Rotor and motor

Abstract

This rotor (4) has a cylindrical shaft (30) that extends in the axial direction, a plastic magnet (40) that annularly covers the outer peripheral surface of the shaft (30) and rotates integrally with the shaft (30), and a blade part (5) that can be attached to and detached from the plastic magnet (40), wherein the plastic magnet (40) has an engagement protrusion (45) that protrudes in the axial direction, and the blade part (5) has an engagement recess (54) that engages with the engagement protrusion (45).

Description

rotor, motor

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

[0002] Brushless DC motors with rotors made of plastic containing magnetic material are known. For example, Patent Document 1 (JP-A-2003-109526) describes a DC motor including an iron-core stator with windings around an iron core, a rotor made of plastic containing magnetic material, a drive magnet, and a back yoke, and a rotating shaft. In this motor, the cylindrical portion of the rotor body is magnetized to serve as a drive magnet.

[0003] Japanese Utility Model Application Laid-Open Publication No. 03-070038

[0004] In the electric motor described in Patent Document 1, in order to detachably mount the blades on the rotating shaft, it is necessary to provide a mechanism for preventing the blades from rotating. One possible mechanism for preventing the blades from rotating is to mount a roll pin in a circumferential groove on the rotating shaft and engage the roll pin with an engaging recess provided on the blade. However, this configuration increases the number of parts, and there is room for improvement from the perspective of reducing the number of parts.

[0005] The present disclosure provides a rotor that can reduce the number of parts.

[0006] A rotor according to one aspect of the present disclosure includes a cylindrical shaft extending in the axial direction, a plastic magnet annularly covering the outer circumferential surface of the shaft and rotating integrally with the shaft, and vanes detachable from the plastic magnet, the plastic magnet having an engaging protrusion protruding in the axial direction, and the vanes having an engaging recess that engages with the engaging protrusion.

[0007] Any combination of the above components, and conversion of the present disclosure into a method, device, system, recording medium, computer program, etc., are also valid aspects of the present disclosure.

[0008] According to the present disclosure, a rotor that can reduce the number of parts can be provided.

[0009] Fig. 1 is a side cross-sectional view schematically showing a motor including a rotor according to an embodiment of the present disclosure. Fig. 2 is a perspective view of a blade portion of the rotor shown in Fig. 1. Fig. 3 is an exploded perspective view showing the motor shown in Fig. 1.

[0010] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the accompanying drawings. Each of the examples described below represents a preferred specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, component placement and connection configurations, steps (processes), and step order shown in the following examples are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following examples, components that are not recited in the independent claims that represent the highest concept of the present disclosure will be described as optional components. Furthermore, in each figure, substantially identical components are assigned the same reference numerals, and redundant explanations will be omitted or simplified.

[0011] Furthermore, terms including ordinal numbers such as first and second are used to describe various components, but these terms are used only to distinguish one component from another and do not limit the components.

[0012] [Example] The configuration of a motor 10 including a rotor 4 according to an example embodiment of the present disclosure will be described with reference to Figures 1 to 3. Figure 1 is a side cross-sectional view that schematically illustrates the motor 10. This figure shows a cross section of the motor 10 cut along a plane that passes through the central axis La of the shaft 30. Figure 2 is a perspective view of the blades of the rotor. Figure 3 is an exploded perspective view of the motor 10. The motor 10 is a brushless DC motor that is suitable for use, for example, in a ventilation fan that rotates blades.

[0013] Hereinafter, for convenience, the direction along the central axis La of the shaft 30 will be referred to as the "axial direction," and the circumferential direction and radial direction of a circle centered on the central axis La in a plane perpendicular to the central axis La will be referred to as the "circumferential direction" and the "radial direction," respectively. Also, a plane perpendicular to the axial direction will be referred to as the "axially perpendicular plane."

[0014] The motor 10 mainly includes a stator 2, a rotor 4, a shaft 30, a first bearing 31, a second bearing 32, and a substrate 50. The stator 2 and the substrate 50 form a stationary body, and the rotor 4 and the shaft 30 form a rotating body.

[0015] The rotor 4 is rotatably supported by the stator 2 via a first bearing 31 and a second bearing 32. The rotor 4 mainly includes a shaft 30, a cup-shaped plastic magnet 40, and blades 5 that are detachable from the plastic magnet 40. The plastic magnet 40 and the blades 5 will be described later.

[0016] The shaft 30 extends cylindrically in the axial direction along the central axis La. The plastic magnet 40 has a hollow cylindrical portion 41 that surrounds the stator core 21 and a fixed end portion 42 that extends from one end of the cylindrical portion 41 to the outer circumferential surface of the shaft 30, and an open end portion 43 is provided at the end of the cylindrical portion 41 opposite the fixed end portion 42.

[0017] The plastic magnet 40 is formed by resin molding such as injection molding using a plastic such as polyamide resin mixed with magnetic powder (hereinafter referred to as "magnetic resin"). The rotor 4 of this embodiment is manufactured by insert molding, in which molten magnetic resin (hereinafter referred to as "molten resin") is poured into a molding die containing the shaft 30. The shaft 30 and the plastic magnet 40 are integrated by insert molding.

[0018] The plastic magnet 40 is a polar anisotropic plastic magnet with a high residual magnetic flux density. The plastic magnet 40 is insert molded while a polar anisotropic magnetic field is applied. A predetermined number of driving magnetic poles are provided on the inner circumferential surface of the cylindrical portion 41 of the plastic magnet 40 by magnetization processing. Due to the characteristics of polar anisotropic magnets, no magnetic poles are formed on the outer circumferential surface of the cylindrical portion 41. For this reason, a back yoke is not provided in this embodiment.

[0019] In the axial direction, the side where the open end 43 is provided relative to the fixed end 42 is referred to as the first direction. In each drawing, the first direction is indicated by the direction of arrow Z1. The first direction side may also be referred to as the lower side, and the opposite side as the upper side. These directional notations do not limit the orientation of the motor 10, and the motor 10 may be used in any orientation.

[0020] The stator 2 mainly includes a stator core 21, a pair of insulators 22, 23 that sandwich the stator core 21 from both sides in the axial direction, a winding 24 wound around the stator core 21 via the insulators 22, 23, a stator base 26, and shaft supports 28, 29. The insulators 22, 23 are resin members formed by molding. The insulators 22, 23 include a first insulator 22 arranged above the stator core 21 and a second insulator 23 arranged below the stator core 21. The stator core 21, the insulators 22, 23, the winding 24, and the substrate 50 are integrated to form a stator unit 25. In this embodiment, four windings 24 are provided at 90° intervals in the circumferential direction.

[0021] The stator base 26 is a disk-shaped member that supports the stator unit 25. The shaft supports 28, 29 are members that rotatably support the base end side of the shaft 30, and include a first shaft support 28 provided on the upper side of the stator base 26 and a second shaft support 29 provided on the lower side of the stator base 26 and engaged with the first shaft support 28.

[0022] The first shaft support portion 28 is formed integrally with the stator base 26. The second shaft support portion 29 is inserted into a central hole 262 of the stator base 26 from below, thereby engaging with the first shaft support portion 28. The washer 34 is fitted into a circumferential groove 35 formed in the shaft 30. The washer 34 functions as a retainer that regulates the axial position of the shaft 30 between the second bearing 32 and the first shaft support portion 28.

[0023] The substrate 50 is a substantially semicircular printed circuit board extending along a plane perpendicular to the axial direction. A Hall element and a drive circuit (neither of which are shown) are mounted on the substrate 50. The Hall element outputs a detection signal that is substantially proportional to the magnetic flux density of the magnetic flux from the drive magnetic pole of the cylindrical portion 41 as it passes through the Hall element. The drive circuit supplies a drive current to the winding 24 based on the detection signal from the Hall element. The lower part of the second insulator 23 is fixed to the substrate 50.

[0024] The operation of the motor 10 will now be described. When a drive current is supplied from the drive circuit to the windings 24 based on the detection signal of the Hall element, a magnetic field corresponding to the drive current is generated around the stator core 21. The interaction between this magnetic field and the drive magnetic poles of the plastic magnets 40 generates a rotational torque in the rotor 4, and the rotor 4 and shaft 30 rotate around the central axis La in response to this torque. As the shaft 30 rotates, the blades 5 connected to the shaft 30 rotate.

[0025] 1 to 3, the plastic magnet 40 and the blade portion 5 will be described. As described above, the rotor 4 has a cylindrical shaft 30 extending in the axial direction, a plastic magnet 40 that annularly covers the outer peripheral surface of the shaft 30 and rotates integrally with the shaft 30, and blade portions 5 that are detachable from the plastic magnet 40.

[0026] The plastic magnet 40 has a hollow cylindrical portion 41 for surrounding the stator core 21, a fixed end portion 42 that extends from one end of the cylindrical portion 41 to the outer circumferential surface of the shaft 30, and an engaging protrusion 45 that protrudes in the axial direction and engages with an engaging recess 54 of the blade portion 5. The engaging recess 54 and the engaging protrusion 45 engage with each other to function as a rotation stopper for the blade portion 5. As no roll pin is used, the number of parts can be reduced.

[0027] The shape of the engaging protrusions 45 is not particularly limited as long as it functions as a rotation stopper. In the embodiment, the engaging protrusions 45 protrude from the fixed end 42 in the axial direction toward the opposite side from the cylindrical portion 41. That is, the engaging protrusions 45 protrude upward from the fixed end 42. In this case, the rotational strength of the engaging protrusions 45 can be increased compared to when the engaging protrusions 45 are provided away from the fixed end 42. The engaging protrusions 45 in the embodiment have a rectangular parallelepiped shape that protrudes upward from the upper end of the fixed end 42 and has a rectangular shape whose longitudinal direction extends radially in a top view. Because the axial inner side of the engaging protrusions 45 contacts the outer peripheral surface of the shaft 30, the rotational strength can be increased compared to when they are separated. The shape and number of the engaging protrusions 45 can be determined through experiments or simulations in order to obtain the desired rotational strength.

[0028] While the number of engaging protrusions 45 is not limited, in the present embodiment, multiple engaging protrusions 45 are provided rotationally symmetrically about the central axis of the shaft 30. That is, multiple engaging protrusions 45 are provided at equal intervals in the circumferential direction. In this case, there are multiple positions in the circumferential direction where the engaging protrusions 45 can fit into the engaging recesses 54, thereby reducing the labor required to attach the blades 5. Furthermore, providing multiple engaging protrusions 45 increases rotational strength. In the present embodiment, two engaging protrusions 45 are provided at 180° intervals in the circumferential direction. Note that the engaging protrusions 45 are not limited to being rotationally symmetrical; they may be provided at equal 120° intervals in the circumferential direction or at unequal intervals. Increasing the number of engaging protrusions 45 in this manner makes it easier to distribute the load when the blades 5 rotate to each engaging protrusion 45. Therefore, when the engaging protrusions 45 are arranged at 120° intervals, the protrusions 45 may protrude less than when they are arranged at 180° intervals. In other words, the protrusion of the engaging protrusion 45 may be shortened as the number of engaging protrusions 45 increases. With this configuration, the recess of the engaging recess 54 can be made shallower by the amount of shortening the protrusion of the engaging protrusion 45, resulting in a reduction in the axial size of the rotor 4 and the motor 10. Furthermore, the engaging protrusion 45 is configured as part of the plastic magnet 40. Therefore, the tip of the engaging protrusion 45 can be magnetized by magnetization. In such a case, by disposing a magnetic material such as metal on the engaging protrusion 45, the engaging protrusion 45 and the engaging recess 54 can be easily engaged by magnetic attraction. In other words, the engaging recess 54 has a magnetism that attracts the engaging protrusion 45, thereby improving the assembly of the rotor 4 and the motor 10.

[0029] As shown in FIG. 2 , the blade portion 5 has a hollow cylindrical fitting tube portion 55 into which the shaft 30 fits, a circular blade hub portion 56 provided radially outward of the fitting tube portion 55, and a plurality of blades 57 protruding radially from the blade hub portion 56. In the embodiment, the blade portion 5 has four blades 57 spaced at predetermined intervals in the circumferential direction. The blade portion 5 also has engagement recesses 54 that engage with the engagement protrusions 45 provided at positions corresponding to the engagement protrusions 45. In the embodiment, two engagement recesses 54 are provided in the fitting tube portion 55 at 180° intervals in the circumferential direction. The engagement recesses 54 are recessed upward from the lower end surface of the fitting tube portion 55 and have a rectangular shape whose longitudinal direction extends radially when viewed from below.

[0030] The engagement recesses 54 may be formed as recesses having a depth equal to or greater than the protruding height of the engagement protrusions 45. With this configuration, when the engagement protrusions 45 and the engagement recesses 54 are engaged, the lower end surface of the fitting tubular portion 55 can abut against the fixed end 42. The abutment of the lower end surface of the fitting tubular portion 55 against the fixed end 42 prevents the blades 5 from being fixed to the shaft 30 in an inclined state. Furthermore, when the protruding height of the engagement protrusions 45 and the depth of the recesses of the engagement recesses 54 are the same, the lower end surface of the fitting tubular portion 55 abuts against the fixed end 42, and the protruding tip of the engagement protrusions 45 abuts against the bottom of the recesses of the engagement recesses 54, making it easier to position the blades 5. In other words, when the protruding height of the engagement protrusions 45 and the depth of the recesses of the engagement recesses 54 are the same, the blades 5 can be stably fixed.

[0031] In the embodiment, the shaft 30 protrudes in the axial direction away from the cylindrical portion 41 beyond the protruding end 46 of the engaging protrusion 45. In this case, it is easier to fix the blade portion 5 to the shaft 30 than if the shaft 30 does not protrude. As shown in FIG. 3 , the shaft 30 has a detachment recess 36 in a portion of the shaft 30 that protrudes beyond the engaging protrusion 45. The detachment recess 36 is a circumferential recess provided in a position that protrudes in the axial direction from the fitting cylindrical portion 55 when the fitting cylindrical portion 55 of the blade portion 5 is fitted onto the shaft 30.

[0032] In this embodiment, a circular end cap 58 is provided to cover the tip of the shaft 30 so that the blade portion 5 attached to the shaft 30 does not come off. The end cap 58 has a detachment mechanism 59 that detachably engages with the detachment recess 36, and is fixed to the shaft 30 by engaging the detachment mechanism 59 with the detachment recess 36.

[0033] The features of the rotor 4 configured as described above will be described below. The rotor 4 has a cylindrical shaft 30 extending in the axial direction, a plastic magnet 40 that annularly covers the outer circumferential surface of the shaft 30 and rotates integrally with the shaft 30, and blades 5 that are detachable from the plastic magnet 40. The plastic magnet 40 has an engaging protrusion 45 that protrudes in the axial direction, and the blades 5 have an engaging recess 54 that engages with the engaging protrusion 45.

[0034] According to this configuration, the plastic magnet 40 has an engaging protrusion 45 that engages with the engaging recess 54 of the blade 5, and the engaging protrusion 45 functions as a rotation stopper, so the number of parts can be reduced compared to when a roll pin or the like is used. Because the engaging protrusion 45 can be formed by resin molding as part of the plastic magnet 40, the number of manufacturing steps can be reduced compared to when a roll pin is attached.

[0035] An outline of one aspect of the present disclosure is as follows.

[0036] [Item 1] A rotor (4) having a cylindrical shaft (30) extending in the axial direction, a plastic magnet (40) annularly covering the outer peripheral surface of the shaft (30) and rotating integrally with the shaft (30), and a blade portion (5) detachable from the plastic magnet (40), wherein the plastic magnet (40) has an engaging protrusion (45) protruding in the axial direction, and the blade portion (5) has an engaging recess (54) that engages with the engaging protrusion (45).

[0037] [Item 2] The rotor (4) according to Item 1, wherein the plastic magnet (40) has a hollow cylindrical portion (41) for surrounding the stator core (21) and a fixed end portion (42) extending from one end of the cylindrical portion (41) to the outer circumferential surface of the shaft (30), and the engaging protrusion (45) protrudes from the fixed end portion (42) to the side opposite the cylindrical portion (41).

[0038] [Item 3] The rotor (4) according to Item 2, wherein the shaft (30) protrudes beyond the protruding end (46) of the engaging protrusion (45) to the side opposite the cylindrical portion (41).

[0039] [Item 4] The rotor (4) according to Item 1, wherein a plurality of engaging protrusions (45) are provided rotationally symmetrically about the central axis of the shaft (30).

[0040] [Item 5] The rotor (4) according to Item 1, wherein a plurality of the engaging protrusions (45) are provided at equal intervals in the circumferential direction of the cylinder.

[0041] [Item 6] The rotor (4) according to Item 5, wherein the engaging protrusions (45) are formed so that the protruding length becomes shorter as the number of the engaging protrusions (45) increases.

[0042] [Item 7] The rotor (4) according to Item 1, wherein the engagement recess (54) has magnetic properties that attract the engagement protrusion (45).

[0043] [Item 8] A motor (10) including the rotor (4) according to any one of items 1 to 7.

[0044] The present disclosure has been described above based on examples. These examples are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component or each treatment process, and that such modifications are also within the scope of the present disclosure.

[0045] In the description of the embodiment, an example in which the rotor 4 does not have a back yoke has been shown, but the present invention is not limited to this. For example, the rotor may include a member that surrounds the outer circumferential surface of the cylindrical portion of the plastic magnet.

[0046] In the description of the embodiment, an example in which the multiple engaging protrusions 45 are arranged at equal intervals in the circumferential direction has been shown, but this is not limiting. For example, the multiple engaging protrusions may be arranged at unequal intervals in the circumferential direction.

[0047] In the description of the embodiment, an example has been shown in which the engaging protrusions 45 come into contact with the outer circumferential surface of the shaft 30, but the present invention is not limited to this. For example, the engaging protrusions may be provided so as not to come into contact with the shaft.

[0048] In the description of the embodiment, the motor 10 is an example of a radial gap type in which the plastic magnet 40 surrounds the stator core 21 via a radial gap, but is not limited to this. The motor may be an axial gap type in which the disk-shaped plastic magnet faces the stator in the axial direction, as long as the engaging protrusions protrude in the axial direction and engage with the engaging recesses in the blades.

[0049] 2 Stator 4 Rotor 5 Blade portion 10 Motor 21 Stator core 22 First insulator 23 Second insulator 24 Winding 25 Stator unit 26 Stator base 28 First shaft support portion 29 Second shaft support portion 30 Shaft 31 First bearing 32 Second bearing 34 Washer 35 Circumferential groove 36 Detachable recess 40 Plastic magnet 41 Cylindrical portion 42 Fixed end portion 43 Open end portion 45 Engaging protrusion 46 Protruding end 50 Base plate 54 Engaging recess 55 Fitting cylindrical portion 56 Blade hub portion 57 Blade 58 End cap 59 Detachable mechanism

Claims

1. A rotor having a cylindrical shaft extending in the axial direction, a plastic magnet that annularly covers the outer surface of the shaft and rotates integrally with the shaft, and a blade portion that can be attached to and detached from the plastic magnet, wherein the plastic magnet has an engaging protrusion that protrudes in the axial direction, and the blade portion has an engaging recess that engages with the engaging protrusion.

2. The rotor according to claim 1, wherein the plastic magnet has a hollow cylindrical portion for surrounding the stator core and a fixed end portion extending from one end of the cylindrical portion to the outer circumferential surface of the shaft, and the engaging protrusion protrudes from the fixed end portion toward the opposite side of the cylindrical portion.

3. The rotor according to claim 2, wherein the shaft protrudes beyond the protruding end of the engaging projection toward the opposite side of the cylindrical portion.

4. A rotor according to claim 1, wherein a plurality of said engaging projections are provided rotationally symmetrically about the central axis of said shaft.

5. The rotor according to claim 1, wherein a plurality of said engaging projections are provided at equal intervals in the circumferential direction of said cylinder.

6. A rotor according to claim 5, wherein the length of the projection of the engaging protrusions is shorter as the number of engaging protrusions increases.

7. The rotor according to claim 1, wherein the engaging recess has a magnetic property that attracts the engaging protrusion.

8. A motor equipped with a rotor according to any one of claims 1 to 7.

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