Abstract:
An airbag module to protect the automobile occupant, which includes an inflatable bag ( 11 ) from the gas that is produced by a generator when a dangerous situation to the occupant is detected, which includes a number of internal straps ( 15, 17  and  19 ) with different lengths and with each having a predetermined resistance to traction, which are joined at their ends to two areas ( 21  and  23 ) of the bag ( 11 ), limiting its deployment in the direction of the occupant. The length and resistance to traction of these straps are calibrated so that they break in succession during the deployment of the bag ( 11 ) until it reaches the occupant.

Description:
INVENTION FIELD 
     This invention refers to an airbag module for protecting a motor vehicle occupant, which can self-adapt to different the positions and sizes of the vehicle&#39;s occupant. 
     INVENTION BACKGROUND 
     Airbag modules with dual operation are known in the above technique; i.e. airbag modules that can adopt two different states of operation from the characteristics of the vehicle&#39;s occupant when they are deployed in case of vehicle impact. For example, a first state with a small volume to protect passengers located in a forward position and a second state with a higher volume to protect passengers located in a back position. 
     The WO 2006/006904 patent application describes an airbag module with a double loading generator that allows the damage to be reduced that is suffered by a potentially incorrectly positioned occupant, through an active device that determines (non) activation of the second generator load based upon the degree of tension of a strap located between two opposite parts of the bag. If during its deployment, the bag quickly reaches the occupant, the strap does not tighten, and therefore the second load is not activated and consequently the bag remains in the first state. Otherwise, the strap tightens, which causes the activation of the second load, which allows the bag to reach the second state. 
     The U.S. Pat. No. 6,808,205 patent describes an airbag module that incorporates a combination of fabric straps sewn at different locations of the bag, which allow a deployment that is differentiated into two states. 
     The U.S. Pat. No. 7,111,871 patent describes an airbag module for protecting the vehicle occupant in case of a front impact, where the mentioned two states are achieved with a dual loading generator and a two-volume bag. The first state is achieved by firing the first generator load, with which the bag deploys to a small volume, assisted by some moving straps inside the bag that hold it back. The second state is achieved by firing the two generator loads, with which the bag is filled completely. At the same time, the straps move by pressure, allowing the bag to be inflated to a large volume. The decision to fire one or both generator charges takes place on the basis of the values of pre-determined variables obtained through sensor devices. For example, this decision may be made depending on the seat&#39;s position, such that the small volume is deployed if the seat is in a more forward position and the large volume if the seat is in a halfway or back position. 
     Those airbag modules have the basic problem that the degree of adaptiveness to the occupant is limited, since only two states of bag filling are provided. In addition, one of them requires detection mechanisms of the occupant&#39;s position, which increases its complexity and cost. 
     Now, the automobile industry is constantly demanding airbag modules with more capacity to adapt to the size and position of the occupant, and this invention aims to satisfy that demand. 
     SUMMARY OF THE INVENTION 
     One purpose of this invention is to provide an airbag module for an automobile capable of adapting to different positions and sizes of the occupant. Each size, occupant&#39;s position and type of impact, need a specific solution, the present invention allowing to provide a unique product adapted to each particular case. 
     Another purpose of this invention is to provide an airbag module for an automobile capable of achieving two or more bag deployment volumes, getting different energy absorptions during the occupant&#39;s load. 
     Another purpose of this invention is to provide an airbag module for an automobile that has a self-adaptive compartment based upon the position and size of the occupant without the need for any detection mechanism of these factors. 
     Another purpose of this invention is to provide an airbag module for an automobile that allows it to absorb the tolerances of other passive safety systems that may involve changes to the anticipated position of the occupant. Among those systems it is worth mentioning the single frame programmed deformation, the seats, the seatbelts and the collapsible steering columns that may cause variations in the position of the occupant within a given adjustment range. 
     That and other purposes are achieved by providing an airbag module to protect the automobile occupant, which includes an inflatable bag from the gas that is produced by a generator when a dangerous situation to the occupant is detected, which includes a number of internal straps with different lengths and with each having a predetermined resistance to traction, which are joined at their ends to two areas of the bag, limiting its deployment in the direction of the occupant. The length and resistance to traction of these straps are calibrated so that they break in succession during the deployment of the bag until it reaches the occupant. 
     In one execution of the invention, the bag is configured to protect the occupant from a front impact. Thus a self-adaptive airbag module is achieved for the driver or passenger. 
     In another execution of the invention, the bag is configured to protect the occupant from a side impact. Thus a self-adaptive side airbag module is achieved. 
     In another execution of the invention, straps are used with a weakened section for better control of the energy dissipated during their breaking. Thus an improved self-adaptive airbag module is achieved. 
     Other characteristics and advantages of this invention will be highlighted in the detailed description that follows, which is for the purpose of illustration but not limitation, regarding its purpose in relation to the accompanying drawings. 
    
    
     
       DESCRIPTION OF THE FIGURES 
         FIGS. 1   a ,  1   b  and  1   c  are schematic views of the deployment of the bag from an airbag module according to this invention. 
         FIGS. 2   a  and  2   b  are perspective views of the deployment of the bag from a driver&#39;s airbag module according to this invention. 
         FIG. 3  is a plan view of a strap section used in an airbag module according to this invention, with two measurements to predetermine the location where it will break during the bag deployment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Following the execution illustrated in  FIGS. 1   a ,  1   b  and  1   c , it can be seen that bag  11  of an airbag module according to this invention, incorporates three straps  15 ,  17  and  19  of different lengths, which are fixed on two areas  21  and  23  of the same bag, through fabric seams of variable configuration, a pressure-temperature setting or any other type of setting that is appropriate. 
     As shown in  FIG. 1   a , the bag ( 11 ) is formed by an upper panel ( 41 ) and a lower panel ( 42 ) joined through a peripheral seam  20 . In one aspect of the invention the bag ( 11 ) is configured to deploy from the front, with the upper panel ( 41 ) contacting the occupant upon deployment; one of the joined areas ( 21  and  23 ) of the internal straps ( 15 ,  17 , and  19 ) to the bag ( 11 ) is located on the upper panel ( 41 ), and the other area is located on the lower panel ( 42 ). Accordingly, references to the upper and lower panels of the airbag ( 11 ) have been marked as  41  and  42 , respectively. It is noted that reference numerals  41  and  42  may also refer to front or back panels of the airbag ( 11 ), depending on the position of the airbag ( 11 ). See, e.g.,  FIG. 2   a  (discussed in further detail below). 
     The other components of the airbag module are conventional, and it is therefore not necessary to represent them in said Figures. 
       FIG. 1   a  shows a first state of bag  11  deployment, where its volume is limited by strap  15  with the smallest length, which is stretched at its ends as a result of the internal pressure of bag  11  exercised by the gas provided by the generator. The other straps  17  and  19 , which are longer, are not under tension in this first state. 
       FIG. 1   b  shows a second state of bag  11  deployment, where after breaking strap  15  with the smallest length, its volume is limited by strap  17  with an intermediate length, which is stretched at its ends. Strap  19 , with the longest length, is not under tension in this second state. 
       FIG. 1   c  shows a third state of bag  11  deployment, where after breaking strap  17  with the intermediate length, its volume is limited by strap  19  with a longer length. 
     If during bag  11  deployment, it had reached the occupant before the tearing away of straps  15 ,  17  and  19 , their tearing away would logically not occur, since those straps can be only be stretched as long as bag  11  does not reach the occupant. 
     The number of straps  15 ,  17  and  19 , the location of their setting areas  21  and  23  to bag  11 , as well as their geometry and mechanical properties, are the variables to be taken into consideration in order to predetermine the self-adaptive behaviour of the bag of the airbag module in question. 
     An important characteristic of this invention is that the tearing away of straps  15 ,  17  and  19  must take place in a direction that is sensitively perpendicular to the traction force exercised by the gas pressure, and therefore without substantially modifying their length when breaking. 
     Another important characteristic of this invention is that the tearing away of straps  15 ,  17  and  19  constitutes an energy absorption mechanism that positively contributes to the self-adaptive behaviour of the bag. 
     Another important characteristic of this invention is that the airbag module, as per its invention, can be an airbag module for a front, oblique or side collision. 
       FIGS. 2   a  and  2   b  illustrate the deployment of a driver airbag module, and the limitation of bag deployment in the direction of the occupant can be observed, which is provided by straps  15 ,  17  and  19 . 
     This invention is also applicable to passenger and side airbag modules. Upon viewing  FIGS. 2   a  and  2   b , an expert in this area will easily understand the application of the invention to these types of airbag modules. In the case that the bag of the airbag modules is formed by two panels, one of the joined areas of straps  15 ,  17  and  19  will preferably be located in each of them. 
     In a preferable execution of the invention, fabric straps  15 ,  17  and  19  with appropriate mechanical characteristics are used, in particular the dtex No. and the direction of the warp and weft. 
     In a preferable execution of the invention, rectangular straps  15 ,  17  and  19  are used. 
     In another preferred execution, straps  15 ,  17  and  19  include a section  31 , shown in  FIG. 3 , rectangular and width A with two measurements  33  and  35  of a triangular shape and depth of P, with axes displaced at a distance D, determining a reduced width area R on the straps. The proper selection of the sizes mentioned in that section  31  allows the energy dissipated by straps  15 ,  17  and  19  to be controlled during their breaking. 
     In a specific example of execution of the invention, 3 straps measuring 400, 450 and 500 mm in length and 100 mm in width will be used, each of them with two measurements  33  and  35  of a triangular shape and depth of 30 mm, with axes displaced at a distance of 80 mm. 
     In another preferable execution of the invention straps  15 ,  17 ,  19  are used formed by two pieces joined by seams with determined characteristics of type of seam, type of thread and stitch density that allow predetermining their tensile strength and controlling the dissipated energy of the straps  15 ,  17 ,  19  during their breakage. 
     In a preferable execution of the invention, straps  15 ,  17  and  19  with the same characteristics are used, except for their length. Thus, its resistance to traction will be the same and it will be selected based upon the change in the planned traction force during the deployment of bag  11 . 
     The main advantage of this invention is that an airbag module is achieved that behaves by self-adaptation, by deploying the required bag volume from the position and size of the occupant. 
     Another advantage of this invention is that OOP (“Out of Position”) behaviour of the airbag module is improved, since the breaking of the straps contributes to the absorption of the energy from the bag deployment, reducing damage to the occupant. 
     Another advantage of this invention is that the straps incorporated into the bag allow the direction and guidance of its deployment to be improved. 
     Another advantage of this invention is that the straps incorporated into the bag optimise the contact surface with the occupant. 
     Another advantage of this invention is that it allows the bag filling volume to be controlled without the need for using dual state generators. 
     Although several executions of the invention have been described and represented, modifications included within the scope of the invention may be introduced, and the scope must not be considered as being limited to said execution, but rather to the contents of the following claims: