An intrinsically safe electro-hydraulic servo valve for mine

Abstract

The application discloses a mine intrinsic safety type electro-hydraulic servo valve and relates to the technical field of coal mine hydraulic control. The servo valve comprises a servo valve, an electromagnetic pilot valve, a hydraulic control main valve assembly, the hydraulic control main valve assembly comprises a plurality of hydraulic control main valve spools, the hydraulic control main valve assembly is connected with the upper chamber of a jack through a pipeline, and the jack is pushed out or retracted through liquid supply or liquid return; a two-stage hydraulic control check valve assembly is used for controlling the liquid state change in the lower chamber of the jack, and the motion state change of the jack is realized; and a servo valve assembly is used for controlling the medium flow in the lower chamber, and the working state of the jack is controllable. The application skillfully combines the 'high-precision continuous regulation' of servo proportional control and the 'large-flow quick response' of traditional hydraulic control switching, fully overcomes the industry pain points such as fixed valve core flow, rough action, low liquid return efficiency and expansion difficulty on the basis of retaining the high reliability of the coal mine electro-hydraulic control system.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology in coal mines, and in particular to an intrinsically safe electro-hydraulic servo valve for mining applications. Background Technology

[0002] The electro-hydraulic control system of hydraulic supports in fully mechanized coal mining faces is a core piece of equipment ensuring safe and efficient mining. Its directional valve group is responsible for converting the controller's electrical signals into hydraulic energy, driving cylinders or jacks to complete actions such as raising, lowering, pushing, and moving the supports. Currently, the industry generally adopts a two-level control architecture of "on / off electromagnet + pilot valve + main valve": the on / off electromagnet receives the digital switching signal from the controller, controls the opening and closing of the pilot valve oil circuit through activation and deactivation, and then drives the hydraulic main valve core to switch to the fully open or fully closed position, realizing the high-flow output or cutoff of high-pressure working fluid, and ultimately controlling the extension or retraction of the actuator.

[0003] This type of valve assembly is essentially an on / off hydraulic control element. Its main valve spool stroke and valve opening are structurally fixed, allowing only two operating conditions: "fully open" or "fully closed," resulting in a step-like change in flow output. In practical applications, due to the unadjustable valve opening and uncontrollable flow, the hydraulic support actuators (such as push jacks and balance jacks) lack continuous adjustment capabilities, making it difficult to achieve precise matching of movement speed, stroke position, and output force. This leads to problems such as hydraulic shock, low positioning accuracy, and uneven posture adjustment during support operation, failing to meet the technological requirements of modern intelligent coal mining for refined support management, low-impact stable operation, and high-precision posture control.

[0004] Therefore, how to break through the technical bottleneck of fixed flow and coarse control of traditional switching valves, and achieve continuous adjustment of the opening of the directional valve core and precise proportional control of the flow, has become a key technical problem that needs to be solved in the current electro-hydraulic control system of hydraulic supports. Summary of the Invention

[0005] The present invention addresses the problem that existing technical solutions are too simplistic and provides a solution that is significantly different from existing technologies. The present invention provides an intrinsically safe electro-hydraulic servo valve for mining, which solves the technical problem that the switching valve in the existing electro-hydraulic control system of hydraulic support is limited by its structure, making it impossible to perform precise control.

[0006] The embodiments of the present invention adopt the following technical solution: an intrinsically safe electro-hydraulic servo valve for mining, further comprising; A servo valve assembly, comprising a servo motor and a servo valve, wherein the servo valve is connected to the lower chamber of the jack; A two-stage hydraulically controlled check valve assembly, comprising two hydraulically controlled check valves, wherein the locking ports of the two hydraulically controlled check valves are connected to a servo valve; A hydraulically controlled main valve assembly, the hydraulically controlled main valve assembly including a hydraulically controlled main valve, the working port of the hydraulically controlled main valve being connected to the upper chamber of the jack; The electromagnetic pilot valve is connected to the hydraulic control port of the two-stage hydraulic control check valve and the hydraulic control main valve respectively, and is used to control the on and off of the two-stage hydraulic control check valve and the switching of the valve core of the hydraulic control main valve between the zero position and the working position. When the jack extends, liquid is injected into the lower chamber of the jack through the servo valve. The servo motor drives the servo valve core to adjust the opening to control the flow rate of the medium in the lower chamber of the jack, so as to achieve precise adjustment of the extension speed and position. The two-stage hydraulic control check valve is locked and pressure is maintained. When the hydraulic control main valve core is in the zero position, the liquid in the lower chamber of the jack is drained. When the jack retracts, the hydraulic control main valve core is in the working position, injecting liquid into the upper chamber of the jack; the two-stage hydraulic control check valves are fully open to form a high-flow return bypass, and the medium in the lower chamber of the jack flows back quickly, achieving rapid retraction.

[0007] Furthermore, the hydraulic control main valve assembly also includes an electromagnetic pilot valve. The hydraulic control main valve is connected to the electromagnetic pilot valve. The hydraulic control main valve is provided with an inlet, a return port, a working port, and a first hydraulic control port (X1), and the valve core is provided with a corresponding through hole for liquid flow.

[0008] Furthermore, the two-stage hydraulic control check valve includes a push rod that moves within it. The two-stage hydraulic control check valve is also provided with a first-stage small valve core and a second-stage large valve core. The second-stage large valve core is reset by a return spring. The first-stage small valve core is located at the end of the second-stage large valve core. The two-stage hydraulic control check valve is respectively provided with an outlet, a lockout port, and a second hydraulic control port.

[0009] Furthermore, the outlet and the locking port form a flow channel.

[0010] Furthermore, the internal through holes of the hydraulic control main valve form flow channels with the inlet and return ports, respectively.

[0011] Furthermore, the servo valve assembly includes a servo motor and a servo valve. The servo valve is controlled by the servo motor and is connected to one of the two-stage hydraulic check valves and the lower cavity of the jack, forming a flow path in the lower cavity of the jack.

[0012] Furthermore, one of the hydraulic control main valves is connected to the upper cavity of the jack to control the back-and-forth flow of liquid inside the upper cavity, forming a flow path in the upper cavity of the jack.

[0013] Furthermore, the electromagnetic pilot valve forms a pilot control flow path with one of the hydraulically controlled main valves and the two-stage hydraulically controlled check valves. Compared with the prior art, the beneficial effects of the present invention are as follows: Firstly, addressing the technical shortcomings of existing switching valves—such as fixed valve core openings and step-like flow outputs leading to rough jack movements, significant hydraulic shocks, and inaccurate position control—this invention constructs a proportional flow control loop through a servo valve and a co-operated electro-hydraulic directional valve. This loop fully utilizes the continuously adjustable servo valve core opening, enabling real-time linear mapping between the high-pressure inlet flow and the controller's analog or PWM commands, achieving stepless and smooth adjustment of the jack's inlet speed. By precisely controlling the flow input, the step-like hydraulic shocks during directional switching are effectively eliminated, achieving millimeter-level precision matching between the jack's advance stroke and the target position. This meets the refined management requirements for fine-tuning the posture of the fully mechanized mining face support and ensuring stable, low-impact operation.

[0014] Secondly, to address the issue of slow response caused by high throttling resistance and limited return path in traditional proportional valves during retraction, this invention employs a parallel control architecture of an electromagnetic pilot valve and a two-stage hydraulically controlled check valve in the retraction circuit. Upon receiving a retraction command, the electromagnetic pilot valve outputs a hydraulic pressure signal, simultaneously triggering the opening of the two-stage hydraulically controlled check valve and the reversal of the hydraulically controlled main valve core, thus constructing a high-flow-rate automatic return bypass in the lower chamber. This design enables rapid direct discharge of high-pressure fluid during jack retraction without the intervention of a servo valve, significantly shortening the retraction response time and improving the efficiency of the support's cyclical operation. Simultaneously, it avoids throttling wear and energy accumulation of the servo valve under high-frequency, high-flow-rate return conditions, significantly extending the service life of core precision components and ensuring the long-term reliability of the system under harsh downhole conditions. (It should be further noted that during the return process, the servo valve in the lower chamber flow path can be selectively engaged. If engagement is required, a controllable retraction state can be achieved, allowing for easy opening or closing.)

[0015] Third, the standardized plug-in modular architecture supports flexible functional expansion and rapid operation and maintenance. To address the challenges of customized valve assembly functions and high downtime maintenance costs in complex downhole operating conditions, this invention employs a modular integrated design. The servo control unit, electromagnetic pilot unit, hydraulic unidirectional unit, and main valve module can be independently packaged, assembled as needed, and quickly replaced. This structure not only facilitates flexible expansion of the control loop within limited installation space (such as adding or removing oil circuit interfaces, upgrading servo precision, or integrating additional logic valves), but also supports online hot-swappable replacement of faulty modules, significantly reducing downtime for maintenance and lowering the complexity of operation and maintenance throughout the entire lifecycle. It provides a highly compatible hardware foundation for the flexible upgrading of hydraulic support electro-hydraulic control systems and the transformation of existing production lines.

[0016] In summary, this invention ingeniously integrates the "high-precision continuous adjustment" of servo proportional control with the "large flow and fast response" of traditional hydraulic switches. While retaining the high reliability of coal mine electro-hydraulic control systems, it comprehensively overcomes industry pain points such as fixed valve core flow, rough action, low return efficiency, and difficulty in expansion. It provides a feasible and easily expandable engineering solution for intelligent, low-impact, and high-precision position and posture control of hydraulic supports, with significant safety benefits and industrialization value. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of the electro-hydraulic servo valve of the present invention; Figure 2 For the present invention Figure 1 Schematic diagram of the corresponding sectional structure in the middle; Figure 3 This is a schematic diagram of the structure of the hydraulic control main valve core movement state change according to the present invention; Figure 4 This is a schematic diagram of the hydraulic control main valve function of the present invention; Figure 5 This is a schematic diagram of the two-stage hydraulic control check valve core motion state change structure of the present invention; Figure 6 This is a schematic diagram of the two-stage hydraulic control check valve of the present invention.

[0019] Figure label: 1. Servo valve assembly; 2. Hydraulic main valve assembly; 3. Two-stage hydraulic check valve assembly; 4. Servo motor; 5. Servo valve; 6. Two-stage hydraulic check valve; 62. Push rod; 63. First-stage small valve core; 64. Second-stage large valve core; 7. Hydraulic main valve; 8. Solenoid pilot valve; P1, Liquid Inlet; R1, Liquid Return Inlet; A1, Working Inlet; X1, First Liquid Control Inlet; R2, liquid outlet; A2, lockout port; X2, second liquid control port. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] The components of the embodiments of the invention described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0022] 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.

[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] The following is combined Figures 1 to 6 As shown, an embodiment of the present invention provides an intrinsically safe electro-hydraulic servo valve for mining applications, comprising: The hydraulic control main valve assembly 2 includes several hydraulic control main valves 7. The hydraulic control main valve assembly 2 is connected to the upper chamber of the jack through a pipeline, and the jack can be pushed out or retracted by supplying or returning liquid. A two-stage hydraulic control check valve assembly 3 includes two two-stage hydraulic control check valves 6. The lower chamber of the jack is connected to one of the servo valves 5 and one of the two-stage hydraulic control check valves 6 in sequence through a flow pipe. This assembly is used to control the change of the liquid state inside the lower chamber of the jack and realize the change of the jack's motion state. The servo valve assembly 1 includes two sets of servo motors 4 and servo valves 5. The servo valve assembly 1 is connected to the flow channel of the lower chamber of the jack. The servo motors 4 are used to drive the movement of the valve core of the servo valve 5. By changing the size of the internal valve core opening, the flow rate of the medium inside the lower chamber is controlled, so as to realize the controllable working state of the jack.

[0026] During operation, the extension and retraction of the jack are coordinated by the precision flow regulation of the servo valve 5 and the on / off control of the solenoid pilot valve 8. In the extension mode, the servo valve 5 receives a controller command and opens, allowing the high-pressure working fluid to flow into the lower chamber of the jack through the two-stage hydraulic control check valve 6 and the servo valve 5, pushing the piston rod to extend. At the same time, the solenoid pilot valve 8 outputs pilot pressure to the first hydraulic control port X1 of the hydraulic control main valve 7, switching it to the working position. The working fluid in the upper chamber of the jack is discharged to the return line through the main valve, achieving synchronous coordination between the upper chamber discharge and the lower chamber inflow. In the retraction mode, the electromagnetic pilot valve 8 simultaneously supplies pressure to the first hydraulic control port X1 of the hydraulic control main valve 7 and the second hydraulic control port X2 of the two-stage hydraulic control check valve 6. The hydraulic control main valve 7 switches to the inlet position, allowing high-pressure liquid to quickly fill the upper chamber. The two-stage hydraulic control check valve 6 unlocks and opens, and the high-pressure liquid in the lower chamber is discharged back to the return line through the unloading channel inside the valve at a high flow rate. The servo valve 5 remains closed, realizing the rapid retraction of the bracket. It should be noted that the principle of the servo valve 5 can be referred to in patent ZL202211077136.3. This part of the technology is prior art, and its principle will not be described again.

[0027] Specifically, the hydraulic control main valve assembly 2 also includes an electromagnetic pilot valve 8. The hydraulic control main valve 7 is connected to the electromagnetic pilot valve 8. The hydraulic control main valve 7 is provided with an inlet port P1, a return port R1, a working port A1 and a first hydraulic control port X1, and the valve core is provided with a corresponding through hole for liquid flow.

[0028] During operation, the valve core of the hydraulic control main valve 7 switches between the zero position and the working position according to the pilot pressure signal from the first hydraulic control port X1. When there is no high-pressure pilot fluid input to the first hydraulic control port X1, the valve core of the hydraulic control main valve 7 is in the zero position under the action of the return spring. At this time, the working port A1 is connected to the return port R1 and disconnected from the inlet port P1, and the upper chamber of the jack is in a free drainage state. When the first hydraulic control port X1 receives high-pressure pilot fluid, the pilot fluid pressure overcomes the spring force and pushes the valve core of the hydraulic control main valve 7 to the working position. At this time, the working port A1 is connected to the inlet port P1 and disconnected from the return port R1. The high-pressure working fluid is output in large flow through the inlet port P1 to the working port A1 and enters the upper chamber of the jack, realizing the rapid filling and retraction of the upper chamber.

[0029] Specifically, the two-stage hydraulic control check valve 6 includes a push rod 62 that moves within it. The two-stage hydraulic control check valve 6 is also provided with a first-stage small valve core 63 and a second-stage large valve core 64. The second-stage large valve core 64 is reset by a return spring. The first-stage small valve core 63 is located at the end of the second-stage large valve core 64. The two-stage hydraulic control check valve 6 is respectively provided with an outlet R2, a locking port A2, and a second hydraulic control port X2.

[0030] During operation, the two-stage hydraulic control check valve 6 switches between locked and unloaded states based on the pressure signal from the second hydraulic control port X2. In the locked state, no pilot fluid acts on the push rod 62, and the first-stage small valve core 63 and the second-stage large valve core 64 are tightly fitted to the valve seat under the spring preload, with the locking port A2 in a high-pressure sealed state, ensuring that the lower chamber of the jack maintains pressure without leakage. In the unloaded state, the high-pressure pilot fluid enters the second hydraulic control port X2 and pushes the push rod 62 to the left. The push rod 62 first opens the first-stage small valve core 63, forming an initial discharge channel, and some high-pressure fluid leaks through the gap of the small valve core to the outlet R2. The push rod 62 continues to move to the left and simultaneously opens the second-stage large valve core 64, opening the main flow section. A large flow of working fluid instantly rushes into the outlet R2 through the large valve core channel, realizing the staged unloading and rapid emptying of the high-pressure fluid in the lower chamber, effectively avoiding liquid hammer and pressure shock.

[0031] Specifically, the outlet R2 and the locking port A2 form the main liquid flow channel within the valve core 6 of the two-stage hydraulic control check valve.

[0032] During operation, the channel is doubly cut off by the primary small valve core 63 and the secondary large valve core 64 in the locked state, maintaining the high pressure of the system and the precise positioning of the jack; in the unloading state, the two valve cores open in sequence to form a stepped high-flow passage, ensuring that the drainage resistance of the lower chamber is minimal, matching the working condition requirements of rapid jack retraction.

[0033] Specifically, when the valve core of the hydraulic main valve 7 is moved to the working position, the internal through hole precisely aligns the inlet port P1 with the working port A1 to form a high-pressure inlet channel; when reset to the zero position, the through hole switches to align the working port A1 with the return port R1 to form a low-pressure return channel. Specifically, the servo valve assembly 1 is connected to the two-stage hydraulic check valve assembly 3 and the lower chamber of the jack, forming a flow path in the lower chamber of the jack. During liquid supply, the liquid inside the pipeline will flow back to the oil tank through the inlet or outlet. The oil tank will pump out the liquid through the output pump. When the liquid in the lower chamber is working, the liquid can be directly output to the pipeline through the outlet of the servo valve 5 without going through the two-stage hydraulic check valve 6.

[0034] During operation, this flow path forms a precision control loop for the jack's extended position. The proportional flow rate of the working fluid output from the servo valve assembly 1 is smoothly injected into the lower chamber through this path. The stepless control of the inlet flow rate and piston movement speed is achieved through continuous adjustment of the valve core opening. Combined with the locking and pressure-holding function of the two-stage hydraulic check valve assembly 3, it ensures that the jack can accurately stop and finely adjust at any position.

[0035] Specifically, one of the hydraulic control main valves 7 is connected to the upper cavity of the jack to control the back-and-forth flow of liquid inside the upper cavity, forming a flow path in the upper cavity of the jack.

[0036] During operation, this flow path constitutes the main control loop for the inlet and outlet of the upper chamber. In the extended state, the path switches to the return mode, quickly guiding the working fluid in the upper chamber to the oil tank to eliminate back pressure; in the retracted state, the path switches to the inlet mode, providing a large flow of high-pressure fluid to drive the piston rod to retract, working in conjunction with the outlet path of the lower chamber to complete a smooth reversal.

[0037] Specifically, the electromagnetic pilot valve 8 forms a flow path C with one of the hydraulically controlled main valves 7 and the two-stage hydraulically controlled check valves 6.

[0038] During operation, path C serves as the distribution hub for pilot control signals. After receiving instructions from the electronic control system, the electromagnetic pilot valve 8 distributes the high-pressure pilot fluid according to a preset logic to the first hydraulic control port X1 of the hydraulic main valve 7 and the second hydraulic control port X2 of the two-stage hydraulic control check valve 6. The opening and closing of this path directly determines the swivel of the valve core of the hydraulic main valve 7 and the unlocking of the check valve, realizing the cascaded amplification control of "electrical signal → pilot hydraulic signal → mechanical displacement of the main valve / check valve", ensuring the synchronization of the precise adjustment of the support extension and the rapid retraction action and the reliability of the system.

[0039] Working principle: Jack extension control process: The servo valve assembly 1 controller sends a specific opening value (specific opening size), and the servo valve 5, driven by the servo motor 4, opens its valve port to the designated position, allowing high-pressure hydraulic fluid to flow along... Figure 2 The lower A path output to the lower chamber of the jack pushes the piston rod to extend, and the liquid in the upper chamber of the jack returns to port R via the hydraulic control main valve 7 (see attached liquid flow path for the upper chamber of the jack). Figure 2 (The connection path between the top of the jack and the hydraulic main valve core 7 is described in the description). The servo valve controller controls the opening degree of the valve port according to the instructions of the automation system to control the speed and position of the jack's extension.

[0040] Jack retraction control process: The electromagnetic pilot valve 8 receives the controller's action command and sends a hydraulic pressure signal. One path controls the two-stage hydraulic check valve 6 to open its valve core; the other path controls the hydraulic main valve 7 to open its valve core. High-pressure fluid is output along path B to the upper chamber of the jack, pushing the piston rod to retract. Fluid in the lower chamber of the jack returns to port R through the two-stage hydraulic check valve 6. (It should be noted that the servo valve 5 in this part can be in a fully open state or a selective opening state. When the fully open state is selected, when the fluid in the upper chamber of the jack flows back from port R, the fluid in the lower chamber of the jack flows out quickly, completing the rapid reset. If it is necessary to control the return flow speed to achieve controllable return flow, the opening angle of the servo valve 5 can be selectively controlled. When the opening angle changes, the fluid flow rate will naturally change, thereby changing the return flow speed, thus making the jack's descent speed controllable.) This completes the jack retraction action.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mining intrinsically safe electro-hydraulic servo valve, characterized in that, include: Servo valve assembly (1), the servo valve assembly (1) includes a servo motor (4) and a servo valve (5), the servo valve (5) being connected to the lower chamber of the jack; A two-stage hydraulic control check valve assembly (3) includes a two-stage hydraulic control check valve (6), the locking port of which is connected to a servo valve (5). The hydraulic control main valve assembly (2) includes a hydraulic control main valve (7), the working port of which is connected to the upper chamber of the jack; An electromagnetic pilot valve (8) is connected to the hydraulic control port of a two-stage hydraulic control check valve (6). The electromagnetic pilot valve (8) is used to control the opening and closing of the two-stage hydraulic control check valve (6). The electromagnetic pilot valve (8) is connected to the hydraulic control port of a hydraulic control main valve (7). The electromagnetic pilot valve (8) is used to drive the valve core of the hydraulic control main valve (7) to switch between the zero position and the working position. When the jack extends, liquid is injected into the lower chamber of the jack through the servo valve (5). The servo motor (4) drives the valve core of the servo valve (5) to adjust the opening to control the flow rate of the medium in the lower chamber of the jack. The two-stage hydraulic control check valve (6) is locked and pressure is maintained. The valve core of the hydraulic control main valve (7) is in the zero position, and the liquid is discharged from the lower chamber of the jack. When the jack is retracted, the valve core of the hydraulic control main valve (7) is in the working position, injecting liquid into the upper chamber of the jack; the two-stage hydraulic control check valve (6) is fully open to form a large flow return bypass, and the medium in the lower chamber of the jack flows back quickly.

2. The intrinsically safe electro-hydraulic servo valve for mining as described in claim 1, characterized in that; The hydraulic control main valve (7) is provided with an inlet (P1), a return port (R1), a working port (A1) and a first hydraulic control port (X1), and the valve core is provided with a corresponding through hole for liquid flow.

3. The intrinsically safe electro-hydraulic servo valve for mining as described in claim 1, characterized in that; The two-stage hydraulic control check valve (6) includes a push rod (62) that moves within it. The two-stage hydraulic control check valve (6) is also provided with a first-stage small valve core (63) and a second-stage large valve core (64). The second-stage large valve core (64) is reset by a reset spring. The first-stage small valve core (63) is located at the end of the second-stage large valve core (64). The two-stage hydraulic control check valve (6) is provided with an outlet (R2), a lockout port (A2), and a second hydraulic control port (X2).

4. The intrinsically safe electro-hydraulic servo valve for mining according to claim 3, characterized in that; The outlet (R2) and the locking port (A2) form a flow channel.

5. A mining intrinsically safe electro-hydraulic servo valve according to claim 2, characterized in that; The internal through-hole of the hydraulic control main valve (7) forms a flow channel with the inlet (P1) and the return port (R1) respectively.

6. The intrinsically safe electro-hydraulic servo valve for mining according to claim 1, characterized in that; The two-stage hydraulic control check valve assembly (3) integrates at least two two-stage hydraulic control check valve cores (6). The servo valve core (5) is connected to one of the two-stage hydraulic control check valve cores (6) and the lower cavity of the jack, forming a flow path in the lower cavity of the jack.

7. The intrinsically safe electro-hydraulic servo valve for mining according to claim 1, characterized in that; The hydraulic control main valve assembly (2) integrates at least two hydraulic control main valves (7), one of which is connected to the upper cavity of the jack to control the back-and-forth flow of liquid inside the upper cavity, forming a flow path in the upper cavity of the jack.

8. A mining intrinsically safe electro-hydraulic servo valve according to claim 7, characterized in that; The electromagnetic pilot valve (8) forms a pilot control flow path with one of the hydraulic control main valve cores (7) and the two-stage hydraulic control check valve cores (6).

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