GB953336A - An electrical igniter - Google Patents

Abstract

953,336. Electrical igniter for explosives. RHEINMETAL G.m.b.H. May 9, 1960 [May 15, 1959], No. 16395/60. Heading F3A. An electrical igniter for explosive charges has a capacitor which includes two coiled metal foils 1 with an insulating intermediate layer and an end face 3 which provide spark gaps in the ignition zone, wherein the resistance of the ionization path between inner and outer poles 4, 6, other than that provided by the spark gaps, is greater than that which would be provided by inner and outer poles having end faces coplanar with face 3. The inner pole is electrically connected to the inner foil and e.g. to the positive terminal of a source of current, while the outer pole is connected to the outer foil and the negative terminal. The outer pole comprises a metallic strip 6 which partially encloses the outer surface 5 of the coil and is so positioned that an insulating air gap is left between its face 7 and the end face 3 of the coils. Alternatively or in conjunction the end face of the inner pole may be similarly positioned relative to the coil face 3. The air gap prevents the build-up of an electric field between the poles which would adversely affect the formation of sparks across the end face 3 when a predetermined voltage is exceeded. In another form the outer pole comprises a metallic ring enclosing the capacitor and insulated from the inner pole by a disc placed on top of the flanged portion of the inner pole 2 and beneath the ring. In another form the coil is enclosed in the vicinity of the ignition zone by a ring of insulating material of synthetic plastic which extends beyond the end face 3 and provides a chamber for a primer charge. The outer and annular pole has an annular recess to accommodate the ring, and extends in like manner, so that its upper end terminates in the plane of the end face of the said ring. Specification 792,169 is referred to.