FR2807155A1 - PYROTECHNIC INITIATOR WHICH CAN BE EQUIPPED WITH AN ELECTRIC OR ELECTRONIC COMPONENT 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

: '1 2807155

  The field of the invention is that of pyrotechnic initiators, that is to say components making it possible to transmit a pyrotechnic effect in a pyrotechnic chain. 5 We know from patents EP600791 and EP711400 initiators whose housing is made at least in part made of plastic. These initiators are for example intended to actuate a pyromechanism or else initiate a composition

  gas generator in a security system for the automobile.

  These initiator boxes are generally produced by injection or overmolding.

  The initiators are connected by connections

  electric to a centralized electronic circuit for controlling vehicle safety.

  The connections are generally formed by lugs

  deformable electrical devices or by connectors.

  The installation of the terminals is long and tedious. This results in an increase in the cost of making the connectors. In addition, the known connectors are bulky axially and difficult to integrate into a vehicle. The terminals also present problems from the point of view of the reliability of the connection and therefore of the security of the

vehicle.

  In addition, it is generally sought today to place an electrical or electronic component at the component level.

  for example a shunt means which makes it possible to avoid, in the absence of a connector, unexpected pyrotechnic initiations, for example by electrostatic discharge.

  Such a shunt is a bulky intermediate component which is interposed between the pyrotechnic component and the

  connector and further complicates the connection by often requiring the installation of adapters. 35 It is the object of the invention to provide a pyrotechnic initiator which overcomes such drawbacks.

  Thus the initiator according to the invention makes it possible, with a reduced axial size, to simplify and make more reliable the connection of the initiator to the circuits of the vehicle. In addition, according to a particular embodiment, the initiator according to the invention allows the installation of a shunt circuit at low cost, for example at the time of manufacture of the initiator, and without this resulting an increase in the axial dimensions or a complication in the making of the connections. 10 The invention therefore relates to a pyrotechnic initiator comprising at least one pyrotechnic composition placed inside a box composed of a case. substantially cylindrical extended by at least two pins, initiator characterized in that the housing is integral15 with a base carrying holes receiving the pins and also comprising a cavity inside which extend the pins, cavity intended to receive a electrical or electronic component and / or a connector. The cavity may in particular carry a shunt component

  ensuring, in the absence of a connector, a short circuit between the pins of the initiator.

  The base may include means ensuring axial immobilization of the shunt component and / or of the connector in the cavity. 25 According to a particular embodiment, the cavity is cylindrical and has at least one notch intended to 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, strip ensuring a short circuit between the pins in the absence of a connector.

  The base can advantageously be molded onto the conductive strip.

  The housing is advantageously arranged inside

  an envelope formed by the attachment of the base and an upper shell.

  The envelope may have an external profile allowing its attachment to a gas generator or a pyromechanism.

  The upper shell and the base can be made integral with one another by ultrasonic welding.

  The invention will be better understood on reading the description which follows of particular examples of

  embodiment, description made with reference to the accompanying drawings and in which: - Figure 1 shows in longitudinal section a

  first embodiment of an initiator according to the invention, section made along the plane of which the trace AA is identified in FIG. 2, - FIG. 2 is a view of the previous one in the direction F identified in FIG. 1, - FIG. 3 represents in longitudinal section a second embodiment of an initiator according to the invention, 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 located in Figure 3, - Figure 5 shows in longitudinal section this second embodiment equipped with a shunt component, - Figure 6 is a perspective view before mounting of the initiator according to the invention, a shunt component and connector, - Figures 7a, 7b are two views of the shunt component alone, Figure 7a is a side view of the component and Figure 7b a front view in the direction H shown in Figure 7a.30 - Figure 7c is a view in perspective 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 taken 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, a pyrotechnic initiator 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 of metal and extended by two pins 7a, 7b. Such a case is not described here in detail, it is known in particular from patent FR2720493.

  This housing 2 is disposed 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 produced by injection of a plastic material, for example polyamide or polycarbonate type. They are made integral with one another, for example by ultrasonic welding. The base 16 has a bearing face 18 on which a circular groove 19 is made and it is crossed by

  two holes 20, 21 connected by a notch 22.

  The holes 20 and 21 are intended to allow the pins 7a and 7b of the housing 2 to pass. The notch 22 makes it possible to receive the curvatures of the 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 the base 16.

  The upper shell 17 defines an internal cylindrical volume 28 which is intended to receive the housing 2. This volume

  therefore has the same diameter as the outer diameter of the housing 230 and has a height equal to that of the housing.

  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 the housing 2.

  The base 16 also includes a cavity 40 inside which the pins 7a, 7b extend. This cavity has a parallelepiped profile and it is intended to receive a connector (not shown). The base also includes an elastic spout 41 which deforms during the introduction of a connector and which has an abutment surface 42 making it possible to prevent the outlet of the connector from the cavity 40.

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

  The mounting of the initiator according to the invention is carried out as follows.

  After manufacture of the housing 2, the latter is positioned on the base 16 by making the pins 7a and 7b penetrate into

  the holes 20 and 21. The bottom 6 of the housing 2 is therefore supported on the support face 18 of the base. The housing 2 is then capped with the upper shell 17. Finally, the two shells are joined together by ultrasonic welding.

  Ultrasonic welding is carried out in a known manner by applying a sonotrode of a welding device to a conical profile 31 of the upper shell 17. The vibrations of the sonotrode cause the contacting surfaces to be welded. The circular toothing 27 enters the mounting in the groove 19 which allows to concentrate the

  stresses caused by ultrasonic vibrations during welding. There is thus localized heating at the level of the groove / toothing contact which allows the soldering. It is of course possible to make the two shells integral by another means, for example by gluing.

  The seal of the initiator relative to the outside is ensured by the laser welding of the housing 2 (not

  shown). No particular precaution from the point of view of sealing is to be provided during the mounting of the casing 3. This simplifies manufacturing.

  The tightness of the initiator with respect to the pyromechanism and relative to the gases generated during operation is ensured by the support of the bottom 6 on the support face 18, the pressure also having the effect of firmly applying the bottom and the case 4 on the bearing face which slightly penetrates the housing 2 in the lower shell

16 and increases the seal.

  To further improve the gas tightness, a tight fit will advantageously be given between the external cylindrical surface of the case 4 and its housing in the upper shell 17 as well as a slightly tight fit of the pins 7a 7b in the holes 20 and 21. One can also provide in addition, on the support face 18, one or more circular grooves (not

  shown) which will play the role of gas expansion baffles or which may each receive an O-ring.

  The initiator according to the invention is therefore perfectly waterproof and can also receive in a reliable and waterproof manner a standard connector with rectangular section. The connector

  being made integral with the initiator thanks to the spout 41 which will cooperate with a notch in the connector.

  One could alternatively provide a notch made in the cavity and cooperating with a spout carried by the connector. 20 One can also have at the bottom of the cavity 40 an electrical or electronic component such as a capacitor or a shunt. Depending on the geometry of the connectors used, it is of course possible to vary the shapes and the

  dimensions of the cavity 40 receiving the connector.

  Thus, thanks to the invention, the internal part of the initiator formed by the housing 2 can 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 of its cavity 40 to obtain an initiator usable in another application. It is also possible to modify the external shape of the base 16 and of the upper shell 17 to obtain an initiator.

  whose external geometry will be adapted to a given type of gas generator.

7 2807155

  We can therefore mass produce the essential and a priori most expensive part of the initiator, i.e. the box 2 which contains the pyrotechnic composition as well as its initiation means. arranging this case in an envelope having external dimensions

  appropriate to the needs of a client and having a base carrying a cavity adapted to the geometry of the connector and / or of the desired components. FIG. 3 thus shows a second embodiment of 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 well

  a shunt component as will be described later. The bead 43 has an abutment surface 44. A circular relief groove 45 is arranged between the bead 20 43 and the internal cylindrical surface of the cavity 40.

  The base 16 finally comprises two notches 46a, 46b intersecting 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 complementary projections integral d '' a connector or a shunt component and allow angular positioning of the component

  or connector with respect 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 in FIGS. 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 5 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 central notch 53 which is delimited by the bottom 51 and two flat surfaces 54a and 54b.

  The planar surface 54a has in the middle part a semi-cylindrical rib 55 while the planar surface 54b carries a rectangular groove 56. The rib and the groove are intended to cooperate with complementary profiles carried by a connector so as to ensure an installation of this one with a correct orientation with respect to the shunt component 48. The flat surfaces 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 made of 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 stamped and folded brass25.

  The tongues are folded so that, when the strip 58 is placed in its notch 57, the ends of the tongues 59a, 59b are located respectively opposite the holes 52a, 52b.30 Thus when the shunt component 48 is introduced into the cavity 40 of the initiator 1, the pins 7a and 7b of the latter repel the tongues 59a and 59b. Due to their elasticity, the tongues 59a and 59b come into contact with the pins and thus provide an electrical connection between the pins 7a and 7b. Such an arrangement allows

: '9 2807155

  protect the initiator from electro-

  static. The tongue 59b is shown in FIG. 7a in its position of contact with a pin of the initiator. The tongue 59a is shown in its rest position, shunt component 48 outside the initiator. When a connector is. introduced into the notch 53 of the shunt component 48, it separates the tabs 59a and 59b from the

  pins which are introduced at the same time inside10 of the connector. The position of a tab thus separated is represented by the dotted lines 61 in FIG. 7a.

  The protective short circuit is therefore eliminated as soon as the connector is introduced. It is however re-established as soon as

  removing the connector. The level of safety obtained with respect to electrostatic discharges is optimal.

  Figure 6 shows in perspective the shunt component 48 (conductive strip not shown) positioned in front of the initiator 1 according to the invention and before it is placed in the cavity 40 thereof.20 The dimensions of the cavity 40 have been defined in a way

  to be able to receive a standard 48 shunt component.

  This component is introduced into the cavity 40. It is positioned in abutment at the bottom thereof. It is adjusted by

  tightly in the cavity so as to ensure its axial retention.

  Thanks to the invention it is therefore possible to equip an initiator from its manufacture with a standard shunt component which then forms an integral part of it. -30 The axial size of the assembly is reduced to the maximum. Safety is ensured with an extremely simplified assembly. A standard connector 62 can then be connected to the initiator 1. It will erase the shunt as previously described. It will be made integral with the initiator by the cooperation of deformable tongues (integral with the connector and not shown) with the abutment surface 44 delimiting the circular release groove 45. The geometry of the cavity will of course be defined as a function of the geometric characteristics the desired shunt component as well as the connector. The invention therefore makes it possible to keep the same geometry for the box 2 of the initiator.

  and that whatever the application envisaged. Figures 8a and 8b show an initiator according to a third embodiment of the invention.

  This mode differs from the previous mode in that the shunt component is not constituted by a separate piece 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 component shunt who were

  shown in Figure 5 as separate parts will then constitute a single piece.

  Thus the cavity 40 of the base has a substantially rectangular profile (see FIG. 8b) which is intended to

  receiving a connector and which plays the same role as the middle notch of the component described above with reference to FIGS. 7a, 7b.

  The cavity 40 carries on one of its planar faces a semi-cylindrical rib 55 and on the other planar surface a rectangular groove 56.25 The rib and the groove are intended to cooperate with complementary profiles carried by a connector so as to

  ensure that it is positioned correctly with respect to the pins. The flat surfaces of the cavity 40 also guide the connector. 30 - The conductive strip 58 is identical to that shown in FIG. 7c.

  It is slid into a notch 57 fitted in the base 16. As a variant, the base can be molded

  in plastic material on the strip 58, the bar 6035 of which will then be embedded in the material of the base.

  11i 2807155 The strip 58 again has two tabs 59a, 59b connected together by a bar 60. It provides a short circuit between the pins 7a and 7b when the initiator does not

not found connected to a connector.

Claims (6)

  1- Pyrotechnic initiator (1) comprising at least one pyrotechnic composition disposed inside a housing (2) composed of a substantially cylindrical case (4) extended by at least two pins (7a, 7b), initiator characterized in that the housing (2) is integral with a base (16) carrying holes (20,21) receiving the pins (7a, 7b) and also comprising a cavity (40) inside which extend the pins, cavity intended to receive a   electrical or electronic component and / or a connector.   2- pyrotechnic initiator according to claim 1, characterized in that the cavity (40) carries a shunt component   (48) ensuring, in the absence of a connector, a short circuit between the pins (7a, 7b) of the initiator.   3- pyrotechnic initiator according to one of claims i or 2, characterized in that the base (16) comprises   means ensuring axial immobilization of the shunt component and / or of the connector in the cavity. 4- Pyrotechnic initiator according to one of the claims   2 to 3, characterized in that the cavity (40) is cylindrical and has at least one notch (46a, 46b) intended to   receiving a projection (50a, 50b) integral with the shunt component (48) and allowing its angular positioning.   - Pyrotechnic initiator according to claim 2, characterized in that the shunt component is constituted by a flexible conductive strip integral with the base, strip ensuring a short circuit between the pins in the absence of connector. 6- Pyrotechnic initiator according to claim 5,   characterized in that the base is overmolded on the conductive strip.   7- Pyrotechnic initiator according to one of the claims   1 to 6, characterized in that the housing (2) is disposed inside an envelope formed by the joining of   the base (16) and an upper shell (17). 13 2807155   8- Pyrotechnic initiator according to claim 7 characterized in that the envelope has an external profile allowing its attachment to a gas generator or a pyromechanism.   9- Pyrotechnic initiator according to one of claims   7 or 8 characterized in that the upper shell (17) and the base (16) are made integral with one another by ultrasonic welding.