Rotor, motor

Abstract

To provide a rotor that can reduce the number of parts. [Solution] The rotor 4 in the motor 10 has a cylindrical shaft 30 extending in the axial direction, a plastic magnet 40 that covers the outer circumferential surface of the shaft 30 in an annular shape and rotates integrally with the shaft 30, and a blade portion 5 that is detachable from the plastic magnet 40. The plastic magnet 40 has an axially recessed engagement recess. The blade portion 5 has an engagement projection that engages with the engagement recess.

Description

Technical Field

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

Background Art

[0002] A brushless DC motor including a rotor using a plastic containing a magnetic material is known. For example, Patent Document 1 describes a DC motor including an iron-core type stator having a winding wound around an iron core, a rotor including a rotor body made of a plastic containing a magnetic material, a drive magnet, and a back yoke, and a rotating shaft. In this motor, a cylindrical portion of the rotor body is magnetized to serve as a drive magnet.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the motor described in Patent Document 1, in order to detachably attach the blade portion to the rotating shaft, it is necessary to provide a blade locking mechanism on the rotating shaft. As the locking mechanism, a configuration in which a roll pin is attached to a circumferential groove of the rotating shaft and the roll pin is engaged with an engaging concave portion provided on the blade can be considered. However, in this configuration, the number of parts increases, so there is room for improvement from the viewpoint of reducing the number of parts.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide a rotor capable of reducing the number of parts.

Means for Solving the Problems

[0006] To solve the above problems, a rotor according to one aspect of the present disclosure comprises a cylindrical shaft extending in the axial direction, a plastic magnet covering the outer circumferential surface of the shaft in an annular shape and rotating integrally with the shaft, and a blade portion detachable from the plastic magnet, wherein the plastic magnet has an axially recessed engaging recess, and the blade portion has an engaging projection that engages with the engaging recess. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a rotor that can reduce the number of parts. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic side cross-sectional view showing a motor equipped with a rotor according to Example 1. [Figure 2] Figures 2(a) and 2(b) show the configuration of the rotor in Figure 1. [Figure 3] Figure 1 is a perspective view of the wing section. [Figure 4] Figure 1 is an exploded perspective view showing the motor after it has been disassembled. [Figure 5] Figures 5(a) and 5(b) show the configuration of the rotor according to Example 2. [Figure 6] This is a perspective view of the blade portion according to Example 2. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments for implementing this disclosure will be described with reference to the attached drawings. The embodiments described below all represent preferred specific examples of this disclosure. Therefore, the numerical values, shapes, materials, components, arrangement and connection configurations of components, as well as the steps (processes) and the order of steps 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 concept of this disclosure will be described as arbitrary components. In addition, substantially identical components are denoted by the same reference numerals in each figure, and redundant explanations are omitted or simplified.

[0010] Furthermore, while terms including ordinal numbers such as "first" and "second" are used to describe various components, these terms are used solely to distinguish one component from others, and do not limit the components themselves.

[0011] (Example 1) Referring to Figures 1 to 4, the configuration of the motor 10 equipped with a rotor 4 according to Embodiment 1 will be described. Figure 1 is a schematic side cross-sectional view of the motor 10. This figure shows a cross-section of the motor 10 cut by a plane passing through the central axis La of the shaft 30. Figures 2(a) and 2(b) show the configuration of the rotor 4. In particular, Figure 2(a) is a perspective view of the rotor 4, and Figure 2(b) is a top view of the rotor 4. Figure 3 is a perspective view of the blade portion 5. Figure 4 is an exploded perspective view showing the rotor 4 in disassembled form. The motor 10 is a brushless DC motor suitable for applications such as a ventilation fan that rotates the blade portion 5.

[0012] 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 and radial directions of a circle centered on the central axis La on a plane perpendicular to the central axis La will be referred to as the "circumferential direction" and "radial direction," respectively. Furthermore, a plane perpendicular to the axial direction will be referred to as the "axial orthogonal plane."

[0013] The motor 10 mainly comprises a stator 2, a rotor 4, a shaft 30, a first bearing 31, a second bearing 32, and a base plate 50. The stator 2 and base plate 50 constitute a stationary body, while the rotor 4 and shaft 30 constitute a rotating body.

[0014] The rotor 4 is rotatably supported relative to the stator 2 via a first bearing 31 and a second bearing 32. The rotor 4 mainly comprises a shaft 30, a cup-shaped plastic magnet 40, and a blade portion 5 that is detachable from the plastic magnet 40. The plastic magnet 40 and the blade portion 5 will be described later.

[0015] 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 surface of the shaft 30, with an open end portion 43 provided at the end of the cylindrical portion 41 opposite to the fixed end portion 42.

[0016] The plastic magnet 40 is formed by resin molding such as injection molding using a plastic such as polyamide resin mixed with magnetic material powder (hereinafter referred to as "magnetic resin"). The rotor 4 in the 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.

[0017] 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 applying a magnetic field for polar anisotropy. A predetermined number of drive magnetic poles are provided on the inner circumferential surface of the cylindrical portion 41 of the plastic magnet 40 by a magnetization process. 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, the embodiment does not include a back yoke.

[0018] In the axial direction, the side where the opening end 43 is provided with respect to the fixed end 42 is referred to as the first direction. In each figure, the first direction is shown as the direction of arrow Z1. Also, the side in the first direction may be referred to as the lower side, and the opposite side as the upper side. Such notation of directions does not limit the posture of the motor 10, and the motor 10 can be used in any posture.

[0019] The stator 2 mainly includes a stator core 21, a first insulator 22, a second insulator 23, a winding 24, a stator base 26, a first shaft support portion 28, and a second shaft support portion 29. The first insulator 22 is disposed above the stator core 21, and the second insulator 23 is disposed below the stator core 21. The first insulator 22 and the second insulator 23 sandwich the stator core 21 from both axial sides. The first insulator 22 and the second insulator 23 are resin members formed by mold molding.

[0020] The winding 24 is wound around the stator core 21 via the first insulator 22 and the second insulator 23. The stator core 21, the first insulator 22, the second insulator 23, the winding 24, and the substrate 50 are integrated to form a stator unit 25. In the embodiment, four windings 24 are provided at intervals of 90° in the circumferential direction.

[0021] The stator base 26 is a disk-shaped member that supports the stator unit 25. The first shaft support portion 28 and the second shaft support portion 29 are members that rotatably support the proximal end side of the shaft 30. The first shaft support portion 28 is provided above the stator base 26, and the second shaft support portion 29 is provided below the stator base 26 and engages with the first shaft support portion 28.

[0022] The first shaft support portion 28 is integrally formed with the stator base 26. The second shaft support portion 29 engages with the first shaft support portion 28 by being inserted from below into the central hole 262 of the stator base 26. The washer 34 is fitted into the circumferential groove 35 formed in the shaft 30. The washer 34 functions as a retainer that restricts 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 (both not shown) are mounted on the substrate 50. The Hall element outputs a detection signal approximately proportional to the magnetic flux density of the magnetic flux that passes through the Hall element from the drive magnetic pole of the cylindrical portion 41. 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 explained. When a drive current is supplied from the drive circuit to the winding 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. Due to the interaction between this magnetic field and the drive magnetic poles of the plastic magnet 40, rotational torque is generated in the rotor 4, and in accordance with this torque, the rotor 4 and shaft 30 rotate around the central axis La. As the shaft 30 rotates, the blade portion 5 connected to the shaft 30 also rotates.

[0025] The plastic magnet 40 and the blade portion 5 will be described with reference to Figures 1 to 4. As mentioned above, the rotor 4 has a cylindrical shaft 30 extending in the axial direction, a plastic magnet 40 that covers the outer circumferential surface of the shaft 30 in an annular shape and rotates integrally with the shaft 30, and a blade portion 5 that can be attached to or detached from the plastic magnet 40.

[0026] The plastic magnet 40 has a hollow cylindrical portion 41 for encircling the stator core 21, a fixed end portion 42 extending from one end of the cylindrical portion 41 to the outer circumferential surface of the shaft 30, and a plurality of wall portions 60 protruding from the fixed end portion 42 toward the opposite side of the cylindrical portion 41. The plurality of wall portions 60 are arranged around the shaft 30. This corresponds to being arranged along the circumferential direction of the cylinder. Figures 2(a)-(b) show four wall portions 60, but the number of wall portions 60 is not limited to "4". In addition, the space between a plurality of adjacent wall portions 60 in the circumferential direction is provided as an engagement recess 45. The engagement recess 45 has a shape that is recessed in the axial direction. When the rotor 4 and the blade portion 5 are combined, the engagement recess 45 engages with the engagement projection 54 of the blade portion 5, which will be described later. Therefore, the engagement recess 45 and the engagement projection 54 function as a rotation stopper for the blade portion 5. Since no roll pin is used, the number of parts can be reduced.

[0027] Each wall portion 60 has the shape of a part of a cylinder, that is, its bottom surface is part of a ring. A first end P1 and a second end P2 are positioned at both ends of the wall portion 60 in the circumferential direction. Specifically, the first end P1 and the second end P2 are positioned in order along a counterclockwise direction in the circumferential direction.

[0028] An inclined surface 62 is positioned as the upper surface of the wall portion 60. The inclined surface 62 is a surface in which the height from the fixed end 42 decreases at a predetermined angle from the first end P1 to the second end P2. When viewed from the tip side of the wall portion 60, such an inclined surface 62 is formed so that the height of the wall portion 60 decreases in a counterclockwise direction in the circumferential direction.

[0029] Furthermore, the inclined surface 62 is formed in a spiral shape. In other words, the difference between the height of the radially inner P4 and the radially outer P3 near the second end P2 is greater than the difference between the height of the radially inner P4 and the radially outer P3 near the first end P1. Therefore, the inclined surface 62 tilts inward as it approaches the second end P2.

[0030] As shown in Figure 3, the blade portion 5 has a hollow cylindrical fitting cylinder portion 55 into which the shaft 30 is fitted, a circular blade hub portion 56 provided on the radially outer side of the fitting cylinder portion 55, and a plurality of blades 57 projecting radially from the blade hub portion 56. In this embodiment, the blade portion 5 has four blades 57 at predetermined intervals in the circumferential direction. The blade portion 5 is also provided with engaging projections 54 that engage with engaging recesses 45. In this embodiment, two engaging projections 54 are provided on the fitting cylinder portion 55 at 180° intervals in the circumferential direction. The engaging projections 54 have a rectangular shape and project downward from the lower end surface of the fitting cylinder portion 55. The engaging projections 54 may have magnetism that allows them to be attracted to the engaging recesses 45.

[0031] When connecting the wing portion 5 and the plastic magnet 40, the lower surface of the engaging projection 54 is brought close to the inclined surface 62 of the wall portion 60 to bring them into contact. When the lower surface of the engaging projection 54 comes into contact with the vicinity of the first end P1 of the inclined surface 62, the engaging projection 54 is more easily supported by the wall portion 60. When the wing portion 5 is rotated counterclockwise relative to the plastic magnet 40 in this state, the engaging projection 54 slides along the spiral inclined surface 62. When the engaging projection 54 reaches the second end P2 of the inclined surface 62, if the engaging projection 54 slides further, the engaging projection 54 engages with the engaging recess 45. In other words, the engaging projection 54 is guided into the engaging recess 45 by the inclined surface 62.

[0032] In this embodiment, the shaft 30 protrudes in the axial direction from the protruding end of the wall portion 60 on the opposite side from the cylindrical portion 41. In this case, it is easier to fix the blade portion 5 to the shaft 30 than when the shaft 30 does not protrude. As shown in Figure 4, the shaft 30 has a detachable recess 36 in the portion that protrudes beyond the wall portion 60. The detachable recess 36 is a circumferential recess provided at a position that protrudes axially from the fitting cylindrical portion 55 when the fitting cylindrical portion 55 of the blade portion 5 is fitted onto the shaft 30.

[0033] The embodiment includes a circular end cap 58 that fits over the tip of the shaft 30 to prevent the wing portion 5 attached to the shaft 30 from coming off. The end cap 58 has a detachable mechanism 59 that detachably engages with a detachable recess 36, and is fixed to the shaft 30 by engaging the detachable mechanism 59 with the detachable recess 36.

[0034] According to this embodiment, the plastic magnet 40 has an engaging recess 45 that engages with the engaging projection 54 of the blade portion 5, and the engaging recess 45 functions as an anti-rotation device, thus reducing the number of parts compared to using a roll pin or the like. Furthermore, since the engaging recess 45 is formed by resin molding as part of the plastic magnet 40, the manufacturing man-hours can be reduced compared to when a roll pin is attached. Also, since the engaging recess 45 is formed by resin molding as part of the plastic magnet 40, processability can be improved. In addition, since the engaging recess 45 is formed by resin molding as part of the plastic magnet 40, it engages with the blade portion 5, which is also made of resin, and damage to the blade portion 5 can be reduced even when it rotates.

[0035] Furthermore, since engagement recesses 45 are provided as spaces between multiple adjacent wall portions 60 in the circumferential direction, the position of the engagement recesses 45 can be brought closer to the blade portion 5. Also, since the shaft 30 protrudes on the opposite side from the cylindrical portion 41 from the protruding end of the wall portion 60, the blade portion 5 can be guided to the engagement recesses 45 along the axial direction of the shaft 30. In addition, since the wall portion 60 has an inclined surface 62, the engagement projection 54 of the blade portion 5 can be guided along the inclined surface 62 to the engagement recesses 45 of the plastic magnet 40. Furthermore, since the height of the wall portion 60 decreases in a counterclockwise direction in the circumferential direction on the inclined surface 62, the blade portion 5 can be supported by the higher side of the wall portion 60 when the blade portion 5 rotates. Furthermore, since the inclined surface 62 is formed in a spiral shape, the ease of mounting the engagement recesses 45 and the engagement projections 54 can be further improved. In addition, since the engagement projections 54 are magnetic, assembly can be improved.

[0036] (Example 2) Next, Example 2 will be described. Similar to Example 1, Example 2 relates to a motor 10 connecting a rotor 4 having an engaging recess 45 and a blade portion 5 having an engaging projection 54. The shape of the engaging recess 45 differs between Example 1 and Example 2. The following will focus on the differences from Example 1.

[0037] Figures 5(a) and 5(b) show the configuration of the rotor 4. Figure 5(a) is a perspective view of the rotor 4, and Figure 5(b) is a top view of the rotor 4. The shaft 30, cylindrical portion 41, and fixed end portion 42 are configured in the same way as in Embodiment 1, but unlike Embodiment 1, multiple wall portions 60 are not provided. On the other hand, the fixed end portion 42 is provided with multiple engagement recesses 45 so as to recess the fixed end portion 42. The multiple engagement recesses 45 are arranged along the circumferential direction of the cylindrical shape.

[0038] Figure 6 is a perspective view of the blade portion. The fitting cylinder portion 55, the blade hub portion 56, and the blade 57 are configured in the same way as in Embodiment 1. The blade portion 5 is also provided with an engaging projection 54 that engages with an engaging recess 45. In this embodiment, two engaging projections 54 are provided on the fitting cylinder portion 55 at 180° intervals in the circumferential direction. The engaging projections 54 have a rectangular shape and protrude downward from the lower end surface of the fitting cylinder portion 55. In particular, the engaging projections 54 protrude further toward the plastic magnet 40 than the blade hub portion 56.

[0039] According to this embodiment, since multiple engagement recesses 45 are provided so as to recess the fixed end portion 42, the degree of freedom in the shape of the engagement recesses 45 can be improved.

[0040] An overview of one aspect of this disclosure is as follows: (Item 1) A rotor (4) having a cylindrical shaft (30) extending in the axial direction, a plastic magnet (40) that covers the outer circumferential surface of the shaft (30) in an annular shape and rotates integrally with the shaft (30), and a blade portion (5) that is detachable from the plastic magnet (40), The aforementioned plastic magnet (40) is The aforementioned axially recessed engagement recess (45) is provided, The aforementioned blade portion (5) is A rotor (4) is provided with an engaging projection (54) that engages with the engaging recess (45).

[0041] (Item 2) The aforementioned plastic magnet (40) is A hollow cylindrical portion (41) for surrounding the stator core, A fixed end portion (42) extends from one end of the cylindrical portion (41) to the outer circumferential surface of the shaft (30), It comprises a plurality of wall portions (60) that protrude from the fixed end portion (42) toward the opposite side from the cylindrical portion (41), The plurality of wall portions (60) Arranged along the circumferential direction of the cylindrical shape, The aforementioned engaging recess (45) is The rotor (4) described in item 1 is provided as a space between the plurality of adjacent wall portions (60) in the circumferential direction.

[0042] (Item 3) The aforementioned shaft (30) is The rotor (4) described in item 2, which protrudes from the protruding end of the wall portion (60) on the side opposite to the cylindrical portion (41).

[0043] (Item 4) A first end (P1) and a second end (P2) are positioned at both ends of the wall portion (60) in the circumferential direction. The aforementioned wall portion (60) is The rotor (4) according to item 2, comprising an inclined surface (62) whose height from the fixed end (42) decreases at a predetermined angle from the first end (P1) to the second end (P2).

[0044] (Item 5) The aforementioned inclined surface (62) is The rotor (4) according to item 4, wherein, when viewed from the tip side of the wall portion (60), the height of the wall portion (60) decreases in a counterclockwise direction in the circumferential direction.

[0045] (Item 6) The aforementioned wall portion (60) The rotor (4) according to item 4, comprising a spiral inclined surface (62) whose height from the fixed end (42) decreases from the first end (P1) to the second end (P2), and whose height from the fixed end (42) decreases from the radially outward (P3) of the cylindrical surface to the radially inward (P4).

[0046] (Item 7) The aforementioned engaging projection (54) The rotor (4) according to item 1, which is provided with magnetism capable of adsorption to the engagement recess (45).

[0047] (Item 8) A motor comprising a rotor (4) according to any one of claims 1 to 7.

[0048] The present disclosure has been explained above based on examples. These examples are illustrative, and it will be understood by those skilled in the art that various modifications are possible for each component or combination of processing steps, and that such modifications are also within the scope of the present disclosure.

[0049] Examples 1 and 2 show a rotor 4 without a back yoke, but the 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.

[0050] Examples 1 and 2 show cases where multiple engagement recesses 45 are arranged at equal intervals in the circumferential direction, but the system is not limited to this. For example, the multiple engagement recesses 45 may be arranged at unequal intervals in the circumferential direction.

[0051] Examples 1 and 2 show cases where the engaging recess 45 contacts the outer circumferential surface of the shaft 30, but the invention is not limited to this. For example, the engaging projection may be provided without contacting the shaft.

[0052] In Examples 1 and 2, the motor 10 was shown to be a radial gap type in which the plastic magnet 40 surrounds the stator core 21 via a radial gap, but it is not limited to this. The motor may also be an axial gap type in which the disc-shaped plastic magnet faces the stator in the axial direction, as long as the engaging protrusions protrude axially and engage with the engaging recesses of the blades. [Explanation of Symbols]

[0053] 2 Stator, 4 Rotor, 5 Blade section, 10 Motor, 21 Stator core, 22 First insulator, 23 Second insulator, 24 Winding, 25 Stator unit, 26 Stator base, 28 First shaft support section, 29 Second shaft support section, 30 Shaft, 31 First bearing, 32 Second bearing, 34 Washer, 35 Circumferential groove, 36 Recess for attachment / detachment, 40 Plastic magnet, 41 Cylindrical section, 42 Fixed end, 43 Open end, 45 Engaging recess, 50 Base plate, 54 Engaging protrusion, 55 Fitting cylinder section, 56 Blade hub section, 57 Blade, 58 End cap, 59 Attachment / detachment mechanism, 60 Wall section, 62 Inclined surface, 262 Central hole.

Claims

1. A rotor comprising a cylindrical shaft extending in the axial direction, a plastic magnet covering the outer circumferential surface of the shaft in an annular shape and rotating integrally with the shaft, and a blade portion detachable from the plastic magnet, The aforementioned plastic magnet is The aforementioned axially recessed engagement recess is provided, The aforementioned wing portion is, A rotor having an engaging projection that engages with the aforementioned engaging recess.

2. The aforementioned plastic magnet is A hollow cylindrical section for surrounding the stator core, A fixed end extending from one end of the cylindrical portion to the outer surface of the shaft, It comprises a plurality of wall portions that protrude from the fixed end toward the opposite side from the cylindrical portion, The plurality of wall portions are Arranged along the circumferential direction of the cylindrical shape, The aforementioned engaging recess is The rotor according to claim 1, provided as a space between the plurality of adjacent wall portions in the circumferential direction.

3. The aforementioned shaft is The rotor according to claim 2, wherein the protruding end of the wall portion protrudes on the side opposite to the cylindrical portion.

4. A first end and a second end are positioned at both ends of the wall portion in the circumferential direction. The aforementioned wall portion is The rotor according to claim 2, further comprising an inclined surface whose height from the fixed end decreases at a predetermined angle from the first end to the second end.

5. The aforementioned inclined surface is The rotor according to claim 4, wherein, when viewed from the tip side of the wall portion, the height of the wall portion decreases in a counterclockwise direction in the circumferential direction.

6. The aforementioned wall portion The rotor according to claim 4, further comprising a spiral inclined surface wherein the height from the fixed end decreases from the first end to the second end, and the height from the fixed end decreases from the radially outer side of the cylindrical surface to the radially inner side.

7. The aforementioned engaging projection is The rotor according to claim 1, further comprising a magnet capable of adsorption to the engagement recess.

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

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