A magnetic steel module structure of a rotor of a permanent magnet motor with radial air ducts

Abstract

The application belongs to the technical field of motor manufacturing, and discloses a magnetic steel module structure of a permanent magnet motor rotor with a radial air duct, which comprises a plurality of magnetic steels, a cushion block assembly and two stainless steel covers, the plurality of magnetic steels are arranged along the motor axis direction in sequence, the cushion block assembly comprises first cushion blocks arranged at the upper and lower ends between adjacent magnetic steels, and second cushion blocks arranged at the upper and lower ends of the outermost one of the magnetic steels in the arrangement direction, the two stainless steel covers are wrapped on the upper and lower sides of the plurality of magnetic steels and the cushion block assembly one by one, and glue is coated between the inner wall of each stainless steel cover and the outer wall of the corresponding magnetic steel and cushion block assembly, so that the magnetic steels, the cushion block assembly and the stainless steel cover form an integral module structure. The magnetic steel module structure of the permanent magnet motor rotor with the radial air duct can fix the magnetic steels and the cushion blocks into a group through the stainless steel cover, can simplify the assembly process of the built-in permanent magnet rotor with the radial air duct, can improve the production efficiency, and can prevent the magnetic steels from being scratched with the rotor iron core.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage permanent magnet motor manufacturing technology, specifically relating to a magnet module structure for a permanent magnet motor rotor with radial air duct. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are increasingly used in industrial drives due to their high efficiency, power factor, simple structure, and high power density. Unlike traditional synchronous motors, the rotor magnetic field of a PMSM is achieved by high-performance permanent magnets instead of pole windings, eliminating the need for excitation current and brush structures, and significantly reducing pole size. Based on the installation position of the permanent magnets on the rotor poles, PMSMs can be divided into internal PMSMs and surface-mounted PMSMs. Internal PMSMs have magnet slots inside the rotor, resulting in a stable overall structure and wide application. Because permanent magnets may demagnetize under extreme conditions, the temperature of the magnets and heat dissipation during motor operation must be carefully considered, especially for internal PMSMs where the magnets are located inside the iron core.

[0003] To ensure the overall magnetic circuit and the effective fixation of the magnets within the rotor, the magnet shape must match the pre-reserved magnet slots in the core, with only a certain assembly gap. This directly increases the difficulty of heat dissipation for the magnets within the rotor core. Currently, magnet manufacturers provide permanent magnets in block form. During installation, multiple magnetized permanent magnets are sequentially inserted along the rotor axis into the pre-pressed rotor core section at the corresponding magnet slot positions. When the core section is long, installing the magnets consumes a significant amount of time, and the magnetic forces between magnets and between magnets and the core pose a challenge to the process.

[0004] Overall, the design of high-temperature demagnetization cooling for magnets and the assembly of magnets are the main challenges in the design of permanent magnet synchronous motors.

[0005] To address the cooling and heat dissipation of permanent magnets under high power density, an effective method is to segment the rotor axially, with the corresponding iron core and permanent magnet blocks of the segmented rotor separated by a certain distance between segments. The resulting space is used to arrange radial cooling air ducts. Air enters the rotor axially and exits through the radial air ducts to cool the surface of the magnets. To provide support for the radial air duct structure, ventilation slots are arranged between the segmented rotor iron cores, which is a common ventilation structure for asynchronous motors with radial air ducts. For permanent magnet motors, the structure supporting the air ducts between the permanent magnets also needs to be considered. A simple method is to separate the magnets with ventilation slots. This method requires the magnets to be assembled simultaneously during the pressing of each iron core segment, and then the segments are separated by ventilation slots, i.e., the iron core with magnets is assembled in segments. With this radial air duct method, the rotor pressing cannot be performed as a whole segment; each segment needs to be pressed independently, magnets inserted, and then the whole assembly aligned, affecting overall efficiency and accuracy.

[0006] Another radial airflow structure between magnets uses spacers placed between the magnets. These spacers are glued to adjacent magnets or physically fixed to them. This type of structure allows for the integral press-fitting of the rotor core without segmentation; the magnets and spacers are assembled after the core is press-fitted. Simultaneously, the spacers, located within the radial airflow duct, must remain fixed under centrifugal force during motor operation and ensure structural reliability over long-term operation. Currently, a typical structure uses small cylinders to separate the magnets. To ensure the cylinders are properly embedded, mounting holes need to be machined on the magnet surface. The cylinders are then glued to the magnets, resulting in a complex overall structure. During magnet assembly, aligning, installing, and applying glue to the cylinders between the magnets presents significant technological challenges.

[0007] Whether using a segmented core or a spacer structure between magnets, the magnets must be installed in segments. For rotors with long axial lengths and numerous radial air ducts, magnet installation takes considerable time. When assembling the magnets into the magnet slots within the core, to prevent the magnets from wobbling within the slots during rotor rotation, the clearance between the magnets and the slots should be as small as possible while still meeting assembly requirements. However, this may cause the magnets to rub against the inner wall of the magnet slots, affecting the magnet material structure or performance. Summary of the Invention

[0008] The purpose of this invention is to overcome the defects of the prior art and provide a magnet module structure for a permanent magnet motor rotor with radial air ducts. The magnets and each pad are fixed together by stainless steel covers, which can simplify the assembly process of the built-in permanent magnet rotor with radial air ducts, improve production efficiency, save time, and prevent the magnets from rubbing against the rotor core.

[0009] The technical solution to achieve the above objective is: a magnet module structure for a permanent magnet motor rotor with a radial air duct, comprising... Multiple magnets, pad assembly, and two stainless steel covers, including: The multiple magnets are arranged sequentially along the motor axis, with each magnet corresponding to an axial segment of the rotor core. The pad assembly includes a first pad disposed at the upper and lower ends between adjacent magnets, and a second pad disposed at the upper and lower ends at one of the outermost ends of one of the magnet arrangement directions; Each stainless steel cover has a box-shaped structure, and the two stainless steel covers are wrapped around the upper and lower sides of the multiple magnets and pads in a corresponding manner; the inner wall of each stainless steel cover is coated with glue between the inner wall and the outer wall of the corresponding magnet and pad assembly, so that the magnets, pads and stainless steel covers form an integral module structure. The second pad has a pad extension that extends outward from the stainless steel cover. When the two magnet modules are axially arranged and assembled, the stainless steel covers of adjacent magnet modules are spaced apart by the pad extension of the second pad to prevent the stainless steel covers from directly contacting each other.

[0010] The above-mentioned magnet module structure of a permanent magnet motor rotor with radial air duct, wherein the dimension of the first pad along the motor axial direction is consistent with the width of the radial air duct of the rotor core. The dimension of the second pad along the motor axis is set as follows: the axial dimension of the second pad plus the wall thickness of the stainless steel cover is equal to the width of the radial ventilation channel of the rotor core.

[0011] The above-mentioned magnet module structure of a permanent magnet motor rotor with radial air duct, wherein the stainless steel cover is provided with a first fastening piece structure extending inward at the side wall position corresponding to the first pad block; The stainless steel cover has a second fastener structure extending inward at the side wall position corresponding to the second pad block; The distance between the first and second fastening structures and the bottom surface of the stainless steel cover is equal to the height of the corresponding pad, which is used to constrain the movement of each pad in the direction of the magnet height.

[0012] The above-mentioned magnet module structure for a permanent magnet motor rotor with radial air duct, wherein the pad assembly is made of a non-magnetic lightweight material, namely epoxy board.

[0013] The above-mentioned magnet module structure of a permanent magnet motor rotor with radial air duct, wherein the magnet is a flat block structure, and its cross-sectional shape perpendicular to the motor axis matches the slot shape of the magnet slot on the rotor core. The length of each magnet along the motor axis is consistent with the axial segment length of the rotor core.

[0014] The above-mentioned magnet module structure of a permanent magnet motor rotor with radial air duct, wherein the magnet, the first pad block and the second pad block have the same dimensions along the width direction of the magnet and the front and rear end faces are aligned. The upper and lower end faces of the magnet, the first pad, and the second pad along the height direction of the magnet are respectively aligned with the inner wall of the corresponding stainless steel cover.

[0015] The above-mentioned magnet module structure for a permanent magnet motor rotor with radial air duct is wherein the magnet module is integrally assembled and pushed into the magnet slot corresponding to the rotor core along the motor axis; the space corresponding to the first pad and the second pad constitutes part of the radial ventilation duct of the rotor core.

[0016] In the above-mentioned magnet steel module structure of a permanent magnet motor rotor with radial air duct, when the rotor core rotates at 1800 rpm, the maximum stress of the stainless steel cover does not exceed 200 MPa, which is lower than the yield strength of the stainless steel cover.

[0017] The magnet module structure of the permanent magnet motor rotor with radial air duct of the present invention has the following technical effects: (1) Fixing the magnets and each pad block together with a stainless steel cover can simplify the assembly process of the built-in permanent magnet rotor with radial air duct. (2) Each pad and magnet are prepositioned and fixed, and enclosed by a stainless steel cover to form a whole. The magnet module and rotor core can be assembled independently. The magnet module has fixed specifications and can be assembled and supplied in batches. Compared with the traditional assembly of magnets as units, the overall process efficiency and reliability of the magnet module and rotor core are improved. (3) The modular assembly of multiple magnets replaces the sequential assembly of single magnets, greatly saving time; (4) The stainless steel cover surrounding the magnet module structure can protect the magnet during assembly. When the magnet module is assembled into the rotor core, the stainless steel cover in the magnet module is in direct contact with the rotor core. Even if the assembly tolerance between the magnet module and the rotor core is too small and squeeze occurs, the magnet will not rub against the rotor core. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural diagram of the magnet module structure of the permanent magnet motor rotor with radial air duct of the present invention; Figure 2 A schematic diagram of the assembly of adjacent magnet modules (cut along the rotor axis). Figure 3 This is a cross-sectional view of the magnet module structure of the permanent magnet motor rotor with radial air duct of the present invention. Figure 4 This is a schematic diagram of the stainless steel cover. Figure 5 This is a schematic diagram of the assembly of the magnet module and the rotor core (two magnet arrangement forms: along the rotor radial direction and perpendicular to the rotor radial direction). Figure 6 The stress condition of the stainless steel cover during motor operation using the magnet module of the present invention; Figure 7 A stainless steel cover is used to protect the magnets from rubbing against the inner wall of the rotor slot. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solution of the present invention, its specific embodiments are described in detail below with reference to the accompanying drawings: Please see Figures 1 to 7 The preferred embodiment of the present invention is a magnet module structure for a permanent magnet motor rotor with radial air duct, comprising multiple magnets 1, a pad assembly and two stainless steel covers 4.

[0020] Multiple magnets 1 are arranged sequentially along the motor axis B (hereinafter referred to as B direction), and each magnet 1 corresponds to a segment of the rotor core along the axis. The motor axis, i.e. the direction of magnet arrangement, is uniformly defined as B direction, the magnet height direction is defined as C direction, and the magnet width direction is defined as A direction.

[0021] The pad assembly includes a first pad 2 disposed at the upper and lower ends (along the C direction) between adjacent magnets 1, and a second pad 3 disposed at the upper and lower ends (along the C direction) on the far right side of the B direction. Each stainless steel cover 4 has a box-shaped structure. Two stainless steel covers 4 are wrapped one-to-one around the upper and lower sides (along the C direction) of multiple magnets 1 and pad assembly. The inner wall of each stainless steel cover 4 is coated with glue between the inner wall of the corresponding magnet 1 and the outer wall of the pad assembly, so that the magnets, pad assembly and stainless steel cover form an integral module structure.

[0022] The second pad 3 has a pad extension 31 extending outward from the stainless steel cover. When the two magnet modules 100 are axially arranged and assembled, the stainless steel covers 4 of adjacent magnet modules 100 are spaced apart by the pad extension 31 of the second pad 3. Through the special design of the second pad 3, the axial contact of two adjacent stainless steel covers 4 to form a circuit is avoided when the magnet modules are inserted into the magnet slots of the rotor core. Because the metal inside the motor induces an electric potential in the magnetic field, if the stainless steel covers 4 are in direct contact, local voltage may be too high, leading to local breakdown discharge.

[0023] The first pad 2 and the second pad 3 have different dimensions in the B direction. The dimension of the first pad 2 in the B direction is the same as the width of the radial ventilation channel of the rotor core. The dimension of the second pad 3 in the B direction is set such that the axial dimension of the second pad 3 plus the wall thickness of the stainless steel cover 4 equals the width of the radial ventilation channel of the rotor core. In this way, the thickness setting of the second pad 3 in the B direction allows the distance between the two magnets in the two magnet modules 100 after axial alignment and assembly to also be the dimension of the radial ventilation channel of the rotor core.

[0024] The inner wall of the stainless steel cover 4 is adapted to the width of the magnet along direction A, and its dimension along direction B is consistent with the axial arrangement length of the magnet and the pad assembly, thus perfectly encapsulating the magnet and the pad assembly. The height of the stainless steel cover 4 matches the height of the pad assembly, surrounding the magnet 1 and the pad assembly inside the stainless steel cover 4.

[0025] The stainless steel cover 4 has a first fastening structure 41 extending inward on the side wall corresponding to the first pad; the stainless steel cover 4 has a second fastening structure 42 extending inward on the side wall corresponding to the second pad; the distance between the first fastening structure 41 and the second fastening structure 42 and the bottom surface of the stainless steel cover 4 is equal to the height of the corresponding pad, which is used to constrain the movement of each pad in the direction of the magnet height.

[0026] Magnet 1 is a flat, block-shaped structure, aligned along direction B. The cross-sectional shape of a single magnet 1 perpendicular to direction B matches the slot shape of the magnet slots on the rotor core, and the length of each magnet along direction B is consistent with the axial segment length of the rotor core. Each core segment corresponds to one magnet, and the space between two adjacent core segments forms a radial ventilation channel for the rotor core. A ventilation channel width is provided between two adjacent magnets for arranging the first spacer block 2; the dimension of the first spacer block 2 along direction B is the width of the radial ventilation channel for the rotor core. It is recommended to arrange three or four magnets 1 in a single magnet module. Too many magnets will result in an excessively long axial dimension of the module, making dimensional control difficult. Too few magnets will not offer significant advantages over a single magnet.

[0027] The pad assembly (first pad 2 and second pad 3) is made of a non-magnetic, lightweight material, such as epoxy board. The magnet 1, first pad 2, and second pad 3 are identical in size along direction A (the width of the magnet) and their front and rear ends are aligned. The upper and lower end faces of the magnet 1, first pad 2, and second pad 3 along direction C (the height of the magnet) are respectively aligned with the inner wall of the corresponding stainless steel cover 4. This ensures that the stainless steel cover 4 can effectively enclose and constrain the magnet 1 and the corresponding pad.

[0028] Please see Figure 2 , Figure 5 and Figure 6 In the present invention, the magnet module structure of the permanent magnet motor rotor with radial air duct is assembled by pushing the magnet module into the corresponding magnet slot of the rotor core along direction B. Figure 2 The image shows a single section of the rotor core cut along the rotor axis, along with the assembled magnets and spacers. The spaces between the magnets and the core corresponding to each spacer form radial cooling air ducts. Figure 5 Two magnet arrangement methods are provided: one along the rotor radial direction D and the other perpendicular to the rotor radial direction. During motor operation, the pads corresponding to the magnet modules 100 along the rotor radial direction are easily thrown into the air duct by centrifugal force F if they are only wrapped by the edge of the stainless steel cover. By setting corresponding first fastening structure 41 and second fastening structure 42 at each pad with the stainless steel cover 4, it can be further secured to prevent each pad from being thrown out during rotation. Figure 6 The stress on the stainless steel cover was considered when the magnet module reached a speed of 1800 rpm within the rotor core. The maximum stress was no more than 200 MPa, lower than the yield strength of the stainless steel cover. In practice, the adhesive between the magnets and the stainless steel cover, and between the spacers and the magnets, inside the magnet module also provides a certain shear resistance, ensuring a tight and unified overall connection of the magnet module. According to... Figure 6 The results showed that even when the adhesive failed in extreme conditions, the mechanical structure of the stainless steel cover could still ensure the stability of the internal magnets and pads.

[0029] The present invention relates to a permanent magnet motor rotor with radial air ducts and a magnet module structure. The magnets and spacers are fixed together using a stainless steel cover, simplifying the assembly process of the rotor with built-in permanent magnets and radial air ducts. The magnet modules and core can be assembled independently. The modules have fixed specifications for mass assembly and supply. Compared to traditional assembly using magnets as units, the overall process efficiency and reliability of the module and core assembly are improved. The multi-magnet module design, replacing the sequential assembly of single magnets, significantly saves time.

[0030] Please see Figure 7 The stainless steel cover 4 of the magnet module structure protects the magnet during assembly. When the magnet module 100 is assembled into the rotor core 200, the stainless steel cover 4 in the module is in direct contact with the rotor core 200. Even if the assembly tolerance between the magnet module 100 and the rotor core 200 is too small and squeeze occurs, the magnet body will not rub against the rotor core.

[0031] In summary, the magnet module structure of the permanent magnet motor rotor with radial air duct of the present invention, which fixes the magnets and each pad block into a group by a stainless steel cover, can simplify the assembly process of the built-in permanent magnet rotor with radial air duct, improve production efficiency, save time, and prevent the magnets from rubbing against the rotor core.

[0032] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A magnet module structure for a permanent magnet motor rotor with radial air ducts, characterized in that, Includes multiple magnets, a pad assembly, and two stainless steel covers, among which: The multiple magnets are arranged sequentially along the motor axis, with each magnet corresponding to an axial segment of the rotor core. The pad assembly includes a first pad disposed at the upper and lower ends between adjacent magnets, and a second pad disposed at the upper and lower ends at one of the outermost ends of one of the magnet arrangement directions; Each stainless steel cover has a box-shaped structure, and the two stainless steel covers are wrapped around the upper and lower sides of the multiple magnets and pads in a corresponding manner; the inner wall of each stainless steel cover is coated with glue between the inner wall and the outer wall of the corresponding magnet and pad assembly, so that the magnets, pads and stainless steel covers form an integral module structure. The second pad has a pad extension that extends outward from the stainless steel cover. When the two magnet modules are axially arranged and assembled, the stainless steel covers of adjacent magnet modules are spaced apart by the pad extension of the second pad to prevent the stainless steel covers from directly contacting each other.

2. The magnet module structure of a permanent magnet motor rotor with radial air duct according to claim 1, characterized in that, The dimension of the first pad along the motor axis is consistent with the width of the radial ventilation channel of the rotor core; The dimension of the second pad along the motor axis is set as follows: the axial dimension of the second pad plus the wall thickness of the stainless steel cover is equal to the width of the radial ventilation channel of the rotor core.

3. The magnet module structure of a permanent magnet motor rotor with radial air duct according to claim 1, characterized in that, The stainless steel cover has a first fastener structure extending inward at the side wall position corresponding to the first pad block; The stainless steel cover has a second fastener structure extending inward at the side wall position corresponding to the second pad block; The distance between the first and second fastening structures and the bottom surface of the stainless steel cover is equal to the height of the corresponding pad, which is used to constrain the movement of each pad in the direction of the magnet height.

4. The magnet module structure of a permanent magnet motor rotor with radial air duct according to claim 1, characterized in that, The pad assembly is made of a non-magnetic lightweight material, which is an epoxy board.

5. The magnet module structure of a permanent magnet motor rotor with radial air duct according to claim 1, characterized in that, The magnet has a flat block structure, and its cross-sectional shape perpendicular to the motor axis matches the slot shape of the magnet slot on the rotor core. The length of each magnet along the motor axis is consistent with the axial segment length of the rotor core.

6. The magnet module structure of a permanent magnet motor rotor with radial air duct according to claim 1, characterized in that, The magnet, the first pad, and the second pad have the same dimensions along the width direction of the magnet and their front and rear ends are aligned. The upper and lower end faces of the magnet, the first pad, and the second pad along the height direction of the magnet are respectively aligned with the inner wall of the corresponding stainless steel cover.

7. The magnet module structure of a permanent magnet motor rotor with radial air duct according to claim 1, characterized in that, The magnet module is assembled and pushed into the magnet slot corresponding to the rotor core along the motor axis; the space corresponding to the first pad and the second pad constitutes part of the radial ventilation channel of the rotor core.

8. The magnet module structure of a permanent magnet motor rotor with radial air duct according to claim 1, characterized in that, When the rotor core rotates at 1800 rpm, the maximum stress of the stainless steel cover does not exceed 200 MPa, which is lower than the yield strength of the stainless steel cover.

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