Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
  • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
  • B60R21/02—Occupant safety arrangements or fittings, e.g. crash pads
  • B60R21/16—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags
  • B60R21/26—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags characterised by the inflation fluid source or means to control inflation fluid flow
  • B60R21/264—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags characterised by the inflation fluid source or means to control inflation fluid flow using instantaneous generation of gas, e.g. pyrotechnic
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B47/00—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06D—MEANS FOR GENERATING SMOKE OR MIST; GAS-ATTACK COMPOSITIONS; GENERATION OF GAS FOR BLASTING OR PROPULSION (CHEMICAL PART)
  • C06D5/00—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets
  • C06D5/06—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets by reaction of two or more solids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
  • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
  • B60R21/02—Occupant safety arrangements or fittings, e.g. crash pads
  • B60R21/16—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags
  • B60R21/26—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags characterised by the inflation fluid source or means to control inflation fluid flow
  • B60R21/264—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags characterised by the inflation fluid source or means to control inflation fluid flow using instantaneous generation of gas, e.g. pyrotechnic
  • B60R21/2644—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags characterised by the inflation fluid source or means to control inflation fluid flow using instantaneous generation of gas, e.g. pyrotechnic using only solid reacting substances, e.g. pellets, powder
  • B60R21/2646—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags characterised by the inflation fluid source or means to control inflation fluid flow using instantaneous generation of gas, e.g. pyrotechnic using only solid reacting substances, e.g. pellets, powder the reacting substances being supported by the inflatable member walls, or by a flexible support within it

Definitions

• the present invention relates to the field of automobile safety and relates to a pyrotechnic gas generator for inflating a protective cushion of a motor vehicle.
• the invention also relates to a hybrid gas generator device using a pyrotechnic gas generator according to the invention as well as the use of a specific propellant composition in this type of pyrotechnic generator according to the invention.
• Also known from document WO-00/46079 is a device intended to increase the period during which a protective cushion remains inflated inside a motor vehicle.
• This device comprises an igniter and a fuel held in a rigid confinement element provided with gas exhaust orifices.
• This containment element is itself disposed in a time delay tube provided with orifices housed inside the airbag.
• This system is deployed in several stages. However, it uses solid fuel placed in a rigid element which makes it difficult to accommodate in all motor vehicles.
• a device comprising, on the one hand, a main body containing an electro-pyrotechnic igniter and a first pyrotechnic charge, and on the other hand, a flexible tube attached to the main body and containing a second pyrotechnic charge consisting of grains of powder.
• This device has the advantage, compared to the generator cited above, of having a main body of small size associated with a tube which can easily be housed along the roof of the vehicle.
• the manufacturing cost of such a device is relatively high, which is detrimental in a competitive market like that of the automotive industry.
• the use of a pyrotechnic charge in the form of grains of powder in the tube is disadvantageous for several reasons.
• the object of the invention is therefore to propose a pyrotechnic gas generator making it possible to overcome the drawbacks of the prior art.
• a pyrotechnic gas generator used in automotive safety comprising a flexible element, this flexible element containing a pyrotechnic charge, and an electropyrotechnic igniter intended to initiate combustion of the pyrotechnic charge, this generator being characterized in that the pyrotechnic charge is a gelled propellant.
• the use of a propellant gel in the flexible element makes the generator perfectly flexible which allows its easy integration into any part of a vehicle.
• the use of a propellant gel has many advantages, some of which are listed below:
• the combustion temperature of the gelled propellant is less than 2000.
• the gas generator is of a reduced mass, cost and size since the gelled propellant is not sensitive to humidity, no protection system against humidity is required.
• the gelled propellant Since the gelled propellant has a high viscosity in the absence of constraints, the risks of leakage of gelled propellant are greatly reduced.
• the pyrotechnic charge contained in the flexible element is capable of generating a volume of gas sufficient to inflate the protective cushion in a period of time of less than 40 ms.
• this will, for example, rapidly inflate a lateral protective cushion in order to to protect the occupants of a motor vehicle during a first side impact.
• a flexible plastic sheath encloses and confines the pyrotechnic charge in gelled form.
• the flexible element is produced using a flexible tube of thermoplastic material provided with outlet openings regularly distributed over its circumference and over its length.
• the flexible tube is intended to be inserted entirely in the protective cushion to be inflated.
• the orifices are intended to allow the exit of the gases resulting from the combustion of the gelled propellant contained in the flexible tube. They are evenly distributed over the entire tube so that the gases resulting from the combustion of the gelled propellant can escape to all the regions of the protective cushion and thus allow a homogeneous inflation of the protective cushion.
• the flexible plastic sheath encloses and confines the pyrotechnic charge in gelled form as well as a relay charge placed near the pyrotechnic charge.
• the generator can comprise a system for transmitting the ignition of the pyrotechnic charge in gelled form over the entire length of the charge.
• This transmission system will, for example, consist of a cord coated with the gelled composition.
• the pyrotechnic charge in gelled form will burn in concentric parallel layers around the cord.
• the gel propellant will burn in the flexible tube like a cigarette, from one end of the tube to the other end.
• a gas generator as described above inflates a side protective cushion to protect the occupants of a motor vehicle in general during the first side impact. Additional means can be integrated to protect the occupants of a motor vehicle when the vehicle, as a result of this first impact, experiences barrels.
• Another object of the invention is to provide a gas generator device for inflating a protective cushion, for example a lateral one, incorporating a gas generator according to the invention as described above.
• the gas generator device comprises a flexible gas generator as described above and a rigid part attached to the flexible element, this rigid part being hollow and containing a pyrotechnic charge in the form of a solid propellant block that can be initiated in combustion by ignition means.
• the device according to this first embodiment is entirely pyrotechnic and semi-flexible since it comprises a flexible element and a rigid part.
• the solid propellant block inserted in the rigid part is with central channel.
• the ignition means comprise said electropyrotechnic igniter.
• the rigid part is a hollow cylindrical part containing the solid propellant block and comprising a first end in which said electro-pyrotechnic igniter is housed longitudinally and a second end to which is attached the flexible element.
• the electropyrotechnic igniter comprises an ignition head which is inserted into the flared end of a tube, this tube extending into the central channel of the solid propellant block and having its end opposite to its flared end, adjacent to a relay charge, itself adjacent to the pyrotechnic charge in gelled form, this tube sealing the connection between the ignition head of the igniter and the relay charge relative to the outside.
• the gases resulting from the combustion of the ignition composition inserted in the ignition head of the igniter are directed to the relay charge and cannot come into contact with the solid propellant block.
• the means for igniting the solid propellant block comprise a pyrotechnic varnish deposited on the internal wall of the tube. This pyrotechnic varnish makes it possible to transmit the ignition to the relay load and also to heat the tube. Heating the tube will thus cause the initiation of the solid propellant block located around the tube. According to the invention, this tube will preferably be a good conductor of heat.
• the device comprises at least one outlet for the gases from the combustion of the solid propellant block contained in the rigid part, this opening being distinct from the outlet openings formed on the flexible tube of the flexible element.
• the presence of the tube in the rigid part does not allow the gases from the combustion of the solid propellant block to reach the flexible tube of the flexible generator and to exit through the outlet orifices formed on the flexible tube.
• the presence of the tube in the rigid part is necessary to avoid hot gases from the combustion of the solid propellant block to escape through the outlets of the flexible tube from the flexible generator.
• these hot gases are delivered for a significant period of the order of several seconds and would thus be capable of melting the flexible tube if they were caused to escape during this entire period through the outlet orifices of the flexible tube . It is therefore necessary to provide at least one outlet orifice separate from the gas outlet orifices formed on the flexible and specific tube for the outlet of the gases resulting from the combustion of the solid propellant block.
• the solid propellant block is therefore capable of generating a sufficient volume of gas to keep the protective cushion inflated for a long period of the order of ten seconds.
• the protective cushion is kept inflated during this period in order to be able to protect the occupants of a motor vehicle when the vehicle is subjected, for example, to barrels following the first impact.
• the gas generating device is flexible and comprises a body in which is housed said electro-pyrotechnic igniter, this body being provided with first and second ends, said flexible element being attached to the second end of the body.
• a ring supporting said flexible element is fixed in the body at its second end and the first end of the body is open, said pyrotechnic igniter being received in the body at this first end, its ignition head being oriented towards the inside of the body.
• the electro-igniter pyrotechnic may be housed in the body at another location.
• the gas generator device is hybrid, that is to say it comprises a pyrotechnic charge and a gas tank.
• this device is semi-flexible since it comprises a rigid gas tank and a flexible generator as described above, that is to say comprising a pyrotechnic charge in gelled form.
• This device in addition to having a geometry allowing it to be integrated into all kinds of motor vehicles, also has a reduced manufacturing cost compared to one prior art defined by patent application WO 01/34516 because 'it uses a pressurized gas tank instead of a pyrotechnic charge, that the number of components required is low and that the assembly process is simplified.
• the gas generating device comprises a body in which is housed said electro-pyrotechnic igniter, this body being provided with first and second ends, said flexible element being attached to the second end of the body.
• the body consists of a tubular part comprising a side wall pierced with an orifice in which is inserted and fixed the electro-pyrotechnic igniter.
• the pressurized gas tank is attached to the body at its first end.
• the tank is closed using a metal piece that can act as a frangible cover under the action of a relay load.
• said electro-pyrotechnic igniter is capable in operation of causing, on the one hand, the initiation into combustion of the pyrotechnic charge in gelled form contained in said flexible element, and on the other hand , the release of pressurized gas contained in the tank.
• the pressurized gas contained in the tank is released so as to keep the protective cushion inflated during a time period of the order of several seconds.
• a flexible plastic sheath encloses and confines the pyrotechnic charge in gelled form contained in said flexible element.
• the flexible plastic sheath encloses and confines the pyrotechnic charge in gelled form as well as the relay charge in the case where it is the device according to the first mode of realization or a relay charge in the case of the other two modes, this relay charge being adjacent to the pyrotechnic charge in gelled form.
• the gas generator device comprises a second flexible element also comprising a pyrotechnic charge in gelled form which is connected to the free end of the flexible element, called the first flexible element, of the generator flexible such as described above.
• the first flexible element comprises a pyrotechnic charge in gelled form having a higher combustion speed than that of the pyrotechnic charge in gelled form contained in the second flexible element.
• the two flexible elements are connected by a conduit having the shape of a U.
• the pyrotechnic charge in gelled form contained in the second flexible element is capable of generating a volume of gas sufficient to keep the cushion inflated during a time period of the order of several seconds.
• the second flexible element is produced using a flexible tube of thermoplastic material provided with outlet orifices regularly distributed over its circumference and over its length.
• a flexible plastic sheath encloses and confines the pyrotechnic charge in gelled form contained in the first and / or the second flexible element.
• the flexible plastic sheath encloses and confines the pyrotechnic charge in gelled form as well as a relay charge which is adjacent to the pyrotechnic charge in gelled form contained in the first flexible element.
• US Pat. No. 5,060,973 discloses liquid propellant compositions comprising 60% hydroxylammonium nitrate (HAN) as an oxidant, 20% triethanolammonium nitrate as a reducing agent and 20% water.
• HAN hydroxylammonium nitrate
• US patent 6,228,193 also refers in its introduction to US patent 5,060,973.
• This patent US 6,228,193 describes for its part the use of a gas generator block intended to be integrated into a device for protecting the occupants of a motor vehicle.
• This gas generator block consists of a solid solution comprising a water-soluble liquid oxidant, a gelling agent and water.
• the gelling agent is organic and has a sufficient number of carbon atoms to function as fuel with the liquid oxidant.
• the liquid oxidant chosen is hydroxylammonium nitrate and the gelling agent is polyvinyl alcohol.
• a preferred composition disclosed in this patent consists of 50 to 90% hydroxylammonium nitrate, 5 to 25% polyvinyl alcohol and 5 to 25% water.
• Another object of the invention is to provide a gelled propellant composition which can be introduced into the flexible element of a flexible gas generator as described above and which can be used in the various embodiments of the device generating gas according to the invention.
• a gelled propellant composition comprising a liquid propellant consisting of an oxidant, a reducing agent and water and a gelling agent.
• the oxidant is liquid and consists of the mixture of one or more oxidants solids and water.
• the solid oxidant is chosen from hydroxylammonium nitrate (HAN), ammonium nitrate (NA) and ammonium dinitraminate (DNA).
• the reducing agent consists of triethanolammonium nitrate (TEAN).
• the gelling agent is chosen from the group consisting of polyvinyl alcohol, hydroxyethylcellulose and xanthan gum.
• the liquid propellant will comprise for example 60% of hydroxylammonium nitrate (HAN), 20% of water and 20% of triethanolammonium nitrate (TEAN).
• HAN hydroxylammonium nitrate
• TEAN triethanolammonium nitrate
• the liquid propellant will comprise, for example as an oxidant, a 50-50 mixture of hydroxylammonium nitrate (HAN) and ammonium dinitraminate (DNA), triethanolammonium nitrate (TEAN) and water.
• HAN hydroxylammonium nitrate
• DNA ammonium dinitraminate
• TEAN triethanolammonium nitrate
• Figure 1 is a longitudinal sectional view of a gas generating device according to a first embodiment of one invention.
• Figure 2 is a longitudinal sectional view of a gas generating device according to a second embodiment of one invention.
• Figure 3 is a longitudinal sectional view of a gas generating device according to a third embodiment of the invention.
• Figure 4A is a longitudinal sectional view of a gas generating device according to a fourth embodiment of the invention.
• Figures 4B and 4C are respectively a top view and a side view of the gas generating device according to the fourth embodiment of the invention shown in Figure
• Figure 5 is an enlarged partial view of the flexible element used in the gas generating devices presented above and containing a pyrotechnic charge contained in a flexible sheath.
• the invention relates to a specific gas generator which can be integrated into gas generating devices having different configurations, in particular those which will be described below in conjunction with FIGS. 1 to 4C.
• This gas generator 1 mainly comprises an electro-pyrotechnic igniter 2 and a flexible element into which a pyrotechnic charge 10 in gelled form is inserted.
• This flexible element consists of a flexible tube 11 made of thermoplastic material with a small internal diameter.
• This flexible tube 11 is closed at one of its ends, called the first end 110.
• This first end 110 is for example stamped and then welded in order to constitute a tight plug.
• the pyrotechnic charge 10 is a gelled propellant which is inserted by injection or by suction into the tube 11.
• FIG. 5 shows a detail of the flexible element and shows the positioning of each of the generator elements described above.
• the flexible tube 11 is provided with outlet orifices 13 regularly distributed over its circumference and over its length. These orifices 13 are intended to let escape the gases resulting from the combustion of the pyrotechnic charge 10 in gelled form. These orifices are regularly distributed over the circumference and over the entire length of the flexible tube 11 so as to obtain a release of gases towards all the regions of the protective cushion (not shown) and thus allow uniform inflation of the protective cushion.
• the electro-pyrotechnic igniter 2 conventionally comprises a body and an ignition head 20 containing an ignition composition intended to be initiated in combustion, for example by a resistive heating element connected to two conductive electrodes passing through its body.
• the ignition of the gelled propellant will be obtained for example by using a charge 6 relays placed near the pyrotechnic charge 10 in gelled form.
• the flexible sheath 12 encloses for example at one of its ends, called the first end 120, the relay load 6 in contact with the gelled propellant, the gelled propellant then extending to the other end of the sheath 12, said second end 121, located near the first end 110 of the tube 11.
• the gelled propellant will burn like a cigarette.
• An ignition transmission system consisting of a cord coated by the pyrotechnic charge 10 in gelled form can be provided over the entire length of the tube 11 so as to obtain combustion of the gelled propellant in concentric parallel layers around this system of transmission.
• the pyrotechnic charge in gelled form used is a liquid propellant gelled with a mineral product or on an organic product. It consists of an oxidant, a reducing agent, water and a gelling agent.
• the oxidant will for example be liquid and consist of one or more solid oxidants and water.
• solid oxidants are hydroxylammonium nitrate (HAN), ammonium nitrate (NA) and ammonium dinitraminate (DNA).
• a liquid oxidant consists, for example, of 90% hydoxylammonium nitrate (HAN), 5% ammonium nitrate (NA) and 5% water.
• Triethanolammonium nitrate (TEAN) is often used as a liquid reducing agent.
• the gelling agent may for example be polyvinyl alcohol, hydroxyethylcellulose or xanthan gum.
• a typical liquid propellant composition is the XM46 formulation which was developed for the propulsion of shells. It contains approximately 60% hydroxylammonium nitrate (HAN), 20% triethanolammonium nitrate (TEAN) and 20% water. Examples of liquid propellant composition are illustrated in Tables 1 and 2 below. Table 1 shows results for three liquid propellant compositions each comprising hydroxylammonium nitrate (HAN), triethanolammonium nitrate (TEAN) and water in different proportions in each of the compositions.
• HAN hydroxylammonium nitrate
• TEAN triethanolammonium nitrate
• Table 2 shows results for three liquid propellant compositions comprising a mixture in equal proportions of hydroxylammonium nitrate (HAN) and ammonium dinitraminate (DNA), triethanolammonium nitrate (TEAN) and water in different proportions in each of the compositions.
• HAN hydroxylammonium nitrate
• DNA ammonium dinitraminate
• TEAN triethanolammonium nitrate
• a liquid propellant composition has a low combustion temperature of less than 2000 K. It also has the following advantages:
• the liquid propellant is gelled by a mineral product or on an organic product.
• Gelification on an organic product has the advantage of not generating a solid particle. Gelification provides the following advantages: - Lowering of the solidification temperature below -40 ° C; - Lowering the vapor pressure;
• this type of gelled composition can be inserted into a flexible gas generator 1 as described above.
• a gas generator device 3 according to a first embodiment comprises a flexible gas generator 1 according to the invention as described above.
• this device 3 comprises a metallic body 30, having the shape of a part cylindrical tubular open at both ends.
• the axis of revolution of the body 30 is defined as its longitudinal axis (A).
• the electro-pyrotechnic igniter 2 is fixed to the body 30 by being inserted at one of its ends, called the first end 300.
• the igniter 2 is inserted along the longitudinal axis (A) of the body 30 so that its ignition head 20 is located inside the body 30.
• the igniter 2 is for example fixed in the body 30 by crimping.
• a ring 4 whose axis is substantially coincident with the longitudinal axis (A) of the body 30.
• This ring 4 is extended along its axis, towards the outside of the device 3, via a nose 40.
• the annular wall forming the nose is intended to be fitted between the flexible tube 11 of the flexible generator 1, at its end, called the second end, opposite its first end 110 , and the flexible plastic sheath 12 enclosing the pyrotechnic charge 10 in gelled form.
• a clamping collar 5 On this second end of the tube 11 is attached a clamping collar 5 which for example is screwed onto said ring 4.
• This gas-generating device 3 comprising a gas generator 1 according to the invention is intended to protect the occupants of a motor vehicle during a first side impact. It does not include additional means making it possible to protect the occupants of a motor vehicle when, following this first side impact, the vehicle is subjected to barrels.
• the flexible generator 1 is inserted into the protective cushion.
• the device 3 operates as follows.
• the electro-pyrotechnic igniter 2 first of all ensures the ignition of the relay load 6.
• the relay load 6 very quickly initiates combustion of the pyrotechnic charge 10 in gelled form contained in the flexible element which generates in a few milliseconds a large amount of gas that can escape through the outlet orifices 13 formed through the flexible tube 11.
• the protective cushion is fully inflated in a period of time not exceeding forty milliseconds and can thus protect the occupants of a motor vehicle during a first impact.
• FIG. 2 represents a second embodiment of a device 7 for generating gas according to the invention.
• this gas generator device 7 is semi-flexible, that is to say it comprises a rigid part 70 attached to the flexible element of the gas generator 1 as described above.
• This rigid part 70 consists of a metal part cylindrical tubular open at its two ends, called first end 700 and second end 701.
• the axis of revolution of the rigid part 70 is defined as its longitudinal axis (Al).
• the electro-pyrotechnic igniter 2 is fixed at the first end 700 of the rigid part 70.
• the ring 4 At the second end 701 of the rigid part 70 is inserted and then fixed the ring 4 whose axis is substantially coincident with the longitudinal axis (Al) of the rigid part 70.
• the ring 4 supports the flexible element using its projecting nose 40 extending it outwards.
• the first end 120 of the flexible sheath 12 enclosing the relay load 6 and part of the pyrotechnic charge 10 in gelled form is inserted into the orifice formed by the nose 40 then by the ring 4.
• the insertion of the flexible sheath 12 into the orifice is not carried out over the entire length of the nose 40 and of the ring 4 located in its extension.
• the collar 5 comes, for example as in the first mode, to be screwed onto said ring 4.
• the diameter of the flexible sheath 12 is slightly less than the internal diameter of the orifice formed by the ring 4.
• a block 72 of solid cylindrical propellant is placed inside the rigid part 70.
• This block 72 of solid propellant has a central channel.
• the longitudinal axis of the block 72 is substantially coincident with the longitudinal axis (Al) of the rigid part 70.
• Block 72 of solid propellant is wedged in part 70 rigid using a wedge 721 and held in this position by a spring 720.
• the central channel of the block 72 is traversed over its entire length by a tube 73 whose longitudinal axis is substantially coincident with the longitudinal axis (Al) of the rigid part 70.
• the external diameter of this tube 73 is slightly smaller than the internal diameter of the central channel of the block 72 of solid propellant, so that the external surface of the tube 73 is in contact with the internal wall of the block 72 of solid propellant forming its channel.
• This tube 73 has a first end 730 which is inserted into the ring 4 so as to be adjacent to the relay charge 6 serving for initiating the pyrotechnic charge 10 in gelled form contained in the flexible element.
• the external diameter of the tube 73 is slightly less than the internal diameter of the orifice formed by the ring 4 and adapted so that the connection between the tube 73 and the ring 4 is sufficiently tight.
• the other end of the tube 73 is flared.
• the tube 73 is crimped at its end 731 flared on the inner wall of the rigid part 70, at the first end 700 of the rigid part 70.
• the igniter 2 is inserted into the flared part of the tube 73 so that its ignition head is located inside the flared part of the tube 73 and oriented along the axis of the tube 73.
• the body of the igniter 2 is then thus fixed to tube 73, at its flared end.
• a pyrotechnic varnish 732 is deposited on the entire internal surface of the tube 73 with the exception of its flared part. This pyrotechnic varnish 732 is put into combustion by the gases coming from the electro-pyrotechnic igniter 2.
• This pyrotechnic varnish 732 makes it possible to transmit the ignition to the relay load 6 and also to heat the tube 73 by conduction. Heating the tube 73 thus makes it possible to initiate the block 72 of solid propellant through its central channel. The combustion of the solid propellant block will thus occur in concentric parallel layers, from the inside to the outside.
• the ring 4 is pierced with a channel 74 opening at one of its ends in the rigid part and at its other end towards the outside.
• This channel 74 serves as an outlet for the gases resulting from the combustion of the block 72 of solid propellant.
• the outlet through the outlet orifices formed on the flexible tube 11 of the flexible generator is impossible since the tube 73 blocks the access to the flexible generator with its first end 730 inserted in the ring 4.
• the gases resulting from the combustion of the block 72 of solid propellants are very hot and are released for a long period, of the order of ten seconds. Prolonged release of these hot gases could melt the flexible tube 11 of the flexible generator 1.
• the device 7 operates as follows.
• the electro-pyrotechnic igniter 2 ignites the pyrotechnic varnish 732 applied to the internal wall of the tube 73.
• the combustion of the pyrotechnic varnish 732 causes the relay load 6 to ignite and the tube 73 to heat up by conduction.
• the relay 6 very quickly causes the initiation into combustion of the pyrotechnic charge 10 in gelled form contained in the flexible element, which generates in a few milliseconds a large quantity of gas which can escape through the outlet orifices 13 formed through the tube 11 flexible.
• the protective cushion is fully inflated in a period of time not exceeding forty milliseconds and can thus protect the occupants of a motor vehicle during a first impact.
• the heating of the tube 73 causes the initiation of the block 72 of solid propellant contained in the rigid part 70.
• the gases from the combustion of the solid propellant block 72 then escape through the channel 74 and make it possible to keep the protective cushion fully inflated during a period of time of the order of ten seconds.
• FIG. 3 represents a third embodiment of a device 8 for generating gas.
• the gas generator device is hybrid, that is to say it comprises a pyrotechnic charge and a pressurized gas tank.
• the gas generator device 8 is semi-flexible and therefore comprises a flexible generator 1 such as that described above and a rigid part.
• the gas generator device 8 more precisely comprises a metallic body 80 having the form of a tubular part open at its two ends, called the first end 800 and the second end 801.
• This tubular part comprises a side wall through which an orifice is formed .
• the electro-pyrotechnic igniter 2 In this orifice is inserted and then welded the electro-pyrotechnic igniter 2, so that the head 20 of the igniter 2 protrudes inside the tubular part.
• the ring 4 extending through the nose 40 is partially inserted into the body 5 at the second end 801 of the body 5.
• the nose 40 is inserted between the flexible tube 11 and the flexible sheath 12 enclosing and confining the gelled propellant.
• the collar 5 for holding the tube on the ring is fixed by screwing on said ring 4.
• a cylindrical metal part 81 is partially inserted into the tubular part constituting the body 80 at its first end 800 and fixed by crimping in the body 80
• This cylindrical metal piece 81 therefore has a projecting part towards outside the body 80.
• the metal part 81 also has a central recess. This central recess is hollowed out over practically the entire thickness of the metal part 81 so as to leave only a solid end 810 of small thickness which can play the role in operation of a frangible cover.
• the central recess is formed so that its opening is oriented towards the inside of the tubular part constituting the body 80.
• a relay load 82 is housed in the central recess formed in this metal part 81.
• the reservoir 83 is produced using a cylindrical metal body comprising, on the one hand, a first end having a gas filling orifice 84 closed by a plug 830 fixed by welding, and on the other hand, a second open end.
• a cylindrical metal body 85 with a central passage forming an internal nozzle is introduced into the tank 83 and is force-fitted near the second end of said tank 83.
• the tank 83 provided with the metal body 85 is finally fixed by welding to the body 80 on the projecting part of the metal piece 81 set in the body 80.
• the device 8 In the event of an impact requiring inflation of the protective cushion to ensure the protection of the occupant, the device 8 according to this third embodiment operates in the following manner.
• the electro-pyrotechnic igniter 2 ignites the two relay charges 6 and 82.
• the first relay charge 6 very quickly initiates combustion of the gelled propellant contained in the element flexible, which generates in a few milliseconds a large amount of gas which escapes through the outlet orifices 13 formed in the flexible tube 11.
• the protective cushion is fully inflated in a period of time not exceeding forty milliseconds.
• the flexible generator makes it possible to inflate the protective cushion very quickly during a first impact.
• the relay charge 82 forces the solid end 810 of the metal part 81 to fracture and the gas 84 under pressure contained in the tank 83 can escape slowly while passing through first the central passage of the metal body 85, then the metal part 81, the body 80 and finally enter the tube 11 now empty, the propellant gel having finished burning.
• This gas 84 is then evacuated through the outlet orifices 13 of the tube and makes it possible to keep the protective cushion fully inflated during a period of time of the order of ten seconds. It is possible to increase or reduce this period of time by varying the pressure level and the volume of the gas 84 contained in the reservoir 83 or even by modifying the diameter of the central passage of the metallic body 85.
• the gas tank 83 84 keeps the cushion inflated during a period of time of the order of ten seconds, which will make it possible to protect the occupants of a motor vehicle and in particular their heads when the vehicle is subjected, for example, to barrels following the first side impact.
• FIGS. 4A to 4C represent a fourth embodiment of a gas generator device 9 according to the invention using a flexible generator 1 as described above.
• this fourth embodiment it is a gas generator device 9 consisting of the gas generator device according to the first embodiment to which a second flexible element is added.
• the device therefore comprises a body 30 in which is housed an igniter 2 and to which is attached a flexible element of the gas generator 1 as described above.
• the flexible tube 11 does not however have its first end 110 closed as in the first embodiment.
• a first end of a conduit 90 having the shape of a U is connected to the first now open end of the flexible tube 11.
• the second end of this conduit 90 is connected to a second flexible element structurally identical to that of the flexible generator 1 described above.
• This second flexible element therefore consists of a flexible tube 91 made of thermoplastic material having outlet orifices 93 distributed over its circumference and over its entire length.
• a pyrotechnic charge (not visible) in gelled form is placed inside the flexible tube 91.
• a flexible sheath (not visible) inserted between the tube and the pyrotechnic charge in gelled form encloses and confines the pyrotechnic charge in gelled form.
• the free end 910 of the flexible tube 91 is closed, for example by being stamped and then welded in order to constitute a tight plug.
• a piece 94 makes it possible to secure the second flexible element to the first flexible element.
• the pyrotechnic charge in gelled form contained in the first flexible element has a higher combustion speed than that of the gelled pyrotechnic charge contained in the second flexible element.
• the pyrotechnic charge contained in the first flexible element is capable in operation of generating a quantity of gas sufficient to inflate the protective cushion in a period of time of less than forty milliseconds.
• the pyrotechnic charge contained in the second flexible element is capable of generating in operation a quantity of gas sufficient to keep the cushion inflated in a period of time of the order of ten seconds.
• the electro-pyrotechnic igniter 2 ignites the relay charge 6.
• This relay charge 6 very quickly initiates combustion of the gelled propellant contained in the first flexible element, which generates a large amount of gas in a few milliseconds which escapes through the orifices of outlet 13 formed in the flexible tube 11.
• the protective cushion is fully inflated in a period of time not exceeding forty milliseconds. This will protect the occupants of a motor vehicle during a first impact.
• the gases resulting from the combustion of the gelled propellant contained in the first flexible element initiate in combustion the pyrotechnic charge in gelled form contained in the second flexible element.
• the gases resulting from the combustion of the pyrotechnic charge in gelled form contained in the second flexible element escape through the outlet orifices 93 formed through the flexible tube 91 of the second flexible element.

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• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
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• Combustion & Propulsion (AREA)
• Air Bags (AREA)

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• 2002
  • 2002-10-18 FR FR0212988A patent/FR2845989B1/fr not_active Expired - Fee Related
• 2003
  • 2003-10-17 EP EP03775490A patent/EP1551784A1/de not_active Withdrawn
  • 2003-10-17 AU AU2003283516A patent/AU2003283516A1/en not_active Abandoned
  • 2003-10-17 WO PCT/FR2003/003086 patent/WO2004035510A1/fr not_active Ceased

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