U.S. patent application number 10/158317 was filed with the patent office on 2003-12-04 for detonator utilizing features of automotive airbag initiators.
Invention is credited to Forman, David M., Tirmizi, Abrar A., Vawter, Gloria, Walsh, John J..
Application Number | 20030221575 10/158317 |
Document ID | / |
Family ID | 29582644 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030221575 |
Kind Code |
A1 |
Walsh, John J. ; et
al. |
December 4, 2003 |
Detonator utilizing features of automotive airbag initiators
Abstract
A detonator that incorporates certain features of automotive
airbag initiators, and methods of making same.
Inventors: |
Walsh, John J.; (Oak Park,
CA) ; Forman, David M.; (Newhall, CA) ;
Tirmizi, Abrar A.; (Simi Valley, CA) ; Vawter,
Gloria; (Valencia, CA) |
Correspondence
Address: |
Thomas J. Brindisi, Esq.
20 28TH PLACE, SUITE B
Studio City
CA
90291
US
|
Family ID: |
29582644 |
Appl. No.: |
10/158317 |
Filed: |
May 29, 2002 |
Current U.S.
Class: |
102/202.5 |
Current CPC
Class: |
F42B 3/121 20130101 |
Class at
Publication: |
102/202.5 |
International
Class: |
F42C 019/12; F42B
003/10; F42B 003/12 |
Claims
What is claimed is:
1. A detonator comprising: a) a cylindrical shell having a
detonator end and an input end, said detonator end being closed and
packed with a charge; b) an ignition element within said shell and
located adjacent to said charge, said ignition element including
one or more of the following: i) a header including a sealed
feedthrough, ii) a metallic charge can, iii) an electrically
insulating cup, iv) a zirconium potassium perchlorate ignition
charge, v) a low-energy igniter wire; and, c) trigger means
extending from said input end of said shell to said ignition
element, for causing said ignition element to ignite in response to
the receipt of a selected signal by said trigger means.
2. The detonator of claim 1, wherein said trigger means includes
two electrical input leads at said input end of said shell.
3. The detonator of claim 1, wherein said trigger means includes a
delay means for delaying the ignition of said ignition means for a
predetermined period of time after receipt of said selected signal
by said trigger means.
4. The detonator of claim 3, wherein said delay means is an
electronic delay means.
5. The detonator of claim 1, wherein said shell has a thickness of
0.5 mm, and an outer diameter of between 6 mm and 8 mm.
6. A detonator comprising: a) a cylindrical shell having a
detonator end and an input end, said detonator end being closed and
packed with a charge; b) an ignition element within said shell and
located adjacent to said charge, said ignition element including a
header with a sealed feedthrough; and, c) a trigger means extending
from said input end of said shell to said ignition element, for
causing said ignition element to ignite in response to the receipt
of a selected signal by said trigger means.
7. The detonator of claim 6, wherein said ignition element includes
an ignition charge, a can surrounding said ignition charge and
connected to said header, and an insulating cup surrounding said
can.
8. The detonator of claim 6, wherein said ignition element includes
an ignition charge that includes zirconium potassium
perchlorate.
9. The detonator of claim 6, wherein said ignition element includes
a low-energy igniter wire having two ends that are electrically
connected to said feedthrough.
10. The detonator of claim 9, wherein the diameter of said igniter
wire is less than 20 microns.
11. The detonator of claim 6, wherein said header includes a
glass-to-metal seal.
12. The detonator of claim 11, wherein said header is an all-glass
header.
13. The detonator of claim 6, wherein said shell has a thickness of
0.5 mm, and an outer diameter of between 6 mm and 8 mm.
14. The detonator of claim 6, wherein said trigger means includes
two electrical input leads at said input end of said shell.
15. The detonator of claim 6, wherein said trigger means includes a
delay means for delaying the ignition of said ignition means for a
predetermined period of time after receipt of said selected signal
by said trigger means.
16. The detonator of claim 15, wherein said delay means is an
electronic delay means.
17. A method of making a detonator comprising the following steps:
a) providing a cylindrical shell having a detonator end and an
input end, said detonator end being closed; b) packing said
detonator end of said shell with a suitable charge; c) providing an
ignition element including a header with a sealed feedthrough
within said shell and adjacent to said charge; d) providing a
trigger means extending from said input end o f said shell to said
ignition element, said trigger means for causing said ignition
element to ignite in response to the receipt of a selected signal
by said trigger means; and, e) securing said ignition element and
trigger means within said shell.
18. The method of claim 17, further comprising the step of loading
an ignition charge of zirconium potassium perchlorate within said
ignition element.
19. The method of claim 17, further comprising the steps of:
providing a metallic can and loading it with an ignition charge,
securing said can to said header, and securing an insulating cup
around said can.
20. The method of claim 17, wherein said trigger means includes a
delay means for delaying the ignition of said ignition means for a
predetermined period of time after receipt of said selected signal
by said trigger means.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to pyrotechnic detonators, and
more particularly, to a detonator that incorporates features known
in certain automotive airbag initiators.
[0002] The efficient use of explosives in mining operations and the
demolition of structures often requires that many charges be placed
in a predetermined pattern and detonated in a timed sequence. In
general, timed detonation can be accomplished by detonators that
use pyrotechnic delays, sequential-type blasting machines, and
electronically programmable detonators. Some examples of
time-delayed detonators are described in U.S. Pat. Nos. 6,173,651,
6,085,659, 6,079,332, 5,602,360, 5,460,093, 5,435,248, 4,869,170,
4,819,560, 4,730,558, and 4,712,477, the disclosures of which are
hereby incorporated by reference herein.
[0003] Such detonators are subject to one or more drawbacks,
however, such as the following: (1) the use of an ignition element
that is difficult to manufacture to precise dimensions so as to
ensure predictable performance, (2) the use of an ignition element
that requires careful handling during manufacturing and thus
impedes the beneficial incorporation of automated steps in the
detonator assembly process, (3) the use of an ignition charge that
contains lead, which presents an environmental and health hazard,
(4) the use of a non-low energy ignition element, which reduces the
ability to provide a compact design, (5) lack of reliability, and
(6) costly manufacturing.
[0004] On the other hand, such problems are overcome or at least
ameliorated in well-known automotive airbag initiators such as
those currently manufactured and sold by the assignee of this
patent application. Various patents also disclose other examples of
initiators having features that address one or more of such
problems, including U.S. Pat. Nos. 6,274,252, 5,709,724, 5,639,986,
5,602,359, 5,596,163, 5,404,263, 5,140,906, and 3,971,320, the
disclosures of which are hereby incorporated by reference
herein.
[0005] Despite the advances regarding these issues in the
automotive airbag initiator field, it is believed that hitherto it
has not been conceived or attempted to apply various features of
such automotive initiators that overcome or ameliorate the
aforementioned problems, to detonators that are used in mining,
blasting, and demolition.
SUMMARY OF THE INVENTION
[0006] One object of the present invention is to provide a
detonator that incorporates one or more features of automotive
airbag initiators so as to overcome or ameliorate one or more of
the problems enumerated above.
[0007] Another objective of the present invention is to provide a
detonator utilizing an ignition element similar to those in
automotive initiators, resulting in a reliable and economical
detonator.
[0008] Another separate and alternative objective of the present
invention is to provide a detonator utilizing an ignition element
that is relatively easy to manufacture to precise dimensions with
known and proven manufacturing processes, resulting in a detonator
having predictable performance.
[0009] It is another separate and alternative objective of the
present invention to provide a detonator utilizing an ignition
element that is sufficiently durable to permit the incorporation of
useful automation steps in the detonator assembly process.
[0010] It is a further separate and alternative objective of the
present invention to provide a detonator utilizing an ignition
charge that does not contain any lead, so as to reduce hazards to
the environmental and health resulting from the use of the
detonator.
[0011] It is yet another separate and alternative objective of the
present invention to provide a detonator utilizing a low energy
ignition element, resulting in a detonator that may be made more
compact.
BRIEF DESCRIPTION OF THE FIGURES
[0012] FIG. 1 is a side sectional view of an embodiment of the
present invention, showing the ignition subassembly portion of the
detonator.
[0013] FIG. 2 is a top sectional view of an alternate ignition
subassembly embodiment to that of FIG. 1.
[0014] FIG. 3 is a partial exploded and sectional view showing how
an ignition subassembly such as that of FIG. 1 fits into a loaded
shell of a detonator according to the present invention.
[0015] FIG. 4 is partial top sectional view of the header and part
of the circuit board of the ignition subassembly of FIG. 2.
[0016] FIG. 5 is a partial bottom view of the header and part of
the circuit board shown in FIG. 4, illustrating the offset from
centerline of the header's pins.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT.sup.1
[0017] Referring to FIGS. 1 and 2, an ignition subassembly 8 of an
embodiment of the present invention, and an alternate embodiment
8', are shown. As shown in FIG. 3, such a subassembly is placed
inside of a shell 40 that may contain a primary charge 36 and a
base charge 38 loaded into its closed end. (A detonator shell is
typically a metal cylinder 6 to 8 mm. in diameter and from 60-100
mm. in length). Subassembly 8 can then be secured in place in the
shell 40, such as by placing an elastomeric plug or the like (not
shown) in the open end of the shell and crimping the shell 40 to
the plug, or other suitable method. Subassembly 8 may have a body
portion 32 formed of an encapsulation 31 and may have ridges 57
protruding out from the outer surface of body portion 32, so as to
snugly hold subassembly 8 within the shell 40. Such ridges 57 or
other protuberances may preferably be formed to dampen vibrations
to which the detonator may be subjected, generally in accordance
with the teachings of U.S. Pat. No. 6,079,332. .sup.1The present
description incorporates by reference in full the disclosures of
the following copending applications filed herewith: "STANDALONE
IGNITION SUBASSEMBLY FOR DETONATORS," by John J. Walsh, David M.
Forman, Abrar A. Tirmizi, and Gloria Vawter, (Express Mail No.
EU124495286US); "DETONATOR WITH AN IGNITION ELEMENT HAVING A
TRANSISTOR-TYPE SEALED FEEDTHROUGH," by David M. Forman and John H.
Oldham (Express Mail No. EU124495272US), and "DETONATOR WITH
ONBOARD ELECTRONICS MECHANICALLY CONNECTED TO IGNITION ELEMENT"
(Express Mail No. EU124495683US), each of which applications is
assigned to the assignee of the present application.
[0018] Alternately, an ignition subassembly similar to that of
FIGS. 1 and 2 (but preferably lacking encapsulation 31) can be
directly incorporated into a shell, such as by molding it directly
in the shell. Various other methods of incorporating an ignition
element into a detonator in accordance with the present invention
will be readily apparent, and it is noted that implementing various
automotive airbag initiator features in a detonator according to
the present invention does not require the use of a "standalone"
ignition subassembly like the ones shown in FIGS. 1-3.
[0019] Turning to the specifics of the automotive airbag initiator
features incorporated in the depicted embodiments, it can be seen
that an automotive airbag initiator-style ignition element 28 is
provided at one end of the ignition subassembly 8. Specifically,
ignition element 28 includes a header assembly with a sealed
electrical feedthrough, comprising an eyelet 10 (preferably
stainless steel), insulator glass 14 (preferably a glass such as a
sodasilicate, e.g., 9010, that is chosen to form a compression seal
with the eyelet and center pin, or less preferably a matched seal),
a center pin 18 (preferably an iron/nickel alloy), a ground pin 20,
and an igniter wire 12 (preferably a low energy igniter wire with a
diameter of 10 to 20 microns). Ground pin 20 and center pin 18 are
preferably selected of the same material. The ignition element 28
further preferably includes a charge can 26 that is preferably
metallic and hermetically sealed to the eyelet at circumferential
through-weld 16, with an ignition charge 30 contained between the
can 26 and upper surface of the header, in tight contact with
igniter wire 12. An insulator cup 27 may preferably be attached
around the can 26 so that, except for female connectors 52 that
protrude from the input end of the subassembly, the entire outer
surface of ignition subassembly 8 consists of insulating material,
thus providing electrical isolation and vibration and environmental
protection to the components within.
[0020] In the depicted embodiment, a circuit board 24 and
electronic components 25 may be provided within ignition
subassembly 8, to provide a means of triggering ignition of the
ignition element based on the processing of an electrical ignition
signal received by input leads 51, which are electrically connected
to a blasting machine or the like that powers the detonator. Such
electronic components are well-known and preferably include means
for imparting a programmable period of delay to the ignition, means
for ESD and RF protection, et cetera. (Another preferred
alternative is the use of an application-specific integrated
circuit). Circuit board 24 and electronic components 25 are
preferably encapsulated together in encapsulation 31, and connected
to pins 18 and 20 at contacts 22 through soldering or other
suitable connection. Referring to FIGS. 2 and 4, as is well-known
in encapsulated automotive airbag initiators, retention of the
ignition element 28 to the encapsulation 31 may be enhanced by
providing a lip 17 at the bottom of the eyelet 10'. The insulator
cup 27' may also be held within the encapsulation to facilitate its
retention as well.
[0021] FIGS. 4 and 5 illustrate an alternate embodiment similar to
that of FIG. 2, wherein the pins 18' and 20' are slightly offset
from the centerline of the header, so that the circuit board 24 can
occupy that centerline, which corresponds to the widest portion of
the cylindrical body portion 32.
[0022] By way of example, in an embodiment like that shown in FIGS.
1 and 2, it has been found that a nickel/chromium alloy, 13 micron
diameter, 0.7 mm long igniter wire, a 50 mg ignition charge of
zirconium potassium perchlorate having a height of 1.0 mm and a
diameter of 4.8 mm is suitable. Preferably, a minimum suitable
charge is approximately 30 mg for a configuration of this size, as
a smaller charge may result in an insufficient charge thickness. A
preferred all-fire voltage may be 6 volts, and may be delivered
with a 100 microfarad capacitor included in the electronic
components 25 in an embodiment like that depicted.
[0023] It should be noted that although the Figures depict
embodiments including electronic components that receive, process,
and deliver an ignition signal, such an ignition signal may
alternately be received, processed, and delivered by a number of
other well-known non-electronic or partly-electronic means, such as
through the use of a shock tube to deliver an ignition signal to a
piezoelectric device, column fuse delays, et cetera. It is noted
that this detailed description of certain embodiments does not
imply that such alternate embodiments are not within the scope of
the invention.
[0024] A preferred embodiment of a detonator utilizing features
known in certain automotive airbag initiators, and many of its
attendant advantages, has thus been disclosed. It will be apparent,
however, that various changes may be made in the form,
construction, and arrangement of the parts without departing from
the spirit and scope of the invention, the form hereinbefore
described being merely a preferred or exemplary embodiment thereof.
Therefore, the invention is not to be restricted or limited except
in accordance with the following claims.
* * * * *