Self-powered mud pulse generator based on EHA and control method thereof

Abstract

The invention relates to an EHA-based self-powered mud pulse generator and a control method thereof. An execution component is in sliding connection with a shell, and a hydraulic driving component is connected with the execution component; the internal gearing cycloid gear pump is connected with the hydraulic driving part, and the driving motor is connected with the internal gearing cycloid gear pump; the displacement sensor is arranged on the execution component and used for detecting the moving distance of the execution component, the displacement sensor and the driving motor are both connected with the closed-loop control unit, and the closed-loop control unit is used for receiving underground measurement information sent by the outside and information sent by the displacement sensor. And the driving motor is controlled to rotate forwards and backwards according to underground measurement information and information sent by the displacement sensor, so that the execution component reciprocates to generate a mud pulse signal. According to the mud pulse generator and the control method thereof, the execution component is directly driven through the hydraulic driving component, arrangement of a traditional hydraulic pipeline or installation of a motor speed reducing mechanism is omitted, and the mud pulse generator and the control method thereof belong to the technical field of petroleum drilling and production equipment.

Description

Technical Field

[0001] This invention relates to the field of oil drilling and production equipment technology, specifically to a self-powered mud pulse generator based on EHA and its control method. Background Technology

[0002] In the field of oil and gas drilling engineering, measurement while drilling (MWD) systems are one of the core technologies for achieving precise drilling of complex well types (such as shale gas horizontal wells and deep-sea directional wells). Among these technologies, the mud pulse generator, as the core component for downhole signal generation in the MWD system, functions by generating pulse signals through the control of drilling fluid (mud) pressure changes, transmitting key data such as real-time downhole acquisition of temperature, pressure, and wellbore trajectory to the surface receiving system. There are two main types of driving methods for mud pulse generators: one is the traditional hydraulic drive type, which uses a downhole hydraulic source to drive the valve core in reciprocating motion, changing the cross-sectional area of ​​the mud flow channel to generate pulses; the other is the direct-drive type, which uses a servo motor in conjunction with a reduction gear mechanism to drive the valve plate to rotate or translate, thus opening and closing the flow channel.

[0003] Traditional hydraulically driven equipment relies on complex oil circuits, which poses a risk of oil leakage and results in significant energy transmission losses, leading to unstable pulse signal strength and a high data transmission error rate.

[0004] Direct-drive motor equipment often uses a reduction gear mechanism. The mechanical transmission gap will delay the valve core action and generate a lot of heat during operation, which will reduce the stability of real-time data transmission in high-speed drilling scenarios. Summary of the Invention

[0005] To address the technical problems existing in the prior art, the purpose of this invention is to provide an EHA-based self-powered mud pulse generator and its control method, which directly drives the actuator through a hydraulic drive component, eliminating the need for traditional hydraulic pipeline layout or motor reduction mechanism installation, thereby improving the driving efficiency and signal transmission stability of the electric mud pulse generator.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A self-powered mud pulse generator based on EHA includes a housing, a closed-loop control unit, an actuator, a displacement sensor, a drive motor, an internal cycloidal gear pump, and a hydraulic drive unit. The actuator is slidably connected to the housing, and the hydraulic drive unit is connected to the actuator to drive the actuator to move relative to the housing. The internal cycloidal gear pump is connected to the hydraulic drive unit to deliver hydraulic oil, and the drive motor is connected to the internal cycloidal gear pump to drive the pump. The displacement sensor is mounted on the actuator to detect the distance the actuator moves. Both the displacement sensor and the drive motor are connected to the closed-loop control unit. The closed-loop control unit receives downhole measurement information sent from the outside and information sent by the displacement sensor, and controls the drive motor to rotate forward and backward according to the downhole measurement information and information sent by the displacement sensor, so that the actuator reciprocates to generate mud pulse signals.

[0007] As a preferred embodiment, the actuating component includes a conical valve, a push rod, and a guide block. The conical valve is slidably connected to the housing. One end of the push rod is connected to the conical valve, and the other end of the push rod is connected to the hydraulic drive component. The guide block is installed on the inner side wall of the housing and has a guide hole that penetrates the guide block. The push rod is slidably connected to the guide hole.

[0008] As a preferred embodiment, the hydraulic drive component includes a piston, an upper chamber guide pipe, a lower chamber guide pipe, and a cylindrical valve block. The cylindrical valve block is installed inside the housing and has two oil passages, both of which are connected to an internal meshing cycloidal gear pump. The two oil passages are respectively connected to the upper chamber guide pipe and the lower chamber guide pipe. The piston has a rodless chamber and a rod chamber, and the upper chamber guide pipe and the lower chamber guide pipe communicate with the rodless chamber and the rod chamber, respectively. The piston is slidably disposed within the housing. The actuator is connected to the piston, and the piston is used to drive the actuator to move relative to the housing.

[0009] As a preferred embodiment, a pressure compensator is also included. The surface of the pressure compensator is provided with a first small hole, and the outer shell is provided with a second small hole. The first small hole and the second small hole are aligned. The pressure compensator is provided with a balance bladder inside, and the balance bladder is connected to a cylindrical valve block. When the mud flows through the outer shell, some of the mud enters the interior of the pressure compensator through the second small hole and the first small hole. As the external mud pressure changes, the balance bladder will contract and expand to balance the oil pressure with the external mud pressure.

[0010] As a preferred embodiment, the cylindrical valve block is equipped with a first hydraulically controlled check valve, a second hydraulically controlled check valve, a first balance valve, a second balance valve, a first overflow valve, a second overflow valve, a first flow channel, a second flow channel, a third flow channel, a fourth flow channel, a fifth flow channel, a sixth flow channel, a seventh flow channel, an eighth flow channel, a ninth flow channel, a tenth flow channel, and an eleventh flow channel. The first and second flow channels are respectively connected to the inlet and outlet ports of the internal meshing cycloidal gear pump through two oil passages. The third flow channel leads to the balance oil bladder. The first flow channel is connected to the fourth and fifth flow channels. The fourth flow channel leads to the inlet port of the second balance valve, and the fifth flow channel leads to the control port of the first hydraulically controlled check valve. The second flow channel is connected to the sixth and seventh flow channels. The sixth flow channel leads to the control port of the first balance valve. The oil inlet and the seventh flow channel lead to the control port of the second hydraulic check valve; the third flow channel connects to the eighth, ninth, and tenth flow channels respectively. The eighth flow channel leads to the oil inlet of the second hydraulic check valve, the ninth flow channel leads to the oil inlet of the first hydraulic check valve, and the tenth flow channel leads to the node between the first and second relief valves; the oil outlet of the second balance valve is connected to the eleventh flow channel, which is connected to the twelfth and thirteenth flow channels respectively. The thirteenth flow channel leads to the oil inlet of the second relief valve, and the twelfth flow channel leads to the rodless chamber; the oil outlet of the first balance valve is connected to the fourteenth flow channel, which is connected to the fifteenth and sixteenth flow channels respectively. The sixteenth flow channel leads to the oil inlet of the first relief valve, and the fifteenth flow channel leads to the rod chamber.

[0011] As a preferred embodiment, it also includes a self-generating energy storage unit, which comprises a mud guide wheel, a turbine drive assembly, a generator, and a lithium battery pack. The mud guide wheel corresponds to the turbine drive assembly, the turbine drive assembly cooperates with the generator, the lithium battery pack is installed inside the casing, and the generator is connected to the lithium battery pack. The mud guide wheel guides the mud to the turbine drive assembly, causing the mud to impact the turbine drive assembly and rotate. The turbine drive assembly drives the generator to operate, enabling the generator to generate kinetic energy to produce electricity, which is stored in the lithium battery pack. The lithium battery pack is connected to the drive motor for power supply.

[0012] A control method for a self-powered mud pulse generator, comprising the following steps: Resistance extension stage: When the actuator of the mud pulse generator extends, the rod chamber is under low pressure and the rodless chamber is under high pressure. The control signal of the closed-loop control unit causes the drive motor to rotate forward, and the drive motor drives the inner rotor of the internal meshing cycloidal gear pump to rotate counterclockwise. The output high-pressure oil flows to the rodless chamber, so that the actuator completes the extension action. The low-pressure oil in the rod chamber flows back to the inlet of the internal meshing cycloidal gear pump; If there is oil overflow in the internal meshing cycloidal gear pump, the overflowing oil flows to the balance oil reservoir, and the oil in the balance oil reservoir flows back to the rod chamber. Beyond the retraction phase: When the actuator of the mud pulse generator retracts, the rod chamber is under low pressure and the rodless chamber is under high pressure; the control signal of the closed-loop control unit causes the drive motor to drive the inner rotor of the internal meshing cycloidal gear pump to rotate clockwise, and the output oil flows to the rod chamber, so that the actuator completes the retraction action; The high-pressure oil in the rodless chamber flows back to the inlet of the internal meshing cycloidal gear pump; If the internal meshing cycloidal gear pump has excessively high oil pressure, the overflowing oil flows back to the balance oil bladder, and the excess oil flowing to the rod chamber flows back to the balance oil bladder for filling.

[0013] As an alternative, the mud kinetic energy recovery and storage stage: the downhole mud flows around the self-powered mud pulse generator. When the mud flows past the mud guide wheel, its flow direction is guided to the turbine drive assembly. The turbine drive assembly drives the generator to rotate, and the generator generates electricity through the principle of electromagnetic induction. The generated electrical energy is stored in the lithium battery pack.

[0014] In summary, the present invention has the following advantages: 1. The self-powered mud pulse generator of the present invention adopts an EHA drive structure in which a permanent magnet synchronous motor directly drives an internal meshing cycloidal gear pump, which simplifies the hydraulic system pipeline and reduces energy loss. At the same time, the internal meshing cycloidal gear pump has the characteristics of small size and stable flow, and is suitable for the confined space environment downhole.

[0015] 2. The self-powered mud pulse generator of the present invention uses a displacement sensor to provide real-time feedback of the push rod position signal, and a motor controller to precisely control the forward and reverse rotation of the permanent magnet synchronous motor, replacing the traditional mechanical limit method. This effectively avoids push rod movement jamming and impact problems, improves the stability and consistency of pulse signals, and reduces the data transmission error rate.

[0016] 3. The self-powered mud pulse generator of the present invention generates electricity by driving a generator with the kinetic energy of mud and storing it in a lithium battery pack, thus eliminating the dependence on wired power supply or disposable batteries, extending the equipment's endurance, reducing the frequency of downtime for battery replacement, and improving drilling operation efficiency. Attached Figure Description

[0017] Figure 1 A 3D view of a self-powered mud pulse generator.

[0018] Figure 2 A top view of a self-powered mud pulse generator.

[0019] Figure 3 for Figure 2 Schematic diagram of sectional view AA.

[0020] Figure 4 for Figure 2 Schematic diagram of the cross-sectional view of BB.

[0021] Figure 5 The hydraulic schematic diagram of a self-powered mud pulse generator.

[0022] Among them, 1 is a conical valve, 2 is a push rod, 3 is a displacement sensor, 4 is a housing, 5 is a guide block, 6 is a piston, 7 is an upper chamber oil guide pipe, 8 is a lower chamber oil guide pipe, 9 is a base bracket, 10 is an internal meshing cycloidal gear pump, 11 is a cylindrical valve block, 12 is a closed-loop control unit, 13 is a pressure compensator, 14 is a drive motor, 15 is a lithium battery pack, 16 is a mud guide wheel, 17 is a generator turbine, 18 is a generator turbine bearing, 19 is a generator external magnet, 20 is a generator internal magnet, 21 is a generator magnetic shaft, 22 is a generator magnetic shaft bearing, 23 is a generator coil, 24 is a permanent magnet, 25 is a first hydraulic control check valve, 26 is a second hydraulic control check valve, 27 is a first balance valve, 28 is a second balance valve, 29 is a first overflow valve, 30 is a second overflow valve, 31 is a third check valve, 32 is a turbine bearing sleeve, 33 is a magnetic shaft bearing sleeve, and 34 is a second small hole.

[0023] a is the first flow channel, d is the second flow channel, e is the third flow channel, a1 is the fourth flow channel, a2 is the fifth flow channel, d1 is the sixth flow channel, d2 is the seventh flow channel, e1 is the eighth flow channel, e2 is the ninth flow channel, e3 is the tenth flow channel, b is the eleventh flow channel, b1 is the twelfth flow channel, b2 is the thirteenth flow channel, c is the fourteenth flow channel, c1 is the fifteenth flow channel, and c2 is the sixteenth flow channel. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to specific embodiments.

[0025] Example 1 like Figures 1-5As shown, this embodiment provides a self-powered mud pulse generator based on EHA, including a housing 4, a closed-loop control unit 12, an actuator, a displacement sensor 3, a drive motor 14, an internal meshing cycloidal gear pump 10, and a hydraulic drive unit. The actuator is slidably connected to the housing 4, and the hydraulic drive unit is connected to the actuator to drive the actuator to move relative to the housing 4. The internal meshing cycloidal gear pump 10 is connected to the hydraulic drive unit to deliver hydraulic oil, and the drive motor 14 is connected to the internal meshing cycloidal gear pump 10 to drive the internal meshing cycloidal gear pump 10. The displacement sensor 3 is installed on the actuator to detect the distance the actuator moves. Both the displacement sensor 3 and the drive motor 14 are connected to the closed-loop control unit 12. The closed-loop control unit 12 receives downhole measurement information sent from the outside and information sent by the displacement sensor 3, and controls the drive motor 14 to rotate forward and backward according to the downhole measurement information and information sent by the displacement sensor 3, so that the actuator reciprocates to generate mud pulse signals. It should be noted that the closed-loop control unit 12 is an existing motor controller, and the drive motor 14 is an existing permanent magnet synchronous motor. A signal line channel is provided in the housing 4 to the cavity containing the closed-loop control unit 12. The signal collected by the displacement sensor 3 can be transmitted to the closed-loop control unit 12 through this channel. The displacement sensor 3 is a laser displacement sensor with a measurement accuracy of not less than ±0.01mm. The downhole measuring instrument transmits the measured information to the closed-loop control unit 12. The closed-loop control unit 12 converts the downhole measurement information into a control signal for the drive motor. Based on the control signal and the signal from the displacement sensor 3, the closed-loop control unit 12 controls the motor to rotate forward and backward, thereby generating a pulse signal. The internal meshing cycloidal gear pump 10 and the drive motor 14 are mounted on the base bracket 9, which provides mounting support for the overall structure. The base bracket is installed inside the housing, and one end of the internal meshing cycloidal gear pump 10 is connected to the drive motor 14 via a coupling.

[0026] The actuating components include a conical valve 1, a push rod 2, and a guide block 5. The conical valve 1 is slidably connected to the housing 4. One end of the push rod 2 is connected to the conical valve 1, and the other end is connected to the hydraulic drive component. The guide block 5 is installed on the inner wall of the housing 4 and has a guide hole that penetrates the guide block 5. The push rod 2 is slidably connected to the guide hole. The push rod 2 is threadedly connected to both the conical valve 1 and the piston 6. The guide block 5 is interference-fitted to the housing 4. The fixed end of the displacement sensor 3 is threadedly connected to the guide block 5, and the movable end of the displacement sensor 3 is threadedly connected to the push rod 2, allowing the movable end of the displacement sensor 3 to move with the push rod and detect the distance the push rod moves.

[0027] The hydraulic drive component includes a piston 6, an upper chamber guide pipe 7, a lower chamber guide pipe 8, and a cylindrical valve block 11. The cylindrical valve block 11 is installed inside the housing 4 and has two oil passages, both of which are connected to the internal meshing cycloidal gear pump 10. The two oil passages are respectively connected to the upper chamber guide pipe 7 and the lower chamber guide pipe 8. The piston 6 has a rodless chamber and a rod chamber. The upper chamber guide pipe 7 and the lower chamber guide pipe 8 communicate with the rodless chamber and the rod chamber, respectively. The piston 6 is slidably disposed within the housing 4. The actuator is connected to the piston 6, and the piston 6 is used to drive the actuator to move relative to the housing 4. The cylindrical valve block is connected to the housing 4 by a threaded connection.

[0028] The self-powered mud pulse generator also includes a pressure compensator 13. The surface of the pressure compensator 13 has a first small hole, and the outer casing 4 has a second small hole 34. The first and second small holes 34 are aligned. Inside the pressure compensator 13 is a balancing bladder, which is connected to a cylindrical valve block 11. When mud flows through the outer casing 4, some mud enters the pressure compensator 13 through the second and first small holes. As the external mud pressure changes, the balancing bladder contracts and expands, balancing the oil pressure with the external mud pressure. Simultaneously, it serves as an oil tank to supply oil to the hydraulic drive components, reducing the overall volume.

[0029] The cylindrical valve block 11 contains a first hydraulically controlled check valve 25, a second hydraulically controlled check valve 26, a first balance valve 27, a second balance valve 28, a first overflow valve 29, a second overflow valve 30, a first flow channel a, a second flow channel d, a third flow channel e, a fourth flow channel a1, a fifth flow channel a2, a sixth flow channel d1, a seventh flow channel d2, an eighth flow channel e1, a ninth flow channel e2, a tenth flow channel e3, and an eleventh flow channel b. The first flow channel a and the second flow channel d are connected to the inlet and outlet ports of the internally meshing cycloidal gear pump 10 via two oil passages, respectively. The third flow channel e leads to the balance oil bladder. The first flow channel a connects to the fourth flow channel a1 and the fifth flow channel a2. The fourth flow channel a1 leads to the inlet port of the second balance valve 28, and the fifth flow channel a2 leads to the control port of the first hydraulically controlled check valve 25. The second flow channel d connects to the sixth flow channel d1 and the seventh flow channel d2. The sixth flow channel d1 leads to the inlet port of the first balance valve 27. The oil port of the seventh flow channel d2 leads to the control oil port of the second hydraulic check valve 26; the third flow channel e connects to the eighth flow channel e1, the ninth flow channel e2, and the tenth flow channel e3 respectively. The eighth flow channel e1 leads to the oil inlet of the second hydraulic check valve 26, the ninth flow channel e2 leads to the oil inlet of the first hydraulic check valve 25, and the tenth flow channel e3 leads to the node between the first relief valve 29 and the second relief valve 30; the oil outlet of the second balance valve 28 connects to the eleventh flow channel... The eleventh flow channel b is connected to the twelfth flow channel b1 and the thirteenth flow channel b2 respectively. The thirteenth flow channel b2 leads to the oil inlet of the second relief valve 30, and the twelfth flow channel b1 leads to the rodless chamber. The oil outlet of the first balance valve 27 is connected to the fourteenth flow channel c. The fourteenth flow channel c is connected to the fifteenth flow channel c1 and the sixteenth flow channel c2 respectively. The sixteenth flow channel c2 leads to the oil inlet of the first relief valve 29, and the fifteenth flow channel c1 leads to the rod chamber.

[0030] This embodiment provides a self-powered mud pulse generator based on EHA, where all hydraulic lines are integrated within a cylindrical valve block. The conical valve is directly driven by a piston, eliminating the need for traditional hydraulic piping arrangements or motor reduction mechanisms. Combined with real-time feedback from a high-precision displacement sensor, the forward and reverse rotation of the drive motor is precisely controlled. The motor speed can be set remotely, thereby adjusting the amplitude and frequency of the mud pulses and enabling the mud pulse generator to perform resistance extension and overrun retraction movements, ensuring stable pulse signal intensity at different well depths.

[0031] The self-powered mud pulse generator also includes a self-generated energy storage unit, which includes a mud guide wheel 16, a turbine drive assembly, a generator, and a lithium battery pack 15. The mud guide wheel 16 corresponds to the turbine drive assembly, which works in conjunction with the generator. The lithium battery pack 15 is installed inside the housing 4, and the generator is connected to the lithium battery pack 15. The mud guide wheel 16 guides the mud to the turbine drive assembly, causing the mud to impact the turbine drive assembly and rotate. The turbine drive assembly drives the generator to run, generating kinetic energy to produce electricity, which is stored in the lithium battery pack 15. The lithium battery pack 15 is connected to the drive motor 14 for power supply. The turbine drive assembly includes a turbine 17, a turbine bearing 18, and a turbine bearing sleeve 32. The generator includes an external generator magnet 19, an internal generator magnet 20, a generator magnetic shaft 21, a magnetic shaft bearing 22, a generator coil 23, and a magnetic shaft bearing sleeve 33. The turbine bearing 18 is fitted onto the outer surface of the magnetic shaft bearing sleeve 33. The inner end face of the turbine bearing 18 forms a positioning fit with the end face of the external generator magnet 19. The outer end face of the turbine bearing 18 forms a positioning fit with the end face of the mud guide wheel 16 and the turbine bearing sleeve 32, respectively. The turbine bearing 18 provides stable support for the rotation of the turbine 17. The external generator magnet 19 is glued to the inner wall of the turbine 17 and can rotate synchronously with the turbine 17. The magnetic shaft bearing 22 is fitted onto the generator magnetic shaft 21. The inner end face of the magnetic shaft bearing 22 forms a positioning fit with the shoulder of the generator magnetic shaft 21. The outer end face of the magnetic shaft bearing 22 forms a positioning fit with the end face of the mud guide wheel 16 and the magnetic shaft bearing sleeve 33, respectively, thus forming the generator magnetic shaft 21. The bidirectional rotating support structure ensures no swaying when the magnetic shaft rotates at high speed. The turbine bearing sleeve 32 is connected to the magnetic shaft bearing sleeve 33 by a threaded connection, and the other end of the magnetic shaft sleeve 33 is connected to the mud guide wheel 16 by a threaded connection. The internal magnet 20 of the generator is fixed to the generator magnetic shaft 21 by adhesive and rotates with the turbine 17. The rotating generator magnetic shaft 21 cuts the magnetic field lines of the generator coil 23, generating an induced electromotive force. The lithium battery pack 15 is fixed in an independent chamber inside the outer casing 4. The mud guide wheel guides the mud to the turbine 17, causing the turbine to rotate due to the impact of the mud. The self-generating energy storage unit generates electricity by recovering the kinetic energy of the mud and stores the electricity in the lithium battery pack 15 to power the drive motor 14 and the closed-loop control unit 12. By integrating a self-generating energy storage unit into the mud pulse generator, energy self-sufficiency is achieved through the recovery of mud kinetic energy, ensuring the sustainability and reliability of its operation.

[0032] Example 2 This embodiment provides a control method for a self-powered mud pulse generator. The method, which employs a self-powered mud pulse generator, includes the following steps: Resistance extension stage: When the actuator of the mud pulse generator extends, the rod chamber is under low pressure and the rodless chamber is under high pressure. The control signal of the closed-loop control unit 12 causes the drive motor 14 to rotate forward. The drive motor 14 drives the inner rotor of the internal meshing cycloidal gear pump 10 to rotate counterclockwise. The output high-pressure oil flows to the rodless chamber, so that the actuator completes the extension action. The low-pressure oil in the rod chamber flows back to the inlet of the internal meshing cycloidal gear pump 10; If there is oil overflow in the internal meshing cycloidal gear pump 10, the overflowing oil flows to the balance oil reservoir, and the oil in the balance oil reservoir flows back to the rod chamber. The specific route of the output high-pressure oil to the rodless chamber is as follows: The output high-pressure oil flows through the first flow channel a to the fourth flow channel a1 and the fifth flow channel a2 respectively; the high-pressure oil in the fourth flow channel a1 flows through the second balance valve 28, and through the control oil circuit, generates control pressure at the control port of the first balance valve 27, causing the first balance valve 27 to be bidirectionally open; the high-pressure oil in the fifth flow channel a2 generates control pressure at the first hydraulically controlled check valve 25 through the control oil circuit, causing the first hydraulically controlled check valve 25 to be open. After flowing out of the second balance valve 28 from the fourth flow channel a1, it flows through the eleventh flow channel b to the twelfth flow channel b1 and the thirteenth flow channel b2 respectively. The eleventh flow channel b connects to the rodless chamber and is used to realize the extension action of the push rod. The thirteenth flow channel b2 flows to the second relief valve 30 to realize oil pressure control.

[0033] The low-pressure oil in the rod chamber flows through the fourteenth flow channel c to the sixteenth flow channel c2 and the fifteenth flow channel c1 respectively. The fourteenth flow channel c is connected to the first balance valve 27. The oil flows through the first balance valve 27 to the second flow channel d, and then to the sixth flow channel d1 and the seventh flow channel d2 respectively. Finally, it flows back to the oil inlet of the internal meshing cycloidal gear pump. The sixteenth flow channel c2 is connected to the first overflow valve 29 to achieve oil pressure control. If the oil pressure is too high, the first overflow valve 29 or the second overflow valve 30 is opened, and the overflowed oil returns to the balance oil bladder through the third flow channel e. At the same time, due to the difference in piston area between the rod chamber and the rodless chamber, more oil flows into the rodless chamber than out of the rod chamber. Therefore, the oil in the balance oil bladder 13 flows through the third flow channel e to the ninth flow channel e2, and then replenishes the low-pressure oil circuit through the first hydraulic check valve 25. Finally, it flows back to the inlet of the internal meshing cycloidal gear pump to achieve compensation for the mismatched flow.

[0034] Beyond the retraction phase: When the actuator of the mud pulse generator retracts, the rod chamber is under low pressure and the rodless chamber is under high pressure. The control signal of the closed-loop control unit 12 causes the drive motor 14 to drive the inner rotor of the internal meshing cycloidal gear pump 10 to rotate clockwise, and the output oil flows to the rod chamber, so that the actuator completes the retraction action. The oil in the rodless chamber flows back to the inlet of the internal meshing cycloidal gear pump 10; If the internal meshing cycloidal gear pump 10 has excessively high oil pressure, the overflowing oil flows back to the balance oil bladder, and the excess oil flowing to the rod chamber flows back to the balance oil bladder for filling.

[0035] The output oil flows through the second flow channel d to the sixth flow channel d1 and the seventh flow channel d2 respectively; the oil in the sixth flow channel d1 flows through the first balance valve 27 and through the control oil circuit generates control pressure at the control port of the second balance valve 28, causing the second balance valve 28 to be bidirectionally open. After flowing out of the first balance valve 27 from the sixth flow channel d1, it flows through the fourteenth flow channel c to the fifteenth flow channel c1 and the sixteenth flow channel c2 respectively. The sixteenth flow channel c2 is connected to the rod chamber, which is used to realize the action of push rod retraction. The sixteenth flow channel c2 flows to the first overflow valve 29 to realize oil pressure control. The oil in the rodless chamber flows through the eleventh flow channel b to the twelfth flow channel b1 and the thirteenth flow channel b2 respectively. The eleventh flow channel b is connected to the second balance valve 28. The oil flows through the second balance valve 28 to the first flow channel a, and then to the fourth flow channel a1 and the fifth flow channel a2 respectively. The high-pressure oil flowing to the fifth flow channel a2 generates control pressure at the control port of the first hydraulic control check valve 25, causing the first hydraulic control check valve 25 to open. The oil flowing to the first flow channel a finally flows back to the oil inlet of the internal meshing cycloidal gear pump. If the oil pressure is too high, the first overflow valve 29 or the second overflow valve 30 is opened, and the overflowed oil returns to the balance oil bladder through the third flow channel e. At the same time, the excess oil flowing to the rod chamber passes through the first hydraulic control check valve 25, and then through the ninth flow channel e2 and the third flow channel e to return to the balance oil bladder for filling (or returns to the balance oil bladder for filling through the check valve 31 on the f flow channel).

[0036] Mud kinetic energy recovery and storage stage: Downhole mud flows around the self-powered mud pulse generator. When the mud flows past the mud guide wheel 16, its flow direction is guided to the turbine drive assembly. The turbine drive assembly drives the generator to rotate. The generator generates electricity through the principle of electromagnetic induction. The generated electrical energy is stored in the lithium battery pack 15. Specifically, the downhole mud flows around the mud pulse generator. The mud guide wheel 16 adopts a streamlined blade design. When the mud flows through the mud guide wheel 16, its flow direction is guided to the generator turbine 17. The mud impacts the blades of the generator turbine 17, causing the generator turbine 17 to rotate around the generator turbine bearing 18. At the same time, the generator external magnet 19 inside the generator turbine 17 rotates synchronously with the turbine, driving the generator internal magnet 20 and the magnetic shaft 21 on the magnetic shaft to rotate. The magnetic shaft 21 rotates around the magnetic shaft bearing 22, generating relative motion with the generator coil 23. Power generation is achieved through the principle of electromagnetic induction. The generated electrical energy is stored in the lithium battery pack 15 and used to drive the motor 14 and the closed-loop control unit 12, ensuring that the entire electric mud pulse generator can work continuously and stably.

[0037] It should be noted that the mud pulse generator pulse generation and closed-loop control stages are as follows: The mud pulse signal generated by the mud pulse generator is a positive pulse, meaning the initial position of the cone valve 1 is at its lowest point. The closed-loop control unit 12 sends a control signal to the drive motor 14 based on downhole measurement information, causing the drive motor 14 to rotate counterclockwise. The mud pulse generator then extends its resistance. The upward movement of the cone valve reduces the mud flow area, increasing the mud pressure inside the drill string. When the displacement sensor 3 detects that the push rod 2 displacement reaches its preset maximum value, it transmits a signal to the closed-loop control unit 12. The closed-loop control unit 12 controls the drive motor 14 to rotate clockwise, causing the mud pulse generator to retract. The downward movement of the cone valve increases the mud flow area, gradually restoring the mud pressure inside the drill string to stability. When the displacement sensor 3 detects that the push rod 2 displacement reaches its minimum value, it transmits a signal to the closed-loop control unit 12, causing the drive motor 14 to rotate counterclockwise. This reciprocating motion generates periodic mud pressure pulses, which carry downhole measurement data to the surface receiving system, completing the data upload. The ground receiving system is an existing system and is not part of the technical solution of this invention, so it will not be described in detail here.

[0038] Hydraulic drive component drive stage: The motion state of the mud pulse generator includes two stages: resistance extension and overtaking retraction. Periodic mud pressure pulses are generated by changing the flow channel cross-sectional area. The lithium battery pack 15 supplies power to the drive motor 14. The closed-loop control unit controls the drive motor 14 to drive the internal meshing cycloidal gear pump 10. The inner rotor of the internal meshing cycloidal gear pump 10 rotates, and the outer rotor meshes accordingly. During this process, the sealed cavity changes periodically to realize the actions of oil suction, oil trapping, and oil discharge, and controls the flow of hydraulic oil to the actuator of the mud pulse generator.

[0039] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A self-powered mud pulse generator based on EHA, characterized in that: The device includes a housing, a closed-loop control unit, an actuator, a displacement sensor, a drive motor, an internal cycloidal gear pump, and a hydraulic drive unit. The actuator is slidably connected to the housing, and the hydraulic drive unit is connected to the actuator to drive the actuator to move relative to the housing. The internal cycloidal gear pump is connected to the hydraulic drive unit to deliver hydraulic oil, and the drive motor is connected to the internal cycloidal gear pump to drive the pump. The displacement sensor is mounted on the actuator to detect the distance the actuator moves. Both the displacement sensor and the drive motor are connected to the closed-loop control unit. The closed-loop control unit receives downhole measurement information sent from the outside and information sent from the displacement sensor, and controls the drive motor to rotate forward and backward based on the downhole measurement information and information sent from the displacement sensor, causing the actuator to reciprocate and generate mud pulse signals.

2. The self-powered mud pulse generator based on EHA according to claim 1, characterized in that: The actuator includes a conical valve, a push rod, and a guide block. The conical valve is slidably connected to the housing. One end of the push rod is connected to the conical valve, and the other end of the push rod is connected to the hydraulic drive component. The guide block is installed on the inner side wall of the housing. The guide block has a guide hole that passes through the guide block, and the push rod is slidably connected to the guide hole.

3. The self-powered mud pulse generator based on EHA according to claim 1, characterized in that: The hydraulic drive component includes a piston, an upper chamber guide pipe, a lower chamber guide pipe, and a cylindrical valve block. The cylindrical valve block is installed inside the housing and has two oil passages, both of which are connected to an internal meshing cycloidal gear pump. The two oil passages are respectively connected to the upper chamber guide pipe and the lower chamber guide pipe. The piston has a rodless chamber and a rod chamber, and the upper chamber guide pipe and the lower chamber guide pipe are connected to the rodless chamber and the rod chamber, respectively. The piston is slidably disposed inside the housing. The actuator is connected to the piston, and the piston is used to drive the actuator to move relative to the housing.

4. The self-powered mud pulse generator based on EHA according to claim 3, characterized in that: It also includes a pressure compensator, which has a first small hole on its surface and a second small hole on its outer shell. The first and second small holes are aligned. The pressure compensator has a balance bladder inside, which is connected to a cylindrical valve block. When the mud flows through the outer shell, some of the mud enters the pressure compensator through the second and first small holes. As the external mud pressure changes, the balance bladder will contract and expand to balance the oil pressure with the external mud pressure.

5. A self-powered mud pulse generator based on EHA according to claim 4, characterized in that: The cylindrical valve block contains a first hydraulically controlled check valve, a second hydraulically controlled check valve, a first balance valve, a second balance valve, a first overflow valve, a second overflow valve, a first flow channel, a second flow channel, a third flow channel, a fourth flow channel, a fifth flow channel, a sixth flow channel, a seventh flow channel, an eighth flow channel, a ninth flow channel, a tenth flow channel, and an eleventh flow channel. The first and second flow channels are connected to the inlet and outlet ports of the internal meshing cycloidal gear pump via two oil passages, respectively. The third flow channel leads to the balance oil bladder. The first flow channel connects to the fourth and fifth flow channels. The fourth flow channel leads to the inlet port of the second balance valve, and the fifth flow channel leads to the control port of the first hydraulically controlled check valve. The second flow channel connects to the sixth and seventh flow channels, and the sixth flow channel leads to the inlet port of the first balance valve. The seventh flow channel leads to the control port of the second hydraulic check valve; the third flow channel connects to the eighth, ninth, and tenth flow channels respectively, the eighth flow channel leads to the inlet of the second hydraulic check valve, the ninth flow channel leads to the inlet of the first hydraulic check valve, and the tenth flow channel leads to the node between the first and second relief valves; the outlet of the second balance valve is connected to the eleventh flow channel, the eleventh flow channel is connected to the twelfth and thirteenth flow channels respectively, the thirteenth flow channel leads to the inlet of the second relief valve, and the twelfth flow channel leads to the rodless chamber; the outlet of the first balance valve is connected to the fourteenth flow channel, the fourteenth flow channel is connected to the fifteenth and sixteenth flow channels respectively, the sixteenth flow channel leads to the inlet of the first relief valve, and the fifteenth flow channel leads to the rod chamber.

6. A self-powered mud pulse generator based on EHA according to claim 5, characterized in that: It also includes a self-generated energy storage unit, which includes a mud guide wheel, a turbine drive assembly, a generator, and a lithium battery pack. The mud guide wheel corresponds to the turbine drive assembly, which works in conjunction with the generator. The lithium battery pack is installed inside the casing, and the generator is connected to the lithium battery pack. The mud guide wheel guides the mud to the turbine drive assembly, causing the mud to impact the turbine drive assembly and rotate. The turbine drive assembly drives the generator to operate, generating kinetic energy to produce electricity, which is stored in the lithium battery pack. The lithium battery pack is connected to the drive motor for power supply.

7. A control method for a self-powered mud pulse generator, characterized in that: The method using the self-powered mud pulse generator as described in claim 6 includes the following steps: Resistance extension stage: When the actuator of the mud pulse generator extends, the rod chamber is under low pressure and the rodless chamber is under high pressure. The control signal of the closed-loop control unit causes the drive motor to rotate forward, and the drive motor drives the inner rotor of the internal meshing cycloidal gear pump to rotate counterclockwise. The output oil flows to the rodless chamber, so that the actuator completes the extension action. The low-pressure oil in the rod chamber flows back to the inlet of the internal meshing cycloidal gear pump; If there is oil overflow in the internal meshing cycloidal gear pump, the overflowing oil flows to the balance oil reservoir, and the oil in the balance oil reservoir flows back to the rod chamber. Beyond the retraction phase: When the actuator of the mud pulse generator retracts, the rod chamber is under low pressure and the rodless chamber is under high pressure; the control signal of the closed-loop control unit causes the drive motor to drive the inner rotor of the internal meshing cycloidal gear pump to rotate clockwise, and the output oil flows to the rod chamber, so that the actuator completes the retraction action; The oil in the rodless chamber flows back to the inlet of the internal meshing cycloidal gear pump; If the internal meshing cycloidal gear pump has excessively high oil pressure, the overflowing oil flows back to the balance oil bladder, and the excess oil flowing to the rod chamber flows back to the balance oil bladder for filling.

8. The control method according to claim 7, characterized in that: The mud kinetic energy recovery and storage stage: The downhole mud flows around the self-powered mud pulse generator. When the mud flows past the mud guide wheel, its flow direction is guided to the turbine drive assembly. The turbine drive assembly drives the generator to rotate. The generator generates electricity through the principle of electromagnetic induction. The generated electrical energy is stored in the lithium battery pack.

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