JPH06269148A - Commutator - Google Patents

Abstract

PURPOSE:To ensure the connection between a plurality of conductive ceramics, which are bonded to the outer surface of insulating ceramic and the end of an armature coil in a commutator of a small size commutator motor used in motor-driven tools, etc. CONSTITUTION:Silver solder, into which active metal is added, is applied on the specified positions of the outer surfaces in the vicinities of the edges of a plurality of conductive ceramics 1 on the side of the coil of an armature. The ceramics are bonded to the outer surface of insulating ceramic 2. Then, heating is performed, and conductive metal parts 3 are formed. The conductive ceramics 1 and the end of the armature coil are connected through the conductive metal parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a commutator made of a conductive ceramic and an insulating ceramic and improved in connection with an armature coil.

[0002]

2. Description of the Related Art Japanese Patent Application No. 03-55685 proposes a ceramic commutator in which a plurality of conductive ceramics are joined to the outer circumference of a cylindrical insulating ceramic at a predetermined pitch along the circumferential direction. It is well known that a ceramic commutator has a problem that the armature coil terminal (hereinafter referred to as coil terminal) and the conductive ceramic cannot be connected as they are,
In order to eliminate such connection difficulty, Japanese Patent Laid-Open No. 3-1715
As described in Japanese Patent No. 78, it is possible to form a conductive metal part by forming a good conductive chromium nitride on a conductive ceramic by a sintering method and connect a coil end to the conductive metal part. Is proposed by the issue.

[0003]

However, the above-mentioned Japanese Unexamined Patent Application Publication No.
In No. 0-5083, as described above, the conductive metal portion is formed of chromium nitride, but the chromium nitride layer eventually changes into a hard and brittle film of the form CrN. Chromium nitride layer in the form of the CrN has a thermal expansion coefficient, 2.3 × ^10-6 and the general coefficient of thermal expansion of the ceramic (7 to 10) × small relative ^10-6. Therefore, when the chromium nitride layer is formed on the surface of the ceramic and then the temperature is raised to a temperature at which silver brazing can be performed by Ni plating or the like, the elongation of the base metal ceramic is larger than the elongation of the chromium nitride layer. There is a risk of peeling off easily, and a strong bond with the coil end cannot be expected. When the coil terminals are connected through the chromium nitride layer by means such as fusing, the melting point of the chromium nitride layer is about 150.
It is as high as 0 ℃, and the pressure at the fusing tip (about 30K
There is a problem that cracks such as cracks due to g / mm ² ) may occur. An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide at low cost a commutator capable of reliably connecting coil ends.

[0004]

In order to achieve the above-mentioned object, the present invention is to form a conductive metal portion at a predetermined position on the outer periphery of a conductive ceramic by means such as metalizing or sputtering, and to form a coil terminal on the conductive metal portion. Is to be connected. Further, when the conductive metal portion is formed by applying silver braze to which an active metal is added and then heating, it is effective because cracks and the like are less likely to occur.
Further, if the conductive metal portion is formed by using the bonding temperature when the conductive ceramic is bonded to the insulating ceramic, the number of manufacturing steps is reduced and the commutator can be provided at a lower cost.

[0005]

According to the commutator having the above-described structure, the coil terminal can be securely connected, and the conductive metal portion is prevented from peeling or cracking due to the temperature and pressure at the time of connecting the coil terminal. Can be expected.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. The conductive ceramic 1 is joined to the outer circumference of the insulating ceramic 2, and the conductive metal portion 3 is formed at a predetermined position on the outer circumference of the conductive ceramic 1 in the vicinity of an end face of the conductive ceramic 1 on the armature coil side (not shown).
A coil terminal 4 is connected to the conductive metal portion 3. The conductive ceramic 1 is joined to the insulating ceramic 2 to form the conductive metal portion 3 and then undercut as shown in FIGS. 1 and 2 to be divided into a plurality of conductive ceramic segments.

The conductive ceramic 1 is made of TiN or Ti.
It is made of materials such as C and ZrB ₂ , and an example of dimensions is
The outer diameter is 23 mm, the inner diameter is 19 mm, and the length is 14 mm. The insulating ceramic 2 is made of, for example, a material composed of 96% by weight of alumina, and its dimensions are an outer diameter of 18.8 mm and an inner diameter of 11 mm.
mm and length 14 mm. The insulating ceramic 2 and the conductive ceramic 1 are joined to each other by applying a T
After applying silver braze containing active metals such as i and Mo or silver braze containing palladium, the degree of vacuum is 5 × 10 to ⁵ torr.
It is carried out by heating at 830 ° C. for 5 minutes in the following treatment tank.

The conductive metal portion 3 is formed by applying silver braze containing the active metal to the outer periphery of the conductive ceramic 1 up to 10 mm from the end face of the conductive ceramic 1 on the armature coil side.
Is formed by utilizing the heating temperature when joining the insulating ceramic 2 to the insulating ceramic 2. The heating temperature needs to be higher than the melting temperature of the silver brazing material, and is preferably 50 ° C. higher than the melting temperature.
Higher is good. The amount of the active metal is 0.5 to 0.5 for Ti.
10% by weight is suitable. If it is less than 0.5% by weight, the wettability with the ceramic will be poor, and if it exceeds 10% by weight, the specific resistance of the silver solder itself will be increased due to the influence of the active metal.
Therefore, the amount within the above range is desirable. Further, considering the connection with the coil terminal 4, the thickness of the conductive metal portion 3 is preferably 30 μm or more from the viewpoint of connection strength.

For example, the wire diameter is 0.5 mm with the conductive metal portion 3.
The connection with the coil terminal 4 is performed by means of conventionally known means such as fusing, resistance welding, TIG welding, electron beam welding, and laser welding.

As is well known, the silver solder is a soft metal and has a thermal expansion coefficient of about 18 × 10 to ⁶ which is larger than that of ceramics and a melting point as low as 780 ° C. Therefore, when the coil terminal 4 is connected. There is no risk of the conductive metal portion peeling off or cracking due to the temperature and pressure.

As a result of measuring the connection load and the connection resistance value of the coil terminal 4 of the commutator manufactured as described above, a connection load of 7 kg or more and a connection resistance of 0.4 mΩ or less can be obtained. It was almost equal to or higher than the commutator.

When sputtering or vacuum deposition is used instead of the metallizing process for forming the conductive metal portion 3, the conductive metal portion 3 has a thickness of about 50 μm and the coil end 4 is formed.
Was connected in the same manner as above, and the connection load and connection resistance values were measured. As a result, a connection load of 5 kg or more and a connection resistance of 0.6 mΩ or less were obtained. The result was obtained.

In the above embodiment, the conductive metal portion 3 is formed on the outer periphery of the conductive ceramic 1. However, a recess such as a groove or a wax reservoir is provided on the outer periphery of the conductive ceramic 1, and the conductive metal portion 3 is formed in the groove or the recess. If formed, the connection with the coil terminal 4 becomes stronger.

[0014]

As described above, according to the present invention, the coil terminals can be reliably connected by connecting the coil terminals through the conductive metal portion formed by metalizing or sputtering. In addition, by forming the conductive metal part with silver braze to which an active metal is added, there is no risk of the conductive metal part peeling or cracking due to temperature and pressure when connecting the coil end, and to provide a highly reliable commutator. Is possible. Further, if the conductive metal portion is formed by utilizing the temperature at which the insulating ceramic and the conductive ceramic are joined together, the manufacturing process can be reduced and an even cheaper commutator can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a commutator of the present invention.

FIG. 2 is a side view showing an embodiment of a commutator of the present invention to which coil terminals are connected.

[Explanation of symbols]

Reference numeral 1 is a conductive ceramic, 2 is an insulating ceramic, 3 is a conductive metal portion, and 4 is an armature coil terminal.

Claims (3)

[Claims] 1. A commutator in which a plurality of conductive ceramics are joined to the outer circumference of a cylindrical insulating ceramic at a predetermined pitch along the circumferential direction, and the conductive metal is metalized or sputtered at a predetermined position on the outer circumference of the conductive ceramic. A commutator, wherein a commutator is formed and is connected to the end of the armature coil through the conductive metal part. 2. The commutator according to claim 1, wherein the conductive metal portion is formed by applying silver braze containing an active metal to a predetermined position on the outer periphery of the conductive ceramic and then heating the silver braze. . 3. The commutator according to claim 1, wherein the conductive metal portion is formed at the same time when the conductive ceramic and the insulating ceramic are joined.