A new tractor hydraulic oil suction system

Abstract

The application relates to a tractor hydraulic oil suction system, which comprises a rear axle housing and a hydraulic auxiliary oil tank, the rear axle housing is connected with the hydraulic auxiliary oil tank through a communication pipe, the hydraulic auxiliary oil tank is connected with an oil suction filter through a pipeline, the oil suction filter is connected with a duplex pump through a pipeline; a multi-way valve, an oil inlet of the multi-way valve is connected with an oil outlet of one pump in the duplex pump through a pipeline, an oil outlet of the multi-way valve is connected with an oil inlet of an oil return filter through an oil return filter oil inlet pipe, and the oil return filter is connected with an inclined oil supplementing device through an oil pipe pipeline. The structure provided by the application has the application effect that the hydraulic auxiliary oil tank is similar to the design of an independent oil tank, the system oil cleanliness is greatly improved, the hydraulic parts are protected, the maintenance cost is reduced, the application of the inclined oil supplementing device can effectively improve the safety and reliability of the equipment system, and the negative pressure respirator can make a timely response to the working condition at high rotating speed.

Description

Technical Field

[0001] This application relates to the field of tractor technology, and in particular to a novel hydraulic oil suction return system for tractors. Background Technology

[0002] Currently, based on the relationship between the tractor hydraulic system and the transmission, hydraulic systems can be divided into combined hydraulic systems that share oil with the transmission fluid and independent hydraulic systems that use independent hydraulic oil tanks. Independent hydraulic systems are unaffected by metal filings from the transmission, heat generated by gear rotation, and air bubbles, effectively protecting the hydraulic components. Most domestic tractor manufacturers now widely adopt independent hydraulic systems in mechanically shifting models to improve reliability, reduce maintenance costs, and increase sales. However, the placement of the critical component, the hydraulic oil tank, is easily limited by the overall machine space, making it difficult to make the tank larger to meet the needs of driving more complex agricultural implements. This problem is particularly pronounced in high-horsepower tractors. Even if some manufacturers make the hydraulic oil tank very large, it still occupies a significant amount of space, making the overall layout very cramped and greatly increasing the difficulty of subsequent maintenance.

[0003] The combined oil system can avoid this problem. After sharing the same oil with the chassis, the hydraulic oil can also lubricate the chassis gears during the return oil. At the same time, it can also reduce the temperature of the chassis oil through the heat sink, avoiding the problem of overheating in the transmission system. In addition, current models with power shift, CVT and other shifting methods all use the combined oil system with shared oil. The application of the combined oil system can reduce the number of pipelines, improve the appearance quality of the whole machine and save manufacturing costs.

[0004] As mentioned above, foreign brands have already mastered the application of shared oil systems, but their application in China is not widespread, and some difficulties and problems have not yet been fully resolved.

[0005] Firstly, the cleanliness of the hydraulic oil is a primary concern. Using a shared oil system with the chassis introduces contaminants such as iron filings from the gears and fine particles from the casing itself into the hydraulic system, significantly increasing the failure rate and reducing the lifespan of hydraulic components. Many manufacturers experience malfunctions even shortly after prototype production, such as stuck multi-way valve cores and short-term alarms from the suction filter. The root cause is poor oil cleanliness, failing to meet the requirements of system components. Secondly, another crucial factor is the large amount of air bubbles generated by gear rotation. Due to the shared oil system, these bubbles also enter the hydraulic system through the pipelines, leading to abnormal noises and system instability. Thirdly, the shared oil system results in a higher chassis oil volume compared to independent oil usage. This significantly increases gear transmission resistance and reduces transmission efficiency. Furthermore, the increased heat generated by gear rotation can cause overheating of the chassis. Therefore, we propose a new tractor hydraulic suction oil system. Summary of the Invention

[0006] This application provides a tractor hydraulic oil suction return system to solve the problems mentioned above.

[0007] In a first aspect, this application provides a tractor hydraulic oil suction and return system, comprising:

[0008] The rear axle housing and the hydraulic auxiliary oil tank are connected to the hydraulic auxiliary oil tank through a connecting pipe. The hydraulic auxiliary oil tank is connected to the suction filter through a pipe. The suction filter is connected to the dual pump through a pipe.

[0009] A multi-way valve, wherein the inlet of the multi-way valve is connected to the outlet of one of the pumps in the tandem pump via a pipeline, the outlet of the multi-way valve is connected to the return oil filter via the inlet pipe of the return oil filter, the return oil filter is connected to the tilting oil replenishment device via an oil pipe, and the tilting oil replenishment device is connected to the hydraulic auxiliary oil tank and the rear axle housing via the first return oil filter outlet pipe and the second return oil filter outlet pipe respectively;

[0010] A negative pressure breathing apparatus is installed on the upper side of the hydraulic auxiliary oil tank, and the negative pressure breathing apparatus is connected to the rear axle breathing apparatus through a breathing tube.

[0011] Preferably, the pipeline between the oil suction filter and the dual pump is provided with an oil suction flange, an oil suction hose, an oil suction steel pipe, and an oil suction hose in sequence.

[0012] Preferably, the connecting pipe is inserted into the pipe inside the hydraulic auxiliary oil tank and has a built-in oil pipe.

[0013] Preferably, the tilting oil replenishment device is a mechanical tilting oil replenishment device or an electrically controlled tilting oil replenishment device.

[0014] Preferably, the mechanical tilting oil replenishment device includes a fixed base, a connecting pipe, a connecting cavity, a connecting shaft, a lower pendulum and an upper pendulum. The fixed base is fixedly installed inside the hydraulic auxiliary oil tank. The connecting pipe is inserted into the middle of the upper side of the fixed base. The connecting cavity is opened on the lower side of the fixed base. The middle of the connecting cavity is connected to the lower pendulum and the upper pendulum through the connecting shaft.

[0015] Preferably, the lower pendulum and the upper pendulum are an integral structure, and the upper end of the upper pendulum movably seals the lower end of the connecting pipe.

[0016] Preferably, the upper end of the connecting pipe is connected to an oil pipe.

[0017] Preferably, the electrically controlled tilting oil replenishment device uses a solenoid valve with a tilt sensor. The solenoid valve receives a PWM pulse signal from a microprocessor. The microprocessor has reset and storage functions. The microprocessor is electrically connected to the tilt sensor. The tilt sensor is connected to a filter module. The filter module is connected to a power supply.

[0018] Preferably, the other pump of the dual pump is connected to the steering and cooling system via a pipeline.

[0019] Secondly, this application provides a tractor, including the tractor hydraulic oil return system described in the first aspect.

[0020] The technical solutions provided in this application have the following advantages compared with the prior art:

[0021] The structure provided in this application embodiment, with its hydraulic auxiliary oil tank suction application similar to a design with an independent oil tank, greatly improves the cleanliness of the system oil, protects hydraulic components, and reduces maintenance costs. Moreover, this suction method can also reduce the amount of air bubbles entering, as most air bubbles are isolated within the rear axle housing. Some air bubbles that enter the hydraulic auxiliary oil tank are separated to the surface of the hydraulic auxiliary oil tank through the internal oil pipe structure of the connecting pipe. Compared to directly suctioning oil from the rear axle housing, this significantly reduces the amount of air bubbles drawn in. The application of the tilting oil replenishment device ensures that the oil level in the hydraulic auxiliary oil tank is always maintained at a safe extraction level, guaranteeing normal oil suction from the dual pump. This effectively improves the safety and reliability of the equipment system. At the same time, the hydraulic auxiliary oil tank has a small installation space, allowing for unified planning of all control pipelines and facilitating pipeline layout. The negative pressure breather can respond promptly to high-speed operating conditions. Finally, the high-pressure oil pumped out by the dual pump is divided into two paths. One path goes to the steering system, and after completing the steering operation, the oil enters the cooling system for cooling. The cooled oil then returns to the rear axle housing, serving to cool the oil in the rear axle housing and lubricate the gears. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 System schematic diagram provided for embodiments of this application;

[0025] Figure 2 The system structure diagram provided for the embodiments of this application;

[0026] Figure 3 This is a diagram of the internal structure of the connecting pipe provided in an embodiment of this application;

[0027] Figure 4 This is an overall structural diagram of the mechanical tilting oil replenishment device provided in the embodiments of this application;

[0028] Figure 5 A cross-sectional view of the mechanical tilting oil replenishment device provided in the embodiments of this application;

[0029] Figure 6 A schematic diagram of the electrically controlled tilting oil replenishment device provided in the embodiments of this application.

[0030] In the diagram: 1. Dual pump; 2. Connecting pipe; 21. Built-in oil pipe; 3. Suction filter; 4. Rear axle housing; 5. Hydraulic auxiliary oil tank; 6. Return oil filter inlet pipe; 7. Multi-way valve; 8. Return oil filter; 9. Inclined oil replenishment device; 91. Fixed base; 92. Connecting pipe; 93. Connecting cavity; 94. Connecting shaft; 95. Lower pendulum; 96. Upper pendulum; 10. First return oil filter outlet pipe; 11. Second return oil filter outlet pipe; 12. Negative pressure breather; 13. Rear axle breather; 14. Suction flange; 15. Suction hose; 16. Suction steel pipe; 17. Suction hose; 18. Oil pipe. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] Various embodiments of this application may exist in the form of a range. It should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of this application. Therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated in this application, it means including any referenced number (fraction or integer) within the indicated range. Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this application can be purchased commercially or prepared using existing equipment.

[0033] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in this application, the terms "comprising," "including," etc., mean "including but not limited to." In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this application, "and / or" describes the relationship between related objects, indicating that three relationships may exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this application, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of a single item or a plural item. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab, i.e., a and b, ac, bc, or abc, where a, b, and c can be a single or multiple.

[0034] like Figures 1 to 6 As shown: This application provides a new hydraulic oil suction and return system for tractors, including:

[0035] The rear axle housing 4 and the hydraulic auxiliary oil tank 5 are connected to the hydraulic auxiliary oil tank 5 through a connecting pipe 2. The hydraulic auxiliary oil tank 5 is connected to the suction filter 3 through a pipe. The suction filter 3 is connected to the double pump 1 through a pipe.

[0036] A multi-way valve 7 has its inlet connected to the outlet of one of the two pumps in the tandem pump 1 via a pipe. The other pump in the tandem pump 1 is connected to the steering and cooling system via a pipe. The outlet of the multi-way valve 7 is connected to the return oil filter 8 via the return oil filter inlet pipe 6. The return oil filter 8 is connected to the tilting oil replenishment device 9 via the oil pipe 18. The tilting oil replenishment device 9 is connected to the hydraulic auxiliary oil tank 5 and the rear axle housing 4 via the first return oil filter outlet pipe 10 and the second return oil filter outlet pipe 11, respectively.

[0037] A negative pressure respirator 12 is installed on the upper side of the hydraulic auxiliary oil tank 5, and the negative pressure respirator 12 is connected to the rear axle respirator 13 through a breathing tube.

[0038] Specifically: The rear axle breather 13 is installed inside the rear axle housing 4. To prevent air intake and the increased hydraulic oil demand due to increased engine speed, the second measure is to increase the oil suction capacity of the dual pump 1. On level roads, the tilting oil replenishment device 9 is closed, and the oil replenishment speed in the hydraulic auxiliary oil tank 5 is slow due to pressure difference and connecting pipes. This makes it difficult to ensure the normal operation of the hydraulic system and implements. Therefore, we specifically developed a "negative pressure breather." The negative pressure breather 12 is installed on the upper end of the hydraulic auxiliary oil tank 5, and the other end is connected to the rear axle housing 4 via a breather pipe. The bridge breather 13 is connected, and the working principle of the negative pressure breather 12 is "open when there is negative pressure and close when there is positive pressure". This principle ensures that the negative pressure breather 12 is closed when the dual pump 1 starts to work, thereby forming a closed oil tank in the hydraulic auxiliary oil tank 5, increasing the oil suction capacity of the dual pump 1, and ensuring the normal operation of the system and the equipment. When the oil in the hydraulic auxiliary oil tank 5 sloshes and generates positive pressure or the dual pump 1 stops working, the negative pressure breather 12 opens and connects to the rear axle breather 13 through the breathing pipe to discharge the gas. The dual pump 1 adopts a pump body that is already available on the market.

[0039] according to Figure 2 As shown: The pipeline between the oil suction filter 3 and the dual pump 1 is sequentially provided with an oil suction flange 14, an oil suction hose 15, an oil suction steel pipe 16, and an oil suction hose 17.

[0040] Specifically: the oil suction flange 14, oil suction hose 15, oil suction steel pipe 16, and oil suction hose 17 all use equipment that is already available on the market.

[0041] according to Figure 1 and Figure 3 As shown: The connecting pipe 2 is inserted into the pipe inside the hydraulic auxiliary oil tank 5 and has an internal oil pipe 21.

[0042] Specifically: the built-in oil pipe 21 can separate air bubbles in the oil.

[0043] according to Figure 4 , Figure 5 and Figure 6 As shown: The tilting oil replenishment device 9 is either a mechanical tilting oil replenishment device or an electrically controlled tilting oil replenishment device.

[0044] according to Figure 1 , Figure 2 , Figure 4 and Figure 5As shown: The mechanical tilting oil replenishment device includes a fixed base 91, a connecting pipe 92, a connecting cavity 93, a connecting shaft 94, a lower pendulum 95, and an upper pendulum 96. The fixed base 91 is fixedly installed inside the hydraulic auxiliary oil tank 5. The connecting pipe 92 is inserted into the middle of the upper side of the fixed base 91. The connecting cavity 93 is opened on the lower side of the fixed base 91. The middle of the connecting cavity 93 is connected to the lower pendulum 95 and the upper pendulum 96 through the connecting shaft 94. The lower pendulum 95 and the upper pendulum 96 are an integral structure. The upper end of the upper pendulum 96 movably seals the lower end of the connecting pipe 92. The upper end of the connecting pipe 92 is connected to the oil pipe 18.

[0045] Specifically, the mechanical oil replenishment device mainly consists of important components such as a fixed base 91, a lower pendulum 95, an upper pendulum 96, and a connecting shaft 94. Figure 4 and Figure 5 As shown, the return oil from the multi-way valve 7 splits into two paths after exiting the return oil filter outlet pipe 6. The first path is directly connected to the rear axle housing 4, allowing the return oil from the multi-way valve 7 to return directly to the rear axle housing 4. The second path is connected to the top of the mechanical tilting oil replenishment device, as shown in the diagram. Figure 2 As shown, the mounting base 91 of the mechanical tilting oil replenishment device is fixed inside the upper part of the hydraulic auxiliary oil tank 5. When the vehicle is driving normally on a road with a small or level slope, the lower pendulum 95 and the upper pendulum 96 in the mechanical tilting oil replenishment device are in a neutral position. In this state, the upper ends of the lower pendulum 95 and the upper pendulum 96 seal the oil inlet of the connecting pipe 92 on the mounting base 91, so that the mechanical tilting oil replenishment device is in a closed state. At this time, the return oil from the multi-way valve 7 will return to the rear axle housing 4 through the first path and will not enter the hydraulic auxiliary oil tank 5. However, when the vehicle is on a slope with a large slope, the lower pendulum 95 and the upper pendulum 96 will rotate around the connecting shaft 94 due to the tilt, opening the oil inlet of the connecting pipe 92 on the mounting base 91. In this way, the return oil from the multi-way valve 7 returns to the rear axle housing 4 and part of the return oil enters the hydraulic auxiliary oil tank 5 to replenish the hydraulic auxiliary oil tank 5 in time, ensuring the normal oil suction of the dual pump 1.

[0046] Several points need attention when using a mechanical oil replenishment device. First, it's crucial to be aware of the occasional opening or closing of the oil level caused by the back-and-forth swing of the lower pendulum 95 and upper pendulum 96 during vehicle bumps and sudden braking. Also, attention must be paid to the sealing between the lower pendulum 95 and upper pendulum 96 and the mounting base 91 to prevent oil leakage due to poor sealing on normal roads. To address these issues, a detailed design of the lower pendulum 95, upper pendulum 96, and mounting base 91 is necessary. Regarding the occasional opening and closing caused by bumps, limiting springs can be added to both sides of the upper part of the integrated structure formed by the lower pendulum 95 and upper pendulum 96. When the vehicle bumps, the lower pendulum 95 and upper pendulum 96 are subjected to... The limiting spring reduces sway. Additionally, the fan-shaped angle at the upper end of the upper pendulum 96 can be appropriately increased to further prevent bumps. Simultaneously, the lower end of the lower pendulum 95 needs to be checked for quality in conjunction with the opening angle of the oil replenishment device and the clamping force of the limiting spring. This ensures that the lower pendulum 95 and upper pendulum 96 can smoothly overcome resistance and open the mechanical oil replenishment device at the required tilt angle. Secondly, the sealing between the lower pendulum 95 and upper pendulum 96 and the fixed base 91 requires strict control of the surface roughness. Furthermore, the fit clearance between the connecting shaft 94 and the fixed base 91, as well as between the lower pendulum 95 and upper pendulum 96, must strictly adhere to design requirements. Meeting these two requirements will greatly improve the performance of the mechanical oil replenishment device.

[0047] according to Figure 1 , Figure 2 and Figure 6 As shown: The electrically controlled tilting oil replenishment device uses a solenoid valve with a tilt sensor. The solenoid valve receives PWM pulse signals from a microprocessor. The microprocessor has reset and storage functions. The microprocessor is electrically connected to the tilt sensor. The tilt sensor is connected to a filter module. The filter module is connected to the power supply.

[0048] Specifically: The electronically controlled tilt-type oil replenishment device uses a combination of tilt angle sensors to better control the on / off state of the device. It mainly consists of a tilt angle sensor, a microprocessor, and solenoid valves. The electronic control logic diagram of the electronically controlled tilt-type oil replenishment device is as follows: Figure 6 As shown, the basic principle is that the tilt sensor transmits the obtained position feedback signal to the microprocessor, and then the microprocessor controls the solenoid valve to open and close in the form of a PWM pulse signal. The specific implementation method is as follows:

[0049] The tilt sensors are installed in two relatively safe locations at the front and rear of the unit and connected to the power cord. It is recommended to install one tilt sensor at the front and one at the rear for better detection of the vehicle's tilt and sag, achieving more precise control. The microprocessor is then fixed in place. The solenoid valve assembly is positioned similarly to that of the mechanical tilt-assisted oil replenishment device, installed between the first return oil filter pipe 10 and the hydraulic auxiliary oil tank 5. The difference from the mechanical type is that it does not need to be installed inside the hydraulic auxiliary oil tank 5. The tilt sensor hardware circuit system uses a microcontroller as its processing core. Two high-precision angle sensors measure the tilt angle in the X and Y planes and transmit the data to the microcontroller via the SPI bus. The microcontroller processes the data and transmits it to the solenoid valve via PWM pulse signals to control the opening and closing of the internal valve core. This allows for precise control of the hydraulic oil entering the hydraulic auxiliary oil tank 5 based on the vehicle's status, ensuring the normal operation of the dual pump 1. The electronically controlled tilt-assisted oil replenishment device avoids the effects of vehicle bumps and poor sealing, and its performance is significantly better than the mechanical tilt-assisted oil replenishment device. However, its disadvantage is the higher cost.

[0050] When the equipment is in use, the dual pump 1 draws hydraulic oil from the hydraulic auxiliary oil tank 5 through the suction filter 3, and is simultaneously connected to the rear axle housing 4 through the connecting pipe 2. This suction structure can effectively reduce the amount of impurity particles drawn in compared to directly drawing oil from the rear axle housing 4, thus improving the cleanliness of the system. Moreover, this suction method can also reduce the amount of air bubbles entering the system. Most air bubbles are isolated inside the rear axle housing 4, and some air bubbles that enter the hydraulic auxiliary oil tank 5 are separated to the surface of the hydraulic auxiliary oil tank 5 through the internal oil pipe 21 inside the connecting pipe 2. Compared to directly drawing oil from the rear axle housing 4, this can greatly reduce the amount of air bubbles drawn in. Meanwhile, the high-pressure oil pumped from the dual pump 1 is divided into two paths. One path goes to the steering system. After completing the steering operation, the oil enters the cooling system for cooling. The cooled oil then returns to the rear axle housing 4 to cool the oil in the rear axle housing 4 and lubricate the gears. The other path of oil from the dual pump 1 goes to the multi-way valve 7. After completing the operation, the hydraulic oil enters the tilting oil replenishment device 9 through the return oil filter 8. Under the action of the tilting oil replenishment device 9, the hydraulic oil returns to the hydraulic auxiliary oil tank 5 or the rear axle housing 4, thus completing the entire hydraulic system cycle.

[0051] A special note regarding this new system is how to prevent the hydraulic auxiliary oil tank 5 from cavitating under special operating conditions. The volume of the hydraulic auxiliary oil tank 5 is not particularly large and cannot independently meet the oil volume requirements of the hydraulic system. In common designs, the main and auxiliary oil tanks are often connected by a connecting pipe between the rear axle housing 4 and the bottom of the hydraulic auxiliary oil tank 5. However, this structure is limited by the diameter of the connecting pipe. If the pipe diameter is too small, when the engine speed is high and the system requires a large flow rate, the oil in the rear axle housing 4 cannot be replenished in time and can easily be cavitated. This places strict requirements on the diameter of the connecting pipe. Even if the diameter issue is resolved, when the vehicle is on a steep incline, the oil will tilt to the rear, making it difficult to guarantee a safe oil suction effect. To address the above problems, this system has taken two measures. The first is to add a tilting oil replenishment device 9. This paper proposes two solutions for the tilting oil replenishment device 9: a mechanical oil replenishment device and an electronically controlled oil replenishment device.

[0052] Based on the same inventive concept, this application also provides a tractor, including the tractor hydraulic oil suction return system described above.

[0053] Since this tractor includes the aforementioned hydraulic oil suction system, it adopts some or all of the technical solutions of the aforementioned hydraulic oil suction system embodiment, and therefore has at least all the beneficial effects brought about by the technical solutions of the aforementioned embodiments, which will not be elaborated here.

[0054] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. 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 this application. Therefore, this application 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 claimed in this application.

Claims

1. A tractor hydraulic oil suction return system, characterized in that, include: The rear axle housing (4) and the hydraulic auxiliary oil tank (5) are connected to the hydraulic auxiliary oil tank (5) through a connecting pipe (2). The hydraulic auxiliary oil tank (5) is connected to the suction filter (3) through a pipe. The suction filter (3) is connected to the double pump (1) through a pipe. A multi-way valve (7) is provided. The inlet of the multi-way valve (7) is connected to the outlet of one of the pumps in the tandem pump (1) via a pipe. The outlet of the multi-way valve (7) is connected to the return oil filter (8) via the return oil filter inlet pipe (6). The return oil filter (8) is connected to the tilting oil replenishment device (9) via the oil pipe (18). The tilting oil replenishment device (9) is connected to the hydraulic auxiliary oil tank (5) and the rear axle housing (4) via the first return oil filter outlet pipe (10) and the second return oil filter outlet pipe (11), respectively. A negative pressure respirator (12) is installed on the upper side of the hydraulic auxiliary oil tank (5), and the negative pressure respirator (12) is connected to the rear axle respirator (13) through a breathing tube. The oil suction filter (3) and the dual pump (1) are connected in sequence to an oil suction flange (14), an oil suction hose (15), an oil suction steel pipe (16) and an oil suction hose (17). The connecting pipe (2) is inserted into the pipe inside the hydraulic auxiliary oil tank (5) and has an internal oil pipe (21).

2. The tractor hydraulic oil suction and return system according to claim 1, characterized in that: The tilting oil replenishment device (9) is either a mechanical tilting oil replenishment device or an electrically controlled tilting oil replenishment device.

3. The tractor hydraulic oil suction and return system according to claim 2, characterized in that: The mechanical tilting oil replenishment device includes a fixed base (91), a connecting pipe (92), a connecting cavity (93), a connecting shaft (94), a lower pendulum (95), and an upper pendulum (96). The fixed base (91) is fixedly installed inside the hydraulic auxiliary oil tank (5). The connecting pipe (92) is inserted into the middle of the upper side of the fixed base (91). The connecting cavity (93) is opened on the lower side of the fixed base (91). The middle of the connecting cavity (93) is connected to the lower pendulum (95) and the upper pendulum (96) through the connecting shaft (94).

4. A tractor hydraulic oil suction and return system according to claim 3, characterized in that: The lower pendulum (95) and the upper pendulum (96) are an integral structure, and the upper end of the upper pendulum (96) is movably sealed to the lower end of the connecting pipe (92).

5. A tractor hydraulic oil suction and return system according to claim 3, characterized in that: The upper end of the connecting pipe (92) is connected to the oil pipe (18).

6. A tractor hydraulic oil suction and return system according to claim 2, characterized in that: The electrically controlled tilting oil replenishment device uses a solenoid valve with a tilt sensor. The solenoid valve receives PWM pulse signals from a microprocessor. The microprocessor has reset and storage functions. The microprocessor is electrically connected to the tilt sensor. The tilt sensor is connected to a filter module. The filter module is connected to the power supply.

7. A tractor hydraulic oil suction and return system according to claim 1, characterized in that: The other pump of the dual pump (1) is connected to the steering and cooling system via a pipeline.

8. A tractor comprising a tractor hydraulic oil return system as described in any one of claims 1-7.

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