US2420651A - Ignition device - Google Patents

Description

y 0, 1947. L. A. BURROWS EI'AL GNITION DEVICE iled Dec. 9, 1942 .l zm

Patented May 20, i947 umrso srATas PATENT OFFKCE 2;420,651 IGNITION DEVICE poration of Delaware Application December 9, 1942, Serial No. 468,364

5 Claims. 1

This invention relates to friction igniters, and in particular to pull-wire igniters which may be used in initiators, for example torpedo caps.

A satisfactory way of designing such igniters is to have the pull wire pass into a shell contain- 5 ing various compositions necessary for bringing about friction and combustion. No satisfactory way of doing this has been available in methods of the prior art. The usual materials that might be used for closing the end of a shell through l0 which the Wire passes have several disadvantages. One objection is that they have not been completely impervious to water, especially under severe storage and other rigorous conditions.

Furthermore, the pull or force required to ignite the charge cannot be determined, because the force necessary to accomplish this varies with the temperature, since these plugs contract and expand with change in temperature. It is important that this be a known, controllable, and

uniform force so as to render the igniter safe. A further defect in igniters of the prior art is that the container holding the flash material is free to move on the wire, which often causes this compound to come in contact with the striker material and prematurely ignite the charge, thus rendering the igniter more hazardous.

An object of the present invention is a new and improved igniter. Another object is a safety I friction igniter with a movable wire. A further object is a friction igniter in which ignition is accomplished by pulling a wire, the force required to cause said ignition being uniform and unaffected by temperature, thus permitting said force to be predetermined. A further object is 5 the production of a pull-wire igniter in which rubber is molded about said pull wire and so constructed as to maintain a fixed relationship between the striker and friction materials. An

additional object is the production of a pull-Wire igniter with uniform performance and enhanced safety. Other objects will be apparent as the description of the invention proceeds.

These objects are achieved and the foregoing disadvantages overcome by employing a charged cylindrical shell having a closed base; a rubberlike plug closing the mouth of said shell, said plug having an elongation of lesser dimensions at the end within said shell; a cup adapted to fit over said elongation and to be secured firmly 60 thereby, said cup being charged with a flashproducing agent; a wire passing through said plug, said plug being molded about said wire, a portion of said wire supporting a, friction-producing agent, said cup and striker end of said (Cl. 102-2'l) wire being so constructed as to maintain a fixed relationship between the two, said .wire being capable, when forceis applied thereto, of effecting ignition of the flash material. Although other materials are within the scope of this invention, we prefer to use gilding metal for the cup and shell and tinned stainless steel wire, 0.032" in diameter, for the pull wire.

Our invention may be understood more readily by referring to the accompanying drawing which serves to illustrate a preferred embodiment of the invention, but this should not be construed to limit the scope thereof. Like numerals designate corresponding parts in the two figures.

Referring generally to the figures of the drawing, Figure 1 is a view in cross-section of the improved pull-wire igniter of our invention assembled in the shell. Figure 2 is a view of the friction and flame-producing elements of the igniter.

Referring in greater detail to the figures, in Figure 1 the numeral I designates a gilding metal shell which is charged with 13.5 grains of tetranitromethylaniline as the base charge 2, 4 grains lead azide as the primer charge 3, and 2.5 grains of a mixture of sulfur, chlorate, and lead sulfocyanate as the main ignition charge 4. The rubber-like cylindrical plug 9 of the igniter extends substantially to the mouth of the shell I and is held therein by crimps II. A small loop I4 is formed on the pull wire I0 and the end of said wire is coiled (I3) around another part of the wire and cut (ii). The pull wire extends through the center of the rubber-like plug 9, the cylindrical elongation 8 of said plug, the flash material ]5 in the gilding metal cup I, and into the central portion of said shell I. At this end the wire is coated with a striker composition 6 comprising 28.6% amorphous red phosphorous, 7.1% ammonium phosphate and 64.3% emery flour, these materials being held together with a nitrocellulose binder. The metal cup 1, into the base of which fits the elongation 8, contains the flash material comprising 33% antimony sulfide and- 67% potassium chlorate, these materials being held together with a similar nitrocellulose binder. The paper spacer tube 5 butts against the plug 9 and the ignition charge 4. The purpose of this tube is to prevent the tail wire from being accidentally forced in the ignition charge and igniting it when the pull-wire units are being assembled in shells.

We have described our plug and plug elongation materials as rubber-like. By this term we refer to those properties generally possessed by rubber compositions, namely elasticity, springiness and extensibility, and, in one sense of the word, compressibility. This capacity of our plug material for rebounding, springing back, and returning to its original shape without permanent deformation, which is characteristic of rubber, is

effective in the pull-wire igniter of our invention for the purpose of forming an effective seal between the shell and plug by crimping the shell into the rubber-like plug material, and at the same time retaining substantial adhesion of said plug to said wire. It will be seen, therefore, that it is important that the wire not only adhere to the plug sufficiently to hold it in position until the predetermined force is applied at the time of firing, but also that it be capable of movement back and forth through said plug when force has been applied. We find molding said plug about said wire to be very suitable for the purpose. Furthermore, the aforementioned properties of our plug material are eflective in producing an igniter which requires a uniform and pre-.

- ized chloroprene compositions, butyl rubber and all such materials that possess the properties described, whenever a plug is formed about the wire in a pull-wire igniter.

In the foregoing, we have expressed a preference for a. pull-wire igniter comprising a singlewire, cylindrical rubber-like plug. containing a smaller cylindrical elongation of said plug, on which a metal cup containing the flash material is placed. However, it is to be understood that our invention also includes, among other things, a pull-wire igniter comprising a two-wire, cylindrical rubber-like plug containing a flat rubber-like wedge, with one Wire cut at the end of said plug opposite said wedge, and the other end extending through said plug and wedge and at this point coiled around the central or pull wire to serve as a framework or receptacle to hold the flash material. Furthermore, the invention is intended to include pull-wire igniters of the type described containing a cylindrical rubber-like plug but having no wedge or longitudinal extension of lesser dimensions. be particularly applicable in the two-wire igniters.

The pull-wire igniter of our invention possesses several outstanding advantages. The rubher-like plug, when crimped into the shell, forms an effective seal between the plug and the shell and between the pull wire and the plug,- thereby protecting the shell charge from water. The plug maintains its original shape and degree of adhesion to the pull wire under varying temperatures, enabling ignition by applying a uniform and predetermined force to the Wire at the pull-wire loop, thus increasing the safety and workability of the igniter. The rubber-like projection, which is a longitudinal continuation of the central portion of said plug, forms a suitable attachment for the flash material cup and preventsthis material from contacting the igniter compound and causing accidental ignition, and in this respect improves the safety of our pull-Wire igniter. I

In the accompanying drawings the invention has been shown merely by way of example and in preferred form, but obviously many variations and modifications may be made therein which This will will still be comprised within its spirit. It is to be understood, therefore, that the invention is not limited to any specific form, composition, method of preparation, Or embodiment except in so far as such limitations are specified in the following patent claims.

We claim:

1. An ignition device comprising a charged cylindrical shell having a closed base; a plug of rubber-like material closing the open end of said shell, said plug having an elongation of lesser dimensions at the end within said shell; a container adapted to fit over said elongation and to be secured firmly thereby, said container being charged with a flash-producing agent; a wire having a striker end passing through said plug, said plug being molded about said wire, and through said container in movable relationship therewith; said container and striker end of said wire being so constructed as to maintain a fixed relationship therebetween, said wire being capable, when pulling force is applied thereto, of effecting ignition of the flash-producing agent.

2. An ignition device comprising a charged cylindrical metal shell; a plug of rubber-like material closing the open end of said shell, said plug having an elongation of lesser dimensions at the end within said shell; a metal capsule adapted to fit over said elongation, with the base of said capsule adjacent to said plug to be secured firmly thereby; said capsule being charged with a flash-producing agent; a wire passing through said plug, said plug being molded about said wire, and through said capsule in movable relationship therewith and a portion of its surface supporting a friction-producing agent; said capsule and friction-supporting end of said wire being so constructed as to maintain a fixed relationship therebetween, said wire being capable, when pulling force is applied thereto, of effecting ignition of the flash-producing agent.

3. An ignition device comprising a charged cylindrical gilding metal shell; a plug of rubberlike material as described closing the open end of said shell and held therein in a water impervious manner, said plug havin an elongation of lesser diameter at the end within said shell; a gilding metal capsule adapted to fit over said elongation, with the base of said capsule adjacent to the plug, to be secured firmly thereby; said capsule being charged with a flash-producing agent; a wire passing longitudinally through the axis'of said plug, said plug being molded about said wire, and through said capsule in movable relationship therewith and a portion'of its surface being coated with a friction-producing agent, said wire being capable, when pulling force is applied thereto, of effecting ignition of the flash-producing agent; said igniter being so constructed as to maintain a fixed relationship between said capsule and' the friction-coated end of said wire.

4. An ignition device comprising a charged cylindrical gilding metal shell; a plug of rubberlike material closing the mouth of said shell and secured thereto by a crimp extending around the circumference of the shell in the region enclosing said plug forcing the shell wall into and deforming said plug to complete a water-proof juncture, said plug having an elongation of lesser dimensions at the end within said shell; a gilding metal cup adapted to fit over said elongation, with the base of said cup adjacent to said plug, to be secured firmly thereby; said cup being charged with a flash material; a wire passing ngitudinally through the axis of said plug, said ug being molded about said wire, and through .id cup in movable relationship therewith and a irtion of its surface being coated with a. friction- 'oducing material, said wire being capable, when llling force is applied thereto, of effecting ignian of the flash material; said'igniter being so instructed as to maintain said cup and coated id of said wire at a given distance from each her.

5. An ignition device comprising a charged cyidrical gilding metal shell; a plug of rubber- :e material closing the mouth of said shell and cured thereto by a crimp extending around the rcumference of the shell in the region enclosing id plug forcing the shell wall into and deformg said plug to complete a water-tight juncture,

id plug having an elongation of lesser dimen- )IlS at the end within said shell; a gilding metal psule adapted to fit over said elongation, with e base of said capsule adjacent to said plug, to

secured firmly thereby; said capsule being .arged with a flash-producing agent; a tinned ainless steel wire 0.032" in diameter passing ."lgitudinally through the axis of said plug, said llg being molded about said wire, and through id capsule in movable relationship therewith id a portion of its surface being coated with a .ction-producing agent, said wire being capable,

5 Number REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date 549,297 Sharp et al Nov. 5, 1895 757,226 Reininger Apr. 12, 1904 1,697,814 Forbes Jan. 1, 1929 333,655 Michaelis Jan. 5, 1886 FOREIGN PATENTS Number Country Date 15,001 ,Great Britain June 20, 1891 16,196 Great Britain Oct. 28, 1887 2,630 Great Britain Jan. 27, 1916 166,115 Germany Dec. 19, 1905

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