METHOD AND ARRANGEMENT FOR PROGRAMMING SHELLS

Abstract: The present invention relates to a method and an arrangement in order to make possible, inshell-firing weapons with rifled barrels (1) made of steel, inductive transmission of programming data from a programming device (11) connected to the weapon to a programmable time fuse (21) arranged in the respective shell (12) while the shell (12) is situated in the cartridge chamber of the weapon. According to the invention, the steel barrel has been provided with an insert (4) made of non-magnetic material which surrounds the cartridge chamber of the weapon and which moreover cannot form a closed electrically conductive circuit around the shell and which therefore will not disrupt transmission. The electric transmitting coil (8) necessary for the inductive transmission is then arranged in a groove (7) around this insert while the shell in turn has its own internal receiving coil (18).

Description: METHOD AND ARRANGEMENT FOR PROGRAMMING SHELLS The present invention relates to a method and an arrangement in order to make it possible, in both single- shot and also semi-automatic and fully automatic shell- firing barrel weapons and in particular in those which are provided with rifled barrels made of steel, to transmit, contactlessly and inductively, relevant programming data to a programmable fuse function included in the respective shell while the shell in question is still situated in the cartridge chamber of the weapon. As far as detonating shells are concerned, the main effect of which on the target is achieved through splinter, it has been known for a long time that the effect on the target depends directly upon how close to the target the detonation takes place and also whether this takes place above the target, which clearly produces the best effect, or on ground impact beside the target. Even though efforts are of course made to achieve direct strikes on the target, such direct strikes are not particularly frequent in spite of modern fire-control and missile-trajectory calculating instruments. One way of bringing about air bursts directly above the target aimed at is based on providing the shells with a programmable time fuse function which can be programmed for detonation at the trajectory distance from the firing point at which it is calculated that the target is situated. When shells of this type are being used, it is desirable to carry out this programming as late as possible before firing. This is particularly the case with shell-firing infantry weapons where, with mobile positions, it may be expected that both oneself and the target are continuously moving around on the battlefield. Under these circumstances, it would therefore be a clear advantage if the time fuse function of the shells could be programmed as late as possible before firing, e.g. when the shell is ready for firing in the cartridge chamber of the shell-firing weapon. Arranging such programming of the time fuse function of the shells inside the cartridge chamber of the weapon, however, involves certain problems because the cartridge chamber constitutes part of the barrel. It is already known from before, however, that it is possible to program in an inductive manner electronic shell fuses which are designed in a special manner. Since all shell-firing weapons, except possibly those of one-shot type, have barrels made of steel which are both electrically conductive and magnetic, however, inductive fuse programming was previously only possible before loading of the weapon or alternatively while the shell was being fed from a magazine to the cartridge chamber of the weapon. Furthermore, EP-A1-0300255 and EP- Al-0467055 describe proposals for how the same type of inductive programming can be carried out immediately after the shell has left the barrel. In these variants, it is proposed that the coil which is to supply the programming signal be placed immediately outside the mouth of the barrel so that the shell passes through it. For various reasons, these solutions have proved to be more difficult to implement in practice than was originally theoretically assumed would be the case. Then, as far as programming further away from the firing point is concerned, along the actual missile trajectory, this involves such great technical complications that, although they are by no means insurmountable, they would probably only be justified in terms of effectiveness in larger calibres such as 10.5 cm and above. As an alternative to the previously used variants indicated above, both a new method and a new arrangement are now proposed according to the present invention for inductive programming directly in the cartridge chamber of the programmable time fuses for the shells of shell- firing barrel weapons intended for both single-shot and also semi-automatic and fully automatic firing. The invention is based on the fact that that part of the material in the barrel of the weapon which constitutes the cartridge chamber of the weapon is replaced by a non-magnetic insert around which one or more coils for inductive programming of the time fuse of the shells are wound. However, the problems are not completely solved by this arrangement alone. This is because a further prerequisite in order for it to be possible for the inductive programming of the time fuses to function is that this non-magnetic insert is not electrically conductive either. If it were electrically conductive, it would form a short-circuited layer which would prevent the programming signal being transmitted to the time fuse of the shell. It would be possible to satisfy both these conditions immediately if the insert could be made of a material which was not magnetic and had such poor electric conductivity that it was of the type which is usually referred to as electrically non- conductive material. Since it must now also be taken into account that the material in the insert must withstand the high temperature and the high pressure which occur in the barrel on firing, however, the number of possible materials is very limited. One group of materials which are both non-magnetic and electrically non-conductive and which therefore, in particular considering the fact that they are known for being hard, hard-wearing and heat- resistant, would theoretically be suitable for producing cartridge chamber inserts of the type in question are the so-called ceramic metals. As a rule, however, these materials are brittle, for which reason it would be difficult today to produce entire cartridge chamber inserts of the type in question from such ceramic metals. According to a preferred development of the invention, it is therefore proposed that the cartridge chamber inserts themselves are made of a non-magnetic metal with sufficiently high hardness and heat resistance such as e.g. niobium or stainless steel, a direct short- circuiting of the surrounding coils being prevented by the insert being provided with a gap in the longitudinal direction of the barrel. Electric insulation of the gap can in this connection advantageously be constituted by a suitable ceramic metal. If the insert is made of stainless steel for example, there is nothing to prevent the barrel rifling being continued into the insert. This presupposes, however, that the insert is fastened non-rotatably in the barrel . The invention has been defined in its entirety in the following patent claims at the same time as it will now be described in somewhat greater detail in conjunction with the attached figures. The invention has here been illustrated in a variant conceived for use on a so-called shell sprayer. As this type of weapon is generally known and exists in a number of variants with mechanically similar operation, only components essential for the invention have been included in the figures, in which Fig. 1 shows a longitudinal section through the part of the barrel which constitutes the cartridge chamber of the weapon, while Fig. 2 shows the same longitudinal section but with a shell rammed home in the cartridge chamber (the shell itself is sectioned only in the part which is significant for understanding the invention) , while lastly Fig. 3 shows the section III-III in Fig. 1. The barrel 1 shown in the figures is provided with a rifling 2 indicated internally. In the rear part of the barrel, there is a bore 3 in which on the one hand a front insert 4 and on the other hand a rear fastening ring 5 are inserted. The front insert 4 can be shrink- fitted or locked with wedges while the rear fastening 5 is shrink-fitted securely. The insert 4 is provided with a gap 6 which is filled with a ceramic metal which is an electrically non-conductive material. Running around the insert 4 is at least one external groove 7 in which at least one induction coil 8 is arranged. The coil(s) 8 is (are) connected by means of the cables 9 and 10 to a programming device 11 which can be set to transmit optional range/time programming to the shell . The shell 12 in question is shown in Fig. 2 as a part of the complete charge 13. The latter also includes the cartridge case 14, filled with propellant, with a rear percussion cap 15. The thrust band 16 of the shell can also be seen in the figure. In the figure, the shell is shown in its rammed-home position in the cartridge chamber of the barrel 1. Components in the front sectioned part of the shell which are significant in connection with the invention include its front cover or cap 17 made of plastic. Embedded in the material of the cap is a receiving coil 18 which is electrically connected to the electronic time fuse function 21 of the shell by the cables 19 and 20. With the arrangement shown in the figure, time programming set in the electronic programming device 11 can be transmitted inductively via the coil 8 to the coil 18 which in turn conveys this information on to the time fuse function 21. With the aid of this arrangement, the shell 12 can always be programmed very close to or during the introductory firing phase.

Claims: PATENT CLAIMS 1. Method in order to make possible, in both single- shot and also semi-automatic and fully automatic shell- firing barrel weapons and in particular in those which are provided with rifled barrels made of steel (1) , contactless inductive transmission of programming data to a programmable time fuse function (21) included in the respective shell, characterized in that this is carried out while the respective shell (12) is situated in the cartridge chamber of the barrel (1) , the data concerned being transmitted to the programmable time fuse function (21) of the shell (12) from the programming device (11) . of the weapon, via a transmitting coil (8) arranged around the cartridge chamber of the shell, to a receiving coil (18) arranged in the shell, at least that part of the barrel (1) which lies between the coils being replaced by a non-magnetic material and designed so that it does not form an electrically conductive short- circuited layer which would prevent transmission between the coils. 2. Method according to Claim 1, characterized in that the time fuse function (21) of the respective shell (12) is time-programmed to detonate after a given trajectory length. 3. Arrangement in order to make possible, in accordance with the method according to Claim 1 or 2, in both single-shot and also semi-automatic and fully automatic shell-firing barrel weapons and in particular in those which are provided with rifled barrels (1) made of steel, contactless inductive transmission of programming data to a programmable time fuse function (21) included in the respective shell (12) while the shell (12) in question is still situated in the cartridge chamber of the barrel (1) , characterized in that the barrel (1) of the weapon around the cartridge chamber arranged there is provided with an insert (4) made of non-magnetic material which surrounds at least that part of the cartridge chamber which is occupied by the shell (12) itself and around which one or more electromagnetic coils (8) for inductive transmission of programming data to the time fuse function (21) of the shell (12) are wound, said insert (4) being designed in such a manner that it does not form an electrically conductive short- circuited layer. 4. Arrangement according to Claim 3, characterized in that the insert (4) in question is made of a non¬ magnetic metal such as stainless steel, niobium or equivalent and in that this insert is divided transversely to the winding direction of the coils (8) by at least one gap (6) which is in turn filled with an electrically insulating material (6) . 5. Arrangement according to Claim 4, characterized in that said electrically insulating material (6) is constituted by a ceramic metal. 6. Arrangement according to one of Claims 3 - 5, characterized in that said insert (4) is non-rotatably and non-displaceably fastened in the barrel (1) by means of shrink-fitting, wedges or in another known manner.

Inventors: FOHRMAN ERIK, HAGSTROEM BJOERN, JERN SVEN-AAKE, JOHANSSON NILS, LARSSON ROLF, FOHRMAN, ERIK, HAGSTROEM, BJOERN, JERN, SVEN-AAKE, JOHANSSON, NILS, LARSSON, ROLF
Applicants: BOFORS AB, FOHRMAN ERIK, HAGSTROEM BJOERN, JERN SVEN AAKE, JOHANSSON NILS, LARSSON ROLF, FOHRMAN, ERIK, HAGSTROEM, BJOERN, JERN, SVEN-AAKE, JOHANSSON, NILS, LARSSON, ROLF
Application year: 1997
Main classification: F42C17
IPC codes: F41F3, F42C17