Land vehicles – Wheeled – Attachment
Reexamination Certificate
2000-01-07
2004-02-03
Johnson, Brian L. (Department: 3618)
Land vehicles
Wheeled
Attachment
C280S731000, C428S578000
Reexamination Certificate
active
06685215
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to inflatable cushions used in vehicle occupant restraint systems. More particularly, this invention relates to a cushion constructed from fabric in the form of two congruent twelve-sided panels that may or may not share a common side. During the construction process, the panels are superimposed in congruent fashion and joined along their respective coincident edge portions to form a twelve-sided polygonal-shaped cushion.
BACKGROUND ART
An inflatable restraint cushion, or air bag, plays an important role in protecting the occupants of a vehicle from injury due to collision against the car body. Typically, the air bag is disposed within a supporting structure such as a steering wheel, dash panel, door panel, or other fixed portion of a car body in opposed or adjacent relationship to a seat in the vehicle. When inflated rapidly by the pressure of a reaction gas released from an inflator during a collision, the air bag serves as a protective barrier between the vehicle occupant and the steering wheel or other portion of the vehicle body against which the occupant might otherwise be thrown.
Air bags have been used in the past to protect both the vehicle operator and vehicle passengers. Systems for the protection of the vehicle operator are typically mounted in the steering column of the vehicle and utilize cushion constructions that deploy directly towards the driver. These driver-side air bags can be of a relatively simple configuration in that they function over a small, well-defined area between the driver and the steering column. Typically, driver-side air bags are circular or substantially circular in shape when viewed from the front or the back. Such circular air bags are frequently constructed by superimposing, aligning, and joining, along their respective coinciding edges, two generally circular fabric sections that are separately cut from a web or blank of air bag fabric.
It has been found that the amount of fabric used in the finished air bag contributes a large percentage of the costs of air bag production. While circular air bags are functionally effective, the circular shape of the front and back fabric panels from which the air bags are constructed does not lend itself to the efficient utilization of fabric during the manufacturing process. Specifically, the arrangement of these circular panels on a given blank of air bag fabric does not result in efficient fabric utilization or yield. Fabric is wasted in producing such circular cushions since the circular templates do not have straight edges which can be aligned with the edges of the fabric blank or which can be juxtaposed in close proximity on the fabric to provide common or nearly common adjacent edges with minimal fabric waste between neighboring cut sections. Furthermore, because use of circular or other curved panels frequently results in oddly-shaped sections of fabric between neighboring cut panels, utilizing such inter-panel fabric to make other necessary parts of the air bag (e.g., various reinforcements, tethers, doublers, etc.) is often difficult.
An additional problem with circular air bags is the amount of time consumed in the production operations of cutting, joining, and folding such bags. Straight edges, as are found in polygon-shaped panels, are easier to cut and to align for joining. The edges also provide a convenient means for folding the finished air bag into the appropriate shape for mounting into the steering column. The present invention addresses the problems of fabric utilization and production efficiency, in a manner not found in the prior art.
As used herein, it is intended that the following terms be defined as indicated: The term “polygon” is a plane geometric figure having n sides and n vertices. The term “dodecagon” is a plane geometric figure having twelve sides and twelve vertices. A regular dodecagon is an equiangular polygon in which the twelve sides are of equal length. An “Alternating Side Length (ASL) dodecagon” is a symmetrical, twelve-sided polygon in which six sides have a first length and six sides have a second length, the second length being approximately twice as long as the first length, and the sides being arranged in an alternating sequence of short and long sides. A convex polygon is one for which no side, if extended, will enter the polygon. Unless otherwise specified, the term “dodecagon” shall refer to a convex, twelve-sided polygon. The term “congruent” shall be used to mean capable of being superimposed so as to have a perimeter that is coincident throughout. The term “fabric” shall be used in a broad sense to describe any woven or non-woven fabric, film, polymer, combinations or composites thereof, or other suitable material from which the individual panels comprising an air bag may be constructed.
It is common, particularly in air bags designed for the protection of vehicle drivers, to find such air bags fabricated from the seaming or joining of two similarly-dimensioned circular panels along their respective perimeter edges after such circular panels have been cut from a blank of suitable air bag fabric and superimposed in congruent fashion. The instant invention provides for the use of relatively simple polygonal starting geometries for the fabric panels in order to reduce fabric waste by reducing the quantity of fabric between the panels on a fabric blank. Additionally, fabric waste may be reduced because, when such polygons are used, the inter-panel fabric (which might otherwise have to be discarded when circular panels are used) tends to have a straight-sided shape from which the fabrication of other components needed for air bag construction (e.g., reinforcements and the like) may be more easily constructed, thereby saving on the area of uncut fabric blank that must be used in the construction process.
It has been found that fabric utilization can be significantly improved by substituting polygon shapes, and particularly polygons having twelve sides, for the circular-shaped panels of the prior art. In one preferred embodiment, two such panels are individually cut and the cushion is constructed by superimposing the panels in congruent fashion (i.e., with coincident edges) and joining each of the twelve sides of one of the polygon-shaped panels to the respective coincident sides of the other panel. In another preferred embodiment, a single panel is cut in the form of a pair of abutting, congruent twelve-sided polygons that share a common uncut side, i.e., a single, dual-lobed panel, in which each lobe resembles an twelve-sided polygon having eleven cut edges. This single piece panel is then folded about an axis that coincides with the shared uncut side to allow the lobes to be superimposed in congruent fashion. By joining the respective eleven coincident cut edges, a polygonal cushion similar to the two-panel cushion of the first embodiment may be formed, but without the need for a joining operation along the shared side due to the lack of any cut edge.
The polygon shapes can be placed in close proximity to one another on the fabric blank from which they are cut, thus minimizing fabric waste and cost, and providing a useful advancement over the present art. In one embodiment, regular dodecagons are placed in such fashion that the number of sides of any given dodecagon that are coincident with adjacent dodecagons is in the range of two to six, depending on the position of the first dodecagon on the fabric blank. The fabric between polygon-shaped panels (the inter-panel fabric) tends to be in the shape of a triangle, having substantially straight sides, and is therefore easier to utilize in the manufacture of other air bag components (e.g., reinforcements or other components). In a second preferred embodiment, Alternating Side Length (ASL) dodecagons are placed in contiguous relation to one another, such that the number of sides of any given first dodecagon that are coincident with adjacent dodecagons is in the range of two to six, depending on the position of the first dodecagon on the fabric blank. I
Bottorff Christopher
Johnson Brian L.
Milliken & Company
Moyer Terry T.
Wilson Charlotte C.
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