JPS59188368A - Coreless motor - Google Patents

Abstract

PURPOSE:To increase the output of a coreless motor by forming a gradient in a magnetic circuit constituent member made of a magnet and a yoke in coincidence to the pulling slope at the time of shaping an armature coil, thereby reducing the distance between the yoke and the magnet. CONSTITUTION:A commutator 2 is mounted on a shaft 1, a coil 3 is integrally molded with a molding material 4 to form a cup-shaped armature, and mounted rotatably through bearings 5a, 5b on frames 6a, 6b, a magnet 7, an inner yoke 8, an outer yoke 9 and a brush 10. The magnet 7 and the yoke 9 are similarly formed with a gradient in coincidence to the pulling slope theta at the time of shaping a cup-shaped armature to construct a small air gap between the magnet 7 and the yoke 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coreless motor, and more particularly to a coreless motor that uses a cup-shaped coreless armature to configure a suitable magnetic circuit.

Conventionally, it is known that the cup-shaped armature of a coreless motor is made by integrally molding and fixing a coil electrically connected to a commutator to a shaft using a molding material, and the cylindrical surface of the cup is removed from the mold after molding. It is a well-known fact that a conical shape with a draft angle of 1° to 2° is practically used for mold release. However, the distance between the yoke and the magnet increases, resulting in a decrease in the magnetic flux passing through the air gap between the yoke and the magnet, resulting in a reduction in output.

In order to eliminate the above-mentioned drawbacks, the present invention aims to provide a high-output coreless motor by reducing the distance between the yoke and the magnet, and an embodiment shown in the drawings will be described below.

In the drawings, reference numeral 1 denotes a shaft that supports a rotating body, to which a commutator 2 is attached, and a coil 3 wound using a known technique is molded and fixed together with a molding material 4 to form a cup-shaped armature, which is attached to a frame via a bearing 5a15b. 6a, 6
b. It is rotatably assembled to the magnet 7, inner yoke 8, outer yoke 9, and brush 10. With the above-described configuration and using a well-known technique, by passing a current through the brush, the current flows through the commutator 2 and into the coil 3 to generate torque.

Here, the draft angle θ during molding of the cup-shaped armature is 2° to 3°, which is more than double the above-mentioned minimum practical value, to improve mold releasability and prevent breakage during mold release. Further, the magnet 7 and the outer yoke 9 are similarly sloped in accordance with the draft angle θ, so that the gap between the magnet 7 and the outer yoke 9 is reduced.

With the above configuration, it is possible to reduce the air gap in the magnetic circuit consisting of the magnet 7, inner yoke 8, and outer yoke 9, and as the permeance of the air gap increases, the permeance coefficient at the operating point of the magnet increases, resulting in the amount of magnetic flux in the air gap. By increasing the number, it is possible to provide a coreless morph with an output anop.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing an embodiment of the motor of the present invention. 1... Shaft, 2... Commutator, 3... Coil, 4... Mold material, 7... Magnet. Representative Patent Attorney Takashi Okabe

Claims (1)

[Claims] A coreless motor in which an armature coil is resin-molded into a cup shape, characterized in that a magnetic circuit component consisting of a magnet 7 and a yoke is also sloped to match the draft angle when the armature coil is molded. coreless motor.