JPH0715899A - motor - Google Patents

Abstract

(57) [Summary] [Object] To provide a motor in which a magnet can be easily positioned with respect to a rotor yoke, and a frequency generating magnet can be easily and reliably prevented from rotating and coming off from the rotor yoke. [Structure] A rotor yoke 12 is provided, and this rotor yoke 1
A motor having a magnet 11 in 2, wherein the rotor yoke 12 is provided with a plurality of positioning means 40 for positioning the magnet 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor having a rotor yoke, such as a capstan motor used in a VTR.

[0002]

2. Description of the Related Art As a motor, for example, a general VTR
The capstan motor used for is used for carrying a magnetic tape. This type of capstan motor
It has a rotor and a stator. A magnet is attached to the rotor yoke of the rotor by adhesion.

When this magnet is attached to the rotor yoke by adhesion, the magnet is centered on the rotor yoke with a jig so that the magnet is adhered to the rotor yoke without displacement.

[0004]

Since the magnet is bonded to the rotor yoke while centering the magnet using the jig as described above, it takes a very long time to bond the magnet.

Further, as shown in FIG. 5, the conventional frequency generating magnet 113 of the capstan motor is a magnet for generating a frequency necessary for knowing the rotation state or the rotation angle of the rotor 100. .

The FG magnet 113 is firmly molded and fixed to the meshing portion 112a of the rotor yoke 112. As a result, the FG magnet 113 prevents the rotor yoke 112 from rotating and coming off.

As described above, since the meshing portion 112a of the FG magnet 113 is formed by being fitted into the rotor yoke 112 over substantially the entire circumference, the meshing portion 112a becomes heavy, and the meshing portion 112a has a dead portion.

The present invention has been made in order to solve the above problems, and the magnet can be easily positioned with respect to the rotor yoke, and the frequency generating magnet can be easily and reliably prevented from rotating with respect to the rotor yoke. It is also an object of the present invention to provide a motor capable of preventing slipping out.

[0009]

According to the present invention, there is provided a motor having a rotor yoke and a magnet on the rotor yoke. The rotor yoke has a plurality of positioning means for positioning the magnet. It is achieved by a motor that comprises.

Further, according to the present invention, preferably, the rotor yoke is provided with a frequency generating magnet, and the plurality of positioning means prevent the frequency generating magnet from rotating with respect to the rotor yoke. It is a stopping measure.

Further, in the present invention, preferably, the plurality of positioning means are projections, and the projections have tapered portions. Further, in the present invention, preferably, the plurality of positioning means are provided in three.

[0012]

The magnet can be positioned and attached to the rotor yoke by a plurality of positioning means. Further, the magnet for frequency generation can be stopped and prevented from rotating with respect to the rotor yoke by these positioning means.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the examples described below are suitable specific examples of the present invention, and therefore, various technically preferable limitations are given, but the scope of the present invention particularly limits the present invention in the following description. Unless otherwise stated, the present invention is not limited to these modes.

FIG. 1 is an exploded perspective view showing a preferred embodiment of the motor of the present invention. In FIG. 1, in order to show the cross-sectional structure, a part thereof is cut away. The motor shown in FIG. 1 is, for example, a capstan motor 1 used in a general VTR, and is used for carrying a magnetic tape.

The motor 1 is a plane-opposed motor in which the rotor portion 10 and the stator portion 20 face each other. The motor 1 includes a rotor unit 10, a stator unit 20, and a rotation detection unit 30.

First, the structure of the rotor section 10 will be described. The rotor unit 10 includes a main magnet 11 also called a permanent magnet, a rotor yoke 12, an FG magnet 13, a rotor boss 14, and a shaft 15.

The main magnet 11 has a ring shape or a disk shape. The main yoke 11 is attached to the inner surface of the rotor yoke 12 by its own magnetic attraction so that the outside of the main magnet 11 is covered by the rotor yoke 12. That is, the rotor yoke 12 is made of a material with which the main magnet 11 is attracted.

An FG magnet 13 is formed on the outer circumference of the rotor yoke 12 over the entire circumference thereof, as shown in FIGS. This FG magnet (Frequ
energy Generating Magnet) 13
Is a so-called frequency generating magnet, which is a magnet for detecting the rotation angle of the rotor 10, in which a large number of magnetic poles are magnetized in multiple poles. The rotor boss 1 is attached to the rotor yoke 12.
A shaft 15 is attached via 4.

Next, the stator section 20 will be described.
The stator portion 20 of FIG. 1 has a stator yoke 21. On the stator yoke 21, a plurality of exciting coils 22 arranged to face the main magnet 11 described above are fixed.

In the example of FIG. 1, the exciting coils 22 are arranged in six circular shapes. By sequentially supplying an exciting current to these exciting coils 22, the rotor unit 10 can be rotated.

A housing 24 is attached to the stator yoke 21, and a shaft 15 of the rotor portion 10 is rotatably attached to a bearing 23 of the housing 24.

The rotation detector 30 is arranged on the stator yoke 21. The rotation detector 30 includes an MR element 31.
And a holder 32 for holding the MR element 31. The MR element 31 is also called a magnetic sensing element, and detects the magnetic field of the FG magnet 13 to detect the rotation angle of the rotor unit 10.

Next, please refer to FIG. 2 to FIG. The rotor yoke 12 preferably has three positioning protrusions 40.
Is provided. These protrusions 40 are arranged in the circumferential direction at the same angular phase and project radially inward. The positioning protrusion 40 is a protrusion for centering or positioning the main magnet 11 with respect to the rotor yoke 12.

The main magnet 11 is centered by these positioning protrusions 40, and as shown in FIG. 4, it is fixed to the inner surface 12a of the rotor yoke 12 by the magnetic attraction force of the main magnet 11. You can do it.

As a result, it is not necessary to position the main magnet 11 with respect to the rotor yoke 12 by using a jig as in the prior art, and it is not necessary to bond the main magnet 11 with an adhesive, and the deviation during the bonding is prevented. There is no need. Therefore, the man-hours for positioning and mounting can be reduced.

As shown in FIGS. 2 to 4, an FG magnet 13 is formed on the outer circumference of the rotor yoke 12 by molding. By molding the FG magnet 13 with respect to the rotor yoke 12 in this manner, as shown in FIG. 3, a part 13 a of the FG magnet 13 enters the inside of the positioning protrusion 40.

For this reason, the FG magnet 13 can prevent the rotor yoke 12 from rotating in the rotational direction, and also prevent the rotor portion 10 from coming off along the axial direction. Therefore, the F
It is not necessary to fit the G magnet 113 into the meshing portion of the rotor yoke for molding.

Further, the positioning projection 40 is formed with a taper portion 40a, as particularly shown in FIG. By forming the tapered portion 40a in this way,
The main magnet 11 can be positioned while being easily fitted into the inner surface 12a of the rotor yoke 12 along the arrow X direction in FIG.

The present invention is not limited to the above embodiment. For example, the number of positioning protrusions 40 is not limited to three, and may be two or four or more.

Further, the shape of the protrusion 40 may be other than the substantially V-shape as in the illustrated embodiment. Also, the present invention is not limited to VTR capstan motors. For example, the present invention can be applied to an FDD (floppy disk drive) motor.

[0031]

As described above, according to the first aspect of the present invention, the magnet can be reliably positioned or centered and attached to the rotor yoke. Therefore, the magnet can be easily positioned with respect to the rotor yoke. According to the second aspect of the invention, when the frequency generating magnet is provided on the rotor yoke, a simple positioning means can be used as the rotation preventing means and the retaining means for the frequency generating magnet. According to the invention of claim 3, the magnet can be fitted into the rotor yoke along the taper portion and easily positioned. For this,
Improves magnet mountability.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a preferred embodiment of a motor of the present invention.

FIG. 2 is a plan view showing a protrusion for positioning a rotor yoke of the rotor portion of FIG. 1, a main magnet, and an FG magnet.

FIG. 3 is a perspective view showing a positioning protrusion of a rotor yoke and an FG magnet.

FIG. 4 is a cross-sectional view of a part of the rotor section shown in FIG. 2 seen from a side surface.

FIG. 5 is a perspective view showing a structure of a magnet, a rotor yoke, and an FG magnet in a conventional motor.

[Explanation of symbols]

 1 Capstan Motor 10 Rotor Part 11 Main Magnet 12 Rotor Yoke 13 FG Magnet 14 Rotor Boss 15 Shaft 20 Stator Part 21 Stator Yoke 22 Excitation Coil 23 Bearing 24 Housing 30 Rotation Detecting Part 31 MR Element 32 Holder 40 Positioning Protrusion (Positioning Means)

Claims (4)

[Claims] 1. A motor having a rotor yoke and having a magnet on the rotor yoke, wherein the rotor yoke is provided with a plurality of positioning means for positioning the magnet.
motor. 2. A frequency generating magnet is provided on the rotor yoke, and the plurality of positioning means serve as a rotation stopping means and a slip-out preventing means for the frequency generating magnet with respect to the rotor yoke. The motor according to 1. 3. The plurality of positioning means are protrusions,
The motor according to claim 1 or 2, wherein the protrusion has a tapered portion. 4. The motor according to claim 1, which has three of the plurality of positioning means.