Aircraft stair system using bumper arrangement
An aircraft stair system is provided with flexible bumpers configured to prevent abrupt impact of the first structure against the second. Each of the bumpers has a flexible body, a base portion, and a lever arm extending out over the base to create a gap and an open mouth.
1 . A system configured to prevent abrupt collapse of a first structure against a second structure around a rotational axis comprising:
a bumper having an at least partially flexible body;
the body having a base portion attached to the first structure;
the body having a linking portion rising up from a rear of the base portion;
the body having a lever portion extending forwardly from the linking portion;
a gap disposed between an underside of the lever portion and the base portion, the gap being configured to at least partially close upon a contact received from the second structure onto an upper surface of the lever portion;
wherein the rotational axis is established by a hinge between the first and second structures and the bumper is attached to the first structure at a location proximate the hinge in an area onto which the second structure would otherwise impact; and
wherein the first and second structures are independent portions of a foldable stairway.
2 . The system of claim 1 comprising:
an upper surface atop the base portion which together with the undersurface of the lever portion creates an engagement profile that becomes larger upon the abrupt collapse of the first and second structures.
3 . The system of claim 2 wherein the upper surface atop the base portion is arcuate.
4 . The system of claim 3 wherein the lever portion extends forward from the linking portion towards a free end towards a mouth defined between the lever portion and the linking portion.
5 . The system of claim 4 wherein the engagement profile is configured to create a gradually-increasing angular resistance which prevents the abrupt impact between the first and second structures.
6 . The system of claim 1 wherein the foldable stairway exists in a doorway of an aircraft.
7 . The system of claim 6 comprising an additional symmetrical bumper is mounted on an opposite side of the stairway from the bumper and is oriented in a substantially symmetrical manner.
8 . The system of claim 6 wherein the first structure is an upper portion of the stairway having a first set of steps on a side of the upper portion and the second structure is a lower portion of the stairway having a second set of steps on a side of the lower portion, the side of the lower portion including a second set of steps being rotatable upward to collapse onto the side of the upper portion.
9 . The system of claim 1 wherein the base portion is connected to the first structure using a chemical adhesive.
10 . The system of claim 1 wherein the height of the linkage portion is configured based on a weight of the second structure.
11 . The system of claim 1 wherein the height of the linkage portion is configured based on a rotational force generated by a collapse of the second structure against the first structure.
12 . The system of claim 1 wherein an angling of the lever portion relative to the base is configured to create a desired level of deceleration upon an engagement between the second structure and an upper surface of the lever portion.
13 . The system of claim 1 wherein the body is configured such that the gap disposed between the underside of the lever portion and the base portion is configured to greatly decelerate the second structure when the gap is substantially closed upon a contact received from the second structure onto an upper surface of the lever portion.
14 . The system of claim 1 wherein the lever portion includes downwardly-extending upper lip atop a mouth that is established between a forward end of the lever portion and a forward end of the base.
15 . The system of claim 1 wherein an eye having a substantially rounded shape is established between the lever portion, the linking portion, and a rear of the base portion.
16 . The system of claim 15 wherein the eye establishes an approximate hinge axis for the lever portion relative to the base portion.
17 . The system of claim 1 wherein an arcuate shape of the upper surface of the base is configured to engage the arcuate shape of an internal roof surface underneath the lever, and that a radius of curvature of the upper surface of the base cooperates with the internal roof surface of the lever portion creating gradually increasing resistance force against a force applied by the second structure.
18 . The system of claim 1 wherein the body is made of an elastomeric composition.