JPS642538Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a brushless motor equipped with a frequency generator.

PRIOR ART A conventional brushless motor equipped with a frequency generator will be described with reference to FIG. 1. A rotor gear 3 having a concavo-convex portion formed on the inner circumferential side is press-fitted into a shaft 2 forming a part of a rotor 1. 3 is further press-fitted into the rotor yoke 4. A multi-pole magnet 5 is fixed to the rotor yoke 4. Further, the shaft 2 is rotatably supported by bearings 6, 7 and a thrust bearing 8. The bearings 6 and 7 are held by a housing 9, and a stator yoke 10 is fixed to the housing 9. A plurality of drive coils 11 are fixed on the stator yoke 10, and each terminal of the coil is connected to the circuit board 12.
It is electrically connected to the upper copper foil pattern to form a stator. A stator gear 13 having a concave and convex portion formed on the outside is fixed to the rotor 1 side of the housing 9, and above and below the gear 13 there are bobbins that house speed detection coils 14, and the rotor gear 3
A power generation magnet 15 facing the is arranged.

In the above structure, the number of teeth of the rotor gear 3 and the teeth of the stator gear 13 are the same, or some of the teeth facing each other are reduced, and are made of a soft magnetic material.

Now, considering the case where the rotor 1 rotates, when the teeth face each other, the magnetic resistance of this magnetic circuit becomes small, and the magnetic flux emitted from the power generation magnet 15 flows more easily. Conversely, when the teeth and valleys face each other, magnetic resistance increases and magnetic flux becomes difficult to flow.

As a result, the amount of flowing magnetic flux alternately changes, and an alternating current voltage appears in the coil 14.

However, in this frequency generator, since it is necessary to reduce the level fluctuation of the output frequency voltage, it is necessary to equalize the gap between the teeth of the stator gear 13 and the rotor gear 3 over the entire circumference, so they are concentric. This assembly is an important issue in terms of the performance of the frequency generator.

In addition, the conventional device requires a rotor gear with a dedicated internal tooth shape, and has problems such as eccentricity of the gear directly resulting in uneven rotation.

As another conventional example, as disclosed in Japanese Utility Model Application Publication No. 56-4375, a flange is provided at the lower end of the peripheral edge of the rotor yoke, and a plurality of slits are provided at equal intervals in the circumferential direction of the flange. A speed detection coil is formed by printed wiring on the stator yoke facing the stator yoke, and the magnetic flux from the rotor magnet is leaked to the flange via the drive coil, stator yoke, and speed detection coil, and the magnetic flux is determined by the presence or absence of slits. There is one that detects the rotation speed by detecting the strength of the rotation speed using a speed detection coil.

In this conventional example, leakage magnetic flux is used, and the air gap length including the drive coil is large, so the magnetic flux is small, the detection output of the speed detection coil is small, and the radial dimension is large due to the collar. There are drawbacks.

Purpose of the invention The object of the present invention is to provide a brushless motor equipped with a frequency generator that has a simple structure, reduces the effects of eccentricity, etc., and has good performance by solving the problems of the conventional motor.

Composition of the present invention The present invention includes a stator to which a drive coil is attached,
A rotor is provided with a rotor magnet mounted on a rotor yoke that faces the drive coil in the axial direction, and a speed detection coil and a stator gear are mounted on the stator centrally from the mounting position of the drive coil. The present invention is a brushless motor equipped with a frequency generator, characterized in that a plurality of concavo-convex portions or holes facing the stator gear are provided in an annular shape on a side rotor yoke.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 2 to 4. Incidentally, the same parts as in the conventional example are given the same reference numerals, and the description thereof will be omitted.

As shown in the figure, an uneven portion 16 is formed on the rotor yoke 4.
Alternatively, the holes 17 are provided concentrically, the stator gear 13 is arranged so as to face the holes 17, and the stator gear 13 is bent so as to approach the rotor magnet 5. The speed detection coil 14 is arranged at a position surrounded by the stator gear 13, rotor magnet 5, and rotor yoke 4. In some cases, a noise canceling coil may be installed in the stator gear 13.
Place it below the . On the other hand, the inner peripheral side of the rotor magnet 5 is magnetized in the axial direction as a power generation magnet, so that the power generation magnet and the rotor magnet are shared.

In this way, by arranging a plurality of concave and convex portions 16 concentrically on the rotor yoke 4 made of a magnetic plate, or by arranging a plurality of fan-shaped or rectangular holes,
The rotation of the rotor causes the speed detection coil 14 placed side by side with the biased magnetic member to generate electricity.

FIG. 3 is a perspective view of the rotor yoke 4 subjected to pressing or the like to form uneven portions 16.
The figure is a cross-sectional view of the power generation magnet 15 arranged around the speed coil 14, and the magnetic flux flows in the direction of the arrow in the figure.

Effects of the invention As explained above, according to the invention, there is no need for a dedicated rotor gear for the frequency generator, which simplifies the structure of the rotor and reduces the number of assembly steps. , and power consumption can be reduced.

In addition, since an uneven part or a hole can be formed by pressing on the center side of the rotor yoke to which the rotor magnet is attached, the hole for the rotor shaft and the rotor gear part for the frequency generator can be formed integrally, and the eccentricity of the rotor gear can be Non-uniformity can be significantly reduced.

Furthermore, compared to the other conventional examples described above, the detection output of the speed detection coil in the frequency generator can be increased, and the radial dimension of the brushless motor can be reduced.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing a conventional example, FIGS. 2 to 4 are related to the present invention, FIG. 2 is a vertical sectional view showing an embodiment of the present invention, and FIG. 3 is a perspective view of the rotor yoke. FIG. 4 is a longitudinal sectional view showing a different embodiment. 1... Rotor, 2... Rotor shaft, 3...
Rotor gear, 4...Rotor yoke, 5...Rotor magnet, 10...Stator yoke, 11...
Drive coil, 13... Stator gear, 14... Speed detection coil, 16... Uneven portion, 17... Hole.

Claims (1)

[Scope of utility model registration request] The stator includes a stator to which a drive coil is attached, and a rotor in which a rotor magnet facing the drive coil in the axial direction is attached to a rotor yoke, and a speed detection coil and a stator gear are attached to the stator on the center side from the attachment position of the drive coil. A brushless motor equipped with a frequency generator, characterized in that a plurality of concavo-convex portions or holes facing the stator gear are provided in a circular shape on a rotor yoke on the center side of the rotor magnet.