EP0991910B1 - Delay action fuse assembly for pyrotechnical device - Google Patents

Abstract

The invention concerns a delay action fuse assembly for a pyrotechnical device, in particular a hand or mechanical grenade, comprising a body (4) wherein is contained a main charge (66) and a triggering lever (16) co-operating with a delay action device (8) ensuring the initiation of the charge (66) with a predetermined delay after the lever is actuated (16). The fuse assembly further comprises a locking member (18) blocking the lever (16) movement. The delay action device (8) comprises time delay means for ensuring initiation of the charge and electronic means for triggering the time delay means. Said electronic triggering means comprise means for comparing the time elapsed between the release of the locking member (18) and the lever (16) movement, to a reference time interval, to trigger the delay action device only if said time lapse is greater than said reference time interval.

Description

The present invention relates to an igniter plug delay for pyrotechnic device, in particular a manual or mechanical launch grenade, of the type comprising a body in which a main charge is contained and a release lever, cooperating with a delay device capable of ensuring the initiation of the charge with a predetermined delay after the movement of the lever, the plug further comprising a locking blocking movement of the lever.

Pyrotechnic devices fitted with such a plug igniter are very safe, especially when of their storage.

When in use, these devices present accidental tripping risks, a once the locking member, generally formed by a pin, is unlocked. Indeed, if the organ of unlock is accidentally unlocked and that the lever is free to move, the main load can be initiated, leading to the ignition of the craft.

The document FR A 2 510 250 which describes the preamble of claim 1, shows an igniter plug of this type. type, comprising timing means capable of ensuring a delayed initiation of charge and electronic means of triggering of the delay means.

Document FR A 2 343 992 shows an igniter plug having delay means whose departure is triggered by a rotation of the grenade around a point outside of this body.

Document FR A 2 483 068 shows an electronic rocket for hand grenade, with triggered timed detonator control circuit by erasing a screen interposed between the detonator and a relay boot.

These various devices again present risks of accidental release.

The object of the present invention is to eliminate the risk of such accidental triggering, and improve thus the safety of pyrotechnic devices equipped with a such plug, in their first phase of use.

To this end, the invention relates to a stopper delay igniter for pyrotechnic device, in particular manual or mechanical launch grenade, of the aforementioned type, characterized in that the delay device includes delay means capable of ensuring initiation delayed charge and electronic means of triggering of the timing means, which trigger means include comparison means the length of time between unlocking the locking member and the movement of the lever, at a reference duration, to trigger said means of delay only if said elapsed time is greater than said reference duration.

• les moyens de comparaison comportent des moyens d'estimation de ladite durée écoulée ;
• il comporte un interrupteur électrique normalement ouvert, dont la fermeture est commandée par le mouvement du levier, et la fermeture dudit interrupteur commande l'arrêt desdits moyens d'estimation ;
• il comporte un générateur électrique actionné par ledit organe de verrouillage lors de son déverrouillage, et ledit générateur électrique alimente ledit dispositif à retard ;
• il comporte des moyens d'éjection dudit générateur électrique, commandés par le mouvement du levier ;
• lesdits moyens d'éjection comportent un ressort maintenu initialement à l'état bandé par ledit levier et dont les extrémités prennent appui respectivement sur ledit générateur électrique et sur le corps du bouchon allumeur ;
• lesdits moyens électroniques de déclenchement comportent des premiers moyens de stockage de l'énergie électrique reliés audit générateur électrique et auxquels sont reliés lesdits moyens de comparaison pour leur alimentation en énergie électrique ;
• lesdits moyens d'estimation de ladite durée écoulée comportent une horloge alimentée par lesdits premiers moyens de stockage après leur charge, et l'estimation de ladite durée écoulée est donnée par la somme de la durée estimée de charge desdits premiers moyens de stockage et de la durée mesurée par l'horloge entre la fin de la charge desdits premiers moyens de stockage et le mouvement du levier ;
• le dispositif à retard comporte des seconds moyens de stockage reliés sélectivement par l'intermédiaire de moyens de commutation pilotés par lesdits moyens de temporisation soit aux premiers moyens de stockage, soit à un dispositif électronique d'initiation de la charge ;
• une résistance de charge est interposée entre les premiers et seconds moyens de stockage pour déterminer le temps de charge des seconds moyens de stockage ; et
• lesdits moyens de temporisation sont adaptés pour commander d'abord la connexion des seconds moyens de stockage aux premiers moyens de stockage en vue de leur charge en énergie électrique après une première période de temps et pour commander ensuite la connexion des seconds moyens de stockage au dispositif d'initiation de la charge après une seconde période de temps .

According to particular embodiments, the igniter plug may have one or more of the following characteristics:

• the comparison means include means for estimating said elapsed time;
• it comprises a normally open electrical switch, the closing of which is controlled by the movement of the lever, and the closing of said switch controls the stopping of said estimation means;
• it comprises an electric generator actuated by said locking member when it is unlocked, and said electric generator supplies said delay device;
• it comprises means for ejecting said electric generator, controlled by the movement of the lever;
• said ejection means comprise a spring initially maintained in the state bandaged by said lever and the ends of which bear respectively on said electric generator and on the body of the igniter plug;
• said electronic triggering means comprise first means for storing electrical energy connected to said electrical generator and to which said comparison means are connected for their supply of electrical energy;
• said means for estimating said elapsed time includes a clock powered by said first storage means after their charging, and the estimation of said elapsed time is given by the sum of the estimated duration of charge of said first storage means and the duration measured by the clock between the end of the charging of said first storage means and the movement of the lever;
• the delay device comprises second storage means selectively connected by means of switching means controlled by said timing means either to the first storage means or to an electronic device for initiating the load;
• a load resistor is interposed between the first and second storage means to determine the charging time of the second storage means; and
• said timing means are adapted to first control the connection of the second storage means to the first storage means with a view to charging them with electrical energy after a first period of time and to then control the connection of the second storage means to the device charge initiation after a second period of time.

• les figures 1 à 5 sont des vues en coupe et élévation longitudinale d'un bouchon allumeur selon l'invention à des stades successifs de fonctionnement ;
• la figure 6 est un schéma du dispositif électronique du bouchon allumeur des figures 1 à 5 ; et
• la figure 7 est un organigramme de fonctionnement du bouchon allumeur selon l'invention.

The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the drawings in which:

• Figures 1 to 5 are sectional views and longitudinal elevation of an igniter plug according to the invention in successive stages of operation;
• Figure 6 is a diagram of the electronic device of the igniter plug of Figures 1 to 5; and
• FIG. 7 is a flowchart of operation of the igniter plug according to the invention.

In its embodiment shown in Figures 1 to 5, the delay igniter plug for a machine pyrotechnic, is intended for a hand grenade. he has a plastic body 4 charged with fiberglass but which could be alternately made of light alloy or any other equivalent material.

On this body 4 are adapted a pyrotechnic module primary 6 comprising an electronic device delay 8, and a secondary pyrotechnic module 10. The primary pyrotechnic module 6 is mounted movable at sliding in a transverse bore 12 of the body. The secondary pyrotechnic module 10 is fixed at one end of bore 12 in the extension of the module primary pyrotechnics 6.

The body 4 is provided with an electric generator removable 14 connected by breakable electrical conductors to the delay device 8. This generator is formed for example by a dynamo. It is placed between two parallel walls of the body defining an open housing. It is held there by a frangible link, not shown.

The body 4 is further provided with a mechanism for control comprising a lever 16 articulated relative to the body. This lever is associated with a transverse pin 18 for locking equipped with a gripping ring 20. This pin locks the lever.

The lever 16 covers the upper part of the body 4 on which opens the open end of the bore 12. It is articulated at a first end on a metal jumper 22, engaged transversely in the body, and which holds the module on both sides primary pyrotechnics 6. The control mechanism also includes a finger 24, articulated around an axis transverse 26. This finger is movable in the plane of the figure 1 from a position applied against the generator electric 14 to a position where it is in contact with the upper part of the pyrotechnic module primary 6. This finger is loaded by a coiled spring 28 around the axis 26. This spring is initially maintained in the bandaged state. One end of the spring 28 is supported on the body 4 while its other end is supported on one side of the electric generator 14 as well as on the finger 24. The spring 28 constitutes both means of stress on finger 24 and ejection of generator 14.

The pin 18 has two branches 18A, 18B, extending substantially parallel and connected to each other the other by a connecting section on which is articulated the gripping ring 20. The first branch 18A is provided with a groove locally reducing its section. This branch 18A is received in a light 30 formed in the lever 16. This light has an arcuate shape, and its width is generally equal to the section of the first branch 18A in its narrowed area. An extremity 30A of light is widened and has dimensions allowing the passage of branch 18A. The other extremity light 30 is aligned with a peripheral groove 31 formed externally at the upper part of the primary pyrotechnic module 6, so that the branch 18A of the pin received in the light 30 is engaged tangentially in this groove, thus blocking the movements of the primary pyrotechnic module.

The second branch 18B of the pin 18 is engaged in a transverse hole 32 of the body 4. This second branch constitutes an actuator of the electric generator 14 and has along its length a rack section. The latter is suitable for cooperate with a pinion 34 disposed at the end of a shaft 36 of the electric generator.

We understand that in the position shown on Figure 1, the pin 18 prohibits the movement of the lever 16, movement of the primary pyrotechnic module 6 as well as the actuation of the electric generator 14.

The primary pyrotechnic module 6 includes a metal case 40, of light alloy, at the base of which is set a cup 42 whose length and diameter correspond to those of a coaxial chamber 44 provided in the secondary pyrotechnic module 10. The case metallic 40 basically contains the device electronic delay 8. It is closed at the top by a conductive pad 45 forming a contact electric. The delay device essentially comprises first and second storage means 46, 48, one microcontroller 50 and an electronic initiation device 52 arranged opposite a pyrotechnic composition initiation 54 which is contained in the part upper of the bucket 42. A microdetonator 56, constituting the primary explosive of the pyrotechnic chain, is arranged in the lower part of the bucket.

The base of the bucket 42 is integral with a pellet metallic 58 coming from material.

The upper end of the case 40 is mounted at sliding directly in bore 12, while the lower end of it is received in a case 60, protecting the secondary pyrotechnic module. A axial spacing is provided between the case 40 and the load main, to allow the sliding of the case 40 inside the case 60, after release of the jumper 22 and the first branch 18A of the pin.

The secondary pyrotechnic module 10 contains a detonation relay 62 consisting of an aluminum cup 64 containing a secondary explosive 66 and a capsule closure 68 which, in combination with the patch 58 arranged at the base of the bucket of the primary module 6, forms a screen between the microdetonator 56 and the explosive secondary 66 which constitutes the main priming charge.

In Figure 1, we see that the shape of the chamber axial 44 agrees with that of bucket 42 of the module primary 6 and that the capsule 68 has an opening axial in which, in the storage position, comes place the pad 58 of the primary module 6.

The electronic delay device will now be described with reference to figure 6.

As shown in this figure, the generator electric 14 is connected by breakable wires to the first storage means 46, formed for example by a capacitor of suitable capacity. A rectifier 80 is interposed between the electric generator 14 and the means storage 46. It allows the proper shaping of the voltage and in particular a limitation thereof for the purpose of charging the storage means 46. These the latter are linked by means of voltage threshold detection 82 at the microcontroller 50. This microcontroller which notably includes means clock is suitable for controlling switching means 84 arranged between the first storage means 46 and the second storage means 48. They are formed for example by an electronic switch. These means are suitable for selectively connecting the second storage means 48, also formed by a capacitor, to the first storage means 46 or to electric initiation device 52. A resistance of load control 86 is provided between the first 46 and the second 48 storage means, in order to impose the charging time of the second storage means 48.

Furthermore, a switch 88 is mounted in parallel to the terminals of the electrical initiation device 52. The switch 88 is formed by the jumper metallic 22, shorting the supply wires initiation device 52.

On the other hand, the microcontroller 50 is connected on the one hand to the conductive finger 24 and on the other hand to the pad 45, the latter forming together a switch 90 whose closure reflects the displacement of the lever 16.

The operation of the microcontroller 50 is piloted by a program managing and controlling the stages of the grenade. The organization chart of this program is described with reference to figure 7.

The operation of the igniter plug will now be described with reference to Figures 1 to 5 for mechanical aspects, and on the other hand figures 6 and 7, for aspects relating to the functioning of the electronic device controlled by the microcontroller 50.

In order to launch the grenade, the operator grasps its body in one hand, now lever 16 as he grabs the ring from grip 20 in the other hand. Using this, it rotates pin 18 around its second branch 18B, so that the first branch 18A comes place in the enlarged end zone 30A of the light, as shown in Figure 2. In this position, it is possible by pulling on the ring 20 to extract the pin. This step of removing the pin corresponds to step 100 of the organization chart of the figure 7. During the extraction, the rack carried by the second branch 18B drives the pinion 34, causing thus the rotation of the shaft 36 of the electric generator 14. The latter then delivers through the rectifier 80, thus loading the first storage means 46 (step 102). When a predetermined charging voltage threshold storage means 46 is detected, in step 104, by the threshold detection means 82, these connect the microcontroller 50 to the storage means 46 (step 106). The microcontroller is thus supplied. The duration obtaining the voltage threshold is substantially equal to 200 milliseconds. This duration is linked to the construction rectifier 80 and the nature of the electric generator 14 and storage means 46. As soon as it is powered up, the microcontroller 50 triggers, in step 108, duration estimation means, formed by a noted counter H1, incremented at a rate linked to the microcontroller's clock.

After extraction of the pin, the lever 16 is held by the operator's hand. So the counter H1 is representative of the duration of maintenance of the lever 16 from the start of the microcontroller. so that the microcontroller does not detect the closing of the switch 90, in step 110, it increments, to step 112, the counter H1. In step 114, it checks whether the duration measured by the H1 counter is greater than 30 minutes. If this duration is greater, the microcontroller stops, at step 116, the implementation of the process initiation of the pyrotechnic device. If the duration is less than 30 minutes, the microcontroller returns to step 110.

When the operator launches the grenade, the lever 16 is released. So, as shown in Figure 3, the lever pivots around its end linked to the jumper 22, releasing the spring 28. The latter, initially compressed, relaxes, ejecting the generator electric 14 in the direction of arrow F1. Simultaneously, the contact finger 24 is brought into contact with the pellet 45 by rotation about the axis 26 along the direction of arrow F2. This contact causes the closure of the switch 90 which is detected in step 110.

After closing the switch 90 translating the movement of the lever 16, the microcontroller brings work of comparison means which verify, at the stage 118, if the duration recorded by the H1 counter is greater at 100 milliseconds. This amounts to checking whether the duration recorded by the counter H1, at which are added the 200 milliseconds corresponding to the duration load of the first storage means is greater at 300 milliseconds. So the microcontroller compares the time elapsed between unlocking the grenade by removal of the pin and movement of the lever to a reference duration, here equal to 300 milliseconds. Yes this elapsed time is less than 300 milliseconds, the microcontroller stops, in step 120, the setting work of the pomegranate initiation process. If the elapsed time is greater than 300 milliseconds, the microcontroller triggers timing means in view of the delayed feeding of the initiation device 52. In particular a new H2 counter is triggered in step 122.

In parallel with the implementation of the means of time delay, and as shown in the figure 4, the continued movement of the lever 16 leads to the progressive extraction of the jumper 22 which thus opens switch 88, making the short circuit stop initiator 52 terminals. After removing the jumper 22, the primary pyrotechnic module 6 is free to move. It then fits, as shown on FIG. 5, in the secondary pyrotechnic module 10 under the effect of finger 24 loaded by the spring 28. The well 42 thus enters chamber 44, leading to the alignment of the additional pyrotechnic modules.

In step 124, the microcontroller checks whether the duration corresponding to the value of the counter H2 is greater than a first predetermined period of time T ₁ . The period T ₁ is for example equal to half of the delay T desired for the explosion of the grenade. If this is not the case, the counter H2 is incremented in step 126. The incrementation continues until the duration represented by the counter H2 is greater than the period T ₁ . When this condition is verified, the switch 84 is inverted, in step 128, under the control of the microcontroller, so that the storage means 46 transfer part of their electrical energy to the storage means 48. The latter are thus progressively charged, at a rate imposed by the load resistor 86. The value of the latter is calculated so that the storage means 48 are charged with a charge corresponding to the energy necessary for actuation of the initiation device 52 to the end of a time period T ₂ corresponding to the remaining half of the delay T.

In step 130, the microcontroller checks whether the duration measured by the H2 counter is greater than the delay T. If this is not the case, it increments, at step 132, the H2 counter. The incrementation continues until the duration measured by the H2 counter, be greater at period T. The microcontroller then commands, at step 134, reversing the switch 84, so that the electrical initiation device 52 is put under voltage at the output of the storage means 48. Sound feeding has the effect of initiating, in step 136, the charge 54, which by thermal effect, initiates the microdetonator 56. The latter, by radial effect, causes the detonation of relay 62. Thus, the main charge of the grenade is initiated, so that the grenade explodes. When the grenade exploded, the different components of the igniter plug are found destroyed.

It is understood that with such an igniter plug, the delay means of the delay device, managed by the microcontroller, are only triggered if the duration elapsed between unlocking the pin and lever movement is greater than a reference duration which is, in the example described, equal to 300 milliseconds. So if the elapsed time is less than 300 milliseconds, that is, the lever was not maintained sufficiently, the initiation of the grenade is impossible. Under these conditions, such an igniter plug prohibits the explosion of the grenade if the pin of security was removed without the lever being held. This prevents accidental release of the plug igniter by simply removing the pin.

In addition, the presence of two storage means successive, arranged in cascade, and of which the second is only charged after a specified time also allows avoid any untimely triggering of the device initiation 52.

In addition, before the extraction of the pin 18, no electrical charge is stored in the plug igniter, or even any mechanical energy likely to be transformed into electrical energy, which avoids the risks of accidental starting of the device electronic delay.

In the embodiment described here, the pomegranate igniter plug has a microcontroller. This can be replaced by a specially designed ASIC designed for the implementation of successive stages of the grenade.

Likewise, the threshold detection means of voltage 82 may not take the form of a device independent and be trained by a simple connection first storage means 46 at the delivery terminal to zero of the microcontroller.

In addition, the switching means 84 can take the form of a switch, as shown in Figure 6. However, they can also be consisting of two controlled electronic switches by the microcontroller 50 and arranged in series between the load resistance 86 and switch 88.

The output of the second storage means 48 is then connected between the two switches mounted in series.

The microcontroller controls these two switches so that they are in different states and in particular that the second storage means 48 are first connected to the first storage means 46 then to the electric initiation device 52.

Claims (11)

1. A delay action fuse for a pyrotechnical device, in particular a manually or mechanically launched grenade, the fuse comprising a body (4) containing a main charge (66) and a trigger lever (16) co-operating with a delay device (8) suitable for initiating the charge (66) after a predetermined delay has elapsed after the lever (16) has moved, the fuse further comprising a locking member (18) preventing the lever (16) from moving, the delay device (8) comprising timer means suitable for providing delayed initiation of the charge and electronic trigger means for triggering the timer means, the fuse being characterized in that the trigger means include comparator means for comparing the duration that elapses between the locking member (18) being unlocked and the lever (16) moving with a reference duration, so as to trigger said timer means only if said elapsed duration is greater than said reference duration.
2. A fuse according to claim 1, characterized in that the comparator means comprise means for estimating said elapsed duration.
3. A fuse according to claim 2, characterized in that it includes a normally open electrical switch (90) which is closed by the lever (16) moving, and in that closure of said switch (90) causes said estimator means to stop.
4. A fuse according to claim 2 or claim 3, characterized in that it includes an electricity generator (14) actuated by said locking member (18) while it is being unlocked, and in that said electricity generator (14) powers said delay device (8).
5. A fuse according to claim 4, characterized in that it includes ejector means (28) for ejecting said electricity generator (14) under the control of the lever (16) moving.
6. A fuse according to claim 5, characterized in that said ejector means comprise a spring (28) initially held in the loaded state by said lever (16) and having its ends bearing respectively against said electricity generator (14) and said body (4) of the fuse.
7. A fuse according to any one of claims 4 to 6, characterized in that said electronic trigger means include first electrical energy storage means (46) connected to said electricity generator (14) and having said comparator means connected thereto so as to be electrically powered thereby.
8. A fuse according to claims 2 and 7 taken together, characterized in that said means for estimating said elapsed duration comprise a clock powered by said first storage means (46) after they have been charged, and in that the estimate of said elapsed duration is given by the sum of the estimated duration required for charging said first storage means (46) plus the duration measured by the clock between the end of said first storage means (80) being charged and the lever (16) moving.
9. A fuse according to claim 7 or claim 8, characterized in that the delay device (8) includes second storage means (48) selectively connected via switch means (48) under the control of said timer means either to the first storage means (46) or to an electrical device (52) for initiating the charge.
10. A fuse according to claim 9, characterized in that a load resistor (86) is interposed between the first and second storage means (46, 48) to determine the time taken to charge the second storage means.
11. A fuse according to claim 9 or claim 10, characterized in that said timer means are adapted firstly to cause the second storage means (48) to be connected to the first storage means (46) in order to be charged with electrical energy after a first time period (T₁), and then to cause the second storage means (48) to be connected to the charge initiator device (52) after a second time period (T).

Images