Squib design

• US 4,208,967 A
• Filed: 05/15/1978
• Issued: 06/24/1980
• Est. Priority Date: 05/15/1978
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Betts, Robert E.
• Primary Examiner(s): Brown, David H.
• Application Number:
  US05/905,833
• Time in Patent Office: 771 Days
• Field of Search: 102/28 R, 102/28 M, 102/28 EB, 102/46, 102/202, 102/203
• US Class Current: 102/202.14
• CPC Class Codes: F42B 3/128 characterised by the composition of the pyrotechnic material

Abstract

The electrically initiated squib of this invention is comprised of a plug member with a pair of spaced apart electrical leads extending through the plug member into a holder member for containing a predetermined quantity of an easily-ignitable composition. A bridgewire that is constructed of a bimetallic composite (Pyrofuze) selected from palladium and aluminum, platinum and aluminum, and ruthenium-palladium alloy and aluminum is secured between the electrical lead ends that terminate in the holder member of the squib. The holder member is loaded with a loose, easily-ignitable composition which is a finely-ground and intimate mixture of a pyrotechnic which is a composition selected from the group consisting of 45% by weight zirconium and 55% by weight potassium perchlorate, 20% by weight boron and 80% by weight potassium nitrate, 45% by weight aluminum flake (17 to 44 microns) and 55% by weight potassium perchlorate (6 to 17 microns), and lead azide or lead styphnate, or a single-base, a double-base, or composite propellant composition in a powder or pellet form. The combination improves the reliability of the squib while reducing the controls on loading and assembly procedures. The amount of easily-ignitable composition to ensure ignition need not be controlled, since the proximity of the easily-ignitable composition to the bimetallic composite bridgewire is not critical. The amount of material that the bridgewire ignites may govern the squib output; however, the reliability of ignition is ensured by the presence of the easily-ignitable composition in the holder member where the bimetallic composite undergoes a violent exothermic reaction after being brought to its ignition temperature by the application of electric current. The violent exothermic reaction is accompanied by a deflagration or a throwing out of the high temperature constituents of the bimetallic bridgewire.

Claims

1. An electrically initiated squib allowing reduced loading and assembling procedures while attaining improved reliability for igniting, said electrically initiated squib comprising in combination:

(i) a pair of electrically insulated lead members positioned in a spaced apart relationship and extending through an insulating plug member, said lead members having terminated ends outside said insulating plug member;

(ii) a bridgewire fastened between said terminated ends of said lead members, said bridgewire constructed of a bimetallic composite selected from the group consisting of palladium and aluminum, platinum and aluminum, and ruthenium-palladium alloy and aluminum, said bridgewire having the capability of igniting an appropriate charge loosely confined within a holder member, said charge being spaced from said bridgewire and within a throw pattern of said bridgewire; and

,

(iii) a housing member for containing said insulating plug member, said lead members, and said bridgewire, said housing member and said plug member when in combination additionally defining a holder member that contains a predetermined quantity of said appropriate charge as a loose, easily-ignitable composition within the throw pattern of said bridgewire after said bridgewire is brought to its ignition temperature by the application of electrical current, said ignition temperature causing a violent exothermic reaction that is accompanied by a deflagration or a throwing out of the high temperature constituents of said bimetallic bridgewire, said easily-ignitable composition being a composition selected from the group of easily-ignitable compositions specified under pyrotechnic groups A-C as follows;

Pyrotechnic group A;

metal fuel-oxidizer, composition 1;

magnesium 60% by weight and polytetrafluoroethylene 40% by weight;

composition 2;

boron 23.7%±

2% by weight, potassium nitrate 70.7%±

2% by weight, and binder 5.6% by weight;

composition 3;

zirconium 10 microns particle size 45% by weight and potassium perchlorate 6 to 17 microns particle size 55% by weight; and

composition 4;

aluminum flake 17 to 44 microns particle size 45% by weight and potassium perchlorate 6 to 17 microns particle size 55% by weight;

Pyrotechnic group B;

primary explosive, composition 1;

lead azide; and

composition 2;

lead styphnate;

Pyrotechnic group C;

propellants, composition 1;

double-base propellants;

composition 2;

single-base propellants;

composition 3;

composite propellants; and

composition 4;

black powders.

2. The electrically initiated squib as defined in claim 1 wherein said housing member is provided with an end cap which in combination with said housing member defines said holder member.

3. The electrically initiated squib as defined in claim 1 wherein a spacer member is employed in combination with said housing member to define said holder member, said housing member being in the form of a unitary construction.