JPS6026545Y2 - small flat motor - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a small flat motor in which a stator field magnet and a plate-shaped armature oppose each other through an axial gap, and to a rotation speed detection mechanism thereof.

Since motors used in audio products and the like are required to have constant rotational speed performance, they are generally provided with constant speed control means for the rotational speed.

Various types of constant speed control means have been proposed, but when constant speed rotation performance is important, a speed generator is attached to the rotating shaft.

However, the provision of a speed generator increases the overall size, making it impossible to use it as a rotational drive source for products that require miniaturization of equipment.

In view of this, the present invention aims to provide a rotation speed detection mechanism without impairing the characteristics of a small flat motor with a reduced axial length.An embodiment of the present invention will be explained based on the drawings. do.

1 and 2 are a sectional view and a perspective view of a commutator of a small flat motor according to the present invention.

In these figures, reference numeral 1 denotes a cylindrical motor case with a bottom, and a field magnet 3 is attached to the inner surface of a bracket 2 that covers the bottom opening of the motor case.

A rotating shaft 6 rotatably supported by bearings 4 and 5 provided at the center of the bottom surface of the motor case 1 and the center of the bracket 2, respectively.
A plate-shaped armature body 8 and a cylindrical commutator 9 are attached to the field magnet 3, which oppose each other with an axial gap 7 interposed therebetween.

The commutator is located in the central hole 10 of the field magnet 3, and brushes 11.11 in sliding contact with the commutator 9 are mounted on the inner surface of the bracket 2.

As shown in FIG. 2, the commutator 9 has a number of commutator pieces 12 corresponding to the number of coils in the armature body 8 held and fixed by an insulating base 13 made of a resin material. be.

In the present invention, the insulating base 13 includes each commutator piece 12...
The insulating base 13 extends from a cylindrical portion 14 supporting the cylindrical portion to a disc portion 15 perpendicular to the cylindrical portion, and magnetic powder is mixed in the insulating base 13.

The outer periphery of the disk portion 15 located on the outer periphery of the riser 16 of each commutator piece 12 is magnetized as shown by diagonal lines in FIG. 2, and a magnet ring 17 is formed.

The magnet ring is magnetized in the axial direction, and is formed by magnetizing so that adjacent magnetic poles in the circumferential direction are different from each other.

The commutator 9 is the opposing surface 1 of the armature body 8 that opposes the field magnet 3.
8, and the magnet ring 17 is located at the outer periphery of the commutator 9 on the opposing surface 18.

A magnetically sensitive member 19 is attached to the inner surface of the bracket 2 to detect changes in magnetic flux from the magnet ring 17 as the magnet ring rotates.

As the magnetically sensitive member 19, a magnetoresistive element, a Hall element, a detection coil, etc. can be used.

Therefore, the magnet ring 17 and the magnetic sensing member 19 constitute a rotational speed detection mechanism.

In the above embodiment, the cylindrical commutator 9 is used and the magnet ring 17 is provided on the outer periphery of the disk portion 15, but the magnet ring may be provided on the outer periphery of the plate commutator. .

This point will be explained based on the front view of the plate commutator shown in FIG.

That is, the plate-shaped commutator 20 has fan-shaped commutator pieces 21 supported and fixed on the back surface thereof by an insulating base 22.

In the present invention, the insulating base body is extended to the outer periphery of each commutator piece 21 to form the disk portion 23. The magnetic powder mixed in the waist insulating base body 22 is placed on the outer periphery of the disk portion 23 as shown by diagonal lines. The magnet ring 24 is formed by magnetizing the magnet ring 24.

The magnetization of the magnet ring is the same as that of the magnet ring 17 shown in FIG. Yes.

In addition, in each example, the magnet ring 17.2
4 is integrally formed on the outer periphery of the disc portion 15, 23 of the commutator 9, 20, but it is clear that it may be formed separately.

As described above, according to the present invention, a magnet ring is provided at the outer circumferential position of the commutator located at the center on the opposing surface of the plate-shaped armature body that opposes the field magnet, and the inner surface of the bracket to which the field magnet is attached. Since a magnetically sensitive member opposing the magnet ring is provided at the center hole of the field magnet along with a brush that slides into contact with the commutator, the extra space inside the motor case can be utilized to reduce the axial length. A rotational speed detection mechanism can be provided without impairing the characteristics of the small flat motor.

Furthermore, when the magnet ring is integrally formed on the outside of the disc portion of the commutator, the magnet can be easily formed and attached, contributing to miniaturization of the entire motor.

[Brief explanation of the drawing]

The drawings show an embodiment of a small flat motor according to the present invention; FIG. 1 is a sectional view of the motor, FIG. 2 is a perspective view of a cylindrical commutator, and FIG. 3 is a front view of a plate commutator. 3... Field magnet, 8... Plate armature body, 18... Opposing surface, 9, 20... Commutator, 17.24. ...Magnetic ring, 2...
・Bracket l-119・・・Magnetic sensitive member, 15,2
3...Disc part.

Claims (1)

[Scope of utility model registration request] A magnet ring is provided on the outer periphery of the disk portion of the commutator located at the center on the opposing surface of the plate-shaped armature body that opposes the field magnet, and a magnet ring is provided in the center hole of the field magnet on the inner surface of the bracket to which the field magnet is attached. A small flat motor comprising a magnetically sensitive member opposing the magnet ring at a position along with a brush slidingly in contact with the commutator.