The present invention relates to a yieldable lighting column, comprising an elongated, continuous sheet metal shell with a polygonal, preferably octagonal, cross-section with internal, stabilizing irons internally attached to the shell. It also relates to a method of providing such a lighting column with the ability to yield to a colliding vehicle with minimum damages to the vehicle and its passengers.
Lighting columns placed at the roadside, where there is a risk for a vehicle leaving the road for some reason to collide with them, are customary of a yieldable construction. The hit column will bend over the colliding vehicle and absorb the collision energy in such a way that the damages to the vehicle and its passengers will be kept at a minimum.
It is normal to construct the column from relatively thin sheet metal with a thickness of say 1.5 mm. In order to withstand the wind forces and other forces normally acting on the column, it needs to be stabilized. Conventionally, the stabilizing function can be performed by rod irons internally attached to the shell.
The stiffness of these rod irons will be maintained also at the flattening of the column shell as a result of the collision of a vehicle, and the deformation of the column is not ideal with regard to the damages to the colliding vehicle and injuries to its passengers, as the bending force of the rod irons is the same as before the collision.
A fundamentally different column is shown in WO 99/02779. The shell is made of “a thin gauge metal sheet”, in practice with a thickness of well under 1 mm. This shell does not have enough stability in any part, and therefore all sides of the shell have to be internally stabilized over their entire lengths and practically over their entire widths by strips. The construction is in practice a shell of thick material with weakened corner portions. The deformation properties at a collision are not satisfactory, because “the giving way ability is achieved . . . because of the bent corner portions joining the intermediary flat areas stabilized by the strips” (page 7, lines 2-4). The less satisfactory deformation properties have to do with the lack of free shell areas that should have the possibility to buckle under the forces from a collision.
There is a need to improve the collision properties of a yieldable lighting column of the kind with a shell with normal thickness while maintaining its stability in its normal, upright condition.
This is according to the invention attained in that the irons are flat irons, which are internally attached to each second of the sides of the shell and extend at least in the longitudinal area of the column, where a vehicle may hit the column at a collision.
The invention will be described in further detail below under reference to the accompanying drawings, in which
A collision between a yieldable lighting column 1 and a car 2 is illustrated in
If a car 2 hits a lighting column 1, it is of advantage for the driver and passengers of the car, if the column is yieldable, so that it can absorb the kinetic energy of the colliding car over a longer distance, than with a stiff column. As shown in
A section through a presently used, yieldable lighting column is shown in
In
In
The sheet metal shell 3 is internally provided with plate irons 5 (instead of the conventional round irons 4, shown in
For the intended function of the yieldable column, the plate irons 5 do not need to extend along the entire height of the column 1; their presence is most important in the area in which a collision with intended bending can occur.
In the shown preferred case, four plate irons 5 are provided, namely at each second of the internal sides of the octagonal column. The intended function may, however, in principle be accomplished with fewer or more plate irons.
When the column 1 is standing upright (
The effect of the provision of the flat irons 5 is mainly that the deformation or bending of the lighting column occurs under decreased deformation force, whereas the intended stability in the normal case with art upright column is maintained. The damages to the colliding vehicle and its passengers will be decreased, while the intended bending of the column is maintained.
Modifications are possible within the scope f the appended claims.
Number | Date | Country | Kind |
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1050753-1 | Jul 2010 | SE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP11/60989 | 6/30/2011 | WO | 00 | 10/31/2013 |