JP7596061B2 - Motor - Google Patents

Description

This invention relates to a motor.

Conventionally, motors have been used that have a frame with a pair of opposing flat plate sections and a pair of opposing curved sections, such as oval-shaped motors. This type of motor has a structure in which magnets are arranged inside the pair of curved sections within the frame.

The following Patent Document 1 describes the structure of a motor magnet in which a groove is provided on the surface that is bonded to the motor parts.

JP 2011-166848 A

The aim of this invention is to provide a motor that produces low noise when rotating.

According to one aspect of the present invention to achieve the above-mentioned object, a motor comprises a frame having one end covered by a surface in the direction of the rotation axis, the other end which is an opening in the direction of the rotation axis, a pair of resonant flat portions facing each other in a radial direction, and a pair of curved portions facing each other in the radial direction, two magnets fixed to the pair of curved portions respectively, the entire inner surface of the curved portions and the entire outer surface of the magnet facing the pair of flat portions, a gap formed between the entire inner surface of the curved portion facing the entire outer surface of the magnet and the pair of flat portions, and a cushioning material disposed in the entire gap , wherein in the circumferential direction, the magnet has ends, a gap is formed between the end of the magnet and the flat portion, the end of the magnet and the inner surface of the flat portion form an acute angle, and part of the cushioning material is in the gap.
According to another aspect of the invention, a motor includes a frame having one end covered by a surface in the direction of rotation axis, the other end which is an opening in the direction of rotation axis, a pair of resonant flat portions facing each other in a radial direction, and a pair of curved portions facing each other in the radial direction, two magnets fixed to each of the pair of curved portions, the entire inner surface of the curved portions and the entire outer surface of the magnet facing the pair of flat portions, a gap formed between the entire inner surface of the curved portions facing the entire outer surface of the magnet and the pair of flat portions, a cushioning material disposed throughout the gap, and a spring that biases the two magnets, with a portion of the cushioning material attached to the spring.

Preferably, the cushioning material disposed between one curved portion and one magnet is formed from a single member.

By following these inventions, it is possible to provide a motor that produces low noise when rotating.

1 is a cross-sectional view showing a motor according to an embodiment of the present invention; 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 2 is a perspective view showing a frame, a magnet, and a spring. FIG. 4 is an exploded perspective view showing a frame, a magnet, and a spring. FIG. 4 is a perspective view illustrating a range in which the cushioning material is arranged. FIG. 4 is a rear view of the frame, magnet, and spring. FIG. 13 is a diagram showing the measurement results of the volume of sound generated when a motor rotates. 13 is a rear view of a frame, a magnet, and a spring of a motor according to a modified example of the present embodiment. FIG. FIG. 13 is a diagram illustrating a coating area of a cushioning material.

The following describes an embodiment of the present invention with reference to the drawings.

In this application, the direction along the motor's rotating shaft is sometimes referred to as the "axial direction", the direction perpendicular to the motor's rotating shaft is sometimes referred to as the "radial direction", and the direction along the arc centered on the motor's rotating shaft is sometimes referred to as the "circumferential direction". In this application, the shape and positional relationship of each part will be described assuming that the axial direction is the front-to-rear direction (the left side in FIG. 1 is the "front"), the radial direction perpendicular to the flat plate portion is the up-to-down direction (the top side in FIG. 2 is the "up"), and the radial direction parallel to the flat plate portion is the left-to-right direction (the left side in FIG. 2 is the "left"). However, these front-to-rear, up-to-down, and left-to-right directions are defined merely for the convenience of explanation, and do not limit in any way the direction in the device in which the motor of the present invention is mounted, or the attitude in which this motor is used.

[Embodiment]

Figure 1 is a cross-sectional view showing a motor according to one embodiment of the present invention.

The cross section shown in Figure 1 is the cross section shown as line B-B in Figure 2 described below. In the following figures, arrow A1 indicates the direction of the rotation axis.

The motor 1 is, for example, a DC motor. The motor 1 has a rotating shaft 2, a frame assembly 1a, and an armature assembly 1b that can rotate around the rotating shaft 2 relative to the frame assembly 1a.

The armature assembly 1b includes an armature portion 4 and a commutator portion 6. The armature portion 4 is attached to the rotating shaft 2. The armature portion 4 includes an armature core 5 having multiple salient poles protruding in the radial direction and a winding 4a wound around each salient pole. The commutator portion 6 is provided near one end of the rotating shaft 2. The commutator portion 6 includes a commutator 7 that comes into contact with a brush 20 provided on the frame assembly 1a.

The frame assembly 1a is composed of a frame 10, a bracket 30, a magnet 60, etc.

The frame 10 has a front end (one end) and a rear end (the other end) in the direction of the rotation axis, and has a cylindrical shape with the front end covered by a surface. In other words, the frame 10 has a cup shape with the rear end as an opening. The opening at the rear end of the frame 10 (the end on the right side in Figure 1) is closed by the bracket 30. The armature assembly 1b is housed in a housing formed by the frame 10 and the bracket 30.

The bracket 30 holds the conductive part 40 to which current is supplied from the outside. The conductive part 40 is electrically connected to the brush 20. The brush 20 is arranged so as to be in contact with the commutator 7. In FIG. 1, the brush 20 and the conductive part 40 are indicated by two-dot chain lines.

The rotating shaft 2 penetrates the front surface of the frame 10. That is, one end of the rotating shaft 2 (hereinafter referred to as the front end) protrudes from the frame 10 to the outside of the frame 10. A bearing 18 is held in the center of the front surface of the frame 10. Also, a bearing 19 is held in the center of the bracket 30. The rotating shaft 2 is rotatably supported by the two bearings 18 and 19 relative to the frame 10.

Figure 2 is a cross-sectional view taken along line A-A in Figure 1.

As shown in FIG. 2, in this embodiment, the motor 1 has an outer circumferential shape that has two flat plate portions and two curved portions that connect the flat plate portions. In other words, the motor 1 has a so-called oval shape. The motor 1 has an outer circumferential shape whose dimension in the up-down direction (arrow A3) is smaller than its dimension in the left-right direction (arrow A2).

That is, as shown in FIG. 2, the frame 10 has a pair of flat plate portions 11, 12 (upper flat plate portion 11, lower flat plate portion 12) facing each other and a pair of curved portions 13, 14 (right curved portion 13, left curved portion 14) facing each other. In FIG. 2, the upper flat plate portion 11, the right curved portion 13, the lower flat plate portion 12, and the left curved portion 14 are connected clockwise, and the left curved portion 14 is again connected to the upper flat plate portion 11. The upper flat plate portion 11 is disposed above the motor 1, and the lower flat plate portion 12 is disposed below the motor 1. The flat plate portions 11, 12 are flat plate-shaped and substantially perpendicular to the up-down direction. The right curved portion 13 is disposed on the right side of the motor 1, and the left curved portion 14 is disposed on the left side of the motor 1. The right curved portion 13 and the left curved portion 14 each have a rounded shape that is convex toward the outside. The outer peripheral shape of the motor 1 is approximately symmetrical with respect to the rotating shaft 2 in a cross section perpendicular to the rotating shaft 2.

The frame 10 is made of a magnetic material. For example, the frame 10 is made of iron. The frame 10 has a substantially uniform thickness. In other words, the inner peripheral surface of the frame 10 is made up of multiple flat portions formed by the flat plate portions 11 and 12 and multiple rounded portions formed by the curved portions 13 and 14.

In this embodiment, the motor 1 is provided with two magnets 60 (when the two magnets 60 are referred to separately, they are referred to as a right magnet 63 and a left magnet 64). Each magnet 60 is disposed inside the frame 10. Each magnet 60 is fixed to a pair of curved portions 13, 14, respectively. That is, the right magnet 63 is fixed to the inside of the right curved portion 13, and the left magnet 64 is fixed to the inside of the left curved portion 14.

The magnet 60 is, for example, a bonded magnet formed using a known rare earth material and a known resin material. Note that the magnet 60 is not limited to a bonded magnet and may be, for example, a sintered magnet.

The right magnet 63 has a magnetic pole element 61a (north pole 61a), and the left magnet 64 has a magnetic pole element 62a (south pole 62a). The two magnetic pole elements 61a, 62a are arranged on the two curved portions 13, 14 of the frame 10 so that the magnetic pole elements 61a, 62a face each other.

The magnets 60 are attached to the inner circumferential surface of the frame 10. As will be described in detail later, the magnets 60 are attached to the inner circumferential surface of the frame 10 by the cushioning material 90 and springs 71, 72 (upper spring 71, lower spring 72) provided between the curved portions 13, 14 and each magnet 60.

Figure 3 is an oblique view showing the frame 10, magnet 60, and springs 71 and 72.

In FIG. 3, only the outer diameter shape of the frame 10 is shown by a two-dot chain line. Also, the cushioning material 90 is not shown.

As shown in FIG. 3, the right magnet 63 and the left magnet 64 have symmetrical shapes. In this embodiment, the right magnet 63 and the left magnet 64 have the same shape, and the right magnet 63 and the left magnet 64 are arranged symmetrically.

The magnet 60 has an outer peripheral shape that fits along the inner peripheral surface of the frame 10. On the outer peripheral surface 65 of the magnet 60, both end portions in the circumferential direction are flat portions 65c that fit along the flat plate portions 11, 12 of the frame 10, and the portion other than the flat portions 65c is a curved surface that fits along the curved portions 13, 14 of the frame 10. The magnet 60 has an inner peripheral surface that is an imaginary cylindrical surface.

In the circumferential direction, the magnet 60 has end portions 67. In the axial direction, the magnet 60 has end portions 66. Between the end portions 66 and 67, an inclined portion (hereinafter referred to as a chamfered portion) 68 having an inclined surface is formed. One magnet 60 has two end portions 67, two end portions 66, and four chamfered portions 68.

In this embodiment, the motor 1 is provided with springs 71, 72 (upper spring 71, lower spring 72) that bias the two magnets 60. The upper spring 71 is disposed inside the upper flat plate portion 11, and the lower spring 72 is disposed inside the lower flat plate portion 12.

The springs 71 and 72 are formed of wire-shaped spring steel members and have a U-shape. The springs 71 and 72 have a portion (first portion) whose longitudinal direction is the left-right direction, and two arm portions (second portion) 77 extending rearward from both ends of the portion. These two arm portions extend along the sides of the two magnets 60, respectively, and the sides of the magnets 60 extend in the direction of the rotation axis. The springs 71 and 72 are arranged between the ends 67 of the two magnets 60 so that both arm portions 77 are in contact with the ends 67 of the magnets 60. The springs 71 and 72 bias the ends 67 of the right magnet 63 and the left magnet 64 in a direction in which the ends 67 move away from each other. The biasing force of the springs 71 and 72 is applied between the upper and lower ends 67, so that each magnet 60 is held pressed against the inner circumferential surface of the frame 10. In other words, the springs 71 and 72 function as retainers that hold the magnet 60 inside the frame 10.

Figure 4 is an exploded perspective view showing the frame 10, magnet 60, and springs 71 and 72.

In FIG. 4, the dashed lines are hidden lines, and the cushioning material 90 is not shown.

The magnet 60 is placed inside the frame 10 through the opening on the rear side of the frame 10, and is fixed by being pressed against the inner surfaces of the curved sections 13 and 14 by two springs 71 and 72. The motor 1 is then assembled by placing the armature assembly 1b inside the frame 10 and attaching the bracket 30 to the frame 10.

In this embodiment, an adhesive is used as the buffer material 90. The buffer material 90 is, for example, an epoxy resin formed by hardening an epoxy-based adhesive. Note that the material of the buffer material 90 is not limited to this, and may be, for example, another type of adhesive.

Figure 5 is a perspective view illustrating the range in which the cushioning material 90 is arranged. Figure 6 is a rear view of the frame 10, magnet 60, and springs 71 and 72.

5 and 6, the cushioning material 90 is shown with hatching. As shown in FIG. 5, the cushioning material 90 is applied to the entire outer peripheral surface 65 (including the flat portion 65c) of the magnet 60 in an unhardened state. That is, the cushioning material 90 is applied to the entire magnet 60 facing the inner peripheral surface of the frame 10. Then, in this state, the magnet 60 is placed inside the frame 10 as described above, and the cushioning material 90 is hardened. Then, the cushioning material 90 is placed in the entire gap formed between the curved portions 13, 14 and the magnet 60. The cushioning material 90 placed between the right curved portion 13 and the right magnet 63 is formed of a single material, and the cushioning material 90 placed between the left curved portion 14 and the left magnet 64 is formed of a single material.

Instead of applying the cushioning material 90 to the outer circumferential surface 65 of the magnet 60, the cushioning material 90 may be applied to the entire area of the inner circumferential surface of the frame 10 that faces the outer circumferential surface 65 of the magnet 60, and the magnet 60 may be positioned in that area.

In this embodiment, a gap 96 is formed between each end 67 of the right magnet 63 and the left magnet 64 and the flat plate portions 11 and 12. In this embodiment, a chamfered portion 68 is formed near both ends of each end 67 in the axial direction, and a gap 96 is formed between the chamfered portion 68 and the inner surface of the flat plate portions 11 and 12. In addition, each end 67 forms an acute angle with the inner surface of the flat plate portions 11 and 12, and a gap 96 is also formed in this area. In FIG. 6, the gap 96 is hatched more roughly than the hatching indicating the buffer material 90. As a result of the gap 96 being formed in this way, a part of the buffer material 90 is in the gap 96. The buffer material 90 in the gap 96 is a part of the buffer material 90 applied to the entire outer peripheral surface 65 that protrudes into the gap 96.

Because the cushioning material 90 is formed from a single member, it is difficult for the cushioning material 90 to protrude from both ends 67 of the magnet 60. This prevents the cushioning material 90 from coming into contact with the armature assembly 1b.

The faces of both ends 67 of the magnet 60 are inclined to form an acute angle with the inner surfaces of the flat plate portions 11 and 12, so even if the cushioning material 90 protrudes from both ends 67 of the magnet 60, the part of the cushioning material 90 protruding from the ends 67 remains in the gap 96. The cushioning material 90 in the gap 96 is hidden from the armature assembly 1b by the ends 67, so contact between the cushioning material 90 and the armature assembly 1b can be prevented. The motor 1 can be easily manufactured.

As described above, in this embodiment, the cushioning material 90 is provided between the magnet 60 and the inner surface of the frame 10, so that the volume of the sound generated when the motor 1 rotates can be reduced. That is, in a motor 1 having the flat plate portions 11, 12 as described above, resonance generally occurs in the flat plate portions 11, 12, which can generate loud noise. In contrast, in this embodiment, the cushioning material 90 is used to prevent the flat plate portions 11, 12 from resonating, and the volume of the generated noise can be reduced.

Figure 7 shows the measurement results of the volume of sound generated when motor 1 rotates.

The measurement results shown in FIG. 7 represent the measurement results of the sound volume when the motor 1 according to the present embodiment is rotated, and a motor (comparative example) that is the same configuration as the motor 1 except that it does not have the cushioning material 90. More specifically, in an environment with a background noise of 13.6 dB, the volume of the mechanical noise (dB) was measured with a sound-collecting microphone at a position 30 centimeters away from the motor 1 while the motor 1 was rotating at a constant speed of 10,000 rpm. The measurement of the motor 1 was performed 10 times each in the clockwise (CW) and counterclockwise (CCW) directions. For the comparative example, only the average value is shown. Note that an epoxy resin (product name: Araldite) was used as the cushioning material 90.

As shown in FIG. 7, it was found that the motor 1 according to this embodiment can reduce noise by approximately 10 dB compared to the comparative example.

[Explanation of modified version]

In addition, a part of the cushioning material 90 may be attached to the springs 71 and 72. For example, the magnet 60 and the springs 71 and 72 may be arranged on the frame 10 with the cushioning material 90 applied not only to the magnet 60 but also to each of the springs 71 and 72.

Figure 8 is a rear view of the frame 10, magnet 60, and springs 71 and 72 of the motor 1 according to one variation of this embodiment. Figure 9 is a diagram explaining the application range of the cushioning material 90.

In Figures 8 and 9, the cushioning material 90 is shown hatched. In Figure 9, only the cushioning material 90 applied to the upper spring 71 is shown.

8 and 9, a cushioning material 90 may be provided between the outer peripheral surface 65 of the magnet 60 and the inner peripheral surface of the frame 10, and the cushioning material 90 may be applied to the springs 71, 72 that bias the two magnets 60. The cushioning material 90 may be applied to the left and right arm portions 77 that contact the two magnets 60, as well as to the portion (front portion) that connects the arm portions 77 to each other. The cushioning material 90 placed on the springs 71, 72 may be placed on the entire springs 71, 72, or may be placed on only a portion of the springs 71, 72.

In this way, by attaching a part of the cushioning material 90 to the springs 71 and 72, the same effect can be obtained as when the springs 71 and 72 with high rigidity are used. In other words, the magnet 60 can be firmly held inside the frame 10.

In general, when the motor 1 is driven, electromagnetic forces (attraction and repulsion) act between the armature assembly 1b and the magnet 60, which may cause the magnet 60 to be displaced radially inward or outward from the frame 10, or displaced circumferentially by being dragged by the armature assembly 1b. In response to this, by attaching a portion of the cushioning material 90 to the springs 71 and 72 as described above, it is possible to prevent the magnet 60 from being displaced when the motor 1 is driven, resulting in abnormal noise, or to prevent the magnet 60 from being displaced due to vibration.

[others]

The motor may be configured by partially combining the features of the above-described embodiments. Some of the features of the above-described embodiments may not be provided, or some of the features may be configured in a different manner.

A cushioning material that has been preformed into a tape, sheet, or film shape may be placed between the outer circumferential surface of the magnet and the inner circumferential surface of the frame.

The configuration of the first terminal member and the second terminal member is not limited to that described above. Each terminal member may be composed of multiple members. Furthermore, each terminal member is not limited to a band-shaped member, but may be a linear member or a member having a lump-shaped portion in one part.

The motor configured as described above can be used for various purposes. For example, it may be used in electronic devices or installed in various vehicles.

In the motor configured as described above, the front end of the rotating shaft protrudes from the frame to the outside of the frame, and the rear end of the rotating shaft is stored inside the frame, but this is not limited to this. For example, the rear end of the rotating shaft may protrude from the frame to the outside of the frame, just like the front end.

The thickness of the cushioning member may be smaller than the thickness of the magnet 60. This allows the magnet 60 and the frame 10 to form a magnetic circuit while reducing vibration.

The above-described embodiments should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

REFERENCE SIGNS LIST 1 motor 2 rotating shaft 10 frame 11 upper flat plate portion 12 lower flat plate portion 13 right curved portion 14 left curved portion 30 bracket 60 magnet 63 right magnet 64 left magnet 67 end portion 71 upper spring 72 lower spring 90 cushioning material 96 gap

Claims (3)

a frame having one end portion covered with a surface in a rotation axis direction, the other end portion being an opening in the rotation axis direction, a pair of flat plate portions capable of resonating and opposed to each other in a radial direction, and a pair of curved portions opposed to each other in the radial direction;
Two magnets fixed to the pair of curved portions, respectively;
a gap formed between an entire inner circumferential surface of the curved portion and an entire outer circumferential surface of the magnet that faces the entire inner circumferential surface of the magnet and the pair of flat plate portions; and
A buffer material disposed throughout the gap; and
Equipped with
In the circumferential direction, the magnet has ends,
A gap is formed between the end of the magnet and the flat plate portion,
The end of the magnet and the inner surface of the flat plate form an acute angle,
A portion of the cushioning material is in the gap . a frame having one end portion covered with a surface in a rotation axis direction, the other end portion being an opening in the rotation axis direction, a pair of flat plate portions capable of resonating and opposed to each other in a radial direction, and a pair of curved portions opposed to each other in the radial direction;
Two magnets fixed to the pair of curved portions, respectively;
a gap formed between an entire inner circumferential surface of the curved portion and an entire outer circumferential surface of the magnet that faces the entire inner circumferential surface of the magnet and the pair of flat plate portions; and
A buffer material disposed throughout the gap; and
Equipped with
A spring is provided to bias the two magnets,
A motor, wherein a portion of the cushioning material is attached to the spring. 3. The motor according to claim 1, wherein the buffer material disposed between one of the curved portions and one of the magnets is formed of a single member.

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