|Publication number||US3793501 A|
|Publication date||Feb 19, 1974|
|Filing date||Dec 4, 1972|
|Priority date||Dec 4, 1972|
|Publication number||US 3793501 A, US 3793501A, US-A-3793501, US3793501 A, US3793501A|
|Original Assignee||Ici America Inc|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (5), Referenced by (37), Classifications (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent 1 Stonestrom EXPLOSIVE SWITCH  Inventor: Donald M. Stonestrom, West Chester, Pa,
 Assignee: ICI America Inc., Wilmington, Del.
 Filed: Dec. 4, 1972  Appl. N0.: 311,494
Related US. Application Data  Continuation-in-partbf Ser. No. 145,608, May 12, 1971, abandoned.
 US. Cl. .J. ZOO/61.08  Int. Cl. H0lh 39/00  Field of Search ZOO/61.08, 168 F  References Cited UNITED STATES PATENTS 2,931,874 4/1960 Leaman ZOO/61.08 X
[4 1 Feb. 19,1974
8/1966 Gay ZOO/61.08 X
3,264,438 3,277,255 10/1966 Mattsson et al. ZOO/61.08 3,286,064 11/1966 Wilson et a1 ZOO/61.08 X
FOREIGN PATENTS OR APPLICATIONS 916,030 1/1963 Great Britain 200/6108 Primary Examiner-.1. R. Scott  ABSTRACT An explosive switch capable of opening or closing one or more poles. An explosive charge moves a piston to which are fixed one or more plungers, each plunger acting as part of a separate pole. Each plunger has a wide portion and a narrow portion. Metal contacts are provided which fit over-the wide portion, making the pole normally opened, or over the narrow portion, making the pole normally closed. The piston can also disconnect a connection to the bridgewire.
8 Claims, 8 Drawing Figures l EXPLOSIVE SWITCH I have invented an explosive switch where the explosive charge moves a piston within a casing. To the piston are fixed one or more plungers, each acting as a separate pole. Each plunger has a wide portion and a narrow portion. If a contact which fits over the wide portion is used, the pole is normally opened. If a contact which fits over the narrow portion is used, the pole is normally closed. The contacts may be easily arranged to give various combinations of normallyopened or normally-closed poles. Initation of the explosive charge forces the plunger between two pins and forces the narrow portion into an insulated well.
The piston in the switch may also disconnect a connection to the bridgewire in a bridgewire-ignited explosive charge. This is an important advantage where the power supply is of a limited capacity since occasionally the bridgewire will fail to completely rupture and will continue to drain the source of electrical energy.
FIG. 1 is a longitudinal, mid-sectional view of the closed firing circuit of a one-shot electro-explosive switch capable of opening or. closing two independent circuits and is the presently preferred embodiment of this invention.
' FIG. 2 is a cross-sectional view through random section 22 in FIG. 1 showing both sides of the switch and all circuit pins.
FIG. 3 is a cross-sectional view through 3-3 in FIG.
1 showing both sides of the switch and the firing circuit.
FIG. 4 is a longitudinal, mid-sectional view of the switch shown in FIG. 1 which has been activated and where the firing circuit is open.
FIG. 5 is a cross-sectional view of FIG. 1 taken through 55 in FIGS. 2 and 3 showing the switch before activation and one circuit open.
FIG. 6 is the view of FIGS after firing and the closed circuit.
FIG. 7 is a longitudinal view of FIG. 1 taken through 7 --7 in FIGS. 2 and 3 showing the closed circuit before firing.
FIG. 8 is the view of FIG. 7 after firing showing the circuit open.
In FIGS. 1 through 8, of casing 1 has a base 2 which 1 holds six pins 3, 4, 5, 6, 7, and 8 (see FIGS. 2, 5, and 6 for pins 7 and 8) imbedded in glass 9 forming a glassto-metal seal between pins 3, 4, 5, 6, 7, and 8 and base 2. The pins are supported by plastic mounting l0. Wire contacts 11 and 12 have end portions 13 and 14, re-
spectively, which touch pins 5 and 6, respectively, and also touch pins 15 and 16, respectively, which are held by piston 17. Piston 17 comprises plastic part 18 and metal part 19 which holds pins 15 and 16 in glass seal 20. An O-ring 21 is mounted on the metal part 19 of the piston to prevent gas leaking. A bridgewire 22 joins pins 16 and 15 and is coated with explosive charge 23. A cup 24 prevents the piston from moving upward.
FIG. 3 shows that plastic part 18 has two plungers 25 and 26 which have wide portions 27 and 28, respectively, and narrow end portions 29 and 30, respectively. FIG. 2 shows key 31 of plastic part 18 which keeps plastic part 18 centered in aperture 32 of plastic mounting l0 and prevents it from rotating (see FIG. 1 also). Plastic mounting 10 has a thin breakaway portion 33 which prevents the switch from functioning when shocked, vibrated, or otherwise subjected to G-forces in the downward direction. It also contains the aperture 32 for key 31.
In FIGS. 7 and 8, short metal contact 34 having end portions 35 and 36 completes the circuit between pins 3 and 4 making a normally-closed switch. Contact 34v is held in place by narrow portion 29 of'plunge'r 25 which presses against contact 34 directly above a well 38 in plastic mounting 10 formed from a portion 39 of 'plastic mounting 10.
In FIGS. 5 and 6, plunger 26 has long metal contact 40 fitted over it and this contact completes the circuit between pins 7 and 8 after firing. Both metal contacts are held in place before firing by thin breakaway portion 33.
The switch is assembled with either two short contacts giving two normally-closed poles, two long contacts giving two normally-opened poles, or one of each as shown in the drawings. In FIG. 1, a current is sent through the circuit pin 5 (shortened to designate firing circuit) to wire contact 1 1 to pin 15 to bridgewire 22 to pin 16 to wire contact 12 to pin 6. This initiates explosive charge 23 forcing piston 17 down so that plastic part 18 disconnects metal contacts 11 and 12 from pins 15 and 16, respectively, by pushing end portions 13 and 15 away from pins 15 and 16, respectively. The switch is sealed before and after initiation and no gases from the explosion escape as can be seen in FIG. 4.
For a plunger having a short metal contact fitted over it (FIG. 7) forming a normally-closed switch, the plunger severs breakaway portion 33 pushing it and metal contact 34 into well 38. As can be seen from FIG. 8, portion 39 of plastic mounting 10 will cause end portions 35 and 36 of contact 34 to separate from pins 3 and 4. I
For a plunger having a long metal'contact fitted over it forming a normally-opened switch, it can be seen from FIG. 5 that contact 40 will not touch pins 7 or 8 prior to initiation, but in FIG. 6 will touch both pins after firing thereby closing the pole.
The switch could also be made with only one pole or with many poles. The explosive charge configuration may be 1 watt, 1 amp, or have RF protection by using techniques well known in the art. A delay between the application of current to the switch and its functioning may be provided by interposing a pyrotechnic delay column between an igniter above the piston and the explosive charge. Molded phenolic parts or other suitable materials may be substituted for the glass-to-metal seals. A four-lobed ring seal, bellows seal, or other suitable seal may be substituted for O-ring 21. The parts referred to as plastic" may be made from suitable materials which are technically not plastics. Other variations will no doubt also come to mind.
Switches having both normally-opened and normallyclosed poles similar to the one shown in the drawings have been made, subjected to severe tests, and successfully functioned. They are remarkably small, about 6 inches long (not including pins) and about 5/16 inches in diameter, and have withstood 13,600 Gs in the downward direction.
What is claimed is:
1. An explosively activated electrical switch comprismg:
a. a casing having an insulative base and within said casing a piston in movable engagement therewith, said piston having a pair of electrical contact pins and at least one insulative plunger connected thereto, said plunger having a wide portion and a leading narrow end portion, conductive means disposed on said insulative plunger, said electrical contact pins being in electrical contact through conductive means with at least one pair of firing circuit pins passing through said base;
b. an explosive charge within said casing positioned so that said piston moves when electrical current is passed through said pair of firing circuit pins; and
c. at least one other pair of circuit pins passing through said base positioned in cooperative relationship with said plunger, said plunger conductive means being such that it forms a closed circuit between said other pair of circuit pins either before or after said explosive is initiated to move said piston.
2. An explosively activated electrical switch of claim 1 wherein said plunger conductive means is a metal contact capable of fitting over-the wide portion of said plunger, and said other pair of metal circuit pins passing through said base are separated by a distance no greater than the width of said conductive means fitted over said wide portion.
3. An explosively activated switch according to claim 1 wherein said conductive means is positioned in contact with said pair of circuit pins passing through said base and which is capable of extending over the wide portion of said plunger after said explosive charge is initiated to move said piston) 4. An explosively activated electrical switch according to claim 3 wherein said pair of circuit pins passing through said base have an insulating well therebetweeri such that when said explosive charge is initiated said plunger conductive means is forced into said insulating well out of electrical contact with said circuit pins.
5. An explosive switch according to claim 4 wherein said well is covered with a breakaway barrier.
6. An explosive switch according to claim 1 wherein at least two plungers are in cooperative relationship with at least two pairs of circuit pins passing through said base.
7. An explosive switch according to claim 6 wherein the plunger conductive means of at least one plunger forms a closed circuit with at least one pair of circuit pins before said charge is initiated and at least a second plunger forms a closed circuit with a second pair of circuit pins after said charge is initiated.
8. An explosive switch according to claim 1 wherein said explosive charge is electrically initiated through a bridgewire connected across said pair of electrical contact pins in said piston.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,793,501
f Febr a y 19' INVENTOR(S) n ld M. Stonestrom It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 1, line 47, "of casing 1'' should read a casing l Column 2, line 27, "13 and 15" should read l3 and 14 Signed and Scaled this twenty-first D a Of October 19 75 [SEAL] A ttes t:
RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ofPatenrs and Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,793,501
DATED February 19, 1974 INVENTOMS) 3 Donald M. Stonestrom It is certified that error appears in the ab0ve-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 1, line 47, "of casing 1" should read a casing l Column 2, line 27, "13 and 15" should read l3 and 14 w Signed and Sealed this twenty-first Day of October 1975 [SEAL] i Attest:
RUTH C MASON C. MARSHALL DANN Arresting Officer Commissioner ofParenrs and Trademarkx
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