A built-in permanent magnet motor rotor structure

Abstract

This invention proposes a rotor structure for a high-speed permanent magnet motor, belonging to the technical field of high-speed permanent magnet motors. It solves the problems of permanent magnet displacement and breakage, high eddy current losses in the metal sheath, and fatigue cracking in high-speed permanent magnet motor rotors under centrifugal force. The structure includes rotor ribs, a rotor core, silicon steel sheets, and permanent magnets. The rotor core is made of multiple stacked silicon steel sheets, each with V-shaped structures evenly spaced along the circumference. The stacked silicon steel sheets form multiple evenly distributed V-shaped grooves along the circumference. The permanent magnets are segmented and embedded within the V-shaped grooves. Dovetail-shaped slots are provided at both ends of the V-shaped grooves, and semi-circular unloading grooves are provided on the axial side of the dovetail-shaped slots. Axial channels are formed at the fracture points of the magnetic bridges after the stacking of multiple silicon steel sheets, and rotor ribs are provided therein. The edges of the V-shaped grooves and the edges of the permanent magnets are rounded. It is mainly used for high-speed permanent magnet motors operating under high-speed centrifugal force environments.

Description

Technical Field

[0001] This utility model belongs to the field of high-speed permanent magnet motor technology, and in particular relates to a rotor structure of a motor with built-in permanent magnets. Background Technology

[0002] High-speed permanent magnet motors are widely used in industrial applications requiring high overload capacity, such as fans and pumps, due to their advantages of high power density and fast dynamic response. However, with the increase in motor center height, the rotor outer diameter and speed increase simultaneously, leading to a sharp rise in centrifugal force on the rotor at high speeds, posing a severe challenge to the mechanical reliability and electromagnetic performance of the rotor structure. Currently, mainstream built-in permanent magnet rotors use metal sheaths (such as stainless steel) to confine the permanent magnets. However, the conductivity of metal materials creates strong eddy currents in alternating magnetic fields, causing significant energy loss, reduced motor efficiency, and localized temperature rises, accelerating the risk of thermal demagnetization of the permanent magnets. Simultaneously, the permanent magnets themselves are prone to displacement or even breakage under high centrifugal force. Conventional magnet slot structures, with their right-angled edges, further amplify the probability of breakage, threatening motor operational safety. Furthermore, the metal sheath is prone to fatigue cracks under long-term alternating centrifugal loads, and the frequent start-stop and overload conditions of fans and pumps accelerate the fatigue failure process of the sheath. Once cracked, it will directly lead to the uncontrolled scattering of the permanent magnets and damage to the motor. While existing technologies attempt to alleviate the problem by thickening the sheath or optimizing the magnet bonding, the fundamental contradiction between eddy current loss and structural fatigue has not yet been resolved. Utility Model Content

[0003] In view of this, the present invention aims to propose a rotor structure with built-in permanent magnet to solve the problems of permanent magnet displacement and breakage, large eddy current loss of metal sheath and fatigue cracking in high-speed permanent magnet motor rotors under centrifugal force.

[0004] To achieve the above objectives, this utility model adopts the following technical solution: a rotor structure for a motor with an embedded permanent magnet, comprising rotor ribs, a rotor core, silicon steel sheets, and permanent magnets; the rotor core is made of multiple stacked silicon steel sheets, each silicon steel sheet having V-shaped structures evenly spaced along the circumferential direction, and the stacked silicon steel sheets forming multiple V-shaped groove structures evenly distributed along the circumferential direction; the permanent magnets are segmented and embedded within the V-shaped groove structures, and dovetail-shaped slots are provided at both ends of the V-shaped groove structures, with axial sides of the dovetail-shaped slots having... A semi-circular unloading groove is provided; the magnetic bridge of the silicon steel sheet is broken to form a fracture, and the fractures of multiple silicon steel sheets stacked together form an axial channel, in which rotor ribs are provided; magnetic pole pressure plates are provided on both sides of the rotor core, and rotor baffles are provided on the outside of the magnetic pole pressure plates; the two ends of the rotor ribs are connected to the rotor baffles on both sides of the rotor core; a carbon fiber protective cover is provided on the outer surface of the rotor core, and the edges of the V-shaped groove structure and the permanent magnets are all provided with 0.5~1mm rounded corners.

[0005] Furthermore, the rotor ribs and the fracture surface are interference fit.

[0006] Furthermore, the space between the permanent magnet and the wall of the V-groove structure is filled with epoxy resin adhesive.

[0007] Furthermore, the rotor ribs are made of a non-magnetic alloy material.

[0008] Furthermore, the magnetic pole pressure plate is connected to the rotor core via a double-ended screw, and the rotor baffle is connected to the magnetic pole pressure plate via screws.

[0009] Furthermore, the carbon fiber protective cover is made by winding carbon fiber prepreg.

[0010] Furthermore, the carbon fiber protective cover uses T700 or T800 grade carbon fiber layers.

[0011] Furthermore, a rotating shaft is provided inside the rotor core.

[0012] Furthermore, the permanent magnet is made of neodymium iron boron material.

[0013] Compared with the prior art, the beneficial effects of this utility model are: 1. This utility model effectively reduces the thickness of the magnetic bridge by breaking the magnetic bridge, which reduces the air gap of the motor compared with the traditional surface-mounted high-speed motor rotor structure. The dovetail-shaped slots at both ends of the V-groove structure form a mechanical lock for the permanent magnet. Combined with the interference fit between the rotor rib and the magnetic bridge break, a double reinforcement structure is formed in the rotor axis, which can resist the displacement of the permanent magnet under high-speed centrifugal force. In addition, the 0.5-1mm rounded corner design of the permanent magnet edge and slot effectively disperses stress concentration. Combined with the unloading groove to release local stress peaks, the risk of permanent magnet breakage is greatly reduced. 2. This utility model uses a carbon fiber protective cover to replace the traditional metal sheath. By utilizing the non-magnetic properties of carbon fiber, the eddy current path caused by the alternating magnetic field is fundamentally blocked. The carbon fiber layer is formed by winding and curing prepreg, which not only achieves lightweighting but also avoids the rotor temperature rise problem caused by induced current, and improves motor efficiency and permanent magnet thermal stability. In addition, the high specific strength and fatigue resistance of the carbon fiber protective cover can withstand long-term high-speed centrifugal loads and frequent start-stop impacts. Combined with the axial reinforcement structure of the rotor ribs, it prevents the risk of fatigue cracking of the traditional metal sheath and extends the service life of the rotor. 3. The rotor ribs set at the fracture of the magnetic bridge in this utility model are interference-fitted with the fracture to form an axially reinforced skeleton, which suppresses structural deformation under high-speed alternating stress. The semi-circular design of the unloading groove eliminates stress concentration at the end of the V-groove. Combined with the high fatigue strength characteristics of the carbon fiber protective cover, the problem of fatigue cracking of the sheath is completely solved. 4. The rotor ribs of this utility model are made of non-magnetic alloy material, which blocks the axial leakage magnetic path and improves the utilization rate of the permanent magnet magnetic field; the epoxy resin glue filling the space between the permanent magnet and the V-groove wall provides an insulating layer while achieving bonding and fixing, reducing eddy current losses under high-frequency operating conditions, and ensuring the high overload capacity and dynamic response stability of the motor under fan and pump loads. Attached Figure Description

[0014] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings: Figure 1 This is a schematic diagram of the shaft side structure of a motor rotor structure with built-in permanent magnets described in this utility model, without carbon fiber sheath. Figure 2 This is a schematic diagram of the silicon steel sheet for a built-in permanent magnet motor rotor structure according to the present invention; Figure 3 This is a cross-sectional structural diagram of a rotor structure for a motor with an integrated permanent magnet as described in this utility model. Figure 4 for Figure 3 Enlarged structural diagram at point A; Figure 5 This is a schematic diagram of the magnetic pole pressure plate of a motor rotor structure with built-in permanent magnets according to the present invention.

[0015] In the picture: 1. Rotating shaft; 2. Rotor baffle; 3. Magnetic pole pressure plate; 4. Rotor rib; 5. Rotor core; 6. Silicon steel sheet; 7. Permanent magnet; 8. Unloading groove; 9. Carbon fiber sheath; 10. Dovetail groove. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present utility model can be combined with each other, and the described embodiments are only some embodiments of the present utility model, not all embodiments.

[0017] Detailed implementation method: See Figure 1-5This embodiment describes a rotor structure for a motor with an integrated permanent magnet, comprising rotor ribs 4, a rotor core 5, silicon steel sheets 6, and permanent magnets 7. The rotor core 5 is made of multiple stacked silicon steel sheets 6, which serve as the basic stacking unit. After stamping, they form the geometric profile of the rotor. The rotor core 5 acts as the magnetic circuit carrier and structural support, utilizing the low iron loss and high permeability characteristics of the silicon steel sheets 6 to optimize magnetic flux conduction. The stacked structure reduces temperature rise by blocking eddy current paths. V-shaped structures are evenly spaced along the circumferential direction on the silicon steel sheets 6, and the stacking of multiple silicon steel sheets 6 forms multiple V-shaped structures along the circumference. The circumferentially distributed V-groove structure and the circumferentially spaced V-shaped openings ensure that the stacked components form uniformly distributed V-grooves, achieving magnetic pole symmetry and magnetic field uniformity, and suppressing torque pulsation. The permanent magnets 7 are segmented and embedded within the V-groove structure. The V-groove structure accommodates the permanent magnets 7 and optimizes the magnetic field distribution. The V-angle provides a larger permanent magnet coverage area and magnetic flux focusing capability, reducing magnetic leakage. The permanent magnets 7 provide a constant excitation magnetic field. The segmented embedding of the permanent magnets 7 into the V-groove structure prevents cracking under thermal stress or mechanical vibration. After segmentation, each segment of the permanent magnet 7 can expand and contract independently. To reduce the risk of breakage, the V-shaped layout enhances the magnetic field strength at the center of the magnetic poles, increasing torque density. The permanent magnet 7, embedded in the V-shaped groove, ensures close contact between the permanent magnet 7 and the rotor core 5, improving magnetic circuit efficiency. The V-shaped groove structure has dovetail-shaped slots 10 at both ends, with semi-circular unloading grooves 8 on the axial side of each slot. The dovetail-shaped slots 10 are used to fix the permanent magnet 7, preventing axial or radial displacement during high-speed motor rotation. The semi-circular unloading grooves 8 alleviate stress concentration and prevent cracking. During rotation or heating, stress easily concentrates in the dovetail-shaped slots. At the root of the groove 10, a semi-circular unloading groove 8 is used to smoothly transition and reduce stress peaks. The silicon steel sheet 6 is broken at the magnetic bridge to form a fracture. The magnetic bridge refers to the magnetic reluctance path between magnetic poles. The fracture is designed on the magnetic bridge to break the magnetic bridge, increase magnetic reluctance, avoid magnetic flux shunting and reduce efficiency, and provide space for the rotor rib 4. The fractures of multiple silicon steel sheets 6 after being stacked form an axial channel. The rotor rib 4 is provided in the axial channel. The rotor rib 4 serves as a support to enhance the axial stiffness of the rotor core 5. It resists centrifugal deformation with high yield strength and avoids the formation of additional eddy current paths.Magnetic pole pressure plates 3 are provided on both sides of the rotor core 5 along its axial direction. The outer contour of the magnetic pole pressure plates 3 is adapted to the shape of the magnetic pole region of the silicon steel sheet 6. The V-groove contour dimension of the magnetic pole pressure plate 3 is larger than the actual inner cavity dimension of the V-groove structure formed by the stacking of silicon steel sheets 6, ensuring that the magnetic pole pressure plate 3 does not interfere with the embedding path of the permanent magnet 7 after assembly. This gap adaptation design allows the pressure plate to completely cover the stacked end face of the silicon steel sheet 6, while avoiding rigid contact with the permanent magnet in the V-groove, eliminating assembly stress caused by manufacturing tolerances. The magnetic pole pressure plate 3 has a clearance feature corresponding to the magnetic bridge break of the silicon steel sheet 6, ensuring that the through channel of the rotor rib 4 is unobstructed. The magnetic pole pressure plate 3 is used for... The silicon steel sheets 6, after being constrained and stacked, generate axial displacement and counteract the loosening caused by electromagnetic vibration. The magnetic pole pressure plate 3 is made of stainless steel, and a rotor baffle 2 is provided on the outside of the magnetic pole pressure plate 3. The two ends of the rotor rib 4 are connected to the rotor baffle 2 on both sides of the rotor core 5. The rotor baffle 2 is used to fix the rotor rib 4. A carbon fiber protective cover 9 is provided on the outer surface of the rotor core 5. The carbon fiber protective cover 9 wraps the rotor surface with a lightweight and high-strength material to suppress the separation between the silicon steel sheets 6. The edges of the V-groove structure and the edges of the permanent magnet 7 are provided with rounded corners of 0.5~1mm. The rounded corner design reduces stress concentration and magnetic field distortion.

[0018] The rotor structure of this invention achieves efficient energy conversion through the synergistic effect of electromagnetic and mechanical means. The rotor core 5 is composed of stacked silicon steel sheets 6 forming a V-groove structure. Segmented permanent magnets 7 are embedded within the V-groove structure to generate the main magnetic field. The V-groove design forces the magnetic flux to concentrate through the air gap, enhancing torque output. To resist high-speed centrifugal force and vibration, axially fractured grooves are inserted into rotor ribs 4. The rotor ribs 4 are connected at both ends to rotor baffles 2, forming an anti-deformation skeleton. Simultaneously, magnetic pole pressure plates 3 constrain the stacked silicon steel sheets 6. Dovetail-shaped slots 10 and semi-circular unloading slots 8 jointly lock the permanent magnets 7 and release mechanical stress, preventing the permanent magnets 7 from... Displacement or cracking is prevented by the carbon fiber protective cover 9, which isolates external erosion and reduces eddy current losses. The rounded corners of all sharp edges eliminate stress concentration points and prevent magnetic field distortion. The thickness of the magnetic bridge is effectively reduced by the magnetic bridge fracture. Compared with the traditional surface-mounted high-speed motor rotor structure, the air gap of the motor is reduced. The structure is reinforced by rotor ribs 4, magnetic pole pressure plates 3 and rotor baffles 2. Reliable operation of the rotor at high speed is achieved while ensuring magnetic field utilization. It is suitable for high-speed and ultra-high-speed drive scenarios such as industrial fans and compressors.

[0019] The rotor rib 4 and the fracture are interference fit. The interference fit makes the rotor rib 4 a rigid skeleton. After it is combined with the groove of the fracture, the load is evenly transmitted to the rotor baffles 2 on both sides through friction, which significantly improves the overall bending resistance and torsional vibration resistance of the rotor. The prestress generated by the interference fit directly offsets the centrifugal expansion force of the silicon steel sheet 6 stack when the rotor rotates at high speed, preventing the silicon steel sheet 6 stack from loosening or displacement, and ensuring the stability of the magnetic circuit.

[0020] The space between the permanent magnet 7 and the wall of the V-groove structure is filled with epoxy resin. After the epoxy resin is cured, it forms a strong and tough adhesive layer, which completely eliminates the assembly gap between the permanent magnet and the wall of the groove, and prevents the magnet from fretting wear caused by high-speed centrifugal force or vibration.

[0021] The rotor rib 4 is made of a non-magnetic alloy material, which is austenitic stainless steel or nickel-based alloy.

[0022] The magnetic pole pressure plate 3 is connected to the rotor core 5 by a double-headed screw, so as to realize the bidirectional pressing of the rotor core 5 by the magnetic pole pressure plate 3. The rotor baffle 2 is connected to the magnetic pole pressure plate 3 by screws, forming a closed structure at the axial end of the rotor core 5.

[0023] The carbon fiber protective cover 9 is made by winding carbon fiber prepreg. The carbon fiber prepreg is wrapped around the outer surface of the rotor core at a winding angle of ±45°. The winding tension of the carbon fiber protective cover 9 is controlled at 60~100N. After high-temperature curing, it is precision machined to Ra≤0.8μm. By using the carbon fiber protective cover 9, the eddy current loss problem of traditional metal sheaths is avoided. At the same time, the precision machined surface can be directly used as the air gap boundary layer of the rotor magnetic circuit.

[0024] The carbon fiber protective cover 9 is made of T700 or T800 grade carbon fiber layer and is wrapped on the outer surface of the rotor core 5 by prepreg winding process.

[0025] The rotor core 5 is provided with a rotating shaft 1. The rotating shaft 1 is connected to the rotor core 5 through keyway fitting or heat fitting process to form a coaxial rigid integrated body. The two journal ends of the rotating shaft 1 extend to the outside of the rotor baffle 2 and are connected to the motor bearing seat through the flange to realize the functions of rotor torque transmission and rotation support.

[0026] The permanent magnet 7 is made of neodymium iron boron material.

[0027] The installation steps of this utility model are as follows: Step 1: Stack a certain number of silicon steel sheets 6 to the preset length of the rotor core 5, install magnetic pole pressure plates 3 at both ends of the stacked silicon steel sheets 6, and use double-headed screws to penetrate the stacked silicon steel sheets 6 and magnetic pole pressure plates 3 for bidirectional locking and fixing. Step 2: After heating the assembled rotor core 5 as a whole, the rotor core 5 is assembled onto the shaft 1 through a hot fitting process, and the rotor rib 4 is pressed into the axial groove formed by the magnetic bridge break with an interference fit. Step 3: Insert the segmented permanent magnets 7 made of neodymium iron boron into the V-groove structure of the rotor core 5 one by one, then fill the gap between the permanent magnets 7 and the groove wall with epoxy resin and cure it. Step 4: Assemble the rotor baffle 2 on the outside of the magnetic pole pressure plate 3, and weld and fix the two ends of the rotor rib 4 to the rotor baffle 2; Step 5: Machining the outer surface of rotor core 5; Step 6: Use T700 or T800 grade carbon fiber prepreg to wrap the rotor surface at a winding angle of ±45°, control the winding tension to 80N±20N, and after high temperature curing, finish it to a dimensional tolerance of ±0.01mm and a surface roughness Ra≤0.8μm, thereby forming a carbon fiber sheath 9 on the outer surface of the rotor core 5.

[0028] The specific embodiments of this utility model disclosed above are merely illustrative of the present utility model. These specific embodiments do not exhaustively describe all details, nor do they limit the utility model to only the described embodiments. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this utility model, thereby enabling those skilled in the art to better understand and utilize it.

Claims

1. An interior permanent magnet motor rotor structure, characterized by: The system includes rotor ribs (4), rotor core (5), silicon steel sheets (6), and permanent magnets (7); the rotor core (5) is made of multiple silicon steel sheets (6) stacked together, and V-shaped structures are evenly spaced along the circumferential direction on the silicon steel sheets (6). After multiple silicon steel sheets (6) are stacked together, multiple V-shaped groove structures are evenly distributed along the circumferential direction; the permanent magnets (7) are segmented and embedded in the V-shaped groove structures, and dovetail-shaped slots (10) are provided at both ends of the V-shaped groove structures. Semi-circular unloading grooves (8) are provided on the axial side of the dovetail-shaped slots (10); the silicon steel sheets (6) The magnetic bridge is broken to form a fracture, and the fracture formed by stacking multiple silicon steel sheets (6) forms an axial channel. The axial channel is provided with rotor ribs (4); magnetic pole pressure plates (3) are provided on both sides of the rotor core (5), and rotor baffles (2) are provided on the outside of the magnetic pole pressure plates (3). The two ends of the rotor ribs (4) are connected to the rotor baffles (2) on both sides of the rotor core (5); carbon fiber protective cover (9) is provided on the outer surface of the rotor core (5), and the edges of the V-shaped groove structure and the permanent magnet (7) are provided with rounded corners of 0.5~1mm.

2. A rotor structure for an interior permanent magnet electric machine according to claim 1, characterized in that: The rotor rib (4) is interference-fitted with the fracture surface.

3. The interior permanent magnet motor rotor structure of claim 1, wherein: The space between the permanent magnet (7) and the wall of the V-groove structure is filled with epoxy resin.

4. The interior permanent magnet motor rotor structure of claim 1, wherein: The rotor rib (4) is made of non-magnetic alloy material.

5. The interior permanent magnet motor rotor structure of claim 1, wherein: The magnetic pole pressure plate (3) is connected to the rotor core (5) by a double-headed screw, and the rotor baffle (2) is connected to the magnetic pole pressure plate (3) by screws.

6. The interior permanent magnet motor rotor structure of claim 1, wherein: The carbon fiber protective cover (9) is made by winding carbon fiber prepreg.

7. A rotor structure for an interior permanent magnet electric machine according to claim 6, characterized in that: The carbon fiber protective cover (9) uses a T700 or T800 grade carbon fiber layer.

8. The interior permanent magnet motor rotor structure of claim 1, wherein: The rotor core (5) is provided with a rotating shaft (1).

9. The interior permanent magnet motor rotor structure of claim 1, wherein: The permanent magnet (7) is made of neodymium iron boron material.

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