MXPA01005475A - Dual level inflator - Google Patents

Abstract

A dual level inflator (10) is provided for creating at least two different rates and levels of air bag inflation while optimizing cost effectiveness, size, safety, and performance. The dual level inflator includes a unitized gas generator canister assembly (16) including two canisters of gas generant material connected to a common base and positioned in a chamber (14) formed in an inflator outer housing (12). The unitized assembly is easily transportable and mountable on the outer housing. Each canister of the unitized assembly includes apertures permitting direct communication between each canister cavity and the chamber of the outer housing. As a result, generant material positioned in each canister is directly exposed to the conditions in the outer housing chamber. The present assembly is advantageous in that it maximizes the internal volume available to the stored gas and, after the ignition of one canister and the inflation of the air bag, the remaining canister may be ignited without reinflating the air bag due to the previous depressurization of the chamber in combination with the selection of a generant material incapable of effectively burning in a low pressure environment, i.e. the directly connected chamber. The present dual inflator also includes seal means to prevent inadvertent ignition, and an arrangement by which the plurality of apertures formed in one canister are positioned relative to the apertures in the other canister to cause the gas flowing from one set of apertures to be sufficiently cooled by the inert gas in the chamber prior to reaching the apertures of the other canister thereby preventing inadvertent thermally induced ignition of the generant material in the remaining unfiredcanister.

Description

DOUBLE LEVEL INFLATOR BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates generally to an inflator device that includes gas generators and more specifically to a double level inflator which can selectively release gas at different speeds and levels and therefore allows an air bag or an immobilization device Similar or inflatable type of security is deployed to different output levels, according to the different detector inputs.

DESCRIPTION OF THE RELATED TECHNIQUE Recently, there has been a demand for control of the speed and amount of inflation of safety devices such as air bag immobilization systems, according to variables, such as passenger size, position, use of the safety belt and vehicle speed. at the time of the collision. In order to provide optimum protection for the occupant, different levels of airbag inflator output are required. For example, in a high speed collision with a large person without a belt, a full rapid inflation of the airbag is required to provide the best immobilization. In collisions at lower speeds with smaller sized occupants or even occupants in out of position, a slower and lower inflation rate is required so as not to inadvertently damage the occupant but still provide enough inflation to provide immobilization. In order to obtain the two levels of inflation, it has been proposed in the United States Patent No. 3,773,353 for Tro bridge et al. provides two separate charges and activate one in the case that a slow inflation is required and activate both in the case of a high-speed collision, so that you get a very fast inflation and deployment of the airbag which is necessary under such circumstances. In this device, the loads are distributed inside a tank which is filled with a non-toxic gas under pressure. This housing is sealed by a discharge plate that is punctured by a piston and a type of distribution rod when the first of the two charges is detonated. However, this distribution suffers from the drawback of being relatively complex and therefore relatively expensive. For example, no less than three discard plate distributions are necessary. In addition, the charges are each insulated from the reservoir and the reservoir gas by an inner housing and a respective rupturable closure. United States Patent No. 3,905,515 for Alleman describes another two-stage inflator assembly which uses two separate charges and which discards the charge in a chamber which is used to store a non-toxic gas under pressure. However, this distribution is even more complex than that of Patent No. 3,773,353. In this arrangement, a portion of the discharge disc forms the head of a slidable shuttle valve member which is projectible to an exit passage to partially throttle the gas exit flow after a detonation of one or both of the charges . Another important concern in a double-level inflator design is the disposal capacity of the inflator assembly after use, for example, when the inflator assembly is removed for disposal or the entire vehicle becomes a waste. In double-level devices if a gas generator is activated, for example in reaction in a low speed connection, the other generator must remain activatable, so that it generates a potential safety concern maybe during the removal or storage of the vehicle. If activated accidentally, the second generator can produce hot gases at high pressure.

For this reason, it is preferred that in the case of a scenario where only the first generator is deployed, the second generator is also deployed after the immediate impact but still within the shock process., for example up to 100 milliseconds after the impact. In this case, it is important to provide as little outlet within the air bag as possible so that the bag does not re-inflate and may hit the occupant. European Patent Publication No. 800965 for Buchanan discloses an inflator that includes a spherical housing that forms a main chamber and two heating devices mounted in the main chamber. The heating devices are activated sequentially to obtain a wide range of operation. However, each heating device is covered with a barrier cover to isolate the device from the gas in the main chamber. As a result, the pressure in the heating device must be increased to a level sufficient to break the barrier cover. In addition, due to the nature of the generant gas typically used in inflators, the generant gas burns more rapidly under a higher pressure which causes increased heating or gas generation. If the inflation is operated in a dual mode and only a heating device corresponding to a low velocity impact is activated, the intentional or inadvertent activation of the remaining gas generator may be sufficient to re-inflate the airbag. In addition, the heating devices are isolated from the stored gas so that volume is wasted which can be occupied by the stored gas and which can make the entire inflator smaller. U.S. Patent Nos. 5,582,428 and 5,630,619 describe other similar inflators. However, these inflators are unnecessarily complex with multiple discharging disks and multiple containers and are also likely to cause reinflation of the bag upon subsequent activation of an unused generator. In addition, the devices described by Tro bridge et al. and Allemann, discussed in the foregoing, present similar drawbacks to the device described in Buchanan. Accordingly, there is a need for simple, compact and cost-effective double level inflation capable of enabling activation of a second generator after the activation of a first generator without inflating a collapsed air bag in a manner Deactivate the unit for disposal.

BRIEF DESCRIPTION OF THE INVENTION An object of the present invention therefore is to overcome the disadvantages of the prior art and provide a cost-effective but safe double-level inflation device which effectively allows double-level operation. A further objective of the present invention is to provide a double-level inflator which allows the activation of one or both generators causing the initial inflating of an air bag and subsequent activation of a second generator in a scenario that requires the output of only one generator, without re-inflating the air pockets. A further objective of the present invention is to provide a double-level inflator that includes or sub-assembly of the unit generating can which maximizes the internal volume available for the stored gas, which is easily transportable and which is easily attached to the inflator assembly. Another object of the present invention is to provide a double level inflator which improves the safety for the personnel after the vehicle accident by allowing the deactivation of the second generator within the crash process.

Another objective of the present invention is to provide a double level inflator which allows the gas generating loads at each level to be adjusted independently based on the requirements of the system so that their adaptability is maximized. Another additional objective of the present invention is to provide a double level inflator which minimizes the cost and size of the assembly. These and other objects of the present invention are obtained by providing a double-level inflation device for inflating a vehicle's safety immobilizer, comprising an exterior housing that includes a chamber to contain an inert gas quantity stored and an outlet for directing the pressurized gas into the vehicle safety immobilization element a first generator lat mounted in a chamber and including a first can wall forming a cavity containing a gas generating material and at least one opening to allow open communication between the cavity and the chamber, and a second generating can assembled in the chamber and including a second can wall forming a cavity containing gas generating material and at least a second aperture to allow open communication between the cavity and the camera. Importantly, the ga generator material in both the first generating can and the second generating lat is exposed to stored inert gas to avoid an undesirable increase in the pressure in the respective cavity before the activation of the generator material and to maximize the internal volume available for the stored gas so that the total size of the inflator is minimized. The double level inflation device also includes at least one activator for activating the gas generating material in the first and second generating cans. The gas generating material in at least one of the first and second generating cans is of a type that is not capable of effectively burning under low pressure. As a result, the generator material not activated in one of the generating cans can be activated subsequent to the activation of the other generating can without re-inflating the associated vehicle safety immobilization element, ie, the airbag. Preferably, each of the first and second generating cans includes a reinforcement load mounted in the cavity between the activator and the generating material. At least the first opening and at least the second aperture preferably include a reinforcing aperture positioned adjacent one of the reinforcing load and at least one activator. Preferably, each of at least the first opening and at least one second opening includes a plurality of longitudinally extending openings along the respective generating can. The plurality of openings may include two rows of openings. The first generating can may contain a first predetermined amount of gas generating material while the second generating can may contain a second predetermined amount of material greater or less than the first predetermined amount. The present invention is also directed to a double level inflation device for inflating a vehicle security immobilization element., which comprises an outer housing that includes a chamber for holding an amount of inert gas at a first predetermined pressure level and an outlet for directing the pressurized gas within the vehicle safety immobilization element, a discharge disc positioned to close the come out and adapted to fail when the pressure in the chamber reached a second predetermined pressure level greater than the first predetermined pressure level, a first generator can mounted in the chamber and including a cavity containing gas generating material and so minus a first aperture formed in the can to allow open communication between the cavity and the chamber, and a second generating can mounted in the chamber and including a cavity containing a gas generating material and at least one second aperture to allow the open communication between the respective cavity and the camera. The double-level inflation device also includes at least one activator, for activating the generating material in the first and second generating cans. Importantly, the double level inflation device also includes an activation prevention arrangement to prevent inadvertent activation of the gas generating material in the second generating can before the activation and burning of gas generating material in the first generating can. The activation prevention arrangement includes placing at least one first aperture and at least one second aperture at a sufficient distance apart to cause the gas to flow from at least one first aperture to be sufficiently cooled by the inert gas in the aperture. camera before it reaches at least the second opening. In a preferred embodiment each of the first and second generating cans includes a first side oriented in a first common direction and a second side oriented in a second common direction substantially opposite the first direction. The activation prevention arrangement d includes at least a first opening that is placed on the first side of the first generating lat, while the second side of the first generating lat is free of openings. The activation prevention arrangement also includes at least a second aperture which is placed on a second side of the second generating can while the first side of the second generating can is free of openings. In addition, there is a seal between the generators on the common base to avoid inadvertent activation of the second generator. The present invention is also directed to an inflation device for inflating a vehicle security immobilization element comprising an outer housing that includes a chamber for holding a quantity of inert gas stored and a lat. Gas generator assembly mounted in a chamber. that includes a first generating can that contains a material generated from gas, a second can generator that contains a gas-generating material and that is placed adjacent to the first generating lat, and a common base connected to the first end of the first as of the second generator housing where the common base connects to the outer housing. The inflation device also includes an activated first positioned adjacent to the common base at the first end of the first generating can to activate the gas generating material in the first generating can, and an activated second placed adjacent to the common base in the first end of the second generating can to activate the gas generating material in the second generating can. Preferably, each of the first and second generating cans is cylindrically shaped and the common base includes a mounting flange extending transversely outward from the first and second generating cans to two opposite sides of the unitized gas generating assembly. The outer housing preferably has a generally circular cross section and the common base is placed inside the outer housing chamber. The outer housing may include an end cap mounted so as to close one end of the chamber and an outlet formed at an opposite end of the chamber and so that the discharge disc may be placed to close the outlet and adapt it to fail. when pressed and the camera reaches a predetermined pressure level Preferably, the first and second activators are mounted on the end layer. In addition, each of the first generating gene and the second generating can preferably include a plurality of openings that expose the gas generating material to the inert gas stored in the chamber so as to avoid an undesirable increase in the pressure in the cavity upon activation. of the second gas generator material.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of the inflation device of the present invention including assembly of the unified gas generating can of the present invention taken along the plane la-la in FIG.

Figure Ib is an end view of one end of the inflation device of the figure which shows the placement of the activators; the figure is a cross-sectional view of the inflation device of the figure taken along the plane lc-lc; Figure Id is a partial cross-sectional view of the inflation device of the present invention taken along the plane ld-ld in Figure Ib; Figure 2a is a cross-sectional view of the unified gas generating can assembly of the present invention; Figure 2b is a perspective view showing one side of the unified gas generating can assembly of the present invention; and Figure 2c is a perspective view of the gas generating can assembly assembled in an inverted position showing an opposite side of the assembly.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES With reference to FIG. 1, there is shown a double-level inflator or inflator of the present invention, generally referred to as number 10, which functions effectively and reliably to provide a high level and speed of inflation of an element. of vehicle safety immobilization, ie, an airbag, in the case, for example, of a high-speed vehicle collision or, alternatively, at a low level and inflation speed of an airbag in the case of a collision at low speed. The double-level inflator 10 generally includes an outer housing 12 that forms a chamber 14, a mounting 16 of a unified gas generating can positioned in the chamber 14, and a first and second activators 18, 20 for initiating the burning of the generator material of the generator. assembly 16 of unified gas generating can. As shown in FIGS la-le, the outer housing 12 includes a housing portion 22 in generally cylindrical shape and an end cap 24 mounted on one end of the housing portion 22 so as to sealingly enclose the chamber 14 , and an output piece 26 mounted at an opposite end of the housing portion 22. The outlet piece 26 extends into the chamber 14 and includes outlet openings 28 for directing gas from the chamber 14 into the air bag (not shown). A diffuser 30 is mounted immediately upstream of the outlet openings 28 and a discharge disc 32 is mounted immediately upstream of the diffuser 30. The discharge disc 32 is adapted to fail upon application of a predetermined pressure thereby allowing the pressurized gas flows from the chamber 14 through the outlet openings 28 into the interior of the air bag. After it is assembled in double-level inflator 10, including the installation of a unified gas generating can 16 as discussed more fully in the following, the end cap 24 is hermetically sealed. A filling orifice 34 is provided in the end cap 24 to facilitate loading of the chamber 14 with a selected non-toxic gas, such as argon or helium, under pressure. As shown in FIGS. 1a, 2a and 2c, the assembly 16 of the unified gas generating can includes a first generating can 36 that is formed by a first can 38, and a second can 40 that is formed by a second can wall 42. Both the first and the second generation cans 36 and 40 are generally cylindrical in shape to form the respective cavities 44 and 46. A generating material indicated with the number 48 is placed in each cavity 44, 46 to generate gas upon activation. In order to obtain double-level operation, a sufficient amount of gas-generating material 48 is placed in the first generating can 36 to allow inflation of the air-bag at a reduced level and speed during, for example a collision at low speed, without the ignition and activation of the second generating can. The second generator can includes a quantity of gas generating material 48 which when activated with the first generating can 36 will create, in combination, a desired higher level and inflation speed during, for example, a high speed collision. The gas generating material 48 is held in position within the respective cavity 44, 46 by a deflection spring 50 and a spring plate 52. The first and second generator cans 36, 40 also each include a reinforcing load 54 placed in a reinforcing housing 56 that is mounted at one end of each cavity adjacent to the first activator 18 and the second activator 20. The load 54 of The reinforcement functions to provide a more effective and reliable activation of the generator material 48 by the activators 18, 20. The assembly 16 of the unified gas generating can advantageously forms as an integral unified assembly which can be easily transported before the final assembly.

Specifically, the first and second generator cans 36, 40 are mounted in contact with each other and connected to a common bas 58, as clearly shown in Figures 2a-2c. The size of the assembly 16 of the unified gas generating can is minimized by forming a common base 58 with a diameter substantially no greater than the combined outer width of the first and second generating cans 36 and 40. The common base 58 includes two mounting flanges 60 extending radially outwardly from a central opening 62 shaped to receive tightly one end of one of the first and second generating cans 36, 40. The common base 58 also includes a support ring 64 which extends around the central opening 62 for support, and which provides a connection position for the first and second generating cans 36, 40. The first and second generator cans 36, 40 can be connected to a common base 58 and specifically a support ring 64, for example by welding with a strong weld, or welding. As a result, the assembly 16 of the unified gas generating can is self-contained and highly compact and at the same time can be easily transported and can be attached to the outer housing 12. As shown in Figures 1, 1 and 1, the gas generator assembly 16 is mounted in the chamber 14 by connecting the common base 5 and the end cap 24 in any conventional manner. A seal 75 is mounted between the common base 58 and the end cap 24 to further ensure that there is no inadvertent activation of the second generator. The first and second activators 18 and 20, respectively, are mounted on the inner portion of the end layer 24 and extend within the first and second respective generator cans 36 and 40. The opposite side of the first and second activators 18 and 20 include connectors for connection to the appropriate electrical wiring to provide activation signals to the actuators.

The first and second generator cans 36 and 40 each include a plurality of openings that are formed in the respective can wall to allow the respective cavity to communicate directly with the chamber 14. Specifically, as shown in Figures 2b and 2c, the first generating can 36 includes a plurality of openings 66 that are placed on a first side 70 of the unified gas generating can assembly 16 while the second generating can includes a plurality of openings 68 that are formed on a second side 72 of assembly 16 of unified generating can. In the preferred embodiment, as shown in Figures 2b and 2c, the first plurality of openings 66 formed in the first generating can 36 include two rows of openings extending longitudinally along the can 36. The plurality of openings 66 they also include a pair of reinforcing apertures 67 for controlling the pressure from the reinforcement load 54. Likewise, the plurality of aperture 68 includes two rows of apertures extending longitudinally along the second side of the second generating can that includes reinforcing apertures 69. Importantly, the plurality of openings 66 and 68 directly expose the generating material in the first and second generating tins 34, 40, respectively, to the conditions present in the chamber 14. The generating material 48 is placed in the first and second cans. 36 and 40 and do not include any other coating, sheath or wrapping between the generator material and the can walls which may cause pressure to accumulate in the respective cavity of the cans during the initial and continuous activation and the burning of both the reinforcing material as well as the generator. Importantly, this design allows the second generating can 40 to be activated subsequent to a predetermined time after activation of the first generating can 36 without re-inflating the air bag. For example, during a collision at low speed, the first generating can 36 will be activated which causes additional pressurization of the chamber 14 by the hot gas generated by the first generating can 36. As the gas generating material 48 is burned, the gas is released immediately through the plurality of openings 66 within the chamber 14 causing an increase in pressure in the chamber 14 due to an increased amount of gas and an increase in temperature. At a predetermined increased pressure level, the discharge disk 32 fails causing gas in the chamber 14 to flow through the outlet openings 28 into the air bag. Subsequently, it is desirable to activate the second generating can 4 for safety purposes and to prevent inadvertent activation and damage to personnel. This second activation can occur without re-inflating the air bag. The double-level inflation 10 of the present invention allows the second generating can to be activated without re-inflating the air bag for two specific reasons. First, the gas generator material 48 in the first and second generator cans 36, 40 is directly exposed to the chamber 14. As a result, when the second generator can 40 is activated by a second activator 20, the chamber 14 essentially it has been depressurized (approximately 100 milliseconds after the initial deployment). The gas generated by the second generating can in combination with an already depressurized volume of gas in the chamber 14 is simply insufficient to re-inflate the air bag. Secondly, the gas generating material 48 is of the type which is incapable of being burned effectively, that is, generating gas at high speed, in a low pressure environment. Since the initial gas generated by the gas generating material 48 is not contained due to the plurality of openings and is further released in a low pressure chamber 14, the gas generating material in the second generating can simply stops generating a enough volume of gas needed to re-inflate the airbag. For example, the gas generating material 48 may be of the type of material described in U.S. Patent No. 5,726,382, the entire contents of which are incorporated herein by reference. The double level inflation device 10 also includes an ignition prevention arrangement to prevent inadvertent ignition of the generator material in the second generator 40 upon activation and burning of the generator material 48 in the first generator can 36. During the activation of the first generating can 36, the gas generated by the burning of the generator material 48 goes out at a very high temperature. This high temperature gas flows through the plurality of openings 66 into the chamber 14 and is mixed with the inert gas in the chamber 14. It has been found that the high temperature gas of the first generating can 36 can cause a temperature-induced activation of the gas generator material 48 in the second generation can 40. However, the current activation prevention arrangement 74 prevents the activation induced by this temperature of the gas generating material 48 in the second generating can 40 by creating a long flow path between the plurality of openings 66 formed in the first can. 36 generator and the plurality of openings 68 that are formed in the second generating can. Specifically, the activation prevention arrangement includes placing the plurality of openings 66 in the first generating can 36 at a sufficient distance around the peripheral extension of the assembly 16 of the unified gas generating can from the plurality of openings 68 that is they form in the second generating can 40 to cause the gas to flow from the plurality of openings 66 and to be sufficiently cooled by the inert gas in the chamber 14 before reaching the plurality of openings 68 that are formed in the second can 40. generator In the preferred mode, as shown in Figures 2b and 2c, a plurality of openings 66 are formed in the first side 70 of the first generating can 36 while the second side 72 of the can 36 contains no openings. On the other hand, a plurality of openings 68 are formed on the second side of the second generating can 40 oriented in an opposite direction of the plurality of openings 66 while the first side 70 of the second generating can 40 is free of any opening. Therefore, the gas flowing through the plurality of aperture 66 must flow completely around the peripheral extension, or distal end, of the unified gas generating can assembly 16 before entering the plurality of aperture 68. As a As a result, the activation prevention arrangement 74 of the present invention generates a large cooling path for the hot gas to flow through before reaching the openings of the remaining can so that the coldest inert gas in the chamber is allowed. 14 cool the hot gas generated by the first generating can 36 at a lower temperature unable to cause thermal induced activation of the generator material 48 in the second generating can. In addition, seal 75 mounted between common base 58 on end cap 24 prevents hot gas from flowing from the first generator to the second generator. This also ensures preventing the inadvertent activation of the second generator. As a result, this distribution generates a safer and more reliable dual level inflator device. Of course, the plurality of openings 66 and the plurality of openings 68 can be formed in other positions in the respective cans insofar as the distance between the openings is sufficient to allow adequate cooling of the high temperature gas to prevent activation Thermally inadvertently induced can not ignited.

Claims (21)

1. An inflation device for inflating the vehicle safety immobilization element, characterized in that it comprises: an outer housing that includes a chamber for containing an inert gas quantity stored; a assembly of a unified gas generating can mounted in the chamber and including a first generating can that includes a gas generating material, a second generating can containing a gas generating material and placed adjacent to the first generating can, and a common base connected to the first end of both the first and the second generating housings, the common base is connected to the outer housing; a first activator placed adjacent to the common base at the first end of the first generating can to activate the gas generating material in the first generating can; and a second activator placed adjacent to the common base at the first end of the second generating can to activate the gas generating material in the second generating can.

2. The inflation device according to claim 1, characterized in that each of the second generating cans are cylindrically shaped, the common base includes a mounting flange extending transversely outwardly from the first and second generating cans on two opposite sides of the assembly of a unified gas generator.

3. The inflation device according to claim 1, characterized in that the outer housing includes a generally circular cross section, the common base is placed inside the chamber of the outer housing.

4. The inflation device according to claim 1, characterized in that the outer housing includes an end cap mounted to close one end of the chamber and an outlet formed at an opposite end of the chamber, which further includes a discharge disc positioned for close the outlet and adapted to fail when the pressure in the chamber reaches a predetermined pressure level.

5. The inflation device according to claim 4, characterized in that the first and second actuators are mounted on the end cap.

6. The inflation device according to claim 1, characterized in that each generating can and the second generating can include a plurality of openings that expose the generating material for storing inert gas in the chamber to avoid an undesirable increase in pressure when the generator is activated. gas generator material.

7. The inflation device according to claim 6, characterized in that it also includes an activation prevention means to prevent inadvertent activation of the gas generating material in the second generating can when it is activated and the burning of the gas generating material in the first generating can, the means for preventing activation includes placing the plurality of openings in the first generating can at a sufficient distance from the plurality of openings in the second generating can to cause the gas to flow from the plurality of openings in the first can. generating can so that it is cooled sufficiently by the inert gas in the chamber before reaching the plurality of openings of the second generating can.

8. The inflation device according to claim 7, characterized in that it also comprises a seal means between the first generator and the second generator to prevent the hot gas from flowing between them.

9. A double-level inflation device for inflating a vehicle safety immobilization element, characterized in that it comprises: an outer housing that includes a chamber for holding a quantity of stored inert gas and an outlet for directing the pressurized gas to the interior of the immobilization of vehicle safety; a first generating can assembled in the chamber, the first generating can includes a first can wall forming a cavity containing gas generating material and at least a first opening formed in the first can wall to allow open communication between the can cavity and the chamber, the gas generating material in the first generating can is exposed to the stored inert gas to avoid an unwanted increase of the pressure in the cavity before the activation of the generating material; a second generating can assembled in the chamber, the second generating can includes a second can wall forming a cavity containing a gas generating material and at least a second opening formed in the second can wall to allow open communication between the the cavity and the chamber, the gas generating material and the second generating can are exposed to the inert gas stored to avoid an undesired increase in the pressure in the cavity before the activation of the generator material; and at least one activator for activating the generating material in the first and second generating cans.

10. The inflation device, according to claim 9, characterized in that the gas generating material in at least one of the first and second generating cans is of a type incapable of being effectively burned under low pressure.

11. The inflation device according to claim 10, characterized in that each of the first and second generating cans includes a reinforcing load mounted in the cavity between at least one activated and a gas-generating material, each of at least a first opening and at least one second opening includes a reinforcing opening placed adjacent the reinforcing load and at least one activator.

12. The inflation device according to claim 10, characterized in that each of at least the first opening and at least the second opening includes a plurality of openings extending longitudinally along the first and second generating cans.

13. The inflation device according to claim 12, characterized in that the plurality of openings includes two rows of openings.

14. The inflation device according to claim 10, characterized in that the first generating can contains a first predetermined amount of gas generating material and the second generating can contains a second predetermined amount of gas generating material smaller than the first predetermined quantity.

15. The inflation device according to claim 10, characterized in that it includes an activation prevention means to prevent the inadvertent activation of the generating material in the second generating can before the activation and burning of the generating material in the first generating can, the means of Activation prevention includes placing at least one first opening at a sufficient distance from at least one second opening to cause the gas flowing from at least the first opening to be sufficiently cooled by the inert gas in the chamber before reaching at least the second opening.

16. The inflation device according to claim 15, characterized in that each of the first and second generating cans includes a first side oriented in a first common direction and a second side oriented in a second common direction substantially opposite the first direction, the activation prevention means includes at least a first opening that is placed on the first side of the first generating can, the second side of the first generating can is free of openings, and at least a second opening that is placed on the second side of the second generating can, and the first side of the second generating can is free of openings.

17. The double-level inflation device for inflating a vehicle security immobilization element, characterized in that it comprises: an outer housing that includes a chamber for containing an inert gas quantity at a first predetermined pressure level and an outlet for directing the pressurized gas inside the immobilization element of the vehicle; a discharge disc positioned to close the outlet and adapted to fail upon pressure in the chamber when it reaches a second predetermined pressure level greater than the first predetermined pressure level; a first generating can assembled in the chamber and including a cavity containing a gas generating material and at least one first opening formed in the first generating can to allow open communication between the cavity and the chamber; a second generating can assembled in the chamber and including a cavity containing gas generating material and at least a second opening formed in the second generating can to allow open communication between the cavity and the chamber; at least one activator to activate the generator material in the first and second generation cans; a means for preventing activation to prevent inadvertent activation of the gas generating material in the second generating can before the activation and burning of the gas generating material in the first generating can, the activation prevention means includes placing at least a first opening at a sufficient distance from at least a second opening to cause gas to flow from at least the first opening which is sufficiently cooled by the inert gas in the chamber before reaching at least the second opening.

18. The inflation device according to claim 17, characterized in that each of the first and second generating cans includes a first side oriented in a first common direction and a second side oriented in a second common direction substantially opposite the first direction, in activation prevention means includes at least a first opening that is placed on the first side of the first generating can, the second side of the first generating can is free of openings, at least a second opening placed on the second side of the second generating can, the first side of the second generating can is free of openings.

19. The inflation device according to claim 17, characterized in that the outer housing includes an end stage mounted to close one end of the chamber and an outlet formed at an opposite end of the chamber, which further includes a discharge disc positioned for close the outlet and adapted to fail when the pressure in the chamber reaches a predetermined pressure level.

20. The inflation device according to claim 17, characterized in that at least one activator includes a first activator mounted on the end cap adjacent one end of the first generating can to activate the generating material in the first generating can, and second activator mounted on the end cap adjacent one end of the second generating can to activate the generating material in the second generating can.

21. The inflation device according to claim 17, characterized in that the gas generating material in the first and second generating cans are continuously exposed to stored inert gas to avoid an undesired pressure increase in the respective cavity before the activation of the generator material each of at least the first opening and at least the second opening includes a plurality of openings extending longitudinally along the first and second generating cans, wherein the gas generating material in at least one of the first and second generating cans are of a type incapable of burning effectively under pressure. SUMMARY OF THE INVENTION A double level inflator (10) is ided to create at least two different speeds and levels of inflation of an airbag while optimizing cost effectiveness, size, safety and performance. The double-level inflator includes a mounting 16 of a unified gas generating can that includes two cans of a gas-generating material connected to a common base and placed in a chamber (14) that is formed in an outer housing (12) of an inflator . The unified assembly is easily transportable and can be mounted on the outer housing. Each can in the unified assembly includes openings that allow direct communication between each can cavity and the chamber of the outer housing. As a result, the generator material placed in each can is exposed directly under the conditions in the outer housing chamber. The present assembly is advantageous in that it maximizes the internal volume available for the stored gas and, after activation of a can and inflation of the airbag, the remaining can can be activated without re-inflating the bag air due to the prior depressurization of the chamber in combination with the selection of a generator material capable of effectively burning in a low pressure environment, i.e., a directly connected chamber. The present double inflator also includes a seal means to prevent inadvertent activation and an arrangement whereby a plurality of openings formed in one can are placed in relation to the openings in the other can to cause the flow of gas from a set of openings to be cooled sufficiently by the inert gas in the chamber before reaching the openings of the other can, whereby inadvertent thermally induced activation of the generating material in the remaining non-activated can is prevented.