US 11,680,780 B2Granted

Pyrotechnic initiator device

AssigneeViettel Group

InventorsMinh Tuan Hoang, Manh Cuong Tran, Thanh Cong Le, Xuan Doan Dang, Tien Hoa Nguyen, Van Hoa Le

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Abstract

The invention proposes the design of a pyrotechnic initiator applied in the aerospace field, including three main components: the housing, the burning bridge and the pyrotechnic dose. The housing has a protective effect and increases the power of the pyrotechnic dose, in which the number of threads and the thread length are calculated to ensure to withstand the fire pressure. The burning bridge generates heat to ignite the ignition dose, the diameter of the bridge is calculated to ensure the resistance of the burning bridge. The pyrotechnic dose consists of 3 ingredient doses, which are the ignition dose, the intermediate dose, and the fire-boosting dose. In which, the mass, composition and density of the doses are calculated to ensure that the required working pressure is created.

A pyrotechnic initiator comprising:

a housing, a burning bridge and a pyrotechnic charge:
wherein the housing protects and increases power of the pyrotechnic charge, the housing is not reactive to the pyrotechnic charge, withstand the pressure of stuffing, and resistant to corrosion;
the housing is connected by a number of threads with other parts;
the housing comprising a stainless steel 09X16H4;
the number of threads is determined from tensile strength (nk) and shear strength (nc) by the formula:
n
k
=
P
·
d
k
k
·
s
·
[
σ
k
]
;
n
c
=
P
·
d
k
c
·
s
·
[
τ
]
in which:
σk, τ is a tensile and shear strength of the material, σk=6750 kG/cm2;
τ=5200 kG/cm2 with stainless steel 09X16H4;
where kk, kc each comprise a safety coefficient, when calculated by tensile strength kk=1.57;
by shear strength kc=2;
s is a pitch, s=0.15 cm;
d is a mean diameter of a thread, ˜2.1 cm;
P is an average pressure, P=693 kG/cm2, nk is a tensile strength, nc is a shear strength of the housing;
the number of the threads is:
n=1.5·nmax(nk;nc)+4
therefore, the number of the threads on the housing is 6;
thread length (lr):
lr=n·s
in which:
n—the number of the threads;
s—the pitch;
therefore:
lr=6 times 0.15=0.9≈1 cm;
the burning bridge generates heat to ignite the ignition charge, requiring a large resistivity and not being substantially changed when activated;
a diameter of the burning bridge is determined by the formula:
R
=
ρ
⁢
l
S
=
ρ
⁢
4
⁢
l
π
⁢
d
2
in which:
R—resistance of the pyrotechnic initiator, average value 0.9Ω;
ρ—the resistivity of the burning bridge;
l—length of the burning bridge 2.4.10−3 m;
d—diameter of the burning bridge;
an optimal calculated burning bridge diameter is 0.04 mm;
the pyrotechnic charge of the initiator includes:
ignition class:
oxidizing agent CuO2—60%;
ignition substance Zr—40%;
cotton binder powder based NO3—2%;
having a mass that is 0.12 g;
density 2.5 g/cm3;
intermediate class:
potassium perchlorate KClO4—50%;
lead rodanite Pb(CNS)2—47%;
barium chromate BaCrO4—3%;
NC glue (C24H31N9O38)—1%;
having a mass that is 0.25 g;
density 1.45 g/cm3;
fire-boosting class:
potassium perchlorate KClO4-64%;
aluminum powder—31%;
NC glue (C24H31N9O38)—5%;
having a mass that is 0.4 g;
density 1.23 g/cm3.

94 more elements

Abstract

Claims4