GB2274905A - Smoke charge canister - Google Patents

Description

2274905 ARRANGEMENT IN A SMOKE CHARGE CANISTER

Field of the invention

The present invention relates to an-arrangement in a smoke charge canister, especially a smoke charge artillery grenade, comprising a front housing holding an ejection/ignition charge, as well as a substantially cylinder-shaped grenade shell holding a plurality of axially consecutively arranged smoke charge canisters, defining or communicating with an axially extending central tube having openings through which the flames from the ejection/ignition charge initiate the combustion of the smoke charge of the smoke charge canister, the smoke charge canisters being ejected through the bottom of said grenade shell, each smoke charge canister being provided with one or more ignition openings or perforations only at its one end portion for initiating an axial combustion of said charge canister.

Prior art

A traditional smoke artillery grenade comprises metal containers having a perforated central tube, which containers are stacked onto each other in the grenade shell. Whilst the grenade is flying at several hundred meters above ground these metal containers or smoke canisters are ejected out from the grenade shell through the bottom of the grenade by means of an ejection charge. The flame of the ejection charge ignites the individual smoke charges through the perforations in the central tube of the smoke canister, and through an ignition charge which surrounds the central tube. This means that the smoke charge in the individual smoke canister is ignited whilst the smoke canisters are far above the ground and will land only after a comparatively long time.

In many prior art smoke artillery grenades the smoke charge burns in the smoke canister radially from the centre and

2 outwardly, which entails that the smoke development which is given by the burning surface, will be proportional with the burning time. In a 155 mm grenade this means that the smoke development increases after firing and will become approxi mately 7 times the initial smoke development at the end of the combustion. This, on its hand, will imply that the screening to be effected by the developed smoke will be very uneven not only due to the varying smoke development, but also due to the increasing heat lift, because the exothermic chemical reaction will release increasing quantities of energy per time unit. By increasing heat lift the smoke will rise faster into the air and the screening effect will be correspondingly reduced and become especially unfavour able by low wind speed conditions.

is GB 1 415 274 (Walde et al.) relates to a smoke grenade comprising smoke canisters which after having been fired and ejected from the grenade at a high altitude will have their wings folded out, said wings serving to reduce the falling velocity of the canisters, said wings also orientating the individual smoke canisters so as to leave the smoke discharge openings pointing upwardly upon landing.

The smoke canisters according to GB 1 415.274 are hampered with the disadvantage that said wings require large space.

Secondly, any smoke canister according to prior art only allows smoke to emerge from the one end of the canister, which thereby entails the disadvantage that the smoke canister is dependent upon a soft support in combination with said wings for avoiding covering or congestion of said end discharge openings when hitting the ground. It is true that GB 1 415 274 suggests an axial combustion pattern, but nowhere is there suggested any time delay in connection with the ignition of the smoke canister, which means that the smoke charge will burn from the moment of ignition during the ejection from the grenade, entailing the further disadvantage that the generated smoke will disappear prior to the smoke canister reaching its ground target.

3 Besides, the smoke canister according to GB 1 415 274 is provided with discharge ports for the smoke to be generated by the charge when it is ignited by two ignition pellets, which parts are covered only by means of the adjacent smoke canister, or by means of a basis plate in the projectile, which constitutes a very unfavourable design as regards long time storage of such smoke canisters.

From DE 2 555 323 (Huber) there is known a smoke canister having a metal housing comprising a smoke composition based on hexachloroethane (HC), ZnO and Al powder, the smoke charge being pressed into the metal housing at a pressure of minimum 1300 kp/cm', and the ignition charge being pressed is into the smoke charge itself for thereby constituting an integrated part thereof. This type of smoke charge will only give a partial axial combustion and then towards the end of the combustion. This is due to the fact that the smoke charge is a so-called HC composition which is difficult to ignite, and in order to have a fairly satisfied smoke development from the start, the ignition charge or the ignition charges must be pressed approximately 25-30% down into the smoke charge. This involves, of course, the disadvantage that the space of the smoke charge is reduced considerably, which is further unfavourable for smoke charges to be effective in the infrared part or range of the electromagnetic spectrum.

A further disadvantage hampering this prior art smoke canister is that during the ignition of the smoke charge there is around the ignition charge formed a burning zone in the smoke charge. which burning zone comprises glowing particles which upon impact of the smoke canister against the ground will loosen and give an undesired break in the combustion and the associated smoke development. In other words, the glowing particles need some time before being able to provide a new effective combustion of the HC charge in the smoke canister, and in certain unfavourable cases 4 there exists a large risk for the combustion and thereby the smoke development to cease upon said impact.

DE 2 841 815 (Prghauser), an additional patent related to the previously mentioned DE 2 555 323, still relates to the problems concerned with the smoke development in the initial phase. According to DE 2 841 815 there has now been introduced a time delay unit which through an opening in the central tube is ignited by the expelling charge and then ignites the ignition charge which has been pressed into the smoke charge, which smoke charge still comprises a substan tialiy heavily ignitable hexachloroethane composition.

However, as with the smoke canister according to DE 2 555 323 neither this smoke canister can be repaired because the ignition charge representing the shelf life limiting parameter, has been pressed into the smoke charge as an integrated part thereof. Also in this case it is a token about a substantial axial combustion only at the end of the combustion and smoke developing process, and nowhere is there suggested any means which initially operate as a closed unit but which upon influence by heat and/or pressure will exhibit the smoke charge in a specific sequence depending on the advancing burning front in the smoke charge.

DE 3 048 147 (Gottschalk) is also an additional patent to DE 2 555 323 and is also related to the mentioned DE 2 841 815, and concerns a further effort to achieve satisfactorily smoke generation at the time of ignition. According to DE 3 048 147 it is suggested to press in additional quantities of more energetic HC charge (including more Al powder) in order to secure satisfied ignition and smoke development.

However, closer to 40% of the length of the smoke canister is comprised by a very complicated compound ignition charge, and it is uncertain whether the combustion can be defined as axial since not only the initial burning but also the final burning will be very uneven and thereby be very unsatisfac tory, especially in connection with IR screening.

This prior art technique is in fact a result of the smoke charge being an HC composition, which entails a complicated design not only of the smoke charge but also of the associated ignition charges. Demilitarisation and/or repair is out of the question by this type of smoke canisters. which means that old smoke canisters must be destroyed by burning, which, of course, is unfavourable for the environment.

DE 3 129 146 (Grau) relates to a smoke mortar wherein are used end covers, but not any end cover which at the same time carries an ignition charge for the respective smoke charge. It is true that DE 3 129 146 suggests an ignition channel in the one end of the smoke canister, but also here it is a token about an ignition charge extending axially a fair distance into the smoke charge itself, which renders axial combustion of the smoke charge impossible during the ignition phase of the smoke generation, a fact which is specifically unfavourable in connection with the IR part or range of the electromagnetic spectrum.

Obiects of the invention An object of the present invention is to provide an arrangement in a smoke grenade which after ignition of the smoke charges of the smoke canisters renders a so to say constant smoke generation.

Another object of the present invention is to provide an arrangement in a smoke grenade in which the smoke charge will be ignited only in the immediate vicinity of the ground, for thereby rendering better smoke screening in the target ground area.

Still another object of the present invention is to provide an arrangement in a smoke grenade in which any unfavourable pressure development in the smoke chambers is avoided, for 6 thereby obtaining a constant burning rate of the smoke charge.

Still another object of the present invention is to provide an arrangement in a smoke charge canister giving a robust design thereof, the smoke charge canister being designed for the smoke to escaspe through the central tube and then at both ends thereof, which renders a greater possibility for open smoke discharge paths when the smoke canister has reached the predetermined ground target.

Yet another object of the present invention is to provide a smoke charge canister having a design for simple demounting, which is specifically important in connection with ammuni- tion which can be stored for several decades. Thereby the ignition/delay unit which is usually the limiting factor regarding the shelf life of the ammunition, can easily be replaced, which is of great economic and environmental advantage since destruction or burning of ammunition is thereby avoided.

Another object of the present invention is to provide a smoke charge canister having end plates remaining stable and giving a proper protection for the smoke charge in the associated smoke charge canister, both regarding long time storage, and regarding launching when said canisters are subjected to a pressure of 600-700 bar, and further regarding burning stability when said canisters impinge on the ground target.

Brief disclosure of the invention

Said objects as well as other objects of the present invention are achieved by an arrangement of the type given in the preamble, which according to the present invention is characterized in that the one end part of each smoke charge canister comprises one or more means which initially operate as a closed unit but which upon being influenced by 7 heat and/or pressure, exhibit the smoke charge for continued substantially axial combustion.

In accordance with a preferred embodiment the invention is characterized in that the one or more means provided at the one end part of each smoke charge canister comprise one or more second initially closed openings which are located further away from said end part than said first opening or openings, and that the one or more second openings individu- ally comprise closing means which can be influenced to open its respective second opening by being influenced by heat andlor pressure.

Since the smoke charge will be ignited at one or more points is in the upper portion of the smoke charge canister, it can be avoided that the smoke charge will burn radially, but rather be ensured that the burning will take place along the length of the smoke charge canister, like a cigarette. The burning surface will then be approximately constant during the entire combustion, which is also the case as regards the development or generation of smoke.

A further feature of the present invention is the fact that the ignition opening provided at the most distant one end part of the smoke charge canister communicates with an ignition charge arranged in said smoke charge canister and possibly comprising a delay charge for delayed ignition of respective smoke charges after the ejection of the smoke charge canister from the grenade shell.

This involves that the ignition of the smoke charge can take place in the immediate vicinity of the ground, and together with the approximately constant burning surface during the entire combustion and thereby also an approximately constant smoke generation, such smoke charge canisters according to the invention will become significantly more effective.

A further feature of the invention is the fact that the one 8 end part of each smoke charge canister comprises one or more first far distant ignition openings communicating with said ignition charge/delay charge, as well as one or more second initially closed openings which are located at a longer distance from said end part than said first mentioned openings, said second opening or openings individually comprising closing means which can be influenced to open the associated second opening by the influence of heat andlor pressure. 10 Such openings or perforations in the central tube can for example be closed with plugs which are pressed in from the centre, and when the burning front is at level with said plugs which can be affixed or blocked by means of fuse is elements they will be pressed out into the central tube, which entails that the pressure in the smoke chamber will be relieved and the burning rate thereby being maintained at an approximately constant level.

Preferably there may be provided so many perforations or openings that the ratio between the burning surface and the discharge area should not exceed 10. In this manner there will be ensured an even burning rate during the entire combustion. 25 Further features and advantages related to the present invention will be discussed in the following with reference to the appending drawings which illustrate non-limiting embodiments of the present invention. 30 Brief description of the drawings

Fig. 1 is a section through a schematically depicted smoke artillery grenade, wherein the arrangement according to the 35 present invention can be applied.

Fig. 2 illustrates diagrammatically the last phase of the trajectory of a smoke artillery grenade, especially just 9 before, during and after ejection/ignition of the smoke charge canisters of the grenade.

Fig. 3 is a section through a first embodiment of a smoke charge canister manufactured in accordance with the teachings of the present invention.

Fig. 4 illustrates on a larger scale a cut-out of the section illustrated in Fig. 3.

Fig. 5 is a diagram illustrating the relation between the smoke generation from a smoke charge canister and the lapsed burning time for a prior art smoke charge canister featuring radial burning and a smoke charge canister according to the is invention based on axial burning, respectively.

Fig. 6 is a view partly in section seen from above of the smoke charge canister illustrated in Fig. 3.

Fig. 7 illustrates on a larger scale a detail of Figures 3 and 6.

Fig. 8 illustrates a section through a first embodiment of an end plate for a smoke charge canister according to the invention.

Fig. 9 is a section through a second embodiment of a smoke charge canister according to the teachings of the present invention.

Fig. 10 illustrates on a larger scale a cut-out of the section illustrated in Fig. 9.

Fig. 11 is a view partly in section seen from below along the lines XI-XI in Figures 9 and 12 of a second embodiment of an end plate for a smoke charge canister according to the invention.

Fig. 12 is a section through the end plate illustrated in Fig. 11 taken along line XII-XII thereof.

Fig. 13 illustrates on a larger scale a further embodiment of structural features of the smoke charge canister according to the present invention.

Fig. 14 illustrates on a larger scale a still further embodiment of structural features of the smoke charge canister according to the present invention.

Detailed description of embodiments

In Fig. 1 which illustrates a section through a smoke artillery grenade which generally is designated by reference numeral 1, there is depicted that such a grenade comprises a front housing 2 holding an ejection/ignition charge 3, as well as a substantially cylinder-shaped grenade shell 4 housing a plurality of axially consecutively arranged smoke charge canisters Sa-5d, here illustrated in for example a number of four. Each of said smoke charge canisters Sa-5d. comprise an individual axially extending central tube 6a, 6b, 6c and 6d, respectively, which together constitute a centrally extending tube 7 in said smoke grenade 1, which tube 7 is provided with openings, which will be discussed in detail later, and through which openings flames from the ejection/ignition charge 3 ignite the individual smoke charges 8a-8d in each smoke canister 5a-5d, the smoke canisters 5a-5d being ejected out through the bottom 9 of the grenade shell 4.

In Fig. 2 it is diagrammatically illustrated how this ignition and ejection of the smoke canisters course takes place when a smoke artillery grenade 1 is at the end of its trajectory 10, the reference 1' illustrating the grenade prior to the ignition of the ejection/ignition charge, i.e. during phase I, whereas reference numeral V' illustrates the smoke artillery grenade after the flames of the 11 ejection/ignition charge 3 have ignited the smoke charges 8a-8d in each smoke charge canister Sa-5d, at the same time as the individual smoke charge canisters Sa-Sd are ejected out from the grenade V' through the bottom 9 thereof, i.e.

at the same time as also the bottom plate- 9' is detached from the grenade shell 4.

The ejection phase which is illustrated at II in Fig. 2, takes place whilst the smoke charge canisters 5a-Sd are far above the ground 11, which means that it will take a relatively long time before the landing of the smoke canisters. As appearing from phase III in Fig. 2, the ignited smoke canisters Sa-5d continue along a steeper trajectory 10' than what was the case for the empty grenade is ifle, and depending upon the ejection/ignition point of the smoke artillery grenade the ejected and ignited smoke canisters Sa-Sd will after some time land on the ground 11, as this is illustrated at phase IV in Fig. 2, and then in the vivinity of a target 12, for example an armoured fighting vehicle.

According to the invention, it is aimed for having the cylindrical smoke charge canisters 5a-5d having their smoke charges 8a-8d ignited as close to the ground 11 as possible, and at the same time the smoke generation should be as even and effective as possible, for thus to generate an optimal screening effect of the target 12 in the vicinity of which said smoke canisters 5a-Sd will land.

In Fig. 3 which is a section through a first embodiment of a smoke charge canister 5, in accordance with the present invention, this canister comprises an end plate 21, a central tube 6 corresponding to the previously discussed central tubes 6a-6d, respectively. In this central tube 6 there is in the area of the disclosed end plate 21 provided one or more ignition openings or perforations 24, and said perforations 24 communicate with one or more ignition charges 25a, 25b, appropriately arranged on each side of a 12 time delay charge 26, said ignition charges 25a and 25b as well as the time delay charge 26 appropriately being mounted in a suitable tube 30, for example a steel tube. When such a smoke charge canister 5 is in a smoke artillery grenade 4, as for example illustrated in Fig. 1, the-smoke charge canister 5 will at a given point in the trajectory of the smoke artillery grenade be ejected from the grenade through the bottom thereof by means of the ejection/ignition charge, and the flames from the ejectionlignition charge will ignite the ignition charge 25a through said perforations 24, and after a certain time of delay due to the time delay charge 26, the inner ignition charge 25b will ignite the smoke charge 28 in the smoke charge canister 25, which smoke charge 28 is surrounded by an outer tube 29 which together with an end plate 31 which is provided opposite said first end plate 21, and said central tube 6 defines the outer surfaces of the canister 5, i.e. a smoke chamber 33.

In addition to one or more first outermost ignition openings or perforations 24 as discussed previously, which communi cate with said ignition charge or charges 25a and 25b through an intermediate time delay charge 26, there are in the central tube 6 provided a plurality of further means which initially operate as a closed unit, but which upon being influenced by heat andlor pressure, exhibit the smoke charge 28 for continued substantially axial combustion. In the illustrated embodiment of Fig. 3, such means take the form of further, initially closed openings or set of openings, designated by 24a, 24b and 24c, respectively, said openings being located further away from said end part, i.e.

further away from said end plate 21 than said first mentioned opening or openings 24.

Each of these further means or openings 24a-24c-comprise, as this is illustrated both in Fig. 3 and on a larger scale on Fig. 4, closing means 27 which can be influenced to open up the associated opening or hole under the influence of heat and/or pressure. Preferably such closing means can be 13 implemented as a plug 27 which is pressed into the tube 6 from the smoke canister, i.e. from the inner of the central tube 6, said plug 27 possibly being attached to the area of said hole or opening, for example the hole 24a by means of a heat fusing material, preferably a melting fuse 32, such a melting fuse melting when the burning front of the smoke charge 28 approaches the level of the respective plug 27, which in turn will entail that the plug or plugs are pressed out from the central tube 6 for thereby releasing the pressure in the smoke chamber 33 in which the smoke charge 28 of the canister is housed.

It is to be understood that the number of first openings or perforations 24 provided at the one end part of the canister is 5, especially in the area of the end plate 21, can be varied within wide limits, said number and location as well as size also being varied according to which requirements are to be met for the initial axial burning of the smoke charge in the smoke canister in question.

Further, it is to be understood that the distribution and the number of said further pressure releasing openings 24a24c can be made in groups and with a number and dimensions thereof, which can be varied within wide ranges. Appropri- ately, such a distribution of the number and the dimensions of said perforations may correspond approximately to preferably more than 1110 of the axial burning surface in question.

Further, it is to be understood that the previously discussed openings and the opening areas thereof can be chosen depending on the selected smoke composition of the smoke charge canisters.

It should also be understood that the heat melting material can take the form of a sleeve or a piece of tube which appropriately can be mounted in the vicinity of said further openings 24a-24c.

14 The novel features of the present invention thus involve that the substantially cylindrical smoke charge canister 5, as this specifically appears from Fig. 3, is ignited through one or more ignition openings or perforations 24 provided at the one end part of the central tube 6, for thereby initiating axial combustion of the smoke charge 28. Since the smoke charge 28 is ignited through one or more time delay charges 26 in the upper part of the central tube 6, the ignition of the smoke charge 28 will take place in the immediate vicinity of the ground, as this appears from Fig. 2, see especially phase III and phase IV thereof.

Since the smoke charge 28 is ignited at one or more points at the one, for example the upper part, of the smoke charge canister 5, the smoke charge 28 will not burn radially as is the case in many previously known smoke charge canisters, but all the time burn similarly to a cigarette along the longitudinal extension of the smoke charge canister 5.

In Fig. 5 there is illustrated a comparison between the smoke development from smoke charge canisters for artillery grenades, the curve A illustrating the smoke development or generation in previously known smoke charge canisters having a smoke charge burning radially from the centre and outwardly therefrom. The smoke generation which is determined by the combustion surface, will then be proportional with the progress of the smoke generation, and as it appears from Fig. 5, this will for a 155 mm grenade mean that the smoke development will increase from 10 g/sec. from the time of ignition, to approximately 70 g/sec. after approximately 50 seconds, which in turn means 7 times as large a smoke generation at the end of the combustion compared with the initiated smoke generation. Such a smoke generation which is based upon radial combustion of the smoke charge will entail that the screening to be provided by the smoke will be very uneven, not only due to the altering smoke generation, but also due to the increasing heat lift due to is increasing quantities of energy being released per time unit through the exothermic chemical reactions. By increased heat lift the smoke will rise faster into the air and the effect of the screening will be correspondingly reduced and specifically unfavourable in connection with low wind speed conditions.

In Fig. 5 there is also illustrated a diagram B for the smoke development provided by a smoke charge canister according to the present invention. Since the smoke charge is ignited at only one or possibly several points at the upper part of the smoke charge canister. the combustion of the smoke charge will take place similarly to a cigarette, namely along the longitudinal extension of the smoke canister. The combustion surface will then remain constant during the entire combustion, which also will be the case regarding the smoke generation. If for example the length of the smoke canister is equal to the diameter of the canister, there will be achieved a combustion distance which is twice as long in this type of combustion according the present invention. see Fig. 5 namely up to 100 seconds in relation to only 50 seconds by prior art technique, the constant combustion and generation of smoke according to the invention involving a substantial reduction of the heat lift. The arrangement according to the present invention will thus give instructions for a smoke charge canister which is significantly more effective compared to prior art technique.

In order to avoid a pressure build-up in the smoke chamber 33 during the combustion of the smoke charge 28, which will entail an increased combustion velocity, the central tube 6 has been provided with further perforations 24a-24c which appropriately is closed with plugs 27 which can be pressed in from the centre. When the axial burning front is at level with these plugs 27, which can be affixed with appropriate melting fuses 32, they will be pressed out from the central tube 6, the pressure in the smoke chamber 33 at the same 16 time being relieved, and there is in this manner ensured an even burning rate during the entire combustion.

In Fig. 6 which illustrates a top view, partly in section, of the smoke charge canister 5 in Fig. 3,_it is depicted how the central tube 6 is supported between the upper end plate 21 and the lower end plate 32 arranged at the second end of the smoke charge canister 5, see also Fig. 3.

In Fig. 6 it is also depicted that in the area of the one end part of thesmoke canister 5 there are provided for example four radially extending tubes 30, which individually hold a first ignition charge 25a placed at the opening 24 provided in the central tube 6, as well as the intermediate time delay charge 26 and the inner ignition charge 25b which communicates with the smoke charge 28 of the smoke canister 5. In Fig. 7 there is on a larger scale illustrated the tube 30 including the time delay charge 26 placed between said ignition charges 25a and 25b, respectively, which tube 30 has been provided with key holes 30a.

In Fig. 8 there is illustrated a section through an appropriate embodiment of the substantially circular end plate 21, and this end plate 21 is here equipped with an edge 35 running along the outer circumference thereof and merging into outer threads 36 which can be affixed to corresponding outer threads 37 provided at the upper end portion of the outer tube 29 of the smoke charge canister 25, see also Fig. 3. Further, the end plate 21 is provided with an inwardly protruding flange 39 running around a central opening 38 and wherein are provided one or more through-going, substantially radially extending channels 40 and in the walls of said channels there may appropriately be provided threads or any other appropriate fastening means for fastening thereinto a tube similar to the previously discussed tube 30, which in turn houses ignition charges and time delay charges, all of which being adapted in relation to said further openings or perforations 24a-24c of 17 the central tube 6. Correspondingly, in the opposite end plate 31 there may be provided radial threads 36a allowing for being screwed onto corresponding threads 37a in the lower end portion of the outer tube 29 of the smoke canister 5, see Fig. 3. Both end surfaces are appropriately provided with key holes 42a and 42b, respectively.

In Fig. 9 which illustrates a section through a second embodiment of a smoke charge canister 105 according to the present invention, this embodiment also comprises an end plate 121, a central tube 106 having one or more ignition openings or perforations 124 provided in the area of said end plate 121, said perforations 124 communicating with one or more ignition charges 125a, appropriately provided ajacent a time delay charge 126, said charges 125a and 126 here being mounted between a supporting or carrying plate and an inwardly protruding flange 139 of said plate 121, running around a first central opening 138a having a smaller diameter corresponding to the inner diameter of the central tube 106, and a second central opening 138b, having a larger diameter corresponding to the outer diameter of the central tube 106. Said semi-circular recesses 140 have been made in order to house said combination of charges 125a and 126, see also Figures 11 and 12 illustrating a bottom view and a section through said end plate 121, respectively. Such a supporting or carrying plate 130 is specifically advantage ous for easy and effective assembly of said smoke charge canister 105, and renders favourable protection against any displacement of said changes when the canister hits the ground after being ejected from the grenade in question. In addition to said first upper ignition openings or perfora tions 124 there are also in this case provided a plurality of initially closed openings 124a, 124b and 124c, said openings being located further away from the end ingition openings 124, i.e. further away from said end plate 121 than said first openings 124.

As illustrated specifically on Fig. 10 each of said further 18 openings 124a-124c are provided with a plug 127, in this case the hole 124a, said plug 127 being attached in said hole by means of a fuse 132 which will melt when the burning front of the ignited smoke charge 128 surrounded by an outer tube 129 and said central tube 106 defining a smoke chamber 133, will be at the level of said plug 127. Also the canister 105 is provided with a second end plate 131 opposite of said previously discussed end plate 121.

As appearing from Figures 11 and 12 there is here illustrated four radially extending recesses 140 each holding the combination of ignition charge and time delay charge as discussed previously, and said end plate 121 is at the circumference thereof provided with outer threads 136 fitting inner threads 137 at the upper end of the canister circumferential tube 129, see also Fig. 9.

Correspondingly, the bottom plate 131 is provided with outer threads 136a fitting inner threads 137a at the bottom portion of the same canister outer tube 129. Both end plates are appropriately provided with key holes 142a and 142b, respectively.

The assembly of the smoke charge canister 5 as illustrated in Figures 3-4 and 7-8 as well as the smoke charge canister 105 illustrates in Figures 9-12 will allow for easy mounting and demounting. This is specifically important in connection with ammunition which can be stored over several decades. Thereby the ignition/time delay charge which is usually the limiting factor as regards the shelf life of the ammunition can easily be replaced. This involves large economic and environmental advantages since in this manner one will avoid the burning of ammunition.

Modern observation expedient does not operate only in the visual part or range of the electromagnetic spectrum, but also in the infrared range (IR) as well. Artillery grenades have as their most important task to prevent hostile 19 observation not only in the visible range, but also in said IR range. Also this is taken care of by the present invention, because IR smoke charges which are also effective in the visible range of the spectrum, are based on a combination of emission and absorption in - the IR range and scattering in the visual range. This combination involves that it is quite crucial that the smoke generation from a smoke charge canister is even, for thereby ensuring a uniform smoke emission during the combustion.

According to the present invention the effect of the emission in the previously discussed smoke charge canister will be in the range of twice as effective as a smoke canister having radial combustion because the combustion is proportional to the burning time. The ratio between the present type of smoke canister and a conventional canister, as regards absorption in IR, is not so significant. The overall degree of screening will with the same quantity of smoke charge be substantially improved due to the present invention, which is not only economically advantageous, but will also reduce the burdening on the environment because, totally, it is not necessary to fire so many grenades. This is of special importance when regarding exercises in peace time on military firing ranges where environmental burdening is specially in focus.

In Fig. 13 there is illustrated a further embodiment of an end part of a central tube 206 to be included in a smoke charge canister according to the present invention, wherein said central tube 206 is provided with one or more ignition openings or perforations (not illustrated) which communicates with previously discussed ignition charges which may be delayed prior to igniting the corresponding smoke charge. In addition to said first outermost ignition openings or perforations there are provided at plurality of initially closed openings 224a, 224n, these openings being located further away from the end portion of the central tube 206 than said first ignition openings.

These further openings 224a, 224n comprise closing means 227 which can be influenced to open the corresponding opening under the influence of heat andlor pressure, and can also here be designed as a plug which has been-pressed in from the centre of the central tube 206, but here being covered by or made integral with an outer pipe-shaped meltable fuse 232, this meltable fuse being melted when the combustion front of the burning smoke charge will be at level with the associated plug 227, whereby said plug will be pressed out from its associated opening and release the pressure in the smoke chamber wherein the smoke charge of the canister is housed.

In Fig. 14 there is illustrated a further embodiment of an end psrt of a central tube 306 also provided with uppermost ignition openings or perforations (not illustrated). In addition to said first outermost ignition openings or perforations communicating with one or more ignition charges and possible a time delay charge, there are in the central tube 306 provided a plurality of further openings 324a, 324n, which further openings are located further away from the end portion of said central tube 306 than said first ignition openings, and which in this specific embodiment have been drilled under an angle different from perpendicular in relation to the longitudinal axis of said central tube 306, i.e. with an appropriately slanting angle.

Also here the further openings 324a, 324n are closed with plugs 327 and are covered with an outer sleeve or tube 332 of fusiblelmelting material, which will melt when the combustion front of the burning smoke charge approaches the level of the respective plug 327 for thereby pressing the plug in question out of the central tube 306 and thereby reducing the pressure in the smoke chamber.

Because the arrangement according to the present invention gives instructions for a smoke charge canister which is ignited only at the one end through one or more time delay 21 elements, it is achieved not only that the smoke charge canisters will come into operation only in the immediate vicinity of the ground target, but also that the smoke charge then through its cigarette-like burning manner will render a continuous and uniform smoke generation during the entire combustion. By also taking precautions for pressure release in the pressure chamber during the combustions, there is also achieved a further safety precaution for the combustion to take place in a uniform manner and with an optimum heat development and heat lift. Thereby is achieved an effective screening not only in the visible range but also an effective screening in the IR range wherein the emissive screening is the dominating parameter.

22 c 1 a Arrangement in a smoke charge canister (1), especial ly a smoke charge artillery grenade, comprising a front housing (2) holding an ejection/ignition charge (3), as well as a substantially cylinder-shaped grenade shell (4) holding a plurality of axially, consecutively arranged smoke charge canisters (5a-5d) defining or communicating with an axially extending central tube (7) having one or more openings (24) through which the flames from the ejection/ignition charge (3) initiates the ignition of the smoke charge (8a-8d) of said smoke charge canisters (5a-5d), said smoke charge canisters (Sa-5d) being ejected through the bottom of said grenade shell (4), and each smoke charge canister (5, Sa-5d) being provided with one or more ignition openings or perforations (24) only at its one end portion (21) for initiating an axial combustion of said smoke charge (28), c h a r a c t e r i z e d i n that the one end portion of each smoke charge canister (5) comprises one or more means which initially operate as a closed unit, but which upon being influenced by heat andlor pressure exhibit the smoke charge (28) for continued substantially axial combustion.

2. Arrangement as claimed in claim 1, c h a r a c t e r i z e d i n that the means arranged at the one end portion of each smoke charge canister (5) comprise one or more second originally closed openings (24a 24c) which are located further away from the end portion than said first opening or openings (24), and that the second opening or openings (24a-24c) individually comprises closing means (27, 32) which can be influenced to open its respective second opening (24a-24c) under the influence of heat and/or pressure.

3. Arrangement as claimed in claim 1 or 2, c h a r a c t e r i z e d i n that each closing means comprises a plug (27) which has been pressed into one of 23 said second openings (24a-24c).

4. Arrangement as claimed in claim 3, c h a r a c t e r i z e d i n that the plug (27) has been pressed into the respective opening.(24a-24c) from the centre, and that the plug (27) has been affixed to the area of the hole (24a) by means of a heat melting material, appropriately a melting fuse (32), such that when the combustion front of the burning smoke charge (28) approaches the level of the plug (27) the melting fuse (32) will melt and the plug (27) be pressed out in the central tube (23) for thereby releasing the pressure in the smoke chamber (33) of the smoke charge canister (5).

is 5. Arrangement as claimed in claim 4, c h a r a c t e r i z e d i n that the heat melting material comprises one melting fuse for each hole (24a-24c), or are provided as a sleeve or small tube (232; 332) arranged for encircling said holes (224a; 324a).

6. Arrangement as claimed in any of the claims 2-5, c h a r a c t e r i z e d i n that said further openings (24a-24c) are distributed or grouped with a number and dimensions corresponding to approximately and preferably more than 1110 of the combustion surface in question.

7. Arrangement as claimed in claim 6, c h a r a c t e r i z e d i n that the number of openings (24a-24c) and the cross sectional area thereof are chosen in dependency of the selected smoke composition of the smoke charge canister (5).

8. Arrangement as claimed in claim 1, c h a r a c t e r i z e d i n that the means arranged at the one end part of each smoke canister (5) comprises a melting sleeve covering one or more second openings being located further away from said end part than said first openings (24), which melting sleeve under the influence of 24 heat will successively exhibit said further openings in pace with the progress of the axial combustion.

9. Arrangement as claimed in claim 1, c h a r a c t e r i z e d i n that the melting sleeve (232; 332) surrounds a plurality of radially arranged holes (224a; 324a).

10. Arrangement as claimed in claim 8, c h a r a c t e r i z e d i n that the melting sleeve (332) surrounds a plurality of further holes or channels (324a) extending under a slanted angle in relation to the central axis of the smoke canister.

is 11. Arrangement as claimed in claim 1, c h a r a c t e r i z e d i n that the one or more ignition openings (24) provided at the outer one end part (21) of the smoke charge canister (5), communicate with an ignition charge (25a, 25b) arranged in the smoke charge canister (5) and possible comprising a time delay charge (26) for delayed ignition of respective smoke charges (28) after the ejection of the smoke charge canisters (5a-5d) from the grenade shell (4).

12. Arrangement as claimed in any of the preceding claims, c h a r a c t e r i z e d i n that in the area of the end part (21) of the smoke charge canister (5) there is provided a radially extending tube (30) housing at least one ignition charge (25a) facing towards the central tube (26), one or more time delay charges (26) adjacently arranged in said tube (30), as well as an inner ignition charge (25b) communicating with the smoke charge (28) of the smoke canister (5).

13. Arrangement as claimed in any of the claim 1-12, c h a r a c t e r i z e d i n that in the area of the end part of the smoke charge canister (5) there is provided a substantially circular end plate (21) which along an outer circumference is provided with attachment means, for example threads (36) which can be fastened to corresponding means, for example corresponding threads (37) provided at the end portion of the outer tube (29) of the smoke canister (5), and that the end plate (21) is provided with an inwardly protruding second flange (39) around a central opening (38) and wherein is provided one or more through- going substantially radially extending channels (40).

14. Arrangement as claimed in claim 13, c h a r a c t e r i z e d i n that said substantially radially extending channel or channels (40) are equipped with inner threads (41) for screwing thereinto a premounted is ignition/delay charge (25a, 26, 25b), for example taking the form of an outwardly threaded tube (30) housing said ignition/delay charge (25a, 26, 25b).

15. Arrangement as claimed in any of the claims 1-12, c h a r a c t e r i z e d i n that in the area of the end part of the smoke charge canister (105) there is provided a substantially circular end plate (121) which is provided with an inwardly protruding flange (139) arranged around a central opening (138) and wherein is provided one or more substantially radially extending recesses (140) in which recesses (140) there are mounted ignition/delay charge (125a, 126, 125b) as well as a supporting/carrying plate (130) for supporting said ignition/delay charge during handling.

16. Arrangement as claimed in claim 15, c h a r a c t e r i z e d i n that the inwardly protruding flange (139) has a diameter which is between 112 and 2/3 of the diameter of the smoke charge canister (105) or the remaining end plate (121), and that the number of recesses (140) can be varied from 3 to 8.