EP2537561B1 - Blocking element for closing an opening - Google Patents

Description

The invention relates to a locking element for closing an opening. Such a blocking element is already known and is used for example in cable ducts application. These cable ducts are made of a non-combustible material and are inside, d. H. in the passage, equipped with a thermally expandable solid which expands in case of fire by the heat developed during the fire and thereby closes the cable channel and thus prevents fire propagation in the cable duct.

The disadvantage here is that a fire in the cable channel can already be further advanced until it comes to the closure of the cable channel. This problem occurs especially in fires that develop relatively little heat, for example because of a lack of oxygen.

In the DE 196 17 017 A1 describes how such a passage can be closed quickly and reliably. There, a blocking element is provided for closing a passage comprising a heat-releasing pyrotechnic composition during firing and a thermally expandable solid. In this case, the pyrotechnic charge and the solid are arranged to each other and to the passage and the solid and the pyrotechnic composition are selected so that the solid expands upon burning of the pyrotechnic charge and thereby closes the passage. The solid and the pyrotechnic composition are chosen so that the released during combustion of the pyrotechnic charge heat is sufficient to expand the solid. Furthermore, the solid and the pyrotechnic composition are arranged to each other so that when burning of the pyrotechnic charge sufficient for the expansion of the solid heat transfer takes place on the solid. Furthermore, the pyrotechnic composition and the solid are arranged such that the solid which expands upon combustion of the pyrotechnic composition passes through the passageway and thereby closes it or actuates a mechanism which closes the passageway. The mechanism may be, for example, a slider or flap which closes the passageway. Such a blocking element can be used to close any passageways.

Compared to the first-described blocking element, the blocking element of DE 196 17 017 A1 has the advantage that it can block the passage much faster and more reliably and less heat is required. When passing through a cable channel, the latter blocking element has the great advantage that even a small fire, which generates relatively little heat, can ignite the pyrotechnic composition quickly and reliably. This allows an immediate and complete closure of the cable channel and thus a reliable prevention of fire propagation can be achieved.

To ignite active compositions in existing from a propellant charge and an active mass pyrotechnic decoys usually so-called squibs are used. A squib is usually installed in a fuse element with a sliding protection and placed between the propellant and the active mass. The burning propellant causes ignition of the squib through a first opening. Opposite the first opening, a second opening is arranged in the squib, which is aligned with an opening in the securing element. A slider closes the opening in the securing element and thereby prevents a flame passing through the second opening of the firing squib from prematurely igniting the active mass. The slider releases the opening in the securing element only when the burning propellant has expelled the remaining decoy from its sleeve. This reliably prevents the active mass from being set on fire prematurely and, for example, still reacting in the plane shooting the decoy. After ejection from the sleeve ignites the flame of the burning squib the active mass through the second opening and then released from the slide opening in the fuse element.

A disadvantage is that this ignition is not reliable and fast at a moving at high speed decoy, because in the direction of flight behind the fuse element, a negative pressure is created, which pulls the flame through the first opening from the squib backwards. As a result, the flame passing through the second opening and the opening in the securing element on the side of the effective mass is very weak and a firing delay of up to a few seconds may occur. However, the ignition delay should be at most 100 milliseconds.

To solve this problem, a very fast burning pyrotechnic kit can be used to make the squib. However, this has the disadvantage that the squib ignited when the slide is still closed due to the rapid burning and the associated rapid pressure increase is easily ejected in the direction of the propellant and then the active mass can not ignite.

Alternatively, an intermediate wall with a small opening can be arranged in the squib. After ignition on the propellant charge side ignition takes place on the effective mass side of the squib through the small opening. Due to the fact that the opening is small, some pressure is built up on the active mass side in spite of a vacuum on the propellant charge side so that the flames can blow increasingly in the direction of the active mass and thereby ignite the active mass. However, the production of such a squib is complex and expensive. The squib must be pressed from two sides and the small opening must be made manually by means of a thin wire. Desirable would be an alternative with little effort and low cost to produce squib, with the effective mass of a decoy can be reliably ignited.

Object of the present invention is therefore to provide a blocking element without the disadvantages described above.

This object is achieved by the blocking element according to claim 1. Advantageous embodiments result from the features of the dependent claims. The scope of the invention is defined by the appended claims.

By means of the blocking element according to the invention such a squib can be provided. In such an embodiment, the container having the opening with the pyrotechnic composition and solid disposed therein comprises at least one further opening. The pyrotechnic set can then be ignited through the opening. When the pyrotechnic composition burns in such a container, the closing of the opening by the solid causes the flame formed during combustion to be blown outward through the additional opening in the container through the additional pressure that is thereby produced. This is also the case when there is a negative pressure on the side of the opening outside the container. As a result, the flame can reliably ignite, for example, an active mass. The named container can be used as a squib.

The blocking element according to the invention has the advantage that it is very reliable and at the same time easy to manufacture. In particular, it does not have to have an intermediate wall with the same to be produced therein, as in the case of an embodiment of a known squib Opening to be provided. Another advantage is that the opening can be relatively large because of the later occlusion. By such an opening is a more reliable and faster ignition of the pyrotechnic charge, for example, by a propellant, possible as through the openings known Zündpillen which keeps as small as possible because of the described negative pressure problem.

In addition, the blocking element according to the invention can be used in a conventional securing element with sliding safety, so that retrofitting is possible without conversion of production.

A particular advantage in the case of decoys is that, due to the closure of the opening by the expandable solid, little or nothing can be seen from the flame arising during combustion of the pyrotechnic charge. This is particularly important for spectral decoys, because the spectrum of the firing pyrotechnic set differs significantly from the spectrum of the active mass of the decoy and thus can reveal detection systems that this is only a decoy and not an aircraft. The avoidance or reduction of an externally detectable from the combustion of the pyrotechnic charge of a squib resulting radiation is a significant advantage of the blocking element according to the invention and guaranteed in any known squib.

In the advantageous embodiment of the locking element according to the invention the passage is an opening and the blocking element further comprises a container having the opening, wherein the pyrotechnic charge and the solid are arranged in the container and the container has at least one further, in particular not to be closed, opening. The blocking element is part of a pyrotechnic ignition means, in particular for igniting an active mass, in particular an active mass of a pyrotechnic decoy target. The ignition means further comprises a securing element with an additional opening aligned with the further opening and with a mechanical closure means for closing the additional opening. The closure means may be a sliding safety device with a slide closing the additional opening.

The release of the additional opening by the closure means can not be effected by the burning of the pyrotechnic charge but only mechanically. As a result, an involuntary ignition of an active mass can be reliably prevented. It has been found that the blocking element according to the invention is then particularly advantageous if the expanded solid such. B. Blähgrafit or a silicate, although in the opening withstand a predetermined pressure, however, yields at exceeding the predetermined pressure and is pushed through the opening. As long as there is still expandable solid within the container, this leads to the fact that within the container no excessive pressure builds up, but the opening is immediately closed as soon as the closure means releases the additional opening aligned with the further opening. As a result, the mechanical load of the container when burning the pyrotechnic charge is relatively low. The container can therefore be made of relatively inexpensive material, for example a plastic, in particular polyamide. The manufacturing can be done inexpensively in an injection molding process.

The closure means, in particular in the form of a sliding safety device, can be designed such that it keeps the additional opening closed at the beginning of the firing of the pyrotechnic composition and opens before the end of the firing of the pyrotechnic composition and before the expandable solid has completely expanded.

Preferably, the pyrotechnic composition and the solid are compressed together in a compressed form. The pressing can be done so that the pyrotechnic charge and the solid are arranged spatially separated from each other. Standing there the solid and the compressed concentrate are in contact with each other over only one surface. Alternatively, it is also possible that the solid is distributed in the pyrotechnic composition. This has the advantage that the blocking element can be produced in a single pressing operation. On the other hand, this has the disadvantage that the flame generated in the pyrotechnic composition has a lower temperature, because the solid does not contribute to the combustion and the energy deprives the flame. As a result, the ignition of an active mass may be delayed somewhat, ie the ignition time is extended in such a blocking element. A spatial separation can be effected, for example, by first pressing a thin layer of the solid and then pressing a slightly thicker layer of the pyrotechnic composition. Both can be introduced into the container so that the layer formed by the solid in the direction of the opening and the layer formed by the pyrotechnic composition is arranged in the direction of the further opening. As a result, a quick closure of the opening and an intense flame discharge are ensured by the further opening after ignition.

In a further advantageous embodiment, the solid is bound with a binder, in particular polychloroprene. The solid may comprise expandable graphite or a silicate, especially sodium silicate.

The pyrotechnic composition usually comprises a fuel, in particular boron, and an oxidizing agent, in particular bismuth trioxide or barium nitrate.

The invention will be explained in more detail by means of exemplary embodiments.

The figure shows schematically a section through a pyrotechnic blocking element 10 according to the invention with a pyrotechnic composition 12 and a thermally expandable solid 14 pressed therewith. The pyrotechnic composition 12 and the thermally expandable solid 14 are arranged in the container 16 compressed from two parts. On the side of the thermally expandable solid 14 of the container 16 is the opening 18 and on the opposite side of the container 16, the further opening 20. Such a blocking element 10 can be arranged between a disposed on the side of the opening 18 and a propellant on the side of be arranged further opening 20 arranged decoy active material within a securing element with a sliding safety.

The compressed solid of the expanding solid and the pyrotechnic composition preferably has a through hole. As a result, a fast and reliable ignition of the pyrotechnic set 12 from opening 18 can be ensured.

During combustion of the propellant ignited this through the opening 18 through the pyrotechnic composition 12, which then brings the thermally expandable solid 14 to expansion by the heat released during its combustion. The solid passes through the opening 18 and thereby closes it. This causes an increase in pressure within the container 16 and an optionally acting on the side of the opening 18 suction has no influence on the pressure within the container 16. Thus, the flame formed by the pyrotechnic composition 12 is blown out of the further opening 20 and not as in a conventional squib without the thermally expandable solid 14 pulled out of the opening 18 when there is a negative pressure on the side of the opening 18. The flame blown out of the further opening 20 ignites more reliably and faster than a conventional squib a fake target active mass arranged on the side of the further opening 20.

example 1

In a designed as Zündpillennapf container of polyamide 100 mg of an expandable to about 50 ml / g expandable graphite graphite with 12% polychloroprene as a binder. This creates a 1 mm thick layer. Then about 500 mg of a pyrotechnic charge are pressed. The diameter of the opening and the further opening in the container is 2 mm. The container is mounted in a securing element with a sliding safety. In each case one of the ignition means thus produced is ignited with a closed slide and one with an open slide by means of a fuse. The reaction was filmed using a video camera at 30 Hz frame rate. It was found that the flame blows exclusively through the opening with the slide closed. The Blähgrafit is so too high pressure in the container and is pushed to the outside. When the slide was open, however, the flame exited only through the further opening. The pyrotechnic composition used was a mixture of boron as fuel and bismuth trioxide as oxidant. Alternatively, a pyrotechnic charge of barium nitrate has been used as the oxidant to provide a slower-burning and less-gas burning but higher-temperature pyrotechnic charge.

Example 2

Instead of the relatively weakly expanding expandable graphite used in Example 1, an expanding expandable graphite was used which expanded to about 500 ml / g. When burned, the same results as in Example 1 showed.

Example 3

Instead of expandable graphite, dry sodium silicate without binder was pressed into the primer cap as an expandable solid. It showed that the sodium silicate expands more slowly than the expanding graphite when the pyrotechnic composition burns down. As a result, the closing of the opening takes a little longer and even with the slide open, a weak flame blows through the opening for about 30 ms. Thereafter, the flame blows only through the further opening.

Example 4

In a pyrotechnic composition, 15% pure expanded graphite was mixed as coarse, about 0.5 mm, flakes. Of these, 600 mg each were pressed into primer pots. When burned, almost the same results as in Example 1 showed.

LIST OF REFERENCE NUMBERS

10

blocking element

12

pyrotechnic set

14

thermally expandable solid

16

container

18

opening

20

further opening

Claims (8)

1. Blocking element (10) for closing an opening (18), comprising a pyrotechnic composition (12) which releases heat during burning and a thermally expandable solid (14) the blocking element (10) further comprising a container (16) having the opening (18) and at least one further opening (20), in which the pyrotechnic composition (12) and the solid (14) are arranged, the pyrotechnic composition (12) and the solid (14) being arranged with respect to one another and with respect to the openings (18, 20) and the solid (14) and the pyrotechnic composition (12) being selected in such a way that the solid (14) expands on burning of the pyrotechnic composition (12) and thereby closes the opening (18) such that the flame formed by the pyrotechnic composition (12) following expansion of the solid (14) is blown out of the further opening (20).
2. Blocking element (10) according to Claim 1, the blocking element (10) being part of a pyrotechnic initiator, in particular for igniting an active mass, in particular an active mass of a pyrotechnic decoy.
3. Blocking element (10) according to Claim 2, the initiator having a safety element with an additional opening, which is aligned with the further opening (20), and with a mechanical closure means for closing the additional opening.
4. Blocking element (10) according to Claim 3, the closure means, in particular in the form of a sliding safety catch, being designed in such a way that it keeps the additional opening closed at the beginning of burning of the pyrotechnic composition (12) and opens the additional opening prior to the end of burning of the pyrotechnic composition (12) and prior to complete expansion of the expandable solid (14).
5. Blocking element (10) according to one of the preceding claims, the pyrotechnic composition (12) and the solid (14) being compressed with one another to form a compact, in particular physically separate from one another.
6. Blocking element (10) according to one of the preceding claims, the solid (14) being bonded with a binder, in particular polychloroprene.
7. Blocking element (10) according to one of the preceding claims, the solid (14) comprising expanded graphite or a silicate, in particular sodium silicate.
8. Blocking element (10) according to one of the preceding claims, the pyrotechnic composition (12) comprising a fuel, in particular boron, and an oxidant, in particular bismuth trioxide or barium nitrate.

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