Positioning connecting structure and hand-held transplanter

Abstract

The utility model relates to a kind of positioning connection structure and hand-held transplanter, including the hydraulic system connected with auxiliary beam and the gearbox assembly connected with main beam, and the hydraulic system is connected with gearbox assembly;It also includes positioning pin and locating hole, positioning pin is not less than two, and all are fixedly connected on the first docking plate of hydraulic system;Positioning hole is one-to-one adaptation with each positioning pin, and positioning hole is located on the second docking plate of gearbox assembly, and the second docking plate is attached with the first docking plate, and is connected by a plurality of first fastener.This utility model is accurately embedded by positioning pin and positioning hole, and forms rigid constraint in the interfacing surface of hydraulic system and gearbox assembly.This constraint can directly limit the relative torsion tendency of both under machine vibration, load impact from structural level, avoid that connecting part fastener is overloaded due to torsion.

Description

Technical Field

[0001] This utility model relates to the field of hand-held rice transplanter technology, specifically to a positioning connection structure and a hand-held rice transplanter. Background Technology

[0002] A hand-held rice transplanter is a small, lightweight agricultural machine specifically designed for rice transplanting. It can replace manual labor in transplanting seedlings, significantly improving the efficiency of paddy field operations. It is the mainstream transplanting equipment for small and medium-sized paddy fields and hilly and mountainous areas. Its core function is to accurately transplant the cultivated seedlings (mostly mat-shaped seedlings) into the paddy field, ensuring uniform row spacing, plant spacing, and planting depth. The specific operation process is divided into seedling picking, seedling transport, and transplanting: As the machine moves forward, the seedling separating mechanism (such as seedling separating claws) quantitatively grabs seedlings from the seedling box, avoiding seedling damage or omissions; through components such as seedling guide tubes, the grabbed seedlings are smoothly transported to the surface of the paddy field; the transplanting mechanism inserts the seedlings into the field soil at a preset depth, while simultaneously covering and fixing them with soil, ensuring that the seedlings are upright and their roots are in the soil.

[0003] Authorization Announcement No.: CN 203523304U, Application Date: October 22, 2013, Utility Model Name: Hand-held High-Efficiency Wide-Narrow Row Rice Transplanter. This utility model relates to a hand-held high-efficiency wide-narrow row rice transplanter, which includes an engine, a hydraulic contouring system, a main gearbox, a drive wheel, a seedling box, a seedling transfer box and seedling delivery mechanism, and a transplanting mechanism. This utility model meets the requirements for promoting high-efficiency rice cultivation technology that combines ultra-wide and narrow row spacing. The product has a simple and reasonable structure, good seedling tray versatility, and the transplanting mechanism is distributed according to narrow row spacing. The wide row size can be adjusted according to the agronomic requirements of different regions without affecting the overall machine performance. It is easy to adjust, has a wide range of applications, is lightweight, and operates reliably.

[0004] According to the description of this utility model in paragraph

[0016] , the prior art only briefly mentions the connection relationship between the hydraulic contour pump and the engine, and only describes the basic power transmission path of the engine driving the hydraulic contour pump and the gearbox through the belt. It does not provide any technical guidance on how to maintain a stable connection between the gearbox and the hydraulic contour pump, nor does it provide any technical guidance on how to avoid relative torsion between the gearbox and the hydraulic contour pump when the machine is subjected to vibration. Summary of the Invention

[0005] In view of the defects in the prior art, such as the relative torsion between the gearbox and the hydraulic system, the purpose of the present invention is to provide a positioning connection structure and a hand-held rice transplanter that limits the relative torsion between the hydraulic system and the gearbox, thereby ensuring a stable connection between the two.

[0006] The technical solution provided by this utility model is as follows: A positioning connection structure includes a hydraulic system connected to an auxiliary beam and a gearbox assembly connected to a main beam, wherein the hydraulic system is connected to the gearbox assembly; and further includes... Positioning pins, there are no fewer than two positioning pins, and all of them are fixedly connected to the first docking plate of the hydraulic system; Positioning holes, which are adapted to each positioning pin, are provided on the second docking plate of the gearbox assembly. The second docking plate is in contact with the first docking plate and is connected by a number of first fasteners. The locating pin engages with the locating hole to restrict relative torsion between the hydraulic system and the gearbox assembly.

[0007] Furthermore, the positioning pin includes a first positioning pin and a second positioning pin, with the first positioning pin and the second positioning pin arranged with a gap between them; the first positioning pin is approximately located in the middle region of the first mating plate.

[0008] Furthermore, the size of the first locating pin is larger than the size of the second locating pin.

[0009] Furthermore, there are no fewer than three first fasteners, and they are located in the corner area of ​​the first mating plate. The second mating plate of the gearbox assembly is provided with limiting holes that are adapted to each of the first fasteners. The second locating pin is located on the line connecting the first locating pin and one of the first fasteners.

[0010] Furthermore, when three of the first fasteners are provided, the first fasteners form a triangular structure, and the lengths of the lines connecting the center of the first locating pin to the center of each first fastener are approximately equal.

[0011] Furthermore, the cross-section of the second locating pin is circular or a regular polygon.

[0012] Furthermore, the fastener is a bolt, and the limiting hole has an internal thread adapted to the bolt.

[0013] Furthermore, the gearbox assembly also includes a gearbox body, and an adapter plate is integrally formed or welded to the end of the main beam. The mating surface of the adapter plate is tightly fitted with the end face of the gearbox body, and the two are connected by a second fastener.

[0014] Furthermore, along the height direction of the main beam, the gearbox body is integrally formed with several extension plates, which extend upward to the top of the gearbox body and downward to the bottom of the gearbox body, respectively. The main beam is fitted with reinforcing connecting plates on both sides, and the reinforcing connecting plates are connected to the fixing plates by a second fastener.

[0015] A hand-held rice transplanter includes an engine, wheels, a seedling rack, a transplanting mechanism, and a positioning and connecting structure.

[0016] Compared with the prior art, the technical solution provided by this utility model has the following advantages: (1) This utility model provides at least two locating pins on the first docking plate of the hydraulic system. The core of this design is to utilize the multi-point positioning principle to form a rigid constraint on the docking surface of the hydraulic system and the gearbox assembly by precisely engaging the locating pins with the corresponding locating holes on the second docking plate of the gearbox assembly. This constraint can directly limit the relative torsional tendency of the two under machine vibration and load impact from a structural perspective, avoiding overload of the fasteners at the connection due to torsion. Compared with the existing technology which lacks a targeted anti-torsion design, this structure can effectively resolve the failure risks such as connection loosening and fastener breakage caused by relative torsion, ultimately ensuring the long-term stability of the connection between the hydraulic system and the gearbox assembly, and providing key structural support for the reliable operation of the hand-held rice transplanter in the complex working environment of paddy fields.

[0017] (2) The hydraulic system and gearbox assembly of this utility model are rigidly connected through the first fastener, and at the same time, with the anti-torsion limiting effect of the positioning pin, a dual guarantee system of fastening connection + structural anti-torsion is formed, which improves the reliability of connection from the two dimensions of mechanical constraint and structural limitation. When there are three first fasteners, the center line of their connection forms a triangular structure. As the geometrically most stable shape, the triangle can evenly distribute the vibration load and torsional moment borne by the mating surface to the three fastening points, avoiding premature failure of a single fastener due to local stress concentration. At the same time, the length of the line connecting the center of the first positioning pin to the center of each first fastener is designed to be approximately equal. This layout can ensure that the constraint effect of the positioning pin on the three fasteners is symmetrically distributed, making it more adaptable to the complex working conditions such as high-frequency vibration and instantaneous impact when the hand-held rice transplanter is working in the paddy field. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a hand-held rice transplanter in one embodiment of this application; Figure 2 This is a schematic diagram of the hydraulic system structure in one embodiment of this application; Figure 3 This is a schematic diagram showing the connection between the hydraulic system and the gearbox assembly in one embodiment of this application; Figure 4 This is a schematic diagram of the second docking plate structure of the gearbox assembly in one embodiment of this application; Figure 5 This is a schematic diagram showing the position of the locating pin in one embodiment of this application; Figure 6 This is a schematic diagram of the first locating pin structure in one embodiment of this application; Figure 7 This is a schematic diagram of the connection between the main beam and the gearbox assembly in one embodiment of this application; Figure 8 This is a schematic diagram showing the positions of the adapter plate and the reinforcing connecting plate in one embodiment of this application.

[0019] Explanation of the labels in the diagram: Hydraulic system 1; First docking plate 10; First locating pin 11; Second locating pin 12; First fastener 13; Second docking plate 20; limiting hole 21; gearbox body 22; extension plate 23; Auxiliary beam 3; Main beam 4; transition plate 41; reinforcing connecting plate 42; 5 wheels for walking; 6. Prepare seedling racks; Rice transplanting mechanism 7. Detailed Implementation

[0020] To further understand the content of this utility model, a detailed description of this utility model will be provided in conjunction with the accompanying drawings and embodiments.

[0021] The structures, proportions, and sizes illustrated in the accompanying drawings are solely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0022] A hand-held rice transplanter is a small agricultural machine used for rice planting. It is mainly operated by hand to realize the mechanized transplanting of rice seedlings. Its core function is to replace traditional manual transplanting, improve planting efficiency, and ensure the quality of transplanting.

[0023] The hand-held rice transplanter is compact, equipped with a handle and wheels, requiring the operator to walk alongside to control direction and speed. It is suitable for small paddy fields or irregular plots, offering greater flexibility than large, ride-on rice transplanters. The hand-held transplanter features a built-in seedling support platform, and its seedling-separating mechanism precisely inserts seedlings into the soil at set plant and row spacings. The transplanting depth and density are adjustable, ensuring seedling uprightness and survival rate, and minimizing the variability caused by manual operation.

[0024] Hand-held rice transplanters are mostly driven by small gasoline or diesel engines, including hydraulic systems (for controlling seedling separation and lifting) and transmission systems. They have a relatively simple structure and low maintenance costs, making them one of the mainstream machines for rice cultivation among small and medium-sized farmers.

[0025] In the existing technology, the gearbox assembly and hydraulic system of the hand-held rice transplanter rely solely on bolt connections, without any dedicated anti-torsion or reinforced load-bearing auxiliary structures. This makes the bolts the only load-bearing components. Once the bolts exceed their limit load capacity due to shear or tensile forces, the hydraulic system will separate from the gearbox assembly, directly causing hydraulic system failure.

[0026] Example 1 This application discloses a positioning connection structure applicable to a hand-held rice transplanter, specifically applicable to a hydraulic system 1 and a gearbox assembly. The hydraulic system 1 is detachably connected to an auxiliary beam 3, and the gearbox assembly is detachably connected to a main beam 4. Furthermore, the first mating plate 10 of the hydraulic system 1 is abutted against the second mating plate 20 of the gearbox assembly, and the two mating plates are detachably connected by a first fastener 13.

[0027] The positioning connection structure mainly includes positioning pins and positioning holes. The positioning pins are fixedly connected to the first docking plate 10, and at least two are provided. It is worth noting that the positioning pins are preferably integrally formed with the first docking plate 10.

[0028] The positioning holes are matched with each positioning pin, and the positioning holes are located on the second mating plate 20. The positioning pins and positioning holes cooperate to restrict the relative torsion of the hydraulic system 1 and the gearbox assembly.

[0029] Specifically, the gearbox assembly is the core of the power distribution of the hand-held rice transplanter, responsible for transmitting engine power to the walking wheels and the transplanting mechanism. The hydraulic system is used to control the lifting and lowering of the transplanting mechanism and the precision of the seedling separation action. The two need to be stably connected to ensure the synchronization of power transmission and action control. This application avoids the risk of hydraulic system 1 failing due to unstable connection caused by relative torsion between the gearbox assembly and the hydraulic system, which would ultimately lead to disordered transplanting rhythm and jerky action.

[0030] In addition, the auxiliary beam 3 is mounted on top of the main beam 4, and the two form a stable combined support system through a pre-designed connection structure. The double-layer beam frame design not only significantly improves the overall structural support strength and effectively resists the load generated during machine operation, but also actively shares some of the tensile or compressive forces borne by the main beam 4 during the movement, start-up, and vibration of the hand-held rice transplanter in the field.

[0031] The hydraulic system 1 is detachably connected to the auxiliary beam 3, and the gearbox assembly is detachably connected to the main beam 4. This double-beam design avoids structural fatigue caused by long-term overload on a single beam, thereby extending the service life of the positioning connection structure and even the entire machine.

[0032] The importance of the positioning pin is described in detail below: In existing technologies, even with a double beam setup (auxiliary beam 3 and main beam 4), the connection between the gearbox assembly and the hydraulic system 1 still carries the risk of loosening or even separation if positioning pins are not provided. The core operating environment of the hand-held rice transplanter is paddy field, which is characterized by dampness, numerous obstacles, and variable operating conditions. The surface layer of the field generally contains a 5-20 cm deep layer of thin mud, and the lower layer may contain hard soil, gravel, or weed roots, which can easily cause the machine to slip, get stuck, or have its walking parts entangled in debris, leading to severe vibrations or instantaneous impacts on the machine.

[0033] Therefore, as the main load-bearing structure, the main beam 4 will be the first to bear the vibration and impact or deform. Since the auxiliary beam 3 is rigidly connected to the main beam 4 and the hydraulic system 1, the force on the main beam 4 will be synchronously transmitted to the auxiliary beam 3, and then the auxiliary beam 3 will directly act on the hydraulic system 1.

[0034] The key point is that the weight of the hydraulic system 1 is much lighter than that of the gearbox assembly, and the two have a large difference in mass. When subjected to vibration or impact loads in the same direction, the inertial response speed of the hydraulic system 1 will be faster than that of the gearbox assembly, causing a relative torsional tendency at the connection between the two.

[0035] This relative torsion directly acts on the first fastener 13 at the connection point, causing it to continuously bear additional shear force and torque. Over time, the fastener is prone to loosening, stripping, or even breaking, ultimately leading to the failure of the connection between the hydraulic system 1 and the gearbox assembly.

[0036] Taking a limiting hole 21 with a diameter of φ9 and the first fastener 13 (bolt) with a diameter of φ8 as an example: the allowable installation deviation rotation angle range after the hydraulic system 1 and the gearbox assembly are assembled is -0.61° to 0.61°, with a total rotation range of 1.22°. Under these assembly conditions, the diameter of the threaded section of the bolt that bears shear force is φ6.826, and its maximum shear stress is 384MPa.

[0037] If the relative torsional angle between the hydraulic system 1 and the gearbox assembly exceeds the allowable range of -0.61° to 0.61°, or if the shear stress borne by the first fastener 13 (bolt) exceeds 384 MPa, it will directly cause the bolt to break.

[0038] After the bolt breaks, it will not only cause the connection between the gearbox assembly and the hydraulic system 1 to loosen or even separate, thus causing the hydraulic system 1 to fail, but it will also transfer the load to the connection between the main beam 4 and the gearbox assembly, causing the connection to bear additional load, and ultimately creating the risk of loosening and deformation of the connection between the main beam 4 and the gearbox assembly.

[0039] Therefore, this application provides at least two locating pins on the first docking plate 10 of the hydraulic system 1. Through the precise cooperation between the locating pins and the locating holes on the second docking plate 20, the relative torsion between the hydraulic system 1 and the gearbox assembly is structurally restricted, thus solving the connection failure problem caused by torsion in the prior art.

[0040] Specifically, the positioning pins include a first positioning pin 11 and a second positioning pin 12, which are arranged with a gap to cover the key stress area of ​​the docking plate. The first positioning pin 11 is located approximately in the middle area of ​​the first docking plate 10 and can serve as the core positioning reference, giving priority to bearing the main torsional constraint load.

[0041] To further enhance connection stability, the corner area of ​​the first docking plate 10 is provided with at least three first fasteners 13, preferably bolts, and the second docking plate 20 of the gearbox assembly is provided with corresponding limiting holes 21 that are adapted to each of the first fasteners 13.

[0042] Through the above design, a dual-protection structure is formed, consisting of a locating pin to prevent torsion and a first fastener to reinforce the connection. It is worth noting that when three first fasteners 13 are provided, the center line connecting all the first fasteners 13 forms a triangular structure. Triangles possess geometric stability, effectively distributing the force on the mating surfaces and avoiding localized stress concentration.

[0043] Meanwhile, the lengths of the lines connecting the center of the first locating pin 11 to the centers of each of the first fasteners 13 are approximately equal, ensuring that the constraint effect of the first locating pin 11 on each of the first fasteners 13 is uniform, further enhancing the overall connection's resistance to deformation. In addition, the second locating pin 12 is located on the line connecting the first locating pin 11 and one of the first fasteners 13, which can specifically supplement the torsional constraint in this area, forming a synergistic limiting effect with the first locating pin 11.

[0044] Considering the functional differences of different locating pins, the size of the first locating pin 11 is larger than that of the second locating pin 12: the larger size of the first locating pin 11 can enhance its structural strength as the core reference and better resist the main torsional force; the smaller size of the second locating pin 12 can reduce the processing difficulty and assembly accuracy requirements of the mating plate while meeting the auxiliary limiting requirements.

[0045] In terms of cross-sectional shape, the second locating pin 12 is preferably circular or regular polygonal. A circular cross-section facilitates fine-tuning of the angle during assembly, while a regular polygonal cross-section can further improve the anti-torsion effect. The choice can be made flexibly according to the precision requirements of the actual working scenario.

[0046] Taking the first fastener 13 with a diameter of φ8 as an example, the second locating pin 12 is also selected with a diameter of φ8, but its surface is smooth and its load-bearing capacity is directly related to its own hardness grade.

[0047] HRC is a commonly used scale in the Rockwell Hardness testing system, mainly used to measure the hardness of metallic materials, especially suitable for harder materials such as quenched steel.

[0048] When the hardness of the second locating pin 12 is controlled within the range of 37 to 44 HRC, the maximum shear stress it can withstand is 650 MPa. Compared with the first fastener 13, which can withstand a shear stress of 384 MPa, its load-bearing capacity is increased by 68.5%.

[0049] If the hardness of the second locating pin 12 is further increased to 45-50 HRC, the maximum shear stress it can withstand will increase to 970 MPa, at which point the load-bearing capacity will increase by 152.5% compared to the above benchmark.

[0050] This data shows that by reasonably increasing the hardness level of the positioning pin, its shear resistance can be significantly enhanced, thereby improving the failure resistance of the connection structure between the hydraulic system 1 and the gearbox assembly, better coping with the additional loads caused by vibration and impact when the hand-held rice transplanter is operating in the field, and providing more reliable structural support for the stable connection between the two.

[0051] Example 2 Based on Embodiment 1, this application strengthens the positioning connection between the main beam 4 and the gearbox assembly.

[0052] The gearbox assembly also includes a gearbox body 22, and an adapter plate 41 is integrally formed or welded to the end of the main beam 4. The mating surface of the adapter plate 41 is fully adapted to and tightly fitted with the end face of the gearbox body 22, and the two are detachably fixedly connected by a second fastener to ensure the force transmission stability of the connection part.

[0053] Along the height direction of the main beam 4, the gearbox body 22 is integrally formed with several extension plates 23. The extension plates 23 extend upward beyond the top of the gearbox body 22 and downward beyond the bottom of the gearbox body 22, respectively. Among them, a pair of extension plates 23 located at the top of the gearbox body 22 are symmetrically arranged, and a pair of extension plates 23 located at the bottom of the gearbox body 22 are also symmetrically arranged. The symmetrical layout can make the lateral force more even.

[0054] The main beam 4 has reinforcing connecting plates 42 snapped onto both sides. The extension plate 23 is connected to the reinforcing connecting plate 42 one by one by a second fastener. The second fastener is preferably a bolt. The bolt connection has both connection strength and ease of assembly and disassembly.

[0055] It is worth noting that the middle part of the reinforcing connecting plate 42 protrudes along the side away from the main beam to form a groove structure. The size of this groove matches the side profile of the main beam 4, which is used to precisely engage the main beam 4. During assembly, the reinforcing connecting plate 42 is first engaged and positioned with the main beam 4 through the groove, and then bolted to the extension plate 23. Through the dual cooperation of engagement and bolt fixing, the lateral support rigidity of the connection between the main beam 4 and the gearbox body 22 is further improved, preventing the connection from loosening.

[0056] The main beam 4 and the gearbox body 22 are fixed together by the end face of the adapter plate 41. Combined with the lateral double reinforcement of the extension plate 23 and the reinforcing connecting plate 42, a multi-directional, high-strength connection structure is formed, which effectively disperses the stress on the connection parts and greatly improves the overall stability and deformation resistance of the connection.

[0057] Example 3 Based on Embodiments 1 and 2, the hand-held rice transplanter of this application, in addition to including core working components such as an engine, walking wheels 5, seedling rack 6 and transplanting mechanism 7, also integrates the positioning and connection structure described in Embodiment 1 or 2.

[0058] The positioning connection structure is specifically applied to the power transmission system of a hand-held rice transplanter to achieve precise docking and positioning between the hydraulic system and the gearbox components. By using the cooperation of positioning pins and positioning holes to restrict relative torsion, and combined with the solid connection of multiple sets of fasteners, it ensures efficient and stable power transmission between the hydraulic system and the gearbox components.

[0059] Meanwhile, the multi-directional reinforced connection design between the main beam and the gearbox body in the positioning connection structure provides reliable structural support for the hand-held rice transplanter in complex working conditions in the field, reduces the problem of loosening of the connection caused by vibration and load changes, and improves the overall stability and service life of the machine.

[0060] The working principle of a hand-held rice transplanter is as follows: First, after the engine starts, mechanical energy is transmitted to the input end of the gearbox assembly through the output shaft. The engine speed can be adjusted by the throttle lever according to the work requirements, so as to achieve on-demand control of power output.

[0061] Secondly, as the core of power distribution and adjustment, the gearbox uses an internal gear set to switch between different speed ratios through a shifting mechanism. On the one hand, it transmits the adjusted power to the walking wheels 5, driving the machine body to move at a constant speed in the field. On the other hand, through the precise positioning of the first docking plate and the second docking plate in the aforementioned positioning connection structure (the positioning pin and the positioning hole cooperate to restrict relative torsion), it ensures that the power is transmitted to the hydraulic system without deviation.

[0062] After receiving power, the hydraulic system converts mechanical energy into hydraulic energy through a hydraulic pump. The hydraulic oil circulates in a closed oil circuit, and the hydraulic valve group precisely controls the pressure, flow and direction of the oil, which respectively drive the lifting and lowering of the transplanting mechanism 7 (to adapt to different field heights), the reciprocating transplanting action of the transplanting arm (to control the transplanting density), and the flexible steering of the steering mechanism, so as to realize multi-dimensional adjustment of the machine's operating posture.

[0063] During the coordinated operation of the engine, transmission components, and hydraulic system 1, the stable connection of the positioning and connection structure avoids vibration loss during power transmission. The power output of the engine, the speed ratio adjustment of the transmission, and the motion control of the hydraulic system 1 form a closed loop. For example, when the machine body encounters a field ridge and the transplanting mechanism needs to be raised, the driver operates the hydraulic handle, and the hydraulic system responds quickly to adjust the height of the transplanting mechanism. At the same time, the transmission maintains a stable speed of the walking wheels, ensuring that the transplanting operation is continuous and uninterrupted, thus jointly ensuring the efficiency and quality of the hand-held rice transplanter under complex field conditions.

[0064] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A positioning connection structure, comprising a hydraulic system (1) connected to an auxiliary beam (3) and a gearbox assembly connected to a main beam (4), wherein the hydraulic system (1) is connected to the gearbox assembly; characterized in that: It also includes, Positioning pins, there are no fewer than two positioning pins, and both are fixedly connected to the first docking plate (10) of the hydraulic system (1); Positioning holes are adapted to each positioning pin. The positioning holes are located on the second docking plate (20) of the gearbox assembly. The second docking plate (20) is in contact with the first docking plate (10) and connected by a number of first fasteners (13). The positioning pin engages with the positioning hole to restrict relative torsion between the hydraulic system (1) and the gearbox assembly.

2. The positioning connection structure according to claim 1, characterized in that: The positioning pin includes a first positioning pin (11) and a second positioning pin (12), with the first positioning pin (11) and the second positioning pin (12) arranged with a gap; the first positioning pin (11) is located approximately in the middle region of the first mating plate (10).

3. The positioning connection structure according to claim 2, characterized in that: The size of the first locating pin (11) is larger than the size of the second locating pin (12).

4. The positioning connection structure according to claim 2, characterized in that: There are at least three first fasteners (13), and they are located in the corner area of ​​the first docking plate (10). The second docking plate (20) of the gearbox assembly is provided with limiting holes (21) that are adapted to each of the first fasteners (13). The second positioning pin (12) is located on the line connecting the first positioning pin (11) and one of the first fasteners (13).

5. A positioning connection structure according to claim 2, characterized in that: When three of the first fasteners (13) are provided, the first fasteners (13) form a triangular structure, and the length of the line connecting the center of the first positioning pin (11) to the center of each first fastener (13) is approximately equal.

6. A positioning connection structure according to claim 2, characterized in that: The second locating pin (12) has a circular or regular polygonal cross section.

7. The positioning connection structure according to claim 1, characterized in that: The fastener (13) is a bolt, and the limiting hole (21) has an internal thread adapted to the bolt.

8. The positioning connection structure according to claim 1, characterized in that: The gearbox assembly also includes a gearbox body (22), and an adapter plate (41) is integrally formed or welded to the end of the main beam (4). The mating surface of the adapter plate (41) is tightly fitted to the end face of the gearbox body (22), and the two are connected by a second fastener.

9. A positioning connection structure according to claim 8, characterized in that: Along the height direction of the main beam (4), the gearbox body (22) is integrally formed with several extension plates (23), the extension plates (23) extending upward out of the top of the gearbox body (22) and downward out of the bottom of the gearbox body (22); The main beam (4) is fitted with reinforcing connecting plates (42) on both sides, and the reinforcing connecting plates (23) and the fixing plates (42) are connected by a second fastener.

10. A hand-held rice transplanter, comprising an engine, wheels (5), a seedling rack (6), and a transplanting mechanism (7), characterized in that, It also includes the positioning connection structure as described in any one of claims 1-9.

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