Downward pressure automatic adjustment device and sowing unit

Abstract

The present invention discloses an automatic downforce adjustment device and a sowing unit, belonging to the technical field of agricultural sowing. The automatic downforce adjustment device includes a parallel four-link profiling mechanism, an electric adjustment mechanism, and a sensor control system. The parallel four-link profiling mechanism includes a front plate, an upper rod, and a lower rod; in the electric adjustment mechanism, the top of the shell is rotatably connected to an intermediate shaft fixed between the middle and rear sections of the two upper rods, the rear ends of the two driven rods are respectively rotatably connected to the two sides of the middle of the shell, the front end of the driven rod is rotatably connected to the connection between the upper rod and the front plate, the front and rear ends of the fixed rod are respectively fixedly connected to the middle of the top end of the front plate and the top end of the arc track, and the bottom end of the arc track is fixedly connected to the middle of the bottom end of the front plate. The sensor control system includes an angle sensor and a controller. The controller controls the operation of the electric push-pull rod, and the downforce of the sowing unit is automatically adjusted in real time by the electric push-pull rod rotating with the parallel four-link profiling mechanism.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural sowing, and in particular relates to an automatic downforce regulating device and a sowing unit. Background Art

[0002] Mechanized sowing plays a vital role in increasing crop yield and yield per unit area. Stable and consistent sowing depth directly affects the uniformity of seed germination and emergence. The stability and consistency of sowing depth are also important indicators for evaluating sowing quality.

[0003] During seeding, soil hardness and surface undulation significantly influence sowing depth. Hard soil or upward traction resulting from the breakdown of traction can lead to insufficient downward pressure on the sowing unit, resulting in shallow sowing depth, which is detrimental to seed germination and weak seedlings, leading to yield reductions. Soft soil or downward traction resulting from the breakdown of traction can lead to excessive downward pressure on the sowing unit, resulting in deep sowing depth, which is detrimental to seed emergence and reduces yields. Inconsistent sowing depths can affect crop density and uniformity, subjecting crops to uneven temperature and light exposure, and thus impacting yields.

[0004] Therefore, it is necessary to provide an adjustment device that can ensure the stability and consistency of the sowing depth. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an automatic downforce adjustment device and a sowing unit, so as to realize follow-up adjustment of the downforce of the sowing unit.

[0006] To solve the above technical problems, according to one aspect of the present invention, a downforce automatic adjustment device is provided, comprising a parallel four-link profiling mechanism, an electric adjustment mechanism and a sensor control system;

[0007] The parallel four-link profiling mechanism comprises a front plate, an upper rod and a lower rod, wherein two upper rods form a group and two lower rods form a group;

[0008] The front end and rear end of the upper rod are rotatably connected to the top end of the front plate and the upper part of the single frame respectively; the front end and rear end of the lower rod are rotatably connected to the bottom end of the front plate and the lower part of the single frame respectively;

[0009] The electric adjustment mechanism includes a driven rod, a fixed rod, an intermediate shaft, an electric push-pull rod, an arc track, a first roller and a second roller;

[0010] The electric push-pull rod includes a housing and a push-pull rod, an intermediate shaft is fixed between the middle and rear sections of the two upper rods, and the top of the housing is rotatably connected to the intermediate shaft;

[0011] Two follower rods form a group, the rear ends of the two follower rods are respectively rotatably connected to the two sides of the middle part of the shell, and the front ends of the two follower rods are respectively rotatably connected to the connection between the upper rod and the front plate;

[0012] The front end of the fixing rod is fixedly connected to the middle of the top end of the front plate, the rear end of the fixing rod is fixedly connected to the top end of the arc track, and the bottom end of the arc track is fixedly connected to the middle of the bottom end of the front plate;

[0013] The first roller and the second roller are both directly or indirectly connected to the push-pull rod and are respectively arranged on the upper and lower sides of the arc track;

[0014] The sensor control system includes an angle sensor and a controller. The controller is connected to the angle sensor and the electric push-pull rod respectively. The angle sensor is used to collect the change information of the traction angle and transmit it to the controller. The controller controls the operation of the electric push-pull rod.

[0015] Furthermore, the sensor control system includes an optical sensor connected to the controller for collecting soil moisture content.

[0016] Furthermore, a first sleeve is fixed to the upper part of the single frame, and the rear ends of the two upper rods are connected by bolts, and the bolts pass through the first sleeve; a second sleeve is fixed to the lower part of the single frame, and the rear ends of the two lower rods are connected by bolts, and the bolts pass through the second sleeve.

[0017] Furthermore, the angle sensor includes an angle sensor fixed plate and an angle sensor movable plate. The angle sensor fixed plate is mounted on one end of the second sleeve, and the angle sensor movable plate is mounted on the rear end of the lower rod corresponding to the angle sensor fixed plate.

[0018] Furthermore, the first roller is mounted on the first roller shaft, the second roller is mounted on the second roller shaft, and the ends of the first roller shaft and the second roller shaft are connected through a connecting plate; the first roller shaft is connected to the bottom of the push-pull rod.

[0019] According to another aspect of the present invention, a sowing unit is provided, comprising a seeding system, a double-disc furrow opener, a depth limiting mechanism, a pressing device, a sowing depth adjusting device and the above-mentioned automatic downforce adjusting device.

[0020] Furthermore, the seeding system includes a seed box, a seeding device and a seeding tube. The seeding device is fixedly mounted on a single frame, the seed box is fixed above the seeding device, the bottom of the seeding device is connected to the seeding tube, and the bottom of the seeding tube is located inside the double disc furrow opener.

[0021] Furthermore, the double disc furrow opener is arranged below the single body frame and is mounted on the single body frame via a disc shaft.

[0022] Furthermore, the depth limiting mechanism is arranged behind the double-disc furrow opener, and includes a depth limiting wheel, a wheel arm, a wheel axle, a limit block, a limit block shaft and a lower pressure sensor. The two depth limiting wheels are respectively located at the rear outside of the double-disc furrow opener, and the depth limiting wheel is connected to the single frame through the wheel arm, one end of the wheel arm is connected to the depth limiting wheel, and the other end of the wheel arm is connected to the single frame through the wheel axle; the limit block shaft is installed on the single frame above the wheel arm, and a middle hole is opened on the limit block, and the middle hole of the limit block is passed through the limit block shaft. The lower pressure sensor is installed at the lower end of the limit block shaft and in the middle hole of the limit block. The limit block shaft is connected to the sowing depth adjustment device, and the sowing depth adjustment device is installed behind the single frame and adjusts the sowing depth by adjusting the position of the limit block shaft.

[0023] Furthermore, the suppression device is arranged behind the sowing unit and is connected to the unit frame through an axis.

[0024] By using the device described in the present invention, during the sowing operation, the downward pressure of the sowing unit is automatically adjusted in real time by the electric adjustment mechanism according to the angle change information collected by the angle sensor as the parallel four-link profiling mechanism rotates, thereby realizing follow-up adjustment of the downward pressure of the sowing unit, ensuring the consistency and stability of the sowing depth, and thus improving the seed germination rate, the quality of the sowing operation and the crop yield.

[0025] The present invention collects information on soil moisture content through an optical sensor and determines the set value range of the downforce of the sowing unit based on the collected information. When the soil moisture content changes during the sowing operation, the set value range of the downforce of the sowing unit also changes accordingly to ensure the optimal set value of the downforce of the sowing unit.

[0026] The present invention senses the actual size of the downforce in real time through a downforce sensor. When the actual downforce exceeds the set value range, the electric adjustment mechanism performs timely auxiliary adjustment during the follow-up adjustment process to ensure the accuracy of the downforce of the sowing unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings herein are used to provide further illustration of the present invention and constitute a part of this application. The illustrative embodiments of the present invention and their description are used to explain the present invention and do not constitute improper limitations on the present invention.

[0028] Figure 1 This is a schematic diagram of the overall structure of the sowing unit of the present invention;

[0029] Figure 2 It is a structural diagram of a parallel four-link profiling mechanism;

[0030] Figure 3 It is a structural diagram of the electric adjustment mechanism;

[0031] Figure 4 This is the installation diagram of the angle sensor diagram;

[0032] Figure 5 It is a schematic diagram of the connection of the roller;

[0033] Figure 6 It is a structural diagram of the seeding system;

[0034] Figure 7 This is a schematic diagram of the structure of the double disc opener and depth limiting mechanism. To avoid blocking the double disc opener, Figure 7 The outer depth gauge wheels are omitted.

[0035] In the figure, 1-parallel four-link profiling mechanism, 2-electric adjustment mechanism, 3-monobody frame, 4-angle sensor, 5-controller, 6-optical sensor, 7-seeding system, 8-double disc furrow opener, 9-depth limiting mechanism, 10-suppression device, 11-seeding depth adjustment device;

[0036] 100-front plate, 110-upper rod, 120-lower rod; 130-first sleeve, 140-second sleeve, 150-connecting pipe;

[0037] 200 - driven rod, 210 - fixed rod, 220 - intermediate shaft, 230 - electric push-pull rod, 240 - curved track, 250 - first roller, 260 - second roller, 270 - connecting plate, 280 - first roller shaft, 290 - second roller shaft, 231 - housing, 232 - push-pull rod;

[0038] 400-angle sensor fixed plate, 410-angle sensor movable plate; 700-seed box, 710-seeder, 720-seed tube; 810-disc shaft; 910-depth limiting wheel, 920-wheel arm, 930-limit block, 940-limit block shaft, 950-downward pressure sensor, 960-wheel axle. DETAILED DESCRIPTION

[0039] In order to make those skilled in the art better understand the present invention, the present invention is further clearly and completely described below in conjunction with the accompanying drawings and embodiments. It should be noted that, unless there is a conflict, the features in the embodiments and examples of this application can be combined with each other.

[0040] like Figure 1 As shown, a typical embodiment of the present invention provides an automatic downforce adjustment device, which includes a parallel four-link profiling mechanism 1, an electric adjustment mechanism 2 and a sensor control system.

[0041] like Figure 2 As shown, the parallel four-bar linkage contour-profiling mechanism 1 includes a front plate 100 , an upper rod 110 and a lower rod 120 .

[0042] Two upper rods 110 form a group, and two lower rods 120 form a group. Both upper rods 110 and lower rods 120 are positioned between the front panel 100 and the monocoque 3, and are rotatable relative to the front panel 100 and the monocoque 3. The front and rear ends of the upper rods 110 are pivotally connected to the top of the front panel 100 and the upper portion of the monocoque 3, respectively; the front and rear ends of the lower rods 120 are pivotally connected to the bottom of the front panel 100 and the lower portion of the monocoque 3, respectively.

[0043] like Figure 2 As shown, the front ends of the two upper rods 110 are rotatably connected to both sides of the top end of the front plate 100 , and the front ends of the two lower rods 120 are rotatably connected to both sides of the bottom end of the front plate 100 .

[0044] For example, the front panel 100 has side panels on both sides, each with a pin hole at the top and bottom of each panel, into which a pin is mounted. The front end of the upper rod 110 is pivotally connected to the pin at the top of the side panel, forming a pivot point, designated as point A. The front end of the lower rod 120 is pivotally connected to the pin at the bottom of the side panel, forming another pivot point, designated as point B.

[0045] like Figure 2 As shown, the rear ends of the two upper rods 110 are rotatably connected to the upper portion of the single frame 3 , and the rear ends of the two lower rods 120 are rotatably connected to the lower portion of the single frame 3 .

[0046] like Figure 2 、 Figure 3 As shown, the electromagnetic force adjustment mechanism includes a driven rod 200 , a fixed rod 210 , an intermediate shaft 220 , an electric push-pull rod 230 , an arc track 240 , a first roller 250 and a second roller 260 .

[0047] The electric push-pull rod 230 includes a shell 231 and a push-pull rod 232. The intermediate shaft 220 is fixed between the middle and rear sections of the two upper rods 110. The connection between the intermediate shaft 220 and the upper rods 110 is marked as point C. The top of the shell 231 is rotatably connected to the intermediate shaft 220.

[0048] The two follower rods 200 form a group, and the rear ends of the two follower rods 200 are respectively rotatably connected to the two sides of the middle of the shell 231, and the front ends of the two follower rods 200 are respectively rotatably connected to the connection between the upper rod 110 and the front plate 100, that is, the pin shaft at point A.

[0049] The front end of the fixing rod 210 is fixedly connected to the middle of the top of the front panel 100, the rear end of the fixing rod 210 is fixedly connected to the top of the arc track 240, and the bottom end of the arc track 240 is fixedly connected to the middle of the bottom end of the front panel 100. The arc track 240 is set with the midpoint of the line connecting the two points A as the center of the circle.

[0050] The first roller 250 and the second roller 260 are both directly or indirectly connected to the push-pull rod 232 and are respectively arranged on the upper and lower sides of the arc track 240, that is, the first roller 250 is arranged on the upper side of the arc track 240, and the second roller 260 is arranged on the lower side of the arc track 240.

[0051] The sensing control system includes an angle sensor 4 and a controller 5. The controller 5 is connected to the angle sensor 4 and the electric push-pull rod 230 respectively. The angle sensor 4 is used to collect the change information of the traction angle and transmit it to the controller 5. The controller 5 controls the operation of the electric push-pull rod 230.

[0052] In a preferred embodiment, the sensor control system includes an optical sensor 6, which is connected to the controller 5 and is used to collect the moisture content of the soil. Preferably, the optical sensor 6 is installed at the bottom of the front plate 100 of the parallel four-bar linkage profiling mechanism.

[0053] In a relatively specific embodiment, a first sleeve 130 is fixed to the upper portion of the monolithic frame 3. The rear ends of the two upper rods 110 are connected by a bolt that passes through the first sleeve 130 and can rotate within the first sleeve 130. A second sleeve 140 is fixed to the lower portion of the monolithic frame 3. The rear ends of the two lower rods 120 are connected by a bolt that passes through the second sleeve 140 and can rotate within the second sleeve 140. In addition, a connecting pipe 150 is fixed between the two lower rods 120.

[0054] Exemplarily, the single frame 3 includes a lower frame and an upper frame longitudinally fixed to the front end of the lower frame, the first sleeve 130 is fixed to the top of the upper frame, and the second sleeve 140 is fixed to the front end of the lower frame.

[0055] Based on the above embodiments, this embodiment provides an optional installation method of the angle sensor 4. Figure 4 As shown, the angle sensor 4 includes an angle sensor fixed plate 400 and an angle sensor movable plate 410. The angle sensor fixed plate 400 is installed at one end of the second sleeve 140, and the angle sensor movable plate 410 is installed at the rear end of the lower rod 120 corresponding to the angle sensor fixed plate 400. The angle sensor movable plate 410 can rotate with the lower rod 120.

[0056] In another relatively specific embodiment, Figure 3 、 Figure 5 As shown, the first roller 250 is installed on the first roller shaft 280, the second roller 260 is installed on the second roller shaft 290, and the ends of the first roller shaft 280 and the second roller shaft 280 are connected by a connecting plate 270; the first roller shaft 280 is connected to the bottom of the push-pull rod 232.

[0057] Another typical embodiment of the present invention provides a sowing unit, which includes the automatic downforce adjustment device described in the above embodiment, as well as a seeding system 7, a double-disc furrow opener 8, a depth limiting mechanism 9, a pressing device 10, and a sowing depth adjustment device 11.

[0058] Among them, such as Figure 6 As shown, the seeding system 7 includes a seed box 700, a seeding device 710 and a seeding tube 720. The seeding device 710 is fixedly mounted on the single frame 3, the seed box 700 is fixed above the seeding device 710, the bottom of the seeding device 710 is connected to the seeding tube 720, and the bottom of the seeding tube 720 is located inside the double disc furrow opener 8.

[0059] The double disc furrow opener 8 is arranged below the single frame 3 and is mounted on the single frame 3 via a disc shaft 810 .

[0060] The depth limiting mechanism 9 is arranged behind the double disc furrow opener 8, and includes a depth limiting wheel 910, a wheel arm 920, a wheel axle 960, a limit block 930, a limit block shaft 940 and a down force sensor 950.

[0061] The two depth-limiting wheels 910 are respectively located at the rear position outside the double-disc furrow opener 8. The depth-limiting wheels 910 are connected to the single frame 3 through the wheel arm 920. One end of the wheel arm 920 is connected to the depth-limiting wheel 910, and the other end of the wheel arm 920 is connected to the single frame 3 through the wheel axle 960. The wheel axle 960 is fixed on the single frame 3.

[0062] refer to Figure 7 The limit block shaft 940 is installed on the single frame 3 above the wheel arm 920. The limit block 930 is provided with a middle hole. The middle hole of the limit block 930 is passed through the limit block shaft 940. The down pressure sensor 950 is installed at the lower end of the limit block shaft 940 and in the middle hole of the limit block 930. The limit block shaft 940 is connected to the sowing depth adjustment device 11. The sowing depth adjustment device 11 is installed behind the single frame 3. The sowing depth adjustment device 11 adjusts the sowing depth by adjusting the position of the limit block shaft 940.

[0063] The suppressing device 10 is arranged behind the sowing unit and is connected to the unit frame 3 through a shaft.

[0064] When the operation starts, the tractor pulls the sowing unit forward through the suspension device, and the optical sensor 6 collects soil moisture information and transmits it to the controller 5. The controller 5 sends the sowing unit downforce setting value range information to the electric push-pull rod 230 and the downforce sensor 950 in real time based on the information collected by the optical sensor 6.

[0065] The parallel four-link profiling mechanism 1 pulls the single frame 3 to move forward with the undulations of the ground. The electric push-pull rod 230 adjusts the force in real time according to the angle change information of the angle sensor 4 and as the parallel four-link profiling mechanism 1 floats up and down, so as to achieve the downward force of the sowing unit within the set value range.

[0066] Under the combined action of the gravity of the sowing unit, the tractor traction decomposition force and the push-pull force of the electric push-pull rod 230, the double-disc furrow opener 8 enters the soil to open a seed furrow, and the seeds are discharged from the seed box 700 through the seed meter 710 and the seed tube 720 into the seed furrow. The depth-limiting wheel 910 rotates upward under the action of the reverse force of the soil, and the depth-limiting wheel 910 and the wheel arm 920 support the limit block 930, and the limit block 930 also supports the lower pressure sensor 950. The lower pressure sensor 950 feeds back the actual value information of the lower pressure of the single frame 3 to the controller 5 in real time. At the same time, the depth-limiting wheel 910 squeezes the soil on the seed furrow, and the suppression device 10 completes the suppression of the seed furrow.

[0067] The following describes the process of downforce adjustment for different states. The main formulas involved are:

[0068] F=G+(±F1sinα)+(±F2);

[0069] Among them, F is the downward force of the sowing unit, G is the weight of the sowing unit, F1 is the traction force of the tractor on the sowing unit, F2 is the push and pull force of the electric push-pull rod, and α is the traction angle of the sowing unit, which refers to the angle between the traction line and the horizontal center line of the sowing unit during the traction process.

[0070] Set the initial state (when α is 0). At this time, the tractor's traction force on the sowing unit is only forward force, and there is no decomposition force. The push-pull rod 232 pulls back the second roller 260, and correspondingly pulls back the upper rod 110, and applies a certain downward force to the sowing unit, so that the downward force of the sowing unit is maintained within the set value range.

[0071] When α changes from 0° to 30°, the monomer frame 3 of the sowing monomer floats upward relative to the front plate 100, and the upper rod 110 and the lower rod 120 rotate counterclockwise around the points A and B at their respective front ends respectively. At the same time, relative rotation occurs between the angle sensor dynamic disk 410 and the angle sensor fixed disk 400 at the rear end of the lower rod 120. The angle sensor 4 transmits the α change information to the controller 5. The controller 5 sends an adjustment instruction to the electric push-pull rod 230 in real time according to the angle change information. The upper rod 110 drives the shell 231 to rotate counterclockwise through the intermediate shaft 220, and the driven rod 200 also rotates counterclockwise with the shell 231. When the cam 220 is in the forward direction, the second roller 260 is pulled back by the push-pull rod 232. ...

[0072] When the driven rod 200, the housing 231, and the line segment connecting points A and C are projected onto the same plane, a triangle is formed. Since the curved track 240 is fixed to the front plate 100 with the midpoint of the line connecting the two points A as its center, the triangle formed also rotates with the midpoint of the line connecting the two points A as its center. Therefore, the first roller 250 and the second roller 260 can roll along the curved track 240 with the push-pull rod 232. Because the push-pull rod 232 is constrained by the curved track 240 and the formed triangle, the length of the push-pull rod 232 extending from the housing 231 remains constant when the push-pull rod 232 rotates with the upper rod 110, whether pushing outward or pulling back. This also enables the electric push-pull rod 230 to exert a force-adding or force-reducing effect on the upper rod 110 in real time as it rotates with the parallel four-bar linkage contouring mechanism 1.

[0073] When α changes from 30° to 0°, the electric push-pull rod 230 rotates clockwise with the parallel four-bar linkage profiling mechanism 1. As α becomes smaller, the downward decomposition force of the traction force gradually becomes smaller, and the push-pull rod 232 pushes the first roller 250 outward and the upward force reduction adjustment gradually becomes smaller. When F2 decreases to 0, the push-pull rod 232 pulls back the second roller 260 according to the instruction of the controller 5, and correspondingly pulls back the upper rod 110. The electric push-pull rod 230 pulls back and adjusts the force downward, and the downward force adjustment gradually increases.

[0074] When α changes from 0° to -30°, the electric push-pull rod 230 rotates clockwise with the parallel four-bar linkage profiling mechanism 1. As α increases, the upward decomposition force of the traction force gradually increases, and the electric push-pull rod 230 pulls back the second roller 260 and the downward force adjustment gradually increases.

[0075] When α changes from -30° to 0°, the electric push-pull rod 230 rotates counterclockwise with the parallel four-bar linkage profiling mechanism 1. As α becomes smaller, the upward decomposition force of the traction force gradually becomes smaller, and the electric push-pull rod 230 pulls back the second roller 260 and the downward force adjustment gradually becomes smaller.

[0076] The downforce sensor 950 feeds back the actual downforce value at the double disc opener 8 to the controller 5 in real time. When the actual downforce exceeds the set value range, the controller 5 sends an immediate auxiliary adjustment instruction to the electromagnetic force adjustment mechanism to quickly adjust it to within the set value range.

[0077] The scope of protection claimed by the present invention is not limited to the above specific embodiments. For those skilled in the art, the present invention may have various variations and modifications. Any modifications, improvements and equivalent substitutions made within the concept and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A downforce automatic adjustment device, characterized in that: It includes a parallel four-link profiling mechanism (1), an electric adjustment mechanism (2) and a sensor control system; The parallel four-link profiling mechanism (1) comprises a front plate (100), an upper rod (110) and a lower rod (120), wherein two upper rods (110) form a group and two lower rods (120) form a group; The front end and rear end of the upper rod (110) are rotatably connected to the top end of the front plate (100) and the upper part of the single frame (3), respectively; the front end and rear end of the lower rod (120) are rotatably connected to the bottom end of the front plate (100) and the lower part of the single frame (3), respectively; The electric adjustment mechanism (2) comprises a driven rod (200), a fixed rod (210), an intermediate shaft (220), an electric push-pull rod (230), an arc track (240), a first roller (250), and a second roller (260); The electric push-pull rod (230) includes a housing (231) and a push-pull rod (232); the intermediate shaft (220) is fixed between the middle and rear sections of the two upper rods (110); and the top of the housing (231) is rotatably connected to the intermediate shaft (220); The two driven rods (200) form a group, the rear ends of the two driven rods (200) are respectively rotatably connected to the two sides of the middle of the housing (231), and the front ends of the two driven rods (200) are respectively rotatably connected to the connection between the upper rod (110) and the front plate (100); The front end of the fixing rod (210) is fixedly connected to the middle of the top end of the front plate (100), the rear end of the fixing rod (210) is fixedly connected to the top end of the arc track (240), and the bottom end of the arc track (240) is fixedly connected to the middle of the bottom end of the front plate (100); The first roller (250) and the second roller (260) are both directly or indirectly connected to the push-pull rod (232) and are respectively arranged on the upper and lower sides of the arc track (240); The sensing control system comprises an angle sensor (4), a controller (5) and an optical sensor (6), wherein the controller (5) is connected to the angle sensor (4) and the electric push-pull rod (230) respectively; the optical sensor (6) is connected to the controller (5) and is used to collect the moisture content of the soil; The optical sensor (6) collects soil moisture information and transmits it to the controller (5). The controller (5) sends the sowing unit downforce setting value range information to the electric push-pull rod (230) and the downforce sensor (950) in real time based on the information collected by the optical sensor (6); The electric push-pull rod (230) performs force addition or reduction adjustment in real time according to the angle change information of the angle sensor (4) and as the parallel four-link profiling mechanism (1) floats up and down, so as to achieve the downward force of the sowing unit within the set value range.

2. The automatic downforce adjustment device according to claim 1, characterized in that: A first sleeve (130) is fixed to the upper portion of the monolithic frame (3), and the rear ends of the two upper rods (110) are connected by a bolt, and the bolt passes through the first sleeve (130); a second sleeve (140) is fixed to the lower portion of the monolithic frame (3), and the rear ends of the two lower rods (120) are connected by a bolt, and the bolt passes through the second sleeve (140).

3. The automatic downforce adjustment device according to claim 2, characterized in that: The angle sensor (4) comprises an angle sensor fixed plate (400) and an angle sensor movable plate (410), wherein the angle sensor fixed plate (400) is mounted on one end of the second sleeve (140), and the angle sensor movable plate (410) is mounted on the rear end of the lower rod (120) corresponding to the angle sensor fixed plate (400).

4. The automatic downforce adjustment device according to claim 3, characterized in that: The first roller (250) is mounted on the first roller shaft (280), the second roller (260) is mounted on the second roller shaft (290), and the ends of the first roller shaft (280) and the second roller shaft (290) are connected via a connecting plate (270); the first roller shaft (280) is connected to the bottom of the push-pull rod (232).

5. A sowing unit, characterized in that: It comprises a seeding system (7), a double-disc furrow opener (8), a depth-limiting mechanism (9), a pressing device (10), a seeding depth adjustment device (11), and the automatic downforce adjustment device according to any one of claims 1 to 4.

6. The sowing unit according to claim 5, characterized in that: The seeding system (7) includes a seed box (700), a seeding device (710) and a seeding tube (720). The seeding device (710) is fixedly mounted on the single frame (3). The seed box (700) is fixed above the seeding device (710). The bottom of the seeding device (710) is connected to the seeding tube (720). The bottom of the seeding tube (720) is located inside the double-disc furrow opener (8).

7. The sowing unit according to claim 5 or 6, characterized in that: The double-disc furrow opener (8) is arranged below the single-body frame (3) and is mounted on the single-body frame (3) via a disc shaft (810).

8. The sowing unit according to claim 7, characterized in that: The depth limiting mechanism (9) is arranged at the rear of the double disc furrow opener (8), and comprises a depth limiting wheel (910), a wheel arm (920), a wheel axle (960), a stop block (930), a stop block axle (940) and a downforce sensor (950). The two depth limiting wheels (910) are respectively located at the rear of the outer side of the double disc furrow opener (8). The depth limiting wheels (910) are connected to the single frame (3) via the wheel arm (920). One end of the wheel arm (920) is connected to the depth limiting wheel (910), and the other end of the wheel arm (920) is connected to the single frame (3) via the wheel axle (960). The limit block shaft (940) is mounted on the single frame (3) above the wheel arm (920), the limit block (930) is provided with a middle hole, the middle hole of the limit block (930) is passed through the limit block shaft (940), the lower pressure sensor (950) is mounted on the lower end of the limit block shaft (940) and in the middle hole of the limit block (930), the limit block shaft (940) is connected to the sowing depth adjustment device (11), the sowing depth adjustment device (11) is mounted on the rear of the single frame (3) and adjusts the sowing depth by adjusting the position of the limit block shaft (940).

9. The sowing unit according to claim 8, characterized in that: The suppression device (10) is arranged behind the sowing unit and is connected to the unit frame (3) via a shaft.

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