A tractor force adjustment feedback mechanism, lifting control system and control method

Abstract

This invention discloses a force adjustment feedback mechanism, a lifting control system, and a control method for a tractor. The force adjustment feedback mechanism includes a bent rod, a return spring, a force adjustment feedback flexible shaft, a bent rod housing, a positioning bolt pin, and a sensor control rod. The bent rod housing is mounted on the rear transmission housing of the tractor, and the bent rod is mounted on the bent rod housing. The sensor control rod is mounted on the bent rod housing via the positioning bolt pin and can rotate around the positioning bolt pin. One end of the sensor control rod is in line contact with the bent rod, and the other end is connected to the force adjustment feedback flexible shaft. In the initial state, the contact foot of the sensor control rod is just in contact with the bent rod. The two ends of the return spring are inserted into the positioning holes of the bent rod housing and the sensor control rod, respectively. This invention replaces the original mechanical linkage of force feedback with a flexible shaft. The deformation of the bent rod caused by the traction force is fed back to the main control valve core of the lifting control valve through the flexible shaft, realizing force adjustment control. The force adjustment feedback mechanism has a simple structure.

Description

Technical Field

[0001] This invention relates to the field of tractor technology, specifically to a tractor force adjustment feedback mechanism, a lifting control system, and a control method. Background Technology

[0002] In the existing technology, there are two main modes of tractor lifting systems: high-pressure systems and lifting systems with force and position feedback.

[0003] Currently, most hydraulic lifting systems for large and medium horsepower tractors in China adopt a strong-pressure soil-entry structure. Although this structure is simple, the suspension mechanism lifts and lowers roughly, which does not meet agronomic requirements and brings disadvantages such as increased fuel consumption and large power loss to the whole machine.

[0004] Medium-horsepower tractor lifting systems often employ lifting systems with force feedback. However, since the distributors in tractors are mostly located within the lifting system, disassembly is inconvenient and maintenance is difficult. Furthermore, lifting systems with force feedback can use either electrical or mechanical feedback. Mechanical feedback systems are widely used due to their force feedback adjustment and their reliability and cost advantages over electrical feedback systems. Tractor-based mechanical feedback lifting systems typically use a linkage mechanism composed of several mechanical links to feedback the force on the lower or upper pull rod to the lifting control valve core, achieving force adjustment feedback. For tractors equipped with mechanical feedback lifting systems, the installation position of the lifting control valve varies. When the control valve is located far from the suspension mechanism, mechanical linkage feedback results in a complex feedback mechanism, difficult layout, long feedback transmission path, low efficiency, and high cost. Summary of the Invention

[0005] This invention provides a tractor force adjustment feedback mechanism, a lifting control system, and a control method. In the lifting control system, the lifting control valve is arranged outside the lifting device housing, which solves the problems of inconvenient disassembly and difficult maintenance. At the same time, the mechanical linkage of the original force feedback is replaced by a flexible shaft. The bending deformation of the rod caused by the traction force is fed back to the main control valve core of the lifting control valve through the flexible shaft, so as to realize force adjustment control. The force adjustment feedback mechanism has a simple structure and is easy to arrange.

[0006] To achieve the above objectives, the specific solution adopted by the present invention is as follows:

[0007] A force adjustment feedback mechanism for a tractor includes a bent rod, a return spring, a force adjustment feedback flexible shaft, a bent rod housing, a positioning bolt pin, and a sensor control rod. The bent rod housing is mounted on the rear box housing of the tractor, the bent rod is mounted on the bent rod housing, and the sensor control rod is mounted on the bent rod housing via the positioning bolt pin. The sensor control rod can rotate around the positioning bolt pin. One contact foot of the sensor control rod rests against the bent rod and makes line contact with it, while the other contact foot is connected to one end of the force adjustment feedback flexible shaft. In the initial state, the contact foot of the sensor control rod is just in contact with the bent rod. The two ends of the return spring are respectively inserted into the positioning holes of the bent rod housing and the sensor control rod.

[0008] A tractor lifting control system includes a lifting control valve, a force adjustment handle, a control mechanism, an intermediate feedback mechanism, and a force adjustment feedback mechanism;

[0009] The lifting control valve and intermediate feedback mechanism are both located outside the lifting housing in the tractor, the force adjustment feedback mechanism is located below the rear of the tractor's rear box housing, and the force adjustment handle is located in the cab.

[0010] The bent rod is connected to the pull rod of the implement mounted on the tractor. The end of the force adjustment feedback flexible shaft away from the sensor control rod is connected to the intermediate feedback mechanism through the force feedback pull rod. When the traction force of the implement changes, the change in traction force is transmitted to the bent rod through the pull rod. The deformation of the bent rod changes, causing the sensor control rod to rotate around the positioning bolt pin, pulling the force adjustment feedback flexible shaft. The force adjustment feedback flexible shaft drives the intermediate feedback mechanism to move. Through the intermediate feedback mechanism, the working position and opening of the main control valve core in the lifting control valve can be changed, blocking or controlling the oil inlet and outlet of the hydraulic cylinder on the tractor, maintaining or changing the depth of the implement in the soil, thereby realizing force adjustment.

[0011] Furthermore, the control mechanism includes a hydraulic oil tank, an oil suction filter, a gear pump, and a multi-way valve assembly; the independent hydraulic oil tank is installed on the right side of the rear housing, the gear pump and the oil suction filter installed at the bottom left side of the hydraulic oil tank are connected by pipelines, and the filtered oil is led to the oil suction port of the gear pump, the oil outlet of the gear pump is connected to the oil inlet of the multi-way valve assembly through an oil pipe; the oil outlet of the oil inlet of the multi-way valve assembly is connected to the lifting control valve.

[0012] Furthermore, the lifting device housing includes a main housing and an outer housing located outside the main housing, and the lifting control valve and the intermediate feedback mechanism are both arranged on the outer housing.

[0013] Furthermore, the intermediate feedback mechanism includes a first connecting rod, a control rod, a second connecting rod, a cam, and a force adjusting rod assembly connected in sequence. The end of the force adjusting rod assembly away from the cam is connected to a force adjusting flexible shaft. The main control valve core of the lifting control valve abuts against the force feedback rod. A transition connecting rod is provided between the force feedback rod and the cam. One end of the transition connecting rod with a roller is located near surface A of the cam, and the other end abuts against the force feedback rod. The end of the control rod away from the first connecting rod, the middle part of the force adjusting rod assembly, the middle part of the transition connecting rod, and the end of the force feedback rod away from the main control valve core are all rotatably connected to a mounting shaft fixed on the outer casing. A first spring is connected between the inner wall of the outer casing and the connecting shaft of the second connecting rod. A second spring is connected between the inner wall of the outer casing and the roller of the transition connecting rod.

[0014] Furthermore, the end of the force adjustment feedback flexible shaft away from the sensing control rod is hinged to the end of the first connecting rod away from the control rod via the force feedback pull rod.

[0015] A tractor lifting control method involves adjusting the force adjustment flexible shaft via a force adjustment handle, pulling or releasing the force adjustment tie rod assembly, thereby driving the cam to rotate, causing its A surface to press against or move away from the roller on the transition link. Then, the main control valve core is pressed or released via a force feedback rod, changing the position and opening of the main control valve core, blocking or controlling the oil inlet and outlet of the hydraulic cylinder, and setting the tillage depth of the implement.

[0016] After the tillage depth is set, when the traction force changes, the change in traction force is transmitted to the bending rod through the pull rod, causing a change in the deformation of the bending rod. The deformation is transmitted to the force feedback rod through the sensor control rod and the force adjustment feedback flexible shaft. The force feedback rod drives the first connecting rod to rotate counterclockwise. Under the action of the second connecting rod, the cam rotates clockwise, pressing or disengaging from the roller on the transition connecting rod. Then, the force feedback rod presses or releases the main control valve core, changing the position and opening of the main control valve core, blocking or controlling the oil inlet and outlet of the hydraulic cylinder, maintaining or changing the tillage depth of the implement, thereby achieving force adjustment.

[0017] Beneficial effects:

[0018] In this invention, the lifting control valve of the lifting control system is located outside the lifting device housing, while the related force adjustment feedback mechanisms are all located at the bottom of the tractor's rear box housing. This solves the problems of inconvenient disassembly and difficult maintenance in existing lifting systems. Furthermore, this invention uses a flexible shaft-type force adjustment feedback mechanism instead of the previous linkage feedback mechanism. Force change signals are fed back to the control valve core via the flexible shaft to achieve force adjustment control. Simultaneously, the external placement of the lifting control valve avoids the complex structure of the linkage feedback mechanism and prevents the mixing of hydraulic and transmission system fluids, ensuring fluid cleanliness and improving the reliability of the hydraulic system. Meanwhile, existing force feedback mechanisms are complex, have long feedback transmission routes, are inefficient, and costly. Attached Figure Description

[0019] Figure 1 This is a diagram showing the layout of the main components of the lifting control system in this invention on a tractor.

[0020] Figure 2 This is one of the structural schematic diagrams of a force regulation feedback mechanism.

[0021] Figure 3 This is the second schematic diagram of the force adjustment feedback mechanism.

[0022] Figure 4 This is a schematic diagram of the intermediate feedback mechanism and the lift control valve.

[0023] Figure 5 The schematic diagram of the hydraulic system for improving the control system.

[0024] Figure 6 This is one of the internal structural diagrams for improving the control valve.

[0025] Figure 7 To and Figure 6 The corresponding schematic diagram of the lift control valve.

[0026] Figure 8 The second internal structure diagram for improving the control valve.

[0027] Figure 9 To and Figure 8 The corresponding schematic diagram of the lift control valve.

[0028] Figure 10 The third diagram shows the internal structure of the control valve.

[0029] Figure 11 To and Figure 10 The corresponding schematic diagram of the lift control valve.

[0030] Figure 12 This is a diagram showing the boost control logic of the boost control system in this invention.

[0031] Diagram markings: 1. Hydraulic oil tank, 2. Suction filter, 3. Gear pump, 4. Rear housing, 5. Pull rod, 6. Hydraulic cylinder, 7. Inlet pipe, 8. Multi-way valve assembly, 9. Force feedback lever, 10. Lifting control valve, 11. Force adjustment handle, 12. Force adjustment flexible shaft, 13. Friction plate, 14. Bent rod, 15. Return spring, 16. Force adjustment feedback flexible shaft, 17. Bent rod housing, 18. Positioning bolt pin, 19. Sensor control rod, 20. First connecting rod, 21. Control lever, 22. Second connecting rod, 23. First spring, 24. Cam, 25. Second spring, 26. Force adjustment lever assembly, 27. Transition connecting rod, 28. Force feedback rod, 29. Lifter housing, 291. Outer housing, 30. Return spring, 31. Main control valve core, 32. Return valve core. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0033] It should be noted that, unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. In the specification and claims of this patent application, the terms "main control valve core" and "main valve core" have the same meaning, referring to the valve core of the main control valve included in the lift control valve 10; the words "the" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The words "comprising" or "including" indicate that the elements or objects preceding "comprising" or "including" encompass the elements or objects listed following "comprising" or "including" and their equivalents, but do not exclude other elements or objects having the same function. The directions of movement of the elements described in the specification are only described according to the directions shown in the accompanying drawings and are not intended to limit the actual directions of movement of the elements.

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] A tractor lifting control system, please refer to Figure 1 and Figure 5The lifting control system includes a hydraulic oil tank 1, an oil suction filter 2, a gear pump 3, a rear housing 4, a multi-way valve assembly 8, a lifting control valve 10, a force adjustment handle 11, a force adjustment feedback mechanism, and an intermediate feedback mechanism. The independent hydraulic oil tank 1 is installed on the right side of the rear housing 4. The gear pump 3 and the oil suction filter 2, installed at the bottom left side of the hydraulic oil tank 1, are connected by pipelines, leading the filtered oil to the suction port of the gear pump 3. The outlet of the gear pump 3 is connected to the inlet port of the multi-way valve assembly 8 via an oil pipe. The outlet port of the multi-way valve assembly 8 is connected to the P port of the lifting control valve 10. The lifting control valve 10 is located outside the tractor lifting housing 29, the force adjustment feedback mechanism is located below the rear of the tractor rear housing 4, and the force adjustment handle 11 is located in the cab. Its hydraulic principle is as follows: After the gear pump 3 draws oil from the hydraulic oil tank 1, the hydraulic oil enters the lifting control valve 10 through the middle position bridge oil circuit of the multi-way valve assembly 8 from the outlet of the gear pump 3, and then enters the hydraulic cylinder 6 through the lifting control valve 10 and the oil inlet pipe 7.

[0036] Please refer to Figure 2 and Figure 3 The specific structure of the force adjustment feedback mechanism is described in detail below. This force adjustment feedback mechanism includes a bent rod 14, a return spring 15, a force adjustment feedback flexible shaft 16, a bent rod housing 17, a positioning bolt pin 18, and a sensor control rod 19. The bent rod housing 17 is mounted on the rear housing 4, and the bent rod 14 is mounted on the bent rod housing 17. The sensor control rod 19 is mounted on the bent rod housing 17 via the positioning bolt pin 18. The sensor control rod 19 can rotate around the positioning bolt pin 18. One end of the sensor control rod 19 rests against the bent rod 14 in line contact, and the other end is connected to one end of the force adjustment feedback flexible shaft 16. The two ends of the return spring 15 are respectively inserted into the positioning holes of the bent rod housing 17 and the sensor control rod 19. When the bent rod 14 deforms under load, it pushes one end of the sensor control rod 19, converting the deformation of the bent rod 14 into a left-right displacement via the sensor control rod 19.

[0037] It should be noted that the lifter housing 29 in this invention includes a main housing and an outer housing 291 disposed on one side of the main housing. The lift control valve 10 and the intermediate feedback mechanism are both arranged on the outer housing 291. This design allows the lift control valve 10 and the intermediate feedback mechanism to be separated from the lifter housing in the prior art, facilitating maintenance. The outer housing 291 has multiple mounting holes on its exterior, each containing a mounting shaft. The placement of these mounting holes is prior art and will not be elaborated here; any arrangement that achieves the function of this invention is sufficient.

[0038] Please refer to Figure 4The specific structure of the intermediate feedback mechanism is described in detail below. This intermediate feedback mechanism includes a first connecting rod 20, a control lever 21, a second connecting rod 22, a first spring 23, a cam 24, a second spring 25, a force adjustment lever assembly 26, a transition connecting rod 27, and a force feedback rod 28. The first connecting rod 20, control rod 21, second connecting rod 22, cam 24, and force adjusting rod assembly 26 are sequentially hinged together. The end of the force adjusting rod assembly 26 away from the cam is connected to the force adjusting flexible shaft 12. The force feedback rod 28 abuts against the main control valve core 31 of the lifting control valve 10. The transition connecting rod 27 is located between the force feedback rod 28 and the cam 24, with one end with a roller close to surface A of the cam 24 and the other end abutting against the force feedback rod 28. The end of the control rod 21 away from the first connecting rod 20, the middle of the force adjusting rod assembly 26, the middle of the transition connecting rod 27, and the end of the force feedback rod 28 away from the main control valve core 31 are all rotatably connected to the mounting shaft fixed on the outer casing 291. A first spring 23 is connected between the inner wall of the outer casing 291 and the connecting shaft of the second connecting rod 22. A second spring 25 is connected between the inner wall of the outer casing 291 and the roller of the transition connecting rod 27.

[0039] In detail, the second link 22 is a double link, and the transition link 27 is an obtuse-angle link.

[0040] In detail, the lift control valve 10 is a combination valve, and its specific structure is existing technology and will not be described in detail here. The multi-way valve assembly 8 is a three-piece multi-way valve assembly with a bridge oil circuit.

[0041] In practical use, when the user needs to adjust the tillage depth using the lifting control system of this invention, the force adjustment handle 11 drives the power adjustment feedback mechanism and the intermediate feedback mechanism to move the implement into the soil to the appropriate tillage depth for operation. When soil hardness or depth changes, or other situations cause a sudden increase or decrease in traction force, the force adjustment feedback mechanism feeds back the force change signal to the lifting control valve through the intermediate feedback mechanism, controlling the oil circuit to lift or lower the implement, changing the tillage depth and ensuring that the traction force is the same as the set value, thereby achieving force adjustment control.

[0042] The following is combined with Figures 6-12 The improvement control methods are explained in detail.

[0043] In the initial state, the contact foot of the sensor control lever 19 is in contact with the bent rod 14, and the bent rod 14 is not deformed. At this time, the force adjustment feedback flexible shaft 16 pulls the force feedback lever 9, which, through the first connecting rod 20, the control lever 21, and the second connecting rod 22, maintains balance with the first spring 23, keeping the cam 24 and the roller on the transition connecting rod 27 at a certain distance. At this time, the return spring 30 on the main control valve core 31 in the lifting control valve 10 is in a naturally extended state. At this time, the force adjustment handle 11 is at the lowest position, and the main control valve core 31 is in the left position (e.g., Figure 6 As shown), the oil circuit path is as follows: Figure 7 As shown in the figure (the thick solid line in the figure represents the direction of oil flow, and the thick dashed line represents the pressure transmission): the oil returns from the rodless chamber of the hydraulic cylinder 6, and the oil enters from the P port and flows back to the oil tank through the oil return valve core 32 and the internal oil passage of the lifter housing 29 (the internal space of the rear transmission box is referred to as the oil tank).

[0044] When a user needs to lift the farm implement while working in the field, they pull up the force adjustment handle 11. The force adjustment handle 11 pulls the power adjustment flexible shaft 12, which in turn pulls the power adjustment lever assembly 26, causing it to rotate clockwise. This, in turn, rotates the cam 24, causing its A-side to press against the roller on the transition link 27, forcing the transition link 27 to rotate. The transition link 27 then rotates the power feedback rod 28, which in turn presses against the main control valve core 31, placing it in the right working position (e.g., ...). Figure 10 As shown), the oil circuit path is as follows: Figure 11 As shown in the diagram (the thick solid line in the diagram indicates the direction of oil flow): Oil enters through port P and enters hydraulic cylinder 6 via oil inlet pipe 7, which will lift the agricultural implement to the transport position.

[0045] When the user is working in the field, first place the force adjustment handle 11 to the bottom, the reset spring 30 returns to its original position, the main control valve core 31 is in the left working position, the oil circuit is the same as the oil circuit in the initial state, the hydraulic cylinder 6 descends, and the farm implement enters the soil.

[0046] After the farm implement is put into the soil, the bent rod 14 deforms under the action of traction force. The amount of deformation is fed back to the sensor control rod 19. The sensor control rod 19 rotates around the positioning bolt pin 18, pulling the force adjustment feedback flexible shaft 16. The force adjustment feedback flexible shaft 16 pulls the force feedback pull rod 9, driving the first connecting rod 20, causing the control pull rod 21 to rotate counterclockwise. Under the action of the second connecting rod 22, the cam 24 rotates clockwise, approaching (but not contacting) the roller on the transition connecting rod 27. When the implement descends to the appropriate position and the tillage depth meets the user's requirements, the user pulls the power adjustment handle 11 upwards, causing the cam 24 to rotate counterclockwise until it presses the roller on the transition link 27. The transition link 27 rotates, driving the power feedback rod 28 to press the main control valve core 31. The main control valve core 31 moves, and when it just reaches the right working position, the hydraulic cylinder 6 begins to lift, and the implement begins to rise. At this time, the user stops pulling the power adjustment handle 11. The main control valve core 31 remains balanced under the action of the return spring 30 and the friction plate 13 on the outside of the clamping force adjustment pull rod assembly 26. The main control valve core 31 is in the lifted position, and the implement continues to rise. After the implement rises slightly, the tillage depth decreases, the traction force decreases, the deformation of the bent rod 14 decreases, and the tension of the force adjustment feedback flexible shaft 16 decreases. The return spring 30 begins to reset until the main control valve core 31 returns to the middle working position, where it is balanced under the action of the return spring 30 and the force adjustment feedback flexible shaft 16. The main control valve core 31 is in the middle working position (e.g., Figure 8 As shown), at this time, cam 24 presses against the roller on the transition link 27. The oil circuit is as follows... Figure 9 As shown in the figure (the thick solid line in the figure represents the direction of oil flow, and the thick dashed line represents the pressure transmission), the oil enters through port P and flows back to the oil tank through the return valve core 32. The hydraulic cylinder 6 is locked, the agricultural implement height is locked, and the tillage depth is constant.

[0047] When soil hardness or depth changes, or other conditions cause a sudden increase in traction, the bending rod 14 deforms more under the action of the pull rod 5, allowing the sensor control rod 19 to rotate counterclockwise around the positioning bolt pin 18. This pulls the force adjustment feedback flexible shaft 16, which in turn pulls the force feedback rod 9, causing the first connecting rod 20 and the control rod 21 to rotate clockwise. Under the action of the second connecting rod 22, the cam 24 rotates clockwise, pressing the roller on the transition connecting rod 27, causing the force feedback rod 28 to rotate. The force feedback rod 28 then presses the main control valve core 31, placing it in the right working position (e.g., ...). Figure 10 As shown), the oil circuit is as follows Figure 11 As shown, oil enters the hydraulic cylinder 6 through the oil inlet pipe 7 via port P, causing the implement to lift. When the implement is lifted, the tillage depth decreases, the traction force decreases, the deformation of the bending rod 14 decreases, the tension of the force adjustment feedback flexible shaft 16 decreases, and the return spring 30 begins to reset until the main control valve core 31 returns to the intermediate working position, at which point the traction force remains unchanged, thus achieving force adjustment control.

[0048] When soil hardness or depth changes, or other conditions cause a sudden decrease in traction, the deformation of the bent rod 14 decreases under the action of the pull rod 5, the tension of the force adjustment feedback flexible shaft 16 decreases, the return spring 30 springs back, pushing the main control valve core 31 to move to the left working position, the hydraulic cylinder 6 descends, the implement descends, the deformation of the bent rod 14 increases, and the tension of the force adjustment feedback flexible shaft 16 increases until a certain tillage depth is reached, the tension of the force adjustment feedback flexible shaft 16 and the force of the return spring 30 are balanced, the main control valve core 31 returns to the middle working position, the traction remains unchanged, and force adjustment control is achieved.

[0049] This invention utilizes a force adjustment handle 11 to drive a force adjustment flexible shaft 12, which pulls or releases the force adjustment lever assembly 26. Through a cam 24, surface A presses against or moves away from the roller on the transition link 27. Further, a force feedback rod 28 presses or releases the main control valve core 31, changing its working position and opening. This blocks or controls the oil flow into and out of the hydraulic cylinder 6, thus setting the tillage depth of the implement. After the tillage depth is set, when the traction force changes, the pull rod 5 transmits this change to the bent rod 14, altering its deformation. This deformation, transmitted through the sensor control rod 19 and the force adjustment feedback flexible shaft 16, further presses or releases the main control valve core 31 of the lifting control valve 10 via an intermediate feedback mechanism. This changes the working position and opening of the main control valve core 31, blocking or controlling the oil flow into and out of the hydraulic cylinder 6, maintaining or changing the tillage depth of the implement, thereby achieving force adjustment.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A tractor lift control system, characterized by, The control mechanism comprises a hydraulic oil tank (1), an oil suction filter (2), a gear pump (3) and a multi-way valve assembly (8); the independent hydraulic oil tank (1) is installed on the right side of the rear box shell (4), the oil suction filter (2) and the gear pump (3) are connected through pipelines, and the filtered oil is introduced into the oil suction port of the gear pump (3); the oil outlet of the oil inlet connection of the multi-way valve assembly (8) is connected with the oil inlet of the lifting control valve (10). The lifting control valve (10) and the intermediate feedback mechanism are arranged on the outer shell (291). The control mechanism comprises a hydraulic oil tank (1), an oil suction filter (2), a gear pump (3) and a multi-way valve assembly (8); the independent hydraulic oil tank (1) is installed on the right side of the rear box shell (4), the oil suction filter (2) and the gear pump (3) are connected through pipelines, and the filtered oil is introduced into the oil suction port of the gear pump (3); the oil outlet of the oil inlet connection of the multi-way valve assembly (8) is connected with the oil inlet of the lifting control valve (10). The lifting control valve (10) and the intermediate feedback mechanism are arranged on the outer shell (291).

2. A tractor lift control system as claimed in claim 1, characterised in that, The control mechanism comprises a hydraulic oil tank (1), an oil suction filter (2), a gear pump (3) and a multi-way valve assembly (8); the independent hydraulic oil tank (1) is installed on the right side of the rear box shell (4), the oil suction filter (2) and the gear pump (3) are connected through pipelines, and the filtered oil is introduced into the oil suction port of the gear pump (3); the oil outlet of the oil inlet connection of the multi-way valve assembly (8) is connected with the oil inlet of the lifting control valve (10).

3. A tractor lift control system as claimed in claim 1, wherein, The lifting control valve (10) and the intermediate feedback mechanism are arranged on the outer shell (291). The control mechanism comprises a hydraulic oil tank (1), an oil suction filter (2), a gear pump (3) and a multi-way valve assembly (8); the independent hydraulic oil tank (1) is installed on the right side of the rear box shell (4), the oil suction filter (2) and the gear pump (3) are connected through pipelines, and the filtered oil is introduced into the oil suction port of the gear pump (3); the oil outlet of the oil inlet connection of the multi-way valve assembly (8) is connected with the oil inlet of the lifting control valve (10).

4. A tractor lift control system as claimed in claim 3, characterised in that, The intermediate feedback mechanism comprises a first connecting rod (20), a control pull rod (21), a second connecting rod (22), a cam (24) and a force adjusting pull rod assembly (26) connected in sequence, the force adjusting pull rod assembly (26) is connected with a force adjusting soft shaft (12) at an end away from the cam, a main control valve core (31) of a lift control valve (10) abuts against a force feedback rod (28), a transition connecting rod (27) is arranged between the force feedback rod (28) and the cam (24), one end of the transition connecting rod (27) with a roller is arranged close to an A surface of the cam (24), and the other end abuts against the force feedback rod (28); wherein an end of the control pull rod (21) away from the first connecting rod (20), a middle part of the force adjusting pull rod assembly (26), a middle part of the transition connecting rod (27) and an end of the force feedback rod (28) away from the main control valve core (31) are all rotationally connected with a mounting shaft fixed on an outer shell (291); a first spring (23) is connected between an inner wall of the outer shell (291) and a connecting shaft of the second connecting rod (22); and a second spring (25) is connected between the inner wall of the outer shell (291) and the roller of the transition connecting rod (27). An end of the force adjusting feedback soft shaft (16) away from a sensing control rod (19) is hingedly connected with an end of the first connecting rod (20) away from the control pull rod (21) through a force feedback pull rod (9).

5. A tractor lift control system as claimed in claim 4, wherein, The force adjusting handle (11) is used to adjust the force adjusting soft shaft (12), the force adjusting pull rod assembly (26) is pulled or loosened, the cam (24) is driven to rotate, the A surface of the cam (24) presses or leaves the roller on the transition connecting rod (27), then the main control valve core (31) is pressed or loosened through the force feedback rod (28), the position and opening degree of the main control valve core (31) are changed, the oil inlet and return of the hydraulic cylinder (6) are blocked or controlled, and the tillage depth of the agricultural implement is set; 6. A lift control method using the tractor lift control system according to any one of claims 4-5, characterized by, After the tillage depth is set, when the traction force changes, the change of the traction force is transmitted to the bent rod (14) through the lower pull rod (5), the deformation amount of the bent rod (14) changes, the deformation amount is transmitted to the force feedback pull rod (9) through the sensing control rod (19) and the force adjusting feedback soft shaft (16), the first connecting rod (20) is driven to rotate counterclockwise, the cam (24) is driven to rotate clockwise under the action of the second connecting rod (22), the roller on the transition connecting rod (27) is pressed or left, then the main control valve core (31) is pressed or loosened through the force feedback rod (28), the position and opening degree of the main control valve core (31) are changed, the oil inlet and return of the hydraulic cylinder (6) are blocked or controlled, the tillage depth of the agricultural implement is maintained or changed, and thus the force adjustment is realized. ​

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