JPS5866567A - Magnetic thrust unit for coreless motor - Google Patents

Abstract

PURPOSE:To stabilize the contact resistance between a brush and a commutator with the direction of a thrust load constant by fixing a magnetic disc corresponding to a field magnet to a rotational shaft. CONSTITUTION:A magnetic disc 16 opposed to the axial end surface of a field magnet 7 is disposed between the inner bottom of an armature coil 9 and a coil fixing plate 10 and is fixed to a rotational shaft 4. Since the axial leakage magnetic flux of the magnet 7 partly attracts the disc 16 at this time, an armature is pulled and the surface of a brush 15 contacted with the commutator 14 always becomes constant, and the contacting degree is improved. On the other hand, a thrust washer 17 interposed between the bearing 5 and the plate 10 is composed by superposing washers of two different types in outer diameter, thereby reducing the adverse influence of punched burr.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC coreless motor in which the armature has no iron core, and the contact resistance between the brush and commutator is stable and rotational unevenness is reduced. The purpose is to obtain.

Conventionally, a configuration shown in FIG. 1 has been generally used as a coreless motor. Below, the configuration 2 "-' will be explained based on the drawings. 1 is a motor frame,
2 is a bracket that covers the opening of the motor frame 1; 3 is a cylindrical bearing housing with one end fixed to the center of the motor frame 1; and a metal bearing 5 that supports the rotating shaft 4.
6 is equipped.

7 is a ring-shaped field magnet fixed to the outer periphery of the bearing housing 3; 8 is a yoke fixed to the inner surface of the motor frame 1 facing the field magnet 7; 9 is a magnet rotating between the field magnet 7 and the yoke 8; It is a cup-shaped armature coil that can be freely installed, is made rigid by resin molding, and is fixed to the rotating shaft 4 via a coil fixing plate 10 made of a non-magnetic material.

11.12 is a thrust washer made of synthetic resin that adjusts play in the thrust direction of the rotating shaft 4, and is installed between the bearing 6 and the coil fixing plate 1o, and between the retaining ring 13 fixed to the rotating shaft 4 and the bearing 6. is equipped with.

14 is a commutator fixed to one end of the rotating shaft 4, with which a brush 16 is constantly in contact.

As is clear from the above configuration, in a coreless motor, there is no iron core in the armature, so 3'', -
'The armature is not pulled in one direction by the field magnet 7, and the armature is unstable in the axial direction. As a result, the contact position between the brush 15 and the straightener 14 changes, making the contact M (resistance) unstable, which has the drawback of adversely affecting the characteristics of the motor.

To solve this problem, a two-way coreless motor has been proposed that maintains the thrust load in a fixed direction by adding a magnetic material to the armature, but this type of coreless motor is supported by a group of coreless thrust washers, and conventional In the configuration of
The thrust support surface provided by the thrust washer l' was unstable, which had a large effect on uneven rotation. Zunawa'
(Since the thrust thrust washer 11 uses multiple washers with the same outside diameter dimension stacked on top of each other, the punching holes that occur on the outside diameter of the washers interact with each other, making it difficult for the thrust support surface to be uniform and preventing uneven rotation. Many people had an impact on the outbreak.

Note that thrust washers are usually formed by punching out synthetic resin sheets, and it is difficult to avoid the occurrence of punching burrs, so removing the burrs in post-processing is considered, but It takes a lot of time to process, and considering productivity and high cost, it is difficult to completely remove the punched particles.

The present invention has been made in view of the above points, and one embodiment of the present invention will be described below with reference to FIGS. 3 and 4. Note that parts that are the same as those in the conventional configuration described above are designated by the same numbers, and their explanations will be omitted. In FIG. 3, reference numeral 16 denotes a magnetic disc facing the axial end face of the field magnet 7, located between the inner bottom of the armature coil 9 and the coil fixing plate 100,
It is fixed on the screen. Here, since the field magnet 7 is magnetized in the radial direction, most of the magnetic flux contributes to the rotation of the armature coil 9, but a part of the leakage magnetic flux in the axial direction attracts the magnetic disc 16. Therefore, the armature is pulled in the direction of the arrow, and the surface where the brush 15 touches the current element 14 is always constant.
The degree of contact is opposite. On the other hand, as shown in FIG.
The thrust washers 17 interposed between the coil fixing plate 10 and the coil fixing plate 10 include two types of washers 17a having different outer diameters,
17b1-2 are stacked one on top of the other, so that the punches that occur in the opening diameter do not interact with each other, and the influence of punches can be reduced.As a result, many washers can be stacked,
It is also possible to lower the reduction ratio per washer from the coil fixing plate 10 to the bearing 5.

As is clear from the above description, according to the present invention, the direction of the thrust load becomes constant due to the attractive force of the field magnet acting on the magnetic disc, the contact resistance between the brush and the commutator becomes stable, and the external Since washers with different diameters are piled up to receive the thrust load, it is possible to reduce the influence of punching out of the washers, and the occurrence of uneven rotation can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional coreless motor, FIG. 2 is a sectional view of a thrust washer in the same motor, FIG. 3 is a sectional view of a coreless motor according to an embodiment of the present invention,
The figure is a sectional view of the thrust washer part in the same motor. 61゛- 1... Motor frame, 3... Old bearing housing, 4... Rotating shaft, 5.6... Bearing,
7...Field magnet, 9...Armature coil, 1o...°Coil fixing plate, 16...
...Magnetic disk, 17.17&, 17b...°゛°°
Name of Thrust Attorney Patent Attorney Toshio Nakao and 1 other person 1st
Figure 4 Figure 3 Figure 4

Claims (1)

[Claims] A cup-shaped armature coil rotatably installed between a field magnet and a motor frame is fixed to a rotating shaft supported by a bearing provided in a bearing housing, and a cup-shaped armature coil is installed at the bottom of the armature coil. a magnetic disk corresponding to the field magnet etc. is fixed to the rotating shaft, and at least two types of thrust washers having different outer diameters are inserted into the rotating shaft between the bearing and the armature coil section. A magnetic thrust device for a coreless motor equipped with.