JP2008011643A - Core and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a core that is used for a rotor of an electric motor or a stator of the electric motor and capable of improving strength; and to provide its manufacturing method, the rotor of the electric motor, the stator of the electric motor, and the electric motor using the core. <P>SOLUTION: The core 10 is used for the rotor of the electric motor or the stator of the electric motor, and comprises a core formed body 12 which is made by forming by compression magnetic particles having an insulating thin film on the surface of metallic grains containing a ferromagnetic element, and an amorphous thin film 14. The amorphous thin film is formed on the surface of the stress concentrated portion 12b of the core formed body. The core manufacturing method has a step of raising the temperature of the core formed body before spraying the amorphous metallic powder, when amorphous metallic powder is sprayed and arranged in a layer to form the amorphous thin film on the core formed body. The rotor of the electric motor, the stator of the electric motor, and the electric motor are the ones using the core. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a core and a manufacturing method thereof, and more particularly to a core used for a rotor for an electric motor or a stator for an electric motor, a manufacturing method thereof, an electric motor rotor using the same, an electric motor stator, and an electric motor.

Conventionally, in an electric motor having a rotor held rotatably, when a centrifugal force accompanying the operation of the electric motor is applied to a magnet built in a magnet hole of the rotor core constituting the rotor, the periphery of the magnet of the rotor core It is known that stress concentration occurs. In order to disperse the stress concentration portion, it has been proposed to provide an arc portion on the outer periphery of the magnet of the rotor core (see Patent Document 1).
JP 2001-16809 A

  However, the rotor described in Patent Document 1 has a problem in that the strength tends to decrease because the thin portion between the magnet hole and the outer periphery of the rotor is narrowed.

  The present invention has been made in view of such problems of the prior art, and the object thereof is a core that can be used for a rotor for an electric motor or a stator for an electric motor and can improve strength, a manufacturing method thereof, Another object of the present invention is to provide a motor rotor, a motor stator and a motor using the same.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have found that a stress concentration portion of a core molded body formed by compression molding magnetic grains having an insulating thin film on the surface of metal grains containing a ferromagnetic element. The present inventors have found that the above object can be achieved by forming an amorphous thin film on the surface of the substrate, and have completed the present invention.

  That is, the core of the present invention is used in a rotor for an electric motor or a stator for an electric motor, and is formed by compression molding magnetic particles having an insulating thin film on the surface of metal particles containing a ferromagnetic element, and an amorphous thin film. The amorphous thin film is formed on the surface of the stress concentration portion of the core molded body.

  Further, a preferred embodiment of the core of the present invention is a core molded body that is used for a rotor for an electric motor or a stator for an electric motor, and is formed by compression molding magnetic particles having an insulating thin film on the surface of metal particles containing a ferromagnetic element. And an amorphous thin film containing a ferromagnetic element, and the amorphous thin film is formed on the surface of the stress concentration portion of the core molded body.

  Furthermore, another preferred embodiment of the core of the present invention is a core molding formed by compression molding magnetic particles having an insulating thin film on the surface of metal particles containing a ferromagnetic element, which are used for a rotor for an electric motor or a stator for an electric motor. And an amorphous thin film containing a nonmagnetic element, wherein the amorphous thin film is formed on the surface of the stress concentration portion of the core molded body.

  Furthermore, the core manufacturing method of the present invention is a method of manufacturing the above-described core of the present invention, in which an amorphous metal powder is sprayed on a core molded body and arranged in layers to form an amorphous thin film. The temperature of the core molded body is raised before the injection of the amorphous metal powder.

  Further, the motor rotor of the present invention is a motor rotor using the core of the present invention, and includes a core used for the motor rotor and a magnet attached to the inside and / or the surface of the core. It is characterized by having.

  Furthermore, the stator for an electric motor of the present invention is an electric motor stator using the core of the present invention, and includes a core used for the stator for the electric motor and a coil wound around the core. Features.

Furthermore, the electric motor of the present invention includes at least the electric motor rotor of the present invention or the electric motor stator of the present invention.
Such an electric motor can be suitably used as an electric motor for driving an electric vehicle or a hybrid vehicle.

  According to the present invention, for example, an amorphous thin film is formed on the surface of a stress concentration portion of a core molded body formed by compression molding magnetic grains having an insulating thin film on the surface of metal particles containing a ferromagnetic element. It is possible to provide a core that can be used for a rotor for an electric motor or a stator for an electric motor and that can improve strength, a method for manufacturing the same, a rotor for an electric motor using the same, a stator for an electric motor, and an electric motor.

Hereinafter, the core of the present invention will be described in detail. In the present specification and claims, “%” for content, concentration, etc. represents mass percentage unless otherwise specified.
As described above, the core of the present invention is used in a rotor for an electric motor or a stator for an electric motor, and a core molded body formed by compression molding magnetic particles having an insulating thin film on the surface of a metal particle containing a ferromagnetic element; And an amorphous thin film.
And this amorphous thin film is formed in the surface of the stress concentration part of this core molded object.
By setting it as such a structure, an amorphous thin film may have high yield strength, it becomes difficult to generate a crack, and intensity | strength improves.
In addition, the amorphous metal thin film often has a higher specific resistance than the crystalline metal thin film, and the secondary effect that the loss due to the eddy current generated when the magnetic flux passes can be suppressed. It is done.
In the scope of the present invention, the core used for the stator for the motor (motor stator core) includes not only an integrated stator core but also a plurality of pieces, which are appropriately combined or Is incorporated in the exterior of an electric motor or the like and functions as a stator core for an electric motor, one of the stator core pieces is also included.
Moreover, the core (motor rotor core) used for the motor rotor usually has a magnet mounting portion that can mount a magnet on one or both of the surface and the inside of the core.

  In the present invention, the amorphous thin film of the core can be formed by, for example, injecting amorphous metal powder onto the core compact and arranging it in layers, but the method for forming the amorphous thin film is not limited to this. Absent.

Here, the formation mechanism of the amorphous thin film estimated at the present time in the formation method mentioned above is demonstrated.
At the same time as the injected amorphous powder collides with the thin film forming body, the kinetic energy possessed by the amorphous powder is instantaneously converted into thermal energy, and the amorphous powder itself is heated.
When the temperature of the amorphous powder reaches the supercooling temperature range of the amorphous powder due to the heating, the amorphous powder exhibits characteristics close to Newtonian fluid, and is thinly extended on the surface of the thin film forming body to form a thin film. .
At that time, thermal energy is released to the thin film forming body and rapidly cooled, so that the formed thin film has an amorphous state.

Assuming such a formation mechanism, it is presumed that an amorphous thin film is formed even when the spraying speed is low when the particle size of the amorphous powder is small.
That is, from the relationship between the internal energy and surface energy that the amorphous powder has, the particle size is reduced, so that the ratio of the surface area to the volume of the powder is increased, and the amorphous powder becomes active. In such a state, the temperature of the amorphous powder easily rises even with a small kinetic energy.
FIG. 1 is a graph showing the relationship between the particle size of amorphous powder and the minimum injection speed of amorphous powder on which an amorphous thin film is formed. An amorphous thin film can be formed by processing in the region above the curve drawn in the graph (region faster than the minimum injection speed).

Furthermore, in this invention, the amorphous metal powder used when forming the amorphous thin film which a core has is following Formula (1).
ΔTx = Tx−Tg (1)
The temperature interval ΔTx of the supercooled liquid region represented by (Tx in the formula represents the crystallization start temperature and Tg represents the glass transition temperature) is preferably 20K or more, more preferably 35K or more, More preferably, it is 45K or more.
It is preferable to use an amorphous metal powder having a temperature interval ΔTx of the supercooled liquid region of 20K or more because the adhesion rate of the powder is improved.

Further, in the present invention, it is desirable that the amorphous thin film contains a ferromagnetic element from the viewpoint of excellent magnetic properties such as saturation magnetic flux density. As such a ferromagnetic element, for example, iron (Fe ), Cobalt (Co), nickel (Ni), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), and the like.
In the present invention, it is more preferable that Fe, Ni, and Co are contained in the amorphous thin film singly or in combination, because of excellent magnetic properties such as saturation magnetic flux density and magnetic permeability, It is further desirable that one of these or a combination thereof is the main component.
The “main component in the amorphous thin film” means an element having the largest content in the amorphous thin film, and can be appropriately adjusted by adjusting the composition of the amorphous metal powder when forming the amorphous thin film.
For example, such an amorphous metal thin film contains iron (Fe), gallium (Ga), phosphorus (P), carbon (C), boron (B), silicon (Si), and the like, and is mainly composed of Fe. Those containing nickel (Ni), zirconium (Zr), boron (B), etc. and containing Ni as the main component, cobalt (Co), iron (Fe), Nb (niobium) and boron (B) And those containing Co as the main component.

  Further, in the present invention, it is desirable that the amorphous thin film contains a nonmagnetic element from the viewpoint of suppressing the leakage magnetic flux on the side surface in the magnetization direction of the magnet attached to the core, and as such a nonmagnetic element, Typical examples include titanium (Ti), copper (Cu), and magnesium (Mg).

Furthermore, as will be described in detail later, the stress concentration portion that forms the amorphous thin film on the surface is not only different depending on the shape of the core used in the motor rotor or the motor stator, but there may be a plurality of such portions. In such a case, by appropriately selecting the above-mentioned elements contained in the amorphous thin film and setting the magnetic characteristics of the amorphous thin film, the strength can be further improved, and the limit rotational speed of the motor can be increased. It is also possible to improve the performance of the electric motor, such as by improving it.
For example, when there are a plurality of stress concentration portions, an amorphous thin film having different magnetic characteristics may be formed for each part, or an amorphous thin film having different magnetic characteristics may be laminated on the same part.

On the other hand, in the present invention, Fe, Ni, Co and the like can be mentioned as suitable examples of the ferromagnetic element contained in the metal particles constituting the core molded body. It is desirable that these are contained singly or in combination, from the viewpoint of magnetic properties and the like, and it is more preferable that one of them or a combination thereof is a main component.
Here, “the main component in the core molded body” means that the content in the core molded body is 50% or more, and the content is, for example, a magnetic powder that becomes magnetic particles when forming the core molded body The composition can be adjusted as appropriate by adjusting the composition of the metal powder, specifically, the composition of the metal powder to be the metal particles, the thickness of the insulating thin film formed on the surface, and the like.

In the present invention, the metal particles constituting the core molded body may have a crystal structure as a main phase or an amorphous structure (amorphous state portion) as a main phase. Good.
For example, in the case where the main phase is an amorphous state portion, the material of the core molded body and the material of the thin film formed on the stress concentration portion of the core molded body are in the same amorphous state. Therefore, for example, when the temperature rises, the linear expansion coefficient can be approximated or matched when the temperature rises, and the generation of stress can be suppressed in advance. The strength can be improved as compared with the structure having a main phase.

And in this invention, in the metal grain which comprises a core molded object and has an amorphous structure (amorphous state part) as a main phase, following Formula (1)
ΔTx = Tx−Tg (1)
The temperature interval ΔTx of the supercooled liquid region represented by (Tx in the formula represents the crystallization start temperature and Tg represents the glass transition temperature) is preferably 20K or more, and more preferably 35K or more.

Next, the manufacturing method of the core of this invention is demonstrated in detail.
As described above, the core manufacturing method of the present invention is a method of manufacturing the above-described core of the present invention, in which an amorphous metal powder is sprayed on a core molded body and arranged in layers to form an amorphous thin film. In this case, the temperature of the core molded body is raised before the injection of the amorphous metal powder.
By setting it as such a structure, the thermal stress which can generate | occur | produce between a core molded object and an amorphous thin film can be reduced.
Moreover, since the amount of kinetic energy of the injected amorphous metal powder can be small, the amorphous thin film can be formed on the surface of the core molded body under mild conditions by reducing the injection speed.
In addition, the core of this invention is not necessarily limited to what was produced by such a manufacturing method.

Next, the motor rotor of the present invention will be described in detail.
As described above, the rotor for an electric motor according to the present invention uses the core according to the present invention, and the core used for the rotor for the electric motor (the rotor core for the electric motor) and any one of the inside and the surface of the core, or And magnets mounted on both sides.
By setting it as such a structure, the electric motor using this becomes what can be rotated to high rotation speed.
In addition, as a magnet with which magnet mounting parts, such as a magnet hole of the rotor core for electric motors, are mounted, magnets, such as neodymium-iron-boron (Nd-Fe-B) and samarium-cobalt (Sm-Co), are used, for example. In particular, Nd—Fe—B can be preferably used from the viewpoint of power density, but is not necessarily limited thereto.

Next, the electric motor stator of the present invention will be described in detail.
As described above, the stator for an electric motor of the present invention uses the core of the present invention, and the core used for the stator for the electric motor (the stator core for the electric motor), the coil wound around the core, It is equipped with.
By setting it as such a structure, the electric motor using this becomes what can be rotated to high rotation speed.
In addition, as a coil wound around the stator core for an electric motor, it is preferable to use a wire such as a polyimide coated electric wire, for example, and it is generally used by being wound around a salient pole portion of the stator core for an electric motor. However, it is not necessarily limited to this.

Next, the electric motor of the present invention will be described in detail.
As described above, the electric motor of the present invention includes at least the motor rotor or the motor stator of the present invention.
Thus, by providing one or preferably both of the motor rotor and the motor stator of the present invention, the motor can be rotated to a high rotational speed.

  In addition, the electric motor of the present invention is not particularly limited as its application, but since the torque can be improved and the acceleration performance can be improved by increasing the driving force, the electric motor for driving an electric vehicle or a hybrid vehicle can be used. Can be suitably used.

  Hereinafter, although several examples are described in more detail about a core of the present invention and its manufacturing method based on a drawing, the present invention is not limited to these examples.

(Example 1)
FIG. 2 is a perspective view of a core (an electric motor rotor core) used in the electric motor rotor according to the first embodiment.
As shown in the figure, the rotor core 10 for an electric motor includes a plurality of magnet holes 12a for inserting permanent magnets (not shown) and mounting them inside.

FIG. 3A is an explanatory view of a part of the rotor for an electric motor in which a permanent magnet is inserted into the magnet hole of the electric motor rotor core according to the conventional example and mounted therein.
As shown in FIG. 2A, the conventional rotor core 50 for an electric motor rotates when incorporated in the electric motor and operates, and centrifugal force acting on the permanent magnet 30 provided in a part of the magnet hole 52a is applied. To support it, stress concentration occurs. In FIG. 6A, stress concentrates on the R portions at both ends in the longitudinal direction of the permanent magnet 30 as viewed from the upper surface to form a stress concentration portion 52b.
Conventionally, the magnitude of R in the stress concentration portion is adjusted to suppress the peak of stress, but the magnitude of R is limited due to restrictions on the magnet size and magnetic circuit.

On the other hand, FIG. 5B is an explanatory view of a part of the motor rotor in which permanent magnets are inserted into the magnet holes of the motor rotor core according to the first embodiment and mounted therein.
As shown in FIG. 2B, the rotor core 10 for an electric motor of this example rotates when it is incorporated in the electric motor and operates, and centrifugal force acting on a permanent magnet 30 provided in a part of the magnet hole 12a is applied. In order to support, stress concentration may occur, but in the motor rotor core 10 of this example, amorphous powder described later in detail is used on the inner surface of the magnet hole 12a that is the surface of the stress concentration portion 12b of the rotor core molded body 12 for motor. Thus, an amorphous thin film 14 is formed.

Here, the manufacturing method of the rotor core for electric motors of this example is demonstrated in detail.
First, the manufacturing method of the used rotor core molded object for electric motors is demonstrated.
A rotor core molded body for an electric motor is obtained by compression molding (molding pressure: 800 MPa) using a compression molding machine (Somaloy 500, manufactured by Höganäs Co., Ltd.) with a magnetic powder having a silicon oxide (SiO ₂ ) insulating film formed on the surface of pure iron powder. , Molding temperature: 440 ° C.).
In such a rotor core molded body for an electric motor, the surface of each magnetic grain is insulated by an insulating thin film, and can effectively block, for example, an eddy current generated when an alternating magnetic field passes through, thereby reducing iron loss. It is possible to reduce.

Next, the used amorphous powder will be described.
For example, a necessary base material alloy is melted by arc melting or the like to produce an ingot, and then this ingot is pulverized using an atomizer.

FIG. 4 is a schematic diagram illustrating an example of an atomizer. As shown in the figure, the atomizer 100 includes a melting chamber 101, a quartz tube 102, a high frequency power source 103, a heating coil 104, a recovery chamber 105, an argon pump 106, an atomizing gas nozzle 107, a vacuum pump 108, and the like. .
An ingot (not shown) is placed in a quartz tube 102 disposed in the melting chamber 101, and the ingot in the quartz tube 102 is heated and melted by a heating coil 104 connected to a high frequency power source 103 capable of applying a high frequency magnetic field. Is done.
After the ingot is melted, argon (Ar) gas is injected from an argon pump 106 connected to the quartz tube 102, and molten metal is injected from the quartz tube 102 into the recovery chamber 105. At that time, Ar gas is blown from the atomizing gas nozzle 107 connected to the argon pump 106 to the molten metal sprayed from the quartz tube 102, whereby the molten metal is refined and rapidly cooled, so that the amorphous powder A Manufactured.
In addition, since the obtained amorphous powder has various particle diameters mixed, it was classified with a 50 μm mesh sieve, and an amorphous powder having a particle diameter of 50 μm or less was used.
The vacuum pump is a diffusion pump and has a capacity of up to 0.07 Pa.

Next, a method for forming an amorphous thin film will be described.
The amorphous thin film is formed by injecting the amorphous powder onto the rotor core molded body for an electric motor and arranging the amorphous powder in layers.

FIG. 5 is a schematic diagram illustrating an example of a powder injection device. As shown in the figure, the powder injection device 200 includes a powder tank 201, a high-pressure air pump 202, and a nozzle 203.
Amorphous powder (not shown) stored in the powder tank 201 is mixed with the air pumped from the high-pressure air pump 202, and the amorphous powder A is injected from the nozzle 203 at a high speed.
The injection speed of the amorphous powder is approximately 300 m / second or more, but can be appropriately adjusted depending on the above-described amorphous powder, the material of the rotor core molded body for an electric motor, and the like.

FIG. 6 is an explanatory view showing a state in which an amorphous thin film is formed on the surface of the rotor core molded body for an electric motor. As shown in the figure, when a permanent magnet (not shown) is mounted in the magnet hole 12a (see FIG. 3), the powder injection device 200 applies the surface of the portion that can become the stress concentration portion 12b of the rotor core molded body 12 for an electric motor. Amorphous powder A is sprayed.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.

(Example 2)
FIG. 7 is an explanatory view of a part of the rotor for an electric motor in which a permanent magnet is inserted into the magnet hole of the electric motor rotor core according to the second embodiment and mounted therein.
As shown in the figure, the motor rotor core 10 of this example is made ferromagnetic by using amorphous metal powder to be described later in detail on the inner surface of a magnet hole 12a that is the surface of the stress concentration portion 12b of the rotor core molded body 12 for motor. An amorphous thin film 14a is formed. A permanent magnet 30 is mounted in the magnet hole 12a.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.
In addition, since such a rotor core for an electric motor can obtain soft magnetic characteristics, the magnetic circuit of the electric motor is not hindered, and the strength can be increased without deteriorating the motor output performance.

The manufacturing method of the rotor core for electric motors of this example is demonstrated in detail.
A predetermined amount of Fe, Ga, B, Si, Fe—C alloy, and Fe—P alloy was weighed and then dissolved in Ar gas using a high-frequency melting furnace, and the composition was Fe ₇₇ Ga ₃ P _9.5 C _4. An ingot of B ₄ Si _2.5 was produced. Except for using this ingot, the same operation as in the method for producing amorphous powder in Example 1 was repeated to produce an amorphous powder, and further, the same operation as in the method for forming an amorphous thin film in Example 1 was repeated, A ferromagnetic amorphous thin film was formed to obtain the rotor core for an electric motor of this example.

(Example 3)
FIG. 8 is a partially enlarged view showing a cross-sectional state of the motor rotor in which permanent magnets are inserted into the magnet holes of the motor rotor core according to the third embodiment and mounted therein.
As shown in the figure, the electric motor rotor core 10 of this example is non-magnetic using an amorphous metal powder to be described later in detail on the inner surface of a magnet hole 12a, which is the surface of the stress concentration portion 12b of the electric motor rotor core molded body 12. An amorphous thin film 14b is formed. A permanent magnet 30 is mounted in the magnet hole 12a.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.
In addition, in such a rotor core for an electric motor, as shown in the figure, the leakage magnetic flux flowing in the vicinity of the magnet is difficult to flow, and the magnetic magnetic flux can be effectively used and the amount of magnetic flux increases. As a result, the performance of the electric motor is improved. When compared with the same magnet size, the motor has a higher output.

The manufacturing method of the rotor core for electric motors of this example is demonstrated in detail.
The nonmagnetic metallic glass used here is a titanium (Ti) -based material, and after weighing a predetermined amount of titanium (Ti), nickel (Ni), copper (Cu), tin (Sn) and tantalum (Ta), an arc dissolved in an Ar gas by melting method, the composition was prepared an ingot of _{Ti 50 Ni 15 Cu 25 Sn 5} Ta 5. Except for using this ingot, the same operation as in the method for producing amorphous powder in Example 1 was repeated to produce an amorphous powder. Further, the same operation as in the method for forming an amorphous thin film in Example 1 was repeated, A nonmagnetic amorphous thin film was formed to obtain a rotor core for an electric motor of this example.

Example 4
The manufacturing method of the rotor core for electric motors of this example is demonstrated in detail.
The magnetic powder in which an insulating thin film of silicon oxide (SiO ₂ ) was formed on the surface of the amorphous metal powder used in Example 2 was compression-molded (molding pressure) with an SPS sintering apparatus (SPS511S manufactured by SPS Shintex Co., Ltd.). : A ferromagnetic amorphous thin film is formed by repeating the same operation as the method for forming an amorphous thin film in Example 2, except that a rotor core molded body for an electric motor manufactured at a molding temperature of 420 to 440 ° C. is used. And the rotor core for electric motors of this example was obtained.
The temperature interval ΔT of the supercooled liquid region of the amorphous metal powder used for manufacturing the core compact was 48K, and the temperature interval ΔT of the supercooled liquid region of the amorphous metal powder used for forming the ferromagnetic amorphous thin film was 48K. It was.
Also in the above-described core rotor molded body for an electric motor, the surface of each magnetic grain is insulated, and for example, an eddy current generated when an alternating magnetic field is applied can be effectively cut off, and iron loss is reduced. Is possible.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.
In addition, since such a rotor core for an electric motor can obtain soft magnetic characteristics, the magnetic circuit of the electric motor is not hindered, and the strength can be increased without deteriorating the motor output performance.
Furthermore, in such a rotor core for an electric motor, since both the metal grains constituting the core molded body and the thin film covering the core molded body are in an amorphous state, stress due to thermal stress is less likely to occur and the reliability is higher. An electric motor can be provided.

FIG. 9 is a schematic diagram illustrating an example of an SPS sintering apparatus. As shown in the figure, the SPS sintering apparatus 300 includes a main body 301, a hydraulic pump 302, a cylinder 303, a replaceable sintering die 304, and a heating power source 305.
The main body 301, the hydraulic pump 302, the cylinder 303, and the sintering die 304 function as a press unit in cooperation, and the cylinder 303, the sintering die 304, and the heating power source 305 cooperate in the energization unit. Function as.
Specifically, pressure is generated by a hydraulic pump 302 provided in the main body 301, and magnetic powder (not shown) filled in the sintering die 304 is pressurized by the cylinder 303. Further, current is supplied to the sintering die 304 from the heating power source 305 via the cylinder 303, and the magnetic powder (not shown) filled in the sintering die 304 is heated by direct current pulse conduction.
The sintering conditions were such that the molding pressure was 600 MPa, and the current and voltage of DC pulse energization were controlled so that the temperature of the sintering mold was about 420 to 440 ° C.

(Example 5)
The manufacturing method of the rotor core for electric motors of this example is demonstrated in detail.
The magnetic powder in which an insulating thin film of silicon oxide (SiO ₂ ) was formed on the surface of the amorphous metal powder used in Example 2 was compression-molded (molding pressure) with an SPS sintering apparatus (SPS511S manufactured by SPS Shintex Co., Ltd.). : A nonmagnetic amorphous thin film is formed by repeating the same operation as the method for forming an amorphous thin film in Example 3 except that a rotor core molded body for an electric motor produced at a molding temperature of 420 to 440 ° C. is used. And the rotor core for electric motors of this example was obtained.
The temperature interval ΔT of the supercooled liquid region of the amorphous metal powder used for manufacturing the core compact was 45K, and the temperature interval ΔT of the supercooled liquid region of the amorphous metal powder used for forming the nonmagnetic amorphous thin film was 40K. It was.
Also in the above-described core rotor molded body for an electric motor, the surface of each magnetic grain is insulated, and for example, an eddy current generated when an alternating magnetic field is applied can be effectively cut off, and iron loss is reduced. Is possible.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.
In addition, in such a rotor core for an electric motor, the leakage magnetic flux that flows in the vicinity of the magnet becomes difficult to flow in the rotor for the electric motor using the same, and the magnetic flux can be effectively used. Will be improved. When compared with the same magnet size, the motor has a higher output.
Furthermore, in such a rotor core for an electric motor, since both the metal grains constituting the core molded body and the thin film covering the core molded body are in an amorphous state, stress due to thermal stress is less likely to occur and the reliability is higher. An electric motor can be provided.

(Example 6)
Using the same rotor core molded body for an electric motor as in Example 1, this was heated to 150 ° C., and the same operation as in the method for forming an amorphous thin film as in Example 1 was repeated to form an amorphous thin film. An example rotor core for an electric motor was obtained.
Also in the above-described core rotor molded body for an electric motor, the surface of each magnetic grain is insulated, and for example, an eddy current generated when an alternating magnetic field is applied can be effectively cut off, and iron loss is reduced. Is possible.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.
In a permanent magnet rotor or the like, the temperature at which the permanent magnet is demagnetized is around 150 ° C., and the vicinity of this temperature is the limit of use. By injecting in the vicinity of this temperature, the thermal stress due to the temperature difference between the amorphous thin film and the rotor core molded body for the motor is reduced, and there is an advantage that no extra stress acts during rotation of the motor.

  FIG. 10 is a schematic explanatory view showing a state in which the rotor core molded body for an electric motor is heated. As shown in the figure, before the amorphous metal powder was sprayed onto the rotor core compact for an electric motor and an amorphous thin film was formed, the rotor core compact 12 for an electric motor was heated by an external heating device 400 such as a hot plate. Moreover, although not shown in figure, you may take out what was heated with the heat processing furnace.

  FIG. 11 is a graph showing the relationship between the temperature of the core compact when injecting amorphous metal powder and the rotation limit of the obtained rotor core. As shown in the figure, it can be seen that the rotation limit is improved by processing at a high temperature.

(Example 7)
FIG. 12 is a perspective view of a piece of a core (an electric motor stator core) used in the electric motor stator according to the seventh embodiment.
As shown in the figure, the stator core piece 20 for an electric motor has a T-shape, and includes a stator salient pole portion 22a and a flange portion 22c formed at the tip thereof.

Fig.13 (a) is explanatory drawing in the cross section of the stator piece for electric motors which wound and attached the stator coil to the salient pole part of the stator core piece for electric motors which concerns on a prior art example.
As shown in FIG. 2A, when the stator core piece 60 for an electric motor of the conventional example is incorporated and operated in the electric motor, the stator core piece 60 includes a stator coil 70 wound around the stator salient pole portion 62a and rotates (not shown). A plurality of motor rotors are used and assembled in a circular shape to form a motor stator. And stress concentration occurs in order to support the repulsive force and attractive force acting between the motor rotor and the motor stator, or to support the counter-torque acting on the flange portion. In the conventional stator core piece 60 for an electric motor, stress concentrates in the vicinity of the root 62b and the flange 62c of the stator salient pole portion 62a, thereby forming stress concentration portions 62d and 62e.

On the other hand, FIG. 5B is an explanatory view of a cross section of the stator piece for the motor in which the stator coil is wound around the salient pole portion of the stator core piece for the motor according to the seventh embodiment.
As shown in FIG. 4B, when the stator core piece 20 for an electric motor of this example is incorporated in the electric motor and operates, the stator core piece 20 includes a stator coil 70 wound around the stator salient pole portion 22a and rotates (not shown). A plurality (9 or 12) of rotors are used around the motor rotor and assembled into a circle to form a motor stator. In order to support the repulsive force and attractive force acting between the motor rotor and the motor stator, or to support the counter-torque acting on the flange, stress concentration can occur. And in the stator core piece 20 for electric motors of this example, the amorphous powder mentioned later on the surface of the stator salient pole part 22a which is the surface of the stress concentration parts 22d and 22e of the stator core piece molded body 22 for motors, the back surface of the flange part 22c, etc. Is used to form an amorphous thin film 24.

Here, the manufacturing method of the stator core piece for electric motors of this example is demonstrated in detail.
First, the manufacturing method of the used stator core piece molded body for an electric motor will be described.
A stator core piece molded body for an electric motor is formed by compression molding (molding pressure: 800 MPa) with a compression molding machine (Somaloy 500, manufactured by Höganäs Co., Ltd.), a magnetic powder having a silicon oxide (SiO ₂ ) insulating thin film formed on the surface of pure iron powder. , Molding temperature: 440 ° C.).
In such a stator core piece molded body for an electric motor, the surface of each magnetic grain is insulated with an insulating thin film, and can effectively block, for example, eddy currents generated when an alternating magnetic field passes through, thereby reducing iron loss. Can be reduced.

Next, the used amorphous powder will be described.
For example, the required base material alloy is melted by arc melting to produce an ingot, and then this ingot is pulverized by an atomizer. In this example, it was produced by the same method as in Example 1.

Next, a method for forming an amorphous thin film will be described.
The amorphous thin film is formed by injecting the amorphous powder onto the stator core piece molded body for an electric motor and arranging the amorphous powder in layers. In this example, it was produced by the same method as in Example 1.

FIG. 14 is an explanatory view showing a state in which an amorphous thin film is formed on the surface of the stator core piece molded body for an electric motor. As shown in the figure, when a stator coil (not shown) is mounted on the stator salient pole portion 22a and a current is passed to generate a magnetic flux to operate the motor (see FIG. 13), the stator core for the motor is used. Amorphous powder A is injected by the powder injection device 200 onto the surface of the portion of the piece molded body 22 that can be the stress concentration portions 22d and 22e of the stator salient pole portion 22a (the vicinity of the root portion 22b and the flange portion 22c of the stator salient pole portion). .
The amorphous powder A was injected by fixing the stator core piece molded body 22 for an electric motor to the jig 500. In the injection of the amorphous powder A onto the flange portion 22c, an injection pressure acts, and therefore it is possible to prevent the flange portion 22c from being damaged by using a jig 500 as illustrated.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.

(Example 8)
FIG. 15 is an explanatory diagram of a cross section of a stator core piece for an electric motor according to an eighth embodiment. As shown in the figure, in the stator core piece for electric motor 20 of this example, a ferromagnetic amorphous thin film 24a is formed on the back surface of the flange 22c, which is the surface of the stress concentration part 22e of the stator core piece molded body 22 for electric motor. .

The manufacturing method of the stator core piece for an electric motor of this example will be described in detail.
The stator core molded body for an electric motor was obtained by forming an amorphous thin film using the same amorphous powder as that of Example 2 on the back surface of the collar portion that could become a stress concentration portion, thereby obtaining the stator core piece for the electric motor of this example.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.
In addition, since such a stator core piece for an electric motor provides soft magnetic characteristics, it does not interfere with the magnetic circuit of the electric motor, and can be increased in strength without deteriorating the motor output performance.

Example 9
FIG. 16 is an explanatory diagram of a cross section of the stator core for an electric motor according to the ninth embodiment. As shown in the figure, in the stator core piece 20 for the electric motor of this example, the surface of the base portion 22b of the stator salient pole portion 22a, which is the surface of the stress concentration portion 22d of the starter core piece molded body 22 for the motor, is ferromagnetic. An amorphous thin film 24a is formed.
Further, the root vicinity portion 22b is a portion where the magnetic flux is most easily concentrated, and is also a portion where the heat generation amount is locally high. Arrow B in the figure indicates the magnetic flux in the root vicinity 22b.

The manufacturing method of the stator core piece for an electric motor of this example will be described in detail.
The stator core molded body for an electric motor is obtained by forming an amorphous thin film on the surface in the vicinity of the root portion of the stator salient pole portion that can be a stress concentration portion, using the same amorphous powder as in Example 2, and for the electric motor of this example. A stator core piece was obtained.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.
In addition, since such a stator core piece for an electric motor provides soft magnetic characteristics, it does not interfere with the magnetic circuit of the electric motor, and can be increased in strength without deteriorating the motor output performance.
Furthermore, since the amorphous metal thin film has a higher specific resistance than the crystalline metal thin film, loss due to eddy current generated when the magnetic flux passes can be suppressed.

(Example 10)
FIG. 17 is an explanatory diagram of a cross section of the stator core piece for an electric motor according to the tenth embodiment. As shown in the figure, in the stator core piece for electric motor 20 of this example, a nonmagnetic amorphous thin film 24b is formed on the back surface of the flange portion 22c, which is the surface of the stress concentration portion 22e of the stator core piece molded body 22 for electric motor.

The manufacturing method of the stator core piece for an electric motor of this example will be described in detail.
The stator core molded body for an electric motor was obtained by forming an amorphous thin film using the same amorphous powder as in Example 3 on the back surface of the collar portion that could be a stress concentration portion, to obtain a stator core piece for an electric motor of this example.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.
Normally, the thickness of the ferromagnetic amorphous thin film is 10 to 100 μm. However, when the film thickness is increased (for example, the film thickness is 100 to 200 μm), the magnetic circuit width increases so much that the magnetic flux bypasses the flange of the adjacent pole. Will increase. On the other hand, when a non-magnetic amorphous thin film is applied, the detouring magnetic flux does not increase, so the film thickness can be, for example, 500 to 1000 μm, and the strength of the buttock is improved while preventing the flow of detouring magnetic flux. be able to.
Moreover, since the freedom degree of design of a collar part improves, there also exists an advantage that the performance of an electric motor is easy to be improved.
Furthermore, since the amorphous metal thin film has a higher specific resistance than the crystalline metal thin film, loss due to eddy current generated when the magnetic flux passes can be suppressed.

(Example 11)
FIG. 18 is an explanatory diagram of a cross section of the stator core piece for an electric motor according to the eleventh embodiment. As shown in the figure, the stator core piece 20 for the electric motor of this example has a nonmagnetic amorphous thin film 24b formed on the back and side surfaces of the flange 22c, which is the surface of the stress concentration portion 22e of the stator core piece molded body 22 for the electric motor. Yes.

The manufacturing method of the stator core piece for an electric motor of this example will be described in detail.
The stator core molded body for an electric motor is obtained by forming an amorphous thin film on the back surface and side surface of the collar portion that can be a stress concentration portion using the same amorphous powder as in Example 3 to obtain the stator core piece for the electric motor of this example. It was.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.
Usually, the thickness of the ferromagnetic amorphous thin film is 10 to 100 μm. However, when the film thickness is increased (for example, the film thickness is 500 to 1000 μm), the magnetic circuit width increases so much that the magnetic flux bypasses the flange of the adjacent pole. Will increase. On the other hand, when a non-magnetic amorphous thin film is applied, the detouring magnetic flux does not increase, so the film thickness can be set to 100 μm, for example, and the strength of the collar can be improved while preventing the flow of detouring magnetic flux. it can.
Furthermore, since the amorphous metal thin film has a higher specific resistance than the crystalline metal thin film, loss due to eddy current generated when the magnetic flux passes can be suppressed.

Example 12
The manufacturing method of the stator core piece for an electric motor of this example will be described in detail.
The magnetic powder in which an insulating thin film of silicon oxide (SiO ₂ ) was formed on the surface of the amorphous metal powder used in Example 2 was compression-molded (molding pressure) with an SPS sintering apparatus (SPS511S manufactured by SPS Shintex Co., Ltd.). : 600 MPa, molding temperature: 420 to 440 ° C.) The same operation as in the amorphous thin film forming method of Example 2 was repeated except that the stator core piece molded body for an electric motor manufactured was used. The stator core piece for the electric motor of this example was obtained.
The temperature interval ΔT of the supercooled liquid region of the amorphous metal powder used for manufacturing the core piece compact was 48K, and the temperature interval ΔT of the supercooled liquid region of the amorphous metal powder used for forming the ferromagnetic amorphous thin film was 48K. It was.
Also in the stator core piece molded body for an electric motor described above, the surface of each magnetic grain is insulated, and for example, an eddy current generated when an alternating magnetic field is applied can be effectively cut off, and iron loss is reduced. It is possible.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.
In addition, since such a stator core for an electric motor can provide soft magnetic characteristics, it does not hinder the magnetic circuit of the electric motor, and it is possible to increase the strength without deteriorating the motor output performance.
Further, in such a stator core piece for an electric motor, since both the metal particles constituting the core piece molded body and the thin film covering the core piece molded body are in an amorphous state, stress due to thermal stress is less likely to occur, and more reliable. A high electric motor can be provided.

(Example 13)
The manufacturing method of the stator core piece for an electric motor of this example will be described in detail.
The magnetic powder in which an insulating thin film of silicon oxide (SiO ₂ ) was formed on the surface of the amorphous metal powder used in Example 2 was compression-molded (molding pressure) with an SPS sintering apparatus (SPS511S manufactured by SPS Shintex Co., Ltd.). : Non-magnetic amorphous thin film by repeating the same operation as the method for forming an amorphous thin film in Example 3 except that a stator core piece molded body for an electric motor produced at a molding temperature of 420 to 440 ° C. is used. The stator core for an electric motor of this example was obtained.
The temperature interval ΔT of the supercooled liquid region of the amorphous metal powder used for manufacturing the core piece compact was 40K, and the temperature interval ΔT of the supercooled liquid region of the amorphous metal powder used for forming the nonmagnetic amorphous thin film was 45K. It was.
Also in the stator core piece molded body for an electric motor described above, the surface of each magnetic grain is insulated, and for example, an eddy current generated when an alternating magnetic field is applied can be effectively cut off, and iron loss is reduced. It is possible.
Since the amorphous thin film formed in this way is dense, cracks are hardly generated even by stress concentration, and an electric motor using the amorphous thin film can be rotated to a high speed. Further, the strength reliability of the electric motor is further improved.
In addition, in such a stator core piece for an electric motor, a leakage magnetic flux that flows in the vicinity of the magnet becomes difficult to flow in an electric motor rotor using the same, and the magnetic flux can be effectively used. Performance will be improved. When compared with the same magnet size, the motor has a higher output.
Furthermore, in such a stator core piece for an electric motor, since both the metal particles constituting the core piece molded body and the thin film covering the core molded body are in an amorphous state, stress due to thermal stress is less likely to occur and more reliable. A high electric motor can be provided.

It is a graph which shows the relationship between the particle size of atomized powder and the minimum injection speed of the amorphous powder in which an amorphous thin film is formed. 1 is a perspective view of a rotor core for an electric motor according to Embodiment 1. FIG. It is explanatory drawing (a) and (b) of a part of the rotor for electric motors which inserted the permanent magnet in the magnet hole of the rotor core for electric motors which concerns on a prior art example, and Example 1, and was mounted | worn inside. It is the schematic which shows an example of an atomizer. It is the schematic which shows an example of a powder injection apparatus. It is explanatory drawing which shows a mode that the amorphous thin film is formed in the surface of the rotor core molded object for electric motors. FIG. 6 is an explanatory view of a part of a rotor for an electric motor in which a permanent magnet is inserted into a magnet hole of an electric motor rotor core according to a second embodiment and mounted therein. FIG. 6 is a partial explanatory diagram of a motor rotor in which a permanent magnet is inserted into a magnet hole of a motor rotor core according to a third embodiment and mounted therein. It is the schematic which shows an example of a SPS sintering apparatus. It is typical explanatory drawing which shows a mode that the rotor core molded object for electric motors is heated. It is a graph which shows the relationship between the temperature of the core molded object at the time of injecting an amorphous metal powder, and the rotation limit of the obtained rotor core. FIG. 10 is a perspective view of a stator core piece for an electric motor according to a seventh embodiment. It is explanatory drawing (a) in the cross section of the stator piece for electric motors which concerns on a prior art example and Example 7, and (b). It is explanatory drawing which shows a mode that the amorphous thin film is formed in the surface of the stator core piece molded object for electric motors. FIG. 10 is an explanatory view in a cross section of a stator core piece for an electric motor according to an eighth embodiment. It is explanatory drawing in the cross section of the stator core piece for electric motors which concerns on Example 9. FIG. It is explanatory drawing in the cross section of the stator core piece for electric motors which concerns on Example 10. FIG. It is explanatory drawing in the cross section of the stator core piece for electric motors which concerns on Example 11. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rotor core for motors 12 Rotor core compact for motors 12a Magnet hole 12b Stress concentration part 14 Amorphous thin film 14a Ferromagnetic amorphous thin film 14b Nonmagnetic amorphous thin film 20 Stator core piece for motor 22 Stator core piece compact for motor 22a Starter salient pole part 22b Stator bump Near pole part 22c collar 22d stress concentration part 22e stress concentration part 24 amorphous thin film 24a ferromagnetic amorphous thin film 24b nonmagnetic amorphous thin film 30 permanent magnet 50 rotor core for motor 52a magnet hole 52b stress concentration part 60 stator core piece for motor 62 electric motor Stator core piece molded body 62a Starter salient pole part 62b Stator salient pole part base vicinity part 62c collar part 62d Stress concentration part 62e Stress concentration part 70 Stator coil 1 0 Atomizer 101 Melting chamber 102 Quartz tube 103 High frequency power supply 104 Heating coil 105 Recovery chamber 106 Argon pump 107 Atomizing gas nozzle 108 Vacuum pump 200 Powder injection device 201 Powder tank 202 High pressure air pump 203 Nozzle 300 SPS sintering device 301 Main body 302 Hydraulic pump 303 Cylinder 304 Sintering mold 305 Heating power source 400 Heating device 500 Jig

Claims (21)

A core formed by compression molding magnetic particles having an insulating thin film on the surface of a metal particle containing a ferromagnetic element, which is used in a rotor for an electric motor or an electric motor stator, and an amorphous thin film. ,
The said amorphous thin film is formed in the surface of the stress concentration part of the said core molded object, The core characterized by the above-mentioned.   2. The core according to claim 1, wherein the amorphous thin film is formed by injecting amorphous metal powder onto the core molded body and arranging the amorphous thin film in a layered manner. For the amorphous metal powder, the following formula (1)
ΔTx = Tx−Tg (1)
The core according to claim 2, wherein the temperature interval ΔTx of the supercooled liquid region represented by (Tx in the formula is a crystallization start temperature and Tg is a glass transition temperature) is 20K or more.   The core according to any one of claims 1 to 3, wherein the amorphous thin film contains a ferromagnetic element.   The core according to claim 4, wherein the amorphous thin film contains at least one selected from the group consisting of iron, nickel, and cobalt as the ferromagnetic element.   The core according to any one of claims 1 to 5, wherein the amorphous thin film contains a nonmagnetic element.   The core according to claim 6, wherein the amorphous thin film contains at least one selected from the group consisting of titanium, copper, and magnesium as the nonmagnetic element.   The said metal particle contains at least 1 sort (s) chosen from the group which consists of iron, nickel, and cobalt as said ferromagnetic element, The statement of any one of Claims 1-7 characterized by the above-mentioned. Core.   The core according to any one of claims 1 to 8, wherein the metal grains have a crystal structure as a main phase.   The core according to any one of claims 1 to 8, wherein the metal grains have an amorphous structure as a main phase. For metal grains having the above amorphous structure as the main phase, the following formula (1)
ΔTx = Tx−Tg (1)
The core according to claim 10, wherein the temperature interval ΔTx of the supercooled liquid region represented by (Tx in the formula represents a crystallization start temperature and Tg represents a glass transition temperature) is 20 K or more.   The core is a core used for a stator for an electric motor, and the stress concentration portion is a portion near the root of the stator salient pole portion of the core and / or a flange portion formed at the tip of the stator salient pole portion. The core according to any one of claims 1 to 11, characterized in that   When the core is a core used for a stator for an electric motor, and the stress concentration portion is a flange formed at the tip of the stator salient pole portion of the core, the core is formed at the tip of the stator salient pole portion. 13. The core according to claim 12, wherein the amorphous thin film formed on the back surface of the flange includes at least one selected from the group consisting of iron, nickel, and cobalt.   When the core is a core used for a stator for an electric motor and the stress concentration portion is in the vicinity of the root of the stator salient pole of the core, the core is formed on the surface of the vicinity of the root of the stator salient pole. The core according to claim 12 or 13, wherein the amorphous thin film contains at least one selected from the group consisting of iron, nickel and cobalt.   When the core is a core used for a stator for an electric motor, and the stress concentration portion is a flange formed at the tip of the stator salient pole portion of the core, the core is formed at the tip of the stator salient pole portion. 15. The amorphous thin film formed on the back surface of the collar portion contains at least one selected from the group consisting of titanium, copper and magnesium, according to any one of claims 12 to 14. Core.   When the core is a core used for a stator for an electric motor, and the stress concentration portion is a flange formed at the tip of the stator salient pole portion of the core, the core is formed at the tip of the stator salient pole portion. 16. The amorphous thin film formed on the back surface of the flange portion and the side surface of the flange portion contains at least one selected from the group consisting of titanium, copper and magnesium. A core according to one paragraph. It is a manufacturing method of the core given in any 1 paragraph of Claims 1-16,
Injecting amorphous metal powder onto a core compact and arranging it in layers to form an amorphous thin film, the temperature of the core compact is increased before the amorphous metal powder is injected. . A rotor for an electric motor using the core according to any one of claims 1 to 16,
A rotor for an electric motor comprising: a core used for the rotor for an electric motor; and a magnet attached to the inside and / or the surface of the core. A stator for an electric motor using the core according to any one of claims 1 to 16,
An electric motor stator comprising: a core used for an electric motor stator; and a coil wound around the core.   An electric motor comprising at least the electric motor rotor according to claim 18 or the electric motor stator according to claim 19.   The electric motor according to claim 20, which is used for an electric vehicle or a hybrid vehicle.

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