JPH1028353A - Armature assembly structure for motor in power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-quality rotating shaft, without performing any strict dimensional management and to secure the strength of the shaft by constituting the shaft of a stepped shaft, composed of a large-diameter section and a small-diameter section and forming a gear in the large-diameter section and, at the same time, providing a thrust bearing at the boundary between the large- and small-diameter sections. SOLUTION: An armature assembly is constituted by using a stepped-rotating shaft 2, composed of a large-diameter section 2A having an outside diameter D1 and a small-diameter section 2B, having another outside diameter D2 (D1>D2). On the shaft 2, in addition, a female screw 2C is formed in the large-diameter section 2A, so that an appropriate transmission gear can be meshed with the screw 2C. Moreover, a washer 3 which becomes a thrust bearing is slid on the small-diameter section 2B, until the washer 3 comes into contact with the step section D of the shaft 2. Therefore, no strict dimensional management is required for press-fitting the gear, and at the same time, a prescribed shaft strength is obtained, even when the overall size of the armature assembly is not enlarged. In addition, the cost of the armature assembly can be reduced, because no after-treatment, etc., is required after performing the press-fitting work.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power tool motor, and more particularly to an armature assembly structure of a power tool motor.

[0002]

2. Description of the Related Art Various types of motors are used as driving means in various types of equipment including electric tools. For example, as shown in FIG. As described above, the core 1 constituting the rotor 100
And a winding (not shown) wound around the core 101 to form a magnetic pole.

[0003] The rotor 100 has a core 101.
A rotating shaft 102 that rotates integrally with the rotating shaft 102 and a commutator 103 fixed to the rotating shaft 102 are provided. The core 101, the winding, the rotating shaft 102, the commutator 103, and the like are integrated to form an armature 104. Make up.

The armature 104 has a rotating shaft 10
A gear 105 is provided on the rotating shaft 102 in order to transmit a rotational force from 2 and drive a required portion to rotate. In FIG. 4, reference numeral 106 denotes a bearing that rotatably supports the rotating shaft 102.

[0005]

By the way, there is a demand for a power tool equipped with such a motor that is lightweight and compact and is convenient to use. Therefore, the diameter of the rotating shaft provided on the armature has been reduced to meet such demands.However, because the thin rotating shaft is fragile and easily broken, the thread is directly cut into the rotating shaft. The gear which is usually formed separately is press-fitted.

When the gear is mounted by press fitting, it is necessary to secure a press fitting tolerance to some extent.
However, prior to this press-fitting operation, heat treatment such as surface hardening is performed to increase the strength as a gear, so that the inner diameter dimension is slightly changed due to thermal expansion, making it difficult to secure required tolerances. .

In such a case, it is necessary to perform a finishing process after the heat treatment in order to secure a tolerance.
The cost is increased accordingly. In addition, to check whether the gear is properly press-fitted after press-fitting, it is impossible to understand unless the product is destructively inspected, so strict quality control such as thorough quality control up to the previous process is required. I have.

[0008] In view of the above circumstances, the present invention can provide a good-quality product without requiring strict dimensional control (including press-fitting work) and without increasing the size of the armature. An object of the present invention is to provide an armature assembly structure of a motor for a power tool, which can secure a required shaft strength and suppress a rise in cost.

[0009]

That is, according to the first aspect of the present invention, a winding constituting a rotor, a core around which the winding is wound, and a rotating shaft which rotates integrally with the core are provided. In the armature assembly of a motor for a power tool having a stepped shaft, the rotating shaft comprises a stepped shaft composed of two kinds of a large diameter portion and a small diameter portion having partially different outer diameters, and the large diameter portion has an external thread. And a thrust bearing is provided at the boundary between the large-diameter portion and the small-diameter portion to abut against a bearing supporting the large-diameter portion of the rotary shaft.

[0010]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an armature assembly structure of a power tool motor according to the present invention. As shown in FIG. 2, the armature assembly 1 has a rotating shaft 2 formed of a large diameter portion 2A and a small diameter portion 2B. The one with a step is used.

The rotary shaft 2 has a large-diameter portion 2A having an outer diameter D1 formed with a male screw 2C.
A suitable transmission gear (not shown) meshes with the gear. A washer 3 serving as a thrust bearing is inserted into the small-diameter portion 2B having an outer diameter D2 (D1> D2) so as to abut the step 2D.

The rotary shaft 2 is rotatably supported by bearings 106 and 106 'at the small diameter portion 2B and the large diameter portion 2A, respectively. The outer diameter of the small diameter portion 2B is the same as the conventional one. The size of the large-diameter portion 2A only needs to have a certain strength and be large enough to cut a screw.

The washer 3 functions as a thrust bearing for the large-diameter portion 2A side step portion 2D and at the same time abuts against the bearing 106 '. In this embodiment, a flanged cylindrical body formed separately is provided. However, instead of this, as shown in FIG. 3, the large diameter portion 2A is formed so that the step portion side protrudes greatly (that is, the large diameter portion is formed by partially cutting the original diameter). A) A flange 2E integral with the rotating shaft 2 may be provided.

Therefore, according to this embodiment, a gear is formed by cutting the external thread 2C in the large diameter portion 2A, and a washer 3 serving as a thrust bearing is provided at the boundary between the large diameter portion and the small diameter portion. Large diameter portion 2A of bearing 106 'supporting 2A
Since the abutment is performed, a reliable bearing operation can be realized.

[0015]

As described above, according to the present invention, an electric machine having a winding constituting a rotating rotor, a core around which the winding is wound, and a rotating shaft which rotates integrally with the core. In the subassembly, the rotating shaft is composed of a stepped shaft composed of two types, a large diameter portion and a small diameter portion having different outer diameters, and a gear is provided by cutting a male screw in the large diameter portion. In other words, since the gear is formed by directly processing the large-diameter portion of the rotary shaft, not only does it not require strict dimensional control required for press-fitting the gear, but also does not increase the size of the entire armature assembly. In both cases, a predetermined axial strength is obtained. Further, according to the present invention, since there is no need to perform the press-fitting operation, post-processing and quality control accompanying the press-in operation are not required, and the cost can be reduced accordingly.

Further, according to the present invention, the cost of parts can be reduced, quality control can be facilitated by the reduced number of parts, and the assembling process can be facilitated.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an armature assembly structure according to the present invention.

FIG. 2 is a schematic perspective view showing a rotating shaft used for an armature assembly structure.

FIG. 3 is a schematic perspective view showing a modification of the rotating shaft.

FIG. 4 is a schematic view showing a conventional armature assembly structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Armature assembly 2 Rotating shaft 2A Large diameter part 2B Small diameter part 2C Male screw 2D Step part 2E Flange 3 Washer 106 'Bearing

Claims (1)

[Claims] An armature assembly for a power tool motor having a winding constituting a rotor, a core on which the winding is wound, and a rotating shaft that rotates integrally with the core, wherein the rotating shaft is A large-diameter portion and a small-diameter portion having partially different outer diameters are configured with a stepped shaft composed of two types, a gear is formed by cutting a male screw in the large-diameter portion, and the large-diameter portion and the small-diameter portion are formed. A thrust bearing for abutting a bearing supporting a large-diameter portion of the rotary shaft at a boundary portion between the armature assembly and the armature assembly structure of the motor for a power tool.