Electro-hydraulic reversing flow proportional control valve with load flow compensation

Abstract

The application discloses an electro-hydraulic reversing flow proportional control valve with load flow compensation, pilot valves at two ends are driven by proportional electromagnets, the displacement of a main valve core relative to a valve body is controlled through a pilot oil way, and the purpose of hydraulic oil reversing of the valve body is realized. The opening size of the pilot valve is adjusted by the thrust of a proportional electromagnet at a certain side, the hydraulic oil thrust of the corresponding end of the main valve core is adjusted, the hydraulic oil flow area between the convex shoulder of the valve core and the sink groove of the valve body is adjusted, and the output hydraulic oil flow is controlled. When the electromagnet thrust is unchanged, the load of an oil outlet working oil way changes, the hydraulic oil output of the working oil port changes, the hydraulic flow change of the working oil port changes the force of a flow feedback piston on the valve body at a certain side, thereby adjusting the position of the corresponding side pilot valve, changing the driving force of the pilot oil way on the main valve core, finely adjusting the relative position of the convex shoulder on the main valve core relative to the sink groove of the valve body, changing the hydraulic oil flow area, thereby adjusting the hydraulic oil flow of the working oil port, making the working oil port oil flow not affected by the load change, and achieving the purpose of working oil port load flow compensation.

Description

Technical Field

[0001] This invention relates to the field of directional valves, and more particularly to an electro-hydraulic directional flow proportional control valve with load flow compensation. Background Technology

[0002] With the advent of steam technology and the application of hydraulic and pneumatic technologies in industrial development, directional control valves also began to emerge. With continuous research and development and improvement of technology, existing directional control valves can now meet the function of changing the flow direction in most hydraulic systems.

[0003] With the development of hydraulic technology, more and more electromechanical products have higher and higher requirements for hydraulic directional valves. Specifically, these requirements include: being able to achieve smooth regulation of the hydraulic reversing process; realizing the proportional output of the flow rate of the working port of the directional valve according to the electrical control signal; and being able to automatically adjust and achieve the stability of the working port flow rate when the load of the hydraulic actuator changes and causes changes in the flow rate of the working port.

[0004] However, existing directional control valves have the following defects and shortcomings: (1) During most directional control operations, due to the lack of flow regulation, it is difficult to control the movement speed of actuators (such as hydraulic cylinders and hydraulic motors). In particular, when the load of the actuator changes, it often leads to changes in flow, causing uncontrollable changes in the speed of the actuator. Ultimately, this results in a low level of motion control in the hydraulic system, which does not meet the intelligent control requirements of actuators in high-end hydraulic equipment; (2) Existing hydraulic electromagnetic proportional directional control valves are mostly low- to mid-range products with poor flow control accuracy and are not sensitive to changes in flow caused by load changes. Although some high-end electromagnetic proportional directional control valves have been developed, they are not yet fully functional. Hydraulic proportional directional valves, such as those from foreign brands like "BOSCH" and "Rexroth," use multiple switching valves to establish a hydraulic flow control bridge to precisely control the main valve, achieving precise proportional output of hydraulic oil. However, their complex structure and high requirements for the dynamic response performance of electromagnetic actuators result in high manufacturing costs. They cannot be used in some low-value-added hydraulic intelligent control systems, such as "agricultural machinery electro-hydraulic control systems." 3) Some hydraulic flow servo valves use a nozzle-baffle structure. Although they have high flow control accuracy, their working pressure is often below 20 MPa, making them unsuitable for high-pressure, high-flow-rate applications.

[0005] Therefore, in the field of electro-hydraulic systems, there is an urgent need for a proportional directional valve that has a relatively simple structure, low manufacturing cost, and can achieve precise control of output flow without changes in load. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this application proposes an electro-hydraulic directional flow proportional control valve with load flow compensation. This device can adjust the output flow of the working port according to the control signal. When the load changes and causes the output flow to change, it can automatically adjust the flow to compensate for the load flow change and achieve precise control of the output flow of the working port.

[0007] The technical solution adopted in this invention is as follows:

[0008] An electro-hydraulic directional flow proportional control valve with load flow compensation, comprising:

[0009] Valve body;

[0010] A main valve hole is opened on the valve body, and a main valve core is set in the middle of the main valve hole. A centering spring is set at both ends of the main valve core.

[0011] Two pilot valve sleeve holes are opened on the valve body, and the two pilot valve sleeve holes are arranged parallel to the main valve hole; in each pilot valve sleeve hole, from the inside to the outside, a pilot valve spring, a flow feedback piston, a pilot valve, a force transmission piston, and a proportional electromagnet are arranged in sequence; both pilot valve sleeve holes are connected to the working oil port through oil passages.

[0012] A first recess is made in the middle of the valve body, and a second and a third recess are set outward from both sides of the first recess. The first recess is connected to the oil inlet through an oil passage, and the first recess is connected to the side of the force-transmitting piston in the pilot valve sleeve hole on the same side through a control oil passage.

[0013] Both second sinks are connected to the side where the flow feedback piston is located in the pilot valve sleeve hole on the same side through oil passages;

[0014] The two third settling tanks are connected by a return oil channel, which is also connected to the return oil port.

[0015] Two drain valve holes are provided on the valve body. The drain valve holes are connected to the drain port. The drain valve holes are connected to the main valve hole through the return oil passage. The drain valve holes are connected to the pilot valve sleeve hole through the pilot oil passage. The drain valve holes are equipped with a drain valve spring and a drain valve core.

[0016] Furthermore, the main valve core is a rotating body, and the main valve core includes three rotating shoulders connected in sequence. The rotating shoulders are cylindrical, and each rotating shoulder has an oil hole opened radially. An inner oil hole is opened axially inside the main valve core, and the inner oil hole connects to the oil holes on the three rotating shoulders.

[0017] Furthermore, the pilot valve is connected to a force transmission piston and a flow feedback piston at its two ends, respectively. The flow feedback piston is provided with several through holes arranged along the axial direction. The effective oil contact area of ​​the force transmission piston and the effective oil contact area of ​​the flow feedback piston are equal.

[0018] Furthermore, preload screws are installed at both ends of the main valve hole, and the preload screws are threaded onto both ends of the main valve core hole of the valve body; by adjusting the screw-in position of the preload screws on both sides, the preload force of the centering springs at both ends of the main valve core is adjusted so that the main valve core is in the middle position of the main valve core hole.

[0019] Furthermore, the pilot valve is equipped with a pilot valve sleeve, which is fixed inside the pilot valve sleeve hole of the valve body, and the pilot valve has a degree of freedom of movement relative to the left pilot valve sleeve.

[0020] Furthermore, the proportional electromagnet is fixed to the outer end face of the pilot valve sleeve hole of the valve body. The proportional electromagnet push rod of the proportional electromagnet is in contact with the end face of the force transmission piston of the pilot valve. The pilot valve spring is installed in the pilot valve sleeve hole, with one end in contact with the end face of the flow feedback piston of the pilot valve and the other end in contact with the bottom end face of the pilot valve sleeve hole. Under the action of the pilot valve spring preload, the pilot valve is in the closed state.

[0021] Furthermore, an oil drain valve core and an oil drain spring are installed sequentially from the inside to the drain port in the oil drain valve hole.

[0022] Furthermore, a one-way valve for the return oil port is installed in the connecting oil passage between the return oil passage and the return oil port.

[0023] Furthermore, the direction of the return oil check valve is as follows: it is open from the return oil passage of the valve body to the return oil port of the valve body, and closed from the return oil port to the return oil passage.

[0024] Furthermore, the oil inlet and oil outlet are connected to the oil tank via oil passages, and the working oil port is connected to the hydraulic cylinder via oil passages.

[0025] The beneficial effects of this invention are:

[0026] (1) The electro-hydraulic directional flow proportional control valve with load flow compensation designed in this invention drives the pilot valve to open by the thrust of the proportional electromagnets on both sides, which can control the oil outlet direction of the working port of the control valve; then, by proportionally controlling the thrust of the proportional electromagnets on both sides, the opening of the pilot valve is adjusted, thereby adjusting the hydraulic flow output of the working port; when the load changes and causes the output flow of the working port to change, the pressure drop at both ends of the flow feedback piston changes, and the thrust of the flow piston, the spring force of the pilot valve and the thrust of the electromagnet reach displacement balance again, thereby adjusting the opening of the pilot valve, so that the opening of the pilot valve changes inversely proportional to the load, thereby automatically adjusting the output flow through the pilot valve and the working port, achieving the purpose of compensating for load flow changes, and realizing precise control of the output flow of the working port; it can meet the needs of intelligent control of the actuators of existing high-end hydraulic equipment.

[0027] (2) In this application, through the coordinated operation of the left and right pilot valves, the left and right pilot valve springs, and the flow feedback pistons on both sides, when the flow rate changes due to load changes at the oil outlet, the flow feedback piston adjusts the opening of the pilot valve based on its sensitivity to flow rate, thereby compensating for the output flow rate at the working oil outlet and maintaining the stability of the oil outlet flow rate. Compared with the flow control bridge circuit built by multiple switching valves in high-end foreign electro-hydraulic proportional valves, the core components of this invention are only the flow feedback piston and the pilot valve. The structure of the core flow control component is simple, easy to manufacture, and reduces processing costs. The design of the flow compensation mechanism of the electro-hydraulic proportional valve is simpler than that of existing high-end electro-hydraulic proportional valves. It can be used in domestic low-value-added hydraulic intelligent control equipment.

[0028] (3) Since the main valve core, main valve bore of the valve body, main valve bore groove, flow feedback pistons on both sides, and pilot valve springs of this application have no design size limitations, the proportional electromagnet indirectly controls the hydraulic oil flow through the working port by controlling the pilot hydraulic oil to push the main valve core displacement. This structure can meet the requirements of high-pressure control in hydraulic systems. The main valve core boss and the main valve bore groove can be designed to meet the requirements of large flow hydraulic oil output. Therefore, the electro-hydraulic directional flow proportional control valve designed in this invention can well adapt to the high-pressure and high-flow working conditions of hydraulic control systems. Attached Figure Description

[0029] Figure 1 This is a structural diagram of an electro-hydraulic directional flow proportional control valve with load flow compensation.

[0030] Figure 2 This is a schematic diagram of the valve body structure.

[0031] Figure 3 This is a structural diagram of the left pilot valve.

[0032] Figure 4 This is a structural diagram of the right pilot valve.

[0033] Figure 5 This is a structural diagram of the main valve core.

[0034] Figure 6 This is a schematic diagram of the oil return working principle from port P to port O.

[0035] Figure 7 This is a schematic diagram of the oil return working principle from port P to port A.

[0036] Figure 8 This is a schematic diagram of the oil return working principle from port P to port B.

[0037] Figure 9 This is a schematic diagram of the electro-hydraulic directional flow proportional control valve designed in this application applied to the uniform speed control of a hydraulic cylinder.

[0038] In the diagram, 1. Left proportional electromagnet, 2. Left proportional electromagnet push rod, 3. Left force transmission piston, 4. Left pilot valve sleeve, 5. Left pilot valve, 6. Left flow feedback piston, 7. Left pilot valve spring, 8. Control oil passage, 9. Right pilot valve spring, 10. Right flow feedback piston, 11. Right pilot valve, 12. Right pilot valve sleeve, 13. Right force transmission piston, 14. Right proportional electromagnet push rod, 15. Right proportional electromagnet, 16. Right pilot oil passage, 17. Right drain port, 18. Right drain valve spring, 19. Right drain valve core, 20. Right return oil passage, 21. Right preload screw, 22. Right centering spring, 23. Working... 24. Oil port A, 25. Oil return passage, 26. Oil inlet P, 27. Oil return port O, 28. Oil return port check valve, 29. Working oil port B, 30. Check valve mounting groove, 31. Valve body, 32. Main valve core, 33. Left centering spring, 34. Left preload screw, 35. Left return passage, 36. Left drain valve core, 37. Left drain valve spring, 38. Left pilot passage, 49. Right pilot valve sleeve hole, 40. Right drain valve hole, 41. Main valve hole, 42. Left drain valve hole, 43. Left pilot valve sleeve hole, 44. Main valve core inner oil hole, 45. Hydraulic pump, 46. Oil tank, 47. Hydraulic cylinder. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0040] This application discloses a structure for an electro-hydraulic directional flow proportional control valve with load flow compensation, as shown below. Figure 1-5 As shown, it includes a valve body 30; a main valve hole 41 is opened along the horizontal axis inside the valve body 30, and combined with... Figure 2 As shown, a first sink groove (hereinafter referred to as sink groove P) is opened in the middle part of the main valve hole 41. With the vertical center line of sink groove P as the axis, a second sink groove and a third sink groove are set outward from both sides of sink groove P. The second sink groove is referred to as sink groove B1 and sink groove A1, and the third sink groove is referred to as sink groove O2 and sink groove O1.

[0041] A main valve core 25 is installed inside the main valve hole 41. The structure of the main valve core 25 is as follows: Figure 5 As shown: The main valve core 25 is a rotating body, which includes three rotating shoulders connected in sequence. The rotating shoulders are cylindrical. Each of the three rotating shoulders has a through oil hole in the radial direction, and the oil hole is located in the middle of the rotating shoulder. The main valve core 25 also has an inner oil hole 44 in the axial direction, which penetrates the three rotating shoulders and connects the oil holes on the three rotating shoulders.

[0042] A left pilot valve sleeve hole 43 and a right pilot valve sleeve hole 39 are also provided on the valve body 30. The left pilot valve sleeve hole 43 and the right pilot valve sleeve hole 39 are symmetrical about the center line of the vertical direction of the sink P. A left pilot valve spring 7 and a left pilot valve 5 are arranged sequentially from the inside to the outside in the left pilot valve sleeve hole 43. A left proportional electromagnet 1 is provided at the end of the left pilot valve sleeve hole 43. More specifically, in conjunction with the attached... Figure 3 The schematic diagram of the left pilot valve shows that the two ends of the left pilot valve 5 are connected to the left force transmission piston 3 and the left flow feedback piston 6, respectively. The left flow feedback piston 6 has several through holes. The effective oil contact area of ​​the M surface of the left force transmission piston 3 is equal to the effective oil contact area of ​​the N surface of the left flow feedback piston 6. The left pilot valve 5 is also equipped with a left pilot valve sleeve 4. The left pilot valve spring 7 is disposed between the left flow feedback piston 6 and the inner wall of the left pilot valve sleeve hole 43. The left force transmission piston 3 is in contact with the left proportional electromagnet push rod 2 of the left proportional electromagnet 1.

[0043] Similarly, the structure of the right pilot valve 11 is as follows: Figure 4 As shown, the right pilot valve 11 is connected to the right force transmission piston 13 and the right flow feedback piston 10 at its two ends, respectively. The right flow feedback piston has several through holes. The effective oil contact area of ​​the M surface of the right force transmission piston 13 is equal to the effective oil contact area of ​​the N surface of the right flow feedback piston 10. The right pilot valve 11 is also equipped with a right pilot valve sleeve 12. The right pilot valve spring 9 is disposed between the right flow feedback piston 10 and the inner wall of the right pilot valve sleeve hole 39. The right force transmission piston 13 is in contact with the right proportional electromagnet push rod 14 of the right proportional electromagnet 15.

[0044] The settling tanks O1 and O2 are connected by the return oil passage 24; the return oil passage 24 is connected to the return port O 26 through the return oil check valve groove 29; the settling tank P and the inlet port P 25 are connected by the oil passage; the settling tank P is connected to the left pilot valve sleeve hole 43 and the right pilot valve sleeve hole 39 through the control oil passage 8 respectively; the working port A 23 is connected to the right pilot valve sleeve hole 39 through the oil passage; the working port B 28 is connected to the left pilot valve sleeve hole 43 through the oil passage; the left pilot valve sleeve hole 43 is connected to the main valve core hole 41 and the left drain valve hole 42 through the left pilot oil passage 38; the right pilot valve sleeve hole 39 is connected to the main valve core hole 41 and the right drain valve hole 40 through the right pilot oil passage 16.

[0045] The connection and assembly of the various components of the inventive device are as follows: Figure 1 and Figure 2 As shown:

[0046] The left pilot valve sleeve 4 is fixed in the left pilot valve sleeve hole 43 of the valve body 30, and the right pilot valve sleeve 12 is fixed in the right pilot valve sleeve hole 39 of the valve body 30; the left pilot valve 5 is installed in the left pilot valve sleeve 4, and the left pilot valve 5 has a degree of freedom of movement relative to the left pilot valve sleeve 4; the left proportional electromagnet 1 is fixed on the outer end face of the left pilot valve sleeve hole 43 of the valve body 30, and the left proportional electromagnet push rod 2 of the left proportional electromagnet 1 is in contact with the end face of the left force transmission piston 3 of the left pilot valve 5; the left pilot valve spring 7 is installed in the left pilot valve sleeve hole 43, one end of which is in contact with the end face of the flow feedback piston 6 of the left pilot valve 5, and the other end is in contact with the bottom end face of the left pilot valve sleeve hole 43; the left pilot valve spring 7 Under the action of preload, the left pilot valve 5 is in the closed state; the right pilot valve 11 is installed in the right pilot valve sleeve 12, and the right pilot valve 11 has a degree of freedom of movement relative to the right pilot valve sleeve 12; the right proportional electromagnet 15 is fixed to the outer end face of the right pilot valve sleeve hole 39 of the valve body 30, the right proportional electromagnet push rod 14 of the right proportional electromagnet 15 is in contact with the end face of the right force transmission piston 13 of the right pilot valve 11, and the right pilot valve spring 9 is installed in the right pilot valve sleeve hole 39, one end of which is in contact with the end face of the flow feedback piston 10 of the right pilot valve 11, and the other end is in contact with the bottom end face of the right pilot valve sleeve hole 39; under the action of the preload of the right pilot valve spring 9, the right pilot valve 11 is in the closed state.

[0047] like Figure 1 and Figure 2 As shown, the left drain valve core 35 and the left drain spring 36 are installed in the left drain valve hole 42 of the valve body 30; the right drain valve core 19 and the right drain spring 18 are installed in the right drain valve hole 40 of the valve body 30. The main valve core 31, the right centering spring 22, and the left centering spring 32 are installed at both ends of the main valve core 31; the right preload screw 21 and the left preload screw 33 are respectively installed at both ends of the main valve core hole 41 of the valve body 30 by threads; by adjusting the screw-in position of the left preload screw 33 and the right preload screw 21, the preload force of the left centering spring 32 and the right centering spring 22 is adjusted so that the main valve core 31 is in the middle position of the main valve core hole 41.

[0048] The return oil check valve 27 is installed in the check valve mounting groove 29 of the valve body 30. The direction of the return oil check valve 27 is: it is connected from the return oil passage 24 of the valve body 30 to the return oil port O 26 of the valve body 30, and it is cut off from the return oil port O 26 to the return oil passage 24.

[0049] The following description, based on the working principle of the electro-hydraulic reversing flow proportional control valve designed in this invention, further illustrates the electro-hydraulic reversing flow proportional control valve of this invention:

[0050] (1) Working principle diagram of oil return from P port to O port

[0051] Left proportional electromagnet 1 and right proportional electromagnet 15 are not energized. Oil enters through oil inlet P25 and flows out through oil return port O26. (Details follow...) Figure 6 As shown, when the left proportional electromagnet 1 and the right proportional electromagnet 15 are not energized, neither the left proportional electromagnet push rod 2 nor the right proportional electromagnet push rod 14 generates thrust. At this time, both the left pilot valve 5 and the right pilot valve 11 are closed. The pressurized oil from the inlet P 25 passes through the valve body groove P and enters the control oil circuit 8, but cannot enter the left side cavity of the main valve core 31 through the left pilot valve 5 and the left pilot oil passage 38; at the same time, the oil in the control oil circuit 8 cannot enter the right side cavity of the main valve core 31 through the right pilot valve 11 and the right pilot oil passage 16; therefore, under the action of the left centering spring 32 and the right centering spring 22, the main valve core 31 is always in the middle working position. When the main valve core 31 is in the middle working position, the groove P on the valve body 30 is connected to the oil hole on the shoulder of the main valve core 31. The pressure oil at the inlet P 25 is connected to the grooves O1 and O2 of the valve body through the inner oil hole 44 of the main valve core 31. Therefore, the pressure oil at the inlet P flows out through the groove P of the valve body, the inner oil hole 44 of the main valve core 31, the grooves O1 and O2 of the valve body, and the return oil check valve 27, and exits through the return oil port O 26. The grooves P, B1, and A1 on the valve body 30 are closed by the shoulder on the main valve core 31, that is, the grooves P, B1, and A1 are not connected. Therefore, when the left proportional electromagnet 1 and the right proportional electromagnet 15 are not energized, when the pressure oil enters from the inlet P, all the oil flows out from the return oil port O 26 of the valve body 30.

[0052] (2) Working principle diagram of oil return from port P to port A

[0053] When the left proportional electromagnet 1 is energized, the right proportional electromagnet 15 is de-energized, oil enters through inlet P25, and oil flows out through working port B28 with a stable flow rate. Figure 7As shown, when the left proportional electromagnet 1 is energized and the right proportional electromagnet 15 is de-energized, the left proportional electromagnet push rod 2 generates a thrust on the left pilot valve 5. When the thrust is greater than the preload of the left pilot valve spring 7, the left pilot valve 5 opens. The pressure oil from the inlet P 25 enters the control oil passage 8 through the groove P of the valve body 30. Then, the pressure oil enters the oil chamber on the left side of the main valve core 31 through the left pilot valve 5. Due to the pressure loss of the left return oil passage 34, the left drain valve core 35 overcomes the preload of the left drain valve spring 36, moves to the left, and blocks the oil passage from the left return oil passage 34 to the left drain port 37. At this time, the pressure in the oil chamber on the left side of the main valve core 31 increases, pushing the main valve core 31 to overcome the preload of the right centering spring 22 and generate a displacement to the right, so that the groove P and groove B1 of the valve body 30 are connected, and the groove A1 and groove O1 are connected. 25. A portion of the pressurized oil flows out through the working port B28 via the oil passage through the P groove, B1 groove, and the hole on the left flow feedback piston 6 of the valve body 30. Simultaneously, due to the rightward movement of the main valve core 31, a portion of the oil port 44 on the middle shoulder of the main valve core 31 is blocked by the main valve hole, resulting in an increase in the pressure difference between the groove P and the return port O26, thus reducing the amount of oil flowing from the groove P to the return port O26. If the hydraulic actuator has a return oil connection, the return oil can be connected to the working port A23. The return oil flows through the working port A23, the oil passage of the valve body, and then through the small hole on the right flow feedback piston 10 into the groove A1, flowing out through the groove O1, the return oil passage 24, the return oil check valve 27, and the return port 26.

[0054] When the oil load pressure at working port B28 increases, the pressure difference between the valve body submersible P and submersible B1 decreases. Since the pressure difference between submersible P and return port O26 remains unchanged, the oil flows from submersible P into return port O26. As the flow rate increases, the flow rate from sink P to sink B1 decreases. Due to the decrease in flow rate through the left flow feedback piston 6, according to the fluid dynamics resistance calculation theory, the pressure loss at both ends of the left flow feedback piston 6 decreases, and the resistance of the left flow feedback piston 6 to the left proportional electromagnetic push rod 2 decreases. Under the condition that the thrust of the left proportional electromagnetic push rod 2 remains unchanged, the left pilot valve spring 7 is further compressed. The opening of the left pilot valve 5 increases, and the pressure difference before and after the left pilot valve 5 decreases. Since the pressure at the oil inlet P remains unchanged, the pressure in the oil chamber on the left side of the main valve core 31 increases, and the thrust of the oil on the main valve core 31 to the right increases, driving the main valve core 31 to move further to the right. This increases the opening of the valve body sink P to B1, further blocking and reducing the opening of the oil hole 44 on the shoulder of the main valve core 31 in sink P. This increases the flow rate from sink P to sink B1 and reduces the flow rate from sink P to the oil hole 44 inside the valve core, thereby stabilizing the oil flow rate of working B23. Conversely, when the oil load pressure at working port B28 decreases, the pressure difference between the sink P and sink B1 increases, the oil output from working port B28 increases, the flow rate through the left flow feedback piston 6 increases, the pressure loss at both ends of the left flow feedback piston 6 increases, and the resistance of the left flow feedback piston 6 to the left proportional electromagnetic push rod 2 increases. Under the condition that the thrust of the left proportional electromagnetic push rod 2 remains unchanged, the left pilot valve spring 6 is further extended, the opening of the left pilot valve 5 decreases, the pressure difference before and after the left pilot valve 5 increases, the pressure in the oil chamber on the left side of the main valve core 31 decreases, the thrust of the oil on the main valve core 31 to the right decreases, the main valve core 31 moves to the left, reducing the opening between the valve body sink P and B1, increasing the opening of the oil hole 44 on the shoulder of the main valve core 31 in sink P, thus reducing the flow rate from sink P to sink B1 and increasing the flow rate from sink P to the oil hole 44 inside the valve core, thereby stabilizing the oil output flow rate of working port B23.

[0055] (3) Working principle diagram of oil return from port P to port B

[0056] Left proportional electromagnet 1 is not energized, right proportional electromagnet 15 is energized, oil enters through inlet P25, and oil flows out through working port A23 with a stable flow rate. For example... Figure 8As shown, when the left proportional electromagnet 1 is not energized, and the right proportional electromagnet 15 is energized, the right proportional electromagnet push rod 14 generates a thrust on the right pilot valve 11; when the thrust is greater than the preload of the right pilot valve spring 9, the right pilot valve 11 opens, and the pressure oil from the inlet P 25 enters the control oil passage 8 through the groove P of the valve body 30. Then, the pressure oil enters the oil chamber on the right side of the main valve core 31 through the right pilot valve 11 and the right pilot oil passage 16. Due to the pressure loss of the right return oil passage 20, the right drain valve core 19 overcomes the preload of the right drain valve spring 18, moves to the right, and blocks the oil passage from the right return oil passage 20 to the right drain port 17; at this time, the pressure in the oil chamber on the right side of the main valve core 31 increases, pushing the main valve core 31 to overcome the preload of the left centering spring (32) and generate a displacement to the left, so that the groove P and groove A1 of the valve body 30 are connected, and the groove B1 and groove O2 are connected; the inlet P 25. A portion of the pressurized oil flows out through the working port A23 via the oil passage through the P groove, A1 groove, and the hole on the right flow feedback piston 10 of the valve body 30. At the same time, due to the leftward movement of the main valve core 31, a portion of the oil port 44 on the middle shoulder of the main valve core 31 is blocked by the main valve hole 41, resulting in an increase in the pressure difference between the groove P and the return port O26, and a decrease in the amount of oil flowing from the groove P to the return port O26. If the hydraulic component has a return oil, the return oil passage is connected to the working port B, and the return oil flows through the working port B, the hole on the left flow feedback piston (6), the groove B, the groove O2, the return oil passage 24, and the return oil check valve 27, and finally flows out through the return port O26.

[0057] When the oil load pressure at working port A23 increases, the pressure difference between the valve body submersible P and submersible A1 decreases. Since the pressure difference between submersible P and return port O26 remains unchanged, the oil flows from submersible P into return port O26. As the flow rate increases, the flow rate from sink P to sink A1 decreases. Due to the decrease in flow rate through the right flow feedback piston 10, according to the fluid dynamics resistance calculation theory, the pressure loss at both ends of the right flow feedback piston 10 decreases, and the resistance of the right flow feedback piston 10 to the right proportional electromagnetic push rod 14 decreases. Under the condition that the thrust of the right proportional electromagnetic push rod 12 remains unchanged, the right pilot valve spring 9 is further compressed, the opening of the right pilot valve 11 increases, and the pressure difference before and after the right pilot valve 11 decreases. Since the pressure at the oil inlet P remains unchanged, the pressure in the oil chamber on the right side of the main valve core 31 increases, and the thrust of the oil on the main valve core 31 to the left increases, driving the main valve core 31 to move further to the left, increasing the opening of the valve body sink P to A1, further blocking and reducing the opening of the oil hole 44 on the shoulder of the main valve core 31 in sink P, thus increasing the flow rate from sink P to sink A1 and reducing the flow rate from sink P to the oil hole 44 inside the valve core, thereby stabilizing the oil flow rate of working A 23. Conversely, when the oil load pressure at working port A23 decreases, the pressure difference between sink P and sink A1 increases, the oil output from working port A23 increases, the flow rate through the right flow feedback piston 10 increases, the pressure loss at both ends of the right flow feedback piston 10 increases, and the resistance of the right flow feedback piston 10 to the left proportional electromagnetic push rod 2 increases. Under the condition that the thrust of the right proportional electromagnetic push rod 14 remains unchanged, the right pilot valve spring 9 is further extended, the opening of the right pilot valve 11 decreases, the pressure difference before and after the right pilot valve 11 increases, the pressure in the oil chamber on the right side of the main valve core 31 decreases, the thrust of the oil on the main valve core 31 to the left decreases, the main valve core 31 moves to the right, reducing the opening from sink P to A1 in the valve body, further increasing the opening of the oil hole 44 on the shoulder of the main valve core 31 in sink P, thus reducing the flow rate from sink P to sink A1 and increasing the flow rate from sink P to the oil hole 44 inside the valve core, thereby stabilizing the oil output flow rate of working port A23.

[0058] Application examples:

[0059] The electro-hydraulic directional flow proportional control valve with load flow compensation described in this invention is applied to the uniform displacement control of a hydraulic cylinder. The purpose is to maintain a uniform piston rod extension speed under varying load conditions during the piston rod extension process. Specific implementation details are as follows: Figure 9 As shown, the oil outlet of the hydraulic pump 45 is connected to the oil inlet P 25 of the device of the present invention, the working oil port A 23 is connected to the rodless chamber oil port of the hydraulic cylinder 47, the working oil port B 28 is connected to the rod chamber of the hydraulic cylinder 47, the return oil port 26 is connected to the hydraulic oil tank 46, and the load on the piston rod of the hydraulic cylinder 47 is F, with the direction shown in the figure.

[0060] The purpose of this application case is to control the piston rod of hydraulic cylinder 47 to extend at a uniform speed using an electro-hydraulic directional flow proportional control valve with load flow compensation.

[0061] Based on the above connections, the left proportional electromagnet 1 is not energized, and current is supplied to the right proportional electromagnet 15. The push rod 14 of the right proportional electromagnet generates a thrust on the right pilot valve 11. When the thrust is greater than the preload of the right pilot valve spring 9, the right pilot valve 11 opens. The pressure oil from the inlet P 25 enters the control oil passage 8 through the groove P of the valve body 30. Then, the pressure oil enters the oil chamber on the right side of the main valve core 31 through the right pilot valve 11 and the right pilot oil passage 16. Due to the pressure loss of the right return oil passage 20, the right drain valve core 19 overcomes the preload of the right drain valve spring 18, moves to the right, and blocks the oil passage from the right return oil passage 20 to the right drain port 17. At this time, the pressure in the oil chamber on the right side of the main valve core 31 increases, pushing the main valve core 31 to overcome the preload of the left centering spring 32 and generate a displacement to the left, so that the groove P and groove A1 of the valve body 30 are connected, and the groove B1 and groove O2 are connected. 25. A portion of the pressurized oil flows out through the working port A23 via the P-slot, A1-slot of the valve body 30, and the hole on the right flow feedback piston 10. The hydraulic oil flowing out from the working port A23 enters the rodless chamber of the hydraulic cylinder 47. The oil in the rod chamber of the hydraulic cylinder 47 flows through the working port B, the hole on the left flow feedback piston 6, slot B, slot O2, return oil passage 24, and return oil check valve 27, finally flowing into the oil tank 46 through the return oil port O26. The piston rod of the hydraulic cylinder 47 extends to the left against the load F.

[0062] When the load F on the piston rod of hydraulic cylinder 47 increases, the oil load pressure at working port A23 rises, and the pressure difference between the valve body submersible P and submersible A1 decreases. This is because the pressure difference between submersible P and the return port O... Since the pressure difference at point 26 remains constant, the flow rate from sink P into return port O26 increases, while the flow rate from sink P into sink A1 decreases. Because the flow rate through the right flow feedback piston 10 decreases, according to fluid dynamics resistance calculation theory, the pressure loss at both ends of the right flow feedback piston 10 decreases, and the resistance of the right flow feedback piston 10 to the right proportional electromagnetic push rod 14 decreases. Under the condition that the thrust of the right proportional electromagnetic push rod 14 remains constant, the right pilot valve spring 9 is further compressed, the opening of the right pilot valve 11 increases, and the pressure difference before and after the right pilot valve 11 decreases. Since the pressure at inlet P remains constant, the pressure in the oil chamber on the right side of the main valve core 31 increases, and the thrust of the oil on the main valve core 31 to the left increases, driving the main valve core 31 to move further to the left. This increases the opening of the valve body from sink P to A1, further obstructing and reducing the opening of the oil hole 44 on the shoulder of the main valve core 31 in sink P. This increases the flow rate from sink P to sink A1 and decreases the flow rate from sink P to the oil hole 44 inside the valve core, thus stabilizing operation. The oil flow rate of 23 achieves the goal of stabilizing the extension speed of the piston rod of hydraulic cylinder 47 under the condition of increased load F.

[0063] Conversely, when the piston rod load F of hydraulic cylinder 47 decreases, the oil load pressure at working port A23 decreases, the pressure difference between sinker P and sinker A1 increases, the oil output from working port A23 increases, the flow rate through the right flow feedback piston 10 increases, the pressure loss at both ends of the right flow feedback piston 10 increases, and the resistance of the right flow feedback piston 10 to the left proportional electromagnetic push rod 2 increases. Under the condition that the thrust of the right proportional electromagnetic push rod 14 remains unchanged, the right pilot valve spring 6 is further extended, the opening of the right pilot valve 11 decreases, the pressure difference before and after the right pilot valve 11 increases, the pressure in the right oil chamber of the main valve core 31 decreases, the thrust of the oil on the main valve core 31 to the left decreases, the main valve core 31 moves to the right, reducing the opening of the valve body sinker P to A1, further increasing the opening of the oil hole 44 on the shoulder of the main valve core 31 in sinker P, thus reducing the flow rate from sinker P to sinker A1 and increasing the flow rate from sinker P to the oil hole 44 inside the valve core, thereby stabilizing the working A23. The oil flow rate of 23; thus, the purpose of controlling the extension speed of the piston rod of hydraulic cylinder 47 to be stable when the piston rod load F decreases.

[0064] The above embodiments are only used to illustrate the design concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications made based on the principles and design ideas disclosed in the present invention are within the protection scope of the present invention.

Claims

1. An electro-hydraulic reversing flow proportional control valve with load flow compensation, characterized in that, Comprise: Valve body (30); The main valve hole (41) is opened on the valve body (30), and the main valve core (31) is arranged at the middle position of the main valve hole (41), and the both ends of the main valve core (31) are respectively provided with centering springs; Two pilot valve sleeve holes are opened on the valve body (30), and the two pilot valve sleeve holes are arranged in parallel with the main valve hole (41); in each pilot valve sleeve hole, a pilot valve spring, a flow feedback piston, a pilot valve, a force transmission piston and a proportional solenoid are sequentially arranged from inside to outside; the two pilot valve sleeve holes are connected with the working oil port through an oil channel; A first sink is opened at the middle position of the valve body (30), and a second sink and a third sink are sequentially arranged outward on both sides of the first sink; the first sink is connected with the oil inlet through an oil channel, and the first sink is respectively communicated with the side of the force transmission piston in the same side pilot valve sleeve hole through a control oil channel (8); The two second sinks are respectively communicated with the side of the flow feedback piston in the same side pilot valve sleeve hole through an oil channel; The two third sinks are communicated through a return oil channel (24), and the return oil channel (24) is also connected with the return oil port; Two oil drain valve holes are opened on the valve body (30), the oil drain valve holes are connected with the oil drain port, the oil drain valve holes are communicated with the main valve hole (41) through a return oil channel, the oil drain valve holes are communicated with the pilot valve sleeve hole through a pilot oil channel; the oil drain valve holes are provided with an oil drain valve spring and an oil drain valve core.

2. An electro-hydraulic reversing flow proportional control valve with load flow compensation according to claim 1, characterized in that, The main valve core (31) is a rotary body, and the main valve core (31) comprises three rotary shoulders which are sequentially connected, the rotary shoulders are cylindrical, oil holes are opened on each rotary shoulder in the radial direction, an inner oil hole (44) is opened in the main valve core (31) in the axial direction, and the inner oil hole (44) communicates the oil holes on the three rotary shoulders.

3. An electro-hydraulic reversing flow proportional control valve with load flow compensation according to claim 1, characterized in that, The both ends of the main valve hole (41) are respectively provided with pre-tightening screws, the pre-tightening screws are threadedly installed at the both ends of the main valve hole (41) of the valve body (30); by adjusting the screwing positions of the pre-tightening screws on both sides, the pre-tightening force of the centering springs at the both ends of the main valve core (31) is adjusted, so that the main valve core (31) is located at the middle position of the main valve hole (41).

4. An electro-hydraulic reversing flow proportional control valve with load flow compensation according to claim 1, characterized in that, The both ends of the pilot valve are respectively connected with the force transmission piston and the flow feedback piston, the flow feedback piston is provided with a plurality of through holes arranged in the axial direction, and the effective oil liquid acting area of the force transmission piston is equal to the effective oil liquid acting area of the flow feedback piston.

5. An electro-hydraulic reversing flow proportional control valve with load flow compensation according to claim 4, characterized in that, The pilot valve is provided with a pilot valve sleeve, the pilot valve sleeve is fixed in the pilot valve sleeve hole of the valve body (30), and the pilot valve has a moving degree relative to the left pilot valve sleeve.

6. An electro-hydraulic commutated flow proportional control valve with load flow compensation according to any one of claims 1-5, characterized in that, The proportional solenoid is fixed on the outer end surface of the pilot valve sleeve hole of the valve body (30), the proportional solenoid push rod of the proportional solenoid is in contact with the end surface of the force transmission piston of the pilot valve, the pilot valve spring is installed in the pilot valve sleeve hole, one end of the pilot valve spring is in contact with the end surface of the flow feedback piston of the pilot valve, and the other end of the pilot valve spring is in contact with the bottom end surface of the pilot valve sleeve hole; under the action of the pre-tightening force of the pilot valve spring, the pilot valve is in a closed state.

7. An electro-hydraulic reversing flow proportional control valve with load flow compensation according to claim 6, characterized in that, The oil drain valve core and the oil drain spring are sequentially installed in the oil drain valve hole from the inside to the oil drain port.

8. An electro-hydraulic commutated flow proportional control valve with load flow compensation according to claim 6, characterized in that, A return oil port one-way valve (27) is arranged in the connecting oil channel between the return oil channel (24) and the return oil port.

9. An electro-hydraulic reversing flow proportional control valve with load flow compensation according to claim 8, characterized in that, The installation direction of the oil return port one-way valve (27) is: from the oil return oil passage (24) of the valve body (30) to the oil return port of the valve body (30) for conduction, and from the oil return port to the oil return oil passage (24) for cut-off.

10. An electro-hydraulic reversing flow proportional control valve with load flow compensation according to claim 6, characterized in that, The oil inlet port and the oil return port are connected with the oil tank (46) through an oil passage, and the working oil port is connected with the hydraulic cylinder (47) through an oil passage.

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