JPH0213244A - Motor - Google Patents

Abstract

PURPOSE:To secure a magnet chip firmly by providing an anti-removal body which engages with a portion of the magnet chip to block movement of the magnet chip in radially outward direction to a rotor. CONSTITUTION:A rotor comprises a rotor core 4 provided on the circumference of a shaft 3 and a plurality of magnet chips 6 having arched cross-section arranged in ring shape on the outer circumference of the rotor core 4. The magnet chips 6 are adhered through adhesive to the rotor core 4. Each magnet chip 6 has groove type engaging recesses 21 at the outer circumferential edges in the axial direction of the end face. A ring type removal-preventing body 5 is pressed into the engaging recess 21. By such arrangement, the magnet chip can be prevented from removal due to the centrifugal force during high speed rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an inner rotor type motor having a permanent magnet in its rotor, such as a DC brushless motor.

[Conventional technology]

Conventionally, there is an inner rotor type DC brushless motor using permanent magnets in the rotor as shown in Fig. 14.
The rotor 52 has a rotor core 54 provided on a shaft 53, and a ring-shaped magnet piece 56 having a circular arc cross section attached to the outer periphery of the rotor core 54.

Stator 51 includes a stator core 57 and coils 58 located on the outer periphery of rotor 52 . Ferrite magnets are generally used as the magnet pieces 56 because they are inexpensive, and are bonded to the rotor core 54 with an adhesive.

However, ferrite magnets are hard and brittle, so when the rotor 52 rotates at high speed, the centrifugal force causes the magnet pieces to
6 may peel off from the rotor core 54 or even scatter.

For this reason, conventionally, as shown in FIGS. 15 to 17,
A structure in which a cylindrical protection member 55 is fitted around the outer circumference of a magnet piece 56 has been proposed. The protection member 55 is made of a resin molded product, a heat-shrinkable resin tube, glass fiber, or the like.

[Problems to be Solved by the Invention] As described above, by providing the protective member 55, the magnet piece 56 is prevented from coming off, and reliability in terms of strength is obtained. However, since the non-magnetic protective member 55 covers the outer surface of the magnet piece 56, the magnetic gap between the rotor core 57 and the magnet piece 56 increases, magnetic resistance increases, and the motor output decreases. There is a problem with that.

An object of the present invention is to provide a motor in which the magnet pieces can be securely fixed without increasing the gap between the magnet pieces and the stator core.

[Means to solve the problem]

The present invention provides an inner rotor type motor having a rotor in which a plurality of magnet pieces each having an arcuate cross-sectional shape are arranged in a ring shape, in which the magnet pieces are engaged with a part of the magnet pieces to move the magnet pieces radially outward. The rotor is provided with a detachment prevention body that prevents the rotor from coming off.

[Effect]

According to the structure of the present invention, the detachment prevention body prevents the magnet piece from coming off due to centrifugal force, but since the detachment prevention body engages with a part of the magnet piece, the gap between the magnet piece and the stator core Do not spread.

〔Example〕

A first embodiment of the present invention will be described based on FIGS. 1 to 4. This embodiment is an example applied to a DC brushless morph.

The stator l has a bearing 9. which supports the shaft 3 of the rotor 2 on a pair of cam-shaped bearing stands 11.12. lO is provided, bearing stand 1
A stator core 13 is provided on the inner surface of 1.12. A coil 14 wound around an insulating frame 15 is externally fitted onto the stator core 13. A printed circuit board 16 is provided with a position sensor 17 for detecting the rotation angle of the rotor 2 and a drive circuit 18.

The rotor 2 includes a rotor core 4 provided on the outer periphery of a shaft 3, and a plurality of magnet pieces 6 each having an arc-shaped cross section arranged in a ring shape around the outer periphery of the rotor core 4. The magnet pieces 6 are bonded to the rotor core 4 with an adhesive. A bush 7 is provided at one end of the rotor core 4, and a washer 8 is interposed between the bush 7 and the bearing 10.

As shown in FIG. 2, each magnet piece 6 has a groove-shaped engagement recess 21 formed on the outer periphery of both end faces in the axial direction, and the ring-shaped detachment prevention body 5 is inserted into the engagement recess 21 in an engineering state. Insert. The outer diameter of the detachment prevention body 5 is equal to the outer diameter of the magnet piece 6 and the distance between the paths.

According to this configuration, the ring-shaped detachment prevention body 5 is connected to the magnet piece 6.
Since the magnet piece 6 is fitted into the engagement recess 21 on the outer periphery of the magnet piece 6, even if the magnet piece 6 is made of a brittle material such as a ferrite magnet, it is prevented from coming off from the rotor core 4 due to centrifugal force during high-speed rotation. Therefore, by using an inexpensive ferrite stone as the magnet piece 6, it can be made highly reliable in terms of strength and can be rotated at high speed.

Since the detachment prevention body 5 is provided on a part of the magnet piece 6, the gap between the magnet piece 6 and the stator core 13 does not become large due to the presence of the detachment prevention body 5. Further, since the detachment prevention body 5 is fitted into the engagement recess 21 and does not protrude outward from the magnet piece 6, the gap does not become large. There is no increase in magnetic resistance between the two and there is no reduction in output.

FIG. 5 shows the manufacturing process of the second embodiment.
Form a gap between the bottom surface of 1 and the adhesive 20 in the gap.
It is filled with Reference numeral 19 denotes a jig for regulating the outer diameter of the detachment prevention body 5.

In the first embodiment, since the ring-shaped detachment prevention body 5 is fixed by press-fitting, it is necessary to improve the accuracy of the thickness d (Fig. 4) of the part where the engaging four parts 21 of the magnet piece 6 are provided. I can't do it. However, if the adhesive 20 is used to regulate the outer diameter of the detachment prevention body 5 with the jig 19 as in this embodiment, even if there are variations in the thickness d of the magnet pieces 6, This can be absorbed and fixed.

6 and 7 show a fourth embodiment. This example:
A chamfered portion 5a is provided on the inner peripheral surface of the ring-shaped detachment prevention body 5,
The space created by this chamfered portion 5a is used as a storage space for the adhesive 20. By providing such a reservoir space, the adhesive 20 can be prevented from protruding onto the outer peripheral surface.

FIGS. 8 and 9 show a third embodiment. This example:
Engagement recesses 24 are provided at the four corners of the outer surface of each magnet piece 6, and a protrusion 23 that fits between the engagement recesses 24 of adjacent magnet pieces 6
Disk-shaped detachment prevention bodies 22 having the following configuration are provided on both sides of the rotor core 4.

The detachment prevention body 22 has an insertion hole for the shaft 3 in the center, and is fixed to the rotor core 4 with adhesive.

With this configuration as well, it is possible to prevent the magnet pieces 6 from coming off due to centrifugal force, and it is also possible to prevent the gap from increasing. The detachment prevention body 22 can also be used as a means for positioning the magnet piece 6 in the axial direction when assembling it.

FIGS. 10 and 11 show a fifth embodiment.

In this example, groove-shaped engagement recesses 27 are provided at both ends of the outer surface of each magnet piece 6 in the circumferential direction, and a detachment preventing body 26 with a T-shaped cross section that engages between the engagement recesses 27 of adjacent magnet pieces 6 is provided. They are integrally provided on the rotor core 4 and protrude radially. The magnet piece 6 is fixed to the rotor core 4 with an adhesive, and the contact surface between the engagement recess 27 and the detachment prevention body 26 is also fixed with an adhesive.

In this configuration, since the detachment prevention body 26 is integrated with the rotor core 4, the number of parts is reduced, and the number of assembly steps is also reduced accordingly.

FIGS. 12 and 13 show a sixth embodiment.

In this example, groove-shaped engagement recesses 30 are provided at both ends of the outer surface of each magnet piece 6 in the circumferential direction, and an engagement recess 31 that is continuous with the engagement recesses 30 is provided in the rotor core 4. A disengagement prevention body 29 having an H-shaped cross section is fitted over the engagement recess 30.31 of the rotor core 4. The magnet piece 6 is adhered to the rotor core 4 with an adhesive, and the detachment prevention body 29 is also fixed in the engagement recess 30.31 with an adhesive.

In the embodiment shown in FIG. 1O, the detachment prevention body 26 is integrally provided on the rotor core 4, so the strength of the detachment prevention body 26, which is the protruding portion, is weak and may deform during handling. In this embodiment, since the detachment prevention body 5 is a separate body,
Strength can be increased.

Note that in the second to sixth embodiments, the structural effects whose explanations are omitted are the same as those in the first embodiment.

〔Effect of the invention〕

In the motor of this invention, the rotor is provided with a detachment prevention body that engages with a portion of the magnet pieces and prevents the magnet pieces from moving outward in the radial direction. Even if a magnet is used, the magnet pieces can be prevented from coming off due to centrifugal force during high-speed rotation.

Since the detachment prevention body engages with a part of the magnet piece,
This has the effect that the gap between the magnet piece and the stator core does not widen, and therefore the output does not decrease.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the first embodiment of the present invention, FIG. 2 is an exploded perspective view of its rotor, FIG. 3 is a sectional view of its detachment prevention body, and FIG. 4 is the same (the magnet pieces 5 is a sectional view of the manufacturing process of the second embodiment, FIG. 6 is a partial sectional view of the rotor of the third embodiment, and FIG. 7 is a sectional view of its detachment prevention body. 8 is a sectional view of the fourth embodiment, FIG. 9 is an exploded perspective view of the rotor, FIG. 10 is an exploded perspective view of the rotor of the fifth embodiment, and FIG. 11 is a plan view of the rotor. Figure, 12th
13 is a plan view of the rotor, FIG. 14 is a sectional view of the conventional example, and FIG. 15 is an exploded perspective view of the rotor of the sixth embodiment.
16 is a cross-sectional view of another conventional example, FIG. 16 is a cross-sectional view of the rotor, and FIG. 17 is a vertical cross-sectional view of the rotor. 1... Stator, 2... Rotor, 3... Shaft, 4...
- Rotor core, 5... Disengagement prevention body, 6... Magnet piece, 13... Stator core, 14... Coil, 21... Engagement recess, 22
26.29...Removal prevention body Fig. Fig. Fig. Fig. 1O Fig. 11 ■

Claims (1)

[Claims] In a motor that has a rotor in which a plurality of magnet pieces each having an arcuate cross-sectional shape are arranged in a ring shape, and the rotor is arranged inside a stator core, the magnet pieces engage with some of the magnet pieces. A motor characterized in that the rotor is provided with a detachment prevention body that prevents the rotor from moving outward in the radial direction.