An electro-hydraulic proportional lift valve group for a rotary tillage device of a tractor

Abstract

The present invention discloses an electro-hydraulic proportional lift valve group for a tractor rotary tillage device, which comprises a valve body and an overflow valve, a first proportional solenoid valve, a second proportional solenoid valve, a rising valve, a falling valve, and a shuttle valve arranged on the valve body; the oil outlet of the rising valve, the second oil inlet of the shuttle valve, and the oil inlet of the falling valve are respectively communicated with the working oil circuit, and at the same time, the oil inlet of the second proportional solenoid valve is communicated with the oil outlet of the shuttle valve to form a shuttle valve oil circuit; wherein, the oil outlet of the first proportional solenoid valve is communicated with the control oil port of the rising valve; the control oil port of the falling valve is communicated with the oil outlet of the second proportional solenoid valve, which is used to control the communication between the oil inlet and the oil return port of the falling valve to complete the unloading of the working oil circuit. This electro-hydraulic proportional lift valve group can perform rising, falling, and suspension control on the rotary tillage device, and perform electro-hydraulic proportional distribution and stepless speed change adjustment based on the data provided by the force-position sensor, so that the tractor-mounted rotary tillage device can achieve precise control of the tillage depth and maintain the function of constant tillage depth.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic valve groups, and particularly to an electro-hydraulic proportional lift valve group for a rotary tillage device of a tractor. Background Art

[0002] As an important working unit of a tractor, the research on the rotary tillage device is related to the tillage efficiency of the tractor, the optimization of tillage effect, and also related to the successful transformation of agricultural modernization.

[0003] At present, most of the rotary tillage devices of tractors in China are suspension systems that are mechanically hydraulically controlled by manual multi-way valves. The main disadvantage of this control method is that during the tillage process, in order to achieve the required tillage depth, the driver needs to operate the handle while roughly estimating the depth of the tillage tool in the soil by experience. The tillage depth cannot be accurately controlled. At the same time, due to the unevenness of the field surface, it is necessary to continuously adjust the tillage depth, with frequent operations, high labor intensity, and low operation efficiency; it cannot adapt to various land environment conditions. When the soil resistance ratio is different, the load of the tractor changes greatly, and the tillage depth is uneven and inconsistent; the system structure is complex, occupies a large space, and has limited speed change gears. The existing structure cannot meet the needs of users. Summary of the Invention

[0004] To overcome the defects of the prior art, the purpose of the present invention is to provide an electro-hydraulic proportional lift valve group for a rotary tillage device of a tractor, which performs lifting, lowering, and suspension on the rotary tillage device through electro-hydraulic control technology, and performs electro-hydraulic proportional distribution and stepless speed change adjustment based on the data provided by a force-position sensor, so that the tractor-mounted rotary tillage device can achieve accurate control of the tillage depth and maintain the function of a constant tillage depth.

[0005] For this purpose, the present invention proposes an electro-hydraulic proportional lift valve group for a rotary tillage device of a tractor, including a valve body and an overflow valve, a proportional solenoid valve I, a proportional solenoid valve II, a lift valve, a lowering valve, and a shuttle valve provided on the valve body; the oil inlet of the overflow valve, the oil inlet of the proportional solenoid valve I, the oil inlet of the lift valve, and the first oil inlet of the shuttle valve are connected in parallel and connected to the main oil circuit; the oil return port of the proportional solenoid valve I, the oil return port of the lift valve, the oil return port of the proportional solenoid valve II, and the oil return port of the lowering valve are connected in parallel and connected to the secondary oil return circuit; the oil return port of the overflow valve is communicated with the main oil return circuit T to form a main oil return circuit; the oil outlet of the lift valve, the second oil inlet of the shuttle valve, and the oil inlet of the lowering valve are respectively communicated with the working oil circuit, and at the same time, the oil inlet of the proportional solenoid valve II is communicated with the oil outlet of the shuttle valve to form a shuttle valve oil circuit.

[0006] Among them, the oil outlet of the first proportional solenoid valve is communicated with the control oil port of the rising valve to form a rising control oil circuit for controlling the communication between the oil outlet and the working oil port of the rising valve to supply oil to the working oil circuit; the control oil port of the falling valve is communicated with the oil outlet of the second proportional solenoid valve to form a falling control oil circuit for controlling the communication between the oil inlet and the oil return port of the falling valve to unload the working oil circuit.

[0007] Furthermore, a check valve is installed on the one-way oil path between the oil outlet and the working oil port C of the rising valve; a back pressure oil circuit is provided between the back pressure oil port of the rising valve and the back pressure port of the overflow valve.

[0008] Furthermore, the rising valve is a Y-type two-position four-way directional control valve, including a spool valve two, a spring, a second spring seat, a third spring seat, a second valve cover, a second adjusting screw, and a second nut; two semi-circular grooves and two straight grooves are evenly distributed on the circumference of the spool valve two. Among them, the semi-circular groove is opposite to the unloading valve position of the rising valve, and the semi-circular groove is used to limit the oil discharge flow of the back pressure oil circuit; the straight groove is opposite to the back pressure valve position of the rising valve, and the straight groove is used to limit the flow of the main oil circuit oil into the back pressure oil circuit.

[0009] Furthermore, four trapezoidal grooves one are evenly distributed on the circumference of the spool valve two. The trapezoidal groove one is opposite to the working valve position of the rising valve, and the notch of the trapezoidal groove one is narrow at the top and wide at the bottom, so that the flow acceleration process of the working oil circuit is stable.

[0010] Furthermore, the falling valve is a two-position two-way directional control valve, including a spool valve three, a spring, a spring seat, a valve seat, a valve cover, an adjusting screw, and a nut; four trapezoidal grooves two are evenly distributed on the circumference of the spool valve three. The trapezoidal groove two is opposite to the unloading valve position of the falling valve, and the notch of the trapezoidal groove two is narrow at the top and wide at the bottom, so that the flow acceleration process of the working oil circuit is stable.

[0011] Furthermore, an annular array groove is provided on the spool valve three, and the annular array groove is located between the oil inlet and the control oil port of the falling valve for maintaining the pressure of the working oil circuit.

[0012] Furthermore, a one-way conical valve is provided on the spool valve three. The conical valve is located at the contact position between the valve seat and the valve cover, and the conical valve is communicated with the oil outlet of the falling valve.

[0013] Furthermore, the first proportional solenoid valve and the second proportional solenoid valve have the same structure and are both two-position three-way solenoid valves; among them, the second proportional solenoid valve includes a spool valve one, a second valve seat, a third spring, a coil, an electromagnet, an emergency push rod, and an adjusting screw; when powered off, the oil inlet is closed, and the oil outlet communicates with the oil return port; when powered on, the oil inlet, the oil outlet, and the oil return port communicate with each other.

[0014] Further, the overflow valve includes a first spool valve, a fourth spring, and a first plug; the first spool valve is provided with two damping holes a, damping holes b, a conical surface, an oil passage, and an oil groove, and an overflow valve is formed at the mating part of the conical surface and the valve body.

[0015] Further, the shuttle valve includes an upper valve seat, a steel ball, a fifth spring, a lower valve seat, and a second plug; when the pressure of the first oil inlet of the shuttle valve exceeds that of the second oil inlet, the passage from the first oil inlet to the oil outlet is opened; when the pressure of the second oil inlet exceeds that of the first oil inlet, the passage from the second oil inlet to the oil outlet is opened.

[0016] The electro-hydraulic proportional lift valve group for a tractor rotary tillage device provided by the present invention forms multiple oil circuits such as a working oil circuit, a control oil circuit, and a backpressure oil circuit by setting an up valve, a down valve, an overflow valve, and two proportional solenoid valves, and can perform up, down, and suspension controls on a working mechanism (rotary tillage device). Through the data provided by a force-position sensor, electro-hydraulic proportional distribution and stepless speed change adjustment are carried out, so that the tractor-mounted rotary tillage device can achieve precise control of the tillage depth and maintain the function of a constant tillage depth.

[0017] In addition to the purposes, features, and advantages described above, the present invention has other purposes, features, and advantages. The present invention will be further described in detail below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0019] Figure 1 is the front view of the electro-hydraulic proportional lift valve group for a tractor rotary tillage device of the present invention;

[0020] Figure 2 is the side view of the electro-hydraulic proportional lift valve group for a tractor rotary tillage device of the present invention;

[0021] Figure 3 is the bottom view of the electro-hydraulic proportional lift valve group for a tractor rotary tillage device of the present invention;

[0022] Figure 4 is the rear view of the electro-hydraulic proportional lift valve group for a tractor rotary tillage device of the present invention;

[0023] Figure 5 is the hydraulic schematic diagram of the electro-hydraulic proportional lift valve group for a tractor rotary tillage device of the present invention;

[0024] Figure 6 is the sectional view of the overflow valve in the electro-hydraulic proportional lift valve group for a tractor rotary tillage device of the present invention;

[0025] Figure 7 This is a cross-sectional view of the rising valve in the electro-hydraulic proportional lift valve group for the rotary tillage device of the tractor of the present invention;

[0026] Figure 8 This is a cross-sectional view of the check valve in the electro-hydraulic proportional lift valve group for the rotary tillage device of the tractor of the present invention;

[0027] Figure 9 This is a cross-sectional view of the shuttle valve in the electro-hydraulic proportional lift valve group for the rotary tillage device of the tractor of the present invention;

[0028] Figure 10 This is a cross-sectional view of the proportional solenoid valve in the electro-hydraulic proportional lift valve group for the rotary tillage device of the tractor of the present invention;

[0029] Figure 11 This is a cross-sectional view of the lowering valve in the electro-hydraulic proportional lift valve group for the rotary tillage device of the tractor of the present invention;

[0030] Figure 12 This is the electro-proportional characteristic curve of the proportional solenoid valve in the electro-hydraulic proportional lift valve group for the rotary tillage device of the tractor of the present invention;

[0031] Explanation of reference numerals

[0032] 1. Relief valve; 2. First proportional solenoid valve; 3. Rising valve; 4. Check valve; 5. Shuttle valve; 6. Second proportional solenoid valve; 7. Lowering valve; 8. Valve body; 9. Main oil circuit; 10. Main return oil circuit; 11. Auxiliary return oil circuit; 12. Rising control oil circuit; 13. One-way oil circuit; 14. Back pressure oil circuit; 15. Working oil circuit; 16. Shuttle valve oil circuit; 17. Lowering control oil circuit; P. Oil inlet; T1. Main oil return port; T2. Auxiliary oil return port; C. Working oil port;

[0033] 101. First plug; 102. Fourth spring; 103. First spool valve; 104. Relief valve; 105. Conical surface; 106. Damping hole a; 107. Damping hole b; 108. Oil passage; 109. Oil groove;

[0034] 31. Second adjusting screw; 32. Second nut; 33. Second valve cover; 34. Second spring seat; 35. Spring; 36. Second spool valve; 37. Third spring seat; 38. Semi-circular groove; 39. Unloading valve; 310. Back pressure valve; 311. Slotted hole; 312. Working valve; 313. First trapezoidal groove; 314. Oil groove;

[0035] 41. Plug; 42. Spring; 43. Second valve core; 44. Oil passage; 45. Conical valve; 46. Valve seat;

[0036] 51. Upper valve seat; 52. Steel ball; 53. Fifth spring; 54. Lower valve seat; 55. Second plug;

[0037] 61. Spool 1; 62. Second valve seat; 63. Third spring; 64. Coil; 65. Electromagnet; 66. Emergency push rod;

[0038] 71. First adjusting screw; 72. First nut; 73. First valve cover; 74. First spring seat; 75. First spring; 76. Slide valve 3; 77. Conical valve; 78. Unloading valve; 79. Trapezoidal groove 2; 710. First valve seat; 711. Annular array groove. Detailed implementation manner

[0039] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0040] As Figures 1 to 5 shown, the electro-hydraulic proportional lift valve group for the tractor rotary tillage device of the present invention includes a valve body 8 and an overflow valve 1, a proportional solenoid valve 1 2, a proportional solenoid valve 2 6, a rising valve 3, a lowering valve 7, a check valve 4, and a shuttle valve 5 provided on the valve body.

[0041] The electro-hydraulic proportional lift valve group further includes: a main oil circuit 9 for paralleling the overflow valve 1, the proportional solenoid valve 1 2, the rising valve 3, and the shuttle valve 5; a main return oil circuit 10 for connecting the overflow valve 1; a sub-return oil circuit 11 for paralleling the proportional solenoid valve 1 2, the rising valve 3, the proportional solenoid valve 2 6, and the lowering valve 7; a rising control oil circuit 12 for connecting the proportional solenoid valve 1 2 and the rising valve 3; a one-way oil circuit 13 for connecting the check valve 4 and the rising valve 3; a back pressure oil circuit 14 for connecting the rising valve 3 and the overflow valve 1; a working oil circuit 15 for paralleling the check valve 4, the shuttle valve 5, and the lowering valve 7; a shuttle valve oil circuit 16 for connecting the shuttle valve 5 and the proportional solenoid valve 2 6; a lowering control oil circuit 17 for connecting the proportional solenoid valve 2 6 and the lowering valve 7; an oil inlet P for connecting to a hydraulic pump; an oil port for connecting to the main return oil port T1; an oil port for connecting to the sub-return oil port T2; an oil port for connecting to the working oil port C of a hydraulic cylinder.

[0042] Among them, the oil inlet of the overflow valve 1, the oil inlet of the proportional solenoid valve 1 2, the oil inlet of the rising valve 3, and the first oil inlet of the shuttle valve 5 are connected in parallel and connected to the main oil circuit 9; the oil return ports of the proportional solenoid valve 1 2, the rising valve 3, the proportional solenoid valve 2 6, and the lowering valve 7 are connected in parallel and connected to the sub-return oil circuit 11; the oil return port of the overflow valve 1 is communicated with the main return oil circuit T1 to form the main return oil circuit 10; the oil outlet of the rising valve 3, the second oil inlet of the shuttle valve 5, and the oil inlet of the lowering valve 7 are respectively communicated with the working oil circuit 15, and at the same time, the oil inlet of the proportional solenoid valve 2 6 is communicated with the oil outlet of the shuttle valve 5 to form the shuttle valve oil circuit 16.

[0043] The oil outlet of the proportional solenoid valve 1 is communicated with the control oil port of the lifting valve 3 to form a lifting control oil circuit 12 for controlling the communication between the oil outlet and the working oil port of the lifting valve 3 to supply oil to the working oil circuit. The control oil port of the lowering valve 7 is communicated with the oil outlet of the proportional solenoid valve 2 to form a lowering control oil circuit 17 for controlling the communication between the oil inlet and the oil return port of the lowering valve 7 to unload the working oil circuit. A check valve 4 is installed on the one-way oil circuit 13 between the oil outlet of the lifting valve and the working oil port C. A back-pressure oil circuit 14 is provided between the back-pressure oil port of the lifting valve 3 and the back-pressure port of the relief valve 1.

[0044] Specifically, as Figure 9 shown, the shuttle valve 5 has a structure in which a steel ball and two conical ports are alternately sealed, and includes an upper valve seat 51, a steel ball 52, a fifth spring 53, a lower valve seat 54, and a second plug 55. The shuttle valve 5 has two oil inlets ①, ③ and one oil outlet ②. When the pressure of the first oil inlet ① exceeds that of the second oil inlet ③, ① to ② is opened; when the pressure of the second oil inlet ③ exceeds that of the first oil inlet ①, ③ to ② is opened, so that no matter which oil inlet has high pressure, it can ensure that there is pressure at the oil outlet. The shuttle valve 5 is used for a two-way hydraulic pressure port and is connected to the proportional solenoid valve 2 that controls the lowering of the rotary tillage device.

[0045] When the hydraulic pump injects oil from the oil inlet P into the main oil circuit 9, the oil pressure at the first oil inlet ① of the shuttle valve 5 compresses the fifth spring 53, and the first oil inlet ① to the oil outlet ② is opened, and the shuttle valve oil circuit 16 is communicated with the main oil circuit 9; at the same time, the second oil inlet ③ is closed. When the proportional solenoid valve 1 and the proportional solenoid valve 2 are not energized, the oil in the main oil circuit 9 is in a closed state, and no oil flows out from the working oil port C connected to the hydraulic cylinder.

[0046] As Figure 6 shown, the relief valve 1 has a spool mobile structure, including a spool 103, a fourth spring 102, and a first plug 101. The spool 103 is provided with two damping holes a106, damping hole b107, a conical surface 105, an oil passage 108, and an oil groove 109. An overflow valve port 104 is formed at the mating part of the conical surface 105 and the valve body. This valve is used to provide the lowest safety pressure when the rotary tillage device is suspended or lowered, and can be converted into the highest working pressure when lifting is required.

[0047] The oil in the main oil circuit 9 enters the inner cavity of the oil inlet ② of the relief valve 1, and then passes through the damping hole a106, the oil passage 108, and the oil groove 109 of the spool 103 to enter the inner cavity of the oil control port ①, generating a reaction force on the tail end of the spool 103. When the reaction force is greater than the spring force, the fourth spring 102 is compressed, and the spool 103 starts to move. Limited by the flow rate of the damping hole a106, the spool 103 moves slowly.

[0048] When the overflow valve 104 is opened, the oil inlet ② of the overflow valve 1 communicates with the oil outlet ③, and the oil fluid overflows through the port ③ to the secondary return oil circuit 11. Limited by the conical surface, the overflow flow rate is small. When the spool 103 continues to move, the damping hole b107 is opened, the reaction force of the spool 103 rapidly increases, the movement of the spool 103 speeds up, and the overflow flow rate increases. Until the reaction force is balanced with the spring force, the oil pressure in the main oil circuit 9 is maintained at the lowest constant pressure, creating conditions for the operation of each valve and also protecting the oil supply pump from bearing a lower load. Due to the design of the above structure, the pressure rise in the main oil circuit is stable and there is no impact phenomenon.

[0049] As Figure 7 shown, the rising valve 3 is a spool mobile structure (a Y-type two-position four-way directional control valve), including a spool 36, a second spring 35, a second spring seat 34, a third spring seat 37, a second valve cover 33, a second adjusting screw 31, and a second nut 32. The spool 36 is provided with two semicircular grooves 38 evenly distributed in the circumferential direction, two straight grooves 311 evenly distributed in the circumferential direction, four trapezoidal grooves 313 evenly distributed in the circumferential direction, and an oil groove 314 at the tail end. This valve is used to fill the hydraulic cylinder with oil and drive the rotary tillage device to perform a rising action.

[0050] When the proportional solenoid valve 1-2 is energized, a part of the oil fluid in the main oil circuit 9 enters the rising control oil circuit 12, and then enters the inner cavity of the control oil port ① of the rising valve 3, generating a reaction force on the tail end of the spool 36. When the reaction force is greater than the spring force, the spring is compressed, and the spool 36 starts to move to the left. The backpressure valve 310 and the working valve 312 are opened, and the unloading valve 39 is closed. The oil inlet ②, the oil outlet ③, and the backpressure oil port ④ of the rising valve 3 communicate with each other, and the oil return port ⑤ is closed. The oil fluid in the main oil circuit passes through the ports ② and ③ of the rising valve 3 into the one-way oil circuit 13, opens the one-way valve 4, enters the working oil circuit 15, and fills the hydraulic cylinder through the working oil port C;

[0051] At the same time, another part of the oil fluid in the main oil circuit passes through the ports ② and ④ of the rising valve 3 into the backpressure oil circuit 14, generating a backpressure at the port ④ of the overflow valve 1, pushing the overflow spool 36 to move in the reverse direction, and the overflow valve of the overflow valve 1 is closed slightly. The oil pressures in the main oil circuit 9 and the working oil circuit 15 rise synchronously. When the oil pressure is greater than the load of the hydraulic cylinder, the rotary tillage device starts to rise. The four trapezoidal grooves 313 evenly distributed in the circumferential direction on the spool 36 have a narrow upper part and a wide lower part, so that the flow rate of the port C increases from small to large as the spool 36 moves, and the acceleration process of the hydraulic cylinder is stable.

[0052] The two straight grooves 311 evenly distributed in the circumferential direction on the spool 36 are structured such that the straight grooves 311 are opposite to the position of the backpressure valve 310 of the rising valve 3, restricting the flow rate of the oil fluid in the main oil circuit 9 entering the backpressure oil circuit 14, and the pressure rise of the overflow valve 1 is stable. Due to the design of the above structure, there is no jitter or impact phenomenon during the rising process of the rotary tillage device.

[0053] When the rotary tillage device rises to a proper position, the first proportional solenoid valve 2 is de-energized, and the oil in the rising control oil circuit 12 is unloaded through the secondary return oil circuit 11. The reaction force at the end of the spool two 36 of the rising valve 3 disappears, and the spring of the rising valve 3 pushes the spool two 36 to reset. The back pressure valve and the working valve are closed, the ports ② and ③ are closed, the one-way oil circuit 13 is cut off, and the one-way valve 4 is closed. At the same time, the unloading valve is opened, the ports ④ and ⑤ are communicated, and the oil in the back pressure oil circuit 14 is unloaded through the secondary return oil circuit 11. The back pressure at the port ④ of the overflow valve 1 disappears, and the main oil circuit 9 returns to the low-pressure state. Two semi-circular grooves 38 are evenly distributed on the circumference of the spool two 36, and the semi-circular grooves 38 are opposite to the position of the unloading valve 39 of the rising valve 3, so that the unloading flow rate of the oil in the back pressure oil circuit 14 is limited, and the pressure of the main oil circuit drops smoothly.

[0054] The pressure of the main oil circuit 9 drops, forming a pressure difference with the load pressure of the working oil circuit 15. The port ① of the shuttle valve 5 is closed. In this way, the oil in the working oil circuit 15 forms a closed pressure-holding state, the hydraulic cylinder floats and does not move, and the tractor drives the rotary tillage device to perform rotary tillage operations. Among them, the second adjusting screw 31 of the rising valve 3 can adjust the spring force, and further adjust the moving speed of the spool two 36.

[0055] As Figure 11 shown, the lowering valve 7 is a spool moving type structure (two-position two-way electromagnetic reversing valve), including a spool three 76, a first spring 75, a first spring seat 74, a first valve seat 710, a first valve cover 73, a first adjusting screw 71, and a first nut 72. The spool three 76 is provided with a conical surface, four trapezoidal grooves two 79 evenly distributed on the circumference, and an annular array groove 711. This valve is used to drain oil from the hydraulic cylinder and drive the rotary tillage device to perform a lowering action.

[0056] When the second proportional solenoid valve 6 is energized, the oil in the working oil circuit 15 enters the lowering control oil circuit 17, and then enters the inner cavity of the control oil port ① of the lowering valve 7, generating a reaction force on the end of the spool three 76. When the reaction force is greater than the spring force, the spring is compressed, and the spool three 76 starts to move to the left. The unloading valve 78 and the conical valve 77 are opened, the oil inlet port ② and the oil outlet port ③ are communicated, and the oil in the working oil circuit 15 is unloaded through the ports ② and ③ to the secondary return oil circuit 11, and the hydraulic cylinder drives the rotary tillage device to lower.

[0057] Four trapezoidal grooves two 79 are evenly distributed on the circumference of the spool three 76. The trapezoidal grooves two 79 are opposite to the position of the unloading valve 78 of the lowering valve 7, and the mouths of the trapezoidal grooves two 79 are narrow at the top and wide at the bottom, so that the unloading flow rate at the port C increases from small to large as the spool three 76 moves, the acceleration of the hydraulic cylinder is stable, and there is no jitter or impact phenomenon during the lowering process of the rotary tillage device.

[0058] When the rotary tillage device descends to the appropriate position, the proportional solenoid valve II 6 is de-energized, and the oil in the descending control oil circuit 17 is unloaded through the secondary return oil circuit 11. The reaction force at the end of the spool III 76 disappears, and the spring of the descending valve 7 pushes the spool III 76 to reset. The unloading valve and the conical valve close, and the ports ② and ③ of the descending valve 7 are cut off. In this way, the working oil circuit 15 forms a closed pressure-holding state again, and the hydraulic cylinder floats and remains stationary. Among them, the adjusting screw of the descending valve 7 can adjust the spring force, and further adjust the moving speed of the spool III 76.

[0059] The spool III 76 is provided with an annular array of grooves 711, which increases the flow resistance of the oil in the working oil circuit 15 through the gap between the spool III 76 and the valve cavity, and extremely reduces the oil leakage, maximizing the pressure-holding effect of the hydraulic cylinder.

[0060] The spool III 76 is provided with a one-way conical valve 77, which can prevent the oil in the secondary return oil circuit 11 from generating back pressure due to unloading during the lifting and pressure-holding switching process of the rotary tillage device, opening the valve of the descending valve 7, and causing the oil in the working oil circuit 15 to flow back to the secondary return oil circuit 11, affecting the rising and pressure-holding of the hydraulic cylinder.

[0061] As Figure 8 shown, the one-way valve 4 has a spool cone sealing structure, including a spool II 43, a valve seat 46, a spring 42, and a plug 41. This valve is used to open the conical valve 45 when the hydraulic cylinder is filling with oil and close the conical valve during pressure-holding. The spool II 43 is provided with an oil passage 44 to eliminate the back pressure generated at the end of the spool II 43 due to oil seepage.

[0062] As Figure 10 shown, the proportional solenoid valve II 6 is a two-position three-way cartridge-type solenoid valve, including a spool I 61, a second valve seat 62, a third spring 63, a coil 64, an electromagnet 65, and an emergency push rod 66. When de-energized, the oil inlet ② is closed, and the oil outlet ① communicates with the oil return port ③. When energized, the oil inlet ②, the oil outlet ①, and the oil return port ③ communicate with each other.

[0063] The proportional solenoid valve II 6 is controlled by an electronic control unit. When the electronic control unit receives the voltage change signals sent by the angle sensor and the force sensor of the tillage tool, it correspondingly adjusts the current output to the proportional solenoid valve, so as to continuously and proportionally adjust the pressure of the rising control oil circuit 12 or the descending control oil circuit 17 (see Figure 12 ), control the opening and closing size of the rising valve 3 or the spool III 76 valve, change the flow rate of the hydraulic cylinder, achieve stepless speed regulation of the lifting of the rotary tillage device, realize precise control of the tillage depth, and maintain the function of constant tillage depth. Among them, the proportional solenoid valve I 2 controls the displacement of the spool II 36, and the proportional solenoid valve II 6 controls the displacement of the spool III 76.

[0064] An emergency push rod is provided at the end of the proportional solenoid valve. When the coil is de-energized due to a fault or the valve core is stuck due to oil pollution, the emergency push rod can be pressed to move the valve core and open the valve.

[0065] In addition to the above beneficial effects, the electro-hydraulic proportional lift valve group of the present invention has the following advantages: 1. The valve group of the present invention adjusts the electro-hydraulic proportional distribution according to the tillage environment and requirements during tillage, controls the depth of the tillage tool, realizes precise control of the tillage depth, and maintains the function of constant tillage depth; 2. The valve group of the present invention realizes the phenomenon of no jitter and no impact of the tillage tool through the flow rate control of the charging / discharging oil of the hydraulic cylinder; 3. The valve group of the present invention integrates valve blocks with different functions on the valve body to form a whole, simplifies the structure, is small in size, light in weight, and easy to install; 4. The valve group of the present invention can be remotely controlled externally, improves the operation performance, and reduces the labor intensity of the driver; 5. The valve group of the present invention develops in the direction of intelligence and unmanned operation.

[0066] The working principle and working process of the electro-hydraulic proportional lift valve group of the present invention are briefly described below in conjunction with the accompanying drawings.

[0067] Preparation stage: When the hydraulic pump injects oil from the oil inlet P into the main oil circuit 9, the oil in the main oil circuit 9 enters the oil inlet ② and the oil control port ① of the overflow valve 1. The valve of the overflow valve 1 is opened and the oil inlet ② is communicated with the oil outlet ③. The oil passes through the oil outlet ③ to the auxiliary return oil circuit 11 for overflow. The oil pressure in the main oil circuit 9 is maintained at the lowest constant pressure, creating conditions for the work of each valve and protecting the oil supply pump from bearing a lower load.

[0068] At the same time, the oil pressure of the oil in the main oil circuit 9 entering the first oil inlet ① of the shuttle valve 5 compresses the fifth spring 53, and the first oil inlet ① to the oil outlet ② is opened. The shuttle valve oil circuit 16 is communicated with the main oil circuit 9; at the same time, the second oil inlet ③ is closed; in the case where the proportional solenoid valve one 2 and the proportional solenoid valve two 6 are not energized, the oil in the main oil circuit 9 is in a closed state, and no oil flows out from the working oil port C connected to the hydraulic cylinder, and the rotary tillage device connected to the hydraulic cylinder is in the lowest position.

[0069] Rise operation: When the proportional solenoid valve one 2 is energized, the oil inlet ②, the oil outlet ① and the oil return port ③ of the proportional solenoid valve one are interconnected. Part of the oil in the main oil circuit 9 enters the rise control oil circuit 12, and then enters the inner cavity of the control oil port ① of the rise valve 3 to control the commutation of the rise valve 3, so that the oil inlet ②, the oil outlet ③ and the back pressure oil port ④ of the rise valve 3 are interconnected, and the oil return port ⑤ is closed. The oil in the main oil circuit passes through the oil inlet ② and the oil outlet ③ of the rise valve 3 into the one-way oil circuit 13, opens the one-way valve 4, enters the working oil circuit 15, and fills the hydraulic cylinder through the working oil port C;

[0070] Meanwhile, another path of the oil in the main oil circuit 9 enters the backpressure oil circuit 14 through the oil inlet ② and the backpressure oil port ④ of the lifting valve 3, generating backpressure at the backpressure oil port ④ of the overflow valve 1, pushing the spool of the overflow valve 1 to move reversely, closing the overflow valve of the overflow valve 1 slightly, and synchronously increasing the oil pressures of the main oil circuit 9 and the working oil circuit 15. When the oil pressure of the working oil circuit 15 is greater than the load of the hydraulic cylinder, the rotary tillage device starts to rise.

[0071] Among them, four trapezoidal grooves 313 with upper narrow and lower wide openings are evenly distributed on the circumference of the spool two 36 of the lifting valve 3. The trapezoidal grooves 313 are opposite to the position of the working valve 312 of the lifting valve 3, so that the flow rate of port C increases from small to large as the spool moves, and the acceleration process of the hydraulic cylinder is stable. Two straight grooves 311 are evenly distributed on the circumference of the spool two 36 of the lifting valve 3, restricting the flow rate of the oil in the main oil circuit 9 entering the backpressure oil circuit 14, and the pressure of the overflow valve 1 rises smoothly. Due to the design of the above structure, there is no jitter or impact during the rising process of the rotary tillage device.

[0072] Lifting and holding operation: When the rotary tillage device rises to a suitable position, the proportional solenoid valve 1 2 is powered off, and the oil in the lifting control oil circuit 12 is unloaded through the secondary return oil circuit 11. The reaction force at the end of the spool of the lifting valve 3 disappears, and the spring of the lifting valve 3 pushes the spool to reset. The backpressure valve and the working valve of the lifting valve 3 are closed, the oil inlet ② and the oil outlet ③ are closed, the one-way oil circuit 13 is cut off, and the one-way valve 4 is closed. In this way, the working oil circuit 15 forms a closed pressure-holding state, and the hydraulic cylinder floats and remains stationary. At the same time, the unloading valve of the lifting valve 3 is opened, the backpressure oil port ④ is communicated with the oil return port ⑤, and the oil in the backpressure oil circuit 14 is unloaded through the secondary return oil circuit 11. The backpressure at the backpressure oil port ④ of the overflow valve 1 disappears, and the main oil circuit 9 returns to the low-pressure state. Two semi-circular grooves 38 are evenly distributed on the circumference of the spool two 36 of the lifting valve 3, restricting the unloading flow rate of the oil in the backpressure oil circuit 14, and the pressure of the main oil circuit drops smoothly.

[0073] Lowering operation: When the proportional solenoid valve 2 6 is powered on, the oil inlet ②, the oil return port ③ and the oil outlet ① of the proportional solenoid valve 2 6 communicate with each other. The oil in the working oil circuit 15 enters the lowering control oil circuit 17, and then enters the inner cavity of the control oil port ① of the lowering valve 7, generating a reaction force on the end of the spool. When the reaction force is greater than the spring force, the spring is compressed, the spool starts to move leftward, the unloading valve 78 and the conical valve 77 are opened, the oil inlet ② and the oil return port ③ of the lowering valve 7 communicate with each other, and the oil in the working oil circuit 15 passes through the lowering valve 7 to the secondary return oil circuit 11 for unloading, and the hydraulic cylinder drives the rotary tillage device to lower.

[0074] Among them, four trapezoidal grooves 79 with upper narrow and lower wide openings are evenly distributed on the circumference of the spool three 76, so that the unloading flow rate of port C increases from small to large as the spool moves, the acceleration of the hydraulic cylinder is stable, and there is no jitter or impact during the lowering process of the rotary tillage device.

[0075] Lower holding operation: When the rotary tillage device descends to the appropriate position, the proportional solenoid valve II 6 is de-energized, and the oil in the descending control oil circuit 17 is unloaded through the secondary return oil circuit 11. The reaction force at the end of the spool III 76 disappears, and the spring of the descending valve 7 pushes the spool to reset. The unloading valve and the conical valve close, and the oil inlet ② and the oil return port ③ of the descending valve 7 are cut off. In this way, the working oil circuit 15 forms a closed pressure-holding state again, and the hydraulic cylinder floats and remains stationary.

[0076] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An electro-hydraulic proportional lift valve group for a rotary tillage device of a tractor, characterized in that, It includes a valve body (8) and an overflow valve (1), a first proportional solenoid valve (2), a second proportional solenoid valve (6), a rising valve (3), a falling valve (7), and a shuttle valve (5) provided on the valve body (8); The oil inlet of the overflow valve (1), the oil inlet of the first proportional solenoid valve (2), the oil inlet of the rising valve (3), and the first oil inlet of the shuttle valve (5) are connected in parallel and connected to the main oil circuit (9); the oil return ports of the first proportional solenoid valve (2), the rising valve (3), the second proportional solenoid valve (6), and the falling valve (7) are connected in parallel and connected to the secondary oil return circuit (11); the oil return port of the overflow valve (1) is communicated with the main oil return circuit T1 to form the main oil return circuit (10); The oil outlet of the rising valve (3), the second oil inlet of the shuttle valve (5), and the oil inlet of the falling valve (7) are respectively communicated with the working oil circuit (15). At the same time, the oil inlet of the second proportional solenoid valve (6) is communicated with the oil outlet of the shuttle valve (5) to form a shuttle valve oil circuit (16); a check valve (4) is installed on the one-way oil circuit (13) between the oil outlet of the rising valve (3) and the working oil port C; a backpressure oil circuit (14) is provided between the backpressure oil port of the rising valve (3) and the backpressure port of the overflow valve (1); Among them, the oil outlet of the first proportional solenoid valve (2) is communicated with the control oil port of the rising valve (3) to form a rising control oil circuit (12) for controlling the communication between the oil outlet of the rising valve (3) and the working oil port to supply oil to the working oil circuit; The falling valve (7) is a two-position two-way reversing valve, including a spool three (76), a first spring (75), a first spring seat (74), a first valve seat (710), a first valve cover (73), a first adjusting screw (71), and a first nut (72); among them, four trapezoidal grooves two (79) are evenly distributed on the circumference of the spool three (76). The trapezoidal grooves two (79) are opposite to the unloading valve (78) of the falling valve (7), and the openings of the trapezoidal grooves two (79) are narrow at the top and wide at the bottom, so that the flow acceleration process of the working oil circuit (15) is stable; The control oil port of the falling valve (7) is communicated with the oil outlet of the second proportional solenoid valve (6) to form a falling control oil circuit (17) for controlling the communication between the oil inlet and the oil return port of the falling valve (7) to complete the unloading of the working oil circuit.

2. The electro-hydraulic proportional lift valve group for the rotary tillage device of a tractor according to claim 1, characterized in that, The lift valve (3) is a Y-shaped two-position four-way directional control valve, including a spool two (36), a second spring (35), a second spring seat (34), a third spring seat (37), a second valve cover (33), a second adjusting screw (31), and a second nut (32); two semi-circular grooves (38) and two straight grooves (311) are evenly distributed in the circumferential direction on the spool two (36). Among them, the semi-circular groove (38) is opposite to the unloading valve (39) of the lift valve (3), and the semi-circular groove (38) is used to limit the oil unloading flow of the back pressure oil circuit (14); the straight groove (311) is opposite to the back pressure valve (310) of the lift valve (3), and the straight groove (311) is used to limit the flow of the oil in the main oil circuit (9) into the back pressure oil circuit (14).

3. The electro-hydraulic proportional lift valve group for the rotary tillage device of a tractor according to claim 2, characterized in that, Four trapezoidal grooves one (313) are evenly distributed in the circumferential direction on the spool two (36). The trapezoidal groove one (313) is opposite to the working valve (312) of the lift valve (3), and the notch of the trapezoidal groove one (313) is narrow at the top and wide at the bottom, so that the flow acceleration process of the working oil circuit (15) is stable.

4. The electro-hydraulic proportional lift valve group for the rotary tillage device of a tractor according to claim 1, wherein, An annular array of grooves (711) is provided on the spool three (76). The annular array of grooves (711) is located between the oil inlet and the control oil port of the down valve (7) and is used to maintain the pressure of the working oil circuit (15).

5. The electro-hydraulic proportional lift valve group for the rotary tillage device of a tractor according to claim 1, characterized in that, A one-way conical valve (77) is provided on the spool three (76). The conical valve (77) is located at the contact position between the first valve seat (710) and the first valve cover (73), and the conical valve (77) is communicated with the oil outlet of the down valve (7).

6. The electro-hydraulic proportional lift valve group for the rotary tillage device of a tractor according to claim 1, characterized in that, The proportional solenoid valve one (2) and the proportional solenoid valve two (6) have the same structure and are both two-position three-way solenoid valves; among them, the proportional solenoid valve two (6) includes a spool one (61), a second valve seat (62), a third spring (63), a coil (64), an electromagnet (65), and an emergency push rod (66); when powered off, the oil inlet is closed, and the oil outlet communicates with the oil return port; when powered on, the oil inlet, the oil outlet, and the oil return port communicate with each other.

7. The electro-hydraulic proportional lift valve group for the rotary tillage device of the tractor according to claim 1, characterized in that, The overflow valve (1) includes a spool one (103), a fourth spring (102), and a first plug (101); two damping holes a (106), a damping hole b (107), a conical surface (105), an oil passage (108), and an oil groove (109) are provided on the spool one (103). An overflow valve (104) is formed at the mating part of the conical surface (105) and the valve body.

8. The electro-hydraulic proportional lift valve group for the rotary tillage device of a tractor according to claim 1, characterized in that, The shuttle valve (5) includes an upper valve seat (51), a steel ball (52), a fifth spring (53), a lower valve seat (54), and a second plug (55); when the pressure of the first oil inlet of the shuttle valve (5) exceeds the pressure of the second oil inlet, the first oil inlet to the oil outlet is opened; when the pressure of the second oil inlet exceeds the pressure of the first oil inlet, the second oil inlet to the oil outlet is opened.

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