EP1524490B1 - Safety device for a sensitive part, in particular for a pyrotechnic igniter - Google Patents

Description

The present invention relates to the field of safety devices for sensitive organs, in particular for pyrotechnically applied igniters.

The igniters generally comprise a mass of thermally flammable material associated with a power supply capable of causing the Joule effect to heat up the material.

In modern applications, the use of igniters leads to a dilemma: on the one hand, for reasons of consumption, it is desired that the firing energy be as low as possible, but on the other hand, for reasons of safety it is desired that the igniters are as robust as possible in the face of electrical or electromagnetic aggression, whether parasitic or controlled. A device is known to US 4,478,147 .

The safety devices heretofore proposed do not give complete satisfaction.

The present invention aims to improve the situation.

This object is achieved in the context of the present invention by means of a device comprising an active member and a safety device which comprises in combination, on the one hand, an electrical logic means and, on the other hand, a mechanical logic means controlled by the electrical logic means, which electrical logic means and mechanical logic means may each be switched between a locking position in which they prohibit the implementation of the active member and a release position in which they allow the setting. implementation of said active member.

• la figure 1 représente une vue schématique, sous forme de blocs fonctionnels, de l'architecture générale d'un système conforme à la présente invention,
• la figure 2 représente une vue plus détaillée d'un système conforme à la présente invention dans le cadre d'une application à un inflammateur pyrotechnique,
• la figure 3 schématise un mode particulier et non limitatif de réalisation des moyens de logique mécanique, et
• les figures 4 et 5 représentent deux variantes alternatives et non limitatives de moyens interrupteurs associés à un filament d'inflammateur.

Other features, objects and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings, given by way of non-limiting examples and in which:

• the figure 1 represents a schematic view, in the form of functional blocks, of the general architecture of a system according to the present invention,
• the figure 2 represents a more detailed view of a system according to the present invention in the context of an application to a pyrotechnic igniter,
• the figure 3 schematizes a particular and nonlimiting embodiment of the mechanical logic means, and
• the Figures 4 and 5 represent two alternative and non-limiting variants of switch means associated with an igniter filament.

We have schematised on the figure 1 appended, a system according to the present invention comprising in combination an active member 100, electrical logic means 200 and mechanical logic means 300.

The active member 100 can be the subject of many embodiments. It is preferably a pyrotechnic igniter comprising a mass of thermally flammable material associated with a filament adapted to be selectively connected to a power supply.

The electrical logic means 200 and the mechanical logic means 300 will be specified thereafter. It will be recalled here that, as previously indicated, the mechanical logic means 300 are driven by the electrical logic means 200. Furthermore, the electrical logic means 200 and the mechanical logic means 300 are each adapted to be switched between a locking position. in which they prohibit the use of the active member 100 and a release position in which they allow the implementation of said active member 100.

Thus, in the context of the present invention, it is necessary that each of the two means 100 and 200 is switched to the release position to allow the implementation of the active member 100.

The mechanical logic means 300 are preferably formed of latches or drawers capable of displacement by translation or rotation under the effect of associated motor means controlled by the electrical logic means 200, for example in the form of electric coils or any other equivalent means. Preferably, several means with mechanical locking logic are thus provided. These can be interactive, that is to say cooperate with each other. Furthermore, preferably, there are provided mechanical locking means responding to opposite logic, that is to say on the one hand, means to be activated and therefore moved to allow the implementation of the organ active 100 and secondly, means that on the contrary should not be activated and therefore should not be moved to allow the implementation of the active organ.

The electrical logic means 200 preferably comprise means for entering a digital code and means for comparing a code entered with a predefined code to allow switching of the mechanical logic means in case of coincidence between the code entered and the predefined code.

Preferably, several electrical logic means 200 are provided, that is to say the need to enter several successive sequences of digital codes.

Furthermore, preferably, in the context of the present invention, the electrical logic means are programmed to require a precise sequencing and timing between the different numeric codes successively entered to allow the switching of the mechanical logic means 300.

We will now specify a particular application of the present invention to the securing of electric igniters with regard to the figure 2 attached.

On this figure 2 a filament capable of being connected to a power supply 102 is shown schematically at 110, and at 120 a mass of flammable material placed in contact with or near the filament 110.

We also find on the figure 2 annexed, diagrammatically illustrated, the means 200 with electrical logic and the means 300 with mechanical logic.

Three security elements are associated with the igniter 100 according to the embodiment schematized on the figure 2 . It is 1) an electrical switch 400, 2) an electrical shunt 410 and 3) a thermal mass 420.

Each of these three elements 400, 410, 420 is associated with a respective control member 402, 412, 422. Each of the control members 402, 412, 422 is driven by the electrical logic means 200 and the mechanical logic means 300. in other words, each of the control members 402, 412 and 422 can be activated to switch the element 400, 410, 420 respectively associated only if previously the electrical logic means and the mechanical logic means 200 and 300 above are switched from their locked position to their release position.

The electrical switch 400 is provided in series between the power supply 102 and the filament 110. In a manner known per se, at rest, the switch 400 is in the open position. The power supply 102 is not connected to the filament 110.

To ensure the implementation of the active member 100, that is to say the power supply of the filament 110 and the heating of the mass 120, the switch 400 must be switched to the closed position by the organ 402.

The shunt 410 is formed of an electrical switch placed in parallel with the filament 110, closest to it. In the rest position, the shunt 410 is in the closed position. It therefore bypasses any electrical or electromagnetic parasite capable of being conveyed towards the filament 110.

To authorize the implementation of the active member 100, the shunt 410 must be previously switched to the open position by the control member 412.

The thermal mass 420 may be typically formed of a tongue, for example metal. At rest, the thermal mass 420 is placed in proximity to the filament 110. It is designed to dissipate the calories emitted by the filament 110 in case of feeding untimely of it. The thermal mass 420 may however be moved to a position remote from the filament 110. In the latter position, the calories emitted by the filament 110, by the Joule effect, when it is fed by the means 102, are then transmitted to the mass 120 for to inflam it. The displacement of the thermal mass 420 between its rest position in contact with the filament 110 and its position remote from the latter, is controlled by the member 422.

We illustrated on the figure 3 a particular and nonlimiting variant embodiment of the mechanical logic means 300. This figure shows the filament 110 of the igniter and the associated thermal mass 420 controlled by its control member 422.

Of course, in a variant, such a mechanical locking means 300 may be associated with the switch 400 and / or the shunt 410.

The mechanical logic means 300 illustrated on the figure 3 comprises a control member 310 and five locks 320, 330, 332, 340, 342.

The latch 320 is a mechanical latch with negative logic, that is to say that as understood when examining the figure 3 it must not be moved relative to its rest position shown in this figure to allow the displacement of the tongue 420 away from the filament 110. Indeed, if the lock 320 is moved relative to this rest position, approximation of the tongue 420, it is likely to enter a groove 421 formed in the tongue 420 to then prohibit its movement.

The two locks 330, 340 are on the contrary positive logic locks. In the rest position, as shown on the figure 3 they are engaged in respective grooves 423, 424 of the tongue 420 and prohibit its movement. The locks 330, 340 must be moved outside the grooves 423, 424 to subsequently allow the movement of the tongue 420.

The lock 330 is associated with the secondary lock 332. In the rest position, the latter is engaged in a groove 331 of the lock 330 and forbidden his movement. The lock 332 must be moved beforehand away from the main lock 330 to allow the withdrawal thereof.

The main latch 340 is associated with it with a secondary latch 342 of negative logic. Again, the secondary latch 342 must not be moved to allow the movement of the main latch 340, as is understood from the examination of the latch. figure 3 . In the opposite case, the secondary lock 342 engages in a groove 341 of the lock 340 and prevents the movement of the latter.

• le verrou 320 doit rester en position de repos,
• le verrou secondaire 332 doit être rétracté,
• puis le verrou principal 330 doit être rétracté,
• le verrou secondaire 342 doit rester en position de repos, et
• le verrou principal 340 doit être rétracté.

In the end, the logic of the particular non-restrictive means represented on the figure 3 is the following, to allow the displacement of the tongue 420:

• the latch 320 must remain in the rest position,
• the secondary lock 332 must be retracted,
• then the main lock 330 must be retracted,
• the secondary lock 342 must remain in the rest position, and
• the main lock 340 must be retracted.

Of course, as indicated above, the number and the logic of the mechanical means 300 represented on the figure 3 , are not limiting.

We have shown on Figures 4 and 5 two variants of electrical means forming switch and shunt.

According to the realization given on the figure 4 two switches 404, 406 are provided which can be switched between a rest position as illustrated in FIG. figure 4 and a working position. In the rest position, the switches 404 and 406 form in combination a shunt in parallel with the filament 110. In contrast, in the working position, the switches 404 and 406 provide the connection between the power supply 102 and the filament 110.

Finally, we have shown on the figure 5 , a single switch 400 that can be switched between a rest position illustrated on the figure 5 in which the switch 400 forms a shunt in parallel with the filament 110 and a working position in which the switch 400 provides a connection between the power supply 102 and the filament 110.

Naturally, the present invention is not limited to the particular embodiments which have just been described, but extends to any variant within its spirit.

Preferably, in the context of the present invention, all the means ensuring the mechanical displacements, either at the level of the mechanical logic means 300, or at the level of the switch 400, at the level of the shunt 410 or displacement of the thermal tongue 420 are formed MEMS type control means according to the Anglosaxon expression. In other words, in the context of the present invention, these mechanical displacement means are formed of micro-actuators machined on a semiconductor substrate, preferably based on silicon.

MEMS (Micro Electro Mechanical Systems) technology is well known to those skilled in the art. It will not be described in detail later.

1. [1] " A quantitative analysis of Scratch Drive Actuation for integrated S/Y motion system", P. Langlet et al. IEEE Transducers 1997, p 773-776 .
2. [2] " Scratch Drive Actuator with Mechanical Links for Self-Assembly of Three-Dimensional MEMS", T. Akiyama et al., Journal of Microelectromechanical Systems, Vol. 6, n° 1, 1997 .
3. [3] " Design and Characterization of High-Torque/Low-Speed Silicon Based Electrostatic Micromotors Using Stator/Rotor Contact Interactions" P. Minotti et al., Jpn. J. Appl. Phys. Vol. 37, 1998, p 359-361 .
4. [4] LEE A P et al. : "Polysilicon angular microvibromotors", Journal of Microelectromechanical Systems, US, IEEE INC. New York, vol. 1, n° 2, 1 juin 1992 (1992-06-01 ).
5. [5] DANEMAN M J et al. : "Linear microvibromotor for positioning optical components", Journal of Microelectromechanical Systems, US, IEEE INC. New York, vol. 5, n° 3, 1 septembre 1996 (1996-09-01 ).
6. [6] PAI M et al. : "Low voltage Electrothermal Vibromotor for silicon optical bench applications", Sensors and Actuators A., CH, Elsevier Sequoia S.A., Lausanne, vol. 83, n° 1-3, mai 2000 (2000-05 ).
7. [7] FLEISCHER M et al. : "Novel Ultrasonic Motors with Mono and Bimodal Drives", Sensors and Actuators A, CH, Elsevier Sequoia S.A., Lausanne, vol. A21, n° 1/03, 1 février 1990 (1990-02-01 ).
8. [8] FLEISCHER M et al. : "Ultrasonic Piezomotor with Longitudinally Oscillating amplitude transforming resonator", IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, US, IEEE INC, New York, vol. 36, n° 6, 1 novembre 1989 (1989-11-01 ).

As non-limiting examples, reference may be made to the following documents:

1. [1] " A quantitative analysis of Scratch Drive Actuation for integrated S / Y motion system, P. Langlet et al., IEEE Transducers 1997, p 773-776 .
2. [2] " Scratch Drive Actuator with Mechanical Links for Self-Assembly of Three-Dimensional MEMS, "T. Akiyama et al., Journal of Microelectromechanical Systems, Vol 6, No. 1, 1997 .
3. [3] " Design and Characterization of High-Torque / Low-Speed Silicon Based Electrostatic Micromotors Using Stator / Rotor Contact Interactions "P. Minotti et al., Jpn J. Appl Phys., Vol 37, 1998, p 359-361 .
4. [4] LEE AP et al. : "Polysilicon angular microvibromotors", Journal of Microelectromechanical Systems, US, IEEE INC. New York, vol. 1, No. 2, June 1, 1992 (1992-06-01 ).
5. [5] DANEMAN MJ et al. Linear microvibromotor for positioning optical components, Journal of Microelectromechanical Systems, US, IEEE INC. New York, vol. 5, No. 3, September 1, 1996 (1996-09-01 ).
6. [6] PAI M et al. : "Low Voltage Electrothermal Vibromotor for silicon optical bench applications", Sensors and Actuators A., CH, Elsevier Sequoia SA, Lausanne, vol. 83, No. 1-3, May 2000 (2000-05 ).
7. [7] FLEISCHER M et al. : "Novel Ultrasonic Motors with Mono and Bimodal Drives", Sensors and Actuators A, CH, Elsevier Sequoia SA, Lausanne, vol. A21, No. 1/03, February 1, 1990 (1990-02-01) ).
8. [8] FLEISCHER M et al. : "Ultrasonic Piezomotor with Longitudinally Oscillating Amplitude Transforming Resonator", IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, US, IEEE INC, New York, vol. 36, No. 6, November 1, 1989 (1989-11-01 ).

According to another advantageous characteristic of the present invention, the set of electrical logic means and the filament 110 are made on a substrate common to the MEMS elements providing the aforementioned mechanical displacement.

Those skilled in the art will understand that the present invention allows the production of an active member, in particular a pyrotechnic igniter which requires little energy for its implementation, but has a strong resistance to external aggressions, particularly with regard to parasitic currents, electromagnetic attacks or electrostatic discharges.

Indeed, the system according to the present invention requires two essential actions for the implementation of the active member, namely on the one hand, the unlocking of the safety device, both at the level of the electrical logic means 200 and mechanical logic means 300 and secondly, the initiation of the igniter 110 or the implementation of an active member in case of equivalent means.

The MEMS means, in the context of the present invention, can respond to any known physical principle (electrostatic, magnetostatic, electromagnetic, induction, electrostriction, magnetostriction, etc.).

Claims (14)

1. A safety device comprising an active member (100) and a safety device (200, 300) which includes as a combination, electrical logic means (200) on the one hand, and mechanical logic means (300) driven by the electrical logic means (200) on the other hand, characterized in that said electrical logic means (200) and mechanical logic means (300) may each be switched between a locking position in which they each prevent application of the active member (100) and a release position in which they jointly allow application of said active member (100).
2. The device according to claim 1, characterized by the fact that the mechanical logic means (300) comprises several locks (320, 330, 331, 340, 342).
3. The device according to any of claims 1 or 2, characterized by the fact that the mechanical logic means (300) comprises interactive elements (330, 332; 340, 342), i.e. elements cooperating with each other.
4. The device according to any of claims 1 to 3, characterized by the fact that the mechanical logic means (300) comprises opposite logic means, i.e. lock elements which have to be displaced and lock elements which do not have to be displaced for allowing application of the active member (300).
5. The device according to any of claims 1 to 4, characterized by the fact that the electrical logic means (200) comprises means for entering a digital code and means for comparing an entered code with a predefined code.
6. The device according to any of claims 1 to 5, characterized by the fact that the electrical logic means is adapted in order to utilize several successive digital codes.
7. The device according to any of claims 1 to 6, characterized by the fact that the electrical logic means (200) is adapted in order to control sequencing or timing between several successive digital codes.
8. The device according to any of claims 1 to 7, characterized by the fact that it comprises a safety element formed by an electrical switch in series between an electric power supply (102) and an active member (100).
9. The device according to any of claims 1 to 8, characterized by the fact that it comprises a safety element formed by a shunt (410) placed in parallel with the active member (100).
10. The device according to any of claims 1 to 9, characterized by the fact that it comprises a safety element formed by a thermal mass (420) capable of being switched between a rest position in contact with the active member (100) and a working position away from this active member (100).
11. The device according to any of claims 1 to 10, characterized by the fact that each of the safety elements is controlled both by the electric logic means (200) and by the mechanical logic means (300).
12. The device according to any of claims 1 to 11, characterized by the fact that it comprises an electrical switch (400, 404, 406) capable of being switched between a shunt position and a power supply position.
13. The device according to any of claims 1 to 12, characterized by the fact that it comprises at least one mechanical displacement member machined in a semiconducting substrate (MEMS).
14. The device according to any of claims 1 to 13, characterized by the fact that the active member (100) is formed by a pyrotechnical igniter comprising an electrical filament (110) in contact with a thermally inflammable material mass (120).

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