Vehicle hydro-pneumatic suspension system, control method thereof and agricultural machinery

Abstract

The invention provides a vehicle hydro-pneumatic suspension system, a control method thereof and agricultural machinery. The vehicle hydro-pneumatic suspension system comprises a hydraulic pump which is configured to provide hydraulic oil; the two suspension oil cylinders are arranged on an oil supply path of the hydraulic pump, piston rods are arranged in the suspension oil cylinders, and the space in the suspension oil cylinders is divided into rod cavities and rodless cavities by the piston rods; the first energy accumulator (12) is communicated with the rod cavities corresponding to the two suspension oil cylinders; the second energy accumulator (10) is communicated with rodless cavities corresponding to the two suspension oil cylinders; and the valve group (23) is arranged on an oil path between the hydraulic pump and the two suspension oil cylinders, and is configured to change the displacement of the piston rod according to working conditions to change the relative position of a frame and an axle, and / or change the pressure in a rod cavity to adjust the rigidity of the vehicle hydro-pneumatic suspension system.

Description

Technical Field

[0001] This disclosure relates to the field of vehicle shock absorption technology, and in particular to a vehicle hydropneumatic suspension system and its control method, as well as agricultural machinery. Background Technology

[0002] Agricultural machinery (such as tractors) can be used for traction operations to complete agricultural production tasks such as tilling, sowing, harvesting, and transportation. It can also be used in engineering construction and short-distance transportation. Agricultural machinery is mostly used on farmland and narrow paths between fields. During operation and travel, agricultural machinery is prone to experiencing bumpy roads, which reduces driver comfort and can easily lead to driver fatigue. Furthermore, in bumpy conditions, agricultural machinery will reduce its operating speed to ensure safety. Traditional agricultural machinery mostly has a rigid direct-drive front axle structure without shock absorption or height adjustment functions.

[0003] In related technologies, the stiffness of a vehicle's hydropneumatic suspension system is adjusted by adding air chambers and air-filled accumulators. The air chambers serve as the air source and their volume is adjustable. The charging ports of each damping air-filled accumulator are connected to the air chambers via their respective branch air lines, each with an on / off valve. The main air line has a proportional pressure reducing valve. A hydraulic pump delivers hydraulic oil to the pressure-regulating air-filled accumulator, increasing the pressure of nitrogen within it and causing the gas to expand. Then, by opening the on / off valves of each branch air line, the expanded nitrogen is delivered to each damping air-filled accumulator, thereby adjusting the stiffness of the vehicle's hydropneumatic suspension system. However, this method of changing the air pressure within the accumulator through air line adjustment is prone to air leakage, potentially causing safety hazards. Summary of the Invention

[0004] The purpose of this disclosure is to provide a vehicle hydropneumatic suspension system and its control method, as well as agricultural machinery, with the aim of improving the safety of stiffness adjustment of the vehicle hydropneumatic suspension system.

[0005] The first aspect of this disclosure provides a vehicle hydropneumatic suspension system, comprising:

[0006] A hydraulic pump is configured to supply hydraulic oil;

[0007] Two suspension cylinders are provided in the oil supply line of the hydraulic pump. Each suspension cylinder is equipped with a piston rod, which divides the space inside the suspension cylinder into a rod chamber and a rodless chamber.

[0008] The first accumulator is connected to the rod chambers corresponding to the two suspension cylinders;

[0009] The second accumulator is connected to the rodless chambers corresponding to the two suspension cylinders; and

[0010] The valve assembly, located in the oil line between the hydraulic pump and the two suspension cylinders, is configured to change the displacement of the piston rod according to operating conditions to adjust the relative position of the vehicle frame and axle, and / or change the pressure in the rod chamber to adjust the stiffness of the vehicle's hydropneumatic suspension system.

[0011] In some embodiments of the vehicle hydropneumatic suspension system, an oil tank is also included, the oil tank including a return port, and the valve assembly includes:

[0012] The first switching valve has an oil inlet connected to the oil supply port of the hydraulic pump and an oil outlet connected to the two rod chambers.

[0013] The second switching valve has an oil inlet connected to the oil supply port and an oil outlet connected to the two rodless chambers.

[0014] A third switching valve, wherein the oil inlet of the third switching valve is connected to both rod chambers, and the oil outlet of the third switching valve is connected to the oil return port; and

[0015] The fourth switching valve has an oil inlet that is connected to the two rodless chambers and an oil outlet that is connected to the oil return port.

[0016] In some embodiments of the vehicle hydropneumatic suspension system, the hydraulic pump includes a load-sensitive pump, and the valve assembly further includes:

[0017] A shuttle valve includes a first hydraulic inlet, a second hydraulic inlet, and a hydraulic outlet. The first hydraulic inlet is connected to the oil supply line between the oil supply port and the first switching valve. The second hydraulic inlet is connected to the oil supply line between the oil supply port and the second switching valve.

[0018] The directional valve has a first oil port, a second oil port, and a third oil port. The first oil port is connected to the hydraulic outlet, the second oil port is connected to the return oil port, and the third oil port is connected to the load-sensitive port of the load-sensitive pump. The directional valve has a first working position and a second working position. In the first working position, the first oil port is connected to the third oil port, and in the second working position, the first oil port is connected to the second oil port.

[0019] In some embodiments of the vehicle hydropneumatic suspension system, a displacement sensor disposed in the suspension cylinder or an angle sensor disposed on the vehicle frame is also included, the displacement sensor and the angle sensor being configured to detect the stroke of the piston rod.

[0020] In some embodiments of the vehicle hydropneumatic suspension system, the pressure sensor is also included, which is configured to detect the pressure within the rod chamber.

[0021] In some embodiments of the vehicle's hydropneumatic suspension system, the system has a manual lifting mode.

[0022] In the manual lifting mode, the suspension cylinder is in a rising state, which sequentially includes a first stroke stage and a second stroke stage.

[0023] The valve assembly is configured to, during the first stroke phase, simultaneously circulate hydraulic oil into the rod chamber and the rodless chamber to allow the piston rod to extend at a constant speed; and during the second stroke phase, circulate the hydraulic oil into the rodless chamber while the rod chamber is locked, causing the piston rod to extend at a reduced speed until it reaches its first limit stroke; and / or

[0024] In the manual lifting mode, the suspension cylinder is in a lowered state.

[0025] The descent state sequentially includes a third stroke stage and a fourth stroke stage. The valve assembly is configured to, during the third stroke stage, allow hydraulic oil to flow into the rod chamber and allow oil to return from the rodless chamber, so that the piston rod retracts at a constant speed; and during the fourth stroke stage, allow hydraulic oil to flow into the rod chamber and lock the rodless chamber, so that the piston rod decelerates and retracts until it reaches the second limit stroke.

[0026] In some embodiments of the vehicle hydropneumatic suspension system, the vehicle hydropneumatic suspension system has a maximum stiffness mode.

[0027] In the maximum stiffness mode, the valve assembly is configured to, when the vehicle speed reaches a first preset speed and the travel distance reaches a preset distance, only allow hydraulic oil to flow into the rod chamber until the first preset pressure is reached; when the vehicle speed exceeds a second preset speed, allow oil to return from the rod chamber until the second preset pressure is reached; and when the vehicle speed decreases to a third preset speed, allow hydraulic oil to flow into the rod chamber until the pressure returns to the first preset pressure.

[0028] Wherein, the second preset pressure is less than the first preset pressure, and the third preset speed is between the first preset speed and the second preset speed.

[0029] In some embodiments of the vehicle hydropneumatic suspension system, the vehicle hydropneumatic suspension system has an automatic mode in which the valve group is configured to adjust the piston rod to the middle position of its stroke as an initial position by uniformly raising and lowering it, and based on the initial position, adjust the pressure in the rod chamber according to at least one of vehicle speed, road conditions and vehicle engine speed to change the stiffness of the vehicle hydropneumatic suspension system.

[0030] In some embodiments of the vehicle hydropneumatic suspension system, the vehicle hydropneumatic suspension system includes two second accumulators, and the two second accumulators are respectively connected to the rodless chambers corresponding to the two suspension cylinders.

[0031] A second aspect of this disclosure provides agricultural machinery, including the vehicle hydropneumatic suspension system described in the above embodiments.

[0032] In some embodiments of the agricultural machinery, the following are also included:

[0033] The first detection device is configured to detect the travel speed of the agricultural machinery;

[0034] The second detection device is configured to detect engine speed;

[0035] A third detection device is configured to detect the travel distance of the agricultural machinery; and

[0036] The controller is configured to control the operating state of the valve assembly based on the detection results of at least one of the first detection device, the second detection device, and the third detection device.

[0037] A third aspect of this disclosure provides a control method for a vehicle hydropneumatic suspension system based on the above embodiments, comprising:

[0038] Obtain the vehicle's operating conditions;

[0039] The working state of the valve group is controlled according to the operating conditions.

[0040] In some embodiments of the control method, obtaining the vehicle's operating conditions further includes:

[0041] The operating modes of the vehicle's hydropneumatic suspension system are obtained, including manual lifting mode, automatic mode, and maximum stiffness mode.

[0042] In the maximum stiffness mode, the vehicle speed and travel distance are obtained;

[0043] In the automatic mode, the vehicle speed, the piston rod stroke, and the engine speed are acquired.

[0044] In some embodiments of the control method, controlling the operating state of the valve group according to the operating conditions in the manual lifting mode includes:

[0045] Control the suspension cylinder to be in the raised state;

[0046] The suspension cylinder is controlled to be in a lowering state.

[0047] In some embodiments of the control method, the ascending state sequentially includes a first stroke stage and a second stroke stage, and the descending state sequentially includes a third stroke stage and a fourth stroke stage.

[0048] In the manual lifting mode, controlling the suspension cylinder to be in the lifting state includes:

[0049] During the first stroke phase, hydraulic oil is simultaneously supplied to both the rod chamber and the rodless chamber to allow the piston rod to extend at a uniform speed; and / or

[0050] During the second stroke phase, hydraulic oil is introduced into the rodless chamber, and the rod chamber is locked, so that the piston rod decelerates and extends until it reaches the first limit stroke.

[0051] In the manual lifting mode, controlling the suspension cylinder to be in a lowering state includes:

[0052] In the third stroke phase, hydraulic oil is introduced into the rod chamber and oil is returned to the rodless chamber, so that the piston rod retracts at a uniform speed; and / or

[0053] In the fourth stroke stage, hydraulic oil is introduced into the rod chamber, and the rodless chamber is locked, so that the piston rod decelerates and retracts until it reaches the second limit stroke.

[0054] In some embodiments of the control method, controlling the operating state of the valve assembly according to the operating conditions in the maximum stiffness mode includes:

[0055] When the vehicle speed reaches the first preset speed and the travel distance reaches the preset distance, hydraulic oil is only introduced into the rod chamber until the first preset pressure is reached;

[0056] If the vehicle speed exceeds the second preset speed, the rod chamber will return oil until the second preset pressure is reached;

[0057] When the vehicle speed decreases to the third preset speed, hydraulic oil is introduced into the rod chamber until it returns to the first preset pressure.

[0058] In some embodiments of the control method, in the automatic mode, controlling the operating state of the valve group according to the operating conditions includes:

[0059] The piston rod is adjusted to the middle position of its stroke by a constant speed of lifting and lowering, which serves as the initial position.

[0060] Based on the initial position, the pressure in the rod chamber is adjusted according to at least one of vehicle speed, road conditions, and vehicle engine speed to change the stiffness of the vehicle's hydropneumatic suspension system.

[0061] Based on the vehicle hydropneumatic suspension system provided in this disclosure, the relative position of the vehicle frame and axle can be adjusted by changing the displacement of the piston rod according to operating conditions via a valve assembly, and / or by changing the pressure in the rod chamber to change the pressure of the suspension cylinder at the equilibrium position, thereby adjusting the attitude or stiffness of the vehicle hydropneumatic suspension system. This vehicle hydropneumatic suspension system reduces the need for components such as proportional pressure reducing valves, avoids adjusting the flow rate of the throttle valve, thus reducing adjustment difficulty. It also avoids adjusting system stiffness through an air path connected to the accumulator, thus preventing air leakage and improving the safety of stiffness adjustment in the vehicle hydropneumatic suspension system.

[0062] The agricultural machinery disclosed herein includes the embodiments described above, and thus has the advantages of the embodiments described above.

[0063] The control method disclosed herein includes the above embodiments, and thus has the advantages of the above embodiments of this disclosure.

[0064] Other features and advantages of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0065] The accompanying drawings, which are included to provide a further understanding of this disclosure and form part of this application, illustrate exemplary embodiments of this disclosure and are used to explain this disclosure, but do not constitute an undue limitation of this disclosure. In the drawings:

[0066] Figure 1 This is a schematic diagram of the hydraulic system of a vehicle hydropneumatic suspension system according to some embodiments of this disclosure.

[0067] Figure 2 This is a flowchart of a method for controlling the maximum stiffness mode of a vehicle hydropneumatic suspension system according to some embodiments of this disclosure.

[0068] Explanation of reference numerals in the attached figures:

[0069] 1. First check valve; 2. Safety valve; 3. First throttle valve; 4. Second throttle valve; 5. Fourth switching valve; 6. Controller; 7. Second switching valve; 8. Third throttle valve; 9. Second check valve; 10. Second accumulator; 11. First suspension cylinder; 12. First accumulator; 14. Second suspension cylinder; 15. Third check valve; 16. Fourth throttle valve; 17. First switching valve; 18. Third switching valve; 19. Fifth throttle valve; 20. Shuttle valve; 21. Sixth throttle valve; 22. Directional control valve; 23. Valve assembly; 24. Pressure sensor; 25. Displacement sensor;

[0070] Y1, First electromagnet; Y2, Second electromagnet; Y3, Third electromagnet; Y4, Fourth electromagnet; Y5, Fifth electromagnet;

[0071] T, return port; P, supply port; Ls, load-sensitive port. Detailed Implementation

[0072] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0073] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this disclosure. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0074] In the description of this disclosure, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this disclosure.

[0075] In the description of this disclosure, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are generally based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this disclosure and simplifying the description. Unless otherwise stated, these directional terms 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 on the scope of protection of this disclosure; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0076] In related technologies, some vehicle hydropneumatic suspension systems change system stiffness by altering the volume or air pressure of the accumulator, but this requires increasing the number of accumulators, control valve assemblies, or adding a new pump source, leading to increased costs. Some vehicle hydropneumatic suspension systems also change system stiffness by altering the size of the throttle valve between the accumulator and the suspension cylinder, but this requires an electro-proportional switching valve, making control more difficult and costly.

[0077] In response to the above problems, such as Figure 1 As shown, this disclosure provides a vehicle hydropneumatic suspension system. The vehicle hydropneumatic suspension system includes:

[0078] A hydraulic pump is configured to supply hydraulic oil;

[0079] Two suspension cylinders are located on the oil supply line of the hydraulic pump. The suspension cylinders are equipped with piston rods, which divide the space inside the suspension cylinders into rod chambers and rodless chambers.

[0080] The first accumulator 12 is connected to the rod chambers corresponding to the two suspension cylinders;

[0081] The second accumulator 10 is connected to the rodless chambers corresponding to the two suspension cylinders; and

[0082] Valve assembly 23, located in the oil line between the hydraulic pump and the two suspension cylinders, is configured to change the displacement of the piston rod according to the operating conditions to adjust the relative position of the vehicle frame and axle, and / or change the pressure in the rod chamber to adjust the stiffness of the vehicle's hydropneumatic suspension system.

[0083] The operating conditions include work status, vehicle speed, travel distance, piston rod stroke, and engine speed. By controlling valve assembly 23 to return oil to the rod chamber and reduce pressure, the stiffness of the vehicle's air suspension system decreases. Conversely, by controlling valve assembly 23 to allow oil to enter the rod chamber and increase pressure, the stiffness of the vehicle's air suspension system increases.

[0084] For example, such as Figure 1 As shown, the two suspension cylinders include a first suspension cylinder 11 and a second suspension cylinder 14.

[0085] If we take the piston rod of the suspension cylinder as the object of force, according to the force balance formula:

[0086] (1)

[0087] in, This refers to the pressure inside the rodless chamber of the suspension cylinder. Let A be the pressure in the rod chamber of the suspension cylinder, and let A be the cylinder barrel area of ​​the suspension cylinder. Let m be the piston rod area of ​​the suspension cylinder, and m be the bearing mass. The piston force formula (1) explains that by adjusting the pressure in the rod chamber of the suspension cylinder... The pressure in the rodless chamber of the suspension cylinder can be adjusted. .

[0088] Ignoring the changes in the gas polytropic index of the gas in the accumulator during operation, the accumulator volume and pressure have the following relationship:

[0089] (2)

[0090] in To increase the charging pressure of the accumulator, For the volume of the energy storage device, The gas pressure of the accumulator under any state. Let be the gas volume of the accumulator under any given state.

[0091] Since the stiffness of the gas spring is achieved through an accumulator, by creating a mathematical model of the gas spring stiffness—that is, by creating a mathematical theoretical model of the gas spring accumulator—the stiffness of the gas spring can be obtained. Relative displacement with piston The functional relationship between them is as follows:

[0092] (3)

[0093] in, The charging pressure for the rodless cavity accumulator, The charging pressure for rod-cavity accumulators. This refers to the total volume of the rodless cavity accumulator; The volume of the rod-shaped cavity accumulator; This refers to the gas volume inside the rodless cavity accumulator at the equilibrium position after oil filling. The volume of gas in the rod cavity accumulator at the equilibrium position after oil filling is denoted as r; r is the gas index, 1.0~1.4.

[0094] Therefore, according to the piston force formula (1), accumulator formula (2), and stiffness formula (3), it can be seen that changing the pressure in the rod chamber of the suspension cylinder at the equilibrium position can change the gas volume. and gas volume This allows for adjustment of the stiffness of the vehicle's hydropneumatic suspension system.

[0095] Based on the vehicle hydropneumatic suspension system provided in this embodiment, the valve assembly 23 adjusts the relative position of the vehicle frame and axle by changing the displacement of the piston rod according to operating conditions, and / or changes the pressure in the rod chamber to change the pressure of the suspension cylinder at the equilibrium position, thereby adjusting the attitude or stiffness of the vehicle hydropneumatic suspension system. This vehicle hydropneumatic suspension system reduces the need for components such as proportional pressure reducing valves, avoids adjusting the flow rate of the throttle valve, reduces adjustment difficulty, and avoids adjusting system stiffness through an air path connected to the accumulator, thus preventing air leakage and improving the safety of stiffness adjustment in the vehicle hydropneumatic suspension system.

[0096] like Figure 1 As shown, in some embodiments, the vehicle hydropneumatic suspension system further includes an oil tank, which includes an oil return port T, and the valve assembly 23 includes:

[0097] The first switching valve 17 has an oil inlet connected to the oil supply port P of the hydraulic pump, and an oil outlet connected to two rod chambers.

[0098] The second switching valve 7 has an oil inlet connected to the oil supply port P and an oil outlet connected to two rodless chambers.

[0099] The third switching valve 18 has an inlet port connected to two rod chambers and an outlet port connected to the return port T.

[0100] The fourth switching valve 5 has an oil inlet that is connected to two rodless chambers and an oil outlet that is connected to the return port T.

[0101] For example, the first switching valve 17, the second switching valve 7, the third switching valve 18, and the fourth switching valve 5 can be solenoid valves. When the first electromagnet Y1 is energized, the first switching valve 17 opens, and the hydraulic pump fills the two rod chambers with oil through the oil supply port P. When the second electromagnet Y2 is energized, the second switching valve 7 opens, and the hydraulic pump fills the two rodless chambers with oil through the oil supply port P. When the third electromagnet Y3 is energized, the third switching valve 18 opens, and the hydraulic oil in the two rod chambers flows to the return port T. When the fourth electromagnet Y4 is energized, the fourth switching valve 5 opens, and the hydraulic oil in the two rodless chambers flows to the return port T.

[0102] The first switching valve 17, the second switching valve 7, the third switching valve 18 and the fourth switching valve 5 work together to extend or retract the piston rod to change the relative position of the frame and the axle, or to change the stiffness of the vehicle's hydropneumatic suspension system by changing the pressure in the rod chamber. The reduced number of valves helps to reduce the difficulty of control and improve the efficiency of stiffness adjustment.

[0103] like Figure 1As shown, in some embodiments, the vehicle's hydropneumatic suspension system further includes a first check valve 1, a second check valve 9, a third check valve 15, and a safety valve 2. The first check valve 1 is disposed on the common return oil line between the third switching valve 18 and the return port T, and the fourth switching valve 5 and the return port T. The first check valve 1 only allows hydraulic oil to flow in the return direction. The second check valve 9 is connected in parallel with the third throttle valve 8 on the common supply oil line between the second switching valve 7 and the rodless chamber, and the fourth switching valve 5 and the rodless chamber. The second check valve 9 only allows hydraulic oil to flow into the rodless chamber in the supply direction. The third check valve 15 is connected in parallel with the fourth throttle valve 16 on the oil line between the first switching valve 17 and the rod chamber, and the third switching valve 18 and the rod chamber. The third check valve 15 only allows hydraulic oil to flow into the rod chamber in the supply direction. Setting up a one-way valve is beneficial for cooperating with the corresponding oil circuit's switching valve and throttle valve to achieve one-way flow control of the oil in each oil circuit. This helps prevent oil backflow and ensures the stable execution of actions such as lifting, stiffness adjustment, etc., of the vehicle's hydropneumatic suspension system.

[0104] Safety valve 2 is connected in parallel between the oil supply port P and the oil return port T to limit the maximum oil supply pressure of the vehicle's hydropneumatic suspension system, which helps to prevent the hydraulic pump from outputting excessive pressure and damaging components.

[0105] like Figure 1 As shown, in some embodiments, a first throttle valve 3 is provided between the oil supply port P and the second switching valve 7. A sixth throttle valve 21 is provided between the oil supply port P and the first switching valve 17. The first throttle valve 3 and the sixth throttle valve 21 are fixed throttle valves, and the flow rate through these two throttle valves is a constant value to ensure that the suspension cylinder rises at a uniform speed. The size of the first throttle valve 3 and the sixth throttle valve 21 determines the uniform rising speed of the suspension cylinder.

[0106] like Figure 1 As shown, in some embodiments, a second throttle valve 4 is provided between the return port T and the fourth switching valve 5. A fifth throttle valve 19 is provided between the return port T and the third switching valve 18.

[0107] The second throttle valve 4 and the fifth throttle valve 19 help reduce the backflow speed of hydraulic oil, avoid backflow impact, and improve the stability of stiffness adjustment.

[0108] like Figure 1 As shown, in some embodiments, the hydraulic pump includes a load-sensitive pump, and valve assembly 23 further includes:

[0109] Shuttle valve 20 includes a first hydraulic inlet, a second hydraulic inlet, and a hydraulic outlet. The first hydraulic inlet is connected to the oil supply line between the oil supply port P and the first switching valve 17, and the second hydraulic inlet is connected to the oil supply line between the oil supply port P and the second switching valve 17.

[0110] The directional valve 22 has a first oil port, a second oil port and a third oil port. The first oil port is connected to the hydraulic outlet, the second oil port is connected to the return oil port T, and the third oil port is connected to the load-sensitive port Ls of the load-sensitive pump. The directional valve 22 has a first working position and a second working position. In the first working position, the first oil port is connected to the third oil port, and in the second working position, the first oil port is connected to the second oil port.

[0111] Among them, the shuttle valve 20 collects the pressure of the oil supply line between the oil supply port P and the first switching valve 17 through the first hydraulic inlet, and collects the pressure of the oil supply line between the oil supply port P and the second switching valve 7 through the second hydraulic inlet. It can filter out the oil line with higher pressure through pressure comparison, and then output the highest pressure signal through the hydraulic outlet one-way directional valve 22.

[0112] In this system, the first port of the directional control valve 22 receives the highest pressure signal output from the shuttle valve 20. When the fifth electromagnet Y5 is energized, the directional control valve 22 switches to the first operating position, transmitting the highest pressure signal to the third port and cutting off the connection with the second port, allowing the hydraulic pump to supply power as needed. When the fifth electromagnet Y5 is de-energized, the directional control valve 22 switches to the second operating position, cutting off the transmission of the highest pressure signal and releasing the pressure from the third port to the return port T via the second port.

[0113] The combination of shuttle valve 20 and directional valve 22 facilitates precise selection of the highest load pressure in the two oil supply circuits of the hydraulic cylinder and transmits it to the load-sensitive pump as needed. This allows the vehicle's hydropneumatic suspension system to supply oil as required under different operating conditions, ensuring the stability and accuracy of suspension lifting and stiffness adjustment. Furthermore, the directional valve 22 can cut off the highest pressure signal transmitted by shuttle valve 20 and relieve the pressure at the load-sensitive port Ls to the return port T, thus enabling the load-sensitive pump to operate at low pressure and save energy.

[0114] like Figure 1 As shown, in some embodiments, the vehicle hydropneumatic suspension system further includes a displacement sensor 25 disposed in the suspension cylinder or an angle sensor disposed on the frame, the displacement sensor or angle sensor being configured to detect the stroke of the piston rod.

[0115] For example, the cylinder of the suspension cylinder can be connected to the vehicle frame, and the piston rod of the suspension cylinder can be connected to the axle. An angle sensor is configured to detect the angular change between the vehicle frame and the axle, and obtain the displacement of the piston rod through this angular change.

[0116] Setting up an angle sensor or displacement sensor 25 is beneficial for accurately detecting the stroke of the suspension cylinder, thereby accurately grasping the real-time vibration of the suspension cylinder, which in turn facilitates precise adjustment of stiffness according to working conditions.

[0117] like Figure 1As shown, in some embodiments, the vehicle hydropneumatic suspension system also includes a pressure sensor 24 configured to detect pressure within the rod chamber.

[0118] Setting up a pressure sensor is beneficial for real-time detection of the pressure inside the rod chamber, which is conducive to precise pressure control and signal feedback of the vehicle's hydropneumatic suspension system in various operating modes. It also helps to improve the accuracy of the rod chamber's oil filling and discharging control, thereby ensuring the accuracy and stability of stiffness adjustment.

[0119] In some embodiments, the vehicle's hydropneumatic suspension system has a manual lifting mode. In the manual lifting mode, the suspension cylinder has an upward state, which includes a first stroke stage and a second stroke stage in sequence.

[0120] Valve assembly 23 is configured to, during the first stroke phase, simultaneously supply hydraulic oil to the rod chamber and the rodless chamber to allow the piston rod to extend at a uniform speed; and during the second stroke phase, supply hydraulic oil to the rodless chamber and lock the rod chamber to allow the piston rod to extend at a reduced speed until it reaches the first limit stroke; and / or

[0121] In manual lifting mode, the vehicle's hydropneumatic suspension system has a lowering state.

[0122] The descent state includes a third stroke stage and a fourth stroke stage. Valve group 23 is configured to allow hydraulic oil to flow into the rod chamber and return oil to the rodless chamber during the third stroke stage, so that the piston rod retracts at a constant speed; and to allow hydraulic oil to flow into the rod chamber and lock the rodless chamber during the fourth stroke stage, so that the piston rod decelerates and retracts until it reaches the second limit stroke.

[0123] In the upward position of the suspension cylinder, the piston rod extends. Since the piston rod is connected to the axle, and the axle remains stationary relative to the ground, the cylinder can move the vehicle frame upward relative to the ground. In the downward position of the suspension cylinder, the piston rod retracts, and the cylinder can move the vehicle frame downward relative to the ground.

[0124] For example, at the end of the first stroke stage, the distance between the piston rod's stroke position and the first limit stroke can be between 10mm and 20mm. At the end of the third stroke stage, the distance between the piston rod's stroke position and the second limit stroke can be between 10mm and 20mm.

[0125] In the first stroke phase, the piston rod is extended and moves towards its first limit stroke. Valve group 23 controls the simultaneous intake of oil into the rod chamber and the rodless chamber. Since the area of ​​the rodless chamber is larger than that of the rod chamber, under the same pressure, the pressure in the rodless chamber is greater than that in the rod chamber, thereby causing the piston rod to extend and the suspension cylinder to be in an ascending state. The first throttle valve 3 and the sixth throttle valve 21 are configured as fixed throttle valves, meaning that the flow rate through these two throttle valves is constant, thus achieving uniform piston rod extension.

[0126] During the second stroke, valve group 23 controls the locking of the rod chamber. As oil continues to enter the rodless chamber of the suspension cylinder, the piston rod extension gradually increases, the gas in the first accumulator 12 is compressed, the pressure in the rod chamber gradually increases, and the piston rod extension speed of the suspension cylinder gradually slows down, thereby achieving decelerated extension of the piston rod.

[0127] In the third stroke phase, the piston rod is retracted and moves towards the second limit stroke. Valve group 23 controls the oil inlet to the rod chamber and the oil return to the rodless chamber, making the pressure in the rodless chamber lower than the pressure in the rod chamber, thereby causing the piston rod to retract and the suspension cylinder to be in the lowered state.

[0128] In the fourth stroke stage, valve group 23 controls the oil intake of the rod chamber and locks the rodless chamber. As the gas in the two second accumulators 10 is compressed, the pressure in the rodless chamber gradually increases, thereby achieving piston rod deceleration and retraction. The second throttle valve 4 and the fifth throttle valve 19 are configured as fixed throttle valves, that is, the flow rate through these two throttle valves is constant, thereby achieving uniform piston rod retraction.

[0129] Due to differences in driving habits, drivers need to adjust the axle's position relative to the chassis when performing agricultural operations to improve visibility and comfort. In this case, the driver can select the manual lifting mode.

[0130] In manual lifting mode, when the suspension cylinder rises, it first extends at a constant speed by simultaneously feeding oil into the rod chamber and the rodless chamber. When it approaches the first limit stroke, it switches to a decelerated extension by feeding oil into the rodless chamber and locking the rod chamber. When the suspension cylinder descends, it first retracts at a constant speed by feeding oil into the rod chamber and returning oil from the rodless chamber. When it approaches the second limit stroke, it switches to a decelerated retraction by feeding oil into the rod chamber and locking the rodless chamber. This deceleration lifting and lowering before the limit position effectively reduces the impact generated by the suspension cylinder at the limit stroke position.

[0131] In some embodiments, the vehicle's hydropneumatic suspension system has a maximum stiffness mode.

[0132] In the maximum stiffness mode, valve assembly 23 is configured to, when the vehicle speed reaches the first preset speed and the travel distance reaches the preset distance, only allow hydraulic oil to flow into the rod chamber until the first preset pressure is reached; when the vehicle speed exceeds the second preset speed, allow oil to return from the rod chamber until the second preset pressure is reached; when the vehicle speed decreases to the third preset speed, allow hydraulic oil to flow into the rod chamber until the pressure returns to the first preset pressure.

[0133] The second preset pressure is less than the first preset pressure, and the third preset speed is between the first preset speed and the second preset speed.

[0134] In this configuration, oil is introduced only into the rod chamber while the rodless chamber is locked. The gas in the first accumulator 12 and the second accumulator 10 is compressed, causing the pressure in the rod chamber to gradually increase, and consequently, the pressure in the rodless chamber also increases, thus increasing the stiffness of the vehicle's hydropneumatic suspension system. Conversely, oil is returned only from the rod chamber, causing the pressure in both the rod chamber and the rodless chamber to decrease, thus reducing the stiffness of the vehicle's hydropneumatic suspension system.

[0135] For example, the first preset speed ranges from 0.3 to 1 km / h, the second preset speed ranges from 25 to 35 km / h, and the third preset speed ranges from 18 to 22 km / h.

[0136] For example, the preset distance range is 3~7m.

[0137] Hydropneumatic suspension systems are commonly used in agricultural machinery such as tractors. These machines may perform deep tillage and plowing operations, requiring increased traction from the rear suspension. Therefore, the stiffness of the hydropneumatic suspension system must be maximized, meaning it needs to be in maximum stiffness mode. In maximum stiffness mode, the system can raise the rod chamber pressure to a first preset pressure when the vehicle speed and travel distance meet certain conditions, maximizing stiffness and enhancing rear suspension traction. It can also dynamically adjust the rod chamber pressure according to changes in vehicle speed, adapting to different driving conditions and ensuring operational needs and driving stability. Furthermore, setting preset speed and distance control conditions helps prevent accidental activation of maximum stiffness mode by the driver when the vehicle is stationary.

[0138] In some embodiments, the vehicle hydropneumatic suspension system has an automatic mode in which the valve assembly 23 is configured to adjust the piston rod to the middle position of its stroke as an initial position by uniformly raising and lowering it, and based on the initial position, adjust the pressure in the rod chamber according to at least one of vehicle speed, road conditions and vehicle engine speed to change the stiffness of the vehicle hydropneumatic suspension system.

[0139] The automatic mode can adjust the attitude and stiffness of the suspension cylinders in a timely manner according to the vehicle's load status, speed and road conditions, which helps to ensure that the vehicle's hydropneumatic suspension system maintains a high level of vibration reduction and improves the vehicle's stability and comfort under various road conditions.

[0140] like Figure 1 As shown, in some embodiments, the vehicle hydropneumatic suspension system includes two second accumulators 10, which are respectively connected to the rodless chambers corresponding to the two suspension cylinders.

[0141] During stiffness adjustment, the rodless chamber bears greater pressure than the rod chamber, therefore the required volume of the second accumulator 10 is greater than that of the first accumulator 12. Providing two second accumulators 10, each connected to the rodless chamber of one of the two suspension cylinders, facilitates standardized accumulator specifications and reduces manufacturing costs. Another aspect of this disclosure provides an agricultural machine including the vehicle hydropneumatic suspension system provided in this disclosure.

[0142] The agricultural machinery of this disclosure has the advantages of the vehicle hydropneumatic suspension system of this disclosure.

[0143] In some embodiments, the agricultural machinery further includes:

[0144] The first detection device is configured to detect the travel speed of agricultural machinery;

[0145] The second detection device is configured to detect engine speed;

[0146] The third detection device is configured to detect the travel distance of agricultural machinery; and

[0147] The controller 6 is configured to control the operating state of the valve group 23 based on the detection results of at least one of the first detection device, the second detection device, and the third detection device.

[0148] For example, the first detection device can be a displacement sensor or a speed sensor, etc. The second detection device can be a speed sensor, etc. The third detection device can be a displacement sensor, etc.

[0149] The controller 6 may be implemented as a general-purpose processor, a programmable logic controller (PLC), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, or any suitable combination thereof for performing the functions described in this disclosure.

[0150] The arrangement of a first detection device, a second detection device, a third detection device, and a controller 6 facilitates the real-time acquisition of information such as the travel speed, engine speed, and travel distance of agricultural machinery. This allows the controller 6 to precisely regulate the working state of the valve group 23 based on at least one piece of acquired data, thereby improving the speed and accuracy of stiffness adjustment. Another aspect of this disclosure provides a control method for a vehicle hydropneumatic suspension system based on embodiments of this disclosure, including:

[0151] Obtain the vehicle's operating conditions;

[0152] The working status of valve group 23 is controlled according to the operating conditions.

[0153] The control method of this disclosure has the advantages of the vehicle hydropneumatic suspension system of this disclosure.

[0154] In some embodiments, obtaining the vehicle's operating conditions further includes:

[0155] The operating modes of the vehicle's hydropneumatic suspension system are obtained, including manual lifting mode, automatic mode, and maximum stiffness mode.

[0156] In maximum stiffness mode, obtain vehicle speed and travel distance;

[0157] In automatic mode, the vehicle speed, piston rod stroke, and generator speed are obtained.

[0158] This control method obtains corresponding operating parameters (vehicle speed, driving distance, piston rod stroke, etc.) by classifying them according to working modes. This is beneficial for accurately controlling the working state of valve group 23 based on operating parameters, for adapting the stiffness adjustment of the vehicle's hydropneumatic suspension system to the vehicle's operating conditions, and for ensuring vehicle stability during operation and driving.

[0159] In some embodiments, in manual lifting mode, controlling the operating state of valve assembly 23 according to operating conditions includes:

[0160] Control the suspension cylinder to be in the raised state;

[0161] The control suspension cylinder is in the lowering state.

[0162] In manual lifting mode, stiffness is adjusted by directly controlling the suspension cylinder to be in the rising or falling state. Compared with directly controlling the accumulator, this helps to avoid air leakage problems in the pipeline and improves the safety of stiffness adjustment of the vehicle's hydropneumatic suspension system.

[0163] In some embodiments, the ascending state includes a first stroke stage and a second stroke stage in sequence, and the descending state includes a third stroke stage and a fourth stroke stage in sequence.

[0164] In manual lifting mode, controlling the suspension cylinder to be in the raised state includes:

[0165] During the first stroke, hydraulic oil is simultaneously supplied to both the rod chamber and the rodless chamber to ensure the piston rod extends at a uniform speed; and / or

[0166] In the second stroke phase, hydraulic oil is introduced into the rodless chamber and the rod chamber is locked, so that the piston rod decelerates and extends until it reaches the first limit stroke.

[0167] In manual lifting mode, controlling the suspension cylinder to be in the lowering state includes:

[0168] During the third stroke, hydraulic oil is introduced into the rod chamber and returned to the rodless chamber, so that the piston rod retracts at a uniform speed; and / or

[0169] In the fourth stroke stage, hydraulic oil is introduced into the rod chamber and the rodless chamber is locked, so that the piston rod decelerates and retracts until it reaches the second limit stroke.

[0170] In the first stroke phase, the hydraulic oil output from the hydraulic pump flows through two supply lines to the rod chamber and rodless chamber of the suspension cylinder, respectively. One line flows through the sixth throttle valve 21, the first switching valve 17, and the third check valve 15 into the rod chamber of the first suspension cylinder 11 and the second suspension cylinder 14, and then into the first accumulator 12. The other line flows through the first throttle valve 3, the second switching valve 7, and the second check valve 9 into the two rodless chambers, and then into the two second accumulators 10. The shuttle valve 20 transmits the maximum pressure in the rodless and rod chambers to the load-sensitive pump through the reversing valve 22, thereby regulating the pressure and flow rate output by the load-sensitive pump.

[0171] During the second stroke, hydraulic oil continues to flow into the two rodless chambers through the first throttle valve 3, the second switching valve 7, and the second check valve 9. However, at this time, the first switching valve 17 and the third switching valve 18 are closed, locking the rod chambers. After the piston rod moves to its first limit stroke, the second switching valve 7 and the directional valve 22 are closed.

[0172] During the third stroke, hydraulic oil flows into the rod chambers of the first suspension cylinder 11 and the second suspension cylinder 14 through the sixth throttle valve 21, the first switching valve 17 and the third check valve 15, then flows into the first accumulator 12, and returns to the return port T through the third throttle valve 8, the fourth switching valve 5, the second throttle valve 4 and the first check valve 1.

[0173] During the fourth stroke, hydraulic oil flows through the sixth throttle valve 21, the first switching valve 17, and the third check valve 15 into the rod chambers of the first suspension cylinder 11 and the second suspension cylinder 14, and then into the first accumulator 12. At this time, the second switching valve 7 and the fourth switching valve 5 are closed, locking the rodless chamber. After the piston rod moves to its second limit stroke, the first switching valve 17 and the directional valve 22 are closed.

[0174] In manual lifting mode, the piston rod is extended and retracted at a constant speed, and deceleration is achieved by controlling the filling, discharging and locking of the rod chamber and the rodless chamber in stages. This control method can effectively reduce the impact of the suspension cylinder in the first and second limit strokes, which is beneficial to protecting the hydraulic components of the vehicle's hydropneumatic suspension system. At the same time, it ensures the stability of the lifting process and is suitable for the manual adjustment of suspension height in agricultural machinery.

[0175] In some embodiments, in the maximum stiffness mode, controlling the operating state of the valve assembly 23 according to the operating conditions includes:

[0176] When the vehicle speed reaches the first preset speed and the travel distance reaches the preset distance, hydraulic oil is only introduced into the rod chamber until the first preset pressure is reached;

[0177] If the vehicle speed exceeds the second preset speed, the rod chamber will return oil until the second preset pressure is reached;

[0178] When the vehicle speed is reduced to the third preset speed, hydraulic oil is introduced into the rod chamber until the pressure is restored to the first preset pressure.

[0179] Oil is only introduced into the hydraulic cylinder's rod chamber when the vehicle speed reaches a preset level and the travel distance reaches a preset distance. This prevents accidental activation of the maximum stiffness mode by the driver when the machine is stationary, and avoids the suspension cylinder's rod chamber from continuously being pressurized to its maximum pressure, thus preventing the suspension from remaining in a stiff state for extended periods. This helps prevent excessive wear on the suspension cylinder and issues like start-up bumps. Furthermore, this control method allows for controlling the rod chamber's oil filling to achieve maximum stiffness according to a set pressure, which is beneficial for meeting the traction requirements of deep tillage and plowing operations. Additionally, dynamically adjusting stiffness based on vehicle speed helps prevent excessive vehicle jolting during transfers due to excessive stiffness, thereby improving vehicle comfort during driving.

[0180] In some implementations, in automatic mode, the operating state of valve assembly 23 is controlled according to operating conditions, including:

[0181] The piston rod is adjusted to the middle position of its stroke by a constant speed of lifting and lowering, which serves as the initial position.

[0182] Based on the initial position, the pressure in the rod chamber is adjusted according to at least one of vehicle speed, road conditions, and vehicle engine speed to change the stiffness of the vehicle's hydropneumatic suspension system.

[0183] For example, when the vehicle speed reaches the fourth preset speed, the rod chamber is returned to oil, which reduces the pressure in the rod chamber and the rodless chamber, thereby reducing the stiffness of the vehicle's hydropneumatic suspension system. When the vehicle speed reaches the fifth preset speed, valve group 23 controls the oil to enter the rod chamber, which increases the pressure in the rod chamber and the rodless chamber, thereby increasing the stiffness of the vehicle's hydropneumatic suspension system.

[0184] For example, road conditions can be judged based on the amount of piston rod vibration per unit time. When the amount of piston rod vibration per unit time is greater than a first preset vibration amount, valve group 23 controls the oil to enter the rod chamber, increasing the pressure in both the rod and rodless chambers, thereby increasing the stiffness of the vehicle's hydropneumatic suspension system. When the amount of piston rod vibration per unit time is less than a second preset vibration amount, valve group 23 controls the oil to return from the rod chamber, decreasing the pressure in both the rod and rodless chambers, thereby decreasing the stiffness of the vehicle's hydropneumatic suspension system.

[0185] For example, when the engine speed is greater than or equal to the preset speed, valve assembly 23 controls the oil intake in the rod chamber, increasing the pressure in both the rod and rodless chambers, thereby increasing the stiffness of the vehicle's hydropneumatic suspension system. When the engine speed is less than the preset speed, valve assembly 23 controls the oil return in the rod chamber, decreasing the pressure in both the rod and rodless chambers, thereby decreasing the stiffness of the vehicle's hydropneumatic suspension system. The preset speed range is 1800 rpm to 2500 rpm.

[0186] In automatic mode, the piston rod is first adjusted to the middle position of its stroke at a constant speed, which helps to provide a stable initial basis for stiffness adjustment. Then, the piston rod position is dynamically adjusted in combination with at least one of the working conditions, such as vehicle speed, road conditions, and load, which helps to achieve adaptive adjustment of suspension stiffness. This ensures the accuracy of agricultural machinery operation, improves ride smoothness and driving comfort, and helps the vehicle's hydropneumatic suspension system adapt to complex and changing working and driving conditions.

[0187] The following combination Figure 1 and Figure 2 The control method of the vehicle hydropneumatic suspension system according to the embodiments of this disclosure will be described in detail.

[0188] (1) When the vehicle speed is ≤5km, turn on the manual lifting mode.

[0189] Open the first switching valve 17, the second switching valve 7, and the reversing valve 22 to bring the vehicle's hydropneumatic suspension system into the first stroke stage of its upward state. During the first stroke stage, the piston rod moves towards its first limit stroke and ends the first stroke stage 15mm away from the first limit stroke.

[0190] When the displacement sensor 25 inside the suspension cylinder detects that the piston rod has moved to a distance of 15mm from the first limit stroke, the second switch valve 7 and the reversing valve 22 are opened, and the first switch valve 17 is closed, so that the vehicle's hydropneumatic suspension system is in the second stroke stage of the rising state until the piston rod moves to the first limit stroke.

[0191] After the displacement sensor 25 inside the suspension cylinder detects that the piston rod has moved to the first limit stroke, the second switching valve 7 and the reversing valve 22 are closed.

[0192] Opening the first switching valve 17, the fourth switching valve 5, and the directional valve 22 puts the vehicle's hydropneumatic suspension system into the third stroke stage of its descent. During the third stroke stage, the piston rod moves towards its second limit stroke and ends the third stroke stage 15mm from the second limit stroke.

[0193] When the displacement sensor 25 inside the suspension cylinder detects that the piston rod has moved to a distance of 15mm from the second limit stroke, the first switch valve 17 and the reversing valve 22 are opened, and the fourth switch valve 5 is closed, so that the vehicle's hydropneumatic suspension system is in the fourth stroke stage of the descent state until the piston rod moves to the second limit stroke.

[0194] After the displacement sensor 25 inside the suspension cylinder detects that the piston rod has moved to the second limit stroke and stops, the first switching valve 17 and the reversing valve 22 are closed.

[0195] (2) Enable maximum stiffness mode

[0196] like Figure 2 As shown, after manually clicking to trigger the maximum stiffness mode, when the vehicle speed is detected to be ≥0.5km / h and the driving distance is ≥5m, the first switch valve 17 and the reversing valve 22 are opened.

[0197] When the pressure sensor detects that the pressure in the rod chamber has reached the first preset pressure, the first switching valve 17 and the reversing valve 22 are closed.

[0198] When the vehicle speed exceeds 30 km / h, the third switch valve 18 is opened, and when the pressure in the rod chamber reaches the second preset pressure, the third switch valve 18 is closed.

[0199] When the vehicle speed is detected to drop to 20km / h, the first switching valve 17 and the reversing valve 22 are reopened until the pressure sensor detects that the pressure in the rod chamber reaches the first preset pressure, and then the first switching valve 17 and the reversing valve 22 are closed.

[0200] (3) Turn on automatic mode

[0201] Open the first switch valve 17, the second switch valve 7, and the reversing valve 22 to put the vehicle's hydropneumatic suspension system into the first stroke stage of the upward state, or open the first switch valve 17, the fourth switch valve 5, and the reversing valve 22 to put the vehicle's hydropneumatic suspension system into the third stroke stage of the downward state, until the piston rod moves to the middle position of the stroke.

[0202] When the vehicle speed is detected to reach the fourth preset speed, only the third switch valve 18 is opened. When the vehicle speed is detected to reach the fifth preset speed, only the first switch valve 17 and the reversing valve 22 are opened.

[0203] When the piston rod vibration amplitude detected per unit time is greater than the first preset vibration amplitude, only the first switching valve 17 and the reversing valve 22 are opened. When the piston rod vibration amplitude detected per unit time is less than the second preset vibration amplitude, only the third switching valve 18 is opened.

[0204] When the transmitter speed is detected to be greater than or equal to the preset speed, only the first switching valve 17 and the reversing valve 22 are opened. When the transmitter speed is detected to be less than the preset speed, only the third switching valve 18 is opened.

[0205] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and not to limit them; although this disclosure has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this disclosure or equivalent substitutions can be made to some technical features, all of which should be covered within the scope of the technical solutions claimed in this disclosure.

Claims

1. A vehicle hydropneumatic suspension system, characterized in that, include: A hydraulic pump is configured to supply hydraulic oil; Two suspension cylinders are provided in the oil supply line of the hydraulic pump. Each suspension cylinder is equipped with a piston rod, which divides the space inside the suspension cylinder into a rod chamber and a rodless chamber. The first accumulator (12) is connected to the rod chambers corresponding to the two suspension cylinders; The second accumulator (10) is connected to the rodless chambers corresponding to the two suspension cylinders; and The valve assembly (23), located in the oil line between the hydraulic pump and the two suspension cylinders, is configured to change the displacement of the piston rod according to the operating conditions to adjust the relative position of the vehicle frame and axle, and / or change the pressure in the rod chamber to adjust the stiffness of the vehicle's hydropneumatic suspension system.

2. The vehicle hydropneumatic suspension system according to claim 1, characterized in that, It also includes an oil tank, which includes an oil return port (T), and the valve assembly (23) includes: The first switching valve (17) has an oil inlet connected to the oil supply port (P) of the hydraulic pump, and an oil outlet connected to the two rod chambers. The second switching valve (7) has an oil inlet connected to the oil supply port (P) and an oil outlet connected to the two rodless chambers. The third switching valve (18) has its inlet connected to both rod chambers and its outlet connected to the return port (T); and The fourth switching valve (5) has an oil inlet that is connected to the two rodless chambers and an oil outlet that is connected to the return port (T).

3. The vehicle hydropneumatic suspension system according to claim 2, characterized in that, The hydraulic pump includes a load-sensitive pump, and the valve assembly (23) further includes: The shuttle valve (20) includes a first hydraulic inlet, a second hydraulic inlet, and a hydraulic outlet. The first hydraulic inlet is connected to the oil supply line between the oil supply port (P) and the first switching valve (17), and the second hydraulic inlet is connected to the oil supply line between the oil supply port (P) and the second switching valve (7). The directional valve (22) has a first oil port, a second oil port and a third oil port. The first oil port is connected to the hydraulic outlet, the second oil port is connected to the return oil port (T), and the third oil port is connected to the load-sensitive port (Ls) of the load-sensitive pump. The directional valve (22) has a first working position and a second working position. In the first working position, the first oil port is connected to the third oil port, and in the second working position, the first oil port is connected to the second oil port.

4. The vehicle hydropneumatic suspension system according to claim 1, characterized in that, It also includes a displacement sensor (25) located in the suspension cylinder or an angle sensor located on the frame, the displacement sensor (25) and the angle sensor being configured to detect the stroke of the piston rod.

5. The vehicle hydropneumatic suspension system according to claim 1, characterized in that, It also includes the pressure sensor (24), which is configured to detect the pressure within the rod cavity.

6. The vehicle hydropneumatic suspension system according to claim 1, characterized in that, The vehicle's hydropneumatic suspension system has a manual lifting mode. In the manual lifting mode, the suspension cylinder is in a rising state, which sequentially includes a first stroke stage and a second stroke stage. The valve assembly (23) is configured to, during the first stroke phase, simultaneously supply hydraulic oil to the rod chamber and the rodless chamber to allow the piston rod to extend at a uniform speed; and during the second stroke phase, supply hydraulic oil to the rodless chamber and lock the rod chamber to allow the piston rod to extend at a reduced speed until it reaches the first limit stroke; and / or In the manual lifting mode, the suspension cylinder is in a lowered state. The descent state includes a third stroke stage and a fourth stroke stage in sequence. The valve group (23) is configured to allow hydraulic oil to flow into the rod chamber and return oil to the rodless chamber during the third stroke stage, so that the piston rod retracts at a constant speed. During the fourth stroke stage, hydraulic oil is allowed to flow into the rod chamber and the rodless chamber is locked, so that the piston rod decelerates and retracts until it reaches the second limit stroke.

7. The vehicle hydropneumatic suspension system according to claim 6, characterized in that, The vehicle's hydropneumatic suspension system has a maximum stiffness mode. In the maximum stiffness mode, the valve assembly (23) is configured to allow hydraulic oil to flow into the rod chamber only until the first preset pressure is reached when the vehicle speed reaches the first preset speed and the travel distance reaches the preset distance. When the vehicle speed exceeds the second preset speed, the rod chamber is returned to oil until the second preset pressure is reached; when the vehicle speed decreases to the third preset speed, the rod chamber is circulated with hydraulic oil until it returns to the first preset pressure. Wherein, the second preset pressure is less than the first preset pressure, and the third preset speed is between the first preset speed and the second preset speed.

8. The vehicle hydropneumatic suspension system according to claim 1, characterized in that, The vehicle hydropneumatic suspension system has an automatic mode in which the valve group (23) is configured to adjust the piston rod to the middle position of its stroke as an initial position by uniformly raising and lowering it, and based on the initial position, adjust the pressure in the rod chamber according to at least one of vehicle speed, road conditions and vehicle engine speed to change the stiffness of the vehicle hydropneumatic suspension system.

9. The vehicle hydropneumatic suspension system according to any one of claims 1-8, characterized in that, The vehicle hydropneumatic suspension system includes two second accumulators (10), which are respectively connected to the rodless chambers corresponding to the two suspension cylinders.

10. An agricultural machine, characterized in that, Includes the vehicle hydropneumatic suspension system as described in any one of claims 1-9.

11. The agricultural machinery according to claim 10, characterized in that, Also includes: The first detection device is configured to detect the travel speed of the agricultural machinery; The second detection device is configured to detect engine speed; The third detection device is configured to detect the travel distance of the agricultural machinery; and The controller (6) is configured to control the working state of the valve group (23) based on the detection results of at least one of the first detection device, the second detection device, and the third detection device.

12. A control method for a vehicle hydropneumatic suspension system according to claims 1-9, characterized in that, include: Obtain the vehicle's operating conditions; The working state of the valve group (23) is controlled according to the operating conditions.

13. The control method according to claim 12, characterized in that, Obtaining the vehicle's operating conditions also includes: The operating modes of the vehicle's hydropneumatic suspension system are obtained, including manual lifting mode, automatic mode, and maximum stiffness mode. In the maximum stiffness mode, the vehicle speed and travel distance are obtained; In the automatic mode, the vehicle speed, the piston rod stroke, and the engine speed are acquired.

14. The control method according to claim 13, characterized in that, In the manual lifting mode, controlling the working state of the valve group (23) according to the operating conditions includes: Control the suspension cylinder to be in the raised state; The suspension cylinder is controlled to be in a lowering state.

15. The control method according to claim 14, characterized in that, The ascending state sequentially includes a first stroke stage and a second stroke stage, and the descending state sequentially includes a third stroke stage and a fourth stroke stage. In the manual lifting mode, controlling the suspension cylinder to be in the lifting state includes: During the first stroke phase, hydraulic oil is simultaneously supplied to both the rod chamber and the rodless chamber to allow the piston rod to extend at a uniform speed; and / or During the second stroke phase, hydraulic oil is introduced into the rodless chamber and the rod chamber is locked, so that the piston rod decelerates and extends until it reaches the first limit stroke. In the manual lifting mode, controlling the suspension cylinder to be in a lowering state includes: In the third stroke phase, hydraulic oil is introduced into the rod chamber and oil is returned to the rodless chamber, so that the piston rod retracts at a uniform speed; and / or In the fourth stroke stage, hydraulic oil is introduced into the rod chamber, and the rodless chamber is locked, so that the piston rod decelerates and retracts until it reaches the second limit stroke.

16. The control method according to claim 13, characterized in that, In the maximum stiffness mode, controlling the operating state of the valve assembly (23) according to the operating conditions includes: When the vehicle speed reaches the first preset speed and the travel distance reaches the preset distance, hydraulic oil is only introduced into the rod chamber until the first preset pressure is reached; If the vehicle speed exceeds the second preset speed, the rod chamber is returned to oil until the second preset pressure is reached; When the vehicle speed decreases to the third preset speed, hydraulic oil is introduced into the rod chamber until it returns to the first preset pressure.

17. The control method according to claim 13, characterized in that, In the automatic mode, controlling the operating state of the valve assembly (23) according to the operating conditions includes: The piston rod is adjusted to the middle position of its stroke by a constant speed of lifting and lowering, which serves as the initial position. Based on the initial position, the pressure in the rod chamber is adjusted according to at least one of vehicle speed, road conditions, and vehicle engine speed to change the stiffness of the vehicle's hydropneumatic suspension system.

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