EP1589316A1 - Irreversible snap action temperature detector and application of such a detector and use of such a detector for the deconfinement of ammunition - Google Patents

Abstract

The detector has a material (10) releasing a cylindrical rod (12) from its initial position when the temperature of the material reaches a preset value. The material is retained in a support (11) that is external to a case (2). The support is integrated with the case. The support has openings permitting the material to be in direct contact with the ambient temperature, where the material works in compression. An independent claim is also included for a system including a pyrotechnic deconfinement device having a detector.

Description

The present invention relates to a temperature detector to sudden and irreversible action. It applies in particular to a device for deconfinement to avoid the explosion of a charge confined in an enclosure (thruster or explosive charge of a munition) in the presence fire.

Under the influence of an external fire, ammunition presents a danger of violent reaction. The explosive charge of a munition or the pyrotechnic loading of a propellant may explode under the effect of external heat. Added to this danger is that of chain reaction when several ammunition are stored in a storage room.

In order to limit the level of reaction of ammunition, and therefore the associated hazard, deconfusion devices are used. The decontamination of ammunition thus makes it possible to protect individuals and goods in the vicinity of an ammunition storage airborne, naval), to protect the premises itself, and to avoid in chains.

A deconfining device generally includes a temperature detector, this detector being of mechanical type or electronic. The detector allows when the surrounding temperature exceeds a certain threshold to open the enclosure in which is confined a explosive charge. The opening of the enclosure avoids the explosion of the charge by allowing it to ignite before any pressure buildup. The firing of a charge is indeed a lower risk compared to its explosion, because the fire can be controlled by specialized teams to land or at sea in the fight against fire.

However, the known deconfining devices use a Autonomous power source (electric) to detect temperature surrounding. Ammunition can be stored for long periods of time periods of the order of several decades. This poses a problem because the sources of energy are not reliable over such long periods.

An object of the invention is to obtain a detector that can be used in a deconfinement device and having reliable operation on a long period of time.

Such a detector can be used more generally for trigger from a given temperature an instant action and irreversible to treat an accidental event.

• un premier mécanisme mobile précontraint dans une position initiale,
• un premier matériau sensible à la température, agencé pour maintenir le premier mécanisme mobile dans sa position initiale, et configuré pour libérer le premier mécanisme de sa position initiale lorsque la température du premier matériau atteint une première valeur 1.

For this purpose, the invention relates to a detector with sudden and irreversible action, comprising at least:

• a first mobile mechanism prestressed in an initial position,
• a first temperature sensitive material arranged to hold the first movable mechanism in its initial position and configured to release the first mechanism from its initial position when the temperature of the first material reaches a first value 1.

Thus, the detector using no energy source other than the prestressing of a mechanical part, its operation is reliable on a long period of time. It also has the advantage of being simple to implement and economic.

According to an advantageous embodiment, the operation of the detector can be made more reliable by detecting two levels of different temperatures.

• un second mécanisme mobile précontraint dans une position initiale;
• un second matériau sensible à la température, agencé pour maintenir le second mécanisme dans sa position initiale, et configuré pour libérer le second mécanisme de sa position initiale lorsque la température du second matériau atteint une seconde valeur 2, la seconde valeur 2 étant supérieure à la première valeur 1, le premier et le second mécanisme étant agencés de manière à produire l'action brusque du détecteur uniquement lorsque le premier et le second mécanisme sont tous les deux libérés.

The detector according to this advantageous embodiment further comprises:

• a second mobile mechanism prestressed in an initial position;
• a second temperature sensitive material arranged to maintain the second mechanism in its initial position and configured to release the second mechanism from its initial position when the temperature of the second material reaches a second value 2, the second value 2 being greater at the first value 1, the first and second mechanisms being arranged to produce the sharp action of the detector only when the first and second mechanisms are both released.

According to an advantageous embodiment, making it possible to generate a large amplitude action, the sudden action of the detector is the activation of a pyrotechnic charge. The pyrotechnic charge can be a detonator or an igniter.

According to an advantageous embodiment, the second mechanism includes a striker configured to activate the pyrotechnic charge when the release of the second mechanism if the first mechanism has been released.

According to an advantageous embodiment, the detector comprises in addition a barrel arranged in a first position when the first mechanism is in its initial position, the barrel being configured to prevent the firing pin from activating the pyrotechnic charge when the barrel is in its first position, the barrel being articulated in rotation to be in a second position when the first mechanism is released, the barrel being configured to allow the firing pin to activate the load pyrotechnic when the barrel is in its second position.

According to an advantageous embodiment, the first mechanism includes a lock arranged to hold the barrel in its first position as long as the first mechanism is in its initial position, the barrel being prestressed in its first position so as to turn towards its second position under the effect of said prestressing when the first mechanism is released.

The invention also relates to a deconfinement device pyrotechnic device comprising at least one detector whose sudden action is the activation of a detonator, and a pyrotechnic cutting chain, in which the detector is arranged so that activation of the detonator initiates the pyrotechnic cutting chain.

According to an advantageous embodiment, the cutting line pyrotechnic is a chopper cord, a pyrotechnic hammer or a thermite type composition.

The invention applies to a system comprising a device for deconfinement, an enclosure and an explosive charge placed in the enclosure, the cutting chain being arranged to weaken or cut the enclosure.

According to an advantageous embodiment, the system comprises in addition an inhibition device presenting a command, the command being able to receive an external command, the muting device being configured to neutralize the deconfinement device when an external order is received by the order

• la figure 1, un exemple de réalisation d'un détecteur selon l'invention,
• la figure 2a, un détail du détecteur représenté sur la figure 1 montrant les pièces sensibles à la température,
• la figure 2b, une variante de réalisation dans laquelle les pièces sensibles à la température sont intégrées dans le boítier du détecteur,
• la figure 3, un détail montrant un mode de réalisation avantageux dans lequel le premier mécanisme est un barillet articulé en rotation,
• la figure 4, une vue en coupe du détecteur dans une première position,
• la figure 5, le détecteur équipé d'accessoires complémentaires,
• les figures 6 et 7, un dispositif de déconfinement d'une enceinte contenant un matériau explosible,
• les figures 8a et 8b, une section de deux exemples de réalisation d'une chaíne de découpe pyrotechnique.

Other features and advantages of the invention will become apparent on reading the following detailed description given by way of non-limiting illustration and with reference to the appended figures, which represent:

• FIG. 1, an exemplary embodiment of a detector according to the invention,
• FIG. 2a, a detail of the detector represented in FIG. 1, showing the parts sensitive to temperature,
• FIG. 2b, an alternative embodiment in which the temperature-sensitive parts are integrated into the housing of the detector,
• FIG. 3, a detail showing an advantageous embodiment in which the first mechanism is a cylinder articulated in rotation,
• FIG. 4, a sectional view of the detector in a first position,
• FIG. 5, the detector equipped with complementary accessories,
• FIGS. 6 and 7, a device for deconfining an enclosure containing an explosive material,
• Figures 8a and 8b, a section of two embodiments of a pyrotechnic cutting chain.

Referring now to FIGS. 1 and 2a on which is represented an example embodiment of a temperature detector according to the invention. The detection of the temperature is carried out by means of at least a material sensitive to temperature, responding to a temperature determined. This material can for example change state or shape to this determined temperature. For example, the material used may be a eutectic material, ie a material that passes directly from the state solid in the liquid state. This avoids the use of temperature probes or electronic detection system that require electrical energy stored.

The detector thus comprises a first material sensitive to temperature. The first material 10 has, for example, a shape substantially cylindrical. The first material 10 is retained in a support 11 secured to the housing 2 of the detector 1.

In the embodiment shown in FIGS. 1 and 2a, the support is external to the housing and has openings. This arrangement external allows the material 10 to be in direct contact with the temperature external. The support comprises disks 11a traversed by the first material 10, these discs being interconnected by wings 11b.

As shown in Figure 1, the material 10 is also attached to a cylindrical rod 12. In the initial position (called still rest position), shown in Figure 1, the rod is prestressed by a spring 13 tending to push the rod 12 against the material 10. The support 11 and holds the material 10 which works in compression.
When the temperature of the material 10 reaches a determined value 1, it passes from the solid state to the liquid state without transition (melting) under the effect of heat. The material then flows and releases the rod 12. The rod 12 then moves under the effect of the spring 13 towards the outside of the housing.

Thus, a sudden mechanical action is generated during the transition to the determined temperature 1, this mechanical action and the detection itself requiring no power source of the electric type.

FIGS. 1 and 2a illustrate a particular embodiment of the detector according to the invention which constitutes a preferred embodiment. Indeed as has been said previously, this embodiment several advantages.

On the one hand, because of the positioning of the material 10 on the outside housing and the structure of the support 11, it allows the material 10 to be in direct contact with the ambient temperature.

On the other hand, the structure of the support 11 allows an evacuation fast and complete material 10 when the latter undergoes a deformation of makes heat. This last advantage being particularly obtained in the case of a eutectic material.

On the other hand, because of the compression operation of the material 10, the release of the prestressing applied to the movable rod 12, during the change of shape of the material 10, is accelerated.

Of course, the detector according to the invention may nevertheless have features of structures different from those illustrated in FIGS. 2a. In particular, the detector components may have different forms. For example, the support 11 can be replaced by a tubular shaped support perforated with multiple through holes, wherein the material 10 is held in position (tight), in direct contact with the external temperature.

It is also possible to replace the eutectic material of other temperature sensitive materials. For example, an alloy can be used shape memory that fades at a specific temperature. We can also use a gas. This gas can be enclosed in an aneroid capsule (such as in altimeters), the expansion of the gas causing a movement translation of a rod.

Moreover, the detector components can be arranged differently. For example, as illustrated in FIG. 2b, the support 11 can be placed inside the housing instead of being external. The material 10 will then be in contact with the internal temperature of the housing.

Military standards require two events to be detected independent devices to operate a security and boot device ("safe and arming device" in the Anglo-Saxon literature). The detector can be improved to meet this requirement, a requirement which makes its operation more reliable.

For this purpose, as shown in FIGS. 2a and 2b, the detector can further include a second temperature sensitive material. The second material 20 has a substantially cylindrical shape. This material 20 forms a calibrated pin working in shear, the pin being retained by a support 21 secured to the housing 2. In this mode of realization, the support 21 and the pin 21 are placed outside the housing, which allows the material forming the pin 21 to be in direct contact with the external temperature.

Of course, as indicated above, the components of the detector may have a different shape or be arranged differently, as shown in particular in Figure 2b.

The pin passes through a cylindrical rod 22. When the rod 22 is in its initial position (or rest position), it is prestressed by a spring 23 tending to move the rod to the inside of the housing.

When the temperature of the material 20 reaches a value determined 2, this value being greater than the value 1, the material passes from the solid state to the liquid state without transition under the effect of heat. The material flows releasing the rod 22. The rod 22 moves under the effect of spring 23 towards the inside of the housing.

Thus, when the temperature increases, one releases successively and in a predetermined order two prestressed moving mechanisms. The movement of each mechanism transmits an order. In this mode of advantageous embodiment, the two mechanisms are arranged to produce the abrupt action of the detector only when they are both released.

According to an advantageous embodiment, the abrupt action of the detector can be an activation of a pyrotechnic charge. Load pyrotechnic may be a detonator or an igniter. This allows quickly dispose of significant energy from an energy medium or weak mechanics (prestressed springs). Thus, the detector can be used in applications (military or civilian) where it is necessary to have a significant energy when the temperature reaches a certain threshold.

For example, a detector according to this last embodiment advantageous can be useful to activate a hydraulic valve or another mechanism requiring significant energy. It will be understood that advantageous embodiments previously described (detection of two independent events and activation of a pyrotechnic charge) are independent and can be implemented separately.

An embodiment is now described in which the two advantageous embodiments are implemented simultaneously. When the abrupt action of the detector is the activation of a detonator, the second mechanism, released second, is the one that activates the detonator. The first mechanism inhibits or allows activation of the detonator by the second mechanism. In other words, the second mechanism includes a striker configured to activate the pyrotechnic charge when the release of the second mechanism if the first mechanism has been released.

In the embodiment shown, the striker is formed by the rod 22, a tip end is intended to hit the load pyrotechnic when the pin 20 releases the second mechanism. However, if the first mechanism was not released, it impedes the percussion of the tip the pyrotechnic charge.

Different solutions can be envisaged to allow both mechanisms to interact in order to produce the abrupt action of the detector only when both mechanisms are released. If we adopts a fully mechanical solution, the first mechanism can to align a pyrotechnic chain when it is released, this chain pyrotechnic can then be activated by the second mechanism. By for example, the first mechanism can act in translation (sliding drawer) to cause the alignment, the pyrotechnic chain being misaligned when the first mechanism is in its initial position.

Reference is now made to Figures 1, 3 and 4. According to a advantageous realization, the interaction between the two mechanisms is realized by means of a barrel 30 articulated in rotation. The barrel can take two positions.

The first position of the cylinder is shown in Figure 4. The barrel is in this first position when the first mechanism is in its initial position. In this first position, the barrel prevents the striker 22 to activate the pyrotechnic charge.

The second position of the cylinder is shown in FIG. barrel is in this second position when the first mechanism is released. In this second position, the barrel allows the firing pin 22 to activate the pyrotechnic charge.

The pyrotechnic charge 31 forms the first element (initiator) of a pyrotechnic chain 31, 32. The load 31 can be placed in the barrel itself, as shown in Figure 3. According to another mode of realization (not shown), the load is placed outside the barrel, the barrel being placed between the firing pin and the load, the barrel having a opening allowing the firing pin to reach the load when the barrel is in the second position.

Thus, the passage of the barrel from the first to the second position allows to align the striker with the load 31. In a more general, the inhibition of the striker's action is caused by the misalignment of an element of the pyrotechnic chain 31, 32. The misalignment is produced by the barrel when it is in the first position.

The rotation of the barrel is actuated by the first mechanism. We can consider several mechanical solutions to transform the translational movement of the rod 12 in rotational movement of the barrel 30, for example by means of a rack and pinion system.

However in a rack and pinion system, it is necessary to have a large stroke of the rod 12 to rotate an angle sufficient. If the detector must have a small footprint, such a system is not possible.

Referring to Figure 1. According to one embodiment advantageous, to reduce the size of the detector, the barrel is held in its first position by a latch 14, the barrel being prestressed in its first position so as to turn towards its second position under the effect of said prestressing when the lock is erased. By elsewhere, the lock is an integral part of the first mechanism, so that fade when the first mechanism is released. In the example of embodiment shown, the latch 14 is placed at one end of the rod 12.

Referring now to FIGS. 6 and 7, which is illustrated an example of application of a detector according to the invention to a pyrotechnic deconfining device. The deconfinement device comprises a pyrotechnic cutting chain 41 pressed against the wall an enclosure 40. The enclosure contains an explosive charge 43. detector whose action is the activation of a detonator 31. The detonator 31 is arranged to initiate the pyrotechnic cutting chain. The chain of cut 41 as for it is arranged to weaken or cut the enclosure 40.

If the detector is moved away from the cutting line, add a pyrotechnic transmission line 42 so as to transmit the action of the detector at the cutting line.

Referring to FIG. 8a, on which is represented a section of an exemplary embodiment of a pyrotechnic cutting line 41 of the cutter cord type. A chopper cord is a charge linear with dihedral effect (same effect as hollow charges). The cord chopper comprises an envelope 50 made of material to be sprayed. Several materials are suitable for making the envelope. We use conventionally a material based on lead or silver. The envelope contains an explosive 51. Hexogen (known under the acronym RDX in the Anglo-Saxon literature) or hexa-nitro-stilbene (HNS). We know, for example, RDX-Pb type cords or still of HNS-Ag type. The whole of the envelope 50 and the explosive 51 can itself be contained in a thermal protection device or more simply in a maintenance mechanics.

Referring to FIG. 9a, which shows a mode of alternative embodiment of a pyrotechnic cutting line. The chain of cutout shown in this figure is of the pyrotechnic hammer type.

A pyrotechnic hammer comprises a chamber 52 that can also provide thermal protection. The enclosure has substantially a shape U shaped, forming a cavity in which is placed an explosive 53. By elsewhere, the enclosure contains a blade 54 for closing the cavity. The blade 54 is disposed facing the enclosure 40 to be cut, with care an empty space 55 between the blade 54 and the enclosure 40. The detonation of the explosive 53 projects the blade. The impact of the blade generates a shock wave on the structure of the enclosure to be cut. The shock is capable of generating a crack that will spread.

Of course, other solutions can be used to make a pyrotechnic cutting line. For example, we can cite the use of a thermite type composition (not shown). Such a composition is well known to those skilled in the art.

Referring now to Figure 5 in which are shown complementary accessories. Other barriers may be added or temperature-sensitive elements 61 so as to enhance the states of security (multiple levels of inhibition) or detection. These accessories can be inserted in the pyrotechnic chain misaligned detector. The action of these accessories can be of mechanical or electronic origin.

According to an advantageous embodiment, it is possible to add a device of inhibition to the deconfinement device, to inhibit the system when firing the missile. Indeed, the free flight temperatures of the missile (kinetic heating of about 500 ° C) are close to those reached during a fuel fire. The inhibition can be achieved by a drawer 60 making part of the detector. The action of the multi-level detector can be inhibited. For example, one can add electromechanical actuators 62 allowing to block the movement of the barrel by engaging a lug.

The inhibition device presents a command, the command being able to receive an external order. The muting device is configured to neutralize the deconfinement device when an external order is received by the order. In the example presented, the inhibition device integral part of the detector and directly inhibits the action of the detector.

Claims (12)

Snap-action and irreversible detector, comprising at least: a housing (2) enclosing a first movable mechanism (12, 13) preloaded in an initial position a first temperature sensitive material (10) arranged to hold the first movable mechanism in its initial position and configured to release the first mechanism from its initial position when the temperature of the first material reaches a first value 1, characterized in that the first material 10 is retained in a support (11) outside the housing (2) and integral with said housing, said support (11) having openings allowing the material 10 to be in direct contact with the ambient temperature, said material (10) working in compression. The detector of claim 1 further comprising: a second movable mechanism (22, 23) preloaded in an initial position; a second temperature sensitive material arranged to maintain the second mechanism in its initial position and configured to release the second mechanism from its initial position when the temperature of the second material reaches a second value 2, the second value 2 being greater at the first value 1, the first and second mechanisms being arranged to produce the sharp action of the detector only when the first and second mechanisms are both released. Detector according to claims 1 and 2 wherein the first material 10 has a substantially cylindrical shape, the support (11) consisting of the discs (11a) traversed by the first material 10, these discs being interconnected by wings (11b). Detector according to claims 1 and 2 wherein the first material 10 has a substantially cylindrical shape, the support (11) having the shape of a perforated tube with multiple through holes, wherein the first material (10) is retained. Detector according to any one of the preceding claims, in which the sudden action of the detector is the activation of a load pyrotechnic. Detector according to claim 5 wherein the second mechanism includes a striker configured to activate the pyrotechnic charge during the release of the second mechanism if the first mechanism has been released. Detector according to claim 6 further comprising a barrel arranged in a first position when the first mechanism is in its initial position, the barrel being configured to prevent the striker to activate the pyrotechnic charge when the barrel is in its first position, the barrel being articulated in rotation to be in a second position when the first mechanism is released, the barrel being configured to allow the firing pin to activate the load pyrotechnic when the barrel is in its second position. Detector according to claim 7 wherein the first mechanism comprises a latch (14) arranged to hold the barrel (30) in his first position as long as the first mechanism is in his initial position, the barrel being prestressed in its first position to turn to its second position under the effect of said prestressing when the first mechanism is released. Pyrotechnic decontamination device comprising at least one Detector according to claim 8 and a cutting line pyrotechnic device (41), in which the detector (1) is arranged so that activation of the detonator initiates the cutting chain pyrotechnic. Deconfinement device according to claim 9 in which the pyrotechnic cutting chain is a chopper cord (50, 51), a pyrotechnic hammer (52, 53, 54, 55) or a composition of a type thermite. System comprising a deconfining device according to claim 10, an enclosure (40) and an explosive charge (43) placed in the enclosure, the cutting chain (41) being arranged to weaken or cut the enclosure. The system of claim 11 further comprising a device inhibiting device having a command, the command being adapted to receive an external command, the muting device being configured to neutralize the deconfinement device when an external order is received by the order.

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