SU64173A1 - Explosion-proof electric lamp - Google Patents

Description

The design of an explosion-proof electrical equipment, in essence, solves the problems of lighting mines that are dangerous for gas. The danger that a short circuit creates is, besides the power of the arc capable of igniting the gas, also in heating the conductors to such high temperatures that touching them of the mine gas will cause the latter to ignite. Among the devices that heat up during normal operation, incandescent bulbs are very dangerous. The working temperature of the filament is so high that white heat is unavoidable, therefore, the design of lighting fixtures intended for operation in gas mines deserves the most serious attention. The design of electric incandescent lamps requires the use of glass for the lamp and the protective cap. The possibility of damage to the glass cap is quite obvious. Therefore, the lack of an automatic device for switching off the electrical circuit before the destruction of the bulb of the incandescent lamp reduces safety when working in mines. As a result of repeated experiments, it has been established that the existing lamp designs do not provide explosion safety when the lamp bulb is broken and do not prevent the heated thread from contacting the flammable mixture. The latter depends both on the time that elapses between the moment the glass bulb of the lamp is destroyed and the interruption of the electric current, and on the cooling rate of the lamp filament itself. It has been established experimentally that the limiting time interval between the moment of interruption of the current and the breaking of the flask, which still creates the possibility of igniting the mine gas mixture, is about 0.03 seconds. It is obvious that lamp fittings should be designed so that when the bulb of the electric lamp is damaged, the current is automatically turned off, and the contact of the glower with the explosive mixture should occur only after a certain minimum period of time during which the thread should cool to a temperature incapable of causing a gas explosion. The explosion of a gas mixture with a naked red thread is equally dangerous.

and when working with conventional battery lamps, since the main danger in this case is not the voltage, but the temperature of the thread and the power of the supply current. These values in battery cells usually differ little from the corresponding values of normal incandescent lamps.

In order to eliminate the drawbacks of the existing structures of mine lighting fixtures, both for battery luminaires and for lamps powered from a lighting network, the present invention provides an appropriate device for automatically switching off electricity until the bulb of the incandescent bulb is open.

The intrinsic safety of the proposed construction is achieved by the fact that the power supply circuit breaker is interlocked with the glass protective lamp fittings so that the switching device gets an impulse to turn off until the light bulb is destroyed, namely, at the moment of beating, the protective glass.

According to the invention, the protective glass bell rests on its base with the help of metal supports on three hollow glass bows, which hold spring contacts in a closed state, connected in series to the filament lamp of the incandescent lamp. When hitting the cap, at least one of the three balls will be destroyed, due to which the lamp power supply circuit is automatically interrupted.

The invention is illustrated in the drawing; in FIG. I of which depicts the design of the proposed explosion-proof lamp for mains supply, and FIG. 2 is the same - luminaire type of mine battery lamp.

The protective glass cap I is mounted on three evenly spaced circumferentially metal supports 2. Lamps On the outer side, the cap fits snugly to the valve cover, and a rubber gasket in the form of a ring 3 is laid between the glass and the cover (Fig. 1) . The supports in the lower part of the quiesum are located on three hollow glass balls 4, which are installed in the sockets on the fiber disk 5. On the latter, a beam-shaped spring 6 is mounted. Under the disk 5, a second fiber disk 7 is mounted, on which the segment contacts are fixed. A gap is provided for adjusting the contacts between the spring and the segments. Three protrusions of the contact spring 6 in the working position are pressed glass balls with balls to touch the segment contacts tightly, there is a flap on the disk 7, and this results in a series connection of the contacts in the lamp power supply circuit. Due to the fact that the protective cap rests on three metal supports, and the latter are standing on hollow glass balls, then a significant blow to the cap anywhere (a blow threatening to cause collapse of the cap) must destroy at least one ball . Thus, the spring breaks the power supply circuit of the lampe until the moment of possible destruction of the glass bulb of the incandescent bulb.

Subject invention

An explosive electric luminaire with a protective glass cap holding in a closed position a series of contacts connected in series to the lamp circuit so that when they hit the cap they open the lamp circuit, characterized in that the cap 1 with its cover rests through intermediate supports 2 Three hollow glass balls 4, which hold the spring contacts in the closed position, so that when you strike the cap, one of the balls collapses and the contacts automatically open.

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FIG. one

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FIG. 2

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