Abstract:
A dynamically deployed device shield (“DDDS”) including a cover, a loop shield, and a means for attaching the cover and loop shield to a vehicle structure. A dynamically deployed device (“DDD”) is contained in the loop shield and the loop shield is in turn contained in the cover. Upon deployment, a tear section in the cover separates and releases the loop shield and DDD. As the DDD expands and moves towards its location, the loop shield unfolds, guides the deployment of the DDD, and prevents the DDD from overshooting its final location. The shield also prevents the DDD from becoming caught on interior vehicle components and supplements the DDD with a larger protective impact surface. Optionally, a fabric shield is attached to the bottom of the DDDS to cover the area of a vehicle window below the deployed DDD and further increase the protective impact surface of the system.

Description:
This application claims the benefit of the filing date of U.S. Provisional Application No. 60/154,954, filed Sep. 21, 1999. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to the deployment of automobile air bags and other dynamically deployed devices (“DDDs”), and more particularly, to a dynamically deployed device shield (the “DDDS”) that increases the protective impact surface of an automobile air bag or other DDD while covering, protecting, and guiding the deployment of the automobile air bag or DDD. 
     2. Background of the Invention 
     Dynamically deployed devices, such as automobile air bags, are widely used to protect vehicle occupants during rapid vehicle deceleration, such as the deceleration encountered in a collision. The DDDs used in vehicles are placed throughout the vehicle in strategic locations where occupants can be expected to impact hard components of the vehicle. Generally, DDDs are placed above and below the dashboard on both the driver and passenger side, and are placed along the sides of the vehicle at both head and hip levels. The lower DDDs protect the legs and hips of the occupant, while the upper DDDs cushion the head and upper torso. 
     During a collision, impact forces deform the vehicle structure and push potentially harmful structural parts into the passenger compartment. During such deformation, parts of the vehicle structure can be severely bent or broken, threatening the safety of the occupant with sharp edges and hard surfaces. The DDD cushions the occupant against the impact and shields the occupant from the sharp edges and hard surfaces. However, the DDD itself is subject to damage from the deformed or broken structural components. Moreover, if the DDD is damaged during deployment by structural components, the DDD will not inflate properly, will not reach the desired fully deployed location, and will not prevent the occupant from striking the structural parts of the vehicle, such as the vehicle dashboard, windshield, doors, side windows, and roof. Thus, to ensure adequate performance of the DDD, the DDD must be shielded from the damaging structural components. 
     Aside from protecting the DDD and the occupant from harmful vehicle components, another aspect critical to occupant safety is the ability of the DDD to reach and remain in a position between the vehicle structure and the expected location of the occupant during the collision. Conventional DDDs tend to oscillate before settling into the designed deployment location. This oscillation is especially troublesome with tubular structures that are attached at only two ends when deployed, such as the typical design used for side impact protection. Because the DDD is anchored at its longitudinal ends, when the DDD deploys from the storage compartment, inflates, and moves toward a position centered between the anchor points, the DDD tends to overshoot its final deployment location and oscillate back and forth past its final deployment location. 
     The prior art does not overcome these problems. For example, U.S. Pat. No. 5,429,385 discloses a dashboard-mounted air bag device that uses either a protective cloth or restraint guide to keep the air bag from contacting and damaging the edge of the upper opening of the DDD storage compartment. The protective cloth and restraint guide keep the upper opening from interfering with the deployment of the air bag. However, because neither the protective cloth nor the restraint guide fully envelops the air bag, the device does not fully protect the air bag and does not limit the oscillation of the deploying air bag. 
     U.S. Pat. No. 5,385,366 discloses an air bag deflection shield for use in a panel-mounted air bag module. The shield is separate from the air bag cover door and is designed to direct the inflating air bag rearwardly and downwardly toward a vehicle occupant and to shield the cover door from contact by the inflating air bag. However, despite the shield, the air bag is still subject to damage from vehicle components and is not restrained against oscillation. 
     U.S. Pat. No. 5,149,130 discloses a protective, high temperature resistant fabric applied to the air bag to prevent damage to the portion of the inflatable cushion closest to the gas generator. Although the protective fabric prevents heat damage around the gas generator, the fabric does not protect against physical damage from harmful vehicle components in other areas of the air bag. Further, the protective fabric does not restrain the air bag to prevent oscillation. 
     U.S. Pat. No. 5,160,164 discloses a deflection device for an air bag assembly, which controls the inflation pattern of the air bag so that the air bag does not undesirably contact an occupant&#39;s head before it contacts the occupant&#39;s torso. The device controls the general deployment direction of the air bag but does not restrain the air bag at full deployment and, therefore, does not prevent oscillation. Further, the device does not protect the air bag itself against damaging contact with vehicle components. 
     SUMMARY OF THE INVENTION 
     The present invention is a protective assembly that enhances vehicle occupant protection by increasing the protective impact surface of a dynamically deployed device, such as an automobile inflatable tubular structure. The protective assembly, or dynamically deployed device shield, also provides an attractive housing for the DDD that transforms upon deployment into a shield that protects the DDD against damage by vehicle components, facilitates deployment of the DDD through vehicle trim and interior components, and limits the oscillation and overshoot of the DDD to optimize the protection of the vehicle occupant. 
     In a preferred embodiment of the present invention, the DDDS shields an inflatable tubular structure, e.g., the side-impact head strike protection structure described in U.S. Pat. No. 5,322,322, which is hereby incorporated by reference in its entirety. Other applications of the present invention include other styles of side-impact head strike and rollover counter measures, front air bags, torso side-impact airbags, and other dynamically deployed devices. 
     The DDDS comprises a loop shield, a cover, and a means for attaching the DDDS assembly to the vehicle structure. The loop shield is made of a protective material and is positioned to optimize its protective benefits to vehicle occupants without compromising its ability to wrap, restrain, and protect the DDD during deployment, particularly in areas where contact with damaging vehicle interior components is anticipated. The loop shield is attached to the vehicle structure by such means as stitching or mounting hardware. The loop shield has an interior volume that is larger than the volume of the inflated DDD, to hold the inflated DDD within a deployment location most favorable to the vehicle occupant. Thus, when the DDD is in its undeployed state, excess loop material must be gathered and secured. 
     The excess loop shield material is folded in an accordion fold, or other appropriate fashion, and placed against the DDD. The DDD and the folded loop shield are wrapped in an integral soft cover that is attached to the vehicle structure. The cover incorporates a perforated or stitched tear section that breaks away upon deployment of the DDD to allow both the loop shield and the DDD to expand. 
     The integral soft cover can be made of a separate piece of material or from the same material as the loop shield. To use the same continuous material of the loop shield, the integral cover is formed by folding back the loop shield material after the point at which it is stitched together and wrapping the loop shield and DDD again with the same loop shield material, but without accordion folds. In this configuration, because the integral cover is continuous to cover the entire length of the DDD and is formed from the same material as the loop shield, the loop shield must also be continuous, i.e., the loop shield is a continuous sleeve. 
     The loop shield is made of a thin, flexible material strong enough to withstand deployment and occupant contact forces. The preferred material for the loop shield is a woven fabric, such as nylon or polyester. Alternately, other thin, flexible materials are possible, e.g., plastic film and non-woven polyester. The length and width of the loop shield will vary depending upon the required zone of protection. 
     In a preferred embodiment of the present invention, the loop shield includes vents, e.g., holes, cuts, or slits, along the inboard or outboard side. These vents allow air to freely enter the interior of the loop shield as the loop shield is unfolding and expanding during deployment. The vents prevent a vacuum from developing inside the loop shield that could restrain the loop shield fabric and inhibit the DDD from reaching the intended final location. Further, a vacuum could draw the sides of the loop shield inward and reduce the distance of impact protection provided by the loop shield. 
     In a further preferred embodiment of the present invention, a fabric shield is attached to the bottom of the DDDS to further increase the protective impact surface of the system. This fabric shield covers the area of a vehicle window below the deployed DDD, reducing the possibility of partial ejection of vehicle occupant limbs and preventing entry of crash debris into the passenger compartment. The fabric shield connects to the bottom of the DDDS and extends to the belt line of the vehicle. A cord runs through the bottom of the fabric shield to draw it down to the belt line when the DDD is deployed. To develop tension and draw the fabric shield down, the fabric shield cord is attached at both ends to the top of the DDD and is routed around fixed points on the vehicle pillars such that when the DDD deploys, the ends of the fabric shield cord are pulled down, the cord travels around the pulleys, and the cord is drawn tightly along the horizontal belt line. With the fabric shield cord drawn tightly, the fabric shield is pulled down to the belt line. The fabric shield cord can be routed around fixed points on the vehicle pillars on one or both sides of the DDD. 
     In a preferred mode of the present invention, mounting hardware attaches the DDDS to the vehicle structure. Many variations of mounting hardware are possible and depend mostly on the structural requirements of the particular automobile. However, in one preferred embodiment, the DDDS material that forms the loop shield is continued beyond the point at which it is stitched in order to form an extra strip of material for a means of attachment. This extra material is referred to hereinafter as an attachment flap. The attachment flap has incremental holes along its longitudinal axis through which fasteners secure the DDDS to the vehicle structure. Once the loop shield material forms the attachment tab, the material is folded and continued again around the loop shield and DDD to form the integral cover. 
     An alternate preferred means of attachment uses a push-fitting stud plate, which comprises a long strip of rigid material with fasteners integrally attached at incremental points along its longitudinal axis. In this application, the flat side of the push-fitting stud plate is placed against the DDD, and the DDDS loop shield with the integral cover is wrapped around both the plate and the DDD. The DDDS loop shield and cover have holes through which the push-fitting stud plate fasteners extend and attach the whole assembly to the vehicle structure. 
     In some applications, inflatable tubular structures are attached at incremental, discrete locations with clips. Because the DDD is not continuously attached to the vehicle, attaching the DDDS at points between the clips would cause the entire DDD and DDDS assembly to pull away from the vehicle structure and “bulge” in an unsightly way. Therefore, in an application that uses incremental attachments such as plastic clips, spring elements and curved plastic strips can be added to more effectively contain the DDD and DDDS and eliminate the “bulging” appearance. The spring element is preferably a metal piano-wire spring that attaches to the vehicle structure at the plastic clip locations and draws the DDD and DDDS assembly tight to the vehicle structure. Alternately, curved plastic strips also attached at the plastic clip locations restrain the DDD and DDDS assembly close to the vehicle structure. 
     The DDDS operates as follows. When the DDD is inflated, the expansion of the DDD results in forces that detach the cover at the tear section. The DDD further expands and causes the loop shield to unfold. During deployment, the loop shield provides a smooth surface within which the DDD can deploy, preventing the DDD from becoming snagged or caught on any vehicle interior features. As deployment continues, the DDD expands, develops tension, and pulls down and away from the vehicle structure. When the loop shield is completely unfolded, the loop shield restrains the DDD and controls the DDD&#39;s ultimate orientation and position. The loop shield also limits the amount the DDD can overshoot its operational position, which in turn reduces or eliminates DDD system oscillation. When the DDD is in its deployed, functional position, the loop shield is under significant tension along its span, providing a tight protective impact surface for the vehicle occupant. In addition, with the preferred fabric shield attached to the bottom of the DDDS and pulled into position by the fabric shield cord, the fabric shield provides an additional protective impact surface from the bottom of the DDDS to the belt line of the vehicle. 
     Accordingly, it is an object of the present invention to enhance the occupant protection benefits of a dynamically deployed device by increasing the occupant impact surface area with a loop shield and a fabric shield. 
     Another object of the present invention to guide and control the deployment of a DDD. 
     Another object of the present invention is to protect the DDD while it is being deployed. For example, the invention can be used to prevent damage to the DDD by interior elements of a vehicle. 
     Another object of the present invention is to limit the DDD from overshooting its intended final position. 
     Another object of the present invention is to reduce or eliminate improper orientation, ;such as twisting, of the DDD. 
     Another object of the present invention is to reduce or eliminate oscillation of the DDD during deployment. 
     Another object of the present invention is to prevent crash debris from entering the vehicle and to prevent portions of occupants&#39; bodies from exiting the vehicle. 
     Another object of the present invention is to provide an aesthetically pleasing, integral soft cover for the DDD. 
     Another object of the present invention is to provide flexibility in positioning the DDD in order to provide maximum protection for a vehicle occupant. 
     These and other objects of the present invention are described in greater detail in the detailed description of the invention, the appended drawings, and the attached claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a cross-sectional view of a DDDS assembly attached at the top, according to a preferred embodiment of the present invention. 
     FIG. 1B is a cross-sectional view of a DDDS assembly attached at the side, according to a preferred embodiment of the present invention. 
     FIG. 2A is a schematic diagram of a deployed DDDS assembly in a vehicle, according to a preferred embodiment of the present invention. 
     FIG. 2B is schematic diagram of a deployed DDDS assembly with vents through the loop shield, according to a preferred embodiment of the present invention. 
     FIG. 2C is a cross-sectional view of a deployed DDDS assembly with a vacuum in the interior volume of the loop shield. 
     FIG. 2D is a cross-sectional view of a deployed DDDS assembly without a vacuum in the interior volume of the loop shield, according to a preferred embodiment of the present invention. 
     FIG. 2E is a cross-sectional view of the deployed DDDS assembly shown in FIG.  2 A. 
     FIG. 2F is a schematic diagram of a deployed DDDS assembly with a fabric shield and fabric shield cord system, according to a preferred embodiment of the present invention. 
     FIG. 2G is a cross-sectional view of the deployed DDDS assembly shown in FIG.  2 F. 
     FIG. 3A is a cross-sectional view of a DDDS assembly attached at the top with an attachment flap, according to a preferred embodiment of the present invention. 
     FIG. 3B is a cross-sectional view of a DDDS assembly attached at the side with an attachment flap, according to a preferred embodiment of the present invention. 
     FIG. 3C is a schematic diagram of an undeployed DDDS assembly that is attached with fasteners through an attachment flap, according to a preferred embodiment of the present invention. 
     FIG. 3D is a cross section of an undeployed DDDS assembly attached with an attachment flap and housed inside vehicle trim, according to a preferred embodiment of the present invention. 
     FIG. 4A is a cross-sectional view of a DDDS with a push-fitting stud plate, according to a preferred embodiment of the present invention. 
     FIG. 4B is a schematic of a push-fitting stud plate, according to a preferred embodiment of the present invention. 
     FIG. 4C is a cross section of an undeployed DDDS assembly attached with a push-fitting stud plate, according to a preferred embodiment of the present invention. 
     FIG. 5 is a schematic diagram of a DDDS assembly attached with clips, according to a preferred embodiment of the present invention. 
     FIG. 6A is a schematic diagram of a DDDS assembly attached with clips and a spring element, according to a preferred embodiment of the present invention. 
     FIG. 6B is a schematic diagram of a spring element, according to a preferred embodiment of the present invention. 
     FIG. 6C is a cross section of the DDDS assembly shown in FIG.  6 A. 
     FIG. 7A is a schematic diagram of a curved plastic strip, according to a preferred embodiment of the present invention. 
     FIG. 7B is a cross section of a DDDS assembly attached with a curved plastic strip, according to a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1A and 1B show cross sections of undeployed DDDS assemblies. The DDDS covers and protects DDD  11  and comprises a loop shield  12 , a cover  10 , and means for attaching the DDDS assembly to the vehicle. Loop shield  12  covers DDD  11 . The dimensions of loop shield  12  are selected to hold the inflated DDD  11  at a deployment location most favorable to the vehicle occupant, when DDD  11  is fully deployed. FIG. 2A illustrates the fully deployed DDD  11  held in place by loop shield  12  between A-pillar  20  and C-pillar  22 , and in front of B-pillar  21 . 
     As shown in FIGS. 1A and 1B, when DDD  11  is uninflated, loop shield  12  is loose and is folded in an accordion fashion and placed compactly against DDD  11 . Cover  10  keeps folded loop shield  12  and DDD  11  together in a tight package secured to the vehicle. The cover and loop shield are attached to the vehicle at means for attachment  15 . Cover  10  has a perforated or stitched tear section  13 , which separates upon deployment, releases cover  10 , and permits loop shield  12  and DDD  11  to expand. 
     Loop shield  12  and cover  10  can be manufactured from a single strip of protective material or from multiple pieces of material joined together. A preferred embodiment of the present invention uses a single strip of material that is routed from means for attachment  15  around DDD  11  and back to means for attachment  15  to form loop shield  12 . The same strip of material continues from means for attachment  15  and back around loop shield  12  and DDD  11  to form cover  10 . After forming cover  10 , the end of the strip is attached once again at means for attachment  15 . Routing the strip in this manner forms two loops, loop shield  12  and cover  10 , both with their ends attached at means for attachment  15 . Additionally, in this configuration, cover  10  and loop shield  12  span the entire length of DDD  11  to provide enhanced impact protection in all passenger compartment locations. 
     As opposed to using a single strip of protective material, an alternate embodiment of the present invention forms loop shield  12  and cover  10  from multiple pieces of material joined at means for attachment  15 . In this configuration, cover  10  spans the entire length of DDD  11 , but loop shield  12  is narrow and is positioned at a particular location along DDD  11 , e.g., in front of a window opening. Optionally, with narrow loop shields, more than one loop shield could be placed along the length of DDD  11  at specified locations. 
     Loop shield  12  is made of a thin, flexible material strong enough to withstand deployment forces and to hold the DDD  11  in position with minimal oscillation. The preferred material for an automotive application is a woven fabric, such as nylon. The length of loop shield  12  varies depending on the optimal deployment location of DDD  11 . The width of the loop shield  12  varies depending on the required zone of protection for DDD  11 . However, in a preferred embodiment, loop shield  12  spans the entire length of DDD  11  to protect the entire DDD  11  and provide impact protection for all vehicle occupants in all locations. 
     As shown in FIG. 2B, a preferred embodiment of the present invention incorporates vents  25  along loop shield  12 , preferably along the outboard side. Vents  25  allow air to enter loop shield  12  while loop shield  12  is unfolding and expanding so that the layers of unfolding fabric do not cause a vacuum to form within loop shield  12 . Avoiding such a vacuum is critical. As shown in FIG. 2C, a vacuum pulls the walls  26  of loop shield  12  inward and hinders the DDD  11  in reaching the intended final location. The vacuum also prevents the loop shield  12  from developing full tension and impact resistance. Additionally, pulling the loop shield walls  26  closer to each other reduces the safe distance  27  that the occupant&#39;s head can travel before striking the vehicle or impacting a structure on the opposite side of loop shield  12  and DDD  11 . 
     FIG. 2C illustrates a vacuum condition in which loop shield walls  26  are  20  drawn in and the safe distance  27  is dangerously shortened. In an example using vents  25 , FIG. 2D shows a loop shield  12  fully deployed in the intended final location, with an optimal safe distance  27  between the loop shield walls  26 . The interior volume  28  of loop shield  12  in FIG. 2D contains air and not a vacuum. 
     Upon deployment of the DDD  11 , the DDDS operates in the following manner. As best shown in FIGS. 1A and 1B, tear section  13  separates and releases cover  10 , permitting loop shield  12  and DDD  11  to expand. Loop shield  12  unfolds as DDD  11  inflates and provides a smooth surface within which DDD  11  can deploy. The protective material of loop shield  12  prevents DDD  11  from catching or snagging on any vehicle interior features, which could cause improper orientation and twisting of DDD  11 . Further, as deployment continues, loop shield  12  develops tension, controls the DDD&#39;s ultimate orientation and position, and limits the amount DDD  11  can overshoot its operational position. Reducing the overshoot, in turn, reduces system oscillation and provides more effective protection for the vehicle occupant. The system oscillation depends on the deployable length of DDD  11  and the system tension developed by the loop shield. 
     In addition to restricting oscillation, when the DDD is in its functional position, loop shield  12  develops significant tension along its span to improve occupant protection with an increased protective impact surface. The added protective surface area improves the restraint of the vehicle occupants and reduces the possibility of a partial ejection during a crash. Additionally, the material of loop shield  12  provides a protective barrier that prevents crash debris from entering the passenger compartment. 
     In a preferred embodiment of the present invention, loop shield  12  is positioned such that all foreseeable occupant sizes in normal seating positions are provided sufficient protection during a crash event. Also, in a preferred embodiment of the present invention, loop shield  12  is placed in areas where there is a potential for damage to DDD  11  by interior vehicle components. As shown in FIG. 2E, such potentially damaging vehicle components include, for example, headliner  211 , roof rail  222 , and B-pillar trim  233 . FIG. 2A shows other potentially damaging vehicle components including the A-pillar  20 , B-pillar  21 , and C-pillar  22  of a typical vehicle interior. 
     As shown in FIG. 2F, in an alternate preferred embodiment of the present invention, a fabric shield  280  is attached to the bottom of loop shield  12  to further increase the protective area of the system. Fabric shield  280  covers the area of the window below the deployed DDD  11 , reduces the possibility of partial ejection of vehicle occupant limbs, and adds another barrier preventing crash debris from entering the passenger compartment. Fabric shield  280  connects to the bottom of loop shield  12  and extends to the belt line of the vehicle. A fabric shield cord  282  runs through the bottom of fabric shield  280  to draw it down to the belt line when DDD  11  is deployed. To develop tension and draw fabric shield  280  down, fabric shield cord  282  is attached at both ends to the top of DDD  11  and is routed around fixed points  284 ,  285 ,  286 , and  287  on the vehicle pillars. In this configuration, when DDD  11  deploys, the ends of fabric shield cord  282  are pulled down, fabric shield cord  282  travels around the fixed points  284 ,  285 ,  286 , and  287 , and fabric shield cord  282  is drawn tightly along the horizontal belt line between fixed points  285  and  286 . With fabric shield cord  282  drawn tightly, fabric shield  280  is pulled down to the belt line. FIG. 2G illustrates a cross section of the deployed system shown in FIG.  2 F. Optionally, fabric shield cord  282  can be routed around fixed points on the vehicle pillars on only one side of DDD  11 , leaving the opposite side of fabric shield cord  282  attached on the pillar where the DDD cord is attached. 
     DDD  11 , loop shield  12 , and cover  10  can be attached to the vehicle in a number of ways. Referring to FIGS. 3A and 3B, in a preferred embodiment, attachment flaps  30  extend from loop shield  12  and cover  10  through which fasteners (e.g., screws, tacks, plugs, and push-fittings) or stitches  15  are placed to secure the DDDS to the vehicle. Attachment flap  30  extends either above or beside the DDDS depending upon the specific configuration of the particular vehicle. FIG. 3A shows the DDDS attached at the top while FIG. 3B shows the DDDS attached on the side. FIG. 3C shows an example of a DDDS assembly that is attached with fasteners  32  through the holes in the attachment flap  30 . FIG. 3D illustrates a cross section of a DDDS assembly attached with fasteners  32  through an attachment flap  30  and housed inside vehicle trim  34 . 
     Another representative embodiment for attaching the DDDS to the vehicle is a system of mounting hardware. The mounting hardware may be fabricated in different ways, depending upon the vehicle configuration and intended use of the DDDS. For example, as shown in FIG. 4A, a push-fitting stud plate  41  attaches the DDDS to the vehicle. As shown in FIG. 4B, the push-fitting stud plate  41  comprises a long strip of rigid material with fasteners  42  integrally attached at incremental points along its longitudinal axis. In this application, the flat side of the push-fitting stud plate is placed against DDD  11 . Loop shield  12  and integral cover  10  are wrapped around both the plate and DDD  11 . DDDS loop shield  12  and cover  10  have holes through which the push-fitting stud plate fasteners  42  extend and attach the whole assembly to the vehicle structure. FIG. 4C shows a cross section of DDDS assembly attached with a push-fitting stud plate  41  and fasteners  42  and concealed within a headliner  44  and a trim component  46 . 
     As shown in FIG. 5, another embodiment of the present invention uses clips  50 , preferably made of plastic. However, other materials may be used to make the clips. In this embodiment, clips  50  attach the DDDS at discrete locations to roof rail  222  of a vehicle. 
     Using clips presents some disadvantages. Between the discrete clip locations, there may be bulges  51  in the DDDS fabric as shown in FIG.  5 . These bulges  51  do not impact the operation of the DDD. However, they may not be aesthetically pleasing to the vehicle owner. In a preferred embodiment using clips, there are several possible ways to eliminate these fabric bulges  51 . Two examples are discussed below: (1) a spring element; and (2) a plastic strip. 
     FIG. 6A illustrates the use of a spring element  60  to remove the fabric bulges  51 . The spring element  60  is attached at the clip  50  and extends to the point equidistant between two discrete clip locations  50 . Cantilevered from its attachment point at clip  50 , spring  60  extends longitudinally along the inflatable assembly, pulls the fabric bulges  51  tight against the vehicle structure, and eliminates any unsightly appearance. The spring  60  is preferably made of a metallic material, such as piano-wire spring or other like materials. 
     FIG. 6B shows an example of a preferred spring element  60  separated from the DDDS assembly for clarity. 
     FIG. 6C is a cross section of a DDDS assembly with a spring element  60 , illustrating the way in which the spring element  60  eliminates the fabric bulges  51 . 
     FIG. 7A shows another way to mitigate the fabric bulges that may appear when using the clip attachment method. A curved plastic strip  70  is attached through holes  71  at the clip locations  50 . The curved plastic strip  70  extends longitudinally along the inflatable assembly, pulls against the fabric, and keeps it close to the vehicle structure, thereby eliminating the fabric bulges  51 . 
     FIG. 7B is a cross section of a DDDS assembly with a curved plastic strip  70 , illustrating the way in which the curved plastic strip  70  eliminates the fabric bulges  51 . 
     The foregoing disclosure of embodiments of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many variations and modifications of the embodiments described herein will be obvious to one of ordinary skill in the art in light of the above disclosure. The scope of the invention is to be defined only by the claims appended hereto, and by their equivalents.