Note: Descriptions are shown in the official language in which they were submitted.
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Street Pole
This invention relates to impact absorbing street poles
according to the preamble of the first claim.
Impacts absorbing street poles are already well known in the
art. Design engineers are now indeed increasingly looking at other ways to
improve vehicle occupant safety by focussing on the advantages that can be
achieved by improving the crashworthiness of street furniture, for example by
reducing the effects of a vehicle-street pole impact. In this context, impact
absorbing street poles have been developed, i.e. a category of poles that are
constructed to at least partially absorb the impact of a vehicle with a pole
of
this type. An example of such an impact absorbing street pole is known from
US 2010/0107521 Al. US 2010/0107521 Al describes an impact absorbing
deformation street pole which is formed in such a way that impact of a vehicle
with the pole deforms, i.e. flattens, an area of the pole that is directly
contacted
by the vehicle initially. The impact then may extrude other sections of the
pole
above and below this area of the pole as the vehicle moves forward after
initial
impact with the pole and ultimately may bend (in effect, collapse) the pole
rearwardly over the roof of the vehicle. The deformation and the subsequent
extrusion absorb the impact energy. The bending of the pole over the roof of
the vehicle confines the vehicle. However, it may happen that the pole upon
impact of the vehicle, when bending over the roof of the vehicle, actually
crushes the roof and may for example injure the occupant(s) of the vehicle.
The street poles according to the state of the art therefore still
represent a substantial risk for the occupants of a vehicle during impact of
the
vehicle with the street pole.
There is thus a need for an impact absorbing street pole for
which the safety features can be improved.
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Thereto, the street pole comprises an elongated extension
detachably connected at a pre-determined height to a first part of the street
pole such that upon impact on the first part of the street pole, the elongated
extension disconnects from the street pole.
The inventors have found that providing an impact absorbing
street pole with an elongated extension, detachable connected to the first
part
of the pole substantially reduces the risk for the occupants of the vehicle to
be
crushed by the bent part of the impact absorbing street pole , more
specifically
in an impact absorbing deformation street pole, during impact of the vehicle
with the street pole. With impact is preferably meant in the context of the
present invention an impact with a vehicle of about 900 kg at for example a
velocity of 35 km/h and than also a higher velocity of 50 km/h, 70 km/h or 100
km/h, according to the European norm EN 12767/2007 or the American norm
NCHRP350 or MASH established at substantially the same velocities, for
example a velocity of 30 km/h and than also a higher velocity of 50 km/h, 70
km/h or 100 km/h, but with a heavier vehicles. Upon impact, the impact
absorbing street pole absorbs at least part of the energy created during the
impact, reducing the deformation of the vehicle upon impact and resulting in a
less aggressive drop in acceleration with respect to time for the occupant(s)
of
the vehicle and the elongated extension disconnects from the street pole such
that for example the clasp-knife effect, wherein the street pole bends and the
bent part of the street pole crushes the vehicle such as for example in impact
absorbing deformation street poles, is reduced. Since the bent part of the
street pole can be reduced in length compared with the deformation street
poles of the prior art, both the length of the pole and its momentum when
impacting the vehicle are reduced, limiting the damage to the vehicle and the
risk of injuries for the occupants of the vehicle. The invention is of course
not
limited to impact absorbing deformation street poles and can also be applied
to
other impact absorbing street poles such as for example break-away impact
absorbing street poles of which the first part breaks away upon impact with
the
vehicle.
The combination of the impact absorbing street pole with an
elongated extension enhances the shock absorbing ability of the assembly and
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allows it to better control the G-forces upon impact. In addition, the
combination according to the invention, allows the inventors to erect higher
and more robust structures for use as roadside hardware.
According to preferred embodiments of the current invention,
the height of the first part of the street pole is chosen such that upon
impact,
allows improved control of the G-forces upon impact and, when applied to an
impact absorbing deformation street pole, the bent part of the street pole
crushing the vehicle does not substantially hit the roof of the vehicle. It
has
been found that such lengths allow to further reduce the risk that the
occupants of the vehicle impacting the street pole are injured is reduced.
According to embodiments of the street pole according to the
invention, the height of the first part of the street pole is smaller or
larger than
the height of the elongated extension, according to the desired configuration.
According to preferred embodiments of the street pole
according to the invention, the elongated extension comprises a cylindrical
body, for example a hollow cylindrical body, extending around the longitudinal
direction along a circumferential direction.
Such an arrangement of the elongated extension makes the
construction thereof easier since it may be manufactured for example by
bending a sheet of a bendable material around a given axis. If the cylindrical
body is hollow, it reduces the risk that the elongated extension, when it
disconnects from the first part upon impact of a vehicle, might injure people
or
damage for example vehicles. It also allows for example electrical wires or
any
other wires or conduits to pass through the hollow cylindrical body,
especially if
such wires are coming from a first part of the street pole, comprising a
hollow
cylindrical body wherein the wires are present.
According to preferred embodiments of the street pole
according to the invention, an attachment, for example any one or more of a
lamp, a roadsign, a street sign, a traffic light, is connected to the
elongated
extension. Naturally, any attachment can also be attached at other locations,
for example in combination with the attachment connected to the elongated
extension. For example, an additional attachment can be attached at a far
lower location, for example a roadsign at height where traffic participants
can
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easily read the sign, for example car drivers through the windows of their
car,
for example at some meters above the road.
Such an attachment may be fixedly connected to the elongated
extension and releasably connected from the street pole together with the
elongated extension upon impact of a vehicle on the first part of the street
pole, thereby avoiding that a relatively heavy object with a relatively large
momentum impacts the vehicle and may harm its occupants or damage
property in the surroundings of the street pole, especially when the street
pole
is an impact absorbing deformation street pole.
According to preferred embodiments of the street pole
according to the invention, the circumference of the first part of the street
pole
is smaller or larger than the circumference of the elongated extension at the
predetermined height according to the desired configuration.
In such a way, the elongated extension may be easily
connected to the first part of the street pole, especially if the
circumference of
the first part of the street pole is smaller than the circumference of the
elongated extension at the predetermined height and the top of the first part
of
the street pole snugly fits into the elongated extension, bringing about an
increased stability of the assembly of the first part of the street pole and
elongated extension and in some cases any supplementary connection means
may be dispensed with. In addition such a connections prevents falling water,
such as for example rain, from entering the street pole.
According to preferred embodiments of the street pole
according to the present invention, the first part of the street pole
comprises a
cylindrical body extending around the longitudinal direction along a
circumferential direction.
Such an arrangement of the first part of the street pole, in a
similar way as for the elongated extension, makes the construction thereof
lighter and easier. The arrangement of the first part of the street pole
comprising the body reduces the force of the impact of a vehicle, because
such a pole may absorb part of the energy of the impact and deform, making it
an impact absorbing deformation street pole, and might reduce the risk of
injuries people and/or damages to for example vehicles. If the cylindrical
body
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is hollow, it also allows for example electrical wires or any other wires or
conduits to pass through the cylindrical body.
According to preferred embodiments of the street pole
according to the present invention, the cylindrical body is hollow and the
5 cylindrical body of the first part comprises at least one overlap of a
first and a
second edge of a circumferential side wall forming the hollow cylindrical
body,
the hollow cylindrical body comprising fastening means for interconnecting the
first and the second edge, the overlap having a length extending substantially
parallel along the longitudinal direction.
The inventor has found that the first part of a street pole having
such an overlap allows for interconnecting the first and the second edge by a
wide range of different fastening means such as welding, soldering, bolts,
rivets, screws, staples, gluing, etc. The street pole according to the
invention
with such a first part moreover is aesthetically attractive and is safer for
people
passing the street pole since it does not have a protruding flange.
Another option for fastening the adjacent metal sheet(s) which
is known from the state of the art is by bending metal sheet(s) such that the
adjacent edges become collinearly touching each other. Interconnecting the
collinearly touching adjacent edges is however difficult and, in order to
achieve
a sufficient interconnection of the first and the second edges, is mainly
limited
to welding. For example, no bolts can directly be used in this
interconnection.
When the metal sheets are coated with zinc, for example by galvanizing,
before being bended and interconnected to form the street pole, the adjacent
edges can no longer, or least with increased difficulty, be welded together.
So
instead, the collinearly touching adjacent edges need to be welded together
before coating with for example zinc and can only be galvanised after the
first
and the second edge have been welded together, which is more difficult and
hence more costly. When street poles comprise a first part comprising an
overlap of the first and the second edge, this problem can be solved by using
other fastening means than welding, such as for example, bolts, nails, rivets,
screws or the like since the fastening means of the first part of the street
pole
according to the current invention are no longer limited to welding.
According to preferred embodiments of the street pole
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according to the invention, the side wall and the fastening means are provided
to split open along the overlap by breaking away the fastening means upon
impact at a place of impact on the first part of the street pole, the hollow
cylindrical body, being provided at the place of impact.
The first part of such a street pole is designed to absorb an
impact of for example a vehicle, such that the kinetic energy of an object,
for
example a vehicle, impacting the street pole preferably is substantially
absorbed by the first part of the street pole by deformation of the first part
of
the street pole, making the street pole an impact absorbing deformation street
pole, due to the impact in stead of for example deformation of the object,
which is, in case of for example a vehicle, hazardous for the occupants of the
vehicle. It has been found that accidents involving such a street pole
impacted
by a vehicle have a reduced mortality rate than accidents involving a street
pole which does not absorb the energy of the impact with the vehicle. A street
pole having the ability to absorb a significant amount of energy of an impact
with a vehicle is generally called a street pole which is passively safe.
A street pole designed to absorb the energy of an impact with a
vehicle is for example described by F194890B. The street pole according to
F194890B however does not comprise the overlap of the street pole of the
current preferred embodiment, having a width which extends substantially
along the circumferential direction, but instead has an inwardly bent flange,
as
described above. When a vehicle impacts the street pole according to
F194890B, the fastening means are provided to break away from the overlap
and the overlap as a further consequence splits open. However, it has been
found that the rigidity of the street pole according to F194890B generally
remains too large during impact with the vehicle such that an insufficient
amount of energy is absorbed by the street pole, which increases the amount
of energy which needs to be absorbed by the car, causing an increased risk of
mortality and/or injuries to occupants of the vehicle.
The overlap of the first part of the street pole of the current
preferred embodiment however allows for an improved absorption of kinetic
energy of the vehicle. Without wanting to be bound by any theory, the inventor
believes that this is caused by the direction of the width of the overlap,
being
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substantially along the circumferential direction. It has been found that the
impact of the vehicle onto the place of impact causes the hollow cylindrical
body to collapse in direction of the impact, making the street pole an impact
absorbing deformation street pole. As a consequence, a first part and a
second part of the side wall of the hollow cylindrical body, the second part
opposing the first part along the direction of the impact are pushed together
in
direction of the impact and a third and a fourth part of the side wall of the
hollow cylindrical body, the fourth part opposing the third part along a
direction
substantially perpendicular to the direction of the impact, are pushed away
from each other. The relative movement of the first, second, third and fourth
part causes the two edges to move in opposite directions along the width
direction of the overlap so that the first part of the street pole splits open
in
longitudinal direction along the overlap by breaking away the fastening means.
A similar effect can for example be observed in W02008151862.
The inventor has found that such an opposing movement of the
edges causes the rigidity of the first part of the street pole to drop
significantly
upon impact, which increases the amount of energy which can be absorbed by
the street pole of the current invention. Without wanting to be bound by any
theory, the inventor believes that the opposing movement of the edges along
the width direction of the overlap causes a shear effect which causes an
improved breaking away of the fastening means.
The inventor also found that the rigidity of the first part of the
street pole of the current invention which has not been impacted remains
substantially the same. The street pole according to the current invention in
other words allows the rigidity of the street pole to be significantly reduced
during impact whereas sustaining the rigidity of the street pole before
impact.
According to more preferred embodiments of the street pole
according to the current invention, the fastening means are rivets.
The inventor has found that by interconnecting the two edges
with rivets, the interconnecting of the two edges becomes increasingly easy
and even edges of for examples galvanised steel can for example be
interconnected. Moreover, although the rivets provide the unimpacted first
part
of the street pole with sufficient rigidity, the rivets are also more easily
broken
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away by the opposing movement of the edges along the width of the overlap
during impact so that the amount of energy absorbed by the first part of the
street pole is further increased, improving the passive safety of the street
pole.
Other details and advantages of the street pole according to the
invention and the method for placing the street pole according to the
invention
will become apparent from the enclosed figures and description of preferred
embodiments of the invention.
Figure 1 shows a preferred embodiment of a street pole
according to the invention.
Figure 2 shows a different embodiment of a street pole
according to the invention.
Figure 3 shows a cross-section of a preferred embodiment of
the street pole according to the invention.
Figure 4 shows a street pole according to the prior art which has
been impacted by a vehicle.
Figure 5 shows a cross-section of a different embodiment of the
street pole according to the invention.
Figures 6a ¨ 6d successively show the effect of a vehicle
impacting a street pole according to the invention during the impact of the
vehicle with the street pole.
A street pole 1 comprising an elongated extension 17 connected
to a first part 18 of the street pole 1 according to the invention is shown in
figure 1 and 2. The first part 18 of the street pole 1 shown in figures 1 and
2 is
fixed to the ground. The first part 18 of the street pole 1 can be fixed to
the
ground in any way known to the person skilled in the art. The first part 18 of
the street pole 1 can for example be dug into the ground, bolted to the
ground,
etc. When fixed to the ground, the street pole 1 preferably extends in a
substantial upright, preferably vertical, direction as shown in figure 1. The
street pole 1 can however also be provided to be fastened to for example the
wall of a building or the like, extending in a substantial horizontal
direction.
The street pole 1 shown in figures 1 and 2 extends substantially
along a longitudinal direction 8. The longitudinal direction 8 extends between
a
first and a second end.
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The first end is provided to be fastened to a substrate. In figures
1 and 2, the substrate shown, is substantially horizontal. The substrate can
however also extend substantially vertically or any other direction. As
discussed above, the substrate can for example be the ground, a wall of a
building, etc.
The first end can for example be provided to be dug into the
ground. The first end can moreover be provided to be put at least partly in
cement. However, other known ways for fastening the first end to the substrate
can be used such as for example bolting the first end to the substrate.
The first end preferably comprises means for allowing electrical
wires to enter the street pole 1, preferably the first part 18 of street pole
1, for
example to provide electricity to lighting or any other electrically powered
means. Thereto, the first end comprises for example an opening leading
towards the interior of the street pole 1, preferably the first part 18 of
street
pole 1. This is however not critical for the invention and the electrical
wires can
for example also be provided along the exterior of the street pole 1.
The second end is provided to be provided with means such as
for example lights 19, street signs, traffic signs, traffic lights,
directions,
billboards, etc. The second end for example can be provided with one, two,
three, four or even more horizontally bent arms, each arm comprising lighting
means, creating a lighting pole which can be used along streets or highways to
illuminate the streets or highways. The second end is part of the elongated
extension 17.
The street pole 1 can have any shape and dimension which is
deemed appropriate by the person skilled in the art. The longitudinal
direction
8 of the street pole 1 shown in figures 1 and 2 is substantially straight.
However, the street pole 1 can for example be bent along its longitudinal
direction 8, for example when it is provided to be mounted to an upright
substrate.
The street pole 1 comprises an elongated extension 17,
detachably connected at a predetermined height h to a first part 18 of the
street pole 1. The elongated extension 17 shown in figures 1 and 2 comprises
a cylindrical body extending around the longitudinal direction along a
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circumferential direction. The circumference of the elongated extension 17
may be smaller, equal or lager than the circumference of the first part 18 of
the
street pole 1 to which it is connected. Figure 1 and 2 show that an attachment
19 is connected to the elongated extension 17. The attachment may be for
5 example a streetlamp, a traffic light, a traffic sign or an advertisement
sign but
is in no way limited to the examples mentioned herein.
The street pole 1, preferably the first part 18, comprises a
cylindrical body 6. The cylindrical body 6 extends around the longitudinal
direction 8 along a circumferential direction 9. A cross section of such a
10 cylindrical body 6 is for example shown in figures 3 and 5.
The cylindrical body 6 can be provided anywhere along the
longitudinal direction 8 of the street pole 1, preferably of the first part
18. The
street pole 1, preferably the first part 18 can for example comprise a first
longitudinal section being solid or hollow, for example, wood, plastic, etc.,
and
a second longitudinal section being formed by at least one cylindrical body 6.
The first and second longitudinal section can be provided anywhere along the
longitudinal direction 8 such that the first longitudinal section is provided
near
the first end and the second longitudinal section is provided near the second
end, but preferably the first longitudinal section is provided near the second
end and the second longitudinal section is provided near the first end. It is
preferred that the street pole 1, preferably the first part 18 is made of at
least
one cylindrical body 6. Figure 2 shows for example the first part 18 of street
pole 1 being made of different subsequent cylindrical bodies 6. Preferably,
the
first part 18 of street pole 1 however is made of a single cylindrical body 6,
as
shown in figure 1.
The inventor has found that when the street pole 1, preferably
the first part 18, is made of a single cylindrical body 6, preferably a hollow
cylindrical body, the street pole 1 can be easily made.
The cylindrical body 6 can be made of any material such as
plastic, wood, metal such as for example aluminium, steel, stainless steel,
galvanised steel, etc.
The cylindrical body 6 can have any shape and dimensions
deemed appropriate by the person skilled in the art.
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The dimensions of the cylindrical body 6 preferably are
substantially determined by its length and its diameter 12. The length of the
cylindrical body is measured along the longitudinal direction 8 of the street
pole
1, preferably the first part 18, whereas the diameter 12 is defined as the
diameter of an arc defining the circumferential direction 9 of the cylindrical
body 6, as shown in figures 3 and 5.
The diameter 12 of the cylindrical body 6 can be determined by
the person skilled in the art.
The shape of the cylindrical body 6 is substantially determined
by the shape of the cross section of the cylindrical body 6. Two examples of
shapes of cross sections, polygonal and round, are respectively shown in
figures 3 and 5. Any other shape of the cross section is however possible and
can be determined by the person skilled in the art such as for example, a
regular or irregular polygon having 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16,
17, 18, 19, 20 or even more vertices 13, an arcuate shape such as an
ellipsoid, etc.
The cross section of the cylindrical body 6 can change along the
length direction of the cylindrical body 6. The area of the cross section can
for
example become larger or smaller along the length direction or can remain
substantially constant.
Preferably, the area of the cross section of the cylindrical body 6
becomes smaller in a direction from the first end of the street pole 1,
preferably the first part 18, towards the second end of the street pole 1, as
shown in figures 1 and 2, more preferably, but not essentially, when the
cylindrical body 6 has a polygonal cross section.
Preferably, the area of the cross section of the cylindrical body 6
is substantially constant along the longitudinal direction 8 of the street
pole 1,
preferably the first part 18, more preferably, but not essentially, when a
round
cross section is used as shown in figure 3.
The cylindrical body 6 of the street pole 1, preferably the first
part 18 of street pole 1, comprises a circumferential side wall 7 forming the
hollow cylindrical body 6. The circumferential side wall 7 comprises a first 3
and a second 4 edge which overlap to form an overlap 2. A top view of the
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overlap 2 is for example shown in figure 3 and 5. The overlap 2 has a length
which extends substantially along, preferably parallel to, the longitudinal
direction 8, as shown in figures 1 and 2. The length 10 of the overlap 2 can
however extend along any possible direction extending substantially along the
5 longitudinal direction 8.
The circumferential side wall 7 can be a single piece or can be
made of different pieces. When the hollow cylindrical body 6 is made of a
multitude of pieces, the pieces can be adjoined using any method known in the
art such as welding, soldering, gluing, stapling, bolting, screwing, riveting,
etc.
10 The overlap 2 can be positioned on every location along the
circumferential side wall 7. However, when the hollow cylindrical body 6 has a
polygonal cross section, the overlap 2 preferably is provided in between two
adjacent vertices 13 of the polygonal cross section. The overlap 2 more
preferably is provided substantially equidistant from the two adjacent
vertices
13. The overlap 2 can however be provided at every location deemed
appropriate by the person skilled in the art such as for example at or near a
vertex 13.
Although a single overlap as shown in figures 3 and 5 can be
sufficient for the envisaged application of the street pole 1, this is not
critical
for the invention and the street pole 1 can also have a plurality of overlaps
2.
For example, the street pole 1 can have two, three, four five six, seven, etc.
overlaps 2 depending on for example the dimensions of the street pole 1. It
has been found that by providing multipleoverlaps, the impact absorbing
properties can be better controlled. Especially when street poles having a
relative large diameter are being provided, it has been found that although
the
increased diameter increases the strength of the street pole 1, the plurality
of
overlaps can nevertheless provide the desired impact absorbing properties.
When a plurality of overlaps 2 is provided, preferably, the
overlaps 2 are distributed substantially evenly over the circumference of the
street pole 1 so as to provide substantially homogeneous impact absorbing
properties. For example, when the hollow cylindrical body 6 has a polygonal
cross section, the overlap 2 preferably is provided between adjacent vertices
13 leaving, for example, the same, or for example substantially the same,
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number of vertices 13 in between overlaps 2. So for example, when the hollow
cylindrical body 6 is a regular convex nonagon polygon, it has nine vertices
13
and the number of overlaps can be for example three, with 3 vertices 13 or two
sides between vertices 13 in between overlaps 2.
The hollow cylindrical body 6 comprises fastening means 5 for
interconnecting the first 3 and second 4 edge of the circumferential side wall
7.
Any fastening means 5 known to the person skilled in the art can be used for
example bolts, nuts, rivets, screws, nails, staples, glue, welds, solderings,
etc.
When the overlap 2 of the first 3 and the second 4 edge causes
one of the first 3 and the second 4 edge to be pressed to the other edge 3, 4,
for example due to a resilient force remaining after bending of the edges in
the
desired overlapping configuration, the friction caused by the pressing of one
edge to the other may cause that a sufficient interconnection of the first 3
and
the second 4 edge is reached. In that case the fastening means 5 are the
cooperating first 3 and second 4 edge and no additional bolts, nuts, rivets,
screws, nails, staples, glue, welds, solderings, etc. are necessary. In this
case
breaking away the fastening means 5, according to preferred embodiments of
the present invention, means that the friction between the first 3 and the
second 4 edge is overcome and that first 3 and the second 4 edge are allowed
to move in opposite directions along the width direction of the overlap 2.
The fastening means 5 are preferably provided along the entire
length 10 of the overlap 2, for example on regular distances when for example
nuts, bolts, screws, nails, staples or the like are used or preferably along
the
entire length 10 of the overlap 2 when for example cooperating first 3 and
second 4 edges, glue, welds, solderings, or the like are used. Other
configurations of the fastening means 5 are however possible.
The overlap 2 has a width 11 which extends substantially along
the circumferential direction 9. The first 3 and the second 4 edge of the
circumferential side wall 7 in other words overlap each other along the
circumferential direction 9. The width 11 is for example shown in figures 1
and
2.
The width 11 of the overlap 2 can be determined by the person
skilled in the art. Preferably, the width 11 of the overlap is determined in
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function of the fastening means 5 and/or the required strength of the street
pole 1. For example, when rivets, bolts, nails, screws, staples, etc. are used
to
interconnect the first 3 and the second 4 edge of the cylindrical body 6, the
width 11 needs to be sufficient to receive the fastening means 5 and to offer
a
sufficient interconnection of the first 3 and the second 4 edge. When using
other fastening means 5 such as for example glue, welds, solderings, etc. the
width 11 needs to be adapted to the interconnecting characteristics of the
fastening means 5 such that the width 11 needs to be increased or can be
decreased in order to offer a sufficient interconnection of the first 3 and
the
second 4 edge.
The width 11 can for example be as small as 1mm for some
types of fastening means 5 or the width 11 can extend up to for example
substantially the entire width of the sides between the vertices 13 and/or
more
than 100% of the circumference of the hollow cylindrical body 6 in which case
the side wall 7 comprises at least two layers wound around the longitudinal
direction of the street pole 1, preferably of the first part 18 of street pole
1.
The inventor has found that an increased width 11 of the
overlap 2, increases the friction between the first 3 and the second 4 edge of
the overlap 2 so that additional fastening means 5 such as bolts, nuts,
rivets,
screws, nails, staples, glue, welds, solderings, etc. can be avoided.
Moreover,
the increased width of the overlap 2 allows that the fastening means 5, if
they
are for example distinctly provided to the street pole 1, are positioned in a
staggered position with respect to each other along longitudinal direction of
the
street pole 1.
The width 11 of the overlap 2 can be substantially constant
along the longitudinal direction 8 of the street pole 1, especially if it is
for
example expressed as percentage of the sides between two vertices 13,
preferably of the first part 18 of street pole 1. This is however not critical
for the
invention and the width 11 can change along the longitudinal direction 8 of
the
street pole 1, preferably of the first part 18 of street pole 1.
The hollow cylindrical body 6 preferably is made of a bendable
material such as for example metal. This way the hollow cylindrical body 6 can
be made by bending a sheet 14 of the bendable material, preferably a metal
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sheet, into the desired shape having the desired cross section. However, any
other material is possible as described above and the hollow cylindrical body
6
can for example also be cast.
In case the hollow cylindrical body 6 has a polygonal cross
5 section, more preferably a regular polygonal cross section, as shown in
figure
1, the hollow cylindrical body 6 preferably is made by bending at least one
sheet 14 of the bendable material along longitudinal folding lines forming the
vertices 13 of the polygonal cross section. Preferably, these folding lines
are
created by pushing a longitudinal edge into and/or along the sheet of bendable
10 material. Any other way of making the cylindrical body is however
possible.
For example, the cylindrical body 6 in this case has an uneven
number of vertices and the overlap 2 is provided in between two adjacent
vertices 13, the last folding line being created being the folding line
opposing
the overlap 2. The inventor has found that such bending of the sheet 14 of
15 bendable material allows the longitudinal edge to be retracted more
easily,
after being pushed into and/or along the sheet 14 of bendable material in
order
to create the folding line, in between the first 3 and the second 4 edge
before
the overlap 2 is created. However, the cylindrical body 6 can also comprise an
even number of vertices.
In case the cylindrical body 6 has a round cross section, the
cylindrical body 6 preferably is made by rolling at least one sheet 14 of
bendable material, preferably metal.
Although the cylindrical body 6 preferably is made of a single
bent sheet 14, as shown in figures 3 and 5, the cylindrical body 6 can also be
made of several bent sheets 14 forming the different pieces of the
circumferential side wall 7, as discussed above.
Preferably, the side wall 7 and the fastening means 5 are
provided to split open along the overlap 2 by breaking away the fastening
means 5 upon impact at a place of impact 15 on the street pole 1, the
cylindrical body 6, being provided at the place of impact 15.
Preferably, the side wall 7 and the fastening means 5 are
provided to split open along the overlap 2 by breaking away the fastening
means 5 upon impact with a vehicle 16. The vehicle 16 can be any vehicle 16,
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preferably motorised, known to the person skilled in the art such as a car,
truck, motorcycle, etc.
This is especially beneficial for street poles 1, preferably first
parts 18 of street poles 1 which are provided to be fixed to the ground since
such poles 1 are generally provided next to roads on which traffic passes to
street pole 1.
With impact in the context of this application is for example
meant an impact caused when such a vehicle 16 drives into the first part 18 of
street pole 1 for example more than 0 km/h, more than 5 km/h, more than 10
km/h, more than 20 km/h or more than 30 km/h or even higher. However, the
side wall 7 and the fastening means 5 must be such as to resist normal forces
acting on the first part 18 of street pole 1 such as for example varying
winds,
relative small impacts caused by for example parking vehicles, etc. when the
first part 18 of street pole 1 has not been impacted by vehicle 16.
Examples of a vehicle impacting such a first part 18 of street
pole 1 are shown in figures 4 and 6a ¨ 6d.
When the first part 18 of street pole 1 is impacted, the first 3
and the second 4 edge of the side wall 7 move away from each other as
described and the fastening means 5 are broken away from the edges 3, 4.
When the impact is large enough, the first and second edge 3, 4 move even
further away until subsequent fastening means 5 are broken away. This
process is repeated until the impact has been fully absorbed. Due to the
impact the first and the second edge 3, 4 can keeping moving away from each
other until the circumferential sidewall 7 is fully unfolded and becomes
substantially flat.
Preferably, the first part of street pole 1 is provided not to break
away from its substrate upon impact but to remain fixed to its substrate,
allowing the energy of the impact to be absorbed until the speed of the
vehicle
16 impacting the street pole 1 has been significantly reduced. Therefore,
after
impact of the vehicle 16 with the first part 18 of street pole 1, the risk
that the
vehicle 16 impacts a further obstacle after impacting the first part 18 of
street
pole 1 is significantly reduced. In order to achieve such a connection of the
first part 18 of street pole 1 to the substrate, the first end preferably is
cast into
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cement, as discussed above. However, this is not critical for the invention
and
any other connection of the first part 18 of street pole 1 to the substrate
may
be used.
A vehicle 16 impacting the street pole 1 causes the first part 18
of street pole 1 to be impacted at the place of impact 15. The preferred
hollow
cylindrical body 6 then splits open at the place of impact 15. Subsequently,
when the impact is large enough the place of impact 15 moves along the
longitudinal direction 8 of the street pole 1 as shown in figures 6a ¨ 6d such
that a part of the first part 18 of street pole 1 moves under the vehicle 16
while
another part folds in the direction of the vehicle 16, as shown in figure 6d.
By
keeping the first part 18 of street pole 1 fixed to the ground, the kinetic
energy
of the vehicle 16 can be absorbed until the speed of the vehicle 16 is
reduced.
While the place of impact 15 moves along the longitudinal direction 8 of the
first part 18 of street pole 1, the first and second edges 3, 4 at the moving
place of impact 15 keep moving away from each other along the width
direction 11 of the overlap 2 such that the fastening means are broken away
and the overlap 2 splits open along the longitudinal direction 8 until the
speed
of the vehicle 16 has been significantly reduced. Preferably, the speed of the
vehicle 16 after impact with the first part 18 of street pole 1 is reduced
such
that it is less than 50 km/h measured after 12m after the initial impact.
Upon impact of a vehicle 16 on the first part 18 of the street pole
1, the impact absorbing street pole 1 absorbs at least part of the energy
created during the impact, reducing the deformation of the vehicle 16 upon
impact and resulting in a less aggressive drop in acceleration with respect to
time for the occupant(s) of the vehicle 16 and the elongated extension 17
disconnects from the first part 18 of the street pole 1, as shown in figure
6b,
such that for example the clasp-knife effect, wherein the street pole 1 bends
and the bent part of the street pole 1 crushes the vehicle 16, as for example
shown in figure 4, is reduced, as illustrated in figures 6 d. Figure 6d no
longer
shows the extension 17 as it has fallen, for example, next to the vehicle 16.
Since for example the bent part of the street pole 1 is reduced in length
compared with the street poles of the prior art, and only comprises the first
part
18 of the street pole 1 both the length of the pole 1 and its momentum when
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impacting the vehicle 16 are reduced, limiting the damage to the vehicle 16
and the risk of injuries for the occupants of the vehicle 16.
As the extension 17 disconnects from the first part 18 after
impact, the material of the extension 17 is less critical for the invention
and can
be substantially chosen by the person skilled in the art in function of the
envisaged application. The extension for example can be a hollow part, for
example a bent metal sheet, or even solid, for example wood.
The part that folds in direction of the vehicle 16, if present, can
fold onto the vehicle 16 or next to the vehicle 16. When the street pole 1 is
provided to fold next to the vehicle the occupants of the vehicle are even
more
protected.
The preferred deformable cylindrical body 6 must be provided at
the place of impact 15 in order to be able to absorb the energy of the impact.
Therefore, the preferred cylindrical body 6 provided to split open upon impact
is preferably provided at a height which can be impacted by vehicles 16. The
cylindrical body 6 is for example provided near the substrate. However, the
cylindrical body 6 preferably extends along substantially the entire length of
the
first part 18 of street pole 1 along the longitudinal direction 8, as shown in
figures 1 and 2. When the overlap 2 extends along substantially the entire
length of the street pole 1, larger impacts can be absorbed since the
absorption of the impact by the splitting open of the cylindrical body 6, the
braking away of the fastening means 5 and the unfolding of the cylindrical
body 6 can continue along the entire length of the street pole 1. A same
effect
can also be achieved when the first part 18 of street pole 1 is formed of
subsequent cylindrical bodies 6, as shown in figure 2.
The cylindrical body 6 in such an embodiment preferably is
made from metal, such as for example steel, aluminium, etc. More preferably
the cylindrical body 6 is made from steel.
Preferably, material of the side wall 7 of the cylindrical body 6
has a yield strength Re of between 50N/mm2 ¨ 700N/mm2, preferably
200N/m m2 ¨ 550N/mm2, more preferably 330N/mm2 ¨ 420N/mm2.
Preferably, the material of the side wall 7 has a tensile strength
Rm of between 50N/mm2 ¨ 1350N/mm2, preferably 350N/mm2 ¨ 1050N/mm2,
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more preferably 600N/mm2 ¨ 700N/mm2, more preferably at least 410 N/rnm2,
for example 410 N/rnm2 - 700N/mm2.
Preferably, the material of the side wall 7 has a minimal
elongation before breaking A80 of at least 5%, preferably at least 15%, more
preferably at least 20%.
Preferably, the side wall 7 has a thickness of between 20mm ¨
0.5mm, preferably 10mm ¨ 1mm, more preferably 5mm - 1mm, even more
preferably 2mm.
Preferably, the cylindrical body 6 has a diameter 12 at the place
of impact 15 of between 50mm ¨ 500mm, preferably 150mm ¨ 400mm, more
preferably 200mm ¨ 350mm.
Preferably, the width 11 of the overlap 2 is at least 0.1%,
preferably maximal 100%, more preferably between 0.1% and 10%, most
preferably between 2% and 3.5% of the circumference of the cylindrical body
6.
A first example is a first part 18 of the street pole 1 consisting of
a single cylindrical body 6 having a length of about 6 ¨ 7m, a diameter of
about
320mm near the first end of the first part 18 of street pole 1 and a
substantially
constant width 11 of the overlap 2 of 20mm which is 2,6% of the diameter 12
near the first end.
Another example is a first part 18 of street pole 1 consisting of a
single cylindrical body 6 having a length of about 10m, a diameter of 208mm
near the first end of the street pole 1 and a substantially constant width 11
of
the overlap 2 of 20mm which is 3,06% of the diameter 12 near the first end.
According to a further example a first part 18 of the street pole 1
consisting of a single cylindrical body 6 having a length of about 8m of which
2m is put into the ground, a diameter of about 322mm near the first end of the
first part 18 of street pole 1 at the ground level. The elongated extension
has a
height of about 14m. The elongated extension 17 and the first part 18 are
provided such that the elongated extension 17 is slid over the first part 18
with
the diameter of the first part 18 at the location where the elongated
extension
17 is slid over it is about 234mm and the diameter of the elongated extension
17 at that location being about 260mm and the first part 18 and the elongated
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extension 17 overlapping for about 500mm. The total height of the street pole
1 therefore is about 21.5m of which about 2m is put into the ground. In such
an embodiments, preferably, the hollow cylindrical body 6 has a polygonal
cross section, for example, a regular convex nonagon polygon with for
5 example three overlaps 2, with 3 vertices 13 or two sides between
vertices 13
in between the overlaps 2.
Preferably, the fastening means 5 have a shear strength, this is
the strength in width 11 direction of the overlap 2, of between 2000N ¨ 7000N,
preferably 3000N ¨ 6000N, more preferably 4000N ¨ 5000N, most preferably
10 4100N ¨ 4500N.
Preferably, the fastening means 5 are rivets since the inventor
found that they offer a good and easy interconnection of the first and the
second edge 3, 4 while being provided to brake away when the first and the
second edge 3, 4 move away from each other and allowing an easy
15 interconnection of the first and the second edge 3, 4. However, any
other
fastening means 5 can be used instead, as described above.
The first part 18 of street pole 1 may be placed such that the
width 11 of the overlap 2 extends substantially along a direction
substantially
parallel to the direction of oncoming traffic.
20 More specifically the width 11 of the overlap 2 extends
substantially along a direction having an angle of between 00 ¨ 900, 00 -
1800,
0 - 45 , preferably 10 ¨ 30 , more preferably 15 ¨ 25 , most preferably 20
with the direction of oncoming traffic.
The overlap 2 can however also be provided in any other
possible direction. The first part 18 of the street pole 1 can for example be
placed such that the width 11 of the overlap 2 extends substantially along a
direction which is substantially perpendicular to the direction of oncoming
traffic or any other possible direction.
