TECHNICAL FIELD

[0001] The present disclosure relates to airbags having one or more vents.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The written disclosure herein describes illustrative embodiments that are non-limiting and non-exhaustive. Reference is made to certain of such illustrative embodiments that are depicted in the figures, in which:

[0003] FIG. 1 is a side elevation view of an embodiment of an airbag that is installed in a vehicle and is being inflated;

[0004] FIG. 2A is another side elevation view of the airbag of FIG. 1 at approximately the same stage of inflation shown in FIG. 1 , wherein FIG. 2 further shows a vehicle occupant prior to impact with the airbag;

[0005] FIG. 2B is another side elevation view of the airbag of FIG. 1 after the airbag has been fully inflated and after the vehicle occupant has impacted the airbag;

[0006] FIG. 3 is an illustrative plot depicting an area of a slit vent as a function of time during a deployment event;

[0007] FIG. 4 is a plan view of a portion of an embodiment of a panel of the airbag of FIG. 1 showing a close-up view of an embodiment of a slit vent;

[0008] FIG. 5A is a partial cross-sectional perspective view of the slit vent of FIG. 4 in a closed orientation;

[0009] FIG. 5B is a partial cross-sectional perspective view of the slit vent of FIG. 4 in an open or venting orientation;

[0010] FIG. 6A is an exterior plan view of a portion of another embodiment of a panel of another embodiment of an airbag showing a close-up view of another embodiment of a slit vent that includes a reinforcing patch;

[0011] FIG. 6B is an interior plan view of the portion of the panel of the airbag of FIG. 6A;

[0012] FIG. 6C is a partial cross-sectional perspective view of the slit vent of FIGS. 6A and 6B;

[0013] FIG. 7A is an exterior plan view of a portion of another embodiment of a panel of another embodiment of an airbag showing a close-up view of another embodiment of a slit vent that includes a reinforcing patch; [0014] FIG. 7B is an interior plan view of the portion of the panel of the airbag of FIG. 7A;

[0015] FIG. 8 is a plan view of a portion of another embodiment of a panel of another embodiment of an airbag showing a close-up view of another embodiment of a slit vent;

[0016] FIG. 9A is a partial cross-sectional perspective view of another embodiment of a slit vent in a closed orientation, wherein the slit vent includes an embodiment of a flap;

[0017] FIG. 9B is a side elevation view of an embodiment of an airbag that includes the slit vent of FIG. 9A in the closed orientation, wherein the airbag is in an intermediate stage of inflation;

[0018] FIG. 10A is a partial cross-sectional perspective view of the slit vent of FIG. 9A in an open or venting orientation;

[0019] FIG. 10B is a side elevation view of the airbag that includes the slit vent of FIG. 9A, wherein the airbag is in a later stage of inflation than that shown in FIG. 9B and the slit vent is in the open or venting orientation;

[0020] FIG. 1 1 is a side elevation view of a portion of another embodiment of an airbag having a slit vent that includes another embodiment of a flap, wherein the slit vent is shown in a closed orientation;

[0021] FIG. 12 is a side elevation view of a portion of another embodiment of an airbag having a slit vent that includes another embodiment of a flap, wherein the slit vent is shown in a closed orientation; and

[0022] FIG. 13 is a side elevation view of a portion of another embodiment of an airbag having a slit vent that includes another embodiment of a flap, wherein the slit vent is shown in a closed orientation.

DETAILED DESCRIPTION

[0023] It will be readily understood that the components of the embodiments as generally described and illustrated in the figures herein could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of various embodiments, as represented in the figures, is not intended to limit the scope of the present disclosure, but is merely representative of various embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated. [0024] The phrases "connected to" and "coupled to" are used in their ordinary sense, and are broad enough to refer to any suitable coupling or other form of interaction between two or more entities, including mechanical, fluid and thermal interaction. Two components may be coupled to each other even though they are not in direct contact with each other. The phrases "attached to" or "attached directly to" refer to interaction between two or more entities which are in direct contact with each other and/or are separated from each other and/or coupled to each other by a fastener of any suitable variety {e.g., mounting hardware, adhesive, stitching), regardless of whether the fastener extends through additional components. The phrase "fluid communication" is used in its ordinary sense, and is broad enough to refer to arrangements in which a fluid {e.g., a gas and/or a liquid) can flow from one element to another element when the elements are in fluid communication with each other.

[0025] Inflatable airbag systems are widely used to reduce or minimize occupant injury in a collision scenario. Airbag modules have been installed at various locations within a vehicle, including, but not limited to, the steering wheel, the instrument panel, within the side doors or side seats, adjacent to roof rail of the vehicle, in an overhead position, or at the knee or leg position. In the following disclosure, "airbag" generally refers to an inflatable front airbag, such as a passenger airbag, although the principles discussed may apply to other airbag types in other embodiments.

[0026] Front airbags are typically installed in the steering wheel and instrument panel of a vehicle. During installation, the airbags are rolled and/or folded, and may be retained in the packaged state behind a cover. During a collision event, an inflator is triggered, which rapidly fills the airbag with inflation gas. Thus, the airbag rapidly changes from a rolled and/or folded configuration (also referred to as a packaged configuration) to an expanded or deployed configuration. For example, the expanding airbag can open the cover {e.g., tear through a burst seam or open a door-like structure) so as to exit a housing. The inflator may be triggered by any suitable device or system, and the triggering may be in response to and/or influenced by one or more vehicle sensors.

[0027] Certain embodiments of airbag assemblies that are disclosed herein are particularly well suited for passenger airbags, although other airbag configurations are contemplated. In some embodiments, the airbags can include one or more passive vents that are configured to be in a closed or substantially closed orientation during early stages of airbag deployment and are capable of opening upon full inflation and/or vehicle occupant impact for purposes of venting. In some embodiments, a passive vent may be reinforced via stitching that permits the passive vent to stay in the closed orientation during early stages of the deployment and subsequently open due to stresses acting on the airbag, such as the impact of a vehicle occupant. Various embodiments can reduce the amount of inflation gas that is used during a deployment and/or can facilitate manufacture of the airbag. One or more of the foregoing advantages and/or other advantages of various embodiments will be apparent from the disclosure that follows.

[0028] FIG. 1 depicts an airbag 100 that has been mounted within a vehicle 50. The airbag 100 is shown during an intermediate stage of deployment, such that the airbag is not yet fully inflated. The airbag 100 is shown protruding from a dashboard 52, and a forward portion thereof is in contact with a windshield 54 of the vehicle.

[0029] The airbag 100 includes a side panel 1 10, a front panel 1 12, and a rear panel 1 14 that cooperate to define an inflatable chamber 1 18. The airbag 100 may also include another side panel positioned opposite the side panel 1 10, which is not shown in FIG. 1 . In other embodiments, more or fewer panels may be used to form the airbag 100. In the illustrated embodiment, the rear panel 1 14, when the airbag 100 is in the deployed and inflated configuration, is generally directed toward an occupant or an occupant position (e.g., a vehicle seat), and may at least partially define a cabin side of the airbag 100. The side panel 1 10 may be generally orthogonal to the rear face 1 14, in some embodiments. The various panels 1 10, 1 12, 1 14 may also be referred to as airbag cushion membranes, and may be formed of any suitable material . For example, in some embodiments, the panels 1 10, 1 12, 1 14 are formed of a woven nylon fabric. Moreover, a variety of types and configurations of airbag cushion membranes can be utilized in various embodiments. For example, the size, shape, and proportions of the cushion membrane may vary according to its use in different vehicles or different locations within a vehicle.

[0030] In the illustrated embodiment, the side panel 1 10 includes a passive vent 120, which may also be referred to as a slit vent 120. As described further below, the slit vent 120 can include a slit or elongated aperture 122 that can be configured to be in a closed configuration during early stages of the deployment of the airbag 100, and can further be configured to transition to an open configuration to permit venting of inflation gases from the inflatable chamber 1 18, depending on inflation conditions. One or more slit vents 120 can be positioned in any suitable orientation on the airbag 100. As further discussed below, the orientation of the slit vent 120 can influence its operational characteristics. In the illustrated embodiment, the airbag 100 includes two slit vents 120: one at the side panel 1 10 and another at the side panel (not shown) that is opposite the side panel 1 10. The slit vents 120 can be oriented substantially identically relative to each other in some embodiments (e.g. at the same height, depth, and rotational orientation). In other embodiments, the slit vents 120 can have different relative orientations, and each slit vent 120 may operate differently from the other.

[0031] The term "passive vent" is intended to distinguish the slit vent 120 from active systems that employ sensors or other electrical systems to sense or otherwise determine conditions relative to a vehicle occupant and/or the vehicle itself prior to, during, or after a collision event and actuate systems in response thereto. Rather, the slit vent 120 can be capable of automatically responding to passenger and/or vehicle conditions. For example, the slit vent 120 can be configured to transition to an open state in out-of-position (OOP) situations due to tensioning of various portions of the side panel 1 10 that result from a vehicle occupant being in close proximity to the airbag 100 as it is deployed, as discussed further below. In other or further situations, the slit vent 120 may be configured to automatically open to permit venting when the a properly positioned occupant makes contact with the airbag 100 and/or when pressure from inflation gases builds within the airbag 100 after the airbag has been fully or nearly fully inflated.

[0032] The airbag 100 can include an inflation gas inlet 132 of any suitable variety. The inflation gas inlet 132 can be coupled with an inflator for introducing inflation gases into the inflatable chamber 1 18. In the illustrated embodiment, the inflation gas inlet 132 comprises a mouth region of a throat 130 that extends from a main body of the airbag 100. The inflation gas inlet 132 can define a central axis 133, which in some embodiments may be a centrally positioned line that is normal to a plane defined by a perimeter of the inflation gas inlet. In some embodiments, the central axis 133 can be oriented in a direction that generally corresponds with a direction in which inflation gases are introduced into the inflatable chamber 1 18 and/or a direction in which the airbag 100 is initially deployed; this is shown in FIG. 1 via an arrow that is collinear with the central axis 133. [0033] In the illustrated embodiment, the central axis 133 passes through a center of the throat 130. Additionally, in the illustrated embodiment, the deployment direction is only slightly angled toward the windshield 54. In other embodiments, the deployment direction may be steeper and more greatly angled toward the windshield 54. A portion of the airbag 100 may contact the windshield 54 at a reaction area that can aid in redirecting the general deployment direction of the airbag from that of the initial direction shown via the arrow to a more car rearward (e.g., toward the vehicle occupant) direction.

[0034] The orientation of the elongated aperture 122 of the slit vent 120 can be configured to permit the slit vent 120 to be in a closed orientation during at least initial deployment of the airbag 100 to prevent venting thereat. Stated otherwise, the slit vent 120 can be configured to substantially retain inflation gases within the inflatable chamber 1 18 during the initial stages of inflation. Orientation of the elongated aperture 122 relative to the initial and/or subsequent deployment directions of the airbag 100 can assist in maintaining the slit vent 120 in the closed orientation during at least the initial stages of inflation. For example, in the illustrated embodiment, the elongated aperture 122 is formed in the side panel 1 10, which can be substantially planar in the vicinity of the elongated aperture 122. Stated otherwise, opposing portions of the side panel 1 10 that define at least a portion of the elongated aperture 122 may be substantially planar when the airbag 100 is filled or partially filled with inflation gases, such as shown in FIG. 1 . The plane can be substantially parallel to the central axis 133 and/or the initial inflation direction of the airbag 100. Such an arrangement can reduce or minimize inflation gas forces that act on the elongated aperture 122 during inflation. For example, such an arrangement can prevent or reduce the amount of inflation gas flow having a component that is directed toward the elongated aperture 122, e.g., so as to impinge directly on the elongated aperture 122.

[0035] In other or further embodiments, relative angular orientations of the initial inflation direction of the airbag 100 and of the elongated aperture 122 can assist in maintaining the slit vent 120 in the closed orientation during at least the initial stages of inflation. For example, it may be desirable for stresses on the side panel 1 10 during inflation to be primarily in a longitudinal direction along which the elongated aperture 122 extends, or stated otherwise, along a longitudinal axis 139 defined by the aperture 122. Such stresses can tend to close the elongated aperture 122. Similarly, it may be desirable to reduce or minimize stresses on the side panel 1 10 during inflation in a transverse direction that is perpendicular to the longitudinal axis 139 (i.e., perpendicular to the elongated aperture 122), as such stresses can tend to open the aperture 122. Accordingly, in various embodiments, an angle a defined by the initial inflation direction (or the central axis 133 of the inflation gas inlet 132) relative to the horizontal can differ from an angle β defined by the longitudinal axis 139 of the aperture 122 by no greater than about ±15, ±30, or ±45 degrees. In some embodiments, the angles a and β can be the same. In some embodiments, the angle β can be smaller than the angle a (i.e., the difference between the angle a and the angle β can be a positive value), and may account for a change in the inflation direction that may occur after the airbag contacts the reaction area of the windshield. For example the inflation direction may become more car-rearward, or shallower, than the initial inflation direction.

[0036] FIG. 2A depicts the airbag 100 installed in the vehicle 50, and further illustrates a vehicle occupant 60 positioned within the vehicle 50. Unlike FIG. 1 , FIG. 2A further depicts an airbag housing 134 and an inflator 136 coupled with the airbag 100. In particular, the inflator 136 is coupled (at a minimum, is fluidly coupled) with the inflation gas inlet 132 so as to introduce inflation gas into the airbag 100. The airbag 100 is shown in an intermediate stage of deployment as it has not yet been filled to its full volume capacity by the inflation gases. As illustrated, the slit vent 120 is in the closed state such that inflation gases are inhibited (e.g., prevented or substantially prevented) from exiting the airbag 100 via the slit vent 120. As previously discussed, the slit vent 120 can be oriented on the side panel 1 10 in such a manner that stresses acting on the side panel 1 10 during initial inflation tend to keep the slit vent 120 in the closed configuration. In FIG. 2A, the head of the vehicle occupant 60 has not yet contacted the rear panel 1 14 of the airbag 100.

[0037] FIG. 2B depicts the airbag 100 at a later stage of inflation at which the volume of the airbag 100 has increased due to further filling by inflation gas and the head of the vehicle occupant 60 has impacted the rear panel 1 14. The slit vent 120 is in the open or venting state in this snapshot of the deployment event. The slit vent 120 can be opened due to the increased stresses on the side panel 1 10 that result from increased pressure within the airbag 100 due to additional introduction of inflation gas into the airbag 100 after the airbag 100 has reached its volume capacity and/or due to the stresses that are imparted to the side panel 1 10 as a result of the impact between the vehicle occupant 60 and the rear panel 1 14 and the subsequent ride down of the vehicle occupant 60.

[0038] In the configuration illustrated in FIGS. 2A and 2B, the vehicle occupant 60 was appropriately positioned during the deployment event, and the slit vent 120 did not open until the later stages of inflation. In other configurations, stresses can act on the slit vent 120 at earlier inflation stages to open the slit vent 120 for venting. For example, in some instances, the vehicle occupant 60 may be out of position, such as initially much closer to the inflating airbag 1 10. The closer proximity of the vehicle occupant 60 and earlier contact of the vehicle occupant with the rear panel 1 14 can provide stresses to the side panel 1 10 that tend to open the slit vent 120 and permit venting thereat, which can accommodate or reduce the risk of injury to the OOP vehicle occupant 60 due to deployment of the airbag 100.

[0039] FIG. 3 is an illustrative plot 90 depicting the area AVENT of the slit vent 120 as a function of time during different phases PH1 , PH2 of airbag deployment. In the illustrated embodiment, the first phase PH1 represents the filling stage of the airbag 100 prior to the vehicle occupant 60 impacting the airbag 100. The slit vent 120 can be in the closed state during the full first phase PH1 . When in the closed state, the slit vent 120 can inhibit inflation gas from exiting the airbag 100. The slit vent 120 may have some finite area that is open, such that a small amount of gas may exit the vent 120, and this small area may increase gradually as pressure from the inflation gas expands the airbag 100. However, the portions of the side panel 1 10 that define the aperture 122 may remain generally approximated to each other such that large amounts of inflation gas do not escape.

[0040] Upon impact by the vehicle occupant 60, which is depicted by the first vertical broken line, the area of the slit vent 120 can increase significantly to permit venting. This increase can result from the aperture 122 expanding in the transverse direction due to stresses acting on the side panel 1 10. The area may change somewhat over the remainder of the deployment event, such as by becoming larger during ride down of the vehicle occupant 60. In various embodiments, the average venting area in second phase PH2 can be greater than the average venting area in the first phase PH1 by no more than about 2, 4, 6, 8, 10, or 15 times or by no less than about 2, 4, 6, 8, 10, or 15 times. Other arrangements may yield plots that are different from the plot 90. For example, in some embodiments, the slit vent 120 may be closed more tightly during the initial inflation stage, such that the area at the left of the plot may be smaller.

[0041] FIG. 4 provides a close-up view of the side panel 1 10 of the airbag 100, and shows the slit vent 120 and the elongated aperture 122 in detail. The elongated aperture 122 extends from a first end 140 to a second end 142 in a longitudinal direction, which corresponds with the longitudinal axis 139. A first portion 176 of the side panel 1 10 that is shown to the left of the longitudinal axis 139 cooperates with a second portion 178 of the side panel 1 10 that is shown to the right of the longitudinal axis 139 to define the elongated aperture 122. One or more of the first and second ends 140, 142 of the elongated aperture 122 can include a cutout region 144, 146 to prevent stress risers in the side panel 1 10. In the illustrated embodiment, the cutout regions 144, 146 are circular. The cutout regions 144, 146 {e.g., the circles) have a diameter that is greater than any spacing between the more intermediate or centrally located regions of the first and second portions 176, 178 of the side panel 1 10 that define the portion of the elongated aperture 122 that extends between the first and second cutout regions 144, 146.

[0042] The elongated aperture 122, including the cutout regions 144, 146, can be formed in any suitable manner. For example, in various embodiments, the aperture 122 can be laser cut or die cut. In some embodiments, the elongated aperture 122 is angled relative to the warp yarns 1 13 and weft yarns 1 15 of the material from which the side panel 1 10 is formed. In other embodiments, the aperture 122 may extend parallel to either the warp or weft yarns 1 13, 1 15.

[0043] In some embodiments, the first and second portions 176, 178 of the side panel 1 10 abut one another in the region between the first and second cutout regions 144, 146. For example, in some embodiments, none of the panel material is removed in forming the aperture 122, other than in the cutout regions 144, 146. In other embodiments, there may be a small spacing between the first and second portions 176, 178 of the side panel 1 10 in the region between the first and second cutout regions 144, 146. For example, in some embodiments, a small amount of the panel material is removed in forming the aperture 122, such as by a laser beam having a finite width or a multi-blade die cutter. Accordingly, in some embodiments, the first and second portions 176, 178 of the side panel 1 10 can be approximated to each other so as to abut one another when the slit vent 120 is in the closed orientation, whereas in other embodiments, the first and second portions 176, 178 of the side panel can be approximated to each other, but not touch one another, when the slit vent 120 is in the closed orientation.

[0044] The region of the slit vent 120 can be reinforced by one or more reinforcing seams 150, 160. The reinforcing seams 150, 160 can reinforce the slit vent 120, such as to prevent tearing, fraying, splitting, or other undesirable weakening of the slit vent 120, such as during an inflation event. In various embodiments, the reinforcing seams 150, 160 can cooperate to fully encompass the elongated aperture 120. Such an arrangement can aid in preventing the formation of tears and, further, can prevent any tears that may form from propagating from an interior to an exterior of the seams 150, 160. The reinforcing seams 150, 160 may be of any suitable variety, and may be formed via stitching, one or more adhesives, taping, welding {e.g., radio frequency welding), heat sealing, or any other suitable technique or combination of techniques, and thus the reinforcing seams 150, 160 may comprise one or more of stitches, welds {e.g., radiofrequency welds), and/or adhesives. In some embodiments, each seam 150, 160 may comprise a single row of stitches. In other embodiments, each seam 150, 160 may include multiple rows of stitches. Such options for forming seams apply equally to other seams discussed herein. In the illustrated embodiment, each seam 150, 160 comprises two parallel rows of stitches 151 , 161 , respectively.

[0045] As further discussed below, the reinforcing seams 150, 160 can be configured to permit the slit vent 120 to naturally be in the closed orientation. For example, the reinforcing seams 150, 160, may provide no bias toward the open orientation. In some embodiments, the reinforcing seams 150, 160 may provide a bias toward the closed orientation.

[0046] The reinforcing seams 150, 160 can be elongated in the longitudinal direction. As used herein, the term "longitudinal direction" includes any direction extending along the longitudinal axis 139 and/or extending parallel to the longitudinal axis 139. In the illustrated embodiment, the first portion 176 of the side panel 1 10 includes a portion of the reinforcing seam 150 that extends alongside the aperture 122 from the first end 140 to the second end 142 thereof. In particular, in the illustrated embodiment, the portion of the reinforcing seam 150 that extends alongside the aperture 122 is parallel to the aperture 122. Similarly, the second portion 178 of the side panel 1 10 includes a portion of the reinforcing seam 160 that extends alongside the aperture 122 from the first end 140 to the second end 142 thereof. In particular, in the illustrated embodiment, the portion of the reinforcing seam 160 that extends alongside the aperture 122 is parallel to the aperture 122.

[0047] Each of the reinforcing seams 150, 160 includes redirection regions 154,

164 at the first end 140 of the elongated aperture 122 and redirection regions 155,

165 at the second end 142 of the elongated aperture 122. In the illustrated embodiment, the redirection regions 154, 155, 164, 165 are substantially rounded or arc-shaped. Stated otherwise, each redirection region 154, 155, 164, 165 defines a radius of curvature. In the illustrated embodiment, the radius of curvature of each redirection region 154, 155, 164, 165 is the same as that of the remaining redirection regions. In some embodiments, the radius of curvature can be small. For example, in an arrangement such as illustrated in FIG. 4, in some embodiments, a center point of the radius of curvature for one or both of the rows of stitches 151 of the seam 150 can be on the same side of the longitudinal axis 139 as the redirection regions 154, 155. The same can also be true for the radius of curvature for one or both of the rows of stitches 161 of the seam 160.

[0048] The redirection regions 154, 155, 164, 165 can angle the reinforcing seams 150, 160 relative to the longitudinal axis 139. In various embodiments, the angle provided at one or more of the redirection regions 154, 155, 164, 165 is no greater than 15, 30, 45, or 60 degrees. In various embodiments, the curves defined by the redirection regions 154, 155, 164, 165 can introduce stresses into the panel material. In some embodiments, larger angles can introduce greater amounts of stress to the panel 1 10. In various embodiments, the stresses introduced by the reinforcing seam 150 can fully offset the stresses introduced by the reinforcing seam 160 in at least the transverse direction. As a result, the slit vent may naturally remain in the closed configuration in the absence of stresses to the side panel 1 10 other than those provided by the reinforcing seams 150, 160.

[0049] The reinforcing seam 150 can extend from a first end 152 to a second end 153. The first and second ends 152, 153 may be referred to as free ends, as they are the terminal ends of the seam 150. In the illustrated embodiment, a majority of the reinforcing seam 150 extends along the first portion 176 of the side panel 1 10, whereas the first and second ends 152, 153 cross over the longitudinal axis 139 and terminate at the second portion 178 of the side panel 1 10. Similarly, the reinforcing seam 160 can extend from a first free end 162 to a second free end 163. In the illustrated embodiment, a majority of the reinforcing seam 160 extends along the second portion 178 of the side panel 1 10, whereas the first and second ends 162, 163 cross over the longitudinal axis 139 and terminate at the first portion 176 of the side panel 1 10.

[0050] The reinforcing seams 150, 160 can cross over one another at crossing regions 172, 174, which can be spaced from and longitudinally aligned with the first and second ends 140, 142 of the elongated aperture 122, respectively. The crossing regions 172, 174 can provide enhanced reinforcement to the panel material, as they include the overlapping of the seams 150, 160. Due to the stresses that arise as the elongated aperture 122 is moved from the closed orientation to the open orientation, should any splitting of the panel material occur, it may be highly likely to do so along the longitudinal axis 139. Accordingly, the crossing regions 172, 174 can provide enhanced protection from ripping or splitting of the panel material during a deployment event.

[0051] The reinforcing seams 150, 160 can be configured to reinforce the elongated aperture 122 without causing the aperture to open. For example, the reinforcing seams 150, 160 may, in some instances, introduce stresses into the panel material, such as when the reinforcing seams 150, 160 are formed of stitches. The stresses may be greatest in the redirection regions 154, 155, 164, 165. However, the reinforcing seams may permit the slit vent 120 to naturally remain in the closed configuration in the absence of any further stresses to the panel 1 10, such as the further stresses due to occupant impact with the airbag 100. For example, in some arrangements, a single continuous seam may be provided about the aperture 122 in a substantially oval shape. The stresses introduced to the panel 1 10 by such a stitching arrangement can cause the slit vent 120 to naturally be in the open position. Stated otherwise, the stresses of such an oval-shaped stitch can undesirably bias the slit vent 120 to an open position in the absence of other stresses acting on the panel 1 10. Seam arrangements such as that depicted in FIGS. 1 -4, in contrast, eliminate stresses that would naturally cause the slit vent 120 to be in the open position.

[0052] In the illustrated embodiment, the reinforcing seams 150, 160 are symmetrical about the longitudinal axis 139. In some instances, such symmetry can result in mirrored, countervailing, or oppositely directed stresses to cancel out each other in the transverse direction (e.g. in a direction perpendicular to the longitudinal axis 139). Furthermore, in some embodiments, the length of the redirection regions 154, 155, 164, 165 are relatively small, as compared with the length of the seams 150, 160 as a whole, such that only a small portion of the seams 150, 160 gives rise to stresses that might tend to bias the aperture 122 to the open orientation. In various embodiments, the a length of each redirection region 154, 155 is not greater than about 1/50, 1/40, 1/30, 1/20, or 1/10 of the total length of the reinforcement seam 150. In other or further embodiments, the a length of each redirection region 164, 165 is not greater than about 1/50, 1/40, 1/30, 1/20, or 1/10 of the total length of the reinforcement seam 160.

[0053] In the illustrated embodiment, the elongated aperture 122 defines a straight line. In other embodiments, the elongated aperture 122 defines a curved line, such as an arc of any suitable radius of curvature. In certain of such embodiments, portions of the reinforcements seams 150, 160 may extend alongside or adjacent to the elongated aperture 122 in a manner similar to that discussed above. The reinforcement seams 150, 160 may include regions that are parallel to the elongated aperture 122.

[0054] FIGS. 5A and 5B illustrate various stresses that can act on the side panel 1 10 during a deployment event, other than those that may be present due to the seams 150, 160. FIG. 5A depicts an early stage of inflation at which the slit vent 120 is closed, and can correspond with the arrangement shown in FIG. 2A. As indicated by four arrows, the stresses in the side panel 1 10 due to inflation gas can be primarily directed in the opposite directions along the longitudinal axis 139. The longitudinal forces can tend to keep the slit vent 120 in the closed orientation. Depending on the position of the slit vent 120, such as discussed above, these longitudinal forces can exceed forces or stressed in the transverse direction that would tend to open the slit vent 120.

[0055] FIG. 5B depicts a later stage of inflation, and can correspond with the arrangement shown in FIG. 2B. The stresses in the transverse direction can be greater than those in the longitudinal direction, and may open the slit vent 120 for venting of the airbag 100.

[0056] In various embodiments, airbags 100 having one or more of the features discussed above can reduce the size and weight of airbag modules and/or can reduce the cost of the airbag modules. For example, the airbag 100 can be more efficient, in that it can reduce the amount of inflation gas that is used during inflation, as compared with airbags that have vents that are open during the initial stages of airbag deployment (e.g., circular vents). This can result from a reduction or elimination of leakage of inflation gases from the airbag during at least the initial stages of inflation [e.g., prior to occupant loading of the airbag 100). Reducing the amount of inflation gases that are used in an inflation event can reduce system waste, system weight, energy use, and/or the envelope size of the airbag assembly. In various embodiments, the slit vent 120 does not open until the vehicle occupant 60 loads the airbag 100, thus all or substantially all of the inflation gas produced by the inflator is retained within the airbag 100 until load dampening is desired. The slit vent 120 can then open to cushion the vehicle occupant 60 upon initial impact and subsequent ride down. The slit vent 120 thus can be capable of altering its configuration in desirable manner, and can do so passively, or without complex mechanisms or devices.

[0057] FIGS. 6A-6C depict a portion of another embodiment of an inflatable airbag 200 that can resemble the inflatable airbag 100 described above in certain respects. Accordingly, like features are designated with like reference numerals, with the leading digits incremented to "2." Relevant disclosure set forth above regarding similarly identified features thus may not be repeated hereafter. Moreover, specific features of the airbag 200 may not be shown or identified by a reference numeral in the drawings or specifically discussed in the written description that follows. However, such features may clearly be the same, or substantially the same, as features depicted in other embodiments and/or described with respect to such embodiments. Accordingly, the relevant descriptions of such features apply equally to the features of the airbag 200. Any suitable combination of the features and variations of the same described with respect to the airbag 100 can be employed with the airbag 200, and vice versa. This pattern of disclosure applies equally to further embodiments depicted in subsequent figures and described hereafter, wherein the leading digits may be further incremented.

[0058] The airbag 200 can include a side panel 210 and a slit vent 220 that includes an elongated aperture 222. The airbag 200 can further include two overlapping reinforcement seams 250, 260 that encompass the elongated aperture 222. The elongated aperture 222 can be bordered on either side by first and second portions 276, 278 of the side panel 210.

[0059] The airbag 200 can further include a reinforcing panel, doubler, or reinforcing patch 280, which can provide further reinforcement of the slit vent 220. The reinforcing patch 280 can be attached to the side panel 210 via the reinforcing stitches 250, 260, whether at the exterior or interior of the airbag 100. The reinforcing patch 280 can be formed of any suitable material, such as, for example, a piece of fabric that is the same as the fabric from which the side panel 210 is constructed. In various embodiments, the reinforcing patch 280 can include a woven nylon material. In some embodiments, the reinforcing patch 280 may be stiffer than the material of which the side panel 210 is formed. In the illustrated embodiment, the reinforcing patch 280 is approximately the same thickness as the side panel 210 material, as shown in FIG. 6C, although other arrangements are possible. Additionally, in the illustrated embodiment, the reinforcing panel 280 substantially defines an oval. Other arrangements are also possible.

[0060] The reinforcing patch 280 can define at least a portion of the slit vent 220. For example, the reinforcing patch 280 can include an elongated aperture 280 that is aligned with and/or otherwise matches the shape and/or size of the elongated aperture 222 of the side panel 210. In the illustrated embodiment, a first portion 286 of the reinforcing patch 280 includes a portion of the reinforcing seam 150 that extends alongside the aperture 282. In particular, in the illustrated embodiment, the portion of the reinforcing seam 250 that extends alongside the aperture 282 is parallel to the aperture 282. Similarly, a second portion 288 of the reinforcing patch 280 includes a portion of the reinforcing seam 260 that extends alongside the aperture 282. In particular, in the illustrated embodiment, the portion of the reinforcing seam 260 that extends alongside the aperture 282 is parallel to the aperture 282.

[0061] FIGS. 7A-7B illustrate a portion of another embodiment of an airbag 300 that can include a reinforcing patch 380 that is attached to a side panel 310 via reinforcing stitches 350, 360. The reinforcing patch 380 can be larger than the reinforcing patch 280 discussed above such that its edges are spaced from an aperture 322 by a greater amount. An additional seam 390 can be used to further secure the reinforcing patch 380 to the side panel 310. In some embodiments, the seam 390 is sufficiently far from the aperture 320 and/or is otherwise arranged such that stresses provided thereby to the side panel 310 do not tend to bias the aperture 322 to the open orientation.

[0062] FIG. 8 illustrates another embodiment of an airbag 400 that includes a continuous reinforcing seam 491 that encompasses an elongated aperture 422. The reinforcing seam 491 can include portions 450, 460 that are analogous to the reinforcing seams 150, 160 discussed above. The portions 450, 460 are joined to each other at redirection regions 496, 498 at either longitudinal end of the reinforcing seam 491 . The large amount of rotation in the redirection regions 496, 498 can introduce relatively large stresses into the panel material. However, these stresses may not provide a bias to the opening of the aperture 422. This may result from the stresses being at positions that are longitudinally spaced from the aperture 422 and/or are symmetrical relative to a longitudinal axis of the aperture 422. In the illustrated embodiment, the reinforcing seam 491 includes two parallel rows of stitches 492, 494.

[0063] FIGS. 9A-10B illustrate another embodiment of an airbag 500 that includes a passive vent or slit vent 520 that resembles the slit vents described above in many respects. However, the slit vent 520 further includes a flap 581 . The flap 581 may also be referred to as a regulating flap or as a valve member in view of the manner in which it can operate to selectively obstruct gas flow through an aperture 522. As discussed further below, the flap 581 can be configured to prevent gas from flowing through at least a portion of the aperture 522 during early and/or intermediate stage of deployment and/or use of the airbag 500 (see FIG. 9B). When the aperture 522 is opened, however, a portion of the flap 581 can extend through the aperture 522 and permit inflation gases to exit through the aperture 522 (see FIG. 10B). The flap 581 can be formed of any suitable material. In some embodiments, the flap 581 may be configured to resist or prevent passage of gases through it. For example, in some embodiments, the flap 581 can be formed of a standard airbag material, and may be formed of the same material as other portions of the airbag 500.

[0064] With reference to FIGS. 9A and 9B, the aperture 522 can be defined by opposing first and second portions 576, 578 of a side panel 510. As with other embodiments described above, the side panel 510 can cooperate with other panels {e.g., a rear panel 514) to define an inflatable chamber 518. The aperture 522 can be bordered on either side by reinforcing seams 550, 560, which can maintain the aperture 522 in a closed configuration in the absence of other stresses on the airbag 500. The aperture 522 can be elongated between a first end 540 and a second end 542. In the illustrated embodiment, the aperture 522 defines a straight line between the first and second ends 540, 542 when the aperture 522 is closed, as shown in FIG. 9A, such that a distance between the first and second ends 540, 542 corresponds with a length of the closed aperture 522.

[0065] The flap 581 can be configured to obstruct at least a portion of the aperture 522. The flap 581 can have a width that is defined as the maximum distance in a direction collinear with or parallel to a longitudinal dimension of the aperture 522. For example, in the illustrated embodiment, the flap 581 includes two lateral edges 587, 589 that are substantially parallel to each other and that extend substantially transversely relative to a longitudinal direction of the flap 581 . The width of the illustrated embodiment is defined as the distance between the lateral edges 587, 589. In the illustrated embodiment, a width of the flap 581 is greater than the length of the closed aperture 522. Accordingly, when the aperture 522 is in the closed configuration, the flap 581 covers an entirety of the aperture 522. Thus, when the slit vent 520 is in the closed orientation, the flap obstructs an entirety of the aperture 522.

[0066] In other embodiments, the flap 581 covers only a portion of the aperture 522. For example, the lateral edges 587, 589 may be closer to each other such that the width of the flap 581 is smaller than the length of the aperture 522. The flap 581 may thus obstruct only a portion of the aperture 522 when the slit vent 520 is in the closed orientation. In some arrangements, the flap 581 may more easily be forced through the aperture 522 when the flap 581 defines a width that is smaller than the length of the aperture 522. In some arrangements, the width may be selected as a balancing of various deployment factors, such as the amount of obstruction provided thereby and the ease of passage through the aperture 522. In some arrangements, a relatively wider flap 581 can provide a greater amount of obstruction, but may not deploy through the aperture 522 as easily, whereas relatively thinner flaps 581 might readily pass through the aperture 522, but may not provide a desired amount of obstruction {e.g., may permit undesired amounts of inflation gas to pass around the lateral edges 587, 589 during early stages of airbag deployment).

[0067] In some instances, a shape of the flap 581 can also affect its deployment characteristics. For example, in the illustrated embodiment, the flap 581 is substantially square. That is, the width between the lateral edges 587, 589 is substantially the same as a distance between longitudinal edges 583a, 585a of the flap 581 . However, in other embodiments, the distance between the longitudinal edges 583a, 585a may be smaller. For example, the distance may be no greater than 30, 40, 50, 60, 70, 80, or 90 percent of the width of the flap 581 . In some arrangements, a smaller distance between the edges 583a, 585a can allow the flap 581 to more readily pass through the aperture 522 {e.g., to slide through the aperture 522 easily and/or to pass through the aperture 522 at earlier stages of airbag deployment). In other embodiments, the lateral edges 587, 589 and/or the longitudinal edge 583a may define other shapes that can affect ease of deployment. For example, in various embodiments, the edges 587, 589, 583a may define a substantially trapezoidal or semicircular shape that decreases in size with increasing distance from the longitudinal edge 585a. Such arrangements may, in some instances, deploy through the aperture 522 more easily than square arrangements having the same maximum distance between the longitudinal edges 583a, 585a.

[0068] The flap 581 can include a fixed end or attached end 585 and a free end or transitional end 583. The fixed end 585 can be attached to the side panel 510 in any suitable manner. In the illustrated embodiment, the fixed end 585 is attached to the side panel 510 via the seam 560 {e.g., via stitching). Specifically, only the portion of the seam 560 that is at the same side of the aperture 522 as the longitudinal edge 585a of the flap 581 and that passes between the lateral edges 587, 589 of the flap 581 attaches the flap 581 to the side panel 510. The remaining portions of the seam 560 and, in the illustrated, all portions of the seam 550 are separate from or are unattached to the flap 581 . Stated otherwise, the fixed end 585 of the flap 581 can be attached to the second portion 578 of the side panel 510 and the transitional end 583 of the flap can be unattached to the first portion 576 of the panel 510. The transitional end 583 of the flap 581 is free to move relative to the panel 510, and thus can be moved from the interior of the airbag 500 {e.g., from within the inflatable chamber 518) to the exterior of the airbag 500 during deployment of the airbag 500.

[0069] With reference to FIGS. 9A and 9B, operation of the flap during early stages of deployment of the airbag 500 will now be described. When the airbag 500 is in a packaged state, the flap 581 can be within the inflatable chamber 518. That is, an outwardly facing surface of the flap 581 can face an inwardly facing surface of each of the first and second portions 576, 578 of the side panel 510. Stated otherwise, the flap 581 can span at least a portion of the first and second portions 576, 578 of the side panel 510 and can obstruct at least a portion of the aperture 522. As the inflatable chamber 518 fills with inflation gas, the inflation gas can press the flap 581 against the inner surfaces of the first and second portions 576, 578 of the side panel 510. When thus pressed against the inner wall of the side panel 510, the transitional end 583 of the flap 581 may be said to be temporarily connected to the first portion 576 of the side panel 510. Accordingly, at this stage of inflation, both the transitional end 583 and the fixed end 585 of the flap 581 are attached, at least temporarily, to the side panel 510. In this orientation, the flap 581 may cover at least a portion of the aperture 522 that prevent inflation gas from passing through the aperture 522 wherever the flap 581 is present. Thus, as the airbag 500 inflates and as the slit vent 520 remains in the initial closed orientation, the flap 581 can serve to prevent gas leakage through the aperture 522 that might otherwise occur in the absence of the flap 581 . The flap 581 may be said to act as a valve or as a regulating device by selectively obstructing at least a portion of the aperture 522. As previously discussed, in the illustrated embodiment, the flap 581 obstructs an entirety of the aperture 522 during the inflation stage shown in FIG. 9B, whereas in other embodiments, the flap 581 may obstruct only a portion of the aperture 522.

[0070] With reference to FIGS. 10A and 10B, at a later stage of airbag deployment, the slit vent 520 may open due to one or more stresses acting thereon, such as those described above. For example, outwardly directed pressure from within the inflatable chamber 518 and/or other forces that tend to separate the first and second portions 576, 578 of the panel 510, such as those due to a vehicle occupant impacting the rear panel 514 of the airbag 500, can cause the first and second portions 576, 578 to separate from each other and open the aperture 522. As the aperture opens, inflation gas from within the airbag 500 can press against the flap 581 and push the transitional end 583 through the aperture 522 to an exterior of the airbag 500. The slit vent 520 thus can be said to transition to the open state in which the aperture 522 is open and the flap 581 no longer obstructs the aperture 522. Stated otherwise, the flap 581 can be moved from a first orientation in which the transitional end 583 is temporarily attached to the side panel 510 (e.g., via gas pressure) and in which the flap 581 reduces or prevents gas flow through the aperture 522 to a second orientation in which the transitional end 583 is unattached to the side panel 510 and the flap 581 permits gas flow through the aperture 522 by a greater amount than when the flap 581 is in the first orientation.

[0071] When the slit vent 520 is in the open orientation, the presence of the flap 581 may somewhat alter the opening size of the vent 520, as compared to embodiments in which the flap 581 is absent. The flap 581 may, in fact, slightly decrease the size of the opening through which inflation gases exit from the airbag 500, as compared with the aperture 522 alone. Nevertheless, this reduction of the opening size does not obstruct the egress of inflation gas via the aperture 522. Rather, the inflation gas passes by the flap 581 as it exits the airbag 500 - the flap 581 does not obstruct the gas flow when in this orientation.

[0072] FIG. 1 1 illustrates another embodiment of an airbag 600 that includes a passive vent or slit vent 620 that resembles the slit vents described above in many respects, particularly the slit vent 520. However, the slit vent 620 includes a flap 681 that differs from the flap 581 in that a fixed end 685 of the flap 681 is at an exterior of a side panel 610 of the airbag 600.

[0073] The flap 681 includes a transitional end 683 that is unattached to the side panel 610. In the illustrated embodiment, a seam 650 does not attach the transitional end 683 to the side panel 610. Stated otherwise, the seam 650 does not attach any portion of the flap 681 that is positioned at an interior of the airbag 600 to the side panel 610. In the illustrated embodiment, the fixed end 685 is attached to the side panel 610 via a seam 660. The flap 681 is unattached to a first portion 676 of the side panel 610 and is attached to a second portion 678 of the side panel 610 that cooperate to define an aperture 622. When the slit vent 620 is in the closed state shown in FIG. 1 1 , the flap 681 extends from an exterior of the airbag 600 to an interior of the airbag 600 through the aperture 622.

[0074] When the airbag 600 is in a packaged state, an outwardly facing surface of the transitional end 683 of the flap 681 (e.g., the internally positioned portion of the flap 681 ) faces an inwardly facing surface of the first portion 676 of the side panel 610, and an inwardly facing surface of the fixed end 685 of the flap 681 (e.g., the externally positioned portion of the flap) faces an outwardly facing surface of the second portion 678 of the side panel 610. As the airbag 600 fills with inflation gas, the inflation gas can press internal portion of the flap 681 against the inner surface of the first portion 676 of the side panel 610. The gas pressure can temporarily secure the internal portion of the flap 681 to the first portion 676 of the side panel 610. Moreover, the external portion of the flap 681 is permanently secured to the second portion 678 of the side panel 610. Accordingly, in some arrangements, the flap 681 can tend to keep the first and second portions 676, 678 in fixed relation relative to each other, which can prevent the aperture 622 from opening. [0075] Further, the flap 681 may also be said to cover at least a portion of the aperture 622 to prevent inflation gas from passing through the aperture 622. In particular, the portion of the flap 681 that extends through the aperture 622 can block and/or redirect gases that would otherwise exit the aperture 622 unimpeded. The external portion of the flap 681 can be positioned relatively tightly against the second portion 678 of the side panel 610. Accordingly, inflation gases that might otherwise escape through the aperture 622 (e.g., between the portion of the flap 681 that extends through the aperture 622 and the portion of the aperture 622 defined by the second portion 678 of the side panel 610), can be inhibited or prevented from doing so by the interaction of the fixed end 685 the flap 681 (e.g., the external portion of the flap) and second portion 678 of the side panel 610.

[0076] Thus, as the airbag 600 inflates and as the slit vent 620 remains in the initial closed orientation, the flap 681 can serve to prevent gas leakage through the aperture 622 that might otherwise occur in the absence of the flap 681 . The flap 681 may be said to act as a valve or as a regulating device by selectively obstructing at least a portion of the aperture 622. In manners such as discussed above with respect to the flap 581 , in the illustrated embodiment, the flap 681 obstructs an entirety of the aperture 622 during the inflation stage of the airbag 600, whereas in other embodiments, the flap 681 may obstruct only a portion of the aperture 622.

[0077] At a later stage of airbag deployment (such as the stage depicted in FIGS. 10A and 10B) the slit vent 620 may open due to one or more stresses acting thereon, such as those described above. For example, outwardly directed pressure from within the airbag 600 and/or other forces that tend to separate the first and second portions 676, 678 of the panel 610, such as those due to a vehicle occupant impacting the rear panel 614 of the airbag 610, can cause the first and second portions 676, 678 to separate from each other and open the aperture 622. As the aperture opens, inflation gas from within the airbag 600 can press against the flap 681 and push the transitional end 683 through the aperture 622 to an exterior of the airbag 600. The slit vent 620 thus can be said to transition to the open state in which the aperture 622 is open and the flap 681 no longer obstructs the aperture 622. Stated otherwise, the flap 681 can be moved from a first orientation in which the transitional end 683 is temporarily attached to the side panel 610 (e.g., via gas pressure) and in which the flap 681 reduces or prevents gas flow through the aperture 622 to a second orientation in which the transitional end 683 is unattached to the side panel 610 and the flap 681 permits gas flow through the aperture 622 by a greater amount than when the flap 681 is in the first orientation.

[0078] FIG. 12 illustrates another embodiment of an airbag 700 that includes a passive vent or slit vent 720 that resembles the slit vents described above in many respects, particularly the slit vents 520, 620. However, the slit vent 720 includes a flap 781 that differs from the flap 681 in that a transitional end 783 of the flap 781 is attached to an exterior of a side panel 710 of the airbag 700 via one or more temporary fasteners 71 1 . The temporary fasteners 71 1 can be of any suitable variety, such as one or more adhesives and/or one or more breakaway, tear-away, or tack stitches 713. The temporary fasteners 71 1 can be configured to secure the transitional end 783 of the flap 781 to the side panel 710 during early stages of airbag deployment when the slit vent 720 is in a closed orientation and further configured to release the transitional end 783 of the flap 781 from the side panel 710 when the slit vent 720 is in an open orientation. In the illustrated embodiment, a seam 750 does not attach any portion of the flap 781 to the side panel 710.

[0079] In the illustrated embodiment, the fixed end 785 is attached to the side panel 710 via a seam 760. The flap 781 is unattached to a first portion 776 of the side panel 710 and is attached to a second portion 778 of the side panel 710 that cooperate to define an aperture 722. When the slit vent 720 is in the closed state shown in FIG. 12, the flap 781 is entirely at an exterior of the airbag 700.

[0080] As the airbag 700 fills with inflation gas, the inflation gas can press the first and second portions 776, 778 of the side panel 710 against the inner surface of the flap 781 , which can tend to keep the first and second portions 776, 778 in fixed relation relative to each other to prevent the aperture 722 from opening. The flap 781 may be said to cover at least a portion of the aperture 722 to prevent inflation gas from passing through the aperture 722. For example, inflation gases that might otherwise escape through the aperture 722 can be inhibited or prevented from doing so by the interaction of the inner surface of the flap 781 and the external surfaces of the first and second portions 776, 778 of the side panel 710. Thus, as the airbag 700 inflates and as the slit vent 720 remains in the initial closed orientation, the flap 781 can serve to prevent gas leakage through the aperture 722 that might otherwise occur in the absence of the flap 781 . The flap 781 may be said to act as a valve or as a regulating device by selectively obstructing at least a portion of the aperture 722. [0081] At a later stage of airbag deployment (such as the stage depicted in FIGS. 10A and 10B) the slit vent 720 may open due to one or more stresses acting thereon, such as those described above. For example, outwardly directed pressure from within the airbag 700 and/or other forces that tend to separate the first and second portions 776, 778 of the panel 710, such as those due to a vehicle occupant impacting the rear panel 714 of the airbag 710, can cause the first and second portions 776, 778 to separate from each other and open the aperture 722. The stresses can further act to decouple or otherwise release the fasteners 71 1 and/or otherwise detach the transitional end 783 of the flap 781 from the side panel 710. In the illustrated embodiment, the tack stitches 71 1 may be oriented in a direction that permits them to readily release the flap 781 . For example, they tack stitches 71 1 may extend in a direction that is parallel to a direction in which forces may act to separate the first and second portions 776, 778 of the side panel 710 from each other. This may permit pulling or tugging forces on the second portion 778, which is fixedly attached to the fixed end 785 of the flap 781 , to pull the entirety of the flap 781 away from the first portion 776. In other or further embodiments, the flap 781 pressure of escaping inflation gas can decouple or otherwise release the fasteners 71 1 . For example, as the aperture opens, inflation gas from within the airbag 700 can press against the flap 781 and push the transitional end 783 outwardly with sufficient force to detach the transitional end 783 from the side panel 710. In each case, the slit vent 720 can be said to transition to the open state in which the aperture 722 is open and the flap 781 no longer obstructs the aperture 722. Stated otherwise, the flap 781 can be moved from a first orientation in which the transitional end 783 is temporarily attached to the side panel 710 (e.g., via the one or more fasteners 71 1 ) and in which the flap 781 reduces or prevents gas flow through the aperture 722 to a second orientation in which the transitional end 783 is unattached to the side panel 710 and the flap 781 permits gas flow through the aperture 722 by a greater amount than when the flap 781 is in the first orientation.

[0082] FIG. 13 illustrates another embodiment of an airbag 800 that includes a passive vent or slit vent 820 that resembles the slit vents described above in many respects. However, the slit vent 820 includes a flap 881 that is attached to an exterior of a side panel 810 of the airbag 800 via a plurality of permanent fasteners at discrete attachment regions 817. The permanent fasteners can be of any suitable variety, such as one or more adhesives, welds, and/or spot stitches 815. Adjacent fasteners can be spaced from each other to define ports 819. The flap 881 can be spaced from or separate from a pair of seams 850, 860, such that the flap 881 is not attached to the side panel 810 via the seams 850, 860.

[0083] As the airbag 800 fills with inflation gas, the inflation gas can press the first and second portions 876, 878 of the side panel 810 against the inner surface of the flap 881 , which can tend to keep the first and second portions 876, 878 in fixed relation relative to each other to prevent the aperture 822 from opening. The flap 881 may be said to cover at least a portion of the aperture 822 to prevent inflation gas from passing through the aperture 822. For example, inflation gases that might otherwise escape through the aperture 822 can be inhibited or prevented from doing so by the interaction of the inner surface of the flap 881 and the external surfaces of the first and second portions 876, 878 of the side panel 810. Thus, as the airbag 800 inflates and as the slit vent 820 remains in the initial closed orientation, the flap 881 can serve to prevent gas leakage through the aperture 822 that might otherwise occur in the absence of the flap 881 .

[0084] At a later stage of airbag deployment (such as the stage depicted in FIGS. 10A and 10B) the slit vent 820 may open due to one or more stresses acting thereon, such as those described above. For example, outwardly directed pressure from within the airbag 800 and/or other forces that tend to separate the first and second portions 876, 878 of the panel 810, such as those due to a vehicle occupant impacting the rear panel 814 of the airbag 810, can cause the first and second portions 876, 878 to separate from each other and open the aperture 822. Inflation gas that exits through the aperture 822 can pass through the ports 819.

[0085] Any suitable method may be employed to form airbags such as discussed above. For example, in various illustrative methods, the apertures 122, 222, 322, 422, 522 can be formed via laser cutting or die cutting. In some instances the reinforcing seams 150, 160, 250, 260, 350, 360, 491 , 550, 560 can be formed manually via a sewing machine. In some instances, such a manufacturing step can avoid the use of automated or programmable sewing machines, which may reduce manufacturing costs. In other instances, automated or programmable sewing machines may be used.

[0086] References to approximations are made throughout this specification, such as by use of the terms "about," "approximately," or "substantially." For each such reference, it is to be understood that, in some embodiments, the value, feature, or characteristic may be specified without approximation. Stated otherwise, the terms of approximation include within their scope the exact feature modified by the term of approximation. For example, it is noted that in various embodiments, a portion of the side panel 1 10 that includes the slit vent 120 can be substantially planar. It is thus understood that in certain of such embodiments, the portion of the side panel 1 10 can be exactly planar.

[0087] Any methods disclosed herein include one or more steps or actions for performing the described method. The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and/or use of specific steps and/or actions may be modified.

[0088] Reference throughout this specification to "an embodiment" or "the embodiment" means that a particular feature, structure or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the quoted phrases, or variations thereof, as recited throughout this specification are not necessarily all referring to the same embodiment.

[0089] Similarly, it should be appreciated that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim require more features than those expressly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment. Thus, the claims following this Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment. This disclosure includes all permutations of the independent claims with their dependent claims.

[0090] Recitation in the claims of the term "first" with respect to a feature or element does not necessarily imply the existence of a second or additional such feature or element. It will be apparent to those having skill in the art that changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. Embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.