram shown in an embodiment of the present application;

[0025] Figure 6 It is a fertilizer liquid detection flow chart shown in an embodiment of the present application.

[0026] Figure numerals: 1 receiving electrode plate, 2 exciting electrode plate, 3 first shielding shell, 4 first external thread, 5 second shielding shell, 6 screw, 7 wiring hole, 8 second external thread. DETAILED DESCRIPTION

[0027] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0028] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific situation.

[0030] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0031] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples" or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0032] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

[0033] The above description is only an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0034] In order to make the purpose, technical solutions and beneficial effects of the present application clearer, the preferred embodiments of the present application will be described in detail below in conjunction with the accompanying drawings to facilitate understanding by technical personnel.

[0035] Embodiment 1:

[0036] See also Figures 1 to 3 A non-contact fertilizer liquid sensor based on a positive and negative alternating electrode array comprises a first shielding shell 3, both ends of which are provided with first external threads 4, and the non-contact fertilizer liquid sensor based on a positive and negative alternating electrode array further comprises:

[0037] An annular array of electrode plates inside the first shielding shell 3, an even number of electrode plates are provided, and the electrode plates include receiving electrode plates 1 and excitation electrode plates 2, which are alternately distributed inside the first shielding shell 3;

[0038] The outer walls of the receiving electrode plate 1 and the excitation electrode plate 2 are connected by copper foil, and there is a gap between the receiving electrode plate 1 and the excitation electrode plate 2, and the gap generates an electric field;

[0039] The annularly distributed electrode plates divide the space into two areas, the inner and outer sides of the ring. The outer side of the ring generates an outer edge electric field, and the inner side of the ring generates an inner edge electric field. The electric field generated by the gap and the outer edge electric field are shielded by the first shielding shell 3.

[0040] Specifically, in order to improve the conductivity and corrosion resistance of the electrode plate, the electrode plate is made of copper. The actual thickness of the copper plate is 0.04 mm, which greatly weakens the facing electric field at the gap between two adjacent electrode plates.

[0041] Combination Figure 3 It can be seen that the annularly distributed electrode plates divide the space into two areas, the inner and outer sides of the ring. In this design, the fringe field generated on the inner side of the ring - the inner fringe field - is used as the detection area, while the fringe electric field generated outside the ring - the outer fringe field - needs to be shielded to shield the influence of other external media. The electrode plate surface on the inner side of the ring is waterproof, moisture-proof and insulated with a three-proof protective agent to enhance the corrosion resistance of the electrode plate, thereby increasing the service life of the electrode plate. The thickness of the insulating film is at the micron level, and the fringe electric field lines can easily penetrate and shoot toward the receiving electrode plate to form a detection electric field.

[0042] Since the outer edge electric field and the electric field at the gap between the electrode plates are shielded, they will not affect the inner edge electric field, nor will they be affected by the external environment. When the characteristic frequency excitation signal is applied to both ends of the sensor, the inner edge electric field can stably penetrate the inner lining pipe to reach the area where the fertilizer liquid flows through to form a detection area. When the fertilizer liquid component information flowing through the detection area changes, it is equivalent to the change of the medium in the capacitor. When the medium changes, the dielectric constant will also change, resulting in a change in the capacitance value of the sensor. The change in the capacitance value of the sensor will cause the amplitude-frequency characteristics and phase-frequency characteristics of the characteristic frequency excitation signal acting on the sensor to change significantly compared to the initial state. The curves of the gain ratio voltage and phase difference voltage of the fertilizer liquid to be tested of different concentrations and types are different. The frequency corresponding to the local peak value of the gain ratio voltage and the local peak value of the phase difference voltage of the fertilizer liquid to be tested is used as the characteristic frequency of the fertilizer liquid component information detection, thereby constructing a fertilizer liquid type and concentration identification model.

[0043] In this embodiment, the receiving electrode plate 1 and the excitation electrode plate 2 are respectively positive and negative electrodes. The present application realizes non-contact detection of fertilizer liquid by designing an array electrode plate with alternating positive and negative electrodes, thereby effectively extending the service life of the sensor. At the same time, the fringe electric field can sense the capacitance value changes at the pF level, thereby improving the detection accuracy of the sensor.

[0044] Embodiment 2:

[0045] See also Figure 4 Based on the first embodiment, further and optionally, the receiving electrode plate 1, the excitation electrode plate 2 and the first shielding shell 3 constitute a single-stage sensor, and the three single-stage sensors are connected by the first external thread 4 to form a multi-stage sensor.

[0046] Specifically, the multi-stage sensor is designed as a three-stage sensor. The working state combination of the electrode plates in each stage is the same, and each stage is responsible for detecting the information of a fertilizer liquid component. Each stage of the sensor is connected by a thread. In actual application, the detection stage can be increased according to the increase in the number of fertilizer liquid types to be detected.

[0047] Further and optionally, a second shielding shell 5 is provided on the outer periphery of the multi-segment sensor, and the second shielding shell 5 is connected to the first shielding shell 3 by screws 6 .

[0048] Specifically, the first shielding shell 3 and the second shielding shell 5 are screwed together through the shell combining holes, aiming to shield the influence of the external environment on the inner edge electric field to improve the detection accuracy.

[0049] Embodiment three:

[0050] See also Figure 4 and Figure 5Based on the above embodiment, further and optionally, a wiring hole 7 is opened on the first shielding shell 3 and the second shielding shell 5, and a countersunk copper nail is inserted into the wiring hole 7, one end of the countersunk copper nail contacts the electrode plate, and the other end is connected to the signal conditioning circuit through the radio frequency line.

[0051] Specifically, since a sinusoidal excitation signal needs to be applied to the sensor, an RF line is selected to connect to the electrode plate, which also improves the sensor's anti-interference ability. The RF line is connected to the signal conditioning circuit. The capacitance value of the fringe electric field sensor is often in the pF level, resulting in a relatively small signal strength. When using the fringe electric field constructed by the array electrode plate for detection, a signal conditioning circuit is required to amplify the signal to prevent the effective signal from being submerged in the noise. The signal conditioning circuit design is as follows:

[0052] The sensor signal conditioning circuit is mainly composed of the sensor signal acquisition channel and the amplitude and phase detection module AD8302.

[0053] The sensor signal acquisition channel includes: the sensor signal starts from the "sinusoidal excitation signal" and enters the sensor module (Lx, Cx, Rx) through R1 and R2. After the signal is conditioned, it is input to the INPA and INPB pins of AD8302 for processing. AD8302 performs amplitude and phase detection on the input signal and outputs it to OFSA and OFSB.

[0054] The specific working process of the sensor signal acquisition channel: the excitation signal generator generates a characteristic frequency excitation signal that acts on both ends of the sensor CX to generate a response signal. R1 and R2 divide the voltage to adjust the signal amplitude entering the sensor module; the sensor module (Lx, Cx, Rx) responds to and conditions the signal. The signal is filtered by C3, C4, C5, and C6 to remove noise and high-frequency interference. The conditioned signal is input to the INPA and INPB pins of AD8302 for phase and amplitude detection. AD8302 outputs the measured amplitude and phase difference through OFSA and OFSB for subsequent processing and analysis.

[0055] The AD8302 amplitude phase detection module is a fully integrated RF IC that can be used to measure the amplitude difference and phase difference between two input signals and convert them into a gain ratio voltage (VMAG) and a phase difference voltage (VPHS). The greater the amplitude difference between the two signals, the greater the gain ratio voltage; when the phase difference between the two signals is in the range of -180° to 0°, the phase difference voltage increases as the phase difference increases, and vice versa in the range of 0° to 180°. The operating frequency range of the AD8302 is from low frequency to 2.7GHz, and it is powered by a 5V power supply. A sinusoidal excitation signal is applied to the RC conditioning circuit. The INPB terminal of the AD8302 is used to collect the sinusoidal excitation signal, and the INPA terminal is used to collect the output signal of the sensor. By comparing the phase difference and amplitude difference between the two, it is converted into a phase difference voltage (VPHS) and a gain ratio voltage (VMAG), and output to the data acquisition module through the VPHS terminal and the VMAG terminal. In addition, the AD8302 amplitude and phase detection module has two precisely matched logarithmic detectors, which can reduce the error source to a minimum and ensure the stability of the sensor.

[0056] Embodiment 4:

[0057] See also Figures 1 to 4 Based on the above embodiment, further and optionally, the inner wall of the first shielding shell 3 is annularly distributed with mounting grooves for mounting the electrode plate, and the depth of the mounting grooves is 1.5 mm.

[0058] Further and optionally, there are eight electrode plates in total, four receiving electrode plates 1 and four excitation electrode plates 2 respectively, each of the electrode plates has a length of 61.88 mm, a width of 22.28 mm, a gap of 1.5 mm, a thickness of 0.12 mm, and an angle between adjacent electrode plates of 135.35°.

[0059] Further and optionally, the outer radius of the first shielding shell 3 is 35 mm, and the inner radius is 30 mm.

[0060] Further and optionally, both ends of the second shielding shell 5 are provided with second external threads 8 , and the outer radius of the second external threads 8 is 41 mm and the inner radius is 32.5 mm.

[0061] Specifically, according to the condition of the fringe electric field, the angle between the excitation electrode and the receiving electrode is 180 °. In order to make the angle between the annularly distributed plates meet this condition, under the restriction that the outer diameter of the sensor is 63 mm, the smaller the width of the plate, the more the angle between the two plates can meet this condition. However, the smaller the width of the plate, the smaller the area of ​​the plate. When the plate spacing, length and thickness are fixed, its capacitance value will decrease, which is not conducive to the detection of subsequent output signals. In the typical concept of ECT (Electrical Capacitance Tomography, capacitance tomography) sensor, there are mostly circular capacitors with 6, 8, 12 and 16 plates. The number of plates of the designed fringe electric field capacitive fertilizer liquid component information sensor is selected as 8, and the plate array is annularly distributed on its inner wall, and a fringe electric field is formed between the plates.

[0062] Considering the outer diameter of the sensor and the spacing between the plates, the length of a single plate is designed to be 61.88mm, the width is 22.28mm, the plate gap is 1.5mm, and the thickness is 0.12mm. Since the sensor is cylindrical in shape, the electrode plates are distributed on the tube wall in a circular array. It is impossible for two adjacent electrode plates to be fully unfolded on the same plane. The angle between them is 135.35°. The schematic diagram of the array distribution structure of 8 electrode plates is shown in the figure. Figure 3 shown.

[0063] The outer radius of the first shielding shell 3 is 35mm, and the inner radius is 30mm. There is a circle of annular plate mounting grooves on the inner wall of the first shielding shell 3, and the groove wall thickness is 1.5mm. The outer radius of the second external thread 8 is 41mm, and the inner radius is 32.5mm. It allows a pipe with an outer diameter of 63mm to be inserted therein, and it is tightly connected through a flexible joint, so that the sensor can be embedded in the fertilizer pipeline, thereby realizing the detection of fertilizer liquid component information, and at the same time, it will not affect the flow of fertilizer liquid, and improve the working efficiency of fertilizer liquid component information detection. Since the sensor is part of the irrigation and fertilization pipeline, it needs to withstand a certain water flow pressure. In the initial stage of production, the sensor printed and formed using PLA material has water seepage on the outer wall during the experiment. Therefore, the sensor made of this material cannot meet the actual working conditions. In response to this problem, the subsequent sensor production is all printed and formed using resin materials. No water seepage occurred in the experiment, and the material strength of the sensor is relatively large and can withstand a large water flow pressure. Each plate of the sensor is tightly attached to the plate mounting groove using high-strength structural adhesive to fix the plate and seal it. The countersunk copper nail is inserted into the wiring hole 7 to contact the electrode plate, and the four excitation electrode plates and the four receiving electrode plates are connected in parallel on the outer wall using copper foil.

[0064] Embodiment five:

[0065] See also Figure 6 Based on the above embodiment, further, when the fertilizer liquid flows through the pipeline, bubbles are inevitably generated and attached to the inner wall of the pipeline. When the properties of the lining pipeline remain unchanged, due to the large difference between the dielectric constant of the fertilizer liquid and the dielectric constant of air, the electric field lines are significantly offset at the bubbles, which has a great impact on the strength of the capacitance signal.

[0066] The utility model provides a solution that can effectively reduce the influence of bubbles in the tube on the detection accuracy of the sensor. Firstly, in terms of structure, the sensor is nested in the downstream arch section of the arch pipe. When the fertilizer liquid flows through the arch pipe, the air in the pipe and the small bubbles in the fertilizer liquid are discharged from the exhaust valve under the action of pressure. Secondly, in terms of detection method, the output signal range of the sensor is obtained when a certain amount of bubbles are contained in the fertilizer liquid through a large number of experimental methods, and converted into a specific voltage value interval through a signal conditioning circuit, and this interval is called the bubble-containing interval. When the sensor starts working, it is first determined whether the voltage value after conversion by the signal conditioning circuit falls within the bubble-containing interval. If it falls within the interval, it indicates that the fertilizer liquid contains a certain amount of bubbles, then the sensor stops detecting, enters a waiting state, and detects again after an interval of 10s; if the output electrical signal does not fall within the bubble-containing interval, it indicates that the bubbles in the pipeline have been discharged. The sensor then starts to detect the fertilizer liquid component information.

[0067] Take the detection of urea in a certain section of the sensor as an example to illustrate the detection strategy: Based on a large number of previous experiments, a characteristic frequency excitation signal library for detecting urea was created (this signal library has no intersection with the characteristic frequency excitation signal library for detecting phosphate fertilizer and potash fertilizer). The excitation signal source can generate these characteristic frequency excitation signals in turn at intervals in a working cycle (about 10s). The characteristic frequency excitation signal acts on both ends of the sensor. The characteristic frequency excitation signal after acting on the sensor is collected through the sensor signal acquisition channel. The amplitude difference and phase difference between the two are detected by the AD8302 module. The relationship between the gain ratio voltage, phase difference voltage output by the sensor under the action of the frequency excitation signal and the concentration and type of the fertilizer solution to be tested is analyzed. A large number of urea with different concentrations are prepared for testing. After a working cycle of data collection, a curve of the gain ratio voltage, phase difference voltage and characteristic frequency excitation signal frequency can be established. Similarly, the gain ratio voltage-frequency curve and phase difference voltage-frequency curve of phosphate fertilizer and potash fertilizer under the action of their respective characteristic frequency excitation signal libraries can also be obtained. The concentration of the fertilizer solution is determined by establishing a corresponding mathematical model through the amplitude (voltage value) of the starting point of the gain ratio voltage-frequency curve and the changing trend of the curve. The type of fertilizer solution is determined by establishing a corresponding decision model through the changing trend of the phase difference voltage-frequency curve. The detection process of phosphate fertilizer and potash fertilizer is the same as above. Figure 6 shown.

[0068] For the detection of mixed fertilizer liquid, a certain section is taken to detect the information of a certain type of nutrient element, so as to realize the detection of the nutrient element information in the mixed fertilizer liquid.

[0069] In summary, the present application realizes non-contact detection of fertilizer liquid by designing an array electrode plate with alternating positive and negative electrodes, which effectively prolongs the service life of the sensor; at the same time, the edge electric field can sense the change of capacitance value at the pF level, which can improve the detection accuracy of the sensor. Both ends of the sensor are provided with threads, which can be easily embedded in the intelligent irrigation and fertilization pipeline to detect the component information of the fertilizer liquid. One section of the sensor is responsible for the detection of a specific type and concentration of fertilizer. By connecting three sections of sensors in series, the detection of the type and concentration of single-element fertilizer liquid and mixed fertilizer liquid can be realized, which improves the working efficiency of the detection of fertilizer liquid component information. Finally, in order to eliminate the influence of bubbles in the pipeline, the present application defines the bubble-containing interval as the basis for whether the sensor is detecting normally, and establishes a corresponding mathematical model to determine the component information of the fertilizer liquid through the change trend of the frequency curve gain ratio voltage-frequency curve, which effectively guarantees the detection accuracy of the sensor and realizes the online rapid detection of various types of fertilizer liquid component information.

[0070] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solution of the present application rather than to limit it. Although the present application has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present application; the dimensions of the drawings are not related to the specific objects, and the dimensions of the objects can be changed arbitrarily.

Claims

1. A non-contact fertilizer liquid sensor based on a positive and negative alternating electrode array, comprising a first shielding shell (3) with first external threads (4) at both ends, characterized in that: The non-contact fertilizer liquid sensor based on the positive and negative alternating electrode array also includes: An annular array of electrode plates is arranged inside the first shielding shell (3), the electrode plates being provided in an even number, the electrode plates comprising receiving electrode plates (1) and excitation electrode plates (2), the two being alternately arranged inside the first shielding shell (3); The outer walls of the receiving electrode plate (1) and the excitation electrode plate (2) are connected by copper foil, and there is a gap between the receiving electrode plate (1) and the excitation electrode plate (2), and the gap generates an electric field; The annularly distributed electrode plates divide the space into two areas, the inner side and the outer side of the ring. The outer side of the ring generates an outer edge electric field, and the inner side of the ring generates an inner edge electric field. The electric field generated by the gap and the outer edge electric field are shielded by a first shielding shell (3).

2. The non-contact fertilizer liquid sensor based on the positive and negative alternating electrode array as claimed in claim 1, characterized in that: The receiving electrode plate (1), the excitation electrode plate (2) and the first shielding shell (3) together form a single-stage sensor, and three of the single-stage sensors are connected via a first external thread (4) to form a multi-stage sensor.

3. The non-contact fertilizer liquid sensor based on the positive and negative alternating electrode array as claimed in claim 2, characterized in that: A second shielding shell (5) is sleeved on the outer periphery of the multi-stage sensor, and the second shielding shell (5) is connected to the first shielding shell (3) via screws (6).

4. The non-contact fertilizer liquid sensor based on the positive and negative alternating electrode array as claimed in claim 1, characterized in that: The first shielding shell (3) and the second shielding shell (5) are provided with wiring holes (7), countersunk copper nails are inserted into the wiring holes (7), one end of the countersunk copper nails contacts the electrode plate, and the other end is connected to the signal conditioning circuit via a radio frequency line.

5. The non-contact fertilizer liquid sensor based on the positive and negative alternating electrode array according to claim 1 or 4, characterized in that: The inner wall of the first shielding shell (3) is provided with mounting grooves for mounting the electrode plate in an annular shape, and the depth of the mounting grooves is 1.5 mm.

6. The non-contact fertilizer liquid sensor based on the positive and negative alternating electrode array as claimed in claim 1, characterized in that: There are eight electrode plates in total, four receiving electrode plates (1) and four excitation electrode plates (2), each of which has a length of 61.88 mm, a width of 22.28 mm, a gap of 1.5 mm, a thickness of 0.12 mm, and an angle between adjacent electrode plates of 135.35°.

7. The non-contact fertilizer liquid sensor based on the positive and negative alternating electrode array as claimed in claim 1, characterized in that: The outer radius of the first shielding shell (3) is 35 mm, and the inner radius is 30 mm.

8. The non-contact fertilizer liquid sensor based on the positive and negative alternating electrode array as claimed in claim 3, characterized in that: The second shielding shell (5) is provided with second external threads (8) at both ends, and the outer radius of the second external threads (8) is 41 mm and the inner radius is 32.5 mm.

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