A large flow digital valve of motor control hydraulic servo drive and working method

Abstract

The application discloses a large-flow digital valve of motor control hydraulic servo driving and a working method, and belongs to the technical field of electro-hydraulic proportional valves. The large-flow digital valve comprises a pilot hydraulic servo mechanism, a reversing valve body and a control motor. The pilot hydraulic servo mechanism comprises a core shaft and a hydraulic servo pilot unit. The core shaft is provided with high / low pressure flow distribution holes. The hydraulic servo unit is provided with a servo through-flow groove. The hydraulic servo pilot unit is fixedly connected with a main reversing valve core. The control motor drives the core shaft to rotate. The main reversing valve core is driven to move through the hydraulic servo meter. The motor rotation angle is proportional to the displacement of the main reversing valve core. The digital valve combines the advantages of motor control and hydraulic driving, has the advantages of high control precision, quick response, easy control and controllable cost, and meets the intelligent development demand of the large-flow digital valve.

Description

Technical Field

[0001] This invention relates to electro-hydraulic proportional valves in the field of fluid transmission and control, and particularly to an electro-hydraulic proportional digital directional valve. Background Technology

[0002] Electro-hydraulic proportional valves are the core components of electro-hydraulic control systems, serving as a bridge between low-power electrical control and high-power hydraulic transmission. High-flow electro-hydraulic proportional valves often use proportional electromagnets as pilot-stage drive elements. This approach offers high reliability and low cost, but suffers from poor control accuracy, slow response, and low repeatability. To improve control performance, closed-loop position feedback is often required, leading to increased costs and reduced stability and environmental adaptability. Meanwhile, high-precision, high-frequency servo valves are expensive, have poor contamination resistance, and high maintenance costs, making them unsuitable for the complex and cost-sensitive demands of current intelligent development.

[0003] With the development of digital hydraulics, motor-driven hydraulic components have developed rapidly. Direct motor drive is the main trend in the development of electro-hydraulic digital valves, which has the advantages of simple structure, easy control, high frequency response and high reliability. However, due to the limitation of driving force, it cannot be directly used in high-pressure and high-flow digital valves. Therefore, it is urgent to develop a high-performance, cost-controllable high-flow electro-hydraulic proportional digital valve with motor-controlled hydraulic servo drive to meet the intelligent development needs of high-flow digital valves. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a high-flow digital valve and its operating method that is controlled by a motor and driven by a hydraulic servo. By using digital motor control and hydraulic servo drive of the valve core, it achieves precise proportional control of a three-position four-way high-flow digital directional valve, which has the advantages of precise control, fast response, controllable cost, and easy control.

[0005] To achieve the above objectives, this invention discloses a high-flow digital valve driven by a motor-controlled hydraulic servo, comprising a directional valve body, within which a pilot hydraulic servo mechanism is provided, driven by a control motor; the directional valve body includes a valve body, within which a slidable hollow main directional valve core is provided, and within the valve body are a main valve high-pressure oil passage P, a main valve low-pressure return oil passage T, and working oil passages A and B; the pilot hydraulic servo mechanism includes a hydraulic servo mechanism disposed within the main directional valve core, the hydraulic servo mechanism including a hydraulic servo unit fixed at the middle position within the main directional valve core, the hydraulic servo unit having a spindle driven by a control motor; the hydraulic servo mechanism controls the flow rate and direction of the oil in the digital valve by driving the main directional valve core to move.

[0006] Furthermore, a left end cap is provided on the left side of the valve body via end cap screws, and a middle cover is provided on the right side of the valve body; a control motor is located on the right side of the valve body and is fixedly connected by bolts, used to drive the pilot hydraulic servo mechanism, and the control motor includes a motor housing located on the right side of the middle cover, and a motor rotor is provided inside the motor housing.

[0007] Furthermore, a spring top ring I is provided between the left side of the main directional valve core and the left end cover via a limiting top ring I, and a spring top ring II is provided between the right side of the main directional valve core and the middle cover via a limiting top ring II; the hydraulic servo unit inside the main directional valve core controls the flow rate and direction of the oil in the digital valve by driving the main directional valve core to move.

[0008] Furthermore, the pilot hydraulic servo mechanism includes a spindle connected to the motor at its right end. The spindle rotates within the inner hole of the hydraulic servo unit under the control of the motor. The hydraulic servo unit has two working chamber units, I and II, respectively, fixedly connected to the main directional valve core via limiting shafts. Working chamber unit I forms a left working chamber j with the hydraulic servo unit, and working chamber unit II forms a right working chamber k with the hydraulic servo unit. Working chamber unit I has a working chamber limiting unit I on its left side, constrained by the limiting top ring I along with the valve core. Working chamber unit II has a working chamber limiting unit II on its right side, constrained by the limiting top ring II along with the valve core. A constant low-pressure chamber m with return oil is formed within working chamber limiting unit I, and a constant low-pressure chamber L with return oil is formed within working chamber limiting unit II.

[0009] Furthermore, the mandrel has distribution grooves a and f at opposite positions on the middle sidewall, which are connected to the axial through hole. An axial flow channel is provided inside the mandrel, connecting the constant low-pressure chamber m and the constant low-pressure chamber L. A stepped inner through hole is provided in the middle of the axial flow channel to form a low-pressure flow channel e. Low-pressure flow channel e is located on the outer cylindrical surface of the mandrel and has low-pressure distribution holes d and g that are connected to the low-pressure flow channel e and distribution groove f. It also has high-pressure distribution holes b and i that are connected to the high-pressure oil source of the main valve high-pressure oil passage P via distribution groove a. The main reversing valve core has a transition hole, within which is a high-pressure flow channel n connected to the main valve high-pressure oil passage P. High-pressure flow channel n is connected to the high-pressure distribution holes b and i of the mandrel. Low-pressure distribution holes d and g are connected to the main valve low-pressure return oil passage T.

[0010] Furthermore, the inner side of the hydraulic servo pilot unit is provided with two obliquely arranged servo flow channels c and h. The servo flow channel c on the hydraulic servo unit is only connected to the right working chamber k and cooperates with the high-pressure distribution hole b and the low-pressure distribution hole d of the spindle 10; the servo flow channel h is only connected to the left working chamber j and cooperates with the high-pressure distribution hole i and the low-pressure distribution hole g.

[0011] Furthermore, when the control motor drives the spindle to rotate counterclockwise, the oblique servo flow channel c connects with the high-pressure distribution hole b to form a high-pressure throttling orifice, and the oblique servo flow channel h connects with the low-pressure distribution hole g to form a low-pressure throttling orifice. This causes the pressure in the right acting chamber k to increase and the pressure in the left acting chamber j to decrease. The pressure difference between the right acting chamber k and the left acting chamber j pushes the hydraulic servo pilot unit to move to the right, while the high-pressure / low-pressure throttling orifice gradually decreases, thereby controlling the displacement of the main valve core. When the control motor drives the spindle to rotate clockwise... When rotating, the oblique servo flow channel c connects with the low-pressure distribution hole d to form a low-pressure throttling orifice, and the oblique servo flow channel h connects with the high-pressure distribution hole i to form a high-pressure throttling orifice. This causes the pressure in the right working chamber k to decrease and the pressure in the left working chamber j to increase. The pressure difference between the right working chamber k and the left working chamber j pushes the hydraulic servo pilot unit to move to the left, while the high-pressure / low-pressure throttling orifice gradually decreases, thereby controlling the displacement of the main valve core. This forms an electro-hydraulic servo screw drive, controlling the motor's rotation angle to be proportional to the displacement of the main valve core.

[0012] Furthermore, the main directional valve core, hydraulic servo unit, working chamber unit I, working chamber unit II, working chamber limiting unit I, working chamber limiting unit II, transition hole, limiting top ring I, and limiting top ring II are fixedly connected and assembled into one unit, which can slide along the axial direction of the main directional valve core. The two ends of the main directional valve core cooperate with the centering spring I and centering spring II through spring top ring I and spring top ring II and limiting top ring I and limiting top ring II, respectively, to achieve centering and reset.

[0013] Furthermore, the high-pressure oil source enters the distribution groove a of the mandrel through the high-pressure flow channel n in the transition hole of the main valve of the high-flow electro-hydraulic proportional digital valve, and then connects to the high-pressure distribution hole b and the high-pressure distribution hole i; the low-pressure return oil enters the low-pressure flow channel e in the mandrel through the low-pressure distribution hole d and the low-pressure distribution hole g, and finally connects to the return oil port T of the main valve through the constant low-pressure chamber m, the constant low-pressure chamber L and the flow passage hole on the main reversing valve core.

[0014] A method for operating a high-flow digital valve controlled by a motor and driven by a hydraulic servo includes the following steps: When the control motor is reset, the servo flow channel c and servo flow channel h are not connected to the high-pressure distribution hole b and high-pressure distribution hole i or the low-pressure distribution hole d and low-pressure distribution hole g, and the main reversing valve core is in the neutral position. When the control motor drives the spindle to rotate counterclockwise by a set angle, the spindle rotation connects the servo flow channel c with the high-pressure distribution hole b and the servo flow channel h with the low-pressure distribution hole g. High-pressure oil enters from the high-pressure oil passage P of the main valve, enters the distribution channel a of the spindle through the high-pressure flow channel n, and connects with the high-pressure distribution hole b. Then, it enters the right working chamber k through the servo flow channel c. At the same time, the oil in the left working chamber j connects with the low-pressure distribution hole g through the servo flow channel h, and connects with the low-pressure return oil passage T of the main valve through the low-pressure flow channel e and the constant low-pressure chamber m. The pressure difference in the two working chambers drives the working chamber unit to move the main reversing valve core 9 to the right axial direction. The movement of the main reversing valve core 9 causes the openings of the distribution holes and servo flow channels to gradually decrease until they are closed. The main reversing valve core 9 stops at the corresponding position, realizing the connection between the high-pressure oil passage P of the main valve and the working oil passage A, and the connection between the working oil passage B and the low-pressure return oil passage T of the main valve. The size of the valve core opening is controlled by the spindle rotation angle ratio. When the control motor drives the spindle to rotate clockwise and counterclockwise by a set angle, the spindle rotation connects the servo flow channel c with the low-pressure distribution hole d, and the servo flow channel h with the high-pressure distribution hole i. High-pressure oil enters from the high-pressure oil passage P of the main valve, enters the distribution channel a of the spindle 10 through the high-pressure flow channel n, and connects with the high-pressure distribution hole i. Then, it enters the left working chamber j through the servo flow channel h. At the same time, the oil in the right working chamber k connects with the low-pressure distribution hole d through the servo flow channel h, and connects with the low-pressure return oil passage T of the main valve through the low-pressure flow channel e and the constant low-pressure chamber m. The pressure difference in the two working chambers drives the working chamber unit to move the main reversing valve core to the left axial direction. The movement of the main reversing valve core gradually reduces the opening of the distribution hole and the servo flow channel until they are closed. The main reversing valve core stops at the corresponding position, realizing the connection between the high-pressure oil passage P of the main valve and the working oil passage B, and the connection between the working oil passage A and the low-pressure return oil passage T of the main valve. The size of the valve core opening is controlled by the spindle rotation angle ratio. The hydraulic servo drive controls the rotation angle of the control motor spindle to correspond proportionally with the displacement of the main directional valve core, thereby achieving precise proportional control of the three-position four-way high-flow digital directional valve.

[0015] Beneficial effects: The large-flow electro-hydraulic proportional digital valve with motor control and hydraulic servo drive proposed in this invention uses motor digital control and hydraulic drive valve core to control the main directional valve core, realizing precise proportional control of the three-position four-way large-flow digital directional valve; this invention features a double-acting chamber design, which improves pressure gain and has the advantages of fast response, high control accuracy, and large thrust; this invention eliminates the need for displacement sensors and complex control systems, balancing the cost and performance of large-flow electro-hydraulic proportional valves; this invention has a symmetrical overall structure, with the rotating parts having a centrally symmetrical structure, no eccentric torque during rotation, and small mass of the rotating parts, resulting in advantages such as low rotational inertia, reasonable structural fit, and simple assembly. Attached Figure Description

[0016] Figure 1This is a schematic diagram of the structure of a high-flow digital valve controlled by a motor and driven by a hydraulic servo, according to the present invention.

[0017] Figure 2 This is a schematic diagram of the overall appearance of the high-flow digital valve driven by a motor-controlled hydraulic servo according to the present invention.

[0018] Figure 3 This is a schematic diagram of the mandrel structure in an embodiment of the present invention.

[0019] Figure 4 yes Figure 3 AA cross-section view.

[0020] Figure 5 yes Figure 3 BB cross-section.

[0021] Figure 6 This is a schematic diagram of the hydraulic servo unit in an embodiment of the present invention.

[0022] Figure 7 This is a plan view of the pilot hydraulic servo mechanism in an embodiment of the present invention.

[0023] In the diagram: 1. End cap screw, 2. Left end cap, 3. Spring top ring I, 4. Limiting top ring I, 5. Actuating chamber limiting unit I, 6. Valve body, 7. Transition hole, 8. Hydraulic servo unit, 9. Valve core, 10. Limiting top ring II, 11. Spring top ring II, 12. Motor housing, 13. Intermediate cover, 14. Motor rotor, 15. Centering spring I, 16. Actuating chamber limiting unit II, 17. Actuating chamber unit I, 18. Sealing ring, 19. Actuating chamber unit II, 20. Top ring screw, 21. Centering spring II, 22. Detailed Implementation

[0024] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0025] like Figure 1 , Figure 2 As shown, this invention discloses a high-flow digital valve driven by a motor-controlled hydraulic servo, comprising a pilot hydraulic servo mechanism disposed within the main body of a directional valve, and a control motor for driving the pilot hydraulic servo mechanism; the main body of the directional valve includes a valve body 6, within which a slidable hollow main directional valve core 9 is disposed, and pressure oil passage P, return oil passage T, and working oil passages A and B are disposed within the valve body 6; the pilot hydraulic servo mechanism is disposed within the main directional valve core 9, and includes a hydraulic servo unit 8 fixedly connected to the main directional valve core 9; the hydraulic servo unit 8 controls the flow rate and direction of the oil in the digital valve by driving the main directional valve core 9; the control motor is disposed on the right side of the valve body 6 and fixedly connected by bolts, for driving the pilot hydraulic servo mechanism. A sealing ring 19 is provided between the outer side of the hydraulic servo unit 8 and the inner side of the main directional valve core 9.

[0026] The pilot hydraulic servo mechanism is located inside the main directional valve core 9, including a spindle 10. The spindle 10 is rotatably mounted inside the hydraulic servo unit 8. The tail end of the spindle 10 is connected to a control motor, which drives the spindle 10 to rotate. The end of the spindle 10 has a stepped protrusion, on which the hydraulic servo unit 8, which is fixedly connected to the main directional valve core 9, is fitted. The hydraulic servo unit 8 has a working chamber unit I 18 and a working chamber unit II 20 on both sides, thus forming a left working chamber j and a right working chamber k between the hydraulic servo unit 8 and the working chamber units. A working chamber limiting unit II 17 is provided between working chamber unit I 18 and the limiting top ring II 11, and a working chamber limiting unit I 5 is provided between working chamber unit II 20 and the limiting top ring I 4. Constant low-pressure chambers m and l, which allow return oil to pass through, are formed inside working chamber limiting units I 5 and II 17. The limiting top ring I 4 and the limiting top ring II 11 are connected to the main directional valve core 9 by a top ring screw 21.

[0027] like Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, the spindle 10 is provided with low-pressure distribution holes d and g connected to the low-pressure return oil and high-pressure distribution holes b and i connected to the high-pressure oil source; the inner surface of the hydraulic servo pilot unit 8 is symmetrically provided with two oblique servo flow channels c and h. The servo flow channel c is only connected to the right working chamber k and is correspondingly engaged with the high-pressure distribution hole b and the low-pressure distribution hole d; the servo flow channel h is only connected to the left working chamber j and is correspondingly engaged with the high-pressure distribution hole i and the low-pressure distribution hole g; when the control motor drives the spindle 10 to rotate, the two servo flow channels are connected to the high-pressure distribution hole and the low-pressure distribution hole respectively and form a throttling orifice, thereby changing the pressure in the left working chamber and the right working chamber, pushing the hydraulic servo pilot unit 8 to move while the throttling orifice gradually decreases, thereby controlling the displacement of the main valve core 10, thus forming an electro-hydraulic servo spiral drive, and finally controlling the rotation angle of the motor 1 to be proportional to the displacement of the main valve core 10.

[0028] The pilot hydraulic servo mechanism includes a cylindrical spindle 10. The spindle 10 has distribution grooves a and f in the middle and a stepped inner through hole to form a low-pressure flow channel e. The outer cylindrical surface of the spindle has low-pressure distribution holes d and g that communicate with the low-pressure flow channel e and the distribution groove f. It also has high-pressure distribution holes b and i that communicate with the high-pressure oil source through the distribution groove a.

[0029] like Figure 6 As shown, the inner side of the hydraulic servo pilot unit 8 is symmetrically provided with two oblique servo flow channels c and h. Servo flow channel c is only connected to the right working chamber k and is correspondingly matched with the high-pressure flow distribution hole b and the low-pressure flow distribution hole d. Servo flow channel h is only connected to the left working chamber j and is correspondingly matched with the high-pressure flow distribution hole i and the low-pressure flow distribution hole g.

[0030] The transition hole 7 is located on the main reversing valve core 9. The transition hole 7 is provided with a high-pressure flow channel n that communicates with the high-pressure oil port of the main valve. The high-pressure flow channel n is connected to the high-pressure distribution holes b and i of the spindle 10.

[0031] The working chamber units 18 and 20 are fixedly connected to the main reversing valve core 9 by limiting pins to prevent rotation.

[0032] like Figure 5 , Figure 7 As shown, the outer circular surface of the mandrel 10 is provided with a distribution groove a communicating with the high-pressure distribution holes b and i, and a distribution groove f communicating with the low-pressure distribution holes d and g; the servo flow groove c on the hydraulic servo unit 8 is only communicating with the right working chamber k, and cooperates with the high-pressure distribution hole b and the low-pressure distribution hole d of the mandrel 10; the servo flow groove h is only communicating with the left working chamber j, and cooperates with the high-pressure distribution hole i and the low-pressure distribution hole g.

[0033] like Figure 1 As shown, the main directional valve core 9, hydraulic servo unit 8, working chamber units 18 and 20, working chamber limiting units 5 and 17, transition hole 7, and limiting top rings 4 and 11 are fixedly connected and assembled into one unit, which can slide along the axial direction of the main directional valve core 9. The two ends of the main directional valve core 9 cooperate with the centering springs 16 and 22 through the spring top rings 3 and 12 and the limiting top rings 4 and 11 respectively to achieve centering and reset.

[0034] The valve body 6 has a left end cover 2 and a middle cover 14 at both ends, which are fixedly connected by end cover screws 1.

[0035] The control motor includes a motor housing 13 and a motor rotor 15. The motor housing 13 is sequentially connected to the intermediate cover 14 and the valve body 6. The motor rotor 15 is connected to the spindle 10 to drive the spindle 10 to rotate.

[0036] like Figure 1 , Figure 7 As shown, the high-pressure oil source enters the distribution groove a of the spindle 10 through the high-pressure flow channel n in the transition hole 7 on the main valve of the high-flow electro-hydraulic proportional digital valve, and then connects to the high-pressure distribution holes b and i.

[0037] The low-pressure return oil enters the low-pressure flow channel e inside the spindle 10 through the low-pressure distribution holes d and g, and then connects to the main valve return port T through the constant low-pressure chambers m and l and the flow holes on the main reversing valve core 9.

[0038] The working method of a high-flow digital valve controlled by a motor and driven by a hydraulic servo is as follows: When the control motor is reset, the servo flow channels c and h are not connected to the high-pressure distribution holes b and i or the low-pressure distribution holes d and g, and the main reversing valve core 9 is in the neutral position. When the control motor drives the spindle 10 to rotate counterclockwise by a set angle, the rotation of the spindle 10 connects the servo flow channel c with the high-pressure distribution hole b and the servo flow channel h with the low-pressure distribution hole g. The high-pressure oil enters the distribution channel a of the spindle 10 through the high-pressure flow channel n from the high-pressure oil passage P of the main valve of the large-flow electro-hydraulic proportional digital valve, and after connecting with the high-pressure distribution hole b, it enters the right working chamber k through the servo flow channel c. At the same time, the oil in the left working chamber j connects with the low-pressure distribution hole g through the servo flow channel h, and then connects with the low-pressure return oil passage T of the main valve of the large-flow electro-hydraulic proportional digital valve through the low-pressure flow channel e and the constant low-pressure chamber m. The pressure difference in the two working chambers drives the working chamber unit to move the main reversing valve core 9 to the right axial direction. The movement of the main reversing valve core 9 causes the opening of the distribution hole and the servo flow channel to gradually decrease until it closes. The main reversing valve core 9 stops at the corresponding position, realizing P→A, B→T, and the size of the valve core opening is controlled by the rotation angle ratio of the spindle 10. When the control motor drives the spindle 10 to rotate clockwise and counterclockwise by a set angle, the rotation of the spindle 10 connects the servo flow channel c with the low-pressure distribution hole d and the servo flow channel h with the high-pressure distribution hole i. The high-pressure oil enters the distribution channel a of the spindle 10 through the high-pressure flow channel n from the high-pressure oil passage P of the main valve of the large-flow electro-hydraulic proportional digital valve, and after connecting with the high-pressure distribution hole i, it enters the left working chamber j through the servo flow channel h. At the same time, the oil in the right working chamber k connects with the low-pressure distribution hole d through the servo flow channel h, and connects with the low-pressure return oil passage T of the main valve of the large-flow electro-hydraulic proportional digital valve through the low-pressure flow channel e and the constant low-pressure chamber m. The pressure difference in the two working chambers drives the working chamber unit to move the main reversing valve core 9 to the left axial direction. The movement of the main reversing valve core 9 causes the opening of the distribution hole and the servo flow channel to gradually decrease until it closes. The main reversing valve core 9 stops at the corresponding position, realizing P→B, A→T, and the size of the valve core opening is controlled by the rotation angle ratio of the spindle 10. The rotation angle of the control spindle 10 is proportionally matched with the displacement of the main directional valve core 9 by the hydraulic servo drive, thereby realizing the precise proportional control of the three-position four-way high-flow digital directional valve.

[0039] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A high-flow digital valve controlled by a motor and driven by a hydraulic servo, characterized in that: The system includes a directional valve body, which contains a pilot hydraulic servo mechanism driven by a control motor. The directional valve body includes a valve body (6), which contains a slidable hollow main directional valve core (9). The valve body (6) contains a main valve high-pressure oil passage P, a main valve low-pressure return oil passage T, and working oil passages A and B. The pilot hydraulic servo mechanism includes a hydraulic servo mechanism located within the main directional valve core (9). The hydraulic servo mechanism includes a hydraulic servo unit (8) fixed in the middle of the main directional valve core (9). The hydraulic servo unit (8) contains a spindle (10) driven by a control motor. The hydraulic servo mechanism controls the flow rate and direction of the oil in the digital valve by driving the main directional valve core (9).

2. The high-flow digital valve with motor-controlled hydraulic servo drive according to claim 1, characterized in that: A left end cap (2) is provided on the left side of the valve body (6) by end cap screws (1), and a middle cover (14) is provided on the right side of the valve body (6). The control motor is located on the right side of the valve body (6) and is fixedly connected by bolts. It is used to drive the pilot hydraulic servo mechanism. The control motor includes a motor housing (13) located on the right side of the middle cover (14), and a motor rotor (15) is provided inside the motor housing (13).

3. The high-flow digital valve with motor-controlled hydraulic servo drive according to claim 2, characterized in that: A spring top ring I (3) is provided between the left side of the main reversing valve core (9) and the left end cover (2) through a limiting top ring I (4), and a spring top ring II (12) is provided between the right side of the main reversing valve core (9) and the middle cover (14) through a limiting top ring II (11); the hydraulic servo unit (8) inside the main reversing valve core (9) controls the flow rate and direction of the oil in the digital valve by driving the main reversing valve core (9) to move.

4. The high-flow digital valve with motor-controlled hydraulic servo drive according to claim 3, characterized in that: The pilot hydraulic servo mechanism includes a spindle (10) connected to the motor at the right end. The spindle (10) is rotated by the motor in the inner hole of the hydraulic servo unit (8). The hydraulic servo unit (8) is provided with a working chamber unit I (18) and a working chamber unit II (20) respectively, which are fixedly connected to the main reversing valve core (9) through a limiting shaft. A left working chamber j is formed between the working chamber unit I (18) and the hydraulic servo unit (8), and a right working chamber k is formed between the working chamber unit II (20) and the hydraulic servo unit (8). A working chamber limiting unit I (18) is provided on the left side, which is constrained by the limiting top ring I (4) together with the valve core (9). A working chamber limiting unit II (20) is provided on the right side, which is constrained by the limiting top ring II (11) together with the valve core (9). A constant low pressure chamber m with return oil is formed in the working chamber limiting unit I (5), and a constant low pressure chamber L with return oil is formed in the working chamber limiting unit II (17).

5. The high-flow digital valve with motor-controlled hydraulic servo drive according to claim 4, characterized in that: The mandrel (10) has a distribution groove a and a distribution groove f in the middle side wall, which are connected to the axial through hole. The mandrel (10) has an axial flow channel in the middle, which connects the constant low pressure chamber m and the constant low pressure chamber L. The middle of the axial flow channel has a stepped inner through hole to form a low pressure flow channel e. The low pressure flow channel e is located on the outer cylindrical surface of the mandrel (10) and has a low pressure distribution hole d and a low pressure distribution hole g connected to the low pressure flow channel e and the distribution groove f. It also has a high pressure distribution hole b and a high pressure distribution hole i connected to the high pressure oil source of the main valve high pressure oil passage P through the distribution groove a. The main reversing valve core (9) has a transition hole (7). The transition hole (7) has a high pressure flow channel n connected to the main valve high pressure oil passage P. The high pressure flow channel n is connected to the high pressure distribution hole b and the high pressure distribution hole i of the mandrel (10). The low pressure distribution hole d and the low pressure distribution hole g are connected to the main valve low pressure return oil passage T.

6. The high-flow digital valve with motor-controlled hydraulic servo drive according to claim 5, characterized in that: The inner side of the hydraulic servo pilot unit (8) is provided with two oblique servo flow channels c and h, which are symmetrically arranged. The servo flow channel c on the hydraulic servo unit (8) is only connected to the right working cavity k and cooperates with the high pressure distribution hole b and the low pressure distribution hole d of the spindle 10. The servo flow channel h is only connected to the left working cavity j and cooperates with the high pressure distribution hole i and the low pressure distribution hole g.

7. The high-flow digital valve with motor-controlled hydraulic servo drive according to claim 6, characterized in that: When the control motor drives the spindle (10) to rotate counterclockwise, the oblique servo flow channel c connects with the high-pressure distribution hole b to form a high-pressure throttling orifice, and the oblique servo flow channel h connects with the low-pressure distribution hole g to form a low-pressure throttling orifice. This causes the pressure in the right working chamber k to increase and the pressure in the left working chamber j to decrease. The pressure difference between the right working chamber k and the left working chamber j pushes the hydraulic servo pilot unit (8) to move to the right, while the high-pressure / low-pressure throttling orifice gradually decreases, thereby controlling the displacement of the main valve core (10). When the control motor drives the spindle (10) to rotate clockwise, When rotating, the oblique servo flow channel c communicates with the low-pressure distribution hole d to form a low-pressure throttling port, and the oblique servo flow channel h communicates with the high-pressure distribution hole i to form a high-pressure throttling port, thereby reducing the pressure in the right working chamber k and increasing the pressure in the left working chamber j. The pressure difference between the right working chamber k and the left working chamber j pushes the hydraulic servo pilot unit (8) to move to the left while the high-pressure / low-pressure throttling port gradually decreases, thereby controlling the displacement of the main valve core (10); thus forming an electro-hydraulic servo screw drive, controlling the rotation angle of the motor to be proportional to the displacement of the main valve core (10).

8. The high-flow digital valve with motor-controlled hydraulic servo drive according to claim 7, characterized in that: The main reversing valve core (9), hydraulic servo unit (8), working chamber unit I (18), working chamber unit II (20), working chamber limiting unit I (5), working chamber limiting unit II (17), transition hole (7), limiting top ring I (4), and limiting top ring II (11) are fixedly connected and assembled into one unit, which can slide along the axial direction of the main reversing valve core (9). The two ends of the main reversing valve core (9) are respectively connected with the centering spring I (16) and centering spring II (22) through the spring top ring I (3), spring top ring II (12) and limiting top ring I (4) and limiting top ring II (11) to achieve centering and reset.

9. The high-flow digital valve with motor-controlled hydraulic servo drive according to claim 1, characterized in that: The high-pressure oil source enters the distribution groove a of the mandrel (10) through the high-pressure flow channel n in the transition hole (7) on the main valve of the high-flow electro-hydraulic proportional digital valve, and then connects to the high-pressure distribution hole b and the high-pressure distribution hole i. The low-pressure return oil enters the low-pressure flow channel e in the mandrel (10) through the low-pressure distribution hole d and the low-pressure distribution hole g, and finally connects to the main valve return port T through the constant low-pressure chamber m, the constant low-pressure chamber L and the flow passage hole on the main reversing valve (9).

10. A method for operating a high-flow digital valve with motor-controlled hydraulic servo drive as described in any one of claims 1-9, characterized in that, Includes the following steps: When the control motor is reset, the servo flow channel c and servo flow channel h are not connected to the high-pressure distribution hole b, high-pressure distribution hole i or the low-pressure distribution hole d, low-pressure distribution hole g, and the main reversing valve core (9) is in the neutral position. When the control motor drives the spindle (10) to rotate counterclockwise by a set angle, the spindle (10) rotates to make the servo flow channel c connect with the high-pressure distribution hole b, and the servo flow channel h connect with the low-pressure distribution hole g; the high-pressure oil enters from the high-pressure oil passage P of the main valve, enters the distribution channel a of the spindle (10) through the high-pressure flow channel n, and after connecting with the high-pressure distribution hole b, it enters the right working chamber k through the servo flow channel c; at the same time, the oil in the left working chamber j connects with the low-pressure distribution hole g through the servo flow channel h. And through the low-pressure flow channel e and the constant low-pressure chamber m, it is connected to the low-pressure return oil channel T of the main valve; the pressure difference in the two working chambers drives the working chamber unit to drive the main reversing valve core 9 to move to the right axial direction; the movement of the main reversing valve core 9 causes the opening of the distribution hole and the servo flow channel to gradually decrease until it is closed, and the main reversing valve core 9 stops at the corresponding position, realizing the connection between the high-pressure oil channel P of the main valve and the working oil channel A, the working oil channel B and the low-pressure return oil channel T of the main valve, and the valve core opening size is controlled by the rotation angle ratio of the spindle (10); When the control motor drives the spindle (10) to rotate clockwise and counterclockwise by a set angle, the spindle (10) rotates to make the servo flow channel c connect with the low-pressure distribution hole d, and the servo flow channel h connect with the high-pressure distribution hole i; the high-pressure oil enters from the high-pressure oil passage P of the main valve, enters the distribution channel a of the spindle 10 through the high-pressure flow channel n, and connects with the high-pressure distribution hole i, and then enters the left working chamber j through the servo flow channel h; at the same time, the oil in the right working chamber k connects with the low-pressure distribution hole d through the servo flow channel h, and passes through The low-pressure flow channel e and the constant low-pressure chamber m are connected to the low-pressure return oil channel T of the main valve; the pressure difference in the two working chambers drives the working chamber unit to drive the main reversing valve core (9) to move to the left axial direction; the movement of the main reversing valve core (9) causes the opening of the distribution hole and the servo flow channel to gradually decrease until it is closed, and the main reversing valve core (9) stops at the corresponding position, realizing the connection between the high-pressure oil channel P of the main valve and the working oil channel B, and the working oil channel A and the low-pressure return oil channel T of the main valve. The size of the valve core opening is controlled by the rotation angle ratio of the spindle (10); By using hydraulic servo drive, the rotation angle of the control motor spindle (10) is proportional to the displacement of the main directional valve core (9), thereby realizing precise proportional control of the three-position four-way high-flow digital directional valve.

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