The invention relates to a method and. a control unit in a vehicle. It refers moITΘ Sp8Cifically to a method for operating an automatic gearbox in a vehicle whereby a gear is prioritised by the driver.

BACKGROUND

In. changing gear in a vehicle arranged, for automatic gear changing, perhaps particularly in slightly more difficult situations such as carrying heavy loads uphill in/from a mine, it may be difficult for an automatically operated gearbox to achieve desirable running behaviour.

Such automatic gear changing in heavy vehicles often takes the form of control system, operation of "manual" gearboxes, also called AMT (automated manual transmission), e.g. because they are substantially less expensive to manufacture, but also because of their greater efficiency compared with traditional automatic gearboxes . They are also less heavy. Automatically operated AMT gearboxes are therefore commonly used in heavy vehicles which are largely used in agriculture and/or on motorways.

Vehicle in this context means for example truck, long-haul carrier, platform vehicle, transporter, wheeled loader, bus, off-road vehicle, tracked vehicle, military vehicle, four- wheeler, car or other similar powered means of transport, whether manned or unmanned, suited to travelling on land.

Road gradient conditions in a mine are often quite particular. Long steep climbs may turn through almost entirely level 90 degree bends . Vehicles making their way up out of a mine are often heavily laden with ore. One problem is that during the gearchange process the engine imparts no tractive force in the vehicle's direction of movement, so the vehicle loses a great deal of speed through the combination of heavy load and travelling uphill.

A further problem in automatic gearchanging is that, a level bend reached after a climb may seem a suitable situation for an upshift in cases where there is no awareness that a further climb is immediately imminent. A higher gear thus adopted ma therefore result in the engine speed being too low after the gear change and in the engine consequently generating so little torque that the vehicle cannot keep moving and the engine therefore stalls, or else the automatic gearbox shifts down and the vehicle accelerates again via too low a gear. It thus loses speed, leading to delay to movement up out of the mine. Being thus out of step with other vehicles may result in queuing which further lowers the speed of movement not only for the respective vehicle but also for others behind. Too low a gear also leads to higher fuel consumption and greater environmental load due to increased emissions of exhaust gases .

If the automatic gearchange process results in the engine stalling on the vehicle' s way up out of the mine, the road may be completely blocked. As well as reducing the productivity of the mine, such a blockage may also present a safety risk if for example the mine has to be quickly evacuated or an emergency vehicle needs immediate access to the mine.

Another possible problem is where a vehicle, e.g. a timber carrier, reaches a section of bad road surface, e.g. on a poorly maintained gravel road with mud and potholes . The driver will usually try to avoid unnecessary gear changes in order not to lose speed and come to a halt, while at the same trying for the same reason to prevent the engine stalling. From the control system's perspective, this situation is rather like the mine example described above, but as well as reverse gradient change there will also be continual changes in both rolling resistance and wheel friction, leading to alternately sliding in mud and. becoming stuck . A known solution to the problem scenarios described above is to employ a gearchange sequence which an (experienced) driver conducts along a given stretch of road. This does however involve various problems, inter alia being expensive and complicated to implement . It also entails the obvious disadvantage of having to travel the stretch of road and employ the gearchange sequence before being able to use the automatic gearchange .

Where possible, the driver will often choose manual position for the gearbox in such driving environments as those described above . This applies where the automatic system sometimes misinterprets extreme situations and changes gear. For example, a stretch of road may be in good condition for tens of metres, so the automatic gearbox shifts up, but if the road immediately thereafter changes to a mud surface and/or a climb, the engine will not be able to propel the vehicle in the higher gear, resulting in the vehicle becoming stuck. In the case of manual gearchange the driver will therefore prefer to stay in the same gear until the road becomes sufficiently good or predictable for the automatic gearbox to cope with the situation. Problems do however occur where for example the vehicle can for any reason not continue in a gear chosen manually. This situation might be solved by a quick downshift to a. lower gear, but manual gear changing is significantly slower than automatic. Disengaging the automatic system and changing gear manually is therefore not a desirable solution.

It may be noted that much has still to be done to improve the gear changing of a vehicle with automatic gears, particularly on vehicles which operate in difficult and/or unpredictable running conditions.

SUMMARY

It is therefore an object of this invention to be able to solve at least some of the problems indicated above and improve the method for changing gear in a vehicle with automatic gearbox and thereby achieve an improvement of the vehicle .

A first aspect of the invention achieves this object by a method for operating an automatic gearbox in a vehicle. The method comprises priorit isat ion of a gear when an indication is detected that the respective gear is preferred by the vehicle's driver. The method further comprises enlarging a parameter range for a gearchange control parameter, which range is associated with the prioritised gear, by adjusting at least one shift, point which delineates the parameter range. The method further comprises parameter value determination for the gearchange control parameter . The method also comprises shifting to the prioritised gear when the parameter value determined is within the enlarged range and the prioritised gear is not engaged. A second aspect of the invention achieves the object by a control uni adapted to controlling- the operation of an automatic gearbox in a vehicle. The control unit comprises a circuit adapted to receiving an indication that a gear is preferred by the vehicle's driver. The same circuit is also adapted to receiving a parameter value for a gearchange control parameter. The control unit further comprises a processor circuit adapted to prioritising a gear when an indication is detected that the respective gear is preferred by the vehicle's driver. The processor circuit is also adapted to enlarging a parameter range for the gearchange control parameter, which range is associated with the prioritised gear, by adjusting at least one shift point which delineates the parameter range . The processor circuit is also adapted to determining- the parameter -value for the gearchange control parameter. The processor circuit is further adapted to initiating a shift to the prioritised gear when the parameter value determined is within the enlarged range and the prioritised gear is not engaged . The control unit also comprises a circuit adapted to sending a control signal to the automatic gearbox to shift to the prioritised gear.

By specifying a prioritised gear preferred by the driver/ vehicle owner and enlarging a parameter range for engaging the prioritised gear by adjusting at least one shift point for it, it is possible to avoid upshifts to a higher gear on a briefly level and/or easy section of a longer climb and/or difficult section of road. An unnecessary upshift quickly followed by a downshift may thus be eliminated, leading to faster movement along the respective stretch of road. A further advantage is that the risk of the engine stalling because of incorrect gear changes on a climb and/or a difficult section of road may be reduced or completely eliminated. The result is an improvement to a vehicle with au.tomatic gear changing .

Other advantages and further novel features are indicated by the detailed description of the invention set out below.

LIST OF DRAWINGS

The invention will now be described in more detail with reference to the attached drawings which illustrate embodiments of it: Figure 1A is an illustration of a vehicle according to an embodiment of the invention.

Figure IB is an illustration of a vehicle according to an embodiment of the invention.

Figure 2A is an illustration of engine speed and torque in a vehicle according to an embodiment of the invention .

Figure 2B is an illustration of engine speed and torque in a vehicle according to an embodiment of the i vention . Figure 2C is an illustration of engine speed and torque in a vehicle according to an embodiment of the i vention .

2D is an illustration of engine speed and torque in a vehicle according to an embodiment of the invention. 2E is an illustration of engine speed and torque in a vehicle according to an embodiment of the invention .

2F is an illustration of engine speed and torque in a vehicle according to an embodiment of the invention .

2G is an illustration of engine speed and torque in a vehicle according to an embodiment of the invention„ Figure 2H is an illustration of engine speed and torque in a vehicle according to an embodiment of the invention .

Figure 21 is an illustration of engine speed and torque in. a.

vehicle according to an embodiment of the invention.

Figure 2J is an illustration of engine speed and torque in a vehicle according to an embodiment of the invention .

Figure 3 is a combined flowchart and signalling diagram according to an embodiment of the invention .

4 is a flowchart illustrating an embodiment oi a method for changing gear in a vehicle. is an illustration of a control unit for changing gear in a vehicle according to an embodiment of the invention . DETAILED DESCRIPTION OF THE INVENTION

The invention is defined as a method and a control unit which may take the form of any of the embodiments described below. This invention may however be implemented in many different forms and is not to be regarded as limited by the embodiments herein described, which are intended instead to illustrated and clarify various aspects of the invention.

Further aspects and features of the invention may be indicated by the detailed description set out below when read in conjunction with the attached drawings. However, the drawings are only to be regarded as examples of ^' various embodiments of the invention and not. as limiting the invention, which is only defined by the attached claims. Moreover, the drawings are not necessarily drawn to scale and are intended, unless specifically indicated otherwise, to conceptually illustrate aspects of the invention.

Figure 1A depicts a vehicle 100 suited to changing gear and powered, to travel inter alia in a first direction of movement 105. The vehicle is on an uphill run A, B, C where a first climb A is followed by a level section of road B which is itself followed by a second climb C. The vehicle might for example be, but is not necessarily, a. freight, vehicle on its way up out of a mine. In other embodiments it might be on its way up a mountain via a serpentine road and might for example take the form of a bus carrying- tourists on icy alpine roads, to mention only one example, or it might be quite simply any vehicle in hilly country.

Figure IB depicts schematically a power train of the vehicle 100 according to an embodiment of the present invention. The power train comprises a combustion engine 110 which, via an output shaft from it, is connected, e.g. via a flywheel, to an input shaft 112 of a gearbox 113 via a clutch 114. A sensor 111 may be particularly adapted to reading the engine's speed on the output shaft. The gearbox 113 may be an automatic gearbox or an automated manual gearbox (AMI) in d1fferent emfoodiments .

The clutch 114 may for example take the form of an automatically operated clutch which may for example be of dry-disc type. The engagement of the friction element (the disc) with the engine' s output shaft may be controlled by means of a pressure plate which may be movable sideways, e.g. by a lever arm whose function may be controlled by a clutch actuator. The action of the clutch actuator on the lever arm will itself be controlled, by the vehicle's clutch cont ol system via a. cont ol unit. 115. The control u it 115 will also operate the gearbox 113.

The control algorithm which operates the vehicle's gearbox 113 is acted upon by one or more parameters which may be driver-dependent, i directly driver-dependent or driver- independent, e.g. the vehicle's angle of inclination, weight, type, ride comfort, accelerator pedal position, rate of accelerator pedal position change, performance choice, road speed and/or engine speed, to mention only some.

The vehicle 100 also has driveshafts 116, 117 ted to its tractive wheels 118, 119 and driven by an output shaft 120 from the gearbox 113 via an axle gear 121, e.g. a differential gear. The vehicle 100 schematically depicted in Figure IB has only two tractive wheels 118, 119 but embodiments of the invention are also applicable on vehicles with two or more driveshafts each provided with one or more tractive whee1 s . The vehicle 100 may also have a service brake system which may for example comprise brake discs 122-125 with associated brake linings (not depicted) situated alongside the wheels 118, 119. The contact pressure of the brake linings against the brake discs 122-125 when braking force is generated is controlled by the vehicle' s control system, e.g. by the control unit 115, which may be adapted to sending signals to the one or more regulators which regulate braking force in the service brake system, when the driver depresses a brake pedal or indicates in some other way that braking of the vehicle is desired. The vehicle may also have a cruise cont ol which may generate and send a control signal to brake the vehicle.

The control unit 115 may in certain embodiments be adapted to operating the vehicle' s service brake system. It may also, in other embodiments, be adapted to operating more of the vehicle' s other brake systems, if any. The vehicle may for example have a retarder 126 and/or other supplementary brake systems such as exhaust brakes and engine brakes . On the basis for example of commands from the driver, control signals will be sent to appropriate system modules to demand desired braking force . The retarder 126 may be adapted to cooperating with the service brake system, which it may inter alia be used to relieve with a view to reducing wear and risk of overheating of brake discs/linings 122-125,

The vehicle 100 may also have a driving cab in which a driver environment with instruments, operating controls etc. is provided in a conventional way. This driver environment may also comprise a viewing screen 130 for presentation of information for the vehicle' s driver . Information related to the vehicle' s gear changing may for example be presented there in certain embodiments, e.g. a gearshift diagram or a text/image which provides information about gears engaged and/or shift ranges for them.

The vehicle 100 may further comprise an input device 131 adapted to receiving an indication that a certain gear is preferred.. Such an indication may be given by the vehicle' ^' s driver while driving, by pressing a button or control device in certain embodiments. In other embodiments an indication that a certain gear is preferred may be programmed via supplementary software. The input device 131 in certain embodiment examples is situated in. the vehicle's driving cab, e.g. close to the gear lever or control device for the automatic gearbox 113.

The control system of the vehicle 100 may take the form of a communication bus system consisting of one or more communication buses for connecting- a. number of electronic control units (ECUs) , or controllers, to various components on board the vehicle. Such a control system may comprise a large number of controllers, and taking care of a specific function may be shared between two or more of them. A controller may also be adapted to taking care of two or more functions .

The control unit 115 may itself be adapted to communicating partly with other units in order to receive signals and measured values and possibly also to trigger a measurement, e.g. at certain intervals of time. The control unit 115 is further adapted to communicating for example via the vehicle ^f s communication bus, which may take the form of one or more from among a cable, a databus, e.g. a CAN (controller area network) bus, a MOST (media oriented systems transport) bus or some other bus configuration. The control unit 115 may also be arranged for wireless communication via a wireless interface in certain embodiments . The wireless interface may be in radio transmitter form based on wireless communication technology such as 3rd Generation Partnership Proj ect ( 3GPP) , Long Tβrm Evolution (LTE) , LTE Advanced, Evolved Universal Terrestrial Radio Access Network (E-UTRAN) , Universal Mobile Telecommunications System (UMTS), Global System for Mobile Communications /Enhanced Data rate for GSM Evolution (GSM/EDGE) , Wideband Code Division Multiple Access (WCDMA) , World-Wide Interoperability for Microwave Access (WiMax) , Wireless Local Area Network (WLAN) , Ultra Mobile Broadband (UMB) , Bluetooth (BT) , Near Field Communication (NFC) or infra-red transmitters, to mention only some conceivable examples of wireless communication.

For the sake of simplicity, Figure IB above shows only one control unit 115 covering various different control functions such as control of the engine 110, but the vehicle might in other embodiments have two or more control units among which the aforesaid control functions might be distributed .

In certain embodiments it is possible to specify a prioritised gear. The vehicle's driver or owner is thus enabled to choose a gear which is preferred for use on a certain section of road, e.g. in a mine environment, on wet road surfaces or on a muddy and/or potholed forest road. Such gear prioritisation may be conducted manually by the vehicle' s driver or via for example service market software.

Gear choice for the automatic gearbox 113 involves using one or more parameters such as rolling resistance, road gradient, vehicle combination weight, engine speed, outdoor temperature,, forecast engine speed in alternative gears, forecast power output in alternative gears, accelerating- power output, comfort level and/or vehicle speed, to mention only some examples. Allowing a. greater scope or range for this parameter or parameters for the prioritised gear makes it possible for automatic shifting to the prioritised gear to take place earlier than otherwise, and similarly for shifting from it to take place later than otherwise, as will be exemplified in more detail in the description of Figures 2A-2J.

The prioritised gear is given a larger parameter range, thereby imitating the desire of drivers to have the engine run a little faster on a level bend in specifically this prioritised gear instead for example of aiming at high gear and nigh load and therefore shifting up immediately when an opportunity arises .

In gear choice in the vehicle 100 the automatic system will endeavour to shift to the prioritised gear where this is possible. Aiming at few gear changes therefore does not apply in the same way for the prioritised gear in certain embodiments, and skipping this prioritised gear will require particular conditions or be completely impossible in certa.in embodiments .

This functionality comprising the prioritised gear with broadened parameter range does in certain embodiments not affect gear choice during other gear changes. It therefore does not affect, or does not appreciably affect, other driving, e.g. on other sections of road which include level ground and/or downhill runs, since driving in these conditions usually takes place in quite different gears. Driver knowledge of gear choice in for example mine situations as described above or the like is thus incorporated and reused while potentially maintaining the advantages of automatic gearchange in other respects. Moreover, since the prioritised gear is specified by the driver and/or the vehicle's owner with respect to a given application, the solution is not locked to a specific type of operation, since a certain gear may be prioritised, deprioriti sed or reprioritised dynamically depending on running condit xons .

A prioritised gear in one embodiment is chosen so long as the engine's safety limit allows in its upper speed range and so long as the engine copes with propelling the vehicle forwards in its lower speed range. Where an unexpected situation occurs and the vehicle needs to downshift quickly, the gearbox 113 will already be in automatic position and therefore able to shift down quickly before any risk of the engine stalling, ust as the driver would ish and without his/her needing- to act. Thus the vehicle's operation is improved and the driver' s control of the vehicle is facilitated.

Figure 2A illustrates an example of the relationship between rotation speed and torque in an engine 110 of the vehicle 100, and examples of changes in them during a gearchange process when a different, unpriori ised gear is engaged. When a gearchange para.met.er, e.g. the engine's speed, is found, to be within a range 220 for shifting to a different gear, the shift may take place in certain embodiments. The range 220 is bounded by a lower shift point 210 and a higher shift point 230. As previously discussed, gear changes by the vehicle's gearbox 113 may be affected by one or more parameters which may be driver-dependent, indirectly driver-dependent or driver-independent, e.g. the vehicle's angle of inclination, 5 weight, type, ride comfort, accelerator pedal position, rate of accelerator pedal position change, performance choice, road speed and/ or engine speed, to me tion only some. The example here illustrated with shift range 220 and shift points 210, 230 associated with engine speed is only to be 10 regarded as one example.

Figure 2B illustrates an example of the relationship betwee rotation speed and torque in an engine 110 of the vehicle 100, rather like the example in Figure 2A, but here for a prioritised, gear. The range within which shifting to this 15 gear takes place has here been enlarged by moving the shift points 210, 230.

An advantage of certain embodiments in which it is possible to prioritise a gear is that automatic gearchanging is possible without risk that up/downshift from the prioritised 20 gear might only make it possible to travel in a. different gear for a short section of road. Unnecessary up/downshifts may thus be avoided.

Figure 2C illustrates an example of the relationship between rotation speed and torque in an engine 110 of the vehicle

25 100, and examples of changes in them during a gearchange process with acceleration, from an unprioritised gear V (left diagram) to another unprioritised gear V+n (right diagram) , where n is a positive whole number greater than zero and smaller than the total number of the vehicle' s

30 gears . The parameter n denotes how many gears are potentially skippable; when n=l the next higher gear is engaged, when n=2 one gear is skipped and the next higher gear is engaged, and so on.

Where the engine's gearchange control parameter increases within the parameter range 220 and approaches an upper shift 5 point 230, a. shift to the higher unpriori tised. gear V+n takes place. The engine's speed then drops as a result of the higher gear ratio. In this situation a gearchange algorithm will often endeavour to engage as high a gear as possible in order to reduce the number of gear changes and 10 minimise or at least reduce fuel consumption. This often results in the choice of a higher gear V+n in which the engine speed after the shift is estimated to be just above the lower shift point 210 for this gear.

This example illustrates how the engine speed changes during 15 the gearshift. As already indicated, this does not necessarily mean that the shift, is controlled by engine speed .

Figure 2D illustrates an example of the relationship between rotation speed and torque in an engine 110 of the vehicle 20 100, rather like the situation in Figure 2C, but with the difference that the shift is now from a prioritised gear V (left diagram) to an unprioritised higher gear V+n (right diagram} .

The essential difference is that the parameter range 220 is 25 enlarged for the prioritised gear V by the lower shift point 210 having been lowered and/or the upper shift point 230 having been raised. Thus the vehicle may stay in the prioritised gear longer before shifting to the unprior.it ised gear V+n. An upshift is thus prevented in a situation where 30 a brief stretch of good and even road surface allows an upshift but a poorer road surface and/or a climb will shortly thereafter make it necessary to shift down again. Thus the driver may continue to drive on automatic gear and utilise all the attendant advantages such as quicker gear 5 changing,. and yet avoid unnecessary rapid gearshift reversals in response to brief changes in running situation or road surface state.

Figure 2E illustrates an example of the relationship between rotation speed and torque in an engine 110 of the vehicle 10 100, and examples of changes in them during a gearchange process with retardation, from an unprioritised gear V (left diagram) to another unprioritised gear V-n (right diagram} .

Where the engine's gearchange control parameter decreases within the parameter range 220 and approaches a lower shift 15 point 210, a shift to the lower unprioritised gear V-n takes place. The speed, of the engine then increases as a result, of the lower gear ratio in this gear.

Figure 2F illustrates an example of the relationship between rotation speed and torque in an engine 110 of the vehicle 20 100, rather like the situation in Figure 2E, but with the difference that the shift is now from a prioritised gear V (left diagram) to an unprioritised lower gear V-n (right diagram} .

As the conditions will soon change such that the prioritised 25 gear V again becomes optimum, which is the reason for the driver choosing to prioritise it, this gear is maintained until there is almost risk of the engine stalling, prompting a downshift to a gear which produces high power output .

Figure 2G illustrates an example of the relationship between 30 rotation speed and torque in an engine 110 of the vehicle 100 , and examples of changes in them during a gearchange process with deceleration, or retardation as mentioned above, from an unprioritised gear V-n (left, diagram) to another unprioritised gear V (right diagram} , This situation resembles that in figure 2E except that neither of the gears is prioritised.

Where the engine's gearchange control parameter decreases within the parameter range 220 and approaches a lower shift point 210, a shift to the lower prioritised gear V takes lace. The speed, of the engine then increases as a result, of the lower gear ratio in this gear.

Figure 2H illustrates an example of the relationship between rotation speed and torque in an engine 110 of the vehicle 100, rather like the situation depicted in Figure 2G, but with the difference that the shift is now from an unprioritised. gear V+n (left diagram) to an prioritised lower gear V (right diagram} with retardation.

Downshift to the prioritised gear V takes lace as early as possible, which also prevents this gear being skipped in response to the retardation.

Figure 21 illustrates an example of the relationship between rotation speed and torque in an engine 110 of the vehicle 100, and examples of changes in them during a gearchange process with acceleration, from an unprioritised gear V-n (left diagram) to another unprioritised gear V (right diagram). This scenario resembles that in figure 2C.

Figure 2J illustrates an example of the relationship between rotation speed and torque in an engine 110 of the vehicle 100, rather like the situation depicted in Figure 21, but with the difference that. the shift is here from an unpriori ised gear V-n (left diagram} to a prioritised lower gear V (right diagram) .

Shifting to the prioritised gear V takes place as early as possible and is of higher priority than _. , for example, lower fuel consumption. As it is desired to keep the prioritised gear V when it has been shifted to, it. is important that there be sufficient power to maintain it after the shift, so the engine speed needs to be not too low.

Figure 3 illustrates a general example of a combined flowchart and signalling diagram according to an embodiment of the invention . The method is divided into a number of steps 1-7 which are not necessarily part of every embodiment of the invention . Moreover, in certain embodiments these steps 1-7 may take place in a different order from that indicated by the numbering. Certain of them may possibly also take place in parallel with one another.

As a first step, the driver chooses to prioritise a gear, e.g. by means of an input devi ΟΘ J. -31 which may for example be situated in the driving cab close to a gear control, instrument panel, steering wheel or similar location readily accessible to the driver. The control unit 115 then detects that a certain gear is prioritised and therefore broadens the parameter range for this prioritised gear. A sensor 111 reads the gearchange control parameter and sends the result to the control unit. The control unit then compares the value read for the gearchange control parameter with the permissible broadened parameter range 220 and keeps the prioritised gear until either of the shift points 210, 230 is crossed. Where the control unit detects that the prioritised gear is not engaged, a control signal to engage it is sent when the parameter determined is within the broadened range, in certain embodiments.

Figure 4 illustrates an embodiment. example for the invention. The flowchart in Figure 4 illustrates a method 400 in a control unit 115 for operating an automatic gearbox 113 of a vehicle 100.

The object of the method 400 is to prioritise a certain gear and enlarge the permissible working range for this prioritised gear by broadening a parameter range 220 for it by adjusting at least one shift point 210, 230 which delineates the range 220 for a gearchange control parameter.

Such a gearchange control parameter may be based on one or more from among, for example, rolling resistance, road gradient, vehicle combination weight, engine speed, outdoor temperature, forecast engine speed in alternative gears, forecast power output in alternative gears, accelerating power output, comfort level and/or ^' vehicle speed.

The parameter range 220 is bounded by an adjustable lower- shift point 210 and an adjustable higher shift point 230, and in certain embodiments the lower shift point 210 is lowered to a level just above the risk of the engine stalling. Conversely, the upper shift point 230 may be raised to a level just below the risk of damage to the engine from running too fast when the parameter range 220 is enlarged for the gearchange control parameter.

The prioritised gear is thus given a larger engine speed range, especially for high engine speeds. The vehicle may thus imitate driver wishes in certain running situations such as mine operations, timber vehicles, off-road or other driving on wet or difficult running surfaces . IInn ssuucchh cciirrccuummssttaanncceess tthhee eennggiinnee iiss aalllloowweedd ttoo rruunn aa lliittttllee ffaasstteerr wwhheerree tthheerree iiss aa bbrriieeff iimmpprroovveemmeenntt iinn rrooaadd ssuurrffaaccee ssttaattee,, iinnsstteeaadd ffoorr eexxaammppllee ooff aaiimmiinngg aatt.. hhiigghh ggeeaarr aanndd hhiigghh llooaadd aanndd tthheerreeffoorree sshhiiffttiinngg uupp iimmmmeeddiiaatteellyy wwhheenn aann 55 ooppppoorrttuunniittyy aarriisseess.. GGeeaarr cchhooiiccee aallssoo aaiimmss aatt sshhiiffttiinngg ttoo tthhee pprriioorriittiisseedd ggeeaarr wwhheenn tthhiiss iiss ppoossssiibbllee.. TThhee ddeessiirree ffoorr ffeew ggeeaarr cchhaannggeess _. ,, wwhhiicchh iiss ootthheerrwwiissee uussuuaall iinn aann aauuttoommaattiicc ggeeaarrbbooxx,, tthheerreeffoorree ddooeess nnoott aappppllyy iinn tthhee ssaammee wwaayy ffoorr tthhee pprriioorriittiisseedd ggeeaarr,, aanndd aannyy ""sshhoorrttccuuttttiinngg"" ooff tthhiiss rreeqquuiirreess 1100 ccoonnddiittiioonnss..

This functionality with a prioritised gear does not affect gearshifts or gear choices in other gearchange situations, so other driving situations such as downhill runs or level ground are affected to only a limited extent or not at all, 15 since quite different engine speeds and gears are then involved .

This context entails building into the gearbox 113 a behaviour which largely resembles that of a driver of a vehicle with manual gearchange in the aforesaid difficult 20 conditions, while at the same time maintaining the advantages of automatic gearchange and also avoiding other solutions which employ complicated and expensive shift sequences and the like.

Where a gear can be prioritised, deprioritised or 25 repriori tised dynamically, the solution is not locked to a specific form of operation but may be altered or completely deactivated when the vehicle is used in some other type of dri ing .

To be able to properly control the automatic gearbox 113 of 30 the vehicle 100, the method 400 may comprise a number of ^ steps 401-406, but it should be noted that some of the steps here described, e.g. steps 405 and 406, occur only in certain alternative embodiments of the invention. Moreover, some steps may serve as alternatives to one another, depending on whether a certain condition is fulfilled or not, e.g. steps 404A and 404B. The steps 401-406 described may also take place in a somewhat different chronological order than indicated by the numerical order, and some of them may take place in parallel with one another. The method 400 comprises the following steps:

Step 401

A gear is prioritised when an indication is detected that, it is preferred by the vehicle's driver.

Such indications may in certain embodiments be received from an input device 131 adapted to receiving an indication that a certain gear is preferred by the vehicle's driver. In some embodiments such indications may be given by the driver- while driving, by pressing a button or control device. In other embodiments such indications may be received via specially programmed supplementary software. The input device 131 may in certain embodiment examples be situated in the vehicle' s driving cab, making it easier for the driver to effect such gear prioritisation while driving.

Step 402 A parameter range 220 for a gearchange control parameter is enla ged. This range is associated with the 401 prioritised gear, and its enlargement is effected by adjusting at least one shift point 210, 230 which delineates it.

Step 403 A parameter value is determined for the gearchange control parameter. For example, the gearchange control parameter may be determined, by measurement, by a sensor 111 in certain embodiments. Such measurement may take place continuously, or at a particular interval of time, in certain embodiments. It is also possible in certain embodiments that the gearchange control parameter may comprise a number of parameters, e.g. one or more from among the previously mentioned rolling resistance, road gradient, vehicle combination weight, engine speed, outdoor temperature, forecast engi e speed in alternative gears, forecast power output in alternative gears, accelerating power output, comfort level and/or vehicle speed.

Parameter value determination may in this case comprise assembling the respective parameters and calculating according to a compositely weighted algorithm the value of the gearchange control parameter, in certain embodiments.

Step 4G4-A

A shift to the 401 prioritised gear takes place when the 403 determined parameter value is within the 402 enlarged parameter range 220 and the 401 prioritised gear is not engaged .

The shift to the 401 prioritised gear may in certain embodiments take place as soon as is possible without risk of the engine stalling from running at too low a speed, nor of its suffering damage from running too fast.

In certain embodiments the control unit 115 is adapted to forecasting engine speed in an alternative gear which is not engaged and/or forecasting power output in alternative gears which are not engaged, to comparing at least one of these parameter values with respective engine speeds and power outputs for engaged gears, and to assessing whether it is possible to shift to the alternative gear when this is possible, on the basis of the forecast made. In certain embodiments the alternative gear is the prioritised gear.

In certain embodiments the control unit 115 may be adapted such that, when the 401 prioritised gear is not engaged, it forecasts engine speed and/or power output in the 401 prioritised gear, compares at least one of these parameter values with respective engine speeds and power outputs for engaged gears, and assesses whether it is possible to change to the 401 prioritised gear, on the basis of the forecast made ,

Step 404-B This step may be conducted in certain embodiments by the method 400 when the 401 prioritised gear is engaged but the 403 determined parameter value is outside the 402 enlarged parameter range 220.

A shift takes place from the 401 prioritised gear to a different gear.

The shift from the 401 prioritised gear may in certain embodiments take place only when there is risk of the engine stalling or disintegrating.

This may be achieved by enlarging the parameter range 220 for the gearchange control parameter and adjusting the shift points 210, 230.

An advantage of maximally enlarging the parameter range 220 is that shifting from the 401 prioritised gear may be avoided as far as possible. Step 405

This step may be performed in certain embodiments by the method 400.

Skipping of the 401 prioritised gear is suppressed, making it possible to specifically avoid skipping this prioritised gear during gearshifts, except in extreme situations such as a very rapid and large change in the gearchange control parameter .

Step 406 This step may be conducted in certain embodiments by the method 400,

The 401 prioritised gear is deprioritised when an indication is detected that this gear is no longer preferred by the vehic1e ' s d.river . Such indications may in certain embodiments be received from an input device 131 adapted to receiving an indication that, a certain gear is preferred by the vehicle's driver. In certain embodiments such indications may be given by the driver while driving, by pressing a button or control device. In other embodiments they may be received via. specially programmed supplementary software. The input device 131 may in certain embodiment examples be situated in the vehicle's driving cab, making it easier for the driver to effect such gear deprioritisation while driving. Figure 5 illustrates an embodiment of a control unit 115 adapted, to controlling gearchanging by an automatic gearbox 113 of a vehicle 100. This control unit 115 is configured to perform at least some of the method steps 401-406 described above in the description of the method. 400 for operating the automatic gearbox 113 of the vehicle 100. To be able properly to control gear changes by the automatic gearbox 113, the control unit 115 comprises a number of components described in more detail below, certain of which form part of some, but not necessarily all, embodiments. There may also be in the control unit 115 further electronics which are not entirel necessa y for unders anding its function according to the invention.

The control unit 115 comprises a circuit 510 adapted to receiving an indication that a gear is preferred by the vehicle's driver. This circuit is also adapted to receiving a parameter value for a gearchange control parameter.

For example, receiving such a parameter value involves a sensor 111 reading the instantaneous speed level of the vehicle' s engine 110. This sensor in this specific case is often called an engine speed sensor. The circuit 510 may also be adapted to receiving indications from a control device 131 in the vehicle's driving cab that a gear is preferred or no longer preferred by the driver.

The cont ol u it 1 5 comp ises also a processor ci cuit 520 adapted to prioritising a gear when an indication is detected that the respective gear is preferred by the vehicle's driver. The control unit is also adapted to enlarging a parameter range 220 for the gearchange control parameter, this range being associated with the prioritised gear. The enlargement of the range 220 may be effected by adjusting at least one of the shift points 210, 230. The processor circuit 520 is also adapted to determining the parameter value for the gearchange control parameter. It is also adapted, to initiating a shift to the prioritised gear when the parameter value determined is within the enlarged parameter range 220 and the prioritised gear is not engaged .

The processor circuit 520 may also be adapted to suppressing skipping of the prioritised gear in certain embodiments.

In certain embodiments the processor circuit 520 may also be adapted to deprioritising the prioritised gear when an indication is detected that this gear is no longer preferred by the ^' vehicle'' s driver.

The processor circuit 520 may also be adapted to forecasting engine speed in an alternative gear which is not engaged at the time and/or forecasting power output in alternative gears which are not engaged, to comparing at least one of these parameter values with respective engine speeds and power outputs for engaged gears, and to assessing- whether it is possible to shift to this alternative gear, on the basis of the forecast made, in certain embodiments. In certain embodiments the alternative gear is the prioritised gear.

In certain embodiments the processor circuit 520 may also, when the 401 prioritised gear is not engaged, be adapted to forecasting engine speed i the prioritised gear, to comparing at least one of these parameter values with respective engine speeds and power outputs for engaged gears, and to assessing whether it is possible to shift to the prioritised gear, on the basis of the forecast made.

The processor circuit 520 may for example take the form of one or more central processing units (CPUs), microprocessors or other logic configured to interpret and carry out instructions and/or to read and write data. The processor circuit may handle data for inflow, outflow or processing of data, including also buffering of data, control functions and the like. The processor circuit 520 may also be adapted to initiating a shift from the prioritised gear a d a shift to another gear when the prioritised gear is engaged but the parameter value determined is outside the enlarged parameter range 220, in certain embodiments. The processor circuit 520 may also be adapted to determining the gearchange control parameter on the basis of one or more from among rolling resistance, road gradient, vehicle combination weight, engine speed, outdoor temperature, forecast engine speed in alternative gears, forecast power output in alternative gears, accelerating power output, comfort level, vehicle speed.

In certain embodiments the control u it 115 comprises a memory unit 525 which serves as a storage medium for data. Such a memory may be adapted to storing information about a prioritised gear and a 220 determined parameter range for engaging it.

The memory unit 525 may for example take the form of a memory card, flash memory, USB memory, hard disc or other similar data storage unit, e.g. any from among ROM (read- only memory} , PROM (programmable read-only memory) , EPROM (erasable PROM) , flash memory, EEPROM (electrically erasable PROM) etc., in different embodiments.

The memory 525 may in certain embodiments be adapted to storing engine speed ranges 220 for engaging a certain gear, in the form of one or more shift points 210, 230. The control unit 115 comprises also a circuit 530 adapted to sending to the automatic gearbox 113 a control signal to shift to the prioritised gear.

The invention further comprises a computer programme for 5 gear changing by an automatic gearbox 11.3 of a vehicle 100. The programme is adapted to applying the method 400 according to at least one of the previously described steps 401-406 when the programme is executed in a processor- circuit 520 of the control unit 115.

10 The method 400 according to steps 401-406 for gear changing by an automatic gearbox 113 of the vehicle 100 may be implemented, by one or more processor circuits 520 in the control unit 115 in conjunction with computer programme code for performing one, several, certain or all of the steps

15 401-406 described above, A computer programme comprising instructions for doing so may thus perform steps 401-406 "when the programme is loaded in the ITOCΘ S S O2 Circuit 520.

Certain embodiments of the invention comprise also a system 500 for operation of an automatic gearbox 113 in a vehicle

20 100. Such a system 500 comprises a control unit 115 described above, a sensor 11 1 adapted to reading a. gearchange control parameter, an automatic gearbox 113 of the vehicle 100 and an input unit. 131 situated in the vehicle's driving cab and adapted to receiving an indication

25 from the vehicle's driver that a gear is preferred.

Some embodiments of the invention comprise also a vehicle 1.00 which is provided with the system 500 described above.