JPH0439210B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of magnetizing a ring-shaped magnetic body for a stator having a notch on its circumferential surface.

(Prior Art) Conventionally, a miniaturized DC motor for driving the tape of a video tape recorder, etc., has a part of its outer circumferential surface cut out parallel to a tangent line to form a flat surface a, as shown in FIGS. A ring-shaped stator b (permanent magnet) is used, and a hybrid integrated circuit board and the like are disposed on its surface a.

The method of magnetizing such a ring-shaped stator magnetic body is to fit an electromagnet e, which has an exciting coil d wound around a substantially H-shaped iron core c, into the inner circumferential side of the stator magnetic body b, as shown in the figure. A direct current of, for example, about 2000 A is passed through the coil d from a magnetizing power source (not shown) for several seconds, and the ' portions of the stator magnetic body b are magnetized to N and S poles, respectively, to obtain a ring-shaped stator. .

(Problems to be Solved by the Invention) In a conventional DC motor using a stator magnetized in this manner, the rotor rotates unevenly, and the tape driven by this motor runs unevenly. There was a problem.

To explain this in more detail, we use a magnetometer to measure the magnetic field distribution from the north pole of the magnetized stator b part to the south pole of the ' part along the inner circumferential surface on the side without the cutout part. Upon further investigation, as shown in Figure 8, the magnetic field strength gradually decreases from the N pole, and disappears at the midpoint between the N and S poles (as shown in Figure 6).
On the south pole side, the magnetic field is reversed and the magnetic field strength gradually increases, becoming strongest at the south pole (portion '). The decrease and increase in the magnetic field near this midpoint are
It is approximately linear. Next, the magnetic field strength along the inner circumferential surface on the side where the notch is located changes in a curved line shape as shown in Figure 8 near the midpoint between the N pole and the S pole (' in Figure 6), and then changes in a straight line shape as shown in Figure 8. does not change.

A DC motor using a stator having a magnetic field strength distribution as shown in FIG. 8 causes uneven rotation of the rotor at the midpoint of the stator b.

An object of the present invention is to provide a method of magnetizing a ring-shaped stator that solves the above-described conventional problems.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a ring having a gap formed by a ring-shaped stator magnetic material having a notch on its circumferential surface and an open end. The stator magnets arranged concentrically are arranged concentrically and in close contact so that the notch and the gap are close to each other, and a current is passed through the excitation coil of the electromagnet. A magnetic flux is caused to flow along the circumferential direction from the inner circumferential surface or the outer circumferential surface of the body and the ring-shaped yoke, and the stator magnetic body is magnetized along the circumferential surface.

(Function) When current is passed through the excitation coil, magnetic flux is generated,
This magnetic flux flows through the ring-shaped stator magnetic material and the ring-shaped yoke, but at the gap at the open end of the ring-shaped yoke, the stator magnetic material has higher magnetic permeability than air, so the ring-shaped stator magnetic material flows through the ring-shaped yoke. The magnetic flux flowing through the gap mainly flows through the stator magnetic material bridging the gap. Therefore, in areas other than the cutout of the ring-shaped yoke, the magnetic flux generated by the excitation coil flows to the stator magnetic material and the ring-shaped yoke, and in the cutout, most of this magnetic flux flows to the stator magnetic material. Each part of the stator magnetic body is magnetized and magnetized by the magnetic flux.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 A magnetized member used in carrying out the present invention is composed of an electromagnet 1 and a ring-shaped yoke 2, as shown in FIGS. 1 and 2.

The electromagnet 1 has an excitation coil 4 formed by winding a coated wire with a wire diameter of 0.8 mm 67 turns around a substantially H-shaped iron core 3, and a ring-shaped yoke 2 has a gap 6 formed by open ends 5, 5. It has a size such that its outer circumferential surface comes into close contact with the inner circumferential surface of the ring-shaped stator magnetic body 7 to be magnetized, and in this example, the outer diameter is 23.4 mm, the inner diameter is 19.0 mm, Thickness 15.0
A carbon-containing iron material with a gap of 5 mm was used.

The ring-shaped stator magnetic body 7 to be magnetized has, for example, an outer diameter of 32 mm, an inner diameter of 23.6 mm, and a thickness of 12.5 mm.
It is a barium ferrite magnetic material, and a part of its outer circumferential surface is plane-polished by 2.2 mm in the diametrical direction parallel to the tangent line, making it a flat surface of 16 mm x 12.5 mm.
was formed.

As shown in FIGS. 1 and 2, the ring-shaped yoke 2 is fitted onto the inner circumferential surface of the stator magnetic body 7, and the gap 6 is brought close to the notch 8 of the magnetic body 7. The electromagnet 1 rotates the shaft of the substantially H-shaped iron core 3 by 90 degrees from the gap 6 to bring it into close contact with the inner circumferential surface of the stator 7.

After attaching the magnetizing member to the stator magnetic body 7 as described above, the excitation coil 4 lasts for 500 μs.
A pulse current of 2000A was applied.

FIG. 3 shows the results of measuring the magnetic field strength along the inner circumferential surface of the magnetized stator magnetic material using an automatic recording magnetometer.

Example 2 The same method and conditions as in Example 1 were carried out except that the gap 6 of the ring-shaped yoke 2 was set to 3 mm.

FIG. 4 shows the measurement results of the magnetic field strength along the inner peripheral surface of the magnetized stator magnetic material.

Example 3 Ring-shaped yoke 2 with an outer diameter of 36.7 mm and an inner diameter
32.0mm, thickness 15mm, gap 5mm,
This is the same as in Example 1, except that this was fitted to the outer peripheral surface of the stator magnetic material 7, and that a substantially H-shaped iron core 3 of the electromagnet 1 had a size that was in contact with the inner peripheral surface of the stator magnetic material 7. It was carried out using the same method and conditions. The magnetic field strength along the inner peripheral surface of this magnetized stator magnetic material was the same as in Example 1.

In Examples 1, 2, and 3 above, the electromagnet 1 was placed on the inner peripheral surface side of the stator magnetic material, but the open end of the electromagnet, which has an approximately U-shaped core and an excitation coil, was placed on the stator magnetic material. The stator magnetic body may be arranged on the outer peripheral surface side and magnetized in the circumferential direction by an external magnetic field generated by passing a current through the excitation coil.

Furthermore, in the magnetized stator magnetic bodies of Examples 1, 2, and 3, a part of the outer circumferential surface is polished in the diametrical direction parallel to the tangent line to form a notch. A cutout is formed by polishing a part of the surface and the inner circumference in the circumferential direction, or a cutout is formed in a part of the upper circumference (or lower circumference) as shown in Figure 5. The magnetization method of the present invention can also be applied to a structure in which a portion is formed.

(Effects of the Invention) As described above, according to the present invention, the stator of a motor using a stator having a notch on its circumference can be magnetized so as to prevent uneven rotation of the rotor. has.

[Brief explanation of drawings]

1 and 2 are a plan view and a side view, respectively, of a stator magnetic body, a yoke, and an electromagnet that are combined to carry out the present invention, and FIGS. 3 and 4 are respectively, a plan view and a side view of a stator magnetic body, a yoke, and an electromagnet that are combined to carry out the present invention. Magnetic field strength characteristic diagram along the inner circumferential surface of the magnetized stator magnetic material,
FIG. 5 is a perspective view of another stator magnetic body to which the magnetization method of the present invention is applied, and FIGS. 6 and 7 are respectively a stator magnetic body and an electromagnet combined to perform the conventional magnetization method. a plan view and a side view of
FIG. 8 is a magnetic field strength characteristic diagram along the inner circumferential surface of a stator magnetic body magnetized by a conventional method. 1... Electromagnet, 2... Ring-shaped yoke, 4...
Excitation coil, 6... Gap, 7... Magnetic material for stator, 8... Notch.

Claims (1)

[Claims] 1. A ring-shaped stator magnetic body having a notch on its circumferential surface and a ring-shaped yoke having a gap formed by an open end are placed concentrically and in close contact so that the notch and the gap are close to each other. By applying current to the excitation coil of the electromagnet, a magnetic flux is caused to flow along the circumferential direction from the inner circumferential surface or outer circumferential surface of the stator magnetic material and the ring-shaped yoke, which are arranged concentrically. , a magnetization method characterized by magnetizing a stator magnetic material along its circumferential surface.