VEHICLE

TECHNICAL FIELD

The invention relates to a method for supplying fuel to a vehicle by filling fuel into a vehicle fuel tank wherein the fuel tank comprises a tank opening for filling fuel into the fuel tank. The invention also relates to a system for performing the method, a control unit for operating the system and a vehicle comprising the system.

BACKGROUND OF THE INVENTION It is generally known in the art that a free volume has to be left above the fuel level for having enough space for thermal expansion of the fuel. Due to construction requirement the free volume cannot be below a certain size. Particularly for large fuel tank volumes of several hundreds litres like in trucks increasing the intake capacity of a fuel tank results in an increase of cruising range and a reduced time consumption for refuelling the vehicle.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method for increasing the amount of fuel which can be filled into the fuel tank.

Another object is to provide a system for performing the method and a control unit for operating the system. Yet another object is to provide a vehicle with an improved fuel filling capacity.

The objects are achieved by the features of the independent claims. The other claims and the description disclose advantageous embodiments of the invention. A method is proposed for supplying fuel to a vehicle by filling fuel into a vehicle fuel tank, the fuel tank comprising a tank opening for filling fuel into the fuel tank, wherein in a fuelling mode a position of the fuel tank opening is adapted to increase an intake capacity of the tank by moving the tank opening from a first position over ground level to a second position over ground level.

The tank opening is normally arranged at an upper part of the fuel tank. This usually results in a dead volume above the maximum fuel level which cannot be filled with fuel and which is much larger than required for thermal expansion of the fuel in the tank. By moving the tank opening from a first position over ground level to a second position over ground level which allows for increasing the intact capacity of the fuel tank it is possible to make use of available space of the dead volume of the fuel tank, but leaving enough space for thermal expansion of the fuel. For instance, only 2-3% of the fuel tank volume is needed for thermal expansion. Moving the tank opening can be done by tilting the fuel tank with respect to a horizontal position for a normal driving operational mode. Expediently, the fuel tank is tilted about an axis which intersects the tank opening in the tank casing. The second position of the opening can be adjusted depending on the position of the vehicle, i.e. whether the vehicle is standing on even ground or on a declining or an ascending slope or is tilted sideward.

After fuelling including filling some of the otherwise free space above the "normal" maximum fuel level it is possible to go back to normal position for the driving operational mode. This can be done automatically.

According to an advantageous embodiment, an inclination of the fuel tank may be adjusted in a way that the tank opening is moved into an uppermost area of the fuel tank compared to ground level. On even ground without a slope, more free space is available the higher the tank opening can be moved above ground level. The inclination can be altered in a longitudinal direction of the vehicle, a

transversal direction of the vehicle or in both directions.

According to an advantageous embodiment, the vehicle may be tilted to increase the intake capacity of the fuel tank. Alternatively or additionally the fuel tank itself may be tilted to increase the intake capacity of the fuel tank. Tilting the vehicle and/or the fuel tank can be done by various means.

According to an advantageous embodiment, a vehicle suspension system may be used to adapt the position of the tank opening from the first position over ground level to the second position over ground level. Expediently, by inflating or deflating air bellows of the air suspension the inclination of the vehicle frame to which the fuel tank is mounted can be easily altered. Additionally or alternatively, one or more tires of the vehicle may be deflated and/or inflated to move the tank opening from the first position over ground level to the second position over ground level. A central deflation and inflation system for the wheels of the vehicle can be used for this purpose. In a further option the actual inclination of the vehicle may be determined and evaluated whether an adjustment of the position of the tank opening over ground level is necessary or not. In case the vehicle is standing on a slope already in an appropriate position for using the dead volume in the fuel tank for storing fuel, the position of the vehicle can be properly recognized. Otherwise, it can be

determined in which direction the tank opening has to be moved and/or which inclination of the fuel tank has to be employed.

Yet in a further advantageous embodiment the position of the tank opening over ground level may be adapted before fuelling, as soon as a filling operation or an intention to perform a filling operation is recognized and/or during filling. This can be done completely automatically or can be initiated manually by the driver, which is very time economic. Time can be saved during the tank stop as the tank opening can be brought to the desired position without delay. According to another aspect of the invention, a system is proposed for performing the above described method, the system comprising at least one sensor unit for determining an inclination of the fuel tank and/or of the fuel surface in the fuel tank and/or a position of a tank opening for receiving fuel relative to a ground level. By moving the tank opening from a first position over ground level to a second position over ground level - for instance to a higher position over ground level than the first position -, it is possible to make use of available space of the dead volume of the fuel tank, but leaving enough space for thermal expansion.

Favourably, when the shape of the fuel tank, the position in the vehicle and the position of the tank opening is known, it can be deduced how much fuel can be added above the normal maximum fuel level with the tank opening in its normal position. It is even possible to adjust the tilting operation to an actually available volume in the fuel tank. If the tank has a complex shape, the inclination of the fuel tank can be changed during the filling operation to make use of all available space. Advantageously, even this filling method allows to build fuel tanks with complex shapes so that the fuel tank can be constructed in a space economic way using available construction space in the vehicle.

Another favourable embodiment may provide an indicator unit for indicating when an at least local optimum of the position tank opening above the ground level in relation to the fuel surface in the fuel tank is reached. The term "local optimum" means that an optimum position above ground of the tank opening can be dependent on actual fuel level in the fuel tank and/or the shape of the fuel tank.

Yet another expedient embodiment may comprise a control unit for automatically adjusting the position of the tank opening above ground level in relation of an available intake capacity of the fuel tank. This can be done either when it is recognized that the fuel tank should be filled and also during filling operation.

Yet another expedient embodiment may have at least one sensor for detection of a fuel filling operation and/or an intention of a fuel filling operation, particularly by detecting at least one of

- approaching a fuel filling station with a fuel level in the fuel tank at or below a predetermined level; - a speed of increasing a fuel level at or above a predetermined speed limit of increasing the fuel level;

- an increase of a fuel level for at least a predetermined time;

- removing a cap from a filling tank opening of the fuel tank;

- moving into and/or attaching a fuel nozzle to the tank opening

- fuel flow into the fuel tank.

It is of advantage that the system can recognize when it should perform the method. For instance, when deflating or inflating of wheels is used to change the position of the tank opening over ground level, the action can be initiated early so that a time economic tank stop is possible. Deflating or inflating the wheels may take some minutes. Furthermore, the position of the tank opening can be readjusted to its normal position for the driving operational mode before the vehicle leaves the fuel station or after the vehicle has left the fuel station.

According to another aspect of the invention, a control unit for operating the described system is proposed, wherein the control unit is connected to a wheel suspension system of a vehicle for automatically adjusting a position of a tank opening relative to a ground level in relation to a fuel surface in the fuel tank.

This is a convenient way of temporarily changing the position of the fuel tank opening above ground level by inclination of the fuel tank and/or the vehicle.

Advantageously, the control unit may be connected to a vehicle inflation system for inflating and/or deflating tires of the vehicle. Air can be easily supplied in a truck.

Additionally or alternatively, the control unit may be connected to a suspension system for deflating and/or inflating air bellows of the suspension system may comprise a control unit connected to the vehicle inflation system. Air can be easily supplied in a truck.

According to another aspect of the invention a vehicle is proposed comprising the above described system and additionally the above-described control unit. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention together with the above-mentioned and other objects and advantages may best be understood from the following detailed description of the embodiment(s), but not restricted to the embodiments, wherein is shown

schematically:

Fig. 1a, 1b an example embodiment of a vehicle comprising a fuel tank in even position (Fig. 1a) and in inclined position along a longitudinal axis (Fig. 1 b) for increasing the intake capacity of the tank according to the invention by deflating or inflating tires of the vehicle; Fig. 2 an example embodiment of a vehicle, comprising a fuel tank at each side of a vehicle frame;

Fig. 3a, 3b an example embodiment of a tank and the position of the tank

opening in an even position (Fig. 3a) and the position of the fuel tank and tank opening with the fuel tank in an inclined position (Fig. 3b), inclined transverse to a longitudinal vehicle axis by inflating and/or deflating air bellows supporting a frame of the vehicle;

Fig. 4a, 4b a tank according to Fig. 3a, 3b in an inclined position employing air bellows of a suspension system (Fig. 4a) and employing a system for inflating and deflating tires (Fig. 4b).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In the drawings, equal or similar elements are referred to by equal reference numerals. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. Moreover, the drawings are intended to depict only typical embodiments of the invention and therefore should not be considered as limiting the scope of the invention.

Figures 1a and 1 b show an example embodiment of a commercial vehicle 10 such as a truck in an even position (Fig. 1a) and in an inclined position along a longitudinal vehicle axis (Fig. 1 b). The vehicle 10 comprises a fuel tank 20 mounted to a frame 12 of the vehicle 10. The fuel tank 20 has an tank opening 50 for filling fuel into the fuel tank 20. The tank opening 50 is conveniently provided at an upper part 22 of the tank casing 30. In its normal position 80, the tank opening 50 in the fuel tank 50 has a defined height H80 above a ground level GL. Due to the required buffer volume for thermal expansion of fuel in the fuel tank 20, there is a dead volume V60 above the maximum fuel level 60 in the fuel tank 20. The dead volume V60 is larger than the required buffer volume. For increasing the intake capacity of the fuel tank 20 when fuel is filled into the fuel tank 20, the vehicle 10 can be tilted, for instance by deflating or inflating tires 14a, 16a, 18a of the vehicle 10. By tilting the vehicle 10 in an adequate way, the inclination of the fuel tank 20 is changed, so that the tank opening 50 moves to a position 90 at a height L90 above ground level GL which is higher than the former position 80, Due to the larger height H90 of the tank opening 50 more fuel can be filled in and the maximum fuel level 60 in the fuel tank 20 increases and the dead volume V60 decreases. As fuel tanks 20 of trucks have an intake capacity of several hundreds of litres up to more than 1000 litres an increase of the fuel amount in the fuel tank 20 already by a few percent can increase the driving range and reduce the number of tank stops. When the fuelling operation is terminated, the vehicle 10 can be brought back in its normal position.

On the other hand, when the vehicle 10 is standing on a slope where the fuel tank 20 is already inclined appropriately (i.e. increasing the intake capacity of the fuel tank 20), it is not necessary to tilt the vehicle 10. If the vehicle 10 is standing on a slope where the fuel tank 20 is inclined inappropriately (i.e. reducing the intake capacity of the fuel tank 20), the vehicle 10 can be tilted to increase the fuel intake capacity of the fuel tank 20. A control system 00 (shown only in a simplified way) can determine if the vehicle 10 is standing on a slope or on even ground and/or is tilted sideward and can determine an actual position 80 as well as a desired position 90 of the tank opening 50 of the fuel tank 20. The position of the tank opening 50 relative to the ground level GL can be adjusted by the control system 100 as soon as a filling operation or an intention to perform a filling operation is recognised and/or during filling. Favourably, a sensor 140 is provided which can detect the inclination of the vehicle 10. For instance, sensor readings of one or more sensors already provided in the vehicle 10 for other support functions can be included in the control.

The control system 100 may include a control unit 144 for automatically adjusting the position of the tank opening 50 over ground level GL in relation of an available intake capacity of the tank 20. Of course, the control unit 144 may be a unit separate from control unit 100.

The control unit 144 is responsive to an indicator unit 142 indicating when an at least local optimum of the tank opening 50 over ground level GL in relation to the fuel surface 60 in the tank 20 is reached. The indicator unit 142, for instance a height sensor and/or an inclination sensor, may be arranged in vicinity of the tank opening 50 or at another appropriate location of the vehicle 10.

The control system 100 can be a separate control system or integrated in an already existing control system for an air suspension which for this purpose can have an additional functionality.

Advantageously, at least one sensor 150 can be provided for detection of a fuel filling operation and/or an intention of a fuel filling operation, particularly by detecting at least one of approaching a fuel filling station with a fuel level in the fuel tank 20 at or below a predetermined level; a speed of increasing a fuel level 60 in the fuel tank 20 at or above a predetermined speed limit of increasing the fuel level 60; an increase of the fuel level 60 for at least a predetermined time; removing a cap from the tank opening 50 of the fuel tank 20; moving into and/or attaching a fuel nozzle to the tank opening 50 and/or recognizing fuel flow into the fuel tank 20.

Particularly, the control system 100 can prepare or initiate a proper positioning of the tank opening 50 of the fuel tank 20 when a fuel filling station is approached with a fuel level 60 in the fuel tank 20 at or below a predetermined level, and/or when a speed of increasing a fuel level at or above a predetermined speed limit of increasing the fuel level is detected, and/or when an increase a fuel level for at least a predetermined time is observed, and/or when a filler cap is removed from the tank opening of the fuel tank 20, and/or when a fuel nozzle is moved into and/or attached to the tank opening 50, and/or when a fuel flow into the tank 20 is adapted. Of course, the positioning change of the tank opening 50 above ground level GL can be done manually by the driver, for example.

Fig. 2 depicts an example embodiment of an arrangement of fuel tanks 20 attached to beams 12a, 12b of a frame 12 of a vehicle. The fuel tanks 20 have a casing 30 with a rectangular cross section. However, the cross section can have any desired shape, for instance circular, oval, D-shaped or the like. The frame 12 is supported on air bellows 120a, 120b of an air suspension system 120. Tires 16a, 16b are connected to a central vehicle inflation system which can deflate or inflate tires of the vehicle wheels. The vehicle can be tilted along a longitudinal direction by inflating or deflating air bellows 120a, 120b or tires 16a, 16b on the same axle and/or along a transverse direction by inflating or deflating air bellows 120a or 120b or tires 16a or 16b on the same side of the vehicle.

A fuel level 60 is established in the inside 40 of the fuel tank 20 with the opening 50 in the fuel tank 20 at a height H80 above ground level GL.

Figures 3a and 3b depict an example embodiment of a fuel tank 20 as shown in Fig. 2 in a first position 80 of a tank opening 50 in an even position of the vehicle (Fig. 3a) and the position of the fuel tank 20 and the position 90 of the tank opening 50 with the fuel tank 20 in an inclined position (Fig. 3b). The fuel tank 20 in Fig. 3b is inclined transversely to the longitudinal vehicle axis by inflating and/or deflating air bellows 120a, 120b supporting longitudinal beams 12a, 12b of a frame 12 of the vehicle 10 (see Fig. 2). The fuel tank 20 in the even position in Fig. 3a indicating a fuel nozzle 160 filling fuel into an opening 50 in the tank casing 30 has a maximum fuel level 60 which cannot be exceeded in this position and a dead volume V60 above the maximum fuel level 60. As can be seen when tilting the fuel tank 20 so that the opening 50 is moved from a first position 80 to a second position 90 above ground level (Fig. 3b), a dead volume V60 above a new maximum fuel level 60 inside the fuel tank 20 decreases as the intake capacity of the fuel tank 20 has increased. The maximum fuel level shown in Fig. 3a is indicated by a broken line in Fig. 3b for comparison reasons.

Fig. 4a, 4b show a fuel tank 20 according to Fig. 3a, 3b in an inclined position employing air bellows 120a, 120b of a suspension system 120 (Fig. 4a) and employing a system for inflating and deflating tires 16a, 16b (Fig. 4b). The fuel tank 20 is shown only at one side of the vehicle but there can be one at each side of the vehicle.

When air bellows 120a, 120b are employed (Fig. 4a), the frame 12 is tilted while the axles remain equidistant to the ground level GL, while when the tires 16a, 16b are employed (Fig. 4b), the vehicle axles are tilted compared to ground level GL so that the framel 2 remains equidistant to the vehicle axles.

In the example embodiments of Fig. 4a, 4b, the vehicle 10 can be tilted sideways when the air bellows 120a or 120b and/or the tires 16a or 16b at one side of the frame 12 are deflated or inflated, thus moving the tank opening 50 of the fuel tank 20 from a first position e.g. for normal driving to a second position 90 for filling fuel into the fuel tank 20.

The invention is preferable suitable for trucks, especially for driving long distances and in environments with few cost effective petrol stations. The invention can also provide an improved handling comfort for the driver of the truck in that the need of replenishing fuel make demands on less time.

Advantageously, the invention allows to use a smaller fuel tank for the same driving range or to provide a larger driving range with the same fuel tank size. A smaller fuel tank 20 allows for installing additional components to the vehicle frame. A higher intake capacity of the fuel tank 20 means a probably shorter vehicle or more space for cargo. The length of the fuel nozzle is large enough so that the fuel tank cannot be overfilled and enough dead volume, e.g. 3%, is still available for the required buffer space for thermal expansion of the fuel. When there are two or more fuel tanks available on the vehicle which are connected with a fuel pipe, it is possible to fill all fuel tanks through one single tank opening 50.