Permanent magnet fixing structure and installation method for axial flux motor

Abstract

This invention discloses a permanent magnet fixing structure for an axial flux motor, comprising an annular mounting plate and a mating cover plate. The mounting plate has a groove for accommodating the permanent magnet, and the edge of the groove has positioning screw holes. The cover plate has through holes corresponding to the positioning screw holes. This invention also provides an installation method. The permanent magnet fixing structure provided by this invention enables glue-free fixing of the permanent magnet to the iron sheet, and the glue-free fixing method also facilitates the subsequent recycling of raw materials.

Description

Technical Field

[0001] This invention belongs to the technical field of axial flux motor design, and particularly relates to a permanent magnet fixing structure and installation method for axial flux motors. Background Technology

[0002] Axial flux motors are widely used in new energy vehicles, industrial servo systems, aerospace, and other fields due to their high power density and small axial dimensions. In their core structure, the permanent magnet (such as neodymium iron boron) must be tightly fixed to the iron sheet (magnetic pole carrier) to ensure that there is no loosening or displacement during operation; otherwise, it will lead to magnetic flux disorder, increased vibration and noise, or even motor failure.

[0003] The drawbacks of existing fixing methods: 1. Adhesive bonding: Relying on adhesives such as epoxy resin, this method has the following problems: (1) High temperature failure: When the motor operating temperature exceeds 120℃, the adhesive is prone to aging, which leads to the permanent magnet falling off (especially in high temperature scenarios such as drive motors of new energy vehicles). (2) Difficult to recycle: Disassembly requires high temperature heating or chemical solvents to dissolve the adhesive, the permanent magnet and iron sheet are easily damaged, and the reuse rate is ≤30%; (3) Low assembly efficiency: Permanent magnet bonding requires multiple processes such as gluing, positioning, pressure holding, and curing. The process chain is long and time-consuming, which is not conducive to automated assembly and large-scale efficient production.

[0004] 2. Bolt / Rivet Fixing: This requires drilling holes in the permanent magnet, which damages the magnet structure, resulting in a magnetic flux loss of ≥5%, and stress concentration is likely to occur at the hole location, with a magnet breakage rate of ≥8%.

[0005] 3. Injection molding for fixation: The plastic wrapping layer affects the magnetic flux path, reducing motor efficiency by 3%-5%, and the plastic is prone to deformation at high temperatures, resulting in poor fixation reliability.

[0006] Furthermore, axial flux motors, due to their compact axial dimensions and high power density (15%-30% higher than radial flux motors), have become core components in new energy vehicle drive axles, aerospace auxiliary power systems, and precision machine tool servo units. Their magnetic circuit performance is highly dependent on the installation accuracy of symmetrically distributed permanent magnets (typically 2n poles, n≥2)—the deviation between adjacent magnetic poles must be ≤0.05mm, and the air gap deviation between the stator and rotor must be ≤0.03mm; otherwise, it will lead to: (1) Magnetic circuit imbalance, torque fluctuation ≥5%, motor operating vibration and noise (NVH) exceeding the standard; (2) Insufficient local air gap can cause stator and rotor rubbing, which can burn out the motor in severe cases; (3) The magnetic flux utilization rate decreases, and the motor energy efficiency decreases by 2%-4%. Summary of the Invention

[0007] The purpose of this invention is to provide a permanent magnet fixing structure and installation method for an axial flux motor. This permanent magnet fixing structure can solve the problems of traditional stators relying on adhesives and failing at high temperatures.

[0008] To achieve the first objective of this invention, the following technical solution is provided: a permanent magnet fixing structure for an axial flux motor, comprising an annular mounting plate and a matching cover plate, wherein the mounting plate is provided with a groove for accommodating a permanent magnet, the edge of the groove is provided with a positioning screw hole, and the cover plate is provided with a through hole corresponding to the positioning screw hole.

[0009] This invention achieves glue-free fixation of permanent magnets and iron sheets through "mechanical fixing + precision fitting". At the same time, the glue-free fixation method also facilitates the recycling of raw materials later.

[0010] Specifically, the mounting plate adopts an integrated structure, and there are multiple grooves, which are arranged at intervals along the edge of the mounting plate.

[0011] Specifically, the mounting plate adopts a unit structure, and the end face of the unit structure is also provided with mounting screw holes for positioning the circumferential surface of the cover plate.

[0012] Specifically, the magnetic permeability of the mounting plate and the cover plate is less than or equal to 1.05μ0.

[0013] Specifically, both the mounting plate and the cover plate are made of metal or non-metal materials.

[0014] Specifically, the metal material includes 304 / 316 stainless steel or 6061 aluminum alloy.

[0015] Specifically, the non-metallic material includes PA66+glass fiber or carbon fiber composite material.

[0016] To achieve the second objective of this invention, the following technical solution is provided: an installation method. The mounting of the permanent magnet fixing structure for the aforementioned axial flux motor includes: Clean the grooves of the mounting plate and the surface of the permanent magnet; Place the permanent magnet into the groove of the mounting plate, cover the permanent magnet with the cover plate, and lock and compact it by passing the mounting bolts through the through hole and the positioning screw hole.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: Improved production efficiency: Assembly does not require waiting for curing, and the assembly time for a single unit is reduced to within 10 minutes, making it suitable for mass production; Improved economic efficiency: The reuse rate of permanent magnets and iron sheets is ≥99%, and the recycling cost is reduced by more than 80%; no adhesive is required, reducing consumable costs. Attached Figure Description

[0018] Figure 1 This is an exploded view of the permanent magnet fixing structure provided in this embodiment; Figure 2 This is the mounting plate with an integrated structure provided in this embodiment; Figure 3 This is the mounting plate for the unit structure provided in this embodiment; Figure 4 for Figure 3 A perspective view of the mounting plate; Figure 5 for Figure 3 A schematic diagram of the mounting plate assembly; Figure 6 The cover plate provided in this embodiment; Figure 7 This is a schematic diagram of the assembly of the cover plate provided in this embodiment; In the diagram, 1 is the mounting plate; 2 is the cover plate; 3 is the permanent magnet; 4 is the groove; 5 is the positioning screw hole; 6 is the through hole; and 7 is the assembly screw hole. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] like Figure 1 The figure shown is an exploded view of a permanent magnet fixing structure for an axial flux motor provided in this embodiment. It includes an annular mounting plate 1 and a matching cover plate 2. The permanent magnet 3 is clamped and encapsulated by the mounting plate 1 and the cover plate 2 to form a stator unit. Finally, multiple stator units are connected in series through a rotating shaft to form a stator structure.

[0021] exist Figure 1 The mounting plate 1 shown in the image represents one type of structure.

[0022] More specifically, such as Figure 2As shown, the mounting plate 1 of the integrated structure provided in this embodiment is a whole circular plate with multiple grooves 4. The multiple grooves are arranged at intervals along the edge of the mounting plate 1, and the edge of the groove 4 is provided with positioning screw holes 5.

[0023] like Figure 3 As shown, the mounting plate 1 of the unit structure provided in this embodiment is similar in shape to the single permanent magnet 3, thereby covering the permanent magnet 3.

[0024] like Figure 4 The diagram shows a schematic of the mounting plate 1 assembly of the unit structure. Two adjacent mounting plates 1 are connected in series and fixed by positioning screw holes 5 stacked on the same axis.

[0025] like Figure 5 As shown, the end face of the mounting plate 1 of the unit structure is also provided with mounting screw holes 7, so as to ensure that each unit structure and the cover plate 2 can firmly clamp the permanent magnet 3.

[0026] like Figure 6 The diagram shown is a schematic of the cover plate 2 provided in this embodiment. The cover plate 2 has a through hole 6 that corresponds to the positioning screw hole 5.

[0027] Compared to the mounting plate 1 of the unit structure, such as Figure 7 As shown, the cover plate 2 has through holes 6 on its circumferential surface that correspond to the mounting screw holes 7, thereby preventing the mounting plate 1 of the unit structure from slipping.

[0028] More specifically, a 0.3-0.8mm thick silicone / nitrile rubber buffer layer is also attached to the groove 4, with a grid-like anti-slip texture (0.1mm deep) on the surface. By increasing friction, micro-displacement of the permanent magnet caused by high-frequency vibration is avoided, further improving the fixation reliability.

[0029] Furthermore, in this embodiment, the material selection for mounting plate 1 must meet the requirements of "high strength + low magnetic permeability (to avoid interference with magnetic flux)," and the following options are available: Metal materials: 304 / 316 stainless steel (tensile strength ≥520MPa), 6061 aluminum alloy (tensile strength ≥310MPa); Non-metallic materials: PA66 + 30% glass fiber (temperature resistance ≥150℃), carbon fiber composite material (density ≤1.6g / cm³). 3 (lightweight) Common requirements: permeability ≤ 1.05μ0 (μ0 is the permeability of free space), to avoid becoming a "leakage point" in the magnetic flux path.

[0030] This embodiment also provides an installation method for installing the permanent magnet fixing structure for the axial flux motor provided in the above embodiment, including: 1) Clean the contact surface of the iron sheet and the surface of the permanent magnet to ensure there are no impurities; 2) Place the permanent magnet against the preset position on the iron sheet, and initially align it using the grooves on the iron sheet; 3) Install the fasteners, align the magnet positioning holes with the fastener alignment holes, and tighten the bolts to the preset preload. 4) Inspection: The displacement of the permanent magnet is measured with a dial indicator (≤0.01mm). Assembly is completed after the displacement is qualified.

[0031] In this embodiment, in order to achieve better installation results, a weakening layer is provided between two adjacent magnets along the rotation axis during the installation process to reduce the attraction between the magnets on the symmetrical mounting plates. The weakening layer is composed of a soft magnet with high magnetic permeability and a lubricating material with low magnetic permeability.

[0032] More specifically, the core of the high permeability soft magnetic material is permalloy (Ni80Fe20) or 30Q130 silicon steel sheet. Utilizing its low magnetic resistance characteristics, it guides some of the magnetic lines of force between the two permanent magnets to close and shunt along the inside of the weakening layer, reducing the magnetic attraction force directly acting on the permanent magnets to be assembled and reducing the magnetic attraction resistance during the assembly process.

[0033] Among them, permalloy (Ni80Fe20) is suitable for single blocks with a magnetic force ≥15 N, and its performance parameters are required to be: magnetic permeability ≥2000μ0; thickness 1-2 mm; elongation ≥30%.

[0034] 30Q130 silicon steel sheets are suitable for single-piece magnetic forces <15 N; cost-sensitive applications require performance parameters such as permeability ≥1500μ0 and thickness 1-2 mm. The core of low magnetic permeability lubricating materials is a polytetrafluoroethylene (PTFE) film. Utilizing its low magnetic permeability and low coefficient of friction, it is adhered to the surface of a high magnetic permeability soft magnetic material, which facilitates the subsequent removal of the weakening layer.

[0035] The surface of the polytetrafluoroethylene (PTFE) film needs to be smoothed, and its performance parameters are required to be: magnetic permeability ≤1.01μ0; thickness 0.2-0.5mm; coefficient of friction ≤0.05. The specific execution process is as follows: 1) Cleaning the magnet and mounting surface: Wipe the surface with isopropyl alcohol; oil residue ≤5mg / m³ 2 No particulate matter (particle size ≥ 0.01 mm) 2) Weakening Layer Attachment: A high-permeability soft magnetic material with a polytetrafluoroethylene (PTFE) film is attached to the surface of the mounting plate. Each piece of high-permeability soft magnetic material must completely cover two adjacent magnets, and all magnets must be covered. The outer edge should extend at least 1 cm beyond the magnet edge for easy removal. 3) Initial positioning (tooling aid): The magnet is placed in the tooling positioning slot, with the gap between the edge and the slot wall ≤ 0.5mm; there is no skewing (verticality deviation ≤ 0.1°). 4) Fine adjustment: The dial indicator is attached to the reference surface of the tooling to monitor the edge deviation of the magnet, and manually fine-tunes it to ≤0.03mm; 5) Fixing and stripping the weakening layer: Fix the motor with a clamp; strip the weakening layer.

[0036] The solution provided by this invention, compared to existing technologies, facilitates subsequent material recycling. The steps are as follows: 1) Loosen the nut, remove the fixing part, and separate the permanent magnet from the iron plate; 2) Screening: The integrity rate of permanent magnets and iron sheets is ≥99%, and they can be directly reused or reprocessed.

[0037] Furthermore, the terms "upper," "lower," "inner," "outer," "front," and "rear" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise specifically stated, the relative steps, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0038] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included in the scope of the claims of the present invention.

[0039] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A permanent magnet fixing structure for an axial flux motor, characterized by, It includes an annular mounting plate and a matching cover plate. The mounting plate has a groove for accommodating a permanent magnet, and the edge of the groove has a positioning screw hole. The cover plate has a through hole arranged corresponding to the positioning screw hole.

2. The permanent magnet fixing structure for an axial flux motor according to claim 1, characterized in that, The mounting plate adopts an integral structure, and there are multiple grooves, which are arranged at intervals along the edge of the mounting plate.

3. The permanent magnet fixation structure for an axial flux machine according to claim 1, characterized by, The mounting plate adopts a unit structure, and the end face of the unit structure is also provided with mounting screw holes for positioning the circumferential surface of the cover plate.

4. The permanent magnet fixation structure for an axial flux machine according to claim 1, characterized by, The magnetic permeability of the mounting plate and the cover plate is less than or equal to 1.05μ0.

5. The permanent magnet fixation structure for an axial flux machine according to claim 1, characterized by, Both the mounting plate and the cover plate are made of metal or non-metal materials.

6. The permanent magnet fixation structure for an axial flux machine according to claim 5, characterized by, The metal material includes 304 / 316 stainless steel or 6061 aluminum alloy.

7. The permanent magnet fixation structure for an axial flux machine according to claim 5, characterized by, The non-metallic materials include PA66+glass fiber or carbon fiber composite materials.

8. A method of mounting, characterized by, The mounting of the permanent magnet fixing structure for an axial flux motor as described in any one of claims 1 to 7 includes: Clean the grooves of the mounting plate and the surface of the permanent magnet; Place the permanent magnet into the groove of the mounting plate, cover the permanent magnet with the cover plate, and lock and compact it by passing the mounting bolts through the through hole and the positioning screw hole.

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