US3132586A

US3132586A - Electric detonator

Info

Publication number: US3132586A
Application number: US126149A
Authority: US
Inventors: Scharwachter Werner
Original assignee: Dynamit Nobel AG
Current assignee: Dynamit Nobel AG
Priority date: 1960-10-18
Filing date: 1961-07-24
Publication date: 1964-05-12
Anticipated expiration: 1981-05-12

Description

y 12, 1964 w. scHARwAcHTER 3,132,586

ELECTRIC DETONATOR Filed July 24, 1961 INVENTOR WERNER SCHARWACHTER.

RNE

a 3,132,586 Patented May 12;, 1964 ELEcTnrc nEroNA'ron [Werner Scharwachter, Spich, Germany, assignor to Dynamit Nobel, A.G., Troisdorf, Bezirk (Iologne, Germany, a German corporation Filed July 24, 1961, Ser. No. 126,149 i priority, application Germany Oct. 18, 1960 Claims 2 Claims. (Cl. 102-28) This invention relates to detonators and, particularly, to that type of detonator which is activated electrically.

'Detonators as employed for setting off explosive charges are often subject to undesired ignition by' stray i currents, electrostatic discharges, and atmospheric electrical potential disturbances. Numerous methods and processes have been proposed to avoid such undesirable igni- ;tion and the most successful to date for such a purpose is V the type which is adapted to shunt such current so that it does not affect the glow wire which is ordinarily used in the ignition circuit. Imperfections in the manufacture of 1 such devices may render uncertain their successful opera- '1 It is an object of this invention to provide a construc- 'tion of,detonator which will positively prevent external tion.

voltage conditions from accidentallysetting off. the detonating charge.

Other objects and advantages of the construction will be'in part obvious and'inpart pointed out hereinafter.

In'tlie drawing in which is shown a prior art construction and an improved embodiment of the invention:

. FIG. 1 is a longitudinal section of a detonator as found I: in the prior art;

United States Patent ever, since in the process of manufacture the supporting element 24 is not always accurately made and the contact at the

edges

28 and 30 with the housing 10 is not equally effective. In that case, with current passing, for instance,-

from the edge 28 to the terminals and 22, there may well be a large potential difference at the terminals to cause glow in the element 12. Accidental discharge of the detonator may then take place.

To avoid thiseifect, the construction of the support for

terminals

22 and 20 has been modifiedso that. in every case the path of the currents from housing 10 to'either terminal will be of substantially the same resistance. To

this end, the invention provides a support 40 which in this instance, is diamond-shaped. As in the previous case, support 40 is of high-resistance material so that'high voltages will not particularly obstruct the flow of current therethrough, while the ordinary low voltages used for activating, the glow element 12'will not be particularly ductor 1s will be conductively substantially the same as 2'i's a cross section taken along the line 22 of 2 FIG. 1 looking in the direction of the arrows;

" FIG.;3 is a longitudinal section of an improved detonator embodying the invention; and

FIG. 4 is a cross section taken along the line 44 of FIG. 3'looking in the direction of the arrows.

Referring to the drawing,in FIGS. 1 and 2 are shown 7 a construction of a detonator which has found favor in the past and which is constructed with an enclosing outer housing 10 within which is suitably mounted an ignition elementor glow Wire 12 for igniting a detonating charge 214. Glowwire 12 is provided with apair of conductors 16 and18 to which is adapted to be applied a suitable ,at'erminal 20 or 22 unequallyso that the difierence in. {potential between the terminals will cause activation of' 7 element 12 In order to avoid this, in the past, the supelectrical current from a' suitable source. Glow wire 12 is attached to a pair of

terminals

20 and 22 suitably mounted in a supporting body 24 held in place within housing 10. The end of housing 10 is closed by a suitable plug 26. As heretofore constructed, the support 24 is rectangular in section and the

terminals

20 and 22 are spaced apart preferably symmetrical about the center of the support. Contact with the outer housing 10 is provided at i I

opposite edges

28 and 30. n l The housing 10 is normally metallic and the ordinary danger is that there will be an arc'from the housing to the glow element 12, or that in someway current will pass to porting element 24 has been made of conductive material of relatively high resistance so that the drop in voltage between point 28 and terminal 20 would be substantially the same as that occurring from the edge 30 to terminal 22." Thus, the efiect would be an equal grounding through conductors 16 and 18 and no potential diiference across :the element 12. This has not always been effective, how- 'trically conductive material, an ignition element within the housing, a pair of electrical conductors for said element operatively connected to said ignition element and, 1

extending to without the housing, a support for said coni the path to conductor 16 andthe potential at these points shouldbe substantially thesame or in any case of insuflicient difference to cause any appreciable flow through element 12. The same condition will hold if corner 44 contacts the wallof housing 10 instead of corner 42. In

any case, there will be no arcing from housing 10 to either conductors 16 or 18 inasmuch as the resistance through the support 40 will be less than across the gap.

Thus are accomplished, among others, the objects hereinbefore referred to.

I claim:

1. An electric detonator comprising a housing of elecductors of relatively low electrical conductivity mounted within thehousingin contact therewith, said support supporting said conductors in spaced relation with respect to each other and with respect to' the housing by engagement of the support and conductors, the shortest distance from each point of contact of the housing and support to each conductor being equal, whereby current path from said housing to each terminal is of substantially the same resistance. I v

2. An electric detonator as set forth in claim 1,in

which said support has a diamond-shaped cross section and extends .axially along said housing with one pair of opposite corners, thereof contacting the housing and the other pair of opposite corners thereof spaced from the housing, one of said conductors being supported at each of said other pair of corners.

References Cited in the file of this patent UNITED STATES PATENTS 2,974,590 Ramer Mar. 14, 1961' V FOREIGN PATENTS 961,873

Germany Apr. 11, 1957

Claims

1. AN ELECTRIC DETONATOR COMPRISING A HOUSING OF ELECTRICALLY CONDUCTIVE MATERIAL, AN IGNITION ELEMENT WITHIN THE HOUSING, A PAIR OF ELECTRICAL CONDUCTORS FOR SAID ELEMENT OPERATIVELY CONNECTED TO SAID IGNITION ELEMENT AND EXTENDING TO WITHOUT THE HOUSING, A SUPPORT FOR SAID CONDUCTORS OF RELATIVELY LOW ELECTRICAL CONDUCTIVITY MOUNTED WITHIN THE HOUSING IN CONTACT THEREWITH, SAID SUPPORT SUPPORTING SAID CONDUCTORS IN SPACED RELATION WITH RESPECT TO EACH OTHER AND WITH RESPECT TO THE HOUSING BY ENGAGEMENT OF THE SUPPORT AND CONDUCTORS, THE SHORTEST DISTANCE FORM EACH POINT OF CONTACT OF THE HOUSING AND SUPPORT TO EACH CONDUCTOR BEING EQUAL, WHEREBY CURRENT PATH FROM SAID HOUSING TO EACH TERMINAL IS OF SUBSTANTIALLY THE SAME RESISTANCE.