A gearless direct-drive annular permanent magnet synchronous motor for ball mill

Abstract

The present invention discloses a gearless direct-drive annular permanent magnet synchronous motor for a ball mill, comprising a stator, a rotor, a sealing device, a frequency conversion control system and an adjusting shim. The stator is designed to be modular and divided into four equal parts, and all modular stator lobes are spliced in sequence to form a complete stator. The rotor is designed to be modular and divided into three equal parts, and each modular rotor lobe is spliced in sequence to form a complete rotor, which is fixed to the cylinder flange of the ball mill with bolts and is coaxial with the cylinder. A sealing device is provided on each side of the motor. The adjusting shims of the present invention include left, middle and right adjusting shims; each adjusting shim includes a base shim, a wedge shim and an adjusting screw. The air gap of the motor is adjusted by rotating the adjusting screw to ensure that the air gap is within the threshold range. The ball mill of the present invention can improve the transmission efficiency of the system, while reducing maintenance and repair work and improving the reliability of the equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of ball mill driving equipment and relates to a gearless direct-drive annular permanent magnet synchronous motor for a ball mill. Background Art

[0002] With the rapid development of China's economy, energy consumption is increasing, but domestic energy utilization is low. The country is constantly strengthening the implementation of energy conservation and emission reduction.

[0003] my country has a huge number of large-scale mechanical equipment used in mines. Due to the large number of transmission links in mechanical equipment, energy consumption is relatively high. Under the national policy of energy conservation and emission reduction, mechanical equipment is urged to develop in the direction of high efficiency and energy saving. Permanent magnet direct drive system is an inevitable trend.

[0004] In industrial production, ball mills are key equipment for pulverizing materials after crushing. They are widely used in industries such as cement, silicate products, refractories, new building materials, non-ferrous metal beneficiation, and glass and ceramics. Traditional ball mills primarily utilize a side-drive gear transmission, where an asynchronous motor drives a reducer, which in turn drives a pinion, which meshes with a large ring gear mounted on the mill drum to drive the mill. This traditional drive system suffers from numerous drawbacks, including low transmission efficiency, severe mechanical wear, high power consumption, high failure rates, and extensive maintenance.

[0005] Furthermore, during normal ball mill operation, the grinding balls are lifted to a certain height and then dropped, impacting the material at a constant speed and pulverizing it, generating significant impact loads. In actual operation, due to harsh working environments, ball mills are often subjected to alternating impact loads. This can lead to severe wear of the ball mill bearings due to shock vibration, insufficient preload, or lubrication system failure. According to incomplete statistics, ball mill bearing wear can cause up to 0.5mm of subsidence per year. This causes the rotor, which is fixed to the flange of the ball mill drum, to sink, while the stator remains fixed. Consequently, the stator and rotor experience a radial relative offset, causing the air gap to change, exhibiting a distribution trend of "larger at the top, smaller at the bottom, and equal on both sides."

[0006] Furthermore, to ensure the rotor can rotate freely within the stator cavity, a relatively uniform air gap must be maintained between the rotor and stator cores. Although there is no direct electromagnetic connection between the rotor and stator, when the stator winding is energized, electromagnetic connection is established between the rotor and stator, similar to the principle of a transformer, thereby achieving energy conversion between electrical and mechanical energy. The size of the air gap significantly affects the performance and operational reliability of the motor. An excessively large air gap significantly increases the magnetic resistance, which in turn increases excitation losses and the excitation current, reducing the motor's power factor and degrading performance. To reduce the excitation current and improve the power factor, the air gap should be minimized. However, an excessively small air gap increases the air gap harmonic magnetic field, increasing stray losses and noise in the motor, and reducing both maximum torque and starting torque. Therefore, to ensure normal and stable operation of the motor, real-time monitoring of the motor's air gap is crucial. In addition, while monitoring the air gap in real time, the operation of the motor also needs to be controlled according to the changes in the air gap. For example, when the air gap exceeds a certain threshold, an alarm should be issued in time and the motor should be shut down for maintenance to avoid larger accidents. Summary of the Invention

[0007] In order to solve the above problems, the present invention provides the following technical solutions:

[0008] A gearless direct-drive annular permanent magnet synchronous motor for a ball mill is provided. The motor is a split-petal annular motor with a rotating shaft, comprising a stator, a rotor, a sealing device, a frequency conversion control system and an adjusting washer.

[0009] The present invention adopts modular design for the stator, rotor and sealing device.

[0010] The stator 2 is a modular, quartered structure, comprising four stator lobes 210 . Each stator lobe 210 has an angle of 90° between its two ends and the axis of rotation. The four modular stator lobes 210 are sequentially joined to form a complete stator 2 . Adjacent stator lobes 210 are secured together using fastening assemblies 215 .

[0011] Furthermore, each stator lobe 210 includes: a machine base 211, a stator core 212, a slip ring 213, an armature winding 214 and a fastening assembly 215; the armature winding 214 of each stator lobe 210 is divided into U phase, V phase and W phase, and is electrically connected by copper wire wound on each stator tooth of the stator core 212 in accordance with the design requirements of the electrical circuit diagram. Each phase consists of three branches, and the three branches are connected in parallel to the slip ring 213 of each stator lobe 210 by welding. The slip rings 213 between the stator lobe 210 are connected in series by bolting.

[0012] Among them, the rotor 3 is a modular three-part structure, including three rotor lobes 310, that is, a complete rotor 3 is equally divided into three modular rotor lobes 310, and the angle between the two ends of each rotor lobe 310 and the rotation axis is 120°. Each rotor lobe 310 includes a rotor pole 311 and a rotor bracket 312. The three modular rotor lobes 310 are spliced in sequence to form a complete rotor 3. The spliced rotor 3 is fixed to the barrel flange of the ball mill drum with bolts. The rotating axis of the rotor 3 is the same as the rotating axis of the drum barrel. The stator 2 and the ball mill bearing support seat are installed on the foundation. During operation, due to the large impact load of the ball mill, the vibration energy can be quickly transmitted to the ground through the contact between the stator 2 and the bearing support seat and the ground, avoiding energy accumulation causing problems such as increased noise and equipment damage.

[0013] An air gap of 5 to 10 mm is pre-set between the stator 2 and the rotor 3 of the ring motor.

[0014] The sealing device 4 is located on both sides of the ring motor and includes a sealing end cap 410, a labyrinth ring 411, and a felt 412. The labyrinth ring 411 is fixedly mounted on the rotor 3. The sealing end cap 410 is provided with comb teeth 413, a first mounting hole 414, and a second mounting hole 416. A groove 417 is provided on the inner ring of the sealing end cap 410 near the rotor 3, and the felt 412 is fixedly mounted within this groove 417. The sealing surfaces of the sealing end cap 410 and the labyrinth ring 411 are each provided with a plurality of annular sealing comb teeth arranged in sequence. The comb teeth 413 on the sealing end cap 410 and the comb teeth on the labyrinth ring 411 intersect to form a labyrinth seal.

[0015] The felt 412 on the inner surface of the sealing end cover 410 is impregnated with oil before installation, creating a non-prestressed, close-fitting sealing surface. The first mounting hole 414 of the sealing end cover 410 is secured to the stator 2 via bolts 415. The sealing end cover 410 also has a modular structure, with multiple sealing end covers 410 interconnected to form an annular seal that mates with the annular rotor 3.

[0016] Furthermore, the annular seal is equally divided into a plurality of sealing end covers 410, for example, four, five or six. Each sealing end cover is connected via second mounting holes 416 at both ends thereof.

[0017] The variable frequency control system 5 includes a display 513 and an air gap detection device 514. The variable frequency control system 5 utilizes PLC logic control. The air gap detection device 514 is mounted on the stator flap 210 and is used to detect the air gap between the stator 2 and the rotor 3. When the air gap detection device 514 detects that the motor air gap exceeds a preset value, the fault operation indicator lights up and displays on the display 513 of the variable frequency control system 5. This indication can also be displayed on the monitoring screen via a connected component that communicates with remote monitoring equipment, facilitating monitoring and control of the ring motor operation.

[0018] Among them, the adjustment shim 6 is set at the motor foot, including a left adjustment shim, a middle adjustment shim and a right adjustment shim; each adjustment shim 6 includes a base shim 610, a wedge shim 611 and an adjustment screw 612. The inclined plane angle α between the base shim 610 and the wedge shim 611 provides horizontal traction for the supported wedge shim 611 by rotating the adjustment screw 612, so that the wedge shim 611 and the base shim 610 slide obliquely at an angle α, thereby raising or lowering the motor foot, playing the role of lifting and lowering adjustment. The raising or lowering of the motor foot will drive the stator to rise or fall, so the air gap between the stator and the rotor will also be adjusted accordingly, thereby ensuring that the air gap is within the threshold range.

[0019] Furthermore, the frequency conversion control system 5 has three operating modes: low-speed operation, high-speed operation, and maintenance operation. In the low-speed and high-speed operation modes, the ring motor controls the drum to rotate at a low or high constant speed. In the maintenance mode, the ring motor controls the drum to rotate in an inching manner and then brake to a stop. The maintenance mode is used to repair the drum or replace the lining material inside the drum.

[0020] Furthermore, the annular permanent magnet synchronous motor is a large or medium-sized permanent magnet synchronous motor, and the core diameter is generally greater than 1180 mm.

[0021] In summary, due to the adoption of the above technology, the beneficial effects of the present invention are:

[0022] In the present invention, both the stator and the rotor adopt a split modular design, and each module is assembled into a complete stator or rotor. When one or more modules are damaged during use, the machine can be repaired or replaced by simply adjusting it to maintenance mode and shutting it down. If only one module is damaged or fails, it can be repaired by replacing or repairing the module. This can greatly improve the efficiency of troubleshooting and greatly save maintenance costs. During the transportation and installation of the ball mill, the modular design enables the stator and rotor to be modularized, making it easier to transport and install.

[0023] In the present invention, a gap of 5 to 10 mm is pre-set between the stator and the rotor of the ring motor. On the one hand, it is convenient to assemble and ensure that the rotor does not rub against the stator during rotation, causing the barrel to be swept and the motor to be burned; on the other hand, it is beneficial to reduce harmonic stray losses, reduce vibration and noise, and improve the overload capacity of the motor.

[0024] In the present invention, since the reducer, large ring gear and small gear of the existing ball mill motor are eliminated, the intermediate transmission link between the motor and the drum is simplified, and the energy loss, mechanical consumption and lubrication consumption caused by the intermediate transmission link are avoided. The system efficiency can be improved by more than 20% compared with the existing technology.

[0025] In the present invention, the repair and maintenance work of the gear transmission device is avoided, the repair cycle and service life of the equipment are extended, and the reliability of the equipment is improved.

[0026] In the present invention, the ring motor directly drives the rotating drum, and the complicated transmission mechanism is completely eliminated, resulting in a compact structure and less occupied area.

[0027] In the present invention, the ring motor adopts a fully enclosed structure and a double sealing type of "labyrinth seal and felt seal". A series of throttling gaps and expansion cavities are formed between the comb teeth. The sealed medium produces a throttling effect when passing through the gaps in the tortuous labyrinth, preventing dust in the air from entering the interior of the motor; after the felt is soaked in oil, it forms a sealing surface in a non-prestressed state, which greatly improves the sealing performance of the motor, ensures the safe and normal operation of the motor, and makes the protection level of the motor reach IP54. It has strong environmental adaptability and can be used reliably in an ambient temperature of -15°C to 45°C and in a dust and oil mist environment.

[0028] In this invention, the variable frequency control system uses PLC logic control instead of a traditional single-chip microcomputer. This significantly reduces external wiring of the control equipment, shortens the control system design and construction cycle, and also makes maintenance easier. It offers excellent speed regulation performance, smooth and impact-free startup and operation, and can adapt to frequent startups, speed adjustments, and sudden load changes in various operating conditions. It offers simple operation, flexible control, and a high degree of automation.

[0029] The present invention utilizes a structural support structure with adjustable washers at the left, center, and right positions. This design offers a more rational structure, more even force distribution, high strength, high rigidity, and excellent stability. By rotating the adjustment screw, horizontal traction is provided to the supporting wedge washers, achieving a lifting and lowering adjustment with high adjustment precision. Furthermore, the included angle α between the base washers and the wedge washers is designed to achieve a self-locking structure, i.e., tanα ≤ f (where f is the static friction coefficient). This ensures that the equipment does not slide down the slope under the influence of gravity, thereby improving equipment reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the ball mill transmission system structure proposed by the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of the gearless direct-drive annular permanent magnet synchronous motor for the ball mill proposed in the present invention;

[0032] Figure 3 Schematic diagram of the stator lobe of the gearless direct-drive annular permanent magnet synchronous motor of the ball mill proposed in the present invention;

[0033] Figure 4 This is a schematic diagram of the rotor lobe of the gearless direct-drive annular permanent magnet synchronous motor of the ball mill proposed by the present invention;

[0034] Figure 5 This is a schematic diagram of the sealed connection between the sealing end cover and the stator and rotor proposed in the present invention.

[0035] Figure 6 This is a schematic diagram of the sealing end cover structure proposed by the present invention.

[0036] Figure 7 This is a schematic diagram of the adjustment pad structure proposed in the present invention.

[0037] In the figure: 1. annular permanent magnet synchronous motor; 2. stator; 210. stator flap; 211. base; 212. stator core; 213. slip ring; 214. armature winding; 215. fastening assembly; 3. rotor; 310. rotor flap; 311. rotor pole; 312. rotor bracket; 4. sealing device; 410. sealing end cover; 411. labyrinth ring; 412. felt; 413. comb teeth; 414. first mounting hole; 415. bolt; 416. second mounting hole; 417. groove; 5. frequency conversion control system; 510. junction box; 511. three-phase power line; 512. frequency converter; 513. display; 514. air gap value detection device; 6. adjusting shim; 610. base shim; 611. wedge shim; 612. adjusting screw. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings.

[0039] See also Figure 1 and Figure 2 The present invention proposes a gearless direct-drive annular permanent magnet synchronous motor 1 for a ball mill. The motor is a split-type annular motor with a rotating axis, including a stator 2, a rotor 3, a sealing device 4, a frequency conversion control system 5 and an adjusting shim 6.

[0040] The present invention adopts modular design for both the stator and the rotor.

[0041] See also Figure 2 and Figure 3The stator 2 is a modular quarter-divided structure, including four stator lobes 210, each of which has an angle of 90° between its two ends and the axis of rotation. The four modular stator lobes 210 are sequentially spliced together to form a complete stator 2.

[0042] Each stator lobe 210 includes: a machine base 211, a stator core 212, a slip ring 213, an armature winding 214 and a fastening assembly 215; the armature winding 214 of each stator lobe 210 is divided into U phase, V phase and W phase, and is electrically connected by copper wire wound on each stator tooth of the stator core 212 in accordance with the design requirements of the electrical circuit diagram. Each phase consists of three branches, and the three branches are connected in parallel to the slip ring 213 of each stator lobe 210 by welding. The slip rings 213 between the stator lobe 210 are connected in series by bolting.

[0043] See also Figure 2 and 4 The rotor 3 is a modular three-part structure, including three rotor lobes 310, that is, a complete rotor 3 is equally divided into three modular rotor lobes 310, and the angle between the two ends of each rotor lobe 310 and the rotation axis is 120 degrees. Figure 4 The rotor lobe 310 shown is a modular rotor lobe designed in three equal parts. Each rotor lobe 310 includes a rotor pole 311 and a rotor bracket 312. Three modular rotor lobe 310 are sequentially spliced together to form a complete rotor 3. The spliced rotor 3 is fixed to the drum flange of the ball mill with bolts, as shown in FIG. Figure 1 As shown. The rotating axis of the rotor 3 is the same as the rotating axis of the drum body. Figure 1 The stator 2 and the ball mill bearing support are installed on the foundation. During operation, due to the large impact load of the ball mill, the stator 2 and the bearing support are in contact with the ground, which can quickly transfer the vibration energy to the ground, avoiding energy accumulation causing increased noise and equipment damage.

[0044] A 5-10mm air gap is pre-set between the stator 2 and rotor 3 of the ring motor. This air gap facilitates assembly of the stator 2 and rotor 3, ensuring that the rotor 3 does not rub against the stator 2 during rotation, which could cause bore scraping and motor burnout. Furthermore, a properly configured air gap helps minimize harmonic stray losses, reduce vibration and noise, and improve the motor's overload capacity.

[0045] See also Figure 2 、 56. The sealing device 4 is provided on both sides of the ring motor and includes a sealing end cover 410, a labyrinth ring 411, and a felt 412. The labyrinth ring 411 is fixedly mounted on the rotor 3. The sealing end cover 410 is provided with comb teeth 413, a first mounting hole 414, and a second mounting hole 416. A groove 417 is provided on the inner ring of the sealing end cover 410 near the rotor 3, and the felt 412 is fixedly mounted in the groove 417. The sealing surfaces of the sealing end cover 410 and the labyrinth ring 411 are respectively provided with a plurality of annular sealing comb teeth arranged in sequence. The comb teeth 413 on the sealing end cover 410 and the comb teeth on the labyrinth ring 411 are interlaced to form a labyrinth seal. A series of throttling gaps and expansion cavities are formed between the comb teeth, and the sealed medium produces a throttling effect when passing through the gaps of the tortuous maze, thereby preventing dust in the air from entering the interior of the motor, with good dustproof effect and high reliability; the felt 412 provided on the inner ring surface of the sealing end cover 410 is impregnated with oil before installation to form a sealing surface in a non-prestressed state, which has a better sealing effect and enables the motor protection level to reach IP54. The first mounting hole 414 of the sealing end cover 410 is fixedly mounted on the stator 2 by bolts 415. In order to facilitate installation, the sealing end cover 410 is also a modular structure, and multiple sealing end covers 410 are interconnected to form an annular seal, so that it matches the annular rotor 3. An annular seal can be divided into multiple sealing end covers 410, for example, four, five or six. For example Figure 1 As shown, the annular seal includes six equally divided sealing end covers 410. Each sealing end cover is connected through the second mounting holes at both ends thereof, for example, by being fixedly connected by bolts.

[0046] See also Figure 1 and Figure 3 The variable frequency control system 5 includes a display 513 and an air gap detection device 514. The variable frequency control system 5 uses PLC logic control and is connected to the motor via a three-phase power line 511. The air gap detection device 514 is mounted on the stator flap 210; the air gap detection device 514 is used to detect the air gap between the stator 2 and the rotor 3. When the air gap detection device 514 detects that the motor air gap value exceeds a preset value, the fault operation indicator light is illuminated and displayed on the display 513 of the variable frequency control system 5. It can also communicate with remote monitoring equipment through a joint component to achieve display on the monitoring screen, facilitating the monitoring and control of the ring motor operation.

[0047] The present invention uses a non-uniform threshold value to represent the preset value of the air gap. After the stator and the rotor are assembled, since the stator and the rotor are both circular, the air gap between the stator and the rotor is an annular air gap. Multiple locations are selected within the annular air gap, and the air gap value is measured at each location. The multiple air gap values are averaged to obtain the average air gap value. The calculation of the unevenness threshold is defined as: the ratio of the difference between the measured value and the average value to the average value, that is, (measured value - average value) / average value. In the present invention, the unevenness threshold is controlled within ±10%. That is, when the unevenness threshold is within ±10%, the air gap value between the rotor and stator is considered to be within a reasonable range, and the ball mill motor is operating normally. If the unevenness threshold exceeds ±10%, the air gap value between the rotor and stator is considered to be outside the reasonable range, resulting in radial relative offset between the rotor and stator. The uneven air gap will rapidly increase. At the least, the vibration amplitude will increase, the starting shock will be large, low-frequency electromagnetic sound will be generated, and transmission efficiency will be reduced. At worst, the rotor will scratch the stator during rotation, causing scavenging and even serious production accidents. Therefore, when the unevenness threshold exceeds the reasonable range, an alarm will be triggered or the machine will be shut down for maintenance.

[0048] When the monitoring personnel deems it necessary to stop the machine for maintenance, they press the "emergency stop" button, the frequency conversion control system 5 loses power, and the annular permanent magnet synchronous motor 1 stops freely; by raising or lowering the feet of the annular permanent magnet synchronous motor 1, the air gap is adjusted to be within the threshold range, and the fault operation indicator light goes out.

[0049] The variable frequency control system 5 has three operating modes: low-speed operation, high-speed operation, and maintenance operation. In these modes, the ring motor controls the drum to rotate at a low or high constant speed. In maintenance mode, the ring motor controls the drum to rotate in steps before braking to a stop. Maintenance mode is used to repair the drum or replace the lining material inside the drum.

Claims

1. A gearless direct-drive annular permanent magnet synchronous motor for a ball mill, characterized by: The annular permanent magnet synchronous motor (1) is a split-type annular motor with a rotating axis, comprising a stator (2), a rotor (3), a sealing device (4), a frequency conversion control system (5) and an adjusting washer (6); The stator (2) is a modular quarter-divided structure, comprising four stator lobes (210), wherein the angle between the two ends of each stator lobes (210) and the rotation axis is 90°; the four modular stator lobes (210) are sequentially spliced to form a complete stator (2), and adjacent stator lobes (210) are mounted and fixed by fastening components (215); The rotor (3) is a modular three-part structure, comprising three rotor lobes (310), wherein the angle between the two ends of each rotor lobe (310) and the rotation axis is 120°; the three modular rotor lobes (310) are sequentially spliced together to form a complete rotor (3); The sealing device (4) is arranged on both sides of the annular motor and comprises a plurality of sealing end covers (410); the plurality of sealing end covers (410) are interconnected to form an annular seal; The variable frequency control system (5) includes a display (513) and an air gap value detection device (514); The adjusting washer (6) comprises a base washer (610), a wedge-shaped washer (611) and an adjusting screw (612); The sealing device (4) comprises a sealing end cover (410), a labyrinth ring (411) and a felt (412); the labyrinth ring (411) is fixedly mounted on the rotor (3); The sealing end cover (410) is provided with comb teeth (413), a first mounting hole (414), and a second mounting hole (416); the sealing end cover (410) is also provided with a groove (417) near the inner ring of the rotor (3); The sealing surfaces of the sealing end cover (410) and the labyrinth ring (411) are respectively provided with a plurality of annular sealing comb teeth arranged in sequence, and the comb teeth (413) on the sealing end cover (410) and the comb teeth on the labyrinth ring (411) are interlaced with each other to form a labyrinth seal; The sealing end cover (410) is fixedly mounted on the stator (2) via bolts (415) on the first mounting hole (414); the sealing end cover (410) is a modular structure, and a plurality of sealing end covers (410) are interconnected to form an annular seal, so as to match the annular rotor (3).

2. The gearless direct-drive annular permanent magnet synchronous motor for a ball mill according to claim 1, characterized in that: in, The stator flap (210) comprises a base (211), a stator core (212), a collector ring (213), an armature winding (214), and a fastening assembly (215); the armature winding (214) of each stator flap (210) is divided into a U phase, a V phase, and a W phase, and is electrically connected by a copper wire wound on each stator tooth of the stator core (212) in accordance with the design requirements of the electrical circuit diagram; each phase consists of three branches, and the three branches are connected in parallel to the collector ring (213) of each stator flap (210) by welding, and the collector rings (213) between the stator flaps (210) are connected in series by bolt fastening.

3. The gearless direct-drive annular permanent magnet synchronous motor for a ball mill according to claim 1, characterized in that: in, The rotor lobes (310) include rotor poles (311) and a rotor bracket (312); the rotor (3) formed by splicing three modular rotor lobes (310) is fixed to the barrel flange of the ball mill drum by bolts; the rotation axis of the rotor (3) and the rotation axis of the drum barrel are the same rotation axis.

4. The gearless direct-drive annular permanent magnet synchronous motor for a ball mill according to claim 3, characterized in that: The felt (412) is fixedly installed in the groove (417), and the felt (412) is impregnated with oil before installation.

5. The gearless direct-drive annular permanent magnet synchronous motor for a ball mill according to claim 1, characterized in that: The variable frequency control system (5) includes a display (513) and an air gap value detection device (514); the variable frequency control system (5) adopts PLC logic control; the air gap value detection device (514) is arranged on the stator flap (210); The air gap value detection device (514) is used to detect the air gap between the stator (2) and the rotor (3); when the air gap value detection device (514) detects that the motor air gap value exceeds a preset value, the fault operation indicator light is on, and is displayed on the display (513) of the frequency conversion control system (5) or communicates with the remote monitoring device through the combined component to achieve display on the monitoring display screen.

6. The gearless direct-drive annular permanent magnet synchronous motor for a ball mill according to claim 1, characterized in that: The adjusting washer (6) is arranged at the motor foot, and comprises a base washer (610), a wedge-shaped washer (611) and an adjusting screw (612); the inclined planes of the base washer (610) and the wedge-shaped washer (611) are angled at an angle α, and by rotating the adjusting screw (612), a horizontal traction force is provided for the supported wedge-shaped washer (611), so that an oblique sliding at an angle α occurs between the wedge-shaped washer (611) and the base washer (610), thereby raising or lowering the motor foot, and ensuring that the air gap is within a threshold range.

7. The gearless direct-drive annular permanent magnet synchronous motor (1) for a ball mill according to claim 1, characterized in that: The frequency conversion control system (5) has three working modes: low-speed operation, high-speed operation and maintenance. In the low-speed operation and high-speed operation modes, the annular motor controls the roller to rotate at a low speed or a high speed at a constant speed. In the maintenance mode, the annular motor controls the roller to rotate in a point-to-point manner and then brake to stop. The maintenance mode is used to repair the roller or replace the lining material in the roller.

8. The gearless direct-drive annular permanent magnet synchronous motor (1) for a ball mill according to claim 1, characterized in that: An air gap of 5 to 10 mm is pre-set between the stator (2) and the rotor (3) of the ring-shaped motor.

9. The gearless direct-drive annular permanent magnet synchronous motor (1) for a ball mill according to claim 1, characterized in that: The sealing end covers (410) of the sealing device (4) are equally divided into four, five or six; each sealing end cover is connected via the second mounting holes (416) at both ends thereof.

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