The present invention concerns a track structure which is adapted to extend along a selected route and its assigned series-oriented road sections. The track structure comprises one or more elongated tracks, which are assigned to each road section and are limited by two side walls and a bottom wall, the bottom wall being adapted to support one or more current-feedable and energizable electrical conductors. Technical Background of the Invention

A system for electrical propulsion of a vehicle along a road is known from WO 2010/140964. This system has electrical conductors in the form of energizable rails embedded in elongated tracks or canalizations in the road. The vehicle has a collector shoe which, upon contact with the rail, allows transfer of electric current between the rail and the vehicle, in order to drive the electric motor of the vehicle and, in such a way, also the vehicle. At the upper edge of the track closest or adjacent to the roadway, a connection to earth potential is arranged.

The route is divided into different consecutive series-oriented, electrically separated, road sections, whereupon the energizable rails of each individual road section are energized only in connection with a vehicle with its collector shoe passing the road section in question.

Roads are generally constructed in different beds or layers with compacted filling consisting of gravel or stone chippings. The top layer or layers usually consist of concrete or asphalt in order to obtain an even and strong surface adapted to the es- timated traffic load on the road. In spite of the side walls and the bottom wall which define the track being arranged embedded in the road and thus surrounded by asphalt, concrete and/or filling, they are subjected to large compressive load by heavy traffic, such as lorries and buses.

The walls of the track preferably consist of materials which do not conduct cur- rent, which materials often have a limited strength, as regards pressure, tension and/or impact. In large compressive load, therefore, there is a risk of the track being deformed, above all laterally because of its U-shaped profile. Lateral deformations of the track represent a great danger to passing vehicles, since collector shoes may risk getting caught in the track.

In case the side walls of the track are compressed entirely, contact between the embedded electrical conductor and the collector shoes of the vehicles is prevented and power supply of vehicles is set out of operation.

If the side walls of the track instead are pulled apart, there is a risk of the electrical conductor being able to move laterally, which may cause an unsatisfactory contact between the embedded electrical conductor and the collector shoes of the vehicles. Dirt and/or water will also be able to be accumulated easier in the track, which may cause down periods.

US 3,848,712 discloses a device for supplying a vehicle with electric current and consists of a rail assembly comprising an outer, hollow rail of metal having a longitudinal slot and at least one inner profile made from an insulating material with resilient properties. The inner profiles have longitudinal guides for current carrying rails.

WO 2011/123049 A1 discloses a track structure comprising elongated tracks, each one of which is limited by two side walls and a bottom wall. The tracks are adapted to support current-feedable and energizable electrical conductors. An outer cover of metal is arranged on the outside of the side walls and the bottom wall in relation to the tracks.

During the winter half in areas with a cold climate and temperatures below 0 °C, water in the ground will freeze, so-called ground frost. When water freezes to ice, the volume increases up to 9 %. The expansion of the ice may cause damage to technical installations in the ground, for example to roads and building foundations. The frost in the ground under a road section may thus give rise to large movements of the road section in the vertical and/or lateral direction. A track structure which is embedded in the road section in question then runs the risk of being pressed up and losing the contact with the roadway. Naturally, a protruding track structure in the road represents a large danger to traffic. Therefore, it is very important that the track structure is kept in place in spite of movements of the road section in the vertical and/or lateral direction as a consequence of frost heaving or of other reasons.

Therefore, there is a need to develop track structures with greater strength which guarantee a power supply of passing vehicles and which are kept in place within its road section Such a track structure should be able to resist the compressive forces that, for instance, vehicular traffic and/or ground frost will exert on the track structure without being deformed other than elastically, and thus being able to recover its original shape after said compressive load.

Summary of the Invention

The object of the present invention is to provide a track structure with a high strength which guarantees a power supply of passing vehicles and which is kept in place within its road section.

This is achieved by a track structure according to claim 1 , adapted to extend along a selected route and its assigned series-oriented road sections, intended to be able to receive a vehicle-related current-collecting means, and comprising one or more elongated tracks, which are assigned to each road section, the track comprising two side walls and a bottom wall adapted to support current-feedable and energi- zable electrical conductors, said track structure comprising an outer cover for forming a strong shell which surrounds the two side walls and the bottom wall, said outer cover comprising one or more through-going recesses in a plane substantially perpendicular to the longitudinal direction of the track structure.

By allowing the side walls of the track and bottom wall to be surrounded by an outer cover, a track structure with a high strength which prevents lateral deformations of the track is achieved. Preferably, the outer cover has, in a cross-section, two paral- lei and vertically extending wall portions integral with a horizontally arranged bottom portion, which together form wall sections. The recesses divide the outer cover into shorter subsections which can follow the movement of the road in the vertical direction without the entire track structure running the risk of projecting from the road.

Preferably, the outer cover consists of a rigid material. In a preferred embodi- ment, the outer cover comprises metal, such as steel or aluminium-based alloys, polymers and/or plastic materials with a high strength against pressure, tension and/or impact. It is also feasible that the outer cover is made from a composite material.

In accordance with one embodiment, the outer cover is formed of an electrically conducting material as well as connected to earth.

In an alternative embodiment, the side walls and/or the bottom wall comprise ceramic, plastic- or polymer-based material. In another embodiment, the extension of the recesses in the longitudinal direction of the track structure is within the range of 1 mm to 5 cm, preferably within the range of 2 to 10 mm.

In a further embodiment, the recesses are incorporated at regular intervals along the track structure. The distance between two consecutive recesses may suitably be selected to be between 0.5 m and 2 m, based on expected frost heaves within the road section in question.

In an alternative embodiment, the recesses are filled with a flexible material to prevent gravel and dirt from being accumulated in the recesses. The flexible material may, for instance, be asphalt, rubber, plastic, or mixtures thereof and follows the movements of the outer cover in compression and expansion of the recesses.

In another embodiment, the track structure may comprise a coupling element, preferably elastically deformable, arranged in a recess between two neighbouring subsections and adapted to connect the two adjacent subsections to each other. The coupling element may suitably be arranged in the upper end portion of the recess closest to the roadway of the road section. Alternatively, the coupling element may be arranged in the lower end portion of the recess farthest away from the roadway or in suitable place between the upper and lower end portions. In an alternative embodiment, the coupling element comprises a part of the wall section, which remains after the formation of the recess.

Brief Description of the Drawings

Figures 1 , 1 A and 1 B show in a perspective view vehicles propellable on a road section comprising a rail construction according to the present invention.

Figure 1 C schematically shows two vehicle-related energy sources and a third source of energy external to the vehicle.

Figure 1 D shows a power/time diagram (P/t) illustrating the passage of the vehicle along a roadway, its route and its road section.

Figure 2 schematically shows a vehicle-related electrical arrangement.

Figure 3 shows in an end view a vehicle, having a downwardly directed contact means in a co-operation with the energizable electrical conductors assigned to the road section.

Figure 4 schematically shows an electrical arrangement for a number of series- oriented road sections. Figure 5 shows in a perspective view a track structure according to the present invention.

Figure 6 shows a cross-section of the track structure according to Figure 5. Figure 7 shows in another perspective view the track structure according to Fig- ure 5.

Figure 8 shows in a perspective view a track structure according to the present invention in connection with movement in the vertical direction of two subsections.

Figure 9 shows in a side view the track structure according to Figure 8 in connection with movement in the vertical direction.

Detailed Description of the Invention

The mechanical arrangement will be described below in more detail with reference to the figures. However, the invention should not be considered limited to the embodiment or embodiments shown in the figures and described below, but may be varied within the scope of the claims.

Accordingly, Figure 1 A shows a system "S" adapted for the conveyance of an electric vehicle 1 , propellable by one or more batteries or a battery kit, along a route 2 and its road section 2a1 as well as 2a1'.

Here, the vehicle 1 is exteriorly an "A-Ford", but here, the same is converted to a battery-operated vehicle, with a continuous access to an external, a third, source of energy, here designated "s1", "III".

The vehicle 1 should then comprise a controlling arrangement 3 (not shown) or a control equipment, so that a driver "F" (not shown) can convey and control the vehicle 1 along said route 2 and its road section 2a1.

The vehicle 1 could also embrace a gearbox and other parts and details that are required for the conveyance of the vehicle, but since these parts are well known to a person skilled in the art, these will not be described in detail.

However, an electrically driven vehicle 1 does not need any gearbox, since a speed regulation and a power output can be effected via known electrical and elec- tronic circuits.

Figure 1B shows, in the same way as in Figure 1A, an electrically propellable lorry 1b, having a coupled trailer 1c, along the route 2, 2a and its assigned road section 2a 1. Figure 1C now clearly shows two vehicle-related and vehicle-associated energy sources, here designated "I" and "II", a "first" in the form of a diesel generator "G", a "second" in the form of a battery or a battery kit "B", and a "third" source of energy "III" in the form of a source of energy oriented externally to the vehicle, here formed as, via connection means or switches, energizable parallel conductors or rails within the road sections, recessed in tracks and a cavity along the roadway or the whole route 2.

In Figure 1C, these are co-ordinated to a vehicle-related control circuit 100, which, depending on a supplied power to an electric driving motor 5, allows selecting all or a combination of the powering energy sources "I", "II" and "III", respectively. Here, the power regulation is illustrated as an accelerator pedal 100a, the movement of which up and down is connected to an actuation circuit "R2" within the control circuit 100, which in turn embraces a circuit "R1" distributing power and energy between the energy sources.

Figure 1D illustrates in a P/t (power/time)-diagram how a full power or reduced powers could be distributed and transferred for the passage of the vehicle along the different road sections 2a of a roadway or route 2 by means of the circuit "R1" and the actuation circuit "R2".

Between the instants of time ti-t ₂ , it is illustrated, in principle, how a full power output from the three energy sources "I", "II" and "III" can be realised, with the power output from the energy source "I" illustrated on top, the power output from the energy source "II" illustrated thereunder (slanting lines), and the power output from the energy source "III" illustrated at the bottom.

Between the instants of time t3— , there is illustrated, in principle, a reduced power output from the energy sources "I" and "II", while here, the energy source "III" is illustrated disconnected.

Between the instants of time ts-te, there is illustrated, in principle, a reduced power output from the energy sources "II" and "III"

During this time duration ts— t_s, full power can be drawn from the energy source "II" and a small surplus can be allowed to trickle charge the battery kit "II", "B".

The battery kit "B" and the second energy source "\\", but particularly the third energy source "III" should primarily, via the distributing circuit "R1", feed the motor 5, and for this purpose, it is required that the battery kit "II", "B" has accumulated an energy and in other respects is dimensioned to drive the motor 5 at full power. The battery kit "II"; "B" should primarily be trickle charged via the energy source "Ml"; "s1" and secondary be trickle charged or charged via the energy source "I", "G".

The energy or power from the energy sources "I" and "Ml" can be selected to be 5-30 % of the energy or power assigned to the energy source "II"; "B", such as about 25 %.

The supply voltage to the motor 5 can be selected to be +400 V DC and -400 V DC, i.e., the voltage value 800 V DC.

The proposed system "S" should then primarily comprise one or more, via each an electric motor 5 or motors, electrically drivable vehicles 1 , 1b, and where the re- spective vehicle has a power-distributing and/or power-regulating control loop "R1" within the control circuit 100, for the provision of a requisite power and/or a speed regulation via the actuation circuit "R2" and the accelerator pedal 100a.

The requisite output power should be provided primarily by the vehicle's internal energy source "M"; "B" and that secondary should be under trickle charging from the third energy source "III"; "s1". The route 2 is shown divisible into road sections 2a (2a1 , 2a2, 2a3; 2a1\ 2a2', 2a3'), where each one advantageously should be assigned an external source of energy "Ml", here illustrated as a number of electrical stations "s1".

One or both of the vehicle's external third energy source "III"; "s1" and/or the vehicle-associated first energy source "I"; "G" can be utilized, in order to thereby supplementary charge the battery kit "II"; "B" of the vehicle, during an adapted sequence of time of power output from this battery kit.

In addition to a driving of the vehicle 1 via the battery kits "M"; "B" and during a supplementing charging of the battery kit "II"; "B" along the road sections and the sta- tionary electrical stations "s1" or the third energy source "III", for the conveyance of the vehicle 1 across the road section 2a1 , a requisite additional power and energy may be supplied via the vehicle-associated energy source "I"; "G".

Figure 2 shows principally an electrical/mechanical connection arrangement "K" related to a vehicle 1 , (1b) with a schematically shown vehicle-related arrangement in the form of a control equipment 10, in order to direct a vehicle-associated connector or collector shoe 4 against and to an electrical contact with paired energizable lines, in the form of rails 4a, 4b, for a possible common parallel operation of an electric motor 5, from the battery kit "M"; "B" and/or from the stationary station "III"; "s1", and/or from the diesel generator "I"; "G". Here, the collector shoe 4 is related to a support 6, which vertically is movably arranged up and down via a first electric auxiliary motor 7 and laterally is movably arranged to and fro via a second electric auxiliary motor 8.

The means and the control of the auxiliary motors 7, 8 that are required for this movement by means of sensors are not shown in detail but are, however, in principle previously known and obvious to a person skilled in the art.

The auxiliary motor 7 and the auxiliary motor 8 are both actuatable in a reciprocating movement, where a first movement is activated via a first signal on a first conductor 7a and a first signal on a first conductor 8a, respectively, whereas a second (opposite) movement is activated via a second signal on the conductor 7a and 8a, respectively, while the instantaneous setting positions of the motors 7, 8 and carrier 6 are evaluated by one or more sensors (not shown) and indicated via a produced signal on a second line or conductor 7b and 8b, respectively.

These signals on the first conductors 7a, 8a are generated in a centrai process- ing unit or control circuit 100 by a control equipment 10, and signals on the second conductors 7b and 8b are produced within the same central processing unit 100, while utilizing position sensors (not shown).

The central unit 100 including the control equipment 10 is a complex unit, which, among other things, via a sensor 16 should be able to detect the presence of and the orientation of the conductors 4a, 4b, and after that lower the collector shoe 4, via the auxiliary motor 7, to an electrical contact with said conductors 4a, 4b, which here are illustrated as energized or vice versa.

Via a connection 10a to the central unit 100 and the actuation circuit "R2" thereof, the power and energy, which via the circuit "R1 " distributing the energy sources is fed to the motor 5, are regulated. For this purpose, it is required that the circuit "R1" is directly controlled by an accelerator pedal 100a (Figure 1 C) in order to, via the actuation circuit "R2", supply requisite power to the motor 5.

In the shown state, the collector shoes 4 conduct current and voltage from the energy source "s1 ";"HI" to the power and energy-distributing circuit "R1". This one or an actuation circuit "R2" detects, via the central unit 100, the power requirement of the motor 5 and primarily feeds the motor 5 with the power it needs according to the input signal on the connection or line 10a and generated output signal on the connection or line 10b, and thereby the stationary system "s1", "III" should be loaded and supplement the power and energy requirements via the battery kit "II", "B". A parallel connection of the vehicle's externally tapped-off power "III", "s1" and the vehicle's internally generated power "I", "G" and/or "II", "B" may here be realised via the control loops "R1" and "R2" and by means of the control circuit 100.

Via the line 10a, pieces of information about a desired speed and thereby asso- ciated power for the vehicle 1 are fed to the central unit 100, and via internal circuits (not shown) and the function "R2", "10", the circuit "R1" is activated via the line 10b.

Figure 3 shows, in an end view, a vehicle 1(1b) with its downwardly directed collector shoes 4 in a mechanical and electrical co-operation with the two live conductors or rails 4a, 4b assigned to the road section 2a1', as well as an earth connec- tion 4c.

Figure 4 shows an electrical connection arrangement "K1", wherein road sections after road sections 2a1 , 2a2 and 2a3 and 2a1', 2a2' and 2a3', respectively, which are electrically separated, with their station after station "s1", "s2", "s3" and "s1 ^' ", "s2"' and "s3"', respectively, can be activated and made live from one and the same parent charging source "III", 42, via connection means and switches 43a, 44a, and 45a for one route 2a, and 43a', 44a' ^' and 45a' for the counter-directed route 2b, as a vehicle 1 will pass along the road sections 2a, 2b separated electrically but coordinated with longitudinal tracks.

For this, a number of switches or connection means are required for a connec- tion and disconnection of the stations "s1", "s2" ... where this connection and disconnection can be effected via stationary sensors (not shown) related to the road section.

The present invention is based on the presumptions mentioned above and provides, according to Figure 5, a track structure intended to receive a vehicle-related current-collecting means 4 according to the above. The track structure comprises one or more tracks 51 , 52. The tracks 51 , 52 are arranged in parallel within each individual road section 2a1.

The design of the track structure is illustrated more clearly by the cross-section in Figure 6. Here is illustrated how the track 51 is limited by two parallel side walls 53, 55 and a bottom wall 54 and has an substantially U-shaped cross-section. Also the track 52 is limited by a similar structure. The tracks 51 , 52 are thus adapted to support current-feedable and energizable electrical conductors 4a, 4b arranged in the lower end portions of the tracks and resting on the bottom wall 54. The track structure comprises also an outer cover 60 which surrounds the side walls 53, 55 and the bottom wall 54. In a cross-section, the outer cover 60 has preferably two parallel and vertically extending wall portions integral with a horizontally arranged bottom portion, which together form wall sections. The outer cover is adapted to form a strong shell which prevents, among other things, the track from being deformed laterally upon strong compressive load. The outer cover 60 is dimensioned to be able to resist deformation forces from buses and lorries when these are passing and exerting compressive loads on the road section 2a1. Suitable materials for the outer cover may, for instance, be steel, aluminium-based alloy, polymer-based material, such as fibre-reinforced plastic or another composite material, or another hard-wearing material of desired strength.

Preferably, the outer cover is formed of an electrically conducting material, suitably selected from some of the above-mentioned materials, as well as connected to an earth connection in order to, in such a way, among other things, decrease the risk of undesired electric discharges.

The outer cover 60 may be provided with one or more through-going recesses or slits 61 perpendicular to the longitudinal direction of the track structure. The recesses 61 divide the outer cover 60 into a plurality of shorter, separate subsections 62, 64. The subsections 62, 64 can thus follow the vertical movements of the road section 2a1 caused by ground frost without the entire track structure projecting from the roadway.

The extension of the recesses 61 in the longitudinal direction of the track structure is within the range of 1 mm to 5 cm, preferably within the range of 2 to 10 mm. The size of the recesses 61 is adapted to the nature of the terrain and expected frost heaves within the road section 2a1 in question.

The recesses 61 may be formed on the outer cover 60 at regular, relatively short intervals, for instance 0.5 to 2 m. The distance between two recesses 61 is selected depending on the nature of the terrain and expected frost heaves within the road section 2a1 in question.

Figure 7 shows a preferred embodiment, wherein the recesses 61 may be filled with a flexible material 70 which follows the movements of the outer cover 60 in compression and expansion. The flexible material protects the track 51 , 52 by preventing accumulation of gravel and dirt, and comprises for instance asphalt, rubber or plastic. An alternative embodiment is illustrated in Figure 8. The recess 61 is filled with a flexible material 70. In the upper end portion 65 of the recess 61 , closest to the roadway of the road section 2a 1 , the subsections 62, 64 are connected by means of a coupling element 80. Alternatively, the coupling element 80 may be arranged in the lower end portion 66 of the recess, farthest away from the roadway of the road section 2a1. The coupling element 80 is rotatably arranged between the segments 62, 64 and allows movements around an imaginary horizontal axis perpendicular to the longitudinal direction of the track structure which intersects the recess 61 in the upper or lower end portion 65, 66. The coupling element 80 may, for instance, be a part of the wall section 60 closest to the upper or lower end portion 65, 66 which has not been removed in connection with the formation of the recess 61. The recess 61 may be formed by milling, cutting or another method suitable for the removal of the material of the wall section 60. The dimension of the coupling element 80 is, in such a case, selected to allow rotation of the subsections 62, 64 in relation to each other around the horizontal axis, but without the subsections 62, 64 being separated from each other.

Figure 9 shows in a side view a vertical movement of the subsection 64 in connection with a frost heave. When the road section 2a1 is affected by frost in the ground, the subsection 64 follows the vertical movement. By the coupling element 80, the subsection 64 is allowed to move in relation to the subsection 62 around the horizontal axis, but no displacement in the vertical direction arises. Accordingly, it is guaranteed that the track structure including its outer cover 60 follows the possible vertical movements of the road section 2a1 because of ground frost, without any part running the risk of projecting from the roadway of the road section 2a 1. The road sec- tion 2a1 is not expected to be subjected to continuous frost heaving during its service life, but only be affected by vertical movements on isolated occasions depending on climate and the nature and composition of the terrain.