Fuse for a projectile

[0001] The invention relates to a projectile igniter with a firing system for firing a main projectile load and with a delay detonator for firing the ignition system after a delay time set by the firing section of the retardant charge, the delay detonator having a housing with an ignition half in which ignition occurs, and a detonator half that contains a detonator charge to ignite the ignition system.

[0002] Igniters for artillery shells, mortar grenades or direct shells usually have an ignition chain ignition system through which the projectile's main charge ignites. The ignition system or ignition chain contains an ignition charge that ignites electronically or mechanically at a certain moment or in a specific igniter situation, and which transfers its energy directly to the main charge or, for example, to the reinforcing charge of the ignition chain, which for its part releases the main charge.

[0003] In the event of failure of such a mechanical or electronic ignition of the ignition charge, the missile after landing becomes a misfire, which for a very long time constitutes a significant source of danger. Such a misfire can occur, for example, when a bullet with a blast detonator lands in deep snow or in a snowdrift, and the blast detonator does not ignite or the bullet contacts the ground so flat that it slips over the ground and stops slowly.

[0004] To guarantee ignition even in such unusual situations, it is known to provide a detonator with a delay detonator, which is triggered by, for example, firing a projectile, and which triggers the ignition system after a pre-set delay time of several seconds, when this was not previously triggered regularly by a time fuse or impact fuse and the like. Such a delay detonator typically contains a delay charge, which e.g. lights up when fired, and which, like a fuse, stays on for a specified delay time to pass the ignition energy to the detonator after this delay time to trigger the ignition system. From EP 0 666 464 A1, for example, a grenade fuse with an impact ignition device and with a self-elimination device having a delay kit is known. The delay set in the tube is triggered by the detonating cistern located above the tube. To be able to evacuate the exhaust gases contained in the collection chamber formed by the distance between the tube and the detonating cistern, the tube is finally fitted with a closing screw covering the drain hole.

[0005] The object of the invention is to create a projectile that reliably protects against firing.

[0006] This object is accomplished with an igniter according to the features of claim 1. The housing according to the invention has in the ignition half a drain hole with a freely open cross section in the igniting condition of the delay detonator.

[0007] The invention is based on the observation that the delay time can be set very precisely via the delay charge. In addition, the separation of the delay charge is very resistant to mechanical damage, so that ignition of the ignition system can take place via a delay detonator even when the igniter has been temporarily exposed to high loads that may occur during a shot and impact. However, due to the high mechanical loading during the projectile launching, it may happen that the uniform structure of the combustible material of the retardant charge is slightly disturbed. When high pressure peaks are created when the delayed detonator is triggered by uneven combustion, hot flammable gases due to nonuniformity in the fuel structure, such as microcracks, can break through the delay charge, so that the delay charge is bridged and the detonation charge released early. If the ignition timing is too early, the ignition charge of the ignition system may not be in the armed position, and triggering the ignition system by the delayed detonator detectors.

[0008] Through the drain hole in the ignition half of the delay detonator housing, the peak pressure values ​​that may arise when the delay detonator is ignited can be reduced, so that insufficient pressure is not created to push hot exhaust gas through the delay charge. Bypassing the delay charge can be reliably avoided and the ignition system can be triggered after a specified delay time.

[0009] The trigger hole allows, in the ignition state of the delay detonator, for the free flow of gas from the charge of the delay detonator to its surroundings. In the igniting condition of the delay detonator, it has a freely open cross section that is at least 1 mm in size². This allows sufficient gas to escape through the drain hole to reduce peak pressure values. The pressure reduction in the ignition half is all the more necessary the higher the peak pressure values ​​occurring during ignition. To be able to reduce high pressure peaks that may occur under high mechanical loads or heterogeneities in the load, the drain hole intentionally has a freely open cross-section in the ignition state of the delay detonator, at least 5 mm².

[0010] The delay detonator housing of the invention includes a plurality of delay detonator charges, such as, for example, a punctured charge, a transient charge between the punctured charge and a delay charge, and optionally a further transient charge and a detonator charge. Since the peak pressure values ​​are preferably formed during the triggering of the delay detonator, the drain hole is located in the ignition half of the housing, i.e. in the half in which the delay detonator is triggered, e.g. through a piercing needle which is pressed into the ignition charge.

[0011] When the ignition needle is used to trigger the delay detonator, it is passed through a housing which, for this purpose, may have a piercing hole. This piercing hole in the igniting condition of the delay detonator, i.e. in the state in which the ignition needle sinks into the ignition charge and releases it, is so blocked by the ignition needle that it cannot serve as a drain hole. The small gap between the ignition needle and the housing is sufficient as a drain hole only when it has a clearance of at least 1 mm², which must also not be covered by the ignition needle element, e.g. by a lid or bumper.

[0012] According to the invention, the drain hole opens directly into the charge of the pierced delay detonator. Peak pressure values ​​that arise during ignition of a punctured charge can thus be particularly well discharged. It is also possible to arrange a drain hole on the transfer charge between the puncture charge and the delay charge to reduce peak pressure values ​​that may arise when transferring energy from load to load. It is also advantageous to place the drain hole on both the pierced load and the transfer load.

[0013] To realize longer delay times, the delay detonator was deliberately made longitudinally, so that its length in the firing direction is longer, and especially more than twice as long as its extent in both other directions in space.

[0014] For making the compact fuse it is advantageous to place a longitudinal detonator delaying transversely to the direction of the projectile. For this purpose, the firing direction of the delay detonator, i.e. the direction preferably lies transversely to the direction of flight of the projectile, and intentionally at an angle between 70 and 110 degrees relative to the direction of flight of the projectile, and especially perpendicular to the direction of flight of the projectile. The firing direction is the direction in which the detonator's retarding charge burns, e.g., from a pierced charge into the detonator's charge.

[0015] In a preferred embodiment of the invention, the piercing hole and the drain hole may be made as two separate holes in the housing. This allows separation of the piercing and pressure reduction processes, and the holes can be optimized for reliable ignition of the delay detonator or for good pressure reduction. Alternatively or additionally, it is possible that the drain hole simultaneously constitutes a piercing hole through which the piercing needle can be inserted for ignition of the delay detonator.

[0016] The penetration of the delay detonator occurs preferably during the firing of the projectile and with the use of acceleration of firing. A particularly easy ignition design can then be obtained when the piercing direction of the piercing needle through the piercing opening is opposite to the direction of flight of the projectile. By the parallelism of the piercing direction and the bullet flight direction, the inertia of the piercing needle can be used to accelerate and drive into the delay detonator without the need for other propulsion means.

[0017] The injection of hot flue gas through the delay detonator in the event of a peak pressure can occur only when there is a suitable counter pressure in the direction opposite the firing in the delay detonator. The generation of such a counter pressure can be particularly effectively counteracted when the drain hole according to the invention is in a housing against the firing direction of the delay charge. Accelerated hot gases can leave the delay detonator without redirection, so that particularly effective pressure reduction can be achieved.

[0018] Preferably the drain hole is opposite the opening of the housing detonator. Pressure reduction against the firing direction can thus be realized particularly easily. The drain hole can then be located in the rear side of the housing, which is in particular parallel to the front side. The back and front can be defined by the ignition half, which is the rear half, and the detonator half, which is the front half.

[0019] In a further preferred embodiment of the invention, the delay detonator is provided to accelerate the armed ignition charge of the ignition system against the ignition needle. The ignition system can be triggered and thus the main charge can be exploded.

[0020] Particularly preferably the invention can be applied to a fuse which is a shock fuse. In the absence or weak impact, the ignition energy needed to trigger the ignition system can be provided by a delay detonator, for example by accelerating the ignition charge of the ignition system against the piercing needle.

[0021] Further advantages result from the following description of the drawing, which shows an embodiment of the invention. The drawing and description contain a number of features in combination that the skilled person will intentionally consider purposefully also separately and combine in meaningful further combinations.

[0022] The figures show:

Figure 1: schematic perspective view of the detonator with a delay detonator, and

Figure 2: delay detonator in cross-sectional side view.

[0023] Figure 1 shows the fuse 2 of a not further depicted projectile, for example a mortar grenade, artillery projectile or direct projectile in partial section view and in strong simplification. The detonator 2 is a striking detonator and can be screwed through the thread 4 into the shell of the projectile, resulting in a projectile. The igniter 2 comprises a fuse housing 6 with a bottom 8 on which the elements of the igniter 2 are attached, e.g. delaying detonator 10 and next to it a double-bolt system 12, of which only one part is schematically indicated for clarity. Also, only one rotor 14 that rotates around the pin 16 and two needles is also marked

Piercing 18, 20 for igniting the ignition charge 22 in the rotor 14, or the piercing charge 24 (see figure 2) in the delaying detonator 10, the attachment of which in the igniter housing 6 has also not been shown for clarity.

[0024] Figure 2 shows the delay detonator 10 in cross-sectional view. In the housing 26 from the front to the rear there is a punctured charge 24, transfer load 28, delay load 30, another transfer load 32 and detonation charge 34. In the area of ​​the punctured load 24 the casing 26 is equipped with a piercing hole 36 through which the punctured load 24 can be insert piercing needle 20. On the rear side 38 of the housing 26 and also in the area of ​​the punctured charge 24, the housing 26 is equipped with a drain hole 40. On the opposite front side 42, the housing 26 is made in an open manner, so that a large detonation hole 44 is formed. The delay detonator 10 has a length of good 20 mm, and the diameter of the detonation hole is about 3.5 mm.

[0025] During the firing of the projectile, the igniter 2 is very much accelerated in the direction of flight 46. Thanks to this, the bolt 48 of the double bolt system 12 is pressed down, i.e. towards the bullet hull, and with it the second bolt of the double bolt system 12 not shown. Thanks to this, the rotor 14 is unlocked, which due to the appropriate mechanics is rotated around the pin 16, so that the ignition charge 22 is displaced according to the arrow 50 under the piercing needle 12. When the bullet hits the target, the igniter 2 is very much accelerated against the direction of flight 46, yes that the rotor 14 is moved upwards relative to the fuse housing 6, i.e. in the direction of flight 46, as indicated by arrow 52. The piercing needle 18 rests immobilized in the igniter housing 6, so that the ignition charge 22 is pressed against the piercing needle 18 and released. By the ignition charge 22, the ignition energy is transferred through the bottom 8 to the non-represented main charge of the projectile, which is released. The ignition charge 22, rotor 14 and piercing needle 18 are components of the ignition system 54, which may optionally also contain one or two consecutive ignition chain loads.

[0026] In the event of a soft landing of the projectile or slow sliding of the projectile during a flat landing on a flat ground, the delay acceleration of the igniter 2 is possibly too low to press the rotor 14 in the upward direction 44 and the ignition charge 22 against the firing needle 18. Bullet it stops without detonating the main charge and becomes a misfire. To avoid this, the igniter 2 is equipped with a delay detonator 10, which is triggered when the projectile is launched. During the firing of the projectile, the piercing needle 20, which is movably mounted in the fuse housing 6, due to inertia is accelerated relative to the fuse housing 6 in the piercing direction 56, i.e. against the direction of flight 56, to the delay detonator 10 so that the tip moves through the hole 36 in the housing 26 for punctured cargo 24. Thanks to the roundabout-shaped limiter 58 of the piercing needle 20, its movement to the pierced load 24 is stopped, whereby the limiter 52 when lighting the pierced load 24 like the lid adheres to the piercing opening 36 and simultaneously closes it.

[0027] The pierced charge 24 releases the transfer charge 28, which again triggers the delay charge 30. The delay charge 30 is made such that from the rear end at the transfer load 28 it burns for 15 seconds, until the combustion reaches the front end and at the same time transferring 32. Transferring charge 32 after these 15 seconds is triggered and releases itself a charge 34 detonator, which causes a strong impact of gas pressure outside. By means of this gas pressure shock, the rotor 14 is accelerated in the flight direction 46, so that the ignition charge 22 is pressed against the piercing needle 18 and released. In this way, the main charge of the projectile is released after 15 seconds at the latest, if it was not previously properly triggered by the impact of the fuse 2.

[0028] When triggering the punctured charge 34 and the transfer charge 28, it may happen that a high gas pressure will form inside the enclosure 26 in the region of the puncture charge 24 and / or the transfer charge 28. As a result, it may happen that hot gases are shaken by delaying charge 30, in particular when it has microcracks and the like, which for example may have been formed during firing. The transfer charge 32 is immediately released, and with it the charge 34 of the detonator, so that a gas pressure surge to raise the rotor 14 is generated during or immediately after firing. At this point, the rotor 14 is not yet screwed into the release position, so that the ignition charge 22 cannot yet be pressed against the piercing needle 18. The main charge is not detonated in the event of a too small impact. Then the missile becomes a misfire. In addition, the rotor 14 may be damaged by a gas pressure drop of the detonator charge 34, so that it becomes wedged and cannot rotate to the unlocked position. In this way, the ignition charge 22 cannot be triggered in the event of a proper impact, and the projectile will in any case become a misfire.

To avoid this, a trigger hole 40 is provided in the ignition half 60 of the delay detonator 10. The ignition half is according to the dimensions of the rear half of the delay detonator 10. The ignition charge 24 is in it 24. The front half of the delay detonator 10 is its detonating half 62, in which there is a 34 detonator charge. Undesirable pressure peaks are reduced through the drain hole 40, allowing the exhaust gas to escape from the housing 26 through the drain hole 40. The delay charge 30 may regularly burn out and reliably prevent the projectile from firing.

[0030] To enable the long firing distance 64 in the firing direction 66, the delay charge 30 is built longitudinally, and with it the delay detonator 10. To obtain a compact igniter 2, the longitudinal direction of the longitudinal delay detonator 10, and with it the firing direction 66 of the delay charge. 30 is positioned perpendicular to flight direction 46. To utilize the inertia of the piercing needle 20 to trigger the delay detonator 10, the piercing needle 20 is arranged such that to trigger the delay detonator 10 it is introduced into the housing 26 sideways with respect to the longitudinal direction of the delay detonator 10 or the firing direction 66.

-7 List of links

<td colspan="2"> [0031]</td>

<td> 2</td><td>igniter</td>

<td> 4</td><td>thread</td>

<td> 6</td><td>housing</td>

<td> 8</td><td>bottom</td>

<td> 10</td><td>delaying detonator</td>

<td> 12</td><td>two-pin system</td>

<td> 14</td><td>rotor</td>

<td> 16</td><td>bolt</td>

<td> 18</td><td>piercing needle</td>

<td> 20</td><td>piercing needle</td>

<td> 22</td><td>ignition charge</td>

<td> 24</td><td>punctured load</td>

<td> 26</td><td>housing</td>

<td> 28</td><td>carrying load</td>

<td> 30</td><td>delayed load</td>

<td> 32</td><td>carrying load</td>

<td> 34</td><td>detonator charge</td>

<td> 36</td><td>pierce hole</td>

<td> 38</td><td>back side</td>

<td> 40</td><td>drain hole</td>

<td> 42</td><td>front side</td>

<td> 44</td><td>detonator hole</td>

<td> 46</td><td>flight direction</td>

<td> 48</td><td>bolt</td>

<td> 50</td><td>arrow</td>

<td> 52</td><td>arrow</td>

<td> 54</td><td>ignition system</td>

<td> 56</td><td>piercing direction</td>

<td> 58</td><td>stop</td>

-860 ignition half detonator half firing distance firing direction

Magdalena Pietrosiuk Patent Attorney