Rotor and electric motor

Abstract

This electric motor comprises: a rotating shaft that extends in an axial direction; and a rotating body that is fixed to the rotating shaft. The rotating body has a plurality of coils disposed so as to surround the rotating shaft, and a resin plate formed from a resin for molding the plurality of coils. The resin plate has a first surface orthogonal to the axial direction, and a second surface positioned on the opposite side of the first surface. At least one among the first surface and the second surface is provided with a rib protruding in the axial direction.

Description

Rotor and Electric Motor

[0001] The present disclosure relates to a rotor and an electric motor.

[0002] Electric motors are widely used in the field of automotive electrical equipment such as electric cleaners, as well as in the field of electrical equipment for automobiles. For example, an electric motor is used in an electric blower mounted on an electric cleaner to rotate a rotary fan. In two-wheeled or four-wheeled vehicles, an electric motor is used to drive a cooling fan such as a radiator.

[0003] As electric motors, a brushed electric motor (commutator motor) using brushes and a brushless electric motor not using brushes are known. Among these, the brushed electric motor includes a stator, a rotor that rotates by the magnetic force of the stator, a commutator attached to the rotating shaft of the rotor, a brush that contacts the commutator, and a brush holder that holds the brush.

[0004] In recent years, in-vehicle electric motors used in vehicles are required to be miniaturized and lightened in addition to cost reduction. In particular, electric motors used for cooling fans of radiators in two-wheeled motorcycles are required to be miniaturized and lightened. For this reason, as an in-vehicle electric motor, a flat-type coreless motor (flat motor) with a thin thickness and using brushes is used.

[0005] Conventionally, as this type of electric motor, Patent Document 1 discloses a flat motor. The flat motor includes a rotor that is a coreless armature having a rotating shaft, a stator composed of an annular thin magnet, a commutator attached to the rotating shaft, a brush that contacts the commutator, and a brush holder that holds the brush.

[0006] In the rotor included in the flat motor, the rotating body has a plurality of coils arranged at a predetermined pitch so as to surround the rotating shaft, and a resin plate formed of a resin that molds the plurality of coils. As the material of the resin that molds the plurality of coils, for example, an unsaturated polyester resin (BMC (Bulk Molding Compound) resin) having a heat resistance of 200°C to 230°C is used in consideration of strength, heat resistance, moldability, cost, etc.

[0007] However, as the temperature environment in which electric motors are used becomes increasingly harsh year by year, the resin plates on the rotating body may deform and warp. When the resin plates deform, they may come into contact with components (magnets or brackets) located close to the rotating body, potentially causing the electric motor to lock up. In other words, the rotor may stop rotating. If the electric motor locks up, and the electric motor is used in a vehicle, this will result in a vehicle malfunction.

[0008] Japanese Patent Application Publication No. 8-275480

[0009] This disclosure was made to solve such problems. The purpose of this disclosure is to provide a rotor and an electric motor that can suppress deformation of the resin plate of the rotating body.

[0010] To achieve the above objective, one embodiment of a rotor according to the present disclosure comprises a rotating shaft extending in the axial direction and a rotating body fixed to the rotating shaft, wherein the rotating body has a plurality of coils arranged to surround the rotating shaft and a resin plate made of resin that molds the plurality of coils, the resin plate having a first surface perpendicular to the axial direction and a second surface located opposite to the first surface, and at least one of the first surface and the second surface is provided with a rib protruding along the axial direction.

[0011] Furthermore, one embodiment of the electric motor according to this disclosure comprises the rotor described above and a stator that generates a magnetic force acting on the rotor.

[0012] According to this disclosure, deformation of the resin plate of the rotating body can be suppressed.

[0013] This is a perspective view of the electric motor according to the embodiment, viewed from above. This is a perspective view of the electric motor according to the embodiment, viewed from below. This is a cross-sectional view of the electric motor according to the embodiment, taken by cutting through a plane that passes through the axis of the rotating shaft and one of the pair of brushes. This is a cross-sectional view of the electric motor according to the embodiment, taken by cutting through a different cross-section than the cross-section in Figure 3. This is a perspective view of the rotor according to the embodiment, viewed from above. This is a perspective view of the rotor according to the embodiment, viewed from below. This is a perspective view of the resin plate on the rotating plate of the rotor according to the embodiment. This is a cross-sectional view of an electric motor of a comparative example. This is a perspective view of the rotor according to Modification Example 1. This is a perspective view of the rotor according to Modification Example 2, viewed from above. This is a perspective view of the rotor according to Modification Example 2, viewed from below. This is a perspective view of the rotor according to Modification Example 3, viewed from above. This is a perspective view of the rotor according to Modification Example 3, viewed from below. This is a perspective view of the rotor according to Modification Example 4, viewed from above. This is a perspective view of the rotor according to Modification Example 4, viewed from below. This is a perspective view of the rotor according to Modification Example 5. This is a cross-sectional view of the electric motor according to Modification Example 6.

[0014] The embodiments of this disclosure will be described below with reference to the drawings. The embodiments described below are all specific examples of this disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions of components, and connection configurations shown in the following embodiments are examples and are not intended to limit this disclosure. Accordingly, among the components in the following embodiments, those components that are not described in the independent claims representing the highest-level concepts of this disclosure will be described as optional components.

[0015] Each figure is a schematic diagram and not necessarily a strictly accurate representation. Throughout all figures, substantially identical components are denoted by the same reference numerals, and redundant explanations are omitted or simplified.

[0016] In this embodiment, the radial direction of the stator 10 and rotor 20 is defined as the "radial direction," and the rotational direction of the rotor 20 is defined as the "circumferential direction." That is, the direction extending from the axis C of the rotation axis 21 is the "radial direction," and the direction revolving around the axis C of the rotation axis 21 is the "circumferential direction." Therefore, the "radial direction" is the direction perpendicular to the direction of the axis C of the rotation axis 21 (also simply called the "axial direction"). In this specification, the terms "up" and "down" do not necessarily refer to the upward direction (vertically upward) and the downward direction (vertically downward) in absolute spatial perception.

[0017] (Embodiment) The overall configuration of the electric motor 1 according to the embodiment will be described using Figures 1 to 4. Figure 1 is a perspective view of the electric motor 1 according to the embodiment as seen from above. Figure 2 is a perspective view of the electric motor 1 according to the embodiment as seen from below. Figure 3 is a cross-sectional view of the electric motor 1 according to the embodiment when it is cut by a plane that passes through the axis C of the rotating shaft 21 and through one of the pair of brushes 50. Figure 4 is a cross-sectional view of the electric motor 1 according to the embodiment when it is cut by a different cross-section than the cross-section in Figure 3.

[0018] As shown in Figures 3 and 4, the electric motor 1 comprises a stator 10, a rotor 20 that rotates due to the magnetic force of the stator 10, and a first bearing 31 and a second bearing 32 that rotatably support the rotating shaft 21 of the rotor 20. The electric motor 1 is a brushed electric motor. The electric motor 1 further comprises a commutator 40 attached to the rotating shaft 21 of the rotor 20, at least one brush 50 in contact with the commutator 40, and a brush holder 60 that holds the brush 50. The electric motor 1 also comprises a first bracket 70 and a second bracket 80. As shown in Figures 1 and 2, a power supply line 2 for supplying power to the electric motor 1 is connected to the electric motor 1.

[0019] The electric motor 1 is a type of DC motor driven by direct current. Therefore, as shown in Figures 3 and 4, a magnet is used as the stator 10 in the electric motor 1. The rotor 20 of the electric motor 1 is an armature having coils 210. Furthermore, the electric motor 1 is a flat-type brushed coreless motor (flat motor) mounted on a two-wheeled or four-wheeled vehicle. Therefore, the stator 10 and rotor 20 do not have a core (iron core), and the electric motor 1 as a whole has a thin and lightweight structure. As an example, the electric motor 1 is a small motor used as a cooling fan for a radiator in a vehicle. The outer diameter (diameter) φ of the electric motor 1 is 120 mm or less. The outer diameter φ of the electric motor 1 is, for example, φ60 mm, φ70 mm, or φ90 mm. The electric motor 1 is driven by power supplied from an external power source such as a battery. For example, the electric motor 1 is driven by a DC 12V input voltage supplied via a power supply line 2 connected to an external power source.

[0020] The following describes each component of the electric motor 1 in detail.

[0021] As shown in Figures 3 and 4, the stator 10 is positioned between it and the rotor 20 with a small air gap in between. The stator 10 generates a magnetic force that acts on the rotor 20. The stator 10 is configured to generate magnetic flux on the surface facing the rotor 20 via the air gap, and together with the armature rotor 20, it forms a magnetic circuit. The stator 10 is a thin, annular plate-shaped member as a whole. The stator 10 is fixed to the second bracket 80.

[0022] The stator 10 is a field magnet that generates a magnetic flux for torque generation. The stator 10 is configured such that north poles and south poles are alternately and evenly distributed on the surface facing the rotor 20 via an air gap along the circumferential direction of the rotation shaft 21. In this embodiment, the stator 10 is made up of magnets. The magnets that make up the stator 10 are, for example, permanent magnets. Therefore, the magnets that make up the stator 10 are configured such that north poles and south poles are alternately and evenly distributed along the circumferential direction. As an example, the annular magnet that makes up the stator 10 is magnetized to have six poles. The direction of the main magnetic flux generated by the stator 10 (magnets) is in the direction of the axis C of the rotation shaft 21.

[0023] The rotor 20 has a rotating shaft 21 and a rotating body 22 fixed to the rotating shaft 21. The rotor 20 rotates about the axis C of the rotating shaft 21. The rotor 20 generates a magnetic force that acts on the stator 10. Specifically, the rotating body 22 of the rotor 20 generates a magnetic force that acts on the stator 10. The direction of the main magnetic flux generated by the rotor 20 (rotating body 22) is in the direction of the axis C of the rotating shaft 21.

[0024] The rotating shaft 21 is a shaft having an axis C, and is a long, rod-shaped member. For example, the rotating shaft 21 is a metal rod made of a metal material such as SUS (Steel Use Stainless). The axis C of the rotating shaft 21 is the center of rotation when the rotor 20 rotates. The longitudinal direction of the rotating shaft 21, that is, the direction in which the rotating shaft 21 extends (extension direction), is the direction of the axis C.

[0025] The rotating shaft 21 is supported by a first bearing 31 and a second bearing 32. Specifically, one end of the rotating shaft 21, the first end 21a, is supported by the second bearing 32. On the other hand, the other end of the rotating shaft 21, the second end 21b, is supported by the first bearing 31. The rotating shaft 21 is press-fitted into the first bearing 31 and the second bearing 32. The first bearing 31 and the second bearing 32 support the rotating shaft 21 so that it can rotate freely. For example, each of the first bearing 31 and the second bearing 32 is a bearing such as a ball bearing. The first bearing 31 and the second bearing 32 are the same bearing. However, this is not limited to this.

[0026] The first end 21a of the rotating shaft 21 is the output end (output shaft). The first end 21a protrudes from the second bracket 80 and the second bearing 32. A load, such as a rotating fan, can be attached to the first end 21a. The motor 1 with a rotating fan attached to the rotating shaft 21 can be used, for example, as a cooling fan or an electric blower. The second end 21b of the rotating shaft 21 is the non-output end (non-output shaft). The second end 21b does not protrude from the first bracket 70 and the first bearing 31.

[0027] The first bearing 31 is held by the first bracket 70. Specifically, the first bearing 31 is fixed to a recess provided in the first bracket 70. The second bearing 32 is held by the second bracket 80. Specifically, the second bearing 32 is fixed to a recess provided in the second bracket 80.

[0028] A rotating body 22 is fixed to the rotating shaft 21. Therefore, the rotating body 22 rotates together with the rotating shaft 21 as the rotor 20 rotates. The rotating body 22 is a disc-shaped rotating plate. As shown in Figures 3 and 4, the rotating body 22 has a plurality of coils 210 and a resin plate 220 made of resin that molds the plurality of coils 210.

[0029] Here, the detailed structure of the rotating body 22 will be described with reference to Figures 3 and 4, and using Figures 5 to 7. Figure 5 is a perspective view of the rotor 20 according to the embodiment, viewed from above. Figure 6 is a perspective view of the rotor 20 according to the embodiment, viewed from below. Figure 7 is a perspective view of the resin plate 220 in the rotating body 22 of the rotor 20 according to the embodiment.

[0030] The coils 210 shown in Figures 3 and 4 are wound coils. In this embodiment, each of the plurality of coils 210 is an armature winding made of electric wire. Each of the plurality of coils 210 is wound in such a way that it generates a magnetic force that acts on the stator 10 when current flows through it. The direction of the main magnetic flux generated by each coil 210 is along the axis C direction of the rotation axis 21. Specifically, each of the plurality of coils 210 is wound in a flattened shape. The coil surface of each of the plurality of coils 210 is positioned to face along the axis C direction of the rotation axis 21. In other words, the coil axis of the coil 210 is parallel to the axis C direction of the rotation axis 21.

[0031] Each coil 210 is composed of an insulated wire having a core wire made of a metal such as copper or aluminum, and an insulating film covering the core wire. In this embodiment, each of the plurality of coils 210 is a thin wound coil having a coil layer in which the insulated wire is wound in a planar manner. Specifically, each of the plurality of coils 210 is composed of, for example, one or more coil layers in which the insulated wire is wound substantially in a fan shape when viewed in plan view. The plurality of coils 210 configured in this way are arranged to surround the rotation axis 21 when viewed from the direction of the axis C of the rotation axis 21. The plurality of coils 210 are arranged in an annular shape to surround the rotation axis 21 such that the coil axes are oriented in the direction of the axis C of the rotation axis 21.

[0032] Each of the multiple coils 210 is electrically connected to the commutator 40. Specifically, each of the multiple coils 210 is electrically connected to one of the multiple commutator segments 41 of the commutator 40. Therefore, current flows through each of the multiple coils 210 via the commutator segment 41 in contact with the brush 50.

[0033] Multiple coils 210 are covered by a resin plate 220. Specifically, the multiple coils 210 are molded by the resin that constitutes the resin plate 220. For example, the multiple coils 210 are resin-molded so as to be embedded in the resin plate 220. In other words, the multiple coils 210 are integrally molded with the resin plate 220 by being covered by the resin (molding resin) that constitutes the resin plate 220. As the material of the resin that constitutes the resin plate 220, insulating resin materials such as phenolic resin or unsaturated polyester (BMC (Bulk Molding Compound)) can be used. The resin that constitutes the resin plate 220 may be either a thermosetting resin or a thermoplastic resin.

[0034] As shown in Figures 3 and 4, the resin plate 220 has a thin-walled portion 221 and a thick-walled portion 222. The thin-walled portion 221 is thinner than the thick-walled portion 222. In other words, the thick-walled portion 222 is thicker than the thin-walled portion 221. For example, the maximum thickness of the thick-walled portion 222 is more than twice the thickness of the thin-walled portion 221. In this embodiment, the thick-walled portion 222 is thicker than the thin-walled portion 221 so as to protrude toward the stator 10 side (second bracket 80 side).

[0035] As shown in Figures 5 and 7, the thin-walled portion 221 is located outside the thick-walled portion 222 when viewed from the axis C direction of the rotation axis 21. The thin-walled portion 221 is the main body of the resin plate 220. As shown in Figures 3 and 4, coils 210 are arranged in the thin-walled portion 221. Specifically, multiple coils 210 are embedded in the thin-walled portion 221. In this embodiment, the thickness of the thin-walled portion 221 is constant, and the thin-walled portion 221 is formed in an annular shape with a constant width. Therefore, the plan view shape of the outer shape of the thin-walled portion 221 is circular. Since the outer shape of the thin-walled portion 221 constitutes the outer shape of the resin plate 220, the plan view shape of the outer shape of the resin plate 220 is circular.

[0036] As shown in Figures 5 and 7, the thickened portion 222 is located in the center of the resin plate 220. As shown in Figures 3 and 4, the thickened portion 222 is connected to the commutator 40, and the commutator 40 and the thickened portion 222 are fixed to each other. By fixing the thickened portion 222 to the commutator 40, which is fixed to the rotating shaft 21, the resin plate 220 is fixed to the rotating shaft 21. In other words, the rotating body 22 is fixed to the rotating shaft 21.

[0037] As shown in Figures 3 and 4, the resin plate 220 configured in this way is located between the first bracket 70 and the second bracket 80. The thin-walled portion 221 of the resin plate 220 is located between the stator 10 (magnet) which is positioned on the inner surfaces of the first bracket 70 and the second bracket 80. Specifically, the thin-walled portion 221 faces both the first bracket 70 and the stator 10 (magnet). The rotating body 22 rotates without contacting the stator 10 and the first bracket 70. Therefore, there is a gap between the resin plate 220 (thin-walled portion 221) and the stator 10, and there is also a gap between the resin plate 220 (thin-walled portion 221) and the first bracket 70. In order to miniaturize the electric motor 1, these gaps are small.

[0038] As shown in Figures 3 and 4, the resin plate 220 has a first surface 220a perpendicular to the axis C direction of the rotation axis 21, and a second surface 220b located on the opposite side of the first surface 220a. The first surface 220a is the surface on the stator 10 side (magnet side). The second surface 220b is the surface on the first bracket 70 side (i.e., the brush holder 60 side). The first surface 220a and the second surface 220b of the thin-walled portion 221 are planes perpendicular to the axis C direction of the rotation axis 21. The first surface 220a of the thin-walled portion 221 faces the stator 10 (magnet). The second surface 220b of the thin-walled portion 221 faces the stator 10 side surface of the first bracket 70.

[0039] A rib 223 is provided on at least one of the first surface 220a and the second surface 220b of the resin plate 220, projecting in the direction of the axis C of the rotation shaft 21. As shown in Figures 3 to 7, the rib 223 is provided on the first surface 220a (the magnet side) of the resin plate 220. The rib 223 is part of the resin plate 220. In other words, the rib 223 is made of the resin that makes up the resin plate 220. Therefore, the rib 223 is formed when the resin plate 220 is molded by molding a plurality of coils 210 with resin.

[0040] The rib 223 is a projection that protrudes from the first surface 220a of the resin plate 220. Specifically, the rib 223 is a projection wall erected on the first surface 220a of the resin plate 220. The rib 223 is elongated. The rib 223 is formed as a ridge. The rib 223 is provided on the thin-walled portion 221 of the resin plate 220. The rib 223 is provided on the radial tip portion that extends outward from the axis C of the resin plate 220. In other words, the rib 223 is provided on the tip portion of the thin-walled portion 221 of the resin plate 220. Therefore, the cross-section of the rib 223 and the thin-walled portion 221 is formed in an L-shape.

[0041] As shown in Figure 5, the ribs 223 are arranged in an annular shape centered on the axis C of the rotating shaft 21. The ribs 223 face the side surface of the magnet, which is the stator 10. In other words, the rotating body 22 is positioned such that the annular ribs 223 surround the resin plate 220 of the magnet, which is the stator 10.

[0042] In this embodiment, the rib 223 is a continuous annular shape that is not interrupted. However, it is not limited to this. That is, the annular rib 223 may be partially interrupted by a notch. In this case, the annular rib 223 may have only one notch, or it may have multiple notches. If the rib 223 has multiple notches, the rib 223 is divided into multiple parts. In this case, for example, the annular rib 223 may be composed of multiple arc-shaped arc sections.

[0043] In the present embodiment, the rib 223 is a single annular protrusion. However, it is not limited to this. For example, a plurality of ribs 223 may be provided concentrically. Specifically, the rib 223 may be constituted by two annular protrusions provided concentrically. In this case, both of the two ribs 223 may be provided at the tip portion of the resin plate 220. Alternatively, one of the two ribs 223 may be provided at the tip portion in the radial direction of the resin plate 220, and the other of the two ribs 223 may be provided at the central portion in the radial direction of the resin plate 220.

[0044] As shown in FIGS. 3 and 4, the rotating body 22 is disposed to face the stator 0. In the present embodiment, the rotating body 22 faces the stator 10 in the axial direction C of the rotating shaft 21. Specifically, the coil 210 of the rotating body 22 and the stator 10 face each other along the axial direction C of the rotating shaft 21. That is, the coil 210 and the stator 10 are arranged side by side in the axial direction C of the rotating shaft 21.

[0045] In the present embodiment, the rotor 0 is a coreless rotor having no core. That is, the motor 1 is a coreless motor in which the rotor 20 has no core. In the motor 1, the plurality of coils 210 of the rotor 20 are thin and resin-molded. Thereby, a thin motor 1 with low inductance and flattened shape can be realized.

[0046] As shown in FIGS. 3 and 4, a commutator 40 is attached to the rotating shaft 21 of the rotor 20. The commutator 40 is fixed to the rotating shaft 21. Therefore, the commutator 40 rotates together with the rotating shaft 21 as the rotor 20 rotates. In the present embodiment, the commutator 40 is attached to the second end portion 21b side of the rotating shaft 21. The commutator 40 attached to the rotating shaft 21 may be a part of the rotor 20. The diameter of the commutator 40 on the side of the first bearing 31 is the same as the diameter of the first bearing 31. However, it is not limited to this.

[0047] The commutator 40 has a plurality of commutator segments 41 provided along the rotation direction of the rotary shaft 21. Specifically, the plurality of commutator segments 41 are arranged in an annular shape along the rotation direction of the rotary shaft 21 so as to surround the rotary shaft 21. The shape of each commutator segment 41 is a long member extending in the longitudinal direction of the rotary shaft 21.

[0048] Each of the plurality of commutator segments 41 is a conductive terminal made of a metal material such as copper. Each of the plurality of commutator segments 41 is electrically connected to the coil 210 of the rotor 20. The plurality of commutator segments 41 are arranged separately from each other. The plurality of commutator segments 41 are electrically connected by the coil 210.

[0049] As an example, the commutator 40 is a molded commutator. In the commutator 40, the plurality of commutator segments 41 are molded by the molding resin 42. In this case, the plurality of commutator segments 41 are embedded in the molding resin 42 so that the surfaces are exposed. The molding resin 42 is the commutator body. The molding resin 42 is a substantially cylindrical member having a through hole into which the rotary shaft 21 is inserted. The molding resin 42 is a resin molded body made of an insulating resin material such as a thermosetting resin.

[0050] As shown in FIG. 3, a brush 50 is in contact with the commutator 40. Although not shown, each of the pair of brushes 50 is in contact with the commutator 40. Specifically, the pair of brushes 50 are in contact with the commutator segments 41 of the commutator 40. Since the commutator 40 rotates due to the rotation of the rotary shaft 21, the pair of brushes 50 continue to sequentially contact all the commutator segments 41.

[0051] The pair of brushes 50 are arranged in the brush holder 60. Specifically, each of the pair of brushes 50 is arranged in the brush holder 60 such that its longitudinal direction is perpendicular to the axis C of the rotary shaft 21 (that is, in the radial direction of the rotation of the rotary shaft 21). Each of the pair of brushes 50 is housed in the brush housing portion 61 of the brush holder 60.

[0052] The pair of brushes 50 are arranged such that the angle between them is less than 180°. In other words, the angle between the pair of brushes 50 is less than 180°. Specifically, the angle between the longitudinal direction of one brush 50 and the longitudinal direction of the other brush 50 is less than 180°. In this embodiment, the angle between the pair of brushes 50 is less than 90°, for example, 60°. In this case, the pair of brushes 50 are arranged in a positional relationship that forms a "V" shape when viewed from above. Note that the angle between the pair of brushes 50 may be 180°. In other words, the pair of brushes 50 may be arranged symmetrically with respect to the axis C of the rotation axis 21.

[0053] Brush 50 is a power supply brush (conducting brush) that supplies power to the coil 210. Specifically, brush 50 supplies power to the coil 210 by contacting the commutator segment 41 of the commutator 40. When brush 50 contacts the commutator segment 41, the armature current supplied to brush 50 from the power supply terminal flows to the coil 210 via the commutator segment 41. The power supply terminal is attached to the brush holder 60. Brush 50 and the power supply terminal are connected by a pigtail wire. Part of the pigtail wire is embedded in brush 50 and is drawn out from brush 50.

[0054] The brush 50 is a conductive material. For example, the brush 50 is a long, substantially rectangular carbon brush made of carbon. The brush 50 may be a carbon brush containing a metal such as copper. This reduces the contact resistance between the brush 50 and the commutator piece 41. Such a brush 50 can be made, for example, by crushing a mixture of graphite powder, copper powder, binder resin, and hardener, compressing it into a rectangular parallelepiped, and firing it.

[0055] As shown in Figure 3, the brush 50 includes a front end 50a that contacts the commutator 40 and a rear end 50b located on the opposite side from the front end 50a. The front end 50a of the brush 50 is one end in the longitudinal direction of the brush 50. Specifically, the front end 50a of the brush 50 is the tip on the side of the rotating shaft 21 (radially inward). The front end surface of the front end 50a is the contact surface that contacts the commutator segment 41 of the commutator 40. The rear end 50b of the brush 50 is the other end in the longitudinal direction of the brush 50. Specifically, the rear end 50b of the brush 50 is the tip on the side of the rotating shaft 21 (radially outward). The rear end surface of the rear end 50b is the contact surface that contacts the brush spring 51.

[0056] The brush spring 51, along with the brush 50, is housed in the brush storage section 61 of the brush holder 60. The brush 50 and brush spring 51 housed in the brush storage section 61 are covered by a cover plate 52. The cover plate 52 is made of, for example, a metal plate. The cover plate 52 is positioned to cover the brush storage section 61.

[0057] The brush 50 is mounted so as to be constantly in contact with the commutator segment 41 of the commutator 40, due to the pressing force from the brush spring 51. In other words, the brush 50 is pressed against the commutator 40 by the brush spring 51.

[0058] The brush spring 51 applies pressure (spring pressure) to the brush 50 by its spring elastic force (spring restoring force), biasing the brush 50 toward the commutator 40. In this embodiment, the brush spring 51 is a compression coil spring. The brush spring 51 is not limited to a compression coil spring; it may also be a constant load spring or a torsion spring, etc.

[0059] The brush spring 51 is positioned behind the brush 50 such that one end of the brush spring 51 in the direction of expansion and contraction contacts the rear end surface of the rear end 50b of the brush 50. As a result, the pressing force from the brush spring 51 causes the longitudinal front end 50a of the brush 50 to always contact the commutator piece 41. In this way, as the brush 50 wears down due to friction with the commutator piece 41, the pressing force from the brush spring 51 causes it to move in the direction toward the axis C of the rotating shaft 21 (radial direction).

[0060] The brush 50 is supplied with power from an external power source located outside the motor 1 via power terminals. The external power source is a power source located outside the motor 1. The external power source supplies a predetermined input voltage to the motor 1. In this embodiment, the external power source is a DC power source that supplies a DC 12V input voltage to the motor 1. The power terminals receive a DC voltage as input voltage via a pair of power supply lines 2 shown in Figures 1 and 2. The pair of power supply lines 2 are power lines for supplying power to the motor 1. Power is supplied from the external power source to the power terminals via the pair of power supply lines 2, and current is supplied to the brush 50 via a pigtail wire connected to the power terminals.

[0061] The brush holder 60 is a holding member that holds the brush 50. The brush holder 60 is made of, for example, an insulating resin material. In this embodiment, the brush holder 60 is a resin molded product formed by integral molding using a resin material. As shown in Figures 3 and 4, in this embodiment, the brush holder 60 is an outer shell member that constitutes the outer shell of the electric motor 1. The brush holder 60 covers the first bracket 70 from the outside.

[0062] As shown in Figure 3, the brush holder 60 has a brush storage section 61 in which the brushes 50 are housed. Although not shown, in this embodiment, two brushes 50 are arranged in the brush holder 60. Therefore, the brush holder 60 is provided with two brush storage sections 61. The brush storage section 61 is a brush box formed in a concave shape on the inner surface of the brush holder 60. In this embodiment, the brush storage section 61 is elongated in a direction perpendicular to the axis C of the rotation axis 21 (i.e., in the radial direction of rotation of the rotation axis 21), and its cross-sectional shape is concave.

[0063] The first bracket 70 covers the brush holder 60. Specifically, the first bracket 70 is positioned to cover the opening of the brush holder 60. In this embodiment, the first bracket 70 covers the entire brush holder 60.

[0064] The first bracket 70 is positioned between the second bracket 80 and the brush holder 60. Specifically, the first bracket 70 is sandwiched between the second bracket 80 and the brush holder 60. In this embodiment, the housing is formed by the first bracket 70 and the second bracket 80. The stator 10 and the rotor 20 are arranged inside this housing.

[0065] The second bracket 80 is an outer shell member of the electric motor 1. The second bracket 80 is formed in a closed-bottom cylindrical shape having a bottom and cylindrical side walls. The magnets constituting the stator 10 are fixed to the bottom of the second bracket 80. The rotating body 22 of the rotor 20 is surrounded by the side walls of the second bracket 80.

[0066] The first bracket 70 and the second bracket 80 are made of, for example, a metal material. For example, the first bracket 70 and the second bracket 80 are made of an iron-based material such as cold-rolled steel sheet (SPC (Steel Plate Cold) material) or a metal such as aluminum. The material of the first bracket 70 and the second bracket 80 is not limited to a metal material, but may also be a resin material. However, from the viewpoint of suppressing noise generated from the electric motor 1, it is preferable that the first bracket 70 and the second bracket 80 are made of a metal material.

[0067] In this embodiment, the first bracket 70 and the second bracket 80 are formed into a predetermined three-dimensional shape by applying a predetermined press working or the like to a metal plate. The first bracket 70 is formed to have a recess in which the commutator 40 and the first bearing 31 are arranged. The second bracket 80 is formed in a low-profile, bottomed cylindrical shape. The first bracket 70 may also be a flat metal plate. In this case, the first bracket 70 is provided with through holes into which the commutator 40 and the first bearing 31 are inserted.

[0068] In the electric motor 1 configured as described above, when power is supplied to the power terminals via the power supply line 2, that power is supplied to the brushes 50 via the power terminals. As a result, the armature current (drive current) flows to the coils 210 of the rotor 20 via the commutator 40 in contact with the brushes 50, generating a magnetic flux in the rotor 20 (coils 210). The magnetic force generated by the interaction between the magnetic flux generated in the rotor 20 and the magnetic flux generated by the stator 10 becomes the torque that rotates the rotor 20. At this time, the direction of the current flowing through the coils 210 is switched depending on the positional relationship when the commutator piece 41 and the brushes 50 are in contact. By switching the direction of current flow in this way, a rotational force in a constant direction is generated by the repulsive and attractive magnetic forces generated between the stator 10 and the rotor 20. As a result, the rotor 20 rotates around the axis C of the rotation shaft 21.

[0069] Next, the features of the rotor 20 and electric motor 1 according to the embodiment will be described in comparison with the comparative example electric motor 1X shown in Figure 8. Figure 8 is a cross-sectional view of the comparative example electric motor 1X.

[0070] The comparative example electric motor 1X shown in Figure 8 has a structure in which the rotating body 22X of the rotor 20X does not have ribs 223, compared to the electric motor 1 according to the above embodiment. Otherwise, the comparative example electric motor 1X and the electric motor 1 according to the above embodiment have the same configuration. Therefore, the rotating body 22X of the rotor 20X of the comparative example electric motor 1X has a plurality of coils 210 arranged to surround the rotating shaft 21 and a resin plate 220 made of resin that molds the plurality of coils 210.

[0071] In the comparative example motor 1X configured in this way, when the environment in which the motor 1X is used becomes hot, the resin plate 220 in the rotating body 22X may deform by bending, as shown by the dashed line in Figure 8. Specifically, the resin plate 220 deforms so that the tip portion of the resin plate 220 bends toward the stator 10 side (magnet side).

[0072] The reason why the resin plate 220 deforms in this way is not clear. However, the inventors have investigated and suspected that the deformation of the resin plate 220 is due to residual stress remaining inside the resin plate 220. Specifically, the resin plate 220 has a thin-walled portion 221 and a thick-walled portion 222. The thin-walled portion 221 and the thick-walled portion 222 have different thicknesses in parts. As a result, when the resin plate 220 is molded with liquid resin, the resin that is heated cools differently in the parts with different thicknesses. Therefore, the thin-walled portion 221 cools and hardens earlier than the thick-walled portion 222 because it is thinner. As a result, it is thought that residual stress remains inside the thin-walled portion 221. In particular, the tip of the thin-walled portion 221 cools more easily, so residual stress is likely to remain in the tip of the thin-walled portion 221.

[0073] Thus, when the rotor 20X and motor 1X are assembled with residual stress remaining in the thin-walled portion 221 of the resin plate 220, and the product using that motor 1X is exposed to a high-temperature environment, the residual stress inside the resin plate 220 in the motor 1X is released. As a result, it is thought that the resin plate 220 deforms by bending. Furthermore, the thick-walled portion 222 is thicker so as to protrude toward the stator 10 side relative to the thin-walled portion 221. For this reason, as shown by the dashed line in Figure 8, it is thought that the thin-walled portion 221 bends so that its tip approaches the stator 10 side.

[0074] If the resin plate 220 of the rotating body 22X in the rotor 20X deforms, the resin plate 220 may come into contact with the stator 10 (magnet) which is positioned close to the rotating body 22X, causing the electric motor 1X to lock up.

[0075] In contrast, the rotor 20 of the electric motor 1 according to this embodiment is provided with ribs 223 on the resin plate 220 of the rotating body 22.

[0076] In this way, the resin plate 220 is reinforced by the ribs 223 provided on it. In other words, the ribs 223 function as reinforcing ribs. This prevents the resin plate 220 from deforming, such as by warping. For example, even if residual stress remains inside the resin plate 220 and the electric motor 1 is exposed to a high-temperature environment, warping of the resin plate 220 can be suppressed.

[0077] Furthermore, in the electric motor 1 according to this embodiment, the rib 223 is an annular shape centered on the axis C that contains the rotating shaft 21.

[0078] This configuration allows the resin plate 220 to be reinforced around the entire circumference of the rib 223. This further suppresses deformation of the resin plate 220.

[0079] Furthermore, in the electric motor 1 according to this embodiment, the rib 223 is provided on the radial tip portion of the resin plate 220 that extends toward the outer circumference.

[0080] With this configuration, even if the resin plate 220 has a thin-walled portion 221 and a thick-walled portion 222, and the radial tip of the resin plate 220 is prone to warping due to residual stress remaining in the thin-walled portion 221, the presence of ribs 223 at the radial tip of the resin plate 220 effectively suppresses warping of the resin plate 220 due to residual stress in the thin-walled portion 221.

[0081] Furthermore, in the electric motor 1 according to this embodiment, the first surface 220a of the resin plate 220 is the surface on the stator 10 side (the surface on the magnet side). The rib 223 is provided on the first surface 220a of the resin plate 220.

[0082] This configuration effectively suppresses deformation of the resin plate 220 due to compressive stress.

[0083] Furthermore, in the electric motor 1 according to this embodiment, the rib 223 that protrudes from the resin plate 220 toward the stator 10 is facing the side surface of the magnet which is the stator 10.

[0084] This configuration allows the distance between the resin plate 220 in which the coil 210 is embedded and the stator 10 (magnet) to be reduced compared to the case where the rib 223 faces the main surface of the magnet. Therefore, a high-performance and compact electric motor 1 can be realized.

[0085] (Modification) The electric motor 1 and rotor 20 according to the present disclosure have been described above based on embodiments. However, the present disclosure is not limited to the above embodiments.

[0086] In the following section, modified examples of the electric motor 1 and rotor 20 according to the above embodiment will be described with reference to the drawings.

[0087] (Modification 1) First, the rotor 20A according to Modification 1 will be explained using Figure 9. Figure 9 is a perspective view of the rotor 20A according to Modification 1.

[0088] As shown in Figure 9, in the rotor 20A according to this modified example, ribs 223A are provided on the resin plate 220 of the rotating body 22A, similar to the rotor 20 according to the above embodiment. However, the structure of the ribs 223A of the rotor 20A according to this modified example is different from that of the ribs 223 of the rotor 20 according to the above embodiment.

[0089] Specifically, in this modified example, the rib 223A has a portion where the height of the rib 223A is partially reduced, which is a low-strength portion of the rib 223A. More specifically, the rib 223A has a structure in which a first portion 223a and a second portion 223b of different heights alternate along the circumferential direction of the rotating body 22A. The first portion 223a is a portion that is taller than the second portion 223b, and the second portion 223b is a portion that is shorter than the first portion 223a. As an example, the rib 223A has a wave-like shape. In this case, the side view shape of the first portion 223a is a curved shape that is convex upwards, and the side view shape of the second portion 223b is a curved shape that is convex downwards.

[0090] In the rotor 20A configured in this way, similar to the rotor 20 in the above embodiment, ribs 223A are provided on the resin plate 220 of the rotating body 22A.

[0091] This configuration reinforces the resin plate 220 with the ribs 223A. Therefore, deformation of the resin plate 220 can be suppressed.

[0092] Furthermore, in this modified example, the rib 223A has a low-strength portion that is partially weaker. Specifically, the rib 223A has a portion where the height of the rib 223A is partially reduced as the low-strength portion. In this modified example, the low-strength portion of the rib 223A is the second portion 223b, which is lower in height.

[0093] This configuration makes the second portion 223b, which is a low-strength part, more easily deformable (for example, more prone to bending) than the first portion 223a. As a result, when the rotor 20A is exposed to a high-temperature environment and the resin plate 220 attempts to deform, the stress that occurs when the resin plate 220 deforms can be released in the low-strength part (second portion 223b). This effectively suppresses the deformation of the resin plate 220. Thus, in this modified example, by deliberately providing a deformable low-strength part (second portion 223b) in the rib 223A, the deformation of the resin plate 220 is effectively suppressed.

[0094] (Modification 2) Next, the rotor 20B according to Modification 2 will be described using Figures 10 and 11. Figure 10 is a perspective view of the rotor 20B according to Modification 2 as seen from above. Figure 11 is a perspective view of the rotor 20B according to Modification 2 as seen from below.

[0095] As shown in Figures 10 and 11, in the rotor 20B according to this modified example, ribs 223B are provided on the resin plate 220 of the rotating body 22B, similar to the rotor 20 according to the above embodiment. However, the structure of the ribs 223B of the rotor 20B according to this modified example is different from that of the ribs 223 of the rotor 20 according to the above embodiment.

[0096] In this modified example, as in the first modified example, the rib 223B has a low-strength portion where the strength of the rib 223B is partially lower. Specifically, the rib 223B has a through hole 223c and a recess 223d formed as the low-strength portion.

[0097] The through-hole 223c penetrates the inner and outer surfaces of the rib 223B. The through-hole 223c is formed at the base of the rib 223B. In this modified example, the through-hole 223c is slit-shaped. The through-hole 223c extends in the circumferential direction of the rotating body 22B. Multiple through-holes 223c are provided along the circumferential direction of the rotating body 22B.

[0098] The recesses 223d are formed to recess the outer surface of the rib 223B and the outer surface of the resin plate 220. The recesses 223d extend to the second surface 220b of the resin plate 220. Multiple recesses 223d are provided along the circumferential direction of the rotating body 22B.

[0099] The through-hole 223c is provided in the recess 223d. In other words, the through-hole 223c is provided in the rib 223B which has been thinned by the recess 223d. This makes it possible to reduce the strength of the area surrounding the through-hole 223c compared to when the through-hole 223c is provided in a place other than the recess 223d. In this modified example, the width of the recess 223d and the width of the through-hole 223c are the same. However, it is not limited to this.

[0100] In the rotor 20B configured in this way, similar to the rotor 20 in the above embodiment, ribs 223B are provided on the resin plate 220 of the rotating body 22B.

[0101] This configuration reinforces the resin plate 220 with the ribs 223B. Therefore, deformation of the resin plate 220 can be suppressed.

[0102] Furthermore, in this modified example, the rib 223B has a through hole 223c formed therein, which is a low-strength portion with partially lower strength.

[0103] This configuration makes the area around the through-hole 223c, which is a low-strength section, more easily deformable. Therefore, when the rotor 20B is exposed to a high-temperature environment and the resin plate 220 attempts to deform, the stress generated during the deformation of the resin plate 220 can be released in the low-strength section (the area around the through-hole 223c). This effectively suppresses the deformation of the resin plate 220.

[0104] Furthermore, in this modified example, a recess 223d is formed in the rib 223B as a low-strength portion with partially lower strength.

[0105] This configuration makes the recessed portion 223d, which is a low-strength area, more easily deformable. Therefore, the stress that occurs when the resin plate 220 deforms can be relieved by the recessed portion 223d. This effectively suppresses deformation of the resin plate 220.

[0106] Furthermore, in this modified example, the through-hole 223c is provided in the recess 223d. Therefore, the strength of the area surrounding the through-hole 223c can be further reduced. This allows the stress that occurs when the resin plate 220 deforms to be effectively released in the low-strength area (the area surrounding the through-hole 223c). As a result, deformation of the resin plate 220 can be suppressed even more effectively.

[0107] (Modification 3) Next, the rotor 20C according to Modification 3 will be described using Figures 12 and 13. Figure 12 is a perspective view of the rotor 20C according to Modification 3, viewed from above. Figure 13 is a perspective view of the rotor 20C according to Modification 3, viewed from below.

[0108] As shown in Figures 12 and 13, in the rotor 20C according to this modified example, ribs 223C are provided on the resin plate 220 of the rotating body 22C, similar to the rotor 20 according to the above embodiment. However, the structure of the ribs 223C of the rotor 20C according to this modified example is different from the ribs 223 of the rotor 20 according to the above embodiment.

[0109] In this modified example, the rib 223C also has a low-strength portion where the strength of the rib 223C is partially lower, similar to modified examples 1 and 2 above. Specifically, the rib 223C has a through hole 223c and a recess 223d formed as the low-strength portion, similar to modified example 2. In this modified example, the rib 223C further has a portion where the height of the rib 223C is partially reduced, which is a low-strength portion. Specifically, the rib 223C has a notch 223e as the portion where the height of the rib 223C is partially reduced (low-strength portion). As an example, the shape of the notch 223e is rectangular. Multiple notches 223e are provided along the circumferential direction of the rotating body 22C. Specifically, the multiple notches 223e are provided such that the notches 223e and recesses 223d alternately exist on the outer circumferential surface of the rotating body 22C. The notches 223e may be formed in the shape of a narrow slit.

[0110] In the rotor 20C configured in this way, similar to the rotor 20 in the above embodiment, ribs 223C are provided on the resin plate 220 of the rotating body 22C.

[0111] This configuration reinforces the resin plate 220 with the ribs 223C. However, deformation of the resin plate 220 can be suppressed.

[0112] Furthermore, in this modified example, the rib 223C has through holes 223c and recesses 223d formed therein as low-strength portions with partially lower strength.

[0113] With this configuration, similar to the second modification, the stress that occurs when the resin plate 220 deforms can be released in the low-strength areas (the area around the through hole 223c and the recess 223d). Therefore, deformation of the resin plate 220 can be effectively suppressed.

[0114] Furthermore, in this modified example, a notch 223e is formed in the rib 223C as a low-strength portion with partially lower strength.

[0115] This configuration makes the low-strength notched portion 223e more easily deformable. Therefore, the stress that occurs when the resin plate 220 deforms can also be released at the notched portion 223e. This makes it possible to more effectively suppress the deformation of the resin plate 220.

[0116] (Modification 4) Next, the rotor 20D according to Modification 4 will be described using Figures 14 and 15. Figure 14 is a perspective view of the rotor 20D according to Modification 4, viewed from above. Figure 15 is a perspective view of the rotor 20D according to Modification 4, viewed from below.

[0117] As shown in Figures 14 and 15, in the rotor 20D according to this modified example, ribs 223D are provided on the resin plate 220 of the rotating body 22D, similar to the rotor 20 according to the above embodiment. However, the position in which the ribs 223D of the rotor 20D according to this modified example are provided is different from that of the ribs 223 of the rotor 20 according to the above embodiment.

[0118] Specifically, in the above embodiment, the rib 223 is provided on the first surface 220a (the surface on the stator 10 side) of the resin plate 220. On the other hand, in this modified example, the rib 223D is provided on the second surface 220b (the surface on the first bracket 70 side) of the resin plate 220.

[0119] The rib 223D is a protruding wall erected on the second surface 220b of the resin plate 220. The rib 223D is provided at the radial end portion of the resin plate 220. The rib 223D is provided in an annular shape centered on the axis C of the rotation shaft 21.

[0120] In the rotor 20D configured in this way, similar to the rotor 20 in the above embodiment, ribs 223D are provided on the resin plate 220 of the rotating body 22D.

[0121] This configuration reinforces the resin plate 220 with the rib 223D. Therefore, deformation of the resin plate 220 can be suppressed.

[0122] Furthermore, in this modified example, the rib 223D is provided on the second surface 220b of the resin plate 220.

[0123] This configuration allows for balancing the residual stress in the resin plate 220. Therefore, even if the thickened portion 222 is thicker than the thinned portion 221 so as to protrude toward the stator 10, and the leading edge of the resin plate 220 is prone to warping toward the stator 10, the ribs 223D can effectively suppress the warping of the resin plate 220.

[0124] In this modified example, the rib 223D is provided only on the second surface 220b of the resin plate 220, whereas in the above embodiment, the rib 223 is provided only on the first surface 220a of the resin plate 220. However, this is not the only option. In other words, ribs may be provided on both the first surface 220a and the second surface 220b (i.e., both sides) of the resin plate 220.

[0125] (Modification 5) Next, the rotor 20E according to Modification 5 will be described using Figure 16. Figure 16 is a perspective view of the rotor 20E according to Modification 5.

[0126] As shown in Figure 16, in the rotor 20E according to this modified example, ribs 223E are provided on the resin plate 220 of the rotating body 22E, similar to the rotor 20 according to the above embodiment. However, the shape of the ribs 223E of the rotor 20E according to this modified example is different from the ribs 223 of the rotor 20 according to the above embodiment.

[0127] Specifically, in the above embodiment, the ribs 223 are arranged in an annular shape. However, in this modified example, the ribs 223E are arranged radially. Specifically, multiple ribs 223E are formed along the radial direction of the resin plate 220, centered on the axis C of the rotation axis 21.

[0128] In the rotor 20E configured in this way, similar to the rotor 20 in the above embodiment, ribs 223E are provided on the resin plate 220 of the rotating body 22E.

[0129] This configuration reinforces the resin plate 220 with the ribs 223E. Therefore, deformation of the resin plate 220 can be suppressed.

[0130] (Modification 6) Next, the motor 1F and rotor 20F according to Modification 6 will be described with reference to Figure 17. Figure 17 is a cross-sectional view of the motor 1F according to Modification 6.

[0131] As shown in Figure 17, in the rotor 20F according to this modified example, ribs 223 are provided on the resin plate 220 of the rotating body 22F, similar to the rotor 20 according to the above embodiment. However, in the rotor 20F according to this modified example, the shape of the coil 210F of the rotating body 22F is different from that of the rotor 20 according to the above embodiment. Specifically, in this modified example, the coil 210F embedded in the resin plate 220 is positioned up to the ribs 223. For example, the coil 210F is formed in an L-shape in cross-section along the thin-walled portion 221 and the ribs 223 of the resin plate 220. Therefore, the coil 210F faces not only the main surface of the magnet which is the stator 10, but also the side surface of the magnet.

[0132] In the electric motor 1F and rotor 20F configured in this way, ribs 223 are provided on the resin plate 220 of the rotating body 22F, similar to the electric motor 1 and rotor 20 according to the above embodiment.

[0133] This configuration reinforces the resin plate 220 with the ribs 223. Therefore, deformation of the resin plate 220 can be suppressed.

[0134] In this modified example, the coil 210F is positioned up to the rib 223. The coil 210F faces not only the main surface of the magnet, which is the stator 10, but also the side surface of the magnet.

[0135] This configuration improves the performance of the electric motor 1. Specifically, for electric motors of the same external dimensions, a motor with a larger coil component can increase its output. Alternatively, for the same output, a motor with a larger coil component can generate magnetic flux more efficiently, allowing for a smaller external dimension.

[0136] (Other Modifications) The following describes other modifications of the electric motor 1 and rotor 20 according to this disclosure. The following modifications can also be applied to modifications 1 to 6 described above.

[0137] For example, in the above embodiment, the ribs 223 on the rotating body 22 of the rotor 20 are provided at the radial end portion of the resin plate 220. However, it is not limited to this. Specifically, the ribs 223 may be provided at the radial center portion of the resin plate 220, etc. It is preferable that the ribs 223 be provided at a location where the resin plate 220 is prone to deformation due to residual stress inside the resin plate 220.

[0138] Furthermore, in the above embodiment, the electric motor 1 is a coreless motor in which the stator 10 and rotor 20 do not have a core. However, it is not limited to this. For example, the electric motor 1 may be an electric motor in which the stator 10 and rotor 20 have a core. However, by using a coreless motor as in the above embodiment, it is possible to realize an electric motor 1 that has low inductance and is thin.

[0139] Furthermore, in the above embodiment, the stator 10 is composed solely of permanent magnets. However, it is not limited to this. For example, the stator 10 may be a stator composed of permanent magnets and an iron core, or it may be an armature consisting of stator windings and an iron core without using permanent magnets.

[0140] Furthermore, in the above embodiment, the electric motor 1 is a flat motor with an external size having a thickness smaller than the outer diameter. However, it is not limited to this. The technology of this disclosure can also be applied to, for example, a cylindrical electric motor having an external size having a cylindrical housing with a thickness larger than the outer diameter.

[0141] Furthermore, in the above embodiment, the direction of the main magnetic flux generated by the stator 10 and rotor 20 is in the direction of the axis C of the rotation axis 21. However, it is not limited to this. Specifically, the direction of the main magnetic flux generated by the stator 10 and rotor 20 may be in a direction perpendicular to the direction of the axis C of the rotation axis 21 (the radial direction of rotation of the rotation axis 21). Moreover, the technology of this disclosure can also be applied to an inner rotor type motor in which the rotor 20 is arranged inside the stator 10.

[0142] Furthermore, in the above embodiment, the electric motor 1 is an on-board motor used in a vehicle. However, it is not limited to this. The technology of this disclosure can also be applied to electric motors used in various other electrical devices, such as electric motors used in electric blowers mounted on vacuum cleaners, etc.

[0143] Furthermore, forms obtained by applying various modifications to the above embodiments that a person skilled in the art could conceive of, or forms realized by arbitrarily combining the components and functions of each embodiment without departing from the spirit of this disclosure, are also included in this disclosure. Arbitrary combinations of two or more claims from the multiple claims described in the claims of this application, within the scope of which they do not contradict each other, are also included in this disclosure. For example, if the cited claims described in the claims of this application are made into a multi-claim or multi-multi-claim so as to refer to all of the higher-level claims within the scope of which they do not contradict each other, then all combinations of claims included in that multi-claim or multi-multi-claim are also included in this disclosure.

[0144] The technology disclosed herein can be widely used in various products that incorporate electric motors, including products in the fields of automotive electrical systems and household electrical appliances.

[0145] 1, 1F, 1X Electric motor 2 Power supply line 10 Stator 20, 20A, 20B, 20C, 20D, 20E, 20F, 20X Rotor 21 Rotating shaft 21a First end 21b Second end 22, 22A, 22B, 22C, 22D, 22E, 22F, 22X Rotating body 210, 210F Coil 220 Resin plate 220a First surface 220b Second surface 221 Thin-walled section 222 Thick-walled section 223, 223A, 223B, 223C, 223D, 223E Rib 223a First part 223b Second part 223c Through hole 223d Recess 223e Notch 31 First bearing 32 Second bearing 40 Commutator 41 Commutator segment 42 Molded resin 50 Brush 50a Front end 50b Rear end 51 Brush spring 52 Cover plate 60 Brush holder 61 Brush storage section 70 First bracket 80 Second bracket C Axis

Claims

1. A rotor comprising: a rotating shaft extending in the axial direction; and a rotating body fixed to the rotating shaft, wherein the rotating body has a plurality of coils arranged to surround the rotating shaft; and a resin plate made of resin that molds the plurality of coils, the resin plate having a first surface perpendicular to the axial direction and a second surface located opposite to the first surface, and at least one of the first surface and the second surface is provided with a rib protruding along the axial direction.

2. The rotor according to claim 1, wherein the ribs are arranged in an annular shape with respect to the axis containing the rotating shaft.

3. The rotor according to claim 2, wherein the ribs are provided on the radial tip portions that extend outward from the axis of the resin plate.

4. The rotor according to claim 1, wherein the rotor does not have a core.

5. The rotor according to any one of claims 1 to 4, wherein the rib has a low-strength portion with partially lower strength.

6. The rotor according to claim 5, wherein the rib has a portion in which the height of the rib is partially reduced as the low-strength portion.

7. The rotor according to claim 5, wherein through holes are formed in the ribs as the low-strength portions.

8. The rotor according to claim 5, wherein the rib has a portion in which the height of the rib is partially reduced and a through hole formed therein as the low-strength portion.

9. An electric motor comprising a rotor according to any one of claims 1 to 4, and a stator that generates a magnetic force acting on the rotor.

10. The electric motor according to claim 9, wherein the stator is a magnet.

11. The electric motor according to claim 10, wherein the first surface of the resin plate is the surface on the magnet side, and the ribs are provided on the first surface.

12. The electric motor according to claim 11, wherein the rib is facing the side surface of the magnet.

13. The electric motor according to claim 11, wherein the coil is arranged up to the rib.

14. The electric motor according to claim 10, wherein the first surface of the resin plate is the surface on the magnet side, and the ribs are provided on the second surface.

15. The electric motor according to claim 9, wherein the electric motor is of the flat type.

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