Automatic pressure maintaining and flow limiting device for mine grouting and hole sealing and working method of automatic pressure maintaining and flow limiting device

Abstract

The invention discloses a mine grouting hole sealing automatic pressure maintaining and flow limiting device which comprises a two-position three-way electromagnetic valve, a check valve, a pressure sensor, a flow sensor, a control module, a relay module, a display module and a grouting pipeline. The inlet end of the two-position three-way electromagnetic valve is connected with the grouting pump through a connecting pipe, the check valve, the pressure sensor and the flow sensor are sequentially installed on the grouting pipeline in the flowing direction of grout in the grouting pipeline, the two-position three-way electromagnetic valve is connected with the control module through the relay module, and the pressure sensor and the flow sensor are both connected with the control module. The display module is connected with the control module. The problems that in the traditional grouting hole sealing process, the pressure is difficult to control, the flow is unstable, the hole sealing device is damaged due to too large expansion or hole sealing fails due to too small expansion, and the crack sealing effect is poor due to untimely manual intervention are solved, and the construction efficiency and the gas extraction concentration are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of coal mine gas extraction technology, specifically relating to an automatic pressure-maintaining and flow-limiting device for mine grouting and sealing, and its working method. Background Technology

[0002] Gas drainage is a crucial technical aspect of coal mine safety production. By pre-extracting methane gas from the coal seam and surrounding rock, it effectively reduces the methane concentration in underground working areas, thereby preventing explosions caused by gas accumulation. According to statistics from the National Energy Administration, approximately 60% of coal mine gas accidents in my country are directly related to insufficient drainage system efficiency. With the increasing depth of coal mining each year, the pressure and content of coal seam gas have risen significantly. Traditional gas control methods are no longer sufficient to meet the safety requirements of modern mining, placing higher demands on sealing technology and the reliability of drainage devices.

[0003] In the existing technological system, grouting and sealing is a core component of gas extraction. Its core function is to construct a well-sealed borehole channel to prevent air from seeping into the extraction pipeline and diluting the gas concentration, while also preventing gas leakage into the working area through borehole fissures. Currently, the sealing techniques commonly used in the industry have revealed significant technical defects in practical applications: a 2020 industry report from the China Coal Industry Association indicated that approximately 35% of extraction boreholes experienced sealing failures due to improper grouting pressure control. Specifically, insufficient grout penetration when the grouting pressure is insufficient can create leakage channels, while excessive pressure can easily cause the sealing bag to rupture.

[0004] In traditional grouting sealing processes, operators monitor the pressure gauge on the grouting pipeline in real time and manually adjust the valves on the pipeline to control the grouting pressure and flow rate. This structure and operation have the following drawbacks: (1) The pressure control accuracy is low, and the pressure gauge is lagging when manually observed, which can easily lead to the grouting pressure exceeding the limit, causing the sealing failure, the sealing device to break or the rock mass to break. (2) It lacks the function of stopping grouting at specific pressure and flow values, and relies on manual start and stop of the grouting pump, which makes it difficult for managers to intervene in a timely manner and is inefficient; (3) When grouting to seal the cracks in the middle section of the sealing device, secondary grouting is required manually. Relying on the experience of construction personnel is not easy to operate and is not scientific. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an automatic pressure-maintaining and flow-limiting device for mine grouting and sealing, which is easy to operate, highly reliable, highly automated, and provides accurate test data, as well as its operating method.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: an automatic pressure-holding and flow-limiting device for mine grouting and sealing, comprising a two-position three-way solenoid valve, a check valve, a pressure sensor, a flow sensor, a control module, a relay module, a display module, and a grouting pipeline. The inlet end of the grouting pipeline is connected to the outlet A of the two-position three-way solenoid valve. The inlet end of the two-position three-way solenoid valve is connected to the grouting pump through a connecting pipe. The check valve, pressure sensor, and flow sensor are sequentially installed on the grouting pipeline along the grout flow direction. The signal input end of the two-position three-way solenoid valve is connected to the signal output end of the control module through the relay module. The signal output ends of the pressure sensor and the flow sensor are both connected to the signal input end of the control module. The signal input end of the display module is connected to the signal output end of the control module. The flow sensor includes a housing, inside which are a magnetic rotation factor component and a Hall sensor. When the grouting liquid flows through the housing and passes through the magnetic rotation factor component, it drives the propeller-shaped rotor to rotate the magnet. After the magnet rotates, it forms a current with the Hall sensor. The Hall sensor outputs an electrical pulse signal for each revolution, and the electrical pulse signal is transmitted to the control module, which calculates the flow value.

[0007] The control module has a built-in ADC chip to receive and process voltage and pulse signals. The control module receives feedback information from the pressure sensor and flow sensor and outputs high and low levels to the relay module. The relay module and the two-position three-way solenoid valve form a closed circuit. The high and low levels are used to open and close the circuit, thereby switching the outlet A and outlet B of the two-position three-way solenoid valve to determine whether to continue grouting.

[0008] A method for operating an automatic pressure-maintaining and flow-limiting device for mine grouting and sealing, implemented using the automatic pressure-maintaining and flow-limiting device for mine grouting and sealing, includes the following steps: S1. Assemble an automatic pressure-maintaining and flow-limiting device for mine grouting and sealing; S2. Eliminate systematic errors; S3. Test the ultimate grouting pressure and flow rate of the sealing device: S4. Prepare for drilling through layers; S5, Connects the sealing device and the automatic pressure-maintaining and flow-limiting device for mine grouting sealing; S6. Grouting and sealing; S7, Joint sampling.

[0009] Step S2 is as follows: When the control module is working, it carries a weak voltage. This weak voltage is not the output voltage of the pressure sensor, but a system error. The system error can be eliminated by reading the pressure value displayed in the display module and subtracting the pressure value displayed in the display module from the detected pressure value when editing the code in the control module.

[0010] Step S3 is as follows: The inlet of the two-position three-way solenoid valve is connected to the grouting pump via a connecting pipe, and the outlet of the grouting pipeline is connected to the sealing device; the sealing device is inserted into the borehole, the inlet of the two-position three-way solenoid valve is connected to outlet A, the grouting pump is started, and grout is injected into the sealing device through the connecting pipe and the grouting pipe. When the sealing device ruptures, the pressure and flow rate displayed on the display module are recorded; several sets of tests are performed according to the above process, and the ultimate pressure is recorded as the minimum value P among the pressure data sets. min The unit is MPa; the limiting flow rate is denoted as the minimum value L among several sets of flow rate data. min Unit: L; Upper pressure limit: P 上 <P min Unit: MPa; Maximum flow rate: L 上 <L min Unit: L; Lower pressure limit: P 下 <P 上 Unit: MPa; Upper pressure limit: P 上 With the traffic limit L 上 All are compared to the minimum pressure P in several sets of data. min and minimum flow rate L min The smaller size allows for a certain margin of error, preventing the sealing device from expanding too much and breaking during the grouting and sealing process, while also ensuring that the sealing device fully contacts the borehole wall and that the grout effectively seals the cracks in the borehole wall, resulting in a good sealing effect; P 上 L 上 P 下 Adjustments should be made based on the actual site conditions to achieve a good sealing effect; finally, the measured P 上 L 上 P 下 Write the built-in program of the control module.

[0011] Step S4 specifically involves drilling through the layers at the designated location, and then cleaning the holes after the drilling is completed.

[0012] Step S5 specifically involves: preparing the mine grouting sealing automatic pressure-maintaining and flow-limiting device and the sealing device; checking the sealing device for damage; replacing the sealing device promptly if any abnormalities are found; lowering a screen pipe of appropriate length according to the actual conditions of the cross-layer borehole; connecting the lower end of the screen pipe to the extraction pipe passing through the sealing device; and sending the sealing device into the designated position of the cross-layer borehole after connection; adding an appropriate amount of clean water to clean the grouting pump; connecting the grouting pump to the connecting pipe of the automatic pressure-maintaining and flow-limiting device; and connecting the outlet end of the grouting pipeline of the automatic pressure-maintaining and flow-limiting device to the grouting pipes of the two bladders of the sealing device.

[0013] Step S6 specifically involves: starting the grouting pump to inject grout into the two sacs of the sealing device; when the grout pressure inside the sacs, as displayed on the display module, reaches P... 上 The grouting volume displayed by the time or display module reaches L上 At this time, the control module controls the two-position three-way solenoid valve to switch outlet A to outlet B via the relay module, stopping the injection of grout into the fetal sac, shutting off the grouting pump to stop grouting, and tying the grouting pipe of the sealing device, thus completing the fetal sac expansion and sealing; then, the outlet end of the grouting pipe of the automatic pressure-maintaining and flow-limiting device is connected to the grouting pipe of the sealing section between the two fetal sacs, and grout is injected into the sealing section. When the display module shows a pressure value greater than P... 上 At this time, the two-position three-way solenoid valve switches from outlet A to outlet B. Grouting is not injected into the sealing section between the two bladders at this point; instead, grout is injected into the grout storage device. After a certain period, due to the grout sealing the cracks in the borehole wall, the pressure in the sealing section decreases. When the pressure value displayed on the module is less than P... 下 At this time, the outlet B of the two-way three-way solenoid valve is switched to outlet A to continue grouting into the sealing section between the tire bladders. This process is repeated two to three times to maintain dynamic pressure and achieve a good sealing effect. Finally, the grouting pump is turned off to stop grouting, and the grouting pipe of the sealing device is tied.

[0014] Step S7 involves connecting the extraction pipe at the center of the sealing device to the underground gas extraction pipeline in the coal mine, and extracting the gas inside the cross-layer borehole through the screen pipe.

[0015] The working principle of this invention, employing the above technical solution, is as follows: The control module receives and processes signals from the pressure sensor and flow sensor that monitor the grouting pressure in real time. It controls the working state of the relay module by outputting high and low levels, thereby controlling the energization and de-energization of the two-position three-way solenoid valve. The switching between outlet A and outlet B of the two-position three-way solenoid valve determines whether grouting continues. Ultimately, during the grouting and sealing process, the display module monitors and displays grouting pressure and flow information in real time, achieving closed-loop control of the grouting status using both parameters. The grouting pipeline adopts a composite structure of high-pressure resistant rubber tubing and metal braided mesh. Quick-sealing connectors are configured at both the outlet end of the grouting pipeline and the inlet end of the connecting pipe for easy connection. Taking the traditional "two-plug-one-injection" pressurized sealing method as an example, when the grouting pressure and flow rate exceed the upper limit of the set value, grouting stops, and the sealing device expands and seals itself. When the grout seals the middle section and cracks of the sealing device, the grouting pressure decreases. When the pressure is less than the lower limit of the set value, grouting continues; when the pressure exceeds the upper limit of the set value, grouting stops, achieving a pressure-maintaining effect.

[0016] Compared with the prior art, the technical effects of the present invention are as follows: (1) This invention provides a dual-parameter automatic control system for grouting pressure and flow rate. When the set pressure or flow rate is reached, grouting stops; when the pressure is less than the set pressure value, grouting continues, thus realizing pressure-flow coordinated control of grouting. This solves the technical problems of large manual operation errors, difficulty in controlling grouting pressure and flow rate, slow abnormal response causing excessive expansion and damage to the sealing device or insufficient sealing device failure, and poor crack sealing effect during the grouting and sealing process; it can significantly improve construction efficiency and gas extraction concentration.

[0017] (2) When sealing the crack in the sealing section between the two bladders of the sealing device, the grouting pressure can be automatically adjusted to keep the grouting pressure within a certain range, so as to achieve "secondary sealing" and "tertiary sealing", and finally ensure the sealing reliability of the sealing device.

[0018] In summary, this invention solves the problems of poor pressure control, unstable flow rate, and untimely manual intervention in the traditional grouting and sealing process, which lead to excessive expansion and damage of the sealing device or insufficient sealing effect due to insufficient expansion, and poor crack sealing effect. It significantly improves construction efficiency and gas extraction concentration. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is the control logic diagram of the present invention. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] like Figure 1 and Figure 2 As shown, an automatic pressure-maintaining and flow-limiting device for mine grouting and sealing according to the present invention includes a two-position three-way solenoid valve 1, a check valve 2, a pressure sensor 3, a flow sensor 4, a control module 5, a relay module 6, a display module 7, and a grouting pipeline 8. The inlet end of the grouting pipeline 8 is connected to the outlet A of the two-position three-way solenoid valve 1. The inlet end of the two-position three-way solenoid valve 1 is connected to the grouting pump through a connecting pipe 9. The check valve 2, pressure sensor 3, and flow sensor 4 are sequentially installed on the grouting pipeline 8 along the grout flow direction. The signal input end of the two-position three-way solenoid valve 1 is connected to the signal output end of the control module 5 through the relay module 6. The signal output ends of the pressure sensor 3 and the flow sensor 4 are both connected to the signal input end of the control module 5. The signal input end of the display module 7 is connected to the signal output end of the control module 5.

[0022] The flow sensor 4 includes a housing, inside which are a magnetic rotation factor component and a Hall sensor. When the grouting liquid flows through the housing and passes through the magnetic rotation factor component, it drives the propeller-shaped rotor to rotate the magnet. After the magnet rotates, it forms a current with the Hall sensor. The Hall sensor outputs an electrical pulse signal for each revolution. The electrical pulse signal is transmitted to the control module 5, and the control module 5 calculates the flow value.

[0023] The control module 5 has a built-in ADC chip to receive and process voltage and pulse signals. The control module 5 receives information from the pressure sensor 3 and the flow sensor 4 and outputs high and low levels to the relay module 6. The relay module 6 and the two-position three-way solenoid valve 1 form a closed circuit. The circuit is turned on and off by using high and low levels, thereby switching the outlet A and outlet B of the two-position three-way solenoid valve 1 to determine whether to continue grouting.

[0024] A method for operating an automatic pressure-maintaining and flow-limiting device for mine grouting and sealing, implemented using the automatic pressure-maintaining and flow-limiting device for mine grouting and sealing, includes the following steps: S1. Assemble an automatic pressure-maintaining and flow-limiting device for mine grouting and sealing; S2. Eliminate systematic errors; S3. Test the ultimate grouting pressure and flow rate of the sealing device: S4. Prepare for drilling through layers; S5, Connects the sealing device and the automatic pressure-maintaining and flow-limiting device for mine grouting sealing; S6. Grouting and sealing; S7, Joint sampling.

[0025] Step S2 is as follows: When the control module 5 is working, it carries a weak voltage. This weak voltage is not the output voltage of the pressure sensor 3, but a system error. The pressure value displayed in the display module 7 is read. When editing the code in the control module 5, the system error can be eliminated by subtracting the pressure value displayed in the display module 7 from the detected pressure value.

[0026] Step S3 is as follows: The inlet of the two-position three-way solenoid valve 1 is connected to the grouting pump via the connecting pipe 9, and the outlet of the grouting pipe 8 is connected to the sealing device; the sealing device is inserted into the borehole, the inlet of the two-position three-way solenoid valve 1 is connected to the outlet A, the grouting pump is started, and grout is injected into the sealing device through the connecting pipe 9 and the grouting pipe. When the sealing device ruptures, the pressure and flow rate displayed on the display module 7 are recorded; several sets of tests are performed according to the above process, and the ultimate pressure is recorded as the minimum value P among the pressure data sets. min The unit is MPa; the limiting flow rate is denoted as the minimum value L among several sets of flow rate data. min Unit: L; Upper pressure limit: P 上 <P min Unit: MPa; Maximum flow rate: L 上 <L min Unit: L; Lower pressure limit: P 下 <P 上 Unit: MPa; Upper pressure limit: P 上 With the traffic limit L 上 All are compared to the minimum pressure P in several sets of data. min and minimum flow rate L minThe smaller size allows for a certain margin of error, preventing the sealing device from expanding too much and breaking during the grouting and sealing process, while also ensuring that the sealing device fully contacts the borehole wall and that the grout effectively seals the cracks in the borehole wall, resulting in a good sealing effect; P 上 L 上 P 下 Adjustments should be made based on the actual site conditions to achieve a good sealing effect; finally, the measured P 上 L 上 P 下 Write the built-in program to control module 5.

[0027] Step S4 specifically involves drilling through the layers at the designated location, and then cleaning the holes after the drilling is completed.

[0028] Step S5 specifically involves: preparing the mine grouting sealing automatic pressure-maintaining and flow-limiting device and the sealing device; checking the sealing device for damage; replacing the sealing device promptly if any abnormalities are found; lowering a screen pipe of appropriate length according to the actual conditions of the cross-layer borehole; connecting the lower end of the screen pipe to the extraction pipe passing through the sealing device; and sending the sealing device into the designated position of the cross-layer borehole after connection; adding an appropriate amount of clean water to clean the grouting pump; connecting the grouting pump to the connecting pipe 9 of the automatic pressure-maintaining and flow-limiting device; and connecting the outlet end of the grouting pipeline 8 of the automatic pressure-maintaining and flow-limiting device to the grouting pipes of the two bladders of the sealing device.

[0029] Step S6 specifically involves: starting the grouting pump to inject grout into the two sacs of the sealing device; when the grout pressure inside the sacs displayed on the display module 7 reaches P... 上 The grouting volume displayed by the time or display module 7 reaches L 上 At this time, control module 5 controls the two-position three-way solenoid valve 1 via relay module 6 to switch outlet A to outlet B, stopping grout injection into the fetal sac, shutting off the grouting pump to stop grouting, and tying the grouting pipe of the sealing device, thus completing the fetal sac expansion and sealing; subsequently, the outlet end of the grouting pipe 8 of the automatic pressure-maintaining and flow-limiting device is connected to the grouting pipe of the sealing section between the two fetal sacs, and grout is injected into the sealing section. When the display module 7 shows a pressure value greater than P... 上 At this time, the outlet A of the two-position three-way solenoid valve 1 switches to outlet B. Grouting is not injected into the sealing section between the two bladders at this point; instead, grout is injected into the grout storage device. After a certain period, due to the grout sealing the cracks in the borehole wall, the pressure in the sealing section decreases. When the pressure value displayed on the display module 7 is less than P... 下 At this time, switch the outlet B of the two-position three-way solenoid valve 1 to outlet A and continue to inject grout into the sealing section between the tire bladders. Repeat this two to three times to maintain dynamic pressure and achieve a good sealing effect. Finally, turn off the grouting pump to stop grouting and tie the grouting pipe of the sealing device.

[0030] Step S7 involves connecting the extraction pipe at the center of the sealing device to the underground gas extraction pipeline in the coal mine, and extracting the gas inside the cross-layer borehole through the screen pipe.

[0031] 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An automatic pressure-maintaining and flow-limiting device for mine grouting and sealing, characterized in that: The system includes a two-position three-way solenoid valve, a check valve, a pressure sensor, a flow sensor, a control module, a relay module, a display module, and a grouting pipeline. The inlet end of the grouting pipeline is connected to the outlet A of the two-position three-way solenoid valve. The inlet end of the two-position three-way solenoid valve is connected to the grouting pump through a connecting pipe. The check valve, pressure sensor, and flow sensor are installed sequentially along the grout flow direction in the grouting pipeline. The signal input end of the two-position three-way solenoid valve is connected to the signal output end of the control module through the relay module. The signal output ends of the pressure sensor and the flow sensor are both connected to the signal input end of the control module. The signal input end of the display module is connected to the signal output end of the control module.

2. The automatic pressure-maintaining and flow-limiting device for mine grouting and sealing, and its working method, as described in claim 1, is characterized in that: The flow sensor includes a housing, inside which are a magnetic rotation factor component and a Hall sensor. When the grouting liquid flows through the housing and passes through the magnetic rotation factor component, it drives the propeller-shaped rotor to rotate the magnet. After the magnet rotates, it forms a current with the Hall sensor. The Hall sensor outputs an electrical pulse signal for each revolution, and the electrical pulse signal is transmitted to the control module, which calculates the flow value.

3. The automatic pressure-maintaining and flow-limiting device for mine grouting and sealing according to claim 2, characterized in that: The control module has a built-in ADC chip to receive and process voltage and pulse signals. The control module receives feedback information from the pressure sensor and flow sensor and outputs high and low levels to the relay module. The relay module and the two-position three-way solenoid valve form a closed circuit. The high and low levels are used to open and close the circuit, thereby switching the outlet A and outlet B of the two-position three-way solenoid valve to determine whether to continue grouting.

4. A method for operating an automatic pressure-holding and flow-limiting device for mine grouting and sealing, implemented using the automatic pressure-holding and flow-limiting device for mine grouting and sealing as described in claim 4, characterized in that: Includes the following steps: S1. Assemble an automatic pressure-maintaining and flow-limiting device for mine grouting and sealing; S2. Eliminate systematic errors; S3. Test the ultimate grouting pressure and flow rate of the sealing device: S4. Prepare for drilling through layers; S5, Connects the sealing device and the automatic pressure-maintaining and flow-limiting device for mine grouting sealing; S6. Grouting and sealing; S7, Joint sampling.

5. The working method of the automatic pressure-maintaining and flow-limiting device for mine grouting and sealing according to claim 4, characterized in that: Step S2 is as follows: When the control module is working, it carries a weak voltage. This weak voltage is not the output voltage of the pressure sensor, but a system error. The system error can be eliminated by reading the pressure value displayed in the display module and subtracting the pressure value displayed in the display module from the detected pressure value when editing the code in the control module.

6. The working method of the automatic pressure-maintaining and flow-limiting device for mine grouting and sealing according to claim 4, characterized in that: Step S3 is as follows: Connect the inlet of the two-position three-way solenoid valve to the grouting pump via a connecting pipe, and connect the outlet of the grouting pipeline to the sealing device; insert the sealing device into the borehole, connect the inlet of the two-position three-way solenoid valve to outlet A, start the grouting pump, and inject grout into the sealing device through the connecting pipe and grouting pipe. When the sealing device ruptures, record the pressure and flow rate displayed on the display module; repeat the above process for several sets of tests, and record the ultimate pressure as the minimum value P among the pressure data sets. min Unit: MPa; The limiting flow rate is denoted as the minimum value L among several sets of flow rate data. min Unit: L; Upper pressure limit: P 上 <P min Unit: MPa; Flow rate Upper limit L 上 <L min Unit: L; Lower pressure limit: P 下 <P 上 Unit: MPa; Upper pressure limit: P 上 With the traffic limit L 上 All are compared to the minimum pressure P in several sets of data. min and minimum flow rate L min The smaller size allows for a certain margin of error, preventing the sealing device from expanding too much and breaking during the grouting and sealing process, while also ensuring that the sealing device fully contacts the borehole wall and that the grout effectively seals the cracks in the borehole wall, resulting in a good sealing effect; P 上 L 上 P 下 Adjustments should be made based on the actual site conditions to achieve a good sealing effect; finally, the measured P 上 L 上 P 下 Write the built-in program of the control module.

7. The working method of the automatic pressure-maintaining and flow-limiting device for mine grouting and sealing according to claim 4, characterized in that: Step S4 specifically involves drilling through the layers at the designated location, and then cleaning the holes after the drilling is completed.

8. The working method of the automatic pressure-maintaining and flow-limiting device for mine grouting and sealing according to claim 4, characterized in that: Step S5 specifically involves: preparing the mine grouting sealing automatic pressure-maintaining and flow-limiting device and the sealing device; checking the sealing device for damage; replacing the sealing device promptly if any abnormalities are found; lowering a screen pipe of appropriate length according to the actual conditions of the cross-layer borehole; connecting the lower end of the screen pipe to the extraction pipe passing through the sealing device; and sending the sealing device into the designated position of the cross-layer borehole after connection; adding an appropriate amount of clean water to clean the grouting pump; connecting the grouting pump to the connecting pipe of the automatic pressure-maintaining and flow-limiting device; and connecting the outlet end of the grouting pipeline of the automatic pressure-maintaining and flow-limiting device to the grouting pipes of the two bladders of the sealing device.

9. The working method of the automatic pressure-maintaining and flow-limiting device for mine grouting and sealing according to claim 4, characterized in that: Step S6 specifically involves: starting the grouting pump to inject grout into the two sacs of the sealing device; when the grout pressure inside the sacs, as displayed on the display module, reaches P... 上 The grouting volume displayed by the time or display module reaches L 上 At this time, the control module controls the two-position three-way solenoid valve to switch outlet A to outlet B via the relay module, stopping the injection of grout into the fetal sac, shutting off the grouting pump to stop grouting, and tying the grouting pipe of the sealing device, thus completing the fetal sac expansion and sealing; then, the outlet end of the grouting pipe of the automatic pressure-maintaining and flow-limiting device is connected to the grouting pipe of the sealing section between the two fetal sacs, and grout is injected into the sealing section. When the display module shows a pressure value greater than P... 上 At this time, the two-position three-way solenoid valve switches from outlet A to outlet B. Grouting is not injected into the sealing section between the two bladders at this point; instead, grout is injected into the grout storage device. After a certain period, due to the grout sealing the cracks in the borehole wall, the pressure in the sealing section decreases. When the pressure value displayed on the module is less than P... 下 At this time, the outlet B of the two-way three-way solenoid valve is switched to outlet A to continue grouting into the sealing section between the tire bladders. This process is repeated two to three times to maintain dynamic pressure and achieve a good sealing effect. Finally, the grouting pump is turned off to stop grouting, and the grouting pipe of the sealing device is tied.

10. The working method of the automatic pressure-maintaining and flow-limiting device for mine grouting and sealing according to claim 4, characterized in that: Step S7 involves connecting the extraction pipe at the center of the sealing device to the underground gas extraction pipeline in the coal mine, and extracting the gas inside the cross-layer borehole through the screen pipe.

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