Electromagnetic drive type coal seam gas in-situ pressure maintaining coring device and method without lifting drill

Abstract

The invention discloses an electromagnetic drive type coal seam gas in-situ pressure maintaining coring device and method without lifting a drill. The device comprises a double-barrel drill rod, a coring bag, an intelligent drill bit and a control system. An electromagnetic driving coil is arranged in the double-barrel drill rod, a permanent magnet is embedded in the outer wall of the coring bag, a mechanical opposite-opening locking door is arranged at the front end of the coring bag, and a material guiding door opening barrel and an iris opening and closing mechanism capable of being remotely controlled are arranged in the intelligent drill bit. The coring method comprises the following steps: after drilling to a target depth, the electromagnetic driving coil is electrified to generate a magnetic field to push the coring capsule to migrate, and the locking door is jacked open by the material guide door opening cylinder; starting the drilling tool to enable the coal core to enter the coring capsule; after coring is completed, the current direction of the coil is changed, reverse magnetic force is generated, the coring bag is pulled back, and the mechanical opposite-opening locking door is automatically closed to achieve pressure maintaining; and the coring capsule slides out of the drill rod. The intelligent drill bit is remotely controlled, the automation degree is high, in-situ and pressure-maintaining coring without lifting the drill bit is achieved, gas dissipation and time consumption caused by lifting the drill bit are thoroughly avoided, and the coring efficiency, the gas retaining amount and the sample authenticity are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of mineral geological exploration and gas control technology, specifically relating to an electromagnetically driven, non-drilling coal seam gas in-situ pressure-maintaining coring device and method. Background Technology

[0002] High-tech mineral geological exploration often involves drilling and sampling of strata. Accurately obtaining the gas content, pressure, and composition of coal seams underground is crucial for assessing gas hazard risks and designing gas drainage systems. Obtaining pressure-retaining, uncirculated coal cores is usually the most direct and reliable means of achieving this goal. Currently, the mainstream technology involves drilling to the target depth using conventional coring tools, then pulling the drill string out to replace it with a specialized pressure-retaining sampler, and then drilling down again for sampling. This process is cumbersome, time-consuming, and labor-intensive. Furthermore, the drastic changes in pressure and temperature at the bottom of the hole during drilling can easily lead to significant desorption and escape of gas from the coal core, causing the sample to lose its in-situ representativeness and resulting in significantly lower measured values.

[0003] To address the issue of coring without drilling, existing technologies have proposed solutions such as wireline-guided coring devices. However, these still require dedicated inner tubes for deployment and retrieval, which are prone to clogging in complex coal seams and have limited pressure-holding capabilities. Other solutions attempt to integrate sampling valves within the drill pipe, but these are structurally complex, have poor reliability in coal dust contamination environments, and struggle to achieve true "in-situ sealing" and "pressure maintenance."

[0004] Therefore, there is an urgent need for a coring device and method that can be integrated into the drill string, can be remotely controlled to achieve in-situ triggering after drilling, and can reliably seal and maintain gas pressure. Summary of the Invention

[0005] To solve the above-mentioned technical problems, this invention provides an electromagnetically driven, non-drilling coal seam gas in-situ pressure-maintaining coring device and method; it can directly complete the cutting, collection, and pressure-maintaining sealing of coal cores at the target depth in a single drilling operation without the need to lift the drill, thus maximizing the preservation of the in-situ gas state of the coal cores and significantly improving coring efficiency and sample authenticity.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: an electromagnetically driven in-situ pressure-maintaining coring device for coal seam gas without drilling, comprising a double-cylinder drill rod, a coring bag, an intelligent drill bit, and an external control system; The twin-cylinder drill rod consists of an outer cylinder and an inner cylinder coaxially mounted, forming an annular cavity between them. A spiral electromagnetic drive coil is installed within the annular cavity. The inner cylinder serves as the operating channel for the core sampling chamber. The core sampling chamber is slidably positioned within the inner cylinder, with a permanent magnet embedded in its outer wall. The front end of the core sampling chamber is open and equipped with a mechanically double-locking door. An intelligent drill bit is connected to the front end of the twin-cylinder drill rod. The intelligent drill bit includes a cylindrical drill bit body, within which is an iris opening and closing mechanism and a material guide opening cylinder located behind the iris opening and closing mechanism. The material guide opening cylinder is used to open the mechanically double-locking door to allow the coal sample to enter the core sampling chamber. The drill bit body has several circumferentially arrayed slag guide holes located in front of the iris opening and closing mechanism. An external control system is used to adjust the magnitude and direction of the current in the electromagnetic drive coil and to control the opening and closing of the iris opening and closing mechanism.

[0007] The outer cylinder has a spiral drill blade on its outer circumference for discharging slag out of the borehole. The annular cavity between the outer and inner cylinders is filled with an insulating cooling medium for heat dissipation and insulation protection of the electromagnetic drive coil. The front and rear ends of the double-cylinder drill rod are respectively provided with coil connection holes that communicate with the front and rear ends of the annular cavity. The inner wall of the inner cylinder has an anti-rotation guide groove along its length, and the outer circumference of the core scavenging bag is provided with a guide strip that is slidably connected in the anti-rotation guide groove.

[0008] The core extraction capsule includes a cylindrical shell with an open front end. A pressure-holding chamber is pre-installed inside the cylindrical shell, and the inner wall of the pressure-holding chamber is coated with an absorbent material layer. The mechanical double-locking doors include two sets of elastic telescopic doors symmetrically arranged about the center line of the core extraction capsule. The open end of the cylindrical shell has guide grooves with opposite openings inside. Each set of elastic telescopic doors includes a door body and a compression spring. The plane of the door body is perpendicular to the center line of the core extraction capsule. The door body slides in the guide groove. The two ends of the compression spring are respectively pressed and connected to the bottom of the guide groove and the inner end of the door body. The contact sides of the door bodies of the two sets of elastic telescopic doors are pressed and fitted together. The front side of the two door bodies outside the guide groove has a sloping structure.

[0009] The iris opening and closing mechanism includes a mounting base coaxially fixed to the rear side of the inner circle of the drill bit body. The mounting base has a coaxial channel at its center that is open from front to back and corresponds to and communicates with the feed gate. The front end of the feed gate is fixedly connected to the rear end of the mounting base. The inner diameter of the coaxial channel is equal to the inner diameter of the feed gate. Two axial-to-radial drive protrusions are symmetrically arranged at the center of the outer circle of the rear end of the feed gate. The cross-sectional profile of the axial-to-radial drive protrusions is V-shaped. The mounting base contains a wireless signal receiver, two independent power supplies, and two explosion-proof motors. Each independent power supply powers one explosion-proof motor. A bevel gear disk with the same centerline as the drill bit body is rotatably mounted on the front side of the mounting base. The two explosion-proof motors are symmetrically arranged about the centerline of the drill bit body. Each explosion-proof motor's spindle is equipped with a driving bevel gear, and both driving bevel gears mesh with the bevel gear disk. Six baffles are arranged in a circumferential array around the centerline of the drill bit body on the rear side of the bevel gear disk. The baffles are all rectangular and triangular in shape. A regular hexagonal groove is provided on the rear side of the conical toothed disc. A front sliding post is fixed to the front rectangular surface of each baffle. Six front sliding posts slide within each side of the regular hexagonal groove. Six connecting rods are arranged in a circular array around the center line of the drill bit body on the front side of the six baffles on the mounting base. Each connecting rod is tangent to the inner circle of the core sampling channel. A strip-shaped groove is provided in the middle of each connecting rod, with the length of the groove along the length of the connecting rod. A rear sliding post is fixed to the rear rectangular surface of each baffle. Each rear sliding post extends into and slides within a strip-shaped groove. When each rear sliding post slides to the end of the corresponding strip-shaped groove closest to the core sampling channel, the triangular sides of the six baffles sequentially connect to block and close the core sampling channel. When each rear sliding post slides to the end of the corresponding strip-shaped groove furthest from the core sampling channel, the triangular sides of the six baffles separate, and the core sampling channel becomes open from front to back.

[0010] A rear-end open mounting cavity is provided between the rear side of the drill bit body and the outer circle of the guide gate. A buffer spring and a buffer plate are fitted inside the mounting cavity and are sleeved on the outside of the guide gate. An inner guide cylinder that is slidably connected to the outer circle of the guide gate is fixed on the inner circle of the buffer plate, and an outer guide cylinder that is slidably connected to the inner circle of the rear side of the drill bit body is fixed on the outer circle of the buffer plate. The front and rear ends of the buffer spring are respectively pressed into the rear end face of the mounting seat and the front side face of the buffer plate.

[0011] The electromagnetic-driven, non-drilling-lift coal seam gas in-situ pressure-maintaining coring method, implemented using an electromagnetic-driven, non-drilling-lift coal seam gas in-situ pressure-maintaining coring device, includes the following steps: S1. The intelligent drill bit is threaded to the front end of the first section of the double-barrel drill rod. Then, several drill rods are connected in series, and the electromagnetic drive coils in the adjacent double-barrel drill rods are connected in series. The drilling machine is started to drive the double-barrel drill rods and the intelligent drill bit to drill to the predetermined core drilling depth of the coal seam. During the drilling process, the coal slag is discharged outward through multiple slag guide holes on the drill bit body and the spiral drill blades on the outer cylinder. S2. A positive current is passed into the electromagnetic drive coil, and the electromagnetic drive coil generates a magnetic field to drive the permanent magnet in the core sac to slide along the inner cylinder toward the intelligent drill bit. S3. When the core scavenging bag slides to the rear end of the guide gate, the guide gate will open the mechanical double-locking door at the front end of the core scavenging bag. S4. The system remotely sends commands through an external control system. The wireless signal receiver inside the mounting base receives the commands and controls the iris opening and closing mechanism of the smart drill bit to open. S5. The drilling rig is started briefly and slightly. The drilling rig drives the double-cylinder drill rod and the intelligent drill bit to rotate. The coal core drilled by the intelligent drill bit enters the core scavenging chamber through the iris opening and closing mechanism, the material guide opening cylinder, and the core scavenging port. S6. When the core sampling index reaches the preset value, the external control system remotely sends a closing command to control the iris opening and closing mechanism to close, and the six baffles cut the coal core and close the core sampling channel. S7. A reverse current is passed into the electromagnetic drive coil. The electromagnetic drive coil generates a reverse magnetic field to drive the permanent magnet in the core retrieval bag to slide along the inner cylinder toward the borehole opening. The mechanical double-locking door at the front end of the core retrieval bag disengages from the guide opening cylinder. The two doors close under the action of their respective compression springs, keeping the core retrieval bag pressure-sealed. S8. When the core retrieval bag moves close to the borehole opening, adjust the coil current to brake and decelerate the core retrieval bag. S9. After the core scavenger is moved to the end of the last section of the double-barrel drill pipe, the core scavenger is removed to complete the sampling.

[0012] Step S3 is as follows: The inclined surfaces of the two axial-to-radial drive protrusions on the outer circle of the rear end of the guide opening cylinder press against the inclined surface structures on the front side of the two sets of elastic telescopic gate bodies respectively. The axial movement of the core-taking bladder is converted into radial thrust. The radial thrust drives the gate body to overcome the elastic force of the compression spring and move outward along the guide groove until the axial-to-radial drive protrusion is located on the rear side of the gate body. At this point, the positive current is stopped from being supplied to the electromagnetic drive coil, and the two gate bodies are opened, that is, the core-taking port of the core-taking bladder is opened.

[0013] Step S4 is as follows: Two explosion-proof motors start and synchronously drive the active bevel gear to rotate in the forward direction. The active bevel gear drives the meshing bevel gear disk to rotate. The regular hexagonal groove behind the bevel gear disk simultaneously drives the front sliding column on the front side of the six baffles to move. The rear sliding column on the rear side of the six baffles moves away from the core extraction channel in the corresponding strip groove until the rear sliding column moves to the end of the strip groove that is far from the core extraction channel. At this time, the two explosion-proof motors are turned off. At this time, the core extraction channel is fully opened, and the core extraction port at the front of the core extraction bag, the guide gate, and the front and rear of the core extraction channel are transparent.

[0014] Step S6 is as follows: Two explosion-proof motors start and synchronously drive the active bevel gear to rotate in the opposite direction. The active bevel gear drives the meshing bevel gear disk to rotate. The regular hexagonal groove behind the bevel gear disk simultaneously drives the front sliding column on the front side of the six baffles to move. The rear sliding column on the rear side of the six baffles moves towards the core extraction channel in the corresponding strip groove. When the rear sliding column moves to the end of the strip groove that is closer to the core extraction channel, the two explosion-proof motors are turned off. At this time, the triangular sides of the six baffles connect in sequence to block and close the core extraction channel.

[0015] By adopting the above technical solution, compared with the prior art, the present invention has the following technical effects: 1) When the mechanical double-locking door at the front end of the core extraction chamber is not subjected to external force, it remains closed and locked under the action of the compression spring. When subjected to the axial force of the axial-radial drive protrusion of the outer circle of the guide opening cylinder, part of the radial separation drives the two door bodies to open, thereby realizing the automatic opening of the core extraction port.

[0016] 2) The buffer spring and buffer plate are designed to reduce the impact on the guide gate cylinder when the core scavenging bag slides from back to front.

[0017] 3) The anti-rotation guide groove on the inner wall of the inner cylinder slides in conjunction with the guide strip on the outer circle of the core scoop, ensuring that the core scoop does not rotate when sliding inside the inner cylinder. The inclined structure of the two doors at the front end of the core scoop is symmetrically provided with two axial-radial drive protrusions at the center of the outer circle at the rear end of the guide opening cylinder, which corresponds one-to-one, thereby ensuring the stability and reliability of opening the mechanical double-locking door.

[0018] 4) The inner wall of the pressure-holding chamber of the core-taking bag is coated with an adsorbent material coating 204, which can adsorb the gas escaping from the coal core.

[0019] 5) The external control system can provide the electromagnetic drive coil with pulse current that is adjustable in direction and magnitude, and can send wireless control signals to the wireless signal receiver in the intelligent drill bit assembly to control the opening and closing of the two explosion-proof motors.

[0020] 6) The iris opening and closing mechanism uses two active bevel gears to drive a bevel gear disk to rotate simultaneously. A regular hexagonal groove is opened on the rear side of the bevel gear disk to drive the movement of six front sliding columns. At the same time, the rear sliding column moves in the strip groove, thereby limiting the six baffles to run according to the specified trajectory, thereby realizing the opening or closing of the core extraction channel.

[0021] In summary, this invention integrates an electromagnetic drive unit with a built-in mechanical actuator, enabling remote control and a high degree of automation. It achieves the direct grabbing and sealing of coal cores at the bottom of the borehole, achieving the goal of in-situ, pressure-maintaining core extraction without lifting the drill. This completely avoids gas escape and time loss caused by drill lifting operations, significantly improving core extraction efficiency, gas retention, and sample authenticity. Attached Figure Description

[0022] Figure 1 This is a schematic cross-sectional view of the overall structure of the device of the present invention; Figure 2 for Figure 1 Enlarged detailed view of the intelligent drill bit; Figure 3 This is a cross-sectional schematic diagram of the iris opening and closing mechanism when it is open; Figure 4 This is a schematic diagram of the cross-section of the iris opening and closing mechanism when the core extraction channel is closed. Figure 5 for Figure 1 A schematic cross-sectional view of the core extraction capsule structure; Figure 6 This is a schematic diagram of the structure of the two frontmost sections of the double-cylinder drill rod connected in series. Figure 7 This is a schematic diagram of the front or rear face of a twin-cylinder drill pipe. Detailed Implementation

[0023] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0024] like Figures 1-7 As shown, the electromagnetically driven, non-drilling coal seam gas in-situ pressure-maintaining coring device of the present invention includes a double-cylinder drill rod 39, a coring bag 1, an intelligent drill bit 2, and an external control system. The double-cylinder drill rod 39 includes an outer cylinder 3 and an inner cylinder 4 coaxially mounted, forming an annular cavity 5 between the outer cylinder 3 and the inner cylinder 4. A spiral electromagnetic drive coil 6 is installed in the annular cavity 5. The inner cylinder 4 serves as the operating channel for the core sampling bag 1. The core sampling bag 1 is slidably disposed in the inner cylinder 4. A permanent magnet 7 is embedded in the outer wall of the core sampling bag 1. The front end of the core sampling bag 1 is open and equipped with a mechanical double-locking door. The intelligent drill bit 2 is connected to the front end of the double-cylinder drill rod 39. The intelligent drill bit 2 includes a cylindrical drill bit body 8. The drill bit body 8 is equipped with an iris opening and closing mechanism and a material guide opening cylinder 9 located behind the iris opening and closing mechanism. The material guide opening cylinder 9 is used to open the mechanical double-locking door to allow the coal sample to enter the core sampling bag 1. Several slag guide holes 10 are arranged in a circular array on the drill bit body 8. The slag guide holes 10 are located in front of the iris opening and closing mechanism. An external control system is used to adjust the magnitude and direction of the current of the electromagnetic drive coil 6 and to control the opening and closing of the iris opening and closing mechanism.

[0025] The outer cylinder 3 is provided with a spiral drill blade 11 for discharging slag to the outside of the borehole. The annular cavity 5 between the outer cylinder 3 and the inner cylinder 4 is filled with an insulating cooling medium for heat dissipation and insulation protection of the electromagnetic drive coil 6. The front and rear ends of the double-cylinder drill rod 39 are respectively provided with coil connection through holes 12 that communicate with the front and rear ends of the annular cavity 5. The inner wall of the inner cylinder 4 is provided with an anti-rotation guide groove 13 along the length direction. The outer circle of the core sac 1 is provided with a guide strip 14 that is slidably connected in the anti-rotation guide groove 13.

[0026] The core extraction bag 1 includes a cylindrical shell 15 with an open front end. A pressure-holding chamber 16 is pre-set inside the cylindrical shell 15. The inner wall of the pressure-holding chamber 16 is coated with an absorbent material layer. The mechanical double-opening locking door includes two sets of elastic telescopic doors symmetrically arranged about the center line of the core extraction bag 1. The open end of the cylindrical shell 15 has a guide groove 17 with opposite openings. Each set of elastic telescopic doors includes a door body 18 and a compression spring 19. The plane of the door body 18 is perpendicular to the center line of the core extraction bag 1. The door body 18 is slidably disposed in the guide groove 17. The two ends of the compression spring 19 are respectively pressed and connected to the bottom of the guide groove 17 and the inner end of the door body 18. The door bodies 18 of the two sets of elastic telescopic doors are pressed and fitted together on the contact side. The front side of the two door bodies 18 outside the guide groove 17 is a sloping structure 40.

[0027] The iris opening and closing mechanism includes a mounting base 20 coaxially fixed to the rear side of the inner circle of the drill bit body 8. The mounting base 20 has a coaxial channel 21 at its center, which is open from front to back and corresponds to and communicates with the feed gate 9. The front end of the feed gate 9 is fixedly connected to the rear end of the mounting base 20. The inner diameter of the coaxial channel 21 is equal to the inner diameter of the feed gate 9. Two axial-to-radial drive protrusions 22 are symmetrically arranged at the center of the outer circle of the rear end of the feed gate 9. The cross-sectional profile of the axial-to-radial drive protrusions 22 is V-shaped. A wireless signal receiver 2 is located inside the mounting base 20. 3. Two independent power supplies 24 and two explosion-proof motors 25. Each independent power supply 24 supplies power to one explosion-proof motor 25. Inside the mounting base 20, a bevel gear disk 26 with the same centerline as the drill bit body 8 is rotatably mounted on the front side. The two explosion-proof motors 25 are symmetrically arranged about the centerline of the drill bit body 8. Each explosion-proof motor 25 has a drive bevel gear 27 mounted on its spindle. Both drive bevel gears 27 mesh with the bevel gear disk 26. The rear side of the bevel gear disk 26 has six baffles 28 arranged in a circumferential array around the centerline of the drill bit body 8. Each baffle 28... All 8 are rectangular and triangular in shape. A regular hexagonal groove 29 is provided on the rear side of the conical toothed disc 26. A front sliding post 30 is fixed to the front rectangular surface of each baffle 28. The six front sliding posts 30 are slidably positioned within each side of the regular hexagonal groove 29. Six connecting rods 31 are arranged in a circumferential array around the center line of the drill bit body 8 on the front side of the six baffles 28 on the mounting base 20. Each connecting rod 31 is tangent to the inner circle of the core extraction channel 21. A strip-shaped groove 32 is provided in the middle of each connecting rod 31, with the length of the strip-shaped groove 32 extending along the connecting rod. Along the length of the connecting rod 31, each baffle 28 has a fixed rear sliding post 33 on its rear rectangular surface. Each rear sliding post 33 extends into and slides within a strip groove 32. When each rear sliding post 33 slides to the end of the corresponding strip groove 32 that is closer to the core extraction channel 21, the triangular sides of the six baffles 28 connect in sequence to block and close the core extraction channel 21. When each rear sliding post 33 slides to the end of the corresponding strip groove 32 that is farther from the core extraction channel 21, the triangular sides of the six baffles 28 separate, and the core extraction channel 21 becomes open from front to back.

[0028] A mounting cavity 34 with an open rear end is provided between the rear side of the drill bit body 8 and the outer circle of the guide gate cylinder 9. A buffer spring 35 and a buffer plate 36 are provided inside the mounting cavity 34 and are sleeved on the outside of the guide gate cylinder 9. An inner guide cylinder 37 that is slidably connected to the outer circle of the guide gate cylinder 9 is fixed on the inner circle of the buffer plate 36, and an outer guide cylinder 38 that is slidably connected to the inner circle of the rear side of the drill bit body 8 is fixed on the outer circle of the buffer plate 36. The front and rear ends of the buffer spring 35 are respectively pressed and engaged with the rear end face of the mounting base 20 and the front side face of the buffer plate 36.

[0029] The electromagnetic-driven, non-drilling-lift coal seam gas in-situ pressure-maintaining coring method, implemented using an electromagnetic-driven, non-drilling-lift coal seam gas in-situ pressure-maintaining coring device, includes the following steps: S1. The rear end of the intelligent drill bit 2 is threaded to the front end of the frontmost section of the double-barrel drill rod 39. Then, several drill rods are connected in series, and the electromagnetic drive coils 6 in the adjacent two sections of the double-barrel drill rod 39 are connected in series. The drilling machine is started to drive the double-barrel drill rod 39 and the intelligent drill bit 2 to drill to the predetermined core drilling depth of the coal seam. During the drilling process, the coal slag is discharged outward through multiple slag guide holes 10 on the drill bit body 8 and the spiral drill blades 11 on the outer cylinder 3. S2. A positive current is passed into the electromagnetic drive coil 6, and the electromagnetic drive coil 6 generates a magnetic field to drive the permanent magnet 7 in the core sac 1 to slide along the inner cylinder 4 toward the intelligent drill bit 2. S3. When the core scavenging bag 1 slides to the rear end of the guide gate cylinder 9, the guide gate cylinder 9 opens the mechanical double-locking door at the front end of the core scavenging bag 1. S4. The wireless signal receiver 23 inside the mounting base 20 receives the command and controls the iris opening and closing mechanism of the smart drill bit 2 to open through the remote control system. S5. The drilling rig is started briefly and slightly. The drilling rig drives the double-cylinder drill rod 39 and the intelligent drill bit 2 to rotate. The coal core drilled by the intelligent drill bit 2 enters the core sac 1 through the iris opening and closing mechanism, the material guide opening cylinder 9, and the core sac opening. S6. When the core sampling index reaches the preset value, the external control system remotely sends a closing command to control the iris opening and closing mechanism to close, and the six baffles 28 cut the coal core and close the core sampling channel 21. S7. A reverse current is passed into the electromagnetic drive coil 6. The electromagnetic drive coil 6 generates a reverse magnetic field to drive the permanent magnet 7 in the core scavenging bag 1 to slide along the inner cylinder 4 toward the drilling hole. The mechanical double-locking door at the front end of the core scavenging bag 1 disengages from the guide opening cylinder 9. The two doors 18 close under the action of their respective compression springs 19, keeping the core scavenging bag 1 under pressure and sealing. S8. When the core retrieval bag 1 moves close to the borehole opening, adjust the coil current to brake and decelerate the core retrieval bag 1. S9. After the core sampler 1 is moved to the end of the last section of the double-barrel drill rod 39, the core sampler 1 is taken out to complete the sampling.

[0030] The specific process of step S3 is as follows: The inclined surfaces of the two axial-radial drive protrusions 22 set on the outer circle of the rear end of the guide opening cylinder 9 press against the inclined surface structure 40 on the front side of the two sets of elastic telescopic door bodies 18 respectively. The axial movement of the core sac 1 is converted into radial thrust. The radial thrust drives the door body 18 to overcome the elastic force of the compression spring 19 and move outward along the guide groove 17 until the axial-radial drive protrusions 22 are located on the rear side of the door body 18. Then, the positive current is stopped from being supplied to the electromagnetic drive coil 6, and the two doors 18 are opened, that is, the core sac 1's core sac opening is opened.

[0031] The specific process of step S4 is as follows: Two explosion-proof motors 25 start and synchronously drive the active bevel gear 27 to rotate in the forward direction. The active bevel gear 27 drives the meshing bevel gear disk 26 to rotate. The regular hexagonal slide groove 29 behind the bevel gear disk 26 simultaneously drives the front slide column 30 on the front side of the six baffles 28 to move. The rear slide column 33 on the rear side of the six baffles 28 moves away from the core extraction channel 21 in the corresponding strip slide groove 32 until the rear slide column 33 moves to the end of the strip slide groove 32 that is far from the core extraction channel 21. At this time, the two explosion-proof motors 25 are turned off. At this time, the core extraction channel 21 is fully opened, and the front core extraction port of the core extraction bag 1, the guide gate 9, and the front and rear of the core extraction channel 21 are transparent.

[0032] Step S6 is as follows: Two explosion-proof motors 25 start and synchronously drive the active bevel gear 27 to rotate in the opposite direction. The active bevel gear 27 drives the meshing bevel disk 26 to rotate. The regular hexagonal slide groove 29 behind the bevel disk 26 simultaneously drives the front slide column 30 on the front side of the six baffles 28 to move. The rear slide column 33 on the rear side of the six baffles 28 moves towards the core extraction channel 21 in the corresponding strip slide groove 32. When the rear slide column 33 moves to the end of the strip slide groove 32 that is closer to the core extraction channel 21, the two explosion-proof motors 25 are turned off. At this time, the triangular sides of the six baffles 28 are connected in sequence to block and close the core extraction channel 21.

[0033] The above embodiments illustrate the basic principles and features of the present invention, but are merely preferred embodiments and are not limited to these embodiments. Those skilled in the art, inspired by this patent, can make many modifications and improvements without departing from the spirit and scope of the claims, all of which fall within the scope of protection of the present invention. Therefore, the scope of this patent and its protection should be determined by the appended claims.

Claims

1. An electromagnetically driven, non-drilling coal seam gas in-situ pressure-maintaining coring device, characterized in that: It includes a twin-barrel drill pipe, a core scavenging bag, an intelligent drill bit, and an external control system; The twin-cylinder drill rod consists of an outer cylinder and an inner cylinder coaxially mounted, forming an annular cavity between them. A spiral electromagnetic drive coil is installed within the annular cavity. The inner cylinder serves as the operating channel for the core sampling chamber. The core sampling chamber is slidably positioned within the inner cylinder, with a permanent magnet embedded in its outer wall. The front end of the core sampling chamber is open and equipped with a mechanically double-locking door. An intelligent drill bit is connected to the front end of the twin-cylinder drill rod. The intelligent drill bit includes a cylindrical drill bit body, within which is an iris opening and closing mechanism and a material guide opening cylinder located behind the iris opening and closing mechanism. The material guide opening cylinder is used to open the mechanically double-locking door to allow the coal sample to enter the core sampling chamber. The drill bit body has several circumferentially arrayed slag guide holes located in front of the iris opening and closing mechanism. An external control system is used to adjust the magnitude and direction of the current in the electromagnetic drive coil and to control the opening and closing of the iris opening and closing mechanism.

2. The electromagnetically driven, non-drilling coal seam gas in-situ pressure-maintaining coring device according to claim 1, characterized in that: The outer cylinder has a spiral drill blade on its outer circumference for discharging slag out of the borehole. The annular cavity between the outer and inner cylinders is filled with an insulating cooling medium for heat dissipation and insulation protection of the electromagnetic drive coil. The front and rear ends of the double-cylinder drill rod are respectively provided with coil connection holes that communicate with the front and rear ends of the annular cavity. The inner wall of the inner cylinder has an anti-rotation guide groove along its length, and the outer circumference of the core scavenging bag is provided with a guide strip that is slidably connected in the anti-rotation guide groove.

3. The electromagnetically driven, non-drilling coal seam gas in-situ pressure-maintaining coring device according to claim 1, characterized in that: The core extraction capsule includes a cylindrical shell with an open front end. A pressure-holding chamber is pre-installed inside the cylindrical shell, and the inner wall of the pressure-holding chamber is coated with an absorbent material layer. The mechanical double-locking doors include two sets of elastic telescopic doors symmetrically arranged about the center line of the core extraction capsule. The open end of the cylindrical shell has guide grooves with opposite openings inside. Each set of elastic telescopic doors includes a door body and a compression spring. The plane of the door body is perpendicular to the center line of the core extraction capsule. The door body slides in the guide groove. The two ends of the compression spring are respectively pressed and connected to the bottom of the guide groove and the inner end of the door body. The contact sides of the door bodies of the two sets of elastic telescopic doors are pressed and fitted together. The front side of the two door bodies outside the guide groove has a sloping structure.

4. The electromagnetically driven, non-drilling coal seam gas in-situ pressure-maintaining coring device according to claim 2, characterized in that: The iris opening and closing mechanism includes a mounting base coaxially fixed to the rear side of the inner circle of the drill bit body. The mounting base has a coaxial channel at its center that is open from front to back and corresponds to and communicates with the feed gate. The front end of the feed gate is fixedly connected to the rear end of the mounting base. The inner diameter of the coaxial channel is equal to the inner diameter of the feed gate. Two axial-to-radial drive protrusions are symmetrically arranged at the center of the outer circle of the rear end of the feed gate. The cross-sectional profile of the axial-to-radial drive protrusions is V-shaped. The mounting base contains a wireless signal receiver, two independent power supplies, and two explosion-proof motors. Each independent power supply powers one explosion-proof motor. A bevel gear disk with the same centerline as the drill bit body is rotatably mounted on the front side of the mounting base. The two explosion-proof motors are symmetrically arranged about the centerline of the drill bit body. Each explosion-proof motor's spindle is equipped with a driving bevel gear, and both driving bevel gears mesh with the bevel gear disk. Six baffles are arranged in a circumferential array around the centerline of the drill bit body on the rear side of the bevel gear disk. The baffles are all rectangular and triangular in shape. A regular hexagonal groove is provided on the rear side of the conical toothed disc. A front sliding post is fixed to the front rectangular surface of each baffle. Six front sliding posts slide within each side of the regular hexagonal groove. Six connecting rods are arranged in a circular array around the center line of the drill bit body on the front side of the six baffles on the mounting base. Each connecting rod is tangent to the inner circle of the core sampling channel. A strip-shaped groove is provided in the middle of each connecting rod, with the length of the groove along the length of the connecting rod. A rear sliding post is fixed to the rear rectangular surface of each baffle. Each rear sliding post extends into and slides within a strip-shaped groove. When each rear sliding post slides to the end of the corresponding strip-shaped groove closest to the core sampling channel, the triangular sides of the six baffles sequentially connect to block and close the core sampling channel. When each rear sliding post slides to the end of the corresponding strip-shaped groove furthest from the core sampling channel, the triangular sides of the six baffles separate, and the core sampling channel becomes open from front to back.

5. The electromagnetically driven, non-drilling coal seam gas in-situ pressure-maintaining coring device according to claim 4, characterized in that: A rear-end open mounting cavity is provided between the rear side of the drill bit body and the outer circle of the guide gate. A buffer spring and a buffer plate are fitted inside the mounting cavity and are sleeved on the outside of the guide gate. An inner guide cylinder that is slidably connected to the outer circle of the guide gate is fixed on the inner circle of the buffer plate, and an outer guide cylinder that is slidably connected to the inner circle of the rear side of the drill bit body is fixed on the outer circle of the buffer plate. The front and rear ends of the buffer spring are respectively pressed into the rear end face of the mounting seat and the front side face of the buffer plate.

6. An electromagnetically driven, non-drilling method for in-situ pressure-maintaining coring of coal seam gas, implemented using the electromagnetically driven, non-drilling method for in-situ pressure-maintaining coring of coal seam gas as described in claim 5, characterized in that: Includes the following steps: S1. The intelligent drill bit is threaded to the front end of the first section of the double-barrel drill rod. Then, several drill rods are connected in series, and the electromagnetic drive coils in the adjacent double-barrel drill rods are connected in series. The drilling machine is started to drive the double-barrel drill rods and the intelligent drill bit to drill to the predetermined core drilling depth of the coal seam. During the drilling process, the coal slag is discharged outward through multiple slag guide holes on the drill bit body and the spiral drill blades on the outer cylinder. S2. A positive current is passed into the electromagnetic drive coil, and the electromagnetic drive coil generates a magnetic field to drive the permanent magnet in the core sac to slide along the inner cylinder toward the intelligent drill bit. S3. When the core scavenging bag slides to the rear end of the guide gate, the guide gate will open the mechanical double-locking door at the front end of the core scavenging bag. S4. The system remotely sends commands through an external control system. The wireless signal receiver inside the mounting base receives the commands and controls the iris opening and closing mechanism of the smart drill bit to open. S5. The drilling rig is started briefly and slightly. The drilling rig drives the double-cylinder drill rod and the intelligent drill bit to rotate. The coal core drilled by the intelligent drill bit enters the core scavenging chamber through the iris opening and closing mechanism, the material guide opening cylinder, and the core scavenging port. S6. When the core sampling index reaches the preset value, the external control system remotely sends a closing command to control the iris opening and closing mechanism to close, and the six baffles cut the coal core and close the core sampling channel. S7. A reverse current is passed into the electromagnetic drive coil. The electromagnetic drive coil generates a reverse magnetic field to drive the permanent magnet in the core retrieval bag to slide along the inner cylinder toward the borehole opening. The mechanical double-locking door at the front end of the core retrieval bag disengages from the guide opening cylinder. The two doors close under the action of their respective compression springs, keeping the core retrieval bag pressure-sealed. S8. When the core retrieval bag moves close to the borehole opening, adjust the coil current to brake and decelerate the core retrieval bag. S9. After the core scavenger is moved to the end of the last section of the double-barrel drill pipe, the core scavenger is removed to complete the sampling.

7. The electromagnetically driven, non-drilling method for in-situ pressure-maintaining coring of coal seam gas according to claim 6, characterized in that: Step S3 is as follows: The inclined surfaces of the two axial-to-radial drive protrusions on the outer circle of the rear end of the guide opening cylinder press against the inclined surface structures on the front side of the two sets of elastic telescopic gate bodies respectively. The axial movement of the core-taking bladder is converted into radial thrust. The radial thrust drives the gate body to overcome the elastic force of the compression spring and move outward along the guide groove until the axial-to-radial drive protrusion is located on the rear side of the gate body. At this point, the positive current is stopped from being supplied to the electromagnetic drive coil, and the two gate bodies are opened, that is, the core-taking port of the core-taking bladder is opened.

8. The electromagnetically driven, non-drilling method for in-situ pressure-maintaining coring of coal seam gas according to claim 6, characterized in that: Step S4 is as follows: Two explosion-proof motors start and synchronously drive the active bevel gear to rotate in the forward direction. The active bevel gear drives the meshing bevel gear disk to rotate. The regular hexagonal groove behind the bevel gear disk simultaneously drives the front sliding column on the front side of the six baffles to move. The rear sliding column on the rear side of the six baffles moves away from the core extraction channel in the corresponding strip groove until the rear sliding column moves to the end of the strip groove that is far from the core extraction channel. At this time, the two explosion-proof motors are turned off. At this time, the core extraction channel is fully opened, and the core extraction port at the front of the core extraction bag, the guide gate, and the front and rear of the core extraction channel are transparent.

9. The electromagnetically driven, non-drilling method for in-situ pressure-maintaining coring of coal seam gas according to claim 6, characterized in that: Step S6 is as follows: Two explosion-proof motors start and synchronously drive the active bevel gear to rotate in the opposite direction. The active bevel gear drives the meshing bevel gear disk to rotate. The regular hexagonal groove behind the bevel gear disk simultaneously drives the front sliding column on the front side of the six baffles to move. The rear sliding column on the rear side of the six baffles moves towards the core extraction channel in the corresponding strip groove. When the rear sliding column moves to the end of the strip groove that is closer to the core extraction channel, the two explosion-proof motors are turned off. At this time, the triangular sides of the six baffles connect in sequence to block and close the core extraction channel.

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