A low-voltage electro-hydraulic control system for tractors

Abstract

This invention relates to the field of tractor technology and discloses a low-pressure electro-hydraulic control system for a tractor, comprising: an oil tank, which serves as the housing of the tractor gearbox and is used to store hydraulic fluid; a gear pump connected to the oil tank for drawing hydraulic fluid; an electro-hydraulic control valve assembly connected to the gear pump, the assembly including multiple solenoid valves, the inlet ends of which are connected to the hydraulic output end of the gear pump, and the output ends of which are respectively connected to corresponding actuators; and a venting directional valve, the inlet end of which is connected to the hydraulic output end of the gear pump, and the outlet end of which is connected to several oil passages. This low-pressure electro-hydraulic control system effectively prevents air from remaining in the hydraulic system, saves power consumption, reduces system heat generation, and extends the service life of hydraulic components.

Description

Technical Field

[0001] The invention relates to the technical field of tractors, and in particular to a low-voltage electro-hydraulic control system for tractors. Background Art

[0002] When the tractor is initially assembled or repaired, there is no hydraulic oil in the hydraulic pipeline; when it is left unused for a long time, the oil in the high part of the hydraulic system pipeline will flow to the low part due to its own weight, so there will be air in the hydraulic pipeline. When there is air in the oil, after the hydraulic system is running, the air in the oil will affect the normal operation of the system, such as the clutch and brake hydraulic booster device is weak, the wet clutch engagement is frustrated, etc. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a low-voltage electro-hydraulic control system for a tractor, which can prevent air from remaining in the hydraulic system, save power consumption, reduce system heating, and extend the service life of hydraulic components.

[0004] The technical solution provided by the present invention is as follows:

[0005] A tractor low-voltage electro-hydraulic control system, comprising:

[0006] An oil tank, which serves as a tractor gearbox housing and is used to store oil;

[0007] A gear pump, the gear pump is connected to the oil tank and is used to extract the oil;

[0008] An electro-hydraulic control valve group, the electro-hydraulic control valve group is connected to the gear pump, the electro-hydraulic control valve group comprises a plurality of solenoid valves, the liquid inlet ends of the plurality of solenoid valves are connected to the oil output end of the gear pump, and the output ends of the plurality of solenoid valves are respectively connected to corresponding actuators;

[0009] An emptying reversing valve, wherein the liquid inlet end of the emptying reversing valve is communicated with the oil output end of the gear pump, and the liquid outlet end of the emptying reversing valve is connected to a plurality of oil circuits.

[0010] In this technical solution, when the tractor is initially assembled, placed for a long time, or repaired and maintained, the oil in the high part of the hydraulic system pipeline will flow to the low part due to the influence of its own weight, so that air will exist in the hydraulic pipeline. When there is air in the oil, after the hydraulic system is running, the air in the oil will affect the normal operation of the system. Under the action of the emptying reversing valve, when the tractor is started, the air in the system can be exhausted to ensure that there is no air in the hydraulic oil circuit when the system is working normally.

[0011] Further preferably, it also includes: a system pressure control valve;

[0012] The fluid inlet end of the system pressure control valve is communicated with the oil output end of the gear pump, and the fluid outlet end of the system pressure control valve is connected to a plurality of oil circuits.

[0013] Further preferably, the multiple solenoid valves include a power output control valve, a four-wheel drive control valve and a differential lock control valve, and the electro-hydraulic control valve group is provided with a P port, a PT0 port, a 4WD port and a DL port;

[0014] The P port serves as the liquid inlet of the electro-hydraulic control valve group, the liquid inlet end of the P port is connected to the gear pump, and the liquid outlet end of the P port is respectively connected to the liquid inlet ends of the system pressure control valve, the power output control valve, the four-wheel drive control valve, the differential lock control valve, and the emptying reversing valve;

[0015] The power output control valve is used to connect to the power output wet clutch via the PT0 port, the four-wheel drive control valve is used to connect to the four-wheel drive wet clutch via the 4WD port, and the differential lock control valve is used to connect to the differential lock wet clutch via the DL port.

[0016] In this technical solution, when the power output wet clutch, four-wheel drive wet clutch, and differential lock wet clutch are not working, all the oil will overflow from the system pressure control valve to the lubrication system or return to the oil tank, which will cause power loss, which will be converted into heat energy to cause the hydraulic oil temperature to rise, and then the oil will deteriorate, which will reduce the service life of the components. In order to reduce overflow losses, when the power output wet clutch, four-wheel drive wet clutch, and differential lock wet clutch are not working, the emptying reversing valve will continue to be energized, so that the oil will pass directly to the lubrication system or return to the oil tank through the emptying reversing valve, allowing the gear pump to run without load, that is, all the oil output by the pump will flow to the lubrication system or return to the oil tank at zero pressure or low pressure, which can save power consumption, reduce system heating, and extend service life.

[0017] Further preferably, the oil circuit includes a first oil return circuit;

[0018] The first oil return circuit includes a lubrication pressure control valve and a T-port arranged on the electro-hydraulic control valve group. The liquid inlet end of the lubrication pressure control valve is respectively connected to the system pressure control valve and the drain reversing valve, and the liquid outlet end of the lubrication pressure control valve is connected to the oil tank via the T-port to form a circulation loop.

[0019] Further preferably, the oil circuit also includes a second transmission system lubricating oil circuit;

[0020] The second transmission system lubrication oil circuit includes a Lub port and a hydraulic radiator arranged on the electro-hydraulic control valve group, the liquid inlet end of the Lub port is respectively connected to the system pressure control valve and the drain reversing valve, the liquid inlet end of the hydraulic radiator is connected to the liquid outlet end of the Lub port, the liquid outlet end of the hydraulic radiator is connected to the transmission system lubrication damping plug, and the liquid outlet end of the transmission system lubrication damping plug is connected to the oil tank.

[0021] In the present technical solution, the hydraulic radiator is a device for cooling the oil in the hydraulic system. The oil performs efficient heat exchange with the forced-flowing cold air in the heat exchanger, so that the oil temperature drops to the working temperature to ensure that the system can continue to operate normally and the work can be carried out smoothly. After the oil is drawn out from the oil tank, it enters from the P port of the electro-hydraulic control valve group, and preferentially passes through the right-position diversion of the emptying reversing valve. Regardless of whether the power output control valve, the four-wheel drive control valve, and the differential lock control valve are in the on state, one path of oil comes out from the Lub port of the electro-hydraulic control valve group, passes through the hydraulic radiator, and lubricates the power output wet clutch, the four-wheel drive wet clutch, and the differential lock wet clutch respectively; and after lubricating the transmission system from the transmission system lubrication damping plug, it enters the oil tank to form a circulation loop.

[0022] Further preferably, the oil circuit further includes a third gear pump lubrication oil circuit;

[0023] The third gear pump lubrication oil circuit includes a gear pump lubrication throttle valve, an LG port and a gear pump lubrication damping plug. The inlet end of the gear pump lubrication throttle valve is respectively connected to the system pressure control valve and the exhaust reversing valve, and the outlet end of the gear pump lubrication throttle valve is connected to the LG port; the gear pump lubrication throttle valve and the LG port are arranged in the electro-hydraulic control valve group, and the LG port is connected to the oil tank through the gear pump lubrication damping plug.

[0024] In this technical solution, after the oil is drawn from the oil tank, it enters from the P port of the electro-hydraulic control valve group, and preferentially flows through the right-position diversion of the emptying reversing valve. Regardless of whether the power output control valve, the four-wheel drive control valve, and the differential lock control valve are in the on state, the oil passes through the gear pump lubrication throttle valve, comes out from the LG port of the electro-hydraulic control valve group, lubricates the gear pump, and then enters the oil tank to form a circulation loop.

[0025] Further preferably, a wet clutch lubricating oil circuit is provided on the third gear pump lubricating oil circuit and / or the second transmission system lubricating oil circuit, and the liquid outlet ends of the wet clutch lubricating oil circuit are respectively connected to the power output wet clutch, the four-wheel drive wet clutch, and the differential lock wet clutch.

[0026] Further preferably, it also includes: a power output accumulator;

[0027] The PTO port is connected to the power output wet clutch through the power output accumulator, and the power output accumulator is used to play a buffering role when the power output wet clutch is separated and engaged.

[0028] In this technical solution, the power output accumulator is an accumulator that acts as a buffer for the separation and engagement of the power output wet clutch. When the power output wet clutch engages and disengages, the load connected to the power output will feedback the impact to the tractor, causing jerking fluctuations in the hydraulic system. The power output accumulator can absorb and release the impact caused by the engagement and disengagement of the power output wet clutch, and act as a buffer for the hydraulic system, making the power output connection more stable. As an auxiliary power source, it can reduce the power of the pump, improve efficiency, reduce temperature rise, save energy, and reduce system energy loss and the resulting heat.

[0029] Further preferably, it further comprises: a clutch boost system, the clutch boost system being arranged between the oil output end of the gear pump and the P port, the clutch boost system comprising a clutch booster master pump and a clutch booster oil sub-cylinder, one end of the clutch booster master pump being connected to the liquid outlet end of the pressure oil circuit filter, and the other end of the clutch booster master pump being connected to the clutch booster oil sub-cylinder;

[0030] And / or, a brake booster system, which is arranged between the pressure oil circuit filter and the P port, and includes a brake booster master pump and a brake booster sub-cylinder, one end of the brake booster master pump is connected to the liquid outlet end of the pressure oil circuit filter, and the other end of the brake booster master pump is connected to the brake booster sub-cylinder.

[0031] Further preferably, it also includes: a booster accumulator;

[0032] The booster accumulator is arranged between the pressure oil circuit filter and the P port, and is respectively connected to the clutch booster master pump and / or the brake booster master pump. The booster accumulator is used to provide temporary power for the clutch booster master pump and / or the brake booster master pump.

[0033] In this technical solution, the booster accumulator is an accumulator that provides temporary power for the clutch booster system and the brake booster system, and stores hydraulic force when the tractor is running. When the tractor is not started, it replaces the gear pump and serves as a temporary power source for the clutch booster system and the brake booster system. When the clutch booster system and the brake booster system need to work, it provides short-term hydraulic force to improve driving controllability and comfort.

[0034] Compared with the prior art, the tractor low-voltage electro-hydraulic control system of the present invention has the following beneficial effects:

[0035] In the present invention, when the tractor is started, the tractor low-voltage electro-hydraulic control system can exhaust the air in the system through the emptying reversing valve, so as to ensure that there is no air in the hydraulic oil circuit when the system is working normally; when the power output wet clutch, the four-wheel drive wet clutch and the differential lock wet clutch are not working, the emptying reversing valve will be continuously energized, so that the oil will directly pass through the emptying reversing valve to the lubrication system or the return oil tank, so that the gear pump can run without load, that is, the oil output by the pump will all flow to the lubrication system or the return oil tank at zero pressure or low pressure, so that power consumption can be saved, the heat of the system can be reduced, and the service life can be extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The preferred implementation scheme will be described below in a clear and understandable manner with reference to the accompanying drawings to further illustrate the above-mentioned characteristics, technical features, advantages and their implementation methods.

[0037] Figure 1 It is a hydraulic principle diagram of the low-voltage electro-hydraulic control system of the tractor of this embodiment;

[0038] Figure 2 1 is a hydraulic principle diagram of the electro-hydraulic control valve group of this embodiment.

[0039] Description of Figure Numbers:

[0040] 1. Oil tank, 2. Oil suction filter, 3. Gear pump, 4. Pressure oil line filter, 5. Power accumulator, 6. Electro-hydraulic control valve group, 7. Power output accumulator, 8. Power output wet clutch, 9. Four-wheel drive wet clutch, 10. Differential lock wet clutch, 11. Gear pump lubrication damping plug, 12. Transmission lubrication damping plug, 13. Hydraulic radiator, 14. Clutch booster master pump, 15. Clutch booster oil cylinder, 16. Brake booster master cylinder, 17. Brake booster sub-cylinder, 18. System pressure control valve, 19. Power output control valve, 20. Four-wheel drive control valve, 21. Differential lock control valve, 22. Exhaust reversing valve, 23. Lubrication pressure control valve, 24. Gear pump lubrication throttle valve, 25. P port, 26. T port, 27. Lub port, 28. LG port, 29. PT0 port, 30. 4WD port, 31. DL port. DETAILED DESCRIPTION

[0041] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0042] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections.

[0043] In order to simplify the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0044] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0045] In the embodiments shown in the drawings, the indications of directions (such as up, down, left, right, front and back) used to explain the structure and movement of the various components of the present invention are not absolute but relative. These descriptions are appropriate when these components are in the positions shown in the drawings. If the descriptions of the positions of these components change, the indications of these directions also change accordingly.

[0046] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined. In addition, it should be noted that, unless otherwise clearly stipulated and defined, the term "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or it can be a connection between the two elements.

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0048] As a specific example, Figure 1 , Figure 2As shown, this embodiment provides a low-voltage electro-hydraulic control system for a tractor, comprising: an oil tank 1, a gear pump 3, an electro-hydraulic control valve group 6 and an emptying reversing valve 22. The oil tank 1 serves as a tractor gearbox housing for storing oil. The gear pump 3 is connected to the oil tank 1 for extracting oil. The electro-hydraulic control valve group 6 is connected to the gear pump 3, and the electro-hydraulic control valve group includes a plurality of solenoid valves, the liquid inlet ends of the plurality of solenoid valves are respectively connected to the oil output ends of the gear pump 3, and the output ends of the plurality of solenoid valves are respectively connected to corresponding actuators. The liquid inlet end of the emptying reversing valve 22 is connected to the oil output end of the gear pump 3, and the liquid outlet end of the emptying reversing valve 22 is connected to a plurality of oil circuits.

[0049] In this embodiment, the emptying reversing valve 22 is a two-position two-way electromagnetic switch valve, which is normally in a closed state in the oil circuit. The emptying reversing valve 22 is preferably arranged in the electro-hydraulic control valve group 6, so that it has a higher degree of integration and is more compact. The liquid outlet of the emptying reversing valve 22 is connected to one or more oil circuits. When the tractor is started, the emptying reversing valve 22 will be energized due to the start-up instruction, the electromagnetic coil will be attracted, and the oil channel of the emptying reversing valve 22 will be converted to a connected state. At this time, the oil will circulate in the system pipeline without load to exhaust the air. When the air is exhausted, the electromagnetic coil of the emptying reversing valve 22 will be powered off, and the oil channel will be converted to a closed state. This is the normal working state of the hydraulic system. When multiple solenoid valves are in the closed state, in order to reduce overflow loss, the emptying reversing valve 22 will continue to be energized, so that the oil can pass directly to the lubrication system or the return oil tank through the emptying reversing valve 22, allowing the gear pump 3 to run at no load, that is, all the oil output by the pump flows to the lubrication system or the return oil tank at zero pressure or low pressure, thereby saving power consumption, reducing system heat generation and extending service life.

[0050] Furthermore, the tractor low-voltage electro-hydraulic control system further includes: a system pressure control valve 18; the liquid inlet end of the system pressure control valve 18 is respectively connected in parallel with a plurality of solenoid valves, the liquid outlet end of the system pressure control valve 18 is connected to a plurality of oil circuits, and the plurality of solenoid valves are preferably switch valves, which realize the solenoid valves being powered on and off, and controlling the wet clutch to be engaged or separated. Among them, the plurality of solenoid valves can be a power output control valve 19, a four-wheel drive control valve 20, and a differential lock control valve 21, and the electro-hydraulic control valve group 6 is provided with a P port 25, a PT0 port 29, a 4WD port 30, and a DL port 31. The P port 25 serves as the liquid inlet of the electro-hydraulic control valve group 6, the liquid inlet end of the P port 25 is connected to the gear pump 3, and the liquid outlet end of the P port 25 is respectively connected to the system pressure control valve 18, the power output control valve 19, the four-wheel drive control valve 20, the differential lock control valve 21, and the emptying reversing valve 22. The liquid inlet of the system pressure control valve 18 is arranged between the liquid outlet of the P port 25 and the power output control valve 19, the four-wheel drive control valve 20, and the differential lock control valve 21; the liquid inlet of the emptying reversing valve 22 is connected to the power output control valve 19, the four-wheel drive control valve 20, and the differential lock control valve 21 respectively; the liquid outlet of the emptying reversing valve 22 and the liquid outlet of the system pressure control valve 18 are both connected to multiple oil circuits. The power output control valve 19 is connected to the power output wet clutch 8 via the PT0 port 29, the four-wheel drive control valve 20 is connected to the four-wheel drive wet clutch 9 via the 4WD port 30, and the differential lock control valve 21 is connected to the differential lock wet clutch 10 via the DL port 31.

[0051] In this embodiment, when the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 are not working, all the oil will overflow from the system pressure control valve 18 to the lubrication system or return to the oil tank, which will cause power loss, which will be converted into heat energy to cause the hydraulic oil temperature to rise, and then the oil will deteriorate, which will reduce the service life of the components. In order to reduce overflow loss, when the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 are not working, the emptying reversing valve 22 will continue to be energized, so that the oil will pass directly to the lubrication system or return to the oil tank through the emptying reversing valve 22, so that the gear pump 3 runs without load, that is, the oil output by the pump will all flow to the lubrication system or return to the oil tank at zero pressure or low pressure, so that power consumption can be saved, the heating of the system can be reduced, and the service life can be extended.

[0052] In another embodiment, if Figure 1 , Figure 2 As shown, on the basis of the above embodiment, the oil circuit includes a first oil return circuit, the first oil return circuit includes a lubrication pressure control valve 23 and a T-port 26 provided on the electro-hydraulic control valve group 6, the liquid inlet end of the lubrication pressure control valve 23 is respectively connected to the system pressure control valve 18 and the drain reversing valve 22, and the liquid outlet end of the lubrication pressure control valve 23 is connected to the oil tank 1 via the T-port 26 to form a circulation loop.

[0053] Furthermore, the oil circuit also includes a second transmission system lubricating oil circuit, which includes a Lub port 27 and a hydraulic radiator 13 provided on the electro-hydraulic control valve group 6. The liquid inlet end of the hydraulic radiator 13 is connected to the Lub port 27, and the liquid outlet end of the hydraulic radiator 13 is respectively connected to the power output control valve 19, the four-wheel drive control valve 20, and the differential lock control valve 21. The second transmission system lubricating oil circuit also includes: a transmission system lubricating damping plug 12, the liquid inlet end of the transmission system lubricating damping plug 12 is connected to the hydraulic radiator 13, and the liquid outlet end of the transmission system lubricating damping plug 12 is connected to the oil tank 1. The hydraulic radiator 13 is a device for cooling the oil in the hydraulic system. The oil performs efficient heat exchange with the forced cold air in the heat exchanger, so that the oil temperature is reduced to the working temperature to ensure that the system can continue to operate normally and the work can be carried out smoothly. One end of the transmission system lubricating damping plug 12 is connected to the hydraulic radiator 13, and the other end of the transmission system lubricating damping plug 12 is connected to the oil tank 1. After the oil is extracted from the oil tank 1, it enters from the P port 25 of the electro-hydraulic control valve group 6, and preferentially flows through the right position of the emptying reversing valve 22. Regardless of whether the power output control valve 19, the four-wheel drive control valve 20, and the differential lock control valve 21 are in the on state, the oil flows out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively, and lubricates the transmission system through the transmission system lubrication damping plug 11, and then enters the oil tank 1 to form a circulation loop.

[0054] Furthermore, the oil circuit also includes a third gear pump lubricating oil circuit, which includes a gear pump lubricating throttle valve 24, an LG port 28 and a gear pump lubricating damping plug 11. The inlet end of the gear pump lubricating throttle valve 24 is respectively connected to the system pressure control valve 18 and the emptying reversing valve 22, and the outlet end of the gear pump lubricating throttle valve 24 is connected to the LG port 28. The gear pump lubricating throttle valve 24 and the LG port 28 are arranged in the electro-hydraulic control valve group 6, and the LG port 28 is connected to the oil tank 1 through the gear pump lubricating damping plug 11. After the oil is drawn out from the oil tank 1, it enters from the P port 25 of the electro-hydraulic control valve group 6, and preferentially passes through the right position diversion of the emptying reversing valve 22. Regardless of whether the power output control valve 19, the four-wheel drive control valve 20, and the differential lock control valve 21 are in the on state, the oil passes through the gear pump lubricating throttle valve 24, comes out from the LG port 28 of the electro-hydraulic control valve group 6, lubricates the gear pump 3, and then enters the oil tank to form a circulation loop. It provides forced lubrication for the transmission mechanism of the transmission system and also provides lubrication for the gear pump 3 on the gearbox.

[0055] Furthermore, a wet clutch lubricating oil circuit is provided on the third gear pump lubricating oil circuit and / or the second transmission system lubricating oil circuit, and the liquid outlet ends of the wet clutch lubricating oil circuit are respectively connected to the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10.

[0056] Preferably, the liquid inlet end of the wet clutch lubrication oil circuit is connected between the hydraulic radiator 13 and the transmission system lubrication damping plug 12, and the liquid outlet end is respectively connected to the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10, to provide lubrication for each wet clutch and at the same time ensure that the lubricating oil is cold oil to improve the lubrication effect on the wet clutch.

[0057] In another embodiment, if Figure 1 , Figure 2 As shown, on the basis of the above embodiment, the tractor low-voltage electro-hydraulic control system also includes: a power output accumulator 7, and the PTO port 21 is connected to the power output wet clutch 8 through the power output accumulator 7. The power output accumulator 7 is used to buffer the power output wet clutch 8 when it is separated and connected. Under normal circumstances, when the tractor frequently connects power output, it has a greater impact on the hydraulic system, which is easy to cause damage to the power output wet clutch 8. The driver also feels the sense of frustration during operation, which reduces the control experience. The power output accumulator 7 is an accumulator that buffers the separation and combination of the power output wet clutch 8. When the power output wet clutch 8 is connected and separated, the load of the power output connection will feedback the impact to the tractor, which will cause the hydraulic system to fluctuate. The power output accumulator 7 can absorb and release the impact caused by the connection and separation of the power output wet clutch 8, play a buffering role on the hydraulic system, and make the power output connection more stable. As an auxiliary power source, it can reduce the power of the pump, improve efficiency, reduce temperature rise, save energy, and reduce system energy loss and heat caused by it.

[0058] Furthermore, if Figure 1 As shown, the tractor low-pressure electro-hydraulic control system also includes: an oil suction filter and a pressure oil circuit oil filter 4. One end of the oil suction filter 2 is connected to the oil tank 1, the other end of the oil suction filter 2 is connected to the gear pump 3, one end of the pressure oil circuit oil filter 4 is connected to the gear pump 3, and the other end of the pressure oil circuit oil filter 4 is connected to the P port 25. By installing the oil suction filter 2 at the oil suction port of the gear pump 3, the gear pump 3 and other hydraulic components are protected to avoid the inhalation of polluting impurities, effectively control the pollution of the hydraulic system, and adjust the cleanliness of the hydraulic system. The main function of the pressure oil circuit oil filter 4 is to filter the oil. Various impurities are inevitably present in the hydraulic system. The cleanliness of the oil can be further improved by the pressure oil circuit oil filter 4.

[0059] Furthermore, if Figure 1As shown, the tractor low-pressure electro-hydraulic control system also includes: a clutch boost system, a brake boost system and a boost accumulator 5. The clutch boost system is arranged between the pressure oil circuit filter 4 and the P port 25, and the clutch boost system includes a clutch booster master pump 14 and a clutch booster oil sub-cylinder 15. One end of the clutch booster master pump 14 is connected to the pressure oil circuit filter 4, and the other end of the clutch booster master pump 14 is connected to the clutch booster oil sub-cylinder 15. The brake boost system is arranged between the pressure oil circuit filter 4 and the P port 25, and the brake boost system includes a brake booster master pump 16 and a brake booster oil sub-cylinder 15. One end of the brake booster master pump 16 is connected to the pressure oil circuit filter 4, and the other end of the brake booster master pump 16 is connected to the brake booster oil sub-cylinder 17. The booster accumulator 5 is arranged between the pressure oil circuit filter 4 and the P port 25, and is respectively connected to the clutch booster master pump 14 and the brake booster master pump 16. The booster accumulator 5 is used to provide temporary power for the clutch booster master pump 14 and the brake booster master pump 16.

[0060] Normally, when the tractor is not started, the clutch assist system and the brake assist system have no hydraulic power source and cannot provide assistance. The assist accumulator 5 is an accumulator that provides temporary power for the clutch assist system and the brake assist system, and stores hydraulic force when the tractor is running. When the tractor is not started, it replaces the gear pump 3 and serves as a temporary power source for the clutch assist system and the brake assist system. When the clutch assist system and the brake assist system need to work, it provides short-term hydraulic force to improve driving controllability and comfort.

[0061] In this embodiment, when the tractor is working normally, the power output control valve 19, the four-wheel drive control valve 20, and the differential lock control valve 21 are energized and triggered, and the corresponding oil circuits are connected, and the corresponding power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 are respectively engaged, and the corresponding mechanisms are driven to make the power output, four-wheel drive, and differential lock work. The power output control valve 19, the four-wheel drive control valve 20, and the differential lock control valve 21 lose power, and the corresponding oil circuits are closed, and the corresponding power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 are respectively separated, and the corresponding mechanisms stop working, so that the power output, four-wheel drive, and differential lock stop working. Then the emptying reversing valve 22 will be energized, so that the oil is directly passed to the lubrication system or the oil tank through the emptying reversing valve 22. When the clutch or brake pedal is pressed, the clutch booster master pump 14 and the brake booster master pump 16 will be linked to open the hydraulic booster system oil circuit, and the pressure oil will push the clutch booster sub-cylinder 15 and the brake booster sub-cylinder 17 to achieve the purpose of hydraulic boosting. When the clutch or brake pedal is released, the clutch booster master pump 14 and the brake booster master pump 16 will be linked to close the hydraulic booster system oil circuit, open the return oil circuit, and the hydraulic oil will return from the clutch booster sub-cylinder 15 and the brake booster sub-cylinder 17 to the oil tank 1. Then the emptying reversing valve 22 will be energized, so that the oil will pass directly to the lubrication system or return to the oil tank through the emptying reversing valve 22. The wet clutch hydraulic control and hydraulic booster device subsystems are independent and do not interfere with each other. When one of the two is working, the emptying reversing valve 22 is in a closed state. When both are not working, the emptying reversing valve 22 will be energized to reduce power loss.

[0062] The boost accumulator 5 is designed in the oil circuit of the clutch booster master pump 14 and the brake booster master pump 16. When the tractor is not started, the clutch booster system and the brake booster system have no hydraulic power source and cannot play a boosting role. However, under the effect of the stored pressure in the boost accumulator 5, the clutch booster master pump 14 and the brake booster master pump 16 still have a short-term power source, and the clutch booster oil cylinder 15 and the brake booster oil cylinder 17 still play a boosting role, improving driving controllability.

[0063] A power output accumulator 7 is designed on the oil circuit of the power output wet clutch 8. When the tractor is in normal operation, the power output will be connected to the agricultural implement. When the power output is frequently connected, it will cause a greater impact on the hydraulic system. Under the action of the power output accumulator 7, the impact caused by the power output load connection can be absorbed, playing a buffering role, making the power output connection more stable.

[0064] Designing an emptying reversing valve 22 in the electro-hydraulic control valve group 6 can prevent air from remaining in the hydraulic system, save power consumption, reduce system heating, and extend the service life of hydraulic components. When the tractor is initially assembled, placed for a long time, or repaired and maintained, the oil in the high position of the hydraulic system pipeline will flow to the low position due to the influence of its own weight, so that air will exist in the hydraulic pipeline. When there is air in the oil, after the hydraulic system is running, the air in the oil will affect the normal operation of the system. Under the action of the emptying reversing valve 22, when the tractor is started, the air in the system can be exhausted to ensure that there is no air in the hydraulic oil circuit when the system is working normally. When the wet clutch and the hydraulic booster are not working, all the oil will overflow from the system pressure control valve 18 in the electro-hydraulic control valve group 6 to the lubrication system or return to the oil tank, which will cause power loss, which will be converted into heat energy to cause the hydraulic oil temperature to rise, and then the oil will deteriorate, thus reducing the service life of the components. To reduce overflow losses, when the three wet clutches and the two hydraulic boosters are not working, the drain reversing valve 22 will continue to be energized, allowing the oil to pass directly to the lubrication system or the return tank through the drain reversing valve 22, allowing the gear pump 3 to run at no load, that is, all the oil output by the pump will flow to the lubrication system or the return tank at zero pressure or low pressure, thereby saving power consumption, reducing system heat generation, and extending service life.

[0065] In this embodiment, the specific oil circuit route of the tractor low-voltage electro-hydraulic control system is as follows:

[0066] (I) Oil drain route:

[0067] When the tractor is initially assembled, stored for a long time, or repaired, there will be air in the hydraulic pipeline. When starting the tractor, the hydraulic system needs to be exhausted. Figure 1 , Figure 2As shown, each component is in the initial state. When the tractor starts, the drain reversing valve 22 will be energized due to the start command, the electromagnetic coil will be attracted, and the oil channel will be converted to the connected state. The oil enters from the P port 25 of the electro-hydraulic control valve group 6 through the oil tank 1, the oil suction filter 2, the gear pump 3, the pressure oil filter 4, and the right position of the drain reversing valve 22. Regardless of whether the power output control valve 19, the four-wheel drive control valve 20, and the differential lock control valve 21 are in the connected state, one way passes through the gear pump lubrication throttle valve 24, comes out from the LG port 28 of the electro-hydraulic control valve group 6, lubricates the gear pump 3, and enters the oil tank 1 to form a circulation loop. The other way comes out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively; and lubricates the transmission system from the transmission system lubrication damping plug 12, and then enters the oil tank 1 to form a circulation loop. There is also a way to control the lubrication pressure through the lubrication pressure control valve 23, directly entering the oil tank 1 to form a circulation loop. At this time, the oil will circulate in the system pipeline without load, exhaust the air, and the air will not enter the wet clutches and booster cylinders. When the air is exhausted, if the power output control valve 19, the four-wheel drive control valve 20, the differential lock control valve 21, the clutch booster master pump 14, and the brake booster master pump 16 are all in the closed state, the emptying reversing valve 22 will continue to be energized, and all the oil will flow to the lubrication system or return to the oil tank, thereby reducing power consumption. When the air is exhausted, if one of the above components is in the connected state, the emptying reversing valve 22 will lose power.

[0068] (ii) Wet clutch working oil circuit route: Figure 1 , Figure 2 As shown, each component is in the initial state after starting the emptying.

[0069] 1. Power output control oil circuit route: When the power output control switch is turned off, the power output control valve 19 is in the power-off state, and the oil channel is in the closed state. The oil enters from the P port 25 of the electro-hydraulic control valve group 6 through the oil tank 1, the oil suction filter 2, the gear pump 3, the pressure oil circuit filter 4, and the drain reversing valve 22 after being drained. The oil is diverted to the right position of the drain reversing valve 22, one way passes through the gear pump lubrication throttle valve 24, and comes out from the LG port 28 of the electro-hydraulic control valve group 6. After lubricating the gear pump 3, it enters the oil tank 1 to form a circulation loop. Another way comes out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively; and lubricates the transmission system from the transmission system lubrication damping plug 12, and then enters the oil tank 1 to form a circulation loop. Another way passes through the lubrication pressure control valve 23 to control the lubrication pressure and directly enters the oil tank 1 to form a circulation loop.

[0070] When the power output control switch is turned on, the power output control valve 19 is in the energized state, and the oil channel is in the connected state. The oil enters from the P port 25 of the electro-hydraulic control valve group 6 through the oil tank 1, the oil suction filter 2, the gear pump 3, the pressure oil line filter 4, and passes through the system pressure control valve 18, and the system pressure is controlled within the low pressure range of 2±0.2MPa. At this time, the power output control valve 19 is in the connected state, the emptying reversing valve 22 loses power, and the oil channel is closed. The oil first passes through the right position of the power output control valve 19 to fill the power output accumulator 7 and the power output wet clutch 8. Since the power output accumulator 7 plays a shunt buffering role, the power output wet clutch 8 can be smoothly engaged. The remaining oil is then shunted through the system pressure control valve 18, passes through the gear pump lubrication throttle valve 24, comes out from the LG port 28 of the electro-hydraulic control valve group 6, lubricates the gear pump 3, and enters the oil tank 1 to form a circulation loop. Another route comes out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively; and lubricates the transmission system through the transmission system lubrication damping plug 12, and then enters the oil tank 1 to form a circulation loop. Another route passes through the lubrication pressure control valve 23 to control the lubrication pressure and directly enters the oil tank 1 to form a circulation loop.

[0071] When the power output control switch is closed again, the power output control valve 19 is in the power-off state, and the oil channel is in the closed state. The oil enters from the P port 25 of the electro-hydraulic control valve group 6 through the oil tank 1, the oil suction filter 2, the gear pump 3, the pressure oil filter 4, and the drain reversing valve 22 is powered again. The oil is diverted to the right position of the drain reversing valve 22, one way passes through the gear pump lubrication throttle valve 24, and comes out from the LG port 28 of the electro-hydraulic control valve group 6. After lubricating the gear pump 3, it enters the oil tank 1 to form a circulation loop. Another way comes out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively; and after lubricating the transmission system from the transmission system lubrication damping plug 12, it enters the oil tank 1 to form a circulation loop. Another way passes through the lubrication pressure control valve 23 to control the lubrication pressure and directly enters the oil tank 1 to form a circulation loop. The oil in the power output wet clutch 8 passes through the left position of the power output control valve 19, bypasses the system pressure control valve 18, and is diverted to various lubrication systems, and finally returns to the oil tank 1. At this time, the pressure oil in the power output accumulator 7 is also released through the left position of the power output control valve 19, which plays a diversion and buffering role, and the power output wet clutch 8 can be separated smoothly.

[0072] 2. Four-wheel drive control oil circuit route: When the four-wheel drive control switch is turned off, the four-wheel drive control valve 20 is in a power-off state, and the oil channel is in a closed state. The oil enters from the P port 25 of the electro-hydraulic control valve group 6 through the oil tank 1, the oil suction filter 2, the gear pump 3, the pressure oil circuit filter 4, and the drain reversing valve 22 after being drained. The oil is diverted to the right position of the drain reversing valve 22, one way passes through the gear pump lubrication throttle valve 24, and comes out from the LG port 28 of the electro-hydraulic control valve group 6. After lubricating the gear pump 3, it enters the oil tank 1 to form a circulation loop. Another way comes out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively; and after lubricating the transmission system from the transmission system lubrication damping plug 12, it enters the oil tank 1 to form a circulation loop. Another way passes through the lubrication pressure control valve 23 to control the lubrication pressure and directly enters the oil tank 1 to form a circulation loop.

[0073] When the four-wheel drive control switch is turned on, the four-wheel drive control valve 20 is in the energized state, and the oil channel is in the connected state. The oil enters from the P port 25 of the electro-hydraulic control valve group 6 through the oil tank 1, the oil suction filter 2, the gear pump 3, the pressure oil circuit filter 4, and passes through the system pressure control valve 18, and the system pressure is within the low pressure range of 2±0.2MPa. At this time, the four-wheel drive control valve 20 is in the connected state, the emptying reversing valve 22 loses power, and the oil channel is closed. The oil first passes through the right position of the four-wheel drive control valve 20 to fill the four-wheel drive wet clutch 9, and the remaining oil is then diverted through the system pressure control valve 18, passing through the gear pump lubrication throttle valve 24, and comes out from the LG port 28 of the electro-hydraulic control valve group 6. After lubricating the gear pump 3, it enters the oil tank 1 to form a circulation loop. Another route comes out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively; and lubricates the transmission system through the transmission system lubrication damping plug 12, and then enters the oil tank 1 to form a circulation loop. Another route passes through the lubrication pressure control valve 23 to control the lubrication pressure and directly enters the oil tank 1 to form a circulation loop.

[0074] When the four-wheel drive control switch is closed again, the four-wheel drive control valve 20 is in the power-off state, and the oil channel is in the closed state. The oil enters from the P port 25 of the electro-hydraulic control valve group 6 through the oil tank 1, the oil suction filter 2, the gear pump 3, the pressure oil filter 4, and the drain reversing valve 22 is powered again. The oil is diverted to the right position of the drain reversing valve 22, one way passes through the gear pump lubrication throttle valve 24, and comes out from the LG port 28 of the electro-hydraulic control valve group 6. After lubricating the gear pump 3, it enters the oil tank 1 to form a circulation loop. Another way comes out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively; and after lubricating the transmission system from the transmission system lubrication damping plug 12, it enters the oil tank 1 to form a circulation loop. Another way passes through the lubrication pressure control valve 23 to control the lubrication pressure and directly enters the oil tank 1 to form a circulation loop. The oil in the four-wheel drive wet clutch 9 passes through the left position of the four-wheel drive control valve 20, bypasses the system pressure control valve 18, and is diverted to various lubrication systems, and finally returns to the oil tank 1.

[0075] 3. Differential lock control oil circuit route: When the differential lock control switch is turned off, the differential lock control valve 21 is in the power-off state, and the oil channel is in the closed state. The oil enters from the P port 25 of the electro-hydraulic control valve group 6 through the oil tank 1, the oil suction filter 2, the gear pump 3, the pressure oil circuit filter 4, and the drain reversing valve 22 after being drained. The oil is diverted to the right position through the drain reversing valve 22, one way passes through the gear pump lubrication throttle valve 24, and comes out from the LG port 28 of the electro-hydraulic control valve group 6. After lubricating the gear pump 3, it enters the oil tank 1 to form a circulation loop. The other way comes out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively; and after lubricating the transmission system from the transmission system lubrication damping plug 12, it enters the oil tank 1 to form a circulation loop. Another path passes through the lubrication pressure control valve 23 to control the lubrication pressure and directly enters the oil tank 1 to form a circulation loop.

[0076] When the differential lock control switch is turned on, the differential lock control valve 21 is in the energized state, and the oil channel is in the connected state. The oil enters from the P port 25 of the electro-hydraulic control valve group 6 through the oil tank 1, the oil suction filter 2, the gear pump 3, the pressure oil line filter 4, and passes through the system pressure control valve 18 to control the system pressure within the low pressure range of 2±0.2MPa. At this time, the differential lock control valve 21 is in the connected state, the emptying reversing valve 22 loses power, and the oil channel is closed. The oil first passes through the right position of the differential lock control valve 21 to fill the differential lock wet clutch 10, and the remaining oil is then diverted through the system pressure control valve 18, passing through the gear pump lubrication throttle valve 24, and comes out from the LG port 28 of the electro-hydraulic control valve group 6. After lubricating the gear pump 3, it enters the oil tank 1 to form a circulation loop. Another route comes out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively; and lubricates the transmission system through the transmission system lubrication damping plug 12, and then enters the oil tank 1 to form a circulation loop. Another route passes through the lubrication pressure control valve 23 to control the lubrication pressure and directly enters the oil tank 1 to form a circulation loop.

[0077] When the differential lock control switch is closed again, the differential lock control valve 21 is in the power-off state, and the oil channel is in the closed state. The oil enters from the P port 25 of the electro-hydraulic control valve group 6 through the oil tank 1, the oil suction filter 2, the gear pump 3, the pressure oil filter 4, and the drain reversing valve 22 is powered again. The oil is diverted to the right position of the drain reversing valve 22, one way passes through the gear pump lubrication throttle valve 24, and comes out from the LG port 28 of the electro-hydraulic control valve group 6. After lubricating the gear pump 3, it enters the oil tank 1 to form a circulation loop. Another way comes out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively; and after lubricating the transmission system from the transmission system lubrication damping plug 12, it enters the oil tank 1 to form a circulation loop. Another way passes through the lubrication pressure control valve 23 to control the lubrication pressure and directly enters the oil tank 1 to form a circulation loop. The oil in the differential lock wet clutch 10 passes through the left position of the differential lock control valve 21, bypasses the system pressure control valve 18, is diverted to various lubrication systems, and finally returns to the oil tank 1.

[0078] (III) Hydraulic power-assisted working oil line:

[0079] 1. When the tractor starts, Figure 1 , Figure 2 As shown in the figure, each component is in the initial state after starting and draining. The hydraulic booster is in an independent working state, and the wet clutch is in a non-working state by default.

[0080] The oil passes through the oil tank 1, the oil suction filter 2, the gear pump 3, the pressure oil line filter 4, and at the same time fills the boost accumulator 5 to store hydraulic pressure. At the same time, it enters from the P port of the electro-hydraulic control valve group 6. At this time, the power output control valve 19, the four-wheel drive control valve 20, and the differential lock control valve 21 are in a closed state. The emptying reversing valve 22 is continuously energized after being emptied. The oil is diverted to the right position of the emptying reversing valve 22. One way passes through the gear pump lubrication throttle valve 24, and comes out from the LG port 28 of the electro-hydraulic control valve group 6. After lubricating the gear pump 3, it enters the oil tank 1 to form a circulation loop. The other way comes out from the Lub port 27 of the electro-hydraulic control valve group 6, passes through the hydraulic radiator 13, and lubricates the power output wet clutch 8, the four-wheel drive wet clutch 9, and the differential lock wet clutch 10 respectively; and lubricates the transmission system from the transmission system lubrication damping plug 12, and then enters the oil tank 1 to form a circulation loop. Another path passes through the lubrication pressure control valve 23 to control the lubrication pressure and directly enters the oil tank 1 to form a circulation loop.

[0081] When the clutch pedal is not pressed, the clutch booster master pump 14 is in the closed state. When the clutch pedal is pressed, the clutch booster master pump 14 is in the oil-connected state. The drain reversing valve 22 loses power and closes the oil channel. The oil enters from the P port 25 of the electro-hydraulic control valve group 6 through the oil tank 1, the oil suction filter 2, the gear pump 3, and the pressure oil circuit filter 4, and passes through the system pressure control valve 18 to control the system pressure within the low pressure range of 2±0.2MPa, and is diverted to each lubrication system or the return tank. At the same time, the clutch booster master pump 14 is used to fill the clutch booster cylinder 15 to play a boosting role. At the same time, the booster accumulator 5 is filled to store hydraulic pressure. When the clutch booster cylinder 15 is full of oil and the clutch pedal is pressed but not released. The clutch booster master pump 14 is in the oil-draining state, and the oil is released through the clutch booster master pump 14 and returns to the oil tank. The clutch booster master pump 14

[0082] 2. When the tractor does not start, Figure 1 , Figure 2 As shown, each component is in an initial state after being started and emptied, and the booster accumulator 5 has stored hydraulic pressure.

[0083] When the clutch pedal is not pressed, the clutch booster master pump 14 is in the closed state. When the clutch pedal is pressed, the clutch booster master pump 14 is in the oil-connected state. The pressure oil of the booster accumulator 5 is released through the middle position of the clutch booster master pump 14, acting as a temporary power source, and the clutch booster sub-cylinder 15 is filled with liquid, playing a boosting role. When the clutch booster sub-cylinder 15 is full of oil and the clutch pedal is pressed but not released, the clutch booster master pump 14 is in the oil-draining state, and the pressure oil of the booster accumulator 5 is released through the right position of the clutch booster master pump 14.

[0084] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0085] It should be noted that the above embodiments can be freely combined as needed. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention.

Claims

1. A tractor low-voltage electro-hydraulic control system, characterized in that: include: An oil tank, which serves as a tractor gearbox housing and is used to store oil; A gear pump, the gear pump is connected to the oil tank and is used to extract the oil; An electro-hydraulic control valve group, the electro-hydraulic control valve group is connected to the gear pump, the electro-hydraulic control valve group comprises a plurality of solenoid valves, the liquid inlet ends of the plurality of solenoid valves are connected to the oil output end of the gear pump, and the output ends of the plurality of solenoid valves are respectively connected to corresponding actuators; An emptying reversing valve, wherein the liquid inlet end of the emptying reversing valve is connected to the oil output end of the gear pump, and the liquid outlet end of the emptying reversing valve is connected to a plurality of oil circuits; A system pressure control valve, wherein a fluid inlet of the system pressure control valve is communicated with an oil fluid output of the gear pump, and a fluid outlet of the system pressure control valve is connected to the plurality of oil circuits; The multiple solenoid valves include a power output control valve, a four-wheel drive control valve and a differential lock control valve, and the electro-hydraulic control valve group is provided with a P port, a PT0 port, a 4WD port and a DL port; The P port serves as the liquid inlet of the electro-hydraulic control valve group, the liquid inlet end of the P port is connected to the gear pump, and the liquid outlet end of the P port is respectively connected to the liquid inlet ends of the system pressure control valve, the power output control valve, the four-wheel drive control valve, the differential lock control valve, and the emptying reversing valve; The power output control valve is used to connect with the power output wet clutch through the PT0 port, the four-wheel drive control valve is used to connect with the four-wheel drive wet clutch through the 4WD port, and the differential lock control valve is used to connect with the differential lock wet clutch through the DL port. When the power output wet clutch, the four-wheel drive wet clutch, and the differential lock wet clutch are not working, the drain reversing valve will continue to be energized, so that the oil passes directly to the lubrication system or the oil return tank through the drain reversing valve; The plurality of oil circuits include a first oil return circuit; The first oil return circuit includes a lubrication pressure control valve and a T port provided on the electro-hydraulic control valve group, the liquid inlet end of the lubrication pressure control valve is respectively connected to the system pressure control valve and the drain reversing valve, and the liquid outlet end of the lubrication pressure control valve is connected to the oil tank via the T port to form a circulation loop; The plurality of oil circuits also include a second transmission system lubricating oil circuit; The second transmission system lubricating oil circuit includes a Lub port and a hydraulic radiator provided on the electro-hydraulic control valve group, the liquid inlet end of the Lub port is respectively connected to the system pressure control valve and the emptying reversing valve, the liquid inlet end of the hydraulic radiator is connected to the liquid outlet end of the Lub port, the liquid outlet end of the hydraulic radiator is connected to the transmission system lubricating damping plug, and the liquid outlet end of the transmission system lubricating damping plug is connected to the oil tank; The plurality of oil circuits also include a third gear pump lubricating oil circuit; The third gear pump lubrication oil circuit includes a gear pump lubrication throttle valve, an LG port and a gear pump lubrication damping plug. The inlet end of the gear pump lubrication throttle valve is respectively connected to the system pressure control valve and the exhaust reversing valve, and the outlet end of the gear pump lubrication throttle valve is connected to the LG port; the gear pump lubrication throttle valve and the LG port are arranged in the electro-hydraulic control valve group, and the LG port is connected to the oil tank through the gear pump lubrication damping plug.

2. The tractor low-voltage electro-hydraulic control system according to claim 1, characterized in that: A wet clutch lubricating oil circuit is provided in the third gear pump lubricating oil circuit and / or the second transmission system lubricating oil circuit, and the liquid outlet end of the wet clutch lubricating oil circuit is respectively connected to the power output wet clutch, the four-wheel drive wet clutch, and the differential lock wet clutch.

3. The tractor low-voltage electro-hydraulic control system according to claim 1, characterized in that: Also includes: Power take-off accumulator; The PTO port is connected to the power output wet clutch through the power output accumulator, and the power output accumulator is used to play a buffering role when the power output wet clutch is separated and engaged.

4. The tractor low-voltage electro-hydraulic control system according to claim 3, characterized in that: Also includes: A clutch boost system, the clutch boost system is arranged between the oil output end of the gear pump and the P port, the clutch boost system comprises a clutch booster master pump and a clutch booster oil sub-cylinder, one end of the clutch booster master pump is connected to the liquid outlet end of the pressure oil circuit oil filter, and the other end of the clutch booster master pump is connected to the clutch booster oil sub-cylinder; And / or, a brake booster system, which is arranged between the pressure oil circuit filter and the P port, and includes a brake booster master pump and a brake booster sub-cylinder, one end of the brake booster master pump is connected to the liquid outlet end of the pressure oil circuit filter, and the other end of the brake booster master pump is connected to the brake booster sub-cylinder.

5. The tractor low-voltage electro-hydraulic control system according to claim 4, characterized in that: Also includes: Booster accumulator; The booster accumulator is arranged between the pressure oil circuit filter and the P port, and is respectively connected to the clutch booster master pump and / or the brake booster master pump. The booster accumulator is used to provide temporary power for the clutch booster master pump and / or the brake booster master pump.

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