U.S. patent number 3,748,770 [Application Number 05/131,404] was granted by the patent office on 1973-07-31 for ammunition high voltage electrical ignition system.
Invention is credited to James W. Mitchell.
United States Patent |
3,748,770 |
Mitchell |
July 31, 1973 |
AMMUNITION HIGH VOLTAGE ELECTRICAL IGNITION SYSTEM
Abstract
An electrical ignition system for ammunition that utilizes two
fixed electrical contacts in the bolt face; and a primer having an
electrically conductive priming mix, and a consumable dielectric
disc having two annular consumable conductors therethrough, the gap
between the two conductors being significantly greater than twice
any gap between the bolt face and the disc, the ignition system
being completed and energized by a high voltage power source of
sufficient voltage to overcome any air gap between the cartridge
and the bolt face.
Inventors: |
Mitchell; James W.
(Philadelphia, PA) |
Family
ID: |
26829433 |
Appl.
No.: |
05/131,404 |
Filed: |
April 5, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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863076 |
Oct 2, 1969 |
3608492 |
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Current U.S.
Class: |
42/84;
89/28.05 |
Current CPC
Class: |
F41A
19/58 (20130101); F42B 5/08 (20130101) |
Current International
Class: |
F42B
5/08 (20060101); F42B 5/00 (20060101); F41A
19/58 (20060101); F41A 19/00 (20060101); F41c
019/12 () |
Field of
Search: |
;102/38,46,464
;42/14,84 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Jordan; C. T.
Parent Case Text
RELATED PATENT
This is a division of application Ser. No. 863,076, filed Oct. 2,
1969, now U.S. Pat. No. 3,608,492.
Claims
What is claimed is:
1. A gun comprising:
a barrel having a chamber in the aft end thereof;
a bolt having a face for obturating the aft end of said
chamber,
said bolt face having first and second electrical conductors
disposed therein, insulated from each other;
a source of high voltage current coupled to and between said
conductors;
a round of ammunition disposed in said chamber,
said round having
an aft face having third and fourth electrical conductors disposed
therein, insulated from each other,
a primer having an electrically conductive priming mixture coupled
to and between said third and forth electrical conductors;
said bolt face and said first and second conductors being spaced
from said round aft face and said third and fourth conductors and
defining an air gap therebetween;
the electrical impedance of the series circuit including said first
conductor, said air gap, said third conductor, said electrically
conductive primer mixture, said fourth conductor, said air gap, and
said second conductor being less than the electrical impedance of
the series circuit including said first conductor, said air gap and
said second conductor.
2. A gun according to claim 1 wherein:
said second electrical conductor, as exposed at said bolt face, is
annular in shape and concentric with and about said first
electrical conductor.
3. A gun according to claim 2 wherein:
said fourth electrical conductor, as exposed at said round aft
face, is annular in shape and concentric with and about said third
electrical conductor.
4. A gun according to claim 1 wherein:
said round of ammunition is consumable and comprises
a main charge made of moulded propellant;
a booster charge disposed in said main charge and made of booster
powder;
said primer communicates with said booster charge and includes
an outer tubular casing of consumable material,
a forward closure of consumable material,
an aft closure disk,
said electrically conductive priming mixture is disposed within
said casing between said forward closure and said aft disk;
said disk is made of consumable insulative material and has said
third and fourth electrical conductors made of consumable material,
transversely spaced apart, and extending longitudinally through
said disk.
5. A gun according to claim 4 wherein:
said primer is disposed in said round with the aft face of said
disk spaced forwardly from said aft face of said round; and further
including
fifth and sixth consumable conductors disposed in said round and
respectively extending between said third conductor and said round
aft face and said fourth conductor and said round aft face.
Description
BACKGROUND OF THE INVENTION
1. Field of Art
This invention relates to the ignition of ammunition, and is
especially adapted to combustible caseless ammunition.
2. Prior Art
Modern firearms conventionally have utilized a movable firing pin
in the bolt to actuate the igniter of the round of ammunition. In a
firearm utilizing cased ammunition, the case has served to seal the
aft end of the chamber to prevent the flow of combustion gas to the
face of the bolt. In the case of a percussion actuated igniter,
movement of the firing pin relative to the bolt is required to
percuss the igniter. Similarly, in the case of an electrically
actuated igniter, movement of the firing pin relative to the bolt
is required to insure a good electrical connection between the pin
and igniter contact. In each case the firing pin is disposed for
movement in a passageway, and this passageway must be sealed from
the combustion gases. In caseless ammunition, obviously, a case is
not available for this function.
In U.S. Pat. No. 3,114,290, issued Dec. 17, 1963, E. M. Harvey et
al proposed a dished cup, similar to a Belleville washer, having a
central protuberance, which would seal the aft end of the chamber,
around the aft end of the caseless round, and which would be
snapped forward by a firing pin, to percuss the igniter. In U.S.
Pat. No. 3,354,780 issued Nov. 28, 1967, M. Ramsey proposed a true
Belleville washer to seal the aft end of the chamber to the face of
the bolt, and a protuberance integral from the bolt face passing
through the center hole of the washer, to percuss the igniter.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a system for the
ignition of caseless ammunition which obviates moving pins and
firing pin seals, and that accommodates dimensional tolerances
between the round of ammunition, the chamber and the bolt face of
the gun.
The advantages of this invention are: (1) the provision of a
combustible electric primer for electric ignition in caseless
ammunition systems; (2) the elimination of moving parts in the gun
bolt, providing a sealed, flush bolt face; (3) the accommodation to
a variable gap between the round and the bolt by use of a high
voltage current source; and (4) the adaptability to multiple
ignition systems with increased reliability of ammunition
performance.
A feature of this invention is an electrical ignition system
utilizing two electrical contacts in the bolt face; and a primer
having an electrically conductive priming mix, and a consumable
dielectric disc having two annular consumable conductors
therethrough, the gap or effective impedance between the two
conductors being significantly greater than twice any gap between
the bolt face and the disc.
BRIEF DESCRIPTION OF THE DRAWING
These and other objects, features, and advantages of this invention
will be apparent from the following specification thereof taken in
conjunction with the accompanying drawing in which:
FIG. 1 is a partial view, in side elevation, in cross-section of an
ignition system embodying this invention;
FIG. 2A is a view in side elevation in cross-section of the igniter
of FIG. 1;
FIG. 2B is a view in end elevation of the primer of FIG. 2A;
and
FIG. 3 is a view in side elevation of another embodiment of a
primer embodying this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In FIG. 1, the forward end of a bolt 10 is seated against the aft
face of the barrel extension 12 to close the chamber 14. A seal 16
may be disposed between the barrel extension and the bolt.
A caseless round 18 of ammunition is disposed in the chamber, and
the aft end of the round, due to dimensional tolerance, is spaced
from the bolt face 20 by a gap 22. The aft end of the round is
shown in the chamber and includes a main charge 24 of molded
propellant, a booster charge 26 of booster powder disposed in an
aft recess in the main charge and captured by a plug 27 of molded
propellant, and a primer 28 disposed in an aft recess in the plug.
On ignition, the primer communicates its flame and heat via a bore
29 in the plug in the powder of the booster charge, and to the
propellant gains of the main charge and the plug.
The bolt 10 includes a central insulator 30 which may be made of a
hard ceramic, a central electrode 31 which is disposed along the
longitudinal axis of the insulator, and an annular ground electrode
32 which is spaced from the central electrode by the insulator. The
two electrodes and the insulator are ground flush with the bolt
face.
The primer 28 may be composed of any suitable materials that are
completely consumable during the interval of the combustion of the
round in the chamber and the barrel, a matter of three to ten or
more milliseconds. They may be moulded, extruded, or cut from
colloided nitrocellulose of any typical propellant composition.
Other self oxidizing consumable plastics that on combustion yield
largely gaseous products are equally suitable, including composite
materials compounded of separate fuel and oxidizers, such as some
rocket propellants and some artillery gun propellants.
The primer 28 includes an outer tubular casing 33, an inner,
forward, closure annulus 34, an electrically conductive priming
mixture 35, which may be tableted, or if loose, then retained by a
thin, forward, consumable disk and an outer aft closure disk 36.
The disk 36 is made of consumable insulative material 38 such as
nitrocellulose and has an annular, longitudinal portion 40 and a
central, longitudinal portion 42 of electrically conductive
material. The transverse cross-sections of the electrically
conductive portions 40 and 42 are substantially congruent with the
bolt face sections of the bolt electrodes 32 and 31 respectively.
The conductive portions 40 and 42 may be composed of nitrocellulose
mixed with 40 to 60 percent powdered graphite. Other conductive
materials may be used such as acetylene black or other forms of
amorphous carbon, powdered copper or silver, although carbon has
the advantage of being largely consumed or reduced to carbon
dioxide/monoxide when the nitrocellulose base material burns.
The bolt electrodes 31 and 32 are axially aligned with the primer
disk electrically conductive portions 42 and 40 and serve as the
conductive path for a high voltage current from a power supply, 44,
which is coupled through the bolt electrodes, to the electrically
conductive primer mix. The radial distance between the primer disk
electrically conductive portions 42 and 40, and between the bolt
electrodes, is arranged to be sufficiently greater than twice the
maximum air gap that may obtain between the bolt face and the
primer disk so that arcing from the bolt electrodes to the primer
disk electrically conductive portions will occur with high
reliability and will result in igniting the primer mix at the
selected firing voltage, without any possibility of arcing between
the bolt electrodes. The high voltage current source may be a
capacitance circuit delivering a pulse of the order of 1 to
5Kv.
It will be appreciated that the invention can be applied to any
type of electrically fired weapon, but is particularly suited to
caseless ammunition wherein (1) the ground connection to the gun is
not provided by a metallic case, and (2) the ammunition to weapon
tolerances are large. Most importantly, the invention permits a
complete sealing of the bolt face to provide an unbroken surface
which obviates the conventional requirement for pressure seals
around the moving parts of a conventional firing pin.
An additional advantage of the invention is illustrated in FIG. 3.
The combustible electric primer may be located elsewhere than on
the outer aft surface of the round. The firing current may be
conducted from the bolt electrodes through short lengths of wire or
metallic inserts 50 imbedded in through the combustible propellant
bodies. These metallic inserts need not establish conventionally
good electrical contacts, insolong as any gaps are small, and an
efficient circuit path is provided which will avoid large power
losses. Short lengths of aluminum, magnesium or other pyrophoric
wire may be used as conductors, and will be consumed in the
combustion of the propellant, at most leaving a powdered residue.
This advantage permits retention of a closed surface over the aft
end of the round during the ignition and burning of the booster
charge, thereby aiding this process by added confinement. Further a
plurality of primers may be provided which are spaced from each
other but electrically connected to the power supply by an
efficient independent circuit and thus significantly increase the
ignition reliability of the round.
* * * * *