Calibration device of soil hygrometer

Abstract

The embodiment of the utility model discloses a calibration device of a soil hygrometer, which relates to the technical field of soil moisture measurement, and comprises a bracket, a protective cylinder, a telescopic mechanism and a monitoring mechanism, the support comprises a cover plate, and the cover plate is provided with a penetration hole. The pile casing is arranged above the cover plate, and the inner diameter of the pile casing is larger than or equal to the diameter of the penetration hole; the telescopic mechanism is arranged above the protective cylinder and connected with the monitoring mechanism, and the protective cylinder surrounds the periphery of the monitoring mechanism; the telescopic mechanism drives the monitoring mechanism to move back and forth in the axial direction of the protective cylinder. The effect of improving the accuracy of the calibration data is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of soil moisture measurement, in particular to a calibration device for a soil moisture meter. Background Art

[0002] Soil moisture content is usually measured on site using a soil moisture sensor, and accurate calibration of the soil moisture sensor is a prerequisite for accurate soil moisture content measurement. Because the moisture sensor calibration curves corresponding to different soil types are inconsistent, the soil moisture sensor needs to be accurately calibrated before installing it to measure the soil moisture content for different soil types, so as to obtain accurate soil moisture monitoring data.

[0003] The soil moisture sensor calibration is usually carried out by compacting soil samples with known moisture content in indoor containers, and then inserting the soil moisture sensor into containers with different soil samples with known moisture content to take readings. Each container with soil samples with known moisture content is a single calibration point. Then, the moisture sensor readings at the single calibration points in each container are obtained. Finally, the calibration curve of the soil moisture sensor corresponding to the soil body is drawn according to the readings of the moisture sensor at each calibration point.

[0004] At present, during the calibration process of the commonly used soil moisture sensor, the insertion and removal process of the soil moisture sensor is usually operated manually by hand. Manual hand-held insertion usually has three shortcomings: first, during the process of inserting the sensor into the soil, because the sensor is inserted by hand, it cannot be guaranteed that the sensor sensing needle can be perpendicular to the soil surface each time it is inserted, which causes an initial measurement error when the sensor needle is inserted into soil samples with different known moisture contents; second, during the calibration process, because test soils with different compaction degrees are used, if a soil with a relatively high compaction degree is encountered, it is difficult to manually insert the sensor needle into the soil. Even if the soil is inserted with effort, the sensor needle is easily damaged during the insertion process, increasing the risk of damaging the sensor; third, during the process of manually inserting the soil moisture sensor by hand, because it cannot be guaranteed that the sensor needle is facing the same direction during the entire insertion process, the penetration direction of the sensor needle during the insertion process will be uncertain, which will cause the sensor needle to cause a large disturbance to the soil around the sensor needle during the insertion process, increasing the error of the soil moisture sensor calibration. Utility Model Content

[0005] The technical problem to be solved by the embodiments of the utility model is that the data measured by the soil moisture sensor through manual handheld insertion has a large error.

[0006] In order to solve the above problems, the embodiment of the utility model discloses a soil moisture meter calibration device, which achieves the effect of improving the accuracy of calibration data.

[0007] The utility model provides a calibration device for a soil moisture meter, which comprises a bracket, a casing, a telescopic mechanism and a monitoring mechanism; the bracket comprises a cover plate, and the cover plate is provided with a penetration hole; the casing is arranged above the cover plate, and the inner diameter of the casing is greater than or equal to the diameter of the penetration hole; the telescopic mechanism is arranged above the casing and connected to the monitoring mechanism, and the casing surrounds the monitoring mechanism; wherein the telescopic mechanism drives the monitoring mechanism to move back and forth along the axial direction of the casing.

[0008] A further technical solution is that it also includes a sleeve, which is sleeved on the monitoring mechanism and connected to the telescopic mechanism, and the protective sleeve surrounds the four sides of the sleeve.

[0009] A further technical solution is that it also includes a connecting piece, which is clamped between the sleeve and the monitoring mechanism.

[0010] A further technical solution is that it also includes a fastener, the sleeve is provided with a fastening hole, the fastener passes through the fastening hole and is connected to the connecting piece.

[0011] A further technical solution is that the protective tube is provided with a limiting groove, and the sleeve is provided with a rib engaged with the limiting groove.

[0012] A further technical solution is that the telescopic mechanism comprises a motor and a telescopic rod, and the telescopic rod is connected to the motor and the monitoring mechanism respectively.

[0013] A further technical solution is that the telescopic rod is provided with a wire hole, the monitoring mechanism comprises a needle body, a shell and a wire, the shell is connected to the needle body and the wire respectively, and the wire passes through the wire hole.

[0014] A further technical solution is that the bracket also includes a rod and a plurality of columns, the plurality of columns are respectively arranged on the cover plate, and the rod is respectively connected to the sleeve, the motor and the plurality of columns.

[0015] A further technical solution is that it also includes a sample container, which is detachably connected to the cover plate, and the bracket, the protective tube, the telescopic mechanism and the monitoring mechanism are respectively on the same side of the sample container.

[0016] A further technical solution is that it also includes a data acquisition module, which is connected to the telescopic mechanism and the monitoring mechanism respectively.

[0017] Compared with the prior art, the technical effects that can be achieved by the embodiments of the present invention include:

[0018] The device can realize precise control of the monitoring mechanism during its penetration into the soil, ensure the uniqueness of the direction of the monitoring mechanism during its penetration into the soil, and avoid disturbance of the surrounding soil during the process, thus greatly improving the accuracy of the calibration data. At the same time, the calibration device can be applied to the calibration of soils with different compaction degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic structural diagram of a calibration device for a soil moisture meter provided in an embodiment of the utility model.

[0021] Reference numerals

[0022] Bracket 1, cover plate 11, protective tube 2, telescopic mechanism 3, monitoring mechanism 4, sleeve 5, connector 6, fastening hole 51, motor 31, telescopic rod 32, needle body 41, shell 42, wire 43, rod body 12, column 13, sample container 8, data acquisition module 9. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments. Similar component numbers in the drawings represent similar components. Obviously, the embodiments to be described below are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0024] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0025] It should also be understood that the terms used in this utility model embodiment specification are only for the purpose of describing specific embodiments and are not intended to limit the utility model embodiments. As used in the utility model embodiment specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0026] See also Figure 1 , an embodiment of the utility model provides a calibration device for a soil moisture meter. The calibration device of the soil moisture meter includes a bracket 1, a casing 2, a telescopic mechanism 3 and a monitoring mechanism 4; the bracket 1 includes a cover plate 11, and the cover plate 11 is provided with a penetration hole; the casing 2 is arranged above the cover plate 11, and the inner diameter of the casing 2 is greater than or equal to the diameter of the penetration hole; the telescopic mechanism 3 is arranged above the casing 2 and is connected to the monitoring mechanism 4, and the casing 2 surrounds the monitoring mechanism 4; wherein the telescopic mechanism 3 drives the monitoring mechanism 4 to move back and forth along the axial direction of the casing 2. The specific introduction of each component is as follows:

[0027] In this embodiment, the bracket 1 is used to install and fix various mechanisms, the casing 2 is fixedly erected on the cover plate 11, the opening of the casing 2 is connected to the penetration hole of the cover plate 11, the monitoring mechanism 4 is used to be inserted into the soil below the penetration hole to measure the moisture content of the soil, the telescopic mechanism 3 includes a fixed part and a movable part, the fixed part is fixedly arranged on the bracket 1, the movable part has the function of moving up and down, the monitoring mechanism 4 is fixed on the movable part, and the movable part drives the monitoring mechanism 4 to move back and forth along the axial direction of the casing 2, for example, the telescopic mechanism 3 drives the monitoring mechanism 4 to move downward, or the telescopic mechanism 3 drives the monitoring mechanism 4 to move upward. The monitoring mechanism 4 includes a soil moisture sensor (also known as a soil moisture meter), which is an instrument for measuring soil moisture content, including a probe, the probe is inserted into the soil, and an electromagnetic wave of a certain frequency is emitted through the probe, the electromagnetic wave is transmitted along the probe, and returns after reaching the bottom, and the voltage output by the probe is detected. Since the change of the soil dielectric constant usually depends on the moisture content of the soil, the moisture content of the soil can be calculated from the relationship between the output voltage and the moisture. In this embodiment, the penetration hole is arranged at the center of the cover plate 11 , and the diameter of the penetration hole is equal to the inner diameter of the casing 2 .

[0028] The sleeve 5 ensures that the monitoring mechanism 4 can maintain vertical upward and downward movement under the push of the telescopic mechanism 3, thereby ensuring that the probe of the monitoring mechanism 4 does not deflect during the process of being inserted into the soil.

[0029] The working process of the calibration device of the soil moisture meter is as follows:

[0030] First, compact and prepare the soil sample in a preset container, then place the cover plate 11 on top of the container, place the monitoring mechanism 4 in the casing 2, and install one end of the monitoring mechanism 4 on the retractable end of the telescopic mechanism 3. The telescopic mechanism 3 drives the monitoring mechanism 4 to move downward along the casing 2 and penetrate into the soil. When the penetration depth reaches the preset depth, the penetration is stopped, and the moisture content data of the soil is collected and recorded by the monitoring mechanism 4. After the monitoring mechanism 4 finishes reading the data, the telescopic mechanism 3 is started to drive the monitoring mechanism 4 to move upward until the monitoring mechanism 4 is completely pulled out and stops above the soil surface. At this point, a calibration point of a soil sample with a known moisture content is calibrated, and the calibration of the next calibration point can be carried out.

[0031] The device can realize precise control of the monitoring mechanism 4 during its penetration into the soil, ensure the uniqueness of the direction of the monitoring mechanism 4 during its penetration into the soil, and avoid disturbance of the surrounding soil during the process, thus greatly improving the accuracy of the calibration data. At the same time, the calibration device can be applied to the calibration of soils with different compaction degrees.

[0032] Continue to see Figure 1 In this embodiment, a sleeve 5 is further included. The sleeve 5 is sleeved on the monitoring mechanism 4 and connected to the telescopic mechanism 3 . The protective tube 2 surrounds the sleeve 5 .

[0033] Specifically, the bottom of the telescopic mechanism 3 is fixedly connected to the top of the sleeve 5 by a thread, and the sleeve 5 is used to fix the monitoring mechanism 4. The monitoring mechanism 4 is connected to the telescopic mechanism 3 through the sleeve 5 to realize the detachable connection between the monitoring mechanism 4 and the telescopic mechanism 3. The telescopic mechanism 3 drives the sleeve 5 and the monitoring mechanism 4 to move up and down along the axial direction of the casing 2 respectively. The outer diameter of the sleeve 5 is equal to or smaller than the inner diameter of the casing 2, so as to avoid the telescopic mechanism 3 driving the monitoring mechanism 4 to move up and down, causing friction between the monitoring mechanism 4 and the inner wall of the casing 2, thereby ensuring the durability of the monitoring mechanism 4. Furthermore, the outer wall of the sleeve 5 and the inner wall of the casing 2 can be polished into smooth surfaces respectively to reduce the friction between the sleeve 5 and the casing 2.

[0034] Furthermore, it also includes a connecting member 6 , which is clamped between the sleeve 5 and the monitoring mechanism 4 .

[0035] Furthermore, a fastener is also included. The sleeve 5 is provided with a fastening hole 51 . The fastener passes through the fastening hole 51 and is connected to the connecting member 6 .

[0036] Specifically, the connector 6 is an elastic structure made of rubber or silicone material, the inner diameter of the sleeve 5 is larger than the outer diameter of the monitoring mechanism 4, and the connector 6 is filled in the gap between the sleeve 5 and the monitoring mechanism 4 to achieve fixed connection between the sleeve 5 and the monitoring mechanism 4. The fastener includes a fastening pin, and the fastening hole 51 is usually set at the middle height of the sleeve 5. The outer wall of the fastener is provided with a thread, and the fastener can be screwed in / out of the fastening hole 51. The fastener is screwed in the fastening hole 51 until the end of the fastener presses the connector 6, so that the sleeve 5, the connector 6 and the monitoring mechanism 4 are fixed as a whole and move up and down with the telescopic mechanism 3.

[0037] The connection between the sleeve 5 and the monitoring mechanism 4 is reinforced by the connecting piece 6 to prevent the monitoring mechanism 4 from being damaged during the process of the sleeve 5 squeezing the monitoring mechanism 4. The connection between the sleeve 5, the connecting piece 6 and the monitoring mechanism 4 is reinforced by fasteners to effectively ensure the vertical up and down movement of the monitoring mechanism 4 along the axial direction of the casing 2.

[0038] Furthermore, the casing 2 is provided with a limiting groove, and the sleeve 5 is provided with a rib engaged with the limiting groove.

[0039] Specifically, the inner wall of the casing 2 is provided with a limiting groove distributed along the axial direction of the casing 2. In this embodiment, the axial direction of the casing 2 is a vertical up and down direction, and the outer wall of the sleeve 5 is provided with a rib that can be engaged with the limiting groove. Through the limiting groove and the rib, the sleeve 5 can be further ensured to move vertically up and down along the casing 2, preventing the sleeve 5 and the monitoring mechanism 4 in the sleeve 5 from circumferential rotation.

[0040] Furthermore, the telescopic mechanism 3 includes a motor 31 and a telescopic rod 32 , and the telescopic rod 32 is connected to the motor 31 and the monitoring mechanism 4 respectively.

[0041] Specifically, the motor 31 includes any one of a stepper motor and a servo motor, and is used to drive the telescopic rod 32 to extend / contract. The telescopic rod 32 includes any one of a lead screw and a sleeve rod. One end of the telescopic rod 32 is fixed to the motor 31, and the other end can move closer to / away from the motor 31 under the action of the motor 31. In one embodiment, the up and down movement distance of the telescopic rod 32 can be controlled by the program of the motor 31.

[0042] Furthermore, the telescopic rod 32 is provided with a wire hole, and the monitoring mechanism 4 includes a needle body 41, a shell 42 and a wire 43, the shell 42 is connected to the needle body 41 and the wire 43 respectively, and the wire 43 passes through the wire hole.

[0043] Specifically, the telescopic rod 32 is made of metal material and has a hollow structure inside. The side wall is preset with a wire hole. A small hole is opened at the top center of the sleeve 5. The wire 43 can pass through the small hole to enter the telescopic rod 32 and be led out through the wire hole of the telescopic rod 32. In one embodiment, the wire 43 is connected to the data acquisition module 9. The monitoring mechanism 4 includes a needle body 41, a shell 42 and a wire 43. The needle body 41, the shell 42 and the wire 43 are fixed by gluing.

[0044] Furthermore, the bracket 1 further includes a rod 12 and a plurality of columns 13 . The plurality of columns 13 are respectively disposed on the cover plate 11 . The rod 12 is respectively connected to the sleeve 5 , the motor 31 and the plurality of columns 13 .

[0045] Specifically, the top of the casing 2 is installed on the lower part of the rod body 12 by bolts, two vertical columns 13 are fixed on the cover plate 11 by threads, the two columns 13 are horizontally connected through the rod body 12, the rod body 12 and multiple columns 13 are respectively connected and fixed by screws, the motor 31 is installed and fixed at the center position of the rod body 12 by bolts, and the sleeve 5 is detachably connected to the rod body 12.

[0046] Furthermore, it also includes a sample container 8 which is detachably connected to the cover plate 11 , and the bracket 1 , the casing 2 , the telescopic mechanism 3 and the monitoring mechanism 4 are respectively on the same side of the sample container 8 .

[0047] Specifically, the sample container 8 can be made of one or more materials such as organic glass and metal, and is usually cylindrical. In this embodiment, the sample container 8 is a barrel-shaped structure with an inner diameter greater than 10 cm and a height greater than 20 cm. The opening of the sample container 8 faces upward, and the cover 11 covers the opening of the sample container 8. In one embodiment, the cover 11 is connected to the side wall of the sample container 8 at the edge, including bolt fixing connection, hinge rotation connection, and snap connection. For example, the side wall of the sample container 8 is drilled with screw mounting holes, and screw holes are provided at the edge of the cover 11. The sample container 8 is detachably connected to the cover 11 by passing bolts through the screw holes and mounting holes. The bracket 1, the casing 2, the telescopic mechanism 3, and the monitoring mechanism 4 are respectively installed above the cover 11.

[0048] Furthermore, it also includes a data acquisition module 9, which is connected to the telescopic mechanism 3 and the monitoring mechanism 4 respectively.

[0049] Specifically, the data acquisition module 9 includes a storage device and a processor. The program of the processor starts the motor 31 to control the telescopic rod 32 to drive the needle body 41 to move downward and insert into the soil. When the depth of insertion into the soil reaches a preset height, for example, when the bottom surface of the sleeve 5 is level with the bottom of the casing 2, the insertion is stopped, and the monitoring mechanism 4 operates and transmits the collected data to the data acquisition module 9 through the wire 43 for recording. When the data is read, the program of the motor 31 is started by the program of the processor to control the telescopic rod 32 to drive the monitoring mechanism 4 to move upward until the needle body 41 is completely pulled out of the soil. At this point, the calibration of a soil sample with a known moisture content is completed, and the calibration of the next calibration point can be carried out.

[0050] By controlling the telescopic mechanism 3 through the data acquisition module 9, measurement errors caused by uneven manual force, which causes the needle body 41 to be unable to be perpendicular to the soil surface during the insertion process, can be avoided, thereby achieving more accurate measurement data.

[0051] In one embodiment, the installation process of the calibration device of the soil moisture meter is as follows:

[0052] First, prepare the soil sample by compacting in the sample container 8, then bolt the cover plate 11 to the sample container 8, install the two columns 13 on the cover plate 11, and install the rod body 12 on the two columns 13 respectively, then place the housing 42 of the monitoring mechanism 4 in the sleeve 5, and place the connecting piece 6 between the housing 42 and the sleeve 5, then pass the fastener through the fastening hole 51 and screw it forward until it presses the housing 42 to stop, then install the sleeve 5 on the telescopic rod 32 by threading, install the casing 2 between the rod body 12 and the cover plate 11 by bolts, and finally install the motor 31 on the rod body 12.

[0053] Compared with the prior art, the technical effects achieved by the embodiments of the present invention include:

[0054] The calibration device of the soil moisture meter uses a telescopic mechanism 3 to drive the monitoring mechanism 4 to accurately penetrate the soil, and is positioned by the casing 2 during the penetration process, thereby ensuring the uniqueness of the direction of the needle 41 of the monitoring mechanism 4 during the penetration process of the soil, and avoiding disturbance. The calibration device of the soil moisture meter can simplify manual steps, has strong operability, improves the accuracy of the calibration data of the soil moisture meter, and also improves the automation and mechanization degree of the soil moisture meter calibration, and reduces the uncertainty during manual operation.

[0055] The calibration device of the soil moisture meter can quickly perform penetration operations on compacted soil samples with different known moisture contents under the same standard procedure, thereby reducing the calibration error caused by penetration differences at various calibration points when the existing handheld moisture content sensor is used to penetrate the soil.

[0056] In the calibration device of the soil moisture meter, a casing 2 is used to orient the monitoring mechanism 4 when it penetrates the soil, ensuring that the needle body 41 remains in a vertical fixed direction when it penetrates the soil, thereby avoiding the direction uncertainty problem caused by the penetration of the existing handheld monitoring mechanism 4. At the same time, it also avoids the problem of the soil around the needle body 41 being greatly disturbed due to the direction uncertainty when the needle body 41 penetrates, thereby greatly reducing the calibration error of the monitoring mechanism 4.

[0057] The calibration device of the soil moisture meter adopts a motor 31 to program-control the needle 41 to mechanically penetrate the soil, has wider applicability and operational certainty, and can be used to calibrate the monitoring mechanism 4 in soils of different soil qualities and different compaction degrees.

[0058] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0059] In the description of the present invention, it should 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" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and 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 a limitation on the present invention.

[0060] 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 one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0061] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be connected, detachably connected, or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0062] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0063] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means 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 utility model. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed 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.

[0064] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these modifications and variations.

[0065] The above is a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the utility model, and these modifications or replacements should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A soil moisture meter calibration device, characterized in that: It includes a bracket, a casing, a telescopic mechanism and a monitoring mechanism; The bracket includes a cover plate, and the cover plate is provided with a penetration hole; the protective tube is arranged above the cover plate, and the inner diameter of the protective tube is greater than or equal to the diameter of the penetration hole; The telescopic mechanism is arranged above the protective tube and connected to the monitoring mechanism, and the protective tube surrounds the monitoring mechanism; The telescopic mechanism drives the monitoring mechanism to move back and forth along the axial direction of the casing.

2. The soil moisture meter calibration device according to claim 1, characterized in that: It also includes a sleeve, which is sleeved on the monitoring mechanism and connected to the telescopic mechanism, and the protective sleeve surrounds the four sides of the sleeve.

3. The calibration device of the soil moisture meter according to claim 2, characterized in that: Also included is a connecting piece, which is clamped between the sleeve and the monitoring mechanism.

4. The calibration device for a soil moisture meter according to claim 3, characterized in that: It also includes a fastener, the sleeve is provided with a fastening hole, the fastener passes through the fastening hole and is connected to the connecting piece.

5. The calibration device for a soil moisture meter according to claim 2, characterized in that: The protective tube is provided with a limiting groove, and the sleeve is provided with a rib engaged with the limiting groove.

6. The calibration device for a soil moisture meter according to claim 2, characterized in that: The telescopic mechanism comprises a motor and a telescopic rod, and the telescopic rod is connected to the motor and the monitoring mechanism respectively.

7. The calibration device for a soil moisture meter according to claim 6, characterized in that: The telescopic rod is provided with a wire hole, and the monitoring mechanism comprises a needle body, a shell and a wire. The shell is connected to the needle body and the wire respectively, and the wire passes through the wire hole.

8. The soil moisture meter calibration device according to claim 7, characterized in that: The bracket also includes a rod body and a plurality of columns. The plurality of columns are respectively arranged on the cover plate. The rod body is respectively connected to the sleeve, the motor and the plurality of columns.

9. The calibration device for a soil moisture meter according to claim 1, characterized in that: It also includes a sample container, which is detachably connected to the cover plate. The bracket, the protective tube, the telescopic mechanism and the monitoring mechanism are respectively located on the same side of the sample container.

10. The calibration device for a soil moisture meter according to claim 1, characterized in that: It also includes a data acquisition module, which is connected to the telescopic mechanism and the monitoring mechanism respectively.

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