JPH05260702A - Spark extinguishing device for motor - Google Patents

Abstract

PURPOSE:To diminish the occurrence of cracks due to thermal stress in soldering the electrodes of a varistor with the electrodes of the commutator of a motor, and to facilitate the assembly. CONSTITUTION:Since electrodes 14 are formed on the peripheral wall of the through hole 12 of a ceramic 11 for varistors, it is possible to insert the electrodes of the commutator of a motor into the through hole 12 and connect them to the electrodes 14. For this connection, soldering is performed by applying cream solder to the electrodes 14, inserting the electrodes of the commutator into the through hole 12, and performing heating and cooling after that. On this occasion, heat applied to the ceramic 11 is transmitted radially from the inner wall on to the peripheral side having a cross section wider than this wall. Accordingly, it is possible to prevent the temperature gradient from becoming steep since the heat is scattered as it is transmitted on the peripheral side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor spark erasing device in which a ring-shaped varistor is connected to a commutator of a motor for erasing sparks generated from the commutator in a small motor or the like.

[0002]

2. Description of the Related Art As shown in FIG. 7, a conventional general ring varistor used in a spark erasing device for a motor of this type is a porcelain composed of a ring-shaped sintered body made of strontium titanate as a semiconductor. 1 is used to form a plurality of electrodes 3 insulated from each other on the surface thereof. The porcelain 1 has a disk shape having a through hole 2, that is, a ring shape, and the electrode 13 is formed by being divided into a plurality of parts on the main surface surrounding the through hole 2. The spark erasing device of the motor is the electrode 3 of this ring-shaped varistor.
It is constructed by soldering the electrodes of the commutator of the motor. This eliminates the sparks generated by the brush.

[0003]

However, the above-described conventional spark erasing device for a motor has the following problems. First of all, when the electrode of the commutator of the motor is soldered to the electrode 3 on the main surface of the porcelain 1, the porcelain 1 is easily broken. This is because, when heated and melted solder is attached to the electrode 3, the heat held by the solder is transferred from the entire electrode 3 to the thickness direction of the porcelain 1 so that the temperature distribution in that direction temporarily becomes steep, It is considered that the porcelain 11 is damaged by the thermal stress generated at this time. Secondly, the soldering process is troublesome. That is, soldering the commutator electrode to the small varistor electrode 3 is not only a manual operation but also difficult to automate, and labor saving is difficult. An object of the present invention is to solve the above-mentioned problems in the conventional spark erasing device for a motor.

[0004]

That is, according to the present invention,
In order to achieve the above-mentioned object, a plurality of electrodes 13 provided on a plate-shaped varistor porcelain 11 having a through hole 12 in the center thereof.
In the spark erasing device for a motor connected to the commutator c of the motor, a plurality of electrodes 14 insulated from each other are formed on the peripheral surface of the through hole 12 of the varistor porcelain 11, and the electrode e of the commutator c is penetrated. Electrode 14 formed on the peripheral surface of hole 12
(EN) Provided is a spark erasing device for a motor, which is soldered only to the.

[0005]

In the spark erasing device for a motor according to the present invention,
Since the electrode 14 is formed on the peripheral wall of the through hole 12 of the varistor porcelain 11, the commutator c of the motor can be connected to the electrode 14 on this peripheral surface. In this case, the heat applied to the porcelain 11 due to the heating accompanying the soldering is radially transferred from the inner wall of the through hole 12 to the outer peripheral side having a wider cross-sectional area than that of the inner wall of the through hole 12, so that the heat is transferred to the outer peripheral side. Heat is dispersed,
A sharp temperature gradient is unlikely to occur. Also, soldering should be done through hole 1
The electrode e of the commutator c can be fitted in 2 and soldered directly there. For example, soldering can be performed by applying cream solder to the electrode 14 and fitting the electrode e of the commutator c into the through hole 12 and then heating and cooling.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. The varistor porcelain 11 used in the motor spark erasing device according to the present invention is, for example, as shown in FIG.
As shown in FIG. 2, it is a plate having a through hole 12 in the center, and the outer shape line on the outer peripheral side is usually circular. On the inner periphery of the through hole 12, grooves 1 are formed at equal intervals in the thickness direction of the porcelain 11.
5 is formed, and the electrode 1 made of a conductive film is formed between the grooves 15
4 are formed. In this embodiment, only electrodes are formed, and no electrodes are formed on the other surface of the porcelain 11.

The electrode 14 can be formed, for example, by applying a conductive paste to the peripheral surface of the through hole 12 by means of a roll transfer method or the like and baking it. That is, the rod-shaped roller (not shown) coated with the conductive paste is used as the through-hole 1
2 is inserted into the through hole 12, the conductive paste is applied to the inner circumference of the through hole 12, and then the conductive paste is baked. When forming the electrodes by this roll transfer, the grooves 15 separate the plurality of electrodes 14 from each other and form a preferable insulating state. Of course, the electrodes 14 can be formed by other means, and when the groove 15 is not formed, a resist or the like can be used to form an insulating state between the electrodes 14.

In order to construct a motor spark elimination device according to the present invention using this varistor, for example, as shown in FIG. 2, the electrode e of the commutator c of the motor is surrounded by the through hole 12 of the varistor porcelain 11. Solder to the electrode 14 formed on the surface. In this case, the electrode of the commutator c may be fitted into the through hole 12 of the porcelain 11 and the electrode 14 may be directly soldered to the electrode e on the commutator c side. For example, a solder paste is applied to the electrode 14 in advance, the commutator c is fitted into the through hole 12 in a predetermined positional relationship, and then the solder paste is heated and cooled to be soldered.

Next, another example of the varistor used in the spark eliminator for a motor of the present invention will be described with reference to FIGS. 3 and 4. These varistors are the electrodes 14 formed on the peripheral surface of the through hole 12. In addition, an electrode 13 continuous with these is formed on one main surface of the porcelain 11. in this case,
Solder for connecting to the commutator c of the motor is through hole 12
The electrode 13 is attached to the solder resist film 1 so that it adheres only to the electrode 14 formed on the peripheral surface of the
It is desirable to cover with 6. The solder resist film 16 does not necessarily have to cover almost the entire surface of the electrode 13 as shown in FIGS. 3 and 4, and is formed only on the edge portion of the through hole 12 as shown in FIGS. 5 and 6, for example. Even if the same effect is obtained. The mounting structure and the like of these motors to the commutator c are substantially the same as those in the above embodiment.

[0010]

As described above, according to the present invention,
When soldering the electrode 14 of the varistor and the electrode e of the commutator c of the motor, a steep temperature gradient is less likely to occur inside the porcelain 11, and cracking due to thermal stress can be reduced. Also,
The commutator c can also be connected to the electrode e by directly fitting the electrode e into the through hole 12 and soldering it. Therefore, the commutator c can be easily manufactured, and labor saving by automation can be easily realized.

[Brief description of drawings]

FIG. 1 is a perspective view of a ring-shaped varistor used in an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, showing a commutator of the motor by a chain double-dashed line.

FIG. 3 is a perspective view showing another example of the ring-shaped varistor used in the embodiment of the present invention.

FIG. 4 is a sectional view taken along line BB of FIG.

FIG. 5 is a perspective view showing still another example of the ring-shaped varistor used in the embodiment of the present invention.

FIG. 6 is a sectional view taken along line CC of FIG.

FIG. 7 is a perspective view of a ring-shaped varistor used in a conventional example.

[Explanation of symbols]

 11 Porcelain 12 Porcelain Through Hole 13 Varistor Electrode 14 Varistor Electrode 15 Porcelain Groove c Motor Commutator e Commutator Electrode

Claims (2)

[Reference number] 062091-01 [Claims] 1. A motor spark eliminator in which a plurality of electrodes 13 provided on a plate-shaped varistor porcelain 11 having a through hole 12 in the center thereof are connected to a commutator c of a motor. A plurality of electrodes 14 which are insulated from each other are formed on the peripheral surface of the hole 12, and the electrodes e of the commutator c are formed.
A spark erasing device for a motor, characterized in that the solder is soldered only to the electrode 14 formed on the peripheral surface of the through hole 12. 2. The spark erasing device for a motor according to claim 1, wherein the electrode e of the commutator c is fitted into the through hole 12 of the porcelain 11 and directly soldered to the electrode 14 there.