FIELD OF THE INVENTION AND PRIOR ART

5 The present invention relates to a tractor vehicle with, on at least one side of it, a side skirt which extends rearwards in the vehicle's longitudinal direction from the region behind the front wheels and is so configured that in a working state of the vehicle it at least partly delineates laterally a space situated under a 10 semitrailer attached to the vehicle, and to a method according to the preamble of the attached independent method claim.

Tractor vehicle means here a vehicle of the type which in everyday parlance is called a long-distance truck and is intended 15 to have in a working state a semitrailer typically attached to it via a so-called fifth wheel coupling.

The tractor vehicle is provided with a said side skirt in order to reduce the vehicle's air resistance when in motion and thereby 20 reduce its fuel consumption. Accordingly, each side of the vehicle is usually provided with such a side skirt, although the respective side skirts may possibly be configured differently, e.g. to cater for the vehicle's refuelling.

25 The smaller the gap, i.e. the distance between the upper edge of the side skirt and the lower edge of the semitrailer, the smaller will be the air resistance and hence the fuel consumption when the vehicle is in motion. There are however a number of factors which limit the possibility of bridging said gap.

30 The gap needs to be large enough for there to be no risk that the upper edge of the side skirt might foul the lower edge of the semitrailer du ring marshalling and when negotiati ng ferry ramps or the like or in cases where the semitrailer's forward portion for some other reason comes close to the side skirt.

Nor may the side skirt protrude so far upwards at the point for climbing onto the boarding step behi nd the tractor vehicle's driving cab that there is risk that a person thus climbing up or down relative to the boarding step mig ht trip on the side skirt.

The side skirt also needs to be so configured as to facilitate access to a refuelli ng orifice . S U MMARY OF TH E I NVENTION

The object of the present invention is to propose a tractor vehicle of the kind defined in the introduction which solves the above problem in a way which in at least one respect is better than previous known tractor vehicles .

Th is object is ach ieved according to the invention by a tractor vehicle being provided with the featu res ind icated in the attached claim 1 .

The provision of an elongate element wh ich can be caused to move between an active position in wh ich it extends the side skirt upwards and thereby reduces said gap , and an inactive lower position , makes it possible for the gap to be reduced in situations which so allow, wh ile at the same time the gap can be kept large enough in situations which require a larger gap. This means that in normal running of the tractor vehicle in a working state, i.e. towing a semitrailer, the elongate element can be in the active position and thereby reduce the air resistance of the vehicle combination and hence the fuel consumption of the tractor vehicle, but be in the inactive position, e.g. during marshalling and when negotiating ferry ramps, without risk of the semitrailer's lower edge fouling the element. In addition, the element is with advantage moved to the inactive position to allow access for refuelling and for climbing up and down the tractor vehicle's boarding step.

Side skirts suspended from trailers which can be regulated to hang down different distances from a trailer are previously known, inter alia from US 4611 847 and US 7950721 B1.

In one embodiment of the invention the tractor vehicle has means for detecting and sending information about its speed to the unit, and the unit is adapted to causing said movement means to move said element to the active position when the vehicle is above a predetermined threshold speed, and to move the element from the active position towards the inactive position when the vehicle is below this threshold speed. Assurance is thus afforded that the element will only be in its active position when it has a real effect upon the tractor vehicle's air resistance and hence fuel consumption, and be in the inactive position when the vehicle is stationary or moving slowly, as during marshalling and when negotiating ferry ramps. To this end, in one embodiment of the invention the unit is adapted to having a speed within the range 20-50 km/h, 20-40 km/h, 25-35 km/h or 30 km/h as said threshold speed . A threshold speed at th is level affords assurance of the intended operation of said element.

In another embod iment of the invention the tractor vehicle has facilities for gathering, or being provided with, i nformation about the state of roads , e.g . the frequency and size of u nevennesses in carriageways, and for sending information about same to said u nit, and the latter is adapted to using said information as a basis for causing said movement means to move said element relative to the side skirt. This means that when the vehicle is travelli ng on an u nusually uneven carriageway the unit can cause the element to be in a position in which its upper edge is at a lower level than in said active position , in order to avoid any risk that the element might fou l the semitrailer's lower edge and thereby suffer damage.

In another embod iment of the invention the tractor vehicle has facilities adapted to detecting the distance between the upper edge of the side skirt and the lower edge of a semitrailer attached to the tractor veh icle, and to send ing information about this to the unit, which is adapted to using the distance thus detected as a basis for causing said movement means to move the element. Th is makes it possible, when the vehicle is in motion , for the element to be in the active position irrespective of the ru n ning conditions and , if for any reason , e .g . when passing over some u neven ness, the semitrailer's lower edge comes close to the side skirt's u pper edge , for the element to be moved downwards from the active position . I n a further development of this embod iment of the invention the u nit is adapted to moving the element towards the inactive position when said d istance is less than a predetermined value and the element is in an active position .

In another embodiment of the invention the tractor veh icle also has operating means usable by a driver of the veh icle to send orders to said unit to cause said movement means to move the element relative to the side skirt in accordance with orders thus given . Th is makes it possible for the driver to determine the position of said element manually if so desired .

In another embodiment of the invention the elongate element is a substantially platelike element with a height intended , in the element's active position , to extend upwards beyond the side skirt towards a said semitrailer by 30-300 mm , 50-250 mm or 1 00-200 mm .

In another embodiment of the invention said movement means is adapted to movi ng the element by shifting it vertically or substantially vertically relative to the side skirt on a tractor vehicle stand ing on a horizontal ru nning surface . I n th is case the element is with advantage put into the inactive position in order to be at least partly concealed behind , and thereby be protected by, the side skirt. In another embodiment of the invention said movement means is adapted to moving the element relative to the side skirt by lowering it from said active position about a spind le which is parallel or substantially parallel with said longitudinal direction , with its u pper bou ndary directed inwards towards the i nterior of said space . The risk of damage to the element in the inactive position thus becomes slight.

In another embodiment of the invention the element is configured to be movable, against the action of said movement means, to an inactive position in wh ich its upper edge is at the same height as or lower than that of the side skirt. Th is makes it possible for the element to be concealed beh ind the side skirt and be protected from damage in the inactive position in which it performs no fu nction .

In another embodiment of the invention the tractor vehicle has a said side skirt with a said elongate element on each of its long sides. This makes it possible for the elongate elements on the two long sides to d iffer in d imensions or shape if so desired .

The invention proposes also a method for altering the air resistance coefficient of a tractor veh icle in a working state with a semitrailer attached to it and with , on at least one side of it, a side skirt which extends rearwards in the tractor vehicle's longitudinal d irection from the region behind its wheels and is configu red to partly delineate laterally a space situated u nder the semitrailer, wh ich space is provided with features as i n the characterising part of the attached independent method claim. The advantages of such a method and of the embodiments of the invention which are covered by the dependent method claims are ind icated with all desirable clarity by the above d iscussion of the tractor vehicle according to the invention. The invention relates also to a computer programme which presents the features set out in claim 16, a computer programme product which presents the features set out in claim 17, and an electronic control unit which presents the features set out in claim 18.

Other advantageous features and advantages of the invention are indicated by the description set out below.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention cited by way of examples are described below with reference to the attached drawings, in which

Fig. 1 is a side view illustrating a tractor vehicle according to the present invention in a working state, i.e. with a semitrailer coupled to it, when moving forwards, Fig.2 is a schematic view illustrating how said element of a tractor vehicle according to the invention may be caused to move according to various embodiments of the invention, Fig.3 is a perspective view of part of a tractor vehicle according to the invention with said element in an active position, Fig.4 is a prespective view of the lower portion of the tractor vehicle depicted in Fig. 3, with the element in an inactive position, Fig.5 is a view corresponding Fig. 4 illustrating another embodiment of the invention, with the element in an inactive position,

Fig.6 is a flowchart illustrating a method according to an embodiment of the invention, and

Fig.7 is a schematic diagram of an electronic control unit for implementing a method according to the invention. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Fig. 1 illustrates schematically a tractor vehicle 1 according to an embodiment of the invention in a working state, i.e. a state in which it performs its function of towing a semitrailer 2 which in a conventional way is attached to the tractor vehicle via a schematically depicted so-called fifth-wheel coupling 3. A space 4 situated under what in the running direction is the forward portion of the semitrailer is partly occupied by part of the tractor vehicle, and when the vehicle is moving forwards at its normal cruising speed, e.g. 60-90 km/h, the presence of this space will have a perceptible effect upon the air resistance to which the tractor vehicle/semitrailer combination is subject if this space is not protected laterally. Accordingly the tractor vehicle is conventionally provided on each side with a side skirt 6 which extends in the vehicle's long itud inal d irection rearwards from the region beh ind the front wheels 5 and is configured to partly del ineate the space 4 laterally when the veh icle is in said working state.

Such a side skirt thus normally extends downwards as far as is possible without causi ng a risk that it might in some situations come into contact with the ru nni ng su rface on wh ich the tractor vehicle may be expected to travel . For the sake of safety the lowest portion of the side skirt may take the form of a rubber strip 7, wh ile the rest of it wi ll be rigid and strong enough to be provided with a foothold 8 to be used by a driver of the vehicle wish ing to make his/her way up onto the board ing step 9 situated beh ind the vehicle's driving cab 1 0. The side skirt does however normally extend upwards no further than the surface of the board ing step , to avoid any risk of tripping on it.

Even if this problem was disregarded in favour of trying to extend the side skirt further upwards, it wou ld be necessary to ensure that during any kind of vehicle movement, e .g . travel ling up a ferry ramp, the semitrailer's lower edge cou ld not fou l and damage the side skirt, nor block access to the refuelling orifice.

To reduce the air resistance coefficient of the tractor vehicle/semitrailer combination wh ile nevertheless avoidi ng the potential problems arising from a heightened side skirt, the tractor vehicle according to the invention has an elongate platelike element 1 1 adapted to extending in the tractor vehicle's longitudinal d irection along at least one, although preferably along each , side skirt and arranged to be movable relative to the side skirt. Here we refer also to Figs.3 and 4. More specifically, the platelike element is so arranged as to be, when seen from the side, partly behind the side skirt and be movable in vertical directions relative to the side skirt, assuming that the tractor vehicle is on a horizontal running surface.

How the element 11 according to the invention may be operated is illustrated in Fig. 2. Means 12, e.g. an electric motor, are provided to move the element between at least one active position (as in Fig. 1 and Fig.3) in which in the tractor vehicle's working state it at least partly bridges the distance between an upper edge 13 of the side skirt and a lower edge 14 of said semitrailer and thereby serves as an upward continuation of the side skirt, and an at least partly inactive position (as in Fig.4) in which its upper boundary 15 is at a greater distance from said lower edge of the semitrailer than in the active position. Accordingly, the element may typically, in its active position, extend upwards beyond the side skirt by about 200 mm, while a side skirt typically has a height in a similar direction of 500-800 mm.

The tractor vehicle is provided with a unit 16, e.g. an electronic control unit, adapted to controlling the movement means 12. The unit 16 receives information from various components of the tractor vehicle to serve as a basis for controlling the movement means 12. Means 17 detect and send information about the tractor vehicle's speed to the unit 16, which is adapted to causing the movement means 12 to move the element 11 towards the active position when the tractor vehicle is above a predetermined threshold speed, e.g. 30 km/h, and to move the element from the active position towards the inactive position when the tractor vehicle is below this threshold speed. Assurance is thus afforded that the element will not be in the active position when the tractor vehicle is stationary or moving so slowly that this position will have no appreciable effect upon the air resistance of the vehicle combination.

Facilities 18 are provided for gathering, e.g. via the internet, or being provided with, information about the state of roads, e.g. the frequency and size of unevennesses in carriageways, and for sending this information to the unit 16, which is adapted to taking this information into account when operating the movement means 12. Should part of a road for any reason be so uneven that when the vehicle combination is in motion substantial relative movements between the semitrailer and the tractor vehicle may occur, the unit 16 will thus be able to cause the movement means to move the element 11 towards the inactive position, in order either to reach that position or, where applicable, to be between the active and inactive positions.

The tractor vehicle might also have facilities 19 for detecting the distance between the upper edge 13 of the side skirt and the lower edge 14 of a semitrailer attached to the tractor vehicle, and for sending information about this distance to the unit, which is then adapted to causing the movement means 12 to move the element in such a way in response to the distance thus detected that when the vehicle combination suddenly runs over an unevenness, causing movement of the semitrailer's lower edge 14 towards the side skirt, the element would be moved towards the inactive position, thereby preventing contact between the semitrailer and the side skirt's upper boundary 15. The presence of such a facility 19 would make it possible for the upper boundary 15 of the element 11 in the active position to be much nearer to a lower edge of a semitrailer, with consequently optimised effects upon the air resistance coefficient and hence upon the tractor vehicle's fuel consumption.

Also illustrated is the provision of operating means 20 which may be used by a driver of the tractor vehicle to send orders to the unit 16 to cause the movement means 12 to move the element 11 relative to the side skirt in accordance with orders thus given. This enables the driver to ensure manually that the element is put into the state desired by him/her, and such manual control may for example be superordinate to the control which is based upon the information from the means 17 and the facilities 18, 19 as regards movement towards the inactive position, but not towards the active position.

Fig. 5 illustrates a possible alternative to what is depicted in Figs. 3 and 4 with regard to the movability of the element 11 relative to the side skirt 6. Here the element is instead movable relative to the side skirt by being lowered from the active position about a spindle which is parallel or substantially parallel with the tractor vehicle's longitudinal direction, with its upper boundary 15 directed inwards towards the interior of the space 4. In the state depicted in Fig. 5 the element is consequently in an inactive lowered position and can be pivoted about said spindle to an active position substantially corresponding to that depicted in Fig.3. Fig . 6 is a flowchart il lustrating a method accordi ng to an embod iment of the invention for altering the air resistance coefficient of a tractor vehicle in a working state with a semitrailer attached to it of the type illustrated in Figs . 1 and 3-5. As a first step S ₁ the speed of the tractor vehicle is measured, and as a second step S ₂ the speed thus measu red is compared with a threshold speed . Step S ₃ asks whether the measured speed is greater than the threshold speed, and if the answer is affirmative the method moves on to step S ₄ , in wh ich the element is moved to or kept in the active position . If on the contrary the answer to the question is negative , the method moves on to step S ₅ , in wh ich the element is caused to move to or remain in the inactive position. This procedure is repeated continuously or at su itable intervals of time. I n parallel therewith, at a step S ₆ the gap G is measu red as the distance between the lower edge 1 4 of the semitrailer and the u pper edge 1 3 of the side skirt, and at step S ₇ th is gap is compared with a threshold gap, and step S ₈ asks whether the measu red gap is greater than the threshold gap and , if the answer is affirmative the method goes to step S ₄ and if it is negative the method goes to step S ₅ . This part of the method is likewise repeated continuously or intermittently.

Computer program me code for implementing a method accord ing to the i nvention is with advantage included in a computer programme which can be read into the internal memory of a computer, e.g . the internal memory of an electronic control u nit of a tractor vehicle. Such a computer programme is with advantage provided via a computer programme product comprising a data storage medium which can be read by an electronic control u nit and which has the computer program me stored on it. Said data storage medium is for example an optical data storage medium in the form of a CD ROM disc, a DVD disc etc., a magnetic data storage medium in the form of a hard disc, a diskette, a cassette tape etc., or a flash memory or a memory of the ROM, PROM, EPROM or EEPROM type.

Fig. 7 illustrates very schematically an electronic control unit 16 comprising an execution facility 21, e.g. a central processor unit (CPU), for execution of computer software. The execution facility 21 communicates with a memory 22, e.g. of the RAM type, via a data bus 23. The control unit 16 comprises also a data storage medium 24, e.g. in the form of a flash memory or a memory of the ROM, PROM, EPROM or EEPROM type. The execution facility 21 communicates with the data storage medium 24 via the data bus 23. A computer programme comprising computer programme code for implementing a method according to the invention, e.g. in accordance with the embodiment illustrated in Fig.6, is stored on the data storage medium 24. The invention is of course in no way restricted to the embodiments described above, as numerous possibilities for modifications thereof are likely to be obvious to one skilled in the art without thereby deviating from the scope of the invention such as is defined in the attached claims.

It would for example be possible for the element to be movable to two or more fixed active positions or be settable steplessly to different positions relative to the respective side skirt.