JPS6130440Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to a varistor for a micromotor that is suitable for eliminating spark discharge generated between a commutator and a brush of a small electric motor.

Generally, when an electric contact breaks a circuit, a sudden change in current occurs, and the accompanying self-induction induces a surge voltage, causing a spark discharge between the contacts.
This spark discharge not only accelerates the wear of contacts, commutators, and brushes, thereby shortening the life of the motor, but also causes various troubles to various equipment as a source of noise. For this reason, resistors and capacitors are connected between the commutators, and SiC varistors and varistors made by sintering oxide semiconductors into ring shapes are used, and these are installed in various ways.

By the way, there are two types of commutators: cylindrical and flat commutators, and there is a motor in which a varistor (hereinafter referred to as a ring varistor) made of a ring-shaped sintered oxide semiconductor is applied to the flat commutator. In other words, thin metal plates divided into three parts are bonded to both sides of an insulating substrate, with the front and back sides connected, respectively, with one serving as a commutator and the other serving as an electrode for a varistor. A ring varistor is connected to the varistor electrode and bonded to the substrate. However, this method requires a commutator substrate and a varistor, and must be bonded to the varistor substrate. Furthermore, the ring varistor has a problem with its nonlinear coefficient, which is one of the performances required of a varistor.
In other words, when applied to small electric motors, it is necessary to suppress the spark voltage, absorb electrical noise, and reduce wear on the commutator and brushes, and on the other hand, it is necessary to have a cleaning effect using the commutator sparks, so a moderate value has a nonlinear coefficient. Barista is best.

This invention allows the nonlinear coefficient to be freely changed along with the varistor voltage, and has superior performance compared to conventional ring varistors.Furthermore, since the varistor is obtained by printing and firing on an alumina substrate, the substrate The object of the present invention is to provide a varistor for a micromotor, which can have a commutator connected to the varistor on the opposite side of the varistor, that is, can integrate the commutator and the varistor.

That is, in the past, an insulating substrate with a commutator and a varistor were required, and this varistor had to be attached to the insulating substrate so as to connect to the commutator. In this case, the varistor had to be attached to the varistor electrodes with a conductive adhesive, and to the insulating substrate with an insulating adhesive. In contrast, the varistor of this invention is not only superior in performance, but also has the ability to provide a commutator on the varistor itself, eliminating the need for extra parts and the need for adhesives. Therefore, not only is it advantageous in terms of cost and labor, but it is also a more reliable varistor with no defects due to adhesion.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. First, in FIG. 1, a varistor element and a silver electrode are printed and fired on an alumina substrate 1 having a terminal 5 that can be wound with a coil, thereby obtaining a varistor 2 and an electrode 3. Incidentally, on the opposite surface of the alumina substrate 1, electrodes are provided divided into three as shown in FIG. 2, and these are used as commutators 4. Furthermore, in order to obtain the varistor 2, as shown in FIG. 3, a lower electrode 6 is printed and fired on the alumina substrate 1, then a varistor element 7 is printed and fired, and finally an upper electrode 8 is printed and fired. . Note that after printing and firing the lower electrode 6, a commutator 4 is printed on the opposite side of the alumina substrate 1, and the electrode 3 on the varistor side and the end face of the alumina substrate 1 are connected with silver paste and then fired to form the commutator 4. get.

As described above, according to the present invention, compared to the conventional structure in which a commutator and a varistor are bonded together, not only the performance of the varistor itself is superior, but also the commutator can be provided on the varistor itself. This method is advantageous in terms of cost and man-hours, and because it does not require adhesion, there are no defects caused by adhesion, and a more reliable varistor can be provided.

[Brief explanation of drawings]

Fig. 1 is a plan view of the front surface showing one of the varistors for a micromotor of the present invention, Fig. 2 is a plan view of the back side of the same, and Fig. 3 is a sectional view showing the structure of the varistor constituting the varistor for the micromotor. be. 1...Alumina substrate, 2...Varistor, 3...
Electrode, 4... Commutator, 5... Terminal for coil winding, 6... Lower electrode, 7... Varistor element, 8...
...Top electrode.

Claims (1)

[Scope of utility model registration request] A varistor electrode and a varistor element are printed and fired on one side of an alumina substrate in a shape that can be wrapped around a coil, and an electrode is connected to the varistor on the opposite side of the alumina substrate to the varistor and divided into three to form a commutator. Varistor for micro motor.