A soil moisture sensor field rapid calibration device

Abstract

The utility model relates to soil moisture detection equipment calibration technical field discloses a kind of soil moisture sensor field fast calibration device, including shell, upper positioning support disc, lower positioning support disc, loading mechanism mounting disc, annular cam driving disc and multiple dielectric loading petals.The utility model dielectric loading petal is made of polytetrafluoroethylene, is set along circumference and is matched with driven bearing and radial direction guide groove group and arc drive groove by limiting post, synchronously moves along radial direction when annular cam driving disc rotates, forms the dielectric loading cavity of multiple petal formula with sensor positioning axisline coaxial and variable inner diameter, for obtaining repeatable dielectric loading state.

Description

Technical Field

[0001] This utility model relates to the field of soil moisture detection equipment calibration technology, specifically to a rapid on-site calibration device for soil moisture sensors. Background Technology

[0002] Soil moisture sensors are widely used in farmland soil moisture monitoring, water-saving irrigation, hydrological observation, and soil environmental monitoring. Dielectric soil moisture sensors typically calculate soil moisture content by utilizing changes in capacitance, frequency, voltage, or other electrical signals caused by changes in the equivalent dielectric environment around the sensing electrodes. Factors such as individual sensor differences, installation conditions, ambient temperature, drift due to long-term use, and contamination of sensitive areas can all cause the sensor output to deviate from its original calibration. Therefore, calibration or consistency verification is necessary during commissioning, maintenance, or on-site verification.

[0003] Current methods for calibrating soil moisture sensors largely rely on soil samples with varying moisture contents, weighing and drying processes, standard liquids, constant temperature and humidity environments, or laboratory equipment. Using soil samples requires sampling, water preparation, mixing, settling, weighing, or drying, and the texture, density, and uniformity of different batches of soil samples are difficult to reproduce quickly in the field. Using standard liquids or environmental generating equipment requires appropriate containers, temperature and humidity control, and a relatively long stabilization time. While these methods can be implemented in a laboratory environment, their application in the field or at monitoring stations typically involves numerous preparation steps, large equipment size, slow standard state switching speeds, and inconsistent clamping positions.

[0004] For dielectric soil moisture sensors, the sensitive electric field is affected not only by the dielectric parameters of the medium itself but also by the spatial position of the medium relative to the sensing electrode. Therefore, if a geometrically defined and repeatedly switchable dielectric boundary condition can be formed around the sensor's sensitive area using an insulating medium with stable and known dielectric parameters, a set of reproducible reference responses can be obtained for on-site determination of whether the sensor output has deviated. To ensure comparability between different loading states, it is also necessary to keep the mounting axis of the sensor to be calibrated, the center of the standard dielectric loading component, and the radial displacement of each loading component consistent.

[0005] Therefore, a compact field calibration device is needed to enable the sensor to be calibrated to be repeatedly positioned on the same axis, and to enable multiple standard dielectric loading components to synchronously and equidistantly change their radial positions around the sensor's sensitive area, thereby forming multiple repeatable standard dielectric loading states without the need for repeated soil sample preparation. Utility Model Content

[0006] To overcome the above shortcomings, this utility model provides a rapid on-site calibration device for soil moisture sensors, which solves the problems of cumbersome preparation of standard media, inconvenient switching of loading states, difficulty in synchronizing multiple loading components, and insufficient consistency of repeated sensor clamping positions during on-site calibration.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a rapid on-site calibration device for a soil moisture sensor, comprising a housing, wherein an upper positioning support plate and a lower positioning support plate are spaced apart along the same calibration axis inside the housing, and the upper and lower positioning support plates are respectively provided with positioning holes coaxial with the calibration axis; an annular cam drive plate and a loading mechanism mounting plate are provided below the lower positioning support plate, the loading mechanism mounting plate is coaxial with the positioning holes, and multiple radial guide groove groups are provided circumferentially, each radial guide groove group including two limiting guide grooves arranged in parallel along the circumferential direction and extending radially, and a bearing guide groove, wherein the bearing guide groove is located between the two limiting guide grooves.

[0008] Each radial guide groove group is provided with a dielectric loading petal. Multiple dielectric loading petals are arranged around the calibration axis. Each dielectric loading petal forms a loading surface on the side facing the calibration axis. Multiple loading surfaces enclose a multi-lobed dielectric loading cavity coaxial with the positioning hole. The lower part of each dielectric loading petal is provided with two limiting posts and a driven bearing. The two limiting posts extend into the two limiting guide grooves of the corresponding radial guide groove group and slide with them. The driven bearing passes through the bearing guide groove located in the middle of the corresponding radial guide groove group and rolls with the corresponding arc-shaped drive groove on the annular cam drive disk. The dielectric loading petal is made of polytetrafluoroethylene.

[0009] Furthermore, the multiple dielectric loading lobes have the same structure, and the dielectric loading lobes are plate-shaped or petal-shaped structures extending along the calibration axis. The radial distance between each loading surface and the calibration axis is equal at the same driving position.

[0010] Furthermore, there are six dielectric loading lobes, six radial guide slot groups, and six arc-shaped drive slots. The six radial guide slot groups are arranged in a rotationally symmetrical manner with the calibration axis as the center. Each radial guide slot group includes two limiting guide slots and a bearing guide slot located between them. The six arc-shaped drive slots correspond one-to-one with the bearing guide slots in the six radial guide slot groups.

[0011] Furthermore, a drive base is provided inside the housing. The drive base includes a servo motor, a worm gear, a worm wheel, a bearing plate, and a bearing bearing. The servo motor, worm gear, worm wheel, and annular cam drive plate are sequentially connected for transmission. The annular cam drive plate is rotatably mounted on the bearing plate through the bearing bearing. The loading mechanism mounting plate is fixedly mounted above the bearing plate.

[0012] Furthermore, a reference detection component is fixedly installed on the loading mechanism mounting plate, and the reference detection component is relatively fixed to the loading mechanism mounting plate.

[0013] Furthermore, a temperature sensor is installed on the surface of the lower positioning support plate.

[0014] Furthermore, the housing is provided with a display operation window and a drive adjustment knob, and the housing is provided with a power supply and a package chip. The package chip is electrically connected to the display operation window, the drive adjustment knob and the servo motor respectively.

[0015] Furthermore, a top cover assembly is provided on the top of the housing, one side of which is hinged to the housing, and the other side of which is fitted with a locking structure; a power dust plug is provided at the bottom of the housing, and a housing fixing connector is provided on the rear outer wall of the housing.

[0016] Furthermore, a carrying support assembly is provided on the outside of the shell. The carrying support assembly includes a carrying strap, a support connector, a foam board, and a reinforcing support plate. The support connector is detachably snapped into the shell fixing connector. The foam board and the reinforcing support plate are stacked along the thickness direction of the carrying support assembly, with the foam board located between the carrying strap and the reinforcing support plate.

[0017] Furthermore, the worm and worm wheel mesh with each other to form a worm gear reduction transmission pair.

[0018] This utility model has the following beneficial effects: 1. This utility model uses the coaxial positioning of the upper positioning support plate and the lower positioning support plate to enable the sensor to be calibrated to be repeatedly installed along a unified calibration axis; multiple dielectric loading lobes with the same structure form a multi-lobed dielectric loading cavity around the calibration axis, so that the sensor positioning center is consistent with the dielectric loading center, reducing the impact of repeated clamping eccentricity on the reference response.

[0019] 2. This utility model uses the cooperation of an annular cam drive disk, radial guide groove group, limiting post and driven bearing to enable multiple dielectric loading petals to change their radial positions synchronously by the same drive mechanism; the two limiting guide grooves in each radial guide groove group are respectively slidably engaged with the two limiting posts, and the central bearing guide groove is engaged with the driven bearing to limit the radial movement direction of the dielectric loading petal; the dielectric loading petal made of polytetrafluoroethylene forms a multi-lobed dielectric loading cavity with different inner diameters at different radial positions, thereby forming multiple repeatable dielectric loading states. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of the overall structure of the present invention from another perspective; Figure 3This is a schematic diagram of the back structure of the housing of this utility model; Figure 4 This is a schematic diagram of the internal structure of the housing of this utility model; Figure 5 This is a schematic diagram of the drive base and reference detection component of this utility model; Figure 6 This is an exploded view of the drive base of this utility model; Figure 7 This is a schematic diagram of the dielectric loading lobe structure of this utility model; Figure 8 This is a schematic diagram of the upper positioning support plate and the lower positioning support plate of this utility model; Figure 9 This is a schematic diagram of the supporting component structure of this utility model; Figure 10 This is an exploded structural diagram of the carrying support component of this utility model.

[0021] Legend: 1. Housing; 101. Display and operation window; 102. Drive adjustment knob; 103. Power dust plug; 104. Housing fixing connector; 105. Top cover assembly; 2. Carrying support assembly; 201. Carrying strap; 202. Support connector; 203. Foam board; 204. Reinforcing support plate; 3. Upper positioning support plate; 301. Lower positioning support plate; 302. Temperature sensor; 4. Drive base; 401. Power supply; 402. Packaged chip; 403. Servo motor; 404. Worm gear; 405. Bearing plate; 406. Bearing bearing; 407. Worm wheel; 408. Annular cam drive plate; 409. Loading mechanism mounting plate; 410. Reference detection assembly; 411. Radial guide groove group; 412. Dielectric loading flap; 413. Limiting post; 414. Driven bearing. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] like Figures 1 to 4As shown, the main body of this device is a housing 1. A top cover assembly 105 is provided on the top of the housing 1. One side of the top cover assembly 105 is hinged to the housing 1, and the other side is connected to the housing 1 via a locking structure. A display operation window 101 and a drive adjustment knob 102 are provided on the front side of the housing 1, and a power dust plug 103 is provided on the lower part of the housing 1. A housing fixing connector 104 is provided on the rear outer wall of the housing 1, which is used to detachably engage with the support connector 202 on the carrying support assembly 2. After the top cover assembly 105 is opened, the installation position of the sensor to be calibrated and its internal mechanisms can be operated.

[0024] like Figure 4 and Figure 8 As shown, an upper positioning support plate 3 and a lower positioning support plate 301 are spaced apart along the same calibration axis inside the housing 1. In this embodiment, a positioning hole coaxial with the calibration axis is formed in the middle of both positioning support plates. The soil moisture sensor to be calibrated passes through the calibration axis and its radial position is defined by the two positioning holes. A positioning space is formed between the two positioning support plates for the sensor to be calibrated to pass through. The outline and size of the positioning hole can be adapted according to the cross-section of the housing of the sensor to be calibrated. A temperature sensor 302 is installed on the surface of the lower positioning support plate 301 to collect temperature information during the calibration process inside the device.

[0025] like Figures 4 to 6 As shown, a drive base 4 is disposed below the lower positioning support plate 301. The drive base 4 includes a power supply 401, a packaged chip 402, a servo motor 403, a worm gear 404, a support plate 405, a support bearing 406, a worm wheel 407, an annular cam drive plate 408, and a loading mechanism mounting plate 409. The power supply 401 is disposed on the drive base 4 and supplies power to the internal electrical components of the device; the packaged chip 402 is electrically connected to the display operation window 101, the drive adjustment knob 102, and the servo motor 403.

[0026] The output end of the servo motor 403 is connected to the worm gear 404, which meshes with the worm wheel 407. The worm wheel 407 is connected to the annular cam drive disk 408. The annular cam drive disk 408 is supported on the support disk 405 by the support bearing 406 and can rotate relative to the support disk 405 around the calibration axis. The loading mechanism mounting disk 409 is fixedly disposed above the support disk 405, so that the loading mechanism mounting disk 409 remains circumferentially fixed when the annular cam drive disk 408 rotates. The worm gear 404 and the worm wheel 407 are coupled by a reduction gear transmission to reduce the speed of the annular cam drive disk 408 and maintain driving stability.

[0027] like Figures 5 to 7As shown, six radial guide groove groups 411 are arranged circumferentially on the loading mechanism mounting plate 409, and each radial guide groove group 411 corresponds to a dielectric loading petal 412. Each radial guide groove group 411 includes three parallel guide grooves that extend radially. The three guide grooves are arranged in parallel along the circumferential direction, with the two guide grooves on both sides being limit guide grooves and the guide groove in the middle being a bearing guide groove. A reference detection component 410 is also fixedly mounted on the loading mechanism mounting plate 409, and the reference detection component 410 is relatively fixed to the loading mechanism mounting plate 409.

[0028] The lower part of the dielectric loading lobe 412 is provided with two limiting posts 413 and a driven bearing 414. The two limiting posts 413 correspond to two limiting guide grooves in the corresponding radial guide groove group 411, and extend into the two limiting guide grooves for sliding engagement. The driven bearing 414 is located between the two limiting posts 413, passes through the bearing guide groove in the middle of the corresponding radial guide groove group 411, and enters the corresponding arc-shaped drive groove on the annular cam drive disk 408 for rolling engagement. Each arc-shaped drive groove extends circumferentially and has a radial component relative to the calibration axis. Multiple arc-shaped drive grooves adopt the same radial displacement law, so that when the annular cam drive disk 408 rotates through the same angle, each driven bearing 414 obtains the same radial displacement.

[0029] Each dielectric loading lobe 412 forms a loading surface facing the calibration axis, and multiple loading surfaces together form a multi-lobed dielectric loading cavity coaxial with the two positioning holes around the calibration axis. After the soil moisture sensor to be calibrated is installed along the calibration axis, its sensitive part is located in the multi-lobed dielectric loading cavity. Each dielectric loading lobe 412 maintains the same radial distance from the calibration axis in the same driving position, so the multi-lobed dielectric loading cavity remains coaxial with the two positioning holes during the diameter reduction or expansion process.

[0030] The dielectric loading lobe 412 is made of polytetrafluoroethylene (PTFE). The dielectric parameters of PTFE can be measured and recorded within the target operating frequency band of the sensor to be calibrated during the factory calibration of the device. The thickness, axial height, and minimum radial distance between the dielectric loading lobe 412 and the sensor to be calibrated can be determined according to the structural dimensions and detection range of the sensor to be calibrated.

[0031] When the annular cam drive disk 408 rotates, the arc-shaped drive groove pushes the corresponding driven bearing 414, which moves radially along the bearing guide groove in the corresponding radial guide groove group 411. Simultaneously, two limiting posts 413 slide along the limiting guide grooves on both sides of the radial guide groove group 411. Under the combined constraint of the two limiting posts 413, the two limiting guide grooves, the driven bearing 414, and the bearing guide groove, the dielectric loading petals 412 move radially, causing the six dielectric loading petals 412 to synchronously and equidistantly approach or move away from the calibration axis. Each dielectric loading petal 412 has the same structure and material, and at the same drive position, its radial distance from the calibration axis is equal, thus forming a multi-petal dielectric loading cavity with different inner diameters that can be repeated. The reference detection component 410 is fixed to the loading mechanism mounting disk 409 and remains in a constant position during the radial movement of the dielectric loading petals 412. The two limiting posts 413 move along the two limiting guide grooves in the radial guide groove group 411 with the dielectric loading petal 412, and are constrained by the groove wall of the corresponding limiting guide groove.

[0032] In this embodiment, the packaged chip 402 can control the servo motor 403 to continuously adjust the angular position of the annular cam drive disk 408 within the allowable rotation stroke, and can stop at several sampling positions as required for calibration; different angular positions of the annular cam drive disk 408 correspond to different radial positions of the dielectric loading petals 412. Since the six dielectric loading petals 412 are driven by the same annular cam drive disk 408, each loading petal does not need to be adjusted separately.

[0033] During the factory or laboratory calibration phase, the device can use a metrologically verified reference sensor or a sensor of the same model calibrated by standard laboratory methods to record the sensor reference output and corresponding temperature at multiple selected dielectric loading positions, establishing the correspondence between loading position, reference output, and temperature. The dielectric loading state is jointly determined by the dielectric parameters and geometric dimensions of the polytetrafluoroethylene dielectric loading lobe 412 and the inner diameter of the multi-lobe dielectric loading cavity.

[0034] In field use, open the top cover assembly 105, insert the soil moisture sensor to be calibrated into the positioning holes of the upper positioning support plate 3 and the lower positioning support plate 301, positioning the sensor along the calibration axis, and then close the top cover assembly 105. Input the adjustment command through the drive adjustment knob 102, and the packaged chip 402 controls the servo motor 403 to rotate. The servo motor 403 drives the annular cam drive plate 408 to rotate via the worm gear 404 and worm wheel 407, synchronously moving each dielectric loading petal 412 to the selected radial position. After the position stabilizes, read the output of the sensor to be calibrated and record the temperature information collected by the temperature sensor 302. Subsequently, change the radial position of the dielectric loading petal 412 to obtain multiple sets of field response data, which are then compared with pre-established reference data.

[0035] After calibration is completed, the servo motor 403 is controlled to rotate in the reverse direction, so that the annular cam drive disk 408 returns to its initial position. Each dielectric loading petal 412 is reset outward under the guidance of the corresponding radial guide groove group 411. Then the upper cover assembly 105 is opened and the sensor to be calibrated is taken out.

[0036] like Figure 1 , Figure 2 , Figure 9 and Figure 10 As shown, a carrying support assembly 2 is provided on the outer side of the housing 1. The carrying support assembly 2 includes a carrying strap 201, a support connector 202, a foam board 203, and a reinforcing support plate 204. The support connector 202 is detachably snapped into the housing fixing connector 104 on the rear outer wall of the housing 1. The foam board 203 and the reinforcing support plate 204 are stacked along the thickness direction of the carrying support assembly 2, with the foam board 203 located between the carrying strap 201 and the reinforcing support plate 204.

[0037] Without altering the aforementioned basic structural relationships, the number and radial travel of the dielectric loading petals 412 can be adapted to different models of soil moisture sensors; the positioning hole profiles of the upper positioning support plate 3 and the lower positioning support plate 301 can also be adjusted according to the shape of the sensor to be calibrated. The scope of protection of this utility model is defined by the claims.

Claims

1. A rapid on-site calibration device for a soil moisture sensor, comprising a housing (1), characterized in that: The housing (1) contains an upper positioning support plate (3) and a lower positioning support plate (301) spaced apart along the same calibration axis. The upper positioning support plate (3) and the lower positioning support plate (301) are respectively provided with positioning holes coaxial with the calibration axis. Below the lower positioning support plate (301) are an annular cam drive plate (408) and a loading mechanism mounting plate (409). The loading mechanism mounting plate (409) is coaxial with the positioning holes and is provided with multiple radial guide groove groups (411) along the circumference. Each radial guide groove group (411) includes two limiting guide grooves arranged in parallel along the circumference and extending radially, and a bearing guide. The bearing guide groove is located between two limiting guide grooves; each radial guide groove group (411) is provided with a dielectric loading petal (412), and multiple dielectric loading petals (412) are arranged around the calibration axis. The lower part of each dielectric loading petal (412) is provided with two limiting posts (413) and a driven bearing (414). The two limiting posts (413) extend into the corresponding two limiting guide grooves and slide with them. The driven bearing (414) passes through the corresponding bearing guide groove and rolls with the corresponding arc-shaped drive groove on the annular cam drive disk (408). The dielectric loading petal (412) is made of polytetrafluoroethylene.

2. The on-site rapid calibration device for a soil moisture sensor according to claim 1, characterized in that: The dielectric loading lobes (412) have the same structure. The dielectric loading lobes (412) are plate-shaped or petal-shaped structures extending along the calibration axis. Each dielectric loading lobe (412) forms a loading surface on the side facing the calibration axis. Each loading surface is equidistant from the calibration axis in the same driving position.

3. The on-site rapid calibration device for a soil moisture sensor according to claim 2, characterized in that: The dielectric loading lobe (412), the radial guide groove group (411), and the arc-shaped drive groove are all six in number. The six radial guide groove groups (411) are arranged in a rotationally symmetrical manner with the calibration axis as the center. The six arc-shaped drive grooves correspond one-to-one with the bearing guide grooves in the six radial guide groove groups (411).

4. The on-site rapid calibration device for a soil moisture sensor according to claim 1, characterized in that: The housing (1) is also provided with a drive base (4), which includes a servo motor (403), a worm (404) and a worm wheel (407). The servo motor (403), the worm (404), the worm wheel (407) and the annular cam drive disk (408) are connected in sequence for transmission.

5. The on-site rapid calibration device for a soil moisture sensor according to claim 4, characterized in that: The drive base (4) also includes a support plate (405) and a support bearing (406). The annular cam drive plate (408) is rotatably mounted on the support plate (405) via the support bearing (406), and the loading mechanism mounting plate (409) is fixedly mounted above the support plate (405).

6. The on-site rapid calibration device for a soil moisture sensor according to claim 4, characterized in that: The worm (404) and worm wheel (407) mesh with each other and form a worm gear reduction transmission pair.

7. The on-site rapid calibration device for a soil moisture sensor according to claim 1, characterized in that: A temperature sensor (302) is installed on the surface of the lower positioning support plate (301).

8. The on-site rapid calibration device for a soil moisture sensor according to claim 4, characterized in that: The housing (1) is provided with a display operation window (101) and a drive adjustment knob (102). The housing (1) is provided with a power supply (401) and a package chip (402). The package chip (402) is electrically connected to the display operation window (101), the drive adjustment knob (102) and the servo motor (403) respectively.

9. The on-site rapid calibration device for a soil moisture sensor according to claim 1, characterized in that: The top of the housing (1) is provided with a top cover assembly (105), one side of the top cover assembly (105) is hinged to the housing (1), and the other side is provided with a locking structure between it and the housing (1); the lower part of the housing (1) is provided with a power dust plug (103), and the rear outer wall of the housing (1) is provided with a housing fixing connector (104).

10. A rapid on-site calibration device for a soil moisture sensor according to claim 9, characterized in that: The outer side of the housing (1) is provided with a carrying support assembly (2). The carrying support assembly (2) includes a carrying strap (201), a support connector (202), a foam board (203), and a reinforcing support plate (204). The support connector (202) is detachably snapped into the housing fixing connector (104). The foam board (203) and the reinforcing support plate (204) are stacked along the thickness direction of the carrying support assembly (2). The foam board (203) is located between the carrying strap (201) and the reinforcing support plate (204).

Images