Soil sample preparation apparatus and self-cleaning method thereof

Abstract

This invention discloses a soil sample preparation device and its self-cleaning method, belonging to the field of soil sample pretreatment technology. The device includes a stator, a cover plate, a bottom plate, a rotor, a drive mechanism, a receiving pipe, an impeller, and a control system. The stator has a conical crushing and mixing chamber that is larger at the top and smaller at the bottom. The cover plate has a feeding hole and an air inlet, and the bottom plate has a discharge port. The rotor axis is offset from the stator axis, rotating on its own axis while revolving around the stator axis. The drive mechanism drives the rotor to rotate in a first rotation direction to achieve crushing and mixing of the soil sample, or in the opposite second rotation direction. The combined motion of the rotor's revolution and rotation creates a periodic cycloidal turbulence in the airflow near the inner wall of the crushing and mixing chamber, applying alternating shear force to peel off and discharge soil residues adhering to the inner wall. This invention achieves both crushing and self-cleaning functions through a single drive mechanism, effectively avoiding cross-contamination of samples.

Description

Technical Field

[0001] This invention relates to the field of soil sample pretreatment technology, specifically to a soil sample preparation device and its self-cleaning method. Background Technology

[0002] In fields such as soil environmental monitoring, agricultural soil fertility testing, and geological and mineral exploration, collected soil samples need to undergo pretreatment processes such as crushing, mixing, and packaging in order to meet the requirements of subsequent chemical analysis or physical testing.

[0003] Currently, soil sample pretreatment is still mainly done manually, which faces prominent problems such as low efficiency, poor quality control, and low standardization. To solve these problems, the industry has begun to develop automated soil sample preparation equipment. Existing equipment typically integrates modules such as crushing and grinding mechanisms, screening mechanisms, and dispensing mechanisms, which can achieve a certain degree of automation in soil sample processing.

[0004] However, existing automated soil sample preparation equipment still has the following shortcomings: First, there is a high risk of cross-contamination. After use, soil residue easily adheres to the inner wall of the crushing and mixing chamber of existing equipment, as well as to components such as blades and shafts. If not effectively cleaned, the residual soil will mix into the next batch of samples, causing cross-contamination and seriously affecting the accuracy of the test results.

[0005] Secondly, the cleaning process is complex and inefficient. Existing equipment often requires manual disassembly of the chambers by operators after shutdown for cleaning, or it uses a spray washing method. Manual disassembly is time-consuming and labor-intensive, and it's difficult to guarantee thorough cleaning; spray washing requires a water source and drying equipment, increasing the complexity and footprint of the equipment, and wastewater discharge after cleaning is also a problem.

[0006] Third, existing self-cleaning solutions rely on adding auxiliary structures. Some existing technologies attempt to achieve self-cleaning by adding structures such as cleaning plates, scrapers, or cleaning brushes inside the crushing chamber. For example, a cleaning plate is fixedly connected to a rotating rod, making the cleaning plate fit against the inner wall of the grinding tank, and scraping off the adhering soil when the rotating rod rotates. However, this solution requires additional cleaning components, increasing the cost and failure rate of the equipment, and the contact pressure between the cleaning plate and the chamber wall is difficult to control precisely, leading to wear of the chamber wall with long-term use.

[0007] Therefore, there is an urgent need for a soil sample preparation device and its self-cleaning method that can automatically and effectively clean the soil sample after crushing and mixing without the need for additional auxiliary cleaning components. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a soil sample preparation device and its self-cleaning method, in order to address the technical problems of existing soil sample preparation devices, such as high risk of cross-contamination, complex cleaning operation, and reliance on the addition of auxiliary cleaning components.

[0009] This invention is achieved through the following technical solution: A soil sample preparation device, comprising: The stator has a cone-shaped crushing and mixing chamber that is larger at the top and smaller at the bottom; A cover plate is provided at the upper end of the stator, and the cover plate is provided with a feeding hole and several air inlets; A base plate is disposed at the lower end of the stator, and a discharge port is provided on the base plate; A first opening and closing structure is provided on the cover plate for opening or closing the feeding hole; The second opening and closing structure is provided on the cover plate and is used to open or close the air inlet. The third opening and closing structure is provided on the base plate and is used to open or close the discharge port; A rotor is disposed within the crushing and mixing chamber, and the axis of the rotor is offset from the axis of the stator; A drive mechanism, connected to the rotor, is used to drive the rotor to rotate in a first rotation direction or a second rotation direction opposite to the first rotation direction, and to drive the rotor to revolve around the axis of the stator while rotating on its own axis. The first rotation direction is used to drive the rotor to crush and mix the soil sample in the crushing and mixing chamber; the second rotation direction is used to drive the rotor to form a periodic cycloidal turbulence in the airflow near the inner wall of the crushing and mixing chamber under the combined motion of revolution and rotation, so as to clean the inner wall of the crushing and mixing chamber. A receiving pipe is connected to the bottom of the base plate and communicates with the discharge port; An impeller is connected to the rotor via a shaft and disposed inside the receiving pipe. When the rotor rotates in the second rotation direction, the impeller is driven to rotate by the rotor via the shaft, generating a suction airflow in the receiving pipe, which draws the stripped residue into the receiving pipe through the discharge port and discharges it. The control system is electrically connected to the drive mechanism and is used to control the rotation direction, speed and start / stop actions of the drive mechanism according to a preset timing sequence.

[0010] Further specified, the drive mechanism includes a first planetary gear mechanism disposed at the upper end of the stator and a second planetary gear mechanism disposed at the lower end of the stator. The first planetary gear mechanism and the second planetary gear mechanism have the same structure, each including an internal gear ring, at least one planetary gear and a sun gear. The upper end of the rotor is connected to the planetary gears of the first planetary gear mechanism, and the lower end of the rotor is connected to the planetary gears of the second planetary gear mechanism. The sun gear of the first planetary gear mechanism is used to connect to the output shaft of the drive motor as a power input.

[0011] Further specifying, the sun gear of the second planetary gear mechanism is fixedly connected to a downwardly extending shaft, and the impeller is connected to the lower end of the shaft.

[0012] Further specified, the air inlet is located at the edge of the cover plate and is opposite to the upper inner edge of the crushing and mixing chamber, and the air entering through the air inlet is blown downward along the cavity wall of the crushing and mixing chamber.

[0013] Further defined, the impeller includes a central block and multiple blades, and the upper end of each blade is hinged to the edge of the central block by a pin; During rotation, the blades are dispersed outward at their lower ends by centrifugal force, and the dispersion angle is proportional to the rotation speed. An upwardly protruding limiting block is provided on the outer side of the upper end of the blade, and the limiting block is used to limit the maximum angle when the blade rotates upward.

[0014] Further, it also includes a counterweight, which is disposed on the second planetary gear mechanism, and the counterweight and the shaft are respectively located on opposite sides of the sun gear rotation center of the second planetary gear mechanism, to counteract the centrifugal inertial force generated by the rotor's revolution.

[0015] A self-cleaning method using the above-mentioned soil sample preparation equipment includes the following steps: S1: Open the feeding hole, feed the soil sample into the crushing and mixing chamber through the feeding hole, close the feeding hole, drive the rotor to rotate in the first rotation direction, and crush and mix the soil sample. S2: Open the discharge port and drive the rotor to rotate continuously along the first rotation direction at a third speed n3. The rotor pushes the crushed and mixed soil sample toward the discharge port and discharges it. S3: Close the discharge port and drive the rotor to rotate in a second rotation direction opposite to the first rotation direction. Under the combined motion of revolution and rotation, the rotor causes the airflow near the inner wall of the stator to form a periodic cycloidal turbulence, which applies alternating shear force to the soil residues adhering to the inner wall of the stator, peels them off and discharges them with the airflow. In step S1, the rotor rotates along the first rotation direction at a first speed n1; in step S2, the third speed n3 is less than the first speed n1; in step S3, the rotor rotates along the second rotation direction at a second speed n2, and n2 ≥ 2 × n1, and the duration of the rotor rotating along the second rotation direction is 10 seconds to 30 seconds. Before driving the rotor to rotate in the second rotation direction, at least one pulse action of rapid acceleration and sudden braking is performed.

[0016] Further specifying that in step S3, the feeding hole remains closed, the air inlet is opened, and external air enters the stator through the air inlet, and is blown downward along the cavity wall from the upper end of the crushing and mixing chamber, participating in the airflow disturbance.

[0017] Furthermore, steps S1, S2, and S3 are automatically controlled and executed by the control system according to a preset timing sequence; The control system outputs a first control signal to control the rotor to rotate at the first speed n1 along the first rotation direction and maintain it for a first set time. The control system outputs a discharge control signal to control the rotor to rotate at the third speed n3 along the first rotation direction and maintain it for a third set time. The control system outputs a second control signal to control the rotor to rotate at the second speed n2 along the second rotation direction and maintain it for a second set duration. Before outputting the second control signal, the control system first outputs a pulse control signal to control the drive mechanism to perform at least one pulse action of rapid acceleration and rapid braking.

[0018] Further specifying that in step S3, when the rotor rotates along the second rotation direction, it drives the impeller to rotate through the shaft. The impeller generates a suction airflow in the receiving pipe, drawing the stripped soil residue into the receiving pipe through the discharge port and discharging it.

[0019] The beneficial effects of this invention are as follows: This invention utilizes the eccentric rotor configuration and the combined motion characteristics of revolution and rotation. When the rotor rotates at high speed in the second rotation direction (opposite direction), the eccentric revolution of the rotor causes the airflow in the crushing and mixing chamber to form a periodic cycloidal turbulence. This special turbulent state applies alternating shear force to the soil residue adhering to the inner wall of the chamber, causing it to peel off from the wall and be discharged with the airflow. The entire process requires no additional cleaning components such as sweeping plates, scrapers, or cleaning brushes; it relies entirely on the self-cleaning of the equipment's own motion state switching, which reduces equipment costs and avoids secondary pollution caused by the wear of auxiliary components.

[0020] Before driving the rotor to rotate in the reverse direction, this invention performs at least one rapid acceleration and braking pulse action. Utilizing the inertial hysteresis effect, it causes a peeling effect on the adhered wet soil, actively detaching it from the wall surface. Subsequently, the rotor rotates in the reverse direction at a speed no less than twice the crushing speed (n2 ≥ 2 × n1) for 10–30 seconds. The resulting high-speed cycloidal turbulence completely blows away the loosened residue. This two-step synergistic effect also provides excellent cleaning results for sticky soils with high moisture content.

[0021] The drive mechanism of this invention performs both crushing and mixing and self-cleaning functions. The first rotation direction is used for crushing and mixing, and the second rotation direction is used to generate a cleaning airflow. The same planetary gear mechanism drives the rotor to crush during forward rotation and generates a cleaning airflow during reverse rotation. Furthermore, the sun gear of the second planetary gear mechanism also acts as a transmission intermediate, transmitting power to the shaft and impeller. During the cleaning phase, it generates a suction airflow to actively draw away and discharge the stripped residue.

[0022] The cover plate of the present invention has several air inlets. When cleaning, the air inlets are opened, and external air is blown down along the conical cavity wall from the upper end of the crushing and mixing chamber. This airflow forms a directional airflow from top to bottom with the cycloidal turbulence generated by the rotor's counter-rotation, ensuring that the stripped residue is discharged smoothly through the bottom outlet and avoiding secondary deposition of residue in the cavity.

[0023] The device of this invention can be used in conjunction with dual-compartment or multi-compartment sample containers. After the soil sample is crushed and mixed, it is directly and evenly dropped into each independent compartment, obtaining parallel samples in one go, thus ensuring the consistency and representativeness of the parallel samples.

[0024] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0025] Figure 1 The soil sample preparation device of the present invention is three-dimensional. Figure 1 ; Figure 2 The three-dimensional representation of the soil sample preparation device of the present invention Figure 2 ; Figure 3 This is a front view of the soil sample preparation equipment of the present invention; Figure 4 for Figure 3 A schematic diagram of the cross-sectional structure of AA; Figure 5 for Figure 3 Schematic diagram of the cross-sectional structure of BB; Figure 6 for Figure 3 A schematic diagram of the cross-sectional structure of CC. Figure 7 This is a schematic diagram of the stator structure; Figure 8 This is a schematic diagram of the connection structure between the impeller and the shaft; Figure 9 This is a flowchart of the self-cleaning method of the present invention; In the diagram: 1. Stator; 11. Crushing and mixing chamber; 2. Cover plate; 21. Feeding hole; 22. Air inlet; 3. Bottom plate; 31. Discharge port; 4. First opening and closing structure; 41. Second opening and closing structure; 42. Third opening and closing structure; 5. Rotor; 6. Drive mechanism; 61. First planetary gear mechanism; 611. First sun gear; 612. First planetary gear; 613. First internal gear ring; 62. Second planetary gear mechanism; 621. Second sun gear; 622. Second planetary gear; 623. Second internal gear ring; 7. Receiving pipe; 8. Impeller; 81. Center block; 82. Blade; 83. Pin; 84. Limiting block; 9. Shaft; 10. Counterweight. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the above description of the present invention, it should be noted that the terms "one side," "the other side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use. These terms are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] Furthermore, terms such as "identical" do not imply that components must be absolutely identical; minor differences are permissible. The term "perpendicular" simply means that the positional relationship between components is more perpendicular than "parallel," not that the structure must be perfectly perpendicular; a slight tilt is acceptable.

[0031] Please see Figure 1-8 The present invention provides a technical solution: a soil sample preparation device provided by the present invention includes a stator 1, a cover plate 2, a bottom plate 3, a rotor 5, a drive mechanism 6, a receiving pipe 7, an impeller 8 and a control system; The stator 1 has a cone-shaped crushing and mixing chamber 11 that is larger at the top and smaller at the bottom. The cone shape is conducive to the soil sample concentrating at the bottom during the crushing and mixing process. It also facilitates the directional flow of air along the chamber wall from top to bottom during cleaning, reducing cleaning dead corners. The cover plate 2 is located at the upper end of the stator 1 and is used to close the upper opening of the crushing and mixing chamber 11. The cover plate 2 is provided with a feeding hole 21 and several air inlets 22. The feeding hole 21 is used to feed the soil sample to be processed into the crushing and mixing chamber 11. The air inlets 22 are located at the edge of the cover plate 2 and are opposite to the upper inner edge of the crushing and mixing chamber 11. The air entering through the air inlets 22 is blown downward along the chamber wall of the crushing and mixing chamber 11. The bottom plate 3 is located at the lower end of the stator 1. The bottom plate 3 has a discharge port 31 for discharging soil samples after crushing and mixing or residues discharged during cleaning. The first opening and closing structure 4 is provided on the cover plate 2 for opening or closing the feeding hole 21. The second opening and closing structure 41 is provided on the cover plate 2 for opening or closing the air inlet 22. The third opening and closing structure 42 is provided on the bottom plate 3 for opening or closing the discharge port 31. The first opening and closing structure 4, the second opening and closing structure 41 and the third opening and closing structure 42 are all ring structures with holes. The first opening and closing structure 4 is rotatably fitted on the cover plate 2, and the hole on it corresponds to the feeding hole 21. The feeding hole 21 is opened when the hole is aligned with the feeding hole 21 by manual or electric means, and closed when the hole is misaligned. Similarly, the second opening and closing structure 41 is rotatably fitted on the cover plate 2, and the hole on it corresponds to the air inlet 22. The air inlet 22 is opened or closed by rotation. The third opening and closing structure 42 is rotatably fitted on the bottom plate 3, and the hole on it corresponds to the discharge port 31. The discharge port 31 is opened or closed by rotation. Each opening and closing mechanism can be manually operated by the operator using a manual handle, or it can be equipped with a micro motor driven by the control system to achieve automatic control; the rotor 5 is set in the crushing and mixing chamber 11, and the axis of the rotor 5 is offset from the axis of the stator 1 (i.e., eccentric setting). The surface of the rotor 5 can be provided with crushing teeth or crushing blades for cutting, crushing and mixing soil samples. The drive mechanism 6 is connected to the rotor 5 for driving the rotor 5 to rotate in a first rotation direction or a second rotation direction opposite to the first rotation direction, and to drive the rotor 5 to revolve around the axis of the stator 1 while rotating on its own axis. The drive mechanism 6 includes a first planetary gear mechanism 61 disposed at the upper end of the stator 1 and a second planetary gear mechanism 62 disposed at the lower end of the stator 1. The first planetary gear mechanism 61 and the second planetary gear mechanism 62 have the same structure, both including an internal gear ring, at least one planetary gear and a sun gear.

[0032] Specifically, the first planetary gear mechanism 61 includes a first internal gear ring 613, at least one first planetary gear 612, and a first sun gear 611. The first internal gear ring 613 is fixedly disposed on the cover plate 2 or the upper end of the stator 1. The first sun gear 611 is disposed at the center of the first internal gear ring 613 and is used to connect with the output shaft of the drive motor (not shown in the figure) as a power input end. The first planetary gear 612 is disposed between the first internal gear ring 613 and the first sun gear 611 and meshes with the first internal gear ring 613 and the first sun gear 611 respectively. The second planetary gear mechanism 62 includes a second internal gear ring 623, at least one second planetary gear 622, and a second sun gear 621. The second internal gear ring 623 is fixedly disposed on the base plate 3 or the lower end of the stator 1. The second sun gear 621 is disposed at the center of the second internal gear ring 623. The second planetary gear 622 is disposed between the second internal gear ring 623 and the second sun gear 621, and meshes with the second internal gear ring 623 and the second sun gear 621 respectively. The upper end of the rotor 5 is connected to the first planetary gear 612, and the lower end of the rotor 5 is connected to the second planetary gear 622. When the first sun gear 611 is driven to rotate by the drive motor, the rotor 5 rotates through the first planetary gear 612. At the same time, since the first planetary gear 612 revolves around the first sun gear 611, the rotor 5 revolves around the axis of the stator 1 while rotating. The second planetary gear 622 at the lower end of the rotor 5 moves synchronously with the rotor 5 and transmits the motion to the second sun gear 621. The first rotation direction is used to drive the rotor 5 to crush and mix the soil sample in the crushing and mixing chamber 11; the second rotation direction (opposite to the first rotation direction) is used to drive the rotor 5 to form a periodic cycloidal turbulence in the airflow near the inner wall of the crushing and mixing chamber 11 under the combined motion of revolution and rotation, so as to clean the inner wall of the crushing and mixing chamber 11. The receiving pipe 7 is connected to the bottom of the base plate 3 and communicates with the discharge port 31. It is used to receive soil samples discharged from the crushing and mixing chamber 11 or residues discharged during cleaning. Impeller 8 is connected to rotor 5 via shaft 9 and is disposed in receiving pipe 7. Specifically, shaft 9 extending downward is fixedly connected to second sun gear 621. Shaft 9 extends into receiving pipe 7. Impeller 8 is connected to the lower end of shaft 9. When rotor 5 rotates in the second rotation direction, impeller 8 is driven to rotate by rotor 5 via shaft 9, generating suction airflow in receiving pipe 7, which draws the stripped residue into receiving pipe 7 through discharge port 31 and discharges it. The impeller 8 includes a central block 81 and multiple blades 82. The upper end of each blade 82 is hinged to the edge of the central block 81 by a pin 83. During rotation, the lower end of the blade 82 is dispersed outward by centrifugal force, and the dispersion angle is proportional to the rotation speed. That is, the higher the rotation speed, the larger the opening angle of the blade 82, and the stronger the suction airflow generated. An upwardly protruding limiting block 84 is provided on the outer side of the upper end of the blade 82. The limiting block 84 is used to limit the maximum angle when the blade 82 rotates upward, and prevent the blade 82 from opening too much during high-speed rotation and causing it to collide with the inner wall of the receiving pipe 7. The control system is electrically connected to the drive mechanism 6 (specifically the drive motor) and is used to control the rotation direction, speed and start / stop action of the drive mechanism 6 according to a preset timing sequence. In addition, it also includes a counterweight 10, which is set on the second planetary gear mechanism 62. The counterweight 10 and the shaft 9 are located on opposite sides of the rotation center of the second sun gear 621, respectively, to counteract the centrifugal inertial force generated by the revolution of the rotor 5, reduce the vibration of the equipment at high speed, and extend the service life of the equipment. The following is combined Figure 9 The self-cleaning method of the present invention is described in detail below: The present invention provides a self-cleaning method using the above-mentioned soil sample preparation equipment, comprising the following steps: Step S1: The operator or automatic feeding device opens the feeding hole 21 (i.e., rotates the first opening and closing structure 4 to align its hole with the feeding hole 21), and feeds the rated weight of soil sample into the crushing and mixing chamber 11 through the feeding hole 21. After feeding is completed, the feeding hole 21 is closed (rotates the first opening and closing structure 4 to offset its hole from the feeding hole 21). At this time, the air inlet 22 and the discharge port 31 are both in a closed state. The control system outputs a first control signal to the drive mechanism 6, driving the rotor 5 to rotate at a first speed n1 along a first rotation direction to crush and mix the soil sample for a first set time (e.g., 30 to 60 seconds, depending on the hardness and moisture of the soil). During this process, the rotor 5 rotates on its own axis while revolving around the axis of the stator 1. The crushing teeth on the surface of the rotor cut, impact, and squeeze the soil sample to achieve crushing and mixing.

[0033] Step S2: After the crushing and mixing process is completed, the control system outputs a discharge control signal. First, the discharge port 31 is opened (specifically, the third opening and closing structure 42 is rotated so that its hole is aligned with the discharge port 31). Then, the drive mechanism 6 drives the rotor 5 to rotate continuously in the first rotation direction at a third speed n3 (the third speed n3 is less than the first speed n1, for example, n3 = 0.2n1 ~ 0.5n1). During the low-speed rotation, the rotor 5 continuously applies a pushing force to the soil sample in the crushing and mixing chamber 11, pushing the soil sample towards the discharge port 31 so that it falls smoothly into the receiving pipe 7 through the discharge port 31, and then into the sample container below. The beneficial effect of this low-speed discharge step is that by continuously rotating the rotor 5 at a low speed, the mechanical pushing action of the crushing teeth or blades on the rotor surface on the soil sample effectively eliminates the dead points of soil sample accumulation at the bottom of the crushing and mixing chamber 11 and the corner of the conical chamber wall, and avoids the situation where the soil sample is stuck in the chamber due to high humidity or inter-particle friction when relying solely on gravity discharge. After the material is discharged, the discharge port 31 is closed (the third opening and closing structure 42 is rotated to make its hole offset from the discharge port 31), and the rotor 5 stops rotating.

[0034] Step S3: After the discharge port 31 is closed, the control system first outputs a pulse control signal to control the drive mechanism 6 to perform at least one pulse action of rapid acceleration and rapid braking. That is, the rotor 5 rapidly accelerates to a certain speed in a short time and then immediately brakes to a stop. This is repeated 1 to 3 times. This pulse action uses the inertial hysteresis effect to cause the soil residues adhering to the inner wall of the crushing and mixing chamber 11 and the surface of the rotor 5 to produce a peeling effect and actively detach from the wall. Subsequently, the control system outputs a second control signal to drive the rotor 5 to rotate at a second speed n2 along a second rotation direction (opposite to the first rotation direction) for a duration of 10 to 30 seconds, where n2 ≥ 2 × n1; During the high-speed rotation of rotor 5 along the second rotation direction, feeding hole 21 remains closed (first opening and closing structure 4 is in the closed position), while air inlet 22 is opened (the second opening and closing structure 41 is rotated to align its hole with air inlet 22). The reason why feeding hole 21 must remain closed is that air inlet 22 is located at the edge of cover plate 2, opposite to the upper inner edge of crushing and mixing chamber 11. Its designed airflow path is to blow downward along the conical cavity wall from the upper end of crushing and mixing chamber 11. If feeding hole 21 is not closed, external air will preferentially escape from feeding hole 21 (located in the middle of cover plate, with a large opening area and short path), and cannot form an effective downward blowing airflow along the cavity wall, weakening or even losing the cleaning effect of blowing along the wall. Therefore, closing feeding hole 21 during the cleaning process is a prerequisite for ensuring the function of air inlet 22. With the feeding hole 21 closed and the air inlet 22 open, external air enters the stator 1 through the air inlet 22 and is blown downward along the conical cavity wall from the upper end of the crushing and mixing chamber 11. At the same time, since the axis of the rotor 5 is deviated from the axis of the stator 1, the rotor 5 revolves around the axis of the stator 1 while rotating on its own axis. This eccentric planetary motion causes the airflow near the inner wall of the crushing and mixing chamber 11 to form a periodic cycloidal turbulence. This periodic cycloidal turbulence applies alternating shear force to the soil residues adhering to the inner wall of the stator 1, completely peeling the residues that have been loosened by the pulse action from the wall. The external air blowing down along the wall from top to bottom and the cycloidal turbulence generated by the counter-rotation of the rotor 5 work together to drive the peeled residues toward the discharge port 31 at the bottom. At the same time, when the rotor 5 rotates in the second rotation direction, the second sun gear 621 is driven to rotate through the transmission chain consisting of the first planetary gear mechanism 61, the rotor 5, and the second planetary gear mechanism 62. This drives the shaft 9, which is fixedly connected to the second sun gear 621, to rotate. The impeller 8 rotates with the shaft 9, generating a suction airflow in the receiving pipe 7. This suction airflow draws the stripped soil residue into the receiving pipe 7 through the discharge port 31 and discharges it into the waste collection container.

[0035] During the cleaning process, the state of each orifice is as follows: feeding hole 21 is closed, air inlet 22 is open, and discharge port 31 is closed. The airflow path forms a complete loop: external air enters through air inlet 22 (edge ​​of cover plate), blows downward along the conical cavity wall, and peels off the residue together with the cycloidal turbulence. The airflow carries the residue to the bottom discharge port 31. The suction airflow generated by impeller 8 draws the residue into the receiving pipe 7 through discharge port 31 and discharges it. The discharge port 31 is kept closed during the cleaning process to prevent the airflow from escaping directly from the bottom, ensuring that the airflow is fully swept along the wall before being concentrated and discharged from the discharge port 31. At the same time, it is also conducive to impeller 8 forming sufficient negative pressure suction force in receiving pipe 7. After cleaning, open the feeding hole 21 for inspection. If the residual amount is qualified, close the air inlet 22 (rotate the second opening and closing structure 41 to make its hole offset from the air inlet 22), and the equipment enters standby mode to wait for the next batch of soil samples to be processed. If the residual amount exceeds the standard (more is visible under visual conditions), repeat step S3 until it meets the standard.

[0036] The above steps S1, S2, and S3 are all automatically executed by the control system according to a preset timing sequence. The specific control signals output by the control system include: First control signal: Controls rotor 5 to rotate at a first speed n1 along a first rotation direction and maintains it for a first set duration; Pulse control signal: Before outputting the second control signal, control the drive mechanism 6 to perform at least one pulse action of rapid acceleration and rapid braking; Second control signal: Control rotor 5 to rotate at a second speed n2 along a second rotation direction and maintain for a second set duration.

[0037] In a preferred embodiment of the present invention, a sample container with at least two independent compartments is provided below the receiving pipe 7. After the soil sample is discharged from the discharge port 31, it falls evenly into each independent compartment of the sample container through the receiving pipe 7, so as to obtain parallel samples at one time. Since the soil samples were thoroughly mixed in the crushing and mixing chamber 11, the soil samples received by each chamber showed good consistency in composition and particle size distribution, which met the quality control requirements for parallel sample analysis.

[0038] The first opening and closing structure 4, the second opening and closing structure 41, and the third opening and closing structure 42 all operate by rotation. They can be equipped with micro drive motors (such as stepper motors) for driving. Each micro drive motor is electrically connected to the control system. The control system automatically controls the opening or closing of each opening and closing structure according to a preset timing sequence, achieving fully automatic operation without manual intervention.

[0039] For example, in step S1, the control system first controls the first opening and closing structure 4 to open the feeding hole 21, and automatically closes the feeding hole 21 after feeding is completed; in step S2, the control system controls the third opening and closing structure 42 to open the discharge port 31, and automatically closes the discharge port 31 after discharging is completed; in step S3, the control system controls the second opening and closing structure 41 to open the air inlet 22, and automatically closes the air inlet 22 after cleaning is completed.

[0040] The soil sample preparation equipment and its self-cleaning method provided by this invention can be widely used in soil sample pretreatment work in institutions such as environmental monitoring stations, agricultural technology extension centers, geological exploration units, and soil testing laboratories. It is particularly suitable for scenarios that require the processing of a large number of soil samples and have strict requirements for cross-contamination control between samples.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A soil sample preparation device, characterized by, include: The stator has a cone-shaped crushing and mixing chamber that is larger at the top and smaller at the bottom; A cover plate is provided at the upper end of the stator, and the cover plate is provided with a feeding hole and several air inlets; A base plate is disposed at the lower end of the stator, and a discharge port is provided on the base plate; A first opening and closing structure is provided on the cover plate for opening or closing the feeding hole; The second opening and closing structure is provided on the cover plate and is used to open or close the air inlet. The third opening and closing structure is provided on the base plate and is used to open or close the discharge port; A rotor is disposed within the crushing and mixing chamber, and the axis of the rotor is offset from the axis of the stator; A drive mechanism, connected to the rotor, is used to drive the rotor to rotate in a first rotation direction or a second rotation direction opposite to the first rotation direction, and to drive the rotor to revolve around the axis of the stator while rotating on its own axis. The first rotation direction is used to drive the rotor to crush and mix the soil sample in the crushing and mixing chamber; the second rotation direction is used to drive the rotor to form a periodic cycloidal turbulence in the airflow near the inner wall of the crushing and mixing chamber under the combined motion of revolution and rotation, so as to clean the inner wall of the crushing and mixing chamber. A receiving pipe is connected to the bottom of the base plate and communicates with the discharge port; An impeller is connected to the rotor via a shaft and disposed inside the receiving pipe. When the rotor rotates in the second rotation direction, the impeller is driven to rotate by the rotor via the shaft, generating a suction airflow in the receiving pipe, which draws the stripped residue into the receiving pipe through the discharge port and discharges it. The control system is electrically connected to the drive mechanism and is used to control the rotation direction, speed and start / stop actions of the drive mechanism according to a preset timing sequence.

2. The soil sample preparation equipment according to claim 1, characterized in that: The drive mechanism includes a first planetary gear mechanism disposed at the upper end of the stator and a second planetary gear mechanism disposed at the lower end of the stator. The first planetary gear mechanism and the second planetary gear mechanism have the same structure, each including an internal gear ring, at least one planetary gear and a sun gear. The upper end of the rotor is connected to the planetary gears of the first planetary gear mechanism, and the lower end of the rotor is connected to the planetary gears of the second planetary gear mechanism. The sun gear of the first planetary gear mechanism is used to connect to the output shaft of the drive motor as a power input.

3. The soil sample preparation equipment according to claim 2, characterized in that: The sun gear of the second planetary gear mechanism has a downwardly extending shaft fixedly connected to it, and the impeller is connected to the lower end of the shaft.

4. The soil sample preparation equipment according to claim 1, characterized in that: The air inlet is located at the edge of the cover plate and is opposite to the upper inner edge of the crushing and mixing chamber. The air entering through the air inlet is blown downward along the cavity wall of the crushing and mixing chamber.

5. The soil sample preparation equipment according to claim 1, characterized in that: The impeller includes a central block and multiple blades, and the upper end of each blade is hinged to the edge of the central block by a pin. During rotation, the blades are dispersed outward at their lower ends by centrifugal force, and the dispersion angle is proportional to the rotation speed. An upwardly protruding limiting block is provided on the outer side of the upper end of the blade, and the limiting block is used to limit the maximum angle when the blade rotates upward.

6. The soil sample preparation equipment according to claim 2, characterized in that: It also includes a counterweight, which is disposed on the second planetary gear mechanism, and the counterweight and the shaft are respectively located on opposite sides of the sun gear rotation center of the second planetary gear mechanism, in order to counteract the centrifugal inertial force generated by the revolution of the rotor.

7. A self-cleaning method using the soil sample preparation equipment according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Open the feeding hole, feed the soil sample into the crushing and mixing chamber through the feeding hole, close the feeding hole, drive the rotor to rotate in the first rotation direction, and crush and mix the soil sample. S2: Open the discharge port and drive the rotor to rotate continuously along the first rotation direction at a third speed n3. The rotor pushes the crushed and mixed soil sample toward the discharge port and discharges it. S3: Close the discharge port and drive the rotor to rotate in a second rotation direction opposite to the first rotation direction. Under the combined motion of revolution and rotation, the rotor causes the airflow near the inner wall of the stator to form a periodic cycloidal turbulence, which applies alternating shear force to the soil residues adhering to the inner wall of the stator, peels them off and discharges them with the airflow. In step S1, the rotor rotates along the first rotation direction at a first speed n1; in step S2, the third speed n3 is less than the first speed n1; in step S3, the rotor rotates along the second rotation direction at a second speed n2, and n2 ≥ 2 × n1, and the duration of the rotor rotating along the second rotation direction is 10 seconds to 30 seconds. Before driving the rotor to rotate in the second rotation direction, at least one pulse action of rapid acceleration and sudden braking is performed.

8. The self-cleaning method according to claim 7, characterized in that: In step S3, the feeding hole is kept closed, the air inlet is opened, and external air enters the stator through the air inlet and is blown down along the cavity wall from the upper end of the crushing and mixing chamber, participating in the airflow disturbance.

9. The self-cleaning method according to claim 7, characterized in that: Steps S1, S2, and S3 are automatically executed by the control system according to a preset timing sequence. The control system outputs a first control signal to control the rotor to rotate at the first speed n1 along the first rotation direction and maintain it for a first set time. The control system outputs a discharge control signal to control the rotor to rotate at the third speed n3 along the first rotation direction and maintain it for a third set time. The control system outputs a second control signal to control the rotor to rotate at the second speed n2 along the second rotation direction and maintain it for a second set duration. Before outputting the second control signal, the control system first outputs a pulse control signal to control the drive mechanism to perform at least one pulse action of rapid acceleration and rapid braking.

10. The self-cleaning method according to claim 7, characterized in that: In step S3, when the rotor rotates along the second rotation direction, it drives the impeller to rotate through the shaft. The impeller generates a suction airflow in the receiving pipe, which draws the stripped soil residue into the receiving pipe through the discharge port and discharges it.

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