AU2015200920A1 - Activation unit for active masses or active bodies - Google Patents

Abstract

An activation unit for explosive masses or explosive bodies includes an ejector tube and high-performance heating elements mounted around the ejector tube, each made of at least one heating wire supplied with electrical power by a control unit. Each heating wire is enclosed in a casing and embedded in a material minimizing heat loss. When the explosive body is passed through the activation unit, the jacket surface of the explosive body contacts the individual elements of the activation unit in a direct or non-contact manner. Thermal energy is transferred to the explosive body by means of the heating wires, and the body ignites at the contact points. A further activation unit includes heating elements in the ejector tube, at least partially fed longitudinally through the ejector tube, made of heating wire clad with CrNi steel and contact plates soldered thereto.

Description

DESCRIPTION Activation unit for explosive masses or explosive bodies The present application is a divisional application from Australian Patent Application No. 2010244780, the entire disclosure of which is incorporated herein by reference. The invention relates to an activation unit for, in particular, munition-free explosive masses or explosive bodies, for example for forming decoys. A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims. Decoys and/or smoke shells based, for example, on red phosphorus (RP) or nitrocellulose (NC) are used in military applications, for example smoke shells, infrared (IR)-acting aircraft decoys etc. The smoke or IR effect is deployed by the RP/NC after appropriate ignition by burning. RP units (explosive bodies) are ignited via an ignition or break-up charge, which ensures that the bodies can be optimally ignited, and can then burn, for the respective purpose. DE 10 2007 032 112 Al describes so-called jamming which are fired from a launching apparatus having a plurality of launching tubes. Launching is performed in a manner initiated electrically or mechanically. The sub-clocking for initiating the individual light flashes is controlled by an electronics system which is incorporated in the apparatus. A plurality of sub-bodies are ignited in a manner clocked in time in order to initiate the light flashes or break-up flashes. To this end, said sub-bodies have pyrotechnic ignition or break-up charges. DE 199 10 074 B4 describes a launching apparatus for firing a plurality of explosive bodies. The explosive bodies which can be fired in this case each have a drive charge with an ignition means, for example a firing cap, which is connected to a 1 control unit of the adapter when the explosive-body pack and adapter are in the assembled state. Decoys of this kind cannot be used in civil aviation because of the munition component since explosives are not accepted in this context and international safety agreements etc. have to be complied with. Proceeding from the above, a novel ignition concept has been developed, this concept not requiring explosive and/or pyrophoric substances to ignite RP/NC flares. This novel ignition concept is described in more detail in DE 10 2006 004 912 Al. Said document discloses a system for protection, in particular, of large flying platforms, such as aircraft, against a threat guided by IR or radar. In this case, the explosive bodies are preferably activated or ignited contactlessly. The explosive bodies are then ejected pneumatically or mechanically. The explosive bodies themselves are munition-free packs which are ignited by means of hot air or a laser. Building on this activation concept, it is desirable to specify an activation unit which activates such explosive bodies in order to produce decoys. According to the present invention, there is provided an activation unit for munition free explosive masses or explosive bodies, wherein the unit comprises: (a) an ejection tube; and (b) a plurality of heating elements disposed in the ejection tube and that are longitudinally routed at least partially through the ejection tube, wherein each heating element comprises: i. a heating wire that is sheathed with CrNi steel; and ii. one or more contact plates that are soldered onto the heating wire. In a particular embodiment of the invention, the plurality of heating elements are routed along through the entire length of the ejection tube. In another particular embodiment, the ejection tube has a thermal insulation means. 2 In another particular embodiment the activation unit as claimed in claim 3, wherein the thermal insulation means is incorporated on an inner surface of the ejection tube between the sheathed heating wires and the ejection tube. According to another embodiment the thermal insulation means is formed by one or more ceramic inlays. According to another embodiment the thermal insulation means is formed by several ceramic inlays. According to another embodiment the plurality of heating elements are disposed only in front part of the ejection tube. According to another embodiment the plurality of heating elements are disposed throughout an entirety of the ejection tube. Fundamentally, the invention is based on the above-mentioned idea of activating (of igniting) the explosive masses/flare material by supplying thermal energy. This avoids the use of explosives. In order to activate the explosive body, said explosive body is thus subjected to the action of thermal energy in a suitable form. This can be achieved by the explosive body, which generally comprises individual flares, being forced through an ignition tube for activation purposes. The "ejection" can be performed pneumatically or mechanically. To this end, an ignition tube, from which the explosive masses are ejected, has a high-temperature activation element which consists essentially of n heating elements which are arranged geometrically separately from one another, radially around the circumference of an ignition tube. The geometry of the activation unit is not necessarily a circular cylinder. The heating elements can also be matched to other geometries, for example to a rectangular cylinder. 3 The material chosen for the individual heating elements allows temperatures of > 600 C, with the heating elements being designed such that they allow extremely dynamic heating on account of small masses. The outer casing of the heating wire of the heating elements is preferably composed of a highly temperature-resistant steel with a high CrNi content. Furthermore, ceramic inlays, for example, ensure further thermal optimization by minimizing heat losses. The heating elements are designed such that they ensure ideal energy input into the explosive body for the application. The heating element can additionally be provided, for example, with contact plates or the like for improved energy transfer. This thermal optimization and appropriate control engineering result in an extremely short reaction time of the heating elements, that is to say the heating time from the switch-on point to reaching the nominal temperature is extremely short (low or small). Any desired number of heating elements may be used and may be selected, and the heating elements may in principle be prefabricated in any shape. It is therefore possible to ideally set the energy input for each application on the one hand by the choice of the number n of heating elements and/or on the other hand by adapted control engineering. Depending on the application, the explosive body can be ignited by contact with the heating elements or else contactlessly. To this end, it is possible to activate the explosive body as it "flies past". This form of activation allows the use of decoys without explosives in the civil environment, not only in civil aviation but also for civil seaborne targets and land vehicles. The design and safety requirements for decoys and dispensers without explosives are simpler, that is to say considerably less stringent. The ignition unit or apparatus allows a multiplicity of ignition operations, while that for traditional flares is intended to be used only once. The extremely high CrNi content results in a high susceptibility to corrosion, the high temperature resistance and a relatively high wear resistance. The separate casing and routing of the elements ensures the leaktightness of the heating elements. The casing is free of potential, and traditional short-circuit links are therefore excluded. It 4 is likewise possible to adapt the power to a slight extent by changing the length or simply changing the circuitry of the heating elements. The functional reliability can be increased by current preferably being carried in multiple circuits through the n heating elements. The contactless and flexible suspension/incorporation of the heating elements permits only low levels of loss and improved contact-making. The explosive-body tolerances could be better compensated for by clean routing of the explosive-body pack. Practice has shown that ignition over a large surface area (surface area of approximately 80%) is achieved with a low mass (and therefore with a minimal thermal inertia for ensuring dynamic heating regulation). The invention will be explained in more detail with reference to an exemplary embodiment and a drawing, in which: fig. 1 shows an activation unit with an ejection tube for an explosive body; fig. 2 shows heating elements of the activation unit from fig. 1; fig. 3 shows a variant of the design of the ejection tube, fig. 4 shows a further embodiment of the ejection tube, and fig. 5 shows an explosive body which is to be dispatched from the ejection tube. In the section illustrated in fig. 1, 1 denotes an activation unit. The high-temperature activation unit 1 substantially comprises an ejection tube 2 from which an explosive body 3 (fig. 5), which is not illustrated in any more detail here, is ejected in the direction of the arrow P. The ejection tube 2 is surrounded by high-temperature heating elements 4 on its inner face/surface, with each individual element 4 being formed from a heating wire 6 which is held in a casing 7, protected against external influences, and is preferably embedded in a material which minimizes heat loss, preferably in a ceramic inlay 8. In the preferred embodiment, the outer casing 7 of the heating element 4 is composed of a highly temperature-resistant steel with a high CrNi content. For mechanical strain relief, the ceramics 8 are held in the metal structure of the ejection tube 2, with the metal structure corresponding to the external 5 shape of the explosive body 3, in this case a cylindrical shape. Alternative forms are likewise possible. The heating wires 6 are supplied by appropriate control engineering (not illustrated in any more detail) with the appropriate electrical energy, and are thus heated to > 600*C. The ceramic inlays 8 themselves improve the energy balance of the respective heating element 4, and in the process ensure more efficient introduction of energy from the explosive body 3. Fig. 2 shows a variant of the arrangement and of the design of heating element 4 which is embedded in the ceramic inlay 8. Figure 3 shows a further variant of the activation unit 1' with an ejection tube 2'. In this figure, 10 denotes heating elements which are routed along through the tube 2' and have a CrNi steel casing 11, the heating wire surface of said tube being increased in size by at least one, for example soldered-on, contact plate 13, as a result of which the contact area of the heating wire 14 relative to the explosive body 3 is also increased in size. The ejection tube 2' has a thermal insulation means 15, for example formed by one/several ceramic inlay(s). Fig. 4 shows another embodiment of the activation unit 1" having an ejection tube 2". In this embodiment, short heating elements 10" are used similarly to those above. Fig. 5 shows the design of the explosive body 3. Said explosive body is distinguished by a plurality of individual flares 9. The functioning is as follows: The explosive body 3 is forced through the activation unit 1 (1', 1"), by way of example, by a plunger (eject unit - not illustrated in any more detail). When the explosive body 3 passes through the activation unit 1, the casing surface of the explosive body 3 makes contact with the individual elements 4 of the activation unit 1. The thermal energy is transferred (directly or indirectly) through the heating wires 6 6 (14) to the explosive body 3 which is ignited at the touching or contact points. After emerging from the activation unit, the explosive body 3 can burn through completely, and can develop its radiation (IR radiation). As already mentioned, as an alternative to making direct contact, contactless activation is also possible, in which case it is necessary to ensure that the individual flares 9 of the explosive body 3 are ignited. The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the present disclosure. Throughout the description and claims of the specification, the word "comprise" and variations of the word, such as "comprising" and "comprises", is not intended to exclude other additives, components, integers or steps. 7

Claims (8)

1. An activation unit for munition-free explosive masses or explosive bodies, wherein the unit comprises: (a) an ejection tube; and (b) a plurality of heating elements disposed in the ejection tube that are longitudinally routed at least partially through the ejection tube, wherein each heating element comprises: i. a heating wire that is sheathed with CrNi steel; and ii. one or more contact plates that are soldered onto the heating wire.

2. The activation unit as claimed in claim 1, wherein the plurality of heating elements are routed along through the entire length of the ejection tube.

3. The activation unit as claimed in claim 1 or 2, wherein the ejection tube has a thermal insulation means.

4. The activation unit as claimed in claim 3, wherein the thermal insulation means is incorporated on an inner surface of the ejection tube between the sheathed heating wires and the ejection tube.

5. The activation unit as claimed in claim 3 or 4, wherein the thermal insulation means is formed by one or more ceramic inlays.

6. The activation unit as claimed in claim 3 or 4, wherein the thermal insulation means is formed by several ceramic inlays.

7. The activation unit as claimed in any one of claims 1 to 6, wherein the plurality of heating elements are disposed only in a front part of the ejection tube.

8. The activation unit as claimed in any one of claims 1 to 6, wherein the plurality of heating elements are disposed throughout an entirety of the ejection tube. 8