Stator or rotor for radial gap motor based on layered soft magnetic ribbons

Abstract

The purpose of the present invention is to provide a stator or a rotor for a radial gap motor that can be produced with little discarding of high-performance materials, with good work efficiency, at low cost, without press-punching, and without a step in which soft magnetic ribbons are stacked one at a time.　In the present invention, deformation processing is applied to wound-up layered soft magnetic ribbons to manufacture a stator or a rotor for a radial gap motor in which a plurality of magnetic components are disposed so as to be connected in a single continuous circuit, the magnetic components configured so that a yoke and teeth adjacent to both ends of the yoke form a single body.

Description

Stator or rotor for radial gap motor using laminated soft magnetic ribbon

[0001] The present invention relates to a radial gap stator or rotor manufactured by processing a laminated soft magnetic ribbon.

[0002] Motor losses include copper loss, iron loss, and mechanical loss. Iron loss depends on the soft magnetic material used and is the sum of hysteresis loss and eddy current loss. Typical motors use soft magnetic steel sheets as the core. Soft magnetic materials include high-performance materials such as thin amorphous and nanocrystalline materials, which have higher magnetic permeability and lower hysteresis loss than magnetic steel sheets. These materials are extremely thin, measuring approximately 0.02 mm, and exhibit low eddy current loss. Therefore, amorphous and nanocrystalline ribbons can reduce iron loss to about one-tenth of that of magnetic steel sheets. Commercially available amorphous and nanocrystalline soft magnetic ribbons (Finemet®) are rapidly cooled from a molten state to produce amorphous ribbons. Even nanocrystalline ribbons are hard, strong, and tough in the amorphous state before crystallization. They can be bent 180° without breaking and can be handled in the same way as conventional amorphous ribbons. However, nanocrystalline materials that have been crystallized to have good soft magnetic properties are brittle and have low rigidity, which poses many manufacturing challenges, making it difficult to create motors with good energy efficiency and low loss.

[0003] More than 40 years have passed since the development and mass production of transformers using amorphous ribbons. However, the only example of a mass-produced, commercially available motor using amorphous ribbons is one in which amorphous ribbons are cut, laminated, and used in the core of an axial gap stator (Non-Patent Document 1). The stator is fabricated using only the iron core portion, which generates the magnetic field, without a yoke, and the stator is sandwiched between rotors on both sides via a gap. Non-Patent Document 2 also reports the prototype of a radial gap motor that uses a rotor with a higher-performance magnet than the above motor, a stator with laminated amorphous ribbons for the teeth, and an electromagnetic steel sheet for the back core. However, the yoke and teeth that make up the stator described in Non-Patent Document 2 are prepared as separate components and connected later, which increases the number of manufacturing steps and does not reduce manufacturing costs.

[0004] The process of creating a stator by stamping out electromagnetic steel sheets requires high power costs, material loss, and further processes of lamination and assembly to create the stator. Block cores, toroidal cores, and cut cores for transformers made of laminated amorphous and nanocrystalline soft magnetic materials are sold, but motor prototypes are simply made by cutting soft magnetic materials made of laminated amorphous and nanocrystalline ribbons into the shape of a stator using wire cutting. Based on preconceived notions, only a few radial gap motors with low iron loss have been prototyped using the stamping method, using amorphous and nanocrystalline ribbons, which have high hardness.

[0005] Ordinary shaft-rotating motors can be classified into two types: axial gap and radial gap, but currently radial gap motors account for an overwhelming majority of production. Axial gap motors are not widely used because a system for mass-producing a wide variety of motors at low cost, like radial gap motors, has not been established. Therefore, in this application, we focused on and examined radial gap motors, aiming to find technology that can be manufactured at low cost.

[0006] Current radial gap motors require a process in which teeth and yokes are press-punched into a circular shape from soft magnetic ribbon, which are then accumulated, stacked, and assembled to form a stator. However, press-punching amorphous and nanocrystalline ribbons, which are thinner than electromagnetic steel sheets, requires many punching operations.

[0007] In Patent Document 1, amorphous alloy ribbons are thin and hard, and conventional press punching methods have a short die life, making them unsuitable for producing stators. However, by revising the design of the punching die, it has become possible to press punch amorphous ribbons in the same way as conventional electromagnetic steel sheets. As a result, it has become possible to produce stators from amorphous ribbons using the same techniques as electromagnetic steel sheets. However, press punching still results in a significant amount of material loss other than punching, and requires a process of stacking a large number of punched ribbons.

[0008] Patent Document 2 discloses a radial gap motor equipped with a rotor having a coil wound around a stator core manufactured by winding and laminating an amorphous alloy ribbon, and magnets arranged opposite the end faces of the multiple stator cores. The multiple stator cores are arranged circumferentially opposite the rotor with gaps between them.

[0009] As described above, attempts have been made to improve the conventional method of press-punching and laminating, but the problems of long working processes and high manufacturing costs have not been solved. There is a need for a stator or rotor for a radial gap motor that can be manufactured without going through the conventional processes of press-punching and laminating soft magnetic ribbons one by one.

[0010] Amorphous soft magnetic material is hard and difficult to process, so if a magnetic field is applied perpendicular to the surface of an amorphous soft magnetic ribbon that is wound without going through the lamination process, the demagnetizing field is large and the ribbon cannot be used. A method is being sought to reduce the demagnetizing field by applying a magnetic field parallel to the multilayered surface of the multilayered winding. If the demagnetizing field is small, the attenuation of the magnetic field generated by the coil can be avoided, making it possible to use the ribbon as a stator or rotor.

[0011] Furthermore, conventional stators and rotors for radial gap motors did not fully consider the torque performance that causes the rotor to rotate. This is because the magnetic field distribution from the tips of the teeth had not been considered. Therefore, there was a demand for stators and rotors with improved torque performance that also took into account magnetic field distribution and magnetic field control.

[0012] Japanese Patent No. 7129048 Japanese Patent Application Laid-Open No. 2018-29420

[0013] "Developing a motor using amorphous metals," [online], Hitachi, Ltd., [Retrieved June 1, 2024], Internet <https: / / www.hitachi.co.jp / rd / sc / story / amorphous / index.html>; "Developing high-efficiency technology for motors using amorphous metals," [online], October 24, 2018, Hitachi Metals, Ltd., [Retrieved February 1, 2024], Internet <URL:https: / / www.proterial.com / press / backnumber / 2018 / n1024.html>

[0014] To provide a stator or rotor for a radial gap motor having good magnetic properties and high performance, which can be manufactured at low cost through a work process with good material usage efficiency and work efficiency, without going through a process of press-cutting and laminating each thin ribbon sheet, or cutting out a laminated thick film body into the shape of a magnetic core by electric discharge machining or the like.

[0015] Another object of the present invention is to provide a stator or rotor for a radial gap motor that controls the magnetic field from the tips of the teeth and improves the torque performance that provides the force that rotates the rotor.

[0016] The stator or rotor for a radial gap motor according to the present invention is a stator or rotor for a radial gap motor in which a plurality of magnetic components, each of which is an integrated yoke and teeth adjacent to both ends of the yoke, are connected in a continuous circle around the yoke, and the magnetic components are formed by deforming a wound laminated soft magnetic ribbon, and the lamination direction of the laminated soft magnetic ribbon in the yoke after arrangement is the radial direction of the radial gap motor, the lamination direction of the laminated soft magnetic ribbon in the teeth is perpendicular to the rotation axis of the radial gap motor, and the direction of the magnetic field generated in the yoke and the teeth by winding wire around the teeth and passing a current therethrough is the longitudinal direction of the laminated soft magnetic ribbon.

[0017] A rotor for a reluctance motor according to the present invention is a rotor for a reluctance motor in which a plurality of magnetic components, each of which is an integral part of a yoke and teeth adjacent to both ends of the yoke, are connected in a continuous circle, and the magnetic components are formed by deforming a wound laminated soft magnetic ribbon, and after arrangement, the lamination direction of the laminated soft magnetic ribbon in the yoke is the radial direction of the radial gap motor, and the lamination direction of the laminated soft magnetic ribbon in the teeth is a direction perpendicular to the rotation axis of the radial gap motor, and the teeth are used without windings.

[0018] According to the present invention, a laminated soft magnetic ribbon formed by winding a soft magnetic ribbon is processed to arrange a plurality of magnetic components each having a yoke integrated with teeth adjacent to both ends thereof, thereby providing a stator or rotor for a radial gap motor that is more productive, low-cost, energy-efficient, and high-performance than conventional methods. Also, by cutting and bending the tips of the teeth to control the magnetic field from the teeth, a stator or rotor for a radial gap motor with improved torque performance can be provided.

[0019] FIG. 1 is a diagram showing the cross-sectional shape of a wound laminated soft magnetic ribbon. FIG. 2 is a diagram showing the cross-sectional shape of the laminated soft magnetic ribbon after deformation. FIG. 3 is a diagram showing a stator for a radial gap motor according to Example 1. FIG. 4 is a diagram showing the shape of teeth tips in which only the outer periphery of a laminated soft magnetic ribbon is cut according to Example 2. FIG. 5 is a diagram showing a stator for a radial gap motor according to Example 2. FIG. 6 is a diagram showing the shape of teeth tips in which all layers of a laminated soft magnetic ribbon are cut and the right half has its tip further bent. FIG. 7 is a diagram showing a stator for a radial gap motor according to Example 3.

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail by way of examples with reference to the accompanying drawings.

[0021] FIGS. 1, 2, and 3 are diagrams showing the process of manufacturing a stator 1 for a radial gap motor according to the first embodiment. A soft magnetic ribbon is wound multiple times around a cylindrical mold to form a laminated soft magnetic ribbon 2. An amorphous alloy ribbon, a nanocrystalline alloy ribbon, or the like is used as the soft magnetic ribbon. The cross-sectional shape of the cylindrical laminated soft magnetic ribbon 2 after being removed from the mold is as shown in FIG. 1. Note that a cylindrical mold is not necessarily required as long as the ribbon can be wound into a cylindrical shape. While FIG. 1 shows the laminated soft magnetic ribbon 2 made of three layers, in practice, a multi-layer laminate of, for example, about 1,000 layers is used. From the state shown in FIG. 1, forces are applied from three directions at 120-degree intervals around the circumference to deform the stator, resulting in the cross-sectional shape shown in FIG. 2. In FIG. 2, three magnetic components 5, each consisting of a yoke 3 and teeth 4 adjacent to both ends, are considered to be connected and arranged continuously around the circumference. In this case, the three magnetic components 5 are arranged integrally without being cut around the circumference. In the present invention, the back yoke, which is the part of the stator 1 or rotor that directs magnetic flux from one tooth 4 to the adjacent tooth 4, is referred to as the yoke 3. The stator 1 shown in FIG. 3 , which is fabricated with a winding 6 spanning two adjacent teeth 4, is used as a three-slot stator 1 for a brushless DC motor. If brushes are attached to the stator 1 shown in FIG. 3 , it can also be used as a rotor for a brushed DC motor. While FIG. 3 shows an example consisting of three magnetic components 5, i.e., three slots, this embodiment can be applied to any type of stator 1 or rotor for a radial gap motor by distributing one circumference equiangularly and configuring any number of magnetic components and slots, such as four or six. This embodiment can be used for any of the outer stator 1, outer rotor, inner stator 1, and inner rotor of a radial gap motor. Furthermore, this embodiment can be applied not only to radial gap motors but also to generators.

[0022] Furthermore, the rotor shown in FIG. 2 without the windings 6 can be used as a rotor for a switched reluctance motor or a synchronous reluctance motor by appropriately increasing the number of magnetic components 5 to four or more. In this case, it can also be used for both an outer rotor and an inner rotor. After arrangement, the lamination direction of the laminated soft magnetic ribbons 2 in the yoke 3 is the radial direction of the radial gap motor, and the lamination direction of the laminated soft magnetic ribbons 2 in the teeth 4 is perpendicular to the rotation axis of the radial gap motor. This lamination direction arrangement generates a magnetic field in the direction of the easy axis of magnetization, improving the characteristics of the stator 1 or rotor. Furthermore, by winding the windings 6 around the teeth 4 and passing current through them, the magnetic field generated in the yoke 3 and the teeth 4 is oriented in the longitudinal direction of the laminated soft magnetic ribbons 2. The magnetic field direction is aligned with the easy axis of magnetization, again resulting in improved characteristics of the stator 1 or rotor. This relationship between the lamination direction and the magnetic field cannot be achieved in an axial gap motor, but is achieved by applying this embodiment to a radial gap motor.

[0023] First, as in Example 1, the cross-sectional shape of the cylindrical laminated soft magnetic ribbon 2 shown in FIG. 1 is deformed from three directions to obtain the cross-sectional shape shown in FIG. 2. This results in three magnetic components 5, each consisting of a yoke 3 and teeth 4 adjacent to both ends of the yoke 3, being arranged in a single unit around the circumference without being cut. From this point, only the outer periphery of the laminated soft magnetic ribbon 2 is cut along the rotational axis of the radial gap motor at the boundary between two adjacent teeth 4. The shape of the tip of the tooth 4 is the cut surface of each cut layer, as shown in FIG. 4. Including the inner periphery of the tip of both teeth 4 that is not cut, the three magnetic components 5 remain in a single unit around the circumference. The stator 1 shown in FIG. 5, which is fabricated with a winding 6 spanning two adjacent teeth 4, is used as a three-slot stator 1 for a brushless DC motor. If brushes are attached to the stator 1 shown in FIG. 5, it can also be used as a rotor for a brushed DC motor. While FIG. 5 shows an example consisting of three magnetic components 5, i.e., three slots, this embodiment can be applied to any type of stator 1 or rotor for a radial gap motor, with any number of magnetic components 5 and slots. This embodiment can be used for any of the outer stator 1, outer rotor, inner stator 1, and inner rotor of a radial gap motor. Furthermore, this embodiment can be applied not only to radial gap motors but also to generators as is.

[0024] Furthermore, when the cross-sectional shape of FIG. 5 is restored to its unwinded state, the number of magnetic components can be increased to four or more, allowing the rotor to be used as a switched reluctance motor or a synchronous reluctance motor. In this case, the rotor can be used as both an outer rotor and an inner rotor. The lamination direction of the laminated soft magnetic ribbons 2 in the yoke 3 after arrangement is the radial direction of the radial gap motor, and the lamination direction of the laminated soft magnetic ribbons 2 in the teeth 4 is perpendicular to the rotation axis of the radial gap motor. This lamination direction arrangement generates a magnetic field in the direction of the easy axis of magnetization, improving the characteristics of the stator 1 or rotor. Furthermore, by winding the windings 6 around the teeth 4 and passing current through them, the magnetic field generated in the yoke 3 and the teeth 4 is oriented in the longitudinal direction of the laminated soft magnetic ribbons 2. The magnetic field direction is aligned with the easy axis of magnetization, again resulting in improved characteristics of the stator 1 or rotor. The magnetic field generated in the teeth 4 by passing current through the windings 6 leaks out from the tips of the teeth 4 shown in FIG. 5, but the cutting of the outer periphery of the tips creates an external magnetic field gradient. If each cut layer is bent outward in both directions, the magnetic field gradient leaking from the teeth 4 becomes even larger. The magnetic field gradient leaking from the teeth 4 of the stator 1 becomes a force that rotates the rotor of the radial gap motor, improving torque performance. Magnetic field control by processing the tips of the teeth according to this embodiment can improve torque performance not only when applied to the stator 1 but also when applied to the rotor.

[0025] Three magnetic components 5, each consisting of a yoke 3 with a cross-sectional shape shown in FIG. 2 and teeth 4 adjacent to both ends, are arranged in a single, uncut configuration. All layers of the laminated soft magnetic ribbon 2 are then cut along the rotational axis of the radial gap motor at the boundary between the tips of the convex portions of two adjacent teeth 4. The three magnetic components are no longer arranged in a single, uncut configuration, but are still connected continuously around the circumference. FIG. 6 shows the state in which the six-layer laminated soft magnetic ribbon 2 has been cut along the boundary between the left and right teeth 4. The six layers on the left are in the state immediately after cutting, with the outer periphery of the laminated soft magnetic ribbon 2 higher and the inner periphery lower at the cut location. The six layers on the right are shown with their tips bent outward after cutting. In practice, the six layers on the left are also bent outward. Since the folding of each layer creates spaces between the layers, it is recommended to fill them with a non-magnetic material such as plastic or adhesive to secure them in place. Figure 6 shows the tip of a tooth 4 cut on a plane determined by the rotational axis direction and the radial direction of the radial gap motor. However, the tip of the tooth 4 facing the rotor can also be shaped by cutting the entire layer on a plane determined by the rotational axis direction and the azimuth direction of the radial gap motor, flattening the tip, forming a fan shape, or crushing and cutting the tip. Figure 7, which is made by winding across two adjacent teeth 4, is used as a three-slot stator 1 for a brushless DC motor. If brushes are attached to Figure 7, it can also be used as a rotor for a brushed DC motor. While Figure 7 shows an example consisting of three magnetic components, i.e., three slots, this embodiment can be applied to any type of stator 1 or rotor for a radial gap motor, configured with any number of magnetic components and slots. This embodiment can be used for the outer stator 1, outer rotor, inner stator 1, and inner rotor of a radial gap motor.

[0026] After arrangement, the lamination direction of the laminated soft magnetic ribbons 2 in the yoke 3 is the radial direction of the radial gap motor, and the lamination direction of the laminated soft magnetic ribbons 2 in the teeth 4 is perpendicular to the rotation axis of the radial gap motor. This lamination direction arrangement generates a magnetic field in the direction of the easy axis of magnetization, improving the characteristics of the stator 1 or rotor. Furthermore, by winding the teeth 4 and passing current through them, the direction of the magnetic field generated in the yoke 3 and teeth 4 is the length direction of the laminated soft magnetic ribbons 2. Since the magnetic field direction is in the direction of the easy axis of magnetization, this also results in improving the characteristics of the stator 1 or rotor. The magnetic field generated in the teeth 4 by passing current through the windings leaks out from the teeth 4, and a large magnetic field gradient is generated externally due to the effect of the bending of each layer, and the stator 1 acts as a stator with the force to rotate the rotor of the radial gap motor. The magnetic field gradient can be further increased by gradually increasing the bending angle from the center to the outside. The stator 1 or rotor according to the third embodiment does not need to start from a cylindrical laminated soft magnetic ribbon 2; instead, laminated soft magnetic ribbon 2 of any shape may be cut and then processed and deformed to form a magnetic component 5 in which a yoke 3 and teeth 4 adjacent to both ends of the yoke 3 are integrated, and multiple magnetic components 5 may be connected continuously around the circumference. In this case, there is no difference in height between the outside and center of the cut surface in a diagram corresponding to FIG. 6 , but by gradually increasing the bending angle from the center to the outside, a magnetic field gradient leaking from the teeth 4 can be obtained. This results in a stator 1 with improved torque performance. Magnetic field control by processing the tooth tips according to this embodiment can improve torque performance not only when applied to the stator 1 but also when applied to a rotor.

[0027] According to the present invention, a magnetic component in which a yoke and teeth adjacent to both ends thereof are integrated can be processed from a laminated soft magnetic ribbon formed by winding a soft magnetic ribbon, which reduces the number of manufacturing steps and significantly reduces material waste compared to the conventional method of manufacturing a stator or rotor by punching out, stacking, and laminating each piece. This has great industrial applicability as it enables the use of motors and generators that are more productive, lower cost, and more energy efficient than conventional methods.

[0028] REFERENCE SIGNS LIST 1 Stator for radial gap motor 2 Laminated soft magnetic ribbon 3 Yoke 4 Teeth 5 Magnetic component 6 Winding

Claims

1. A stator or rotor for a radial gap motor in which a plurality of magnetic components, each consisting of a yoke and teeth adjacent to both ends of the yoke integrated together, are connected in a continuous circle, the magnetic components being formed by deforming a wound laminated soft magnetic ribbon, the lamination direction of the laminated soft magnetic ribbon in the yoke after arrangement is the radial direction of the radial gap motor, the lamination direction of the laminated soft magnetic ribbon in the teeth is perpendicular to the rotation axis of the radial gap motor, and the direction of the magnetic field generated in the yoke and the teeth by winding wire and passing current through the teeth is the longitudinal direction of the laminated soft magnetic ribbon.

2. A rotor for a reluctance motor in which a plurality of magnetic components, each consisting of a yoke and teeth adjacent to both ends of the yoke integrated together, are connected in a continuous circle, the magnetic components being formed by deforming a wound laminated soft magnetic ribbon, the lamination direction of the laminated soft magnetic ribbon in the yoke after arrangement being the radial direction of the radial gap motor, the lamination direction of the laminated soft magnetic ribbon in the teeth being perpendicular to the rotation axis of the radial gap motor, and the rotor for a reluctance motor being used without windings on the teeth.

3. A stator or rotor for a radial gap motor as described in claim 1, characterized in that the magnetic components are formed by deforming multiple locations around one circumference of the cylindrical laminated soft magnetic ribbon that has been wound and laminated, and the multiple magnetic components are arranged integrally around the circumference without being cut.

4. A rotor for a reluctance motor as described in claim 2, characterized in that the magnetic components are formed by deforming multiple locations around one circumference of the cylindrical laminated soft magnetic ribbon that has been wound and laminated, and the multiple magnetic components are arranged integrally around the circumference without being cut.

5. A stator or rotor for a radial gap motor as described in claim 1, characterized in that the magnetic components are formed by deforming multiple locations around one circumference of the cylindrical laminated soft magnetic ribbon that has been wound and laminated, the outer periphery of the tip of the laminated soft magnetic ribbon of the multiple teeth is cut in the direction of the rotation axis of the radial gap motor, and the multiple magnetic components, including the inner periphery of the tip of the teeth that is not cut, are arranged integrally without being cut around the entire circumference.

6. A stator or rotor for a radial gap motor as described in claim 5, characterized in that the laminated soft magnetic ribbon at the outer periphery of the cut tooth tip is bent in both outward directions for each layer, generating a magnetic field gradient leaking from the tooth.

7. A rotor for a reluctance motor as described in claim 2, characterized in that the magnetic components are formed by deforming multiple locations around one circumference of a cylindrical laminated soft magnetic ribbon that has been wound and laminated, the outer periphery of the tip of the laminated soft magnetic ribbon of the multiple teeth is cut in the direction of the rotation axis of the reluctance motor, and the multiple magnetic components, including the inner periphery of the tip of the teeth that is not cut, are arranged integrally without being cut around the entire circumference.

8. A stator or rotor for a radial gap motor as described in claim 1, characterized in that the magnetic components in which the tip portions of the teeth are cut across all layers of the laminated soft magnetic ribbon are connected continuously around the circumference, and the laminated soft magnetic ribbon at the tip portions of the teeth is bent in both outward directions for each layer, generating a magnetic field gradient that leaks out from the teeth.

9. The laminated soft magnetic ribbons at the tip of the teeth are folded outward on both sides of the tip of the teeth for each layer, and the spaces created by the folding are filled with a non-magnetic material and fixed.

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