TØNDEVOLD, Tore (Lofthus terrasse 11, 0588 Oslo, N-0588, NO)
FOSSE, Jan (Øygardvn. 2B, 1357 Bekkestua, N-1357, NO)
TØNDEVOLD, Tore (Lofthus terrasse 11, 0588 Oslo, N-0588, NO)
C l a i m s
1. Yielding mast (10) supporting means (11) requiring supply of electricity, where the mast (10) in a collision with a moving body, such as for example a vehicle or a plane or the like, is configured to yield as much as possible, thereby at least minimizing injury to a person and/or damage to the moving body, said mast (10) at its lower end being fixed to a foundation (12) by means of a supporting foot plate (13), c h a r a c t e r i z e d i n that the mast (10) is attached to the foot plate (13) in such manner that if hit by a moving body the mast (10) is bent and yields, and that an electrical contact (18) is attached to the mast (10) and the foot plate (13) in such way that the power is cut off in a collision without exposing the moving body and/or personnel to electrical impact or sparks as a consequence of the collision.
2. Yielding mast (10) according to claim I^ ■ wherein a first plug unit (25) is fixed to the foot plate (13) while a second plug unit (24) is connected to the mast (10) .
3. Yielding mast (10) according to claim 1 or 2, wherein the first plug unit (25) which is fixed to the foot plate (13) is fixed to the lower surface of the foot plate (13), so that said first plug unit (25) will be protected in a collision.
4. Yielding mast (10) according to one of the claims 1- 3, wherein the connection between said two plug units (24,25) is configured in such way that the plugs (24,25) are separated independent upon the direction from which the collision occurs.
5. Yielding mast (10) according to one of the claims 1-
4, wherein the second plug unit (24) is fixed to the mast (10) at the lower end of the mast (10) .
6. Yielding mast (10) according to one of the claims 1-
5, wherein a split line between the two plug units (24,25) more or less coincides with the upper surface of the foot plate (13) .
7. Yielding mast (10) according to claim 6, wherein the current conducting parts of the first plug unit (25) are protected so that the possibilities of contact between said parts and a person or a moving body involved in the collision at least is reduced.
8. Yielding mast (10) according to one of the claims 1-
7, wherein the first plug unit (25) is provided with flanges (26) extending laterally outwards from the said plug unit (25) , said flanges (26) being intended to rest against the lower surface of the foot plate (13), thereby preventing the plug unit (25) from moving upwards with respect to the foot plate (13) .
9. Yielding mast (10) according to one of the claims 1-
8, wherein the foot plate (13) is provided with a plurality of holes (22) extending through the foot plate
(13), intended to receive one or more plugs (18,24,25) .
10. Yielding mast according to claim 9, wherein the holes extending through the foot plate (13) are arranged in the vicinity of each corner of the mast (10) . |
COMPLIANT SUPPORT
The Technical Field
The present invention relates to a yielding mast which supports means requiring supply of electricity, the mast when hit by a moving body, such as a vehicle or an aircraft or the like, to a largest extent is configured to yield in order to at least reduce injury to persons involved and/or damage to the moving body. At its lower end the mast is fixed to a foundation by means of a foot plate.
Background for the Invention
Use of yielding masts is important in order to achieve traffic safety in areas where movable bodies, such as vehicles or aircrafts, passes by or moves over such masts .
Use of yielding masts is an important feature for traffic safety on the roads. How serious an accident with a vehicle may be for the persons involved, and also for the vehicle involved, may be influenced by the behavior of the structural elements of the traffic accessories during the collision. Based on safety considerations such structural elements of the traffic accessories should be designed and constructed so as to yield or easily break off if hit by a moving body.
It is established standards with respect to functionality and testing of such structural elements, the structures being classified into high energy absorbing units (HE units) ; low energy absorbing units (LE units) ; and non- energy absorbing units (NE units) . Common for all such units is that there exits large possibilities that the units may be subjected to excessive damages. The terms HE, LE and NE are defined in more details in NS-EN 12767.
Further, there is an increasing demand of traffic information along roads and motorways. Further, there is a requirement that such information shall be as visual and readable from long distance possible. This implies that there is a requirement of large, illuminated signs which either shall be places along the road side or placed on gantries or semi-gantries above the road. Such large information boards require supply of electricity. At the same time, the mast and/or gantry must be so robust that the mast or gantry will be able to withstand the environmental forces caused by wind or the like acting on the mast or the gantry and on the sign boards.
The invention is also suitable for use in other areas, such as for example as light masts or the like for aviation purposes, marking the direction of a runaway at an airport.
For supply of electricity to the installations on such masts or gantries, it is known to use cables from a electricity source, the cables being trenched in the ground, leading to the foundation of the mast, and where the cables are routed up through the foundation to a connection box inside the mast at a level above the ground. At such level, one or more conductors from the installation on the mast is/are connected to said supply line (s) .
Summary of the Invention
An object of the present invention is to provide a mast with electricity supply eliminating or at least reducing the risk of inflicting injury to personnel or causing damage to the moving body at a collision with the mast .
Another object of the invention is to provide means for attaching the mast to a foundation with a power
supply, securing that the attachment means and the power connection yield in such way that the probability of imposing damage on the moving body and/or persons involved is eliminated or at least substantially reduced. A still further object of the invention is to provide and utilize a connector in a power supply circuit which, independent upon the direction from which the collision occur, will be disconnected without causing any formation of sparks during or after the collision. A still further object of the invention is to provide a solution where re-installation or possibly repair after a collision is as simple and cost effective as possible.
The objects of the solution according to the invention are obtained by the treats defined by the independent claim.
According to the invention, the mast is fixed to the foot plate in such way that the mast during a collision at least is bent and yields. Further an electrical connector is attached to the mast and the foot plate in such way that the electricity supply is cut off as a consequence of the collision, without exposing persons involved or the moving body to electrical current.
According to one embodiment, a first unit of the plug is rigidly fixed to the foot plate, while a second unit is attached to the mast. The first plug unit may preferably be attached to the lower surface of the foot plate, so that the said first plug unit is not affected by a possible collision.
The connection between the two plug units may preferably be configured in such way that the connection is cut off independent upon the direction of the collision.
According to one embodiment the second plug unit may be attached to mast at the lower end of the mast and that
the split line or the interface between the two plug units is more or less aligned with the upper surface of the foot plate.
It is advantageous if the current conducting parts of said interface of the first plug unit is protected so that the possibilities for contact between such current conducting elements and persons and/or moving bodies involved at least is reduced.
In order to facilitate attachment of the fist plug unit to the foot plate, said unit may be provided with outwards extending flanges in lateral direction, intended to rest firmly against the lower surface of the foot plate, thereby preventing the first plug unit from moving upwards through the hole in the foot plate. Further, the foot plate may be provided with a plurality of holes extending through the plate, said holes allowing installation of one or more plugs in different positions, if required. Said holes extending through the plate may for example be arranged in the vicinity of the corners of the mast.
For the solution according to the invention a connection is provided between the mast and a foundation, together with an electrical connection, both being able to yield, thus elimination or at least reducing the possibilities of causing injury to persons involved and/or damage to a moving body.
Further, a solution eliminating the possibilities of creation of sparks due to short circuiting of electrical conductors in the mast is also provided. By positioning the plug in connection with the foot plate, such placing will also protect the connector and at the same time make it easy to install the cables and possibly substi-tute damaged connectors subsequent to a collision.
A still further advantage according to the invention is that the connection is protected against vandalism and other types of unauthorized tampering, and that a more simple installation is provided together with a solution which makes it practical to assemble.
Short Description of the Drawings
An embodiment of the invention shall be described in detail below, referring to the accompanying drawings, where:
Figure 1 shows schematically a mast for traffic lights, supported by a foundation by means of the plate according to the invention;
Figures 2a - 2c show schematically a view seen from above of three different types of foot plates according to the invention;
Figure 3 shows schematically a vertical section through the lower part of a mast according to the invention, where the plate and an electrical plug in connected condition also are shown;
Figures 4a and 4b show schematically a view of the lower end of a mast during a collision where the movable vehicle hits the mast high up above the ground from two opposite directions; and Figures 5a and 5b show schematically a view of the lower end of a mast during a collision where the movable vehicle hits the mast at a lower level than shown in Figure 4, from two opposite directions.
Detailed Description of the Invention
Figure 1 shows a typical mast 10, supporting traffic lights 11. The mast 10 is supported by the ground by means of a foundation 12, dug into the ground, the foundation 12 for example being made of concrete. Four threaded irons or
bolts 14 may for example extend upwards from the foundation 12. Further, the foundation 12 may be provided with a hole or channel 15 extending through the entire foundation 12. Cables 19, both for high voltage and/or low voltage electricity, extend through said hole or channel 15, such electricity being supplied to the traffic lights 11 on the mast by a power source and/or a control unit (not shown) . The mast shown is of a type which is traded under the trademark Lattix® by the company Lattix AS. The mast is at its lower end fixed to the foundation 12 by means of the threaded bolts and nuts 17. Electrical cables 16 extend from the lower end of the mast 10 and up to the traffic lights 11. A connection 18 connects the cables 19 coming up through the foundation 12, the cable 16 extending further up through the mast 10. Such connector may have several shapes and embodiments and may be placed in several positions, and still functioning in accordance with the objects of the present invention. Such position of the connector may protect the cables against being tampered with, against UV-rays and against impact from collision. Further, the cables may be positioned in a cable duct or in a closed duct.
The mast 10 is fixed to the plate 13 in such way that the mast 12 may be removed from the plate 13 if subjected to a collision. The mast 10 is attached to the plate 13 by means of bolts.
Figures 2a-2c show horizontal views of three different embodiments of a foot plate 13. Figure 2a shows a foot plate 13 having a square shape, while Figures 2b and 2c show foot plates having a triangular shape. Figures 2a and 2c indicates a mast 10 assembled of profiles which are laterally pulled apart for formation of a truss work, while Figure 2b shows a hollow, cylindrically shaped mast 10. As shown in the Figures the foot plates are at their
corner, formed with oblong holes 20, extending through the plate, intended to receive the threaded bolts 14 in the foundation 12. The holes 20 are made oblong and are configured in such way that it will be possible to adjust the position of the mast 10 with respect to the foundation 12 to a certain extent. As indicated in Figure 2a the plate 13 shown is intended to be used for fixation of a mast 10 having a square cross sectional area and being provided with four corner profiles 21. From a clarity point of view the braces of the mast profile are not shown. The foot plate 13 shown is provided with four centrally arranged openings 22 extending through the entire plate, where a connector plug 18 is occupying one of the openings 22. As shown in Figure 2a, the conductor 16 is covered by a U-shaped jacket 40, which together with the corner of the profile form a protection for the conductor 16.
The plate 13 may alternatively have a triangular shape for those cases where the mast 10 has a triangular profile. Alternatively, the plate 13 may have any suitable shape without deviating from the inventive concept.
The dotted lines in Figures 2b and 2c indicate the vertical opening 15 through the foundation 12.
Figure 3 shows schematically a vertical section through the lower part of a mast 10 with a foundation 12 according to the present invention. The foot plate 13 is fixed to the foundation 12 by means of threaded bolts 14 and nuts 17. As shown in the Figure the foundation 12 is also provided with a centrally arranged opening 15 extending trough the foundation, forming a channel for housing a conductor 19 for supply of electricity.
The plate 13 according to the embodiment shown is provided with only one opening 22, extending through the plate, configured for receiving a plug 18. The plug 18 is
a two-part plug, provided with a split line 23, splitting the plug in an upper plug unit 24 and a lower plug unit 25. The lower plug unit 25 is provided with sideways projecting flanges 26, configured to rest against the lower surface of the plate 13, so that the lower plug unit 25 is prevented from moving up and out through the opening 22. As indicated in Figure 3, the split line 23 is more or less aligned with the upper surface of the plate 13. The upper plug unit 24 and the lower plug unit is clamped together by means of a clamping means 42 of any suitable type, establishing a water tight connection, but where the clamping force is not so great that the upper plug unit 24 is prevented from being released from the lower plug unit 25 if the mast 10 is hit by a moving body. The entrails of the plug 18 may be of any suitable type securing electrical contact between the various conductors (not shown) entering the lower plug unit 25 and the conductors leaving the upper plug unit 24. The transition between the two plug units 24,25 may be provided with sealing means, such as for example O-rings . Further, said transition may also be covered by a surrounding jacket. The connector 18 is covered by a housing 41, attached to the upper surface of the plate 13.
Figure 4a and 4b show schematically a situation where the lower end of a mast 10 is hit by a force K H in two opposite directions, caused by a moving body. In such case the laterally acting force acting on the mast 10 will tear the bolts off, upstream of the direction of collision, but also more or less downstream, so that the mast 10 is tipped sidewise in the direction of the force K H , while the foot plate 13 more or less remains standing unaffected in the its position. Since the lower plug unit 25 is fixed to the foot plate 13 by means of the flanges 26, while the upper plug unit 24, at least as a consequence of the
fixing of the conductor 16 to the mast 10, the upper plug unit 24 will move together with the mast 10. As a result, the contact between the conductors in the two plug units 24,25 will be broken in a controlled manner. Figures 5a and 5b show a case where the mast 10 in two diametrically directions, is hit at a lower level than the case shown in Figures 4a and 4b. For the case shown in Figures 5a and 5b both the front and rear bolt locking the mast 10 to the foot plate 13 are cut off as a consequence of the collision force K H , so that the upper plug unit 24 is forced sideways with respect to the lower plug unit 25. Hence, the electric contact is broken. Also in this case the lower plug unit 25 will remain in its position within the recess 22 in the foot plate 13, since the flanges 26 do not allow this plug unit 25 to move upwards.
For repairing activities after a collision, the mast 10 is removed and replaced by a new mast 10, equipped with the necessary cables and a corresponding upper plug unit 24. In many cases the foot plate 13 with its supply cables 19 and the attached lower plug unit 25 will be intact.
The plug units 24 and 25 may preferably be formed so that the cables 16,19 to a certain extent contribute to the splitting of the connection in a controlled manner during a collision. The entrance of the lower plug 24 is angled towards the centre of the foundation, while the exit of the cable 16 in the upper plug unit 24 is correspondingly angled sideways towards the corner of the mast 10. It should be appreciated that the upper plug unit
24 is so shaped and configured that the plug unit in a controlled manner may be released from the lower plug unit
25 both in vertical direction and in any sideways direction.
At least the upper plug unit 24 may be covered by a housing 41, so that unauthorized personnel is denied
access to the plug or at least made much more difficult. In the cable system a separate circuit breaking the power supply immediately when the contact between one or more of the conductors through the plug 22 is broken or short circuited.
According to a preferred embodiment the cable 16, extending from the upper plug unit 24 and upwards along the mast 10, may be attached and extend along the side of the mast facing towards the prevailing direction of collision, while the plug 18 is arranged as closed as possible to such side or edge. In a possible collision this will contribute to establishing the force required to split the two plug units 24,25 from each other.
Even though the embodiments shown are based on use of flanges 26, it should be appreciated that any locking method of the connection 18 or the female plug 24 may be used, such as tight fit of the plug unit 24 in the hole, bolting or the like.
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