March 15, 1965
c. o. J. NORDZELL
3,173,364
AMMUNITION SAFETY DEVICE
Filed May 24, 1962
65
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INVENTOR
CARL OLOF JULIUS NORDZELL
BY
ATTORNEY
United States Patent Office
3,173,364‘
Patented Mar. 16, 1965
1
2
margin because unpacked shells normally detonate spon
3,173,364
taneously after ten to ?fteen minutes and shells having
AMMUNITION SAFETY DEVICE
wooden packing in about twenty to twenty-?ve minutes.
By detonation of top charge 5, a su?'iciently large open
Carl Olof Julius Nordzell, Lidingo, Sweden, assignor to
Military Training Device Company, Stockholm, Sweden,
ing will be formed to allow the main charge during con
a corporation of Sweden
tinued heating to burn Wholly or partly or to melt with
out detonating. Preferably, the parts 3 to 6 according to
the invention may form a unit which easily may be in
Filed Mar. 24, 1962, Ser. No. 197,420
4 Claims. (Cl. 102-1)
If a body charged with an explosive, such as a projectile
serted into the top opening 7 of the projectile. Said parts
the explosive of which is completely enclosed in a ?re 10 may for instance be housed in a sleeve 8.
resistant strong shell, is heated by ?re or in any other way
Instead of heating the detonating charge 4 by means
to a critical temperature the charge will detonate more or
of thermal conductivity of the closure 3 the latter may
less completely. An explosive such as T.N.T., having a
be provided with an igniting channel 9 having a melting
melting point of about 80° C., will, in melting, expand
seal 10 which melts at the critical temperature and leaves
about 10%. If the explosive is completely enclosed in a 15 the channel open thereby causing the detonating charge to
cover that will not burst or open itself in another way, a
be directly exposed to the high outer temperature or to
more or less complete detonation will occur. It has been
a flame from a ?re or the like. In this case the detonat
observed that molten T.N.T. will be forced out through
ing charge 4 may comprise a low explosive, the melting
screw holes and be ignited. This will usually occur some
point of which does not need to be higher than that of
minutes before the detonation. The pressure is here 20 the main charge.
estimated to be about 1,000 kilograms per square centi
The invention may be embodied in other speci?c forms
meter.
without departing from the spirit or essential character
If on the other hand the shell is provided with a su?‘i
istics thereof. The present embodiment is therefore to be
ciently large “venting” opening the charge may wholly or
considered in all respects as illustrative and not restric
partly burn or melt out of the shell without detonating. 25 tive, the scope of the invention being indicated by the
Such a venting opening may be provided by removing the
appended claims rather than by the foregoing description,
closure (detonating fuze, detonator closing cover or the
and all changes which come Within the meaning and
like) or by providing a burnable or meltable closure. For
range of equivalency of the claims are therefore intended
storage purposes or in military emergencies, said measure
to be embraced therein.
may be less desirable, or the venting opening thus pro 30
What is claimed and desired to be secured by United
vided may be too small.
States Letters Patent is:
The main object of the present invention is to be ap
1. In combination with a shell ?lled with a high ex
plied in such latter cases. According to the invention a
plosive main charge, a safety device for preventing unin
protective explosive charge which can be ignited under
tended, heat induced detonation of the explosive main
the influence of heat is arranged close to the shell or to
charge, comprising:
a closed opening thereof in such a way that said protec
(a) a protective explosive charge in said shell, said
tive charge at the igniting temperature is caused to burst
charge being large enough that its detonation will
or to blast up part of said shell or open said closure re
spectively without causing the main charge to detonate or
in any case to detonate incompletely only and thus with 40
a sufficiently reduced effect.
One embodiment of the invention as illustrated in con
nection with a projectile is shown diagrammatically in a
longitudinal section in the accompanying drawing.
The shell 1 of the projectile contains a main charge 2 45
with detonator 2a arranged adjacent the top of the pro
jectile said top being closed by a closure 3 which may be
provided with a handle, and is made of a material having
a good thermal conductivity or being provided with an
“igniting channel.” A detonating charge 4 arranged in
plosive of the top charge may have a higher melting point 55
than the main charge. Further, a protective body 6 of a
suitable material such as wood, plastic, cork, metal or
the like is provided to prevent or obstruct the detona
tion wave from the top charge 5 from being transmitted
60
to the detonator 2a and the main charge 2.
When the projectile is exposed to heat, for instance
through ?re the detonating charge 4 will be ignited caus
ing the top charge 5 to detonate thereby opening the top
of the projectile or causing the shell 1 to burst before the
main charge 2 is detonated. The release time is usually 65
one to four minutes from the beginning of a heavy ?re,
but may be as much as eight minutes in one practical
the shell without high order detonation; and
(b) means responsive to the heating of said shell and
operable at a temperature below the detonation tem
perature of the main charge for detonating the pro
tective charge and thereby creating said venting
opening in said shell.
2. The combination as de?ned in claim 1, wherein:
(a) said shell has a normally sealed opening at one
end thereof; and
50
the closure is provided with a temperature sensitive igniter
and with an explosive having a higher melting point than
said main charge. A protective or top charge 5 is inserted
close to the detonating charge 4, and preferably the ex
embodiment tested. This provides an adequate safety
create a venting opening in said shell of suf?cient
size to allow the main charge to burn or ?ow out of
(b) the protective explosive charge is located adjacent
said Opening.
3. The combination as de?ned in claim 1, wherein
said protective charge detonating means is in thermal
contact with said shell.
4. The combination as de?ned in claim 1:
(a) wherein said shell has an opening at one end there
of; and
(b) said safety device includes a closure for said open
ing, means forming a protective charge ignition
channel in said opening, and a seal in said channel
of a normally solid material having a melting point
lower than the detonation temperature of the main
charge in said shell.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,943,445
3,054,349
Ritterskamp et a1. ______ __ July 5, 1960
Plumley _____________ __ Sept. 18, 1962