Patent Grant
6863467
The present invention relates to a crash cushion, and in particular to a crash cushion having one or more deflector skins adapted to redirect a laterally impacting vehicle, and methods for the use thereof.
Roadways are often configured or lined with protective crash barriers that protect drivers from various rigid objects, such as bridge abutments, guardrails and other obstructions. Likewise, slow moving vehicles, such as trucks, can be outfitted with truck-mounted attenuators to attenuate the impact of vehicle striking them from the rear. In various configurations, highway crash barriers and truck-mounted attenuators can be constructed of an array of compressible, resilient, energy-absorbing cylinders positioned in front of or alongside the rigid object. In operation, and in particular during an axial impact, the cylinders are compressed and absorb the energy of the impacting vehicle, thereby decelerating the vehicle in a controlled manner. However, during a lateral impact, the vehicle may tend to snag or pocket one or more of the cylinders at gaps formed between the outer curved surfaces of adjacent cylinders.
To combat this problem, crash barriers have been provided with one or more cables strung alongside the crash barrier between the barrier and the roadway, as shown for example in U.S. Pat. Nos. 5,011,326 and 5,403,112 to Carney III. The cables span the gaps between adjacent cylinders and assist in redirecting the errant vehicle back onto the roadway.
Another solution to avoid pocketing of the vehicle in the array of cylinders is shown in U.S. Pat. No. 3,845,936 to Boedecker. In particular, a series of sheet-like fish scales are positioned between the cylinders and the roadway. The fish scales are attached to selected ones of the cylinders. The fish scales are relatively expensive structurally rigid plates that are attached to the cylinders in a relatively complex manner.
By way of introduction, various preferred embodiments of the crash cushion described below include a cylinder, preferably resilient and self-restoring, having a substantially vertical longitudinal axis and an outer surface comprising a curved portion adapted to be exposed to a roadway. A deflector skin has a curved contour shaped to mate with the curved portion of the outer surface of the cylinder. The deflector skin is mounted to the cylinder on the outer surface over at least a portion of the curved portion of the outer surface.
In one aspect, one preferred embodiment of crash cushion system includes an array of cylinders having a side and at least one deflector skin which is mounted to at least one of the cylinders on the outer surface thereof over at least a portion of the curved portion that defines part of the side of the array. In a preferred embodiment a plurality of deflector skins are each mounted to a corresponding one of the cylinders.
In another aspect, one preferred embodiment of the crash cushion system includes a plurality of cylinders, at least some of which define a side of the array. Each of the cylinders defining the side of the array has an outermost vertical tangent, and the combination of such tangents preferably defines a vertical plane. At least one, and preferably a plurality of deflector skins, each including a leading edge and a trailing edge, is mounted to a corresponding one of the cylinders forwardly of the tangent. In one preferred embodiment, the deflector skins are substantially flat and are oriented in a non-parallel relationship with the vertical plane. Preferably, only the leading edge of the deflector skins is mounted to the cylinder, with the trailing edge being a free edge.
In one preferred embodiment, the crash cushion assembly includes a plurality of first and second deflector skins mounted to corresponding cylinders. Preferably, the second, outer deflector skin has a greater thickness than the first, inner deflector skin.
In another aspect, one preferred embodiment of a method for attenuating the impact of a vehicle striking a crash cushion system includes impacting a side of a crash cushion and thereby impacting at least one of the deflector skins. In another preferred embodiment, the method includes impacting a front of the crash cushion and thereby compressing at least some of the cylinders, but without substantially deforming one or more of the deflector skins. In one preferred embodiment, the frontal impact includes deforming at least one of the first curved deflector skins without substantially deforming the second deflector skins secured along only the leading edges thereof.
In another aspect, a method of assembling a crash cushion system includes arranging a plurality of cylinders in an array, positioning cylinders having a deflector skin along a side of the array and orienting the cylinders with deflector skins with the skins facing outwardly from the side of the array.
The various preferred embodiments provide significant advantages over other crash cushions. In particular, the cylinders can each be individually configured with one or more deflector skins. Accordingly, the cylinders can be easily arranged or configured in different arrays without expensive customization. Moreover, if one or more cylinders or deflector skins are damaged, they can be easily replaced.
In addition, in one preferred embodiment, the deflector skin having a leading edge mounted in front of the tangent and a free edge extending away therefrom can be angled out of the plane of the side of the array so as to provide resistance to penetration, scoring and/or gouging of the cylinders during the initial impact of a vehicle at an angle to the side of the crash cushion. Moreover, since the deflector skin is preferably secured along only one edge, it is not substantially deformed during a frontal, or axial, impact and does not interfere with the operation of the energy absorbing cylinders.
The inner, curved deflector skins also provide the advantage of providing a lower coefficient of friction than the underlying cylinder, such that the vehicle tends to slide along the deflector skin. Moreover, the deflector skin acts as armor plating, and is not as easily gouged as the underlying cylinder, so as to further avoid snagging of the impacting vehicle. Preferably, the inner deflector skin is thinner than the outer deflector skin, and thereby can bend and deform with the cylinder during a frontal impact. Moreover, the positioning of the deflector skins provides discrete protection for the cylinders in the area vulnerable to a lateral impact, yet does not interfere with the overall operation of the system.
The foregoing paragraphs have been provided by way of general introduction, and are not intended to limit the scope of the following claims. The presently preferred embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.
Referring to
In another embodiment (not shown), the crash cushion is mounted to the rear of a vehicle, such as a truck. In such an embodiment, it should be understood that the front of the crash cushion is the portion facing the flow of traffic farthest from the rear of the vehicle to which it is mounted, with the rear of the crash cushion being closest to the rear of the vehicle.
In yet another embodiment, shown in
Referring to
Referring to
The cylinders 14 each have an outer circumferential surface 18 and are formed by a wall 22 having thickness. Preferably, the wall thickness is less than about 3 inches, more preferably between about 0.5 and 2.0 inches, and most preferably between about 0.75 inches and about 1.75 inches. In one preferred embodiment, the cylinders 14 each have an outer diameter of about 24 inches and a length or height of about 40 inches. Of course, it should be understood that other shapes and sizes would also work as explained above. For example, the cylinders can be configured with alternative cross-sections, such as ellipses, ovals and the like, each of which has an outer curved surface presented to the traffic flow, with the outer curved surface having an outermost tangent. In one alternative embodiment, an upright member, for example a wall, is configured with a plurality of outer convex surfaces that face outwardly toward the flow of traffic.
The cylinders are preferably made of a resilient, polymeric material, such as high-density polyethylene (HDPE), including for example high molecular weight (HMW HDPE) high-density polyethyelene, such that the cylinders are self-restoring after impact. One suitable material is HDPE 3408. In other preferred embodiment, the cylinders are made of elastomeric materials, such as rubber, or combinations of polymeric and elastomeric materials. As used herein, the term “self-restoring” means that the cylinders return substantially (though not in all cases completely) to their original condition after at least some impacts. Therefore, to be self-restoring, the cylinder does not have to return to exactly its original condition. The term “resilient,” as used herein, means capable of withstanding shock without permanent deformation or rupture. Of course, it should be understood that the cylinders can be made of other materials, and can be solid rather than hollow, or can be filled with various materials, such as water or sand. The cylinders 14 each deform resiliently in response to compressive loads extending along a diameter of the cylinder, thereby providing forces that tend to slow an impacting vehicle. The resiliency of the individual cylinders restores the cylinders substantially to the original configuration after the impact, and preferably after many impacts.
In one preferred embodiment, shown in
In the preferred embodiment shown in
In an axial impact, the frame members 28 slide along the rail 26, and the cylinders 14 are flattened along the longitudinal direction. Deformation of the cylinders 14 absorbs kinetic energy and decelerates the impacting vehicle.
In a lateral impact, the compression elements 24 transfer compressive loads to the transverse elements 30, which in turn transfer the compressive loads to the rail 26 by way of the guides 29. This provides substantial lateral stiffness to the crash cushion such that the crash cushion redirects an impacting vehicle that strikes the crash cushion laterally. Because the frame members 28, guides 29 and the elongated structure, including the rail 26, are positioned inboard of the vertically oriented outermost tangents of the cylinders 14, a vehicle traveling down the side 8 of the crash cushion 2 cannot engage the guides or the elongated structure in a fashion likely to cause snagging of the impacting vehicle.
It should be understood that pluralities of the cylinders 14 can be configured in many different arrays, and that the crash cushion embodiment shown in
Referring to
Referring to
Referring to one preferred embodiment of the cylinder shown in
Preferably, the first deflector skin 42 is centered on the cylinder 14 about the tangent 38 of the cylinder to which it is secured or mounted, with the first deflector skin extending equal amounts forwardly and rearwardly from the tangent. In other embodiments, the first deflector skin is not centered about the tangent, and may even be positioned entirely in front of or behind the tangent. In one preferred embodiment, the first deflector skin 42 has a leading edge 46 and a trailing edge 48, both of which are preferably secured to the cylinder 14. The deflector skin 42 has an inner surface 50 and an outer surface 52. In one preferred embodiment, the inner surface 50 is abutted against the outer surface 18 of the cylinder, and a washer bar 54 is positioned on the outer surface 52 of the deflector skin adjacent the trailing edge 48. In one preferred embodiment, where the deflector skin 44 is omitted, a second washer bar 54 is positioned on the outer surface 52 of the deflector skin 42 adjacent the leading edge 46. A plurality of mechanical fasteners 56, shown as two rows of six fasteners, are used to secure the deflector skin 42 and washer bars 54 to the cylinder. The fasteners may take the form of various known types, including for example and without limitation, various screws, nuts, bolts, and washers. In one preferred embodiment, the distance between the rows of fasteners is about 21 and {fraction (11/16)} inches, forming an angle of about 104 degrees relative to the axis of the cylinder. One or more washer bars or washers can also be used inside the cylinder to secure the fasteners on the inner surface thereof. It should be understood that in alternative embodiments, the deflector skin 42 can be secured to the cylinder 14 with adhesives, with tabs or other snap-fit devices, with guides shaped to receive the ends thereof, by welding, or by other devices available and known to those of skill in the art. Preferably, openings on one of the leading or trailing edges of the deflector skin, or the mating openings formed in the cylinder, which receive the fasteners, are slotted to allow for tolerance build-ups and ease of assembly.
Preferably, the first deflector skin 42 is secured to a lower portion of the cylinder 14, with a bottom edge 58 of the skin being positioned adjacent to or slightly above the bottom edge 60 of the cylinder. Preferably, the deflector skin 42 covers only a discrete portion of the outer circumferential surface, and preferably at least a portion of the outer surface that is exposed to a lateral impact. In this way, the deflector skin 42 preferably does not extend around the entire periphery of the cylinder, such that the cylinder assembly can be made lighter and at lower costs. In one preferred embodiment, the first deflector skin 42 extends around the circumferential surface of the cylinder and forms an angle A1 between the leading and trailing edges 46, 48 relative to the center of the arc of the deflector skin or the axis 16 of the cylinder, which centers are preferably substantially coaxial. The angle A1 is preferable greater than about 60°, more preferably greater than about 90° and even more preferably greater than about 100°, although angles less than 60° would of course also work. In one alternative embodiment, the deflector skin can be secured around the entire circumference of the cylinder.
It should be understood that the terms “mounted,” “secured,” “attached,” and variations thereof, mean that one member is connected to another member, whether directly or by way of another member, and regardless of whether other members may be interposed between the members being so mounted, secured or attached. Thus, for example, a first member directly attached to a second member is also attached to a third member by way of the second member being attached to the third member.
Referring again to
Preferably, the second deflector skin 44 is relatively stiff and resilient and is capable of aiding in the redirection of an errant vehicle back on to the roadway. Preferably, the second deflector skin 44 is stiffer than the first deflector skin 42, and has a greater thickness than the first deflector skin 42, although it should be understood that the converse would also work, or alternatively that the deflector skins can be made of the same materials and have the same thicknesses. For example, in one preferred embodiment, the second deflector skin is made of 14 gauge HR (hot rolled) sheet. Of course, other materials, including other steels, and constructions such as a laminate, would also work as explained above with respect to the first deflector skin. Preferably, the material of the second deflector skin has a lower coefficient of friction relative to the vehicle or wheel than does the cylinder. In addition, the material of the first and second deflector skins preferably has a tensile yield strength of greater than about 4 ksi, more preferably greater than about 5 ksi, and even more preferably greater than about 20 ksi. In one preferred embodiment, the second deflector skin has a width of about 8 inches and a length of about 24 inches. Preferably, the second deflector skin 44 is vertically aligned with respect to the first deflector skin 42 in an overlapping relationship therewith, and with the leading edges thereof being preferably substantially flush. The dimensions and materials of the cylinder and deflector skins are meant to be exemplary rather than limiting, and larger and smaller cylinders and skins made out of a variety of materials would also work.
In one preferred embodiment, the trailing free edge 66 of the second deflector skin 44 does not extend rearwardly beyond the tangent 38 of the corresponding cylinder 14 to which the deflector skin 44 is attached, but does extend up to or outwardly from the vertical plane 40 defined by the tangents. In other preferred embodiments, the free edge 66 terminates inwardly of the vertical plane 40.
In one alternative preferred embodiment, shown in
It should be understood that other deflector skins could be mounted on top of or between the aforedescribed first and second deflector skins without departing from the scope of the invention. Likewise, other components, surface treatments and the like can be applied to or mounted on the deflector skins.
In operation, the crash cushion 2 is designed to absorb the energy of a vehicle axially impacting a front 4 of the crash cushion and redirecting the vehicle back onto the roadway when impacting a side 8 of the cushion or array. For example, when a vehicle impacts the front 4 of the array, the cylinders 14 are flattened along the longitudinal direction 20. Depending on the configuration of the system, the cylinders may be guided by a rail, as explained above, or may be tethered or secured together by other fasteners and devices. Moreover, one or more compression elements can be designed to absorb the energy of the vehicle, if desired.
During this sequence, as shown in
When a vehicle impacts the side 8 of the array, the deflector skins 42, 44 redirect the vehicle smoothly back onto the roadway. For example, when the angle of impact is relatively large relative to the vertical plane 40, the second deflector skin 44 redirects the wheel or other portion of the vehicle towards the rear 6 so as to avoid pocketing in the array of cylinders. When the angle is more shallow, the vehicle will glance off one or both of the first and second deflector skins 42, 44. The deflector skins 42, 44, with their relatively low coefficients of friction, allow the vehicle to slide along the deflector skins 42, 44 and also prevent the vehicle from gouging the cylinder 14 or otherwise becoming snagged thereon. Moreover, the deflector skins 42, 44 increase the stiffness of the cylinders in the lateral direction and thereby help prevent the vehicle from pocketing in the cylinders.
When a vehicle impacts the side of the crash cushion shown in
By securing individual deflector skins 42, 44 to corresponding individual cylinders 14, various configurations of crash cushions can be configured and deployed easily and inexpensively due to the diminished amount of customization of the various components. In essence, the system is modular, permitting like components to be configured and reconfigured as needed.
Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. As such, it is intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it is the appended claims, including all equivalents thereof, which are intended to define the scope of the invention.
| Number | Name | Date | Kind |
|---|---|---|---|
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| 3856268 | Fitch | Dec 1974 | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20030161682 A1 | Aug 2003 | US |
