Clutch boosting hydraulic control system of tractor

Abstract

The utility model provides a hydraulic control system for clutch assistance of a tractor, which belongs to the technical field of clutch assistance of tractors and comprises a hydraulic pump, an energy accumulator, a radiator and a chassis oil tank. An oil suction port of the hydraulic pump is connected with the chassis oil tank through an oil filter mechanism pipeline, and an oil outlet of the hydraulic pump is connected with the energy accumulator through a pipeline. The energy accumulator is connected with the clutch power-assisted oil cylinder through a pipeline, an adjusting overflow valve unit capable of adjusting oil pressure is arranged in the clutch power-assisted oil cylinder, and the clutch power-assisted oil cylinder is connected with the clutch control mechanism through a pipeline. The clutch boosting oil cylinder is connected with the chassis oil tank through an oil return pipeline, and a radiator is arranged at the oil return pipeline. The tractor clutch assisting system solves the problems that a traditional clutch assisting system is high in failure risk and non-adjustable in assisting force, has the advantages of being high in reliability, accurate in assisting force adjustment, efficient in energy utilization, high in system stability and the like, and effectively improves the convenience of tractor clutch operation and the overall performance of the system.

Description

Technical Field

[0001] This utility model relates to the field of tractor clutch assist technology, and in particular to a tractor clutch assist hydraulic control system. Background Technology

[0002] In the field of agricultural machinery, tractors are important production tools, and the performance of their clutch assist system directly affects the ease and reliability of operation. Currently, tractor clutch assist methods are mainly mechanical power-assisted operation and single hydraulic pump clutch assist; however, these two traditional assist methods have many drawbacks.

[0003] In terms of reliability, both mechanical clutch assist and single hydraulic pump assist are single-method assist. If a mechanical assist component malfunctions, such as wear or breakage of the mechanical transmission parts, or damage to the hydraulic pump in a single hydraulic pump assist system that prevents it from providing pressure, the entire clutch assist system will fail. This will not only make clutch operation extremely difficult for the tractor, but may even render it unusable, severely impacting the continuity of agricultural production and increasing maintenance and time costs.

[0004] Regarding the adjustability of clutch assist, traditional mechanical clutch assist and single hydraulic pump clutch assist are not adjustable during the assist process. Tractors have different clutch assist requirements under different working conditions, such as deep plowing in the field and transport operations. However, due to the limitation of the operating stroke, the clutch assist effect drops sharply after the operating stroke reaches a certain point. This is especially true for dual-acting clutches, whose strokes are more complex, making it even more difficult to achieve a good assist effect. This fails to meet the usage habits of different customers and the diverse needs of different working conditions, reducing the tractor's applicability and work efficiency.

[0005] In summary, existing tractor clutch assist systems have significant shortcomings in terms of reliability and assist adjustability, affecting the overall performance and user experience of the tractor and making it difficult to meet the needs of different customers and working conditions. Utility Model Content

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology, such as poor reliability and difficulty in adjusting the clutch assist, and to provide a tractor clutch assist hydraulic control system.

[0007] This utility model is achieved through the following technical solution: a tractor clutch assist hydraulic control system, including a hydraulic pump, an accumulator, a radiator, and a chassis oil tank; the oil inlet of the hydraulic pump is connected to the chassis oil tank through an oil filter mechanism pipeline, and the oil outlet pipeline of the hydraulic pump is connected to the accumulator; the accumulator pipeline is connected to the clutch assist cylinder, the clutch assist cylinder is internally equipped with a regulating overflow valve unit that can adjust the oil pressure, and the clutch assist cylinder pipeline is connected to the clutch operating mechanism; the clutch assist cylinder is connected to the chassis oil tank through a return oil pipeline, and a radiator is installed at the return oil pipeline. The components such as the hydraulic pump, accumulator, radiator, and chassis oil tank constitute the basic system architecture of this utility model. The accumulator provides backup assist energy to avoid system paralysis due to the failure of a single assist; the regulating overflow valve unit can adjust the oil pressure to achieve assist adjustment; the radiator cools the return oil to ensure stable system operation.

[0008] A further improvement of this utility model is that the regulating relief valve unit includes a first proportional valve, a second proportional valve, an adjustable relief valve, and a hydraulic cylinder. The port P of the clutch assist cylinder is connected to the port A of the first proportional valve, and the port C of the first proportional valve is connected to the port T of the return oil line. The port B of the first proportional valve is connected to the port B of the second proportional valve, and the adjustable relief valve is connected to the oil lines at the ports B of both the first and second proportional valves. The port D of the second proportional valve is connected to the rod chamber of the hydraulic cylinder, and the rodless chamber of the hydraulic cylinder is connected to the port T of the return oil line. The regulating relief valve unit consists of the first proportional valve, the second proportional valve, the adjustable relief valve, and the hydraulic cylinder. The oil lines of each component are clearly defined, and through precise oil line layout and component cooperation, accurate control of the oil supply to the hydraulic cylinder is achieved, thereby more precisely adjusting the clutch assist magnitude to meet different working conditions and operational requirements.

[0009] A further improvement of this invention is that the port C and port D of the second proportional valve are connected in series with the port T of the return oil line, and a check valve A is installed at the oil passage between the port C and port D of the second proportional valve. The check valve A ensures that when the hydraulic cylinder returns to its original position, the oil in the rod chamber can smoothly return to the oil tank, ensuring the normal reciprocating motion of the cylinder and maintaining the stable operation of the system.

[0010] A further improvement of this invention is that the port A of the second proportional valve is connected to the control oil circuit of the first proportional valve to form a load-sensitive circuit. This design enables the system to automatically adjust the oil circuit according to the actual load, reducing energy consumption when there is no pedal signal and providing assistance with a rapid response when there is a signal, thereby improving energy utilization efficiency and system response speed.

[0011] A further improvement of this invention is that the accumulator is internally equipped with a secondary accumulator and a two-position two-way solenoid valve, which are connected in series with the accumulator's oil inlet P. This design of the secondary accumulator enhances energy storage capacity, and the two-position two-way solenoid valve controls the storage and release of energy in the accumulator, further ensuring the stability and reliability of the power supply.

[0012] A further improvement of this invention is that a time-delay relay and a clutch switch are provided in the intermediate circuit between the two-position two-way solenoid valve and the external power supply, and the two-position two-way solenoid valve, the time-delay relay, the clutch switch, and the external power supply are connected in series. This design of the time-delay relay prevents frequent operation of the solenoid valve, protecting the solenoid valve and the circuit system; the clutch switch controls the operation of the solenoid valve, ensuring that the accumulator releases energy according to the actual clutch operation.

[0013] A further improvement of this invention is that the accumulator is equipped with a pressure measuring port MP, and the pressure measuring port MP and its oil outlet PA of the accumulator are connected in series with the port A of the first proportional valve. This design facilitates real-time monitoring of the accumulator pressure, transmits pressure information to relevant components, and allows the system to adjust its operating state according to the pressure conditions, ensuring stable system operation.

[0014] A further improvement of this invention is that the oil filtration mechanism includes a suction filter and a pressure filter. The suction filter is located in the intermediate oil circuit between the hydraulic pump and the chassis oil tank, while the pressure filter is located in the intermediate oil circuit between the hydraulic pump and the accumulator. This design enables two-stage filtration of the hydraulic oil, effectively removing impurities, reducing wear on system components, and extending the system's service life.

[0015] A further improvement of this invention is that a one-way valve B is installed in parallel with the oil passage of the radiator. This one-way valve B, with its design, can release pressure when the system pressure rises abnormally, protecting the radiator and the entire system and preventing damage to components due to excessive pressure.

[0016] As can be seen from the above technical solutions, the beneficial effects of this utility model are:

[0017] 1. The accumulator and hydraulic pump described in this utility model can work together to effectively improve the reliability of the power assist. When the hydraulic pump fails, the accumulator can release energy to maintain the clutch assist, avoiding system paralysis caused by the failure of a single power assist in traditional methods, ensuring stable operation of the tractor, and reducing maintenance costs and downtime.

[0018] 2. This utility model achieves precise adjustment of the assist level through the design of a clutch assist cylinder. The clutch assist cylinder is equipped with an adjustable overflow valve unit, which can precisely control the oil supply to the cylinder according to user needs and operating conditions to adjust the assist level, meeting the operating habits of different customers and diverse operating requirements, thus improving operating comfort and equipment applicability.

[0019] 3. This utility model improves system performance through the design of a load-sensitive circuit. The load-sensitive circuit, formed by components such as proportional valves, can automatically adjust the oil circuit according to the actual load. When there is no pedal signal, the oil returns to the oil tank to reduce energy consumption; when there is a signal, it quickly provides assistance, improving response speed and energy utilization efficiency.

[0020] 4. The key components of this utility model are rationally designed. The auxiliary accumulator inside the accumulator enhances energy storage capacity, the time-delay relay and clutch switch between the solenoid valve and the external power supply protect the circuit, and the pressure measuring port facilitates pressure monitoring. Meanwhile, the two-stage filtration of the oil filter mechanism effectively reduces component wear, and the radiator's heat dissipation and one-way valve's pressure relief extend the overall service life of the system, thereby ensuring safe and stable system operation. Attached Figure Description

[0021] To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a structural schematic diagram of a specific embodiment of the present utility model.

[0023] Figure 2 This is a schematic diagram of the clutch assist cylinder according to a specific embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the energy storage device according to a specific embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram of the structure of a heat sink according to a specific embodiment of the present invention.

[0026] In the diagram: 1. Hydraulic pump; 2. Suction filter; 3. Pressure filter; 4. Accumulator; 401. Auxiliary accumulator; 402. Two-position two-way solenoid valve; 403. Time delay relay; 404. Clutch switch; 5. Clutch assist cylinder; 501. First proportional valve; 502. Second proportional valve; 503. Adjustable relief valve; 504. Hydraulic cylinder; 505. Check valve A; 6. Clutch operating mechanism; 7. Radiator; 8. Check valve B; 9. Return oil line; 10. Chassis oil tank. Detailed Implementation

[0027] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0028] Please refer to the attached document. Figure 1 , 2 3 and 4, in conjunction with specific embodiments, are described as follows: The tractor clutch-assisted hydraulic control system of this utility model includes a hydraulic pump 1, an accumulator 4, a radiator 7, and a chassis oil tank 10. The oil inlet of the hydraulic pump 1 is connected to the chassis oil tank 10 through an oil filter mechanism pipeline, and the oil outlet pipeline of the hydraulic pump 1 is connected to the accumulator 4. The oil filter mechanism includes an oil suction filter 2 and a pressure filter 3. The oil suction filter 2 is located in the intermediate oil passage between the hydraulic pump 1 and the chassis oil tank 10, and the pressure filter 3 is located in the intermediate oil passage between the hydraulic pump 1 and the accumulator 4. The accumulator 4 is connected to a clutch-assisted cylinder 5. The clutch-assisted cylinder 5 has an internal regulating overflow valve unit capable of adjusting oil pressure, and the clutch-assisted cylinder 5 is connected to a clutch operating mechanism 6. The clutch-assisted cylinder 5 is connected to the chassis oil tank 10 through a return oil pipeline 9, and a radiator 7 is installed at the return oil pipeline 9.

[0029] After the tractor engine starts, it drives the hydraulic pump 1 to operate. The hydraulic pump 1 draws oil from the chassis oil tank 10. The oil first passes through the suction filter 2 to remove large particles of impurities, and then enters the hydraulic pump 1. Inside the hydraulic pump 1, the oil is pressurized. The oil with increased pressure then passes through the pressure filter 3 for a second filtration to ensure purity before entering the accumulator 4 for storage.

[0030] When the driver depresses the clutch pedal, the clutch control mechanism 6 actuates, triggering the clutch assist cylinder 5. At this time, the accumulator 4 releases its stored energy, and hydraulic fluid enters the clutch assist cylinder 5. The relief valve unit adjusts the hydraulic pressure entering the cylinder according to preset or real-time adjusted parameters, causing the cylinder to generate appropriate thrust to help the driver easily disengage the clutch. During this process, the amount of clutch assist can be adjusted according to the driver's needs or different operating conditions.

[0031] After the clutch operation is completed, the oil in the clutch booster cylinder 5 flows back to the chassis oil tank 10 through the return oil line 9. During the return process, the oil is first cooled by the radiator 7 before returning to the chassis oil tank 10. The radiator 7 lowers the oil temperature to prevent excessively high oil temperatures from adversely affecting the system. The chassis oil tank 10 collects the returned oil and performs sedimentation and separation treatment to provide clean oil for the next cycle.

[0032] This system is based on the principle of hydraulic transmission. A hydraulic pump 1 converts mechanical energy into hydraulic pressure energy. An oil filter ensures oil cleanliness, an accumulator 4 stores and releases energy, and a clutch assist cylinder 5 converts hydraulic energy into mechanical energy to provide clutch assistance. A radiator 7 controls the oil temperature to maintain stable system operation. The relief valve unit, based on fluid mechanics principles, adjusts the oil pressure by changing the valve opening, thereby achieving precise control over the clutch assist level. Through the coordinated work of all components, the entire system achieves hydraulic power assist control for the tractor's clutch operation.

[0033] In one embodiment, the regulating relief valve unit includes a first proportional valve 501, a second proportional valve 502, an adjustable relief valve 503, and a hydraulic cylinder 504. The port P of the clutch assist cylinder 5 is connected to the port A of the first proportional valve 501, and the port C of the first proportional valve 501 is connected to the port T of the return oil line 9. The port B of the first proportional valve 501 is connected to the port B of the second proportional valve 502, and the adjustable relief valve 503 is connected to the oil passage at the port B of the first proportional valve 501 and the port B of the second proportional valve 502. The port D of the second proportional valve 502 is connected to the rod chamber of the hydraulic cylinder 504, and the rodless chamber of the hydraulic cylinder 504 is connected to the port T of the return oil line 9.

[0034] When the tractor's hydraulic system starts, hydraulic pump 1 delivers oil from the tank to port P of clutch booster cylinder 5, at which point the oil enters the first proportional valve 501. Based on the system's pressure requirements and preset parameters, the first proportional valve 501 directs a portion of the oil back to the return line 9 via port C, while the remaining oil flows out via port B into the second proportional valve 502. During this process, adjustable relief valve 503 monitors the oil pressure at ports B of both the first and second proportional valves 501 and 502 in real time. If the pressure exceeds the set value, adjustable relief valve 503 opens, overflowing excess oil back to the tank to ensure stable system pressure. The oil, further regulated by the second proportional valve 502, enters the rod chamber of hydraulic cylinder 504, driving the piston. Since the rodless chamber of hydraulic cylinder 504 is connected to port T of the return line 9, the oil in the rodless chamber flows back smoothly during piston movement. The piston's movement generates thrust, which, through connection with the clutch control mechanism 6, assists in clutch operation, enabling easy clutch engagement and disengagement. After the clutch operation is completed, as the system pressure changes, the oil in the rod chamber of the hydraulic cylinder 504, under pressure, flows through the second proportional valve 502 and the first proportional valve 501, and finally returns to the oil tank through the return oil line 9, completing one working cycle.

[0035] This system is based on the pressure and flow control principles of hydraulic systems, regulating the hydraulic fluid through proportional valves and relief valves. The proportional valve can change the valve core opening according to input signals (such as electrical or mechanical signals, which in this system is achieved through mechanical linkage between components and changes in hydraulic pressure), thereby precisely controlling the flow and pressure of the hydraulic fluid. The adjustable relief valve 503 opens to overflow when the system pressure exceeds a set pressure value, maintaining stable system pressure. Furthermore, the hydraulic cylinder 504 utilizes Pascal's principle to create a pressure difference between the rod and rodless chambers, converting the pressure energy of the hydraulic fluid into mechanical energy, generating a linear thrust or pull force that acts on the clutch operating mechanism 6, achieving clutch assistance.

[0036] In one embodiment, port C and port D of the second proportional valve 502 are connected in series with port T of the return oil line 9, and a check valve A505 is provided at the oil passage between port C and port D of the second proportional valve 502.

[0037] By connecting ports C and D of the second proportional valve 502 in series with port T of the return oil line 9, a specific oil return path is established. During hydraulic system operation, this series connection ensures that the oil, after passing through the second proportional valve 502, flows back to the oil tank along a predetermined route, guaranteeing the orderly circulation of oil in the system. By adjusting the oil flow and pressure using the proportional valve, and in conjunction with the series-connected return oil line 9, the working state of the hydraulic cylinder 504 can be precisely controlled, as the inflow and outflow of oil directly affects the movement of the cylinder piston.

[0038] Meanwhile, a one-way valve A505 is located in the oil passage between port C and port D of the second proportional valve 502. Utilizing the unique valve core structure and operating characteristics of the one-way valve, the valve core opens under positive pressure, allowing oil to flow from port D to port C; under reverse pressure, the valve core closes, preventing reverse flow of oil. This characteristic plays a crucial guiding role in the system, ensuring that when the hydraulic cylinder 504 returns to its original position, the oil in the rod chamber can only flow into the return oil line 9 in the specified direction, preventing backflow of oil from interfering with the normal operation of the system.

[0039] In one embodiment, port A of the second proportional valve 502 is connected to the control oil circuit of the first proportional valve 501 to form a load-sensitive circuit.

[0040] The principle of the load-sensitive circuit is based on the matching control of pressure and flow in the hydraulic system. Port A of the second proportional valve 502 is connected to the control oil circuit of the first proportional valve 501, forming a circuit that can automatically adjust the oil flow and pressure according to load changes.

[0041] When the hydraulic pump 1 is working continuously, there is a certain initial pressure in the system. At this time, under the action of this pressure, the control oil circuit of the first proportional valve 501 pushes the valve block to slide first, so that the port C of the first proportional valve 501 is connected to the return oil line 9, and the oil returns directly to the oil tank, and the system is in a low-energy standby state.

[0042] When a clutch pedal signal is input, it indicates a change in system load. This signal causes the valve core of the second proportional valve 502 to actuate, changing the flow state between port A and port B, thereby altering the pressure in the control circuit of the first proportional valve 501. Under the new pressure, the first proportional valve 501 resets, and its valve block actuates to connect port A and port B. The hydraulic fluid output from the hydraulic pump 1 then enters the hydraulic cylinder 504 via the first proportional valve 501 and the second proportional valve 502, providing power to the system.

[0043] This circuit can sense changes in system load in real time and automatically adjust the direction and flow rate of the oil through the coordinated action of two proportional valves, ensuring that the system meets load requirements while maximizing energy efficiency.

[0044] In one embodiment, the accumulator 4 is internally provided with a secondary accumulator 401 and a two-position two-way solenoid valve 402, and the secondary accumulator 401, the two-position two-way solenoid valve 402 are connected in series with the oil inlet P of the accumulator 4.

[0045] The accumulator 4 and its internal auxiliary accumulator 401 together constitute a multi-level energy storage system. When the hydraulic pump 1 is working, hydraulic fluid enters the accumulator 4 through the inlet P. During this process, the auxiliary accumulator 401 and the accumulator 4 synchronously store the pressure energy of the hydraulic fluid. The presence of the auxiliary accumulator 401 increases the effective volume of the entire energy storage device, enabling it to store more hydraulic energy, thereby enhancing the system's energy storage capacity and providing more sufficient power reserves for subsequent clutch-assisted operations.

[0046] Meanwhile, the two-position two-way solenoid valve 402 is connected in series in the oil circuit of the oil inlet P, playing a crucial role in on / off control. When the tractor is not engaged by the clutch, the two-position two-way solenoid valve 402 is in a specific state (such as the closed state), allowing oil to continuously flow into the accumulator 4 and the auxiliary accumulator 401 for energy storage. When a clutch operation signal is received (such as the clutch switch 404 being triggered), the two-position two-way solenoid valve 402 switches its state (such as the open state), changing the direction of oil flow, so that the energy stored in the accumulator 4 and the auxiliary accumulator 401 can be released to provide hydraulic power to the clutch assist cylinder 5.

[0047] In one embodiment, a time delay relay 403 and a clutch switch 404 are provided in the intermediate circuit between the two-position two-way solenoid valve 402 and the external power supply, and the two-position two-way solenoid valve 402, the time delay relay 403, the clutch switch 404 and the external power supply are connected in series.

[0048] This section constructs a control circuit using a clutch switch 404, a time-delay relay 403, and a two-position two-way solenoid valve 402 connected in series. The clutch switch 404 acts as a signal input device; when the driver operates the clutch pedal, the state of the clutch switch 404 changes (e.g., closed or open), generating an electrical signal. This signal is then transmitted along the series circuit to the time-delay relay 403.

[0049] After receiving the signal from the clutch switch 404, the time delay relay 403 does not immediately transmit the signal to the two-position two-way solenoid valve 402. Instead, it delays the signal according to a preset time. This is based on principles such as electromagnetic induction and capacitor charging and discharging. During the delay, the internal circuit of the time delay relay 403 utilizes the charging of the capacitor or the characteristics of electromagnetic components to achieve the time delay. Only after the set delay time has elapsed will the time delay relay 403 transmit the signal to the two-position two-way solenoid valve 402.

[0050] After receiving the signal from the time delay relay 403, the two-position two-way solenoid valve 402 generates a magnetic field in its internal electromagnetic coil according to the characteristics of the signal (such as current direction, voltage magnitude, etc.), attracting the valve core to move, thereby changing the solenoid valve's passage state, controlling the flow of oil in the accumulator 4, and realizing the energy release control of the clutch assist system.

[0051] In one embodiment, the accumulator 4 is provided with a pressure measuring port MP, and the pressure measuring port MP and its oil outlet PA of the accumulator 4 are connected in series with the port A of the first proportional valve 501.

[0052] The accumulator 4 is equipped with a pressure measuring port MP, which is connected to a pressure sensor or pressure detection device. Based on the principle of pressure transmission, the pressure information inside the accumulator 4 can be obtained in real time. Because the pressure measuring port MP is connected to the inside of the accumulator 4, the pressure inside the accumulator 4 will directly act on the detection device connected to the pressure measuring port MP, thereby realizing real-time pressure monitoring.

[0053] Simultaneously, the pressure measuring port MP and the oil outlet PA are connected in series with port A of the first proportional valve 501, allowing the pressure state of the accumulator 4 to directly affect the operation of the first proportional valve 501. When the pressure inside the accumulator 4 changes, the pressure signal is transmitted to port A of the first proportional valve 501 through the series oil circuit. Based on the received pressure signal, the first proportional valve 501 adjusts the valve core position according to its own control characteristics, thereby changing the flow rate and direction of the oil, achieving pressure and flow regulation of the entire hydraulic system to adapt to different working requirements.

[0054] In one embodiment, a one-way valve B8 is provided in parallel with the oil passage of the radiator 7.

[0055] The radiator 7 operates primarily based on the principle of heat exchange. In the hydraulic system, the oil temperature rises after the clutch-assisted cylinder 5 performs work. When the high-temperature oil flows through the radiator 7, the radiator 7 utilizes its large heat dissipation area to transfer the heat in the oil to the surrounding air, thereby cooling the oil and ensuring that the hydraulic oil always operates within a suitable temperature range, maintaining its good performance.

[0056] The one-way valve B8 is connected in parallel to the oil circuit of the radiator 7 and has a one-way flow characteristic. Under normal circumstances, the hydraulic oil flows in the direction set by the system, and the one-way valve B8 is in the closed state, which does not affect the normal heat dissipation of the radiator 7. When an abnormal situation occurs in the system, such as internal blockage of the radiator 7 or a sudden increase in pressure in the return oil line 9, the one-way valve B8 will open under the action of pressure difference, allowing the oil to bypass the radiator 7 and flow back directly, avoiding damage to the radiator 7 and the entire system due to excessive pressure.

[0057] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A tractor clutch-assist hydraulic control system comprising a hydraulic pump (1), an accumulator (4), a radiator (7) and a chassis sump (10), characterized by, The oil suction port of the hydraulic pump (1) is connected to the chassis oil tank (10) through an oil filter mechanism pipeline, and the oil outlet of the hydraulic pump (1) is connected to the accumulator (4) through a pipeline; the accumulator (4) is connected to the clutch assist oil cylinder (5) through a pipeline, the inside of the clutch assist oil cylinder (5) is provided with an adjustable overflow valve unit capable of adjusting oil pressure, and the clutch assist oil cylinder (5) is connected to the clutch operating mechanism (6) through a pipeline; the clutch assist oil cylinder (5) is connected to the chassis oil tank (10) through a return oil pipeline (9), and the return oil pipeline (9) is provided with a radiator (7).

2. A tractor clutch-assist hydraulic control system as in claim 1, wherein, The adjustable overflow valve unit comprises a first proportional valve (501), a second proportional valve (502), an adjustable overflow valve (503) and a hydraulic oil cylinder (504), the port P of the clutch assist oil cylinder (5) is connected to the port A of the first proportional valve (501), and the port C of the first proportional valve (501) is connected to the port T of the return oil pipeline (9); the port B of the first proportional valve (501) is connected to the port B of the second proportional valve (502), and the adjustable overflow valve (503) is connected to the oil circuit at the ports B of the first proportional valve (501) and the second proportional valve (502); the port D of the second proportional valve (502) is connected to the rod cavity of the hydraulic oil cylinder (504), and the rodless cavity of the hydraulic oil cylinder (504) is connected to the port T of the return oil pipeline (9).

3. A tractor clutch-assist hydraulic control system as defined in claim 2, wherein, The port C and the port D of the second proportional valve (502) are connected in series to the port T of the return oil pipeline (9), and a one-way valve A (505) is arranged at the middle oil circuit of the port C and the port D of the second proportional valve (502).

4. A tractor clutch-assist hydraulic control system as defined in claim 2 or 3, wherein, The port A of the second proportional valve (502) is connected to the control oil circuit of the first proportional valve (501) to form a load-sensitive circuit.

5. A tractor clutch-assist hydraulic control system as defined in claim 4, wherein, The inside of the accumulator (4) is provided with a sub-accumulator (401) and a two-position two-way electromagnetic valve (402), and the sub-accumulator (401) and the two-position two-way electromagnetic valve (402) are connected in series to the oil inlet port P of the accumulator (4).

6. A tractor clutch-assist hydraulic control system as defined in claim 5, wherein, The two-position two-way electromagnetic valve (402) is provided with a delay relay (403) and a clutch switch (404) at the intermediate circuit of the external power supply, and the two-position two-way electromagnetic valve (402), the delay relay (403) and the clutch switch (404) are connected in series to the external power supply.

7. A tractor clutch-assist hydraulic control system as defined in claim 6, wherein, The accumulator (4) is provided with a pressure measuring port MP, and the pressure measuring port MP and the oil outlet port PA of the accumulator (4) are connected in series to the port A of the first proportional valve (501).

8. A tractor clutch-assist hydraulic control system as defined in claim 7, wherein, The oil filter mechanism comprises an oil suction filter (2) and an oil pressure filter (3), the oil suction filter (2) is arranged at the intermediate oil circuit between the hydraulic pump (1) and the chassis oil tank (10), and the oil pressure filter (3) is arranged at the intermediate oil circuit between the hydraulic pump (1) and the accumulator (4).

9. A tractor clutch-assist hydraulic control system as defined in claim 8, wherein, The oil circuit of the radiator (7) is provided with a one-way valve B (8) connected in parallel thereto.

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