JPS6037006Y2 - small dc motor - Google Patents

Description

[Detailed description of the invention] The present invention relates to a small DC motor with a cup-shaped ironless core armature, and a yoke that passes the magnetic flux of a field magnet placed inside the cup and holds a bracket to which a brush is attached. By dividing the motor into two parts, the purpose is to provide a motor that is inexpensive and easy to maintain and inspect.

As shown in FIG. 1, a small DC motor with a conventional cup-shaped coreless armature has a field magnet 1. metal 2
, 2' are attached to a housing assembly, a commutator in which a commutator segment 4 is molded with a mold 5, a coil 6, and a shaft 7 are integrally molded with resin 8. Insert the armature A, further insert the yoke 9 into the outer periphery of the armature A, fix one end of the yoke 9 to the housing 3, and the terminal plate 11 to which the brush 10 is spot welded.
It was constructed by inserting and fixing the bracket 12 with the attached bracket into the other end of the yoke 9.

In addition, 13 is a thrust washer, 14 is an E-ring washer for preventing the armature from being pulled out, and 15 is a coil end portion on the outer periphery of the opening of the armature A, which has a convex shape to hold the coil end.

In such a conventional structure, (1) the coil end convex portion exists on the outer periphery of the opening of the armature A, so the shape of the yoke 9 becomes extremely complicated;
Generally, the yoke 9 must be made by cutting,
Manufacturing costs were rising.

(2) Since the weight of the yoke 9 is large, it is necessary to firmly hold the yoke 9 at the B portion in order to sufficiently withstand drops and impacts.

Therefore, once part B is removed for maintenance and inspection of the armature, the same yoke cannot be used again.

■ York 9. When armature A is removed, iron powder and other foreign matter adhere to the magnet 1 inside.

There were other problems.

The present invention solves the above-mentioned conventional problems.

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 2, the same members as in FIG. 1 are given the same numbers, and the difference from FIG.
, 9B.

That is, 9A is an outer yoke having an inner diameter slightly larger than the convex portion on the outer periphery of the opening of armature A, and 9B is an inner yoke having an inner diameter slightly larger than the outer periphery of armature A and having the same height as armature A. One end of the outer yoke 9A is caulked to the housing 3, and the inner yoke 9B is inserted into the outer yoke 9A.

Furthermore, the bracket 12 is inserted into the other end of the outer yoke 9A, and the bracket 12 is held by caulking the 0 part of the outer yoke 9A.

As the inner yoke 9B, not only a pipe-shaped one but also a cylindrical one formed by bending a plate may be used.

In addition, if a ferromagnetic material with high permeability, such as pure iron permalloy, is used for the inner yoke 9B, leakage magnetic flux to the outside can be reduced.
Motor output can be increased.

The small DC motor of the present invention has the configuration shown in the above embodiment, and has the following effects.

- Since the yoke is divided into two parts, the inner and outer parts, the yoke can be made from a pipe or by press working, making it extremely inexpensive to manufacture and improving mass productivity.

■ It is now possible to assemble while measuring the distance between the coil end protrusion 15 on the outer periphery of the armature opening and the outer yoke 9A (section D) visually or with a jig, improving the reliability of the finished product. do.

■ To perform 9 maintenance inspections on the armature, attach the bracket 12.
This can be done by removing the caulked part (part 0) of the outer yoke 9A that holds the outer yoke 9A and taking out the inner yoke 9B. Since it is sufficient to leave the magnet 1 in the same state, it can be easily carried out, and since the outer yoke 9A is not removed, there is no possibility that iron powder or the like will adhere to the magnet 1.

■ Since the inner yoke 9B is provided only for the purpose of effectively passing field flux, if a ferromagnetic material is used for this material, the cost will be lower than if a ferromagnetic material is used for the entire yoke material. It is possible to obtain an efficient, small, and high-output motor without increasing the cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional small DC motor, and FIG. 2 is a sectional view of a small DC motor showing an embodiment of the present invention. 1...Field magnet, 3...Housing, 6...Coil, 9A...Outer yoke, 9B...Inner yoke, 10... Brush, 12... Bracket, 15... Coil end portion, A... Armature.

Claims (2)

[Scope of utility model registration request] (1) It has a coreless armature in which a convex part protruding outward is formed on the coil end on the outer periphery of the cup opening of a coil wound in a cup shape, and the armature is attached to the housing inside the cup of this armature. A small DC motor in which a field magnet is arranged and a yoke is arranged outside the armature,
The yoke has a cylindrical outer yoke whose inner diameter is slightly larger than the convex portion on the outer periphery of the opening of the armature, and a cylindrical outer yoke having a substantially uniform inner diameter and whose inner diameter is slightly larger than the convex portion on the outer periphery of the opening of the armature. Consisting of a cylindrical inner yoke that is slightly larger than the outer circumference of the armature and has a height almost equal to the height of the armature. One end of the outer yoke is fixed to the housing, and the inner yoke is inserted into the outer yoke. A small DC motor equipped with a yoke and having a bracket having a brush held at the other end of the outer yoke. (2) A small DC motor according to claim 1, which uses a ferromagnetic material with high magnetic permeability as the inner yoke.