JPH0524739B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a discharge protection device for electrical equipment.

[Background of the invention]

The prior art will be explained using a rotating electrical machine for a vehicle as an example. FIG. 2 shows a conventional example of an arcing stud type discharge protection device employed in a rotating electrical machine for a vehicle, etc. As shown in the figure, the commutator piece 1 is connected to the V
It is tightened with a nut 5 together with a shaped box 3 and a V-ring 4. The brush 8 is held down by the brush holder frame 6 and the brush presser spring 7, and the brush holder 6 is attached to the embrar 11 by an insulating rod 9 and a fitting 10 while maintaining insulation. An arcing stud 12 is provided at a position on the circumference of the embrar 11, and a discharge tip 13 is provided on the brush holder frame 6 so as to face the stud 12.

In the discharge protection device for electrical equipment configured as described above, when an overcurrent flows in the rotating machine and excessive rectifying sparks are generated, a discharge protection device is installed between the two electrodes 12 and 13 using the discharge chip 13 and the arcing stud 12 as electrodes. Generates concentrated discharge to minimize erosion of the brush holder body and commutator parts due to discharge.

Further, as shown in FIG. 3, the arcing ring type discharge protection device has an arcing ring 14 instead of the arcing stud, and the arcing ring 14 and the discharge chip 13 provided on the brush holder frame 6 are connected to each other. The electrodes are designed to generate concentrated discharge between these two electrodes 14 and 13.

By the way, in such discharge protection devices, iron bolts, etc. are often used for the arcing stud and discharge chip, so once an accident such as a flashover occurs, the heat generated by the discharge arc generated between the arcing stud and the discharge chip will cause damage. The bolt melts and becomes red-hot particles that scatter into the brush chamber. As a result, there was a high incidence of secondary damage that damaged the brush holder, brushes, commutator surface, armature windings, brush crossover wires, etc. Regarding this type of discharge protection device, Japanese Patent Application Laid-Open No. 52-132306 and Japanese Utility Model Application No. 52-110304 disclose a structure that facilitates the replacement of the arcing stud.

[Purpose of the invention]

The present invention has been made in view of the above points,
The object of the present invention is to provide a discharge protection device for electrical equipment that can prevent secondary damage to the electrical equipment.

[Summary of the invention]

That is, the present invention provides a discharge protection device for electrical equipment having an arcing stud and a discharge chip disposed opposite to the arcing stud with an appropriate discharge distance, in which at least one of the arcing stud and the discharge chip is made of conductive ceramic. A discharge protection device for electrical equipment, which has a first feature of: an arcing stud and a discharge chip disposed opposite the arcing stud with a suitable discharge distance therebetween;
A second feature is that at least one of the arcing stud and the discharge chip is made of conductive ceramics and a metal with good thermal conductivity. At least one of the particles becomes fine particles when flashover occurs, and becomes evaporated and worn away.

[Embodiments of the Invention] The present invention will be described below based on illustrated embodiments. FIG. 1 shows an embodiment of the invention. Note that parts that are the same as those in the conventional system are given the same reference numerals, and therefore their explanations will be omitted. In this embodiment, the arcing stud 15 is made of conductive ceramics. That is, the ceramic stud 15 is made of conductive ceramic. By doing so, the arcing stud is constructed of the ceramic stud 15 made of conductive ceramics, and it is possible to obtain a discharge protection device for electrical equipment that can prevent secondary damage to the electrical equipment.

The ceramic stud 15 may be attached by tightening the end of the ceramic stud 15, which has been formed into a screw shape in advance, into a screw hole provided in the embrar 11, by fixing it with a nut, or by fixing it with a conductive adhesive. good. By doing this, when a flashover accident occurs, an excessive current flows to the ceramic stud 15 due to a discharge arc, and the ceramic stud 15 is melted due to heat.
When the ceramics constituting the ceramic stud 15 are melted at high temperatures, they become very fine particles and are worn away as they evaporate. Therefore, like a conventional bolt, the molten particles fly around the brush chamber,
No secondary damage to other components occurs. Furthermore, since the ceramic stud 15 suffers less wear due to heat than conventional iron arcing studs, there is no need to replace the ceramic stud 15 at every flashover as in the conventional case. Therefore, since it is possible to restart the operation only by inspection, the life of the electrical equipment can be extended and the inspection time can be reduced.

Another embodiment of the invention is shown in FIG. In this embodiment, the discharge chip 16 disposed opposite the arcing ring 14 is made of conductive ceramics. That is, it is constructed of a discharge ceramic chip 16 made of conductive ceramic. The discharge ceramic chip 16 may be attached to the brush holder frame 6 by cutting a thread at one end of the discharge ceramic chip 16 and screwing it into a screw hole previously provided in the brush holder frame 6. It may be fixed with adhesive. In this case as well, when a flashover occurs, the discharge ceramic chip 16 is worn out in the form of fine particles, and the same effect as in the above case can be achieved.

FIG. 5 shows yet another embodiment of the invention. In this embodiment, the ceramic stud 15a, which is an arcing stud, is made of conductive ceramics having two different resistances. That is, the inner side is made of low-resistance ceramics 17 and the outer side is made of high-resistance ceramics 18, and has a cylindrical shape. The low resistance ceramic 17 was made to protrude from the high resistance ceramic 18. By doing this, the tip end corner of the ceramic stud 15a is multi-staged, and the local concentration of the electric field is alleviated, thereby reducing the flashover occurrence rate.
Note that the shape of the ceramic stud 15a is not limited to a cylindrical shape, but may be a square prism, an elliptical prism, or the like.

FIG. 6 shows yet another embodiment of the invention. In this embodiment, the ceramic stud 15b
have a double cylindrical structure with the same height, the inside is made of low resistance ceramics 17 and the outside is made of high resistance ceramics 18.
It was composed of By arranging the low-resistance ceramic 17 in the center in this way, it is possible to concentrate the current in the center of the ceramic stud 15b (normally, in a cylindrical shape, the current flows densely in the center). ), the arc itself can be squeezed during flashover, and secondary damage to parts other than the ceramic stud 15b and discharge chip 13 due to spread of the arc can be prevented.

FIG. 7 shows yet another embodiment of the invention. In this example, the ceramic stud 15c
has a double cylindrical structure, with the inner side made of high resistance ceramics 18 and the outside made of low resistance ceramics 17. By doing this, the melting and scattering phenomena of the ceramic studs 15c and discharge chips 13 are directly caused by the heat generated by the arcing current. Due to the I ² R loss, the inner high-resistance ceramic 18 is first melted down. In this case, the outer low-resistance ceramics 17 have not melted yet, so they serve as a guard fence for the arc in the center, and can prevent the high-resistance ceramics 18 in the center from scattering.

FIG. 8 shows yet another embodiment of the invention. In this example, the ceramic stud 15d
A high resistance ceramic 1 is placed on the discharge chip 13 side.
8. Low-resistance ceramics 17 were disposed on the embrar 11 side and were stacked in the axial direction. By doing this, the high-resistance ceramics 18 are first melted and then the low-resistance ceramics 17 are melted and damaged due to resistance heat generation, making it possible to disperse the melting loss of the ceramic studs 15d over time. , it is possible to further reduce secondary damage.

FIG. 9 shows yet another embodiment of the invention. In this embodiment, the ceramic stud 15e
is constructed by stacking low-resistance ceramics 17 and high-resistance ceramics 18 alternately in the axial direction. In the case of this embodiment, stud melting damage due to arc can be separated more than in the case described above, and secondary damage can be reduced more than in the case described above.

FIG. 10 shows yet another embodiment of the invention. In this example, ceramic studs 15
f is a stud 19 made of conductive ceramics.
A metal 20 having good thermal conductivity made of copper or the like is pressed into contact with the metal 20. This ceramic stud 15f
Although the metal 20 is constructed in the form of a bolt and is tightened with a nut, it goes without saying that the metal 20 may be attached to the Embler 11 using a conductive adhesive. In the case of this embodiment, the heat-uniforming property of the metal 20 with good thermal conductivity alleviates the local heating of the stud 19 due to arc discharge during flashover, which prevents cracking of the stud 19 made of ceramic. can be prevented.

FIG. 11 shows yet another embodiment of the invention. In this example, ceramic studs 15
g is a stud 19 made of conductive ceramics.
and a metal 20 having good thermal conductivity, and the joint area 21 between the stud 19 and the metal 20 is stepped so that the joint area between the stud 19 and the metal 20 is different. That is, the cross-sectional area of the metal 20 is made smaller than the axial cross-sectional area of the stud 19, so that the joint portion 21 is stepped. In the case of this example, the concentration of thermal stress can be reduced during pressure welding of the stud 19 and the metal 20, so defects such as cracking of the stud 19 during pressure welding are prevented, and a good ceramic stud 15g can be obtained. be able to.

Furthermore, in this embodiment, the case where the present invention is mainly applied to an arcing stud has been described, but the same can be applied to an arcing ring.

Further, although this embodiment has been described with reference to the case where it is applied to a rotating electric machine for a vehicle, it goes without saying that the present invention is not limited to this and can also be applied to a DC machine or the like.

〔Effect of the invention〕

As described above, the present invention is such that at least one of the arcing stud and the discharge tip is made of conductive ceramics, so that the arcing stud and the discharge tip become fine particles and wear out, thereby preventing secondary damage to electrical equipment. A discharge protection device for electrical equipment that can prevent electrical discharge can be obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of the area around the commutator of an embodiment of the discharge protection device for electrical equipment of the present invention, FIG. 2 is a longitudinal sectional side view of the area around the commutator of a conventional electrical equipment discharge protection device, and FIG. 4 is a longitudinal sectional side view of the area around the commutator of another example of the conventional discharge protection device for electrical equipment, and FIG. 5 to 11 are longitudinal sectional side views of the arcing stud and its surroundings showing different embodiments of the discharge protection device for electrical equipment of the present invention. 1...Commutator piece, 6...Brush retainer frame, 8...
... Brush, 11 ... Embra, 13 ... Discharge chip, 14 ... Arcing ring, 15, 15a,
15b, 15c, 15d, 15e, 15f, 15
g...Ceramic stud (arching stud), 16...Discharge ceramic chip, 17...
...Low resistance ceramics, 18...High resistance ceramics, 19... Studs made of conductive ceramics, 20... Metals with good thermal conductivity, 21...
joint.

Claims (1)

[Scope of Claims] 1. A discharge protection device for electrical equipment comprising an arcing stud and a discharge chip disposed opposite to the arcing stud with an appropriate discharge distance between the arcing stud and the discharge chip. A discharge protection device for electrical equipment characterized by being constructed of conductive ceramics. 2. The discharge protection device for electrical equipment according to claim 1, wherein the conductive ceramic has two different resistances. 3. A discharge protection device for an electrical device having an arcing stud and a discharge chip disposed opposite the arcing stud with a suitable discharge distance, wherein at least one of the arcing stud and the discharge chip is made of conductive ceramics, A discharge protection device for electrical equipment characterized by being constructed of a metal with good thermal conductivity.