JPH1189146A - Armature of electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the cooling performance of an armature by dividing an armature core into a plurality of core blocks on a shaft and fixing the core blocks on the shaft so that there is a gap between them. SOLUTION: An armature core 12 is divided into a plurality of core blocks 12a and 12b on a shaft 9 and is fixed on the shaft 9 so that there is a gap 22 between the core blocks, thus increasing the surface area of the armature core 12 and an armature coil 13 owing to the gap 22 and increasing the contact area of cooling wind and hence improving the cooling efficiency of the armature core 12 and the armature coil 13 due to cooling wind.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an armature of a motor having high cooling efficiency.

[0002]

2. Description of the Related Art As shown in FIG. 3, an armature 1 of a conventional electric motor comprises a shaft 2, an armature core 3 pressed into the shaft 2, and an armature coil 4 wound around the armature core 3. A commutator 5 provided at the rear of the shaft 2;
A cooling fan 6 attached to the front of the shaft 2. When the armature 1 is rotated by energization of the commutator 5 and excitation of the field around the armature 1, the cooling fan 6 generates cooling air. The cooling air flows into the housing of the electric motor, cools the armature 1, the field, and the like, and then flows out of the housing.

[0003]

The conventional armature core 3
As shown in FIG. 3, there is a limit in enlarging the contact area with the cooling air since it is press-fitted as a lump on the shaft 2. Accordingly, an object of the present invention is to provide means for solving such a problem.

[0004]

In order to achieve the above object, the present invention provides an armature core (7) divided into a plurality of core blocks (12a, 12b) on a shaft (9),
The core blocks (12a, 12b) have a gap (2
An armature of an electric motor fixed on the shaft (9) so that 2) is empty was employed.

[0005]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, this armature 7
For example, it is used for a power tool such as a hammer drill and a concrete hammer.

This electric power tool has a shaft 9 serving as an output shaft in a housing 8. The shaft 9 is rotatably supported by the housing 8 via bearings 10 and 11. The shaft 9 is integral with the armature 7.

The armature 7 includes an armature core 12 fixed on the shaft 9, an armature coil 13 wound around the armature core 12, and a rectifier disposed behind the armature coil 13. And a child 14.

A field 15 and a brush 16 are arranged around the armature 7. The field 15 is a field coil 17
And a field core 18. The field core 18 faces the armature core 12. The brush 16 is in contact with the commutator 14. The field 15 and the brush 16 are in the housing 8
It is fixed to the inner surface of.

[0010] A cooling fan 19 is fixed on the shaft 9 in front of the armature coil 13. The cooling fan 19 is for cooling the armature 7 and the like, and an intake port 20 is formed in a rear wall of the housing 8 for flowing cooling air toward the armature 7 and the like. Has an exhaust port 21 formed therein.

When electric power is supplied to the field coil 17 to use the electric tool, the armature 7 rotates at a high speed together with the shaft 9 so that a drill, a hammer or the like (not shown) attached to the shaft 9 can be used as a concrete, rock or the like. Drilling, grinding, crushing, etc. Further, the cooling fan 19 also rotates integrally with the shaft 9, and takes in outside air into the housing 8 from the intake port 20 and discharges outside air from the exhaust port 21 to the outside of the housing 8. This outside air flows in the direction of arrow A in FIG. 1 and removes heat from the armature 7 and the like in the housing 8 to prevent overheating of the armature 7 and the like.

As described above, the cooling air from the cooling fan 19 cools the armature core 12 and the like through the narrow gap between the field core 17 and the armature core 12, so that the cooling efficiency is limited. Therefore, in the armature 7, a configuration as shown in FIG. 2 is employed to increase the cooling efficiency. That is, the armature core 12 is divided on the shaft 9 into a plurality of core blocks 12a and 12b,
2a and 12b are fixed on the shaft 9 such that a gap 22 is left therebetween. The space 22 increases the surface area of the armature core 12 and the armature coil 13 and increases the contact area of the cooling air, thereby increasing the cooling efficiency of the armature core 12 and the armature coil 13 by the cooling air.

It should be noted that the number of divisions of the armature core 12 is not limited to two, and the armature core 12 may be divided into more core blocks to form two or more gaps.

The armature 7 is formed by the following method. First, two core blocks 12a and 12b are prepared and pressed into the shaft 9. At this time, an appropriate gap 22 is provided between the core blocks 12a and 12b. For the armature core 12 fixed on the shaft 9, the shaft 9
The insulator is inserted into a number of slots extending parallel to the length direction, and the armature coil 13 is wound thereon. Next, in order to fix the armature coil 13 in the armature core 12, the wedge 23 is inserted from above the slot. Thereafter, a varnish is applied from above the armature coil 13 to form a protective film. The armature 7 thus obtained is incorporated in a power tool or the like as shown in FIG.

[0015]

According to the present invention, the armature core is divided into a plurality of core blocks on the shaft, and the core blocks are fixed on the shaft so as to leave a gap between them. The contact area between the armature, the armature core, the armature coil and the like can be increased, and the cooling performance of the armature can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a power tool using an armature according to the present invention.

FIG. 2 is a side view showing an armature.

FIG. 3 is a side view of a conventional armature.

[Explanation of symbols]

 7 armature core 9 shaft 12a, 12b core block 22 gap

Claims (1)

[Claims] 1. An armature for an electric motor, wherein an armature core is divided into a plurality of core blocks on a shaft, and the core blocks are fixed on the shaft so as to leave a gap therebetween.