Ammunition and explosives – Igniting devices and systems – Electrical primer or ignitor
Reexamination Certificate
2002-11-14
2003-09-02
Carone, Michael J. (Department: 3641)
Ammunition and explosives
Igniting devices and systems
Electrical primer or ignitor
C102S202100, C102S202700, C102S202900
Reexamination Certificate
active
06612241
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the field of initiators, and more particularly to a pyrotechnic initiator having a center pin with a circumferential notch retention feature.
Pyrotechnic initiators have many uses in industrial and consumer applications. One important use is the inflation of airbags in motor vehicles. As airbag production has steadily increased, significant efforts have been made to reduce the cost of reliable airbag initiators. One advance has been the use of a pyrotechnic droplet that is dispensed onto the header of the airbag initiator in a liquid or slurry form. For example, a generally suitable formula and techniques for dispensing liquid or slurry pyrotechnic droplets are described in U.S. Pat. No. 5,821,446 to Chatley, Jr., and U.S. Pat. No. 5,939,660 to Fogle, Jr., which are incorporated herein by reference as if set forth in full. A droplet can be dispensed with volumetric dispensing syringe-type equipment, or it can also be sprayed or placed after it is dispensed onto another part of the equipment.
And as is shown in
FIG. 1
(generally depicting a header made by Nico Pyrotechnic of Trittau, Germany), it is known to use two pins
25
raised above the glass (
45
)/metal (
60
) header surface, with “nailheads”
26
on the ends of the pins
25
, to help retain the droplet in place on the surface of the header. As shown by crack
27
, however, after the liquid or slurry droplet
80
is dispensed and begins to harden, it tends to contract around the pins
25
, creating a region between the pins
25
that is prone to cracking apart at crack
27
. The effects of this are potentially magnified by the fact that such a crack may be immediately adjacent to the bridgewire
70
. Further, in the plane of the nailheads of pins
25
, a crack
28
may also form between the nailheads of the pins
25
and the edges of the droplet
80
, potentially allowing the top of the droplet
80
to shear away from the rest of the droplet
80
. Thus, there remains a need for improvement of the means of retaining such droplets in place on the header.
SUMMARY OF THE INVENTION
In accordance with the present invention, a header for an initiator is provided that includes a center pin with a circumferential notch retention feature. The circumferential notch retention feature of the center pin enhances secure and effective disposition of an ignition pyrotechnic charge droplet to the header in the area of the bridgewire.
REFERENCES:
patent: 5763814 (1998-06-01), Avory et al.
patent: 5821446 (1998-10-01), Chatley, Jr.
patent: 5939660 (1999-08-01), Fogle, Jr.
patent: 6446557 (2002-09-01), Lubbers
Blackner H. A.
Carone Michael J.
Law Offices of Thomas J. Brindisi
Special Devices, Inc.
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