JPS59159656A - Permanent magnet type flat motor - Google Patents

Abstract

PURPOSE:To obtain a flat motor having low irregular rotation by forming the thickness of the axial direction of an outer circle of a doughnut-shaped permanent magnet larger than that of an inner circle. CONSTITUTION:A disc-shaped armature 2 is disposed in parallel at the prescribed interval to a doughnut-shaped permanent magnet 1. A disc-shaped rotary support 3 fixes the magnet 1 to a shaft 4, which is passed through the magnet 1 and the rotating center of the armature 2. The axial thickness t1 in the bore r1 of the inner circle of the magnet 1 is constant on the inner periphery, the thickness t2 in the bore r2 of the outer circle is constant on the outer periphery, and constructed so that the thickness t2 is larger than t1. In this manner, a flat motor having low irregular rotation can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a permanent magnet type flat motor used for winding tape in, for example, a VTR.

A conventional permanent magnet type flat motor is shown in FIG. 1(a). (1) r/i, a donut-shaped flat plate permanent magnet, with N, 5ffl-holes arranged alternately on the circumference as shown in FIG. 1(b). (2) is the armature, which has a permanent magnet (1
) are arranged in parallel with each other at a predetermined distance. (3)
is a disc-shaped rotating support that connects the permanent magnet (1) to the shaft (4).
). The shaft (4) passes through the rotation centers of the permanent magnet (1) and the armature (2), and rotates as the permanent magnet (1) rotates.

When the periodically magnetized permanent magnet (1) becomes a field and a current flows through the armature (2), the water recreation stone (1) rotates due to the interaction with the armature (2).

However, from the point of view of image performance, it is necessary to severely suppress the uneven rotation of the motor, and for this purpose it is conceivable to increase the inertia of the rotating body to some extent. In the conventional permanent magnet type flat motor as described above, there is a drawback that increasing the inertia of the rotating body, that is, the permanent magnet, becomes very expensive.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional magnets, and the thickness of the outer circle of the donut-shaped permanent magnet in the direction of the rotation axis is larger than that for internal use. The object of the present invention is to provide a Hiku magnet-type flat motor with increased inertia and low rotational unevenness without increasing the amount of expensive magnet material.

An embodiment of the present invention will be described below with reference to the drawings. @2
In the figure, the radius of the inner circle of the donut-shaped permanent magnet (1) is 1
・Listness in the rotational axis direction at l [l is constant on the inner circumference,
The thickness t2 at the radius r2 of the outer circle is constant on the outer circumference, and the thickness t2 of the outer circle is larger than the inner thickness [1]. ) side slopes from the inner circle to the outer circle. The support (3) is also constructed in this manner.

A current is applied to the armature (2), and the armature (2) and the permanent magnet (
1), the permanent magnet (1) and shaft (4) rotate, but since the outer periphery of the permanent magnet (1) is made to withstand heavy loads, the inertia in rotation increases, causing rotational It's all about making the unevenness low. The amount of increase in inertia of the fruit is shown by the following calculation.

The weight is proportional to ~■ in the following equation, W = J 27rr (tt+-(r-r
1]) drrl r2-r1 inertia is proportional to ↓ of the following equation J=J 2πr(H+-(r-rl))r2drr
l r2-rl e.g. r2=35
, r 1 = 15, t l = t 2 = 7 compared to the conventional type, r2 = 35, rl < 15, t I = 35, t 2 = 9.
In the present invention, which is set to 7, the weight is the same, but the inertia is increased by about 1 bite.

Further, since the donut-shaped permanent magnet (1) has a large spacing between poles on the outer periphery, the amount of pole magnetic flux also becomes larger on the outer periphery.

Therefore, by increasing the thickness of the outer periphery as in this invention, the thickness of the magnetic path is not large and the resistance to armature reaction is increased.
This will further enhance the performance of the motor.

In the above embodiment, the permanent magnet (1) was configured to be sloped from the inner circle to the outer circumference, but a step is provided between the inner circle and the outer circle, so that the outer circle is smaller than the thickness of the inner circle by 2. If the structure is such that the thickness is increased, the processing is simple and the same effect can be obtained.

As described above, the present invention includes a disc-shaped ζ-shaped armature, a donut-shaped permanent magnet arranged parallel to the armature at a predetermined distance, and a center of rotation between the armature and the permanent magnet. and a shaft fixed to the permanent magnet and the supporting material, by making the thickness of the outer circle of the permanent magnet in the direction of the rotation axis smaller than the thickness of the saw circle, This has the effect of obtaining a flat morph with low rotational unevenness.

[Brief explanation of drawings]

Fig. 1(a) is a sectional view showing a conventional permanent magnet type flat morph, Fig. 1(bJ is a sectional view taken along the line A-1 in Fig. 1(a). An example of an example
It is. In the figure 2, (1) is a permanent magnet, (2) is a t/'i tunic, (3) is a supporting paulownia, and (4) is a shaft. In addition, in the figures, the same reference numerals are the same as - or il'i: + The relevant part is indicated. - Figure 1 (θ) Figure 2

Claims (1)

[Claims] A disk-shaped armature, a donut-shaped permanent magnet arranged parallel to the armature at a predetermined distance, and a donut-shaped permanent magnet that passes through the center of rotation of the armature and the permanent magnet, and is fixed by the permanent magnet and the supporting material. 1. A permanent magnet type flat motor comprising a shaft, wherein the thickness of the outer circle of the permanent magnet in the rotation axis direction is larger than the thickness in Japan.