JPH0416626Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a small motor. For example, if the motor is used for an electric shaver,
For convenience of portability and storage, it is necessary to make the motor thinner in the radial direction. However, when it comes to electric razors, it is said that it is not good for the rotating force to decrease when the load of cutting beards is applied, or for the current to increase in order to maintain a long battery life. Therefore, in order to achieve a low current value with a thin design and high torque, it is necessary to increase the effective flux due to the stator's permanent magnets as much as possible within the allowed body size, and increase the ampere turns on the rotor side to increase the torque constant M (gf It is necessary to make .cm/A) as large as possible. For the former, the specific method is to increase the effective cross-sectional area of the yoke, and for the latter, the concrete method is to increase the rotor core diameter as much as possible. On the other hand, if you use a coreless motor,
Although the above problems are eliminated, the cost is two to three times higher than that of a core type DC motor.

More specifically, if the stator case A is made into a flat box shape as shown in Figure 4 in order for the motor to fill the limited space, the rotor's iron core will inevitably be smaller than the yoke's inner dimension a. It is necessary to make the outer diameter b small (a>b), so the output,
This will result in inferior performance. As a solution to this problem, a notch D is formed in the flat plate portion C as shown in Fig. 5, and the outer circumference of the core of the rotor B can be inserted into the notch D. The diameter can be increased and the output can be improved.

However, in this case, the provision of the notch D reduces the effective magnetic cross-section of the case (yoke) A, increases magnetic resistance, and increases leakage of magnetic flux, so that the performance is not improved.

Therefore, the purpose of this invention is to provide a small motor with improved output and performance.

An embodiment of this invention is shown in FIGS. 1 to 3. That is, in this small motor, a case 1 that also serves as a yoke is formed into a flat cylindrical shape with a pair of opposing flat plate parts 2 and a pair of opposing arcuate side plates 3, with an end wall 4 at one end and an opening at the other end. 5. Further, an exposed window 6 is formed in the center of the flat plate portion 2, and cut-out pieces 7b and 7c are formed on the connecting piece 7 on the axial opening 5 side of the exposed window 6, so that the exposed window 6 is opened in a cutout shape. A cut and raised opening 7a is formed. A bearing stand 10 with an oil-impregnated bearing 9 is attached to the central hole 8 of the end wall 4 of the case 1, arcuate magnets 11 and 12 are press-fitted inside the arcuate side plate 3 as shown in FIG. It is positioned by a cut-and-raise stopper 13 at a corresponding position.

On the other hand, in the rotor 14, 15 is a shaft, 16 is a rotor core, 17 is a coil, 18 is a thrust regulating ring, 19 is a commutator, and 20 is a noise prevention element such as a varistor. The outer diameter of the core of this rotor 14
b' is approximately equal to the distance h between the outer surfaces of the flat plate portion of the case 1, and the axial length l of the exposed window 6 is slightly larger than the axial length a' of the iron core 16. By making the outer surface of the rotor core 16 and the outer surface of the flat plate part 2 substantially flush with each other in this way, the case 1 can be made as flat as possible, and the rotor core 16 can not protrude outward from the case 1. The rotating part does not touch the mounting surface of the motor.

The rotor 14 is inserted using the cut and raised opening 7a formed by the cut and raised pieces 7b and 7c, and when the shaft 15 is passed through the bearing 9, the outer peripheral part of the iron core 16 is located in the exposed window 6. Therefore, the cut and raised pieces 7b and 7c of the connecting piece 7 are brought down to their original positions to form part of the magnetic path. Further, a bearing stand 21 is fitted into the opening 5 of the case 1, and in this bearing stand 21, 22 is an oil-impregnated bearing, 23 is a terminal, 24 is a brush holding spring, and 25 is a carbon brush.

As described above, the small motor of this invention has a flat cylindrical shape having a rotor and an opening at one end into which the rotor is inserted. a magnetic case in which a connecting piece is formed on a flat plate part and a connecting piece that closes between the exposed window and the opening is formed by a cut-and-raised piece; a magnet disposed inside a side plate adjacent to the flat plate part of the case; It has the following effects.

In other words, the rotor can be inserted into the case by forming a cut-and-raised piece on the connecting piece, so the case can be made flat by exposing the rotor's core through the exposure window, and the connecting piece can be closed after the rotor is inserted. As a result, the connecting piece becomes almost the same as when it is not a cut and raised piece, and compared to the case where the connecting piece is cut and raised, the magnetic path of the case increases, the effective magnetic path cross section of the case becomes larger, and the magnetic resistance increases. Since it is small and leakage magnetic flux is reduced, effective magnetic flux can be increased. Therefore, a small motor with high torque can be obtained, which has the effect of improving both output and performance compared to the conventional motor.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional side view of an embodiment of this invention.
Fig. 2 is a sectional view taken along the - line, Fig. 3 is a perspective view showing the state in which the connecting piece of the case is cut up and cut down;
4 and 5 are perspective views of the conventional example. DESCRIPTION OF SYMBOLS 1... Case, 2... Flat plate part, 3... Arc side plate, 6... Exposed window, 7... Connecting piece, 7a... Cut-and-raised opening, 7b, 7c... Cut-and-raise piece, 11, 12... …
Magnet, 14...rotor.

Claims (1)

[Scope of utility model registration request] A rotor and an exposed window which has a flat cylindrical shape at one end having an opening into which the rotor is inserted and which exposes the outer circumference of the iron core of the rotor are formed in the flat plate part on the flat side, and the exposed window and the opening. A magnetic case with a connecting piece formed by a cut and raised piece,
and a magnet disposed inside a side plate adjacent to the flat plate portion of the case.