Constant pressure output downhole turbine power generation device and method

Abstract

The application discloses a constant-voltage output downhole turbine power generation device and method, and belongs to the technical field of oil or natural gas drilling. In the turbine generator body, a generator rotor shaft rotates to cut a generator stator coil to output three-phase alternating current. The three-phase alternating current is rectified and adjusted to output, and the output is parallelly led out in two ways. One way is connected to a power consumption unit as a generator output, and the other way is transmitted to a comparison circuit. In the comparison circuit, an output current value is compared with a preset current value to determine a difference value. After processor operation, an adjustment instruction is sent to an execution unit. Through two ways, the first way adjusts the driving turbine speed to synchronously change the turbine generator rotor shaft speed, and the second way directly acts on the generator rotor shaft. Both ways can change the generator output. After continuous fitting, the constant-voltage output of the turbine generator is finally realized. The application solves the problem of unstable generator output caused by displacement fluctuation, and is suitable for popularization and application.

Description

Technical Field

[0001] This invention relates to the field of oil or natural gas drilling technology, and in particular to a constant pressure output downhole turbine generator and method. Background Technology

[0002] In the field of oil and gas drilling, downhole turbine generators, as power supply units for downhole drilling instruments, are widely used due to their ability to provide power for extended periods and deliver high power output. Currently, both domestically and internationally, downhole turbine generators require the selection of appropriate turbine components based on the drilling fluid discharge rate. This approach necessitates the preparation of various turbine components with different blade inclination angles, inevitably increasing the manufacturing cost of the turbine components. During drilling operations, changes in drilling technology or complex downhole conditions can cause variations in drilling fluid discharge rate over a wide range, resulting in significant differences in the high and low speeds of the drive turbine. This leads to abnormal fluctuations in the generator's output. Such fluctuations place extremely high demands on the generator's subsequent rectification and voltage regulation output. Due to the limited space and severe vibrations downhole, it is very difficult to directly regulate the generator's output voltage from an electrical perspective. It is necessary to address the issue from the perspective of the downhole turbine generator's structure itself, reducing the impact of changes in generator rotor shaft speed caused by discharge rate variations, and maintaining a constant output from the downhole turbine generator.

[0003] In the prior art, invention patent CN201510830422.6 discloses a downhole turbine generator for measurement while drilling (MSD), including a turbine drive unit, a generator unit connected to the turbine drive unit, a brake clamping device mounted on the generator rotor shaft, and an electronic control unit. The turbine drive unit is located outside the generator unit's rotor shaft. When drilling fluid passes through the blades of the turbine drive unit, the blades rotate under the action of the fluid, thereby driving the generator unit's rotor to rotate. The blade inclination angle is variable to adjust the output voltage stability of the downhole turbine generator when using different drilling fluid media and different flow rates during MSD. The brake clamping device can reduce the rotor speed by clamping the generator rotor shaft; the electronic control unit collects the generator's output voltage and issues commands to further adjust the generator speed. For downhole turbine generators used in drilling measurement, a method to regulate the generator output is proposed by using a brake clamping device to reduce the generator rotor shaft speed. However, this mechanical clamping device cannot precisely control the clamping force, inevitably requiring multiple clamping actions. Furthermore, the pure friction clamping method causes significant wear on the generator rotor shaft, which is detrimental to long-term use. There is an urgent need in the existing technology for a constant-pressure output downhole turbine generator device and method. Summary of the Invention

[0004] The purpose of this invention is to overcome two shortcomings of existing downhole turbine generators: first, different turbine components need to be replaced according to the drilling fluid discharge rate; second, the drilling fluid discharge rate varies significantly due to changes in drilling processes or complex downhole conditions, resulting in significant differences in high and low turbine speeds, leading to abnormal fluctuations in generator output and making the design of rectifier and voltage regulator circuits difficult. This invention provides a constant-pressure output downhole turbine generator device and method. This technical solution compares the generator output with the preset value of the circuit module and issues adjustment information to change the rotor shaft speed of the downhole turbine generator in real time, keeping the rotor shaft speed constant within a certain range, thus achieving constant-pressure output from the generator.

[0005] The embodiments of the present invention are implemented as follows:

[0006] On one hand, the embodiments of this invention provide a constant pressure output downhole turbine generator, including a turbine generator body, a generator rotor shaft, a constant current regulator, a constant pressure output device, a comparator circuit, a processor, an execution unit-drive turbine, and an execution unit-magnetorheological fluid. The turbine generator body and the constant current regulator are electrically connected. The generator rotor shaft is located in the turbine generator body. The two execution units are connected to the generator rotor shaft, but the two execution units are not used simultaneously. The execution unit changes the generator rotor shaft speed in response to the processor command. The constant current regulator is connected to the comparator circuit, the processor, and the execution unit in sequence. After the execution unit executes the processor command, it adjusts the generator rotor shaft speed to make the turbine generator output constant pressure.

[0007] In a preferred embodiment of the present invention, the constant pressure output downhole turbine generator device, which uses a drive turbine to regulate the rotational speed of the generator rotor shaft, further includes a flow guide, a sealed floating piston, a dynamic sealing assembly, a centralizing end plug, an outer magnetic coupling protective cover, an outer magnetic coupling plate, an inner magnetic coupling plate, a sliding bearing, a generator housing, a magnetically shielded sealing cover, a wire guide spindle, a rotating slip ring assembly, a linear motor, a conical pusher, a preload spring, and a turbine protective sleeve. The flow guide, installed in the turbine protective cover, provides support and enhances the efficiency of the drive turbine. The sealed floating piston is installed on the side wall of the drive turbine. The dynamic sealing assembly and the centralizing end plug form a sealed space inside the drive turbine. The rotating slip ring assembly and the linear motor are installed inside the sealed space. The outer magnetic coupling plate is installed inside the outer magnetic coupling protective cover, and the inner magnetic coupling plate is installed on the generator rotor shaft. The sliding bearing is installed between the outer magnetic coupling protective cover and the magnetically shielded sealing cover. The generator rotor shaft is fixed to the generator housing by a set of rolling bearings. The wire guide spindle passes through the generator rotor shaft, and a preload spring is fixed inside the drive turbine blades.

[0008] In a preferred embodiment of the present invention, the constant pressure output downhole turbine generator further includes a magnetic block, a stator coil, a circuit chamber, an excitation coil, a moving ring, a fixed ring, and a magnetic shielding sleeve. The magnetic block is mounted around the surface of the generator rotor shaft. The stator coil is mounted coaxially with the generator rotor shaft outside the magnetic block. The comparator circuit and processor are mounted in the circuit chamber. The excitation coil is mounted at the tail end of the generator body, and a magnetic shielding sleeve is installed inside it. The magnetic shielding sleeve, the moving ring, and the fixed ring of the dynamic sealing assembly form a sealed space, and the magnetorheological fluid is filled into the sealed space.

[0009] A constant-pressure output downhole turbine power generation method is characterized by the following steps: In the turbine generator body, the generator rotor shaft rotates and cuts the generator stator coil to output three-phase AC power. The three-phase AC power is rectified and regulated, and the output is led out in parallel with two paths. One path is used as the generator output and connected to the power consumption unit, and the other path is transmitted to the comparison circuit. In the comparison circuit, the output current value is compared with the preset current value and the difference is determined. After the processor calculates, the adjustment command is sent to the execution unit. By adjusting the speed of the drive turbine to synchronously change the speed of the turbine generator rotor shaft or by directly acting on the generator rotor shaft, the generator output changes. After continuous fitting, the constant-pressure output of the turbine generator is finally achieved.

[0010] In a preferred embodiment of the present invention, the step of synchronously changing the rotor shaft speed of the turbine generator by adjusting the speed of the drive turbine is specifically as follows: When the downhole turbine generator is working, the drilling fluid flowing at high speed in the axial direction is accelerated by the deflection of the blades of the guide vane in the turbine protective sleeve and impacts the blades of the drive turbine. The turbine blades are squeezed by the drilling fluid, causing the drive turbine to rotate, and driving the outer magnetic coupling protective cover fixed thereto to rotate at the same speed. The outer magnetic coupling protective cover is equipped with an outer magnetic coupling plate, and an inner magnetic coupling plate arranged corresponding to the outer magnetic coupling plate is fixed on the generator rotor shaft. A magnetic shielding seal is installed between the outer magnetic coupling plate and the inner magnetic coupling plate to isolate the internal components of the downhole turbine generator from the external drilling fluid. A pair of sliding bearings are arranged between the magnetic shielding seal and the outer magnetic coupling protective cover. The inner and outer magnetic coupling plates maintain the same speed under the action of magnetic induction, realizing the rotational motion of the outer magnetic coupling plate is transmitted to the inner magnetic coupling plate without contact and linked to the generator rotor shaft. The generator rotor shaft rotates and cuts the generator stator coil to generate electrical energy output.

[0011] A set of cables containing power and adjustment command signals passes through a mandrel inside the generator rotor shaft. The mandrel is fixed at both ends and maintains sufficient clearance from the generator rotor shaft. The cables are led out from the cable holes of the mandrel, pass through the centering end plug, and communicate with the inner ring of the rotating slip ring assembly 14 fixed to its end face. The outer ring of the rotating slip ring assembly is fixed inside the drive turbine and rotates synchronously with the turbine. This set of rotating slip ring assemblies is used to convert the power and adjustment command signals from a fixed state to a rotating state synchronized with the drive turbine. The linear motor is also fixed inside the drive turbine.

[0012] The centralizing end plug and the magnetic shielding cover are threadedly connected, keeping the centralizing end plug stationary with the generator body. A set of rolling bearings is installed on the surface of the centralizing end plug, and the drive turbine is fitted onto these rolling bearings, allowing the drive turbine to rotate along the axis of the centralizing end plug. The linear motor is fixed inside the drive turbine. Because the drive turbine is a rotating component, and the outside is drilling fluid, a closed cavity must be formed inside. Therefore, a dynamic sealing design is required inside the drive turbine: a dynamic sealing assembly is installed on the contact face between the drive turbine and the centralizing end plug. This structure is fixedly placed on the inner wall of the drive turbine. O-rings ensure the sealing performance between the dynamic sealing assembly and the inner wall of the drive turbine. A set of thrust springs compresses the dynamic sealing assembly to keep its sealing surface pressed against the end face of the centralizing end plug. The end face of the centralizing end plug is polished. Insulating hydraulic oil is filled into the internal cavity of the drive turbine, and a sealed floating piston is designed and installed, floating freely in the drive turbine to maintain the internal and external pressure balance of the drive turbine.

[0013] After receiving an action command, the linear motor in the drive turbine controls the extension or retraction of its motor shaft. A conical pusher is fixedly installed at the top of the motor shaft. The angle of the conical pusher is designed to match the angle at the root of the drive turbine blade. When the motor shaft extends, the conical pusher moves to the left inside the blade, pushing the blade to extend outward. When the motor shaft retracts, a preload spring extending from the blade pulls the blade inward. The extension and retraction of the linear motor shaft enables controllable extension length of the drive turbine blade. When the drilling fluid discharge changes, the extension length of the blade changes accordingly, keeping the output speed of the drive turbine stable and achieving constant pressure output of the turbine generator.

[0014] In a preferred embodiment of the present invention, the direct action on the generator rotor shaft specifically involves: the drilling fluid flowing at high speed in the axial direction impacts and drives the turbine to rotate after passing through the guide, and the generator rotor shaft rotates at the same speed. The magnetic blocks arranged circumferentially on the generator rotor shaft move relative to the stator coils, cutting magnetic lines of force to generate current output. At the end of the generator rotor shaft, the rotor shaft is designed to be extended, with the extended part extending into the magnetic shielding sleeve. Dynamic sealing components are installed at both ends of the magnetic shielding sleeve. When the generator rotor shaft rotates, the contact friction surfaces of the dynamic ring and the stator ring of the dynamic sealing component move relative to each other to form a sealed cavity. A magnetorheological fluid filled with metal particles is injected into the cavity. An excitation coil is installed outside the magnetic shielding sleeve. When the excitation coil is energized, it generates a magnetic field. The viscosity of the magnetorheological fluid in the magnetic field will change, and this viscosity depends on the magnetic field strength.

[0015] The rectified generator output line is led to the circuit compartment. In the circuit compartment, one output is led out directly through the circuit compartment, and the other output is transmitted to the comparator circuit. After the comparator circuit calculates, it is converted into a fixed current output. This current is led to the excitation coil and forms a closed loop. The magnitude of this current determines the magnetic field strength generated by the excitation coil. If the magnetic field strength is increased, the viscosity of the magnetorheological fluid increases, and the counter torque on the generator rotor shaft increases. If the magnetic field strength is decreased, the viscosity of the magnetorheological fluid decreases, and the counter torque on the generator rotor shaft decreases. By changing the counter torque, the speed of the generator rotor shaft is kept stable, and the constant voltage output of the turbine generator is achieved.

[0016] The beneficial effects of the embodiments of the present invention are:

[0017] This invention provides a constant-pressure output downhole turbine generator device and method. When the drilling fluid discharge rate changes, the output of the downhole turbine generator changes accordingly. After the changed output is processed by a comparison circuit, an adjustment command is sent to the execution unit. After the execution unit is activated, the rotational speed of the generator rotor shaft is adjusted to achieve constant-pressure output of the downhole turbine generator. This avoids the need to replace the drive turbine due to different drilling fluid discharge rates and solves the problem of unstable generator output caused by discharge rate fluctuations. It is suitable for widespread application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the electrical control principle of the constant pressure output downhole turbine generator of the present invention;

[0020] Figure 2 This is a schematic diagram of the constant pressure output downhole turbine generator in Embodiment 1 of the present invention;

[0021] Figure 3 This is a schematic diagram of the constant pressure output downhole turbine generator in Embodiment 2 of the present invention.

[0022] In the diagram, 1-flow guide, 2-drive turbine, 3-sealed floating piston, 4-dynamic seal assembly, 5-aligning end plug, 6-outer magnetic coupler protective cover, 7-inner magnetic coupler plate, 8-outer magnetic coupler plate, 9-sliding bearing, 10-turbine generator body, 11-magnetic shielding cover, 12-generator rotor shaft, 13-wire guide shaft, 14-rotating slip ring assembly, 15-linear motor, 16-conical pusher frame, 17-preload spring, 18-turbine protective sleeve, 19-magnetic block, 20-stator coil, 21-circuit chamber, 22-excitation coil, 23-dynamic ring, 24-stator ring, 25-magnetic shielding sleeve, 26-magnetorheological fluid. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Please refer to Figure 1 In the generator body, the generator rotor shaft rotates and cuts the generator stator coil to output three-phase AC power. The three-phase AC power is rectified and regulated, and then output in parallel to two paths. One path is used as the generator output and connected to the power consumption unit. The other path is transmitted to the comparison circuit. In the comparison circuit, the output current value is compared with the preset current value and the difference is determined. After the processor calculates, the adjustment command is sent to the execution unit. Two methods are used: Method 1 adjusts the speed of the drive turbine to synchronously change the speed of the turbine generator rotor shaft; Method 2 directly acts on the generator rotor shaft. Both methods can change the generator output. After continuous fitting, the constant voltage output of the turbine generator is finally achieved.

[0025] The following two examples illustrate how method 1 and method 2 utilize the execution unit to change the rotor shaft speed of the turbine generator:

[0026] Example 1

[0027] Figure 2This is a schematic diagram of a constant-pressure output downhole turbine generator according to an embodiment of the present invention. When the downhole turbine generator is working, the axially high-speed flowing drilling fluid in the turbine protective sleeve 18 is deflected and accelerated by the blades of the guide vane 1, impacting the blades of the driving turbine 2. The turbine blades are squeezed by the drilling fluid, causing the driving turbine to rotate, which in turn drives the external magnetic coupling protective cover 6, which is fixed to it, to rotate at the same speed. An external magnetic coupling plate 8 is installed inside the external magnetic coupling protective cover, and an inner magnetic coupling plate 7, corresponding to the external magnetic coupling plate, is fixed on the generator rotor shaft 12. A magnetically shielding sealing cover 11 is installed between the external and internal magnetic coupling plates to isolate the internal components of the downhole turbine generator from the external drilling fluid. A pair of sliding bearings 9 are arranged between the magnetically shielding sealing cover and the external magnetic coupling protective cover to reduce frictional losses during relative rotation. The inner and outer magnetic coupling plates maintain rotation at the same speed under magnetic induction, realizing contactless transmission of the rotational motion of the outer magnetic coupling plate to the inner magnetic coupling plate and linkage with the generator rotor shaft. The rotating generator rotor shaft cuts the generator stator coils to generate electrical energy output.

[0028] A set of cables containing power and adjustment command signals passes through the wire guide spindle 13 inside the generator rotor shaft. The two ends of the wire guide spindle are fixed and maintain sufficient clearance with the generator rotor shaft to prevent the generator rotor shaft from contacting the wire guide spindle when rotating. The cables are led out from the wire guide hole of the wire guide spindle, pass through the straightening end plug 5, and are connected to the inner ring of the rotary slip ring assembly 14 fixed to its end face. The outer ring of the rotary slip ring assembly is fixed in the drive turbine and rotates synchronously with the turbine. This set of rotary slip ring assemblies is used to convert the power and adjustment command signals from a fixed state to a rotating state synchronized with the drive turbine. The linear motor 15 is also fixed in the drive turbine. This arrangement ensures that the outer ring of the rotary slip ring assembly always remains relatively stationary with the linear motor. The power and adjustment command signals led out from the outer ring of the rotary slip ring assembly can be transmitted to the linear motor to power the linear motor and control the displacement of the motor motion actuator.

[0029] The centering end plug 5 and the magnetic shielding cover 11 are fixedly connected by threads, so that the centering end plug and the generator body remain stationary. A set of rolling bearings is installed on the surface of the centering end plug, and the drive turbine is sleeved on the rolling bearings, so that the drive turbine can rotate along the axis of the centering end plug. The linear motor is fixed inside the drive turbine. Because the drive turbine is a rotating component, the outside is drilling fluid, and the inside needs to form a sealed cavity, a dynamic seal design is required inside the drive turbine: a dynamic seal assembly 4 is installed on the contact end face between the drive turbine and the centralizing end plug. This structure is fixedly placed on the inner wall of the drive turbine. An O-ring seal ensures the sealing performance between the dynamic seal assembly and the inner wall of the drive turbine. A set of thrust springs compresses the dynamic seal assembly so that its sealing surface is always pressed against the end face of the centralizing end plug. The end face of the centralizing end plug is polished to ensure the reliability of the dynamic seal. Since the outside of the drive turbine is high-pressure drilling fluid and the inside is at normal pressure, an excessive pressure difference between the inside and outside will inevitably cause the intrusion of high-pressure drilling fluid. Therefore, insulating hydraulic oil is injected into the internal cavity of the drive turbine, and a sealed floating piston 3 is designed and installed, which can float freely in the drive turbine, so that the internal and external pressures of the drive turbine are kept in balance.

[0030] After receiving an action command, the linear motor in the drive turbine controls the extension or retraction of the motor shaft. A conical pusher 16 is fixedly installed at the top of the motor shaft. The angle of the conical pusher is designed to match the angle of the root of the drive turbine blade. When the motor shaft extends, the conical pusher moves to the left inside the blade, pushing the blade to extend outward. When the motor shaft retracts, the preload spring 17 extending from the blade pulls the blade inward. The extension and retraction of the linear motor shaft enables controllable extension length of the drive turbine blade. When the drilling fluid discharge changes, the extension length of the blade changes accordingly, keeping the output speed of the drive turbine stable and achieving constant pressure output of the turbine generator.

[0031] Example 2

[0032] Figure 3 This is a schematic diagram of another constant-pressure output downhole turbine generator according to an embodiment of the present invention. Axially high-speed drilling fluid, after passing through the guide 1, impacts and drives the turbine 2 to rotate. The generator rotor shaft 12 rotates at the same speed. Magnetic blocks 19 arranged circumferentially on the generator rotor shaft move relative to the stator coil 20, cutting magnetic lines of force to generate current output. At the end of the generator rotor shaft, the rotor shaft is elongated, with the elongated portion extending into the magnetic shielding sleeve 25. Dynamic sealing components are installed at both ends of the magnetic shielding sleeve. When the generator rotor shaft rotates, the contact friction surfaces of the dynamic ring 23 and the fixed ring 24 of the dynamic sealing component move relative to each other to form a sealed cavity. A magnetorheological fluid 26 filled with metal particles is injected into the cavity. An excitation coil 22 is installed outside the magnetic shielding sleeve. When the excitation coil is energized, it generates a magnetic field. The viscosity of the magnetorheological fluid in the magnetic field changes, and this viscosity depends on the magnetic field strength.

[0033] The rectified generator output line is led to the circuit compartment 21. In the circuit compartment, one output is led out directly through the circuit compartment, and the other output is transmitted to the comparator circuit. After processing by the processor, the comparator circuit converts the output into a fixed current output. This current is led to the excitation coil and forms a closed loop. The magnitude of this current determines the magnetic field strength generated by the excitation coil. This magnetic field strength affects the viscosity characteristics of the magnetorheological fluid: when the magnetic field strength increases, the viscosity of the magnetorheological fluid increases, and the counter-torque on the generator rotor shaft increases; when the magnetic field strength decreases, the viscosity of the magnetorheological fluid decreases, and the counter-torque on the generator rotor shaft decreases. Counter-torque is the determining factor affecting the rotational speed of the generator rotor shaft. By changing the counter-torque, the rotational speed of the generator rotor shaft is kept stable, thus achieving constant pressure output of the turbine generator.

[0034] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A constant-pressure output downhole turbine generator, characterized in that, The device includes a turbine generator body, a generator rotor shaft, a constant current regulator, a constant pressure output device, a comparator circuit, a processor, an execution unit-drive turbine, and an execution unit-magnetorheological fluid. The turbine generator body and the constant current regulator are electrically connected. The generator rotor shaft is located in the turbine generator body. The execution unit-drive turbine and the execution unit-magnetorheological fluid are both connected to the generator rotor shaft, but they are not used simultaneously. The execution unit changes the generator rotor shaft speed in response to processor commands. The constant current regulator is connected to the comparator circuit, the processor, and the execution unit in sequence. After executing the processor commands, the execution unit adjusts the generator rotor shaft speed to achieve constant pressure output from the turbine generator. The execution unit—drive turbine—includes a guide vane, a sealed floating piston, a dynamic sealing assembly, a centralizing end plug, an outer magnetic coupling protective cover, an outer magnetic coupling plate, an inner magnetic coupling plate, a sliding bearing, a generator housing, a magnetically shielded sealing cover, a wire guide spindle, a rotating slip ring assembly, a linear motor, a conical pusher, a preload spring, and a turbine protective sleeve. The guide vane, installed in the turbine protective cover, supports and enhances the drive turbine. The sealed floating piston is installed on the side wall of the drive turbine. The dynamic sealing assembly and the centralizing end plug form a sealed space inside the drive turbine. The rotating slip ring assembly and the linear motor are installed inside the sealed space. The outer magnetic coupling plate is installed inside the outer magnetic coupling protective cover, and the inner magnetic coupling plate is installed on the generator rotor shaft. The sliding bearing is installed between the outer magnetic coupling protective cover and the magnetically shielded sealing cover. The generator rotor shaft is fixed to the generator housing by a set of rolling bearings. The wire guide spindle passes through the generator rotor shaft, and a preload spring is fixed inside the drive turbine blades. The execution unit-magnetorheological fluid includes a magnetic block, a stator coil, a circuit chamber, an excitation coil, a moving ring, a fixed ring, and a magnetic shielding sleeve. The magnetic block is mounted around the surface of the generator rotor shaft. The stator coil is mounted coaxially with the generator rotor shaft outside the magnetic block. The comparator circuit and processor are installed in the circuit chamber. The excitation coil is installed at the tail end of the generator body, and a magnetic shielding sleeve is installed inside it. The magnetic shielding sleeve, the moving ring, and the fixed ring of the dynamic sealing assembly form a sealed space, and the magnetorheological fluid is filled into the sealed space.

2. A constant-pressure output downhole turbine power generation method, characterized in that, The constant-pressure output downhole turbine generator device according to claim 1 includes the following steps: In the turbine generator body, the generator rotor shaft rotates and cuts the generator stator coil to output three-phase AC power. The three-phase AC power is rectified and regulated for output. The output is connected in parallel to two paths. One path is used as the generator output and connected to the power consumption unit. The other path is transmitted to the comparison circuit. In the comparison circuit, the output current value is compared with the preset current value and the difference is determined. After the processor calculates, the adjustment command is sent to the execution unit. By adjusting the speed of the drive turbine to synchronously change the speed of the turbine generator rotor shaft or by directly acting on the generator rotor shaft, the generator output changes. After continuous fitting, the constant-pressure output of the turbine generator is finally achieved.

3. The constant pressure output downhole turbine power generation method according to claim 2, characterized in that, The method of synchronously changing the rotor shaft speed of the turbine generator by adjusting the speed of the drive turbine is as follows: When the downhole turbine generator is working, the drilling fluid flowing at high speed in the axial direction is accelerated by the deflection of the blades of the guide vane in the turbine protective sleeve and then impacts the blades of the drive turbine. The turbine blades are squeezed by the drilling fluid, causing the drive turbine to rotate, and driving the outer magnetic coupler protective cover fixed to it to rotate at the same speed. The outer magnetic coupler protective cover is installed inside the outer magnetic coupler protective cover, and the inner magnetic coupler is fixed on the generator rotor shaft. A magnetic shielding seal is installed between the outer magnetic coupler and the inner magnetic coupler to isolate the internal components of the downhole turbine generator from the external drilling fluid. A pair of sliding bearings are arranged between the magnetic shielding seal and the outer magnetic coupler protective cover. The inner and outer magnetic couplers maintain the same speed under the action of magnetic induction, realizing the rotational motion of the outer magnetic coupler is transmitted to the inner magnetic coupler without contact and linked to the generator rotor shaft. The generator rotor shaft rotates and cuts the generator stator coil to generate electrical energy output. A set of cables containing power and adjustment command signals passes through a wire guide mandrel inside the generator rotor shaft. The two ends of the wire guide mandrel are fixed and maintain sufficient clearance with the generator rotor shaft. The cables are led out from the wire guide holes of the wire guide mandrel, pass through the centering end plug, and communicate with the inner ring of the rotating slip ring assembly fixed to its end face. The outer ring of the rotating slip ring assembly is fixed inside the drive turbine and rotates synchronously with the turbine. This set of rotating slip ring assemblies is used to convert the power and adjustment command signals from a fixed state to a rotating state synchronized with the drive turbine. The linear motor is also fixed inside the drive turbine. The centering end plug and the magnetic shielding cover are fixedly connected by threads, keeping the centering end plug and the generator body stationary. A set of rolling bearings is installed on the surface of the centering end plug, and the drive turbine is sleeved on these rolling bearings, causing the drive turbine to rotate along the axis of the centering end plug. The linear motor is fixed inside the drive turbine. Because the drive turbine is a rotating component, the outside is drilling fluid, and the inside needs to form a sealed cavity, a dynamic sealing design is required inside the drive turbine: a dynamic sealing assembly is installed on the contact end face between the drive turbine and the centering end plug. The dynamic sealing assembly is fixedly placed on the inner wall of the drive turbine. An O-ring seal ensures the sealing performance between the dynamic sealing assembly and the inner wall of the drive turbine. A set of thrust springs compresses the dynamic sealing assembly so that its sealing surface always presses against the end face of the centering end plug. The end face of the centering end plug is polished. Insulating hydraulic oil is injected into the internal cavity of the drive turbine, and a sealed floating piston is designed and installed to float freely in the drive turbine, so that the internal and external pressures of the drive turbine are kept in balance. After receiving an action command, the linear motor in the drive turbine controls the extension or retraction of its motor shaft. A conical pusher is fixedly installed at the top of the motor shaft. The angle of the conical pusher is designed to match the angle at the root of the drive turbine blade. When the motor shaft extends, the conical pusher moves to the left inside the blade, pushing the blade to extend outward. When the motor shaft retracts, a preload spring extending from the blade pulls the blade inward. The extension and retraction of the linear motor shaft controls the extension length of the drive turbine blade. When the drilling fluid discharge changes, the extension length of the blade changes accordingly, keeping the output speed of the drive turbine stable and achieving constant pressure output of the turbine generator.

4. The constant pressure output downhole turbine power generation method according to claim 2, characterized in that, The direct action on the generator rotor shaft is as follows: the drilling fluid flowing at high speed in the axial direction impacts and drives the turbine to rotate after passing through the guide, and the generator rotor shaft rotates at the same speed. The magnetic blocks arranged on the circumference of the generator rotor shaft move relative to the stator coils, cutting the magnetic lines of force to generate current output. At the end of the generator rotor shaft, the rotor shaft is designed to be extended, and the extended part extends into the magnetic shielding sleeve. Dynamic sealing components are installed at both ends of the magnetic shielding sleeve. When the generator rotor shaft rotates, the contact friction surfaces of the dynamic ring and the stator ring of the dynamic sealing component move relative to each other to form a sealed cavity. A magnetorheological fluid filled with metal particles is injected into the cavity. An excitation coil is installed outside the magnetic shielding sleeve. When the excitation coil is energized, it generates a magnetic field. The viscosity of the magnetorheological fluid in the magnetic field will change. The viscosity depends on the magnetic field strength. The rectified generator output line is led to the circuit compartment. In the circuit compartment, one output is led out directly through the circuit compartment, and the other output is transmitted to the comparator circuit. After the comparator circuit and processor calculate, it is converted into a fixed current output. This current is led to the excitation coil and forms a closed loop. The magnitude of this current determines the magnetic field strength generated by the excitation coil. If the magnetic field strength is increased, the viscosity of the magnetorheological fluid increases, and the counter torque on the generator rotor shaft increases. If the magnetic field strength is decreased, the viscosity of the magnetorheological fluid decreases, and the counter torque on the generator rotor shaft decreases. By changing the counter torque, the rotational speed of the generator rotor shaft is kept stable, and the constant voltage output of the turbine generator is achieved.

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