JPH0343832Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Technical field of invention] The present invention relates to improvements in brushless motors.

[Technical background of the invention]

Conventionally, in a brushless motor, a rotor having magnetic poles made of a magnet attached thereto is rotatably provided to a stator made of an armature.

[Problems with background technology]

However, in the above-mentioned brushless motor, magnetic poles made of magnets are attached to the rotor, which increases the number of manufacturing steps as a whole, resulting in higher costs.

[Purpose of invention]

Therefore, an object of the present invention is to provide a brushless motor that can reduce manufacturing man-hours and contribute to lower costs.

[Summary of the idea]

In the present invention, a rotor is rotatably provided with respect to a stator made of an armature, the rotor is formed by forming a thin plate made of soft magnetic material into a cup shape, and the stator is disposed inside the rotor. At the same time, a peripheral wall portion of the rotor facing the stator is bent in an uneven manner in the circumferential direction so that convex portions and concave portions are alternately arranged at the same circumference, and the rotational position of the rotor is The feature is that a rotational position detecting means is provided.

[Example of idea]

An embodiment in which the present invention is applied to an external rotary brushless motor will be described below with reference to the drawings. First, in FIG. 1, reference numeral 1 indicates a machine frame, and a shaft cylinder portion 2 is erected on this machine frame 1. A stator 3 is disposed around the outer periphery of the shaft cylinder portion 2, and the stator 3 is composed of an armature formed by winding a stator coil 5 around a stator core 4. On the other hand, 6 is a rotating shaft, which is inserted into the inside of the shaft cylinder portion 2 and supported by bearings 7, 7.
A cup-shaped, ie, approximately cylindrical rotor 8 with a closed upper surface is attached to the rotating shaft 6.
is formed of a thin plate material made of soft magnetic material, and its peripheral wall is bent in an uneven manner in the circumferential direction as shown in FIG. Also, the recesses 8b, 8
b is located between both convex portions 8a and 8a and is opposed to each other;
The convex portions 8a and the concave portions 8b are alternately arranged at the same circumference, and the peripheral wall of the rotor 8 is located on the outer peripheral side of the stator 3,
The convex portions 8a, 8a are close to the stator 3. Thereby, the stator 3 is disposed inside the rotor 8. Reference numeral 9 denotes a printed circuit board disposed at the lower part of the inside of the machine frame 1, on which a photo sensor 10, for example, serving as a rotational position detecting means is disposed facing the lower end of the peripheral wall of the rotor 8. This optical sensor 10 includes a convex portion 8a and a concave portion 8 on the peripheral wall of the rotor 8.
It is designed to detect b.

In the above configuration, when the stator coils 5 are sequentially switched and energized, the convex portions 8a of the rotor 8 made of soft magnetic material are sequentially attracted to the stator 3 and rotated.

As described above, according to this embodiment, the rotor 8 is made of a soft magnetic material, and its peripheral wall is bent in an uneven manner in the circumferential direction, so that the convex portions 8a and the concave portions 8b are alternately arranged at the same circumference. By doing so, magnetic imbalance can be caused by creating a difference between the gap between the convex portion 8a and the magnetic pole of the stator 3 and the gap between the concave portion 8b and the magnetic pole of the stator 3. , it is possible to obtain the function of an electric motor without using a magnet, thereby reducing the number of manufacturing steps. Further, an optical sensor 10 is provided as an element for detecting the rotational position of the rotor 8, and the rotational position of the rotor 8 is detected by detecting concavities and convexities on the circumferential wall of the rotor 8 using the optical sensor 10. Concavities and convexities can be used to detect rotational position.

[Effect of idea]

As is clear from the above description, in the present invention, the rotor is formed by forming a thin plate made of soft magnetic material into a cup shape, and a stator is disposed inside the rotor, and a portion of the rotor that faces the stator is provided. The peripheral wall portion is bent in a concave and convex shape in the circumferential direction so that convex portions and concave portions are arranged alternately around the circumference, and a rotational position detection means for detecting the rotational position of the rotor is provided, so that manufacturing is easy. It is possible to provide a brushless motor that has excellent effects such as improving performance, reducing cost, having a rotor with low inertia, and increasing space efficiency.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, with FIG. 1 being a longitudinal sectional side view of the whole, and FIG. 2 being a bottom view of the rotor alone. In the figure, 3 is a stator, 8 is a rotor, 8a is a convex portion, 8b is a concave portion, and 10 is an optical sensor (rotational position detecting means).

Claims (1)

[Claims for Utility Model Registration] 1. In a rotor rotatably provided to a stator comprising an armature, the rotor is configured by forming a thin plate made of soft magnetic material into a cup shape,
The stator is disposed inside the rotor, and a peripheral wall portion of the rotor that faces the stator is bent in an uneven shape in the circumferential direction so that convex portions and concave portions are alternately arranged evenly around the circumference. A brushless motor characterized in that the brushless motor is further provided with rotational position detection means for detecting the rotational position of the rotor. 2. The brushless motor according to claim 1, wherein the rotational position detection means is an optical sensor that detects the convex portions and concave portions of the rotor.