CA1150108A - Propellant charge igniter with an electrical ignition system in middle zone of a flame guiding duct - Google Patents
Propellant charge igniter with an electrical ignition system in middle zone of a flame guiding ductInfo
- Publication number
- CA1150108A CA1150108A CA000378487A CA378487A CA1150108A CA 1150108 A CA1150108 A CA 1150108A CA 000378487 A CA000378487 A CA 000378487A CA 378487 A CA378487 A CA 378487A CA 1150108 A CA1150108 A CA 1150108A
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- igniter
- flame
- guiding duct
- ignition
- charge
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Abstract
ABSTRACT OF THE DISCLOSURE:
A propellent charge igniter for ammunition which comprises an electrical ignition system and an ignition charge operatively associated therewith housed in a flame-guiding duct, the electrical ignition system being positioned in a middle zone of the flame-guiding duct and being adapted to supply an ignition impulse in both the forward and rearward directions with respect thereto. And a shell which comprises a cartridge case housing a such propellent charge igniter.
A propellent charge igniter for ammunition which comprises an electrical ignition system and an ignition charge operatively associated therewith housed in a flame-guiding duct, the electrical ignition system being positioned in a middle zone of the flame-guiding duct and being adapted to supply an ignition impulse in both the forward and rearward directions with respect thereto. And a shell which comprises a cartridge case housing a such propellent charge igniter.
Description
r~
This in~ention relates to a propellent charge igniter for ammunition, and a shell which comprises a cartridge case housing a such propellent charge igniter.
A~nunition may be ignited using a class of igniters which is usad together with a powder cartridge and has a flame guiding tube made of metal. The flame-guiding tube has an ignition charge arranged therein and is intended to provide a uniformly distributed igniting flame in the charge chamber of the cartridge case. The igniting flame is produced by a pressure-tight screw element having an electric fuse element situated in the base of the cartridge case, that is to say, at one end of the flame-guiding tube.
When a short igniting time is to be provided for, which is preferably the case, it is possible for considerable pressure differences to be set up between the base of the cartridge case and the base of the projectile, that is to say, in the charge chamber filled with the propellent charge powder, if the radial discharge openings of the flame-guiding tube which are adjacent the hase of the cartridge case are the first to be opened, as is frequently the case. This can sometimes lead to undesirable phe~omena, including strong pressure loads on the grains of propellent, which at low temperatures often leads to the destruction of the grains, and in turn causes unexpected increases in gas pressure or superimposition of the pressure wa~e reflections, likewise connected with increases in gas pressure, and bulging of the gun barrel. For these reasons, it is necessary to extend the firing operatLon over a relatively long time. With may guns, this leads to an increase in the minimum firing time or, with automatic weapons, to a restriction in the rate of firing.
In the course of de~eloping more accurate weapon systems with a greater fire power, the external cartridge volume and -the weight oE the cartridge have also come to play a decisive part. The fire power can be consider-ably increased by reducing the weight of the cartridge case, because the time required for discharging the fired cartridge case can then be considerably reduced. In addition, the problems of ammunition storage and of storage of empty cartridge cases, more particularly in armoured fighting vehicles, are reduced when using light and/or relatively small cartridges.
For this reason so-called 1' combustible cartridge cases"
have been developed, which sometimes onl~ comprise a metallic base fox sealing purposes in the cartridge chamber as non-combustible cornponent which needs to be disposed of.
~ ccording to the present invention, there is provided a propellent charge ingniter Eor ammun:Ltion which comprises an electrical ignition system and an ignition charge operatively associated therewith housed in a flame-guiding duct, the electrical ignition system being positioned in a middle zone of the flame-guiding duct and being adapted to supply an ignition impulse in both the forward and rearward directions with respect thereto.
According to one aspect of this invention, there is provided a propellent charge igniter for ammunition -comprising a propellent charge and a projectile, which igniter comprises an electrical ignition system and a flame guiding duct formed as an elongate duct having an ignition charge housed therein and intended to be emplaced in said propel-lent charge to extend from the base side thereof, being the end thereof remote from the projectile and at which side connection to electric supply means is to be provided, the electrical ignition system of the igniter being arranged in a middle zone of the flame guiding duct extending length-wise thereof such that the ignition impulse of tha ignit1on ~ .
- ~ 2 --system is propagated in the i~nition charge both towards the rear and the front o~ the flame guidi~g duct.
According to the present incention, there is also provided a shell which comprises a cartridge case housing a propellent charge igniter as above described, and which carries a projectile in a Eorward region thereof.
With an igniter according to this invention, the housing comprises a material which do not consume any energy during the burning, but supplies additional energy to the system and as a result causes an internal ballistic increase in efficiency of ~he ammunition. The exothermic effect is pro~ided by a secondary material the proportion of which in the flame guiding ducts can then be so chosen to be sufficient - for the exothermal reaction of the flame-guiding duct to be reliably guaranteed.
Suitable secondary explosives include, Octogen, more expecially ~-Octogen, hexanitrostilbene, triamino-.guanidine nitrate, hexanitrodiphenyl ether or dipicrylsulphone; binders which can be used include polyester ~0 resins, as well as polyurethanes or other synthetic plastics materials having satisfactory burning properties.
A flame-guiding duct during the initiation of uniform distribution of the igniting flame in the load chamber containing the propellent powder, is consumed by burning, in exothermic reaction, thereby making a positive, internal ballistic energy contrihution to the increase in efficiency of the igniter, is to be distinguished from flame-guiding ducts formed of so-called consumable materials, ; e.g. synthetic plastics materials such as polyvinylchloride, or even cardboard, which burn more slowly and contribute nothing to the desired internal ballistic increasP in efficiency, and even consume energy required for the combustion.
A flame-guiding duct of an.igniter as discl.osed herein has the ad~antage over such ducts when formed of metal, of being readily shaped, for example by pressin~r so that any desired shape of igniter can be produced in a simple manner.
Moreo~er, ~
- 3a -the flame-guiding duct prossesses a high mechanical stability against bending, vibration and .impact.
The ignition charge which is arranyed in the flame-guiding duct can for example be in the form of a plurality of strands of black powder arranged parallel to one another, being, in particuIer, preferably a black powder with a low sulphur content, the so-called Benite strands.
However, what is most preferred-are ignition charges made up from thermal mixtures free from inflammable matter and also referred to as a hot particle ignition compositions;
these compositions comprise inorganic reducing and oxidising agents~ for example boron and potassium nitrate. Such mixtures have a low gas cuntent, burn away at high temperature and are more suitable than other ignition charges because of the lesser tamping action which they require; tamping is only generally feasible to a considerable extent with flame-guiding ducts made of metal. ~n ignition charge consisting .of such a thermal mixture can, for example, be made up in the form of a plurality of annular, pressed tablets arranged in succession in the fire-guide housing. The ignitiny flame emanating from the electric firing system can be propagaked through the central channel to the column of tablets. The tablets may if desired also be bonded by adhesives to the flame guiding duct.
Where an additional increase in the mechanical rigidity and dimensional stability of the flame-guiding duct is desired this may be achieved by use of reinforcing inlays in for example one of the following ways:
1. An inlay of wire mesh, which is preferably 0 . formed of combustible metal, for example aluminium, magnesium or pyrometal, or of boron.
This in~ention relates to a propellent charge igniter for ammunition, and a shell which comprises a cartridge case housing a such propellent charge igniter.
A~nunition may be ignited using a class of igniters which is usad together with a powder cartridge and has a flame guiding tube made of metal. The flame-guiding tube has an ignition charge arranged therein and is intended to provide a uniformly distributed igniting flame in the charge chamber of the cartridge case. The igniting flame is produced by a pressure-tight screw element having an electric fuse element situated in the base of the cartridge case, that is to say, at one end of the flame-guiding tube.
When a short igniting time is to be provided for, which is preferably the case, it is possible for considerable pressure differences to be set up between the base of the cartridge case and the base of the projectile, that is to say, in the charge chamber filled with the propellent charge powder, if the radial discharge openings of the flame-guiding tube which are adjacent the hase of the cartridge case are the first to be opened, as is frequently the case. This can sometimes lead to undesirable phe~omena, including strong pressure loads on the grains of propellent, which at low temperatures often leads to the destruction of the grains, and in turn causes unexpected increases in gas pressure or superimposition of the pressure wa~e reflections, likewise connected with increases in gas pressure, and bulging of the gun barrel. For these reasons, it is necessary to extend the firing operatLon over a relatively long time. With may guns, this leads to an increase in the minimum firing time or, with automatic weapons, to a restriction in the rate of firing.
In the course of de~eloping more accurate weapon systems with a greater fire power, the external cartridge volume and -the weight oE the cartridge have also come to play a decisive part. The fire power can be consider-ably increased by reducing the weight of the cartridge case, because the time required for discharging the fired cartridge case can then be considerably reduced. In addition, the problems of ammunition storage and of storage of empty cartridge cases, more particularly in armoured fighting vehicles, are reduced when using light and/or relatively small cartridges.
For this reason so-called 1' combustible cartridge cases"
have been developed, which sometimes onl~ comprise a metallic base fox sealing purposes in the cartridge chamber as non-combustible cornponent which needs to be disposed of.
~ ccording to the present invention, there is provided a propellent charge ingniter Eor ammun:Ltion which comprises an electrical ignition system and an ignition charge operatively associated therewith housed in a flame-guiding duct, the electrical ignition system being positioned in a middle zone of the flame-guiding duct and being adapted to supply an ignition impulse in both the forward and rearward directions with respect thereto.
According to one aspect of this invention, there is provided a propellent charge igniter for ammunition -comprising a propellent charge and a projectile, which igniter comprises an electrical ignition system and a flame guiding duct formed as an elongate duct having an ignition charge housed therein and intended to be emplaced in said propel-lent charge to extend from the base side thereof, being the end thereof remote from the projectile and at which side connection to electric supply means is to be provided, the electrical ignition system of the igniter being arranged in a middle zone of the flame guiding duct extending length-wise thereof such that the ignition impulse of tha ignit1on ~ .
- ~ 2 --system is propagated in the i~nition charge both towards the rear and the front o~ the flame guidi~g duct.
According to the present incention, there is also provided a shell which comprises a cartridge case housing a propellent charge igniter as above described, and which carries a projectile in a Eorward region thereof.
With an igniter according to this invention, the housing comprises a material which do not consume any energy during the burning, but supplies additional energy to the system and as a result causes an internal ballistic increase in efficiency of ~he ammunition. The exothermic effect is pro~ided by a secondary material the proportion of which in the flame guiding ducts can then be so chosen to be sufficient - for the exothermal reaction of the flame-guiding duct to be reliably guaranteed.
Suitable secondary explosives include, Octogen, more expecially ~-Octogen, hexanitrostilbene, triamino-.guanidine nitrate, hexanitrodiphenyl ether or dipicrylsulphone; binders which can be used include polyester ~0 resins, as well as polyurethanes or other synthetic plastics materials having satisfactory burning properties.
A flame-guiding duct during the initiation of uniform distribution of the igniting flame in the load chamber containing the propellent powder, is consumed by burning, in exothermic reaction, thereby making a positive, internal ballistic energy contrihution to the increase in efficiency of the igniter, is to be distinguished from flame-guiding ducts formed of so-called consumable materials, ; e.g. synthetic plastics materials such as polyvinylchloride, or even cardboard, which burn more slowly and contribute nothing to the desired internal ballistic increasP in efficiency, and even consume energy required for the combustion.
A flame-guiding duct of an.igniter as discl.osed herein has the ad~antage over such ducts when formed of metal, of being readily shaped, for example by pressin~r so that any desired shape of igniter can be produced in a simple manner.
Moreo~er, ~
- 3a -the flame-guiding duct prossesses a high mechanical stability against bending, vibration and .impact.
The ignition charge which is arranyed in the flame-guiding duct can for example be in the form of a plurality of strands of black powder arranged parallel to one another, being, in particuIer, preferably a black powder with a low sulphur content, the so-called Benite strands.
However, what is most preferred-are ignition charges made up from thermal mixtures free from inflammable matter and also referred to as a hot particle ignition compositions;
these compositions comprise inorganic reducing and oxidising agents~ for example boron and potassium nitrate. Such mixtures have a low gas cuntent, burn away at high temperature and are more suitable than other ignition charges because of the lesser tamping action which they require; tamping is only generally feasible to a considerable extent with flame-guiding ducts made of metal. ~n ignition charge consisting .of such a thermal mixture can, for example, be made up in the form of a plurality of annular, pressed tablets arranged in succession in the fire-guide housing. The ignitiny flame emanating from the electric firing system can be propagaked through the central channel to the column of tablets. The tablets may if desired also be bonded by adhesives to the flame guiding duct.
Where an additional increase in the mechanical rigidity and dimensional stability of the flame-guiding duct is desired this may be achieved by use of reinforcing inlays in for example one of the following ways:
1. An inlay of wire mesh, which is preferably 0 . formed of combustible metal, for example aluminium, magnesium or pyrometal, or of boron.
2. An inlay of non-metallic nature in the form of woven fabric or meshes, for example, of carbon ~graphite) or synthetic plastics fibre.
3. A fleece, preferably formed of cellulose or ni-trocellulose.
4. A non-combustible inlay of for example glass fibre in an amount of up to about 50% by weight, c`alculated on the total quantity, of a material which is disintegrated with the build up of pressure in the cartridge, or
5. A combination of any two or more of the ma-terials mentioned under 1 to 4, in the form of a laminated structure.
Furthermore, the flame-guiding duct may be con-structed with an at least partially porous structure thereby increasing its surface area so as to accelerate its exothermic combustion. For this purpose, a soluble salt, for example potassium nitrate, may be incorporated in one or more of the aforesaid materials from which the duct may be formed. After the formation of the flame-guiding duct, for example, by extrusion or pressing this salt is dissolved out, therefrom for example by application of water~ so that the required cavities are left.
When the flame-guiding duct of the igniter of this invention is made of two or more parts, these are - advantageously connected to one another by adhesive bonding.
In general, polyester resins and polyurethanes can be used for bonding the parts to one another as well as possibly also for fixing the flame-guiding duct in a metallic base screw which is generally arranged in the base of the cartridge case or for connection with other components. It is preferred to ~ q~
use those bonding agents which effect interconnection of those parts of the flame guiding duct which are to be bonded to one another by causing superficial dissolution or softening of said parts so that these can be directly bonded to one another and produce a homogeneous structure. Wlth a flame-guiding duct made of nitrocellulose, it is Eor example possible to use a nitrocellulose la~quer as such a bonding agent, the proportion of solvent le.g. acetone) in -the lacquer causing the softening of -the surface. After e~aporation of the solvent, practlcally nomore foreign substance is to be found at the point o connection. This bonding is termed herein-after herein " cross-linking" and is a form of solvent welding.
The aforementioned disadvantageous rises in pressure during the firing procedure are minimised and as a result the fire power of the ~eapon increased as a result of the Elame-guiding duct being formed as an elongated sleeve or tube, ln the central region of which the electric iring system is arranged. The electrlc firing system is so designed that a firing impulse is emitted from it, both into that portion of the flame-guide tube facing forwardly, i.e.
towards a projectile, and into the portion facing rearwardly.
The flame-guiding duct is preferably formed from two identical component sleeves or tubes. A separate electric firing element may be provided for each component sleeve, such elements being arranged between the two portions and being capable of simultaneous ,triggering. However, it is preferred to use only a single firing element, which comprises an axial recess extending completely therethrough and which enables the firing impulse to be transmitted to the side further from its firing bridge or its firing gap. Particu-larly suitable for this purpose is the form of current propagation element which is described in our British Patent Specification No. 1,344,932. Such elements comprise an insulating body of glass or ceramics wi~h a bore extending therethrough, on the end faces of which are provided laminated metal contacts. A firing bridge partially covers the contacts or possibly a firing gap may be formed between the said contacts. Such an element ensure that when there is central firing of the propellent charge of the igniter of this in-vention, a symmetrical propagation of flame from the centre towards the front and towards the rear in the direction of the base of the cartridge case is achieved. The longer travels or paths of the firing flame, which are necessary when firing from the base of the cartridge case occurs and which usually set up a higher pressure in order to penetrate axialIy through the entire charge chamber are avoided. It is thus possible to reduce the pressure necessar~ for the firing that is to say, to provide a weaker initiation o the firing and thus avoid the pressure waves caused by ignition. This allows shorter firing tim~s to be achieved and thus a reduction in the minimum firing time or an increase in -the rate of firing.
In contrast to conventional base ignition or fusing, fusing at the centre is all the more effective as the longer ~s the total length of the flame-guiding duct.
Central fusing is conse~uently generally to be used with a total length of at least 100 mm, although in individual cases, it is of course also possible for this to be used with shorter lengths of the flame-guiding tube, for example about 50 mm. The tubular flame-guiding duct generally extends at least approximately the length of the charge chamber in which the igniter is used, i.e. from the base of the cartridge case up to or close to the base of the pro-jectile. However, it is also possible for the duct to be made shorter, so that it only extends, for example, over ~4~
half the ax.ial length of the charge chamber. Whilst central fusing will be more applicable to full length flame-guiding ducts occupying the length of the charge chamber, it can be used when the flame-guiding ducts do not extend this length, nevertheless.
The central firing of the flame-guiding ducts is particularly advantageous when the flame-guiding ducts comprise a material which reacts exothermally, since it still permits a favourable constructional form of igniter with an excellent igniting behaviour to be devised. The insulating body of the current propagation element as aforesaid can be made of exothermally combustible material, for example nitrocellulose, ibre-reinforced material such as epoxide resin with glass fibre fabric or of other combustible material, instead of being made of for example glass or ceramic material.
Central fusing may be employed in principle with flame-guiding ducts of so-called inflammable material in general or even~
.of metal, since it permits a favourable pressure curve to be sent up during the initiation phase and thus a shortening of the initiation or ignition. With metal flame-guiding ducts, it is then obviously necessary for at least one of the lines for the electric firing system to be guided to the central firing system while insulated from the sleeve base, while the flame-guiding duct itself can serve as an earthing connection.
However, with flame-guiding ducts of exothermally burning material, which simultaneously constitute an electric insulator, it is possible in a very simple manner to provide a suitable metal~coating of the surface thereof or any desired electrical wiring for contacting of the firing system.
A wide range of processes, such as screen-printing, adhesive and electrodeposition processes can be used for the metal coating of the combus-tible components. By suitably choosing the contact materials and by application in very thin coatings, it is possible to provide metallic conductor strips which also undergo combustion. Typical materials for the conductor strips are copper, pyrometal, aluminium, silver, gold and silver-palladium alloys or the like which can readily be produced in the form of foils and/or screen print-ing pastes and/or electrolytic coatings~
The electric supply line ~or the electric firing system is preferably guided from the base of the cartridge case over at least substantially the full length of -the flame-guiding duct i.e. not only over the rearward portion thereof, but also over its forward portion. The supply line thus extends in practice from the base of the cartridge case as far as the forward end of the flame-guiding duct and back again, it being possible for the firing system to be connected into the outgoing line or the return line. The gulding of the supply line up to the forward end of the flame-guide sleeve has the advantage that incorrect functioning at the ~0 time of firing, i.e. delayed ignitions possibly resulting from a previous damage to the flame-guiding duct are e~cluded, independently of whether this damage occurs in the rear portion or front portion. This is because the electric supply line in both portions is also interrupted and hence the firing system can no longer be triggered. This effect is more reliably guaranteed when using metallic conductor strips in very thin layers, which are arranged directly on the electrically insulating flame-guiding duct. This safe-guard against incorrect functioning due to possible structural damage to the flame-guiding duct~ is of very great importance in practice. The arrangement of the supply line up to the forward portion of the flame-guiding duct has, in addition, the advantage that both portions can be made indentical, as a resul-t of which the manufacture and assembly of the lgniter are simplifled.
It is preferred that the central firing system be housed in a cufE~llke coupling ~lceve, whlch engages witll its two ends over the two portions of the flame-guiding duck and is connected in this zone to the said portions, preferably by adhesive bonding as aforesaid.
In order to improve the so-called " first hit probability" of a projectile, electronic methods are general-ly used for effecting a correction of the range table, with which variations in ballistics in the time of passage through the barrel and in the muzzle velocity in dependenae on the temperature of the propellent are allowed for by measurement.
Furthermore, electronic methods are generally used in order automatically to recognise the type of ammunition, for example ammunition with inertia shells or ammunition with armour-piercing warheads, so that an error in the use of an incorrect range table or an incorrect ploting programme in the fire control computer of the weapon is excluded. Temper-ature sensors and electronic components, such as diodes, capacitors and resistors, the functioning of which is for example described in German ~uslegeschrift 2,059~655 are required for use in such electronic correction methods.
In order that such electric components may also be ar anged in a propellent charge igniter according to the invention, in such a way that the electric lines which are necessary in the latter are kept as simple and as short as possible, and so that in addition the electric components do not cause any damage to the weapon during the igniting oper-ation, the electric components are preferably arranged on the firing system in the middle region of the flame-guide sleeve and are connected through electric llnes to the firing system. The main advantage of this arrangement of the electric co~ponents in the region of central firing or fusing is the complete destruction of the components thereof made of ceramics, glass, synthetic plastics, silicon crys-tals, metallic connecting wires, ets~, which occurs at this location under the very high pressure and the very high temperature set up in use. This destruction is extremely important in ensuring that no relatively large particles which may damage the barrel of the weapon are formed.
~ dapters of combustible material may be provided for fitting of the electric components. These adapters will have recesses for accommodating the electric components and will be adhesively bonded at their ends to the block forming the iring system.
Possible variations in length of the propellant charge igniter, the size of which is depenaent on the materials being used and the temperature range in which the propellent charge igniter is to be operative may be compen-sated for if the electric coupling of the propellant chargeigniter to the cartridge case is achieved by means of a sprung contact pin which is fitted in an electrically insulated manner into the base screw of the base of the cartridge case. This pin will always be yieldably displaceable in an axial direction, but will always press against the electric line of the igniting system, which is preferably formed on the flame-guiding duct.
Where the base screw needs to have a very high mechanical pressure resistance, for example from 7000 to 8000 bars, the base screw may be sealed within a elastically expandable packing element, which bears with a sealing action against the adjacent walls of the base screw under the action of the gas pressure set up in use.
For a better understanding of the invention and to show how the same can be carried into effect, refer-ence will now be made, by way oE example only to the accom-panying drawings, wherein:
Figure 1 shows diagrammatically in longitudinal section a propellent charge igniter according to this in-vention;
Figure 2 is a longirudinal section to an enlarged scale of the iring system of the propellent charge igniter of Figure l;
Figure 3 is a diagram of an electric circuit which can be fitted in a propellent charge i~niter according to this invention;
Figure 4 is a view similar to that of Figure 2 of an alternative form of firing system in which additional electronic adapters for accommodating the circuit components which are shown in Figure 3 are provided;
Figure 5 shows a conductor strip on a greatly enlarged scale, which strip is enclosed between two com-bustible bodies, and Figure 6 is a longirudinal section through a base screw of a propellent charge igniter according to this invention.
The propellent charge igniter which is shown in Figure 1 comprises a metallic base screw 1 which is resistant to high pressure and which is screwed into the base of a cartridge case.~ A pressure-resistant, electrically insulated central contact 11, which is connected to an electric supply line for the firing system thereto is arranged in the base screw 1 while the base screw 1 provides an earthing terminal for the firing system.
3~
The rearward portion 2 o~ a flame-guiding tube, the length of which corresponds approximately to half the length of the propellent charge igniter is introduced into the base scr~w 1, The portion 2 of the flame-guiding tube is lengthened by the forward portion 22. This ~engthening is achieved by means of a cuf-like connectlng sleeve 3, which engages in the manner of a cu~f over the two portions 2 and 22 over a part o~ the length of each of which it extends. A firing system 4 is arranged in the middle of the coupling sleeve 3.
The forward end of the portion 22 of the ~lame~
guiding tube is closed by means o~ a conical cap 7 beneath which cap is located a cover disc 6. The conicalcap 7 ensures that when a projectile is fitted into the cartridge case, into which the propellent charge igniter has been screwed and the cartridge case has been filled with propellent charge powder, no undesirably high compression of the pxopellent charge powder occurs between the propellent charge igniter and the base of the projectile, since the individual grains of propellent powder are able to slide away laterally on the cap 7 and thus escape such compression.
I'he danger o~ the compression and possibly even ~estruction of the igniter occurs more particularly when the propellent charge igniter extends up to or at least close to the pro-jectile base, which is preferably the case.
An additional closure disc 6 is arranged inside the base screw 1. The portions 2 and 22 of the Elame-guiding tube are each filled with an igniter charye 5 and incorporate longitudinally extending electric conductors strips a and b, of which the conductor strip a is connected to the base screw 1 as earth terminal and the conductor strip b is connected to the central terminal 11, for example, by being gripped between the rearward co~er disc 6 and the central terminal 11. The conductor strips are Eor example made from the adhesive copper foil 118~ manufactured by the 3M-Company.
~i The conductor strip or suppl~ line a ex-tends from the base screw 1 along the outside of the portion 2 of the flame tube, through the coupling sleeve 3~ the forward portion 22 of the flame channel as far as its forward end, is then deflected between the cap 7 and the forward cover
Furthermore, the flame-guiding duct may be con-structed with an at least partially porous structure thereby increasing its surface area so as to accelerate its exothermic combustion. For this purpose, a soluble salt, for example potassium nitrate, may be incorporated in one or more of the aforesaid materials from which the duct may be formed. After the formation of the flame-guiding duct, for example, by extrusion or pressing this salt is dissolved out, therefrom for example by application of water~ so that the required cavities are left.
When the flame-guiding duct of the igniter of this invention is made of two or more parts, these are - advantageously connected to one another by adhesive bonding.
In general, polyester resins and polyurethanes can be used for bonding the parts to one another as well as possibly also for fixing the flame-guiding duct in a metallic base screw which is generally arranged in the base of the cartridge case or for connection with other components. It is preferred to ~ q~
use those bonding agents which effect interconnection of those parts of the flame guiding duct which are to be bonded to one another by causing superficial dissolution or softening of said parts so that these can be directly bonded to one another and produce a homogeneous structure. Wlth a flame-guiding duct made of nitrocellulose, it is Eor example possible to use a nitrocellulose la~quer as such a bonding agent, the proportion of solvent le.g. acetone) in -the lacquer causing the softening of -the surface. After e~aporation of the solvent, practlcally nomore foreign substance is to be found at the point o connection. This bonding is termed herein-after herein " cross-linking" and is a form of solvent welding.
The aforementioned disadvantageous rises in pressure during the firing procedure are minimised and as a result the fire power of the ~eapon increased as a result of the Elame-guiding duct being formed as an elongated sleeve or tube, ln the central region of which the electric iring system is arranged. The electrlc firing system is so designed that a firing impulse is emitted from it, both into that portion of the flame-guide tube facing forwardly, i.e.
towards a projectile, and into the portion facing rearwardly.
The flame-guiding duct is preferably formed from two identical component sleeves or tubes. A separate electric firing element may be provided for each component sleeve, such elements being arranged between the two portions and being capable of simultaneous ,triggering. However, it is preferred to use only a single firing element, which comprises an axial recess extending completely therethrough and which enables the firing impulse to be transmitted to the side further from its firing bridge or its firing gap. Particu-larly suitable for this purpose is the form of current propagation element which is described in our British Patent Specification No. 1,344,932. Such elements comprise an insulating body of glass or ceramics wi~h a bore extending therethrough, on the end faces of which are provided laminated metal contacts. A firing bridge partially covers the contacts or possibly a firing gap may be formed between the said contacts. Such an element ensure that when there is central firing of the propellent charge of the igniter of this in-vention, a symmetrical propagation of flame from the centre towards the front and towards the rear in the direction of the base of the cartridge case is achieved. The longer travels or paths of the firing flame, which are necessary when firing from the base of the cartridge case occurs and which usually set up a higher pressure in order to penetrate axialIy through the entire charge chamber are avoided. It is thus possible to reduce the pressure necessar~ for the firing that is to say, to provide a weaker initiation o the firing and thus avoid the pressure waves caused by ignition. This allows shorter firing tim~s to be achieved and thus a reduction in the minimum firing time or an increase in -the rate of firing.
In contrast to conventional base ignition or fusing, fusing at the centre is all the more effective as the longer ~s the total length of the flame-guiding duct.
Central fusing is conse~uently generally to be used with a total length of at least 100 mm, although in individual cases, it is of course also possible for this to be used with shorter lengths of the flame-guiding tube, for example about 50 mm. The tubular flame-guiding duct generally extends at least approximately the length of the charge chamber in which the igniter is used, i.e. from the base of the cartridge case up to or close to the base of the pro-jectile. However, it is also possible for the duct to be made shorter, so that it only extends, for example, over ~4~
half the ax.ial length of the charge chamber. Whilst central fusing will be more applicable to full length flame-guiding ducts occupying the length of the charge chamber, it can be used when the flame-guiding ducts do not extend this length, nevertheless.
The central firing of the flame-guiding ducts is particularly advantageous when the flame-guiding ducts comprise a material which reacts exothermally, since it still permits a favourable constructional form of igniter with an excellent igniting behaviour to be devised. The insulating body of the current propagation element as aforesaid can be made of exothermally combustible material, for example nitrocellulose, ibre-reinforced material such as epoxide resin with glass fibre fabric or of other combustible material, instead of being made of for example glass or ceramic material.
Central fusing may be employed in principle with flame-guiding ducts of so-called inflammable material in general or even~
.of metal, since it permits a favourable pressure curve to be sent up during the initiation phase and thus a shortening of the initiation or ignition. With metal flame-guiding ducts, it is then obviously necessary for at least one of the lines for the electric firing system to be guided to the central firing system while insulated from the sleeve base, while the flame-guiding duct itself can serve as an earthing connection.
However, with flame-guiding ducts of exothermally burning material, which simultaneously constitute an electric insulator, it is possible in a very simple manner to provide a suitable metal~coating of the surface thereof or any desired electrical wiring for contacting of the firing system.
A wide range of processes, such as screen-printing, adhesive and electrodeposition processes can be used for the metal coating of the combus-tible components. By suitably choosing the contact materials and by application in very thin coatings, it is possible to provide metallic conductor strips which also undergo combustion. Typical materials for the conductor strips are copper, pyrometal, aluminium, silver, gold and silver-palladium alloys or the like which can readily be produced in the form of foils and/or screen print-ing pastes and/or electrolytic coatings~
The electric supply line ~or the electric firing system is preferably guided from the base of the cartridge case over at least substantially the full length of -the flame-guiding duct i.e. not only over the rearward portion thereof, but also over its forward portion. The supply line thus extends in practice from the base of the cartridge case as far as the forward end of the flame-guiding duct and back again, it being possible for the firing system to be connected into the outgoing line or the return line. The gulding of the supply line up to the forward end of the flame-guide sleeve has the advantage that incorrect functioning at the ~0 time of firing, i.e. delayed ignitions possibly resulting from a previous damage to the flame-guiding duct are e~cluded, independently of whether this damage occurs in the rear portion or front portion. This is because the electric supply line in both portions is also interrupted and hence the firing system can no longer be triggered. This effect is more reliably guaranteed when using metallic conductor strips in very thin layers, which are arranged directly on the electrically insulating flame-guiding duct. This safe-guard against incorrect functioning due to possible structural damage to the flame-guiding duct~ is of very great importance in practice. The arrangement of the supply line up to the forward portion of the flame-guiding duct has, in addition, the advantage that both portions can be made indentical, as a resul-t of which the manufacture and assembly of the lgniter are simplifled.
It is preferred that the central firing system be housed in a cufE~llke coupling ~lceve, whlch engages witll its two ends over the two portions of the flame-guiding duck and is connected in this zone to the said portions, preferably by adhesive bonding as aforesaid.
In order to improve the so-called " first hit probability" of a projectile, electronic methods are general-ly used for effecting a correction of the range table, with which variations in ballistics in the time of passage through the barrel and in the muzzle velocity in dependenae on the temperature of the propellent are allowed for by measurement.
Furthermore, electronic methods are generally used in order automatically to recognise the type of ammunition, for example ammunition with inertia shells or ammunition with armour-piercing warheads, so that an error in the use of an incorrect range table or an incorrect ploting programme in the fire control computer of the weapon is excluded. Temper-ature sensors and electronic components, such as diodes, capacitors and resistors, the functioning of which is for example described in German ~uslegeschrift 2,059~655 are required for use in such electronic correction methods.
In order that such electric components may also be ar anged in a propellent charge igniter according to the invention, in such a way that the electric lines which are necessary in the latter are kept as simple and as short as possible, and so that in addition the electric components do not cause any damage to the weapon during the igniting oper-ation, the electric components are preferably arranged on the firing system in the middle region of the flame-guide sleeve and are connected through electric llnes to the firing system. The main advantage of this arrangement of the electric co~ponents in the region of central firing or fusing is the complete destruction of the components thereof made of ceramics, glass, synthetic plastics, silicon crys-tals, metallic connecting wires, ets~, which occurs at this location under the very high pressure and the very high temperature set up in use. This destruction is extremely important in ensuring that no relatively large particles which may damage the barrel of the weapon are formed.
~ dapters of combustible material may be provided for fitting of the electric components. These adapters will have recesses for accommodating the electric components and will be adhesively bonded at their ends to the block forming the iring system.
Possible variations in length of the propellant charge igniter, the size of which is depenaent on the materials being used and the temperature range in which the propellent charge igniter is to be operative may be compen-sated for if the electric coupling of the propellant chargeigniter to the cartridge case is achieved by means of a sprung contact pin which is fitted in an electrically insulated manner into the base screw of the base of the cartridge case. This pin will always be yieldably displaceable in an axial direction, but will always press against the electric line of the igniting system, which is preferably formed on the flame-guiding duct.
Where the base screw needs to have a very high mechanical pressure resistance, for example from 7000 to 8000 bars, the base screw may be sealed within a elastically expandable packing element, which bears with a sealing action against the adjacent walls of the base screw under the action of the gas pressure set up in use.
For a better understanding of the invention and to show how the same can be carried into effect, refer-ence will now be made, by way oE example only to the accom-panying drawings, wherein:
Figure 1 shows diagrammatically in longitudinal section a propellent charge igniter according to this in-vention;
Figure 2 is a longirudinal section to an enlarged scale of the iring system of the propellent charge igniter of Figure l;
Figure 3 is a diagram of an electric circuit which can be fitted in a propellent charge i~niter according to this invention;
Figure 4 is a view similar to that of Figure 2 of an alternative form of firing system in which additional electronic adapters for accommodating the circuit components which are shown in Figure 3 are provided;
Figure 5 shows a conductor strip on a greatly enlarged scale, which strip is enclosed between two com-bustible bodies, and Figure 6 is a longirudinal section through a base screw of a propellent charge igniter according to this invention.
The propellent charge igniter which is shown in Figure 1 comprises a metallic base screw 1 which is resistant to high pressure and which is screwed into the base of a cartridge case.~ A pressure-resistant, electrically insulated central contact 11, which is connected to an electric supply line for the firing system thereto is arranged in the base screw 1 while the base screw 1 provides an earthing terminal for the firing system.
3~
The rearward portion 2 o~ a flame-guiding tube, the length of which corresponds approximately to half the length of the propellent charge igniter is introduced into the base scr~w 1, The portion 2 of the flame-guiding tube is lengthened by the forward portion 22. This ~engthening is achieved by means of a cuf-like connectlng sleeve 3, which engages in the manner of a cu~f over the two portions 2 and 22 over a part o~ the length of each of which it extends. A firing system 4 is arranged in the middle of the coupling sleeve 3.
The forward end of the portion 22 of the ~lame~
guiding tube is closed by means o~ a conical cap 7 beneath which cap is located a cover disc 6. The conicalcap 7 ensures that when a projectile is fitted into the cartridge case, into which the propellent charge igniter has been screwed and the cartridge case has been filled with propellent charge powder, no undesirably high compression of the pxopellent charge powder occurs between the propellent charge igniter and the base of the projectile, since the individual grains of propellent powder are able to slide away laterally on the cap 7 and thus escape such compression.
I'he danger o~ the compression and possibly even ~estruction of the igniter occurs more particularly when the propellent charge igniter extends up to or at least close to the pro-jectile base, which is preferably the case.
An additional closure disc 6 is arranged inside the base screw 1. The portions 2 and 22 of the Elame-guiding tube are each filled with an igniter charye 5 and incorporate longitudinally extending electric conductors strips a and b, of which the conductor strip a is connected to the base screw 1 as earth terminal and the conductor strip b is connected to the central terminal 11, for example, by being gripped between the rearward co~er disc 6 and the central terminal 11. The conductor strips are Eor example made from the adhesive copper foil 118~ manufactured by the 3M-Company.
~i The conductor strip or suppl~ line a ex-tends from the base screw 1 along the outside of the portion 2 of the flame tube, through the coupling sleeve 3~ the forward portion 22 of the flame channel as far as its forward end, is then deflected between the cap 7 and the forward cover
6 and travels back along the portion 22 to the firing system to one contact of which it is connected so as to be electri-cally conducting. The other contact of the firing system is connected to the conductor strip or supply line b, which extends internally on the rearward portion 2 of the flame-guiding tube as far as the central terminal 11. Both conductor strips are thus connected to the firing system 4, one of the two being guided in a roundabout way over the forward tubular portion 22, so that even if the latter is clestroyed mechanically, as may possibly occur, initiation of the firing system, which would then be disadvantageous, will be prevented~
In addition, the conductor strip which leads to the forward end of the propellent charge igniter enables an electrical connection to be made to a projectile so that i the forward end of the propellent charge igniter is formed as a plug-type connector, it can engage in the base of the projectile and the conductor strip can then be connected to electrical components of the projectile. For e~ample, it is then possible to set a time fuse oE the projectile by introducing appropriate electrical data.
The portions 2 and 22 of the flame-guiding tube comprise radial openings 23, through which the igniting flame is able to strike into the outer charge chamber.
The flame-guiding tube 2/ 22 and preferably also the coupling sleeve 3, the cap 7 and the cover discs 6 are advantageously formed of exothermally combustible material, and preferably at least to a substantial degree of propellant, so that they burn exothermally during the igniting operation~ They can, for example, be formed as moulded propellent bodies and contain a binder.
The firing system 4 is shown of a larger scale in Figure 2. It contains a multi-component current propaga-tion element 42, which comprises an insulating body formed for example of glass, ceramics, plastics material or propellant, which is provided on its ends with thin metal contacts between which an igniting bridge is situated. The two sides of the element 42 communicate through a bore 50. Such a current propagation element is described in British Patent Specification No~ 1,344,932. The said element 42 is di-sposed in a cylindrical recess, which is formed between two axially opposite members 41, 41' which between them house the firing system. The ends oE the members 41, 41l bear against annylar discs 12 which are for example made of thin ~ronze and one of which is connected to the supply line a and the other to the supply line b. The supply lines a and b are in this case guided in the region of the firing system 4 in a somewhat diferent manner from that indicated in Figure 1. The firing bridge is not visible in the drawing.
The element 42 is surrounded by an annular centering member 48, which enables a spatial centering of the element 42 to be achieved inside the cylindrical recess which is formed between the members 41, 41' holding the fuse element.
Axial bores which are filled with the primary igniting charges 45 which are pressed therein lead from both outer ends of the fuse element-holding members 41, 41' to the element 42. These bores are increased in size in the region of their outer ends. These enlarged portions are occupied by pressed-in intensifier charges 43. Finally, the enlarged portions are closed by cover discs 44 which have axial holes 49 in the region of the charges ~3.
The complete central firing or fuse system as shown in Figure 2 is made as a compact, symmetrical block, the sections of which are adhesively bonded to one another, compressed together or firmly connected in some other way.
All parts, excepting the metal layers of the element ~2 and possibly the insulating body thereof where it is made for example of glass or ceramic material, are either essentially (in the case of charges 43 and 45) or otherwise preferably formed of exothermally reacting material, more particularly a propellant. The firing system ~ is located inside the cou~ling sleeve 3 (Figure l) between the opposed ends of the portions 2 and 22 of the flame channel.
; If an electric voltage is applied between the central terminal ll and the metallic base screw l, then a current flows through the conductor strip b, which is located inside the portion 2, to a terminal of the element 42 and then on, via the firiny bridge, to the other side o the conductor strip a which is led around the combustible flame-guiding tube part 22 and continues back to the base screw 1 via the coupling sleeve 3 and the likewise combustible portion 2 of the flame-guiding tube.
The firing bridge which is disposed on the element 42 is ignited by the flowing current. The igniter charges 5 (Figure 1) are ignited in conjuction with the primar~ igniter charges 45 and the intensifer charges 43 as a result of the operative connection of the primary igniter charges 45 with one another through the axial bore 3~8 50 of the element 42 of the central firing system 4. Depend-ing on the dimensions of the openings 23 formed in -the wall of the flame channel 2, 22, the initiating flames strilce immediately or with a delay action into the charge chamber of a projectile therearound.
The central firing system ~ is of symmetrical form. The primary initiating charge 45 on either the right or on the left side of the element 42 is the Eirst to be ignited, depending on the position of the firing bridge on the element ~2. This igniting flame then strikes through its bore 50 and initiates the respective other primary initiating charge 45. In this way, both intensiEier charges are ignited almost simultaneously and the ini-tiating flames spread out symmetrically in the flame-guiding tube 2, 22 in rearward and forward directions, from a central position.
When all the initiating charges, which burn more quickly than surrounding combustible components, have become Eully operative, the propellent powder charge situated around the propellent charge igniter in the cartridge case is ignited. The high combustion temperatures and the high pressuref which are then formed on Eiring, ensure that all the combustible portion of the propellent charge igniter is completely consumed by burning during the course of ignition.
The central firing system is preferably constructed of as many as possible identical components, so that in conjunction with the flame-yuiding tube housing, the cost of manufacturingand assembling the igniter is kept as low as possible. An additional advantage oE initiating the firing directly in the centre or approximately in the centre of a propellent powder charge is the very rapid ignition achieved with a comparatively small amount of the ignition charges so that a further cost reduction is obtained which is not to - 17 ~
the detriment of the improved fire power of the weapon.
As will be seen from thP circuit shown if Figure 3, a typical electrical circuit of a propellent charge igniter according -to this invention may comprise, in addition to the current propayation element which is denoted by a resistance Rz, three additional electrical components, namely, a code capacitor CK~ a temperature sensor NTC ancl a diode D. This circult serves, irstly, to establish the ammunition coding and to measure the temperature of the propellent charge powder and, secondly, to initiate the firing system Rz.
During the measurement phase, a positive direct voltage is applied at the point b, on which is superimposed an alter-nating voltage of low level. In this phase, the diode D
prevents the initiation of the firing system Rz. The alter-nating current resistivity being produced from the capacitor CK and the Nr~C resistance is established with the alternating voltage. The shift in th~ ohmic resistance value of the NTC
resistance, in dependence on the temperature, changes the real increase in the complex alternating current resistivity.
The complex alternating current resistivity is split up into a real portion and an imaginary portion by means of an evaluat-ing instrument. The temperature is associated with the real portion and the ammunition coding is associated with the imaginary portion, which is independent of temperature. By way of example, if different capacitors CK are installed for each of a variety of types of ammunition, it is possi~le to differentiate between the types of ammunitiont with equal measurement frequency of the alternating voltage, in accord-ance with the different imaginary portions.
If firing is to take place, the positive direct voltage is applied to the point a and, as a result, the flow of current through the firing system Rz is made avail-able by the diode D. The range of resistance of the NTC
resistance is chosen to be larger by several powers of ten than that of the firing system Rz, so that the energy consumption which occurs because of the shunting of the NTC
resistance does not adversely afect the satisfactory initiation of the firing system Rz.
Figure 4 shows a firing system 4', which is substantially similar to the fi~ing system 4 as shown in Figure 2 and in which like reference numerals denote like features, but which, in addition, contains all the electrical components of the circuit indicated in Figure 3. These are arranged in electronic adapter plates 46 and 47, which are fitted to the cover discs 44.
A particular advantage of including the electrical components in the central firing system is that the complete destruction of components made of ceramic material, glass, synthetic plastics material, semi-conductor material, and .of the metal connecting wires takes place when the igniter is operative because of the very high pressure and the ver~
high temperature, which are established at the time of initiation of the igniter. This destruction is of particular importance in ensuring that no relatively large particles are available to the barrel of the weapon.
Since all four of the components, CK, NTC, Rz and D are arranged in a longitudinal direction in the middle region of the propellent charge igniter, only two conductor strips a and b are required for the connection of all components. Since it is generally desirable to measure the propellent charge temperature in the middle thereof, the arrangement of the temperature sensor NTC close to the laminated metal element 42 is extremely desirable. If the other components, such as the code capacitor CK and the diode 3~
D were to he arranged in the metallic base screw 1, then at least three supply lines would be necessary for the supply of current to the components disposed centrally in the channel.
The electronic adapters 46 and 47 are m~de of combustible and more particularly exothermally combustible material and form a mechanical holding means for the electrical components. They comprise longitudinal bores, in which the electrical components are arranged. It can be seen from Figure 4 how only two connections are necessary with the conduction arrangement shown. The components CK, N~C and D completely Eill the recesses or openings in the adapters 46, 47. Their electrical connections lie in the plane of the end faces of the adapters 46~ 47.
Not only does the arrangement shown in ~igure 4, possess the previously mentioned advantage of the simple guiding of the electric supply lines to the central firing system, but, in addition, the geometrical symmetry of the components permits ready use of the firing system as a unit construction system in different forms of igniter according to this invention ~or different projectiles. If propellent charge igniters wi$hout electrical components are required, then it is only necessary to omit the electronic adapters 46, 47. This orm of firing system lends itself well to the mass production of different types of combustible igniter systems and thus also a considerable saving in cost.
Since the structural components of an igniter in accordance with this invention consist largely of combustible material as sources of energy, the complete ;
inter-connection of the parts of the igniter can be effected by adhesive bonding. The use of adhesive bonding has the advantage that, for e~ample, a firm interconnection of the æ
materials is guaranteed as a result of ~I cross-linking"
and as a result there are practically no points of connection which are structurally weak. The provision of the conductor strips for achie~ing the electrical inter-connection of the electrical operated elements can also be achie~ed readily by the adhesive bonding techniques. For example, the electrical conductor strips may be made with openings, and the material to be united therewith can be ".cross-linked" in conjunction with a suitable pressing operarion forcing the material through the openings in the conductor strips.
Thus, referring next to Figure 5, there is shown a seam position where two combustible components are to be joined using a bonding agent which causes " cross-linking" .
A conductor strip 9 having openings 51 therethrough is in this case located between two combustible elements 8 and 10 which are being united by use of adhesi~e. The conductor strip 9 has a thickness which is between approximately 2 ~m and 50 ~m. ~s pressure is applied strongly to the elements 8 and 10, the adhesive is able to cross-link the two elements 8 and ~ 20 10 to one another as it passes through the openings 51. The ; scattered lines which are shown in Figure 5 are in-tended here to indicate the molecular " cross-linking" which occurs.
Referring finally to Figure 6, the base screw 1 shown therei.n comprises a main body la', preferably formed of brass, which is adapted for screwing into the metallic base of a cartridge case. Formed in the main body la is a recess 52, in which is arranged the pressure-resistant centre terminal 11, made for example of steel, and a packing element 53, which is preferably made of brass or even of an elastic steel. In addition, a resilient contact pin 55 is arranged in the packing element 53 from which it is electrically insulated, together with a housing 54. The central terminal 11 and the contact pin 55 are electrically insulated from the main body la by means of insulations 56 and the housing 54~ which is formed of a hard pressure-resistant synthetic plastics material, for example a laminated moulding material.
The contact pin 55 is supported by means oE a biased helical spriny 57, made for example of steel or spring bronze, which preferably also gold-plated, on the central terminal 11 and on the rear cover disc 6 of the flame channel 2 and is thus connected to the latter to be electrically conducting. The pressure tigh~ness within the main body is achie~ed by means of annular collars 58, 59 of the elastically deformable packing element 53, which is supported towards the rear end against the central terminal 11~ The inner cylindrical collar 58 bears against the housing 54, while -the outer collar 59 rest on the wall of the recess 52 in the main body 1. An annular pressure chamber 60 is formed between the two collars.
The forward rim of the outer collar 59 enters into positive engagement with an annular gap 61 around the recess 52, formed by flanging over the latter with its annular edge 62 against the rim of the collar. Because of this pretensioning of the packing element 53 at the time of assembly, a relatively good sealing action with respect to the main body 1 is obtained. If propellent gases flow into the pressure chamber 60 on firing of the propellent charge igniter, the outer collar 59 is forced against the main body 1 and the inner collar 513 is Eorced against the housing 5~ by the very high gas pressure, as a result of which a sealing of the base screw with a satis~actory packing action is produced, which has proved to be effective up to pressures oE 7000 to 8000 bar.
.
In addition, the conductor strip which leads to the forward end of the propellent charge igniter enables an electrical connection to be made to a projectile so that i the forward end of the propellent charge igniter is formed as a plug-type connector, it can engage in the base of the projectile and the conductor strip can then be connected to electrical components of the projectile. For e~ample, it is then possible to set a time fuse oE the projectile by introducing appropriate electrical data.
The portions 2 and 22 of the flame-guiding tube comprise radial openings 23, through which the igniting flame is able to strike into the outer charge chamber.
The flame-guiding tube 2/ 22 and preferably also the coupling sleeve 3, the cap 7 and the cover discs 6 are advantageously formed of exothermally combustible material, and preferably at least to a substantial degree of propellant, so that they burn exothermally during the igniting operation~ They can, for example, be formed as moulded propellent bodies and contain a binder.
The firing system 4 is shown of a larger scale in Figure 2. It contains a multi-component current propaga-tion element 42, which comprises an insulating body formed for example of glass, ceramics, plastics material or propellant, which is provided on its ends with thin metal contacts between which an igniting bridge is situated. The two sides of the element 42 communicate through a bore 50. Such a current propagation element is described in British Patent Specification No~ 1,344,932. The said element 42 is di-sposed in a cylindrical recess, which is formed between two axially opposite members 41, 41' which between them house the firing system. The ends oE the members 41, 41l bear against annylar discs 12 which are for example made of thin ~ronze and one of which is connected to the supply line a and the other to the supply line b. The supply lines a and b are in this case guided in the region of the firing system 4 in a somewhat diferent manner from that indicated in Figure 1. The firing bridge is not visible in the drawing.
The element 42 is surrounded by an annular centering member 48, which enables a spatial centering of the element 42 to be achieved inside the cylindrical recess which is formed between the members 41, 41' holding the fuse element.
Axial bores which are filled with the primary igniting charges 45 which are pressed therein lead from both outer ends of the fuse element-holding members 41, 41' to the element 42. These bores are increased in size in the region of their outer ends. These enlarged portions are occupied by pressed-in intensifier charges 43. Finally, the enlarged portions are closed by cover discs 44 which have axial holes 49 in the region of the charges ~3.
The complete central firing or fuse system as shown in Figure 2 is made as a compact, symmetrical block, the sections of which are adhesively bonded to one another, compressed together or firmly connected in some other way.
All parts, excepting the metal layers of the element ~2 and possibly the insulating body thereof where it is made for example of glass or ceramic material, are either essentially (in the case of charges 43 and 45) or otherwise preferably formed of exothermally reacting material, more particularly a propellant. The firing system ~ is located inside the cou~ling sleeve 3 (Figure l) between the opposed ends of the portions 2 and 22 of the flame channel.
; If an electric voltage is applied between the central terminal ll and the metallic base screw l, then a current flows through the conductor strip b, which is located inside the portion 2, to a terminal of the element 42 and then on, via the firiny bridge, to the other side o the conductor strip a which is led around the combustible flame-guiding tube part 22 and continues back to the base screw 1 via the coupling sleeve 3 and the likewise combustible portion 2 of the flame-guiding tube.
The firing bridge which is disposed on the element 42 is ignited by the flowing current. The igniter charges 5 (Figure 1) are ignited in conjuction with the primar~ igniter charges 45 and the intensifer charges 43 as a result of the operative connection of the primary igniter charges 45 with one another through the axial bore 3~8 50 of the element 42 of the central firing system 4. Depend-ing on the dimensions of the openings 23 formed in -the wall of the flame channel 2, 22, the initiating flames strilce immediately or with a delay action into the charge chamber of a projectile therearound.
The central firing system ~ is of symmetrical form. The primary initiating charge 45 on either the right or on the left side of the element 42 is the Eirst to be ignited, depending on the position of the firing bridge on the element ~2. This igniting flame then strikes through its bore 50 and initiates the respective other primary initiating charge 45. In this way, both intensiEier charges are ignited almost simultaneously and the ini-tiating flames spread out symmetrically in the flame-guiding tube 2, 22 in rearward and forward directions, from a central position.
When all the initiating charges, which burn more quickly than surrounding combustible components, have become Eully operative, the propellent powder charge situated around the propellent charge igniter in the cartridge case is ignited. The high combustion temperatures and the high pressuref which are then formed on Eiring, ensure that all the combustible portion of the propellent charge igniter is completely consumed by burning during the course of ignition.
The central firing system is preferably constructed of as many as possible identical components, so that in conjunction with the flame-yuiding tube housing, the cost of manufacturingand assembling the igniter is kept as low as possible. An additional advantage oE initiating the firing directly in the centre or approximately in the centre of a propellent powder charge is the very rapid ignition achieved with a comparatively small amount of the ignition charges so that a further cost reduction is obtained which is not to - 17 ~
the detriment of the improved fire power of the weapon.
As will be seen from thP circuit shown if Figure 3, a typical electrical circuit of a propellent charge igniter according -to this invention may comprise, in addition to the current propayation element which is denoted by a resistance Rz, three additional electrical components, namely, a code capacitor CK~ a temperature sensor NTC ancl a diode D. This circult serves, irstly, to establish the ammunition coding and to measure the temperature of the propellent charge powder and, secondly, to initiate the firing system Rz.
During the measurement phase, a positive direct voltage is applied at the point b, on which is superimposed an alter-nating voltage of low level. In this phase, the diode D
prevents the initiation of the firing system Rz. The alter-nating current resistivity being produced from the capacitor CK and the Nr~C resistance is established with the alternating voltage. The shift in th~ ohmic resistance value of the NTC
resistance, in dependence on the temperature, changes the real increase in the complex alternating current resistivity.
The complex alternating current resistivity is split up into a real portion and an imaginary portion by means of an evaluat-ing instrument. The temperature is associated with the real portion and the ammunition coding is associated with the imaginary portion, which is independent of temperature. By way of example, if different capacitors CK are installed for each of a variety of types of ammunition, it is possi~le to differentiate between the types of ammunitiont with equal measurement frequency of the alternating voltage, in accord-ance with the different imaginary portions.
If firing is to take place, the positive direct voltage is applied to the point a and, as a result, the flow of current through the firing system Rz is made avail-able by the diode D. The range of resistance of the NTC
resistance is chosen to be larger by several powers of ten than that of the firing system Rz, so that the energy consumption which occurs because of the shunting of the NTC
resistance does not adversely afect the satisfactory initiation of the firing system Rz.
Figure 4 shows a firing system 4', which is substantially similar to the fi~ing system 4 as shown in Figure 2 and in which like reference numerals denote like features, but which, in addition, contains all the electrical components of the circuit indicated in Figure 3. These are arranged in electronic adapter plates 46 and 47, which are fitted to the cover discs 44.
A particular advantage of including the electrical components in the central firing system is that the complete destruction of components made of ceramic material, glass, synthetic plastics material, semi-conductor material, and .of the metal connecting wires takes place when the igniter is operative because of the very high pressure and the ver~
high temperature, which are established at the time of initiation of the igniter. This destruction is of particular importance in ensuring that no relatively large particles are available to the barrel of the weapon.
Since all four of the components, CK, NTC, Rz and D are arranged in a longitudinal direction in the middle region of the propellent charge igniter, only two conductor strips a and b are required for the connection of all components. Since it is generally desirable to measure the propellent charge temperature in the middle thereof, the arrangement of the temperature sensor NTC close to the laminated metal element 42 is extremely desirable. If the other components, such as the code capacitor CK and the diode 3~
D were to he arranged in the metallic base screw 1, then at least three supply lines would be necessary for the supply of current to the components disposed centrally in the channel.
The electronic adapters 46 and 47 are m~de of combustible and more particularly exothermally combustible material and form a mechanical holding means for the electrical components. They comprise longitudinal bores, in which the electrical components are arranged. It can be seen from Figure 4 how only two connections are necessary with the conduction arrangement shown. The components CK, N~C and D completely Eill the recesses or openings in the adapters 46, 47. Their electrical connections lie in the plane of the end faces of the adapters 46~ 47.
Not only does the arrangement shown in ~igure 4, possess the previously mentioned advantage of the simple guiding of the electric supply lines to the central firing system, but, in addition, the geometrical symmetry of the components permits ready use of the firing system as a unit construction system in different forms of igniter according to this invention ~or different projectiles. If propellent charge igniters wi$hout electrical components are required, then it is only necessary to omit the electronic adapters 46, 47. This orm of firing system lends itself well to the mass production of different types of combustible igniter systems and thus also a considerable saving in cost.
Since the structural components of an igniter in accordance with this invention consist largely of combustible material as sources of energy, the complete ;
inter-connection of the parts of the igniter can be effected by adhesive bonding. The use of adhesive bonding has the advantage that, for e~ample, a firm interconnection of the æ
materials is guaranteed as a result of ~I cross-linking"
and as a result there are practically no points of connection which are structurally weak. The provision of the conductor strips for achie~ing the electrical inter-connection of the electrical operated elements can also be achie~ed readily by the adhesive bonding techniques. For example, the electrical conductor strips may be made with openings, and the material to be united therewith can be ".cross-linked" in conjunction with a suitable pressing operarion forcing the material through the openings in the conductor strips.
Thus, referring next to Figure 5, there is shown a seam position where two combustible components are to be joined using a bonding agent which causes " cross-linking" .
A conductor strip 9 having openings 51 therethrough is in this case located between two combustible elements 8 and 10 which are being united by use of adhesi~e. The conductor strip 9 has a thickness which is between approximately 2 ~m and 50 ~m. ~s pressure is applied strongly to the elements 8 and 10, the adhesive is able to cross-link the two elements 8 and ~ 20 10 to one another as it passes through the openings 51. The ; scattered lines which are shown in Figure 5 are in-tended here to indicate the molecular " cross-linking" which occurs.
Referring finally to Figure 6, the base screw 1 shown therei.n comprises a main body la', preferably formed of brass, which is adapted for screwing into the metallic base of a cartridge case. Formed in the main body la is a recess 52, in which is arranged the pressure-resistant centre terminal 11, made for example of steel, and a packing element 53, which is preferably made of brass or even of an elastic steel. In addition, a resilient contact pin 55 is arranged in the packing element 53 from which it is electrically insulated, together with a housing 54. The central terminal 11 and the contact pin 55 are electrically insulated from the main body la by means of insulations 56 and the housing 54~ which is formed of a hard pressure-resistant synthetic plastics material, for example a laminated moulding material.
The contact pin 55 is supported by means oE a biased helical spriny 57, made for example of steel or spring bronze, which preferably also gold-plated, on the central terminal 11 and on the rear cover disc 6 of the flame channel 2 and is thus connected to the latter to be electrically conducting. The pressure tigh~ness within the main body is achie~ed by means of annular collars 58, 59 of the elastically deformable packing element 53, which is supported towards the rear end against the central terminal 11~ The inner cylindrical collar 58 bears against the housing 54, while -the outer collar 59 rest on the wall of the recess 52 in the main body 1. An annular pressure chamber 60 is formed between the two collars.
The forward rim of the outer collar 59 enters into positive engagement with an annular gap 61 around the recess 52, formed by flanging over the latter with its annular edge 62 against the rim of the collar. Because of this pretensioning of the packing element 53 at the time of assembly, a relatively good sealing action with respect to the main body 1 is obtained. If propellent gases flow into the pressure chamber 60 on firing of the propellent charge igniter, the outer collar 59 is forced against the main body 1 and the inner collar 513 is Eorced against the housing 5~ by the very high gas pressure, as a result of which a sealing of the base screw with a satis~actory packing action is produced, which has proved to be effective up to pressures oE 7000 to 8000 bar.
.
Claims (68)
1. A propellent charge igniter for ammunition which comprises an electrical ignition system and an ignition charge operatively associated therewith housed in a flame-guiding duct, the electrical ignition system being positioned in a middle zone of the flame-guiding duct and being adapted to supply an ignition impulse in both the forward and rearward directions with respect thereto.
2. An igniter as claimed in claim 1, wherein the flame guiding duct is formed as an elongate tube in a middle zone of which is provided the electric ignition system which is adapted to supply an ignition impulse in both the forward and rearward directions with respect thereto.
3. A igniter as claimed in claim 2, wherein the said tube has a length of at least 100 mm.
4. An igniter as claimed in claim 3, wherein the electric firing system is housed in a coupling sleeve which engages at its ends two portions of flame-guiding duct to which it is fixedly connected.
5. An igniter as claimed in claim 4,wherein the coupling sleeve is adhesively bonded to said two portions.
6. An igniter as claimed in claim 5, which com-prises electrical components, all the electrical components exclusive of electric leads being housed in said middle zone of the elongate tube.
7. A igniter as claimed in claim 6, wherein said electrical components comprise a code capacitor, a temperature sensor and a diode whereby ammunition coding and temperature direction may be effected and initiation of the ignition system achieved only in accordance with prescribed coding and temperature information.
8. An igniter as claimed in claim 6 or 7, which comprises an adaptor formed of combustible material at at least one end of the ignition system, which adaptor com-prises at least one recess accommodating at least one said electrical components.
9. An igniter as claimed in claim 1, wherein the flame-guiding duct comprises a propellent composition present in sufficient amount for the flame-guiding tube to undergo exothermal reaction.
10. An igniter as claimed in claim 9, wherein the flame-guiding duct is formed of a bound explosive material.
11. An igniter as claimed in claim 1, wherein the material forming the flame-guiding duct is reinforced with a metallic reinforcing insert.
12. An igniter as claimed in claim 11, wherein the insert is combustible.
13. An igniter as claimed in claim 1, wherein the flame-guiding duct possesses a porous structure.
14. An igniter as claimed in claim 1 or 2, wherein the ignition charge is formed of Benite strands.
15. An igniter as claimed in claim 1, wherein the ignition charge is formed of a thermal mixture free from inflammable matter.
16. An igniter as claimed in claim 15, wherein the thermal mixture comprises boron and potassium nitrate.
17. An igniter as claimed in claim 15, wherein the thermal mixture is pressed into annular tablets arranged in a column in the flame-guiding duct.
18. An igniter as claimed in claim 17, wherein the tablets are adhesively bonded to the flame-guiding duct.
19. An igniter as claimed in claim 1, which comprises an electric conductor extending the entire length thereof.
20. An igniter as claimed in claim 19, wherein the conductor is applied to the flame-guiding duct as a film by screenprinting, or electrodeposition or by use of an adhesive.
21. An igniter as claimed in claim 1, further comprising a base screw connected to the flame-guiding duct and having a terminal arranged therein and insulated electri-cally from said duct, which terminal is connected to one supply line of the electrical ignition system through a contact pin arranged in a housing, which pin is supported against said terminal and the flame-guiding duct against the force of a predetermined electrically conducting spring constantly acting on said pin.
22. An igniter as claimed in claim 21, wherein the housing of the contact pin is surrounded by a packing element which is supported between the said contact and the base screw, which packing element comprises two annular collars which extend forwardly towards the flame-guiding duct and with an annular channel therebetween, the inner collar bearing with its forward rim against the housing and the outer collar bearing with its rim against the wall of a recess in the base screw.
23. An igniter as claimed in claim 22, wherein the rim of the outer collar is positively held in an annular channel formed in the wall of the recess.
24. A shell which comprises a cartridge case housing a propellant charge igniter as claimed in claim 1 and which carries a projectile in a forward region thereof.
25. An igniter as claimed in claim 3, wherein the electric ignition system is housed in a coupling sleeve which engages at its ends two portions of flame-guiding duct to which it is fixedly connected.
26. An igniter as claimed in claim 25, wherein the coupling sleeve is adhesively bonded to said two portions.
27. An igniter according to claim 2, which further comprises an electric conductor extending the entire length thereof.
28. An igniter as claimed in claim 27, wherein the conductor is applied to the flame-guiding duct as a film by screenprinting, or electrodeposition or by use of an adhesive.
29. An igniter as claimed in claim 28, wherein the electric ignition system is housed in a coupling sleeve which engages at its ends two portions of flame-guiding duct to which it is fixedly connected.
30. An igniter as claimed in claim 29, wherein the coupling sleeve is adhesively bonded to said two portions.
31. An igniter as claimed in claim 13, which comprises electrical components, all the electrical components exclusive of electric leads being housed in said middle zone of the elongate tube.
32. An igniter as claimed in claim 31, wherein the electrical components comprise a code capacitor, a temperature sensor and a diode whereby ammunition coding and temperature detection may be effected and initiation of the ignition system achieved only in accordance with prescribed coding and temperature information.
33. An igniter as claimed in claim 30, which comprises electrical components, all the electrical components exclusive of electric leads being housed in said middle zone of the elongate tube.
34. An igniter as claimed in claim 33, wherein the electrical components comprise a code capacitor, a tem-perature sensor and a diode whereby ammunition coding and temperature detection may be effected and initiation of the ignition system achieved only in accordance with prescribed coding and temperature information.
35. An igniter according to claim 1 or 2, wherein the flame-guiding duct is made of metal.
36. A propellent charge igniter for ammunition comprising a propellent charge and a projectile, which igniter comprises an electrical ignition system and a flame-guiding duct formed as an elongate duet having an ignition charge housed therein and intended to be emplaced in said propellent charge to extend from the base side thereof, being the end thereof remote from projectile and at which side connection to electric supply means is to be provided, the electrical ignition system of the igniter being arranged in a middle zone of the flame-guiding duct extending lengthwise thereof such that the ignition impulse of the ignition system is propagated in the ignition charge both towards the rear and the front of the flame-guiding duct.
37. An igniter as claimed in claim 36, in which at least one electrical conductor is trained on the flame-guiding duct from the base end thereof to the ignition system.
38. An igniter as claimed in claim 37, wherein said least one electrical conductor is provided on an electri-cally insulating inner wall surface of the flame-guiding duct by a metal coating procedure.
39. An igniter as claimed in claim 38, wherein said metal coating procedure is an adhesive bonding, a screen printing or an electrodeposition procedure.
40. An igniter as claimed in claim 37, 38 or 39, wherein the at least one electrical conductor for the ignition system is led forward beyond the ignition system over the entire length of the flame-guiding duct and back again to the ignition system.
41. An igniter as claimed in claim 36, wherein the said tube has a length of at least 100 mm.
42. An igniter as claimed in claim 36, wherein the electric firing system is housed in a coupling sleeve which engages at its ends two portions of the flame-guiding duct, to which portions of the flame-guiding duct the electric firing system is fixedly connected.
43. An igniter as claimed in claim 42, wherein the coupling sleeve is adhesively bonded to said two portions.
44. An igniter as claimed in claim 42 or 43, wherein the coupling sleeve contains an ignition element provided with an axial bore, the ignition element being bounded on both sides by a primary ignition charge which is in turn bounded by an intensifier charge in a substantially symmetrical arrangement, the ignition element comprising an insulating body whose opposed surfaces carry metal contacts in electrical communication with each other through the axial bore.
45. An igniter as claimed in claim 36, which comprises further electrical components, all the electrical components exclusive of electric leads being housed in said middle zone of the elongate tube.
46. An igniter as claimed in claim 95, wherein the further electrical components comprise a code capacitor, a temperature sensor and a diode whereby ammunition coding and temperature detection may be effected and initiation of the firing system achieved only in accordance with prescribed coding and temperature information.
47. An igniter as claimed in claim 45 or 46, which comprises an adaptor formed of combustible material at at least one end of the firing system, which adaptor comprises at least one recess accommodating at least one said further electrical component.
48. An igniter as claimed in claim 36, wherein the flame-guiding duct comprises a propellent composition present in sufficient amount for the flame-guiding tube to undergo exothermal reaction.
49. An igniter as claimed in claim 48, wherein the flame-guiding duct is formed of a secondary explosive material and a binder -therefor.
50. A propellent charge igniter as claimed in claim 49, wherein the secondary explosive is octogen.
51. A propellent charge igniter as claimed in claim 50, wherein the secondary explosive is .alpha.-octogen.
52. A propellent charge igniter as claimed in claim 49, 50, or 51, wherein the binder material is a polyester resin.
53. A propellent charge igniter as claimed in claim 49, wherein the flame-guiding duct comprises therein incombustible inlays formed of a material which is dis-integrated with the buildup of pressure within the igniter.
54. A propellent charge igniter as claimed in claim 53, wherein glass fibres are embedded in the material of the flame-guiding duct.
55. An igniter as claimed in claim 36, wherein the flame-guiding duct possesses a porous structure.
56. An igniter as claimed in claim 36, wherein the ignition charge is formed of Benite strands.
57. An igniter as claimed in claim 36, wherein the ignition charge is formed of a thermal mixture free from inflammable matter.
58. An igniter as claimed in claim 57, wherein the thermal mixture comprises boron and potassium nitrate.
59. An igniter as claimed in claim 58, wherein the thermal mixture is pressed into annular tablets arranged in column in the flame-guiding duct.
60. An igniter as claimed in claim 59, wherein the tablets are adhesively bonded to the flame-guiding duct.
61. An igniter as claimed in claim 36, further comprising a base screw connected to the flame-guiding duct and having a terminal arranged therein and insulated electrical-ly from said duct, which terminal is connected to one supply line of the electrical firing system through a contact pin arranged in a housing, which pin is supported against said terminal and the flame-guiding duct against the force of a predetermined electrically conducting spring constantly acting on said pin.
62. An igniter as claimed in claim 61, wherein the housing of the contact pin is surrounded by a packing element which is supported between the said contact and the base screw, which packing element comprises two annular collars which extend forwardly towards the flame-guiding duct and with an annular channel therebetween, the inner collar bearing with its forward rim against the housing and the outer collar bearing with its rim against the wall of a recess in the base screw.
63. An igniter as claimed in claim 62, wherein the rim of the outer collar is positively held in an annular channel formed in the wall of the recess.
64. A shell which comprises a cartridge case housing a propellent charge igniter as claimed in claim 36, and which carries a projectile in a forward region thereof.
65. A shell as claimes in claim 64, in which the propellent charge igniter extends substantially the entire length thereof.
66. An igniter according to claim 1, wherein the material forming the flame-guiding duct is reinforced with a non-metallic reinforcing insert.
67. An igniter according to claim 1, wherein said flame-guiding duct is formed of an exothermically-burning material comprising secondary explosive and a non-explosive binder therefor.
68. An igniter according to claim 67, wherein said binder is a synthetic plastics binder.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000378487A CA1150108A (en) | 1976-10-23 | 1981-05-27 | Propellant charge igniter with an electrical ignition system in middle zone of a flame guiding duct |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2648137A DE2648137C2 (en) | 1976-10-23 | 1976-10-23 | Propellant charge lighter for ammunition |
| DEP2648137.8 | 1976-10-23 | ||
| CA289,250A CA1125091A (en) | 1976-10-23 | 1977-10-21 | Propellant charge igniter |
| CA000378487A CA1150108A (en) | 1976-10-23 | 1981-05-27 | Propellant charge igniter with an electrical ignition system in middle zone of a flame guiding duct |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1150108A true CA1150108A (en) | 1983-07-19 |
Family
ID=27165338
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000378487A Expired CA1150108A (en) | 1976-10-23 | 1981-05-27 | Propellant charge igniter with an electrical ignition system in middle zone of a flame guiding duct |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1150108A (en) |
-
1981
- 1981-05-27 CA CA000378487A patent/CA1150108A/en not_active Expired
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |