EP1139060B1 - Pyrotechnic initiator comprising an electrical or electronic componant and/or a connector - Google Patents

Abstract

The detonator (1) contains a pyrotechnic charge inside a container (2). The container is attached to an insulated plug body (16). The charge is ignited by an electric current fed to a resistance element via connector pins (7). When connected, a free male socket is inserted in the connection cavity (40). When the connection is broken, by removal of the socket, a simple mechanism shorts out the pins (7) to prevent inadvertent ignition.

Description

The field of the invention is that of the initiators pyrotechnics, i.e. components for transmit a pyrotechnic effect in a chain pyrotechnic. Such a pyrotechnic initiator is described in the document US5621183 (basis of claim 1).

We know from patents EP600791 and EP711400 initiators whose housing is made at least partly in plastic material.

These initiators are for example intended to come activate a pyromechanism or initiate a composition gas generator in a security system for the automobile.

These initiator boxes are generally made by injection or overmolding.

The initiators are connected by connections electric to a centralized electronic control circuit vehicle safety.

The connections are generally formed by lugs deformable electrical devices or by connectors.

The installation of the terminals is long and tedious. he this results in an increase in the cost of carrying out the connectivity. In addition, the known connectors are bulky axially and difficult to integrate into a vehicle.

The pods also present problems from the point of view the reliability of the connection and therefore the security of the vehicle.

In addition, we generally seek today to place component level an electrical or electronic component for example a shunt means which makes it possible to avoid, in the absence connector, unexpected pyrotechnic initiations, by example by electrostatic discharge.

Such a shunt is a bulky intermediate component which comes between the pyrotechnic component and the connector and further complicates the connection often requiring the installation of adapters.

It is the object of the invention to propose an initiator pyrotechnic to overcome such drawbacks.

Thus the initiator according to the invention allows with a reduced axial dimensions to simplify and make reliable the connection of the initiator to vehicle circuits.

In addition, according to a particular embodiment, the initiator according to the invention authorizes the establishment of a low-cost shunt circuit, for example at the time of manufacture of the initiator, and without resulting increase in axial dimensions or a complication of making connections.

Thus the subject of the invention is a pyrotechnic initiator according to claim 1.

The cavity may in particular carry a shunt component ensuring, in the absence of a connector, a short circuit between the initiator pins.

The base may include means ensuring a axial immobilization of the shunt component and / or the connector in the cavity.

According to a particular embodiment, the cavity is cylindrical and has at least one notch intended for receive a projection integral with the shunt component and allowing its angular positioning.

The shunt component may consist of a strip flexible conductor secured to the base, lamella ensuring a short circuit between the pins in the absence of a connector.

The base can advantageously be molded onto the conductive coverslip.

The upper shell and the base can be returned secured to each other by ultrasonic welding.

• la figure 1 représente en coupe longitudinale un premier mode de réalisation d'un initiateur selon l'invention, coupe réalisée suivant le plan dont la trace AA est repérée à la figure 2,
• la figure 2 est une vue de la précédente suivant la direction F repérée à la figure 1,
• la figure 3 représente en coupe longitudinale un deuxième mode de réalisation d'un initiateur selon l'invention, coupe réalisée suivant le plan dont la trace BB est repérée à la figure 4,
• la figure 4 est une vue de la précédente suivant la direction G repérée à la figure 3,
• la figure 5 représente en coupe longitudinale ce deuxième mode de réalisation équipé d'un composant shunt,
• la figure 6 est une vue en perspective avant montage de l'initiateur selon l'invention, d'un composant shunt et d'un connecteur,
• les figures 7a, 7b sont deux vues du composant shunt seul, la figure 7a étant une vue latérale du composant et la figure 7b une vue frontale suivant la direction H représentée figure 7a.
• la figure 7c est une vue en perspective de la lamelle contact du composant shunt,
• la figure 8a est une vue en coupe longitudinale d'un troisième mode de réalisation d'un initiateur selon l'invention, coupe réalisée suivant le plan brisé dont la trace CC est repérée à la figure 8b,
• la figure 8b est une vue de la précédente suivant la direction Z repérée à la figure 8a.

The invention will be better understood on reading the description which follows of specific examples of embodiment, description made with reference to the appended drawings and in which:

• FIG. 1 shows in longitudinal section a first embodiment of an initiator according to the invention, section made along the plane, the trace AA of which is identified in FIG. 2,
• FIG. 2 is a view of the previous one in the direction F identified in FIG. 1,
• FIG. 3 shows in longitudinal section a second embodiment of an initiator according to the invention, a section made along the plane, the trace BB of which is identified in FIG. 4,
• FIG. 4 is a view of the previous one in the direction G identified in FIG. 3,
• FIG. 5 shows in longitudinal section this second embodiment equipped with a shunt component,
• FIG. 6 is a perspective view before mounting of the initiator according to the invention, of a shunt component and of a connector,
• Figures 7a, 7b are two views of the shunt component alone, Figure 7a being a side view of the component and Figure 7b a front view in the direction H shown in Figure 7a.
• FIG. 7c is a perspective view of the contact strip of the shunt component,
• FIG. 8a is a view in longitudinal section of a third embodiment of an initiator according to the invention, section made along the broken plane, the trace CC of which is identified in FIG. 8b,
• Figure 8b is a view of the previous in the direction Z identified in Figure 8a.

Referring to Figure 1, an initiator pyrotechnic 1 according to a first embodiment of the invention comprises a pyrotechnic composition (not shown) arranged inside a housing 2 composed a substantially cylindrical case 4, made for example in metal and extended by two pins 7a, 7b. Such a case is not here described in detail, it is known in particular by FR2720493.

This case 2 is arranged inside an envelope 3 formed by the joining of two parts: a base 16 and an upper shell 17.

The shell and the base are made by injection a plastic material, for example of the polyamide type or polycarbonate. They are made integral of one another for example by ultrasonic welding.

The base 16 has a bearing face 18 on which is made a circular groove 19 and it is crossed by two holes 20, 21 connected by a notch 22.

The holes 20 and 21 are intended to let the pins 7a and 7b of the housing 2. The notch 22 allows receive the bends of pins 7a and 7b.

The upper shell 17 has a bearing face which has a circular toothing 27 intended to cooperate with the groove 19 of base 16.

The upper shell 17 defines a cylindrical volume internal 28 which is intended to receive the housing 2. This volume therefore has the same diameter as the outer diameter of the housing 2 and it has a height equal to that of the case.

The thickness e of the upper shell is of the order of 0.5 mm. This shell is thin enough to be able be broken by the initiation of the pyrotechnic composition contained in case 2.

The base 16 also includes a cavity 40 to the interior of which extend the pins 7a, 7b. This cavity with a parallelepiped profile and it is intended for receive a connector (not shown).

The base also includes an elastic spout 41 which deforms when a connector is inserted and which has an abutment surface 42 making it possible to prohibit the connector outlet out of cavity 40.

This spout is formed in one piece with the base 16.

The initiator according to the invention is assembled as follows.

After manufacturing the case 2, we position it on the base 16 by bringing the pins 7a and 7b into holes 20 and 21. The bottom 6 of the housing 2 is therefore in support on the support face 18 of the base. We then style the housing 2 with the upper shell 17. It is secured finally the two shells by ultrasonic welding.

Ultrasonic welding is carried out in a known manner by applying a sonotrode from a welding machine to a conical profile 31 of the upper shell 17.

The vibrations of the sonotrode cause the welding of surfaces in contact. The circular toothing 27 penetrates the mounting in the groove 19 which allows to concentrate the stresses caused by ultrasonic vibrations during welding. We thus locate a warm-up at the level of groove / toothing contact which allows welding.

It is of course possible to make the two shells by another means, for example by gluing.

The tightness of the initiator compared to the outside is ensured by the laser welding of the housing 2 (not shown). No special precautions from the point of view sealing is not to be expected when mounting the envelope 3. This simplifies manufacturing.

The tightness of the initiator with respect to the pyromechanism and relative to the gases generated during operation is provided by the support of the bottom 6 on the support face 18, the pressure which also has the effect of firmly applying the bottom and the case 4 on the support face which makes slightly penetrate the case 2 into the lower shell 16 and increases the seal.

To further improve gas tightness we will give advantageously a tight fit between the surface external cylindrical of the case 4 and its housing in the upper shell 17 as well as a slight adjustment tight pins 7a 7b in holes 20 and 21.

We can also provide in addition, on the face support 18, one or more circular grooves (not represented) which will play the role of relaxation baffles for gas or which can each receive an O-ring.

The initiator according to the invention is therefore perfectly waterproof and can also receive reliably and waterproof a standard connector with rectangular section. The connector being made integral with the initiator thanks to the spout 41 which will cooperate with a connector notch.

We can alternatively provide a notch made in the cavity and cooperating with a spout carried by the connector.

We can also have at the bottom of the cavity 40 a electrical or electronic component such as a capacitor or a shunt.

Depending on the geometries of the connectors used, there it is of course possible to vary the shapes and dimensions of the cavity 40 receiving the connector.

Thus thanks to the invention the internal part of the initiator formed by the housing 2 may be the same whatever the external geometry of the complete component and that of the connector which will have to adapt to it.

It will suffice to modify the shape of the base 16 and in particular from its cavity 40 to obtain an initiator usable in another application

We can also modify the external shape of the base 16 and the upper shell 17 to obtain an initiator whose external geometry will be adapted to a type of given gas generator.

We can therefore mass produce the part essential and a priori the most expensive of the initiator, that is to say the case 2 which contains the composition pyrotechnics and its means of initiation.

We will then personalize the initiator by arranging this housing in an envelope having external dimensions appropriate to the needs of a client and having a base bearing a cavity adapted to the geometry of the connector and / or desired components.

Figure 3 thus shows a second embodiment an initiator according to the invention.

This mode differs from the previous one mainly by the geometry of the cavity 40. The latter is here cylindrical and it is delimited at its opening by a circular bead 43. The cavity 40 is intended to receive a cylindrical component, for example a connector or a shunt component as will be described later. The bead 43 has a stop surface 44. A groove clearance circular 45 is arranged between the bead 43 and the internal cylindrical surface of the cavity 40.

The base 16 finally comprises two notches 46a, 46b cutting the bead 43 and extending from a lower face 47 of the base 16 to beyond the groove 45.

These notches are intended to receive projections complementary to a connector or component shunt and allow angular positioning of the component or connector relative to the base 16.

FIG. 5 shows this same initiator comprising inside the cavity 40 a shunt component 48.

The latter is more particularly visible on Figures 7a and 7b.

Such a component is well known to those skilled in the art and is therefore not the subject of the present invention.

Its description is given here in order to facilitate the understanding of the invention.

A known shunt component is formed by an insulating body 49 having a cylindrical external profile of the same diameter as the cavity 40 of the initiator 1, carrying two projections 50a and 50b intended to cooperate with the notches 46a and 46b of the base 16.

The bottom 51 of the body carries two holes 52a, 52b intended to receive pins 7a and 7b from the initiator.

The body 49 has a middle notch 53 which is delimited by the bottom 51 and two flat surfaces 54a and 54b.

The flat surface 54a has in the middle part a semi-cylindrical rib 55 while the flat surface 54b has a rectangular groove 56.

The rib and the groove are intended to cooperate with additional profiles carried by a connector so as to ensure that it is put in place with an orientation correct compared to component shunt 48. The surfaces planes 54a and 54b will furthermore guide the connector.

The body 49 of the component 48 carries a notch 57 rectangular which is parallel to the surface 54a and which receives a conductive strip 58 (for example brass).

This strip is shown alone in FIG. 7c. It has two tabs 59a, 59b connected together by a bar 60. It is formed from a single piece of brass stamped and folded.

The tabs are folded so that when the strip 58 is placed in its notch 57, the ends of the tabs 59a, 59b are located respectively opposite the holes 52a, 52b.

So when the shunt component 48 is introduced into the cavity 40 of initiator 1, pins 7a and 7b of this last push the tabs 59a and 59b. Because of their elasticity, the tabs 59a and 59b come into contact with the pins and thus provide an electrical connection between pins 7a and 7b. Such an arrangement allows protect the initiator from electrostatic discharges.

The tongue 59b is shown in Figure 7a in its contact position with an initiator pin. The tongue 59a is shown in its rest position, shunt component 48 outside the initiator.

When a connector is inserted in the notch 53 of the shunt component 48, it spreads the tabs 59a and 59b from the pins which are inserted inside at the same time of the connector. The position of a tab thus spread is represented by the dotted lines 61 in FIG. 7a.

The protective short circuit is therefore eliminated as soon as the introduction of the connector. It is however re-established as soon as removing the connector. The level of security obtained with screw electrostatic discharge is optimal.

Figure 6 shows in perspective the shunt component 48 (conductive strip not shown) positioned in front the initiator 1 according to the invention and before its implementation in the cavity 40 thereof.

The dimensions of the cavity 40 have been defined so to be able to receive a standard shunt 48 component from trade.

This component is introduced into the cavity 40. It positions in abutment at the bottom of it. It is adjusted by tightly in the cavity so as to ensure its maintenance axial.

Thanks to the invention it is therefore possible to equip a initiator from its manufacture with a shunt component standard which is then an integral part of it.

The axial size of the assembly is reduced to the maximum. Safety is ensured with extremely mounting simplified.

A standard connector 62 can then be connected to initiator 1. It will delete the shunt as it was previously described. It will be made in solidarity with the initiator by the cooperation of deformable tabs (integral with the connector and not shown) with the abutment surface 44 delimiting the circular clearance groove 45.

We will of course define the geometry of the cavity function of the geometric characteristics of the shunt component desired as well as the connector. The invention therefore makes it possible to keep the same geometry for the initiator box 2 and that whatever the application envisaged.

Figures 8a and 8b show an initiator following a third embodiment of the invention.

This mode differs from the previous mode in that the component shunt is not constituted by a separate part mounted in the cavity 40 but only by a conductive strip 58 secured to the base 16.

The base 16 and the body 49 of the shunt component which were shown in Figure 5 as separate parts will then constitute a single piece.

Thus the cavity 40 of the base has a profile substantially rectangular (see Figure 8b) which is intended to receive a connector and which plays the same role as the middle notch of the component described above in reference to Figures 7a, 7b.

The cavity 40 carries on one of its planar faces a rib semi-cylindrical 55 and on the other flat surface a groove rectangular 56.

The rib and the groove are intended to cooperate with additional profiles carried by a connector so as to ensure that it is put in place with an orientation correct with respect to the pins. The flat surfaces of the cavity 40 also provide guidance of the connector.

The conductive strip 58 is identical to that shown in Figure 7c.

It is slid into a notch 57 arranged in the base 16. Alternatively, the base can be overmolded made of plastic on the strip 58 including the bar 60 will then be embedded in the base material.

The strip 58 again comprises two tongues 59a, 59b interconnected by a bar 60. It provides a short circuit between pins 7a and 7b when the initiator does not not found connected to a connector.

Claims (7)

1. A pyrotechnic igniter (1) comprising at least one pyrotechnic composition placed inside a casing (2) composed of a substantially cylindrical case (4) extended by at least two pins (7a, 7b), the casing (2) being arranged inside an envelope delimited by the joining of a base (16) and a shell (17), the envelope having an external profile allowing it to be attached to a gas generator or pyromechanism, said base (16) incorporating a cavity (40) inside which the pins extend, such cavity being of adapted dimensions and intended to accommodate an electric or electronic component and/or a connector, igniter characterised in that said base (16) has holes (20) each accommodating one of the pins (7a, 7b).
2. A pyrotechnic igniter according to Claim 1, wherein the cavity (40) has a shunt component (48), which, in the absence of a connector, ensures a short circuit between the pins (7a, 7b).
3. A pyrotechnic igniter according to Claim 1 or 2, wherein the base (16) incorporates means ensuring the axial immobilisation of the shunt component and/or the connector in the cavity.
4. A pyrotechnic igniter according to any one of the above Claims, wherein the cavity (40) is cylindrical and has at least one notch (46a, 46b) intended to receive a protrusion (50a, 50b) integral with the shunt component (48) and allowing it to be positioned angularly.
5. A pyrotechnic igniter according to Claim 2, wherein the shunt component (48) is constituted by a flexible conductive strip integral with the base, such strip ensuring a short circuit between the pins (7a, 7b) in the absence of a connector.
6. A pyrotechnic igniter according to Claim 2, wherein the base is duplicate moulded over the conductive strip.
7. A pyrotechnic igniter according to any one of the above Claims, wherein the upper shell (17) and the base (16) are made integral with one another by ultrasonic sealing.

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