Permanent magnet eddy current governor for constant torque load heavy load starting and control method thereof

Abstract

The application provides a permanent magnet eddy current governor for constant torque load heavy load starting and a control method thereof, and belongs to the technical field of permanent magnet eddy current transmission speed regulation. The permanent magnet eddy current governor comprises a conductor cylinder, a magnet disc, a transmission shaft and a magnet disc axial traction mechanism. The conductor cylinder is connected with a motor input shaft, the inner wall of the conductor cylinder is fixed with two groups of annular conductor sleeves, the annular conductor sleeves are divided into starting zones and rated working zones in the axial direction, and the two groups of starting zones are separated by an idle zone. The transmission shaft passes through the rear end of the conductor cylinder, the front end is located in the conductor cylinder, and the rear end is connected with a load output shaft. The magnet disc is installed on the shaft rod of the transmission shaft located in the conductor cylinder, and the outer ring surface of the magnet disc is uniformly distributed with permanent magnets. The magnet disc axial traction mechanism is used for driving two magnet discs to synchronously approach or move away from the center of the idle zone. The application can be used for motor idle starting, heavy load controllable starting, load balancing, speed regulation operation and unloading overload protection of constant torque load.

Description

Technical Field

[0001] This invention belongs to the technical field of permanent magnet eddy current drive speed regulation, and specifically discloses a permanent magnet eddy current speed regulator and its control method for heavy-load starting of constant torque load. Background Technology

[0002] Continuous underground transportation equipment in coal mines includes belt conveyors and scraper conveyors. Both scraper conveyors and belt conveyors are multi-motor driven and high-powered, with single motor power reaching 2000kW (belt conveyors) and 1600kW (scraper conveyors). These types of equipment typically have the following operating requirements: heavy-load soft start or controllable start to reduce mechanical and electrical shock during startup; ability to achieve load balancing across multiple motors; timely unloading or load limiting in case of overload; and speed regulation and energy-saving operation during equipment operation.

[0003] Currently, the drive methods used in conveyors mainly include speed-regulating hydraulic couplings based on hydraulic transmission technology, CST controllable drive devices based on liquid viscous transmission technology, variable frequency motors based on frequency conversion technology, and permanent magnet variable frequency synchronous motors.

[0004] Speed-regulating hydraulic couplings are transmission systems based on the principle of hydraulic transmission. The control mechanisms include scoop-tube type and valve-controlled type, and the media include water and oil. They are used in belt conveyors and scraper conveyors.

[0005] Hydraulic transmission is characterized by flexible transmission, which can isolate vibration and eliminate wear. However, it has the following drawbacks: ① Small speed range and low speed control accuracy, typically 0.45–0.97; ② Low driving torque and high heat generation at low speeds; ③ Requires an oil medium, which can easily pollute the environment.

[0006] The CST controllable drive unit is composed of the internal gear ring of a planetary gear reducer and a wet friction (or liquid viscous) clutch. It achieves soft start and power balance through a proportional valve and a complete set of electro-hydraulic control systems. Its transmission principle is liquid viscous transmission technology.

[0007] Advantages: ① It enables the conveyor to start smoothly under various working conditions; ② The starting acceleration is controllable during the starting process.

[0008] Disadvantages: ① The driving torque provided by the equipment is small when running at low speed; ② The speed in the low-speed range is uncontrollable and the speed adjustment range is narrow; ③ The friction pair is a contact transmission, and the quality and wear resistance of the friction plates affect the life and reliability of the equipment; ④ The transmission nature is rigid transmission and there is no vibration isolation capability.

[0009] A frequency converter is a power control device that uses frequency conversion technology and microelectronics technology to control an AC motor by changing the frequency of the motor's power supply.

[0010] The advantages are a smaller starting current surge, convenient speed adjustment, and a wide speed range. The disadvantages are a lower starting torque and insufficient heavy-load starting capacity. Since the motor is directly connected to the load, it does not have overload protection and cannot isolate mechanical shocks to protect the transmission system. During operation, it will generate high-order harmonics, pollute the power grid, and shorten the fatigue life of transmission components.

[0011] Permanent magnet variable frequency synchronous motors have strong starting capabilities and constant torque characteristics, but they are rigidly connected to the working mechanism and cannot isolate mechanical shocks to protect the transmission system.

[0012] Permanent magnet eddy current drive is a new speed regulation and energy-saving technology developed in recent years. It achieves transmission and speed regulation through the relative motion between a permanent magnet and a conductor, and has advantages such as high efficiency and energy saving, effective vibration isolation, reliable operation, long service life, low maintenance costs, and strong environmental adaptability. In particular, it does not generate high-order harmonics and has extremely low maintenance costs, making it the first choice for energy-saving technology transformation of equipment such as fans and pumps.

[0013] Disc-type permanent magnet speed controllers have the following advantages: ① Wear-free transmission, thus eliminating wear issues; ② During operation, a slip difference exists between the driving and driven discs, automatically achieving load balancing for multi-machine drives; ③ Overload can be quickly unloaded; ④ Speed ​​regulation can be achieved by mechanically controlling the air gap. Disadvantages include low starting capability and a narrow speed range, limiting its application to fan and pump loads.

[0014] Magnetic eddy current drive was first proposed by Magnaforce in the United States in 1993, and achieved a breakthrough in 1999. The designed disc-type permanent magnet eddy current speed controller successfully regulated the speed of centrifugal loads such as fans and pumps, significantly improving motor efficiency and exhibiting excellent energy-saving effects. Its structure mainly consists of three parts: a copper conductor rotor, a permanent magnet rotor, and an air gap adjustment mechanism. The conductor rotor is fixed to the motor shaft, and the permanent magnet rotor is fixed to the load shaft. When the conductor rotor rotates, the relative motion between the conductor rotor and the permanent magnet rotor cuts the magnetic lines of force. The alternating magnetic field generates eddy currents on the conductor rotor through the air gap. Simultaneously, the eddy currents generate an induced magnetic field that interacts with the permanent magnet, thereby driving the permanent magnet rotor to rotate in the same direction as the copper rotor. This results in torque being generated on the output shaft on the load side, causing the load to rotate.

[0015] Based on the aforementioned permanent magnet eddy current drive principle, two types of permanent magnet speed control systems have been developed: ① Disc-type permanent magnet eddy current speed controllers, where the output torque and speed are adjusted and controlled by changing the air gap between the driving and driven discs to regulate the magnitude of the air gap magnetic field; ② Cylindrical-type permanent magnet speed controllers, which are developed by converting the conductor disc and magnet disc into a circumferential direction. By adjusting the relative position of the conductor rotor and permanent magnet rotor in the axial direction through the regulator, and changing the meshing area between them, the magnitude of the output torque can be controlled, thereby achieving the regulation of the load speed.

[0016] The shortcomings of permanent magnet eddy current speed control transmission are: ① Low starting torque. It can only be started directly. If the speed controller is engaged after the motor has started under no-load conditions, the slip is at its maximum, resulting in very low starting torque, which can only be used for light loads. ② Narrow speed range. The speed is changed by adjusting the air gap, similar to the voltage regulation speed control of an asynchronous motor. The speed range is very narrow, and it can only be used for fan loads. ③ It can achieve unloading overload protection, but the unloading is not complete.

[0017] There are currently two protection modes. One is the overload protection mode with a fixed air gap, which relies on the low stall point to achieve overload protection. However, since the stall point torque is generally about 0.5 times the maximum torque, the unloading is not complete, and there is slippage and heat generation, which can easily cause high temperature and demagnetize the magnet.

[0018] Another method is to achieve unloading by increasing the air gap, which can completely unload the load, but requires an air gap adjustment mechanism.

[0019] In summary, regardless of hydraulic transmission, viscous fluid transmission, variable frequency drive technology, or permanent magnet synchronous motors, none of these technologies can effectively perform functions such as heavy-load soft start, energy-saving speed regulation, and overload protection for constant torque loads. Therefore, researching new transmission technologies to achieve heavy-load controllable start, multi-machine drive load balancing, energy-saving operation, and overload protection for constant torque loads has significant scientific and practical implications. Summary of the Invention

[0020] To address the issue that existing permanent magnet eddy current speed controllers have low starting torque and cannot simultaneously meet the requirements for heavy-load starting, speed regulation, and unloading overload protection for constant torque loads, this invention provides a permanent magnet eddy current speed controller for heavy-load starting of constant torque loads. By mechanically adjusting its characteristics, the speed regulation range is expanded, the starting torque is increased, and the stall torque is reduced, enabling it to be used for no-load starting, controllable heavy-load starting, load balancing, speed regulation operation, and unloading overload protection of motors with constant torque loads.

[0021] This invention provides a permanent magnet eddy current speed controller for heavy-load starting under constant torque load, comprising a conductor cylinder, a magnet disk, a drive shaft, and an axial traction mechanism for the magnet disk. The conductor cylinder is connected to the motor input shaft. Two sets of annular conductor sleeves are fixed to the inner wall of the conductor cylinder. The annular conductor sleeves are divided into a starting area and a rated working area in the axial direction. The area between the two starting areas is an unloaded area. The permeability and conductivity of the starting area gradually increase from the inside to the outside along the axial direction, reaching their maximum when connected to the rated working area. The permeability and conductivity of the rated working area are fixed. The drive shaft passes through the rear end of the conductor cylinder, with its front end located inside the conductor cylinder and its rear end connected to the load output shaft. The magnet disk is mounted on the shaft of the drive shaft located inside the conductor cylinder. It can move axially on the drive shaft and rotate circumferentially synchronously with the drive shaft. The two magnet disks are symmetrically arranged on both sides of the center of the unloaded area. Permanent magnets are evenly distributed on the outer ring surface of the magnet disks. The magnetic poles of the permanent magnets are radially oriented, with N poles and S poles arranged alternately. The axial traction mechanism for the magnet disk is used to drive the two magnet disks to synchronously approach or move away from the center of the unloaded area.

[0022] Furthermore, the axial traction mechanism of the magnet disk includes a crank-slider mechanism and a magnet disk position adjustment mechanism for driving one of the magnet disks to move axially back and forth; the crank-slider mechanism includes a slider groove, a crank, and a slider; each magnet disk has two slider grooves on the side facing the unloaded area, the two slider grooves are symmetrically arranged on both sides of the transmission shaft, and the direction of the slider grooves is perpendicular to the axial direction of the transmission shaft; the centers of the two cranks are rotatably mounted on the transmission shaft, and the mounting points are located at the center of the unloaded area, and the ends of the cranks are fixed with sliders, which are slidably mounted in the slider grooves.

[0023] Furthermore, the magnet disk position adjustment mechanism is a cam adjustment mechanism. The magnet disk near the front end of the conductor cylinder is the first magnet disk, and the magnet disk near the rear end of the conductor cylinder is the second magnet disk. The cam adjustment mechanism includes an isolation bearing, an inner sleeve of the isolation bearing, a cam guide, an outer sleeve of the isolation bearing with a cam groove, a first connecting arm, a rolling bearing, a cam sleeve, and a second connecting arm. The inner sleeve of the isolation bearing is slidably mounted on the drive shaft, with its front end fixedly connected to the second magnet disk and its rear end fixedly connected to the inner ring of the isolation bearing. The cam sleeve is mounted on the drive shaft via a rolling bearing. The outer sleeve of the isolation bearing is fixedly connected to the outer ring of the isolation bearing and rotatably mounted outside the cam sleeve. The rod end of the cam guide is fixed to the cam sleeve, and the bearing end is rotatably mounted in the cam groove. The first connecting arm is fixed to the outer sleeve of the isolation bearing, and the second connecting arm is fixed to the cam sleeve.

[0024] Furthermore, a first speed measuring gear is fixed to the outside of the conductor cylinder, and a second speed measuring gear is fixed to the outside of the inner sleeve of the isolation bearing; the rotational speed of the first speed measuring gear is detected by a first speed sensor, and the rotational speed of the second speed measuring gear is detected by a second speed sensor.

[0025] Furthermore, a protective cover is provided outside the conductor cylinder, and a water outlet pipe is provided on the protective cover; the conductor cylinder includes a conductor cylinder yoke ring and a conductor cylinder front end plate and a conductor cylinder rear end plate provided at both ends of the conductor cylinder yoke ring; a water outlet connected to the water outlet pipe is provided on the conductor cylinder front end plate, and a water inlet pipe passing through the protective cover is provided on the conductor cylinder rear end plate; a first speed sensor is installed inside the protective cover, and the motor input shaft and the inner sleeve of the isolation bearing both pass through the protective cover.

[0026] Furthermore, the drive shaft includes a profiled shaft section and a circular shaft section; the first magnet disk is sleeved on the profiled shaft section through a profiled shaft sleeve, the second magnet disk is integrally formed with the inner sleeve of the isolation bearing, and the rolling bearing is sleeved on the circular shaft section; the crank-slider mechanism also includes a central shoulder and a double-ended stud; the central shoulder is sleeved on the profiled shaft section; the double-ended stud passes through the crank, the central shoulder and the profiled shaft section, and is located at the center of the unloaded area.

[0027] Furthermore, a first limiting ring is provided at the front end of the drive shaft to limit the axial displacement of the first magnet disk; a second limiting ring is provided at the position of the inner sleeve of the isolation bearing in front of the second speed measuring gear, and a second limiting ring is provided at the position of the drive shaft between the inner sleeve of the isolation bearing and the cam sleeve. The two second limiting rings are used to limit the axial displacement of the inner sleeve of the isolation bearing.

[0028] Furthermore, a disc connector is fixed to the rear end of the cam sleeve, and the second connecting arm is fixed to the disc connector; the front end disc of the conductor cylinder is connected to the motor input shaft through an input coupling and a second bolt; the rear end of the transmission shaft is connected to the shaft end baffle through a sixth bolt, and the transmission shaft is connected to the load output shaft through a flange coupling and a shrinking connecting sleeve.

[0029] This invention provides a control method for the aforementioned permanent magnet eddy current speed controller used for heavy-load starting under constant torque load:

[0030] ① Before the motor starts and after the equipment stops, the magnet disk is in the no-load area, and there is no power transmission between the conductor cylinder and the magnet disk, so the motor can start under no-load conditions;

[0031] ② Load start-up and acceleration: The motor drives the conductor cylinder to rotate, and through the axial traction mechanism of the magnet disk, it drives the two magnet disks to move in opposite directions along the axial direction, synchronously moving away from the center of the unloaded area and entering the start-up area. The annular conductor sleeve in the start-up area moves in the magnetic field generated by the permanent magnet on the magnet disk to cut the magnetic field lines, causing the magnet disk and the conductor cylinder to rotate in the same direction, so that the load follows the movement.

[0032] The two magnet disks continue to move in opposite directions into the rated working area. The eddy current loop impedance at the corresponding position of the magnet disk decreases, and the magnet disk and load accelerate until the load reaches the rated working condition and the magnet disk stops moving.

[0033] ③Speed ​​regulation and load balance: The two magnet disks are driven to move towards or away from each other along the axial direction by the axial traction mechanism of the magnet disk. The eddy current circuit impedance of the conductor cylinder changes with the position of the magnet disk, thereby adjusting the transmission characteristics of the permanent magnet eddy current speed controller and realizing speed regulation and load balance of multiple drives.

[0034] ④ Unloading overload protection: When a sudden overload occurs, the slip difference between the conductor cylinder and the magnet disk suddenly increases, and the operating point quickly drops from the rated point past the maximum torque point to the stall point. The stall torque is small, and because the transmission torque is very small, the motor unloading function is realized.

[0035] ⑤ Equipment stops operating when power is off: After the load stops, the motor is powered off and stops operating. The axial traction mechanism of the magnet disk drives the two magnet disks to move towards each other along the axial direction and return to the unloaded area.

[0036] The present invention has the following beneficial effects:

[0037] This invention regulates the transmission characteristics by altering the axial resistance of the eddy current circuit in the conductor cylinder, thereby adjusting the circuit impedance and achieving: ① motor no-load starting; ② maximizing heavy-load starting capacity using the overturning point; ③ enabling speed-regulating soft starting by adjusting the size of the magnetic pair formed by the evenly distributed permanent magnets on the magnet disk and the annular conductor sleeve embedded in the conductor cylinder, with the starting time and speed pattern arbitrarily set; ④ widening the speed regulation range, ensuring load balancing or a constant overturning point during speed regulation; ⑤ providing operation and overload protection, with the overturning point at its maximum and the stall point at its minimum, achieving both high efficiency and unloading; ⑥ addressing the persistent slippage during starting, operation, and overload protection, especially at low speeds (with large slippage), which leads to low efficiency and heat generation, by incorporating a water-cooling system to remove heat and ensure a safe operating environment for the system. Attached Figure Description

[0038] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 This is a diagram showing the no-load state of a permanent magnet eddy current speed controller.

[0040] Figure 2 This is a diagram showing the rated operating state of a permanent magnet eddy current speed controller.

[0041] Figure 3 This is a side view of the drive shaft;

[0042] Figure 4 This is a side view of the central shoulder;

[0043] Figure 5 This is a magnified view of a portion of the cam guide.

[0044] Figure 6 This is a schematic diagram showing the distribution of permanent magnets on the first magnet disk and conductor material on the conductor cylinder yoke ring.

[0045] Figure 7 This is a side view of the front end of the conductor cylinder.

[0046] Icons: 1. Protective cover, 2. Rated working area, 3. Starting area, 4. Crank, 5. Central shoulder, 6. Threaded cap, 7. Permanent magnet, 8. Inlet pipe, 9. Conductor cylinder rear end plate, 10. Second magnet plate, 11. Conductor cylinder front end plate, 12. Second bolt, 13. Input coupling, 14. Motor input shaft, 15. First limit retaining ring, 16. Profile bushing, 17. Drive shaft, 18. Outlet, 19. Outlet pipe, 20. Third bolt, 21. First magnet plate, 22. Slider groove, 23. Conductor cylinder yoke ring, 24. Isolation bearing outer sleeve, 25. Cam guide 26. First connecting arm, 27. Fourth bolt, 28. Second connecting arm, 29. Flange coupling, 30. Shaft end baffle, 31. Load output shaft, 32. Expansion connecting sleeve, 33. Inner sleeve of isolation bearing, 34. Isolation bearing, 35. Cam sleeve, 36. Rolling bearing, 37. Disc connector, 38. Second limit retaining ring, 39. Fifth bolt, 40. Sixth bolt, 41. Seventh bolt, 42. First bolt, 43. Nut, 44. First speed measuring gear, 45. First speed sensor, 46. Second speed sensor, 47. Second speed measuring gear. Detailed Implementation

[0047] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] This embodiment provides a permanent magnet eddy current speed controller for heavy-load starting under constant torque load, including a protective cover 1, a conductor cylinder, a magnet disk, a drive shaft, and an axial traction mechanism for the magnet disk.

[0049] The protective cover 1 is installed outside the conductor cylinder and fixed to the ground by the third bolt 20. The protective cover 1 serves to isolate and protect the conductor cylinder. A water outlet pipe 19 is installed on the protective cover 1.

[0050] The conductor cylinder includes a conductor cylinder yoke ring 23 and a conductor cylinder front end plate 11 and a conductor cylinder rear end plate 9, which are mounted on both ends of the conductor cylinder yoke ring 23 by a first bolt 42. The conductor cylinder front end plate 11 is provided with a water outlet 18 connected to a water outlet pipe 19, and the conductor cylinder rear end plate 9 is provided with a water inlet pipe 8 passing through a protective cover 1. An input coupling 13 is mounted on the conductor cylinder front end plate 11 by a second bolt 12, and the motor input shaft 14 passes through the protective cover 1 and is connected to the input coupling 13.

[0051] The inner wall of the conductor cylinder is fixedly inlaid with two sets of annular conductor sleeves made of conductor materials. The annular conductor sleeves are divided into a starting area 3 and a rated working area 2 in the axial direction. The area between the two sets of starting areas 3 is an unloaded area. The magnetic permeability and electrical conductivity of the starting area 3 gradually increase from the inside to the outside in the axial direction, and reach the maximum when it is connected to the rated working area 2. The magnetic permeability and electrical conductivity of the rated working area 2 are fixed.

[0052] The drive shaft 17 passes through the rear end of the conductor cylinder, with its front end located inside the conductor cylinder. The rear end is connected to the shaft end baffle 30 by the sixth bolt 40. The two sections of the flange coupling 29 are tightly connected by the seventh bolt 41. Under the action of the fifth bolt 39, the expansion sleeve 32 generates a huge clamping force between the flange coupling 29 and the load output shaft 31.

[0053] The magnet disks are mounted on the shaft of the drive shaft 17 located inside the conductor cylinder. The magnet disk near the front end of the conductor cylinder is the first magnet disk 21, and the magnet disk near the rear end of the conductor cylinder is the second magnet disk 10. The two magnet disks are symmetrically arranged on both sides of the center of the unloaded area. Permanent magnets 7 are evenly distributed on the outer ring surface of the magnet disks. The magnetic poles of the permanent magnets 7 are radial, with N poles and S poles arranged alternately. The magnet disks can move axially on the drive shaft 17 and rotate circumferentially synchronously with the drive shaft 17. The evenly distributed permanent magnets 7 on the circumference of the magnet disks and the conductor material embedded on the conductor cylinder form a magnetic pair. In this embodiment, the drive shaft 17 includes a profiled shaft section (three-sided or four-sided) and a circular shaft section. The first magnet disk 21 is sleeved on the profiled shaft section through a profiled shaft sleeve 16, and the second magnet disk 10 is directly sleeved on the profiled shaft section. A positioning hole is provided on the profiled short shaft at a position corresponding to the center of the unloaded area. The front end of the drive shaft 17 is provided with a first limiting ring 15 for limiting the axial displacement of the first magnet disk 21.

[0054] The axial traction mechanism of the magnet disk is used to drive the two magnet disks to move synchronously closer to or further away from the center of the unloaded area. In this embodiment, it includes a crank-slider mechanism and a magnet disk position adjustment mechanism for driving one of the magnet disks to move axially back and forth. The magnet disk position adjustment mechanism is a cam adjustment mechanism.

[0055] The crank-slider mechanism includes a central shoulder 5, a double-ended stud, a slider groove 22, a crank 4, and a slider. The central shoulder 5 is fitted onto the profiled shaft section. Each magnet disk has two slider grooves 22 on its side facing the unloaded area. The two slider grooves 22 are symmetrically arranged on both sides of the drive shaft 17, and the direction of the slider grooves 22 is perpendicular to the axial direction of the drive shaft 17. The double-ended stud passes through the positioning holes of the crank 4, the central shoulder 5, and the profiled shaft section, and threaded caps 6 are fitted at both ends to realize the rotation of the two cranks 4. A slider is fixed to the end of the crank 4, and the slider is slidably installed in the slider groove 22.

[0056] The cam adjustment mechanism includes an isolation bearing 34, an inner isolation bearing sleeve 33, a cam guide 25, an outer isolation bearing sleeve 24 with a cam groove, a first connecting arm 26, a rolling bearing 36, a cam sleeve 35, and a second connecting arm 28. The inner isolation bearing sleeve 33 is slidably fitted on the drive shaft 17, passes through the protective cover 1, has its front end integrally formed with the second magnet disk 10, and its rear end fixedly connected to the inner ring of the isolation bearing 34. The rolling bearing 36 is fitted on the circular shaft section. The cam sleeve 35 is fitted outside the rolling bearing 36. The outer ring of the isolation bearing 24 is fixedly connected to the outer ring of the isolation bearing 34, and is rotatably sleeved on the outside of the cam sleeve 35; the cam guide 25 is a cylindrical hexagonal needle roller cam with an oil injection nozzle guide, the rod end is a threaded rod, and is fixed to the cam sleeve 35 by a nut 43, and the bearing end is rolled in the cam groove; the first connecting arm 26 is fixed to the isolation bearing outer ring 24 by a fourth bolt 27; a disc connector 37 is fixed to the rear end of the cam sleeve 35, and the second connecting arm 28 is fixed to the disc connector 37. The first connecting arm 26 is connected to the actuator through a connecting rod, and the second connecting arm 28 is connected to the ground through a connecting rod.

[0057] A first speed measuring gear 44 is fixed to the outside of the conductor cylinder, and a second speed measuring gear 47 is fixed to the outside of the inner sleeve 34 of the isolation bearing. Speed ​​measuring holes are distributed around the circumference of the second speed measuring gear 47. The rotational speed of the first speed measuring gear 44 is detected by a first speed sensor 45, which is installed inside the protective cover 1. The rotational speed of the second speed measuring gear 47 is detected by a second speed sensor 46.

[0058] A second limiting ring 38 is provided at the position of the inner sleeve 33 of the isolation bearing in front of the second speed measuring gear 47, and a second limiting ring 38 is provided at the position of the transmission shaft 17 between the inner sleeve 33 of the isolation bearing and the cam sleeve 35. The two second limiting rings 38 are used to limit the axial displacement of the inner sleeve 33 of the isolation bearing.

[0059] The conductor cylinder is connected to the motor input shaft 14 via the input coupling 13 to form the active rotor. The magnet disk, crank-slider mechanism, and transmission shaft 17 are connected to the load output shaft 31 via the output coupling 29 and the expansion coupling sleeve 32 to form the driven rotor. The cam adjustment mechanism is attached to the transmission shaft 17 via the rolling bearing 36. The active rotor, driven rotor, and cam adjustment mechanism together form a speed adjustment mechanism from the motor input shaft 17 to the load output shaft 31.

[0060] The assembly method of the permanent magnet eddy current speed controller used for heavy-load starting under constant torque load is as follows:

[0061] The first limiting ring 15, the first magnet disk 21, the crank slider mechanism, and the isolation bearing inner sleeve 33 with the second magnet disk 10 fixedly connected are sequentially installed on the drive shaft 17. The conductor cylinder yoke ring 23 is connected to the front end disk 11 of the conductor cylinder by a high-strength first bolt 42. Then, the installed drive shaft 17 and its accessories are aligned with the conductor cylinder and the installation distance is determined. The rear end disk 9 of the conductor cylinder and the first speed measuring gear 44 are installed. The second limiting ring 38 and the second speed measuring gear 47 on the isolation bearing inner sleeve 33 are installed. The isolation bearing 34, the rolling bearing 36, the cam sleeve 35 pre-installed with the cam guide 25, the disc connector 37, the isolation bearing outer sleeve 24 with the cam groove, the first connecting arm 26, and the second connecting arm 28 are installed.

[0062] When connecting the motor input shaft 14 and the load output shaft 31, the input coupling 13 is connected to the motor input shaft 14, and the transmission shaft 17 and the load output shaft 31 are connected through the coupling 29 and the expansion coupling sleeve 32.

[0063] Install the inlet pipe 8, the protective cover 1, and the outlet pipe 9. Connect the first connecting arm 26 to the actuator via a connecting rod. Fix the second connecting arm 28 to the ground via a connecting rod. Fix the protective cover 1 to the ground via a third bolt 20.

[0064] The control method for the permanent magnet eddy current speed controller used for heavy-load starting under constant torque load is described below:

[0065] ① Before the motor starts and after the equipment stops, the magnet disk is in the unloaded area. There is no power transmission between the conductor cylinder and the magnet disk. The motor can start under no-load conditions. The motor input shaft 14 drives the conductor cylinder to rotate. At this time, the permanent magnet 7 on the magnet disk does not mesh with the conductor material on the conductor cylinder. The second connecting arm 28 is fixed to fix the cam sleeve 35 and the cam guide 25.

[0066] ② Load Start-up and Acceleration: The conductor cylinder rotates, and the actuator drives the first connecting arm 26 to rotate, causing the outer sleeve of the isolation bearing 24 to rotate and move backward along the transmission shaft 17. This pulls the inner sleeve of the isolation bearing 33 and the second magnet disk 10 connected to it to move backward. Under the action of the crank-slider mechanism, the first magnet disk 21 moves forward synchronously, realizing that the two magnet disks move in opposite directions along the axial direction, synchronously moving away from the center of the unloaded area and entering the starting area. The annular conductor sleeve in the starting area moves in the magnetic field generated by the permanent magnet on the magnet disk, cutting magnetic field lines. According to Lenz's law, induced eddy currents are generated in the conductor material. The induced magnetic fields generated by the induced eddy currents interact with each other, causing the magnet disk and the conductor cylinder to rotate in opposite directions. The magnet disk drives the transmission shaft 17 and the load output shaft 31 connected to it to rotate in the same direction, realizing the load following the movement.

[0067] The speed sensors (45, 46) measure the motor input speed and load output speed and input them into the control system. The control system controls the actuator to continue to operate, so that the two magnet disks continue to move in opposite directions into the rated working area. The eddy current loop impedance at the corresponding position of the magnet disk decreases, and the magnet disk and load accelerate until the load reaches the rated working condition and the magnet disk stops moving.

[0068] ③Speed ​​regulation and load balance: The two magnet disks are driven to move towards or away from each other along the axial direction by the axial traction mechanism of the magnet disk. The eddy current circuit impedance of the conductor cylinder changes with the position of the magnet disk, thereby adjusting the transmission characteristics of the permanent magnet eddy current speed controller and realizing speed regulation and load balance of multiple drives.

[0069] ④ Unloading overload protection: When a sudden overload occurs, the slip difference between the conductor cylinder and the magnet disk suddenly increases, and the operating point quickly drops from the rated point past the maximum torque point to the stall point. The stall torque is small, and because the transmission torque is very small, the motor unloading function is realized.

[0070] ⑤ Equipment stops running when power is off: After the load stops, the motor is powered off and stops running. The axial traction mechanism of the magnet disk drives the two magnet disks to move towards each other along the axial direction and return to the no-load area.

[0071] The method to determine if the motor is stalled is to confirm that, under the condition that the motor is running, the output speed is equal to zero for a specified time (e.g., 3 seconds).

[0072] During the operation of the permanent magnet eddy current speed controller, cooling water flows in from the inlet pipe 8 at the opening between the rear end plate 9 of the conductor cylinder and the inner sleeve 33 of the isolation bearing. It flows through the second magnet plate 10, the conductor cylinder yoke ring 23, the first magnet plate 21, and the front end plate 11 of the conductor cylinder, and then flows out from the outlet 18 set on the front end plate 11 of the conductor cylinder. After gathering at the bottom of the protective cover 1, it flows out from the outlet pipe 19. The cooling system can cool the magnet plate and the inner wall surface of the conductor cylinder, remove heat, and prevent the permanent magnet eddy current speed controller from demagnetizing due to the heat generated by the permanent magnet slippage, thus ensuring the normal operation of the permanent magnet eddy current speed controller.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A permanent magnet eddy current speed controller for heavy-load starting under constant torque load, characterized in that, Includes conductor cylinder, magnet disk, drive shaft and magnet disk axial traction mechanism; The conductor cylinder includes a conductor cylinder yoke ring and a conductor cylinder front end plate and a conductor cylinder rear end plate disposed at both ends of the conductor cylinder yoke ring. The conductor cylinder is connected to the motor input shaft. Two sets of annular conductor sleeves are fixed on the inner wall of the conductor cylinder. The annular conductor sleeves are divided into a starting area and a rated working area in the axial direction. The area between the two starting areas is an unloaded area. The magnetic permeability and electrical conductivity of the starting area gradually increase from the inside to the outside in the axial direction, and reach the maximum when connected to the rated working area. The magnetic permeability and electrical conductivity of the rated working area are fixed. The drive shaft passes through the rear end of the conductor cylinder, with its front end located inside the conductor cylinder and its rear end connected to the load output shaft. The magnet disk is mounted on the shaft inside the conductor cylinder of the transmission shaft, and can move axially on the transmission shaft and rotate circumferentially synchronously with the transmission shaft. The two magnet disks are symmetrically arranged on both sides of the center of the unloaded area. Permanent magnets are evenly distributed on the outer ring surface of the magnet disk. The magnetic poles of the permanent magnets are radial, and the N poles and S poles are arranged alternately. The axial traction mechanism of the magnet disk is used to drive the two magnet disks to move synchronously closer to or away from the center of the unloaded area. The impedance of the eddy current loop of the conductor cylinder changes with the position of the magnet disk, thereby adjusting the transmission characteristics of the permanent magnet eddy current speed controller.

2. The permanent magnet eddy current speed controller for heavy-load starting under constant torque load as described in claim 1, characterized in that, The axial traction mechanism of the magnet disk includes a crank-slider mechanism and a magnet disk position adjustment mechanism for driving one of the magnet disks to reciprocate axially. The crank-slider mechanism includes a slider groove, a crank, and a slider; Each magnet disk has two slider slots on the side facing the unloaded area. The two slider slots are symmetrically arranged on both sides of the drive shaft, and the direction of the slider slots is perpendicular to the axis of the drive shaft. The two cranks are rotatably mounted on the drive shaft, with the mounting point located at the center of the unloaded area. A slider is fixed to the end of the crank and is slidably mounted in the slider groove.

3. The permanent magnet eddy current speed controller for heavy-load starting under constant torque load as described in claim 2, characterized in that, The magnet disk position adjustment mechanism is a cam adjustment mechanism. The magnet disk near the front end of the conductor cylinder is the first magnet disk, and the magnet disk near the rear end of the conductor cylinder is the second magnet disk. The cam adjustment mechanism includes an isolation bearing, an inner sleeve of the isolation bearing, a cam guide, an outer sleeve of the isolation bearing with a cam groove, a first connecting arm, a rolling bearing, a cam sleeve, and a second connecting arm. The inner sleeve of the isolation bearing is slidably mounted on the transmission shaft, with its front end fixedly connected to the second magnet disk and its rear end fixedly connected to the inner ring of the isolation bearing. The cam sleeve is mounted on the drive shaft via a rolling bearing; The outer sleeve of the isolation bearing is fixedly connected to the outer ring of the isolation bearing and is rotatably sleeved on the outside of the cam sleeve; The rod end of the cam guide is fixed on the cam sleeve, and the bearing end is rolled in the cam groove. The first connecting arm is fixed to the outer sleeve of the isolation bearing, and the second connecting arm is fixed to the cam sleeve.

4. The permanent magnet eddy current speed controller for heavy-load starting under constant torque load as described in claim 3, characterized in that, A first speed measuring gear is fixed to the outside of the conductor cylinder, and a second speed measuring gear is fixed to the outside of the inner sleeve of the isolation bearing; The rotational speed of the first speed measuring gear is detected by the first speed sensor, and the rotational speed of the second speed measuring gear is detected by the second speed sensor.

5. The permanent magnet eddy current speed controller for heavy-load starting under constant torque load as described in claim 4, characterized in that, The conductor cylinder is equipped with a protective cover, and a water outlet pipe is installed on the protective cover; The front end plate of the conductor tube is provided with an outlet that is connected to the outlet pipe, and the rear end plate of the conductor tube is provided with an inlet pipe that passes through the protective cover. The first speed sensor is installed inside the protective cover, and the motor input shaft and the inner sleeve of the isolation bearing both pass through the protective cover.

6. The permanent magnet eddy current speed controller for heavy-load starting under constant torque load as described in claim 5, characterized in that, The drive shaft includes profiled shaft sections and circular shaft sections; The first magnet disk is fitted onto the profiled shaft section via a profiled shaft sleeve, the second magnet disk is integrally formed with the inner sleeve of the isolation bearing, and the rolling bearing is fitted onto the circular shaft section; The crank-slider mechanism also includes a central shoulder and a double-ended stud; The central shoulder is fitted onto the profiled shaft section; The double-ended stud passes through the crank, the central shoulder, and the profiled shaft section, and is located at the center of the unloaded area.

7. The permanent magnet eddy current speed controller for heavy-load starting under constant torque load as described in claim 6, characterized in that, The front end of the drive shaft is provided with a first limiting ring for limiting the axial displacement of the first magnet disk; A second limiting ring is provided at the position in front of the second speed measuring gear on the inner sleeve of the isolation bearing, and a second limiting ring is provided at the position between the inner sleeve of the isolation bearing and the cam sleeve on the drive shaft. The two second limiting rings are used to limit the axial displacement of the inner sleeve of the isolation bearing.

8. The permanent magnet eddy current speed controller for heavy-load starting under constant torque load as described in claim 7, characterized in that, A disc connector is fixed to the rear end of the cam sleeve, and the second connecting arm is fixed to the disc connector; The front end disc of the conductor cylinder is connected to the motor input shaft via an input coupling and a second bolt. The rear end of the drive shaft is connected to the shaft end baffle via the sixth bolt, and the drive shaft is connected to the load output shaft via a flange coupling and a shrink fitting.

9. A control method for a permanent magnet eddy current speed controller for heavy-load start-up under constant torque load as described in any one of claims 1-8, characterized in that: ① Before the motor starts and after the equipment stops, the magnet disk is in the no-load area, and there is no power transmission between the conductor cylinder and the magnet disk, so the motor can start under no-load conditions; ② Load start-up and acceleration: The motor drives the conductor cylinder to rotate, and through the axial traction mechanism of the magnet disk, it drives the two magnet disks to move in opposite directions along the axial direction, synchronously moving away from the center of the unloaded area and entering the start-up area. The annular conductor sleeve in the start-up area moves in the magnetic field generated by the permanent magnet on the magnet disk to cut the magnetic field lines, causing the magnet disk and the conductor cylinder to rotate in the same direction, so that the load follows the movement. The two magnet disks continue to move in opposite directions into the rated working area. The eddy current loop impedance at the corresponding position of the magnet disk decreases, and the magnet disk and load accelerate until the load reaches the rated working condition and the magnet disk stops moving. ③Speed ​​regulation and load balance: The two magnet disks are driven to move towards or away from each other along the axial direction by the axial traction mechanism of the magnet disk. The eddy current circuit impedance of the conductor cylinder changes with the position of the magnet disk, thereby adjusting the transmission characteristics of the permanent magnet eddy current speed controller and realizing speed regulation and load balance of multiple drives. ④ Unloading overload protection: When a sudden overload occurs, the slip difference between the conductor cylinder and the magnet disk suddenly increases, and the operating point quickly drops from the rated point past the maximum torque point to the stall point. The stall torque is small, and because the transmission torque is very small, the motor unloading function is realized. ⑤ Equipment stops operating when power is off: After the load stops, the motor is powered off and stops operating. The axial traction mechanism of the magnet disk drives the two magnet disks to move towards each other along the axial direction and return to the unloaded area.

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