U.S. patent application number 10/124470 was filed with the patent office on 2003-10-16 for header with overlying eyelet.
Invention is credited to Avetisian, Vahan, Berg, Paul, Renz, Robert.
Application Number | 20030192446 10/124470 |
Document ID | / |
Family ID | 28790877 |
Filed Date | 2003-10-16 |
United States Patent
Application |
20030192446 |
Kind Code |
A1 |
Berg, Paul ; et al. |
October 16, 2003 |
Header with overlying eyelet
Abstract
Disclosed is a pyrotechnic initiator header having an eyelet
overlying a recessed primary glass insulator. The recessed region
can be filled with a secondary glass insulator and/or a pyrotechnic
ignition charge.
Inventors: |
Berg, Paul; (Northridge,
CA) ; Avetisian, Vahan; (Newbury Park, CA) ;
Renz, Robert; (Phoenix, AZ) |
Correspondence
Address: |
THOMAS J. BRINDISI
20 28TH PLACE
SUITE B
VENICE
CA
90291
US
|
Family ID: |
28790877 |
Appl. No.: |
10/124470 |
Filed: |
April 16, 2002 |
Current U.S.
Class: |
102/202.9 |
Current CPC
Class: |
F42B 3/103 20130101 |
Class at
Publication: |
102/202.9 |
International
Class: |
F42C 001/00 |
Claims
We claim:
1. A header for use in a pyrotechnic initiator, comprising: a) an
electrically conductive eyelet having an upper eyelet surface and
an eyelet bore defining an inner eyelet surface; b) a primary glass
insulator having an outer glass surface and an upper glass surface,
and having an insulator bore defining an inner glass surface,
wherein said outer glass surface is sealed to said inner eyelet
surface, and said upper glass surface is disposed below said upper
surface of said eyelet; c) an electrically conductive center pin
having an upper end, said center pin being disposed within said
insulator bore and sealed to said inner glass surface; and, d) a
bridgewire attached between said upper eyelet surface and said
upper end of said center pin.
2. The header of claim 1, wherein said upper glass surface is
flat.
3. The header of claim 1, wherein said upper glass surface includes
a meniscus.
4. The header of claim 1, further including an ignition charge
droplet that includes a portion that is disposed between said
center pin and said inner eyelet surface and extends below the
plane of said upper eyelet surface.
5. The header of claim 4, wherein said droplet further includes a
portion that extends above the plane of said upper eyelet
surface.
6. The header of claim 4, wherein said ignition charge droplet
extends down to said upper glass surface.
7. The header of claim 6, wherein said center pin includes a
circumferential notch above said upper glass surface and below said
upper end of said center pin.
8. The header of claim 1, further comprising a secondary glass
insulator disposed between said center pin and inner eyelet
surface, said secondary glass insulator having an upper surface
that does not protrude above the plane of said upper eyelet
surface.
9. The header of claim 8, wherein said primary glass insulator and
said secondary glass insulator are made from pressed parts.
10. The header of claim 8, wherein said upper surface of said
secondary glass insulator is substantially flat.
11. The header of claim 8, wherein said upper surface of said
secondary glass insulator includes a meniscus.
12. The header of claim 11, further including an ignition charge
droplet that includes a portion that is disposed between said
center pin and said inner eyelet surface and extends below the
plane of said upper eyelet surface.
13. The header of claim 1, further including an electrically
conductive ground pin that is welded, soldered, or press-fit onto
said eyelet.
14. The header of claim 1, wherein said eyelet is cold-formed.
15. The header of claim 1, wherein said eyelet is formed by
stamping.
16. The header of claim 1, wherein said eyelet includes at least
one punched hole.
17. The header of claim 15, wherein said eyelet primarily consists
of 1010 carbon steel.
18. The header of claim 1, wherein said eyelet, primary glass
insulator, and center pin are selected of materials to result in a
compression seal when subjected to a suitable glass sealing
process.
19. The header of claim 1, wherein said header is formed to be
attached to a can loaded with an output pyrotechnic charge.
20. The header of claim 19, wherein said header is further formed
to be incorporated into an initiator assembly for use in an
automotive airbag inflator.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to the field of pyrotechnic
initiators, and more particularly to a pyrotechnic initiator having
an eyelet that overlies the glass insulator.
[0002] 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. Nevertheless, there remains a
substantial need in the automotive airbag industry in particular as
well as in other applications, for further reduction in the costs
of manufacturing reliable initiators.
SUMMARY OF THE INVENTION
[0003] In accordance with the present invention, a header for an
initiator is provided that includes an eyelet overlying the glass
insulator. A smaller second glass insulator aspect can also be
provided, or the bridgewire can be suspended and encapsulated in an
ignition droplet.
BRIEF DESCRIPTION OF THE FIGURE
[0004] The FIGURE is a side sectional view of an embodiment of the
present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0005] In conventional sealed-glass headers, there is a single
insulator that is flush with the top surface of a generally
cylindrical eyelet. As shown in the FIGURE, however, a preferred
embodiment of a header 20 according to the present invention
includes a ground pin 30, a central isolated pin 40, a primary
glass insulator 50, an overlying eyelet 60, and a bridgewire 70,
with the primary glass insulator 50 being recessed below and
substantially covered over by the eyelet 60. Consequently, the top
of the pin 70 is flush with the top surface of the eyelet 60, and
separated therefrom by an annular region that is filled with a
secondary glass insulator 80, or, alternately (not shown), with an
ignition pyrotechnic charge.
[0006] Although eyelets in conventional sealed-glass headers are
typically machined from stainless steel, the eyelet of the present
invention may desirably be fabricated of nickel-plated 1010 carbon
steel. Further, the eyelet can be stamped or cold-formed
(preferably into a cup-like shape as shown), and then plated with
nickel using a standard plating process. The eyelet should have a
wall thickness that is sufficient to sustain a compression seal and
to sustain ballistic firing forces without creating undue stress in
the glass. However, it should be thin enough that the header can
fit within the allotted space for the initiator assembly, and thin
enough to facilitate any desired stamping or cold-forming. The hole
in eyelet 60 (which includes the upper portion of the isolated pin
40 and the annular region around it) may also simply be punched,
preferably after the stamping or cold-forming of the eyelet 60, and
may even be done on the same press.
[0007] The primary glass insulator 50, pins 30 and 40, and eyelet
60 are preferably of materials that are selected to result in a
compression seal, or less preferably, a matched seal. For example,
a suitable compression seal would result with a 1010 carbon steel
eyelet, a sodasilicate (e.g., TM9) primary glass insulator, and
pins of a 52 alloy (or less preferably 42-6 alloy). The primary
glass insulator can be made of drawn or pressed glass. The ground
pin 30 may be press fit into a corresponding hole (not shown) in
the eyelet 60, or it can be welded on, or it can be brazed with a
solder ring during the sealing process. Both pins are preferably
gold-plated, either individually, or as part of the header in
"barrel" plating process.
[0008] If the annular region between the isolated pin 40 and the
eyelet 60 is filled with a secondary glass insulator 80, it may
made be flush (either by a non-grinding flush-glassing process, or
by grinding), or it can have a meniscus. The material of a
secondary glass insulator 80 is also preferably selected for a
compression seal, or less preferably for a matched seal, but in
either case, is preferably the same material as the primary glass
insulator. The secondary glass insulator also may be drawn or
pressed, and if pressed, the primary and secondary glass insulators
could be made of a single integral pressed piece. If a flush
secondary glass insulator is not used, grinding of the top surface
of the header may be eliminated since the bridgewire will be
suspended above, rather than lying flat against, a glass
surface.
[0009] There are a number of ways to seal a header according to the
present invention wherein the eyelet overlies a primary glass
insulator. For example, the header can be fixtured upside-down,
using a fixture that includes a carbon or other suitable projection
(not shown) to displace the primary glass insulator 50 (but not the
isolated pin 40) away from the top surface of the eyelet 60 during
heating and sealing. Alternately, the header might be fixtured
right-side-up, using a fixture that includes means positioned below
the primary glass insulator 50 to support it at the appropriate
height during heating and sealing. While steps can also be taken to
ensure that the top surface of the primary glass insulator 50 is
flat (as shown in the FIGURE), a meniscus (not shown) on the top
surface of the primary glass insulator 50 may also be
acceptable.
[0010] If an ignition charge is placed in the annular region
between the isolated pin 40 and the eyelet 60 rather than a
secondary glass insulator 80, or if a secondary glass insulator 80
is formed with a meniscus and an ignition charge is placed in the
sunken region of an insulator 80 below the plane of the top surface
of the eyelet 60, such an ignition charge is preferably dispensed
as a droplet. Such a droplet can be dispensed in a liquid or slurry
using formulas and techniques known to those of ordinary skill in
the art, such as those described in U.S. Pat. No. 5,939,660 to
Fogle, Jr., which patent is incorporated herein by reference as if
set forth in full. Such a droplet can preferably be sprayed or
dispensed with volumetric dispensing syringe-type equipment, and if
there is no secondary glass insulator, the retention of the droplet
in place can be enhanced by the provision of a circumferential
notch (not shown) or other irregular surface near the top of
isolated pin 40.
[0011] Assignee's co-pending U.S. patent application Ser. No.
09/733,548, filed Dec. 7, 2000, the disclosure of which is
incorporated herein by reference as if set forth in full, teaches
another recessed header wherein a substantial part of the
bridgewire is suspended a distance away from the glass. As with the
invention of that application, in the present invention, if a
secondary glass insulator is not used, the annular cavity between
the isolated pin and the eyelet beneficially helps to maintain the
ignition charge in contact with the bridgewire so that it does not
move during environmental testing or other physical shocks.
[0012] As evident to one of ordinary skill in the art, the header
of the present invention can be pressed into a suitable can (not
shown) that is loaded with a suitable output pyrotechnic charge
(such as one provided using a conventional slurry loading process).
The header can then be hermetically sealed (for example, with a
through-weld) to the can to form an initiator sub-assembly, which
can in turn be completed by, for example, a suitable method of
insert-molding a nylon body to provide electrical insulation and
structural support.
[0013] A preferred header with recessed glass insulator, 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 and their legal
equivalents.
* * * * *