JPS59216458A - Dc motor - Google Patents

Abstract

PURPOSE:To reduce the thickness of a DC motor and to sufficiently achieve the performance of a magnet by employing as a permanent magnet an anisotropic magnet in a thicknesswise direction and having sole-pole magnet of N- pole at one side and S-pole at the other side. CONSTITUTION:Upper and lower magnet teeth 12A, 12B formed of soft magnetic material are secured at both sides of a magnet 13 to a rotational shaft 11, and respectively rotatably via upper and lower ball bearings 15A, 15B. A printed board 17 is secured to the inside of a back yoke 14A. The magnet 13 is an anisotrpic magnet of thicknesswise direction, and has sole-pole magnet of N-pole at one side and S-pole at the other side. A coil 18 for generating torque is secured to the board 17.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an axial gap type Do motor, and more specifically, the permanent magnet used is a unipolar magnet with N poles on one side and 8 poles on the other side, and a magnet made of a soft magnetic material. The present invention relates to a Do motor characterized by having multiple poles formed by teeth.

Conventionally, as shown in the sectional view of FIG. 1, a rotor yoke 2 is fixed to a rotating shaft 1, and a multipolar permanent magnet 3 is fixed to the rotor yoke. The permanent magnet has a plurality of N poles in the axial direction as shown in the figure. Two ball bearings 5A and 5B are attached to the housing 4, and the rotating shaft 1
can rotate via this ball bearing.

A back yoke 6 is fixed to the housing 4, a printed circuit board 7 is fixed to the magnet side of the back yoke, a plurality of coils 8 are fixed to the printed circuit board, and the terminals of the coils are connected through the printed circuit board (not shown). Not connected to the drive circuit. A suitable gap is maintained between the coil 8 and the magnet 5. Regarding the rotational operation, although not shown, the drive circuit elements are switched by a magnetic pole detection element such as a Hall element, so that a rotational driving force is generated in the coil. However, this conventional motor has several drawbacks as shown below.

(1) Since the magnet and coil are stacked on top of each other, the thickness of the motor increases, making it difficult to make it thinner.

(2) The magnet must have multiple poles if&1, which not only complicates the magnetizing device but also prevents the magnet from achieving the magnetizing ability that is appropriate to demonstrate its original performance. Magnet performance is poor. This tendency is particularly noticeable in samarium cobalt magnets for small motors. Therefore, the magnet has no choice but to use 70% to 90% of its basic performance, which is unreasonable.

The present invention solves all of the above-mentioned drawbacks, and an object of the present invention is to reduce the thickness of a DC motor. Another object of the present invention is to provide a DC motor with a magnetic circuit that can fully utilize the inherent performance of the magnets used in the motor.

Next, the present invention will be explained in detail with reference to the drawings. FIG. 2 is a sectional view of the main parts of an embodiment of the DC motor of the present invention.

Upper magnet teeth 12A and 12B made of a soft magnetic material are fixed to the rotating shaft 11 with a magnet 13 in between, and can be rotated by upper and lower ball bearings 15A and 15B. Back yoke 14A that also serves as upper housing
A lower housing 14B, which also serves as a shield, is fixed at the outer periphery. A coil 18 for generating torque is fixed via a printed circuit board 17, and the terminals of the coil are processed. The printed circuit board 17 is fixed to the inside of the back yoke 14A. The magnet 13 is an anisotropic magnet in the thickness direction, and is a unipolar magnet with an N pole on one side and 8 poles on the other side. It is located. Figure 3 is a plan view of the rotating shaft unit shown in Figure 2 taken out and viewed from above.This example shows an example of 8 poles (N and 8 poles each have 4 poles), but the number of poles is It is optional depending on the design conditions. As can be seen in Figure 3, the magnet 13 and coil 18 are not overlapped, making it possible to make the device extremely thin. The coil and magnet teeth are overlapped, but the magnet teeth are as thick as one piece of soft magnetic material, and are about 1 to 1.5 mm thick, so they can be ignored compared to the magnet of 3 to 10 mm. There are few. As magnets suitable for this motor, any material can be used, such as ferrite magnets, rare earth magnets, and metal magnets. However, in conventional axial type motors, the number of magnetized poles of the magnet is plural, so it is necessary to install the motor after magnetizing it in advance, and only magnets with large coercive force can be used. Furthermore, due to the magnetization of multiple poles, sufficient saturation magnetization is impossible, reducing the magnet performance by 10%.
The current situation is that 0% cannot be utilized, and this is especially noticeable with rare earth magnets.

As described above, the magnet of the present invention is a single-pole magnet in the thickness direction, so it is possible to sufficiently saturate magnetize from the outside after assembling the motor, so that the magnet can exhibit 100% of its original magnetic performance. Especially when rare earth magnets are used, it is possible to provide extremely high performance and high efficiency motors. The coil 18 may be a coil wound with wire, but
If a thin coil such as a plated coil or an etched coil is used, the magnetic resistance of the magnetic circuit will be reduced, which is extremely advantageous for the purpose of thinning the magnetic circuit. Although both the conventional example and the embodiment of the present invention have been described using a brushless DC motor as an example, it is also possible to use a brushed motor, and they are common.

As described above, the DC motor of the present invention can be made thinner and can fully demonstrate its magnetic performance, improving the performance of the motor, and will be used in future portable electronic devices, VTRs, hand belt computer peripherals, etc. is not only optimal, but can also be widely applied to DC motors to demonstrate its effectiveness.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional axial gap type DC motor, Fig. 2 is a sectional view of the main part of an embodiment of the DC motor of the present invention, and Fig. 3 is a plan view of the rotor portion of the Do motor of the present invention. 1: Rotating shaft 3: Magnet 8: Coil 11: Rotating shaft 12AB: Magnet tooth 13: Magnet 18: Coil. Above Figure 1 Figure 2

Claims (1)

[Claims] (1) In an axial gap type DO motor in which a permanent magnet and a coil are arranged in the direction of the rotation axis, the permanent magnet is an anisotropic magnet in the thickness direction, and one side has a low N pole. A DO motor characterized in that it is a single-pole magnet with eight poles. (2) The permanent magnet and the coil do not directly face each other, but face the coil through magnet teeth made of a soft magnetic material that are connected to one permanent magnet. DO motor. (8) The DO motor according to claim 2, wherein the magnet teeth made of a soft magnetic material and connected to the permanent magnets have multiple poles.