JPH0130875Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an ultra-small flat motor suitable for use in a microcassette type tape recorder.

In recent years, with the miniaturization of microcassette tape recorders, there has been a demand for the direct current motor that drives the tape to be miniaturized as much as possible.

Conventionally, as shown in FIG. 1, a generally used axial gap type flat motor has a ring-shaped magnet 2 placed on a disc-shaped bracket 1, and the upper surface of this magnet 2 and the inner ceiling of a case 3 are connected to each other. A flat rotor 4 with integrated coils is arranged in the gap formed between the two, a commutator 5 is attached to the rotor 4, and a pair of brushes 7, 7 are fixed to the bracket 1 via a brush base 6. A rectifying device 567 consisting of a rectifying device 567 is disposed inside the magnet 2. In the figure, 8 and 9 are press-fitted into the case 3 and bracket 1, respectively, and are attached to the shaft 1.
This is an oil-impregnated bearing that supports the rotor 4 via the rotor 4.

However, in a compact cassette motor that requires a relatively large outer diameter with this configuration, the inner diameter of the magnet 2 can be set as large as possible, so there is no problem with the brush tension, but the micro cassette Since a motor for use in motors is required to have an outer diameter of about 20 to 22 mm, the inside of the magnet 2 must also be small, making setting the brush tension extremely difficult. For this reason, in order to cover this drawback, the inner diameter of the magnet 2 is increased, and the resulting brush placement part is designed to be large, at the expense of the resulting output (i.e., efficiency), or in order to cover this drawback, recently, As shown in Figure 2, the magnet 2 is provided with recesses 2a, 2a for brush placement, and the brushes 7, 7 are placed here.
A proposal has also been disclosed in which the setting of the brush tension is facilitated by arranging a magnet, but this creates a new drawback in that the magnet is easily damaged and the yield is reduced.

In addition, in order to prevent the problem of damage, a third
As shown in the figure, the magnet 22 is divided in advance,
A plan has also been adopted in which the brush holder 66 made of an insulating material is placed in the gap to hold the brush.
In this case, since the gap for arranging the brushes is quite wide, the effective cross-sectional area of the magnet is smaller than that of a ring-shaped magnet, resulting in an inefficient motor.

Furthermore, there is a problem that applies to any of the above cases, and it is necessary to use a non-adjustable method to obtain the electrical neutral point. In other words, the positions of the magnets and brushes are fixed, and therefore the positions of the commutator pieces and rotor windings must be kept constant, but since the motor body is small, the commutator is also small, and these must be fixed from the perspective of assembly. It was extremely difficult to maintain a constant positional relationship, leading to a decline in yield.

This device was devised to overcome the above-mentioned drawbacks, namely, a magnet having an inner diameter smaller than the inner diameter of the magnetic path plate is fixed concentrically to one side of the magnetic path plate, and a magnet is fixed concentrically to one side of the magnetic path plate. The main feature is that a bracket is arranged in the bracket, and the brush is arranged in this bracket so as to be housed within the thickness of the magnetic path plate.This makes it easy to set the tension of the brush, and also makes it extremely easy to set the electrical neutral point. The aim is to provide an ultra-compact flat motor that can be used in various applications.

The configuration of this invention will be explained below based on the embodiments shown in the drawings.

The feature of this device is that, as shown in FIG. 4, a magnet 2 having an inner diameter smaller than the inner diameter of the magnetic path plate is fixed concentrically to one surface of a magnetic path plate 11 made of a magnetic material such as iron. A bracket 13 is disposed on the surface via a vibration isolating rubber 12, a brush base 14 is attached to this bracket 13, and a brush unit consisting of a pair of brushes 7, 7 embedded in this brush base 14 is attached to the inner diameter part of the magnetic path plate 11. This is because the magnetic path plate is arranged so as to be housed within the thickness of the magnetic path plate.

As can be seen from the drawing, such a configuration
Since the position of the commutator 5 facing the brushes 7, 7 can be set downward, oil-impregnated bearings are not necessarily required at the top and bottom, and an axially long oil-impregnated bearing 1 fixed to the case 3 is used.
The rotor 4 is supported only by the rotor 5. In this example,
A suction plate 4a made of a magnetic stainless steel plate is arranged on the case side surface of the rotor 4, and a thrust bearing 1 is arranged at the center of a bracket 13 at the base of the shaft 10.
Although the rotor 4 is pivotably supported at 6, this configuration is effective in preventing movement of the rotor 4 in the thrust direction and suppressing noise generation. In the figure, 13a is a pair of mounting screw holes arranged on the bracket 13,
The magnetic pole of the magnet 2 on the magnetic path plate which is temporarily fixed by being urged inward of the case 3 by the attractive force of the magnetized magnet, and the brush 7 planted in the brush base 14 fixed on the bracket. , 7, and also serves as an adjustment hole for ensuring an electrical neutral point. And this bracket 13
After rotating to find the electrical neutral point, case 3
It is assembled by caulking the edges of the opening.

This invention allows the tension displacement of the brushes 7, 7 to be set to a large value without reducing the cross-sectional area of the magnet as described above, and therefore without sacrificing the effective air gap magnetic flux with respect to the rotor 4. ,
Variations in brush tension can be reduced, and a longer life can be expected than in the past.

Further, since the magnetic path plate 11 and the bracket 13 are free from each other before being caulked, the electrical neutral point can be easily adjusted since the relative position of each component is rough. Furthermore, since the magnet does not need to be separated, there is no difficulty in assembling it, and since the commutator can be positioned downward, a part of the oil-impregnated bearing 15 on the case side can be loosely fitted inside the rotor. Since only one bearing is required, centering is extremely easy.

Furthermore, in this embodiment, since the vibration isolating rubber 12 is interposed between the magnetic path plate and the bracket, it is also effective in reducing vibrations and mechanical noise caused by brushes, rotors, etc.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main part of a conventional axial gap type flat motor, FIG. 2 is a sectional view of the same main part of another conventional example, FIG. 3 is a sectional view of the main part of a third conventional example, and FIG. FIG. 4 is a sectional view of essential parts of the ultra-compact flat motor of the present invention. 2 is a magnet, 7 is a brush, 11 is a magnetic path plate,
13 is the bracket.

Claims (1)

[Claims for Utility Model Registration] 1. A magnet having an inner diameter smaller than the inner diameter of the magnetic path plate is fixed concentrically to one side of the magnetic path plate, and a bracket is arranged on the other side, and a brush is attached to the bracket. An ultra-compact flat motor arranged so as to be housed within the thickness of the magnetic path plate. 2. The ultra-compact flat motor according to claim 1, wherein the magnetic path plate is arranged on a bracket via a vibration isolating member.