A drive gear shaft for a tray conveying system

Abstract

This invention discloses a transmission gear shaft for a planting tray conveying system, belonging to the technical field of transportation equipment. It aims to solve the problems of noise generated by gear disk displacement under force and gear disk corrosion caused by condensation. The transmission gear shaft includes a central shaft, a first spacer, a second spacer, a gear disk, and a hollow shaft. The first and second spacers are fixed to the central shaft, which can limit the displacement of the gear disk under force and reduce noise. The first spacer, the second spacer, and the through holes on the gear disk are coaxial. The clearance fit between the hollow shaft and the central shaft forms an air duct. After the air duct is connected to a fan, it can accelerate the evaporation of condensation on the surface of the central shaft, prevent corrosion at the connection between the gear disk and the central shaft, extend the service life of components, and ensure the stable operation of the planting tray conveying system.

Description

Technical Field

[0001] This invention belongs to the field of transportation equipment technology, and more specifically, relates to a transmission gear shaft for a planting tray conveying system, particularly for spiral towers. Background Technology

[0002] One of the main challenges in forage production at present is the difficulty in increasing forage yield. The primary reason is the increasing pressure on land resources. Increased production of grains, oilseeds, and legumes has placed enormous pressure on land resources for forage production. To meet the growing demand for fresh, high-quality forage, the spiral production method can produce forage including corn, barley, oats, sorghum, rye, alfalfa, and triticale. In summary, seven-day forage production, as a production model that can sustain continuous year-round production, produce high-quality fresh forage, and has high land resource utilization efficiency, can support regional livestock farms to achieve partial self-sufficiency in high-quality feed, and has high practical significance and economic value. In modern agricultural planting, especially in vertical farming models, the planting tray conveyor system is the core equipment for achieving automated transfer of planting trays and improving space utilization. The transmission gear shaft, as a key transmission component of the conveyor system, directly affects the working efficiency and service life of the entire conveyor system due to its operational stability.

[0003] To address the aforementioned issues, a search revealed, for example, that patent document CN202110644632.1 discloses a plant production system. This system includes a conveying section and a production tower body with an outlet and an inlet. The production tower body contains a support section extending in a spiral shape along the vertical direction, and the support section forms a multi-layered structure on the production tower body. The conveying section is located on the support section and is movably positioned thereto, used to transport cultivation trays. Controlling the speed of the conveying section allows cultivation trays in different layers of the production tower body to be at different growth stages. Furthermore, it can precisely regulate environmental parameters such as water and carbon dioxide according to different growth stages.

[0004] For example, patent document CN114620396A discloses a planting tray conveying system for a spiral tower, which includes a track forming a multi-layered spiral tower body with a defined path; a trolley drive assembly including a chain guide rail, a chain, and a chain drive component; the chain guide rail is disposed inside the track and aligned with the track's extension direction; the chain is disposed within the chain guide rail; the chain drive component is used to control the movement of the chain; and a trolley disposed on the track, including a connecting plate and a support plate; one side of the connecting plate is detachably connected to the chain, and the other side is fixedly connected to the support plate.

[0005] However, regarding the structure disclosed in the aforementioned patent, the weight is relatively light when the planting tray first enters the spiral tower. As the crops in the planting tray grow, the overall weight increases linearly, resulting in a greater force on the chain connecting the trolley, which causes significant noise during operation. At the same time, since the current spiral tower is used to produce different crops, when the crops on both sides are different, the connecting plate deforms under pressure, further exacerbating the noise generation. Summary of the Invention

[0006] 1. The problem to be solved In view of at least some of the problems existing in the prior art, the present invention proposes a transmission gear shaft for a planting tray conveying system, thereby reducing noise generation.

[0007] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: The present invention provides a transmission gear shaft for a planting tray conveying system, comprising: A central shaft has a first spacer and a second spacer evenly spaced on it, and a gear disk is placed between the first spacer and the second spacer. When the gear disk is subjected to force (such as the pressure transmitted by the transport trolley through the chain), it will cause the gear disk to displace downward along the central shaft, causing the chain and gear disk to deviate from their contact, which can easily generate noise. The first spacer and the second spacer are both fixed to the central shaft. The first spacer and the second spacer can reduce the displacement of the gear disk, thereby reducing the generation of noise.

[0008] In one possible embodiment of the present invention, at least one first through hole is provided on the first spacer along the length direction of the central shaft, at least one second through hole is provided on the second spacer along the length direction of the central shaft, and a through hole is provided on the gear disk coaxial with the first through hole and the second through hole; The device includes several hollow shafts fitted onto the central shaft body. The two ends of each hollow shaft are respectively fitted onto the first spacer and the second spacer, and there is a gap between the hollow shaft and the central shaft body. The through hole, the first through hole, the second through hole, and the gap constitute an air duct. The air duct can be connected to a fan. Through the downward exhaust action of the fan, the evaporation rate of condensate on the surface of the central shaft body can be accelerated, thereby preventing condensate from falling into the connection between the gear disk and the central shaft body and causing corrosion of the gear disk.

[0009] In addition, the hollow shaft is sleeved on the outside of the central shaft body, forming a relatively closed accommodating space between the two, which can serve as a carrier for the layout of the air duct; at the same time, the axial end faces of the adjacent hollow shafts abut against the two end faces of the gear disk respectively, which can form a bidirectional axial limiting support for the gear disk, effectively suppressing the axial displacement of the gear disk after being loaded, and ensuring the stability of the gear disk assembly position.

[0010] In one possible embodiment of the present invention, the cross-section of the central shaft is solid or hollow, and the first and second spacers are fixed to the central shaft by flat keys and screws to ensure the connection stability between the spacers and the central shaft and to prevent the spacers from displacing relative to the central shaft.

[0011] In one possible embodiment of the present invention, the hollow shaft has at least one third through hole along its circumference. The third through hole is connected to the air duct. The third through hole corresponds to the level of the spiral tower, that is, there is at least one third through hole in each level. The oxygen produced by the crop can be discharged in time through the third through hole to ensure the healthy growth of the crop. At the same time, the number of third through holes should not be too many to avoid reducing the pressure in the air duct. The upper limit is 4.

[0012] In one possible embodiment of the present invention, 1-2 third through holes are evenly distributed circumferentially in each layer, with a hole diameter of φ10-25mm and a downward inclination angle of 45°-60° between the hole axis and the radial direction. A filter screen is installed at the hole opening. This structural design can ensure ventilation efficiency and prevent debris from falling into the through holes through the downward inclination angle. The filter screen can further block dust, crop debris, etc. from entering the air duct and prevent the air duct from becoming blocked.

[0013] In one possible embodiment of the present invention, the single-hole wind speed of the third through hole is controlled at 0.8-1.5 m / s, and the total exhaust volume of each spiral tower is ≥0.02 m³ / (min·m²); the friction resistance of the hollow shaft air duct is ≤50 Pa, and the local resistance of the third through hole is ≤30 Pa; the airflow in the air duct can keep the temperature difference between spiral tower layers ≤2℃ and control the humidity of the space at 60%-85%.

[0014] In one possible embodiment of the present invention, the inner wall of the third through hole is smooth, and the third through holes of adjacent layers are circumferentially offset by 15°-30° to improve the uniformity of ventilation between layers and avoid ventilation dead zones.

[0015] In one possible embodiment of the present invention, the surface of the central shaft is galvanized, making it smooth. Water vapor in the spiral tower space is less likely to condense on the surface of the central shaft. Even if it does condense into small water droplets, the droplets are less likely to fall into the mating area between the gear disc and the central shaft under the action of the air duct's suction force, thus avoiding water vapor corrosion.

[0016] In one possible embodiment of the present invention, the number of the first through hole and the second through hole are both 2-8, and they are evenly distributed along the circumference of the central axis to ensure uniform airflow distribution in the duct and improve the condensate evaporation efficiency.

[0017] In one possible embodiment of the present invention, the two ends of the hollow shaft are respectively adapted to be connected to the outer wall of the first spacer and the outer wall of the second spacer, thereby improving the sealing performance of the connection between the hollow shaft and the spacer, preventing air leakage in the air duct, and ensuring the negative pressure suction force in the air duct.

[0018] In one possible embodiment of the present invention, the center distance of the third through hole is 100-150mm from each layer of planting trays to ensure that the airflow evenly covers the root zone, avoids vortex dead zones, and at the same time ensures that the ventilation airflow does not directly impact the crop and affect crop growth.

[0019] In one possible embodiment of the present invention, the gap between the hollow shaft and the central shaft forms a coaxial circular air duct with a gap of 70-100mm, which guides the airflow for directional delivery, avoids interlayer air leakage in the spiral tower, and improves the targeting and efficiency of ventilation.

[0020] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The transmission gear shaft of the planting tray conveying system of the present invention forms a double axial limiting structure by setting a fixed first spacer and a second spacer on the central shaft body and using the axial end faces of adjacent hollow shafts to abut against both sides of the gear disk. This can effectively suppress the axial displacement of the gear disk after being loaded, ensure the precise meshing of the chain and the gear disk, significantly reduce the running noise, reduce the wear of the gear disk and the chain, and extend the service life of the transmission components. (2) The transmission gear shaft of the planting tray conveying system of the present invention forms an air duct through the first through hole, the second through hole, the gear disk through hole and the gap between the hollow shaft and the central shaft. With the downward exhaust action of the fan, the evaporation rate of the condensate on the surface of the central shaft can be accelerated. At the same time, the galvanized treatment of the surface of the central shaft reduces water vapor condensation. The double protection prevents condensate from falling into the connection between the gear disk and the central shaft, solves the problem of gear disk corrosion from the root, and ensures the transmission fit accuracy. (3) The transmission gear shaft of the planting tray conveying system of the present invention has a third through hole on the hollow shaft that corresponds to the spiral tower level, which can timely discharge the oxygen generated by the crops at each level and ensure the healthy growth of the crops; and the number, diameter, inclination angle and distribution of the third through hole have been optimized to ensure ventilation efficiency, avoid air duct pressure loss, achieve uniform ventilation between layers, avoid vortex dead zones, and improve the comfort of the planting environment. (4) The transmission gear shaft of the planting tray conveying system of the present invention has a simple and reliable connection method for each component. The first and second spacers are fixed by flat keys and screws. The hollow shaft is matched with the spacers and is easy to assemble. The air duct adopts a coaxial circular design to guide the airflow for directional delivery, avoid interlayer air leakage, and has a compact overall structure. It does not occupy extra planting space and has strong adaptability. Attached Figure Description

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0022] Figure 1 This is a schematic diagram of the transmission gear shaft of the planting tray conveying system of the present invention; Figure 2 This is another schematic diagram of the transmission gear shaft of the planting tray conveying system of the present invention; Figure 3 This is a front view of the transmission gear shaft of the planting tray conveying system of the present invention; Figure 4 This is a partially enlarged schematic diagram of the transmission gear shaft of the planting tray conveying system of the present invention; Figure 5 This is a schematic diagram of the gear disk structure of the transmission gear shaft of the planting tray conveying system of the present invention; Figure 6 This is another schematic diagram of the gear disk structure of the transmission gear shaft of the planting tray conveying system of the present invention; Figure 7 This is a diagram showing the usage state of the transmission gear shaft in the planting tray conveying system of the present invention.

[0023] Explanation of reference numerals in the attached figures: 1. Central shaft; 2. First spacer; 3. Second spacer; 4. Gear disc; 5. First through hole; 6. Second through hole; 7. Through hole; 8. Hollow shaft; 9. Clearance; 10. Third through hole; 11. Filter screen; 12. Flat key; 13. Screw. Detailed Implementation

[0024] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings.

[0025] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the 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 invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] The present invention will be further described below with reference to specific embodiments.

[0027] Existing planting tray conveyor systems generally suffer from two major technical defects in practical applications: First, the gear disc lacks an effective axial limiting structure when mounted on the central shaft. When the transport trolley transmits pressure to the gear disc via the chain, the gear disc is prone to axial displacement along the central shaft, causing deviations in the meshing position between the chain and the gear disc. This not only generates significant operating noise but also accelerates wear on the gear disc and chain, shortening the service life of the transmission components. Second, in vertical planting environments, especially within spiral tower planting structures, the high humidity causes moisture to condense on the surface of the central shaft of the transmission gear disc, forming water droplets. These condensed water droplets easily fall into the connection between the gear disc and the central shaft, causing gear disc corrosion, compromising transmission precision, further reducing transmission efficiency, and even leading to transmission failures, severely affecting the stable operation of the planting tray conveyor system.

[0028] Existing transmission gear shafts do not consider the ventilation requirements of the planting environment. In the spiral tower vertical planting mode, crops on each level of the planting tray produce oxygen. If this oxygen cannot be discharged in time, it will lead to excessively high local oxygen concentrations, affecting the normal respiration of the crops. At the same time, poor air circulation between layers may also cause uneven humidity distribution, increasing the risk of crop diseases. Although some ventilation structures are designed in existing technologies, they are mostly independent ventilation devices, which not only occupy additional space but are also prone to interference with transmission components, and it is difficult to achieve uniform ventilation between layers, resulting in low ventilation efficiency.

[0029] The spiral tower disclosed herein includes a tower frame, a planting tray conveying device, a fluid supply system, a lighting system, a ventilation system, and matching planting trays. The planting tray conveying system is installed and arranged based on the tower frame, while the fluid supply system, lighting system, and ventilation system can be selectively arranged on or around the tower frame according to actual needs.

[0030] like Figures 1 to 7 As shown, this embodiment provides a transmission gear shaft for a planting tray conveying system, including a central shaft 1. The central shaft 1 is either solid or hollow, and its surface is galvanized with a zinc coating thickness of 8-12 μm to ensure a smooth surface and reduce the probability of water vapor condensation. A first spacer 2 and a second spacer 3 are fixedly arranged at equal intervals on the central shaft 1. Both the first spacer 2 and the second spacer 3 are fixedly connected to the central shaft 1 by a flat key 12 and a screw 13. The flat key 12 is an A-type flat key, and the screw 13 is an internal hexagonal head screw to ensure a firm connection and prevent the first spacer 2 and the second spacer 3 from rotating or shifting relative to the central shaft 1.

[0031] Furthermore, the aforementioned central shaft is made of 45# steel to ensure sufficient strength and wear resistance. For example... Figure 3 and Figure 4As shown, the first spacer 2 and the second spacer 3 are both annular structures and are fixed to the central shaft 1 by an interference fit. During assembly, the first spacer 2 and the second spacer 3 are fitted into the preset position of the central shaft 1 by thermal expansion and contraction to ensure that they are firmly fixed and there is no relative displacement.

[0032] A gear disk 4 is provided between the first spacer 2 and the second spacer 3. The gear disk 4 is clearance-fitted with the central shaft 1, and its two end faces abut against the axial end faces of the adjacent hollow shaft 8 respectively. Through the synergistic action of the first spacer 2, the second spacer 3 and the hollow shaft 8, the gear disk 4 is bidirectionally axially limited, effectively suppressing the axial displacement of the gear disk 4 after being loaded.

[0033] In this embodiment, as Figure 5 and Figure 6 As shown, the first spacer 2 has eight first through holes 5 along the length of the central shaft 1, and the second spacer 3 has eight corresponding second through holes 6. The first through holes 5 and second through holes 6 are evenly distributed circumferentially along the central shaft 1, with a central angle of 45° between adjacent through holes. The gear disk 4 has eight through holes 7, which are coaxial with the first through holes 5 and second through holes 6 to ensure smooth airflow. Furthermore, as... Figure 6 As shown, weight reduction holes can be made on the gear disk 4.

[0034] The aforementioned first through hole 5 and second through hole 6 each number eight, evenly distributed around the central axis 1. The diameter of the first through hole 5 and the second through hole 6 is 50mm, which ensures the ventilation volume of the air duct without weakening the structural strength of the first spacer 2 and the second spacer 3. The diameter of the through hole 7 of the gear disk 4 is the same as that of the first through hole 5 and the second through hole 6, ensuring smooth airflow within the air duct.

[0035] In this embodiment, combined with Figure 3 and Figure 4 As shown, a number of hollow shafts 8 are fitted onto the central shaft body 1. The number of hollow shafts 8 corresponds to the planting levels of the spiral tower; in this embodiment, 18 hollow shafts 8 are provided. The two ends of the hollow shafts 8 are respectively fitted to the outer walls of the first spacer 2 and the second spacer 3, with a fitting gap of 0.02-0.05mm to ensure a tight seal. There is an 80mm gap 9 between the hollow shafts 8 and the central shaft body 1. This gap 9, together with the first through hole 5, the second through hole 6, and the through hole 7, forms a coaxial circular air duct. The top of the air duct is connected to an external fan, forming a downward exhaust structure.

[0036] exist Figure 4In it, each hollow shaft 8 is provided with 2 third through-holes 10. The 2 third through-holes 10 are evenly distributed along the circumferential direction of the hollow shaft 8, and the central angle is 180°. The aperture of the third through-hole 10 is φ20mm, the axis of the hole is inclined downward at an angle a of 50° with the radial direction, and a stainless steel filter screen 11 with an aperture of 0.5mm is arranged at the hole opening to prevent sundries from entering the air duct. The third through-holes 10 on adjacent layers of hollow shafts 8 are circumferentially offset by 20° to ensure the uniformity of ventilation between layers. At the same time, the center distance of the third through-holes 10 corresponding to the planting trays of each layer is 120mm, ensuring that the air flow can evenly cover the crop root zone and avoiding the generation of eddy current dead angles.

[0037] Furthermore, the hollow shaft 8 is made of stainless steel, and the outer diameters at both ends are adapted to the inner wall apertures of the first spacer sleeve 2 and the second spacer sleeve 3, and are sleeved in a clearance fit manner, which is convenient for assembly and disassembly. The clearance width between the hollow shaft 8 and the central shaft body 1 is 80mm. This clearance serves as a part of the air duct and can guide the air flow to flow along the surface of the central shaft body 1, quickly taking away the condensed water.

[0038] Through numerical simulation (such as CFD simulation) or small-scale model tests, the wind speed distribution and attenuation are verified, and the present invention meets the usage conditions. Through a large number of on-site experiments, it is obtained that the single-hole wind speed of the above-mentioned third through-hole 10 is controlled at 0.8 - 1.5m / s, and the total exhaust air volume per layer ≥ 0.02m³ / (min m²), meeting the oxygen demand of crops (root O2 concentration ≥ 18%); the frictional resistance along the hollow shaft air duct ≤ 50Pa, and the local resistance of the third through-hole ≤ 30Pa, adapting to high-power variable-frequency fans with low energy consumption; the air flow takes away the transpired water vapor and heat of the leaves at the same time, and the temperature difference between layers ≤ 2℃, and the humidity is controlled at 60% - 85%, adapting to crops such as crops, strawberries, and forages.

[0039] Therefore, on the basis of the above conditions, although local resistance will be generated when the air passes through the through-holes 7, the first through-holes 5 and the second through-holes 6, causing pressure loss, the total air volume at the lower end of the air duct will decrease, and the load of the variable-frequency fan will increase accordingly. However, the wind speed in the air duct is controlled in the medium wind speed range of 3m / s < v ≤ 8m / s. At this wind speed, the air flow turbulence is moderate, neither blocking due to too low wind speed nor generating strong aerodynamic noise due to too high wind speed.

[0040] In addition, when blowing air downward, the direction of gravity is consistent with the direction of the air flow, which can offset the speed attenuation of the air flow caused by resistance to a certain extent. Especially in the wind speed range of 3 - 5m / s with a relatively low wind speed, the auxiliary effect of gravity is obvious; gravity and the air flow are in the same direction, and it is not easy for the air flow to float and stratify during the sinking process. Especially when the vertical section of the air duct is relatively long, it can improve the stability of the wind speed at the end.

[0041] Such as Figure 7As shown, in order to ensure the room temperature environment of the spiral tower, an insulation layer is set on the outside of the spiral tower. Therefore, the oxygen produced by the crops on each planting tray will be diluted by the air discharged from the third through hole 10, which can accelerate the air circulation of each planting environment, avoid excessive local oxygen concentration affecting crop growth, and at the same time, the airflow can also help regulate the humidity of the planting environment and improve the crop growth quality.

[0042] For example, a 15-meter-high spiral tower can be divided into 17 levels. Along the direction of the transmission gear shaft, the fan blows air from top to bottom, and then the oxygen concentration of each level is tested. The oxygen concentration is reduced by at least 10%, which effectively reduces the phenomenon of oxygen poisoning in crops.

[0043] In actual use, the top of the air duct is connected to the air outlet of the fan via a connecting flange. After the fan is started, the air in the air duct is discharged sequentially through gap 9, first through hole 5 / second through hole 6, through hole 7, and third through hole 10. During this process, if there is condensation on the surface of the central shaft 1, it will evaporate quickly under the action of airflow and be discharged with the airflow, preventing condensation from falling into the connection between the gear disk 4 and the central shaft 1. At the same time, the zinc plating layer further reduces water vapor condensation, providing double protection to prevent the gear disk 4 from rusting.

[0044] Meanwhile, due to the limiting effect of the first spacer 2 and the second spacer 3, when the transport trolley applies pressure to the gear disk 4 through the chain, the displacement of the gear disk 4 along the central shaft 1 is greatly limited, the meshing deviation between the chain and the gear disk 4 is reduced, and the noise in the transmission process is effectively reduced.

[0045] In this embodiment, during operation, when the transport trolley transmits pressure to the gear disk 4 via the chain, the axial end faces of the hollow shafts 8 on both sides of the gear disk 4, as well as the first spacer 2 and the second spacer 3, form a rigid limit, preventing the gear disk 4 from axially displacing along the central shaft 1, ensuring precise meshing between the chain and the gear disk 4, and effectively reducing operating noise.

[0046] 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 spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A transmission gear shaft for a planting tray conveying system, characterized in that, include: A central shaft (1) is provided with a first spacer (2) and a second spacer (3) fixed at equal intervals on the central shaft (1), and a gear disk (4) is assembled between the first spacer (2) and the second spacer (3). Several hollow shafts (8) are sleeved on the outside of the central shaft body (1), and their two ends are respectively sleeved with the first spacer (2) and the second spacer (3), and there is a gap (9) between the hollow shaft (8) and the central shaft body (1). The axial end faces of the adjacent hollow shafts (8) respectively abut against the two end faces of the gear disk (4), forming a bidirectional axial limiting support for the gear disk (4).

2. The transmission gear shaft of the planting tray conveying system according to claim 1, characterized in that, The first spacer (2) has at least one first through hole (5) along the length of the central shaft (1), the second spacer (3) has at least one second through hole (6) along the length of the central shaft (1), the gear disk (4) has a through hole (7), the through hole (7) is coaxial with the first through hole (5) and the second through hole (6); the through hole (7), the first through hole (5), the second through hole (6) and the gap (9) between the hollow shaft (8) and the central shaft (1) together form an air duct, the top of the air duct is connected to the fan; The cross-section of the central shaft (1) is a solid structure or a hollow structure; the first spacer (2) and the second spacer (3) are both fixed to the central shaft (1) by a flat key (12) and a screw (13).

3. The transmission gear shaft of the planting tray conveying system according to claim 2, characterized in that, The hollow shaft (8) has at least one third through hole (10) on its circumference. The third through hole (10) is connected to the air duct, and the third through hole (10) corresponds one-to-one with the level of the spiral tower. Each level of the spiral tower is provided with at least one third through hole (10).

4. The transmission gear shaft of the planting tray conveying system according to claim 3, characterized in that, One to two third through holes (10) are evenly distributed around the hollow shaft (8) for each layer. The diameter of the third through hole (10) is φ10-25mm. Its hole axis is inclined at a 45°-60° downward angle with the radial direction of the hollow shaft (8). A filter screen (11) is provided at the opening of the third through hole (10).

5. The transmission gear shaft of the planting tray conveying system according to claim 4, characterized in that, The inner wall of the third through hole (10) is smooth, and the third through holes (10) of adjacent layers are misaligned by 15°-30° in the circumferential direction.

6. The transmission gear shaft of the planting tray conveying system according to claim 5, characterized in that, The surface of the central shaft (1) is galvanized.

7. The transmission gear shaft of the planting tray conveying system according to claim 6, characterized in that, The number of the first through hole (5) and the second through hole (6) are both 2-8, and they are evenly distributed along the circumference of the central axis (1).

8. The transmission gear shaft of the planting tray conveying system according to claim 7, characterized in that, The two ends of the hollow shaft (8) are respectively adapted to be connected to the outer wall of the first spacer (2) and the outer wall of the second spacer (3).

9. The transmission gear shaft of the planting tray conveying system according to claim 3, characterized in that, The distance between the center of the third through hole (10) and each layer of planting tray is 100-150mm.

10. The transmission gear shaft of the planting tray conveying system according to claim 9, characterized in that, The gap (9) between the hollow shaft (8) and the central shaft (1) forms a coaxial circular air duct, and the width of the gap (9) of the circular air duct is 70-100mm.

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