EP2434252B1 - Security and arming device for a gyrostabilised explosive projectile and priming device implementing such a security and arming device - Google Patents

Description

The technical field of the invention is that of priming devices (rockets) of gyro-stabilized projectiles and in particular that of the safety and arming devices equipping these priming devices.

Gyro-stabilized explosive projectiles, and in particular medium-caliber projectiles (caliber less than 50 mm), most often comprise a safety and arming device that incorporates a primer rotor which is released consecutively to the firing of the projectile. This rotor has an imbalance that ensures alignment of the primer with the rest of the pyrotechnic priming chain.

Licences FR-2689972 and FR-2533686 describe such safety and arming devices. The unbalanced rotor is placed in a cage which is free to rotate relative to the axis of the projectile.

A disadvantage of these known devices is that they require the establishment of a primer (and therefore a pyrotechnic component) on the rotor. The primer must also be of relatively small size for medium-sized applications (caliber less than 50 mm).

Another disadvantage is that if this solution is well suited to projectiles in which the rotor primer is initiated by percussion, it is more difficult to implement for a projectile in which the primer is initiated by an electric current supplied by a electronic firing control means. Such modes of operation are adopted when one seeks to make projectiles using a programmable time rocket.

It is indeed difficult to make flexible conductors that can accompany the pivoting of the rotor primer without disturbing the movement of the latter.

It is also known from the patent EP-1780495 a security and arming device comprising a screen formed by two half-screens which close off a channel of transmission connecting a detonator and a pyrotechnic relay.

These half screens are movable by the action of motor means, for example one or more springs, which are released by electrically controlled locks.

Such a solution is particularly well suited to an embodiment in the form of microelectromechanical integrated circuits. However for a realization of screens of larger dimensions, the motor means or the control locks become difficult to integrate especially in a projectile of medium caliber.

The patent is still known FR-1184670 describing a security and arming device comprising a screen formed of two half-screens which close off a transmission channel connecting a detonator and a pyrotechnic relay. These two screens are able to move relative to each other and transversely to the transmission channel and being locked in the closed position by a first inertial lock fading when firing the projectile. In this device, there is no interaction with a rotor.

The object of the invention is to propose a safety and arming device that is easily integrable into a projectile, even of reduced caliber. This device allows the use of an electric initiation detonator without imposing its implementation in a rotor.

The invention thus proposes a safety and arming device which can be housed in the bulk of the known rotor devices.

Thus, the subject of the invention is a safety and arming device for a gyro-stabilized explosive projectile, a device comprising a screen closing a transmission channel connecting a detonator and a pyrotechnic relay, the screen consisting of two half-screens. being movable relative to each other and transversely to the transmission channel the two half-screens closing the channel when in contact with each other, the two half-screens being slidably mounted in a bore, the two half-screens being moreover locked in the closed position of the channel by a first latch or inertial lock which fades when firing the projectile, characterized in that said bore is carried by a coaxial rotor at projectile, rotor which is itself pivotally mounted relative to the axis of the projectile and which carries the transmission channel, and in that the two half-screens are also locked in the closed position of the channel by a second lock or centrifugal latch which is constituted by a spiral spring surrounding an outer cylindrical surface of the rotor and thus applied against the ends of the half-screens, spiral unwinding under the effect of the centrifugal force.

Advantageously, the half-screens are made in the form of cylindrical rods, having an end in contact with the spiral which is in the form of a spherical cap.

The rods forming the half-screens will preferably contact each other by their ends comprising conical machining of complementary shapes.

The first lock may be constituted by a ring slidably mounted relative to the rotor and having an internal conical bearing surface which abuts against the half-screens, the ring comprising an external groove receiving a circular metal ring which bears on an integral abutment. device, ring ensuring the axial immobilization of the ring before firing the projectile and which is deformed by the effect of the axial acceleration during firing to escape the stop and allow the translation of the ring.

The metal ring is carried by a circular rim of the ring which is introduced during the translation of the ring in a groove of a fixed plate.

The invention also relates to a priming device comprising such a safety and arming device, ignition device incorporating an electric initiation detonator whose mounting and integration are facilitated.

This priming device is characterized in that the detonator is disposed along the axis of the projectile and connected to an electronic card of a firing module.

The electronic card may carry a cup surrounding at least partially the detonator cup ensuring electrical contact between the card and the detonator.

• la figure 1a représente en coupe longitudinale partielle un dispositif d'amorçage d'un projectile moyen calibre incorporant un dispositif de sécurité et d'armement selon l'invention, le dispositif de sécurité étant représenté à l'état de sécurité,
• la figure 1b est une vue agrandie d'une partie du dispositif de la figure 1a,
• les figures 2a, 2b et 2c représentent trois états successifs de ce dispositif de sécurité, la figure 2a montrant le dispositif après la libération du premier verrou, la figure 2b après celle du deuxième verrou et la figure 2c à l'état armé.

The invention will be better understood on reading the following description of a particular embodiment, a description given with reference to the appended drawings and in which:

• the figure 1a represents in partial longitudinal section a device for initiating a medium caliber projectile incorporating a safety and arming device according to the invention, the safety device being represented in the safety state,
• the figure 1b is an enlarged view of part of the device of the figure 1a ,
• the Figures 2a , 2b and 2c represent three successive states of this safety device, the figure 2a showing the device after the release of the first lock, the figure 2b after that of the second lock and the Figure 2c in the armed state.

Referring to the figure 1 , a priming device (or rocket) 1 according to the invention comprises a firing module 2 which incorporates an electronic card 3 on which is fixed a detonator 4.

The detonator 4 is electric initiation. It comprises an axial pin 4a which is directly connected to the electronic card 3. Moreover, the electronic card 3 carries a conductive cup 5 (soldered to the card) which at least partially surrounds the detonator 4 and provides another electrical contact between card 3 and detonator 4.

The detonator 4 is here fixed, arranged along the axis 6 of the projectile and connected to the electronic card 3 of the firing module 2.

This results in a simplified mechanical assembly of this pyrotechnic element.

The electronic module 2 is disposed in a base 7 which closes the rear of a projectile and it is fixed to the body 8 of the latter. The complete projectile is not represented on the figures. A part of its external profile has been shown by broken lines.

The base 7 carries a belt 9 intended to seal the gas when fired in a weapon.

The priming device 1 also incorporates a safety and arming device which comprises a screen 10 closing a transmission channel 11 connecting the detonator 4 and a pyrotechnic relay 12. The transmission channel 11 has the same axis 6 as the projectile. The detonation relay 12 is intended to initiate an explosive charge (not shown) disposed inside the body 8.

The screen 10 is constituted by two half-screens 10a and 10b which can move relative to one another and transversely with respect to the transmission channel 11. These two half-screens 10a and 10b close the channel 11 when they are in contact with each other, in the safety position represented in figure 1a .

Each half-screen 10a or 10b is made in the form of a cylindrical rod which is slidably mounted in a cylindrical bore 13 arranged in a rotor 14 which is coaxial with the projectile ( figure 1b ). The bore 13 is perpendicular to the transmission channel 11 which is also pierced in the rotor 14.

The rods 10a and 10b forming the half-screens are in mutual contact with their ends 25a and 25b which comprise conical machining of complementary shapes ( figure 1b ). Thus, the half-screen 10b has an end 25b having a male cone, while the half-screen 10a has at its end 25a a female cone. The complementary conical shapes facilitate the adaptation of the half-screens during assembly.

Thanks to such an arrangement the interface between the two half-screens is not flat and the stopping of an effect pyrotechnic is provided as efficiently as if the screen was monobloc.

The rotor 14 is mounted free to rotate with respect to the axis 6 of the projectile and therefore relative to the priming device 1. It thus comprises cylindrical journals 14a and 14b which are positioned in integral complementary spans of the priming device 1 .

We notice on figures 1a , 1b that the priming device contains a sleeve 15 which is housed in a bore 16 of the base 7 and which carries a partition 15a pierced and surrounding the detonator 4. This sleeve 15 receives a plate 17 which has a cylindrical surface receiving the rear trunnion 14b rotor 14. The plate 17 also has a circular groove 18 and having the same axis 6 as the projectile throat whose function will be specified later.

Inside the bore 16 of the base 7 are also housed a washer 19 and a spacer cage 20 which is applied against the washer 19 by a rear threaded plug 21 which closes the safety device and arming.

The threaded plug 21 has a wall 21a ( figure 1b ) which has a cylindrical bearing receiving the front pin 14a of the rotor 14.

The threaded plug 21 is screwed into a connecting ring 22 which is itself screwed to the base 7 of the device.

We notice on figures 1a and 1b that the screwing of the plug 21 makes it possible to axially link to the base 7 the various parts of the safety and arming device and in particular: the spacer 20, the washer 19, the plate 17 and the rotor 14.

We notice on figures 1a and 1b the presence of a ring 26 between the spacer 20 and the plate 17. This ring 26 constitutes a first latch (or inertial lock) ensuring the maintenance of the two half-screens 10a and 10b locked in the closed position of the channel 11.

The ring 26 is slidably mounted with respect to the rotor 14 and has an internal conical bearing surface 26a which (in the locked position of the device) bears against the half-screens 10a and 10b and locks them in the safety position (shutting off the channel ).

The ring 26 also has an external groove which receives a circular metal ring 23. In the locked position ( figures 1a , 1b ) of the device, this ring 23 bears against an abutment which is formed by a conical surface carried by the washer 19.

The outer groove of the ring 26 carrying the ring 23 is carried by a circular rim of the ring which has a thickness less than the width of the groove 18. Thus, when the device is unlocked, the ring 26 can be introduced into the groove 18 of the plate 17.

The security and arming device finally comprises a second latch (or centrifugal latch) which is constituted by a spiral spring 24 which surrounds the outer cylindrical surface of the rotor 14. This hairspring is therefore applied against the ends of the half-screens 10a and 10b.

Such a spiral spring is already known including patents FR-2689972 and FR-2533686 . It unfolds progressively as a result of the centrifugal force due to the rotation of the projectile. This unwinding is made possible because of the freedom to pivot the rotor 14 relative to the rest of the device 1. It causes a differential rotation between the rotor 14 and the body of the device 1.

Thus, during the rotation of the projectile, an outer end of the hairspring will move away from the rotor 14 to bear against the inner cylindrical surface of the spacer 20. The hairspring will unfold gradually by inducing a rotation differential between the rotor 14 and the spacer 20 and will eventually come off completely from the rotor 14 to be fully applied against the spacer 20.

We notice on figures 1a and 1b each rod 10a and 10b has one end in contact with the spiral 24 which is in the form of a spherical cap (of radius equal to that of the rotor). Such an arrangement makes it possible to have a linear (circular) contact between the rods 10a, 10b and the spiral 24. This avoids marking the spiral spring 24.

The operation of the safety and arming device will now be described with reference to Figures 2a to 2c .

The figure 2a shows the state of the device at the time of the shot. The axial acceleration received by the projectile caused the recoil of the ring 26, which caused the deformation of the ring 23 which escapes its abutment surface on the washer 19. The ring 26 is translated and its circular rim s' introduced into the groove 18 of the plate 17.

The internal conical bearing surface 26a of the ring 26 is no longer supported against the half screens 10a and 10b. The ring 26 thus no longer locks the half-screens which remain however still immobilized in the safety position by the spiral 24.

The ring 23 also engages in the groove 18 and ensures immobilization of the ring 26 in its unlocked position ( figure 2a ).

The figure 2b shows the device after its exit from the barrel of the weapon and once traveled a safety distance of mouth of the order of a few tens of meters.

The rotation of the projectile caused the complete unwinding of the spiral 24 until its application against the inner surface of the spacer 20. The second latch of the half screens 10a and 10b is released.

This state is fugitive because the half-screens 10a and 10b, driven themselves by the centrifugal force, deviate from one another and are applied against the spiral 24 thus completely releasing the axial transmission channel 11 ( Figure 2c ).

The device is then in the armed state and the detonator 4 can initiate the relay 12 at the desired instant and programmed before firing.

Claims (7)

1. A safety and arming device for a spin-stabilised explosive projectile, such device incorporating a screen (10) obstructing a transmission channel (11) linking a detonator (4) and a pyrotechnic relay (12), the screen being constituted by two half-screens (10a, 10b) able to move with respect to one another and transversally with respect to the transmission channel (11), the two half-screens obstructing the channel when they are in contact with one another, the two half-screens (10a, 10b) being mounted able to slide in a bore hole, the two half-screens (10a, 10b) being furthermore locked into the position in which they obstruct the channel (11) by means of a first lock or inertial lock (26) which retracts when the projectile is fired, characterised in that said borehole is carried by a rotor (14) coaxial to the projectile, rotor which is itself mounted able to pivot with respect to the projectile's axis (6) and which carries the transmission channels (11), and in that the two half-screens (10a, 10b) are furthermore locked into the position in which they obstruct the channel (11) by means of a second lock (24) or centrifugal lock that is formed by a spiral spring surrounding an external cylindrical surface of the rotor (14) and thus applied against the ends of the half-screens (10a, 10b), such spiral unwinding under the effect of the centrifugal force.
2. A safety and arming device according to Claim 1, characterised in that the half-screens (10a, 10b) are made in the form of cylindrical rods which have one end in contact with the spiral (24) in the form of a spherical cap.
3. A safety and arming device according to Claim 2, characterised in that the rods forming the half-screens (10a, 10b) are in mutual contact by their ends incorporating matching conical machining (25a, 25b).
4. A safety and arming device according to one of Claims 1 to 3, characterised in that the first lock (26) is constituted by a ring mounted able to slide with respect to the rotor (14) and incorporating an internal conical seat (26a) that presses on the half-screens (10a, 10b), the ring incorporating an external groove receiving a circular metallic band (23) pressing on a limit stop (19) integral with the device, such band ensuring the axial immobilisation of the ring (26) before the projectile is fired and which is deformed through the effect of the axial acceleration during firing to escape the limit stop (19) and enable the ring (26) to translate.
5. A safety and arming device according to Claim 4, characterised in that the metallic band (23) is carried by a circular rim of the ring (26) that is introduced, during the translation of the ring, into a groove (18) in a fixed plate (17).
6. A priming device (1) implementing such a safety and arming device according to one of Claims 1 to 5, priming device characterised in that the detonator (4) is arranged along the projectile's axis (6) and connected to an electronic card (3) of a firing module(2).
7. A priming device according to Claim 6, characterised in that the electronic card (3) carries a cup (5) at least partially surrounding the detonator (4), such cup ensuring an electrical contact between the card (3) and the detonator (4).

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