Crawler-type lifting chassis hydraulic system and leveling method thereof

Abstract

The present application relates to a kind of tracked lifting chassis hydraulic system and its leveling method, including hydraulic oil tank, load sensing system, two-position four-way reversing valve, leveling hydraulic system and adjusting ram group;The hydraulic oil tank is connected with load sensing system, load sensing system is connected with leveling hydraulic system by two-position four-way reversing valve, and leveling hydraulic system and adjusting ram group are connected;The leveling hydraulic system includes several groups of sub-leveling hydraulic system, and sub-leveling hydraulic system includes pressure reducing valve, three-position four-way electromagnetic proportional valve, two check valves and shuttle valve.The leveling hydraulic system according to the present application changes the oil intake of each sub-leveling hydraulic system according to the load of each oil cylinder, reduces the influence of load on the oil intake of each sub-leveling system, so as to carry out preliminary synchronous adjustment to adjusting ram.

Description

Technical Field

[0001] This invention belongs to the technical field of tracked combine harvester chassis, and particularly relates to a hydraulic system for a tracked lifting chassis and its leveling method. Background Technology

[0002] Leveling the chassis is crucial for improving the passability, maneuverability, and operational performance of tracked combine harvesters. In the hilly and mountainous areas of southern my country, fields are often small, scattered, and riddled with ridges. When tracked combine harvesters cross ridges or ditches, or are being loaded / unloaded within the field, excessive changes in the vehicle's tilt angle can easily cause overturning. In paddy fields, the vehicle often tilts, increasing harvest losses and making it easy to sink and become stuck. To address these issues, researchers both domestically and internationally have developed leveling lifting chassis for tracked combine harvesters. This is achieved by adding a lifting mechanism to the existing fixed-clearance chassis. Among these, the lifting chassis based on a parallel four-bar linkage and hydraulic cylinders as the actuators exhibits good strength and stability. The four-point lifting chassis achieves lateral, longitudinal, and overall lifting adjustments by adjusting the extension and retraction of four cylinders. However, the system flow required for different adjustment conditions varies with the external load. If a traditional fixed-displacement pump is used for oil supply, the hydraulic system cannot adaptively adjust to changes in external load, resulting in low efficiency, high heat generation, and difficulty meeting the long-term operational requirements of the combine harvester.

[0003] The longitudinal adjustment and overall lifting of a four-point lifting chassis require synchronized movement of two hydraulic cylinders within the system. However, existing chassis lifting hydraulic systems often suffer from synchronization errors due to factors such as oil contamination and leakage, uneven load distribution, asymmetrical layout, oil pressure fluctuations, and manufacturing and installation errors of components. When the accumulated error reaches a certain level, it can easily lead to chassis frame distortion and deformation, or even breakage, significantly reducing the service life of the lifting chassis. Therefore, ensuring the synchronization of cylinder movement is particularly important during the angle adjustment of the lifting chassis.

[0004] Currently, the main types of hydraulic synchronization systems are as follows:

[0005] Using mechanical structures for the synchronous adjustment of hydraulic cylinders presents several challenges: transmission errors can occur. Manufacturing and assembly errors in transmission components within the mechanical structure, such as connecting rods and gears, can affect the synchronization of the hydraulic cylinders. These errors can accumulate during transmission, leading to differences in motion between the hydraulic cylinders. Simultaneously, unbalanced loads on the mechanical structure can occur. In some cases, the load distribution among the hydraulic cylinders may be uneven, causing the mechanical structure to bear different loads. This can result in uneven wear of the mechanical structure and hydraulic components, reducing their lifespan and performance.

[0006] Using a flow divider / combiner synchronizing valve for the synchronous adjustment of hydraulic cylinders: After use, multiple hydraulic cylinders can only move synchronously and cannot be adjusted individually, and changes in load have a great impact on the synchronization of hydraulic cylinders.

[0007] The use of hydraulic synchronous motors for synchronous adjustment of hydraulic cylinders in the past and present: Hydraulic synchronous motors are usually composed of multiple hydraulic motors and control systems, which require relatively complex design and installation, making them relatively expensive, including the costs of purchase, installation and maintenance; at the same time, hydraulic synchronous motors generate a lot of heat when running under high load or high speed, requiring a cooling system to control the temperature, which increases the complexity and cost of the system, and may impose limitations on space and environmental requirements. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a hydraulic system for a tracked lifting chassis and its leveling method, aiming to alleviate the problem of asynchronous operation of the adjusting cylinders due to load during the attitude adjustment of the harvester lifting chassis.

[0009] The technical solution of the present invention is: a hydraulic system for a tracked lifting chassis, comprising a hydraulic oil tank, a load-sensitive system, a two-position four-way directional valve, a leveling hydraulic system, an adjusting cylinder group, and a controller;

[0010] The hydraulic oil tank is connected to the load-sensitive system, which is connected to the leveling hydraulic system via a two-position four-way directional valve. The leveling hydraulic system is connected to the adjusting cylinder group. The leveling hydraulic system includes several sub-leveling hydraulic systems. Each sub-leveling hydraulic system includes a pressure reducing valve, a three-position four-way solenoid proportional valve, two check valves, and a shuttle valve. The pressure reducing valve is connected to the two-position four-way directional valve, the shuttle valve, and the three-position four-way solenoid proportional valve. The three-position four-way solenoid proportional valve is also connected to the two check valves, and the two check valves are connected to the shuttle valves.

[0011] The regulating cylinder group includes several cylinders, each of which is equipped with a displacement sensor. The displacement sensor is used to measure the extension and retraction of the cylinder and transmit the data to the controller.

[0012] The controller is connected to the load-sensitive system, the displacement sensor of the leveling hydraulic system, and the two-position four-way directional valve.

[0013] In the above scheme, the load-sensitive system includes a variable pump, a reset hydraulic cylinder, a variable adjustment lever, a pressure shut-off valve, a load-sensitive control valve, and a throttle valve;

[0014] The variable pump is connected to the reset hydraulic cylinder, the variable adjustment lever and the throttle valve respectively. The reset hydraulic cylinder is connected to the pressure shut-off valve and the load-sensitive control valve respectively. The variable adjustment lever is connected to the pressure shut-off valve and the load-sensitive control valve respectively. The variable pump is connected to the hydraulic oil tank. The throttle valve is connected to the pressure reducing valve through a two-position four-way directional valve.

[0015] The above solution also includes an oil filter;

[0016] The oil filter is installed between the hydraulic oil tank and the load-sensitive system.

[0017] The above solution also includes an overflow valve;

[0018] The overflow valve is installed between the load-sensitive system and the two-position four-way directional valve, and the overflow valve is connected to both the load-sensitive system and the two-position four-way directional valve.

[0019] In the above scheme, the adjusting cylinder group includes several cylinders;

[0020] The shuttle valve is connected to the hydraulic cylinder.

[0021] In the above scheme, when the controller receives the signal of the tilt sensor detecting the tilt of the vehicle body, that is, the longitudinal tilt angle θ1 of the vehicle body, and compares it with the preset allowable longitudinal tilt angle θ0 of the vehicle body, when θ1>θ0, the controller determines the target cylinder to be adjusted according to the signal of the tilt of the vehicle body, and defines the target cylinder as the master adjustment cylinder and the slave adjustment cylinder through the controller.

[0022] The controller delivers hydraulic oil from the hydraulic tank to the corresponding cylinder by controlling the load-sensitive system, the leveling hydraulic system, and the two-position four-way directional valve. The controller controls the extension and retraction of the target cylinder by controlling the connection direction of the three-position four-way electromagnetic proportional valve. The controller detects the values ​​of the displacement sensor on the target cylinder and the displacement difference Δh in real time. During the movement of the cylinder, the controller compares the displacement difference Δh with the preset allowable displacement difference Δh0 and controls the movement of the three-position four-way electromagnetic proportional valve corresponding to the cylinder, thereby controlling the movement speed of the cylinder to ensure that Δh≤Δh0, thus maintaining the synchronization of each cylinder. When the vehicle body is adjusted to θ1≤θ0, the controller controls the two-position four-way directional valve and the three-position four-way electromagnetic proportional valve to close, and the hydraulic oil overflows into the hydraulic tank, completing the leveling of the vehicle body.

[0023] In the above scheme, the regulating cylinder group includes 4 cylinders.

[0024] In the above scheme, the hydraulic oil tank is also connected to the relief valve, the two-position four-way directional valve and the leveling hydraulic system.

[0025] A leveling method for a hydraulic system of a tracked lifting chassis specifically includes the following steps:

[0026] Step S1: When the controller receives the signal of vehicle body tilt, that is, the longitudinal tilt angle θ1 of the vehicle body, it is compared with the preset allowable longitudinal tilt angle θ0 of the vehicle body. When θ1>θ0, the controller determines the target cylinder to be adjusted according to the signal of vehicle body tilt. The controller defines the target cylinder as the master adjustment cylinder and the slave adjustment cylinder.

[0027] Step S2: The controller delivers hydraulic oil from the hydraulic tank to the corresponding cylinder by controlling the load-sensitive system, the leveling hydraulic system, and the two-position four-way directional valve. The controller controls the extension and retraction of the target cylinder by controlling the connection direction of the three-position four-way solenoid proportional valve. The controller detects the value of the displacement sensor on the target cylinder and the displacement difference Δh in real time. During the movement of the cylinder, the controller compares the displacement difference Δh with the preset error allowable displacement difference Δh0 and controls the movement of the three-position four-way solenoid proportional valve corresponding to the regulating cylinder to control the movement speed of the regulating cylinder, ensuring that Δh≤Δh0, thereby maintaining the synchronization of each regulating cylinder. When the vehicle body is adjusted to θ1≤θ0, the controller controls the two-position four-way directional valve and the three-position four-way solenoid proportional valve to close, and the hydraulic oil overflows into the hydraulic tank, completing the leveling of the vehicle body.

[0028] In the above scheme, the control of the target cylinder extension / retraction amount in step S2 specifically includes the following steps:

[0029] Step S2.1: The controller controls the left position of the three-position four-way electromagnetic proportional valve to be connected. The hydraulic oil passes through the pressure reducing valve, the three-position four-way electromagnetic proportional valve, the check valve and the shuttle valve located in the left position of the three-position four-way electromagnetic proportional valve in the leveling hydraulic system in sequence, and enters the rod chamber in the oil cylinder to realize the retraction of the oil cylinder.

[0030] Step S2.2: The controller controls the right position of the three-position four-way electromagnetic proportional valve to be connected. The hydraulic oil passes through the pressure reducing valve, the three-position four-way electromagnetic proportional valve, the check valve and the shuttle valve located in the right position of the three-position four-way electromagnetic proportional valve in the leveling hydraulic system in sequence, and enters the rodless chamber in the oil cylinder to realize the extension of the oil cylinder.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] 1. The load-sensitive system of the present invention delivers hydraulic oil from the hydraulic oil tank to the hydraulic system and adjusts the pumping oil volume of the variable pump according to the system load to meet the oil volume requirements of the entire hydraulic system, thereby reducing internal system losses and improving the working efficiency of the entire hydraulic system.

[0033] 2. The leveling hydraulic system of the present invention changes the oil inlet of each sub-leveling hydraulic system according to the load of each cylinder, thereby reducing the impact of the load on the oil inlet of each sub-leveling system and thus performing preliminary synchronous adjustment of the adjusting cylinder.

[0034] 3. Each sub-adjustment hydraulic system of the present invention has two one-way valves that are respectively connected to the two cylinder chambers of the corresponding adjustment cylinder in the adjustment cylinder group, forming a double-loop locking oil circuit to ensure that the adjustment cylinder is not affected by the weight of the vehicle body during the adjustment process, to ensure the extension and retraction of the adjustment cylinder, and to ensure that the adjustment cylinder group can maintain its current posture when the entire hydraulic system suddenly fails.

[0035] 4. The present invention adjusts the extension and retraction of the hydraulic cylinder to drive the movement of the lifting mechanism, thereby adjusting the posture of the lifting chassis.

[0036] 5. The hydraulic cylinder of this invention is equipped with a displacement sensor on its outer side. The signal data from the displacement sensor is transmitted to the controller. The controller adjusts the various components in the hydraulic system based on the feedback displacement signal, thereby controlling the movement of the regulating cylinder so that it moves to the required length according to the desired adjustment angle. The adjustment principle is as follows: one of the two regulating cylinders that need to operate synchronously is the master regulating cylinder, and the other is the slave regulating cylinder. The controller detects the displacement difference between the master and slave regulating cylinders and controls the piston opening size of the three-position four-way electromagnetic proportional valve of the slave regulating cylinder to control the displacement speed and displacement time of the slave regulating cylinder. This keeps the displacement difference between the two regulating cylinders within the allowable error range, thereby ensuring the synchronicity of the cylinder movement, reducing transmission errors, and thus reducing local stress on the chassis. This improves the reliability and service life of the lifting chassis and reduces costs. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the hydraulic system principle of a tracked lifting chassis according to an embodiment of the present invention.

[0038] Figure 2 This is a three-dimensional schematic diagram of a tracked lifting chassis according to an embodiment of the present invention.

[0039] Figure 3 This is a schematic diagram of the position of the adjusting cylinder assembly according to an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the leveling of the hydraulic system of the tracked lifting chassis according to one embodiment of the present invention.

[0041] Figure 5 This is a schematic diagram of the working process of the hydraulic system of the tracked lifting chassis according to an embodiment of the present invention.

[0042] Figure 6 This is a schematic diagram of the maximum displacement working state of the hydraulic system of the tracked lifting chassis according to an embodiment of the present invention.

[0043] Figure 7 This is a schematic diagram of the uniform motion of the left and right rear cylinders of the hydraulic system of the tracked lifting chassis according to an embodiment of the present invention.

[0044] Figure 8 This is a schematic diagram of the hydraulic system adjusting the oil cylinder to its maximum stroke in a tracked lifting chassis according to an embodiment of the present invention.

[0045] In the diagram: 1. Hydraulic oil tank; 2. Oil filter; 3. Load-sensitive system; 301. Variable pump; 302. Reset hydraulic cylinder; 303. Variable adjustment lever; 304. Pressure shut-off valve; 305. Load-sensitive control valve; 306. Throttle valve; 4. Relief valve; 5. Two-position four-way directional valve; 6. Leveling hydraulic system; 601. Pressure reducing valve; 602. Three-position four-way solenoid proportional valve; 603. Check valve; 604. Shuttle valve; 7. Adjusting cylinder group; 701. Left front cylinder; 702. Right front cylinder; 703. Left rear cylinder; 704. Right rear cylinder; 8. Controller. Detailed Implementation

[0046] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0047] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "front," "rear," "left," "right," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention 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, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0048] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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 invention according to the specific circumstances.

[0049] Figure 1 , 2 Figures 3 and 4 show a preferred embodiment of the hydraulic system for the tracked lifting chassis, including a hydraulic oil tank 1, a load-sensitive system 3, a two-position four-way directional valve 5, a leveling hydraulic system 6, and an adjusting cylinder group 7.

[0050] The main oil circuit passes sequentially through hydraulic oil tank 1, load sensing system 3, two-position four-way reversing valve 5, leveling hydraulic system 6 and adjusting cylinder group 7. Hydraulic oil tank 1 is connected to load sensing system 3. Load sensing system 3 is connected to leveling hydraulic system 6 through two-position four-way reversing valve 5. Leveling hydraulic system 6 is connected to adjusting cylinder group 7.

[0051] The leveling hydraulic system 6 includes several sub-leveling hydraulic systems. Each sub-leveling hydraulic system includes a pressure reducing valve 601, a three-position four-way solenoid proportional valve 602, two check valves 603, and a shuttle valve 604. The pressure reducing valve 601 is connected to the two-position four-way directional valve 5. The main oil circuit passes through the pressure reducing valve 601, the three-position four-way solenoid proportional valve 602, the two check valves 603, and the shuttle valve 604 in sequence. The pressure reducing valve 601 is connected to the shuttle valve 604 and the three-position four-way solenoid proportional valve 602, the three-position four-way solenoid proportional valve 602 is connected to the two check valves 603, and the two check valves 603 are connected to the shuttle valve 604.

[0052] The two-position four-way solenoid directional valve 5 is a master switch valve that controls the on / off state of the entire oil circuit.

[0053] According to one embodiment of the present invention, preferably, the leveling hydraulic system 6 includes four identical sub-leveling hydraulic systems. A two-position four-way solenoid directional valve 5 is connected in parallel with the four sub-leveling hydraulic systems. Each sub-leveling hydraulic system controls one hydraulic cylinder in the regulating cylinder group 7. The pressure regulating port of the pressure reducing valve 601 and the oil outlet of the shuttle valve 604 are connected together to form a differential pressure reducing valve, which can control the oil inlet of the sub-leveling hydraulic system according to the load of the regulating cylinder. The outlet pressure of the shuttle valve 604 is affected by the load of the regulating cylinder controlled by its sub-leveling hydraulic system and compared with the preset spring force of the pressure reducing valve 601. The opening size of the pressure reducing valve 601 is adjusted to obtain the required hydraulic oil flow rate; the oil inlet of the pressure reducing valve 601 is connected to the main oil circuit; the three-position four-way electromagnetic proportional valve 602 is connected to the oil outlet of the pressure reducing valve 601, thereby controlling the on / off state of each sub-hydraulic system and determining the flow direction of the hydraulic oil inside the oil circuit, thereby controlling the extension and retraction of the regulating hydraulic cylinder and adjusting the posture of the tracked lifting chassis; the two one-way valves 603 are respectively connected to the two cylinder chambers of the corresponding regulating cylinder of the regulating cylinder group 7, forming a double-path locking oil circuit, which can provide a reliable position locking function, ensure the safe and stable operation of the system, and guarantee the stability of the regulating cylinder group 7 after adjustment.

[0054] Preferably, the load-sensitive system 3 includes a variable pump 301, a reset hydraulic cylinder 302, a variable adjustment lever 303, a pressure shut-off valve 304, a load-sensitive control valve 305, and a throttle valve 306;

[0055] The variable pump 301 is connected to the reset hydraulic cylinder 302, the variable adjustment lever 303 and the throttle valve 306 respectively. The reset hydraulic cylinder 302 is connected to the pressure shut-off valve 304 and the load-sensitive control valve 305 respectively. The variable adjustment lever 303 is connected to the pressure shut-off valve 304 and the load-sensitive control valve 305 respectively. The variable pump 301 is connected to the hydraulic oil tank 1. The throttle valve 306 is connected to the pressure reducing valve 601 through the two-position four-way directional valve 5. The load-sensitive system 3 can change the oil discharge of the variable pump 301 according to the load of the entire hydraulic system.

[0056] Preferably, the swash plate of the variable pump 301 is tangent to the plunger of the reset hydraulic cylinder 302 and the variable regulating cylinder 303. The variable pump 301 adjusts the swash plate tilt angle through the pressure difference between the reset hydraulic cylinder 302 and the variable regulating cylinder 303 to change the pump's oil discharge. The rodless chamber of the reset hydraulic cylinder 302 is connected in parallel with the pressure shut-off valve 304 and the load-sensitive control valve 305. The rodless chamber of the variable regulating cylinder 303 is also connected in parallel with the pressure shut-off valve 304 and the load-sensitive control valve 305. The pressure shut-off valve 304 can be manually adjusted to control the maximum working pressure of the load-sensitive system 3. The load-sensitive control valve 305 controls the flow rate in the pilot oil circuit. The throttle valve 306 is connected to the oil outlet of the variable pump 301. By adjusting the size of the throttle orifice, the flow rate and speed of the hydraulic oil entering the regulating oil circuit are controlled, thereby relieving oil pressure.

[0057] Preferably, it also includes an oil filter 2 for filtering out most of the impurities in the oil;

[0058] The oil filter 2 is installed between the hydraulic oil tank 1 and the variable pump 301.

[0059] Preferably, the oil filter 2 includes an oil inlet and an oil outlet. The oil inlet is connected to the hydraulic oil tank 1, and the oil outlet is connected to the pump inlet of the variable pump 301 in the load-sensitive system 3. The hydraulic oil in the hydraulic oil tank 1 enters the hydraulic system through the filtration of the oil filter 2.

[0060] Preferably, it also includes an overflow valve 4, which plays a safety protection role. When the total oil circuit exceeds the total load limit, it will overflow to protect the entire oil circuit.

[0061] The overflow valve 4 is installed between the throttle valve 306 and the two-position four-way directional valve 5, and the overflow valve 4 is connected in parallel with the throttle valve 306 and the two-position four-way directional valve 5.

[0062] Preferably, the adjusting cylinder group 7 includes a plurality of cylinders;

[0063] The shuttle valve 604 is connected to the oil cylinder.

[0064] Preferably, each of the plurality of hydraulic cylinders is equipped with a displacement sensor for detecting the relative position of the hydraulic cylinders.

[0065] Preferably, the regulating cylinder group 7 includes 4 cylinders.

[0066] Preferably, it also includes a controller 8;

[0067] The controller 8 is connected to the load sensing system 3, the leveling hydraulic system 6, and the two-position four-way directional valve 5. When the controller 8 receives a signal from the tilt sensor indicating that the vehicle body is tilted (i.e., the longitudinal tilt angle θ1 of the vehicle body), and compares it with the preset allowable longitudinal tilt angle θ0 of the vehicle body, if θ1 > θ0, the controller 8 determines the target cylinder to be adjusted based on the vehicle body tilt signal. The controller defines the target cylinder as the main regulating cylinder and the slave regulating cylinder. Based on the displacement difference between the extension and retraction of the main and slave regulating cylinders, the controller adjusts the opening size of the three-position four-way solenoid valve corresponding to the slave regulating cylinder to adjust the extension and retraction speed of the slave regulating cylinder.

[0068] The controller 8, through controlling the load-sensitive system 3, the leveling hydraulic system 6, and the two-position four-way directional valve 5, delivers hydraulic oil from the hydraulic oil tank 1 to the corresponding cylinder. The controller 8 controls the connection direction of the three-position four-way electromagnetic proportional valve 602 to control the extension and retraction of the target cylinder. The controller 8 detects the values ​​of the displacement sensor on the target cylinder and the displacement difference Δh in real time. During the movement of the cylinder, the controller 8 compares the displacement difference Δh with the preset allowable displacement difference Δh0 and controls the movement of the three-position four-way electromagnetic proportional valve 602 corresponding to the cylinder, thereby controlling the movement speed of the cylinder and ensuring that Δh≤Δh0, thus maintaining the synchronization of each cylinder. When the vehicle body is adjusted to θ1≤θ0, the controller 8 controls the two-position four-way directional valve 5 and the three-position four-way electromagnetic proportional valve 602 to close, and the hydraulic oil overflows into the hydraulic oil tank 1, completing the leveling of the vehicle body.

[0069] Preferably, the hydraulic oil tank 1 is also connected to the overflow valve 4, the two-position four-way directional valve 5, and the leveling hydraulic system 6.

[0070] According to an embodiment of the present invention, preferably, the adjusting cylinder group 7 includes four hydraulic cylinders for adjusting the chassis posture: a left front cylinder 701, a right front cylinder 702, a left rear cylinder 703, and a right rear cylinder 704. All four hydraulic cylinders are double-acting cylinders, and each hydraulic cylinder is equipped with a displacement sensor to measure the extension and retraction of the cylinder and control the synchronicity of the cylinder adjustment, so as to perform more precise control on the synchronous movement of the adjusting cylinders.

[0071] The extension and retraction of four adjusting cylinders drive the movement of the lifting mechanism, thereby adjusting the posture of the lifting chassis at four points. When the left front cylinder 701 and the right front cylinder 702 move individually, while the left rear cylinder 703 and the right rear cylinder 704 do not move, the lifting chassis can be tilted to the left or right. When the left front cylinder 701 and the right front cylinder 702 move together, while the left rear cylinder 703 and the right rear cylinder 704 do not move, the lifting chassis can be raised and lowered as a whole. When the left rear cylinder 703 and the right rear cylinder 704 move individually, while the left front cylinder 701 and the right front cylinder 702 do not move, the lifting chassis can be tilted forward or backward as a whole.

[0072] Preferably, the tracked lifting chassis hydraulic system is equipped with a height sensor and a tilt sensor on the chassis to detect the height and tilt of the chassis, and the height sensor and tilt sensor are connected to the controller.

[0073] A leveling method based on the above-mentioned hydraulic system for a tracked lifting chassis, such as... Figure 5 As shown, the specific steps include the following:

[0074] Step S1: When the vehicle body is climbing a slope, the controller 8 receives a signal of vehicle body tilt, that is, the longitudinal tilt angle θ1 of the vehicle body, and compares it with the preset allowable longitudinal tilt angle θ0 of the vehicle body. When θ1>θ0, the controller 8 starts to control the hydraulic system of the tracked lifting chassis. The controller 8 determines the target cylinder to be adjusted through the signal of vehicle body tilt and divides the target cylinder into the main adjustment cylinder and the slave adjustment cylinder.

[0075] Step S2: The controller 8, by controlling the load-sensitive system 3, the leveling hydraulic system 6, and the two-position four-way directional valve 5, delivers hydraulic oil from the hydraulic oil tank 1 to the corresponding cylinder. The controller 8 controls the connection direction of the three-position four-way electromagnetic proportional valve 602 to control the extension and retraction of the target cylinder. The controller 8 detects the value of the displacement sensor on the target cylinder and the displacement difference Δh in real time. During the movement of the cylinder, the controller compares the displacement difference Δh with the preset error allowable displacement difference Δh0 and controls the movement of the three-position four-way electromagnetic proportional valve 602 corresponding to the regulating cylinder to adjust the movement speed of the regulating cylinder, ensuring that Δh≤Δh0, thereby maintaining the synchronization of each regulating cylinder. When the vehicle body is adjusted to θ1≤θ0, the two-position four-way directional valve 5 and the three-position four-way electromagnetic proportional valve 602 are closed, and the hydraulic oil overflows into the hydraulic oil tank 1, completing the leveling of the vehicle body.

[0076] In the above scheme, the control of the target cylinder extension / retraction amount in step S2 specifically includes the following steps:

[0077] Step S2.1: Controller 8 controls the left position of the three-position four-way electromagnetic proportional valve 602 to be connected. The hydraulic oil passes through the pressure reducing valve 601, the three-position four-way electromagnetic proportional valve 602, the check valve 603 located in the left position of the three-position four-way electromagnetic proportional valve 602 and the shuttle valve 604 in the leveling hydraulic system 6 in sequence, and enters the rod chamber in the oil cylinder to realize the retraction of the oil cylinder.

[0078] Step S2.2: Controller 8 controls the right position of the three-position four-way electromagnetic proportional valve 602 to be connected. The hydraulic oil passes through the pressure reducing valve 601, the three-position four-way electromagnetic proportional valve 602, the check valve 603 located in the right position of the three-position four-way electromagnetic proportional valve 602 and the shuttle valve 604 in the leveling hydraulic system 6 in sequence, and enters the rodless chamber in the oil cylinder to realize the extension of the oil cylinder.

[0079] When starting work, the controller 8 opens the two-position four-way directional valve 5 and the three-position four-way electromagnetic proportional valve 602 corresponding to the cylinder to be adjusted; the hydraulic oil in the hydraulic oil tank 1 passes through the oil filter 2, the load sensing system 3, the two-position four-way directional valve 5, and the leveling hydraulic system 6 in sequence, and reaches the cylinder. The controller 8 controls the connection direction of the three-position four-way electromagnetic proportional valve 602 to control the extension and retraction of the cylinder.

[0080] Preferably, when both the two-position four-way directional valve 5 and the leveling hydraulic system 6 are closed, the hydraulic oil flows back from the two-position four-way directional valve 5 to the hydraulic oil tank 1.

[0081] Preferably, when the two-position four-way directional valve 5 is open and the leveling hydraulic system 6 is closed, the oil flows back from the relief valve 4 to the hydraulic oil tank 1.

[0082] Example 1

[0083] like Figure 4 As shown, when the vehicle climbs a slope, the chassis automatically performs longitudinal leveling, i.e., the two rear adjusting cylinders move automatically, and the entire system's workflow is as follows:

[0084] When the vehicle is climbing a slope, the tilt sensor detects the vehicle tilt signal, i.e., the longitudinal tilt angle θ1 of the vehicle body. It is compared with the preset allowable longitudinal tilt angle θ0 of the vehicle body. When θ1>θ0, the tilt sensor sends an adjustment signal to the controller. The controller 8 starts to control the hydraulic system of the tracked lifting chassis. The controller determines the target cylinder to be adjusted based on the vehicle tilt signal detected by the tilt sensor. For example, for forward and backward tilt, the left and right rear cylinders are adjusted; for left and right tilt, the left and right front cylinders are adjusted; for oblique tilt, the cylinder on the tilt side or the other cylinders besides the cylinder on the tilt side are adjusted. The controller defines the target cylinder as the master adjustment cylinder and the slave adjustment cylinder.

[0085] The controller 8 opens the main valve 5 and the three-position four-way electromagnetic proportional valves 602 corresponding to the left rear cylinder 703 and the right rear cylinder 704, respectively; the variable pump 301 automatically adjusts the swashplate angle of the variable pump 301 according to the load on the main hydraulic system, and provides the required amount of hydraulic oil to the leveling hydraulic system 6; the pressure reducing valve 601 and the shuttle valve 604 combine to form a differential pressure reducing valve, which controls the oil inlet of the leveling hydraulic system according to the load of each regulating cylinder, and initially reduces the impact of the load on the asynchronous operation of the cylinders; the left rear cylinder 703 and the right rear cylinder 704 start to move, and the vehicle body begins to automatically level.

[0086] Automatic leveling process:

[0087] The left rear cylinder 703 is designated as the main regulating cylinder, and the right rear cylinder 704 as the slave regulating cylinder. During the movement of the regulating cylinders, the controller 8 continuously monitors the values ​​h1 and h2 of the displacement sensors on the left and right rear cylinders 703 and 704, as well as the displacement difference Δh, with h1 as the main value and h2 as the slave value. During the movement of the regulating cylinders, the controller compares the displacement difference Δh with the preset allowable displacement difference Δh0, and controls the movement of the three-position four-way electromagnetic proportional valve 602 corresponding to the right rear cylinder 704 to adjust the movement speed of the right rear cylinder 704, ensuring that Δh ≤ Δh0, thereby maintaining the synchronization of the two rear regulating cylinders. When the vehicle body is adjusted to θ1 ≤ θ0, the main valve 5 and the three-position four-way electromagnetic proportional valve 602 are closed, and the hydraulic oil overflows into the hydraulic oil tank 1, completing the vehicle body leveling.

[0088] Hydraulic oil circuit in load-sensitive system 3:

[0089] like Figure 6 As shown, when the lifting chassis needs to tilt forward or backward to a certain height, the three-position four-way solenoid proportional valves 602 in the sub-leveling hydraulic system corresponding to the two-position four-way directional valve 5, the left rear cylinder 703, and the right rear cylinder 704 all open, and the hydraulic oil pumped by the variable pump 301 begins to enter the leveling hydraulic system 6. At this time, the pressure P at the oil outlet of the variable pump 301... 泵 The total load pressure P of the entire leveling hydraulic system is greater than 6. 负载 With the maximum operating pressure P of the load-sensitive system 3 弹簧 The sum of these values, at this point, balances the total load pressure P of the hydraulic system 6. 负载 If the corresponding cylinder cannot be pushed, the valve core of the load-sensitive control valve 305 moves to the left due to the spring force. The right chamber of the variable adjustment cylinder 303 is directly connected to the hydraulic oil tank 1. The hydraulic oil in the right chamber of the variable adjustment cylinder 303 flows directly into the hydraulic oil tank 1. The swashplate tilt angle of the variable pump 301 becomes the maximum, and it is in the maximum displacement working state.

[0090] like Figure 7 As shown, with the continuous pumping of oil by the variable pump 301, P负载 Continue to increase until P 泵 equals P 负载 With P 弹簧 The load-sensitive control valve 305 overcomes the preset spring force, causing the valve core of the load-sensitive control valve 305 to move to the right, the left chamber to work, and hydraulic oil to enter the right chamber of the variable regulating cylinder 303. The swashplate angle of the variable pump 301 decreases to a certain range, maintaining the pumping speed of the variable pump 301 within a certain range, thus stabilizing the internal pressure of the hydraulic system. The left rear cylinder 703 and the right rear cylinder 704 move at a constant speed. Regardless of the load change, the load-sensitive system will repeat the above steps to ensure the stable movement of the regulating cylinder. During the movement of the regulating cylinder, it will drive the displacement sensor on its cylinder body. The data from the displacement sensor is fed back to the controller 8, reflecting the extension and retraction displacement of the regulating cylinder. If the difference in the extension and retraction of the two rear regulating cylinders exceeds the preset error range, the controller 8 will control the three-position four-way solenoid proportional valve 602 corresponding to the two regulating cylinders, controlling its opening size to change the movement speed of the regulating cylinder, thereby reducing the difference in the extension and retraction of the regulating cylinder, forming a closed-loop control, and precisely controlling the synchronization of the regulating cylinder.

[0091] like Figure 8 As shown, when the corresponding regulating cylinder reaches its end point and the corresponding regulating cylinder reaches its maximum stroke, the pressure on both sides of the load-sensitive control valve 305 is the same. Under the action of the spring force, it operates in the right position, and the variable pump 301 continuously pumps oil. The pump's output flow has nowhere to be released, and the pressure rises. When the pressure reaches the set pressure of the pressure shut-off valve 304, the pressure shut-off valve 304 operates in the left position, and the oil from the variable pump 301 enters the hydraulic oil tank 1 through the shut-off valve 304. The oil in the right chamber of the variable regulating cylinder 303 also enters the hydraulic oil tank through the shut-off valve 304. The swashplate tilt angle of the variable pump 301 decreases, and the pumping volume of the variable pump 301 decreases. At this time, the pump's output flow can only meet the internal leakage requirements.

[0092] The present invention reduces the impact of the load on the cylinder's operating speed by using a load-sensitive system 3 and a leveling hydraulic system 6.

[0093] This invention uses a load-sensitive system and a displacement sensor to jointly control the extension of the regulating cylinder. The load-sensitive system adjusts the output pressure and flow rate of the hydraulic pump according to the load demand, providing more precise control performance. The system can sense load changes in real time and adjust the working state of the hydraulic pump and valves as needed, ensuring accurate control of the movement speed and force of hydraulic components. Each sub-leveling hydraulic system in the leveling hydraulic system can automatically adjust the oil inlet in the corresponding oil circuit according to the load of the corresponding cylinder, reducing the impact of cylinder load on the cylinder extension and retraction speed, and initially solving the problem of non-synchronization of the regulating cylinder extension and retraction during the adjustment of the lifting chassis. The controller detects the data of the displacement sensor on each regulating cylinder to determine the synchronicity of the regulating cylinder adjustment. If the extension and retraction displacement of two regulating cylinders that need to operate synchronously differs significantly, the controller controls the current of the solenoid valve in each sub-regulating oil circuit to adjust the hydraulic oil flow in the sub-circuit, thereby speeding up or slowing down the extension and retraction speed of the cylinders and reducing the difference in the extension and retraction displacement of the regulating cylinders, thus achieving precise adjustment of the synchronization of the regulating cylinders. This reduces local stress on the chassis, thereby improving the reliability and service life of the lifting chassis.

[0094] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0095] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hydraulic system for a tracked lifting chassis, characterized in that, Includes a hydraulic oil tank (1), a load-sensitive system (3), a two-position four-way directional valve (5), a leveling hydraulic system (6), an adjusting cylinder group (7), and a controller (8); The hydraulic tank (1) is connected to the load-sensitive system (3), which is connected to the leveling hydraulic system (6) via a two-position four-way directional valve (5). The leveling hydraulic system (6) is connected to the adjusting cylinder group (7). The leveling hydraulic system (6) includes several sub-leveling hydraulic systems. Each sub-leveling hydraulic system includes a pressure reducing valve (601), a three-position four-way electromagnetic proportional valve (602), two check valves (603), and a shuttle valve (604). The pressure reducing valve (601) is connected to the two-position four-way directional valve (5), the shuttle valve (604), and the three-position four-way electromagnetic proportional valve (602). The three-position four-way electromagnetic proportional valve (602) is also connected to two check valves (603), and the two check valves (603) are connected to the shuttle valve (604). The regulating cylinder group (7) includes several cylinders, each of which is equipped with a displacement sensor. The displacement sensor is used to measure the extension and retraction of the cylinder and transmit the data to the controller (8). The controller (8) is connected to the load-sensitive system (3), the leveling hydraulic system (6) displacement sensor, and the two-position four-way reversing valve (5), respectively. When the controller (8) receives a signal from the tilt sensor that the vehicle body is tilted, i.e., the longitudinal tilt angle of the vehicle body... and the preset allowable longitudinal tilt angle of the vehicle body. In comparison, when > At that time, the controller (8) determines the target cylinder to be adjusted according to the signal of the vehicle body tilt. The controller defines the target cylinder as the main regulating cylinder and the slave regulating cylinder. According to the displacement difference of the cylinder extension and retraction of the main and slave regulating cylinders, the opening size of the three-position four-way solenoid valve corresponding to the slave regulating cylinder is adjusted to adjust the extension and retraction speed of the slave regulating cylinder. The controller (8) delivers hydraulic oil from the hydraulic tank (1) to the corresponding cylinder by controlling the load-sensitive system (3), the leveling hydraulic system (6), and the two-position four-way directional valve (5). The controller (8) controls the extension and retraction of the target cylinder by controlling the connection direction of the three-position four-way electromagnetic proportional valve (602). The controller (8) detects the values ​​of the displacement sensor on the target cylinder and the displacement difference in real time. During the adjustment of the hydraulic cylinder's movement, the controller (8) adjusts the displacement difference... The displacement difference between the preset error and the preset error is allowed. In comparison, controlling the movement of the three-position four-way solenoid proportional valve (602) corresponding to the regulating cylinder controls the movement speed of the regulating cylinder, ensuring... ≤ This maintains the synchronization of each adjusting cylinder, so that when the vehicle body is adjusted to... ≤ At this time, the controller (8) controls the two-position four-way directional valve (5) and the three-position four-way electromagnetic proportional valve (602) to close, and the hydraulic oil overflows into the hydraulic oil tank (1), and the vehicle body is leveled.

2. The hydraulic system for a tracked lifting chassis according to claim 1, characterized in that, The load-sensitive system (3) includes a variable pump (301), a reset hydraulic cylinder (302), a variable adjustment lever (303), a pressure shut-off valve (304), a load-sensitive control valve (305), and a throttle valve (306). The variable pump (301) is connected to the reset hydraulic cylinder (302), the variable adjustment lever (303) and the throttle valve (306) respectively. The reset hydraulic cylinder (302) is connected to the pressure shut-off valve (304) and the load-sensitive control valve (305) respectively. The variable adjustment lever (303) is connected to the pressure shut-off valve (304) and the load-sensitive control valve (305) respectively. The variable pump (301) is connected to the hydraulic oil tank (1). The throttle valve (306) is connected to the pressure reducing valve (601) through the two-position four-way directional valve (5).

3. The tracked lifting chassis hydraulic system according to claim 1, characterized in that, It also includes an oil filter (2); The oil filter (2) is installed between the hydraulic oil tank (1) and the load-sensitive system (3).

4. The hydraulic system for a tracked lifting chassis according to claim 1, characterized in that, It also includes an overflow valve (4); The overflow valve (4) is installed between the load-sensitive system (3) and the two-position four-way directional valve (5), and the overflow valve (4) is connected to the load-sensitive system (3) and the two-position four-way directional valve (5).

5. The tracked lifting chassis hydraulic system according to claim 1, characterized in that, The regulating cylinder group (7) includes several cylinders; The shuttle valve (604) is connected to the oil cylinder.

6. The tracked lifting chassis hydraulic system according to claim 1, characterized in that, The regulating cylinder group (7) includes 4 cylinders.

7. The tracked lifting chassis hydraulic system according to claim 4, characterized in that, The hydraulic oil tank (1) is also connected to the relief valve (4), the two-position four-way directional valve (5), and the leveling hydraulic system (6).

8. A leveling method for a hydraulic system of a tracked lifting chassis according to any one of claims 1-7, characterized in that, Specifically, the steps include the following: Step S1: When the controller (8) receives the signal of vehicle body tilt, i.e., the longitudinal tilt angle of the vehicle body The preset allowable longitudinal tilt angle of the vehicle body In comparison, when > When the vehicle body tilts, the controller (8) determines the target cylinder to be adjusted based on the signal of the vehicle body tilt, and sets the target cylinder as the main adjusting cylinder and the slave adjusting cylinder through the controller. Step S2: The controller (8) delivers hydraulic oil from the hydraulic tank (1) to the corresponding cylinder by controlling the load-sensitive system (3), the leveling hydraulic system (6), and the two-position four-way directional valve (5). The controller (8) controls the extension and retraction of the target cylinder by controlling the connection direction of the three-position four-way electromagnetic proportional valve (602). The controller (8) detects the values ​​of the displacement sensor on the target cylinder and the displacement difference in real time. During the adjustment of the hydraulic cylinder's movement, the controller (8) adjusts the displacement difference... The displacement difference between the preset error and the preset error is allowed. In comparison, controlling the movement of the three-position four-way solenoid proportional valve (602) corresponding to the regulating cylinder controls the movement speed of the regulating cylinder, ensuring... ≤ This maintains the synchronization of each adjusting cylinder, so that when the vehicle body is adjusted to... ≤ At this time, the controller (8) controls the two-position four-way directional valve (5) and the three-position four-way electromagnetic proportional valve (602) to close, and the hydraulic oil overflows into the hydraulic oil tank (1), and the vehicle body is leveled.

9. The leveling method for the hydraulic system of the tracked lifting chassis according to claim 8, characterized in that, The control of the target hydraulic cylinder extension / retraction amount in step S2 specifically includes the following steps: Step S2.1: The controller (8) controls the left position of the three-position four-way electromagnetic proportional valve (602) to be connected. The hydraulic oil passes through the pressure reducing valve (601), the three-position four-way electromagnetic proportional valve (602), the check valve (603) located in the left position of the three-position four-way electromagnetic proportional valve (602), and the shuttle valve (604) in the leveling hydraulic system (6) in sequence, and enters the rod chamber in the cylinder to realize the retraction of the cylinder. Step S2.2: The controller (8) controls the right position of the three-position four-way electromagnetic proportional valve (602) to be connected. The hydraulic oil passes through the pressure reducing valve (601), the three-position four-way electromagnetic proportional valve (602), the check valve (603) located in the right position of the three-position four-way electromagnetic proportional valve (602), and the shuttle valve (604) in the leveling hydraulic system (6) in sequence, and enters the rodless chamber in the cylinder to realize the extension of the cylinder.

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