EP0741855A1

EP0741855A1 - Firing mechanism

Info

Publication number: EP0741855A1
Application number: EP95903478A
Authority: EP
Inventors: Pär Andersson; Sten Hallqvist
Original assignee: Bofors AB
Current assignee: Saab Bofors AB
Priority date: 1993-12-08
Filing date: 1994-11-24
Publication date: 1996-11-13
Also published as: SE9304075D0; IL111835A0; SE502027C2; SE9304075L; WO1995016182A1

Abstract

The present invention relates to an improved type of firing mechanism for barrel weapons, in the first place mortars (1), of the type which comprises a striker pin (9) which is mounted in the rear piece (2) of the gun and is provided with a separate return function (10) for bringing back to the non-firing position and which can, by means of a striker hammer (13) likewise mounted in the rear piece of the gun and displaceable towards the striker pin (9) under the action of a striker spring (14), be acted on in the direction of the firing position. It is characteristic of the arrangement according to the invention that the return function (10) of the striker pin (9) is coupled together with the movements of the striker hammer (13) in such a manner that the striker pin can only reach the firing position in association with it being struck by the striker hammer, subsequently to be brought back to a position in wich no initiation of a shell which has been guided down into the barrel of the weapon can take place.

Description

Firing mechanism

The present invention relates to a firing mechanism which is safeguarded against premature firing and is intended in the first place for heavy and medium- heavy mortars but can also be used for other similar purposes.

The firing mechanism according to the invention is of the general type in which the firing function is actuated by a cam curve which is rotated by means of a lever and which, as it is rotated, first prestresses a striker spring by forcing backwards a striker hammer connected to the latter, in order subsequently in its end position to release the striker hammer so that the latter, driven by the striker spring, can act on a striker pin provided with a separate return function so that this initiates the propelling-charge igniter on a shell already guided down into the barrel of the mortar.

Firing mechanisms of this general type have existed for a long time and they are therefore used mainly in heavy and medium-heavy mortars since it is in this case desirable to allow the loader to get out of the way before the shot is fired. Most mortars, with of course the exception of some of the very heaviest guns, have been front-loaded. The intention in using firing mechanisms of the general type now in question has therefore been that, on loading, the shells are to be able to slide down to the bottom of the barrel without, as in the case of light mortars, being fired directly by contact with a striker pin mounted rigidly in the bottom of the barrel, whereupon it is to be possible for firing, when required, to take place by actuation of the firing mechanism. With this type of firing mechanism, it is therefore possible to have the guns standing loaded for firing at a time determined later.

A general weakness with earlier variants of this general type of firing mechanism has, however, been the separate return function of the striker pin. This is because this has had a tendency, after being used for a long time, to get stuck in the firing position, which meant that the shells were fired directly when they reached the bottom of the barrel, entirely in accordance with the function of light mortars. The fact that such unintentional firing could take place in spite of the striker hammer having been blocked by a separate safety function meant a further unsafeness factor. This weakness in earlier firing mechanisms has in peace time meant a safety risk and could, in the event of war, mean even greater risks in that the gun then reveals its position prematurely. The return function in question has in its simplest and probably most usual form consisted of a cup spring which in the normal state held back the striker pin from the firing position but at the same time allowed it to strike towards this position when it was struck by the striker hammer on the return stroke of the latter.

According to the present invention, this problem has now been solved by the striker pin, the striker hammer and the striker spring in firing mechanisms of the general type in question here being surrounded by a displaceable tubular sleeve which can be adjusted from a first position, corresponding to everything but the firing position, to a second position corresponding to this firing position, and the sleeve comprising at least one blocking heel designed to interact with at least one corresponding heel on the striker pin, and said heels, in the first position of the sleeve, forcing back the striker pin from the firing position, while the striker pin, with the sleeve in its second position, is free to initiate the propelling-charge igniter of the shell as soon as it is reached by the striker hammer, and the position of the sleeve being determined by a member, the movement of which is coordinated with the eccentric which is used for prestressing the striker spring by the eccentric forcing back the striker hammer connected to the striker spring and, in the turning position of the striker hammer, releasing the same, and this coordination being carried out in such a manner that the sleeve adopts its second position only immediately before the striker hammer reaches its prestress/turning position in which the eccentric comes to lose its grip of/on the striker hammer.

The tubular sleeve which is characteristic of the firing mechanism according to the invention can advantageously be designed with a centred cavity which is designed in its front part facing towards the bottom of the barrel of the weapon and which provides space for the main part of the front part of the striker pin, together with a return spring clamped in between the bottom of the barrel of the weapon and an annular contact edge on the striker pin, while the sleeve has, in its rear part facing away from said bottom of the barrel, a rear centred cavity which provides space for a striker hammer extending in the longitudinal direction of the sleeve, together with a striker spring surrounding the hammer at least partly, and there running between these two cavities a duct which provides space for the rear part of the striker pin together with the return heels of the pin and of the sleeve.

According to a further development of the firing mechanism according to the invention, the striker hammer thereof is designed in such a manner that, when it is thrown towards the striker pin by the striker spring, it first acts on the pin, immediately subsequently to be forced backwards to a position in which it does not have direct contact with the striker pin. This function is achieved by the striker hammer being provided with a front stop edge which bears against the striker spring via a guide washer, the guide washer being wider than the front part of the striker hammer and, with the striker spring in the unloaded state, bearing against a stop edge adapted to it in the sleeve, which the front part of the striker hammer is in turn free to pass on its contact against the rear part of the striker pin at the same time as the striker hammer has in its other end a stop edge facing in the direction of the striker pin and against which a second guide washer bears, the outer dimension of which is adapted to the outer dimension of the striker spring, and a stop edge in the sleeve, which likewise faces in the direction of the striker pin, and the striker spring being clamped in between these two washers. With this design of the different components, a striker hammer is obtained which, when it is forced backwards by the previously mentioned eccentric, prestresses the striker spring clamped in between the first and the second guide washer at the same time as the second guide washer bears against the rear stop edge of the sleeve. When the eccentric, during its firing stroke, loses its grip on the striker hammer, the latter is driven forwards by the striker spring in the direction of the striker pin and its front part passes the stop edge at the front guide washer and reaches the striker pin. Immediately beforehand, however, the rear stop edge of the striker hammer has reached the rear guide washer and in so doing, as a consequence of its own kinetic energy, started to compress the striker spring from the rear. This compression comes as soon as the striker hammer has discharged its kinetic energy to the striker pin to lead to the striker hammer being forced backwards from its contact with the striker pin. It also forms part of the invention that the tubular movable sleeve, after having been situated in its second position when the striker hammer reaches the striker pin, is to be brought back to its first position as soon as the striker pin has accomplished initiation of the propelling-charge igniter of the shell. This can advantageously be achieved by the movements of the sleeve being coupled together with the movements of the eccentric in such a manner that the sleeve is guided towards its second position immediately before the eccentric, under the tension of- the striker spring, reaches the position in which it loses its grip of the striker hammer. In the same manner, the sleeve is forced backwards to its first position as soon as the eccentric starts its return stroke to the original position and, in so doing, the heels of the sleeve draw the striker pin backwards to its safety position. This control of the movements of the sleeve can advantageously be arranged so that a number of eccentrics are mounted on the same shaft, one of which controls the prestress and the firing of the striker hammer while the other controls the movements of the sleeve.

The firing arrangement according to the invention is defined in the following patent claims and it is now to be described in somewhat greater detail in association with attached figures, in which:

Fig. 1 shows quite generally a mortar with a barrel.

Figs 2 - 4 show a cross-section through the rear piece of the mortar according to Fig. 1 with the firing mechanism according to the invention in three different functional positions, and

Figs 5 and 6 show oblique projections of the firing handle with associated eccentrics. The mortar shown in Fig. 1 consists of a barrel

1 with associated rear piece 2, support plate 3, a bipod support 4 and vertical and horizontal aiming arrangements 5 and 6 respectively. There are also vehicle-mounted mortars and those with a number of barrels, and extremely heavy mortars which are collapsible for loading from the rear, but the basic principle with barrels which during firing are directed very steeply upwards together with the use of fin-guided projectiles which themselves contain necessary propellant is found in all these cases. Figures 2-4 then show the rear piece 2 in cross- section. This includes the main part 2a of the rear piece, which is screwed firmly into the rear part of the barrel by means of the thread 2b. Also included is a cap 7 screwed into the front part of the rear piece 2, and a tubular sleeve 8 which is displaceable in a cavity 2c adapted thereto partly in this cap and partly in the main part 2a of the rear piece and which consists of a front part 8a and a rear part 8b. Arranged displaceably in a recess 8a' in the front part 8a of the sleeve is a striker pin 9. The front ignition tip 9a of the striker pin 9 has, via an opening 7a in the uppermost part of the cap 7, free passage into the barrel and, in its front position, reaches the place in which the propelling- charge igniter on a shell guided down into the barrel comes to be situated. The striker pin 9 also comprises a stop edge 9b facing upwards in the direction of the barrel and a return spring 10 clamped in between this edge and the inside 7b of the cap 7. In its rear part 9c, the striker pin 9 is provided with a return heel 11. Corresponding to this is a return heel 12 in the front part 8a of the sleeve 8. Arranged displaceably in the rear part 8b of the sleeve 8 is a striker hammer 13. This is surrounded by a striker spring 14 of the helical- spring type. In the rest position, the striker spring 14 is clamped in between an upper guide washer 15 and a lower guide washer 16. The upper guide washer 15 bears in turn against a stop edge 8c, facing away from the barrel, in the upper sleeve part 8a while the lower guide washer 16 bears in turn against a stop edge 8d facing in the direction of the barrel and designed in the lower sleeve part 8b.

In its front part, the striker hammer 13 has a hammer head 13a which in the rest position, by means of its own stop edge 13b, bears against the upper guide washer 15 but does not itself have a greater diameter than can pass the stop edge 8c. The hammer head 13a has in itself the same diameter as the free diameter inside the return heel 11. The striker hammer 13 also has, in its part facing away from the barrel 1, a stop edge 13c which in the rest position bears against the outside of the lower guide washer 16.

In the lowest part of the striker hammer outside the part which is surrounded by the striker spring 14 and beyond the stop edge 13c, a cocking heel 17 of a type known per se is mounted movably about a spindle 18. This cocking heel is in turn spring-loaded so that its free upper end 17a tends to move out towards the sleeve 8. At the height of the upper edge 17a of the cocking heel 17 when everything is in the rest position, a multi-plate eccentric 19 is mounted rotatably in the main part 2a of the rear piece.

As can be seen from Figures 5-6, this eccentric actually comprises three eccentric plates arranged on the same shaft 20, the central one 19a of which passes through an opening 8e in the sleeve 8 and, on rotation of the eccentrics 19a-c, is first brought with its cocking edge 19a' into contact with the upper edge 17a of the cocking heel 17 and then forces the cocking heel 17 and the striker hammer 13 backwards and downwards under prestress by the striker spring 14. At the same time, the two remaining eccentrics 19b and 19c displace the sleeve 8 from the rear first position shown in Figure 2 to the front second position shown in Figures 3 and 4. This means that the stop edges 11 and 12 no longer bear against one another and the striker pin 9 is free to move forwards provided that the force from the return spring 10 can be overcome. The eccentrics 19a and 19b also pass in through the opening 8e and act directly against the upwardly and respectively downwardly delimiting edge sides 8e' and 8e'' respectively thereof and control in this manner the displacement of the sleeve by raising it or pressing it backwards respectively. When the eccentric 19a has reached its lowest position shown in Fig. 3, its cocking edge 19a' slides off from the upper edge 17a of the cocking heel 17 and this edge 17a comes instead into contact with the curve- shaped part 19a'' of the eccentric 19, from which it comes to slide off when the cocking heel 17 is forced towards the side against the action of its own spring. The striker hammer 13 is then released and this is driven by the striker spring 14 in the direction of the striker pin 9. The head 13a of the striker hammer passes the stop edge 8c and drives the striker pin 9 forwards at the same time as the guide washer 15 is intercepted by the stop edge 8c and a part of the kinetic energy of the striker hammer is utilized for a limited compression of the striker spring this time from the rear with starting point from the guide washer 16 which is in turn forced forwards by the stop heel 13c. As soon as the striker hammer 13 has discharged its kinetic energy to the striker pin 9, its limited prestress brought about from the rear draws the striker hammer back from its direct contact with the striker pin.

The eccentrics 19a, b and c are expediently connected in a known manner to a return spring which has not, however, been drawn in the figures. When the eccentrics begin their return stroke, the eccentric 19a passes by the cocking heel 17 which gives way while the eccentrics 19b and c, by bearing against the edge 8e", displace the tubular sleeve 8 which is characteristic of the invention back to its first position. At this, by bearing against the stop edge 11, the stop edge 12 forces the striker pin 9 back to the position which is shown in Figures 2 and 3. In a normal case, the return spring 10 does this on its own but the displaceable tubular sleeve which is characteristic of the invention constitutes a complete guarantee that, as soon as the handle 21 with which the eccentrics are manoeuvred has returned to its original position, there is no longer any possibility of the striker pin remaining in its front firing position. In the figures, the less important components are also given, 22 being a stop screw for the eccentric rotation and 23 marking a decompression duct. The reference 24 in turn marks the lever with which the eccentrics are manoeuvred.

Claims

Patent Claims

1. Firing mechanism for barrel weapons, in the first place mortars, of the type which comprises a striker pin (9) which is mounted in the rear piece (2) of the gun and is provided with a separate return function (10) for bringing back to the non-firing position and which can, by means of a striker hammer (13) likewise mounted in the rear piece of the gun and displaceable towards the striker pin (9) under the action of a striker spring (14), be acted on in the direction of the firing position, the striker hammer (13) in turn being capable of being displaced, by an eccentric (19) which can be rotated by means of a lever, against the action of the striker spring (14) to a prestress position in which the eccentric (19) loses its grip on the striker hammer (13) and this being driven towards the striker pin (9) by the striker spring (14) , characterized in that the striker pin (9), the striker hammer (13) and the striker spring (14) are surrounded by a displaceable sleeve (8) which can be adjusted from a first position, corresponding to everything but the firing position, to a second position corresponding to this firing position, and said sleeve (8) comprising at least one blocking heel (12) designed to interact with at least one corresponding heel on the striker pin (11), and said heels (11 and 12 respectively), in the first position of the sleeve (8), forcing back the striker pin (9) from the firing position, while, with the sleeve (8) in its second position, the pin is free to initiate the propelling- charge igniter of the shell as soon as it is reached by the striker hammer (13), and the position of the sleeve (8) being determined by a member (19b or c respectively), the movement of which is coordinated with the movements of said eccentric (19a) in such a manner that the sleeve (8) adopts its second position only immediately before the striker hammer (13) reaches the prestress position in which the eccentric (19a) loses its grip of the same.

2. Firing mechanism according to Claim 1, characterized in that the sleeve (8) has, in its front part facing towards the bottom of the barrel of the weapon, a centred front cavity (8a') which provides space for the front part of the striker pin (9), together with a return spring (10) of the helical spring type clamped in between the bottom of the barrel of the weapon and an annular contact edge (9b) on the striker pin, while the sleeve (8) has, in its rear part (8b) facing away from said bottom of the barrel, a rear centred cavity which provides space for a striker hammer (13) extending in the longitudinal direction of the sleeve, together with a striker spring (14) surrounding the hammer, and there running between these two cavities a duct which provides space for the rear part of the striker pin (9) together with the return heels (12 and 11 respectively) of the pin and of the sleeve.

3. Firing mechanism according to Claim 1 or 2, characterized in that the striker hammer (13) has a front stop edge (13b) which bears against the striker spring via a guide washer (15) , the guide washer being wider than the front part (13a) of the striker hammer and, with the striker spring in the unloaded state, bearing against a stop edge adapted to it in the sleeve (8c) which the front part (13a) of the striker hammer is free to pass on its contact against the rear part of the striker pin (9) .

4. Firing mechanism according to one of Claims 1-3, characterized in that it comprises a first eccentric plate (19) mounted in the rear piece (2) of the gun about a spindle (18) arranged transversely to the barrel direction of the gun, with a cocking edge (19a') which, on rotation of the eccentric, is brought into contact with the free end of a cocking heel (17) which is mounted in the rear part of the striker hammer (13) about a transverse-running spindle (18) and is pressed by a spring in the direction of the eccentric (19a), together with at least one other eccentric plate (19b and c), the movements of which are coordinated with the first eccentric plate (19a) and the movements of which control the movements of the movable sleeve (8) in the manner indicated.

5. Firing mechanism according -to one of Claims 1-4, characterized in that the first (19a) and the other eccentric (19b and c) are located on the same shaft (20).

6. Firing mechanism according to one of Claims 1-5, characterized in that it comprises a safety handle which is mounted separately in the rear piece of the gun and with which the movable sleeve can be blocked in its first position.