WO1999001715A2

WO1999001715A2 - Electronic delay action fuse assembly for pyrotechnical device

Info

Publication number: WO1999001715A2
Application number: PCT/FR1997/001204
Authority: WO
Inventors: Frédéric TEILHOL; Arnaud Viard; Daniel Casenave
Original assignee: Ruggieri
Priority date: 1997-07-04
Filing date: 1997-07-04
Publication date: 1999-01-14
Also published as: ES2174266T3; EP0991910B1; ATE216487T1; WO1999001715A3; DE69712109D1; DE69712109T2; EP0991910A1; AU3547297A

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

Delayed igniter plug for pyrotechnic device

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

French patent application FR-A-92.00931 describes an igniter plug of the aforementioned type.

Pyrotechnic devices fitted with such an igniter plug are very safe, especially during storage. However, during their use, these devices present accidental risks of tripping, once the locking member, generally formed by a pin, is unlocked. In fact, if the unlocking member is accidentally unlocked and the lever is free to move, the main load can be initiated, then leading to the ignition of the machine.

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

To this end, the subject of the invention is a delay igniter plug for a pyrotechnic device, in particular a grenade with manual or mechanical launching, of the aforementioned type, characterized in that the delay device comprises timing means capable of ensuring delayed initiation of the load and electronic means for triggering the delay means, which trigger means include means for comparing the time elapsed between the unlocking of the locking member and the movement of the lever, at a reference duration, for triggering said delay means only if said elapsed duration is greater than said reference duration. 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 includes a normally open electric 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 includes 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 comprise 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 charging of said first storage means and the time measured by the clock between the end of the charge of said first storage means and the movement of the lever;

the delay device comprises second storage means selectively connected by the intermediary of switching means controlled by said timing means either to the first storage means or to an electronic device for initiating the charge;

- 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 for their charge of electrical energy after a first period of time and to then control the connection of the second storage means to charge initiation device after a second period of time. 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 at successive stages of operation;

- Figure 6 is a diagram of the electronic device of the igniter plug of Figures 1 to 5; and

- Figure 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 pyrotechnic device, is intended for a hand grenade. It has a plastic body 4 charged with glass fibers, but which could alternatively be made of light alloy or any other equivalent material.

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

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

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

The lever 16 covers the upper part of the body 4 on which the open end of the bore 12 opens. It is articulated at a first end on a metal jumper 22, engaged transversely in the body, and which holds on either side other the primary pyrotechnic module 6. The control mechanism also includes a finger 24, articulated around a transverse axis 26. This finger is movable in the plane of FIG. 1 from a position applied against the electric generator 14 to a position where it is in contact with the upper part of the primary pyrotechnic module 6. This finger is loaded by a spring 28 wound around the axis 26. This spring is initially held in the banded state. One end of the spring 28 is supported on the body 4 while its other end bears on one face of the electric generator 14 as well as on the finger 24. The spring 28 constitutes both means for urging the finger 24 and for ejecting the generator 14. The pin 18 comprises two branches 18A, 18B, extending substantially parallel and connected to one another 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 slot 30 formed in the lever 16. This slot has an arcuate shape, and its width is generally equal to the section of the first branch 18A in its narrowed region. One end 30A of the lumen is widened and has dimensions allowing the passage of the branch 18A. The other end of the lumen 30 is aligned with a peripheral groove 31 formed outside the upper part of the primary pyrotechnic module 6, so that the branch 18A of the pin received in the lumen 30 is tangentially engaged 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 a member for actuating the electric generator 14 and comprises, along its length, a section of rack. The latter is adapted to cooperate with a pinion 34 disposed at the end of a shaft 36 of the electric generator.

It is understood that in the position shown in FIG. 1, the pin 18 prohibits the movement of the lever 16, the movement of the primary pyrotechnic module 6 as well as the actuation of the electric generator 14.

The primary pyrotechnic module 6 comprises a metal case 40, made of light alloy, at the base of which is crimped a cup 42 whose length and diameter correspond to those of a coaxial chamber 44 formed in the secondary pyrotechnic module 10. The metal case 40 essentially contains the electronic delay device 8. It is closed at its upper part by a conductive pad 45 forming an electrical contact. The delay device essentially comprises first and second storage means 46, 48, a microcontroller 50 and an electronic initiation device 52 disposed opposite a pyrotechnic initiation composition 54 which is contained in the upper part of the well 42. A microdetonator 56, constituting the primary explosive of the pyrotechnic chain, is placed in the lower part of the well. The base of the bucket 42 is integral with a metal pellet 58 made of material.

The upper end of the case 40 is slidably mounted directly in the bore 12, while the lower end of the latter is received in a case 60, protecting the secondary pyrotechnic module. An axial spacing is provided between the case 40 and the main load, in order to allow the case 40 to slide 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 constituted by an aluminum bucket 64 containing a secondary explosive 66 and a closure capsule 68 which, in combination with the pellet 58 disposed at the base of the bucket of the primary module 6, forms a screen between the microdetonator 56 and the secondary explosive 66 which constitutes the main priming charge.

In FIG. 1, it can be seen that the shape of the axial chamber 44 agrees with that of the cup 42 of the primary module 6 and that the capsule 68 has an opening axial in which, in the storage position, the pad 58 of the primary module 6 is housed.

The electronic delay device will now be described with reference to FIG. 6. As shown in this figure, the electric generator 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 storage means 46. It allows the proper shaping of the voltage and in particular a limitation thereof for the purpose of. charging the storage means 46. The latter are connected via voltage threshold detection means 82 to the microcontroller 50. This microcontroller which in particular comprises clock means 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 switching means are adapted to selectively connect the second storage means 48, also formed by a capacitor, to the first storage means 46 or to the electrical initiation device 52. A charge control resistor 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 with the terminals of the electrical initiation device 52. The switch 88 is formed by the metal jumper 22, short-circuiting the supply wires of the 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 an interrup- tor 90 whose closure translates the movement of the lever 16.

The operation of the microcontroller 50 is controlled by a program managing and controlling the operating stages of the grenade. The flowchart 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 on the one hand for the mechanical aspects, and on the other hand to Figures 6 and 7, for the aspects relating to the operation of the electronic device controlled by the microcontroller 50 .

In order to launch the grenade, the operator grasps its body in one hand, while holding the lever 16, while it grasps the grip ring 20 in the other hand. Using this, it rotates the pin 18 around its second branch 18B, so that the first branch 18A comes to be placed in the enlarged end zone 30A of the light, as shown in FIG. 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 flow diagram of FIG. 7. During the extraction, the rack carried by the second branch 18B drives the pinion 34, thus causing the rotation of the shaft 36 from the electric generator 14. The latter then flows through the rectifier 80, thus charging the first storage means 46 (step 102). When a predetermined charging voltage threshold of the 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 of obtaining the voltage threshold is substantially equal to 200 milliseconds. This duration is linked to the construction of the rectifier 80 and to 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 counter denoted H1, incremented at a rate linked to the clock of the microcontroller.

After extraction of the pin, the lever 16 is held by the hand of the operator. Thus, the counter H1 is representative of the duration of maintenance of the lever 16 from the start of the microcontroller. As long as the microcontroller does not detect the closing of the switch 90, in step 110, it increments, in step 112, the counter H1. In step 114, it checks whether the duration measured by the counter Hl is greater than 30 minutes. If this duration is greater, the microcontroller stops, in step 116, the implementation of the initiation process 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. Thus, as shown in FIG. 3, the lever pivots around its end linked to the jumper 22, releasing the spring 28. The latter, initially compressed, relaxes, ejecting the electric generator 14 in the direction of the arrow FI. Simultaneously, the contact finger 24 is brought into contact with the pad 45 by rotation about the axis 26 in the direction of the arrow F2. This contact causes the closure of the switch 90 which is detected in step 110.

After closing the switch 90 reflecting the movement of the lever 16, the microcontroller implements comparison means which verify, in step 118, whether the duration recorded by the counter Hl is greater than 100 milliseconds. This amounts to checking whether the duration recorded by the counter Hl, to which are added the 200 milliseconds corresponding to the duration load of the first storage means is greater than 300 milliseconds. Thus, the microcontroller compares the time elapsed between unlocking the grenade by removing the pin and the movement of the lever to a reference time, here equal to 300 milliseconds. If this elapsed time is less than 300 milliseconds, the microcontroller stops, at step 120, the implementation of the initiation process of the grenade. If the elapsed time is greater than 300 milliseconds, the microcontroller triggers timing means for the delayed supply of the initiation device 52. In particular a new counter H2 is triggered in step 122.

In parallel with the implementation of the delay means, and as shown in FIG. 4, the continued movement of the lever 16 leads to the progressive extraction of the jumper 22 which thus opens the switch 88, making the short-circuit stop circuit at the terminals of the initiation device 52. After the removal of the jumper 22, the primary pyrotechnic module 6 is free to move. It then fits, as shown in Figure 5, in the secondary pyrotechnic module 10 under the effect of the finger 24 loaded by the spring 28. The bucket 42 thus enters the chamber 44, leading to the alignment of the pyrotechnic modules complementary. 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 _x . 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 _x . When this condition is satisfied, the switch 84 is inverted, in step 128, under the microcontroller control, 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 required for actuating the initiation device 52 at 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 counter H2 is greater than the delay T. If this is not the case, it increments, in step 132, the counter H2. The incrementation continues until the duration measured by the counter H2, is greater than the period T. The microcontroller then commands, in step 134, the reversal of the switch 84, so that the electrical device d initiation 52 is energized at the output of the storage means 48. Its power supply has the effect of initiating, in step 136, the charge 54, which by thermal effect, initiates the microdetonator 56. The latter, by effect radial, causes the detonation of relay 62. Thus, the main charge of the grenade is initiated, so that the grenade explodes. When the grenade explodes, the various constituents of the igniter plug are 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 time elapsed between the unlocking of the pin and the movement of the lever is greater than a reference duration. which is, in the example described, equal to 300 milliseconds. Thus, if the elapsed time is less than 300 milliseconds, that is to say that the lever has not been maintained sufficiently, the initiation of the grenade is impossible. Under these conditions, such an igniter plug is prohibited _. exploding the grenade if the safety pin has been removed without the lever being depressed. This prevents accidental release of the igniter plug by simply removing the pin.

Furthermore, the presence of two successive storage means, arranged in cascade, and the second of which is loaded only after a determined time also makes it possible to avoid any untimely triggering of the initiation device 52.

In addition, before the extraction of the pin 18, no electrical charge is stored in the igniter plug, nor even any mechanical energy capable of being transformed into electrical energy, which avoids the risks of accidental starting of the device. electronic delay.

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

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

In addition, the switching means 84 can take the form of a switch, as shown in FIG. 6. However, they can also be constituted by two electronic switches controlled by the microcontroller 50 and arranged in series between the load resistor 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 and then to the electrical initiation device 52.

Claims

CLAIMS 1. - Delayed igniter plug for pyrotechnic device, in particular shotblasting with manual or mechanical launching, comprising a body (4) in which a main charge (66) is contained and a release lever (16) cooperating with a delay device (8) suitable for initiating the load (66) with a predetermined delay after the movement of the lever (16), the plug further comprising a locking member (18) blocking the movement of the lever (16), characterized in that the delay device (8) comprises timing means capable of ensuring delayed initiation of the load and electronic means for triggering the timing means, which triggering means comprise means for comparing the elapsed time between the unlocking of the locking member (18) and the movement of the lever (16), at a reference duration, to trigger said timing means only if said he elapsed time is greater than said reference time.

2.- igniter plug according to claim 1, characterized in that the comparison means comprise means for estimating said elapsed time.

3.- igniter plug according to claim 2, characterized in that it comprises an electric switch (90) normally open, the closing of which is controlled by the movement of the lever (16), and in that the closing of said switch (90 ) controls the stopping of said estimation means.

4. - igniter plug according to claim 2 or

3, characterized in that it comprises an electric generator (14) actuated by said locking member (18) when it is unlocked, and in that said electric generator (14) supplies said delay device (8).

5.- igniter plug according to claim 4, characterized in that it comprises ejection means (28) of said electric generator (14), controlled by the movement of the lever (16).

6.- igniter plug according to claim 5, characterized in that said ejection means comprise a spring (28) initially maintained in the bandaged state by said lever (16) and the ends of which bear respectively on said electric generator ( 14) and on the body (4) of the igniter plug.

7. - Igniter plug according to any one of claims 4 to 6, characterized in that said electronic triggering means comprise first storage means (46) of electrical energy connected to said electrical generator (14) and to which are connected said comparison means for their supply of electrical energy.

8.- Igniter plug according to claims 2 and 7 taken together, characterized in that said means for estimating said elapsed time include a clock powered by said first storage means (46) after their charge, and in that the estimate of said elapsed time is given by the sum of the estimated time of charge of said first storage means (46) and the time measured by the clock between the end of the charge of said first storage means (80) and the movement lever (16).

9. - Igniter plug according to claim 7 or 8, characterized in that the delay device (8) comprises second storage means (48) selectively connected by means of switching means (84) controlled by said means of time delay either to the first storage means (46), or to an electrical device (52) for initiating the charge.

10.- Igniter plug according to claim 9, characterized in that a charging resistor (86) is interposed between the first and second storage means (46, 48) to determine the charging time of the second storage means.

11.- igniter plug according to claim 9 or 10, characterized in that said timing means are adapted to firstly control the connection of the second storage means (48) to the first storage means (46) for their charge in electrical energy after a first period of time (T _x ) and for then controlling the connection of the second storage means (48) to the device for initiating the charge after a second period of time (T).