U.S. patent application number 11/023304 was filed with the patent office on 2006-06-29 for method and apparatus for an improved initiator and retainer.
This patent application is currently assigned to LIFESPARC, INC.. Invention is credited to Rick Mavrakis, Alex Orozco.
Application Number | 20060137559 11/023304 |
Document ID | / |
Family ID | 36609915 |
Filed Date | 2006-06-29 |
United States Patent
Application |
20060137559 |
Kind Code |
A1 |
Mavrakis; Rick ; et
al. |
June 29, 2006 |
Method and apparatus for an improved initiator and retainer
Abstract
An initiator is provided for use with an initiator holder. The
initiator comprises a can; at least two electrodes; an explosive
charge positioned to be ignited when electrical charge is passed
through said electrodes; and a body portion surrounding the
electrodes. The body portion may have a first portion with a first
cross-sectional area and a second portion having a second
cross-sectional area, wherein the second cross-sectional area has a
shape different from the first cross-sectional area and wherein the
second cross-sectional area is less than 40% of the first
cross-sectional area; wherein the second portion is shaped to
extend outward from an opening in the holder when the body portion
is seated in the holder.
Inventors: |
Mavrakis; Rick; (Alta Loma,
CA) ; Orozco; Alex; (Hollister, CA) |
Correspondence
Address: |
HELLER EHRMAN LLP
275 MIDDLEFIELD ROAD
MENLO PARK
CA
94025-3506
US
|
Assignee: |
LIFESPARC, INC.
Hollister
CA
95023
|
Family ID: |
36609915 |
Appl. No.: |
11/023304 |
Filed: |
December 23, 2004 |
Current U.S.
Class: |
102/202.12 |
Current CPC
Class: |
F42C 19/06 20130101;
F42B 3/103 20130101 |
Class at
Publication: |
102/202.12 |
International
Class: |
F42B 3/10 20060101
F42B003/10 |
Claims
1. An initiator for use with an initiator holder, said initiator
comprising: a can; at least two electrodes; an explosive charge
positioned in the can and configured to be ignited when electrical
charge is passed through said electrodes; and a body portion
surrounding at least a portion of said electrodes, said body
portion having a first portion with a first cross-sectional area
and a second portion having a second cross-sectional area, said
first cross-sectional area measured at the interface with the
second portion; said second cross-sectional area having a shape
different from said first cross-sectional area and wherein said
second cross-sectional area is less than 40% of said first
cross-sectional area; wherein said second portion is shaped to
extend outward from an opening in the holder when the body portion
is seated in the holder.
2. The device of claim 1 wherein the first cross-sectional area has
a circular shape.
3. The device of claim 1 wherein the second cross-sectional area
has a race track shape.
4. The device of claim 1 wherein the second cross-sectional area
has a shape selected from one of the following: rectangular, race
track shape with a cutout, oval, square, triangular, three-legged,
rectangular with at least one rounded end, rectangular with a
cutout, or combinations of these shapes.
5. The device of claim 1 wherein the first body portion is made of
a material selected from a list consisting of: polybutylene
terephthalate, polybutylene naphthalate, high strength polyamide,
nylon 6,12, nylon 10,12, nylon 12,12, nylon 66, thermoplastic
aromatic polyamides, Amodel.TM. polyphthalamide, polyether-amides;
polyimides, Aurum.TM. (MTC America); polyether-imides,
polyether-ketones (PEK), polyether-ether-ketones (PEEK),
polyether-ketone-ether-ketone-ketones (PEKEKK), and high
temperature thermoplastic aromatic polyketone polymers, liquid
crystal polymers (LCP), Vectra.TM. A515.
6. The device of claim 1 wherein the second portion is shaped to
surround the side portions of at least two of said electrodes.
7. The device of claim 1 wherein the second portion is shaped to
prevent rotation of the initiator about its longitudinal axis when
placed in the holder.
8. The device of claim 1 wherein body portion has a section with a
conical shape, said section having conical surfaces at a 45 degree
angle.
9. The device of claim 1 wherein the body portion includes a marker
positioned to indicate polarity of the electrodes.
10. The device of claim 1 wherein the body portion has a 1.33 mm
height.
11. The device of claim 1 wherein the body portion has a 6.45 mm
diameter.
12. The device of claim 1 wherein interface between a surface of
the first portion of the initiator and an inner surface of the
holder is capable of holding the body portion in a manner
sufficient to withstand a backpressure of at least about 200
megapascals pushing the body portion against the inner surface of
the holder.
13. The device of claim 1 wherein the holder has a shape capable of
holding the body portion in a manner sufficient to withstand a
backpressure of at least about 220 megapascals pushing the body
portion against an inner surface of the holder.
14. The device of claim 1 wherein the holder is capable of holding
the body portion in a manner sufficient to withstand a backpressure
of at least about 250 megapascals pushing the body portion against
an inner surface of the holder.
15. The device of claim 1 further comprising at least one
bridgewire coupling said electrodes together.
16. The device of claim 1 wherein the area of the second portion is
less than 10% of the area of the first cross-sectional area when
measured at the widest point of the first portion.
17. An initiator for use with a holder, said initiator comprising:
a can; at least two electrically conductive pins; an explosive
charge configured to be ignited when electrical charge is passed
through said pins; and a body having a first portion with a
circular cross-section relative to a longitudinal axis of the
initiator and a second portion having a rectangular cross-section
relative to a longitudinal axis of the initiator.
18. The device of claim 17 wherein the rectangular cross-section
includes a cutout or notch portion.
19. The device of claim 17 wherein the rectangular cross-section
includes at least one rounded end portion.
20. An initiator for use with a holder, said initiator comprising:
a can; a plurality of electrodes; an explosive charge configured to
be ignited when electrical charge is passed through said
electrodes; and means for supporting and positioning said plurality
of electrodes, wherein at least a portion of said means extends
outward from the holder when the means are seated against the
holder.
21. An initiator holder comprising: a housing with an inner surface
and an outer surface, said inner surface having a shape to receive
an initiator body having a first portion and a second portion; an
opening on said housing, said opening sized and shaped to receive
the second portion of the initiator body, an area of said opening
being less than 40% of an cross-sectional area of the first portion
of the body, said first cross-sectional area measured at the
interface with the second portion.
22. The device of claim 21 wherein the inner surface conforms to
the shape of the initiatory body.
23. The device of claim 21 further comprising: said opening having
a race-track shape.
24. The device of claim 21 wherein said holder can withstand at
least 250 megapascals of pressure when the initiator body is
pressed against the holder.
25. The device of claim 21 wherein the opening has area of about
9.34 mm.sup.2.
26. A micro gas generator including at least one holder of claim
21.
27. An airbag inflator including at least one holder of claim 21.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to initiators and more specifically
to creating a robust interface between an initiator body and an
initiator holder.
[0003] 2. Description of Related Art
[0004] Initiators or "popcorn" squibs are well-known in the art.
They are used in a variety of applications such as but not limited
to deploying airbags or pretensioning of seat belts during rapid
deceleration of an automobile. These known initiators are designed
to conform to certain industry standards for size and shape.
Unfortunately, these conventional designs fail to provide a
sufficiently robust device that can withstand the rigors of rapid,
hot gas expansion and high pressure.
[0005] For example, in microgas generators (MGGs) which use
initiators, the conventional initiator retainer or holder 10, as
seen in FIG. 1, has a circular hole 12 for receiving the header 20.
The diameter of that circular hole 12 is typically about 6.6 mm.
This unit is a holder or retainer, and it holds or retains the
initiator in place. This may be done by a crimping process to apply
compression on an O-ring to obtain a good seal. This retainer may
be welded onto a housing, a large cup, molded into another device,
or the like to position the initiator for use.
[0006] Now, the initiator has an explosive primary charge which may
be used to initiate or ignite a secondary charge. The initiator may
include a header 20 with a stainless steel body, a piece of glass,
and two pins (it is called a glass to metal seal interface). A
bridge wire is placed between the centerpin, that is insulated by
glass, over to the body. This bridge wire creates an electrical
connection between the two pins. When current is sent though the
pin, the current heats the bridge wire and causes the initiator to
ignite its charge. This explosion in an inflator makes an airbag
begin to expand. This explosion in an MGG lights propellant that is
housed in another can on top of the initiator and generates a
pressure wave that will push a piston that may be used in
situations such as (but not limited to) tightening a seat belt. In
an airbag application, the initiator will ignite airbag propellant
which generates gas and inflates an airbag.
[0007] As discussed above, the standard retainer or holder for use
with the header has a circular hole as seen in FIG. 1. The diameter
of that hole is to allow the initiator when it is being assembled
to have some freedom to rotate around, allow for manufacturing
tolerances. Because the diameter of the hole and the outer diameter
of the initiator that fits in the cup are fairly close, the known
device has a reduced capability to withstand the heat and
backpressure of the charge igniting.
[0008] To determine the robustness of these initiators, there are
certain safety and performances tests where there is a fairly high
amount of pressure in the test chamber. The only thing that
prevents the pressure from exiting through a "rearward" direction
as indicated by arrow 30 in FIG. 2 is the interface between the
holder and the initiator body. This backpressure from the
detonation may sometimes cause either the retainer or the body of
the initiator to fail, causing the initiator to fire out the rear
of the device as indicated by arrow 30. Backpressure wants to push
the initiator out and that backpressure is caused by hot gas
(several hundred degrees Celsius) from the detonation of the
charge. In some situations, this hot backpressure gas will cause
the nylon body of the initiator to melt at around 500 degrees C.
This backpressure gas is strong (several thousand PSI), and it is
very hot. In a functional gas seal integrity test (FGSI), a small
test chamber is filled with powder and an initiator is mounted in a
holder in this chamber. Then, the powder is ignited and the
pressure needs to exit the chamber somehow. The gas is hot enough
to melt the plastic body of the initiator and the pressure will
want to push the header out of the holder. Since the hole in the
retainer is fairly large, what happens is the header with the body
melted away will be shot out of the chamber via several thousand
PSI of pressure.
[0009] This failure of the interface between the header and the
retainer or holder is extremely undesirable due to the potentially
lethal chain reaction that could result from high velocity ejection
of the header from the holder.
SUMMARY OF THE INVENTION
[0010] Accordingly, one object of the present invention is to
provide improved header and retainers to withstand the extreme
pressures and heat associated with charge detonation.
[0011] Another object of the present invention is to provide
improved design without significantly increasing manufacturing cost
or difficulty.
[0012] Yet another object of the present invention is to design the
holder to allow a user to visually observe the polarity of the
electrode pins during assembly of the initiator into the
holder.
[0013] A still further object of the present invention is to
provide a holder and initiator that is correctly sized for use in
MGGs and inflators.
[0014] At least some of these objects are achieved by some
embodiments of the present invention.
[0015] In one aspect of the present invention, an initiator is
provided for use with an initiator holder. The initiator comprises
a can; at least two electrodes; an explosive charge positioned to
be ignited when electrical charge is passed through said
electrodes; and a body portion surrounding the electrodes. The body
portion may have a first portion with a first cross-sectional area
and a second portion having a second cross-sectional area, wherein
the second cross-sectional area has a shape different from the
first cross-sectional area and wherein the second cross-sectional
area is less than 40% of the first cross-sectional area; wherein
the second portion is shaped to extend outward from an opening in
the holder when the body portion is seated in the holder.
[0016] In another embodiment, the present invention comprises an
initiator having a can; at least two electrodes; an explosive
charge positioned in the can and configured to be ignited when
electrical charge is passed through the electrodes; and a body
portion surrounding the electrodes, wherein the body portion having
a first portion with a first cross-sectional area and a second
portion having a second cross-sectional area; a holder configured
to engage at least a portion of the body portion, wherein the
holder is capable of holding the body portion in a manner
sufficient to withstand a backpressure of at least about 200
megapascals pushing the body portion against an inner surface of
the holder.
[0017] A microgas generator may use an initiator and/or a holder as
described herein.
[0018] In another embodiment, the present invention provides a
method of manufacturing an initiator comprising: providing a can,
at least two electrodes, and an explosive charge positioned in the
can and configured to be ignited when electrical charge is passed
through said electrodes; forming a body portion surrounding at
least a portion of said electrodes, said body portion having a
first portion with a first cross-sectional area and a second
portion having a second cross-sectional area, said second
cross-sectional area having a shape different from said first
cross-sectional area and wherein said second cross-sectional area
is less than 40% of said first cross-sectional area; wherein said
second portion is shaped to extend outward from an opening in the
holder when the body portion is seated in the holder.
[0019] A further understanding of the nature and advantages of the
invention will become apparent by reference to the remaining
portions of the specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 shows a perspective view of an initiator and holder
known in the art.
[0021] FIG. 2 shows a perspective view of an initiator seated in a
holder.
[0022] FIG. 3 shows a cross-section view of one embodiment of a
header according to the present invention.
[0023] FIG. 4 shows a cross-section view of one embodiment of an
initiator according to the present invention.
[0024] FIG. 5 shows a perspective view of an initiator according to
the present invention.
[0025] FIG. 6 is a bottom-up view of the initiator of FIG. 5.
[0026] FIG. 7 is a cross-sectional view as indicated by lines 7-7
in FIG. 6.
[0027] FIG. 8 is a cross-sectional view of one embodiment of an
initiator and a holder according to the present invention.
[0028] FIG. 9A is a bottom up view of the holder of FIG. 8.
[0029] FIG. 9B shows a perspective view a microgas generator.
[0030] FIG. 9C shows a close-up view of the holder of FIG. 8.
[0031] FIGS. 10A-10H are bottom up views of a various embodiments
of the second portion of the initiator body.
[0032] FIGS. 11A-11D various views of a various embodiments of the
first portion of the initiator body.
[0033] FIGS. 12A and 12B show the cross-sectional areas described
in FIG. 7.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0034] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed. It may be noted that, as used in the specification and the
appended claims, the singular forms "a", "an" and "the" include
plural referents unless the context clearly dictates otherwise.
Thus, for example, reference to "a material" may include mixtures
of materials and the like. References cited herein are hereby
incorporated by reference in their entirety, except to the extent
that they conflict with teaching explicitly set forth in this
specification.
[0035] In this specification and in the claims which follow,
reference will be made to a number of terms which shall be defined
to have the following meanings:
[0036] "Optional" or "optionally" means that the subsequently
described circumstance may or may not occur, so that the
description includes instances where the circumstance occurs and
instances where it does not. For example, if a device optionally
contains a feature for having a shorting bar, this means that the
shorting bar feature may or may not be present, and, thus, the
description includes structures wherein a device possesses the
shorting bar feature and structures wherein the shorting bar
feature is not present.
[0037] Referring now to FIG. 3, one embodiment of a header 100
according to the present invention will now be described. The
header 100 may include a stainless steel body 102, at least one
piece of glass 104, and two electrically conductive pins 106 and
108. These structures form a glass-to-metal field interface. A
bridge wire 110 is placed between the centerpin 108, which is
insulated by glass 104, over to the body 102. This bridge wire 110
creates an electrical connection between the two pins or electrodes
106 and 108. When current flows though the pins 106 and 108, the
current flow heats the bridge wire 110 and causes the explosive
charge 112 to ignite. Upon ignition, the explosive charge 112 will
explode outward as indicated by arrows 114. The can 116 may include
a scored portion 118 across a top surface of the can 116 to allow
the metal can 116 to fail in a controlled manner. In one
embodiment, the scores may be at equal angles to about half the
depth of the material, to encourage even opening of the can top
when the generator is used. Of course, other score depths and score
patterns may be used with the present invention. It should also be
understood of course, that other headers which use other designs
and techniques to ignite the explosive charge, such as but not
limited to semiconductor bridge initiators, may also adapted for
use with the present invention as described herein. Suitable
semiconductor bridge initiators are described in copending U.S.
patent application Ser. No. 10/914,969 (Attorney Docket No.
37073-0009C1C1).
[0038] Referring now to FIG. 4, this embodiment of the initiator
125 may also include another can 120 and a body 130 to house and
support the various elements described above for FIG. 3. The cans
116 an d120 may be made of a variety of material including but not
limited to various metals and alloys such as low-corrosion metals
and alloys, passivated stainless steel, for example of about 0.4 mm
thickness, 304 Stainless Steel. The body 130 may be made of a
variety of materials including but not limited to engineering grade
reinforced thermoplastics: glass filled engineering polyesters such
as polybutylene terephthalate, polybutylene naphthalate, and the
like; high strength polyamides such as nylon 6,12, nylon 10,12,
nylon 12,12, nylon 66, and the like; thermoplastic aromatic
polyamides such as Amodel.TM. polyphthalamide (BP Chemicals);
polyether-amides; polyimides such as Aurum.TM. (MTC America);
polyether-imides; and the like; and polyether-ketones (PEK),
polyether-ether-ketones (PEEK),
polyether-ketone-ether-ketone-ketones (PEKEKK), and similar high
temperature thermoplastic aromatic polyketone polymers, liquid
crystal polymers (LCP), Vectra.TM. A515, and compatible mixtures of
any two or more of the above. In the present embodiment, the body
130 may be overmolded or otherwise formed over the elements in FIG.
3 and over the can 120.
[0039] As seen in the embodiment of FIG. 4, the body 130 may have a
first portion 132 and a second portion 134. The first portion 132
is designed to remain inside the retainer or holder while the
second portion 134 is designed to protrude outward from an opening
in the holder. In the present embodiment, the second portion 134
also supports the pins 106 and 108 which also extend out ward from
the opening, allowing for electrical connection to a current
source. The second portion 134 may be designed to provide
protection to the pins and allow them to be properly positioned
through the hole in the retainer. In some embodiments, the second
portion 134 or lower part of the body may be shaped to engage a
clip or other interface from the wiring harness of the automobile,
carrying trigger wires from the sensor circuit. Additionally, as
seen in the cross-section of FIG. 4, the center pin 108 may include
a bend 109 so that the pin 108 outside the second portion 134 is
symmetrical about the centerline 136.
[0040] FIG. 5 shows a perspective view of one embodiment of
initiator 125 according to the present invention. The body 130 is
shaped to surround the side portions of at least two of the
electrodes or pins 106 and 108. As seen in FIG. 5, the portion 132
may include a conical or beveled portion with a surface at a 45
degree angle. Of course, the surface of the cone may also be
designed to be at angles other than 45 degrees. The second portion
134 is designed to surround the side walls of the pins 106 an 108
to provide electrical insulation and physical protection.
[0041] Referring now to FIG. 6, a bottom up view of the initiator
125 will now be described. As seen, the second portion 134 has a
race track configuration. The embodiment may optionally include a
cutout area 140. This cutout 140 allows the user to orient the pins
106 and 108 for the proper polarity during assembly with the
holder. The X associated with the cutout 140 will be visible to the
user through the opening.
[0042] As seen in FIG. 6, the cone shape of the first portion 132
has a widest diameter indicated by reference number 150 and the
smallest diameter indicated by reference number 152 on the surface
154. In the present embodiment, the dimensions for the largest
diameter and smallest diameter are 11.10 and 6.45 respectively. It
should be understood that a range of sizes may be suitable for the
present invention such as 12.0 and 7.00. The first portion 132 with
the cone shape has a circular cross-section. As seen for this
embodiment, the second portion 134 has a different cross-sectional
shape (i.e. race track) than the cross-sectional shape of the first
portion 132 (i.e. circular). The area of surface 154 is 90 sq. mm,
and the area of surface 134 is 9.34 sq. mm.
[0043] FIG. 7 shows another cross-sectional view of the body 130
(as indicated by lines 7-7 in FIG. 6). The surface 154 is designed
to rest against an inner surface 202 of the retainer 200 as more
clearly seen in FIG. 8. The surface 154 may be viewed as a
backpressure resistance surface as it will press against the
surface 202 of the retainer 200 of an initiator holder to prevent
ejection of the initiator due to backpressure. In the present
embodiment, the greater the area for surface 154, the greater its
resistance to backpressure. Of course, the holder or retainer 200
would also be designed to have a surface 202 of sufficient size to
support the surface 154. The greater the area of overlap between
surface 154 and the inner surface 202 of the retainer, the greater
the resistance to backpressure during detonation. In the present
embodiment, the surface 154 is perpendicular to the longitudinal
axis of the electrodes.
[0044] Referring now to FIG. 8, it should be understood that the
size and shape of the second portion can be selected to increase
the robustness of the initiator header. FIG. 8 shows one embodiment
where the cross-sectional area of second portion 134 is minimized
(as indicated by arrows 210) so that there is greater overlap
between surface 154 and surface 202. From a pressure point of view,
the standard holder will withstand up to 100-150 megapascals of
force. The present embodiment of an improved holder shown in FIG. 8
can withstand up to about 250 megapascal, which is beyond the
amount of pressure that a typical air bag inflator can produce. The
bottom interface is designed to withstand higher pressures while
having a 1.33 mm height. This reduced cross-sectional shape and
reduced hole size in the retainer 200 address the high MGG and
inflator backpressure issue. It should be understood that this
holder or retainer 200 may be individually formed and then attached
or welded to a housing. In some embodiments the holder or retainer
200 may be integrally formed with the housing.
[0045] FIG. 9A shows a bottom up view of the embodiment of the
retainer 200 shown in FIG. 8. As seen, the retainer 200 has a
race-track shaped opening 230 shaped to receive the second portion
134. The opening 230 is minimized in size so that there is more
overlap between the retainer and the surface 154. In some
embodiments, the retainer 200 may be part of a microgas
generator.
[0046] FIG. 9B shows a perspective view of one embodiment of a
microgas generator with the retainer 200. As seen, the second
portion 134 will be received in the opening 230. As more clearly
indicated in FIG. 9C, the cutout 140 can be seen through the
opening 230 to indicate the appropriate orientation of the
initiator.
[0047] Referring now to FIGS. 10A-10H, it should be understood that
the second portion 134 may be designed to have a variety of shapes
and still conform to the spirit of the present invention. FIGS.
10A-10H are bottom up views of only the second portions 134. FIG.
10A shows a second portion 134 having a rectangular cross-sectional
shape. FIG. 10B shows a substantially rectangular shape that is
square on one end and rounded on the other. FIG. 10C shows that the
pins 106 and 108 may be protected by separate formations, one
having a square shape and the other a circular shape. FIG. 10D-10E
shows various combinations of square, triangular, and circular
cross-sectional shapes. It should understood that these shapes may
be combined in any manner including all round, all square, any
other combination, or with shapes where one is larger is area than
the other. FIG. 10F shows a single circular device with a pin 250
in the middle and a conductive outer portion 252 that may function
as a second pin. FIG. 10G shows a dumbbell shaped cross-section and
FIG. 10H shows a three-legged shape. Of course, the holders or
retainers would have openings shaped to receive these
cross-sectional shapes.
[0048] Referring now to FIGS. 11A-11D, it should be understood that
the first portion 132 may be designed to have a variety of shapes
and still conform to the spirit of the present invention. FIG. 11A
shows an embodiment from the side where the portion 132 appears
square. FIG. 11B shows an embodiment where a larger area of portion
132 is tapered. FIG. 11C shows a top down view where the portion
132 has a square shape. FIG. 11D shows a top down view where the
device has a polygonal shape. It should be understood that the
device have a portion 132 that may be triangular, rectangular,
square, circular, polygonal, any single or multiple combination of
these shapes, whether view from top down or from the side. In some
embodiments, these portions 132 are designed to minimize the
opening for portion 134 and maximize the area of overlap with the
inner surface of the holder or retainer 200.
[0049] FIGS. 12A and 12B more clearly illustrate the
cross-sectional areas discussed with regards to FIGS. 6 and 7. The
cross-sectional area in FIG. 12A corresponds to the cross-section
of the second portion 134. The cross-sectional area in FIG. 12B
corresponds to the cross-section of the first portion 132 at the
interface with portion 134. As seen, the cross-sectional area in
FIG. 12B is significantly larger than the cross-sectional area of
the area show in FIG. 12A. In one embodiment, the cross-sectional
area in FIG. 12A is less than 40% of the cross-sectional area of
FIG. 12B. In another embodiment, the cross-sectional area in FIG.
12A is less than 30% of the cross-sectional area of FIG. 12B.
[0050] In another view, the exposed surface area of backpressure
resistance surface 154 (FIG. 6) is greater than the cross-sectional
area of FIG. 12A, which is the cross-section of portion 134. In one
embodiment, the exposed area 154 is at least 10% greater than the
cross-sectional area of FIG. 12A. In another embodiment, the
exposed area 154 is at least 20% greater than the cross-sectional
area of FIG. 12A. In another embodiment, the exposed area 154 is at
least 50% greater than the cross-sectional area of FIG. 12A. In
another embodiment, the exposed area 154 is at least 100% greater
than the cross-sectional area of FIG. 12A. The shape of the
cross-section of the area of FIG. 12A is also shaped to prevent
rotation about the longitudinal axis of the initiator. Some
embodiments may have the shape of the section 134 "keyed" with a
notch or protrusion to prevent misorientation. Some embodiments
will have the opening 230 shaped to match the cross-sectional shape
of the portion 134.
[0051] While the invention has been described and illustrated with
reference to certain particular embodiments thereof, those skilled
in the art will appreciate that various adaptations, changes,
modifications, substitutions, deletions, or additions of procedures
and protocols may be made without departing from the spirit and
scope of the invention. For example, with any of the above
embodiments, notches or cutouts may be incorporated onto the body
or other initiator portions to indicate correct orientation or
other indicator. The device may also include protrusions to "key"
into notches on the holder, or vice versa. These elements may be
found on the body portions or other housing on the initiator or
holder. For any of the embodiments above, the device may include a
shorting bar connecting the electrodes to prevent accidental
detonation. Suitable materials for use in the present invention and
shorting bar designs may be found in copending U.S. patent
application Ser. No. 10/953,468 (Attorney Docket No. 37073-0010C1).
Various embodiments of an improved initiator and holder can
withstand up to about 160, 170, 180, 190, 200, 210, 220, 230, 240,
and/or 250 megapascal of force resulting from detonation of
explosive charge.
[0052] The publications discussed or cited herein are provided
solely for their disclosure prior to the filing date of the present
application. Nothing herein is to be construed as an admission that
the present invention is not entitled to antedate such publication
by virtue of prior invention. Further, the dates of publication
provided may be different from the actual publication dates which
may need to be independently confirmed. All publications mentioned
herein are incorporated herein by reference to disclose and
describe the structures and/or methods in connection with which the
publications are cited.
[0053] Where a range of values is provided, it is understood that
each intervening value, to the tenth of the unit of the lower limit
unless the context clearly dictates otherwise, between the upper
and lower limit of that range and any other stated or intervening
value in that stated range is encompassed within the invention. The
upper and lower limits of these smaller ranges may independently be
included in the smaller ranges is also encompassed within the
invention, subject to any specifically excluded limit in the stated
range. Where the stated range includes one or both of the limits,
ranges excluding either both of those included limits are also
included in the invention.
[0054] Expected variations or differences in the results are
contemplated in accordance with the objects and practices of the
present invention. It is intended, therefore, that the invention be
defined by the cope of the claims which follow and that such claims
be interpreted as broadly as is reasonable.
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