Digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve

Abstract

This invention discloses a digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve, belonging to the field of electro-hydraulic directional valve technology. It includes a main valve body, a main valve core, a centering spring, a direct-drive stepper motor, and a pilot valve core. Using a direct-drive stepper motor as the conversion element, it linearly drives the pilot valve core, which is embedded inside the main valve core and forms a direct mechanical position feedback with it in the two-stage control valve. The hydraulic force generated by the pilot valve core's hydraulic amplification directly drives the linear movement of the main valve core. This achieves a 1:1 high-precision adjustment of the main valve core's movement direction and valve opening according to the digital control signal from the direct-drive stepper motor, thus realizing digital control of high flow rate and flow direction. By inputting positive and negative pulse signals to the direct-drive stepper motor, bidirectional reciprocating digital control of the digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve can be achieved, enabling precise adjustment of the main valve's high flow rate and convenient control of the flow direction.

Description

Technical Field

[0001] This invention relates to the field of electro-hydraulic directional valve technology, and in particular to a digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve. Background Technology

[0002] Electro-hydraulic proportional directional valves and electro-hydraulic servo valves are electro-hydraulic control valves that use proportional electromagnets and torque motors or linear force motors to achieve continuous and proportional adjustment of valve opening and control of fluid flow direction. They can be used in closed-loop control systems to achieve high-precision speed and direction control of load movement. However, because these two types of valves use proportional electromagnets and torque motors or linear force motors as drive elements, their output force is limited, making it difficult to drive large-sized valve cores to move rapidly. This limits high-flow-rate output, and they are relatively expensive. Furthermore, because the valve opening is adjusted at a small degree, the valve is easily contaminated by oil and clogged, making it difficult to meet the requirements of high-reliability applications.

[0003] In recent years, with the increasing maturity and stability of stepper motor technology, especially with the rapid advancement of the development and application of direct-drive stepper motor products, it has become possible to directly drive the valve core using a direct-drive stepper motor. In particular, when a pilot stage is directly driven by a direct-drive stepper motor, and then the main valve core is driven by the hydraulic pressure amplified by the pilot stage, and direct mechanical position feedback is used between the pilot stage and the main stage, digital proportional regulation of the main stage's large flow rate can be achieved. Moreover, the direction control of the liquid flow direction at the main stage valve port can be easily achieved through the directional control of the direct-drive stepper motor.

[0004] The invention patent with application number CN201310437365.6 and authorization announcement number CN103438243B, entitled "A Dual-Core Opposing-Directional Rotation Incremental Electro-hydraulic Digital Flow Control Valve," discloses a dual-core opposing-directional rotation incremental electro-hydraulic digital flow control valve. Compared with existing incremental sliding digital flow valves, this invention's digital valve has higher resolution, dynamic response speed, and flow control accuracy. However, it is only a digital flow control valve and cannot control the direction of liquid flow.

[0005] The invention patent with application number 202210539556.2 and publication (announcement) number CN114658883A describes a servo motor-driven digital directional valve that solves the problems of vibration, flow pulsation, and uneven force on the valve core in existing servo motor-driven digital directional valves. This invention mainly uses a servo motor, which is more expensive than a stepper motor, to rotate in both directions, driving a threaded sleeve to rotate. The rotation of the threaded sleeve then drives the threaded connecting rod to move axially to the left or right, thereby driving the valve core to reciprocate linearly, achieving a digital directional valve that controls the direction and flow rate of the liquid. However, this valve is structurally a single-stage valve, which limits its ability to control large flow rates.

[0006] The invention patent with application number CN201810974619.0 and publication number CN108799236A, entitled "High-Pressure Digital Rotary Motor Driven Servo Valve," includes a four-way servo valve body, a high-response rotary servo motor, an LVDT displacement sensor, an angular displacement sensor, an eccentric mechanism, and a digital servo controller. This invention's high-pressure digital rotary motor driven servo valve features a simple control algorithm, fast response speed, high control accuracy, strong reliability, simple structure, and low maintenance cost. However, this valve is a single-stage structure, which limits its maximum output flow rate, thus restricting its application range.

[0007] The invention patent with application number CN202010566021.5 and publication number CN111894924A is a high-water-based, high-pressure, high-flow digital proportional directional valve with manual and automatic integrated control. It includes an ECU control unit, a pressure sensing element, a pilot valve and a main valve. It can realize liquid inlet proportional control, liquid return switch control and also has manual liquid inlet / return switch control functions. The pilot stage is composed of a two-position three-way switch valve and a two-position two-way high-speed switch valve.

[0008] The proportional directional valve of this invention has built-in displacement sensing and valve orifice flow calculation functions. It monitors the inlet, outlet, and working port pressures through pressure sensing elements, and then calculates the valve core displacement and valve orifice flow through the electronic control unit (ECU). The overall cartridge structure allows for easy integration into a valve assembly. However, its pilot stage consists of two high-speed switching valves, and there is no mechanical feedback between it and the main stage, making it difficult to achieve high-precision positioning control of the main valve core.

[0009] In summary, it is not difficult to see that the digital valves in existing invention patents do not use direct-drive bidirectional stepper motors as linear drive elements, and rarely adopt a structure in which the pilot valve core is embedded inside the main valve core to form a direct mechanical position feedback. Single-stage digital valves generally have difficulty achieving large flow control. Summary of the Invention

[0010] To address the above technical problems, this invention provides a digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve. It employs a direct-drive stepper motor as the electro-mechanical conversion element, linearly driving a pilot valve core housed within the main valve core, forming a direct mechanical position feedback mechanism with it. The hydraulic force generated by the pilot valve core's hydraulic amplification directly drives the linear movement of the main valve core. This allows the main valve core's movement direction and valve opening to be adjusted according to the digital control signal from the direct-drive stepper motor, thereby achieving digital control of large fluid flow rate and direction.

[0011] To achieve the above objectives, the present invention provides the following solution:

[0012] This invention provides a digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve, comprising a main stage valve body, a main stage valve core, a pilot stage valve core, and a linear reciprocating drive mechanism;

[0013] The main valve body is provided with a valve chamber;

[0014] Both the main stage valve core and the pilot stage valve core are disposed within the valve cavity, with one end of the pilot stage valve core extending into the main stage valve core; the other end of the pilot stage valve core is connected to the linear reciprocating drive mechanism; the linear reciprocating drive mechanism is used to drive the pilot stage valve core to reciprocate along a linear path.

[0015] The main valve body is provided with a first working oil port, a second working oil port, an oil inlet, an oil return port, and an external oil drain port;

[0016] The main valve body is provided with a first cavity, a second cavity, a third cavity, and a fourth cavity;

[0017] The pilot valve core is provided with a fifth cavity;

[0018] A sixth cavity is provided between one end of the main valve core and the inner wall of the valve chamber;

[0019] A seventh cavity is provided between the other end of the main stage valve core, the side wall of the pilot stage valve core, and the inner wall of the valve cavity.

[0020] One end of the first cavity is connected to one end of the second cavity; the other end of the second cavity is connected to one end of the third cavity; the other end of the third cavity is connected to the fourth cavity; the fourth cavity is used to connect one end of the external oil drain port and one end of the fifth cavity;

[0021] The sixth cavity is provided with a first main stage valve core centering spring, and the seventh cavity is provided with a second main stage valve core centering spring.

[0022] The pilot valve core is used to control the connection and disconnection between the fifth cavity and the seventh cavity, as well as the connection and disconnection between the sixth cavity and the fifth cavity;

[0023] When initially operating at zero position, the main valve core is in the middle position; at this time, the first working port, the second working port, the inlet port, and the return port are not connected to each other;

[0024] When in the left-hand working position, the main valve core is in the left-hand position; at this time, hydraulic oil flows from the inlet to the first working port, and hydraulic oil flows from the second working port to the return port;

[0025] When in the right-hand working position, the main valve core is in the right-hand position; at this time, hydraulic oil flows from the inlet to the second working port, and hydraulic oil flows from the first working port to the return port.

[0026] Optionally, the output end of the linear reciprocating drive mechanism is provided with a push rod, and the end of the push rod is connected to the other end of the pilot stage valve core.

[0027] Optionally, an eighth cavity is provided between the side wall of the push rod near the pilot valve core and the inner wall of the valve chamber. In the rightward working position, the eighth cavity is connected to the other end of the first cavity.

[0028] Optionally, the main stage valve core is provided with a first valve port and a second valve port radially; the main stage valve core is provided with a third valve port and a fourth valve port axially; the first valve port and the third valve port are connected; the fifth cavity is connected to the seventh cavity through the first valve port and the third valve port; the second valve port and the fourth valve port are connected; the sixth cavity is connected to the seventh cavity through the second valve port and the fourth valve port.

[0029] Optionally, a damper is provided at the end of the fourth valve port facing the sixth cavity.

[0030] Optionally, the linear reciprocating drive mechanism includes a direct-drive stepper motor.

[0031] Optionally, a left valve cover plate for the main valve is provided at one end of the main valve body, and a right valve cover plate for the main valve is provided at the other end of the main valve body; the third cavity is provided on the left valve cover plate of the main valve, and the first cavity is provided on the right valve cover plate of the main valve.

[0032] Optionally, a pipe joint is provided at the end of the main valve body away from the linear reciprocating drive mechanism, and the external oil drain port is provided on the pipe joint.

[0033] The present invention achieves the following technical effects compared to the prior art:

[0034] The digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve of this invention utilizes the direct mechanical position feedback principle between the pilot valve core and the main valve core. When positive and negative pulse signals are input to the direct-drive stepper motor respectively, the bidirectional reciprocating digital control of this digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve can be achieved, thereby regulating the high flow rate and controlling the flow direction of the main valve. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the initial working zero position of the digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve of the present invention.

[0037] Figure 2 This is a structural diagram of the left-hand working position of the digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve of the present invention.

[0038] Figure 3 This is a structural diagram of the right-hand working position of the digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve of the present invention.

[0039] Explanation of reference numerals in the attached diagram: 1. Pipe fitting; 2. First static seal ring; 3. First plug; 4. Second static seal ring; 5. First main stage valve core centering spring; 6. Main stage valve body; 7. Main stage valve core; 8. Second plug; 9. Third plug; 10. Third static seal ring; 11. Fourth plug; 12. Fourth static seal ring; 13. Direct drive stepper motor; 14. Left valve cover plate of the main stage valve; 15. Fifth static seal ring; 16. Glyd ring of the main stage valve core; 17. Pilot stage valve core; 18. Second main stage valve core centering spring; 19. Sixth static seal ring; 20. Right valve cover plate of the main stage valve; 21. Push rod;

[0040] I. First cavity; II. Second cavity; III. Third cavity; IV. Fourth cavity; V. Fifth cavity; VI. Sixth cavity; VII. Seventh cavity; VIII. Eighth cavity;

[0041] a. First valve port; b. Second valve port; c. Third valve port; d. Fourth valve port; e. Damper;

[0042] A, First working oil port; B, Second working oil port; P, Oil inlet; T, Oil return port; L, External drain port. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] like Figures 1 to 3As shown, this embodiment provides a digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve, including a main stage valve body 6, a main stage valve core 7, a pilot stage valve core 17, and a linear reciprocating drive mechanism; a valve cavity is provided inside the main stage valve body 6; both the main stage valve core 7 and the pilot stage valve core 17 are disposed within the valve cavity, and one end of the pilot stage valve core 17 extends into the main stage valve core 7; the other end of the pilot stage valve core 17 is connected to the linear reciprocating drive mechanism; the linear reciprocating drive mechanism is used to drive the pilot stage valve core 17 to move linearly reciprocally; the main stage... The valve body 6 is provided with a first working oil port A, a second working oil port B, an oil inlet P, an oil return port T, and an external drain port L; the main stage valve body 6 is provided with a first cavity I, a second cavity II, a third cavity III, and a fourth cavity IV; the pilot stage valve core 17 is provided with a fifth cavity V; a sixth cavity VI is provided between one end of the main stage valve core 7 and the inner wall of the valve cavity; a seventh cavity VII is provided between the other end of the main stage valve core 7, the side wall of the pilot stage valve core 17, and the inner wall of the valve cavity; one end of the first cavity I and the second cavity II... One end is connected; the other end of the second cavity II is connected to one end of the third cavity III; the other end of the third cavity III is connected to the fourth cavity IV; the fourth cavity IV is used to connect one end of the external drain port L and one end of the fifth cavity V; the sixth cavity VI is equipped with a first main stage valve core centering spring 5, and the seventh cavity VII is equipped with a second main stage valve core centering spring 18; the pilot stage valve core 17 is used to control the on / off state of the fifth cavity V and the seventh cavity VII, as well as the on / off state of the sixth cavity VI and the fifth cavity V; in the initial working zero position When the main valve core 7 is in the middle position, the first working port A, the second working port B, the inlet port P, and the return port T are not connected to each other. When the main valve core 7 is in the left-hand working position, the hydraulic oil flows from the inlet port P to the first working port A and from the second working port B to the return port T. When the main valve core 7 is in the right-hand working position, the hydraulic oil flows from the inlet port P to the second working port B and from the first working port A to the return port T.

[0045] In this specific embodiment, the linear reciprocating drive mechanism includes a direct-drive stepper motor 13. A push rod 21 is provided at the output end of the direct-drive stepper motor 13, and the end of the push rod 21 is connected to the other end of the pilot stage valve core 17. Further, the end of the push rod 21 connected to the direct-drive stepper motor 13 has the largest diameter, the end of the push rod 21 connected to the pilot stage valve core 17 has the smallest diameter, and the diameter of the middle portion of the push rod 21 near the pilot stage valve core 17 is between the diameters of the two ends, forming an eighth cavity VIII. Figure 1 As shown, when push rod 21 moves to the left, the part with the largest diameter in the middle of push rod 21 blocks the first cavity I. When push rod 21 moves to the right, the part with the smaller diameter in the middle of push rod 21 connects the first cavity I with the eighth cavity VIII.

[0046] The main valve core 7 has a first valve port a and a second valve port b arranged radially; the main valve core 7 has a third valve port c and a fourth valve port d arranged axially; a second plug 8 is provided at one end of the first valve port a on the outer wall of the main valve core 7, and a third plug 9 is provided at one end of the second valve port b on the outer wall of the main valve core 7.

[0047] The first valve port a is connected to the third valve port c; the fifth cavity V is connected to the seventh cavity VII through the first valve port a and the third valve port c; the second valve port b is connected to the fourth valve port d; the sixth cavity VI is connected to the seventh cavity VII through the second valve port b and the fourth valve port d.

[0048] A damper e is provided at the end of the fourth valve port d facing the sixth cavity VI. In this specific embodiment, the damper e includes a damping short hole disposed in the damping body, and the damping body is threadedly connected to the fourth valve port d, which is beneficial to the dynamic response of the valve.

[0049] A main stage valve body 6 has a main stage valve left cover plate 14 at one end and a main stage valve right cover plate 20 at the other end. A third cavity III is located on the main stage valve left cover plate 14, and a first cavity I is located on the main stage valve right cover plate 20. A first plug 3 is located at the end of the third cavity III on the outer wall of the main stage valve left cover plate 14, and a fourth plug 11 is located at the end of the first cavity I on the outer wall of the main stage valve right cover plate 20. A second static sealing ring 4 and a fifth static sealing ring 15 are provided between the main stage valve left cover plate 14 and the main stage valve body 6; a third static sealing ring 10 and a sixth static sealing ring 19 are provided between the main stage valve right cover plate 20 and the main stage valve body 6.

[0050] A pipe joint 1 is provided at the end of the main valve body 6 away from the linear reciprocating drive mechanism, and an external drain port L is provided on the pipe joint 1. The external drain port L is used to communicate with the oil tank. A first static sealing ring 2 is provided between the pipe joint 1 and the main valve body 6.

[0051] In a more specific embodiment, a fourth static sealing ring 12 is provided between the housing of the direct-drive stepper motor 13 and the right valve cover plate 20 of the main stage valve. A main stage valve core Gladius ring 16 is provided on the side wall of the main stage valve core 7 facing the fourth cavity IV to prevent leakage of the high-pressure chamber of the sixth cavity VI.

[0052] The working process of this digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve is as follows:

[0053] Figure 1With the valve in its zero-position working state, the first valve port a and the second valve port b are closed. When no pulse signal is input to the direct-drive stepper motor 13, high-pressure oil is input to the main stage valve through the oil inlet P. The pressure in the sixth chamber VI is equal to the pressure at the oil inlet P. Since the effective pressure-bearing area at the left end of the main stage valve core 7 is slightly larger than that at the right end, the main stage valve core 7 moves rapidly to the right under the drive of the unbalanced oil pressure. The second valve port b opens and the first valve port a remains closed. The high-pressure oil from the sixth chamber VI then enters the seventh chamber VII through the second valve port b. As the oil pressure in the seventh chamber VII increases, the oil pressure force acting on the right end of the main stage valve core 7 increases rapidly until it equals the oil pressure force at its left end. The main stage valve core 7 then moves rapidly to the left again, returning to the initial working zero position. That is, the first valve port a and the second valve port b are both closed again. The four oil inlets P, the first working oil port A, the second working oil port B, and the return oil port T of the main stage valve are not connected to each other. Next, a positive pulse signal is input to the direct-drive stepper motor 13, causing the push rod 21 to move the pilot valve core 17 to the left by a corresponding step displacement. The second valve port b is then quickly opened again, while the first valve port a remains closed. As the oil pressure in the seventh chamber VII increases, the main valve core 7, driven by the unbalanced oil pressure force, also rapidly moves to the left by the same step displacement until the oil pressure forces at both ends of the main valve core 7 are equal again. That is, the main valve core 7 moves to a new working position to the left along with the pilot valve core 17. This is the so-called direct mechanical position feedback. At this time, the opening degree of the main valve inlet P, which connects to the first valve port a, is the same step displacement, and the opening degree of the second valve port b, which connects to the return port T, is the same step displacement. Therefore, the pressure entering the first valve port a... The flow rates of the hydraulic oil and the pressure oil flowing out of the second valve port b are adjusted. At the same time, the flow direction of the pressure oil at the inlet port P is also controlled, that is, the oil flows from the inlet port P to the first valve port a, and the oil flows from the second valve port b to the return port T. Similarly, if a positive pulse signal is input to the direct drive stepper motor 13, the push rod 21 moves the pilot valve core 17 to the left until the maximum step displacement. Then the main valve core 7 also moves to the left with the pilot valve core 17 to the maximum step displacement and reaches a new working position. At this time, the valve opening of the main valve inlet port P connected to the first valve port a is at the maximum step displacement, and the valve opening of the second valve port b connected to the return port T is also at the maximum step displacement. Therefore, the flow rate through the first valve port a and the second working port B of the main valve is the maximum, but the flow direction of the hydraulic oil does not change.Next, a reverse pulse signal is input to the direct-drive stepper motor 13. The push rod 21 moves the pilot valve core 17 to the right by a corresponding step displacement. The first valve port a is immediately opened, while the second valve port b remains closed. As the oil pressure in the seventh chamber VII decreases, the main valve core 7, driven by the unbalanced oil pressure force, also quickly moves to the right by the same step displacement until the oil pressure values ​​at both ends of the main valve core 7 are equal again. That is, the main valve core 7 moves to a new working position together with the pilot valve core 17 to the right. At this time, the opening of the valve port P, which is connected to the first valve port a, decreases by the same step displacement, and the opening of the valve port b, which is connected to the return port T, also decreases by the same step displacement. Therefore, the flow rates of the pressurized oil entering the first valve port a and exiting the second valve port b decrease, but the flow direction remains unchanged. Similarly, by continuing to input a reverse pulse signal to the direct-drive stepper motor 13, the push rod 21 moves the pilot valve core 17 to the right until it reaches its maximum step displacement and returns to its initial zero position. The main valve core 7 also moves to the right with the pilot valve core 17, reaching its maximum step displacement and returning to its initial zero position. During this adjustment process, the opening of the main valve's inlet P, which connects to the first valve port a, decreases sequentially to zero, as does the opening of the second valve port b, which connects to the return port T. The flow rate through the main valve ports also decreases sequentially to zero. Thus, the valve completes one positive reciprocating control cycle from its initial zero position.

[0054] When the valve is in its initial zero-position state, a reverse pulse signal is first input to the direct-drive stepper motor 13. The push rod 21 moves the pilot valve core 17 to the right by a corresponding step displacement. The first valve port a is then quickly opened, while the second valve port b remains closed. As the oil pressure in the seventh chamber VII decreases, the main valve core 7, driven by the unbalanced oil pressure force, also quickly moves to the right by the same step displacement until the oil pressure values ​​at both ends of the main valve core 7 are equal again, at which point it stops. That is, the main valve core 7 follows the pilot valve core 17... The first stage valve core 17 moves to the right to a new working position. At this time, the valve opening of the main stage valve's inlet P and the second valve port b increases by the same step displacement, and the valve opening of the first valve port a and the return port T also increases by the same step displacement. Therefore, the flow rate of the pressure oil entering the second valve port b and the pressure oil flowing out of the first valve port a is adjusted, and the flow direction of the pressure oil at the inlet P is also controlled, that is, the oil flows from the inlet P to the second valve port b, and the oil flows from the first valve port a to the return port T. Similarly, if a reverse pulse signal is input to the direct-drive stepper motor 13, the push rod 21 will move the pilot valve core 17 to the right until the maximum step displacement. Then the main valve core 7 will also move to the right with the pilot valve core 17 to the maximum step displacement and reach a new working position. At this time, the valve opening of the main valve inlet P and the second valve port b is at the maximum step displacement, and the valve opening of the first valve port a and the return port T is also at the maximum step displacement. Therefore, the flow rate through the main valve second valve port b and the first working port A is the maximum, but the flow direction of the pressure oil does not change. Next, a positive pulse signal is input to the direct-drive stepper motor 13. The push rod 21 moves the pilot valve core 17 to the left by a corresponding step displacement. The second valve port b is then quickly opened, while the first valve port a remains closed. As the oil pressure in the seventh chamber VII increases, the main valve core 7, driven by the unbalanced oil pressure force, also quickly moves to the left by the same step displacement until the oil pressure values ​​at both ends of the main valve core 7 are equal again. That is, the main valve core 7 moves to a new working position to the left along with the pilot valve core 17. At this time, the opening of the valve port P, which connects to the second valve port b, decreases by the same step displacement, and the opening of the valve port a, which connects to the return port T, also decreases by the same step displacement. Therefore, the flow rates of the pressurized oil entering the second valve port b and the pressurized oil flowing out of the first valve port a are reduced, but the flow direction of the liquid remains unchanged. Similarly, if a positive pulse signal is continuously input to the direct-drive stepper motor 13, the push rod 21 moves the pilot valve core 17 to the left until the maximum step displacement is reached and it returns to the initial working zero position. Then the main valve core 7 also moves to the left with the pilot valve core 17 to the maximum step displacement and also returns to the initial working zero position. During this adjustment process, the valve opening of the main valve inlet P connected to the second valve port b is reduced to zero in sequence, the valve opening of the first valve port a connected to the return port T is also reduced to zero in sequence, and the flow rate of the liquid passing through the main valve port is also reduced to zero in sequence.At this point, the valve has completed one reverse reciprocating control from its initial zero-position state.

[0055] As can be seen, by utilizing the direct mechanical position feedback principle between the pilot valve core 17 and the main valve core 7, by inputting positive and negative pulse signals to the direct-drive stepper motor 13 respectively, bidirectional reciprocating digital control of this digital high-flow direct mechanical feedback two-stage electro-hydraulic directional valve can be achieved, thus realizing the regulation of high flow rate and control of flow direction of the main valve.

[0056] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0057] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A digital high flow direct mechanical feedback two-stage electro-hydraulic directional valve characterized in that, The valve comprises a main-stage valve body, a main-stage valve core, a pilot-stage valve core and a linear reciprocating driving mechanism. The main-stage valve body is provided with a valve cavity. The main-stage valve core and the pilot-stage valve core are arranged in the valve cavity, and one end of the pilot-stage valve core extends into the main-stage valve core. The other end of the pilot-stage valve core is connected with the linear reciprocating driving mechanism. The main-stage valve body is provided with a first working oil port, a second working oil port, an oil inlet port, an oil return port and an external oil discharge port. The main-stage valve body is provided with a first cavity, a second cavity, a third cavity and a fourth cavity. The pilot-stage valve core is provided with a fifth cavity. One end of the main-stage valve core is provided with a sixth cavity. The other end of the main-stage valve core, the side wall of the pilot-stage valve core and the inner wall of the valve cavity are provided with a seventh cavity. One end of the first cavity is communicated with one end of the second cavity; the other end of the second cavity is communicated with one end of the third cavity; the other end of the third cavity is communicated with the fourth cavity; and the fourth cavity is used for communicating one end of the external oil discharge port and one end of the fifth cavity. The sixth cavity is provided with a first main-stage valve core centering spring, and the seventh cavity is provided with a second main-stage valve core centering spring. The pilot-stage valve core is used for controlling the opening and closing of the fifth cavity and the seventh cavity and the opening and closing of the sixth cavity and the fifth cavity. In the initial working zero position, the main-stage valve core is in the middle position; at this time, the first working oil port, the second working oil port, the oil inlet port and the oil return port are not communicated with each other. In the left working position, the main-stage valve core is in the left position; at this time, the hydraulic oil flows from the oil inlet port to the first working oil port, and the hydraulic oil flows from the second working oil port to the oil return port.

2. The digital high flow direct mechanical feedback bi-state electro-hydraulic directional valve of claim 1, wherein, In the right working position, the main-stage valve core is in the right position; at this time, the hydraulic oil flows from the oil inlet port to the second working oil port, and the hydraulic oil flows from the first working oil port to the oil return port.

3. The digital high flow direct mechanical feedback bi-state electro-hydraulic directional valve of claim 2, wherein, The output end of the linear reciprocating driving mechanism is provided with a push rod, and the end of the push rod is connected with the other end of the pilot-stage valve core.

4. The digital high flow direct mechanical feedback bi-state electro-hydraulic directional valve of claim 1, wherein, The end of the push rod close to the side wall of the pilot-stage valve core and the inner wall of the valve cavity are provided with an eighth cavity, and in the right working position, the eighth cavity is communicated with the other end of the first cavity.

5. The digital high flow direct mechanical feedback bi-state electro-hydraulic directional valve of claim 4, wherein, The main-stage valve core is provided with a first valve port and a second valve port in the radial direction; the main-stage valve core is provided with a third valve port and a fourth valve port in the axial direction; the first valve port is communicated with the third valve port; the fifth cavity is communicated with the seventh cavity through the first valve port and the third valve port; the second valve port and the fourth valve port are communicated; the sixth cavity is communicated with the seventh cavity through the second valve port and the fourth valve port.

6. The digital high flow direct mechanical feedback double stage electro-hydraulic directional valve of claim 1, wherein, The fourth valve port is provided with a damper towards one end of the sixth cavity. The linear reciprocating driving mechanism comprises a direct-drive stepper motor.

7. The digital high flow direct mechanical feedback bi-state electro-hydraulic directional valve of claim 1, wherein, One end of the main stage valve body is provided with a main stage valve left cover plate, and the other end of the main stage valve body is provided with a main stage valve right cover plate; the third cavity is arranged on the main stage valve left cover plate, and the first cavity is arranged on the main stage valve right cover plate.

8. The digital high flow direct mechanical feedback double stage electro-hydraulic directional valve of claim 1, wherein, One end of the main stage valve body is provided with a main stage valve left cover plate, and the other end of the main stage valve body is provided with a main stage valve right cover plate; the third cavity is arranged on the main stage valve left cover plate, and the first cavity is arranged on the main stage valve right cover plate. One end of the main stage valve body is provided with a main stage valve left cover plate, and the other end of the main stage valve body is provided with a main stage valve right cover plate; the third cavity is arranged on the main stage valve left cover plate, and the first cavity is arranged on the main stage valve right cover plate. One end of the main stage valve body is provided with a main stage valve left cover plate, and the other end of the main stage valve body is provided with a main stage valve right cover plate; the third cavity is arranged on the main stage

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