Abstract:
An inflatable cushion for use in an airbag module is provided. The inflatable cushion generally includes a primary inflatable chamber configured for deployment from the air bag module, the primary inflatable chamber having an inlet opening for receipt of an inflation gas and the primary inflatable chamber defines a first volume. A secondary inflatable chamber secured to the primary inflation chamber, the secondary inflatable chamber defining a second volume, the second volume being less than the first volume and the secondary inflatable chamber being in fluid communication with the primary inflatable chamber such that the inflation gas must travel through the primary inflatable chamber prior to reaching the secondary inflatable chamber.

Description:
BACKGROUND 
       [0001]    Exemplary embodiments of the present invention relate generally to airbags or inflatable cushions. More specifically, exemplary embodiments of the present invention relate to systems and methods for deploying a two-chamber inflatable cushion from an airbag module in a gas-efficient manner. 
         [0002]    Passenger side airbags or inflatable cushions have historically been designed as a single chamber cushion for restraining both the head and chest of a belted or unbelted occupant during a predetermined event. Because the head and chest of the occupant have different masses, each are restrained at different rates by a single chamber cushion. 
         [0003]    Accordingly, it is desirable to provide an inflatable cushion and/or system for providing an inflatable cushion capable of providing differing amounts of support or cushion reaction to various portions of a vehicle occupant while also reducing the amount of gas needed for deploying a passenger airbag. 
       SUMMARY OF THE INVENTION 
       [0004]    Thus in accordance with exemplary embodiments of the present invention there is provided an airbag module or system including a two-chamber inflatable cushion that operates in a gas-efficient manner. 
         [0005]    In one exemplary embodiment, an inflatable cushion for use in an airbag module is provided. The inflatable cushion generally includes a primary inflatable chamber configured for deployment from the air bag module, the primary inflatable chamber having an inlet opening for receipt of an inflation gas and the primary inflatable chamber defines a first volume. A secondary inflatable chamber is secured to the primary inflation chamber, the secondary inflatable chamber defining a second volume, the second volume being less than the first volume and the secondary inflatable chamber being in fluid communication with the primary inflatable chamber such that the inflation gas must travel through the primary inflatable chamber prior to reaching the secondary inflatable chamber. 
         [0006]    In another exemplary embodiment, an inflatable cushion for use in an air bag module is provided. The inflatable cushion comprising: a primary inflatable chamber configured for deployment from the air bag module, the primary inflatable chamber having an inlet opening for receipt of an inflation gas, the primary inflatable chamber defining a first volume; and a secondary inflatable chamber secured to the primary inflation chamber, the secondary inflatable chamber defining a second volume the second volume being less than the first volume, the secondary inflatable chamber receiving the inflation gas from the primary inflation chamber through a portion of the primary inflatable chamber that is surrounded by an inlet opening of the secondary inflatable chamber, the portion of the primary inflatable chamber being configured such that the inflation gas must travel into the primary inflatable chamber and create a first predetermined pressure in the primary chamber prior to the inflation gas passing through the portion and into the secondary inflatable chamber. 
         [0007]    In another exemplary embodiment, an airbag module is provided the airbag module comprising: a housing portion; an inflatable cushion for deployment from the housing portion, the inflatable cushion having a primary inflatable chamber configured for deployment from the air bag module, the primary inflatable chamber having an inlet opening for receipt of an inflation gas, the primary inflatable chamber defining a first volume; and a secondary inflatable chamber secured to the primary inflation chamber, the secondary inflatable chamber defining a second volume the second volume being less than the first volume, the secondary inflatable chamber receiving the inflation gas from the primary inflation chamber through a portion of the primary inflatable chamber that is surrounded by an inlet opening of the secondary inflatable chamber, the portion of the primary inflatable chamber being configured such that the inflation gas must travel into the primary inflatable chamber and create a first predetermined pressure in the primary chamber prior to the inflation gas passing through the portion and into the secondary inflatable chamber. The airbag module further comprising an inflator for providing the inflation gas. 
         [0008]    In still another exemplary embodiment, a method for deploying an inflatable cushion of an airbag module, the method comprising: inflating a primary inflatable chamber of the inflatable cushion with an inflating gas released from an inflator in fluid communication with the primary inflatable chamber, the primary inflatable chamber defining a first volume; and inflating a secondary inflatable chamber of the inflatable cushion by venting a portion of the inflating gas in the primary inflatable chamber into the secondary inflatable chamber after the primary inflatable chamber has been inflated to a predetermined pressure, the secondary inflatable chamber defining a second volume, the first volume being greater than the second volume. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  illustrates a portion of a vehicle interior with an airbag module in accordance with an exemplary embodiment of the present invention; 
           [0010]      FIG. 2  is a perspective view of a baseline or single chamber inflatable cushion; 
           [0011]      FIG. 3  is a perspective view of an inflatable cushion constructed in accordance with an exemplary embodiment of the present invention; 
           [0012]      FIG. 4  is a graph illustrating the plots of cushion pressure in the baseline cushion of  FIG. 2  and the chambers of the cushion illustrated in  FIG. 3  during a deployment event; 
           [0013]      FIG. 5  is a graph illustrating the plots of cushion volumes in the baseline cushion of  FIG. 2  and the chambers of the cushion illustrated in  FIG. 3  during a deployment event; 
           [0014]      FIG. 6  illustrates an occupant interacting with the baseline cushion of  FIG. 2 ; and 
           [0015]      FIG. 7  illustrates an occupant interacting with the multiple chamber cushion of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0016]    Exemplary embodiments of the present invention are directed to a passenger side airbag module (PAB) or an airbag system, and more particularly to an airbag system that includes a two-chamber inflatable cushion that operates in a gas-efficient manner wherein gas management is achieved through chambering and gas reuse. 
         [0017]    Referring now to  FIG. 1 , a portion of an interior of a vehicle  10  is illustrated. Within the interior compartment of vehicle  10  is seating structure  12  and an airbag module  14  disposed in a selected spatial relationship with respect to seating structure  12 . In one exemplary embodiment, the airbag module  14  comprises a housing  16 , an inflator  18 , and an inflatable cushion or airbag  20 . The airbag module  14  is positioned within vehicle  10  for deployment of inflatable cushion  20  towards the seating structure  12 . 
         [0018]    The housing  16  of the airbag module  14  is mounted to or mounted proximate to an instrument panel or interior surface of vehicle  10  by suitable means such as fasteners. Of course, the housing  16  is contemplated for mounting to other structures in the vehicle. The housing  16  is made of an easily molded or extruded rigid material such as plastic, steel, aluminum, etc. The housing  16  includes an opening or door (not shown) in which the inflatable cushion  20  is deployed outwardly from. Alternatively, the opening or door is located within a portion of the instrument panel covering the housing of the airbag module. As will be discussed in more detail, the inflatable cushion  20  deploys away from the airbag module  14  generally in the direction of arrow X as well as other directions and typically deploys towards seating structure  12 . During deployment, the door of the housing and/or the instrument panel is pushed away or moved in a manner such that inflatable cushion  20  has an unobstructed deployment. 
         [0019]    The inflator is secured to or within the confines of housing  16  by a suitable means such as a fastener. The inflator  18  operates to provide the inflatable cushion  20  with an inflating gas. In one exemplary embodiment, the inflator  18  includes an igniter (not shown) for initiating a rapid chemical reaction for generating primarily nitrogen gas to fill and deploy cushion  20 . It should be understood that other suitable inflating gases or gas generating materials can be used to fill and deploy cushion  20 . It should be further understood that known inflator technologies can be used in accordance with an exemplary embodiment of the present invention such as single stage inflators and dual stage inflators. 
         [0020]    A sensor or sensing-and-diagnostic module  22  is in signal communication with airbag module  14 , and more particularly, with inflator  18 . The sensing-and-diagnostic module  22  is adapted to detect an activation event wherein the occurrence of a threshold event will cause an activation signal  24  to be generated and received by the inflator  18 , thereby causing the inflator  18  to inflate or deploy the inflatable cushion  20 . The detection of the threshold event is determined by one or more sensors that are disposed about the vehicle  10  in accordance with known technologies. Thus, the activation signal  24  controls the activation of the airbag module  14 . 
         [0021]    In an exemplary embodiment, sensing-and-diagnostic module  22  comprises a microprocessor, microcontroller or other equivalent processing device capable of executing commands of computer readable data or program for executing a control algorithm that controls the operation of the airbag module  14 . In order to perform the prescribed functions and desired processing, as well as the computations therefore (e.g., the execution of fourier analysis algorithm(s), the control processes prescribed herein, and the like), the controller may include, but not be limited to, a processor(s), computer(s), memory, storage, register(s), timing, interrupt(s), communication interfaces, and input/output signal interfaces, as well as combinations comprising at least one of the foregoing. For example, the controller may include input signal filtering to enable accurate sampling and conversion or acquisitions of such signals from communications interfaces. As described above, exemplary embodiments of the present invention can be implemented through computer-implemented processes and apparatuses for practicing those processes. 
         [0022]    In addition, and in accordance with the alternative exemplary embodiments of the present invention, the sensing-and-diagnostic module can also be adapted to detect one or more conditions. 
         [0023]    For example, the sensing-and-diagnostic module can receive inputs from one or more sensors such as, but not limited to, a seat position sensor  26 , an optical scanner  28 , a load sensor  30 , a seat recline sensor  32 , a seat belt use detection sensor  34 , and a belt tensioning sensor (not shown). 
         [0024]      FIG. 2  illustrates a baseline or single chamber inflatable cushion  21 , which will be used for comparison purposes when discussing the multiple chamber cushion of exemplary embodiments of the present invention. Referring now to  FIG. 3 , the inflatable cushion  20  includes a first chamber or chest chamber or primary inflation chamber  40  and a second chamber or head chamber or secondary inflatable chamber  42  in fluid communication with the primary inflation chamber  40  when the same has been inflated to a predetermined pressure. In one non-limiting exemplary embodiment, the predetermined pressure is approximately 20 KPa. See the graph of  FIG. 4  at time  60 , wherein the pressure of the secondary inflatable chamber begins to increase. Of course, other pressures greater or less than the aforementioned value are considered to be within the scope of exemplary embodiments of the present invention.  FIG. 3  illustrates the inflatable cushion in a fully deployed state. The primary inflatable chamber  40  and secondary inflatable chamber  42  are designed to restrain a first region (e.g., chest) and a second region (e.g., head) of the occupant respectively. The inflatable cushion  20  is positioned to be in fluid communication with inflator  18  by an opening  44  in the primary inflatable chamber. More specifically, opening  44  provides fluid communication between inflator  18  and primary inflatable chamber  40 . Thus, a path  46  is defined between inflator  18  and primary inflatable chamber  40 , whereby the inflating gas generated by inflator  18  for deploying inflatable cushion  20  flows through a path generally in the direction of arrow Y. Preferably, the opening  44  is defined in a bottom surface of primary inflatable chamber  40  near inflator  18 . 
         [0025]    The primary inflatable chamber  40  and secondary inflatable chamber  42  are each formed from a fabric, such as a nylon fabric arranged into an inflatable bag. In one exemplary embodiment, the primary inflation chamber and/or the secondary inflation chamber further comprises small vent holes that allow the inflation gas to be slowly expelled from the bag as the occupant pushes against it. Other suitable known inflatable fabrics can be used to construct primary inflatable chamber  40  and secondary inflatable chamber  42  and should not be limited to the one described above. In one exemplary embodiment, the primary inflatable chamber  40  is designed to be less permeable than the secondary inflatable chamber  42 . This is accomplished by thinly coating the primary inflatable chamber  40  with coatings of compounds such as neoprene, silicones and the like that are generally utilized to provide low permeability. As such, the primary inflatable chamber  40  exhibits a low leak-down time. In other words, gas expels from the primary inflatable chamber  40  at a slower rate than from secondary inflatable chamber  42  with no coatings. Other suitable compounds for providing low permeability can be coated onto the primary inflatable chamber  40  and should not be limited to the compounds described above. 
         [0026]    In accordance with one non-limiting exemplary embodiment, the primary inflatable chamber  40  is designed to provide a volume of approximately eighty liters at full inflation or deployment and the secondary inflatable chamber  42  is designed to provide a volume of approximately fifteen liters at full inflation or deployment. The size of the primary inflatable chamber and secondary inflatable chamber in combination is relatively smaller than the size of a conventional single inflatable cushion which in average provides a volume of approximately  110  liters at full inflation or deployment. Thus, the primary inflatable chamber  40  is approximately twenty-seven percent smaller than the baseline cushion or conventional cushion, thereby requiring less gas to fill and then the gas is reused to inflate the secondary inflatable chamber. The primary inflatable chamber and secondary inflatable chamber can be of any combination of sizes depending on the application, preferably less than the size of a conventional single inflatable cushion, and should not be limited to the size combination described above. 
         [0027]    In accordance with one exemplary embodiment of the present invention, a portion  48  of the primary inflatable chamber is selectively located to correspond to an opening into the secondary inflatable chamber wherein the secondary inflatable chamber is secured to the primary inflatable chamber proximate to portion  48 , thereby forming inflatable cushion  20  as illustrated in  FIG. 3 . Portion  48  has a top face or exterior  50  and a bottom face or interior surface  52 . 
         [0028]    In accordance with an exemplary embodiment of the present invention portion  48  is formed from a fabric material (e.g. nylon or the like) and can be of any size depending on the opening of secondary inflatable chamber  42 . In one exemplary embodiment, portion  48  comprises the same material as the primary inflatable chamber however portion  48  is not coated as opposed to other surfaces of the primary inflatable chamber and thus portion  48  is more permeable than exterior surfaces of the primary inflatable chamber not located within the opening of the secondary inflatable chamber. 
         [0029]    In one non-limiting exemplary embodiment, other areas exclusive of portion  48  of the primary inflatable chamber are coated with a coating  51  or compounds such as neoprene, silicones and the like that are generally utilized to provide low permeability. Thus, during deployment, inflating gas from the primary inflatable chamber  40  will ultimately flow through portion  48  and into the secondary inflatable chamber  42 . Accordingly and since the portion  48  is uncoated the portion  48  is used to regulate the flow of inflation gases into the secondary inflation chamber until a predetermined or desired pressure is reached within the primary inflation chamber. For example, the non-limiting example of 20 KPa mentioned above is used to design the permeability of portion  48 . 
         [0030]    In one exemplary embodiment, the primary inflatable chamber is configured to hold the inflating gases until a predetermined pressure is reached within the primary inflatable chamber thereafter and as the pressure increases from the predetermined pressure the gas will then vent through portion  48  and inflate the secondary inflatable chamber. As such, gas flows from the primary inflatable chamber into the secondary inflatable chamber generally in the direction of arrow Z. Thus, gas required to fully inflate the primary inflatable chamber  40  is recycled to fully inflate the secondary inflatable chamber  42 . In other words, the gas needed to fill the secondary inflatable chamber  40  is vented from the primary inflatable chamber  40 . As such, the same gas supply is used twice for occupant restraint. This provides a gas-efficient way of deploying cushion  20 . 
         [0031]    In one alternative exemplary embodiment and as illustrated by the dashed lines in  FIG. 3 , a vent or a plurality of vents  60  is/are located on portion  48  to allow venting of inflation gases from the primary inflatable chamber into the secondary inflatable chamber wherein the vent opens when the pressure within the primary inflatable chamber exceeds a predetermined value. Again, a non-limiting example would be the 20 KPa mentioned above of course, other pressures are contemplated. Here the vents are positioned on portion  48 , which in this embodiment may be more permeable than other portions of the primary inflatable cushion or in another alternative exemplary embodiment, portion  48  will have the same permeability as other portions of the primary inflatable cushion. Of course, numerous configurations are contemplated to be within the scope of exemplary embodiments of the present invention as long as the desired flow rates are achieved at the desired pressures. In one non-limiting exemplary embodiment vent  60  is a petal vent comprising a plurality of petals or members  62  that cover an opening  64  in portion  48  and when the pressure in the primary inflatable chamber exceeds a predetermined level the petals or members unfurled or deploy to the configuration illustrated in  FIG. 3  and opening  64  is uncovered. In addition, and in yet another alternative exemplary embodiment and if the pressure in the secondary inflatable chamber  42  exceeds that of the primary inflatable chamber the petals or members  62  are configured to limit flow from the secondary inflatable chamber back into the primary inflatable chamber when the pressure in the secondary chamber is greater than the first chamber and the gas flow is in the opposite direction to arrow Z thereby limiting gas transfer from the secondary inflatable chamber to the primary inflatable chamber after the secondary chamber has been inflated. 
         [0032]    In yet another alternative exemplary embodiment, the primary inflatable chamber can also be configured to have a plurality or at least one vent  68  that allows some of the inflation gas of the primary inflatable chamber to be vented directly out from the chamber. Vent or vents  68  can be used in conjunction with vent  60  or the cushion may only have either one of vent  60  or  68 . Similarly and in yet another alternative embodiment, a vent or vents may be disposed in the secondary inflatable chamber thus, the pressure in the secondary or head chamber and the primary or chest chamber can be discretely controlled by the number size and type of vents or lack thereof selected for each of the chambers. 
         [0033]    The inflatable cushion having a two-chamber (primary inflatable chamber  40  and secondary inflatable chamber  42 ) design as described herein restrains the occupant with approximately forty percent less gas than a convention inflatable cushion. Thus, a single stage inflator instead of a dual stage inflator is employed in one exemplary embodiment, thus decreasing or minimizing the size, weight, and potentially the cost of the airbag module and restraint system. This reduction in gas usage helps meet low risk airbag requirements (e.g. unbelted FMVSS 208) as the total energy released in a deployment is reduced by approximately forty percent. 
         [0034]    In one exemplary embodiment, the pressure in the primary inflatable chamber  40  is controlled by the selection of the inflator output and the vent size to the secondary chamber, which in some embodiments is the area of portion  48  disposed between the two chambers. The pressure in the secondary inflatable chamber  42  is also controlled by the size and number of vents  68 , which are the vents defined by the nylon bag used to form primary inflatable chamber. This allows the chest and head pressures to be separately controlled for optimal restraint of the two body regions (chest and head). Vent sizes or the amount of vents of the primary inflatable chamber and the secondary inflatable chamber can be any size or number depending on the application. 
         [0035]    In one exemplary embodiment, the chamber peak pressure in the primary inflatable chamber  40  during deployment can reach approximately 67 KPa while the chamber peak pressure in the secondary inflatable chamber during deployment can reach approximately 56 KPa. A conventional single inflator typically reaches approximately 40 KPa in peak pressure in a conventional single chamber cushion as mentioned above. As such, the two-chamber design as described above has approximately a sixty-seven percent increase in peak pressure over the baseline cushion namely 16 KPa in the secondary and 27 KPa in the primary. Moreover, and as will be discussed below these higher peak pressures are also achieved by using approximately  40 % less inflation force than that which was required for the baseline cushion illustrated in attached Figures. 
         [0036]    For example,  FIG. 4  is a graph illustrating the plots of cushion pressure in the baseline cushion of  FIG. 2  and the chambers of the cushion illustrated in  FIG. 3  during a deployment event wherein the baseline plot is the cushion illustrated in  FIG. 2  and the plot of the New Chamber  1  is the primary inflatable cushion chamber and the plot of New Chamber  2  is the secondary inflatable cushion chamber of the inflatable cushion illustrated in  FIG. 3 . In addition,  FIG. 5  is a graph illustrating the plots of cushion volumes in the baseline cushion of  FIG. 2  and the chambers of the cushion illustrated in  FIG. 3  during a deployment event. In accordance with an exemplary embodiment of the present invention the inflatable cushion of an exemplary embodiment of the present invention achieves full deployment of both chambers while only using approximately 60% of the inflator output required to achieve the plot of the baseline inflatable cushion. 
         [0037]    Accordingly and by employing the two chamber design with a means for inflating the second chamber only after a predetermined pressure has been achieved in the primary inflatable cushion chamber an inflatable cushion with approximately 95 liters of volume (both chambers) is fully deployed using 60% of an inflation force required to fully deploy a 115 liter single chamber cushion. This is achieved by limiting fluid flow into the secondary inflatable chamber until a predetermined pressure has been achieved in the primary inflatable chamber as well as occupant interaction with the primary inflatable chamber, which forces the inflation gas from the primary inflatable chamber to the secondary inflatable chamber. Moreover, the peak pressure volumes of the primary inflatable chamber and the secondary inflatable chamber are greater than the peak pressure volume of the baseline cushion and these peak pressure volumes are achieved at approximately the same time from initial activation of the inflator inflating the inflatable cushion. 
         [0038]    The secondary inflatable chamber  42  increases in pressure more quickly as the occupant moves forward and displaces the primary inflatable chamber  40 . The chamber peak pressure of the primary inflatable chamber  40  and secondary inflatable chamber  42  can vary depending on any one or more of the design considerations described above (e.g. chamber size, vent size, etc.). 
         [0039]    In accordance with an exemplary embodiment of the present invention, an exemplary method of restraining a first region and a second region of an occupant  90  in a vehicle is provided. In this exemplary method, sensing-and-diagnostic module  22  detects a threshold event. This causes sensing-and-diagnostic module  22  to generate activation signal  24  to the inflator  18 . Next, inflator  18  provides an inflating gas to the primary inflatable chamber  40  to fully inflate or deploy primary inflatable chamber  40  to be in a position to restrain the first region (e.g. chest) of the occupant. Then, the inflating gas from the primary inflatable chamber  40  flows through the portion  48  and into secondary inflatable chamber  42  to fully inflate or deploy secondary inflatable chamber  42  and be in a position to restrain the second region (e.g. head) of the occupant. 
         [0040]    During occupant interaction and as the occupant moves against the primary inflatable chamber  40 , the secondary inflatable chamber  42  increases in pressure more quickly, thus causing the secondary inflatable chamber  42  to fill faster. Finally, the inflating gas in the primary inflatable chamber leaks through the vents defined by the nylon bag used to form primary inflatable chamber and the gas vents into the vehicle or atmosphere. 
         [0041]    For example,  FIG. 6  illustrates an occupant interacting with the baseline cushion of  FIG. 2  while  FIG. 7  illustrates an occupant interacting with the multiple chamber cushion of  FIG. 3 . 
         [0042]    In accordance with an exemplary embodiment of the present invention and for purposes of comparison, the baseline cushion has a total volume of 110 liters while the combined volume of the cushion of an exemplary embodiment has a total volume of 95 liters (80 primary and 15 secondary). Moreover, the pressure in the single chamber of the baseline cushion only reaches 40 KPa at full output while the primary chamber reaches 67 KPa and the secondary reaches 56 KPa at only 60% output of the same inflator. Accordingly, a gas efficient cushion design is provided. 
         [0043]    While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the present application.