MXPA97002543A - High pressure resistant initiator, integrated with metallic oxide varistor for protection against download electrostat - Google Patents

Abstract

The present invention relates to a resistive initiator for a passenger restraint system in a motor vehicle, which includes a protective cover having an upper chamber and a lower chamber. The connector pins connect the initiator with an electrical connector of the vehicle. A metal oxide varistor placed in the protective cover provides electrostatic discharge and IRE / IFR protection for the initiator. A glass-to-metal watertight mounting plate is formed in the protective cover and includes an integrated circuit to burn pyrotechnic material placed in a cargo vessel attached to the protective cover

Description

INITIATOR RESISTANT TO L? HIGH PRESSURE, INTEGRATED WITH METALLIC OXIDE VARISTOR FOR PROTECTION AGAINST ELECTROSTATIC DISCHARGE This application relates to the co-pending application US Series No. 08 / 456,257 entitled "Circle of connector plugs of the inflator for initiator with integrated metal oxide varistor for protection against electrostatic discharge"; and US Series No. 08 / 574,426 entitled "Inflator initiator with protection against electrostatic discharge with zener diode", both assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the invention: The present invention relates to an electro-explosive device or initiator for an electrical passenger restraint system in a motor vehicle, and more particularly, to an initiator that includes a metal oxide varistor for the motor vehicle. electrostatic protection of the electroexplosive device. 2. Description of the Related Art: In the prior art it is well known to use an inflatable containment system for the occupant, to protect the passenger of a car. These containment systems consist of a reaction vessel that houses a gas generator or inflator, and an air bag in a deflated state. In response to a collision, the gas generator is operated to inflate and extend the airbag to protect the vehicle occupant. Inflators for passive containment systems for automobiles and other devices require a pyrotechnic initiator or electroexplosive device (DEE) to operate the inflator. To activate the gas generator or inflator, an electro-explosive device initiates the combustion of the material contained in the gas generator. The inflator initiator is connected to a crash detector that is located next to the initiator or at a remote location in the vehicle. During operation, the shock detector sends an electrical signal to the initiator. The initiator ignites in the combustion chamber and breaks a container containing a flammable material, commonly a mixture of boron nitrate and potassium. The initiator consists of a pair of electrical terminals placed in parallel joined at one end by a cursor thread (or Wheatstone bridge) embedded within the pyrotechnic material. The pyrotechnic material burns with a very hot flame and burns the solid fuel granules that generate gas contained in the combustion chamber. The granules release nitrogen gas, which travels through the diffusing chamber and enters the protective air bag to protect the occupants of the vehicle. A common feature of electroexplosive devices (DEE) is the susceptibility of the cursor wire to the undesirable energy coming from the sources of the external environment that could cause an inadvertent display or a failure in the initiator. The undesirable energy may be, but is not limited to, electrostatic discharge (DES), electromagnetic radiation interference (IRÉ) or radio frequency interference (IFR). The protection against this radiation energy, in the present, will be mentioned as IRE / IFR protection. To overcome the risk of IRE / IFR, a solution of the prior art includes the use of a ferrite bead placed directly into an initiator chamber. The ferrite bead absorbs the extraneous energy, preventing the energy from reaching the cursor thread. See the Patent No. 4,306,499, to Holmes, which is assigned to the assignee of the present invention. A problem with the Holmes electroexplosive device is that the incorporation of the IRE / IFR protection directly within the limits of the DEE increases both the size of the device as well as the costs and time of manufacture. In addition, the gas generator manufacturer is limited to a specific design of the DEE. Another solution is a universal initiator charging connector that contains a ferrite bead which surrounds the electrical terminal of the DEE. See US Patent No. 5, 200,574 and 5,241,910 to Cunningham et al., Assigned to the assignee of the present invention. Cunningham et al. discloses a universal connector comprising the IRE / IFR protection, which is permanently secured within the gas generator. From the electrical point of view, the ferrite bead is essentially an inductor that prevents instantaneous change in the flow of the current. v Another problem with known inflator units is that the initiator (DEE) is crimped in the base of the inflator. This crimping process often damages the initiator if it is improperly developed. U.S. Patent No. 4,103,619 discloses an electroexplosive device in which the terminals of the device are sealed with glass and contain a strong branch to protect the bridge circuit from extraneous energy. A disadvantage of the resistant shunt is that a percentage of the energy supplied to the initiator during the deployment sequence is derived to ground, thus requiring substantially more total power than would be required if the resistant shunt were not present. U.S. Patent No. 4,422,381 discloses an ignition device incorporating a ferrite jacket (IRE / IFR) and a static discharge disk (DDE). For DES protection, the static discharge disk depends on the "disruptive discharge" method and its utility is limited to a specific type of electrostatic discharge voltage, that is, generally greater than 25 O'OO volts of direct current. The present invention uses the metal oxide varistor which can adapt the protection of the DES to a wider voltage range by varying the varistor dimension. The present invention is designed to ground any extraneous voltage in excess of 500 volts of direct current. Figures 1-6 describe the different initiators of the prior art. Figure 1 depicts a low-cost ignition device manufactured by ICI Explosives of Tamaqua, Pennsylvania, incorporating a spark-generating ring for DES protection. Figure 2 illustrates a mixed initiator, also manufactured by ICI Explosives, which includes two terminals and a bypass wire, which in essence acts as a co-axial initiator. Figure 3 illustrates another low cost initiator, manufactured by Quantic Industries of San Carlos, California. The prior art initiator of Figure 4 is a spike-type initiator utilizing an off-center coaxial mounting plate design, such as the initiator manufactured by Special Devices Inc. of Newhall, California. In Figure 5 the prior art discloses a conductive wire initiator having a co-axial centered design, also manufactured by ICI Explosives of Tamaqua, Pennsylvania. Figure 6 is an advanced impeller initiator having a coaxial centered design, manufactured by OEA Inc. of Englewood, Colorada. A disadvantage of all the prior art initiators of Figures 1-6 is the need for total electrical isolation. Recently, the use of a metal oxide varistor (VOM) to absorb electrostatic energy in an electroexplosive device has been explored. See, U.S. Patent No. 4,103,274, 4,041,436 and 3,821, 686. Metal oxide varistors are commonly used in surge suppression devices, such as computers. However, the prior art has not explored the use of a VOM in an electroexplosive device for use in the gas generators of an airbag.

SUMMARY OF THE INVENTION The high pressure resistant initiator of the present invention serves as an electrical connection between the electrical wiring unit of the passive containment system in a car and the bridge element in the circuit of the electroexplosive device. An object of the present invention is to provide an initiator (DEE) that includes a glass for a glass-to-metal hermetic mounting plate that allows the use of an integrated circuit which may be a semiconductor bridge (PSC), a circuit bridge printed (PCI), the deposition of a thick film / thin film of a pyrotechnic mixture, or a conventional thermal bridge. Another object of the present invention is to provide an initiator (DEE) that incorporates a metal oxide varistor for the electrostatic protection of the initiator. The integrated metal oxide varistor (VOM) is excellent for protecting an integrated circuit initiator from electrostatic discharge. The metal oxide varistor is an improvement to the disruptive discharge method of the prior art, this is due to the better characteristics of heat dissipation by the placement of the metal oxide varistors between the connector pins and the circle. The VOM can be designed to comply with the specific voltage protection of the consumer by varying the thickness and length of the VOM. Another advantage of the present invention is the possibility of using a laser welding manufacturing technique, bonding with adhesive or a combination of both, between the different components in order to provide a hermetic seal without damaging the initiator. The load carrying unit and closure disk also uses a laser / adhesive welding joint to provide a tight and pressure-resistant seal. In addition, the stainless steel protective cover, laser welding / adhesive bonding and the glass-to-metal sealed mounting plate provide protection against high pressure. Still another object of the present invention is to provide a high pressure resistant initiator having an integrated circuit bridge element with a deposited explosive layer and a channel for locating the integrated circuit bridge between the pins of the glass sealed mounting plate to metal. In order to achieve these and other objects of the invention, a high pressure resistant initiator of an electrical restraint system for the passenger of a motor vehicle is provided which includes a cover having an upper chamber and a lower chamber. The means connecting the initiator to an electrical connector of a vehicle, the lower chamber is capable of receiving the electrical connector. The means of protection for electrostatic discharge are placed on the cover to protect the initiator from electrostatic discharge. The means for housing a pyrotechnic material are attached to the cover. Also attached to the cover is an airtight glass-to-metal mounting plate. Other features and advantages of the present invention will become apparent from the following description of the invention, which refers to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS v Figures 1-6 are cuts of the initiators known in the prior art. Figure 7 is a section of a first embodiment of the high pressure resistant initiator of the present invention. Figure 8 is an amplified cut-off of a first molded insert of the high pressure resistant initiator of the present invention. Figure 9 is an amplified section of a second molded insert according to the present invention.

Figure 10 is a section of a second embodiment of the initiator of the present invention. Figure 11 is a sectional view of another embodiment of the initiator of the present invention. Figure 12 is a section of the initiator of Figure 1, taken along line A-A. Figure 13 is a section of a fourth embodiment of the initiator of the present invention. Figure 14 is a section of a fifth embodiment of the initiator of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 7, a first embodiment of the high pressure resistant initiator of the present invention is shown. The initiator is located inside a gas inflator (not shown). The initiator includes a protective cover 10. The protective cover 10 is made of machined stainless steel or stamped or injection molded stainless steel. It should be appreciated that. the protective cover can be made with other materials without departing from the scope of the invention.

The protective cover 10 is divided into two chambers, the lower chamber 12 and the upper chamber 14. The lower chamber 12 facilitates the electrical interface with the electrical wiring unit for the passive containment system of a car 19 (Figure 10). The lower chamber 12 receives a first pre-molded plug 20. As shown in Figures 7 and 8, the plug 20 includes a cavity 18, the holes 22 and an interface of the electrical connector 16 which is aligned in engagement with the orientation feature. of the coupling connector of the electrical wiring unit 19. The upper chamber 14 receives a second pre-molded plug 24. As shown in figures 7 and 9, the plug 24 includes a cavity 28 and the holes 26 which support and they align with the connector pins 36 and a metal oxide varistor 30, which will be described hereinafter. Both pins 20 and 24 can be made of a plastic material. The connector pins 36 extend through the protective cover 10 and provide the electrical connection between the electrical wiring unit 19 and the integrated circuit initiator 46. Again in relation to FIG. 7, surrounding each of the connector pins 36 is find a metal oxide varistor 30. The metal oxide varistor 30 is tubular in shape and fits over the connector pins. The length and thickness of the metal oxide varistor 30 determines the actual voltage of the disruptive discharge, and, in this way, it allows to meet the specific requirements of the consumer. The metal oxide varistors can be manufactured by die cutting and sintering a mixture of metal oxide powder at a temperature of about 1300 ° C to form a generally hard and brittle ceramic body. It should be appreciated that, the VOM of the present invention can be made from other suitable materials and methods, which will be described herein. When installed, the metal oxide varistors 30 extend into both cavities 28 and 18 of the pins 24 and 20. The lower chamber 12 also includes a metal sleeve of low ohmic resistance 34 which provides the electrical connection between the oxide varistor metallic 30 and the protective cover 10. The sleeve 34 includes the holes 32 through which pass the connector pins 36 and the respective metal oxide varistors 30 that surround them when the initiator is installed. The sleeve 34 is in the middle of the pins 20 and 24 in such a way that the respective holes 26, 32 and 22 are aligned. Attached to the unit of the protective cover is a glass-to-metal airtight mounting plate 40. The glass-to-metal sealing provides a path for the hermetic passage of an electrical conductor from one medium to another. In addition to providing airtightness, the glass acts as an insulator between the pins and between the pins and the protective cover. The glass-to-metal seal of the present invention is manufactured by placing the pins in the protective covers within a graphite plate. The glass mixture is placed inside the desired area and then the artifact is placed on a conveyor belt that takes it through a high temperature oven, which increases the temperature of the glass to its liquid state. When leaving the cold room of the oven, the glass solidifies and adheres to the metal surfaces forming an airtight seal between the dowels and the glass and between the protective cover and the glass. The mounting plate 40 provides a connection plane for the integrated circuit 46. The integrated circuit 46 can be a semiconductor bridge, a printed circuit bridge using a conventional and suitable refractory metal, a bridge for the deposition of a thick film / thin pyrotechnic mixture or a "hot wire" or thermal bridge device for burning the pyrotechnic material 54 contained in a charging container 48 of the initiator. The mounting plate 40 includes the pins 42 which coincide with the connector pins 36. The pins of the mounting plate 42 generally have a diameter in the range of 0.05 centimeters. In order to provide a hermetic connection, the glass-to-metal sealing plate 40 is attached to the protective cover lü by circumferential laser welding or the bonding method with adhesive as indicated in 38 in Figure 7. The processes of Laser welding / adhesive bonding provide an excellent circumferential hermetic seal. As shown in Figure 7, attached to the glass-to-metal hermetic mounting plate 40 is a charging container 48, which contains the pyrotechnic material, and a locking disc unit 44. To provide a hermetic seal Further, the loading container 48 is attached to the mounting plate 40, and the disc 44 is attached to the loading container 48 by the method of laser welding or bonding with adhesive 38. Figure 10 describes a second embodiment of the invention. high pressure resistant initiator of the present invention. The embodiment of the figure is identical to the previous embodiment, with the exception of the solid feed through the pegs 50 which are encapsulated in the hermetic connection of glass to metal 40. As far as possible, in all the modalities of the present invention the same numbers have been used to indicate similar parts. Since the pins 50 do not include plugs, as in the first embodiment, the holes 26 of the plug 24 may be slightly smaller. Next, the installation method of the high-pressure resistant initiator of FIG. 7 will be described. The plug 20 and the sleeve 34 are snapped into the chamber 12 of the protective cover 10. Next, a metal oxide varistor 30 is provided. it is tightened around each of the contact pins 36. Then, in the cavities 26 and 28 of the plug 24 a sub-unit is inserted consisting of the connector pins 36 and the metal oxide varistor 30. This subunit then it is inserted into the cavity 14 of the protective cover 10 until the solid terminals of the connector pins 36 exit from the holes 22 of the pin 20. The pins 42 of the glass-to-metal assembly plate 40, which is attached an integrated circuit 46 is inserted into the plug of the pins 36 and on the mounting plate 40 the loading container 48 is placed. To attach the mounting plate to the protective cover 10 and the loading container 48 to the mounting plate 40 performs the method of circumferential welding or adhesive bonding 38. The mixture of pyrotechnic powder 54 is then loaded into the loading container 48 and the closure disk 44 is attached to the loading container 48 by the method by circumferential welding or adhesive bond 38. The protective cover 10 is then installed in the gas inflator using any suitable means. During the installation of the high pressure resistant initiator of Figure 10, the plug 20 and the sleeve 34 are press fitted into the chamber 12 of the protective cover 10. Next, the plug 20 and the sleeve 34 are adjusted with pressure in the chamber 12 of the protective cover 10. The unit of the glass-to-metal hermetic mounting plate containing the mounting plate 40 and the pins 50 is then inserted into the cavity 26 of the plug 24, and the metal oxide varistor 30 is tightened around each of the contact pins 50, and the metal oxide varistor 30 is inserted into the cavity 28 of the plug 24. This subunit is then inserted into the cavity. 14 of the protective cover 10 until the solid ends of the pins 50 protrude from the holes 22 of the pin 20. The loading container 48 is placed on the mounting plate 40 and the method of welding bonding is carried out. circumferential or adhesive bond for attaching the mounting plate to the protective cover 10 and the loading container 48 to the mounting plate 40. Then the pyrotechnic powder mixture 54 is placed in the loading container 48 and the closure disc 44 it is attached to it by the circumferential welding / adhesive bonding method 38. The protective cover 10 is then installed in a gas inflator using any suitable method. Referring to Figures 11 and 12, a third embodiment of the resistive initiator of the present invention will be described. The protective cover 10 includes a single pre-molded plastic plug 56 snapped into the lower chamber 12. The plug 56 has the shape of a cup and includes an interface feature along its internal surface that matches a connector of a electrical wiring unit (not shown) of the containment system. The upper chamber 14 of the protective cover 10 includes a metal oxide varistor 30 and a glass-to-metal sealing plate 40. The metal oxide varistor 30 can be: a) formed around each of the pins 50 by consolidating a formulation of reconstituted metal oxide powders, followed by a sintering operation; b) an integral cohesive compound of the glass-to-metal watertight mounting plate formed by the mixing of a metal oxide powder with the glass mixture followed by the sintering operation, thus, forming an integral cohesive metal oxide varistor and the hermetically sealed glass to metal; or, c) a piece or preformed insert consolidating metal oxide powders and sintering the piece to form a hardened ceramic material that is punched into position during the manufacturing process. In still another variant, the metal oxide varistor can be located on a packed disk of an integrated circuit chip inside the chamber 14, or the integrated circuit 46 and the varistor can be located on a single integrated circuit disk. In the embodiment of Figures 11 and 12, the glass-to-metal hermetic mounting plate 40 includes a channel 60 which functions as an alignment mechanism for the integrated circuit 46 between the pegs 50. Referring to Figure 6, an explosive composition 62, which acts as the source of primary ignition, is deposited directly on the bridge element of the integrated circuit. Attached to the protective cover 10 is the charge container unit 48 and the closure disk 44 containing the pyrotechnic mixture 54. To provide a hermetic seal, the charge container 48 is attached to the protective cover 10 and the disc 44 it is attached to the container 48 using the circumferential laser welding method or the adhesive bonding method 38.

The embodiment of Figure 13 is identical to the embodiment of Figures 11-12, with the exception of a closing cup 68 which replaces the loading container unit 48 and the closure disc 44 of the above embodiments. The cup 68 is a single unit, the closed bottom cup containing the pyrotechnic mixture 54 is hermetically sealed to the protective cover 10 by the method of circumferential laser welding or adhesive bonding 38. The embodiment of Figure 14 is identical to the embodiment of Figures 11-12, with the exception that the protective cover 10 includes the elongated end walls 8 which serve as the loading container for the pyrotechnic mixture and thus eliminates the need for a separate cargo container 48. Thus, the glass-to-metal hermetic mounting plate 40 is contained within the protective cover 10. A cup-shaped closure disc, similar to the disc 44 of Figure 11, is attached to the side wall 8 of the protective cover 10 by means of the method of circumferential laser welding or adhesive bonding 38. The installation method of the embodiments of Figures 11-14 will now be described. The metal oxide varistor can be formed together with the glass-to-metal seal to produce an integrated cohesive unit including the protective cover 10, the pegs 50, the mounting plate 40 and the metal oxide varistor 30. The oxide varistor The metal can also be a separate component that is inserted into the cavity directly behind the glass mounting plate 40. The pin 56 is snapped into the protective cover 10 until it reaches the base of the cavity. An adhesive compound is deposited between the pegs 50 along the channel 60 to secure the integrated circuit 46 to the glass mounting plate '40. The integrated circuit 46 is then placed between the pegs 50 using the channel 60 as a mechanical mechanism. self alignment To connect the integrated circuit 46 electrically to the pins 50, onductive adhesive, bonding by means of wire or welding is used. In relation to the embodiment of Figure 11, the loading container 48 is then attached to the protective cover 10 and the pyrotechnic mixture 54 is charged to the loading container 48. Then the closure disc 44 is attached to the loading container 48. by the circumferential welding method or adhesive bond 38. Next, in relation to Figure 12, the explosive layer 62 is placed directly on the bridge element of the integrated circuit and allowed to dry. The remaining installation steps are similar to the embodiment of figures 11, 13 and 14. It should be noted that the explosive layer 62 can be used in all the embodiments of the present invention. With the embodiment of Figure 13, the cup 68 is loaded with the pyrotechnic mixture and is bonded to the protective cover 10 using the method of circumferential welding or adhesive bonding 38. In the embodiment of Figure 14, the pyrotechnic mixture 54 is loaded into the cavity and the closure disk 44 is attached to the protective cover 10 using the circumferential welding / adhesive bonding method 38. Although the present invention has been described in relation to the particular embodiments thereof, many other variants and Modifications and other uses will be apparent to those skilled in the art. Therefore, it is preferable that the present invention is not limited to the specific description thereof, but only by the appended claims.

Claims (23)

1. A high pressure resistant initiator of an electrical restraint system for the passenger of a motor vehicle, comprising: a protective cover having an upper chamber and a lower chamber; means for connecting the initiator to an electrical connector of the vehicle, wherein the lower chamber is capable of receiving the electrical connector; means for protecting from electrostatic discharge placed in the protective cover to protect the initiator from electrostatic discharge; the means for housing the pyrotechnic material, attached to the protective cover; a glass-to-metal sealed mounting plate formed in the protective cover, the glass-to-metal hermetic mounting plate includes the integrated circuit means for burning the pyrotechnic material; and the means for hermetically sealing the glass-to-metal hermetic mounting plate with the protective cover.

2. The initiator resistant to high pressure, of. according to claim no. 1, characterized in that the means of protection against electrostatic discharge contain a metal oxide varistor.

3. The initiator resistant to high pressure, in accordance with claim no. 2, characterized in that the metal oxide varistor contains a cohesive compound integrated with the glass-to-metal hermetic mounting plate, formed by mixing the metal oxide powder with the glass mixture followed by a sintering operation.

4. The initiator resistant to high pressure, according to claim no. 2, characterized in that the connection means comprises a pair of elongated pins that extend through the upper and lower chambers of the protective cover.

5. The initiator resistant to high pressure, in accordance with claim no. 4, characterized in that the metal oxide varistor is formed around each of the pins by consolidating a formulation of reconstituted metal oxide powders followed by a sintering operation.

6. The initiator resistant to high pressure, in accordance with claim no. 4, characterized in that the metal oxide varistor contains a preformed insert which is formed by consolidating the metal oxide powders and sintering the insert to form a hardened ceramic material which is punched into the protective cover, the pair of pins extends through of the insert.

7. The initiator resistant to high pressure, in accordance with claim no. 6, is characterized in that the metal oxide varistor is tubular in shape and is tightened on each of the pins.

8. The initiator resistant to high pressure, in accordance with claim no. 4, further containing at least one pre-molded plug disposed within the lower chamber of the protective cover, the pre-molded plug includes means for interconnecting with the electrical connector.

9. The initiator resistant to high pressure, in accordance with claim no. 4, characterized in that the first pre-molded plug is placed inside the upper chamber of the protective cover and the second pre-molded plug is placed in the lower chamber of the protective cover, both the first and second pins include the means for accommodating the varistor of metal oxide and the spikes.

10. The high pressure resistant initiator according to claim no. 9, furthermore, it contains a metallic sleeve of low ohmic resistance placed in the protective cover between the first and second pins to provide an electrical connection between the metal oxide varistor and the protective cover.

11. The initiator resistant to high pressure, in accordance with claim no. 4, characterized in that the glass-to-metal hermetic mounting plate includes the pins of the mounting plate to coincide with the pair of pins.

12. The initiator resistant to high pressure, in accordance with claim no. 11, characterized in that each of the pins of the mounting plate 'has a diameter of approximately 0.05 centimeters.

13. The initiator resistant to high pressure, in accordance with claim no. 1, characterized in that the means for housing the pyrotechnic material consists of a unit of the charging container and the closing disc attached to the protective cover, the glass-to-metal hermetic mounting plate is hermetically sealed inside the charging container.

14. The initiator resistant to high pressure, in accordance with claim no. 1, characterized in that the means for housing the pyrotechnic material consists of a sealing cup sealed with the protective cover.

15. The initiator resistant to high pressure, in accordance with claim no. 1, characterized in that the protective cover includes an elongate terminal wall, the terminal wall and the closure disc comprise the means for housing the pyrotechnic material, the closure disk is hermetically sealed to the end wall.

16. The initiator resistant to high pressure, in accordance with claim no. 4, characterized in that the glass-to-mind hermetic mounting plate includes a channel extending along the diameter of the glass-to-metal watertight mounting plate to align the integrated circuit medium between the pins which pass through of the Chanel.

17. The initiator resistant to high pressure, in accordance with claim no. 16, characterized in that the integrated circuit means includes a printed circuit board placed in the channel between the pair of elongated pins and a layer of explosive composition deposited on the printed circuit board.

18. The initiator resistant to high pressure, in accordance with claim no. 1, characterized in that the hermetic sealing means consists of circumferential laser welding.

19. The initiator resistant to high pressure, according to claim no. 1, characterized in that the sealing means consists of an adhesive.

20. A method for installing a high pressure resistant initiator that includes the integral protection against electrostatic discharge of an electric passenger restraint system, comprising the steps of: providing a protective cover having an upper chamber and a camera lower; Insert a means to connect the initiator to an electrical connector through the lower and upper chambers; the formation of a means of protection against electrostatic discharge to protect the initiator from electrostatic discharge; insert the means of protection against electrostatic discharge in the protection box, the means of protection against electrostatic discharge is in communication with the connection means; the formation of a glass-to-metal hermetic mounting plate within the protective cover, the glass-to-metal hermetic mounting plate includes the integrated circuit means for burning a pyrotechnic material; and the hermetic sealing of a means for housing the pyrotechnic material and the protective cover.

21. The method, according to claim no. 20, characterized in that the connecting means consists of a pair of elongated pins extending along the upper and lower chambers of the protective cover and the forming step of the metal oxide varistor comprises the consolidation of a powder formulation of reconstituted metal oxide around each of the pins and the sintering of the reconstituted metal oxide powders.

22. The method, according to claim no. 20, characterized in that the forming step of the metal oxide varistor comprises the consolidation of a reconstituted metal oxide powder formulation into a preformed insert and the sintering of the insert to form a hardened ceramic material which is press fit within the protective cover, on the spikes.

23. The method, according to claim no. 20, characterized in that the connecting means consists of a pair of elongated pins extending along the upper and lower chambers of the protective cover and the forming step of the glass-to-metal hermetic mounting plate comprises the adaptation of the protective cover and the pins in a graphite plate, the insertion of a glass mixture into the protective cover, the heating of the graphite plate to a high temperature which brings the glass mixture to a liquid state and cooling of the liquid glass mixture until the glass solidifies and adheres to the protective cover and the pegs to form a tight seal between the pegs and the solidified glass and between the protective cover and the solidified glass.