JP7848990B2 - motor - Google Patents

Description

This invention relates to a motor.

Conventionally, a support structure has been proposed in which the stator is fixed to the outer circumferential surface of the stator support cylinder portion on the outer circumference of the base portion to which the bearing portion is fixed, by adhesive or the like (see, for example, Patent Document 1).

Japanese Patent Publication No. 2019-68604

However, in the motor described in Patent Document 1, there is a risk that the support force supporting the stator may decrease due to factors such as heat and vibration, and there was a desire to stabilize the stator's support force compared to conventional designs.

This invention was made in view of the above background, and one example of its objective is to provide a motor with improved stability of stator support force.

The above problems are solved by the present invention as follows. That is, the motor of the present invention comprises a rotor and
The rotor comprises a stator having a coil positioned opposite to the rotor, and a holder for holding the stator, wherein the stator has an annular portion and a magnetic pole portion that protrudes from the annular portion toward the outer circumference and around which the coil is wound, and the holder is in contact with the outer circumference of the annular portion in the radial direction and the inner circumference of the annular portion in the radial direction.

This is a perspective view showing the overall configuration of an outer rotor type motor according to one embodiment of the present invention. This is a perspective cross-sectional view showing the configuration of a motor according to one embodiment of the present invention. This is a perspective cross-sectional view showing a motor according to one embodiment of the present invention, with the rotor, bearings, and rotor housing removed. This is a perspective view showing the configuration of the stator holder of a motor according to one embodiment of the present invention, as viewed from above. This is a perspective view showing the configuration of the stator core of a motor according to one embodiment of the present invention. This is a perspective cross-sectional view showing the configuration of a stator holder according to one embodiment of the present invention. This is a perspective cross-sectional view from above of a motor according to one embodiment of the present invention, showing the stator core being held in the stator holder. This is a perspective cross-sectional view from below of a motor according to one embodiment of the present invention, showing the stator core being held in the stator holder. This is a cross-sectional perspective view showing a state in which a stator core is attached to a stator holder of a motor according to one embodiment of the present invention. This is a perspective cross-sectional view showing the configuration of a stator holder according to another embodiment of the present invention.

<Embodiments of the present invention>
Next, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a perspective view showing the overall configuration of an outer rotor type motor according to one embodiment of the present invention. Figure 2 is a perspective cross-sectional view showing the configuration of a motor according to one embodiment of the present invention. Figure 3 is a perspective cross-sectional view showing the configuration of a motor according to one embodiment of the present invention with the rotor, bearings, and rotor housing removed. Figure 4 is a perspective view showing the configuration of the stator holder of a motor according to one embodiment of the present invention when viewed from above. Figure 5 is a perspective view showing the configuration of the stator core of a motor according to one embodiment of the present invention. Figure 6 is a perspective cross-sectional view showing the configuration of the stator holder according to one embodiment of the present invention. Figure 7 is a perspective cross-sectional view from above showing the state in which the stator core is held in the stator holder of a motor according to one embodiment of the present invention. Figure 8 is a perspective cross-sectional view from below showing the state in which the stator core is held in the stator holder of a motor according to one embodiment of the present invention. Figure 9 is a cross-sectional perspective view showing the state in which the stator core is attached to the stator holder of a motor according to one embodiment of the present invention.

In this embodiment, for convenience, the direction in which the axis X extends when the motor 1 rotates will be referred to as the axial direction or rotational direction. Furthermore, for convenience, in the axial direction, arrow a will be considered upward or upward, and arrow b will be considered downward or downward. In the radial direction perpendicular to axis X, arrow c, moving away from axis X, will be considered the outer circumference or outside, and arrow d, moving towards axis X, will be considered the inner circumference or inside. In the circumferential direction of the motor 1, arrow e will be considered clockwise, and arrow f will be considered counterclockwise. In the following description, upward (arrow a direction) and downward (arrow b direction) refer to the vertical relationship of the motor 1 in the drawing, and do not necessarily coincide with the vertical relationship in the direction of gravity.

As shown in Figures 1 to 9, motor 1 is an outer rotor type brushless motor mounted on a floating mobile device such as a drone (not shown). In drones, the various components are attached to each other using fasteners or adhesives during assembly. However, it is known that impacts to the aircraft during landing or falling can lead to damage to motor 1. Therefore, in this embodiment, motor 1 simplifies assembly and significantly improves the stability of the support force for each component compared to conventional designs.

As shown in Figures 1 to 3, the motor 1 has the drone's propeller (not shown) attached to the rotor housing 17 on the upper side (direction of arrow a), and the drone's body attached to the stator holder 11 (Figure 2), which acts as a holder on the lower side (direction of arrow b). As shown in Figure 2, the motor 1 mainly consists of the stator holder 11 (Figure 2), stator 13 (Figure 3), rotor 15 (Figure 2), rotor housing 17 (Figures 1 and 2), and bearing 19 (Figure 2).

The stator holder 11 is made of a metal such as an aluminum alloy and is a component that holds the bearing 19 and the stator 13 (Figure 3). The stator holder 11 has a cylindrical portion (hereinafter referred to as the "inner circumferential cylindrical portion") 111 provided on the inner circumference side (direction of arrow d) in the radial direction.

The inner cylindrical portion 111 of the stator holder 11 is formed in an overall cylindrical or substantially cylindrical shape, extending in the direction of the rotation axis. This inner cylindrical portion 111 holds two bearings 19 (19a, 19b) on its inner surface (direction of arrow d) 111n (hereinafter referred to as the "inner surface").

The two bearings 19 (19a, 19b) are integrally fixed to the inner surface 111n of the inner cylindrical portion 111 using adhesive or the like. However, the means of fixing are not limited to this; the outer rings of the bearings 19 may also be press-fitted onto the inner surface 111n of the inner cylindrical portion 111 in the stator holder 11.

In other words, the inner cylindrical portion 111 of the stator holder 11 also functions as a bearing holder for the two bearings 19. The bearings 19 are, for example, ball bearings. However, the bearings 19 are not limited to ball bearings; various other bearings, such as sleeve bearings, may also be used.

A thin, disc-shaped plate 12 is fixed to the end of the inner cylindrical portion 111 of the stator holder 11 that is opposite to the rotor housing 17 (the lower side (direction of arrow b)).

The plate 12 is integrally fixed with adhesive or the like, with its outer peripheral surface (direction of arrow c) 12g fitted against the inner peripheral surface 111n of the inner peripheral cylindrical portion 111. The plate 12 also has a stepped portion 12a at its outer peripheral end in the radial direction, and the bearing 19b is supported from below (direction of arrow d) by this stepped portion 12a.

As shown in Figures 2 to 4, the stator holder 11 has a disc-shaped connecting portion 113 that extends radially from the lower end (direction of arrow b) of the inner cylindrical portion 111 toward the outer circumference (direction of arrow c).

The connecting portion 113 is formed integrally with the inner cylindrical portion 111 and connects the inner cylindrical portion 111 and the inclined portion 115, which will be described later. The connecting portion 113 is a thin, plate-like annular portion centered on axis X and is connected to the inner end (direction of arrow d) of the inclined portion 115.

The stator holder 11 has a slanted portion 115 that extends diagonally upward (in the direction of arrow a) toward the stator 13 from the outer peripheral end (direction of arrow c) in the radial direction of the connecting portion 113. The slanted portion 115 is integrally formed with the outer peripheral end (direction of arrow c) of the connecting portion 113. The slanted portion 115 extends toward the rotor housing 17 along the rotation axis from the outer peripheral end (direction of arrow c) and is integrally formed with an arm portion 120 that has a substantially inverted U-shaped cross-section.

The arm portion 120 of the stator holder 11 has a plurality of inner circumferential cylindrical pieces (hereinafter referred to as "inner circumferential cylindrical pieces") 117 that extend toward the rotor housing 17 along the axis of rotation. Each of the plurality of inner circumferential cylindrical pieces 117 is integrally formed with the outer circumferential end of the inclined surface portion 115 and is concentric with the inner circumferential cylindrical portion 111 of the stator holder 11.

Here, the number of inner cylindrical pieces 117 is the same as the number of teeth 133 of the stator core 131, which will be described later. That is, the number of inner cylindrical pieces 117 in the arm portion 120 matches the number of spaces between the teeth 133. However, this is not the only option; the number may be less than the number of spaces between the teeth 133. However, from the viewpoint of firmly holding the stator core 131, it is preferable that the number of inner cylindrical pieces 117 matches the number of spaces between the teeth 133.

In this state, when multiple inner cylindrical pieces 177 are gathered in the circumferential direction, the entire structure forms a cylindrical shape.

The arm portion 120 extends from the upper end (direction of arrow a) of the inner circumferential cylindrical piece 117 toward the outer circumferential side (direction of arrow c), and has a connecting piece 118 that is integrally connected to a plurality of outer circumferential cylindrical pieces (hereinafter referred to as "outer circumferential cylindrical pieces") 119.

The connecting piece 118 has a radial width that allows it to cover the annular portion 132 of the stator core 131 (described later) from above (in the direction of arrow a). The lower surface (in the direction of arrow b) of the connecting piece 118 (hereinafter referred to as the "lower surface") 118b (Figure 4) is either a flat surface or a curved surface that curves concavely upwards (in the direction of arrow a).

The lower surface 118b of the connecting piece 118 is in contact with the upper surface (hereinafter referred to as the "upper surface") 132a of the annular portion 132 of the stator core 131. The upper surface (in the direction of arrow a) of the connecting piece 118 (hereinafter referred to as the "upper surface") 118a is either a flat or curved surface and has a certain space between it and the rotor housing 17.

The arm portion 120 has a plurality of outer-circumferential cylindrical pieces 119 extending downward (in the direction of arrow b) along the rotation axis from the outer-circumferential end of the connecting piece 118. These plurality of outer-circumferential cylindrical pieces 119 are positioned further outward (in the direction of arrow c) than the plurality of inner-circumferential cylindrical pieces 117 in the arm portion 120, and are concentric with the inner-circumferential cylindrical pieces 117.

The inner cylindrical piece 117, connecting piece 118, and outer cylindrical piece 119 of the arm portion 120 all have the same thickness. However, this is not limited to this; the connecting piece 118 and outer cylindrical piece 119 may be formed thinner than the inner cylindrical piece 117, and their respective thicknesses can be arbitrarily set.

The arm portion 120 is formed in an inverted U-shape in cross-section so as to contact the inner circumferential surface 132n (Figure 5) and the outer circumferential surface 132g (Figure 5) of the annular portion 132 of the stator core 131. In this case, the outer circumferential surfaces 117g of the multiple inner cylindrical pieces 117 of the arm portion 120 are in contact with the inner circumferential surface 132n of the annular portion 132, and the inner circumferential surfaces 119n of the multiple outer cylindrical pieces 119 are in contact with the outer circumferential surface 132g of the annular portion 132.

In the arm portion 120, multiple inner cylindrical pieces 117, multiple connecting pieces 118, and multiple outer cylindrical pieces 119 are formed to hold the annular portion 132 of the stator core 131 from above (in the direction of arrow a).

In practice, the arm portion 120 is formed when the connecting piece 118 engages with the annular portion 132 while the multiple outer cylindrical pieces 119 are not bent, and then the outer cylindrical pieces 119 are bent (crimped) toward the outer surface 132g of the annular portion 132.

The outer circumferential surfaces 117g of the multiple inner cylindrical pieces 117 are formed as flat surfaces to facilitate close contact with the inner circumferential surface 132n of the annular portion 132 of the stator core 131. Similarly, the inner circumferential surfaces 119n of the multiple outer cylindrical pieces 119 are formed as flat surfaces to facilitate close contact with the outer circumferential surface 132g of the annular portion 132 of the stator core 131. However, the design is not limited to this; the outer circumferential surfaces 117g of the inner cylindrical pieces 117 and the inner circumferential surfaces 119n of the outer cylindrical pieces 119 may have any shape that allows for surface contact with the inner circumferential surface 132n and outer circumferential surface 132g of the annular portion 132 of the stator core 131.

The multiple outer cylindrical pieces 119 on the arm portion 120 are formed to be longer than the length of the annular portion 132 of the stator core 131 along the rotation axis. That is, the outer cylindrical pieces 119 have a protruding portion 119c at the lower end (in the direction of arrow b) that extends lower (in the direction of arrow b) than the lower end (in the direction of arrow b) of the annular portion 132 of the stator core 131.

Thus, the stator holder 11 is composed of the inner cylindrical portion 111, the connecting portion 113, the inclined portion 115, and the arm portion 120.

The stator 13 is fixed to the arm portion 120 of the stator holder 11. As shown in Figure 3, the stator 13 has a stator core 131 and a coil 139.

As shown in Figure 5, the stator core 131 is a laminate of silicon steel sheets or the like, which serve as the magnetic material. The stator core 131 comprises an annular portion 132, a plurality of teeth portions 133 extending from the annular portion 132 toward the outer circumference (in the direction of arrow d), and tip portions 134 connected to each of the teeth portions 133. The teeth portions 133 and tip portions 134 together are referred to as the magnetic pole portion.

The annular portion 132 of the stator core 131 is a cylindrical portion, having an inner circumferential surface 132n and an outer circumferential surface 13g, and also having an upper surface 132a as one surface and a lower surface 132b as the other surface.

The inner circumferential surface 132n and outer circumferential surface 132g of the annular portion 132 are smooth curved surfaces corresponding to the outer circumferential surface 117g of the inner cylindrical piece 117 and the inner circumferential surface 119n of the outer cylindrical piece 119 in the arm portion 120 of the stator holder 11. The upper surface 132a and lower surface 132b of the annular portion 132 are flat surfaces.

The inner circumferential surface 132n of the annular portion 132 of the stator core 131 is in contact with the outer circumferential surfaces 117g of the multiple inner cylindrical pieces 117 on the arm portion 120 of the stator holder 11. The outer circumferential surface 132g of the annular portion 132 of the stator core 131 is in contact with the inner circumferential surfaces 119g of the multiple outer cylindrical pieces 119 on the arm portion 120 of the stator housing 11.

The teeth portion 133 is the part that connects the annular portion 132 and the tip portion 134, extending from the annular portion 132 toward the outer circumference (direction of arrow c) to the tip portion 134.

The tip portion 134 has convex portions that protrude in the circumferential direction in both the clockwise direction (arrow e) and the counterclockwise direction (arrow f), and the gap between adjacent convex portions is narrower than the gap (slot) between adjacent tooth portions 133.

As shown in Figures 2 and 3, an insulator 18 made of an insulating material is attached to the teeth portion 133 of the stator core 131, and the coil 139 is wound around this insulator 18.

The insulator 18 is constructed by the engagement of an upper insulator portion 18a, which covers the annular portion 132, the teeth portion 133, and the tip portion 134 from above (direction of arrow a), and a lower insulator portion 18b, which covers the annular portion 132, the teeth portion 133, and the tip portion 134 from below (direction of arrow b).

In other words, the stator core 131 and the coil 139 are electrically insulated via the insulator 18. Note that the insulator 18 does not necessarily need to be divided into an upper insulator portion 18a and a lower insulator portion 18b as described above; it may be formed as a single integrated unit. Furthermore, instead of using the insulator 18, an insulating resin film may be formed on the surface of the stator core 131, and this resin film may be used as the insulator.

The rotor 15 (Figure 2) has a yoke 151 and a magnet 153. The yoke 151 is an annular and cylindrical iron core extending along the axis X. The yoke 151 surrounds the magnet 153 and holds it integrally. The magnet 153 has a cylindrical shape extending along the axis X, similar to the yoke 151.

Specifically, the magnet 153 is fixed to the inner circumferential surface 151n of the yoke 151 using adhesive. However, this is not the only option; for example, the magnet 153 may be held in contact with the inner circumferential surface 151n of the yoke 151 by press-fitting or other means.

The yoke 151 is made of a magnetic material such as iron. The yoke 151 is positioned higher than the magnet 153 in the direction of rotation.

The magnet 153 is a single-piece molded magnetic material. The inner circumferential surface of the magnet 153, facing the tip 134 of the stator core 131, is divided into a region magnetized to the south pole and a region magnetized to the north pole, which are arranged alternately along the circumferential direction. The height of the magnet 153 in the direction of rotation is lower than the height of the yoke 151 in the direction of rotation.

In other words, the magnet 153 only needs to be held in a state where its outer circumferential surface 153g is covered from the outer circumferential side (direction of arrow c) by the yoke 151. Furthermore, the outer circumferential portion 173 (described later) of the rotor housing 17 is held by the inner circumferential surface 151n of the yoke 151 and the upper end face 153a (direction of arrow c) of the magnet 153.

The rotor housing 17 is made of a relatively light metal such as an aluminum alloy and has an overall disc shape. However, it is not limited to this, and the rotor housing 17 may be made of other materials such as resin or plastic.

As shown in Figures 1 and 2, the rotor housing 17 has an inner circumferential portion 171 provided on the inner circumference side (direction of arrow c), an outer circumferential portion 173 provided at the end on the outer circumference side (direction of arrow d), and a spoke portion 175.

As shown in Figure 2, the inner circumference 171 of the rotor housing 17 has a cylindrical projection 171d with a through hole 171h centered on axis X, and a flange portion 171f extending radially from the outer circumference end of the projection 171d. The flange portion 171f has an outer diameter that allows it to cover the inner cylindrical portion 111 of the stator holder 11 from above (direction of arrow a).

The protrusion 171d of the inner circumference 171 of the rotor housing 17 has a cylindrical rotating shaft 172 that extends vertically (in the direction of arrows a and b) around axis X. The inner ring of the bearing 19 (19a, 19b) is held on the outer circumference 172g of the rotating shaft 172. That is, the rotating shaft 172 of the rotor housing 17 rotates together with the rotor 15 in the motor 1. Note that the rotating shaft 172 may also be cylindrical in shape without a space on its inner circumference.

Multiple (for example, six) spokes 175 are connected to the outer circumference (direction of arrow c) of the flange portion 171f, and an annular outer circumference portion 173 is connected to the outer circumference tip of each spoke portion 175. In other words, the spokes 175 connect the flange portion 171f of the inner circumference portion 171 to the outer circumference portion 173.

The outer periphery portion 173 is the part that covers the magnet 153, which is fixed to the inner circumferential surface 151n of the yoke 151, from above (in the direction of arrow a) by its radially outer periphery side (direction of arrow c). The outer periphery portion 173 of the rotor housing 17 is integrally attached by press-fitting it onto the inner circumferential surface 151n of the yoke 151, and the circumferential surface 173m of the outer periphery portion 173 and the inner circumferential surface 151n of the yoke 151 are in close contact.

In the above configuration, as shown in Figure 6, when the outer cylindrical piece 119 of the arm portion 120 of the stator holder 11 is not bent (indicated by the dashed line), the upper surface surface 132a of the annular portion 132 of the stator core 131 engages with the multiple connecting pieces 118 of the arm portion 120.

In this case, the outer circumferential surfaces 117g of the multiple inner cylindrical pieces 117 on the arm portion 120 are in contact with the inner circumferential surface 132n of the annular portion 132 of the stator core 131, and the multiple connecting pieces 118 on the arm portion 120 are in contact with the upper surface 132a of the annular portion 132.

Subsequently, when the multiple outer cylindrical pieces 119 on the arm portion 120 are bent and crimped so as to approach the outer surface 132g of the annular portion 132 of the stator core 131, the inner surface 119n of the outer cylindrical pieces 119 and the outer surface 132g of the annular portion 132 come into contact.

This allows the stator holder 11 to firmly hold the multiple inner cylindrical pieces 117, connecting pieces 118, and outer cylindrical pieces 119 of the arm portion 120, and the annular portion 132 of the stator core 131 in surface contact from three directions.

At this time, since each of the multiple outer cylindrical pieces 119 on the arm portion 120 has a protrusion 119c, the inner circumferential surface 119n (Figure 6) of the outer cylindrical piece 119 contacts the entire outer circumferential surface 132g of the annular portion 132 of the stator core 131, completely covering it from the outer circumferential side (direction of arrow c). Thus, the degree of contact between the arm portion 120 and the annular portion 132 of the stator core 131 is increased, and the stator holder 11 can firmly hold the stator core 131 without using adhesive.

With the above configuration, the motor 1 can firmly hold the annular portion 132 of the stator core 131 by the arm portion 120 of the stator holder 11, thus integrating the stator holder 11 and the stator core 131 without the use of adhesives or fixing members. Thus, the motor 1 can significantly improve the stability of the support force when supporting the stator 13 with the stator holder 11 compared to conventional designs.

<Other Embodiments>
Although the motor 1 in this embodiment is configured as an outer rotor type brushless motor, the present invention is also applicable to motors other than brushless motors. Furthermore, the present invention is also applicable to inner rotor type motors.

The motor of the present invention has been described above with reference to preferred embodiments, but the motor of the present invention is not limited to the configuration of the above embodiments. Figure 10 is a perspective cross-sectional view showing the mounting state of the stator holder and stator core according to another embodiment of the present invention.

For example, in this embodiment, the case was described in which the protruding portions 119c of the multiple outer cylindrical pieces 119 on the arm portion 120 protrude below the annular portion 132 of the stator core 131 (in the direction of arrow b). However, the present invention is not limited to this, and the protruding portions 119c may be further bent toward the lower surface 132b of the annular portion 132, so that the protruding portions 119c and the lower surface 132b of the annular portion 132 come into contact. In this case, the arm portion 120 of the stator holder 11 can firmly hold the annular portion 132 of the stator core 131 by enclosing it from four directions, so that the stator core 131 can be prevented from falling out even if the stator holder 11 is subjected to an impact from the outside.

Furthermore, although this embodiment describes the case in which a rotor housing 17 having spokes 175 is used, the present invention is not limited to this, and a disc-shaped rotor housing without spokes may also be used.

Furthermore, those skilled in the art may modify the motor of the present invention as appropriate in accordance with conventionally known knowledge. Such modifications, as long as they still possess the configuration of the present invention, are of course included within the scope of the present invention.

1...Motor, 11...Stator holder, 13...Stator, 15...Rotor, 17...Rotor housing, 19 (19a, 19b)...Bearing, 111...Inner cylindrical part, 113...Connecting part, 115...Inclined surface part, 117...Inner cylindrical piece, 118...Connecting piece, 119...Outer cylindrical piece, 120...Arm part, 131...Stator core, 132...Ring part, 133...Teeth, 134...Tip part, 139...Coil, 151...Yoke, 153...Magnet, 171...Inner part, 171d...Convex part, 171f...Flange part, 171h...Through hole, 173...Outer part, 175...Spoke part.

Claims (7)

Rotor and,
bearings and
A stator facing the rotor,
The system comprises a holder that holds the bearing and the stator,
The stator comprises a magnetic material, an insulator, and a coil wound around the magnetic material via the insulator.
The magnetic material of the stator has an annular portion and a plurality of magnetic pole portions that protrude outward from the annular portion.
The holder contacts the outer circumference of the annular portion in the radial direction and the inner circumference of the annular portion in the radial direction .
The holder comprises a bearing holder for holding the bearing, an arm portion, and a connecting portion for connecting the bearing holder and the arm portion.
The arm portion comprises an inner cylindrical piece and an outer cylindrical piece.
The cylindrical piece on the outer circumference is positioned between the plurality of magnetic pole portions in the circumferential direction.
Motor. The motor according to claim 1, wherein the holder contacts one of the surfaces of the annular portion in the axial direction. The motor according to claim 1 or 2, wherein the holder has a protrusion that protrudes more than the other surface in the axial direction of the annular portion. The motor according to claim 2, wherein the holder contacts the other surface of the annular portion in the axial direction. The motor according to any one of claims 1 to 4, wherein the holder is formed of a magnetic material. The motor according to any one of claims 1 to 5, wherein the arm portion contacts the outer circumferential surface on the outer side in the radial direction of the annular portion and the inner circumferential surface on the inner side in the radial direction of the annular portion. The outer circumferential surface of the inner cylindrical piece on the inner side contacts the inner circumferential surface of the annular portion in the radial direction.
The inner surface of the cylindrical piece on the outer circumference contacts the outer surface of the annular portion in the radial direction.
The motor according to claim 6 .