Abstract:
An air bag module including a cushion, a diffuser and an inflator is provided. The cushion is expandable radially and rearward of the air bag module. The diffuser is disposed in the cushion and is also expandable radially and rearward of the air bag module. The diffuser includes a vent in fluid communication with the cushion. The inflator generates an inflator gas exhaustible into the diffuser to deploy the cushion. The inflation gas is receivable by the diffuser for expanding the cushion and the diffuser to a first predetermined position. The vent is positioned downstream of the interior surfaces when the diffuser is at the first predetermined position. The inflation gas is diffusible by the diffuser through the vent to radially expand the cushion after the rearward expansion to the first predetermined position. The cushion is further expandable rearward to a second predetermined position after the radial expansion of the cushion.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims benefit of provisional application Serial No. 60/229,431 filed on Aug. 31, 2000, the contents of which are incorporated herein in their entirety. 
    
    
     TECHNICAL FIELD 
     This application relates generally to air bags for vehicles. More specifically, this application relates to a diffuser for diffusing inflator gas during deployment of an air bag. 
     BACKGROUND 
     Air bags have become common in modern automobiles. An air bag module including an inflatable cushion and an inflator is installed in the desired position within the vehicle. The cushion is stored in a folded position within the air bag module. In response to a threshold event or occurrence, a sensor provides a signal for activating the inflator. The inflator provides a supply of inflating gas to the cushion to inflate the cushion. 
     There are several types of inflators for air bag modules. One type is the pure gas inflator wherein a pressure vessel contains stored pressurized gas. The pressure vessel communicates with the cushion through various types of rupturable outlets or diaphragms. Another type is the gas generator wherein a propellant is ignited and the resultant gas flow through an outlet to the cushion. A third type is the hybrid or augmented type. This type includes a pressure vessel containing stored pressurized gas and a gas generator. When the generator is ignited, the resultant gas flows with the stored gas to the cushion through the pressure vessel outlet. 
     Tethers within the cushion have been used to limit the rearward excursion and biasing of the air bag cushion. As used in this application, rearward excursion is expansion of the air bag cushion inboard of the vehicle in a centralized manner and biasing is for the expansion of the cushion off center or in a particular direction. Thus, tethers provide for reduction or set a limit for rearward excursion and provide for a reduction or limit in the biasing of the cushion. 
     SUMMARY 
     An air bag module including an inflator, a cushion, and a flexible diffuser is provided. The inflator generates an inflator gas for deploying the cushion. The flexible diffuser is folded to a generally parachute shape for diffusing the inflator gas during deployment of the cushion. 
     An air bag module including a cushion and a diffuser is provided. The cushion is expandable radially and rearward of the air bag module. Similarly, the diffuser is expandable radially and rearward of the air bag module and is disposed in the cushion. The diffuser includes at least one vent in fluid communication with the cushion. An inflation gas exhaustible into the diffuser deploys the cushion. The inflation gas expands the cushion and the diffuser rearward to a first predetermined distance. The vent is positioned downstream of the interior surfaces when the diffuser is at the first predetermined distance. The inflation gas is diffused by the diffuser through the vent to radially expand the cushion after the rearward expansion to the first predetermined distance. The cushion is further expandable rearward to a second predetermined distance after the radial expansion of the cushion. 
     A rectangular diffuser in an air bag cushion is provided. The rectangular diffuser includes a pair of minor edges, a pair of length-wise edges, and a fold. The fold approximately bisects the pair length-wise edges such that the pair of minor edges are adjacent one another. The fold forms a pair of sealed top corners at the fold and an opening at the minor edges. A curved seam is sewn at the pair of top corners. Vents are positioned in the diffuser downstream of the interior surfaces. 
     A box shaped diffuser in an air bag cushion is provided. The box shaped diffuser includes a flexible material having a first edge, a second edge, a third edge, a fourth edge and four corners. A vertical fold line approximately bisects the first edge and the second edge, forming left and right sections of each of the first and second edges. Similarly, a horizontal fold line approximately bisects the third edge and the fourth edge, forming upper and lower sections of each of the third and fourth edges. A diagonal fold at each of the four corners is sealed with a corner seam. An opening formed at the corner seams by sealing: (1) the left section and the right section of the first edge to one another with a first seam; (2) the left section and the right section of the second edge to one another with a second seam; (3) the upper section and the lower section of the third edge to one another with a third seam; and (4) the upper section and the lower section of the fourth edge to one another with a fourth seam. Vents are positioned in the diffuser downstream of the interior surfaces. 
     The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross sectional view of an air bag module installed in the dashboard of a vehicle; 
     FIG. 2 is a cross sectional view of a first embodiment of a diffuser showing a partially deployed cushion; 
     FIG. 3 is a cross sectional view of an alternate embodiment of a diffuser in a fully deployed cushion; 
     FIG. 4 is a top view of the diffuser of FIG. 3 in a raw or incomplete state; 
     FIG. 5 is a side view of the diffuser of FIG. 3 in a complete, folded state, illustrating an alternate venting embodiment; 
     FIG. 6 is a cross sectional view of another embodiment of a diffuser shown in a partially deployed cushion; 
     FIG. 7 is a top view of the diffuser of FIG. 6; 
     FIG. 8 is a cross sectional view of the diffuser of FIG. 6 showing a fully deployed cushion; 
     FIG. 9 is a top view of an embodiment of the diffuser prior in a raw, or incomplete state; 
     FIG. 10 is a first side view of the diffuser of FIG. 9 in a complete folded state; and 
     FIG. 11 is a second side view of the diffuser of FIG. 9 in a complete, folded state. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the Figures and particularly to FIG. 1, an air bag module  10  is illustrated. Module  10  includes an inflator  14  and an inflatable cushion  16  in a cavity defined in a dashboard or interior surface  18  of a vehicle (not shown). A sensor  12  is adapted to detect an activation event to provide an activation signal to inflator  14  or alternatively a sensing and diagnostic module for controlling the activation of the airbag module. Sensor  12  or a plurality of sensors are positioned to detect vehicle conditions and generate a signal to the inflator or sensing and diagnostic module. Cushion  16  is stored in a folded position in module  10  and is in fluid communication with inflator  14 . Thus upon activation of inflator  14 , cushion  16  is adapted to inflate. 
     Cushion  16  includes a diffuser  22 , shown in FIGS. 2-11, disposed in the cushion. Diffuser  22  is made of flexible material, preferably fabric, and is operatively positioned in cushion  16  between the cushion and inflator  14  such that inflation gases  24  exhausted from the inflator enter the diffuser. Diffuser  22  creates a parachute effect for inflation gas  24  within cushion  16 . Namely, upon actuation of inflator  14 , gas  24  enters diffuser  22  causing the diffuser and cushion  16  to expand rearward and radially as shown in FIG.  2 . Radial expansion of cushion  16  is created by the flow of gas  24  through a plurality of vents  26 . The expansion of cushion  16  is radially limited by the size of the cushion, and initially limited rearward by the size of diffuser  22 . 
     Thus, once cushion  16  is radially expanded, gas  24  causes the cushion to expand rearward to its outer limit, shown in FIG.  3 . Here, diffuser  22  creates its parachute effect by initially capturing gas  24  such that the diffuser is fully expanded rearward, while cushion  16  is only partially expanded rearward. Gas  24  is vented through vents  26  to radially expand cushion  16 . After radial expansion of cushion  16 , the cushion is expanded rearward to its outer limit. 
     The parachute effect described above will reduce or set a limit for rearward excursion and biasing of cushion  16  during deployment. The parachute effect also provides for quick radial coverage of interior surfaces, and provides a thermal barrier for cushion  16  from heat in gas  24 . 
     In an alternate embodiment, diffuser  22  is releasably connected to cushion  16  by breakaway stitching  28 . Breakaway stitching is adapted to secure cushion  16  and diffuser  22  such that the stitching allows for complete expansion of the cushion rearward after the cushion is radially expanded. Thus, stitching  28  aids diffuser  22  in setting a limit for or reducing rearward excursion of cushion  16  until the cushion is radially expanded. 
     Diffuser  22 , illustrated in FIGS. 2-5, is a rectangular diffuser  30 . A preferred embodiment of rectangular diffuser  30  is shown in a raw or incomplete state in FIG.  4  and in a complete state in FIG.  5 . Shown in FIG. 4, rectangular diffuser  30  has minor edges  32  and length-wise edges  34 . Optionally, length-wise edges  34  are folded over to provide strength for seams to be discussed below. Rectangular diffuser  30  is folded along axis  36  such that minor edges  32  are adjacent one another, shown in FIG.  5 . Axis  36  bisects length-wise edges  34  about halfway of the length of the lengthwise edges. For purposes of clarity, folding axes are shown as single dotted lines, while seams are shown as double dotted lines. 
     A quarter-circular seam  38  is sewn or otherwise provided (hereinafter sewn) at the corners on either end of axis  36 . Rectangular diffuser  30  includes vents  26  provided in sufficient number so as to allow cushion  16  to expand and are positioned such that the vents are past dashboard  18  when the diffuser is expanded rearward to its outer limit. Vents  26  enable gas  24  to radially expand cushion  16  downstream of dashboard  18 . Thus, rectangular diffuser  30  has its top end sealed by fold axis  36 , its top corners sealed at seams  38 , and vents  26 , which all cooperate to provide the diffuser with the parachute effect described above. Moreover, rectangular diffuser  30  has its bottom end at minor edges  32  open to receive gas  24  from inflator  14 . 
     In an alternate embodiment, a horizontal seam  40  is sewn on a bottom portion of each length-wise edge  34 . Horizontal seams  40  are adapted to provide vents  26  with greater flow restriction capabilities, if needed. 
     Rectangular diffuser  30  illustrated in FIGS. 4 and 5 includes horizontal seams  40  restricting vents  26  and includes circular vents  26  disposed therein. In contrast, rectangular diffuser  30  illustrated in FIG. 2 has no horizontal seams restricting vents  26  and includes no circular vents  26 , while the rectangular diffuser illustrated in FIG. 3 has no horizontal seams restricting vents  26  but does include circular vents  26 . Of course, and as applications require other vents  26  disposed in rectangular diffuser  30  are considered within the scope of the present invention. 
     In use, inflator  14  is operatively positioned at the open end  32  of rectangular diffuser  30  such that the inflator is adapted to exhaust gas  24  into the diffuser. Rectangular diffuser  30  is operatively positioned in cushion  16  between the cushion and inflator  14  such that inflation gases  24  exhausted from the inflator enter the diffuser. Upon deployment of inflator  14 , gas  24  enters rectangular diffuser  30  at open ends  32  and acts on sealed fold axis  36  causing the diffuser and the cushion to expand rearward past dashboard  18 . Gas  24  is diffused, channeled or dispersed (hereinafter diffused) by curved seams  38  away from axis  36  toward vents  26 . Radial expansion of cushion  16  is created by the flow of gas  24  through vents  26 . Once cushion  16  is radially expanded, gas  24  causes the cushion to expand rearward to its outer limit. Thus, rectangular diffuser  30  creates the parachute effect described above. 
     In the embodiment of FIG. 2, rectangular diffuser  30  is releasably connected to cushion  16  along axis  36  by breakaway stitching  28 . Breakaway stitching  28  is adapted to secure cushion  16  and rectangular diffuser  30  such that the stitching allows for complete rearward expansion of the cushion after the cushion is radially expanded. 
     An alternate exemplary embodiment of diffuser  22  is illustrated in FIGS. 6 through 11 as a box-shaped diffuser  42 . Box shaped diffuser  42  is shown in a complete state in FIGS. 6-8 and in a raw or incomplete state in FIGS. 9-11. Diffuser  42  has edges  44 ,  46 ,  48  and  50  and a fold line along axis  52  and along axis  54 . Axes  52 ,  54  bisect edges  44 ,  46 ,  48  and  50  to form first and second sections of each edge, shown as sections  56 ,  58 ,  60 ,  62 ,  64 ,  66 , and  68 ,  70 , respectively. Axes  52 ,  54  bisect edges  44 ,  46 ,  48 , and  50  about halfway of the length of the edges. For purposes of clarity, folding axes are shown as single dotted lines, while seams are shown as double dotted lines. 
     The corners of diffuser  42  are folded over diagonally and a seam  72  is sewn over the folded corners, as shown in FIG.  9 . An opening  74  is formed at seams  72  by sealing the first and second sections of each edge to one another, namely  56  to  58 ,  60  to  62 ,  64  to  66 , and  68  to  70 . 
     In order to form opening  74 , diffuser  42  is folded in half along axis  52  such that edge  44  and edge  48  are adjacent one another, shown in FIGS. 10 and 11. Edge  50  is sewn with a seam  76  such that section  70  and section  68  are sealed to one another. Similarly, edge  46  is sewn with another seam  76  such that section  62  and  60  are sealed to one another. Next, edge  44  is pulled away from edge  48  folding the edges  44 ,  48  along fold axis  54  such that section  56  is adjacent section  58  and section  64  is adjacent  66 . A seam  78  is sewn to seal section  56  and section  58 . Similarly, a seam  80  is sewn to seal section  64  and section  66 . Thus, box-shaped diffuser  42  appears as a box with opening  74  at corner seams  72 . 
     Diffuser  42  includes vents  26  provided in sufficient number so as to allow cushion  16  to expand rearward and are positioned such that when the diffuser is extended rearward to its outer limit, the vents are past dashboard  18 . Vents  26  enable gas  24  to radially expand cushion  16  downstream of dashboard  18 . Thus, diffuser  42  provides the parachute effect as a result of the cooperation of its top end being sealed by axes  52 ,  54 , ends  46 ,  50  being sealed at seams  76 , section  64  being sealed to section  66 , section  56  being sealed to  58 , and the placement of vents  26 . Moreover, diffuser  42  includes opening  74  adapted to receive gas  24  from inflator  14 . 
     In use, inflator  14  is operatively positioned at opening  74  of box-shaped diffuser  42  such that the inflator is adapted to exhaust gas  24  into the diffuser. Diffuser  42  is operatively positioned in cushion  16  between the cushion and inflator  14  such that inflation gases  24  exhausted from the inflator enter the diffuser. Upon deployment of inflator  14 , gas  24  enters diffuser  42  at opening  74  and acts on fold lines  52 ,  54 , and seams  76 ,  78 , and  80  causing the diffuser and the cushion to expand rearward past dashboard  18 . Gas  24  is diffused in box-shaped diffuser  42  toward vents  26 . Radial expansion of cushion  16  is created by the flow of gas  24  through vents  26 . Once cushion  16  is radially expanded, gas  24  causes the cushion to expand rearward to its outer limit. Thus, rectangular diffuser  22  creates the parachute effect described above. 
     In the embodiment of FIG. 6, box-shaped diffuser  42  is releasably connected to cushion  16  along fold axis  52  or  54  by breakaway stitching  28 . Breakaway stitching  28  is adapted to secure cushion  16  and diffuser  42  such that the stitching allows for complete rearward expansion of the cushion after the cushion is radially expanded. 
     It should be recognized that diffuser  22  is described above by way of example as rectangular diffuser  30  and box-shaped diffuser  42  and is not limited to such shapes. Rather, diffuser  22  of any shape configured to provide the parachute effect described above is considered within the scope of the present invention. Additionally, diffuser  22  is described above by way of example as mounted in a dashboard. However, it should be recognized that diffuser  22  is intended for use with air bags mounted not only in dashboards, but also mounted in other portions of the vehicle. 
     Diffuser  22  radially dissipates inflation gas  24  upon partial rearward deployment of cushion  16  prior to complete rearward deployment of the cushion. Radially dissipating gas  24  reduces rearward excursion and increases coverage of interior surfaces. Moreover, diffuser  22  reduces or sets a limit for the biasing of cushion  16 , thus, replacing other types of biasing controlling devices and/or means, such as tethers, canister diffusers, and the like. Diffuser  22  also provides a thermal barrier to deflect heat contained within gas  24  from cushion  16 . 
     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 appended claims.