A frame self-adaptive leveling system

Abstract

The application provides a vehicle frame self-adaptive leveling system, which comprises left front, right front, left rear and right rear hydraulic cylinder control circuits; in each hydraulic cylinder control circuit: the oil outlet of a one-way valve connected at the oil discharge port of a variable pump is connected with the P port of a proportional reversing valve, the A port of a switching valve and an accumulator respectively, the B port of the switching valve is connected with the A port of the proportional reversing valve, the P port of the switching valve and the B port of the proportional reversing valve are connected with the rodless cavity and the rod cavity oil port of a hydraulic cylinder respectively, the rod cavity of the hydraulic cylinder is connected with an oil tank through an oil supplementing one-way valve; a pressure sensor is connected on the accumulator, a displacement sensor is connected on the piston rod of the hydraulic cylinder, and a load is connected on the end of the piston rod of the hydraulic cylinder; the loads on the two hydraulic cylinders of the front part and the rear part are connected through connecting buckles; a pitch direction inclination sensor and a roll direction inclination sensor are respectively installed on the frame of the agricultural machine. The system has good terrain adaptability, excellent climbing performance and is beneficial to improving the versatility of the agricultural machine.

Description

Technical Field

[0001] This invention belongs to the field of agricultural machinery technology, specifically relating to a vehicle frame adaptive leveling system. Background Technology

[0002] my country has a large hilly and mountainous area, characterized by rugged and uneven terrain, relatively scattered and small arable land, and steep slopes. This leads to a weak foundation in agricultural machinery operation skills, limiting the operation, transfer, and transportation of agricultural machinery. Furthermore, large and medium-sized agricultural machinery is unsuitable for agricultural cultivation in hilly and mountainous areas, resulting in a very low rate of mechanized crop planting and harvesting, severely hindering the economic development of these regions. In particular, the inability of traditional vehicle frames to withstand steep slopes and undulating terrain is a significant factor restricting economic development in these areas.

[0003] Most existing agricultural machinery can only be used and operated on flat land or large areas of gentle terrain, which has certain limitations. It suffers from poor slope mobility, poor terrain adaptability, low climbing performance, and poor operational stability, making it unsuitable for operation in sloping areas. Therefore, traditional agricultural machinery is not suitable for use in hilly areas. Thus, there is an urgent need for a system with leveling capabilities to enable agricultural machinery to be better suited for hilly and mountainous operations. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides a vehicle frame adaptive leveling system. This system has good terrain adaptability and excellent climbing performance, enabling it to enter hilly areas with a certain slope for agricultural operations. This is beneficial to improving the versatility of agricultural machinery and also helps to improve the mechanization level of agricultural cultivation in hilly areas.

[0005] To achieve the above objectives, the present invention provides a vehicle frame adaptive leveling system, which is installed in agricultural machinery and includes a variable pump, a motor, a left front hydraulic cylinder control circuit, a right front hydraulic cylinder control circuit, a left rear hydraulic cylinder control circuit, a right rear hydraulic cylinder control circuit, a pitch angle sensor, and a roll angle sensor.

[0006] The motor is coaxially connected to the variable pump; the control circuit of the left front hydraulic cylinder consists of a check valve, a proportional directional valve, a switching valve, an accumulator, a left front position hydraulic cylinder, a replenishing check valve, a pressure sensor, a displacement sensor, and a load; the inlet of the check valve is connected to the outlet of the variable pump, and its outlet is connected to the P port of the proportional directional valve, the A port of the switching valve, and the accumulator, respectively; the T port of the proportional directional valve is connected to the oil tank, and its B port is connected to the rod chamber port of the left front position hydraulic cylinder; the switching valve... The B port of valve one is connected to the A port of proportional directional valve one, and its P port is connected to the rodless chamber port of the left front position hydraulic cylinder; the inlet of the replenishing check valve one is connected to the oil tank, and its outlet is connected to the rod chamber port of the left front position hydraulic cylinder; the pressure sensor one is connected to accumulator one to collect the pressure signal inside accumulator one in real time; the displacement sensor one is connected to the piston rod of the left front position hydraulic cylinder to collect the displacement signal of the piston rod of the left front position hydraulic cylinder in real time; the load one is connected to the piston rod end of the left front position hydraulic cylinder.

[0007] The right front hydraulic cylinder control circuit consists of a second check valve, a second proportional directional valve, a second switching valve, a second accumulator, a right front position hydraulic cylinder, a second replenishing check valve, a second pressure sensor, a second displacement sensor, and a second load. The inlet of the second check valve is connected to the outlet of the variable displacement pump, and its outlet is connected to the P port of the second proportional directional valve, the A port of the second switching valve, and the second accumulator. The T port of the second proportional directional valve is connected to the oil tank, and its B port is connected to the rod-side port of the right front position hydraulic cylinder. The B port of the second switching valve is connected to the... For example, the A port of the directional valve two is connected, and its P port is connected to the rodless chamber port of the right front position hydraulic cylinder; the inlet of the replenishing check valve two is connected to the oil tank, and its outlet is connected to the rod chamber port of the right front position hydraulic cylinder; the pressure sensor two is connected to the accumulator two to collect the pressure signal inside the accumulator two in real time; the displacement sensor two is connected to the piston rod of the right front position hydraulic cylinder to collect the displacement signal of the piston rod of the right front position hydraulic cylinder in real time; the load two is connected to the piston rod end of the right front position hydraulic cylinder.

[0008] The control circuit for the left rear hydraulic cylinder consists of a third check valve, a third proportional directional valve, a third switching valve, a third accumulator, a third left rear position hydraulic cylinder, a third replenishing check valve, a third pressure sensor, a third displacement sensor, and a third load. The inlet of the third check valve is connected to the outlet of the variable displacement pump, and its outlet is connected to the P port of the third proportional directional valve, the A port of the third switching valve, and the third accumulator. The T port of the third proportional directional valve is connected to the oil tank, and its B port is connected to the rod-side port of the left rear position hydraulic cylinder. The B port of the third switching valve is connected to the proportional directional valve. For example, the A port of the directional valve three is connected, and its P port is connected to the rodless chamber port of the left rear position hydraulic cylinder; the inlet of the replenishing check valve three is connected to the oil tank, and its outlet is connected to the rod chamber port of the left rear position hydraulic cylinder; the pressure sensor three is connected to the accumulator three to collect the pressure signal inside the accumulator three in real time; the displacement sensor three is connected to the piston rod of the left rear position hydraulic cylinder to collect the displacement signal of the piston rod of the left rear position hydraulic cylinder in real time; the load three is connected to the piston rod end of the left rear position hydraulic cylinder.

[0009] The right rear hydraulic cylinder control circuit consists of a four-way check valve, a four-way proportional directional valve, a four-way switching valve, a four-way accumulator, a right rear position hydraulic cylinder, a four-way replenishing check valve, a four-way pressure sensor, a four-way displacement sensor, and a four-way load. The inlet of the four-way check valve is connected to the outlet of the variable displacement pump, and its outlet is connected to the P port of the four-way proportional directional valve, the A port of the four-way switching valve, and the four-way accumulator. The T port of the four-way proportional directional valve is connected to the oil tank, and its B port is connected to the rod-side port of the right rear position hydraulic cylinder. The B port of the four-way switching valve is connected to the proportional directional valve. For example, the A port of the reversing valve four is connected, and its P port is connected to the rodless chamber port of the right rear position hydraulic cylinder; the inlet of the replenishing check valve four is connected to the oil tank, and its outlet is connected to the rod chamber port of the right rear position hydraulic cylinder; the pressure sensor four is connected to the accumulator four to collect the pressure signal inside the accumulator four in real time; the displacement sensor four is connected to the piston rod of the right rear position hydraulic cylinder to collect the displacement signal of the piston rod of the right rear position hydraulic cylinder in real time; the load four is connected to the piston rod end of the right rear position hydraulic cylinder.

[0010] Load 1 and load 2 are connected by connecting clip 1; load 3 and load 4 are connected by connecting clip 2;

[0011] The pitch angle sensor is mounted on the frame of the agricultural machinery and is used to collect pitch angle signals in the pitch direction in real time.

[0012] The tilt angle sensor is installed on the frame of the agricultural machinery to collect the tilt angle signal in the tilt direction in real time.

[0013] The controller is connected to pressure sensor 1, pressure sensor 2, pressure sensor 3, pressure sensor 4, displacement sensor 1, displacement sensor 2, displacement sensor 3, displacement sensor 4, connecting buckle 1, connecting buckle 2, pitch angle sensor, and roll angle sensor, respectively.

[0014] Furthermore, to prevent impurities in the oil tank from entering the variable pump and damaging it, and to facilitate setting the safety pressure of the leveling system, a filter and a safety valve are also included. The filter is connected in series in the oil line between the oil inlet of the variable pump and the oil tank; the oil outlet of the variable pump is also connected to the oil tank through the safety valve.

[0015] Furthermore, to facilitate automated unloading of the oil circuit where the variable pump's discharge port is located, the system also includes relief valve one, relief valve two, relief valve three, and relief valve four. The inlet of check valve one is connected to the oil tank via relief valve one, and the hydraulic control port of relief valve one is connected to the outlet of check valve one. The inlet of check valve two is connected to the oil tank via relief valve two, and the hydraulic control port of relief valve two is connected to the outlet of check valve two. The inlet of check valve three is connected to the oil tank via relief valve three, and the hydraulic control port of relief valve three is connected to the outlet of check valve three. The inlet of check valve four is connected to the oil tank via relief valve four, and the hydraulic control port of relief valve four is connected to the outlet of check valve four.

[0016] Furthermore, in order to effectively improve the service life of hydraulic components, a filter circuit is also included; the filter circuit consists of a filter pump, a second filter, a spring-loaded check valve, and a fine filter. The oil inlet of the filter pump is connected to the oil tank through the second filter, and its oil outlet is connected to the oil inlet of the spring-loaded check valve and the oil inlet of the fine filter, respectively. The oil outlet of the spring-loaded check valve and the oil outlet of the fine filter are both connected to the oil tank.

[0017] As a preferred embodiment, the proportional directional valve one, proportional directional valve two, proportional directional valve three, and proportional directional valve four are all three-position four-way valves. When they are energized and operating in the left position, the oil circuit between their P port and A port is connected, and the oil circuit between their T port and B port is connected. When they are de-energized and operating in the middle position, their A port, B port, P port, and T port are each cut off and not connected to each other. When they are energized and operating in the right position, the oil circuit between their P port and B port is connected, and the oil circuit between their T port and A port is connected.

[0018] As a preferred embodiment, the switching valves 1, 2, 3 and 4 are all two-position three-way directional valves. When they are energized and operating in the left position, the oil circuit between their P port and A port is connected, and their B port is closed. When they are de-energized and operating in the middle position, their A port is closed, and the oil circuit between their P port and B port is connected.

[0019] As a preferred embodiment, the controller is a PLC controller.

[0020] In this invention, an accumulator is installed in each hydraulic cylinder control circuit. This not only allows for energy recovery when the piston rod retracts under load, but also enables the stored energy in the accumulator to work together with the oil discharged from the variable pump to the rodless chamber of the hydraulic cylinder when the piston rod extends outward. This effectively increases the extension speed of the piston rod, facilitating rapid leveling operations. The accumulator is connected to both port A of the switching valve and port P of the proportional directional valve. Simultaneously, port B of the switching valve is connected to port A of the proportional directional valve, and ports P and B of the switching valve are connected to the rodless and rod chambers of the hydraulic cylinder, respectively. This ensures that the oil discharged from the variable pump enters both chambers and allows for recharging of the accumulator when its energy is insufficient, utilizing the return oil from the rodless chamber. This facilitates energy recovery and reuse of the collected energy. By connecting a pressure sensor to the accumulator, the pressure signal of the accumulator can be easily collected in real time. The controller can then obtain the pressure value of the accumulator in real time based on the pressure signal and further determine the energy status of the accumulator. Similarly, by connecting a displacement sensor to the hydraulic cylinder, the displacement signal of the hydraulic cylinder piston rod can be easily collected in real time. The controller can then obtain the displacement value of the hydraulic cylinder piston rod in real time based on the displacement signal, facilitating closed-loop control of the hydraulic cylinder's movement and improving control accuracy. Furthermore, when encountering situations requiring the overall height of the machine to be raised or lowered, the controller can independently control each control loop based on the data from the displacement sensors. This allows the four hydraulic cylinders in their independent states to extend to or retract to the same position, facilitating the raising or lowering of the overall machine height. When the overall machine height is raised, the overall passability is significantly enhanced, significantly improving the agricultural machinery's ability to travel on continuously undulating roads. Connecting the rodless chamber of the hydraulic cylinder to the oil tank via a replenishing check valve allows for connection in the neutral position of the proportional directional valve. When using the accumulator to recover energy from the hydraulic cylinder under load, the phenomenon of cavitation in the rod chamber of the hydraulic cylinder is avoided. Load 1 and Load 2 are connected to the left front and right front hydraulic cylinders respectively. Load 1 and Load 2 are connected by a connecting clip 1. The locking state of the connecting clip can be used to synchronize the operation of the two front hydraulic cylinders as needed. Load 3 and Load 4 are connected to the left rear and right rear hydraulic cylinders respectively. Load 3 and Load 4 are connected by a connecting clip 2. The locking state of the connecting clip 2 can be used to synchronize the operation of the two rear hydraulic cylinders as needed. Alternatively, the four hydraulic cylinders can be operated independently by opening the connecting clips. This allows the leveling system to flexibly perform leveling actions according to different working conditions during the leveling process, improving the system's intelligence.Installing a pitch angle sensor on the frame of agricultural machinery allows for real-time acquisition of pitch angle signals in the pitch direction. The controller can then obtain the frame's pitch angle data based on these signals. Similarly, installing a roll angle sensor on the frame allows for real-time acquisition of roll angle signals in the roll direction. The controller can then obtain the frame's roll angle data based on these signals. This enables the controller to determine the overall tilt status of the machine and control the hydraulic cylinders at different positions based on the tilt status, thereby achieving rapid leveling of the entire machine.

[0021] This leveling system has a simple structure and high reliability. It has good terrain adaptability and climbing ability, and can be effectively used in agricultural production in hilly areas. It has good adaptability to work areas with uneven roads or steep slopes, and can avoid the occurrence of uncoordinated four wheels of agricultural machinery or even rollover caused by uneven roads or steep slopes. Attached Figure Description

[0022] Figure 1 This is a hydraulic schematic diagram of the adaptive leveling system in this invention;

[0023] Figure 2 This is the circuit control schematic diagram of the present invention.

[0024] In the diagram: 1. Variable displacement pump, 2. Filter 1, 3. Relief valve 1, 4. Check valve 1, 5. Proportional directional valve 1, 6. Replenishment check valve 1, 7. Connecting clip 1, 8. Displacement sensor 1, 9. Load 1, 10. Left front position hydraulic cylinder, 11. Tangential valve 1, 12. Accumulator 1, 13. Pressure sensor 1, 14. Relief valve 2, 15. Check valve 2, 16. Proportional directional valve 2, 17. Replenishment check valve 2, 18. Displacement sensor 2, 19. Load 2, 20. Right front position hydraulic cylinder, 21. Tangential valve 2, 22. Accumulator 2, 23. Pressure sensor 2, 24. Relief valve 3, 25. Check valve 3, 26. 27. Proportional directional valve 3, 28. Replenishing check valve 3, 29. Connecting clip 2, 30. Displacement sensor 3, 31. Load 3, 32. Left rear position hydraulic cylinder, 33. Switching valve 3, 34. Accumulator 3, 35. Pressure sensor 3, 36. Relief valve 4, 37. Check valve 4, 38. Proportional directional valve 4, 39. Replenishing check valve 4, 40. Displacement sensor 4, 41. Load 4, 42. Right rear position hydraulic cylinder, 43. Switching valve 4, 44. Accumulator 4, 45. Pressure sensor 4, 46. Filter 2, 47. Filter pump, 48. Spring-loaded check valve, 49. Fine filter, 50. Safety valve, 51. Oil tank. Detailed Implementation

[0025] The present invention will be further described below.

[0026] like Figure 1 and Figure 2 As shown, the present invention provides a vehicle frame adaptive leveling system, which is installed in agricultural machinery and includes a variable pump 1, a motor, a left front hydraulic cylinder control circuit, a right front hydraulic cylinder control circuit, a left rear hydraulic cylinder control circuit, a right rear hydraulic cylinder control circuit, a pitch angle sensor and a roll angle sensor.

[0027] The motor is coaxially connected to the variable pump 1;

[0028] The control circuit for the left front hydraulic cylinder consists of a check valve 4, a proportional directional valve 5, a switching valve 11, an accumulator 12, a left front position hydraulic cylinder 10, a replenishing check valve 51, a pressure sensor 13, a displacement sensor 8, and a load 9. The inlet of the check valve 4 is connected to the outlet of the variable pump 1, and its outlet is connected to the P port of the proportional directional valve 5, the A port of the switching valve 11, and the accumulator 12, respectively. The T port of the proportional directional valve 5 is connected to the oil tank 50, and its B port is connected to the rod-side port of the left front position hydraulic cylinder 10. The B port of the switching valve 11... The port is connected to port A of the proportional directional valve 5, and its port P is connected to the rodless chamber port of the left front position hydraulic cylinder 10; the inlet of the replenishing check valve 51 is connected to the oil tank 50, and its outlet is connected to the rodless chamber port of the left front position hydraulic cylinder 10; the pressure sensor 13 is connected to the accumulator 12 to collect the pressure signal inside the accumulator 12 in real time; the displacement sensor 8 is connected to the piston rod of the left front position hydraulic cylinder 10 to collect the displacement signal of the piston rod of the left front position hydraulic cylinder 10 in real time; the load 9 is connected to the piston rod end of the left front position hydraulic cylinder 10.

[0029] The right front hydraulic cylinder control circuit consists of a second check valve 15, a second proportional directional valve 16, a second switching valve 21, a second accumulator 22, a right front position hydraulic cylinder 20, a second replenishing check valve 17, a second pressure sensor 23, a second displacement sensor 18, and a second load 19. The inlet of the second check valve 15 is connected to the outlet of the variable pump 1, and its outlet is connected to the P port of the second proportional directional valve 16, the A port of the second switching valve 21, and the second accumulator 22, respectively. The T port of the second proportional directional valve 16 is connected to the oil tank 50, and its B port is connected to the rod-side port of the right front position hydraulic cylinder 20. The second switching valve 21... Port B of the first valve is connected to port A of the proportional directional valve 16, and port P of the second valve is connected to the rodless chamber port of the right front position hydraulic cylinder 20; the inlet of the second oil replenishment check valve 17 is connected to the oil tank 50, and its outlet is connected to the rodless chamber port of the right front position hydraulic cylinder 20; the second pressure sensor 23 is connected to the second accumulator 22 to collect the pressure signal inside the second accumulator 22 in real time; the second displacement sensor 18 is connected to the piston rod of the right front position hydraulic cylinder 20 to collect the displacement signal of the piston rod of the right front position hydraulic cylinder 20 in real time; the second load 19 is connected to the piston rod end of the right front position hydraulic cylinder 20.

[0030] The control circuit for the left rear hydraulic cylinder consists of a check valve 25, a proportional directional valve 26, a switching valve 32, an accumulator 33, a left rear position hydraulic cylinder 31, a replenishing check valve 27, a pressure sensor 34, a displacement sensor 39, and a load 30. The inlet of the check valve 25 is connected to the outlet of the variable pump 1, and its outlet is connected to the P port of the proportional directional valve 26, the A port of the switching valve 32, and the accumulator 33. The T port of the proportional directional valve 26 is connected to the oil tank 50, and its B port is connected to the rod-side port of the left rear position hydraulic cylinder 31. The switching valve 32... Port B of the valve is connected to port A of the proportional directional valve 26, and port P of the valve is connected to the rodless chamber port of the left rear position hydraulic cylinder 31; the inlet of the replenishing check valve 27 is connected to the oil tank 50, and its outlet is connected to the rodless chamber port of the left rear position hydraulic cylinder 31; the pressure sensor 34 is connected to the accumulator 33 to collect the pressure signal inside the accumulator 33 in real time; the displacement sensor 29 is connected to the piston rod of the left rear position hydraulic cylinder 31 to collect the displacement signal of the piston rod of the left rear position hydraulic cylinder 31 in real time; the load 30 is connected to the piston rod end of the left rear position hydraulic cylinder 31.

[0031] The right rear hydraulic cylinder control circuit consists of a check valve 36, a proportional directional valve 37, a switching valve 42, an accumulator 43, a right rear position hydraulic cylinder 41, a replenishing check valve 38, a pressure sensor 44, a displacement sensor 49, and a load 40. The inlet of the check valve 36 is connected to the outlet of the variable pump 1, and its outlet is connected to the P port of the proportional directional valve 37, the A port of the switching valve 42, and the accumulator 43. The T port of the proportional directional valve 37 is connected to the oil tank 50, and its B port is connected to the rod-side port of the right rear position hydraulic cylinder 41. The switching valve 42... Port B of the valve is connected to port A of the proportional directional valve 37, and port P of the valve is connected to the rodless chamber port of the right rear position hydraulic cylinder 41; the inlet of the replenishing check valve 38 is connected to the oil tank 50, and its outlet is connected to the rodless chamber port of the right rear position hydraulic cylinder 41; the pressure sensor 44 is connected to the accumulator 43 to collect the pressure signal inside the accumulator 43 in real time; the displacement sensor 39 is connected to the piston rod of the right rear position hydraulic cylinder 41 to collect the displacement signal of the piston rod of the right rear position hydraulic cylinder 41 in real time; the load 40 is connected to the piston rod end of the right rear position hydraulic cylinder 41.

[0032] Load 19 and load 219 are connected by connecting buckle 17; load 30 and load 40 are connected by connecting buckle 28; both connecting buckle 17 and connecting buckle 28 have electric control locking and disconnecting functions. In the locked state, the two loads connected to them are rigidly connected. In the disconnected state, the two loads connected to them move independently.

[0033] The pitch angle sensor is mounted on the frame of the agricultural machinery and is used to collect pitch angle signals in the pitch direction in real time.

[0034] The tilt angle sensor is installed on the frame of the agricultural machinery to collect the tilt angle signal in the tilt direction in real time.

[0035] The controller is connected to pressure sensor 13, pressure sensor 23, pressure sensor 34, pressure sensor 44, displacement sensor 18, displacement sensor 28, displacement sensor 39, displacement sensor 49, connecting buckle 17, connecting buckle 28, pitch angle sensor and roll angle sensor respectively.

[0036] As a preferred embodiment, the controller is also connected to the variable pump 1, and the controller can adjust the displacement of the variable pump 1 when it is necessary to adjust the response speed of the hydraulic cylinder.

[0037] To prevent impurities in the oil tank from entering the variable pump and damaging it, and to facilitate setting the safety pressure of the leveling system, a filter 2 and a safety valve 49 are also included. The filter 2 is connected in series in the oil line between the oil inlet of the variable pump 1 and the oil tank 50; the oil outlet of the variable pump 1 is also connected to the oil tank 50 through the safety valve 49. The safety valve 49 is used to set the safety pressure of the leveling system. When the operating pressure of the variable pump 1 exceeds the set safety pressure, the safety valve 49 automatically opens to relieve the load.

[0038] To facilitate automated unloading of the oil circuit where the variable pump's discharge port is located, the system also includes relief valve 3, relief valve 14, relief valve 24, and relief valve 35. The inlet of check valve 4 is connected to the oil tank 50 via relief valve 3, and the hydraulic control port of relief valve 3 is connected to the outlet of check valve 4. The inlet of check valve 215 is connected to the oil tank 50 via relief valve 214, and the hydraulic control port of relief valve 214 is connected to the outlet of check valve 215. The inlet of check valve 325 is connected to the oil tank 50 via relief valve 324, and the hydraulic control port of relief valve 324 is connected to the outlet of check valve 325. The inlet of check valve 34 is connected to the oil tank 50 via relief valve 35, and the hydraulic control port of relief valve 35 is connected to the outlet of check valve 34.

[0039] To effectively improve the service life of hydraulic components, a filtration circuit is also included. This filtration circuit consists of a filter pump 46, a second filter 45, a spring-loaded check valve 47, and a fine filter 48. The suction port of the filter pump 46 is connected to the oil tank 50 via the second filter 45, and its discharge port is connected to the inlet of the spring-loaded check valve 47 and the inlet of the fine filter 48, respectively. Both the outlet of the spring-loaded check valve 47 and the outlet of the fine filter 48 are connected to the oil tank 50. Since the variable pump 1 and the proportional directional valve are extremely sensitive to the quality of the hydraulic fluid, a filtration circuit is specifically designed to effectively improve the service life of these components. Preferably, the filter pump 46 is a large-displacement fixed-displacement pump, which draws oil from the hydraulic oil tank 50 via the second filter 45. The output oil from the filter pump 46 flows back to the oil tank 50 after passing through the fine filter 48. When the fine filter 48 becomes clogged, its flow resistance increases, and the output oil from the filter pump 46 flows back to the oil tank 50 via the spring-loaded check valve 47. The fine filter 48 is equipped with a life indicator, which can remind the user to replace it in time.

[0040] As a preferred embodiment, the proportional directional valve 1 (5), proportional directional valve 2 (16), proportional directional valve 3 (26), and proportional directional valve 4 (37) are all three-position four-way valves. When they are energized and operating in the left position, the oil circuit between their P port and A port is connected, and the oil circuit between their T port and B port is connected. When they are de-energized and operating in the middle position, their A port, B port, P port, and T port are each cut off and not connected to each other. When they are energized and operating in the right position, the oil circuit between their P port and B port is connected, and the oil circuit between their T port and A port is connected.

[0041] As a preferred embodiment, the switching valve 11, switching valve 21, switching valve 32 and switching valve 42 are all two-position three-way directional valves. When they are energized and operating in the left position, the oil circuit between their P port and A port is connected and their B port is closed. When they are de-energized and operating in the middle position, their A port is closed and the oil circuit between their P port and B port is connected.

[0042] As a preferred embodiment, the controller is a PLC controller.

[0043] As a preferred embodiment, it also includes a control handle connected to the controller, the control handle being used to send control signals to the controller according to the operator's control;

[0044] How the leveling mode works:

[0045] The vehicle's pitch angle is collected in real time by a pitch angle sensor and sent to the controller. The vehicle's roll angle is collected in real time by a roll angle sensor and sent to the controller. The controller obtains the pitch angle and roll angle values ​​based on the received pitch angle and roll angle signals. The controller judges the vehicle's travel condition based on the pitch angle and roll angle values. When the controller judges that the vehicle is traveling uphill or downhill, the controller puts the adaptive leveling system in pitch leveling mode. When the controller judges that the vehicle is traveling on a continuously undulating road surface, the controller puts the adaptive leveling system in full-state leveling mode.

[0046] The pitch-leveling mode refers to the leveling operation achieved by simultaneously extending or retracting the two front or rear hydraulic cylinders when the machine is going uphill or downhill and the front and rear heights are inconsistent. The full-state leveling mode refers to the leveling operation achieved by independently operating the four hydraulic cylinders on continuously undulating surfaces, using a pre-defined control strategy.

[0047] 1. In the pitch leveling mode, the controller locks both the first connecting clip 7 and the second connecting clip 28. That is, the first load 9 and the second load 19 are rigidly connected by mechanical means, and the third load 30 and the fourth load 40 are rigidly connected by mechanical means. In this way, it can be ensured that the left front position hydraulic cylinder 10 and the right front position hydraulic cylinder 20 move synchronously, and that the left rear position hydraulic cylinder 31 and the right rear position hydraulic cylinder 41 move synchronously.

[0048] When the controller determines that the machine is going uphill based on the pitch and roll angle sensors, it controls the motor to operate. Simultaneously, it energizes proportional directional valve 5 to operate in the right position and controls switching valve 11 to be energized or de-energized based on the energy level of accumulator 12. The controller also energizes proportional directional valve 16 to operate in the right position and controls switching valve 21 to be energized or de-energized based on the energy level of accumulator 22. Furthermore, it energizes proportional directional valve 26 to operate in the left position and de-energizes switching valve 32 to operate in the right position. Finally, it energizes proportional directional valve 37 to operate in the left position and de-energizes switching valve 42 to operate in the right position, allowing the high-pressure oil discharged from variable pump 1 to flow... The hydraulic fluid enters the rod chamber of the left front position hydraulic cylinder 10 through the proportional directional valve 15, and simultaneously enters the rod chamber of the right front position hydraulic cylinder 20 through the proportional directional valve 26, causing the left front position hydraulic cylinder 10 and the right front position hydraulic cylinder 20 to retract synchronously. This allows the high-pressure oil discharged from the variable pump 1 to enter the rodless chamber of the left rear position hydraulic cylinder 31 through the proportional directional valve 36 and the switching valve 32, and simultaneously enters the rodless chamber of the right rear position hydraulic cylinder 41 through the proportional directional valve 47 and the switching valve 42, causing the left rear position hydraulic cylinder 31 and the right rear position hydraulic cylinder 41 to extend synchronously until the controller determines that the entire machine has reached a level state based on the pitch angle and roll angle values, thus achieving adaptive leveling of the frame.

[0049] When the controller determines that the machine is descending a slope based on the pitch and roll angle sensors, it activates the motor. Simultaneously, it energizes proportional directional valve 5 (left position), de-energizes switching valve 11 (right position), energizes proportional directional valve 21 (left position), de-energizes switching valve 21 (right position), energizes proportional directional valve 326 (right position), and de-energizes switching valve 322 based on the energy level of accumulator 33. It also energizes proportional directional valve 47 (right position) and de-energizes switching valve 42 based on the energy level of accumulator 43, thus allowing the high-pressure oil discharged by variable pump 1 to pass through the proportional directional valve... For example, directional valve 5 and switching valve 11 enter the rodless chamber of the left front position hydraulic cylinder 10. At the same time, they enter the rodless chamber of the right front position hydraulic cylinder 20 through proportional directional valve 16 and switching valve 21, causing the left front position hydraulic cylinder 10 and the right front position hydraulic cylinder 20 to extend synchronously. This allows the high-pressure oil discharged by the variable pump 1 to enter the rod chamber of the left rear position hydraulic cylinder 31 through proportional directional valve 36. Simultaneously, it enters the rod chamber of the right rear position hydraulic cylinder 41 through proportional directional valve 47, causing the left rear position hydraulic cylinder 31 and the right rear position hydraulic cylinder 41 to retract synchronously. This continues until the controller determines that the entire machine has reached a level state based on the pitch angle and roll angle values, thus achieving adaptive leveling of the chassis.

[0050] II. In full-state leveling mode, the controller controls both connecting clip 7 and connecting clip 28 to disconnect. Simultaneously, the controller uses displacement sensor 8 to collect the displacement signal 1 of the left front hydraulic cylinder 10 in real time, and obtains the displacement value 1 of the piston rod of the left front hydraulic cylinder 10 based on displacement signal 1; the controller uses displacement sensor 2 18 to collect the displacement signal 2 of the right front hydraulic cylinder 20 in real time, and obtains the displacement value 2 of the piston rod of the right front hydraulic cylinder 20 based on displacement signal 2; the controller uses displacement sensor 3 29 to collect the displacement signal 3 of the left rear hydraulic cylinder 31 in real time, and obtains the displacement value 3 of the piston rod of the left rear hydraulic cylinder 31 based on displacement signal 3; the controller uses displacement sensor 4 39 to collect the displacement signal 4 of the right rear hydraulic cylinder 41 in real time, and obtains the displacement value 4 of the piston rod of the right rear hydraulic cylinder 41 based on displacement signal 4; the controller uses a pitch angle sensor to collect the pitch angle signal of the frame in the pitch direction in real time, and obtains the displacement value 4 of the piston rod of the right rear hydraulic cylinder 41 based on the pitch angle signal. The controller obtains the pitch angle value; it acquires the roll angle signal of the frame in the roll direction in real time through the roll angle sensor, obtains the roll angle value based on the roll angle signal, and judges the tilt state of the whole machine based on the pitch angle value and the roll angle value, determining the lowest and highest side of the whole machine position. It then controls the control circuit of the hydraulic cylinder near the lowest side of the frame position, causing the piston rod of that hydraulic cylinder to extend outward. Simultaneously, it controls the control circuit of the hydraulic cylinder near the highest side of the frame position, causing the piston rod of that hydraulic cylinder to retract inward. This relative extension and retraction adjustment brings the whole machine closer to a level position. When it can no longer approach a level position, it controls the control circuits of the other two hydraulic cylinders in the opposite directions, causing them to extend and retract until the frame is finally level. During this process, the displacement signal acquired in real time by the displacement sensor connected to the corresponding hydraulic cylinder is used to perform closed-loop control of the extension and retraction actions of the corresponding hydraulic cylinder. In this leveling process, the controller can also improve the position control accuracy through a fuzzy adaptive PID control algorithm.

[0051] In addition, the full-state leveling mode can also realize the automatic lifting function of the frame. Specifically, based on the feedback signal of the displacement sensor, the displacement of the piston rod of one hydraulic cylinder is used as a reference, and the control signals of the corresponding proportional reversing valves are adjusted under the control of the fuzzy adaptive PID control algorithm of the other three hydraulic cylinders, thereby realizing the synchronous action of the four hydraulic cylinders (the piston rod stroke is exactly the same). When the four hydraulic cylinders extend synchronously, the frame rises, and vice versa, the frame lowers, thereby adjusting the ground clearance of the whole machine.

[0052] In addition, the independent operation processes of the four hydraulic cylinders—left front position hydraulic cylinder 10, right front position hydraulic cylinder 20, left rear position hydraulic cylinder 31, and right rear position hydraulic cylinder 41—are as follows:

[0053] 1. The left front position hydraulic cylinder 10 is controlled via the left front hydraulic cylinder control circuit:

[0054] Pressure sensor 13 collects pressure signal 1 from accumulator 12 in real time and sends it to controller. The controller obtains pressure value 1 from accumulator 12 based on pressure signal 1 and compares pressure value 1 with lower limit pressure value A and upper limit pressure value A. When pressure value 1 is less than or equal to lower limit pressure value A, it is determined that accumulator 12 has insufficient energy. When pressure value 1 is greater than or equal to upper limit pressure value A, it is determined that accumulator 12 has sufficient energy.

[0055] When the left front position hydraulic cylinder 10 needs to extend, the controller energizes the proportional directional valve 5 to operate in the left position, de-energizes the switching valve 11 to operate in the right position, and controls the motor to operate. This causes the high-pressure oil discharged by the variable pump 1 to enter the rodless chamber of the left front position hydraulic cylinder 10 through the proportional directional valve 5 and the switching valve 11. Simultaneously, the oil in the rod chamber of the left front position hydraulic cylinder 10 flows back to the oil tank 50 through the proportional directional valve 5. During this process, when the accumulator 12 has sufficient energy, the high-pressure oil stored in the accumulator 12 and the high-pressure oil discharged by the variable pump 1 can simultaneously supply oil to the rodless chamber of the left front position hydraulic cylinder 10, thereby significantly increasing the movement speed of the left front position hydraulic cylinder 10.

[0056] When the left front position hydraulic cylinder 10 needs to retract, the controller first determines whether the energy of the accumulator 12 is sufficient. When the energy of the accumulator 12 is insufficient, the controller controls the proportional directional valve 5 to be energized and operate in the neutral position, controls the switching valve 11 to be energized and operate in the left position, and controls the motor to stop. The piston rod of the left front position hydraulic cylinder 10 retracts under the action of the load gravity. The oil in its rodless chamber charges the accumulator 12 through the switching valve 11. At the same time, its rod chamber is replenished with oil through the oil replenishment check valve 51 to prevent the phenomenon of cavitation. When the accumulator 12 has sufficient energy, the controller energizes the proportional directional valve 5 to operate in the right position, de-energizes the switching valve 11 to operate in the right position, and controls the motor to operate. This causes the high-pressure oil discharged by the variable pump 1 to enter the rod chamber of the left front position hydraulic cylinder 10 through the proportional directional valve 5. At the same time, the oil in the rodless chamber of the left front position hydraulic cylinder 10 flows back to the oil tank 50 through the switching valve 11 and the proportional directional valve 5.

[0057] When the left front position hydraulic cylinder 10 is not activated, the controller assesses the energy status of accumulator 12. If accumulator 12 is underpowered, the controller de-energizes proportional directional valve 5 to operate in the neutral position, de-energizes switching valve 11 to operate in the right position, and activates the motor. This causes the high-pressure oil discharged from variable pump 1 to open check valve 4 and supply oil to accumulator 12. When accumulator 12 is fully charged, the output oil pressure at the outlet of variable pump 1 rises sharply. The pressure at the hydraulic control port of relief valve 3 exceeds the spring force in its spring chamber, causing the internal oil circuit of relief valve 3 to open and unload. At this time, the displacement of variable pump 1 decreases, only used to maintain system leakage, with no excess flow loss.

[0058] 2. The right front position hydraulic cylinder 20 is controlled via the right front hydraulic cylinder control circuit:

[0059] Pressure signal 2 from accumulator 22 is collected in real time by pressure sensor 23 and sent to controller in real time. The controller obtains pressure value 2 from accumulator 22 based on pressure signal 2 and compares pressure value 2 with lower limit pressure value B and upper limit pressure value B. When pressure value 2 is less than or equal to lower limit pressure value B, it is determined that accumulator 22 has insufficient energy. When pressure value 2 is greater than or equal to upper limit pressure value B, it is determined that accumulator 22 has sufficient energy.

[0060] When the right front position hydraulic cylinder 20 needs to extend, the controller energizes the proportional directional valve 16 to operate in the left position, de-energizes the switching valve 21 to operate in the right position, and controls the motor to operate. This causes the high-pressure oil discharged by the variable pump 1 to enter the rodless chamber of the right front position hydraulic cylinder 20 through the proportional directional valve 16 and the switching valve 21. Simultaneously, the oil in the rod chamber of the right front position hydraulic cylinder 20 flows back to the oil tank 50 through the proportional directional valve 16. During this process, when the accumulator 22 has sufficient energy, the high-pressure oil stored in the accumulator 22 and the high-pressure oil discharged by the variable pump 1 can simultaneously supply oil to the rodless chamber of the right front position hydraulic cylinder 20, thereby significantly increasing the movement speed of the right front position hydraulic cylinder 20.

[0061] When the right front position hydraulic cylinder 20 needs to retract, the controller first determines whether the energy of the accumulator 22 is sufficient. When the energy of the accumulator 22 is insufficient, the controller controls the proportional directional valve 16 to be energized and operate in the neutral position, controls the switching valve 21 to be energized and operate in the left position, and controls the motor to stop. The piston rod of the right front position hydraulic cylinder 20 retracts under the action of the load gravity. The oil in its rodless chamber charges the accumulator 22 through the switching valve 21. At the same time, its rod chamber is replenished with oil through the oil replenishment check valve 17 to prevent the phenomenon of cavitation. When the energy of accumulator 22 is sufficient, the controller controls proportional directional valve 216 to be energized and operate in the right position, controls switching valve 21 to be de-energized and operate in the right position, and controls the motor to operate. This causes the high-pressure oil discharged by variable pump 1 to enter the rod chamber of hydraulic cylinder 20 in the right front position through proportional directional valve 216. At the same time, the oil in the rodless chamber of hydraulic cylinder 20 in the right front position flows back to oil tank 50 through switching valve 21 and proportional directional valve 216.

[0062] When the right front position hydraulic cylinder 20 is not activated, the controller assesses the energy status of accumulator 22. If accumulator 22 is underpowered, the controller de-energizes proportional directional valve 16 to operate in the neutral position, de-energizes switching valve 21 to operate in the right position, and activates the motor. This causes the high-pressure oil discharged from variable pump 1 to open check valve 15 and supply oil to accumulator 22. When accumulator 22 is fully charged, the output oil pressure at the outlet of variable pump 1 rises sharply. The pressure at the hydraulic control port of relief valve 14 exceeds the spring force in its spring chamber, causing the internal oil circuit of relief valve 14 to open and unload. At this time, the displacement of variable pump 1 decreases, only used to maintain internal system leakage, with no excess flow loss.

[0063] 3. The left rear position hydraulic cylinder 31 is controlled via the left rear hydraulic cylinder control circuit:

[0064] The pressure signal of the accumulator 33 is collected in real time by the pressure sensor 34 and sent to the controller in real time. The controller obtains the pressure value of the accumulator 33 based on the pressure signal and compares the pressure value with the lower limit pressure value C and the upper limit pressure value C. When the pressure value is less than or equal to the lower limit pressure value C, it is determined that the energy of the accumulator 33 is insufficient. When the pressure value is greater than or equal to the upper limit pressure value C, it is determined that the energy of the accumulator 33 is sufficient.

[0065] When the left rear position hydraulic cylinder 31 needs to extend, the controller energizes the proportional directional valve 26 to operate in the left position, de-energizes the switching valve 32 to operate in the right position, and controls the motor to operate. This causes the high-pressure oil discharged by the variable pump 1 to enter the rodless chamber of the left rear position hydraulic cylinder 31 through the proportional directional valve 26 and the switching valve 32. Simultaneously, the oil in the rod chamber of the left rear position hydraulic cylinder 31 flows back to the oil tank 50 through the proportional directional valve 26. During this process, when the accumulator 33 has sufficient energy, the high-pressure oil stored in the accumulator 33 and the high-pressure oil discharged by the variable pump 1 can simultaneously supply oil to the rodless chamber of the left rear position hydraulic cylinder 31, thereby significantly increasing the movement speed of the left rear position hydraulic cylinder 31.

[0066] When the left rear position hydraulic cylinder 31 needs to retract, the controller first determines whether the energy of the accumulator 33 is sufficient. When the energy of the accumulator 33 is insufficient, the controller controls the proportional directional valve 326 to be energized and operate in the neutral position, controls the switching valve 32 to be energized and operate in the left position, and controls the motor to stop. The piston rod of the left rear position hydraulic cylinder 31 retracts under the action of the load gravity. The oil in its rodless chamber charges the accumulator 33 through the switching valve 32. At the same time, its rod chamber is replenished with oil through the oil replenishment check valve 327 to prevent the phenomenon of cavitation. When the energy of accumulator 33 is sufficient, the controller controls the proportional directional valve 326 to be energized and operate in the right position, controls the switching valve 32 to be de-energized and operate in the right position, and controls the motor to operate. This causes the high-pressure oil discharged by variable pump 1 to enter the rod chamber of the left rear position hydraulic cylinder 31 through the proportional directional valve 326. At the same time, the oil in the rodless chamber of the left rear position hydraulic cylinder 31 flows back to the oil tank 50 through the switching valve 32 and the proportional directional valve 326.

[0067] When the left rear position hydraulic cylinder 31 is not activated, the controller assesses the energy status of accumulator 33. If accumulator 33 is underpowered, the controller de-energizes proportional directional valve 326 to operate in the neutral position, de-energizes switching valve 32 to operate in the right position, and activates the motor. This causes the high-pressure oil discharged from variable pump 1 to open check valve 325 and supply oil to accumulator 33. When accumulator 33 is fully charged, the output oil pressure at the outlet of variable pump 1 rises sharply. The pressure at the hydraulic control port of relief valve 324 exceeds the spring force in its spring chamber, causing the internal oil circuit of relief valve 324 to open and unload. At this time, the displacement of variable pump 1 decreases, only used to maintain internal system leakage, with no excess flow loss.

[0068] 4. The right rear position hydraulic cylinder 41 is controlled via the right rear hydraulic cylinder control circuit:

[0069] Pressure signal 4 from accumulator 43 is collected in real time by pressure sensor 44 and sent to controller in real time. The controller obtains the pressure value 4 of accumulator 43 based on pressure signal 4 and compares the pressure value 4 with the lower limit pressure value D and the upper limit pressure value D. When the pressure value 4 is less than or equal to the lower limit pressure value D, it is determined that the energy of accumulator 43 is insufficient. When the pressure value 4 is greater than or equal to the upper limit pressure value D, it is determined that the energy of accumulator 43 is sufficient.

[0070] When the right rear position hydraulic cylinder 41 needs to extend, the controller energizes the proportional directional valve 37 to operate in the left position, de-energizes the switching valve 42 to operate in the right position, and controls the motor to operate. This causes the high-pressure oil discharged by the variable pump 1 to enter the rodless chamber of the right rear position hydraulic cylinder 41 through the proportional directional valve 37 and the switching valve 42. Simultaneously, the oil in the rod chamber of the right rear position hydraulic cylinder 41 flows back to the oil tank 50 through the proportional directional valve 37. During this process, when the accumulator 43 has sufficient energy, the high-pressure oil stored in the accumulator 43 and the high-pressure oil discharged by the variable pump 1 can simultaneously supply oil to the rodless chamber of the right rear position hydraulic cylinder 41, thereby significantly increasing the movement speed of the right rear position hydraulic cylinder 41.

[0071] When the right rear position hydraulic cylinder 41 needs to retract, the controller first determines whether the energy of the accumulator 43 is sufficient. When the energy of the accumulator 43 is insufficient, the controller controls the proportional directional valve 437 to be energized and operate in the neutral position, controls the switching valve 42 to be energized and operate in the left position, and controls the motor to stop. The piston rod of the right rear position hydraulic cylinder 41 retracts under the action of the load gravity. The oil in its rodless chamber charges the accumulator 43 through the switching valve 42. At the same time, its rod chamber is replenished with oil through the oil replenishment check valve 438 to prevent the phenomenon of cavitation. When the energy of accumulator 43 is sufficient, the controller controls the proportional directional valve 437 to be energized and operate in the right position, controls the switching valve 42 to be de-energized and operate in the right position, and controls the motor to operate. This causes the high-pressure oil discharged by variable pump 1 to enter the rod chamber of the right rear position hydraulic cylinder 41 through the proportional directional valve 437. At the same time, the oil in the rodless chamber of the right rear position hydraulic cylinder 41 flows back to the oil tank 50 through the switching valve 42 and the proportional directional valve 437.

[0072] When the right rear hydraulic cylinder 41 is not activated, the controller assesses the energy status of accumulator 43. If accumulator 43 is underpowered, the controller de-energizes proportional directional valve 437 to operate in the neutral position, de-energizes switching valve 42 to operate in the right position, and activates the motor. This causes the high-pressure oil discharged from variable pump 1 to open check valve 436 and supply oil to accumulator 43. When accumulator 43 is fully charged, the output oil pressure at the outlet of variable pump 1 rises sharply. The pressure at the hydraulic control port of relief valve 435 exceeds the spring force in its spring chamber, causing the internal oil circuit of relief valve 435 to open and unload. At this time, the displacement of variable pump 1 decreases, only used to maintain internal system leakage, with no excess flow loss.

[0073] In this invention, an accumulator is installed in each hydraulic cylinder control circuit. This not only allows for energy recovery when the piston rod retracts under load, but also enables the stored energy in the accumulator to work together with the oil discharged from the variable pump to the rodless chamber of the hydraulic cylinder when the piston rod extends outward. This effectively increases the extension speed of the piston rod, facilitating rapid leveling operations. The accumulator is connected to both port A of the switching valve and port P of the proportional directional valve. Simultaneously, port B of the switching valve is connected to port A of the proportional directional valve, and ports P and B of the switching valve are connected to the rodless and rod chambers of the hydraulic cylinder, respectively. This ensures that the oil discharged from the variable pump enters both chambers and allows for recharging of the accumulator when its energy is insufficient, utilizing the return oil from the rodless chamber. This facilitates energy recovery and reuse of the collected energy. By connecting a pressure sensor to the accumulator, the pressure signal of the accumulator can be easily collected in real time. The controller can then obtain the pressure value of the accumulator in real time based on the pressure signal and further determine the energy status of the accumulator. Similarly, by connecting a displacement sensor to the hydraulic cylinder, the displacement signal of the hydraulic cylinder piston rod can be easily collected in real time. The controller can then obtain the displacement value of the hydraulic cylinder piston rod in real time based on the displacement signal, facilitating closed-loop control of the hydraulic cylinder's movement and improving control accuracy. Furthermore, when encountering situations requiring the overall height of the machine to be raised or lowered, the controller can independently control each control loop based on the data from the displacement sensors. This allows the four hydraulic cylinders in their independent states to extend to or retract to the same position, facilitating the raising or lowering of the overall machine height. When the overall machine height is raised, the overall passability is significantly enhanced, significantly improving the agricultural machinery's ability to travel on continuously undulating roads. Connecting the rodless chamber of the hydraulic cylinder to the oil tank via a replenishing check valve allows for connection in the neutral position of the proportional directional valve. When using the accumulator to recover energy from the hydraulic cylinder under load, the phenomenon of cavitation in the rod chamber of the hydraulic cylinder is avoided. Load 1 and Load 2 are connected to the left front and right front hydraulic cylinders respectively. Load 1 and Load 2 are connected by a connecting clip 1. The locking state of the connecting clip can be used to synchronize the operation of the two front hydraulic cylinders as needed. Load 3 and Load 4 are connected to the left rear and right rear hydraulic cylinders respectively. Load 3 and Load 4 are connected by a connecting clip 2. The locking state of the connecting clip 2 can be used to synchronize the operation of the two rear hydraulic cylinders as needed. Alternatively, the four hydraulic cylinders can be operated independently by opening the connecting clips. This allows the leveling system to flexibly perform leveling actions according to different working conditions during the leveling process, improving the system's intelligence.Installing a pitch angle sensor on the frame of agricultural machinery allows for real-time acquisition of pitch angle signals in the pitch direction. The controller can then obtain the frame's pitch angle data based on these signals. Similarly, installing a roll angle sensor on the frame allows for real-time acquisition of roll angle signals in the roll direction. The controller can then obtain the frame's roll angle data based on these signals. This enables the controller to determine the overall tilt status of the machine and control the hydraulic cylinders at different positions based on the tilt status, thereby achieving rapid leveling of the entire machine.

[0074] This leveling system has a simple structure and high reliability. It has good terrain adaptability and climbing ability, and can be effectively used in agricultural production in hilly areas. It has good adaptability to work areas with uneven roads or steep slopes, and can avoid the occurrence of uncoordinated four wheels of agricultural machinery or even rollover caused by uneven roads or steep slopes.

Claims

1. A vehicle frame adaptive leveling system, the adaptive leveling system being installed in agricultural machinery, comprising a variable displacement pump (1) and a motor, the motor being coaxially connected to the variable displacement pump (1); characterized in that, It also includes the control circuits for the left front hydraulic cylinder, the right front hydraulic cylinder, the left rear hydraulic cylinder, the right rear hydraulic cylinder, the pitch angle sensor, and the roll angle sensor; The control circuit of the left front hydraulic cylinder consists of a check valve (4), a proportional directional valve (5), a switching valve (11), an accumulator (12), a left front position hydraulic cylinder (10), a replenishing check valve (6), a pressure sensor (13), a displacement sensor (8), and a load (9); the inlet of the check valve (4) is connected to the outlet of the variable pump (1), and its outlet is connected to the P port of the proportional directional valve (5), the A port of the switching valve (11), and the accumulator (12), respectively; the T port of the proportional directional valve (5) is connected to the oil tank (50), and its B port is connected to the rod chamber oil port of the left front position hydraulic cylinder (10); the control circuit of the left front hydraulic cylinder (6) consists of a check valve (4), a proportional directional valve (5), a switching valve (11), a displacement sensor (8), and a load (9); the inlet of the check valve (4) is connected to the outlet of the variable pump (1), and its outlet is connected to the P port of the proportional directional valve (5), the A port of the switching valve (11), and the load (9). Port B of 11) is connected to port A of proportional directional valve (5), and port P is connected to the rodless chamber port of the left front position hydraulic cylinder (10); the inlet of the replenishing check valve (6) is connected to the oil tank (50), and its outlet is connected to the rod chamber port of the left front position hydraulic cylinder (10); the pressure sensor (13) is connected to the accumulator (12) for real-time acquisition of the pressure signal inside the accumulator (12); the displacement sensor (8) is connected to the piston rod of the left front position hydraulic cylinder (10) for real-time acquisition of the displacement signal of the piston rod of the left front position hydraulic cylinder (10); the load (9) is connected to the piston rod end of the left front position hydraulic cylinder (10). The control circuit of the right front hydraulic cylinder consists of a second check valve (15), a second proportional directional valve (16), a second switching valve (21), a second accumulator (22), a right front position hydraulic cylinder (20), a second replenishing check valve (17), a second pressure sensor (23), a second displacement sensor (18), and a second load (19). The inlet of the second check valve (15) is connected to the outlet of the variable pump (1), and its outlet is connected to the P port of the second proportional directional valve (16), the A port of the second switching valve (21), and the second accumulator (22), respectively. The T port of the second proportional directional valve (16) is connected to the oil tank (50), and its B port is connected to the rod chamber oil port of the right front position hydraulic cylinder (20). The second switching valve... Port B of the second (21) is connected to port A of the second proportional directional valve (16), and its port P is connected to the rodless chamber port of the right front position hydraulic cylinder (20); the inlet of the second replenishing check valve (17) is connected to the oil tank (50), and its outlet is connected to the rod chamber port of the right front position hydraulic cylinder (20); the second pressure sensor (23) is connected to the second accumulator (22) and is used to collect the pressure signal inside the second accumulator (22) in real time; the second displacement sensor (18) is connected to the piston rod of the right front position hydraulic cylinder (20) and is used to collect the displacement signal of the piston rod of the right front position hydraulic cylinder (20) in real time; the second load (19) is connected to the piston rod end of the right front position hydraulic cylinder (20); The control circuit of the left rear hydraulic cylinder consists of a check valve three (25), a proportional directional valve three (26), a switching valve three (32), an accumulator three (33), a left rear position hydraulic cylinder (31), a replenishing check valve three (27), a pressure sensor three (34), a displacement sensor three (29), and a load three (30). The oil inlet of the check valve three (25) is connected to the oil outlet of the variable pump (1), and its oil outlet is connected to the P port of the proportional directional valve three (26), the A port of the switching valve three (32), and the accumulator three (33), respectively. The T port of the proportional directional valve three (26) is connected to the oil tank (50), and its B port is connected to the rod chamber oil port of the left rear position hydraulic cylinder (31). The switching valve three (25) is connected to the oil tank (50), and its B port is connected to the rod chamber oil port of the left rear position hydraulic cylinder (31). Port B of valve 3 (32) is connected to port A of proportional directional valve 3 (26), and port P is connected to the rodless chamber port of the left rear position hydraulic cylinder (31); the inlet of the replenishing check valve 3 (27) is connected to the oil tank (50), and its outlet is connected to the rod chamber port of the left rear position hydraulic cylinder (31); the pressure sensor 3 (34) is connected to accumulator 3 (33) and is used to collect the pressure signal inside accumulator 3 (33) in real time; the displacement sensor 3 (29) is connected to the piston rod of the left rear position hydraulic cylinder (31) and is used to collect the displacement signal of the piston rod of the left rear position hydraulic cylinder (31) in real time; the load 3 (30) is connected to the piston rod end of the left rear position hydraulic cylinder (31); The control circuit of the right rear hydraulic cylinder consists of a check valve four (36), a proportional directional valve four (37), a switching valve four (42), an accumulator four (43), a right rear position hydraulic cylinder (41), a replenishing check valve four (38), a pressure sensor four (44), a displacement sensor four (39), and a load four (40). The inlet of the check valve four (36) is connected to the outlet of the variable pump (1), and its outlet is connected to the P port of the proportional directional valve four (37), the A port of the switching valve four (42), and the accumulator four (43), respectively. The T port of the proportional directional valve four (37) is connected to the oil tank (50), and its B port is connected to the rod chamber oil port of the right rear position hydraulic cylinder (41). The switching valve four (36) is connected to the oil tank (50), and its B port is connected to the rod chamber oil port of the right rear position hydraulic cylinder (41). Port B of valve 4 (42) is connected to port A of proportional directional valve 4 (37), and port P is connected to the rodless chamber port of the right rear position hydraulic cylinder (41); the inlet of the replenishing check valve 4 (38) is connected to the oil tank (50), and its outlet is connected to the rod chamber port of the right rear position hydraulic cylinder (41); the pressure sensor 4 (44) is connected to accumulator 4 (43) and is used to collect the pressure signal inside accumulator 4 (43) in real time; the displacement sensor 4 (39) is connected to the piston rod of the right rear position hydraulic cylinder (41) and is used to collect the displacement signal of the piston rod of the right rear position hydraulic cylinder (41) in real time; the load 4 (40) is connected to the piston rod end of the right rear position hydraulic cylinder (41); Load 1 (9) and load 2 (19) are connected by connecting buckle 1 (7); load 3 (30) and load 4 (40) are connected by connecting buckle 2 (28); both connecting buckle 1 (7) and connecting buckle 2 (28) have electric control locking and disconnecting functions. In the locked state, the two loads connected to it are rigidly connected. In the disconnected state, the two loads connected to it move independently. The pitch angle sensor is mounted on the frame of the agricultural machinery and is used to collect pitch angle signals in the pitch direction in real time. The tilt angle sensor is installed on the frame of the agricultural machinery to collect the tilt angle signal in the tilt direction in real time. The controller is connected to pressure sensor 1 (13), pressure sensor 2 (23), pressure sensor 3 (34), pressure sensor 4 (44), displacement sensor 1 (8), displacement sensor 2 (18), displacement sensor 3 (29), displacement sensor 4 (39), connecting buckle 1 (7), connecting buckle 2 (28), pitch angle sensor and roll angle sensor respectively.

2. The vehicle frame adaptive leveling system according to claim 1, characterized in that, It also includes a filter (2) and a safety valve (49), wherein the filter (2) is connected in series in the oil line between the oil inlet of the variable pump (1) and the oil tank (50); the oil outlet of the variable pump (1) is also connected to the oil tank (50) through the safety valve (49).

3. A vehicle frame adaptive leveling system according to claim 1 or 2, characterized in that, It also includes overflow valve one (3), overflow valve two (14), overflow valve three (24) and overflow valve four (35). The oil inlet of the one-way valve one (4) is connected to the oil tank (50) through overflow valve one (3), and the hydraulic control port of the overflow valve one (3) is connected to the oil outlet of the one-way valve one (4). The oil inlet of the one-way valve two (15) is connected to the oil tank (50) through overflow valve two (14). The hydraulic control port of the one-way valve two (14) is connected to the oil outlet of the one-way valve one (4). The control port is connected to the oil outlet of the one-way valve two (15), the oil inlet of the one-way valve three (25) is connected to the oil tank (50) through the overflow valve three (24), the hydraulic control port of the overflow valve three (24) is connected to the oil outlet of the one-way valve three (25), the oil inlet of the one-way valve four (36) is connected to the oil tank (50) through the overflow valve four (35), and the hydraulic control port of the overflow valve four (35) is connected to the oil outlet of the one-way valve four (36).

4. The adaptive leveling system for a vehicle frame according to claim 3, characterized in that, It also includes a filtration circuit; the filtration circuit consists of a filter pump (46), a second filter (45), a spring-loaded check valve (47) and a fine filter (48). The oil inlet of the filter pump (46) is connected to the oil tank (50) through the second filter (45), and its oil outlet is connected to the oil inlet of the spring-loaded check valve (47) and the oil inlet of the fine filter (48) respectively. The oil outlet of the spring-loaded check valve (47) and the oil outlet of the fine filter (48) are both connected to the oil tank (50).

5. The vehicle frame adaptive leveling system according to claim 4, characterized in that, The proportional directional valve one (5), proportional directional valve two (16), proportional directional valve three (26) and proportional directional valve four (37) are all three-position four-way valves. When they are energized and working in the left position, the oil circuit between their P port and A port is connected, and the oil circuit between their T port and B port is connected. When they are de-energized and working in the middle position, their A port, B port, P port and T port are each cut off and not connected to each other. When they are energized and working in the right position, the oil circuit between their P port and B port is connected, and the oil circuit between their T port and A port is connected.

6. The adaptive leveling system for a vehicle frame according to claim 5, characterized in that, The switching valves 1 (11), 2 (21), 3 (32) and 4 (42) are all two-position three-way directional valves. When they are energized and in the left position, the oil circuit between their P port and A port is connected and their B port is closed. When they are de-energized and in the middle position, their A port is closed and the oil circuit between their P port and B port is connected.

7. A vehicle frame adaptive leveling system according to claim 6, characterized in that, The controller is a PLC controller.

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