JP7131457B2 - Electric motor manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing an electric motor, an electric blower equipped with the electric motor manufactured by this manufacturing method , and an electric device equipped with this electric blower.

A rotor for an electric machine typically includes a rotor core that is affixed to a shaft, the rotor core containing magnets that adhere to the shaft. The rotor core also includes a sleeve that surrounds the magnets for the purpose of preventing the magnets from cracking and breaking apart due to stress caused by rotation of the rotor. The sleeve is fixed to the magnet by gluing or the like (see, for example, Patent Document 1).

Moreover, various permanent magnets can be employed for the rotor core of the electric blower. A bonded magnet, which is one type of permanent magnet, is mainly composed of ferromagnetic powder and a polymer compound, and is often manufactured by an injection molding method because of its high productivity. Also disclosed is a method for producing an anisotropic magnet in injection molding, in which the outer peripheral surface of a molded body obtained by injection molding in a mold is magnetized in the same direction as the anisotropic direction (for example, , see Patent Document 2).

Japanese Patent No. 5506992 Japanese Patent No. 6371235

The shaft and permanent magnet (rotor core), and the permanent magnet and sleeve are respectively bonded with an adhesive. Here, in the rotor manufacturing process in which the permanent magnet is adhered to the shaft and the sleeve is adhered to the permanent magnet, the relative positional relationship between the two to be adhered must be maintained so as not to change while the adhesive is being cured. I need to continue. This process therefore requires a long waiting time and increases the manufacturing cost of the rotor.

Here, a predetermined gap for injecting the adhesive is formed between the outer peripheral surface of the rotor core and the inner peripheral surface of the sleeve, and the sleeve is positioned relative to the rotor core so as to maintain the relative positional relationship between the two. Positioning is important. As means for facilitating this positioning, it is effective to form a plurality of convex shapes on the cylindrical outer peripheral surface of the rotor core.

By the way, as a means for increasing the magnetic force of the rotor core, it is effective to use an anisotropic bonded magnet as the permanent magnet of the rotor core. When the magnetic force of the rotor core is increased, the force to rotate the rotor is increased, and an electric motor capable of high-speed rotation is obtained. When molding an anisotropic bonded magnet for a rotor having a convex shape for positioning on the outer peripheral surface, the anisotropic bonded magnet for the rotor is placed in a mold for molding the anisotropic bonded magnet for the rotor. In order to create an aligning magnetic field for magnetism, a permanent magnet for generating an aligning magnetic field is required in addition to the anisotropic bonded magnet for the rotor. This permanent magnet for generating an oriented magnetic field needs to be arranged away from the cylindrical outer peripheral surface of the anisotropic bonded magnet for the rotor by the height of the convex shape radially outward of the cylindrical rotor core. The distance between the magnetic field generating permanent magnet and the cylindrical outer peripheral surface of the rotor anisotropic bonded magnet is increased. As a result, the strength of the oriented magnetic field in the anisotropic bonded magnet for rotors is reduced, and sufficient orientation of the anisotropic material (magnetic powder) cannot be obtained in the molding of the anisotropic bonded magnet for rotors, resulting in increased magnetic force. There was a problem that it was difficult to mold strong anisotropic bonded magnets for rotors.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and provides an electric motor that facilitates the positioning of the sleeve with respect to the rotor core, provides a rotor core with strong magnetic force, reduces manufacturing costs, and is capable of high-speed rotation. An object of the present invention is to provide an electric blower provided with and an electric device provided with this electric blower.

A method for manufacturing an electric motor according to the present invention has a rotor assembly including a shaft, a cylindrical rotor core fixed to the shaft, and a sleeve enclosing the rotor core, and the rotor core has a predetermined thickness in the radial direction. A mixture of anisotropic material and resin is filled in the inner peripheral side of the first mold, which is a cylindrical non-magnetic material having a The rotor core has a plurality of magnetic poles, the rotor core has a cylindrical surface with a plurality of ridges having the same radial height from the cylindrical surface, the plurality of ridges having an orientation filling the recesses between the molded rotor core and a second mold into which the rotor core is inserted and which has recesses formed on the inner peripheral surface so as to be scooped outward in the radial direction; It is molded using a resin containing no anisotropic material and fixed to the rotor core.

According to the present invention, a plurality of protrusions provided on the outer periphery of the rotor core facilitate positioning of the sleeve with respect to the rotor core, and the rotor core having a magnet with strong magnetic force is provided to provide an electric motor capable of high-speed rotation. be able to.

1 is an external perspective view of an electric blower including the electric motor of Embodiment 1. FIG. FIG. 2 is a view of the electric blower including the electric motor of Embodiment 1 viewed from the axial direction of the rotor assembly. FIG. 3 is a cross-sectional view taken along line AA of FIG. 2; 3 is a cross-sectional view parallel to the axis of the rotor assembly in the electric motor of Embodiment 1 and passing through the center of the axis; FIG. 2 is an external perspective view of a stator in the electric motor of Embodiment 1. FIG. FIG. 2 is a side view of the rotor subassembly in the electric motor of Embodiment 1, with the sleeve, the pair of bearings, and the preload portion removed from the rotor assembly; FIG. 5 is a cross-sectional view taken along line BB of FIG. 4; FIG. 7 is a partially enlarged view of a C portion of FIG. 6; 4 is a cross-sectional view in the direction perpendicular to the axis at the stage of molding the rotor core in the electric motor of Embodiment 1 with a mold; FIG. FIG. 4 is a cross-sectional view in a direction perpendicular to the axis at the stage of forming a plurality of projections of the rotor core in the electric motor of Embodiment 1 with a mold; FIG. 4 is a cross-sectional view in a direction perpendicular to the axis at the stage of molding a rotor core in an electric motor different from that of Embodiment 1; FIG. 8 is a side view of a rotor assembly in the electric motor of Embodiment 2; 8 is a cross-sectional view parallel to the axis of the rotor assembly in the electric motor of Embodiment 2 and passing through the center of the axis; FIG. FIG. 11 is a side view of a rotor core in a modification of the electric motor of Embodiment 2; FIG. 11 is a side view of a rotor core in another modification of the electric motor of Embodiment 2;

Embodiments will be described below with reference to the drawings. The same reference numerals in each figure indicate the same or corresponding parts. In the present disclosure, overlapping descriptions are appropriately simplified or omitted. It should be noted that the present invention can include any combination of configurations disclosed in the following embodiments. In addition, the shape, material, manufacturing method, and the like described in the present disclosure can be appropriately selected as long as they do not contradict the outline of the present invention, even if they are not specified.

Unless otherwise specified in the present disclosure, the axial direction is the direction parallel to the longitudinal direction of the shaft 301 shown in FIG. 6 to be described later. The radial direction is defined as a direction perpendicular to the axial direction and passing through the center of the shaft 301 .

Embodiment 1.
1 to 3 show electric blower 100 in which impeller 101 is attached as a load portion to electric motor 1 according to Embodiment 1, and FIG. 1 is an external perspective view of electric blower 100 having electric motor 1 according to Embodiment 1. is. FIG. 2 is a view of electric blower 100 including electric motor 1 of Embodiment 1, viewed from the axial direction on the side of rotor assembly 300, which will be described later. FIG. 3 is a cross-sectional view of electric blower 100 including electric motor 1 of Embodiment 1, showing a cross section taken along line AA in FIG. The cross section along line AA is a cross section passing through the central axis of shaft 301 of electric blower 100 .

The electric motor 1 is, for example, a brushless electric motor. The electric motor 1 rotates at a rated rotation speed of 100000 [r/min], for example. Also, the possible rotation speed range may be 30000 to 120000 [r/min].

The electric motor 1 has a frame 200 . Frame 200 is a member that forms the outer shell of electric motor 1 . The shape of the frame 200 includes, for example, a first cylindrical portion 200a and a second cylindrical portion 200b. The first cylindrical portion 200a has a smaller diameter than the second cylindrical portion 200b. That is, the frame 200 has a stepped cylindrical shape, and one end of the frame 200 is narrower than the other end. The second cylindrical portion 200b has an opening 200c on the opposite side of the first cylindrical portion 200a. The frame 200 is made of aluminum alloy, for example.

Electric motor 1 includes rotor assembly 300 and stator 400 . FIG. 4 is a cross-sectional view parallel to shaft 301 of rotor assembly 300 in electric motor 1 of Embodiment 1 and passing through the central axis of shaft 301 . FIG. 5 is an external perspective view of stator 400 in electric motor 1 of Embodiment 1. FIG.

The rotor assembly 300 includes a shaft 301, a cylindrical rotor core 302 fixed to the shaft 301, a sleeve 303 enclosing the rotor core 302, a first end cap 304, a second end cap 305, a pair of bearings 306 and It has a preload portion 307 . A preload portion 307 applies a preload to each of the pair of bearings 306 . The preload portion 307 is composed of, for example, a preload spring 307a, a cushion rubber 307b, and a spacer 307c. Note that the preload portion 307 is not limited to the configuration shown here. For example, the configuration may include only the preload spring 307a.

A stator 400 has a stator core 401 made of laminated thin electromagnetic steel sheets and wound with windings 402. Terminal wires 402a of the windings 402 are tied to terminals 404 for electrical connection. Stator core 401 and windings 402 are electrically insulated by insulating member 403 . The connection between the terminal wire 402a and the terminal 404 may be a solder connection, a fusing connection, a bite terminal connection, or the like, in addition to the connection shown here. Stator 400 generates a magnetic flux when current flows through terminals 404 . Then, this magnetic flux acts on the rotor core 302 as a force to rotate the shaft 301 with respect to permanent magnets, which are fixed to the rotor core 302 and will be described later.

As shown in FIGS. 3 and 4 , the pair of bearings 306 and preload portion 307 of rotor assembly 300 are housed in first cylindrical portion 200 a of frame 200 , and a portion of rotor assembly 300 and stator 400 are mounted on frame 200 . It is accommodated in the second cylindrical portion 200b. At least one of the pair of bearings 306 of the rotor assembly 300 is desirably fixed to the inner peripheral surface of the first cylindrical portion 200a of the frame 200 via an adhesive or the like. At least one of the pair of bearings 306 is fixed to the inner peripheral surface of the first cylindrical portion 200a of the frame 200 to prevent the rotor assembly 300 from slipping out of the first cylindrical portion 200a of the frame 200. can be done. As the adhesive, for example, a two-liquid reaction type adhesive or an anaerobic adhesive is used. The stator 400 is fixed to the second cylindrical portion 200b of the frame 200 by interference fit, for example. For example, the frame 200 is heated to expand the second cylindrical portion 200b of the frame 200 by thermal expansion, the stator 400 is inserted through the opening 200c, and then the cylindrical portion 200b of the frame 200 is cooled to contract, so that the frame 200 provides an interference fit to stator 400 .

Stator 400 is provided to surround rotor core 302 . The axial center of rotor core 302 is the magnetic center of rotor core 302 , and the axial center of stator core 401 is the magnetic center of stator core 401 . The magnetic center of the rotor core 302 means a point at which the intensity distribution in the axial direction of the shaft 301 is symmetrical with respect to the intensity distribution of the lines of magnetic force generated by the rotor core 302 . Similarly, the magnetic center of the rotor core 302 means a point at which the intensity distribution in the axial direction of the shaft 301 is symmetrical with respect to the intensity distribution of the lines of magnetic force generated by the rotor core 302 . Rotor core 302 and stator core 401 are configured such that the magnetic center of rotor core 302 and the magnetic center of stator core 401 match.

Rotor core 302 and stator core 401 are configured such that the magnetic center of rotor core 302 and the magnetic center of stator core 401 match, but may be configured so that they do not match. For example, the magnetic center of rotor core 302 may be located on the opening side of frame 200 (opposite side of impeller 101 side) relative to the magnetic center of stator core 401 . A force acts on rotor core 302 from stator core 401 in a direction in which the magnetic center of rotor core 302 coincides with the magnetic center of rotor core 302 . For example, when the magnetic center of rotor core 302 is located on the opening side of frame 200 (opposite side of impeller 101 side) than the magnetic center of stator core 401, rotor core 302 is on the side opposite to the opening of frame 200. That is, the force is applied to the impeller 101 side. That is, the rotor core 302 acts to press the entire rotor assembly 300 toward the impeller 101 side. Therefore, the rotor assembly 300 is prevented from falling off the frame 200 .

Conversely, when the magnetic center of rotor core 302 is closer to impeller 101 than the magnetic center of stator core 401 , rotor core 302 receives force on the opening side of frame 200 . On the other hand, due to the rotation of impeller 101 , rotor assembly 300 receives force toward impeller 101 . In this way, the force acting on the rotor core 302 due to the misalignment of the magnetic centers of the rotor core 302 and the stator core 401 acts to cancel the force acting on the rotor core 302 due to the rotation of the impeller 101. Therefore, the rotor assembly The force that presses the entire 300 against the impeller 101 side is relaxed.

The shaft 301 is a member that serves as a rotating shaft of the electric motor 1, and is made of, for example, structural carbon steel, martensitic stainless steel with higher hardness, or the like. Moreover, considering the use of a magnetic field orientation mold, non-magnetic austenitic stainless steel or the like may be used. Shaft 301 is arranged in the center of the internal space of frame 200 . The rotor core 302 is fixed to the shaft 301 by, for example, an adhesive or integral molding, which will be described later. A pair of bearings 306 are also attached to the shaft 301 by, for example, an interference fit. Shaft 301 is rotatably supported by frame 200 via bearing 306 . Rotor core 302 is formed by permanent magnets. The permanent magnet here may be a plastic magnet formed by injection molding or compression molding a mixture of rare earth magnet powder such as neodymium Nd or samarium cobalt Sm2Co17 and resin. Rotor core 302 has a plurality of magnetic poles. Rotor core 302 is a member that transmits the magnetic force received from stator 400 to shaft 301 . The rotor core 302 is, for example, cylindrical. Rotor core 302 is fixed to the outer peripheral surface of shaft 301 . The rotor core 302 made of plastic magnet and the shaft 301 can be integrally molded. When rotor core 302 and shaft 301 are fixed by integral molding, the outer peripheral surface of shaft 301 is preferably knurled.

The first end cap 304 and the second end cap 305 are substantially cylindrical members, and their inner peripheral surfaces are fixed to the outer peripheral surface of the shaft 301 . The first end cap 304 and the second end cap 305 are secured to the shaft 301 by press fit or adhesive. When the rotor core 302 and the shaft 301 are integrally molded, the first end cap 304 and the second end cap 305 are fixed to the shaft 301 after the rotor core 302 is fixed to the shaft 301 . When the rotor core 302 and the shaft 301 are adhered and the first end cap 304 and the second end cap 305 are also adhered, they may be fixed at the same time.

The first end cap 304 and the second end cap 305 prevent fragments of the permanent magnet from scattering in the axial direction when the rotor core 302 is cracked. Also, each end cap is connected to the rotor core 302 directly, via an adhesive, or via a connecting portion 302c, which will be described later. Deformation/distortion of the rotor core 302 due to centrifugal force when the rotor assembly 300 is rotating is suppressed by the end caps 304 and 305, so the rotor core 302 is less likely to crack. Also, for the adjustment of mass imbalance, which will be described later, they are arranged at both ends of the rotor core 302 to enable two-face correction. Two-face correction improves dynamic unbalance (dynamic mass imbalance). The first end cap 304 and the second end cap 305 may be, for example, cylindrical with a stepped outer peripheral surface. The first end cap 304 and the second end cap 305 are non-magnetic.

A first end cap 304 is positioned between rotor core 302 and bearing 306 . The second end cap 305 is arranged on the opposite side of the first end cap 304 with respect to the rotor core 302 . The side surface of the rotor core 302 on the impeller 101 side and the side surface of the first end cap 304 facing this, and the side surface of the rotor core 302 opposite to the impeller 101 and the side surface of the second end cap 305 facing this contact. The first end cap 304 and rotor core 302 or the second end cap 305 and rotor core 302 may be arranged with a gap. When the sleeve 303 is adhered to the rotor core 302 , the adhesive can impregnate the gap between the first end cap 304 and the rotor core 302 or the gap between the second end cap 305 and the rotor core 302 .

There is a mass imbalance in rotor assembly 300, such as when the center of gravity of rotor core 302 is not on the axis of shaft 301, or when shaft 301 has a slight bend. The mass imbalance produces radial forces as the rotor assembly 300 rotates supported by the pair of bearings 306 . This radial force causes excessive whirling of the rotor assembly 300 and excessive stress inside the pair of bearings 306, degrading the performance of the electric blower 100. FIG. By measuring the mass imbalance of rotor assembly 300 and cutting portions of first end cap 304 and second end cap 305 at appropriate locations, the mass imbalance of rotor assembly 300 is reduced.

The sleeve 303 is a member that covers the outer circumference of the rotor core 302 . The sleeve 303 is, for example, a cylindrical member. Sleeve 303 is a member for fixing rotor core 302 . In this embodiment, sleeve 303 covers the entire outer circumference of rotor core 302 . Alternatively, the sleeve 303 covers a portion of the outer circumference of the first endcap 304 and a portion of the outer circumference of the second endcap 305 . For example, when the second end cap 305 has a stepped cylindrical shape as shown in FIG. 4, the sleeve 303 covers the small diameter portion of the second end cap 305 and abuts on the step portion with the large diameter portion for positioning. be able to. The rotor core 302 and the sleeve 303 are fixed with an adhesive.

The sleeve 303 of this embodiment is a non-magnetic material. As an example, the sleeve 303 is made of a composite material containing carbon fiber and resin. A composite material containing carbon fiber and resin is an example of a lightweight, high-strength and heat-resistant material.

Electric blower 100 includes electric motor 1 , impeller 101 , diffuser 102 , bracket 201 and cover 202 . The impeller 101 is a member that rotates to generate an airflow sucked from the cover 202 side toward the inside of the electric blower 100 . The impeller 101 is fastened to the shaft 301 with a nut or the like. Bracket 201 and cover 202 are members forming part of the outer shell of electric blower 100 . The inner peripheral surface of the cover 202 is fitted to the outer peripheral surface of the bracket 201 . The inner peripheral surface of cover 202 and the outer peripheral surface of bracket 201 are fixed with an adhesive.

As shown in FIG. 3, impeller 101 is attached to a portion of shaft 301 that protrudes outward from one end of frame 200 . In this embodiment, a pair of bearings 306 are arranged between impeller 101 and rotor core 302 . Note that the arrangement of the impeller 101, the pair of bearings 306, and the rotor core 302 is not limited to this arrangement. For example, one bearing 306 may be arranged axially on the impeller 101 side with respect to the rotor core 302 , and the other bearing 306 may be arranged axially on the opposite side of the impeller 101 with respect to the rotor core 302 .

Bracket 201 is attached to one end of frame 200 . Bracket 201 is provided to surround first cylindrical portion 200 a of frame 200 . The inner peripheral surface of the cover 202 is fitted to the outer peripheral surface of the bracket 201 . The inner peripheral surface of cover 202 and the outer peripheral surface of bracket 201 are fixed with an adhesive. A cover 202 is provided to cover the impeller 101 . An intake port 202 a is formed in the cover 202 on the windward side with respect to the impeller 101 at one end side of the cover 202 . A diffuser 102 is attached to one end of the bracket 201 . A cascade of blades is formed in the diffuser 102 to form a plurality of flow paths on the inner surface of the cover 202 .

An exhaust port 201 a is formed on the other end side of the bracket 201 . The exhaust port 201a is provided radially outward of the shaft 301 from the intake port 202a. The exhaust port 201 a is provided radially outward of the shaft 301 relative to the frame 200 . Electric blower 100 takes in air from intake port 202a and sends out air from exhaust port 201a.

Frame 200 , bracket 201 and cover 202 described above are an example of a casing that forms the outer shell of electric blower 100 . In this embodiment, rotor assembly 300, stator 400 and impeller 101 are housed in this casing. Also, the intake port 202a and the exhaust port 201a are formed in this casing.

Here, with reference to FIG. 3, air flow during operation of electric blower 100 will be described. In electric blower 100 , when current is supplied from terminal 404 , stator 400 generates magnetic flux that rotates around shaft 301 over time, and rotor core 302 is given a rotating force. This causes rotor core 302 and shaft 301 to rotate. Also, the impeller 101 attached to the shaft 301 rotates.

When the impeller 101 rotates, the pressure at the intake port 202a becomes negative. As a result, air is sucked into the cover 202 through the intake port 202a. The sucked air is sent from the center of the impeller 101 to the outer periphery. Air sent to the outer periphery of impeller 101 flows into a plurality of flow paths created by cover 202 and diffuser 102 . The air flowing through the plurality of flow paths recovers the pressure and improves the blowing performance of the electric blower 100 . The air that has passed through the plurality of flow paths flows inside the bracket 201 and is blown out from the exhaust port 201a.

Further, as shown in FIG. 3, the frame 200 may be formed with a vent 200d. The air vent 200d is an opening that connects the internal space of the second cylindrical portion 200b of the frame 200 and the internal space of the bracket 201 . By forming the vent 200d, part of the air flowing inside the bracket 201 flows into the second cylindrical portion 200b via the vent 200d. Rotor assembly 300 or stator 400 is cooled by the air flowing into second cylindrical portion 200b. The air that has flowed into the second cylindrical portion 200b is discharged from the opening 200c on the other end side of the frame 200. As shown in FIG. In addition, when the ventilation port 200d is formed, part or all of the exhaust port 201a may be blocked. In that case, part or all of the air flowing through bracket 201 flows into second cylindrical portion 200b, and the cooling effect of rotor assembly 300 or stator 400 is improved.

Next, the structure of rotor assembly 300 according to Embodiment 1 of the present invention will be described with reference to FIGS. 6 to 8. FIG. FIG. 6 is a side view of the rotor subassembly 300a excluding the sleeve of the rotor 300, the pair of bearings 306, and the preload portion 307 in the electric motor 1 of Embodiment 1. FIG. 7 is a cross-sectional view perpendicular to the axis of rotor assembly 300 in electric motor 1 of Embodiment 1, and is a cross-sectional view along BB in FIG. FIG. 8 is a partially enlarged view of the rotor assembly in electric blower 100 of Embodiment 1, and is a partially enlarged view of section C in FIG.

As shown in FIGS. 6 to 8, rotor core 302 of rotor subassembly 300a has a plurality of linear projections 302a formed parallel to the axial direction of shaft 301 on its cylindrical outer peripheral surface. The plurality of protrusions 302a have the same height on the cylindrical surface of the rotor core 302 in the radial direction from this cylindrical surface. A plurality of protrusions 302 a are provided rotationally symmetrically around the central axis of the shaft 301 . A plurality of projections 301 are formed continuously on the other axial end surface (opposite side of impeller 101) of rotor core 302, which is a magnet. When the sleeve 303 encloses the rotor subassembly 300a, the plurality of protrusions 302a contact the inner peripheral surface of the sleeve 303, forming a uniform gap between the outer peripheral surface of the rotor core 302 and the inner peripheral surface of the sleeve 303. do. In this way, since the plurality of protrusions 302 a are formed in a straight line parallel to the axial direction of the shaft 301 , there is even space between the outer peripheral surface of the rotor core 302 and the inner peripheral surface of the sleeve 303 in the axial direction of the shaft 301 . A large gap can be formed, and the axial deviation of the shaft 301 can be suppressed with respect to the filled adhesive.

An adhesive (not shown) is filled between the outer peripheral surface of the rotor core 302 and the inner peripheral surface of the sleeve 303 . The plurality of protrusions 302a make the gaps between the two even, and the plurality of protrusions 302a are arranged so as to be rotationally symmetrical about the central axis of the shaft 301. Therefore, the gap between the shaft 301 and the adhesive to be filled is relatively small. To suppress the occurrence of mass imbalance due to deviation around the axis. Due to the rotational angular acceleration of the rotor assembly 300a and the moment of inertia of the sleeve 303, a shear stress acts on the interface between the sleeve 303 and the adhesive in the rotational direction of the rotor assembly 300a. Since the generation of shear stress concentration due to non-uniformity of the adhesive is suppressed, reliability is improved. In addition, positioning and fixing is performed from the outside of the rotor assembly 300 using a jig or the like, and compared to the conventional manufacturing process that requires a long period of time for hardening the adhesive, no jig or the like for positioning and fixing is required, and the plurality of convex portions 302a are formed. A uniform gap is easily obtained by

As shown in FIG. 6 , the plurality of protrusions 302 a are linear parallel to the shaft 301 and shorter than the axial length of the rotor core 302 . Thereby, the gap formed between the rotor core 302 and the sleeve 303 is not partitioned into a plurality of spaces by the plurality of protrusions 302a, but becomes one continuous space. For example, when the adhesive is filled after the sleeve 303 is attached to the rotor subassembly 300a, the gap formed between the rotor core 302 and the sleeve 303 becomes one continuous space. is not required, the manufacturing cost is suppressed, and non-uniformity of the adhesive due to unevenness of the filling amount is suppressed.

As shown in FIG. 8, the ends of the plurality of projections 302a on the impeller 101 side form a slope shape with an angle of D°. Therefore, when the sleeve 303 is attached to the rotor core 302 from the impeller 101 side, the end surface of the sleeve 303 is less likely to be caught by the end of the convex portion 302a, resulting in good workability.

Next, an example of a method for manufacturing rotor assembly 300 in the electric blower according to Embodiment 1 of the present invention will be described with reference to FIGS. 9 and 10. FIG. FIG. 9 is a cross-sectional view in the direction perpendicular to shaft 301 at the stage of molding rotor core 302 with a mold in the method of manufacturing rotor core 302 in electric motor 1 of the first embodiment. FIG. 10 is a cross-sectional view in a direction perpendicular to shaft 301 at the stage of forming a plurality of protrusions 301a of rotor core 302 in electric motor 1 of Embodiment 1 with a mold. FIG. 11 is a cross-sectional view in the direction perpendicular to shaft 301 at the stage of molding rotor core 601 of an electric motor different from electric motor 1 of Embodiment 1 with a mold.

Rotor core 302 of the first embodiment is a plastic magnet formed by injection molding a mixture of rare earth magnet powder and resin. Moreover, this powder is an anisotropic magnet each having an axis of easy magnetization. That is, the rotor core 302 has magnets made of an anisotropic material. By using an anisotropic magnet powder and molding it in an oriented magnetic field, the rotor core 302 has a direction of easy magnetization, and the magnetic force per unit volume is reduced compared to the case of an isotropic magnet that does not have a direction of easy magnetization. becomes stronger. An electric motor with a rotor core made of anisotropic plastic magnets is capable of high output, or a smaller and lighter electric motor can be provided for the same output requirement.

FIG. 9 is a diagram schematically showing a cross section of an injection molding die 500 for molding rotor core 302 on the outer circumference of shaft 301. As shown in FIG. In the rotor core 302, the shaft 301 molded by another mold is inserted in advance into the center of the cylindrical mold sleeve 502, and magnetic powder and resin are formed on the outer side of the shaft 301 on the inner peripheral side of the mold sleeve 502. It is molded by being filled with a mixed material (hereinafter referred to as a plastic magnet compound). The injection mold 500 comprises a plurality of oriented magnets 501 that create a magnetic field within the molding machine. That is, the rotor core 302 and the plurality of oriented magnets 501 are separated by the mold sleeve 502 during molding. The mold sleeve 502 is non-magnetic and has a radial thickness E. A plurality of oriented magnets 501 are arranged outside the mold sleeve 502 . A plurality of orienting magnets 501 are arranged around the shaft 301 such that their north and south poles are adjacent. Arrows in FIG. 9 indicate lines of magnetic force generated by the oriented magnet 501 .

When the injection mold 500 is filled with the melt-plasticized plastic magnet compound, the anisotropic magnet powder contained in the plastic magnet compound follows the magnetic field created by the orienting magnets 501 to form the anisotropic magnet powder. It is oriented in the direction of easy magnetization, which is the direction in which the magnetic moment of the body tends to be oriented. The smaller the distance between the oriented magnets 501 and the rotor core 302 , the stronger the magnetic force of the oriented magnets 501 acts on the rotor core 302 . Here, the thickness E of the mold sleeve 502 is desirably made as thin as possible from the physical strength, wear resistance, fatigue characteristics, etc. of the mold sleeve 502 . That is, the smaller the thickness E of the die sleeve 502, the stronger the magnetic field generated by the oriented magnets 501 acts on the rotor core 302, forming the rotor core 302 with a large magnetic force, thereby obtaining a high-performance motor with higher speed and output. be done.

The rotor core 302 of Embodiment 1 is manufactured by insert molding in which the shaft 301 is previously inserted into a mold and a melted plastic magnet compound is filled therein. By insert molding the shaft 301 and the rotor core 302, they are integrated, and the manufacturing cost is suppressed compared to the case where the shaft 301 and the rotor core 302 are fixed by other methods such as adhesion.

Also, in FIG. 9, the case where the oriented magnet 501 uses four poles and the rotor core 302 is a magnet having four magnetic poles has been described as an example. Here, the magnetic poles formed on the rotor core 302 are S poles when the magnetic poles of the oriented magnets 501 facing the rotor core 302 are N poles, and N poles when the magnetic poles of the oriented magnets 501 are S poles. be done. A similar manufacturing method can be applied even if the number of poles is different.

FIG. 10 is a diagram schematically showing a cross section of an injection molding die 510 for molding a plurality of projections 302a on the surface of the cylindrical surface, which is the outer peripheral surface of rotor core 302. As shown in FIG. The plurality of protrusions 302a has a height F in the radial direction. When molding the plurality of protrusions 302a, first, a mold sleeve different from the mold sleeve 502 of the injection mold 500 shown in FIG. The molded rotor core 302 is inserted in advance into the cylindrical molding portion 511 . Here, a plurality of concave portions for forming the plurality of convex portions 302a are formed on the inner periphery of the molded portion 511. As shown in FIG. This concave portion is formed so as to be scooped out radially outward from the cylindrical surface of the inner surface of the forming portion 511 in the cross section shown in FIG. And it is formed so as to extend in the axial direction of the shaft 301 . The plurality of protrusions 302a are formed by melted plasticized resin in a space surrounded by the outer cylindrical surface of the rotor core 302 and recesses formed so as to be scooped out on the inner periphery of the molding portion 511 of the injection mold 510. It is molded by filling with That is, the plurality of projections 302a are fixed to the rotor core 302, which is a magnet, and the plurality of projections 302a are molded by two-color molding after the rotor core 302, which is a magnet, is molded in an oriented magnetic field.

At this time, since the material of the plurality of projections 302a is chemically bonded to the rotor core 302, the strength of the bonding surface between the two is increased. Also, the resin of the plurality of protrusions 302 a may be a resin different from that of the rotor core 302 . For example, it may be a resin that does not contain magnet powder. When the material of the plurality of protrusions 302a is a plastic magnet compound, it functions as a magnetic path. As the plastic magnet compound forming the rotor core 302, the case where the anisotropic magnet powder is mixed with the resin has been described, but the plastic magnet compound as the material of the plurality of protrusions 302a is the isotropic magnet powder. The body may be mixed. Thus, since the plurality of protrusions 302a are made of a material different from that of the rotor core 302, the degree of freedom in designing the plurality of protrusions 302a is increased.

Here, for comparison, rotor core 601 in an electric blower different from that of Embodiment 1 will be described with reference to FIG. 11 . FIG. 11 is a cross-sectional view in the direction perpendicular to shaft 301 at the stage of molding rotor core 601 with a mold in a method of manufacturing rotor core 601 in an electric blower different from that of the first embodiment.

FIG. 11 is a diagram schematically showing a cross section of an injection mold 700 for molding rotor core 601. As shown in FIG. The injection mold 700 has a mold sleeve 702, and the inner peripheral surface of the mold sleeve 702 is filled with an anisotropic plastic magnet compound to form the rotor core 601 different from that of the first embodiment. The injection mold 700 also includes a plurality of oriented magnets 701 . A rotor core 601 different from the first embodiment includes a plurality of protrusions 601a that are continuous with the rotor core 601 .

When the injection mold 700 is filled with the melt-plasticized plastic magnet compound, the anisotropic magnet powder contained in the plastic magnet compound is oriented according to the magnetic field created by the orienting magnet 701 . The thickness E of the thin portion of the mold sleeve 702 is preferably as thin as possible in order to manufacture a rotor core with a large magnetic force. cannot be less than the thickness E. A plurality of projections 601 a formed on rotor core 601 have a height F radially outward from the cylindrical surface of rotor core 601 . That is, the rotor core 601 in the electric blower, which is different from the first embodiment, has an oriented magnetic field formed at a position E+F away from the surface of the oriented magnet 701 facing the metal sleeve 702, and is molded in this magnetic field. This is because rotor core 601 has a greater distance from orienting magnet 701 than orienting magnet 501 in rotor core 302 in the electric blower of the first embodiment, and the magnetic force received from orienting magnet 701 is relatively large. means small. As a result, it is difficult to obtain a high-performance electric motor with the rotor core 601 in the electric blower different from that of the first embodiment.

In this way, the plurality of projections 302a are formed by two-color molding after the rotor core 302, which is a magnet, is molded in an oriented magnetic field. and the oriented magnet can be reduced by the height F of the plurality of projections, and a motor provided with a magnet having a large magnetic force can be obtained. Also, the degree of freedom in forming the plurality of projections is increased.

Thus, the electric motor according to Embodiment 1 has a rotor assembly including a shaft, a cylindrical rotor core fixed to the shaft, and a sleeve enclosing the rotor core. The rotor core has a plurality of magnetic poles, the magnet has a plurality of protrusions having the same radial height from the cylindrical surface, and a plurality of The sleeve is molded using the rotor core after the rotor core is molded and is fixed to the magnet, so positioning jigs are not required, and the sleeve can be easily positioned on the outer circumference of the rotor core by the multiple projections. be done. As a result, adhesion between the sleeve and the rotor core is facilitated. Further, since the rotor core excluding the plurality of protrusions is formed before forming the plurality of protrusions, the distance between the rotor core and the oriented magnets before forming the plurality of protrusions is equal to that of the plurality of protrusions. A rotor core can be obtained that can be reduced by the height and has magnets with a large magnetic force. In other words, the plurality of protrusions provided on the outer periphery of the rotor core facilitates the positioning of the sleeve with respect to the rotor core, and since the rotor core has magnets with strong magnetic force, it is possible to obtain an electric motor capable of high-speed rotation. In addition, the rotor core can be manufactured by injection molding, thereby suppressing an increase in manufacturing cost.

In addition, since the plurality of projections are formed in a straight line parallel to the axial direction of the shaft and arranged so as to be rotationally symmetrical about the axis of the shaft, the outer peripheral surface of the rotor core and the inner peripheral surface of the sleeve are aligned. A uniform gap can be formed between them in the axial direction of the shaft, and when this gap is filled with adhesive, it is possible to suppress the occurrence of mass imbalance due to unevenness of the plurality of protrusions and unevenness of the adhesive.

In addition, since the plurality of projections are formed by two-color molding after the rotor core is molded in the oriented magnetic field, the distance between the rotor core and the oriented magnets before the plurality of projections are molded is set to a plurality of distances. It is possible to reduce the height by the height of the convex portion, thereby obtaining an electric motor provided with a magnet having a large magnetic force. Also, the degree of freedom in forming the plurality of projections is increased.

Moreover, the plurality of protrusions are formed continuously on one of the two axial end faces of the rotor core, and are not continuous on the other. Since the gap formed between the outer peripheral surface of the rotor core and the inner peripheral surface of the sleeve is continuous as a single space due to the fact that the plurality of protrusions are not continuous with the axial end surface of the rotor core, the adhesive is not applied. When filling, the entire gap can be filled with the adhesive without being blocked by the plurality of protrusions. In addition, since the plurality of protrusions are continuously formed on one of the two axial end faces of the rotor core, the structure of the die becomes complicated when the plurality of protrusions are formed in the die. It can be molded without breaking.

Moreover, since the plurality of protrusions are made of a material different from that of the rotor core, the degree of freedom in designing the plurality of protrusions is increased.

Embodiment 2.
Next, an electric motor according to Embodiment 2 will be described. The second embodiment will be described with a focus on differences from the electric motor of the first embodiment described above. Parts that are the same as or correspond to those in the first embodiment are denoted by the same reference numerals, and explanations thereof are simplified and omitted. In Embodiment 1, the plurality of convex portions 302a are formed using the formed rotor core 302 and the forming portion 511, which is a die sleeve. Embodiment 2 is different in that the molded rotor core 302 is not used when forming the plurality of protrusions 302b. FIG. 12 is a side view of rotor assembly 310a in electric motor 1 of Embodiment 2. FIG. FIG. 13 is a cross-sectional view parallel to shaft 301 of rotor assembly 310 a in electric motor 1 of Embodiment 2 and passing through the center of shaft 301 .

Rotor assembly 310 a includes rotor core 302 affixed to shaft 301 . Further, the cylindrical surface of the rotor core 302 is provided with a plurality of protrusions 302b. Each of the plurality of protrusions 302b is continuous with the connecting portion 302c on the other axial end side of the rotor assembly 310a. A rotor assembly 310a shown in FIGS. 12 and 13 includes a first end cap 304 on one end side of the rotor core 302 (on the impeller 101 side).

Rotor assembly 310a of the second embodiment is molded in a magnetic field by an oriented magnet provided in an injection molding die in the same manner as rotor assembly 300a of the first embodiment. A connection portion 302c that is continuous with the portion 302b and the plurality of protrusions 302b is formed integrally with the rotor core 302 . That is, the plurality of protrusions 302b are formed by two-color molding after the rotor core 302, which is a magnet, is molded in the oriented magnetic field. When molding the connecting portion 302c and the plurality of projections 302b, for example, a resin inflow gate is provided on the axial end face of the connecting portion 302c, and molten resin is filled from the resin inflow gate. Since the melted resin is filled from a relatively wide portion and all the plurality of protrusions 302b are continuous, all the plurality of protrusions 302b are uniformly filled with resin, and stable moldability can be obtained. At the same time, molding defects such as mass imbalance and short shots can be suppressed.

FIG. 14 shows a rotor core in a modification of the electric motor 1 of the second embodiment. Rotor assembly 310a includes a second end cap 305 on the other end (the side opposite impeller 101). The inner diameter of the sleeve 303 and the diameter of the cylinder circumscribing the plurality of protrusions 302b are equal, and are indicated by diameter φG in FIG. Also, the outer diameter of the second end cap 305 is indicated by φH. As shown in FIG. 14, by making φH larger than φG, the end cap 305 functions as positioning of the sleeve 303 .

FIG. 15 shows a rotor core in another modification of the electric motor 1 of the second embodiment. Connection 302c in rotor assembly 310a has a range of diameters φI greater than φG. As shown in FIG. 15, by making φI larger than φG, the connecting portion 302c functions as positioning of the sleeve 303. As shown in FIG.

Thus, the electric motor according to Embodiment 2 has a rotor assembly including a shaft, a cylindrical rotor core fixed to the shaft, and a sleeve enclosing the rotor core. The rotor core is provided with a plurality of magnetic poles, and the rotor core is provided with a plurality of projections having the same height in the radial direction from the cylindrical surface on the cylindrical surface. , the plurality of projections are fixed to the rotor core, and have a connecting portion continuous with the plurality of projections on one end face of the shaft in the axial direction with respect to the rotor core, so that the sleeve can move a positioning jig or the like by the plurality of projections. It is easily positioned around the outer circumference of the rotor core without the need to facilitate bonding between the sleeve and the rotor core. As a result, the distance between the rotor core and the orienting magnets before forming the plurality of projections can be reduced by the height of the plurality of projections, and a rotor core having magnets with large magnetic force can be obtained. A rotatable electric motor can be obtained. In addition, since the plurality of projections are in communication with the connection portion, all the plurality of projections 302b are uniformly filled with the resin, and stable moldability is obtained. can be suppressed.

Further, since the plurality of protrusions are formed in a straight line parallel to the axial direction of the shaft and are arranged so as to be rotationally symmetrical about the axis of the shaft, the outer peripheral surface of the rotor core and the inner peripheral surface of the sleeve are aligned. A uniform gap can be formed between them in the axial direction of the shaft, and when this gap is filled with adhesive, it is possible to suppress the occurrence of mass imbalance due to unevenness of the plurality of protrusions and unevenness of the adhesive.

Also, since the diameter of the connecting portion is larger than the diameter of the cylinder circumscribing the plurality of projections, the connecting portion functions as positioning of the sleeve.

Further, since the plurality of projections are formed by two-color molding after the rotor core is molded in the oriented magnetic field, for example, the material of the plurality of projections 302b is made of a plastic magnet compound, and a gold plate having oriented magnets is used. By molding in a mold, an integrated product of the connecting portion 302c and the plurality of convex portions 302b having a strong magnetic force can be obtained.

Moreover, since the plurality of protrusions are made of a material different from that of the rotor core, the degree of freedom in designing the plurality of protrusions is increased.

Also, the electric blower 100 includes an electric motor 1 and an impeller 101 . Impeller 101 is fixed to the end of shaft 301 of electric transmitter 1 . In the electric motor 1, a rotor core having a magnet with a large magnetic force can be produced by injection molding, thereby suppressing an increase in manufacturing costs and providing an electric blower with a strong attractive force.

As examples of electrical equipment, the present invention can be applied to a vacuum cleaner equipped with an electric blower 100 having the electric motor 1, a hand dryer, and the like. In the electric motor 1 of the electric blower 100 provided in the electric equipment, a rotor core having a magnet with a large magnetic force can be produced by injection molding, suppressing an increase in manufacturing costs and obtaining an electric equipment with strong suction force and blowing force.

1 electric motor,
100 electric blower,
101 Impeller,
102 Diffuser,
200 frames,
200a first cylindrical portion,
200b first cylindrical portion,
200c opening,
200d vent,
201 brackets,
201a exhaust port,
202 cover,
202a inlet,
300 rotor assembly,
300a rotor subassembly;
301 shaft (axle),
302 rotor core,
302a convex part,
302b convex part,
302c connection,
303 sleeve,
304 first end cap;
305 second end cap;
306 bearings,
307 preload unit,
307a preload spring;
307b cushion rubber,
307c spacer,
310a rotor assembly;
400 stator,
401 stator core,
402 windings,
402a terminal line,
403 insulating member,
404 terminals,
500 injection mold,
501 oriented magnets,
502 mold sleeve,
510 injection mold,
601 rotor core,
700 injection mold,
701 oriented magnets,
702 mold sleeve.

Claims (10)

a rotor assembly comprising a shaft, a cylindrical rotor core secured to the shaft, and a cylindrical sleeve surrounding the rotor core;
The rotor core is filled with a mixture of an anisotropic material and a resin on the inner peripheral side of a cylindrical nonmagnetic first mold having a predetermined thickness in the radial direction. having magnets oriented and molded by an orientation magnet positioned outside the mold;
The rotor core has a plurality of magnetic poles,
The rotor core has a plurality of projections having the same radial height from the cylindrical surface on the cylindrical surface,
The plurality of protrusions are formed by the oriented rotor core and a second mold having recesses formed in the inner peripheral surface so as to be hollowed out in the radial direction while the rotor core is inserted. A method of manufacturing an electric motor that is fixed to the rotor core and is molded using a resin that does not contain the anisotropic material and that is filled in the recesses between. 2. The method of manufacturing an electric motor according to claim 1, wherein said plurality of projections are formed in a straight line parallel to the axial direction of said shaft, and arranged so as to be rotationally symmetrical about said shaft axis. 3. The method of manufacturing an electric motor according to claim 1, wherein said plurality of convex portions are formed by two-color molding. 4. The method of manufacturing an electric motor according to claim 3, wherein the plurality of protrusions are formed continuously on one of the two axial end faces of the rotor core, and are not continuous on the other. The method of manufacturing an electric motor according to any one of claims 1 to 4, wherein the plurality of protrusions are made of a material different from that of the rotor core. a rotor assembly comprising a shaft, a cylindrical rotor core secured to the shaft, and a cylindrical sleeve surrounding the rotor core;
The rotor core is filled with a mixture of an anisotropic material and a resin on the inner peripheral side of a cylindrical nonmagnetic first mold having a predetermined thickness in the radial direction. having magnets oriented and molded by an orientation magnet positioned outside the mold;
The rotor core has a plurality of magnetic poles,
The rotor core has a plurality of projections having the same radial height from the cylindrical surface on the cylindrical surface,
The plurality of protrusions are molded by filling a resin in a third mold different from the first mold and fixed to the rotor core,
having a connecting portion fixed to one end surface of the shaft in the axial direction with respect to the rotor core;
The method of manufacturing an electric motor, wherein the plurality of protrusions are continuous with the connecting portion. 7. The method of manufacturing an electric motor according to claim 6, wherein said plurality of projections are formed in a straight line parallel to the axial direction of said shaft, and arranged so as to be rotationally symmetrical about said shaft axis. 8. The method of manufacturing an electric motor according to claim 6, wherein a diameter of said connecting portion is larger than an inner diameter of said sleeve that circumscribes said plurality of projections. The method of manufacturing an electric motor according to any one of claims 6 to 8, wherein the plurality of protrusions are formed by two-color molding. The electric motor manufacturing method according to any one of claims 6 to 9, wherein the plurality of protrusions are made of a material different from that of the rotor core.

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