JPH05284679A - Miniature dc motor - Google Patents

Abstract

PURPOSE:To obtain a miniature DC motor capable of thinning while ensuring a high torque characteristic. CONSTITUTION:A bent section 3a is formed on the lower end of a laminated rotor core 2 in the direction of magnetic thrust, an auxiliary rotor core 3 is laminated thereon, the magnetic center of the laminated rotor core 2 is located upward of the magnetic center of a field magnet 1 to oppose it to the field magnet 1, magnetic flux is induced in the laminated rotor core 2 by the auxiliary rotor core 3, so that the laminated rotor core 2 is not additionally laminated. Torque can be increased without lengthening the length of the field magnet 1 and, at the same time, an appropriate magnetic thrust can be also obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated rotor for a small DC motor.

[0002]

2. Description of the Related Art Conventionally, in a small DC motor with a brush, as shown in FIG. 3, in order to give a magnetic thrust to the laminated rotor core 1, the magnetic centers of the magnet 1 and the laminated rotor core 2 are generally displaced from each other. Met.

By the way, in recent years, in order to improve the structural efficiency of various precision instruments and audio products, it has been demanded to supply a thin and compact DC motor having high torque characteristics.

[0004]

In order to improve the torque characteristics of such a small DC motor having the conventional structure, the stacking thickness of the laminated rotor core 2 and the length of the magnet 1 must be increased. Therefore, there is a problem that the thickness of the motor becomes thicker.

The present invention solves the above problems, and an object of the present invention is to provide a small DC motor which can be made thin while obtaining high torque characteristics.

[0006]

In order to achieve the above object, the present invention has a slot having the same shape and the same outer diameter as the rotor core, and a bent portion extending in the thrust direction is formed on the outer peripheral portion. The auxiliary rotor core is laminated on the rotor core as a lowermost plate with the bent portion facing downward to form a laminated rotor core, and the magnetic center of the laminated rotor core is positioned above the magnetic center of the field magnet. The laminated rotor core and the field magnet are opposed to each other.

[0007]

According to the present invention, the bent portion of the auxiliary rotor core laminated on the laminated rotor core opposes the field magnet to guide the magnetic flux to the laminated rotor core. In addition, the torque characteristics are improved without increasing the size of the field magnet, and the magnetic thrust is also obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In the figure, reference numeral 1 is a field magnet, which is arranged on the inner surface of the motor case 4. Reference numeral 2 denotes a laminated rotor core, and an auxiliary rotor core 3 is laminated on the lower end surface as a lowermost plate. The auxiliary rotor core 3 has a slot having the same shape as the rotor core and the same outer diameter dimension, and a bent portion 3a extending in the thrust direction is formed on the outer peripheral portion thereof. The laminated rotor core 2 laminated in this way is arranged so as to face the field magnet 1 so that the magnetic center of the laminated rotor core 2 is located above the magnetic center of the field magnet 1, and the rotating shaft 5 thereof It is pivotally supported by the bearing 6 of the motor case 4 and the bearing 6 of the bracket 7. In addition, 8 is a commutator, 9 is a brush, and 10 is a winding of the laminated rotor core 2.

According to the above structure, since the bent portion 3a of the auxiliary rotor core 3 faces the field magnet 1, it is possible to induce a magnetic flux into the laminated rotor core 2 and increase the rotational torque of the laminated rotor core 2. Moreover, since the bent portion 3a is opposed to the projecting portion of the field magnet 1 projecting more than the lower end of the laminated rotor core 2 in order to obtain the magnetic thrust, the field magnet 1 can be lengthened or the laminated rotor core 2 can be formed.
Further, the rotational torque can be increased by utilizing the space below the laminated rotor core 2 without increasing the stacking thickness.

According to the experiment, as shown in FIG.
% Improvement in the rotational torque characteristic was obtained.

Also, a proper magnetic thrust was obtained.

[0013]

As is apparent from the above description of the embodiments, according to the present invention, the bent portion of the auxiliary rotor core laminated on the laminated rotor core faces the field magnet to guide the magnetic flux to the laminated rotor core. Therefore, the rotational torque characteristic can be improved without increasing the number of laminated rotor cores and without increasing the size of the field magnet, and the magnetic thrust can be properly obtained.

As described above, according to the present invention, it is possible to provide a small DC motor which can be made thin while obtaining high torque characteristics.

[Brief description of drawings]

FIG. 1A is a side sectional view of a small DC motor according to an embodiment of the present invention, and FIG. 1B is a side sectional view of the same laminated rotor core.

[Fig. 2] Rotational torque characteristic diagram of the same small DC motor

FIG. 3 is a side sectional view of a conventional small DC motor.

[Explanation of symbols]

 1 field magnet 2 laminated rotor core 3 auxiliary rotor core 3a bent portion

Claims (1)

[Claims] 1. An auxiliary rotor core having a slot having the same shape and the same outer diameter as the rotor core, and having a bent portion extending in the thrust direction formed on the outer peripheral portion thereof, with the bent portion facing downwardly. A small direct current formed by laminating the laminated rotor core as a plate to form a laminated rotor core, and positioning the magnetic center of the laminated rotor core above the magnetic center of the field magnet so that the laminated rotor core and the field magnet face each other. motor.