A permanent magnet transmission device with magnets arranged in an eight-shaped pattern and a method for calculating torque thereof

Abstract

The present invention discloses a permanent magnet transmission device with magnets arranged in an eight-shaped pattern and a method for calculating the torque thereof. Structurally, a tile-shaped magnet is embedded in the inner wall of the power drum hub, and an eight-shaped permanent magnet is embedded inside the load core hub, so that torque transmission is achieved through magnetic attraction. A high-elasticity annular rubber airbag ring is installed in the power side sealing end cover, and roller bearings are installed at the journals of the power keyway shaft and the load keyway shaft to achieve axial and radial vibration isolation. The device reduces eddy current distribution and improves torque transmission efficiency. Load changes can be adapted by adjusting the slip angle of the inner and outer rotors. The vibration isolation device enhances the system's ability to cope with sudden working conditions. The torque calculation method is based on theories such as the equivalent magnetic charge method. With two tile-shaped magnets and the sandwiched eight-shaped permanent magnets as research objects, a double Cartesian three-dimensional coordinate system is established to solve the magnetic charge surface density and magnetic attraction torque, thereby obtaining the total output torque of the system. This method avoids the complicated process of traditional finite element analysis, can quickly and accurately solve torque, and has good universality.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical transmission, and relates to a permanent magnet transmission device with magnets arranged in an eight-shaped pattern and a torque calculation method thereof. Background Art

[0002] In industrial manufacturing, high-precision transmissions are widely used in industries such as vehicle transportation, shipbuilding, and metallurgy. They are primarily used to transmit torque between power sources and loads, ensuring stable operation of mechanical systems. Traditional mechanical transmissions have numerous shortcomings, including significant friction losses. Micro-roughness on the contact surfaces during gear contact and chain-sprocket engagement can lead to energy loss as heat and mechanical wear. Furthermore, when the meshing frequency of internal mechanisms coincides with the system's natural frequency, resonance can occur. Overload tolerance is poor, and gear materials (such as hardened steel) are hard but have low toughness, making them prone to brittle fracture under overload. Furthermore, most mechanical transmissions utilize rigid connections, lacking overload protection through slip. Emerging permanent magnet transmissions, through contactless energy transfer and flexible torque transmission, effectively address the challenges of high friction losses, frequent maintenance, and poor environmental adaptability inherent in traditional mechanical transmissions. These devices are crucial for ensuring the efficient operation of mechanical equipment. However, permanent magnet transmissions generally face challenges in structural design and torque calculation. Structurally, the magnetic circuit design is complex, making it difficult to accurately calculate and optimize the magnetic flux distribution, resulting in low magnetic field utilization and negatively impacting transmission efficiency. Secondly, the arrangement and fixing of permanent magnets face challenges. It is necessary to ensure sufficient magnetic attraction to achieve efficient transmission, while also considering the stability of the permanent magnets under different working conditions to prevent vibration, impact, etc. from causing the permanent magnets to loosen or shift, thereby reducing the performance of the transmission device. Computationally, solving the torque of permanent magnet transmission devices often relies on finite element simulation technology. It is necessary to couple a large number of environmental parameters when building the simulation model and perform detailed meshing in key areas, making the calculation process very lengthy and complex, seriously reducing the calculation efficiency. Therefore, proposing a permanent magnet transmission device with a compact structure, stable performance, strong vibration isolation, and strong torque transmission capability, and its torque calculation method, is of vital importance to promoting the theoretical research of permanent magnet transmission devices and realizing the diversification of transmission devices.

[0003] Regarding the structural design of permanent magnet transmission devices, J.A. Faulkner proposed in his patent "Lubricated Gear Coupling" (CN106715939B) to utilize the axial, radial, and angular relative motion between a first hub and a second hub arranged in a sleeve to achieve the purpose of transmitting torque from the input shaft to the output shaft. However, due to the limitations of gear strength and other mechanical characteristics, this device has shortcomings such as weak speed change capability and low torque transmission. In addition, lubricant needs to be added regularly to reduce friction loss between the hubs, which cannot meet the requirements of long-term system operation.

[0004] In his paper "Analysis of Eddy Current and Transmission Characteristics of a Double-Layer Solid Asynchronous Magnetic Coupling," Yang Chaojun conducted electromagnetic field finite element simulation analysis to determine field quantities such as eddy current density, magnetic flux density, and torque over different time periods for a specific finite element model of a double-layer solid asynchronous magnetic coupling. However, this method requires detailed meshing of the copper layer and air gap region, significantly reducing computational efficiency. Furthermore, this method cannot handle torque calculations for other permanent magnet transmission devices, limiting its applicability and flexibility.

[0005] Therefore, it is very necessary to propose a permanent magnet transmission device with low friction loss, strong torque transmission capability, and long-term stable operation, as well as a high-precision and universal calculation method for the permanent magnet transmission device. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a permanent magnet transmission device with a figure-eight arrangement of magnets and a torque calculation method. By embedding a tile-shaped magnet in the inner wall of the power drum hub and a figure-eight permanent magnet in the inner wall of the load core hub, the non-contact magnetic force generated between the two facilitates torque transmission between the power source and the load side, thereby reducing contact friction in the system and achieving improved efficiency, reduced noise, and increased service life.

[0007] The technical solution of the present invention:

[0008] A permanent magnet transmission device with magnets arranged in an "eight" pattern is described. First, a tile-shaped magnet is embedded in a fixed groove on the inner wall of the power drum hub. Both are covered with a power drum dustproof shell. An "eight" groove is opened at an appropriate position inside the load core hub, into which the "eight" permanent magnet is embedded. The magnet is then covered with a load core sealing shell to achieve the purpose of limiting and sealing the permanent magnet. Second, a high-elastic annular rubber airbag ring is locked on the inner surface of the power side sealing end cover using fastening bolts. Roller bearings are installed on the journals of the power keyway shaft and the load keyway shaft to complete the assembly of the axial and radial vibration isolation mechanisms. Finally, the power keyway shaft and the load keyway shaft are fixed on both sides by specific bolts. This achieves the purpose of achieving the purpose of system torque transmission by using the power source to drive the power keyway shaft to rotate under the action of the magnetic attraction between the tile-shaped magnet and the "eight" permanent magnet. When the speed changes suddenly, the misalignment angle between the tile-shaped magnetic steel and the figure-eight permanent magnet changes accordingly, thereby generating different degrees of torque, thereby realizing self-stabilizing adjustment of the system; the present invention has a compact structure, convenient operation, no mechanical friction loss, good silent performance, and good dynamic torque adaptability. It is suitable for scenarios with flexible load changes and has high engineering application promotion value in the field of high-precision transmission.

[0009] A permanent magnet transmission device with magnets arranged in an "eight" pattern is characterized by easy assembly, stable structure, and excellent vibration isolation performance. The device comprises a load keyway shaft, a load-side vibration isolation roller bearing, a tile-shaped magnetic steel, a power drum hub, a power drum dust cover, a power-side sealing end cover, a power-side vibration isolation roller bearing, a power keyway shaft, a high-elasticity annular vibration isolation rubber airbag ring, a core limiting sealing cover, a load core hub, an "eight"-shaped permanent magnet, and a load core sealing shell.

[0010] The load core hub is provided with an eight-shaped groove and an eight-shaped permanent magnet is embedded in it. The load core sealing shell covers the outer surface of the load core hub, and the two are fixed by bolts; the core limit sealing cover is fixed to the power side of the load core sealing shell by bolts; the inner wall of the power drum hub is grooved and embedded with a tile-shaped magnetic steel, and the power drum dust shell is sleeved on the surface of the power drum hub; the power side sealing end cover is fixed to the outside of the power drum dust shell, and the power side sealing end cover, the power drum dust shell and the power drum hub are fixedly connected by bolts; the high-elastic annular vibration isolation rubber airbag ring is locked in the cavity inside the power side sealing end cover by bolts and nuts; the power keyway shaft is fixed to the power side sealing end cover by bolts, and the load keyway shaft is movably connected to the load core sealing shell; the load side vibration isolation roller bearing and the power side vibration isolation roller bearing are respectively installed on the shaft necks of the load keyway shaft and the power keyway shaft.

[0011] All the bolt connections mentioned above are padded with highly elastic O-shaped sealing washers.

[0012] A method for calculating the torque of a permanent magnet transmission device with a figure-eight arrangement of magnets is disclosed. Based on the layout characteristics of the permanent magnets of the device, two tile-shaped magnets and the figure-eight permanent magnet sandwiched between them are used as research objects. A dual Cartesian three-dimensional coordinate system is established. Based on the equivalent magnetic charge method, linear space and linear transformation theory, multiple integrals are used to solve the magnetic charge surface density of the permanent magnet material surface. A misalignment angle is given to the two Cartesian coordinate systems, and the magnetic attraction torque between the two tile-shaped magnets and the figure-eight permanent magnet sandwiched between them is solved. The total output torque of the system under a given misalignment angle is calculated based on the misalignment angle, thereby obtaining the system output torque under a given misalignment angle. This method realizes the rapid calculation of the torque and misalignment angle required for different loads, achieves the purpose of quickly adapting to changing scenarios, and provides important theoretical calculation support for the structural design and performance optimization of permanent magnet transmission devices.

[0013] The specific steps are as follows:

[0014] The first step is to determine the key parameters of the permanent magnet transmission device with magnets arranged in an eight-shaped pattern;

[0015] Key parameters include residual magnetization of tile magnets , residual magnetization intensity of figure eight permanent magnet , vacuum permeability , the curvature radius of the tile-shaped magnetic steel , Curvature radius of the splayed groove , the equivalent magnetic charge density of the lower surface of the tile-shaped magnet along the coordinate axis , the equivalent magnetic charge surface density of the outer surface of the figure-eight permanent magnet , the axial length of the power drum hub , axial length of the load core hub and the coordinate transformation matrix ;

[0016] The second step is to calculate the magnetic charge surface density of the tile-shaped magnetic steel and the figure-eight permanent magnet;

[0017] Taking the geometric center of the load core hub as the origin, make a cross section Ω of the load core hub through the origin, and randomly select two adjacent tile-shaped magnetic steels, which are defined as the Pth tile-shaped magnetic steel and the Qth tile-shaped magnetic steel; establish a Cartesian coordinate system I with the directions of the lines connecting the origin and the midpoints of the arcs projected on the cross section Ω by the Pth tile-shaped magnetic steel and the Qth tile-shaped magnetic steel as the X-axis and Y-axis directions; establish a Cartesian coordinate system II with the center of curvature K of the splayed slot sandwiched between the Pth tile-shaped magnetic steel and the Qth tile-shaped magnetic steel as the origin, the direction of the line connecting the origin and the midpoint of the arc projected on the cross section Ω by the splayed slot as the Y-axis direction, and any direction perpendicular to the Y-axis as the X-axis direction; the Z-axis directions of both Cartesian coordinate systems I and II are the directions of the central axis of the load core hub;

[0018] After that, solve the basis transformation matrix from Cartesian coordinate system II to Cartesian coordinate system I:

[0019] (1)

[0020] It is stipulated that the Y-axis direction of the P-th tile-shaped magnet and the Q-th tile-shaped magnet in the Cartesian coordinate system I is the magnetization direction; the eight-shaped permanent magnet sandwiched by the P-th tile-shaped magnet and the Q-th tile-shaped magnet is the U-th eight-shaped permanent magnet and the V-th eight-shaped permanent magnet, and the Y-axis direction of the U-th eight-shaped permanent magnet and the V-th eight-shaped permanent magnet in the Cartesian coordinate system II is the magnetization direction;

[0021] The inner surface magnetic charge density of the Pth tile-shaped magnetic steel and the Qth tile-shaped magnetic steel is:

[0022] (2)

[0023] (3)

[0024] The outer surface magnetic charge density of the Uth figure-eight permanent magnet and the Vth figure-eight permanent magnet:

[0025] (4)

[0026] (5)

[0027] Where L is the distance between the origin of Cartesian coordinate system I and the origin of Cartesian coordinate system II, is the rotation angle of Cartesian coordinate system II relative to Cartesian coordinate system I around the central axis of the load core hub, is the angle between the line connecting the origin of Cartesian coordinate system I and the origin of Cartesian coordinate system II and the X-axis of Cartesian coordinate system I, is the unit vector in the XY plane in Cartesian coordinate system I, is the unit vector in the Y-axis direction in Cartesian coordinate system I, is the azimuth of the Cartesian coordinate system I, is the unit vector in the XY plane in Cartesian coordinate system II, is the unit vector in the Y-axis direction in Cartesian coordinate system II; is the azimuth of Cartesian coordinate system II;

[0028] Step 3: Calculate the magnetic attraction torque of the figure-eight permanent magnet sandwiched between the Pth tile-shaped magnetic steel and the Qth tile-shaped magnetic steel;

[0029] From the first step, we can know the basis transformation matrix from Cartesian coordinate system II to Cartesian coordinate system I ,

[0030] but (6)

[0031] in, and are the homogeneous coordinates of any point in Cartesian coordinate system I and Cartesian coordinate system II;

[0032] Calculate the magnetic attraction between the Uth figure-eight permanent magnet and the Vth figure-eight permanent magnet sandwiched by the Pth tile-shaped magnet and the Qth tile-shaped magnet:

[0033] (7)

[0034] in:

[0035] (8)

[0036] in, is the relative position vector of any two magnetic charges on the surface of the tile-shaped magnet and the figure-eight permanent magnet, is the vacuum permeability, are the starting angle and ending angle of the Pth tile-shaped magnet in Cartesian coordinate system I, are the starting angle and ending angle of the Qth tile-shaped magnet in Cartesian coordinate system I, are the starting angle and ending angle of the Uth figure eight permanent magnet in Cartesian coordinate system II, are the starting angle and ending angle of the Vth figure-eight permanent magnet in Cartesian coordinate system II;

[0037] After that, calculate the moment arm of the magnetic attraction:

[0038] make Magnetic force arm The four-dimensional homogeneous vector ,in =1;

[0039] (9)

[0040] Thus, (10)

[0041] Further obtain the magnetic attraction torque:

[0042] (11)

[0043] Furthermore, the total torque transmitted by a permanent magnet transmission device with magnets arranged in an eight-shaped pattern under a given inner and outer rotor slip angle is obtained:

[0044] (12)

[0045] in, is the number of eight-shaped permanent magnet slots, is the absolute value of the magnetic attraction torque;

[0046] At this point, the torque calculation of a permanent magnet transmission device with magnets arranged in an eight-shaped pattern is completed.

[0047] The beneficial effect of the present invention is that a permanent magnet transmission device with magnets arranged in a figure eight is proposed. The internal slots of the load core hub of the device reduce the eddy current distribution to a certain extent, and the torque transmission efficiency is significantly improved. At the same time, the system torque can be dynamically adapted by adjusting the slip angle of the inner and outer rotors, which is suitable for load-variable scenarios. Under working conditions, the high-elasticity annular vibration isolation rubber airbag ring on the inner wall of the power side sealing end cover plays an axial vibration isolation role, and the roller bearings on both sides enhance the support and stability of the system, greatly improving the system's ability to cope with sudden working conditions. At the same time, the torque calculation method of the permanent magnet transmission device with magnets arranged in a figure eight proposed by the present invention avoids the complicated calculation process of traditional finite element analysis, realizes the rapid and accurate solution of the transmitted torque, has good universality, and can be used for efficient analysis and solution of torque of various permanent magnet transmission devices. It not only has a solid theoretical basis, but also shows a high degree of universality and practicality in engineering practice, providing a precise and efficient algorithm tool for engineering design and optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1This is a flow chart of a method for calculating torque of a permanent magnet transmission device with magnets arranged in a figure eight pattern;

[0049] Figure 2 It is a basic model of a permanent magnet transmission device with magnets arranged in an eight-shaped pattern;

[0050] Figure 3 It is a radial cross-sectional view and coordinate system of a permanent magnetic transmission device with magnets arranged in an eight-shaped pattern;

[0051] In the figure: 1 load keyway shaft; 2 load side vibration isolation roller bearing; 3 load keyway shaft fastening bolt; 4 core sealing shell fastening bolt; 5 high elastic O-ring sealing gasket; 6 tile-shaped magnet; 7 power drum hub; 8 power drum dust cover; 9 power side sealing end cover; 10 sealing end cover limiting long bolt; 11 power keyway shaft fastening bolt; 12 power side vibration isolation roller bearing; 13 power keyway shaft; 14 core sealing cover plate limiting bolt; 15 high elastic annular vibration isolation rubber airbag ring; 16 high elastic annular vibration isolation rubber airbag ring fastening bolt; 17 high elastic annular vibration isolation rubber airbag ring fastening nut; 18 core limiting sealing cover; 19 load core hub; 20 figure eight permanent magnet; 21 load core sealing shell; N is the north pole of the tile-shaped magnet; S is the south pole of the figure eight permanent magnet; is the Cartesian coordinate system I; is the Cartesian coordinate system II; K is the eight-shaped slot; P is the P-th tile-shaped magnet; Q is the Q-th tile-shaped magnet; U is the U-th eight-shaped permanent magnet; V is the V-th eight-shaped permanent magnet; is the vector angle corresponding to the Pth and Qth tile-shaped magnets in Cartesian coordinate system I; is the vector angle corresponding to the Uth and Vth figure-eight permanent magnets in Cartesian coordinate system II; It is the rotation angle of Cartesian coordinate system II relative to Cartesian coordinate system I around the central axis of the load core hub. DETAILED DESCRIPTION

[0052] The embodiments of the present invention are further described below in conjunction with the accompanying drawings and technical solutions.

[0053] This example uses a permanent magnet transmission device with four slots in a loaded rotor hub and magnets arranged in a figure-eight pattern. The torque transmitted by the system is calculated at a given slip angle.

[0054] Among them, the load keyway shaft 1 has a journal diameter of 40mm, the load side vibration isolation roller bearing 2 adopts a cylindrical roller bearing with an inner diameter of 40mm, the load keyway shaft fastening bolt 3 adopts a hexagon socket bolt, the core sealing shell fastening bolt 4 adopts a hexagon socket bolt, the high elastic O-ring sealing gasket 5 adopts a stainless steel grade A chamfered flat washer, and the inner surface curvature radius of the tile-shaped magnetic steel 6 is 74mm, central angle 60°, axial length 60mm, The power drum hub 7 has an inner diameter of 149mm, an outer diameter of 180mm, and an axial length of 60mm. The power drum dust cover 8 has a thickness of 2mm. The power side sealing end cover 9 has an inner diameter of 144mm, an outer diameter of 180mm, and an axial length of 15mm. The sealing end cover limit bolt 10 uses an inner hexagonal bolt, the power keyway shaft fastening bolt 11 uses an inner hexagonal bolt, the power side vibration isolation roller bearing 12 uses a cylindrical roller bearing with an inner diameter of 40mm, and the power keyway shaft 13 journal The diameter is 40mm, the limiting bolts 14 of the rotating core sealing cover are hexagonal bolts, the inner diameter of the high-elastic annular vibration-isolating rubber airbag ring is 70mm, the thickness is 5mm, the fastening bolts 16 of the high-elastic annular vibration-isolating rubber airbag ring are hexagonal bolts, the fastening nuts 17 of the high-elastic annular vibration-isolating rubber airbag ring are nuts, the rotating core limiting sealing cover 18 is 2mm thick and has a diameter of 120mm, the load rotating core hub 19 has a diameter of 130mm and an axial length of 60mm, and the curvature radius of the eight-shaped permanent magnet 20 is 120mm. 60mm, central angle 30° axial length 60mm, The thickness of the load core sealing shell 21 is 2mm, the distance L between the origin of coordinate system II and I is 100mm, and the relative angle =150°, .

[0055] The installation steps of the permanent magnet rotating device with the magnets arranged in an eight-shaped pattern are as follows:

[0056] First, an S-shaped groove is opened inside the load core hub 19 and the S-shaped permanent magnet 20 is embedded therein. The core sealing shell 21 covers the outer surface of the load core hub 19 to complete the assembly and fixation of the S-shaped permanent magnet 20.

[0057] Secondly, the load keyway shaft 1 is fixed to the load core hub 19 by the fastening bolts 3, the core sealing shell fastening bolts 4 are opened and fixed to the load core sealing shell 21 and the load core hub 19, and the core limiting sealing cover 18 is fixed to the power end of the load core sealing shell 21 by the core sealing cover plate limiting bolts 14 to complete the load side assembly and sealing.

[0058] Again, the inner wall of the power drum hub 7 is grooved to embed the tile-shaped magnetic steel 6, and the power drum dust cover 8 is put on the surface of the power drum hub 7 to realize the assembly and fixation of the tile-shaped magnetic steel 6. The sealing end cover limiting long bolt 10 penetrates the power side sealing end cover 9, the power drum dust cover 8, and the power drum hub 7 and locks the three. The power keyway shaft 13 is fixed to the power side sealing end cover 9 by the power keyway shaft fastening bolt 11 to realize the power side assembly and sealing.

[0059] Finally, the high-elastic annular vibration isolation rubber airbag ring 15 is locked in the inner cavity of the power side sealing end cover 9 through the high-elastic annular vibration isolation rubber airbag ring fastening bolts 16 and the high-elastic annular vibration isolation rubber airbag ring fastening nuts 17. The load side vibration isolation roller bearing 2 and the power side vibration isolation roller bearing 12 are respectively installed on the load keyway shaft 1 and the power keyway shaft 13 shaft necks. The above-mentioned bolts are all padded with high-elastic O-ring sealing washers 5 of stainless steel grade A chamfered flat washers to complete the assembly of the system vibration isolation device and sealing fasteners.

[0060] At this point, the permanent magnet transmission device with magnets arranged in an eight-shaped pattern has been installed.

[0061] A method for calculating the torque of a permanent magnet transmission device with an eight-shaped magnet arrangement is as follows: Figure 1 The specific steps are as follows:

[0062] The first step is to solve the magnetic charge surface density of tile-shaped magnets and figure-eight permanent magnets;

[0063] First, establish Cartesian coordinate system I with the intersection of the inner and outer rotor central axes and the cross section as the origin, and Cartesian coordinate system II with the center of curvature of the splayed slot as the origin. Next, select the y-axis direction of the coordinate system where the tile-shaped magnetic steel and the splayed permanent magnet are located as the magnetization direction.

[0064] Calculated by formula (2), formula (3), formula (4), and formula (5) 、 .

[0065] The second step is to calculate the magnetic attraction torque of the eight-shaped permanent magnet clamped by the two tile-shaped magnets. From formula (1), we can know the transformation matrix , the magnetic attraction torque of the eight-shaped permanent magnet clamped by the two tile-shaped magnets is obtained by equations (6), (7), (8), (9), (10), and (11): ;

[0066] The third step is to calculate the total magnetic attraction torque of the system, and we can get it from formula (11): At this point, the calculation of the system torque of the permanent magnet transmission device with an eight-shaped magnet arrangement under a given slip angle is completed.

[0067] This new permanent magnet transmission effectively reduces eddy current losses through slotted internal hubs within the load-bearing rotor. Adjusting the slip angle between the inner and outer rotors allows for torque adjustability, flexibly adapting to varying loads. The vibration isolation structure significantly reduces the impact of unexpected operating conditions on the system, and the contactless magnetic transmission significantly reduces operating wear and noise, further enhancing system stability and engineering reliability.

[0068] Compared to traditional finite element analysis, this calculation method can quickly and accurately determine the torque of a system at a given slip angle, avoiding the complex calculation process of traditional finite element analysis and effectively reducing time costs. This method is also highly universal and applicable to various other common permanent magnet transmission devices, providing reliable theoretical support for torque calculations in various permanent magnet transmission devices and demonstrating its strong engineering applicability.

Claims

1. A method for calculating the torque of a permanent magnet transmission device with magnets arranged in an eight-shaped pattern, wherein the permanent magnet transmission device comprises a load keyway shaft (1), a load-side vibration isolation roller bearing (2), a tile-shaped magnetic steel (6), a power drum hub (7), a power drum dustproof shell (8), a power side sealing end cover (9), a power side vibration isolation roller bearing (12), a power keyway shaft (13), a high-elasticity annular vibration isolation rubber airbag ring (15), a core limiting sealing cover (18), a load core hub (19), an eight-shaped permanent magnet (20) and a load core sealing shell (21); The load core hub (19) has an eight-shaped groove inside and an eight-shaped permanent magnet (20) is embedded therein. The load core sealing shell (21) covers the outer surface of the load core hub (19), and the two are fixed. The core limiting sealing cover (18) is fixed to the power side of the load core sealing shell (21). The inner wall of the power drum hub (7) is grooved and a tile-shaped magnetic steel (6) is embedded therein. The power drum dustproof shell (8) is sleeved on the surface of the power drum hub (7). The power side sealing end cover (9) is fixed to the outer side of the power drum dustproof shell (8). The sealing end cover (9), the power drum dust cover (8) and the power drum hub (7) are fixedly connected; the high-elasticity annular vibration-isolating rubber airbag ring (15) is locked in the cavity inside the power side sealing end cover (9); the power keyway shaft (13) is fixed on the power side sealing end cover (9), and the load keyway shaft (1) is movably connected to the load core sealing shell (21); the load side vibration-isolating roller bearing (2) and the power side vibration-isolating roller bearing (12) are respectively installed on the journals of the load keyway shaft (1) and the power keyway shaft (13); It is characterized in that Here are the steps: The first step is to determine the key parameters of the permanent magnet transmission device with magnets arranged in an eight-shaped pattern; Key parameters include the residual magnetization strength of the tile magnet , residual magnetization intensity of figure eight permanent magnet , vacuum permeability , the curvature radius of the tile-shaped magnetic steel 、Slot curvature radius , the equivalent magnetic charge density of the lower surface of the tile-shaped magnet along the coordinate axis , the equivalent magnetic charge surface density of the outer surface of the figure-eight permanent magnet , the axial length of the power drum hub , axial length of the load core hub and the coordinate transformation matrix ; The second step is to calculate the magnetic charge surface density of the tile-shaped magnetic steel and the figure-eight permanent magnet; Taking the geometric center of the load core hub (19) as the origin, making a cross section Ω of the load core hub (19) through the origin, randomly selecting two adjacent tile-shaped magnetic steels (6), which are defined as the Pth tile-shaped magnetic steel (6) and the Qth tile-shaped magnetic steel (6); establishing a Cartesian coordinate system I with the directions of the lines connecting the origin and the midpoints of the arcs projected on the cross section Ω by the Pth tile-shaped magnetic steel (6) and the Qth tile-shaped magnetic steel (6) as the X-axis and Y-axis directions; establishing a Cartesian coordinate system II with the center of curvature K of the splayed groove sandwiched between the Pth tile-shaped magnetic steel (6) and the Qth tile-shaped magnetic steel (6) as the origin, the direction of the line connecting the origin and the midpoints of the arcs projected on the cross section Ω by the splayed groove as the Y-axis direction, and any direction perpendicular to the Y-axis as the X-axis direction; establishing a Cartesian coordinate system II with the Z-axis direction of both the Cartesian coordinate system I and the Cartesian coordinate system II as the central axis direction of the load core hub (19); After that, solve the basis transformation matrix from Cartesian coordinate system II to Cartesian coordinate system I: （1）， It is stipulated that the Y-axis direction of the P-th tile-shaped magnetic steel (6) and the Q-th tile-shaped magnetic steel (6) in the Cartesian coordinate system I is the magnetization direction; the eight-shaped permanent magnets sandwiched by the P-th tile-shaped magnetic steel (6) and the Q-th tile-shaped magnetic steel (6) are the U-th eight-shaped permanent magnet and the V-th eight-shaped permanent magnet, and the Y-axis direction of the U-th eight-shaped permanent magnet and the V-th eight-shaped permanent magnet in the Cartesian coordinate system II is the magnetization direction; The inner surface magnetic charge density of the Pth tile-shaped magnetic steel (6) and the Qth tile-shaped magnetic steel (6): （2）， （3）， The outer surface magnetic charge density of the Uth figure-eight permanent magnet and the Vth figure-eight permanent magnet: （4）， （5） ， Where L is the distance between the origin of Cartesian coordinate system I and the origin of Cartesian coordinate system II, is the rotation angle of Cartesian coordinate system II relative to Cartesian coordinate system I around the central axis of the load core hub (19), is the angle between the line connecting the origin of Cartesian coordinate system I and the origin of Cartesian coordinate system II and the X-axis of Cartesian coordinate system I, is the unit vector in the XY plane in Cartesian coordinate system I, is the unit vector in the Y-axis direction in Cartesian coordinate system I, is the azimuth of the Cartesian coordinate system I, is the unit vector in the XY plane in Cartesian coordinate system II, is the unit vector in the Y-axis direction in Cartesian coordinate system II; is the azimuth of Cartesian coordinate system II; Step 3: Calculate the magnetic attraction torque of the Pth tile-shaped magnetic steel (6) and the Qth tile-shaped magnetic steel (6) on the sandwiched eight-shaped permanent magnet; From the first step, we can know the basis transformation matrix from Cartesian coordinate system II to Cartesian coordinate system I ,but （6）， in, and are the homogeneous coordinates of any point in Cartesian coordinate system I and Cartesian coordinate system II; Calculate the magnetic attraction of the Uth figure-eight permanent magnet and the Vth figure-eight permanent magnet sandwiched between the Pth tile-shaped magnetic steel (6) and the Qth tile-shaped magnetic steel (6): （7）， in: （8） in, is the relative position vector of any two magnetic charges on the surface of the tile-shaped magnet (6) and the figure-eight permanent magnet, is the vacuum permeability, are the starting angle and ending angle of the Pth tile-shaped magnet in Cartesian coordinate system I, are the starting angle and ending angle of the Qth tile-shaped magnet in Cartesian coordinate system I, are the starting angle and ending angle of the Uth figure eight permanent magnet in Cartesian coordinate system II, are the starting angle and ending angle of the Vth figure-eight permanent magnet in Cartesian coordinate system II; After that, calculate the moment arm of the magnetic attraction: make Magnetic force arm The four-dimensional homogeneous vector ,in =1 （9）， Thus, (10), Further obtain the magnetic attraction torque: （11）， Furthermore, the total torque transmitted by a permanent magnet transmission device with magnets arranged in an eight-shaped pattern under a given inner and outer rotor slip angle is obtained: （12）， in, is the number of eight-shaped permanent magnet slots, is the absolute value of the magnetic attraction torque; At this point, the torque calculation of a permanent magnet transmission device with magnets arranged in an eight-shaped pattern is completed.

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