State of the art

International patent application no. PCT/DK91/00146 (WO 91/18777) describes a transport system of the dual-mode type and with dual-mode vehicles which can drive on a tri¬ angular rail, separately or coupled, and as an individual electric car on an ordinary road.

All that is otherwise stated in the above application forms part of the subject application by this reference.

The main component of the transport system is the vehicle 1, which is shown in figs. 1 and 2 of the drawing, running either on a rail 2 of a triangular cross-sectional profile 7 and perhaps a particular brake rail 9 at the top of the rail 2. Each vehicle also has ordinary road wheels 8 for driving on a roadway 10.

Each vehicle 1 has a front end and a rear end where the front end has two substantially plane faces 3, 4 which meet at an angle along a horizontal line 5, and where the rear end has two substantially plane faces 3', 4' which likewise meet along a horizontal line 5, as shown, and otherwise as explained in the abovementioned international application.

Fig. 2 shows how the dual-mode vehicle 1 is transferred from rail driving, receiving current from the rail, to road driving on the roadway 10 as an independent electric ve¬ hicle on wheels 8 receiving current from conveyed bat¬ teries.

The vehicle is also provided with a downwardly facing groove 6 extending in the longitudinal direction and with a cross-sectional profile which substantially corresponds to

the cross-sectional profile 7 of the rail 2.

The vehicle 1 and the design thereof as well as the rail 2 and the design thereof will not be further described in the present application, reference being made to the abovemen- tioned international application.

When the vehicle 1 leaves the triangular rail, it will drive as an electric car with the inherent limited range or the capacity of the built-in battery/batteries. The range of such electric cars is of the order of 25-100 km depend¬ ent on the size of the batteries, the charging conditions thereof, the weight of the vehicle, road conditions etc.

Advantages of the invention

By designing a power unit for a dual-mode vehicle of the kind described in the introduction to claim 1 and as disclosed in the characterising part of claim 1, there is achieved an increase in the range when the vehicle drives as an independent vehicle on an ordinary road.

The longitudinal groove in the lower part of the vehicle, which is only used when the vehicle drives on the triangu- lar rail, is simply utilised. The range of the vehicle is thus increased without reducing the cabin space or any lug¬ gage space. The power unit is for example externally pro¬ vided with electrical terminals arranged at the correct height for electrical connection with the sliding contacts or the like used by the vehicle for drawing current from the rail. The power unit may thus supply current to the ve¬ hicle and increase the range by the amount of energy sup¬ plied by the unit.

By designing the power unit according to the invention as disclosed in the characterising part of claim 2 or the

characterising part of claim 3, it is possible to utilise the entire useful cavity of the groove in the vehicle with¬ out reducing the aerodynamic properties of the vehicle, without damaging the outer shape and design of the vehicle, and without the power unit in any way being in the way, neither by normal driving nor by controlled queue driving when the vehicles drive on the road in a line and closely behind each other.

The power unit according to the invention may be designed as disclosed in the characterising part of claim 4 in case the energy store does not contain energy of a type which can be directly used by the vehicle.

The power unit according to the invention may also by de¬ signed as disclosed in the characterising part of claim 5 such that it is simply a matter of an increase in the bat¬ tery capacity of the dual-mode vehicle.

Finally, the power unit according to the invention may be designed as disclosed in the characterising part of claim 6, whereby there is achieved a particularly substantial in¬ crease in the range of the vehicle when it is away from the current supply of the rail, in that it is well-known that motor fuel has a very high degree of energy density and that the energy content of the motor fuel can be converted into electic current at a reasonable efficiency.

If the power unit is designed as disclosed in the charac- terising part of claim 7, optimum utilisation of the avail¬ able space in the power unit is achieved and pollution etc. from the combustion engine is minimised.

The drawing

The invention will now be further explained with reference

to the drawing wherein

fig. 1 is a known dual-mode vehicle adapted as a rail ve¬ hicle as well as a road vehicle,

fig. 2 is the vehicle in fig. 1 during the transitional phase from rail driving to road driving,

fig. 3a,b is the principle of the connection of a dual- mode vehicle with a power unit according to the invention,

fig. 4 schematically shows the power unit according to an embodiment of the invention, and

fig. 5 is a plane section V-V in fig. 3a in an empty power unit.

Explanation of the embodiment

Figs. 1 and 2 of the drawing showing a dual-mode transport system are explained above and will not be further mention¬ ed in this context.

In figs. 3a,b the dual-mode vehicle 1 is shown driving on a roadway, ie. as an ordinary electric car. The vehicle 1 has a triangular groove 6 with its point in an upwards direc¬ tion and widening downwards as shown in connection with figs. 1 and 2. When the vehicle 1 is not driving on its triangular rail, the mentioned triangular groove may be used for connecting the power unit 11. The power unit 11 is in a generally known manner mechanically connected under the vehicle 1, so that it will substantially fill the tri¬ angular groove 6 and such that the power unit is fixedly and immovably retained. The power unit 11 may have a front end 12 and a rear end 13 which designwise correspond to the

front end and rear end of the vehicle 1.

The cross-sectional profile of the power unit 11 is shown in fig. 5 and may comprise a unit built up by sheet walls 14 enclosing an elongate hollow space 15. The power unit 11 is preferably designed in such a manner that it substan¬ tially fills the triangular groove in the vehicle 1 so that maximum increase of the range of the vehicle is achieved and has externally not shown electrical terminals or the like for electrical connection with the vehicle 1, prefer¬ ably connection with the existing sliding contacts adapted for drawing current from the driving rail.

In an embodiment of the invention, which is schematically shown in fig. 4, the hollow space 15 of the power unit 11 holds a fuel tank 16 for motor fuel, for example gasoline or Diesel oil, for a combustion engine 17 powering a gener¬ ator 18 for generating electric current. The combustion en¬ gine 17 is preferably optimised in relation to efficiency and pollution, for example by being controlled for driving at a constant, optimum number of revolutions. If the cur¬ rent from the generator 15 is conducted in parallel over the battery of the vehicle, the generator will only have to supply the average consumption, which means that the engine and the generator may be less powerful than required for supplying the maximum consumption since current peaks etc. are supplied by the battery.

Even if fig. 4 shows the currently preferable embodiment of the invention because it may provide a relatively substan¬ tial increase in the range of the vehicle outside the rail, it is obvious to a person skilled in the art that the power unit may be designed in many other ways. The power unit may in a simple embodiment merely be an additional battery, but may in a more complicated embodiment by a hydrogen engine powered by a hydrogen store which has for example been fil-

led up by applying non-polluting energy such as wind en¬ ergy, wave energy, solar energy etc.

The energy store in the power unit according to the inven- tion may also be based on the application of fuel cells or similar technology so that it is possible to provide electricity without using a combustion engine.

It is obvious to a person skilled in the art that the power unit according to the invention may be built up by any type of energy store as long as the energy in the store can be converted into electric energy for the vehicle.