A multi-stage priority load-sensitive hydraulic control system and tractor

Abstract

The utility model relates to tractor hydraulic control field, more particularly, a kind of multistage priority load-sensitive hydraulic control system and tractor, comprising: hydraulic oil suction filter, set to hydraulic oil tank export end;Load-sensitive pump, suction hydraulic oil by hydraulic oil suction filter, can automatically adjust output flow and pressure according to system load variation;Multistage priority control valve, connect in the oil outlet of load-sensitive pump, for distributing hydraulic oil to different function module according to preset priority order;Wherein, function module includes: steering system, brake system, chassis walking control system and hydraulic lifting system, steering system is first level.It can provide unified and accurate hydraulic power distribution and adjustment basis for each function module on tractor according to preset priority order, ensure that each module realizes efficient collaborative operation.

Description

Technical Field

[0001] This utility model relates to the field of tractor hydraulic control, specifically to a multi-level priority load-sensitive hydraulic control system and a tractor. Background Technology

[0002] With the rapid development of agricultural mechanization, the energy consumption of tractors, as the mainstay of agricultural production, has become a focus of industry attention. Currently, load-sensitive systems in tractors are mainly applied to hydraulic lifting and steering systems, achieving a certain degree of energy saving and efficiency improvement in these two key components. However, in terms of chassis control, most tractors still use a fixed-displacement system.

[0003] During operation, the oil pump continuously supplies oil at a constant rate, and the output cannot be flexibly adjusted regardless of changes in the actual load. This results in a large amount of energy being wasted in the overflow stage, which greatly reduces energy utilization efficiency and causes the tractor's energy consumption to remain high.

[0004] Researching a load-sensitive system suitable for chassis control is of great significance for reducing the overall energy consumption of tractors. It not only adjusts the oil pump output in real time according to the actual load, reducing unnecessary energy waste and lowering user operating costs, but also aligns with the global trend of energy conservation and emission reduction. From an environmental perspective, reduced energy consumption means reduced emissions of pollutants such as carbon dioxide and nitrogen oxides from fuel combustion. This is of paramount importance for mitigating the greenhouse effect, reducing air pollution, and promoting the green and sustainable development of agricultural machinery. Utility Model Content

[0005] The purpose of this invention is to provide a multi-level priority load-sensitive hydraulic control system, which can provide a unified and precise hydraulic power distribution and adjustment basis for each functional module on the tractor according to a preset priority order, ensuring efficient collaborative operation between the modules.

[0006] Another objective of this invention is to provide a tractor that can provide a unified and precise hydraulic power distribution and adjustment basis for each functional module on the tractor according to a preset priority order, thereby ensuring efficient collaborative operation between the modules.

[0007] The technical solution of this utility model is implemented as follows: A multi-level priority load-sensitive hydraulic control system, applied to tractors, includes: A hydraulic suction filter is installed at the outlet end of the hydraulic oil tank; The load-sensitive pump draws in hydraulic oil through the hydraulic suction filter and can automatically adjust its output flow and pressure according to changes in system load. A multi-stage priority control valve is connected to the outlet of the load-sensitive pump and is used to distribute hydraulic oil to different functional modules according to a preset priority order. The functional modules include: steering system, braking system, chassis travel control system, and hydraulic lifting system; The multi-level priority control valve is hydraulically controlled and has multi-level priority control logic to divide multiple functional modules into different priorities. In an emergency, the multi-level priority control valve distributes hydraulic oil to multiple functional modules according to a preset priority order, and the steering system is the first level.

[0008] Furthermore, the multi-level priority control valve has a four-level priority control logic, with the steering system, braking system, chassis travel control system, and hydraulic lifting system respectively assigned as the first, second, third, and fourth levels according to a preset priority order, wherein: The first priority is to supply hydraulic fluid to the steering system, including the load-sensitive steering gear and steering cylinder; The second stage prioritizes supplying hydraulic oil to the braking system, including the trailer brake control valve, service brake control valve, brake cylinder, parking brake valve, and parking brake cylinder. The third priority is to supply hydraulic oil to the chassis travel control system, which includes the power shift mechanism and the PTO four-wheel drive differential valve. The fourth stage supplies the remaining hydraulic oil to the hydraulic lifting system; The multi-stage priority control valve responds and adjusts according to the highest load demand of each functional module and drives the load-sensitive pump.

[0009] Furthermore, the multi-stage priority control valve integrates a brake fluid filling valve, which is used to pre-pressurize the brake oil circuit before the braking action is initiated and maintain a stable oil pressure during the braking process, thereby improving the braking response speed and reliability.

[0010] Furthermore, it also includes a separately configured fixed displacement gear pump, which is dedicated to driving the chassis cooling system and lubrication bypass valve; The fixed displacement gear pump is separated from the main hydraulic circuit to avoid occupying the total oil source of the load-sensitive system and to ensure the stability of the main system's oil supply.

[0011] Furthermore, the outlet of the fixed displacement gear pump is connected to the main oil circuit of the load-sensitive pump through a confluence valve, which can realize the confluence of the two pumps under high load conditions, jointly providing additional hydraulic flow to the system and improving the system's peak oil supply capacity.

[0012] Furthermore, a temperature control valve is also provided to detect the temperature of the chassis hydraulic oil; When the oil temperature exceeds the set threshold, the temperature control valve opens, and a low-pressure, small-displacement pump is started to drive the cooling medium circulation; when the oil temperature returns to normal, the cooling circuit is automatically shut off to reduce energy loss.

[0013] Furthermore, the lubrication bypass valve is connected to the output branch of the fixed displacement gear pump to monitor the lubrication status of the hydraulic oil and adjust its flow direction, ensuring that the transmission components receive continuous and effective lubrication and preventing dry friction damage.

[0014] Furthermore, the load-sensitive pump integrates a large-displacement make-up oil pump, which provides stable oil replenishment to the main pump's suction chamber, enhances self-priming capability, prevents cavitation, and ensures stable oil supply to the system under inclined or high-speed operating conditions.

[0015] Furthermore, the load-sensitive steering gear and the steering cylinder form a closed-loop steering execution unit, which can accurately control the wheel steering angle according to the driver's operating instructions, thereby improving the vehicle's handling stability.

[0016] A tractor equipped with the aforementioned multi-level priority load-sensitive hydraulic control system for achieving energy-saving, safe, and efficient multi-functional collaborative operation and driving control.

[0017] Compared with the prior art, the beneficial effects of this utility model are: This solution designs a multi-level priority control valve and provides a multi-level priority control strategy. The steering system, due to its critical impact on operational safety and flexibility, is given the highest priority (level 1). Once steering action is initiated, the new load-sensitive system responds quickly, prioritizing sufficient hydraulic flow to the steering system through precise sensing and control mechanisms. This ensures the accuracy and smoothness of steering operations, allowing the driver to easily operate the tractor in various complex road conditions. The multi-level priority control valve distributes hydraulic oil to various functional modules according to a preset priority order, providing a unified and precise hydraulic power distribution and adjustment basis for modules such as steering, lifting, braking, and chassis control. This ensures efficient collaborative operation between modules. Similarly, each functional module on the tractor receives a unified and precise hydraulic power distribution and adjustment basis according to a preset priority order, ensuring efficient collaborative operation between modules. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1This is a schematic diagram of the multi-level priority load-sensitive hydraulic control system of this utility model.

[0020] In the picture: 1-Hydraulic suction filter; 2-Load-sensitive pump; 3-Multi-stage priority control valve; 4-Load-sensitive steering gear; 5-Steering cylinder; 6-Trailer brake control valve; 7-Service brake control valve; 8-Brake cylinder; 9-Parking brake valve; 10-Parking brake cylinder; 11-PTO four-wheel drive differential valve; 12-Chassis cooling system; 13-Temperature control valve; 14-Lubrication bypass valve; 15-Low-pressure small displacement pump. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0026] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0027] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] Example 1 Reference Figure 1 This embodiment provides a multi-level priority load-sensitive hydraulic control system for tractors, including: Hydraulic suction filter 1 is installed at the outlet end of the hydraulic oil tank. As the starting point of the system, hydraulic suction filter 1 bears the important responsibility of providing clean hydraulic oil for the entire system. With its efficient filtration mechanism, it can effectively filter out various impurities in the hydraulic oil, thereby creating a good operating environment for subsequent components and greatly extending the service life of the system. Load-sensitive pump 2 draws in hydraulic oil through hydraulic suction filter 1 and can automatically adjust its output flow and pressure according to changes in system load. Innovatively, load-sensitive pump 2 integrates a large-displacement replenishing pump. During system operation, the replenishing pump actively provides stable replenishment support to the plunger pump. In this way, the replenishing pump significantly enhances the plunger pump's self-priming capability, ensuring the plunger pump can always operate smoothly, thus laying a solid foundation for the stable operation of the entire system. The multi-stage priority control valve 3 is connected to the oil outlet of the load-sensitive pump 2. It adopts a multi-stage priority control strategy to distribute hydraulic oil to different functional modules according to a preset priority order. The system comprises multiple functional modules, including a steering system, a braking system, a chassis travel control system, and a hydraulic lifting system. Among these, a multi-level priority control valve 3 employs multi-level priority control logic to classify the multiple functional modules into different priorities. In emergency situations, the multi-level priority control valve 3 distributes hydraulic oil to the multiple functional modules according to a preset priority order. Through demand analysis and precise control of different functional modules, the system resources (hydraulic oil) are rationally allocated.

[0029] In this scheme, the multi-level priority control valve 3 is controlled hydraulically. It has a four-level priority control logic, which assigns the steering system, braking system, chassis travel control system, and hydraulic lifting system to the first, second, third, and fourth levels respectively according to a preset priority order. Level 1: Steering Priority: Steering operation plays a decisive role in the tractor's maneuverability in complex and ever-changing working environments. To ensure timely and accurate steering, this system independently sets the steering function priority to the highest level. When a steering demand arises, the system responds rapidly, prioritizing the allocation of sufficient hydraulic resources to the steering system through a dedicated sensing and control mechanism. This allows the steering system to obtain the necessary power immediately, achieving fast and precise steering operations and ensuring flexible adjustments to the tractor's direction of travel.

[0030] Level Two: Braking System Priority: The braking system is crucial to the tractor's driving safety, and its importance is self-evident. Therefore, the braking system is set as the second priority. This system includes several key components such as the trailer brake control valve 6, the service brake control valve 7, the brake cylinder 8, the parking brake valve 9, and the parking brake cylinder 10. It is worth mentioning that the multi-level priority control valve 3 integrates a brake filling valve, which plays a crucial role in the braking process. When braking demand is triggered, the system rationally and quickly allocates hydraulic resources to the corresponding braking components based on the braking type (such as service brake, parking brake, or trailer brake) and the actual urgency. Simultaneously, the brake filling valve precisely controls the braking pressure in real time. For example, during emergency service braking, the brake filling valve responds rapidly, ensuring that the brake cylinder 8 can quickly obtain sufficient and stable pressure, achieving a reliable braking effect, timely reducing vehicle speed, and ensuring driving safety.

[0031] Level 3: Chassis and Travel System Priority: The chassis and travel system, including the power shift system, involves power shifting and the PTO four-wheel drive differential valve 11, and is crucial for the tractor to achieve different driving states and operational needs. After meeting the priority requirements of the steering and braking systems, the system will allocate appropriate hydraulic resources to the chassis and travel system based on real-time operating conditions and load changes. When the tractor travels on different terrains or performs different tasks, the system can automatically sense and adjust the hydraulic flow to ensure smooth power shifting, adapting to the power demands of different road conditions and operating scenarios, and ensuring the stability of the tractor's driving and the efficiency of power output.

[0032] Level 4: Hydraulic Lifting System Priority: The hydraulic lifting system is responsible for tasks such as lifting agricultural implements. After satisfying the priority requirements of the first three functional modules, the system will rationally allocate remaining hydraulic resources to the hydraulic lifting system. Through precise pressure and flow control, the system ensures that the hydraulic lifting system can stably and accurately complete the lifting action according to the actual operational needs, guaranteeing the smooth progress of the lifting operation.

[0033] Load-sensitive steering gear 4 and steering cylinder 5: The load-sensitive steering gear 4 and steering cylinder 5 work closely together to achieve precise steering operation of the tractor. The load-sensitive steering gear 4 precisely controls the flow direction and volume of hydraulic oil based on the driver's intentions and the vehicle's driving status, thereby driving the steering cylinder 5. The steering cylinder 5 changes the steering angle of the wheels through its extension and retraction movement. The combined effect of these two components effectively improves the stability and agility of the vehicle, enabling the tractor to achieve precise steering in various complex road conditions.

[0034] Cooling and temperature control components: The chassis cooling system 12 is equipped with a low-pressure, small-displacement pump 15, which, together with the chassis oil temperature control valve 13, maintains a suitable operating temperature for the system. When the system detects an increase in chassis oil temperature, the temperature control valve 13 activates, and the low-pressure, small-displacement pump 15 begins operation. By circulating the cooling medium, excess heat generated by the system is dissipated, keeping the oil temperature within a reasonable range. When the oil temperature is low, the cooling system automatically stops working to avoid unnecessary energy consumption and ensure efficient system operation under various conditions.

[0035] Lubrication bypass valve 14: The lubrication bypass valve 14 plays a crucial role in regulating lubrication within the system. When the lubrication performance of the hydraulic oil in the system becomes abnormal due to various factors, the lubrication bypass valve 14 can promptly detect and respond. By adjusting the flow direction and flow rate of the hydraulic oil, it ensures that all components receive sufficient and good lubrication, effectively reducing wear between components, extending component service life, and guaranteeing the long-term stable operation of the system.

[0036] This design retains a gear pump for the fixed-displacement system. This gear pump is specifically designed for oil temperature cooling and lubrication systems. Due to its continuous operation and relatively low operating pressure, it is chosen as the power source for this subsystem. If the oil required for this cooling and lubrication system were entirely sourced from the complex variable-displacement system, it would consume the total oil supply of the variable-displacement system, thereby affecting the normal operation of other systems.

[0037] The gear pump operates independently, stably supplying the necessary oil to the cooling and lubrication systems. This meets the system's continuous operating requirements without interfering with the overall oil supply distribution of the variable displacement system. Notably, this fixed displacement system for controlling chassis cooling, while maintaining cost control, also features dual-pump confluence with the load-sensitive system. When the tractor is under high load conditions, and the hydraulic oil flow demand of each system increases, the fixed displacement pump and load-sensitive pump 2 can confluence. The hydraulic oil continuously and stably output by the fixed displacement pump and the hydraulic oil output adjusted by the load-sensitive pump 2 according to load changes converge to provide the system with more sufficient oil, meeting the flow requirements of each system under heavy loads and improving the overall system efficiency and performance. This dual-pump confluence design optimizes the system's oil supply capacity without significantly increasing costs, enabling the tractor to operate more efficiently under various working conditions.

[0038] Specifically: The first priority is to supply hydraulic oil to the steering system, including the load-sensitive steering gear 4 and the steering cylinder 5; The second stage prioritizes supplying hydraulic oil to the braking system, which includes trailer brake control valve 6, service brake control valve 7, brake cylinder 8, parking brake valve 9, and parking brake cylinder 10. The third priority is to supply hydraulic oil to the chassis travel control system, which includes the power shift mechanism and the PTO four-wheel drive differential valve 11. The fourth stage supplies the remaining hydraulic oil to the hydraulic lifting system; The multi-stage priority control valve 3 integrates a pressure feedback mechanism to sense the highest load demand of each functional module and drive the load-sensitive pump 2 to respond and adjust.

[0039] The load-sensitive steering gear 4 and the steering cylinder 5 form a closed-loop steering actuator, which can precisely control the wheel steering angle according to the driver's operating instructions, thereby improving the vehicle's handling stability.

[0040] The steering system, braking system, chassis travel control system and hydraulic lifting system share the same load-sensitive pump 2 and multi-stage priority control valve 3, eliminating the original decentralized quantitative pump structure, simplifying pipeline layout, reducing leakage risk and improving system integration and operational reliability.

[0041] In summary, "on-demand allocation" means that the system can sense in real time how much oil and pressure each functional module needs, and then direct the oil pump to output only the exact amount of oil required. When not needed, the output is reduced to avoid waste. In this solution, all high-energy-consuming parts of the tractor, such as steering, braking, gear shifting, and lifting implements, are connected to this "intelligent fuel-saving system," significantly reducing fuel consumption and heat generation.

[0042] The hydraulic control method for a multi-level priority load-sensitive hydraulic control system for a tractor includes the following steps: Real-time monitoring of whether the steering system issues a work request; if so, the first-level priority response is initiated, cutting off or reducing the oil supply ratio of other systems to prioritize the hydraulic oil flow required for steering. When a braking system activation signal is detected, the braking type and urgency level are determined, and a second-level priority response is triggered to quickly establish brake fluid pressure and stably supply brake cylinder 8. In the absence of a higher priority request, the hydraulic supply to the power shift mechanism and / or the four-wheel drive differential mechanism is adjusted according to the chassis's driving conditions to achieve third-level priority control. The remaining available hydraulic flow in the system is allocated to the hydraulic lifting system to complete operations such as lifting and lowering agricultural implements. The load-sensitive pump 2 generates a compensation signal based on the system's highest load demand pressure, adjusts its own displacement, and achieves on-demand energy output.

[0043] It should be noted that in current tractor variable displacement systems, the control mode of variable displacement pumps combined with priority valves is widely used. The priority valve, as a key component, cleverly connects the steering system and the lifting system. When the tractor is operating, if the steering system issues a work request, the priority valve responds quickly, prioritizing the distribution of hydraulic oil to the steering system to ensure smooth and precise steering, providing reliable control of the tractor's direction. After fully satisfying the steering system's needs, the remaining hydraulic oil flow will flow to the hydraulic working system to drive other operations such as implement lifting. This coordinated operation ensures the orderly operation of all tractor systems, improving work efficiency and safety. There is significant room for optimization in current tractor hydraulic control systems. In existing hydraulic control systems, the chassis control system encompasses key components such as chassis travel, power shift travel, and vehicle braking control, including service brake, parking brake, and trailer brake. These chassis and braking control components have not been effectively integrated with load-sensitive systems. Furthermore, the existing priority valve flow distribution method only applies to the steering and lifting systems, and cannot meet the needs of the chassis and braking systems for priority flow control in relation to the transmission system, which further limits the improvement of the overall performance of the tractor.

[0044] This solution breaks through traditional design concepts, creating a comprehensive load-sensitive system architecture through innovative technologies. This architecture abandons the traditional hybrid approach of using load sensors and fixed displacement pumps, constructing an integrated load-sensitive system. This new architecture becomes the core hub for all key functional modules of the tractor, providing a unified and precise hydraulic power distribution and adjustment basis for modules such as steering, lifting, braking, and chassis control, ensuring efficient collaborative operation between these modules.

[0045] To address the diverse functional requirements of tractors, this solution employs a meticulously designed multi-level priority control strategy. The steering system, due to its critical impact on operational safety and flexibility, is given the highest priority. Once steering is initiated, the new load-sensitive system responds rapidly, prioritizing sufficient hydraulic flow to the steering system through precise sensing and control mechanisms. This ensures accurate and smooth steering, allowing the driver to easily operate the tractor in various complex road conditions. The service brake, parking brake, and trailer brake systems have secondary priority. When braking is required, the system quickly and rationally allocates hydraulic resources based on the braking type (e.g., emergency braking, conventional braking) and the actual urgency. For example, in emergency braking, the system instantly provides maximum hydraulic support to the braking system, ensuring reliable braking performance and effectively protecting driving safety. The power shift and lifting systems in the chassis control system acquire appropriate hydraulic flow in an orderly manner, based on real-time operating conditions and load requirements, while prioritizing high-priority functional modules. This intelligent flow allocation method ensures stable operation of each functional module under different operating conditions, avoiding performance degradation or malfunctions caused by uneven flow distribution.

[0046] Through a sophisticated pressure and flow sensing feedback mechanism within the load-sensitive system, this solution successfully integrates steering, lifting, service braking, parking braking, trailer braking, and power shifting for chassis movement into a unified whole. The functional modules no longer operate independently but are interconnected and work in tandem.

[0047] Example 2 A tractor equipped with the aforementioned multi-level priority load-sensitive hydraulic control system for achieving energy-saving, safe, and efficient multi-functional collaborative operation control.

[0048] The tractor's multi-level priority load-sensitive hydraulic control system has four levels of priority control logic: 1. First priority: Turning Turning is a safety matter and requires an immediate response. As soon as the steering wheel moves, the system prioritizes steering fluid to ensure agile handling.

[0049] 2. Second priority: Braking (braking) This includes service brakes, parking brakes, and even trailer brakes.

[0050] Especially during emergency braking, the system will instantly concentrate resources to ensure fast and powerful braking, thus guaranteeing safety.

[0051] The system also includes a "brake fluid filling valve" to make the brakes respond faster and the pressure more stable.

[0052] 3. Third priority: Chassis control (such as power shift, four-wheel drive differential) Hydraulic power assist is required when shifting gears or switching to four-wheel drive mode, but it is distributed only after steering and braking are satisfied.

[0053] 4. Fourth priority: Hydraulic lifting system For example, the plowshare that lifts the plowshare, the header of a harvester, etc.

[0054] These tasks are important, but they do not directly affect driving safety, so they are listed last.

[0055] The beneficial effects of the technical solution of this utility model are: 1. Equipped with a hydraulic gear pump and dedicated cooling and lubrication pipes. The system is equipped with a separate small hydraulic gear pump, specifically responsible for cooling the oil temperature and lubricating the components. It operates at low power throughout, without affecting the oil distribution of the main system. It is inexpensive but very practical, and can also "parallel support" the main system when necessary, a process known as "dual pump confluence," where they work together under heavy loads to enhance performance.

[0056] 2. Automatic temperature control: stops when it gets cold and dissipates heat when it gets hot. The system uses temperature control valve 13 to detect oil temperature. If the oil temperature is too high, the cooling system is activated. Conversely, when the hydraulic oil temperature drops, the cooling system is automatically shut off to avoid wasting energy.

[0057] 3. Simpler structure, fewer malfunctions Compared to existing technologies, this solution integrates multiple previously separate hydraulic systems into a unified intelligent system, reducing pipelines, valves, and interfaces, making it not only more reliable but also easier to maintain.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

[0059] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A multi-level priority load-sensitive hydraulic control system, applied to a tractor, characterized in that, include: A hydraulic suction filter (1) is installed at the outlet end of the hydraulic oil tank; The load-sensitive pump (2) draws in hydraulic oil through the hydraulic oil suction filter (1) and can automatically adjust the output flow and pressure according to changes in system load; A multi-stage priority control valve (3) is connected to the oil outlet of the load-sensitive pump (2) and is used to distribute hydraulic oil to different functional modules according to a preset priority order. The functional modules include: steering system, braking system, chassis travel control system, and hydraulic lifting system; The multi-level priority control valve (3) is hydraulically controlled and has multi-level priority control logic to divide multiple functional modules into different priorities. In an emergency, the multi-level priority control valve (3) distributes hydraulic oil to multiple functional modules according to a preset priority order, and the steering system is the first level.

2. The multi-level priority load-sensitive hydraulic control system according to claim 1, characterized in that, The multi-level priority control valve (3) has four-level priority control logic. The steering system, braking system, chassis travel control system and hydraulic lifting system are respectively the first level, second level, third level and fourth level according to the preset priority order, wherein: The first stage prioritizes supplying hydraulic oil to the steering system, which includes the load-sensitive steering gear (4) and the steering cylinder (5); The second priority is to supply hydraulic oil to the braking system, which includes the trailer brake control valve (6), the service brake control valve (7), the brake cylinder (8), the parking brake valve (9), and the parking brake cylinder (10). The third priority is to supply hydraulic oil to the chassis travel control system, which includes the power shift mechanism and the PTO four-wheel drive differential valve (11); The fourth stage supplies the remaining hydraulic oil to the hydraulic lifting system; The multi-stage priority control valve (3) responds and adjusts according to the highest load requirements of each functional module and drives the load-sensitive pump (2).

3. The multi-level priority load-sensitive hydraulic control system according to claim 1, characterized in that, The multi-stage priority control valve (3) has an integrated brake filling valve, which is used to pre-pressurize the brake oil circuit before the braking action is started and maintain a stable oil pressure during the braking process, thereby improving the braking response speed and reliability.

4. The multi-level priority load-sensitive hydraulic control system according to claim 1, characterized in that, It also includes a separately configured quantitative gear pump, which is dedicated to driving the chassis cooling system (12) and the lubrication bypass valve (14). The fixed displacement gear pump is separated from the main hydraulic circuit to avoid occupying the total oil source of the load-sensitive system and ensure the stability of the main system's oil supply.

5. The multi-level priority load-sensitive hydraulic control system according to claim 4, characterized in that, The outlet of the fixed gear pump is connected to the main oil circuit of the load-sensitive pump (2) through a confluence valve. Under high load conditions, the two pumps can be combined to provide additional hydraulic flow to the system and improve the system's peak oil supply capacity.

6. The multi-level priority load-sensitive hydraulic control system according to claim 4, characterized in that, It is also equipped with a temperature control valve (13) for detecting the temperature of the chassis hydraulic oil; When the oil temperature exceeds the set threshold, the temperature control valve (13) opens and starts the low-pressure small displacement pump (15) to drive the cooling medium circulation; when the oil temperature returns to normal, the cooling circuit is automatically shut off to reduce energy loss.

7. The multi-level priority load-sensitive hydraulic control system according to claim 4, characterized in that, The lubrication bypass valve (14) is connected to the output branch of the quantitative gear pump to monitor the lubrication status of the hydraulic oil and adjust the flow direction to ensure that the transmission components receive continuous and effective lubrication and prevent dry friction damage.

8. The multi-level priority load-sensitive hydraulic control system according to claim 1, characterized in that, The load-sensitive pump (2) has a large-displacement oil replenishment pump integrated inside, which is used to provide stable oil replenishment to the main pump's suction chamber, enhance self-priming capability, prevent cavitation, and ensure stable oil supply to the system under inclined or high-speed operating conditions.

9. The multi-level priority load-sensitive hydraulic control system according to claim 2, characterized in that, The load-sensitive steering gear (4) and the steering cylinder (5) form a closed-loop steering execution unit, which can accurately control the wheel steering angle according to the driver's operation instructions and improve the vehicle's handling stability.

10. A tractor, characterized in that, Equipped with a multi-level priority load-sensitive hydraulic control system as described in any one of claims 1 to 9, for realizing energy-saving, safe, and efficient multi-functional collaborative operation and driving control.

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