U.S. patent application number 13/102329 was filed with the patent office on 2012-07-26 for firing device for an initiator.
This patent application is currently assigned to INSTITUT FRANCO-ALLEMAND DE RECHERCHES DE SAINT-LOUIS. Invention is credited to Thomas Arnold, Henry Moulard, August Ritter.
Application Number | 20120186478 13/102329 |
Document ID | / |
Family ID | 43385765 |
Filed Date | 2012-07-26 |
United States Patent
Application |
20120186478 |
Kind Code |
A1 |
Ritter; August ; et
al. |
July 26, 2012 |
FIRING DEVICE FOR AN INITIATOR
Abstract
An initiator firing device has a firing member adapted to
generate heat for allowing the initiation of an energetic material
arranged in the initiator. The device also has an electrical switch
mounted in series with the firing member, the switch changing from
an open condition to a closed condition by application at its
terminals of a voltage higher than a predetermined cut-in
voltage.
Inventors: |
Ritter; August; (Village
Neuf, FR) ; Arnold; Thomas; (Sierentz, FR) ;
Moulard; Henry; (Saint-Louis La Chaussee, FR) |
Assignee: |
INSTITUT FRANCO-ALLEMAND DE
RECHERCHES DE SAINT-LOUIS
Saint-Louis Cedex
FR
|
Family ID: |
43385765 |
Appl. No.: |
13/102329 |
Filed: |
May 6, 2011 |
Current U.S.
Class: |
102/202.9 |
Current CPC
Class: |
F42B 3/121 20130101;
F42B 3/18 20130101; F42B 3/113 20130101 |
Class at
Publication: |
102/202.9 |
International
Class: |
F42D 1/05 20060101
F42D001/05 |
Foreign Application Data
Date |
Code |
Application Number |
May 10, 2010 |
FR |
10/53627 |
Claims
1. An initiator firing device comprising a firing member adapted to
generate heat to initiate an energetic material arranged in the
initiator, an electrical switch arranged in series with the firing
member and having states changing from an open state to a closed
state by application at terminals of a voltage larger than a
predetermined cut-in voltage, wherein the electrical switch
comprises at least one thyristor having a non-used trigger and a
breakover voltage corresponding to the predetermined cut-in
voltage.
2. The firing device according to claim 1, wherein the electrical
switch comprises a single thyristor.
3. The firing device according to claim 1, wherein the electrical
switch comprises a Triac.
4. The firing device according to claim 1, wherein the
predetermined cut-in voltage is higher than an alternating voltage
of 500 V.
5. The firing device according to claim 1, wherein the
predetermined cut-in voltage is lower than 1 000 V.
6. The firing device according to claim 1, wherein the firing
member comprises a laser diode.
7. The firing device according to claim 1, wherein the firing
member comprises a resistive element.
8. The firing device according to claim 7, wherein the resistive
element comprises a resistance.
9. The initiation device according to claim 7, wherein the
resistive element comprises a tantalum capacitator.
10. An initiation system of a pyrotechnic chain comprising: a
firing device which comprises a firing member adapted to generate
heat to initiate an energetic material arranged in the initiator,
an electrical switch arranged in series with the firing member and
switching from an open state to a closed sate by application at
terminals of a voltage higher than a predetermined cut-in voltage,
wherein the electrical switch comprises a thyristor having a
non-used trigger and a breakover voltage corresponding to the
predetermined cut-in voltage, and an initiator to which the firing
device is connected.
11. The initiation system according to claim 10, wherein the
initiator is an igniter.
12. The initiation system according to claim 10, wherein the
initiator is a detonator.
13. The initiation system according to claim 10, wherein the
electrical switch comprises a single thyristor.
14. The initiation system according to claim 10, wherein the
electrical switch comprises a Triac.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a firing device for firing
an initiator. Advantageously, the initiator, which is electrical,
will be a pyrotechnic initiator, a priori a controllable
pyrotechnic initiator. Typically, it can be an igniter or a
detonator. More particularly, the firing device will be of the type
allowing the ignition of the initiator by heat production, mainly
by Joule effect or by radiation.
BACKGROUND OF THE INVENTION
[0002] Is already known a projected-layer detonator that allows the
initiation of a secondary safety explosive induced by a primary
impact or initiation. In such a detonator, an electric conductor
produces plasma used for propelling at high velocity a small
projectile delivering the shock wave required for the initiation of
the secondary explosive. Such a detonator requires a voltage equal
to or higher than 2000 V and a voltage rise time lower than 1
.mu.s, which leads to the use of a complex power supply and a very
demanding low inductance connector technology.
[0003] This particularly high voltage allows the projected-layer
type to meet the STANAG 4560 safety standards, notably preventing
the initiator from reacting when an alternating current of 500 V
(with peaks of 710 V) is directly connected on its terminals,
otherwise the initiator shall mechanically interrupt the
pyrotechnic chain located downstream of the energetic material.
[0004] However, this particularly high voltage exhibits the
drawback of having a rather cumbersome firing device, therefore
limiting the use of the projected-layer detonators.
[0005] Furthermore, is also known an optical detonator wherein a
laser emitted by a laser source (preferably, a laser diode) ignites
a secondary explosive arranged in a first level that propels a
small projectile delivering the shock wave required for the
initiation of the secondary explosive of the second level.
[0006] Such a detonator has several advantages, particularly, that
of requiring very little energy (a laser diode requires less than 2
V and less than 1 A to emit light), of being compact (the laser
diode is less cumbersome than a low voltage converter/high voltage
converter), and of not being very sensitive to static electricity
(the optical fiber may be up to hundreds of meters long, the laser
diode may be integrated in the protected enclosure of the
computer).
[0007] Nevertheless, the "laser diode-fiber-opto-pyrotechnic
initiator" set is equated with an electrical initiator, for the
first time, in the third edition of the STANAG 4368 standard from
the fact that the laser diode is an electrical component.
Consequently, as 2 V are enough for initiating the laser diode,
such a detonator cannot remain insensitive to an alternating
voltage of 500 V and, so as to respect the aforementioned 4560
STANAG safety standard, it should exhibit an interruption of
optical line, upstream of the energetic material initiated by the
laser light.
[0008] Yet, an optical switch arranged on the optical fiber is
cumbersome, has additional cost and is unable to stand up to harsh
environments (mechanical and thermal) that some initiators
endure.
[0009] WO2008/112235 discloses the fact of protecting the heating
component of an initiator by an electrical component, swapping by
itself from an insulating state to a conducting state, and that is
only from a certain voltage at its terminals. Yet, this electrical
component does not act as a switch: the switch is added in series
to the protection component. FR 2408114 and FR 2866703 also refer
to the same type of protection as the one described above. In FR
2408114, various electronic components are concerned and wherein
the thyristor is used as a switch guided by its trigger. In FR
2866703, the component is called micro switch and acts as a
breakable insulator or a spark-gap.
[0010] Thus, an initiator firing device is already known, said
device comprising a firing member adapted to generate heat for
initiating an energetic material arranged in the initiator, an
electrical switch arranged in series with the firing member and
switchable between an open position to a closed position via
application, on its terminals, of a voltage higher than the
predetermined cut-in voltage.
[0011] However, this does not address the above mentioned
problem.
[0012] It should also be noted that in WO2008/112235, repeated
mention is made to TVS and not to thyristor. And yet, the TVS are
different components (made of avalanche diodes). Their breakover
voltages are very low in this case.
[0013] In addition, in the prior art documents, the thyristor was
only mentioned in its normal function of a switch controlled by its
trigger. It was not used outside its normal function and limits, in
contrast to the requirement of the invention.
SUMMARY OF THE INVENTION
[0014] The invention is intended to produce a firing device that
allows the initiator with which it is associated to be insensitive
to the alternating voltages of 500 V (and thus not requiring a line
interruption), while being compact.
[0015] A proposed solution provides in this respect that the
electrical switch comprises at least one thyristor having a
non-used trigger and a breakover voltage corresponding (i.e. equal)
to the predetermined cut-in voltage.
[0016] Thus, the switch itself will be the protection
component.
[0017] In the present solution, it is further recommended that the
firing member is a resistive element (for an electrical initiator)
or a laser diode (for an optical initiator).
[0018] In order to meet the STANAG 4560 safety standard, the
electrical switch is selected so as its predetermined cut-in
voltage is higher than 500 V (alternating voltage), which
corresponds to peaks of 710 V. Moreover, to guarantee compactness
and simple setting, the electrical switch is selected so as its
predetermined cut-in voltage is lower than 1 000 V.
DESCRIPTION OF THE FIGURES
[0019] Other features and advantages will appear more fully in the
following embodiments given only by way of non-limitative examples
and illustrated in the accompanying drawings, wherein:
[0020] FIG. 1 illustrates a diagram of a firing device of a first
embodiment, the device comprising, in series, a thyristor and a
diode, FIG. 1 showing also a diagram illustrating the voltage U and
the light output L according to the intensity I,
[0021] FIG. 2 illustrates a firing device of a second embodiment,
said device comprising, in series, a thyristor and a resistive
component, FIG. 2 showing also a diagram illustrating the voltage
according to the intensity I,
[0022] FIG. 3 illustrates the intensity crossing the firing device
of the first embodiment for an alternating current with 660 V
spikes;
[0023] FIG. 4 illustrates the intensity crossing the firing device
of the first embodiment following application of a voltage of 800
V;
[0024] FIG. 5 illustrates the intensity crossing the firing device
of the first embodiment following application of a voltage of 1000
V, and
[0025] FIGS. 6 and 7 represent each a diagram of a firing device of
another embodiment, said device comprising, in series, FIG. 6, a
triac and a diode and, FIG. 7, a triac and a resistive
component.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The invention relates to a firing device 1 allowing the
ignition of an electrical initiator. Such an initiator may be used
for firing actuators or propulsors.
[0027] Powder or explosive firing devices are involved.
[0028] The firing device 1 comprises a firing member 2, 3 adapted
to generate heat allowing the initiation of an energetic material
arranged in the initiator.
[0029] In the first embodiment, the firing member is a laser diode
2 that allows the generation of a laser light which, after
focalizing, allows igniting the energetic material enclosed in the
initiator.
[0030] As illustrated in FIG. 1, the laser diode 2 starts
conducting the electrical current from a voltage threshold (Udl
curve) and, from a minimal intensity crossing therethrough,
emitting a light the power of which is proportional to this
intensity (curve L).
[0031] In the second embodiment, the firing member is a resistive
element 3 (here, an electrical resistance 3) that generates, by
Joule effect, heat allowing igniting the energetic material
enclosed in the initiator.
[0032] As shown in FIG. 2, the intensity crossing the resistance 3
is proportional to the voltage at its terminals (curve Ur), and the
delivered power is proportional to the square of this
intensity.
[0033] The firing device 1 also comprises an electrical switch 4
mounted in series with the firing member 2, 3 and which switches
between an open state and a closed state by application of a
voltage higher than the predetermined cut-in voltage. More
particularly, the electrical switch 4 comprises (at least) a
thyristor 4 the trigger of which is not used, with a breakover
voltage equal to the predetermined cut-in voltage. In the
embodiments of FIGS. 1, and 2, the electrical switch 4 is a single
thyristor.
[0034] Typically, such a thyristor is intended for being used with
a voltage inferior to its breakover voltage and switching from its
open position to its closed position by application of an
electrical pulse on its trigger. In the present invention, the
trigger is not used, the characteristic of the thyristor utilized
is its switching from its open state to its closing state,
following application, between its cathode and its anode, of a
voltage higher than its breakover voltage (cf. Ut curve of FIGS. 1
and 2).
[0035] Thus, the firing device 1 of the present invention does not
conduct current when the predetermined cut-in voltage of the
electrical switch 4 is not reached (cf. FIGS. 3 and 4 wherein the
intensity crossing therethrough remains zero). When this
predetermined cut-in voltage is reached, the firing device 1 acts
as the firing member 2, 3 by itself with a voltage a bit higher
(cf. curves U of FIGS. 1 and 2).
[0036] FIG. 5 illustrates the behavior of a firing device 1
following the application of a voltage of 1 000 V at its terminals:
once the voltage reaches the breakover voltage of the electrical
switch function thyristor 4 (here, 900 V), an electrical current
crosses the device, which allows the ignition of the associated
initiator.
[0037] The electrical initiator 4 and the initiation member 2, 3
can be placed in the same casing so that they come together as one
component (with only two connections at the output of the
casing--the trigger being not used). The electrical switch 4 and
the heating component 2, 3 may be arranged side by side or fused
onto the same substrate.
[0038] The use of an electrical switch 4 the predetermined cut-in
voltage of which (the breakover voltage in the case of a thyristor)
is higher than the peaks of 710 V of an alternating voltage with
500 V allows to meet the STANAG 4560 safety standard, without
interruption of the line. Accordingly, such a firing device 1
allows having a highly reliable and a highly safe initiator, at the
level of functioning, handling and implementation. In addition, the
costs of electrical switches such as the thyristors or the triacs
are low, allowing for the production of very highly safe initiators
at a very low price compared to those that are currently on the
market.
[0039] Furthermore, the use of an electrical switch 4 the
predetermined cut-in voltage of which (the breakover voltage in the
case of a thyristor) is lower than 1 000 V allows to have a simple
implementation and therefore to miniaturize the firing device 1.
For example, it is possible to use such a device for the firing of
four impulsors onboard a 30 mm diameter projectile.
[0040] In addition, to have the smallest circuit possible, it is
favorable to select an electrical switch 4 the breakover voltage of
which is scarcely over that allowed under the regulations
(typically, starting from 800 V).
[0041] These initiators' firing devices are therefore of the utmost
safety while not being of high energy.
[0042] They enable the firing of detonators meeting the 4187 STANAG
standards and comprising only the secondary explosives which are
conform to the STANAG 4170 standards, as well as the firing of
igniters in line with the 4368 STANAG standards and charged with
safety pyrotechnic compositions. As a reminder, an igniter is a
trigger device that produces a deflagration (rapid combustion).
[0043] In the case of an optical initiator (igniter or detonator),
said initiator can be conform to one of the applications EP 1 067
356, EP 1 067 357, EP 1 306 643 and EP 1 742 009.
[0044] In the case of an electrical initiator, and more
particularly, in the case of a detonator, the resistive element 3
can also be any passive electrical component (resistor or
capacitator) or active (diode or transistor) enabling to transmit
its heat to the energetic material with a high efficiency. Joule
effect does not allow to make a secondary explosive to detonate, it
is therefore required to use a two-stage detonator with a
deflagration-detonation transition or a shock-detonation
transition. For reliability reasons, the shock-detonation
functioning is favored.
[0045] Thus, the resistive element can be a tantalum capacitator
having the advantages of being small, of being easy to operate, and
of having two impedance curves differing according to their
direction of use: this capacitator can be taken as a diac when it
is stressed directly as it has a negative resistance curve above a
certain limit, or to a direct diode when it is reverse stressed as
it has a positive resistance curve beyond a certain limit.
[0046] Consequently, in this invention, the initiator to which is
associated the firing device has the three following advantages: a
reliable functioning with less than 1 000 V (and hence a simple
implementation), a successful and unaltered resistance to
alternating current 500 V tests, and a use of insensitive active
materials.
[0047] Other embodiments are possible. Therefore, the electrical
switch can be a triac.
[0048] FIGS. 6, 7 incidentally illustrate such a triac (Triode for
Alternating Current)
[0049] FIGS. 6,7 correspond to the mountings in FIGS. 1,2,
respectively, except that the thyristor has been replaced by the
triac.
[0050] The triac is an electronic component equivalent to two
thyristors or Semiconductor Controlled Rectifier (SCR) mounted
anti-parallel to each other. A triac is sometimes referred to as a
bidirectional thyristor. It has the same characteristics as those
of the thyristor, and can be used here in the same way as the
thyristor, instead of said thyristor, provided that it has the same
breakover voltage value. It can even be considered more practical
in the case of a resistive element initiator, since it can be used
interchangeably in the two current flow directions and does not
require tracking.
[0051] What was afore presented in relation with the thyristor
operating method applies to the triac.
[0052] Thus, in FIGS. 6, 7, it can be found the firing device 1
comprising the firing member, respectively 2 et 3, adapted to
generate heat allowing the energetic material disposed within the
electrical initiator to be initiated. FIG. 6, the firing member is
the laser diode 2. FIG. 7, the firing member is the resistive
element 3. In both cases, the firing device 1 further comprises the
electrical switch 4 which presently comprises a Triac, and which is
disposed in series with the firing member 2, 3. This Triac switches
from an open state to a closed state by application at its
terminals of a voltage larger than a predetermined cut-in
voltage.
* * * * *