US1856642A - Fire-damp proof time fuse - Google Patents

Description

May 3, 1932. E. KAR'oLLUs FIRE DAMP PROOF TIME FUSE Filed Sept. 29, 1930 /N yeN fak Patented May 3, 1932 l stares FIRE-Dm PROF TME FUSE Application ned september as, issu, sel-rei Ne. `islaam, ena Vin ansa-ia september pao, 1929.

This invention relates to a time fuse consisting in the known manner of an electric glow fuse and a detonating cap. A retardation or delay-action fuse contained in a special shell is inserted between the glow us'e,

and the detonating cap.

Gases are formedduring the ignition of the said fuse. These gases must be quickly dis charged, otherwise the shells containing the fuse would burst. A pointed dame is produced which immediately ignites the blasting charge whereby the action f the time fuse, which consists in retarding the ignition of the blasting charge, will be annulled.

However, the chief drawback of the formation of the said pointed ame resides in the fact that this llame is adapted to ignite fire damp.

A large number of arrangements or systems have become known which have for their-object to quickly expand the gases formed during the lgnition of the fuse and to cool them during the expansion so that apointed flame can no longer be produced.

For this purpose, .porous material (filters) of non-infiammable matter in the form of plugs or -illers are provided in the path where the gases areexpanded.

Practical experience has shown that it is not immaterial where these porous materials (filters) are provided and in which direction the gases are led. The filter materials must present only slight resistance to the advance- Y ment of the gases. The filter materials must be so shaped and arranged that they cannot be compressed by the gas pressure to such an extent that they form an obstruction for the passage of thegases or close the perforations o the fuse.

The openings of the `fuse,thro ugh which the gases escape into the bore hole chamber, must be provided in such places of the fuse so that they cannot be covered externally.

All time fuses have the last drawback, wherein the openings are directed in the bore hole chamber on the obstruction side. The drawback that parts of the filter material are forced internally against the outlet openings into the bore hole chamber and partial-n ly close same is to be found in most of those arrangements or systems wherein thesaid outlet openings4 are closed or protection against moisture or impurities externally. Theinner pressure must increase until the plug or the like is forced away or burnt.A The p ath for the gases is vthen suddenly opened and the gases entrain parts of the filter material into the opening which is again closed. This process fr uently causes a bursting of the shell of these and the formation of a pointed flame.

These drawbacks" are obviated by the present invention by the following arrangement or system.

Figure 1 shows a longitudinal sectional view of the invention.

Figure 2 shows a longitudinal sectional view of a modification of Fig. 1, showing the ribs 11.

Figure 3 shows a cross sectional view thru the r1b section 11 of Fig. 2.

' The shell 4 Figure 1) contains in its upper part the e ectrically ignitable composition 1, below which there is a plug 12 com-` posed of glass, slag, or asbestos wool and provided with a central bore 13 wherein a tube 14 is inserted which does not extend to the endsv of the bore. During the ignition, the pointed llame coming from the electric fuse may freely. strike through the said tube Vand reach the retardation fuse 5 which is provided in the retarder 2. The retarder 2 is surrounded by the shell 8 which has a ange 10. .The shell 4 is mounted on the shell 8. The shell 8 is of such dimensions that a space is left betweenit and the shell 4. The

shells are fixed by a center-mark 6 so that the plug 12 of the shell 4 firmly bears against the retardation fuse 5 and a rigid connectionv is formed between 4 and 8.

The end of the shell 8 directed toward the detonating cap 3 is slightly conical-shaped so that the shell 7 of the detonating cap 3 --bears tightly on the said conical part of the shell 8 and the shell 8 cannot pass to thel composition of the cap.

According to the constructional form shown in Figures 2 and 3, the shell 8 has longitudinal ribs 11 so far as it is inserted in the shell 4.

It is advisable to provide the shell 4, on its lower end opposite the flange 10 with notches or the like.

The fuse operates as follows:

As soon as the composition 1 of the electric fuse is ignited, the pointed flame thereof strikes through the tube 13 so the retardation fuse 5 which burns and ignites the composition of the detonating cap 3.

The excessive gases can immediately pass from the electric fuse 1, then above and below the tube 14 and from the retardation fuse 5 into the plug 12 without any obstruction; the gases are cooled therein and can freely pass to the chamber between shell 4 and shell 8 whence they issue past the edge 9 of the flange 10 into the bore hole chamber. This part of the bore hole chamber is always uncovered and a free exit of the gases is therefore also possible. It is possible by this arrangement to prevent a bursting of the shell and the formation of a pointed flame.

According to the present invention, it is possible to obtain a uniform, vfrictionless degassing free from a pointed flame in the space always remaining free between composition and charge so that the duration ofv combustion of a time fuse is maintained up to 116 part of a second and not only a premature eXplosion of the blasting charge' is avoided but also the security of the fire-damp is increased.

What I claim is:

Fire-damp proof time-fuse with a filter layer preventing the formation of a pointed flame, characterized in that the filter-plug made of non-inflammable fibrin in the known manner is arranged between the electrically ignitable composition and the retarder and is provided with an axial bore, into which a tube is inserted but which does not extend to the ends of the bore in order to lead the pointed flame from the glow-fuse to the retarder.

In testimony whereof I affix my signature.

. EDMUND KAROLLUS.

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