A kind of drill tool for continuous medium-free pressure-maintaining while-drilling core sampling in soft coal seam

Abstract

This invention provides a drilling tool for continuous, pressure-maintaining, closed-loop coring of soft, fractured coal seams without media. From front to back along the axial direction, it comprises a coaxially arranged electrically driven, closable drill bit, a core barrel outer tube assembly, and a signal transmission drill rod. A hollow core barrel inner tube assembly is coaxially mounted inside the core barrel outer tube assembly. The electrically driven, closable drill bit is connected to the signal transmission drill rod, allowing the drill bit to be opened or closed. The core barrel outer tube assembly is connected to the signal transmission drill rod, providing axial restraint for the core barrel inner tube assembly. The core barrel inner tube assembly is connected to the signal transmission drill rod, allowing the axial opening or closing of both ends of the internal cavity of the core barrel inner tube assembly. The outer wall of the signal transmission drill rod is integrally provided with spirally wound drill rod blades. The drilling tool of this invention is a dry drilling tool, ensuring that the obtained coal core sample is uncontaminated. The drilling tool of this invention does not require the introduction of water or air during the drilling and sampling processes, ensuring that the properties of the extracted coal core sample are consistent with the coal body within the borehole.

Description

Technical Field

[0001] This invention belongs to the field of coal body sampling technology in underground coal mines, and relates to drilling tools, specifically a drilling tool for continuous pressure-maintaining closed coring without media in fractured and soft coal seams. Background Technology

[0002] Coal core drilling under pressure maintenance refers to maintaining the in-situ pressure (such as gas pressure or groundwater pressure) of the coal core during drilling in underground or surface coal mines using special techniques, ensuring that the coal core does not exchange gases or liquids with the external environment during extraction. This technology is of great significance for coal mine gas extraction, coalbed methane resource assessment, water inrush mechanism research, and disaster prevention.

[0003] Traditional coring techniques struggle to maintain the in-situ pressure and environment of coal cores, leading to gas escape, moisture loss, or structural damage, thus affecting data accuracy. Therefore, pressure-controlled closed-loop coring technology has become a key research direction for safe coal mining and efficient resource utilization.

[0004] Current closed-pressure coring drilling tools and methods have the following shortcomings in actual construction:

[0005] First, cored samples are easily contaminated. Current coring tools, especially during the opening and closing of the coring cylinder, require dropping a ball from the borehole and introducing water or air to create a pressure difference that drives the actuator. This causes gas or liquid exchange between the coal core and the external environment during extraction, making the obtained sample easily contaminated and compromising its purity.

[0006] Second, it cannot perform coring while drilling. Current coring processes involve drilling to a predetermined layer, then pulling the drill string back up, and then lowering the coring tool to perform coring operations. This requires two drilling runs, which is time-consuming and labor-intensive, and cannot achieve coring while drilling.

[0007] Third, coring tools have complex structures and high failure rates. Current coring tools are mostly designed with two or three layers of tubing. They use a ball dropped into the borehole and water or air to create a pressure difference that drives the actuator. This makes them complex, troublesome to maintain, and prone to failure during use. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a drilling tool for continuous, pressure-maintaining, closed-loop coring without media in soft, fractured coal seams, thereby solving the technical problem in existing drilling tools where it is difficult to simultaneously improve sample quality and reduce device complexity during coring.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A drilling tool for continuous, pressure-maintaining, closed-loop coring without media in soft coal seams comprises, from front to back along the axial direction, a coaxially arranged and hollow electrically driven openable and closable drill bit, a core barrel outer tube assembly, and a signal transmission drill rod. The core barrel outer tube assembly has a hollow core barrel inner tube assembly coaxially installed inside.

[0011] The electrically driven openable drill bit is connected to the signal transmission drill rod via an insulated wire or conductive block, thereby enabling the opening or closing of the electrically driven openable drill bit.

[0012] The outer tube assembly of the core barrel is connected to the signal transmission drill rod via an insulated wire or conductive block, thereby enabling axial positioning of the inner tube assembly of the core barrel.

[0013] The core barrel inner tube assembly is connected to the signal transmission drill rod via an insulated wire or conductive block, thereby enabling the opening or closing of the axial ends of the internal cavity of the core barrel inner tube assembly.

[0014] The outer wall of the signal transmission drill pipe is also integrally and coaxially provided with a spirally wound drill pipe blade.

[0015] The present invention also has the following technical features:

[0016] Preferably, the electrically driven openable drill bit includes a drill bit body, and a central through hole is coaxially formed in the drill bit body, which passes through both ends of the axial direction. The diameter of the front section of the central through hole is smaller than the diameter of the rear section of the central through hole. The stepped surface at the connection between the front section and the rear section of the central through hole is the first limiting surface of the front end of the outer tube.

[0017] The drill bit body is also integrally provided with multiple fixed blades at its axial front end, and the multiple fixed blades are evenly distributed circumferentially on the outer edge of the axial front end of the drill bit body.

[0018] The drill bit body is further embedded with a rear conductive block and a rear insulating wrapping layer on its axial rear end face. The rear insulating wrapping layer isolates the rear conductive block from the drill bit body. The rear conductive block is connected to the drive motor of the electrically driven openable drill bit through an insulated wire.

[0019] Specifically, the drill bit body has two rotatable blades arranged symmetrically at the center of its axial front end. When closed, the two rotatable blades seal the axial front end of the central through hole. The drill bit body also has blade rotation shafts installed at its axial front end. Each blade rotation shaft corresponds to one of the rotatable blades. The two rotatable blades are mounted on the drill bit body via their corresponding blade rotation shafts. The two rotatable blades can also rotate 90° around their corresponding blade rotation shafts under the drive of the electric drive motor of the electrically driven openable and closable drill bit.

[0020] Specifically, the core sampling tube outer tube assembly includes, from front to back, an integrated coaxially arranged male connector at the front end of the outer tube, the core sampling tube body, and a female connector at the rear end of the outer tube.

[0021] The aforementioned external tube front end male connector includes a cylindrical external tube front end male connector body. The axial front end of the external tube front end male connector body is axially limited by the first limiting surface of the external tube front end. The external tube front end male connector body is connected to the drill bit body body by external thread. The external tube front end male connector body also has a first external tube channel coaxially opened in the body. The axial front end of the first external tube channel is connected to the axial rear end of the central through hole.

[0022] The core-taking cylinder outer tube body includes a cylindrical outer tube body. The axial front end of the outer tube body is limited by the axial rear end face of the drill bit body. Multiple outer tube front conductive units are also embedded and evenly distributed along the circumferential direction on the axial front end face of the outer tube body. The outer tube front conductive units can contact the rear conductive block to achieve mutual communication.

[0023] The outer tube body is also coaxially provided with a second outer tube channel that extends through the axis. The axial front end of the second outer tube channel is connected to the axial rear end of the first outer tube channel. The stepped surface of the second outer tube channel near the axial front end is the inner tube front end limiting surface. The core tube inner tube assembly is also installed in the second outer tube channel. The maximum inner diameter of the second outer tube channel is equal to the maximum outer diameter of the core tube inner tube assembly.

[0024] Specifically, multiple conductive units are embedded in the inner wall of the outer tube body, and a solenoid valve assembly and a locking tongue at the rear end of the inner tube body are embedded in the inner wall near the axial rear end. The solenoid valve assembly can drive the locking tongue at the rear end of the inner tube to extend and retract radially along the second outer tube channel, thereby limiting the axial rear end of the core-taking cylinder inner tube assembly.

[0025] The aforementioned outer tube rear end female connector includes an outer tube rear end female connector body. A third outer tube channel is coaxially provided within the outer tube rear end female connector body. The axial front end of the third outer tube channel is connected to the axial rear end of the second outer tube channel. A stepped surface-shaped transmission rod front end limiting surface is also provided within the third outer tube channel.

[0026] Specifically, the outer tube rear end female connector body is also embedded and uniformly distributed with an outer tube rear end conductive unit along the circumferential direction on the axial rear end surface. The outer tube rear end conductive unit includes an outer tube rear end conductive block. The outer tube rear end conductive block is isolated from the outer tube rear end female connector body through the outer tube rear end insulating wrapping layer. The outer tube rear end conductive block can contact the signal transmission drill rod to achieve mutual communication.

[0027] The structure of the conductive unit at the front end of the outer tube is the same as that of the conductive unit at the rear end of the outer tube.

[0028] The aforementioned conductive unit on the inner wall of the outer tube includes a conductive block on the inner wall of the outer tube, which is isolated from the outer tube body by an insulating wrapping layer on the inner wall of the outer tube.

[0029] The conductive block of the outer tube front end conductive unit, the conductive block of the outer tube inner wall, the solenoid valve assembly, and the conductive block of the outer tube rear end are interconnected by insulated wires and are insulated from the outer tube front end male connector body, the outer tube body body, and the outer tube rear end female connector body.

[0030] Specifically, the core retrieval tube assembly includes, from front to back, a front-end electrically controlled valve, a core retrieval tube body, a rear-end electrically controlled valve, and a retrieval mechanism, which are coaxially arranged and threadedly connected. The structure of the front-end electrically controlled valve is the same as that of the rear-end electrically controlled valve, and the two are arranged symmetrically at both ends of the axial direction of the core retrieval tube body.

[0031] The aforementioned electrically controlled valve at the front end of the inner tube includes a front valve body shell, which comprises, from front to back, an integrated coaxially arranged front valve body seat and a front valve body. The axial front end of the front valve body seat is axially limited by the front end limiting surface of the inner tube. The outer diameter of the front valve body seat is equal to the maximum inner diameter of the second outer tube channel. Multiple inner tube front conductive units are also embedded on the outer side wall of the front valve body seat. The multiple inner tube front conductive units are evenly distributed circumferentially. Each inner tube front conductive unit includes an inner tube front conductive block, which is isolated from the front valve body seat by an inner tube front insulating wrapping layer. The inner tube front conductive block also corresponds one-to-one with the conductive block on the inner wall of the outer tube near the axial front end of the outer tube body and is interconnected.

[0032] The front valve body is also coaxially provided with an axially penetrating front valve body channel. The front valve body channel extends forward along the axial direction, penetrates the interior of the front valve body seat, and is connected to the axial rear end of the third outer tube channel. The cavity in the middle section of the front valve body channel is a spherical cavity. A front ball valve core is also installed in the spherical cavity. A front valve core drive motor is also installed on the front valve body. The front valve core drive motor can drive the front ball valve core to open or close the front valve body channel.

[0033] Specifically, the core sampling tube inner tube body includes an inner tube body body, and an inner tube body channel is coaxially opened in the inner tube body body body. The diameter of the inner tube body channel is equal to the diameter of the front valve body channel, and the axial front end of the inner tube body channel is connected to the axial rear end of the front valve body channel.

[0034] The aforementioned internal tube rear-end electrically controlled valve includes a rear-end valve body channel, the axial front end of which is connected to the axial rear end of the internal tube channel; the axial rear end of the rear-end valve body seat of the internal tube rear-end electrically controlled valve can be axially limited by the internal tube rear-end locking tongue, and the rear-end valve body seat of the internal tube rear-end electrically controlled valve is also connected to the axial front end of the coaxially arranged salvage mechanism through internal threads; the rear-end valve body seat of the internal tube rear-end electrically controlled valve is also provided with an internal tube rear-end conductive block, and the internal tube rear-end conductive block is also corresponding one-to-one with the conductive block on the inner wall of the outer tube near the axial rear end of the outer tube body and is interconnected with each other.

[0035] The inner tube front conductive block, the front valve core drive motor, the inner tube rear conductive block of the inner tube rear electrically controlled valve, and the inner tube rear electrically controlled valve rear valve are connected by insulated wires and are all isolated from the front valve body shell, the inner tube body, and the inner tube rear electrically controlled valve rear valve shell.

[0036] Specifically, the signal transmission drill rod includes, from front to back, a transmission rod male connector, a transmission rod tube body, and a transmission rod female connector, which are coaxially arranged and connected in sequence.

[0037] The male connector of the transmission rod includes a male connector body, which is connected to the female connector body at the rear end of the outer tube via an external thread; the male connector body of the transmission rod also has an axially penetrating transmission rod channel coaxially opened inside, and the axial front end of the transmission rod channel is connected to the third outer tube channel.

[0038] An embedded conductive block for the front end of the transmission rod is installed on the end face of the male connector near the inner end of the male connector body. The conductive block for the front end of the transmission rod is insulated and protected by the insulating wrapping layer at the front end of the transmission rod. The conductive block for the front end of the transmission rod can contact and connect with the conductive block at the rear end of the outer tube.

[0039] The transmission rod tube body includes a transmission rod tube body body, and the transmission rod tube body body body also has an axially through-passing transmission rod tube body body channel coaxially opened inside.

[0040] The female connector of the transmission rod includes a female connector body. The female connector body is also coaxially provided with an axially penetrating rear end channel of the transmission rod. The axial front end of the rear end channel of the transmission rod is connected to the axial rear end of the male connector channel of the transmission rod through the transmission rod tube body channel. The inner diameter of the rear end channel of the transmission rod, the inner diameter of the transmission rod tube body channel, and the inner diameter of the male connector channel of the transmission rod are all greater than the maximum outer diameter of the core tube inner tube assembly.

[0041] The axial rear end face of the female connector body of the transmission rod is also embedded with a transmission rod rear end conductive block, which is insulated and protected by the transmission rod rear end insulating wrapping layer; the transmission rod rear end conductive block is also connected to the transmission rod front end conductive block through an insulated wire.

[0042] Compared with the prior art, the present invention has the following technical effects:

[0043] (I) The drilling tool in this invention is a dry drilling tool, which ensures that the obtained coal core sample is uncontaminated; the drilling tool of this invention does not require water or air to be introduced during the drilling and sampling process, ensuring that the coal core sample does not exchange gas or liquid with the external environment during the extraction process. After entering the inner tube of the core tube assembly, both ends are sealed to ensure that the extracted coal core sample has the same properties as the coal in the borehole to the greatest extent.

[0044] (II) The drilling tool in this invention can achieve continuous sampling while drilling; the drilling and sampling can be combined into one, eliminating the need for one drilling trip; when a core tube assembly is filled and removed, another core tube assembly can be lowered to achieve continuous pressure-maintaining and sealed core sampling while drilling.

[0045] (III) The drilling tool in this invention has developed intelligently; it transforms the traditional pure mechanical structure into an electromechanical integrated structure, and uses a multi-channel signal transmission drill rod to send commands to the bottom hole drilling tool to execute various actions. The action response is rapid, accurate, stable and reliable.

[0046] (IV) The drilling tool in this invention can be used for both ordinary gas extraction hole construction and continuous closed-pressure coring operations while drilling. This improves the adaptability of the drilling tool to different strata, reduces labor intensity, and improves construction efficiency. It provides technical equipment support for coal body sampling and coal and gas control projects in coal mines, and solves the technical problems existing in the construction of underground gas extraction holes in coal mines, such as poor adaptability of drilling tools, easy hole collapse after hydraulic permeation and drilling, difficulty in setting screen pipes in open holes, and the need for hydraulic permeation and screen pipe setting to be done in two separate operations. Attached Figure Description

[0047] Figure 1 This is a schematic cross-sectional view of the device of the present invention.

[0048] Figure 2 This is a cross-sectional structural diagram of an electrically driven, closable drill bit.

[0049] Figure 3 This is a rear view schematic diagram of an electrically driven, closable drill bit.

[0050] Figure 4 This is a cross-sectional structural diagram of the outer tube assembly of the core sampler.

[0051] Figure 5 This is a rear view structural diagram of the core barrel outer tube assembly.

[0052] Figure 6 This is a cross-sectional structural diagram of the inner tube assembly of the core sampler.

[0053] Figure 7 This is a schematic diagram of the structure of the electrically controlled valve at the front end of the inner pipe.

[0054] Figure 8 This is a cross-sectional view of the electrically controlled valve at the front end of the inner pipe.

[0055] Figure 9 This is a schematic diagram of the structure of the signal transmission drill rod.

[0056] Figure 10 This is a cross-sectional structural diagram of the signal transmission drill pipe.

[0057] Figure 11 This is a rear view schematic diagram of the signal transmission drill pipe.

[0058] The meanings of the labels in the diagram are as follows: 1-Electrically driven openable drill bit, 2-Outer core tube assembly, 3-Inner core tube assembly, 4-Signal transmission drill rod.

[0059] 101-Drill bit body, 102-Central through hole, 103-First limiting surface at the front end of the outer tube, 104-Fixed cutter wing, 105-Rotable cutter wing, 106-Cutter wing rotation shaft, 107-Rear handle conductive block, 108-Rear handle insulating wrapping layer.

[0060] 201-Outer tube front end male connector, 202-Core sampler outer tube body, 203-Outer tube rear end female connector.

[0061] 301 - Electrically controlled valve at the front end of the inner tube; 302 - Inner tube body of the core scavenging cylinder; 303 - Electrically controlled valve at the rear end of the inner tube; 304 - Salvage mechanism.

[0062] 401-Transmission rod male connector, 402-Transmission rod tube body, 403-Transmission rod female connector, 404-Drill rod blade.

[0063] 20101 - Male connector body at the front end of the outer tube; 20102 - First outer tube channel.

[0064] 20201-Outer tube body, 20202-Outer tube front end conductive unit, 20203-Second outer tube channel, 20204-Inner tube front end limiting surface, 20205-Outer tube inner wall conductive unit, 20206-Solenoid valve assembly, 20207-Inner tube rear end locking tongue.

[0065] 20301 - Female connector body at the rear end of the outer tube; 20302 - Third outer tube channel; 20303 - Conductive unit at the rear end of the outer tube; 20304 - Limiting surface at the front end of the transmission rod.

[0066] 30101 - Front valve body housing, 30102 - Inner tube front conductive unit, 30103 - Front valve body channel, 30104 - Front ball valve core, 30105 - Front valve core drive motor.

[0067] 30201 - Inner tube body, 30202 - Inner tube channel.

[0068] 40101 - Transmission rod male connector body, 40102 - Transmission rod male connector channel, 40103 - Transmission rod front conductive block, 40104 - Transmission rod front insulating wrapping layer.

[0069] 40201 - Transmission rod tube body, 40202 - Transmission rod tube body channel.

[0070] 40301 - Transmission rod female connector body, 40302 - Transmission rod rear end channel, 40303 - Transmission rod rear end conductive block, 40304 - Transmission rod rear end insulating wrapping layer.

[0071] 2020501 - Conductive block on the inner wall of the outer tube; 2020502 - Insulating wrapping layer on the inner wall of the outer tube.

[0072] 2030301 - Conductive block at the rear end of the outer tube; 2030302 - Insulating wrapping layer at the rear end of the outer tube.

[0073] 3010101-Front-end valve body seat, 3010102-Front-end valve body.

[0074] 3010201 - Conductive block at the front end of the inner tube; 3010202 - Insulating wrapping layer at the front end of the inner tube.

[0075] The specific content of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0076] It should be noted that, unless otherwise specified, all mechanisms, components, parts and materials in this invention are commonly used in the art in the prior art. For example, the salvage mechanism is a known salvage mechanism, the solenoid valve assembly is a known solenoid valve assembly, the rear handle conductive block is a known rear handle conductive block, the inner tube rear end locking tongue is a known inner tube rear end locking tongue, the special salvage spearhead is a known special salvage spearhead, the front valve core drive motor is a known front valve core drive motor, the front ball valve core is a known front ball valve core, the drill rod blade is a known drill rod blade, the rear handle insulation wrapping layer is a known rear handle insulation wrapping layer, and the insulation material is a known insulation material.

[0077] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0078] Example:

[0079] This embodiment provides a drilling tool for continuous, pressure-maintaining, closed-loop coring without media in fractured and soft coal seams, such as... Figure 1 As shown, the structure includes, from front to back along the axial direction, a coaxially arranged and hollow electric drive openable drill bit 1, a core barrel outer tube assembly 2, and a signal transmission drill rod 4. The core barrel outer tube assembly 2 has a hollow core barrel inner tube assembly 3 coaxially installed inside.

[0080] The electrically driven openable drill bit 1 is connected to the signal transmission drill rod 4 via an insulated wire or conductive block, thereby enabling the opening or closing of the electrically driven openable drill bit 1.

[0081] The outer tube assembly 2 of the core barrel is connected to the signal transmission drill rod 4 via an insulated wire or conductive block, thereby enabling axial positioning of the inner tube assembly 3 of the core barrel.

[0082] The inner tube assembly 3 of the core barrel is connected to the signal transmission drill rod 4 through an insulated wire or a conductive block, thereby enabling the opening or closing of the axial ends of the internal cavity of the inner tube assembly 3.

[0083] The outer wall of the signal transmission drill pipe 4 is also integrally and coaxially provided with a spirally wound drill pipe blade 404.

[0084] As a preferred embodiment of this invention, such as Figure 2As shown, the electrically driven openable drill bit 1 includes a drill bit body 101. A central through hole 102 is coaxially formed in the drill bit body 101, passing through both ends of the axial direction. The diameter of the front section of the central through hole 102 is smaller than the diameter of the rear section of the central through hole 102. The stepped surface at the connection between the front section and the rear section of the central through hole 102 is the first limiting surface 103 at the front end of the outer tube.

[0085] The drill bit body 101 also has multiple fixed blades 104 integrated at its axial front end, which are evenly distributed circumferentially on the outer edge of the axial front end of the drill bit body 101.

[0086] like Figure 3 As shown, a rear handle conductive block 107 and a rear handle insulating wrapping layer 108 are also embedded on the axial rear end face of the drill bit body 101. The rear handle insulating wrapping layer 108 isolates the rear handle conductive block 107 from the drill bit body 101. The rear handle conductive block 107 is connected to the drive motor of the electrically driven openable drill bit 1 through an insulated wire.

[0087] In this embodiment, the number of fixed blades 104 is 4.

[0088] As a preferred embodiment, two rotatable blades 105 are symmetrically arranged at the center of the axial front end of the drill bit body 101. When closed, the two rotatable blades 105 seal the axial front end of the central through hole 102. A blade rotation shaft 106 is also installed at the axial front end of the drill bit body 101. The blade rotation shaft 106 corresponds one-to-one with the rotatable blades 105. The two rotatable blades 105 are mounted on the drill bit body 101 through the corresponding blade rotation shaft 106. The two rotatable blades 105 can also rotate 90° around the corresponding blade rotation shaft 106 under the drive of the drive motor of the electrically driven openable and closable drill bit 1.

[0089] In this embodiment, the rotatable blade 105 adopts a commonly known rotatable blade in the art. The two rotatable blades perform drilling when closed.

[0090] As a preferred embodiment of this invention, such as Figure 4 As shown, the core tube outer tube assembly 2 includes, from front to back, an integrated coaxially arranged male connector 201 at the front end of the outer tube, a core tube body 202, and a female connector 203 at the rear end of the outer tube.

[0091] The outer tube front end male connector 201 includes a cylindrical outer tube front end male connector body 20101. The axial front end of the outer tube front end male connector body 20101 is axially limited by the outer tube front end first limiting surface 103. The outer tube front end male connector body 20101 is connected to the drill bit body body 101 by external thread. The outer tube front end male connector body 20101 is also coaxially provided with an axially penetrating first outer tube channel 20102. The axial front end of the first outer tube channel 20102 is connected to the axial rear end of the central through hole 102.

[0092] The outer tube body 202 of the core tube includes a cylindrical outer tube body 20201. The axial front end of the outer tube body 20201 is limited by the axial rear end face of the drill bit body 101. Multiple outer tube front conductive units 20202 are also embedded and uniformly arranged along the circumferential direction on the axial front end face of the outer tube body 20201. The outer tube front conductive units 20202 can contact the rear conductive block 107 to achieve mutual communication.

[0093] The outer tube body 20201 is also coaxially provided with a second outer tube channel 20203 that is axially connected. The axial front end of the second outer tube channel 20203 is connected to the axial rear end of the first outer tube channel 20102. The stepped surface of the second outer tube channel 20203 near the axial front end is the inner tube front end limiting surface 20204. The core tube inner tube assembly 3 is also installed in the second outer tube channel 20203. The maximum inner diameter of the second outer tube channel 20203 is equal to the maximum outer diameter of the core tube inner tube assembly 3.

[0094] As a preferred embodiment, a plurality of outer tube inner wall conductive units 20205 are also embedded in the inner wall of the outer tube body 20201. A solenoid valve assembly 20206 and an inner tube rear end locking tongue 20207 are also embedded in the inner wall of the outer tube body 20201 near the axial rear end. The solenoid valve assembly 20206 can drive the inner tube rear end locking tongue 20207 to extend and retract along the radial direction of the second outer tube channel 20203, thereby limiting the axial rear end of the core-taking cylinder inner tube assembly 3.

[0095] The outer tube rear end female connector 203 includes an outer tube rear end female connector body 20301. A third outer tube channel 20302 is coaxially provided inside the outer tube rear end female connector body 20301. The axial front end of the third outer tube channel 20302 is connected to the axial rear end of the second outer tube channel 20203. A stepped transmission rod front end limiting surface 20304 is also provided inside the third outer tube channel 20302.

[0096] As a preferred embodiment of this invention, such as Figure 5As shown, the outer tube rear end female connector body 20301 is also uniformly embedded in the circumferential direction on the axial rear end surface of the outer tube rear end female connector body 20301. The outer tube rear end conductive unit 20303 includes an outer tube rear end conductive block 2030301. The outer tube rear end conductive block 2030301 is isolated from the outer tube rear end female connector body 20301 through the outer tube rear end insulating wrapping layer 2030302. The outer tube rear end conductive block 2030301 can contact the signal transmission drill rod 4 to achieve mutual communication.

[0097] The structure of the conductive unit 20202 at the front end of the outer tube is the same as that of the conductive unit 20303 at the rear end of the outer tube.

[0098] The conductive unit 20205 on the inner wall of the outer tube includes a conductive block 2020501 on the inner wall of the outer tube. The conductive block 2020501 on the inner wall of the outer tube is isolated from the body 20201 of the outer tube through an insulating wrapping layer 2020502 on the inner wall of the outer tube.

[0099] The conductive block of the outer tube front conductive unit 20202, the conductive block 2020501 of the outer tube inner wall, the solenoid valve assembly 20206, and the conductive block 2030301 of the outer tube rear end are interconnected by insulated wires and are insulated from the outer tube front male connector body 20101, the outer tube body 20201, and the outer tube rear female connector body 20301.

[0100] As a preferred embodiment of this invention, such as Figure 6 As shown, the core retrieval tube assembly 3 includes, from front to back, a coaxially arranged and threadedly connected front-end electrically controlled valve 301, a core retrieval tube body 302, a rear-end electrically controlled valve 303, and a retrieval mechanism 304. The structure of the front-end electrically controlled valve 301 is the same as that of the rear-end electrically controlled valve 303, and the two are arranged axially symmetrically at both ends of the core retrieval tube body 302.

[0101] like Figure 7 and Figure 8As shown, the inner tube front-end electrically controlled valve 301 includes a front-end valve body housing 30101. The front-end valve body housing 30101, arranged axially from front to back, includes an integrated coaxially mounted front-end valve body seat 3010101 and a front-end valve body 3010102. The axial front end of the front-end valve body seat 3010101 is axially limited by the inner tube front-end limiting surface 20204. The outer diameter of the front-end valve body seat 3010101 is equal to the maximum inner diameter of the second outer tube channel 20203. An embedded device is also installed on the outer side wall of the front-end valve body seat 3010101. Multiple inner tube front-end conductive units 30102 are evenly arranged circumferentially. Each inner tube front-end conductive unit 30102 includes an inner tube front-end conductive block 3010201. The inner tube front-end conductive block 3010201 is isolated from the front valve seat 3010101 by the inner tube front-end insulating wrapping layer 3010202. The inner tube front-end conductive block 3010201 also corresponds one-to-one with the outer tube inner wall conductive block 2020501 at the axial front end near the outer tube body 20201 and is interconnected with each other.

[0102] The front valve body 3010102 is also coaxially provided with an axially penetrating front valve body channel 30103. The front valve body channel 30103 extends forward along the axial direction, penetrates the interior of the front valve body seat 3010101, and is connected to the axial rear end of the third outer pipe channel 20302. The cavity of the front valve body channel 30103 in the middle section of the front valve body 3010102 is a spherical cavity. The front ball valve core 30104 is also installed in the spherical cavity. The front valve core drive motor 30105 is also installed on the front valve body 3010102. The front valve core drive motor 30105 can drive the front ball valve core 30104 to open or close the front valve body channel 30103.

[0103] As a preferred embodiment, the core tube inner tube 302 includes an inner tube body 30201, and an inner tube channel 30202 is coaxially opened inside the inner tube body 30201. The diameter of the inner tube channel 30202 is equal to the diameter of the front valve body channel 30103, and the axial front end of the inner tube channel 30202 is connected to the axial rear end of the front valve body channel 30103.

[0104] The inner tube rear end electrically controlled valve 303 includes a rear end valve body channel, the axial front end of which is connected to the axial rear end of the inner tube body channel 30202; the axial rear end of the rear end valve body seat of the inner tube rear end electrically controlled valve 303 can be axially limited by the inner tube rear end locking tongue 20207; the rear end valve body seat of the inner tube rear end electrically controlled valve 303 is also connected to the axial front end of the coaxially arranged retrieval mechanism 304 through internal threads; the rear end valve body seat of the inner tube rear end electrically controlled valve 303 is also provided with an inner tube rear end conductive block, and the inner tube rear end conductive block is also corresponding one-to-one with the outer tube inner wall conductive block 2020501 near the axial rear end of the outer tube body 20201 and is interconnected with each other.

[0105] The conductive block 3010201 at the front end of the inner tube, the front valve core drive motor 30105, the conductive block at the rear end of the inner tube of the electrically controlled valve 303 at the rear end of the inner tube, and the valve core drive motor at the rear end of the electrically controlled valve 303 at the rear end of the inner tube are connected by insulated wires and are all isolated from the front valve body shell 30101, the inner tube body 30201, and the rear valve body shell of the electrically controlled valve 303 at the rear end of the inner tube.

[0106] In this embodiment, the diameters of the internal channels of the front ball valve core 30104, the front valve body channel 30103, and the inner tube channel 30202 are all equal when the front ball valve core 30104 is open.

[0107] As a preferred embodiment of this invention, such as Figures 9 to 11 As shown, the signal transmission drill rod 4 includes, from front to back, a transmission rod male connector 401, a transmission rod tube body 402, and a transmission rod female connector 403, which are coaxially arranged and connected in sequence.

[0108] The male connector 401 of the transmission rod includes a male connector body 40101, which is connected to the female connector body 20301 at the rear end of the outer tube by an external thread; the male connector body 40101 of the transmission rod also has a male connector channel 40102 that is axially through it, and the front end of the male connector channel 40102 of the transmission rod is connected to the third outer tube channel 20302.

[0109] An embedded conductive block 40103 for the front end of the transmission rod is installed on the end face of the male connector 401 near the inner end of the male connector body 40101. The conductive block 40103 for the front end of the transmission rod is insulated and protected by the insulating wrapping layer 40104 for the front end of the transmission rod. The conductive block 40103 for the front end of the transmission rod can contact and connect with the conductive block 2030301 for the rear end of the outer tube.

[0110] The transmission rod tube body 402 includes a transmission rod tube body 40201, and the transmission rod tube body body 40201 is also coaxially provided with an axially penetrating transmission rod tube body channel 40202 inside the transmission rod tube body body 40201.

[0111] The female connector of the transmission rod 403 includes a female connector body 40301. The female connector body 40301 is also coaxially provided with an axially penetrating rear end channel 40302 of the transmission rod. The axial front end of the rear end channel 40302 of the transmission rod is connected to the axial rear end of the male connector channel 40102 of the transmission rod through the male connector channel 40202 of the transmission rod tube body. The inner diameter of the rear end channel 40302 of the transmission rod, the inner diameter of the male connector channel 40202 of the transmission rod tube body, and the inner diameter of the male connector channel 40102 of the transmission rod are all greater than the maximum outer diameter of the core tube assembly 3.

[0112] The axial rear end face of the female connector body 40301 of the transmission rod is also embedded with a transmission rod rear end conductive block 40303. The transmission rod rear end conductive block 40303 is insulated and protected by the transmission rod rear end insulating wrapping layer 40304. The transmission rod rear end conductive block 40303 is also connected to the transmission rod front end conductive block 40103 through an insulated wire.

[0113] In this embodiment, the insulated wires in the signal transmission drill rod 4 are all wrapped with a wear-resistant protective layer; the insulated wires in the signal transmission drill rod 4 are arranged in a spiral winding manner on the signal transmission drill rod 4, and the insulated wires arranged on the signal transmission drill rod 4 are in contact with the outer wall surface of the signal transmission drill rod 4.

[0114] In this embodiment, the insulating wrapping layer 108, the front insulating wrapping layer 40104 of the transmission rod, the rear insulating wrapping layer 40304 of the transmission rod, the inner wall insulating wrapping layer 2020502 of the outer tube, the rear insulating wrapping layer 2030302 of the outer tube, and the front insulating wrapping layer 3010202 of the inner tube are all made of insulating materials.

[0115] In this embodiment, the connection between the electrically driven openable drill bit 1 and the core barrel outer tube assembly 2 is sealed, the connection between the core barrel outer tube assembly 2 and the signal transmission drill rod 4 is sealed, and the contact point between the core barrel outer tube assembly 2 and the electrically controlled valve 301 at the front end of the inner tube is also sealed.

[0116] In this embodiment, the drive motor of the electric openable drill bit 1, the solenoid valve assembly 20206, the front valve core drive motor 30105, and the rear valve core drive motor of the rear electrically controlled valve 303 of the inner tube are all explosion-proof electronic products that meet the requirements for use in coal mines with methane conditions. The drive motor of the electric openable drill bit 1, the solenoid valve assembly 20206, the front valve core drive motor 30105, and the rear valve core drive motor of the rear electrically controlled valve 303 of the inner tube are commonly used in the art for electric openable drill bits, solenoid valve assemblies, front valve core drive motors, and rear valve core drive motors of the rear electrically controlled valves of the inner tube.

[0117] In this embodiment, after the electrically driven openable drill bit 1, the core barrel outer tube assembly 2, and the signal transmission drill rod 4 are connected in sequence, the core barrel inner tube assembly 3 is installed inside the core barrel outer tube assembly 2. Then, the rear conductive block 107 is brought into contact with the conductive block of the outer tube front conductive unit 20202, the outer tube inner wall conductive block 2020501 is brought into contact with the inner tube front conductive block 3010201 and the inner tube rear conductive block of the inner tube rear electrically controlled valve 303, and the outer tube rear conductive block 2030301 is brought into contact with the transmission rod front conductive block 40103, thus realizing the circuit conduction.

[0118] The method of using the device in this embodiment specifically includes the following steps:

[0119] Step 1, Drill string connection:

[0120] Connect the electrically driven openable drill bit 1, the core barrel outer tube assembly 2, and the signal transmission drill rod 4 in sequence, and install the core barrel inner tube assembly 3 inside the core barrel outer tube assembly 2.

[0121] Step 2, normal drilling:

[0122] Dry gas extraction boreholes are drilled without introducing water or air. The rotation of the drill rod blades 404 of the drill rod 4, transmitted by signal transmission, pushes coal slag out of the borehole. The two rotatable blades 105 of the electrically driven openable drill bit 1 are in a closed state, that is, the axial front end of the central through hole 102 is completely sealed to prevent impurities from entering the inner tube channel 30202. The front ball valve core 30104 and the rear ball valve core of the rear electrically controlled valve 303 of the inner tube are in an open state, allowing for full-section drilling.

[0123] Step 3, closed-loop pressure-maintaining core extraction:

[0124] When drilling reaches the predetermined coal seam section, an action signal is sent to the electrically driven openable drill bit 1 via the signal transmission drill rod 4. The two rotatable cutter blades 105 rotate 90° to open, and the coal body passes sequentially through the central through hole 102 of the electrically driven openable drill bit 1, the axial front section of the first outer tube channel 20102, the second outer tube channel 20203, and the front valve body channel 30103, and finally enters the inner tube channel 30202. When the drilling depth is equal to the length of the inner tube channel 30202, an action signal is sent to the front valve core drive motor 30105 and the rear valve core drive motor of the rear electrically controlled valve 303 of the inner tube via the signal transmission drill rod 4. The front ball valve core 30104 and the rear ball valve core of the rear electrically controlled valve 303 at both ends of the core tube assembly 3 rotate 90° to close, sealing the coal body in the inner tube channel 30202 and maintaining its original state.

[0125] Step 4: Remove the core sampler:

[0126] The special retrieval spearhead is lowered and hooks onto the retrieval mechanism 304. After the connection is secure, an action signal is sent to the solenoid valve assembly 20206 through the signal transmission drill rod 4. The locking tongue 20207 at the rear end of the inner tube retracts radially to release the axial restriction on the inner tube assembly 3 of the core barrel. At this time, the inner tube assembly 3 of the core barrel can be pulled out of the borehole in sequence along the third outer tube channel 20302, the male connector channel 40102 of the transmission rod, and the rear end channel 40302 of the transmission rod.

[0127] Step 5: Insert a new core extraction tube:

[0128] Lower the new core barrel inner tube assembly 3. When the axial front end of the core barrel inner tube assembly 3 contacts the inner tube front end limiting surface 20204, an axial front end limiting is formed. The axial rear end of the core barrel inner tube assembly 3 is blocked by the inner tube rear end locking tongue 20207 extending radially to form an axial rear end limiting. Continue drilling and repeat step three.

[0129] When a borehole is designed with continuous closed pressure coring, steps three, four, and five can be repeated.

[0130] Step Six, Drilling:

[0131] After the coring operation is completed, the drill bit is pulled out of the hole, and the coal in the inner tube assembly 3 of multiple core tubes can form a continuous in-situ coal sample for subsequent experimental analysis according to the sampling sequence.

Claims

1. A drilling tool for continuous, pressure-maintaining, closed-loop coring without media in fractured soft coal seams, characterized in that, Along the axial direction from front to back, it includes an electrically driven openable drill bit (1) that is coaxially arranged and hollow inside, a core barrel outer tube assembly (2) and a signal transmission drill rod (4). The core barrel outer tube assembly (2) has a hollow core barrel inner tube assembly (3) coaxially installed inside. The electrically driven openable drill bit (1) is connected to the signal transmission drill rod (4) through an insulated wire or a conductive block, thereby realizing the opening or closing of the electrically driven openable drill bit (1). The outer tube assembly (2) of the core barrel is connected to the signal transmission drill rod (4) through an insulated wire or a conductive block, thereby enabling axial positioning of the inner tube assembly (3) of the core barrel; The core tube inner tube assembly (3) is connected to the signal transmission drill rod (4) through an insulated wire or a conductive block, thereby enabling the opening or closing of the axial ends of the internal cavity of the core tube inner tube assembly (3); The outer wall of the signal transmission drill rod (4) is also integrally and coaxially provided with a spirally wound drill rod blade (404).

2. The drilling tool for continuous, pressure-maintaining, closed-loop coring of soft, fractured coal seams without media, as described in claim 1, is characterized in that... The electrically driven openable drill bit (1) includes a drill bit body (101), and a central through hole (102) is coaxially opened in the drill bit body (101) that passes through both ends of the axial direction. The diameter of the front section of the central through hole (102) is smaller than the diameter of the rear section of the central through hole (102). The stepped surface at the connection between the front section of the central through hole (102) and the rear section of the central through hole (102) is the first limiting surface (103) at the front end of the outer tube. The drill bit body (101) is also integrally provided with multiple fixed blades (104) at its axial front end. The multiple fixed blades (104) are evenly distributed circumferentially on the outer edge of the axial front end of the drill bit body (101). The drill bit body (101) is also embedded with a rear handle conductive block (107) and a rear handle insulating wrapping layer (108) on its axial rear end face. The rear handle insulating wrapping layer (108) isolates the rear handle conductive block (107) from the drill bit body (101). The rear handle conductive block (107) is connected to the drive motor of the electrically driven openable drill bit (1) through an insulated wire.

3. The drilling tool for continuous, pressure-maintaining, closed-loop coring of soft, fractured coal seams without media, as described in claim 2, is characterized in that... The drill bit body (101) is provided with two rotatable blades (105) arranged symmetrically at the center of its axial front end. When closed, the two rotatable blades (105) seal the axial front end of the central through hole (102). The drill bit body (101) is also provided with a blade rotation shaft (106) at its axial front end. The blade rotation shaft (106) corresponds one-to-one with the rotatable blades (105). The two rotatable blades (105) are mounted on the drill bit body (101) through the corresponding blade rotation shaft (106). The two rotatable blades (105) can also rotate 90° around the corresponding blade rotation shaft (106) under the drive of the drive motor of the electrically driven openable drill bit (1).

4. The drilling tool for continuous, pressure-maintaining, closed-loop coring of soft, fractured coal seams without media, as described in claim 2, is characterized in that... The core tube outer tube assembly (2) comprises, from front to back, an integrated coaxially arranged male connector (201) for the front end of the outer tube, a core tube body (202) for the outer tube, and a female connector (203) for the rear end of the outer tube; The aforementioned outer tube front end male connector (201) includes a cylindrical outer tube front end male connector body (20101). The axial front end of the outer tube front end male connector body (20101) is axially limited by the outer tube front end first limiting surface (103). The outer tube front end male connector body (20101) is connected to the drill bit body body (101) by external thread. The outer tube front end male connector body (20101) is also coaxially provided with an axially penetrating first outer tube channel (20102). The axial front end of the first outer tube channel (20102) is connected to the axial rear end of the central through hole (102). The core tube outer tube body (202) includes a cylindrical outer tube body (20201). The axial front end of the outer tube body (20201) is limited by the axial rear end face of the drill bit body body (101). Multiple outer tube front conductive units (20202) are also embedded and uniformly arranged along the circumferential direction on the axial front end face of the outer tube body (20201). The outer tube front conductive units (20202) can contact the rear conductive block (107) to achieve mutual communication. The outer tube body (20201) is also coaxially provided with an axially penetrating second outer tube channel (20203). The axial front end of the second outer tube channel (20203) is connected to the axial rear end of the first outer tube channel (20102). The stepped surface of the second outer tube channel (20203) near the axial front end is the inner tube front end limiting surface (20204). The core tube inner tube assembly (3) is also installed in the second outer tube channel (20203). The maximum inner diameter of the second outer tube channel (20203) is equal to the maximum outer diameter of the core tube inner tube assembly (3).

5. The drilling tool for continuous, pressure-maintaining, closed-loop coring of soft, fractured coal seams without media, as described in claim 4, is characterized in that... The inner wall of the outer tube body (20201) is also embedded with multiple outer tube inner wall conductive units (20205). The inner wall of the outer tube body (20201) near the axial rear end is also embedded with a solenoid valve assembly (20206) and an inner tube rear end locking tongue (20207). The solenoid valve assembly (20206) can drive the inner tube rear end locking tongue (20207) to extend and retract radially along the second outer tube channel (20203), thereby limiting the axial rear end of the core tube inner tube assembly (3). The outer tube rear end female connector (203) includes an outer tube rear end female connector body (20301), and a third outer tube channel (20302) is coaxially opened inside the outer tube rear end female connector body (20301). The axial front end of the third outer tube channel (20302) is connected to the axial rear end of the second outer tube channel (20203). A stepped transmission rod front end limiting surface (20304) is also provided inside the third outer tube channel (20302).

6. The drilling tool for continuous, pressure-maintaining, closed-loop coring of soft, fractured coal seams without media, as described in claim 5, is characterized in that... The outer tube rear end female connector body (20301) is also uniformly embedded in the circumferential direction on the axial rear end surface. The outer tube rear end conductive unit (20303) includes an outer tube rear end conductive block (2030301). The outer tube rear end conductive block (2030301) is isolated from the outer tube rear end female connector body (20301) by the outer tube rear end insulating wrapping layer (2030302). The outer tube rear end conductive block (2030301) can contact the signal transmission drill rod (4) to achieve mutual communication. The structure of the outer tube front end conductive unit (20202) is the same as that of the outer tube rear end conductive unit (20303); The outer tube inner wall conductive unit (20205) includes an outer tube inner wall conductive block (2020501), which is isolated from the outer tube body (20201) by an outer tube inner wall insulating wrapping layer (2020502); The conductive block of the outer tube front end conductive unit (20202), the conductive block of the outer tube inner wall (2020501), the solenoid valve assembly (20206), and the conductive block of the outer tube rear end (2030301) are interconnected by insulated wires and are insulated from the outer tube front end male connector body (20101), the outer tube body body (20201), and the outer tube rear end female connector body (20301).

7. The drilling tool for continuous, pressure-maintaining, closed-loop coring of soft, fractured coal seams without media, as described in claim 6, is characterized in that... The core-collecting tube inner tube assembly (3) includes, from front to back, a coaxially arranged and threadedly connected front-end electric valve (301), a core-collecting tube inner tube body (302), a rear-end electric valve (303), and a retrieval mechanism (304); the structure of the front-end electric valve (301) is the same as that of the rear-end electric valve (303), and the two are arranged symmetrically at both ends of the axial direction of the core-collecting tube inner tube body (302); The aforementioned internal tube front-end electrically controlled valve (301) includes a front-end valve body housing (30101), which, along the axial direction from front to back, includes an integrated coaxially arranged front-end valve body seat (3010101) and a front-end valve body (3010102). The axial front end of the front-end valve body seat (3010101) is axially limited by the internal tube front-end limiting surface (20204). The outer diameter of the front-end valve body seat (3010101) is equal to the maximum inner diameter of the second external tube channel (20203). An embedded device is also installed on the outer side wall of the front-end valve body seat (3010101). Multiple inner tube front-end conductive units (30102) are evenly arranged circumferentially. Each inner tube front-end conductive unit (30102) includes an inner tube front-end conductive block (3010201). The inner tube front-end conductive block (3010201) is isolated from the front-end valve seat (3010101) by the inner tube front-end insulating wrapping layer (3010202). The inner tube front-end conductive block (3010201) also corresponds one-to-one with and is interconnected with the outer tube inner wall conductive block (2020501) at the axial front end near the outer tube body (20201). The front valve body (3010102) is also coaxially provided with an axially penetrating front valve body channel (30103). The front valve body channel (30103) extends forward along the axial direction, penetrates the interior of the front valve body seat (3010101), and is connected to the axial rear end of the third outer tube channel (20302). The cavity of the front valve body channel (30103) in the middle section of the front valve body (3010102) is a spherical cavity. A front ball valve core (30104) is also installed in the spherical cavity. A front valve core drive motor (30105) is also installed on the front valve body (3010102). The front valve core drive motor (30105) can drive the front ball valve core (30104) to open or close the front valve body channel (30103).

8. The drilling tool for continuous, pressure-maintaining, closed-loop coring of soft, fractured coal seams without media, as described in claim 7, is characterized in that... The core sampling tube inner tube body (302) includes an inner tube body body (30201), and an inner tube body channel (30202) is coaxially opened inside the inner tube body body (30201). The diameter of the inner tube body channel (30202) is equal to the diameter of the front valve body channel (30103). The axial front end of the inner tube body channel (30202) is connected to the axial rear end of the front valve body channel (30103). The inner tube rear end electrically controlled valve (303) includes a rear end valve body channel, the axial front end of which is connected to the axial rear end of the inner tube body channel (30202); the axial rear end of the rear end valve body seat of the inner tube rear end electrically controlled valve (303) can be axially limited by the inner tube rear end locking tongue (20207); the rear end valve body seat of the inner tube rear end electrically controlled valve (303) is also connected to the axial front end of the coaxially arranged salvage mechanism (304) through internal thread; the rear end valve body seat of the inner tube rear end electrically controlled valve (303) is also provided with an inner tube rear end conductive block, and the inner tube rear end conductive block is also one-to-one corresponding to and connected to the outer tube inner wall conductive block (2020501) near the axial rear end of the outer tube body (20201). The inner tube front conductive block (3010201), the front valve core drive motor (30105), the inner tube rear electrically controlled valve (303) and the inner tube rear electrically controlled valve (303) are connected by insulated wires and are all isolated from the front valve body shell (30101), the inner tube body (30201) and the inner tube rear electrically controlled valve (303).

9. The drilling tool for continuous, pressure-maintaining, closed-loop coring of soft, fractured coal seams without media, as described in claim 6, is characterized in that... The signal transmission drill rod (4) includes, from front to back, a transmission rod male connector (401), a transmission rod tube body (402), and a transmission rod female connector (403) that are coaxially arranged and connected in sequence. The male connector (401) of the transmission rod includes a male connector body (40101), which is connected to the female connector body (20301) at the rear end of the outer tube by an external thread; the male connector body (40101) of the transmission rod also has an axially through male connector channel (40102) coaxially opened inside, and the axial front end of the male connector channel (40102) is connected to the third outer tube channel (20302); An embedded conductive block (40103) for the front end of the transmission rod is installed on the end face of the male connector (401) near the inner end of the male connector body (40101). The conductive block (40103) for the front end of the transmission rod is insulated and protected by the insulating wrapping layer (40104) for the front end of the transmission rod. The conductive block (40103) for the front end of the transmission rod can contact and communicate with the conductive block (2030301) for the rear end of the outer tube. The transmission rod tube body (402) includes a transmission rod tube body body (40201), and the transmission rod tube body body body (40201) is also coaxially provided with an axially penetrating transmission rod tube body body channel (40202). The female transmission rod connector (403) includes a female transmission rod connector body (40301), and the female transmission rod connector body (40301) is also coaxially provided with an axially penetrating transmission rod rear end channel (40302). The axial front end of the rear end channel (40302) is connected to the axial rear end of the male transmission rod connector channel (40102) through the transmission rod tube body channel (40202). The inner diameter of the rear end channel (40302), the inner diameter of the transmission rod tube body channel (40202), and the inner diameter of the male transmission rod connector channel (40102) are all greater than the maximum outer diameter of the core tube inner tube assembly (3). The axial rear end face of the female connector body (40301) of the transmission rod is also embedded with a transmission rod rear end conductive block (40303), which is insulated and protected by the transmission rod rear end insulating wrapping layer (40304); the transmission rod rear end conductive block (40303) is also connected to the transmission rod front end conductive block (40103) through an insulated wire.

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