SE544441C2 - Method and control arrangement for operating an engine of a vehicle based on hardware limitations of the engine system; vehicle computer program and computer readable medium associated with the method - Google Patents

Abstract

A method and a control arrangement for operating an engine of a vehicle comprising a combustion engine system are presented. The method comprising:monitoring a temperature parameter associated with a hardware limitation of the combustion engine system and a first engine speed;determining a second engine speed based on the hardware limitation when the temperature parameter meets a temperature threshold value associated with the hardware limitation, wherein the first engine speed is associated with a first gear and the second engine speed is associated with a second gear; andrequesting a gear shift from the first gear to the second gear.Hereby, the components of the vehicle’s engine may be protected from excessive wear due to reaching or exceeding a hardware limitation of the combustion engine system and the risk of decreased engine component lifetime or even engine failure may be mitigated. Moreover, maximum vehicle performance may be obtained by reducing the risk of substantial drops of engine power output and decreased speed of the vehicle.

Description

lO METHOD AND CONTROL ARRANGEMENT FOR OPERATING AN ENGINE OF AVEHICLE BASED ON HARDWARE LIMITATIONS OF THE ENGINE SYSTEM;VEHICLE, COMPUTER PROGRAM AND COMPUTER READABLE MEDIUMASSOCIATED WITH THE METHOD Technical field The invention relates to a method and a control arrangement for operating an engineof a vehicle based on hardware limitations of the combustion engine system allowingprotection of the engine.

The invention also relates to a computer program and a computer-readable medium and a vehicle comprising such a control arrangement.

BackgroundThe following background description constitutes a description of the background to the invention, which does not, however, necessarily have to constitute prior art.

Motor vehicles such as cars, trucks and busses are expected to efficiently and reliablydeliver an engine torque requested by the vehicle's driver. Vehicle performance islimited for one or more reasons for example by the vehicle's hardware performance Iimitations such as a maximum power an engine in the vehicle can provide.

A combustion engine in a motor vehicle will operate efficiently and safely within its safeoperating temperature. A safe operating temperature is often specified with atemperature range which may vary depending on measurement point, and ranges froma minimum operating temperature to a maximum operating temperature. Outside thisrange of safe operating temperatures, the wear on the engine components mayincrease which may lead to decreased component lifetime or even to engine failure.The operating temperature of a combustion engine and its parts is transient anddepends on various parameters such as engine configuration, cooling system, load on the engine, etc. lO Today, in modern vehicles, the operating temperatures of various parts of an engineare monitored. ln situations when an operating temperature exceeds a desiredtemperature limit a common solution is to reduce the load on the engine e.g. byelectronically Iimiting the engine power output. The torque generated by the engine isthereby reduced which may lead to reduces vehicle speed. However, this solutionreduces the overall performance of the vehicle which may not be desirable forparticular vehicles since it may adversely affect the time efficiency of the vehicle. Forexample, the vehicle may not be able to follow its time schedule.

Summafllt is an objective of the present invention to provide a method and a control arrangement for mitigating or solving drawbacks of conventional solutions. ln particularan objective of the present invention is to provide a solution for operating an engine ofa vehicle preventing the hardware limitations of the engine and its components to bereached.

According to a first aspect of the invention, aforementioned and further objectives areachieved through a method for operating an engine of a vehicle comprising acombustion engine system, the method comprising monitoring a temperature parameter associated with a hardware limitation of thecombustion engine system and a first engine speed; determining a second engine speed based on the hardware limitation when thetemperature parameter meets a temperature threshold value associated with thehardware limitation, wherein the first engine speed is associated with a first gear andthe second engine speed is associated with a second gear; and requesting a gear shift from the first gear to the second gear.

A combustion engine system may here comprise at least one of: an internalcombustion engine, an engine cooling system, a turbo system, and an exhausttreatment system.

By monitoring a temperature parameter associated with a hardware limitation of thecombustion engine system, conditions which may be potentially dangerous to the lO vehicle's engine e.g. leading to a decreased lifetime of engine components or even an engine failure may be detected.

The combustion engine system may hereby be protected by requesting a gear changebased on a determined engine speed and thereby mitigating the risk of a temperatureparameter meeting a temperature threshold value associated with the hardware limitation.

Moreover, increased engine efficiency may be obtained by determining an engine speed so that favourable operating conditions are enabled.

Hereby, the components of the vehicle's engine may be protected from excessive weardue to reaching or exceeding a hardware limitation of the combustion engine systemand the risk of decreased engine component lifetime or even engine failure may bemitigated. Moreover, maximum vehicle performance may be obtained by reducing therisk of substantial drops of engine power output and decreased speed of the vehicle. ln an embodiment of the invention, the first gear and the first engine speed togetherprovide a first power and a first torque to drive wheels and the second gear and thesecond engine speed together provide a second power and a second torque to thedrive wheels, wherein the second power is within an interval comprising the first power and/or the second torque is within an interval comprising the first torque.

Here, the power provided to the vehicle's drive wheels may correspond to the powergenerated by the vehicle's engine and delivered to the vehicle's drive wheels by meansof the vehicle's drivetrain i.e. the components delivering the engine power to the drivewheels. The power delivered to the drive wheels will depend on the engine power andon the losses in the vehicle's drivetrain, including the losses in vehicle's gearbox. Thelosses in the vehicle's drive train may vary e.g. depending on which gear is applied.

Hereby, the second gear is selected enabling the power and/or the torque delivered tothe vehicle's drive wheels after a gear shift being maintained within an interval fromthe power or the torque delivered to the vehicle's drive wheels before the gear shift so lO that the risk of engine power output and vehicle speed deficit is reduced allowing a maximum vehicle performance. ln an embodiment of the invention, the method comprises requesting the gear shiftfrom the first gear to the second gear prior to requesting a torque reduction associated with the hardware Iimitation of the combustion engine system.

By requesting a gear shift from the first gear to the second gear and mitigating therebythe risk of a temperature parameter reaching or exceeding a temperature threshold, atorque reduction associated with the hardware Iimitation may not be necessary.However, if a torque reduction still needs to be performed, a smaller torque reductionmay be sufficient compared to the case when no gear shift is performed. Hereby, the vehicle's performance is improved. ln an embodiment of the invention, the method comprisesdetermining the second engine speed to be higher than the first engine speedwhen the temperature parameter exceeds the temperature threshold value.

Hereby, the engine can be controlled in a safe, efficient, and correct way, mitigatingthe risk of decreased lifetime of the engine components due to increased wear on the engine. ln an embodiment of the invention, the temperature parameter indicates a temperature or a change of a temperature of an engine coolant or an engine oil.

By monitoring the temperature or a change of a temperature of an engine coolant oran engine oil, the risk of engine overheating may be mitigated by increasing the speedof an oil pump and/or the speed of a water pump and a cooling fan in the vehicle's combustion engine system. ln an embodiment of the invention, the method comprisesdetermining the second engine speed to be lower than the first engine speedwhen the temperature parameter exceeds the temperature threshold value. lO Hereby, the engine can be controlled in a safe, efficient, and correct way, mitigatingthe risk of decreased lifetime of the engine components due to increased wear on the engine. ln an embodiment of the invention, the temperature parameter indicates a boosttemperature or a change of a boost temperature.

By monitoring the boost temperature or a change of the boost temperature in an engine, the risk of engine overheating may be determined and mitigated. ln an embodiment of the invention, the boost temperature or the change of the boost temperature is at an in|et manifold.

Hereby, the boost temperature may be monitored in a precise and controlled manner. ln an embodiment of the invention, the method comprises at least one of determining the second engine speed to be higher than the first engine speedwhen the temperature parameter exceeds the temperature threshold value and the firstengine speed is lower than a first engine speed threshold value; and determining the second engine speed to be lower than the first engine speedwhen the temperature parameter exceeds the temperature threshold value and the firstengine speed is higher than a second engine speed threshold value.

Hereby, the engine can be controlled to operate in an engine speed interval where arisk of torque reduction is minor and where a damage to the engine hardware is unlike to occur. ln an embodiment of the invention, the temperature parameter indicates a temperatureor a change of a temperature of an exhaust gas.

By monitoring the temperature or a change of the temperature of the exhaust gas, therisk of engine system overheating may be determined and mitigated. Moreover, a lO favorable distribution of fuel and air in the engine is obtained so that vehicle performance ls increased. ln an embodiment of the invention, the temperature, or the change of the temperature of the exhaust gas is at an engine outlet or at an exhaust treatment system.

Hereby, the engine can be controlled in a safe, efficient, and correct way so that therisk of engine failure due to overheating is mitigated and the engine performance is increased. ln an embodiment of the invention, the temperature parameter indicates a temperatureor a change of a temperature of a turbo compression.

By monitoring the temperature or a change of the temperature of the turbocompression, the risk of engine components overheating may be determined andmitigated. Moreover, a favorable distribution of fuel and air in the engine is obtained so that vehicle performance is increased ln an embodiment of the invention, the temperature, or the change of the temperature of the turbo compression is at a turbo compressor.

Hereby, the engine can be controlled in a safe, efficient, and correct way so that therisk of engine failure due to overheating is mitigated and the engine performance is increased. ln an embodiment of the invention, the method comprises obtaining map data and/or traffic data for an upcoming road section for thevehicle; and determining the second engine speed based on the hardware limitation and the map data and/or the traffic data for the upcoming road section. lO Hereby further parameters related to map data and/or traffic data are considered forimproved determination of the second engine speed. Thereby e.g. unnecessary gear change is avoided.

According to a second aspect, the invention re|ates to a control arrangement forcontro||ing vehicle comprising a combustion engine system, the control arrangementbeing configured to monitor a temperature parameter associated with a hardware limitation of thecombustion engine system and a first engine speed; determine a second engine speed based on the hardware limitation when thetemperature parameter meets a temperature threshold value associated with thehardware limitation, wherein the first engine speed is associated with a first gear andthe second engine speed is associated with a second gear; and request a gear shift from the first gear to the second gear. lt will be appreciated that all the embodiments described for the method aspects of theinvention are applicable also to at least one of the control arrangement aspects of theinvention. Thus, all the embodiments described for the method aspects of the inventionmay be performed by the control arrangement, which may also be a control device, i.e.a device. The control arrangement and its embodiments have advantagescorresponding to the advantages mentioned above for the methods and their embodiments.

According to a third aspect of the invention, aforementioned and further objectives areachieved through a vehicle comprising the control arrangement of the second aspect.

According to a fourth aspect, the invention re|ates to a computer program comprisinginstructions which, when the program is executed by a computer, cause the computerto carry out the method according to the first aspect.

According to a fifth aspect, the invention re|ates to a computer-readable mediumcomprising instructions which, when executed by a computer, cause the computer tocarry out the method according to the first aspect. lO Brief description of the drawingsEmbodiments of the invention will be illustrated in more detail below, along with the enclosed drawings, where similar references are used for similar parts, and where:Figure 1 illustrates an engine torque vs engine speed curve and engine power vsengine speed curve, Figure 2a illustrates a powertrain of an exemplary vehicle in which the invention maybe implemented, Figure 2b schematically illustrates a combustion engine system, Figure 3 shows a flow chart of a method for operating an engine of a vehicle accordingto an embodiment of the invention, Figure 4 shows a flow chart of a method for operating an engine of a vehicle accordingto an embodiment of the invention, and Figure 5 shows a control arrangement, in which a method according to any one of theherein described embodiments may be implemented.

Detailed descriptionA too high temperature of components of the combustion engine system may increase wear on the components and decrease their lifetime or even permanently damagethem which may lead to high costs for the vehicle owner. ln existing engine protection mechanisms, upon determining a temperature increasein the engine hardware, certain steps are performed by the engine to decrease thetemperature. When this fails, the maximum torque limit is decreased leading to reducedengine power and decreased speed of the vehicle.

Figure 1 shows a non-limiting example of an engine torque variation and an enginepower variation in a vehicle as a function of the vehicle's engine speed for two differentworking areas. A vehicle's working area corresponds to the vehicle's performanceduring a certain engine speed range. The curve 302a shows the vehicle's enginetorque as a function of the engine speed and the curve 304a shows the correspondingengine power of the vehicle as a function of engine speed at a first working area. Thecurves 302b and 304b show the vehicle's engine torque and the corresponding engine power at a second working area where the maximum torque level has been reduced lO from level A to level B. The maximum torque may be reduced so that the load on theengine is reduced when a component of the combustion engine system reaches or isabout to reach or exceed a temperature threshold value corresponding to a hardwarelimitation of the component. However, by reducing the maximum engine torque fromlevel A to level B, the engine power 304b is also reduced. Reduced engine power may e.g. lead to torque reduction and decreased speed of the vehicle. lt is an objective of the present invention to provide a method and a controlarrangement for controlling a vehicle such that these problems are at least partlysolved.

Figure 2a, which will be used to explain the herein presented embodiments,schematically depicts an exemplary vehicle 100 comprising a powertrain 140,configured to transfer a torque between combustion engine system 101, and drivewheels 111,The powertrain 140 comprises the combustion engine system 101 which will bedescribed further with reference to Figure 2b and a drivetrain 141 configured to transfera torque between the combustion engine system 101 and the drive wheels 111, 112.The drivetrain 141 comprises an output shaft 102, connecting in a conventional mannerthe combustion engine system 101 to a clutch 106, and via the clutch also to a gearbox103. An output shaft 107 from the gearbox 103 propels drive wheels 111, 112 via afinal drive 108, such as a common differential, and drive axles 104, 105 connected tosaid final drive 108. The clutch 106 can be a manually or automatically controlledclutch in a known manner, and the gearbox 103 can be arranged to be changed by thedriver of the vehicle 100 or automatically by the control system of the vehicle.

The combustion engine system 101 is controlled by a vehicle control system via acontrol arrangementThe control arrangement 160 may be distributed on several control units configured tocontrol different parts of the vehicle 100. The control arrangement 160 may e.g. includea temperature-monitoring unit 161, a speed-determining unit 162 and a gearshiftrequesting unit 163 arranged for performing the method steps of the disclosed lO lO invention as is explained further on. The control arrangement 160 and/or anothercontrol arrangement may further be configured for controlling one or more of the atleast the clutch 106, the gearbox 103, and/or any other units/devices/entities of thevehicle 100. However, in Figure 2a, only the units/devices/entities of the vehicle usefulfor understanding the present invention are illustrated. The control arrangementwill be described in further detail in FigureNow turning to Figure 2b, which shows an exemplified combustion engine system 101,as the one illustrated in Figure 2a. The combustion engine system 101 comprises apower source, e.g. an internal combustion engine 110. The internal combustion engine110 comprises an inlet manifold 121 conveying air to one or a plurality of cylinders 122of the internal combustion engine 110 for combustion with supplied fuel, such asgasoline or diesel via an injector 123. An engine torque MX is generated by therotational speed wx of the internal combustion engine 110 and conveyed to thedriveline 141 of the vehicle 100 via an output shaft 102 as mentioned with reference toFigure 2a. Exhaust gases resulting from the combustion are conveyed through anexhaust manifold 127 to the engine outlet 128. An oil pump, not shown in Figure 2b,circulates engine oil to the components of the engine for lubrication and for cooling the engine.

The combustion engine system 101 may also comprise a turbo system 120 such as aVGT (variable geometry turbocharger) unit, or a turbo unit with a waste gate arrangedfor compressing the air supplied for combustion in the internal combustion engine 110to increase the power of the internal combustion engine 110. The turbo system 120has a compressor 124 that is mechanically connected to a turbo turbine 125 via a shaft126. The air that is drawn into the combustion engine system is compressed in thecompressor 124 and then cooled down in a charge air cooler 129 before conveyedthrough the inlet manifold 121 into the cylinders 122. Exhaust gases from thecombustion process in the cylinders 122 are conducted through the turbo turbine 125,which imparts speed to the turbo compressor 124 via the shaft 126, and the exhaustgases may then pass through an exhaust treatment system 130 with one or moreaftertreatment components for aftertreatment (purifying) of exhaust gases resultingfrom combustion in the internal combustion enginelO ll The combustion engine system also comprises a cooling system for controlling enginetemperature. Cooling systems often comprise a circulating coolant circulating in acoolant circuit including the internal combustion engine 110 and a cooler, wherebyexcess heat is conveyed away from the internal combustion engine 110. The components of the cooling system are not shown in Figure 2b. lt is to be noted that the system described herein is only exemplary, and that accordingto embodiments of the invention, the vehicle may be of a kind where exhaust gasesare not subject to aftertreatment. The vehicle may also be of a kind where noturbocharger is used.

The proposed solution will now be described with reference to a method 200 disclosedin Figure 3. Figure 3 illustrates a flow chart of the method 200 for operating an engineof a vehicle 100 comprising a combustion engine system 101, the method 200comprising: ln step 210 in Figure 3 monitoring a temperature parameter Ti associated with ahardware limitation of the combustion engine system 101 and a first engine speed un; ln step 220 in Figure 3 determining a second engine speed m2 based on thehardware limitation when the temperature parameter Ti meets a temperature thresholdvalue TTh_i associated with the hardware limitation, wherein the first engine speed omis associated with a first gear g1 and the second engine speed wz is associated with asecond gear gz; and ln step 230 in Figure 3 requesting a gear shift from the first gear g1 to the second gear gz.

By executing the steps 210 - 230 of the method 200, the engine 110 of the vehiclemay be protected if a hardware limitation is or is about to be reached or exceeded bye.g. decreasing a temperature of a component of the vehicle's combustion enginesystem 101 and at the same time maintaining a power output level of the vehicle. ln other words, the method 200 may be executed to operate an engine of a vehicle100, such as the vehicle disclosed in Figure 2a, comprising a combustion enginesystem 101 such as the combustion engine system disclosed in Figure 2b. lOMonitoring the temperature parameter Ti, according to step 210 in Figure 3, may bedone according to any conventional method. As previously mentioned, the operatingtemperature of components of the combustion engine system 101, must be kept withina safe temperature range to protect the engine and its components from excessivewear, decreased lifetime and possibly even failure due to reaching or exceeding theengine's hardware limitation. The temperature parameter Ti may here be a parameterindicating a temperature of a combustion engine system component that must be keptbelow a temperature threshold value TTii_i in order not to reach or exceed a hardwarelimitation of the combustion engine system 101. The temperature threshold value Tfii_iassociated with the hardware limitation may be based on the engine characteristicsand be preconfigured in the control system of the vehicle 100. The first engine speedwi may be a current engine speed of the vehicle at the time the monitoring the temperature parameter Ti is performed.

Determining a second engine speed wz, according to step 220 in Figure 3, may in oneexample be done when the temperature parameter Ti, i.e. a temperature or atemperature change of an engine component, meets or is about to meet or exceed atemperature threshold value TTii_i associated with the hardware limitation. The secondengine speed wz may be determined such that the temperature of the enginecomponent is reduced when the second speed wz is applied to the vehicle's engine. lnone example, the first engine speed wi may be associated with a first gear gi and thesecond engine speed m2 may be associated with a second gear g2. The first gear gimay be higher or lower than the second gear gzdepending on application. The secondgear gz may be determined in a control arrangement of the vehicle 100 in aconventional way by using an appropriate gear selection algorithm. The method of gear selection is out of scope of this invention. ln step 230 in Figure 3, a gear shift from the first gear gi to the second gear gz isrequested. Requesting a gear shift from the first gear gi to the second gear gz, may inone example be done automatically by the vehicle's control systems e.g. via the controlarrangement 160 by receiving control signalling from the combustion engine system101 corresponding to a gear shift request and transmitting control signalling lOcorresponding to a gear shift request to the gearbox 103. ln another example, in caseof manual transmission in the vehicle, requesting a gearshift may be done by thecontrol arrangement transmitting gear shift request information to a driver of the vehiclee.g. via a graphical user interface (GUI) in the vehicle of by conventional methods. ln order to mitigate the risk of engine power decrease, it is, in embodiments of theinvention, proposed to determine a second engine speed w2 to reduce the temperatureof the component when the temperature of the component is getting too high and, ifpossible, maintain the engine power to not deteriorate the performance of the vehicle100, as will be explained further on.

The second engine speed w2 may, for example, be determined such that the enginepower P1 at the first engine speed w1 is maintained or reduced only by a minimum. lnan embodiment, the first gear g1 and the first engine speed w1 may together provide afirst power P1 and a first torque M1 to drive wheels 111, 112. ln similar way, the secondgear g2 and the second engine speed m2 may together provide a second power P2 anda second torque M2 to the drive wheels 111, 112. ln an embodiment, the second powerP2 may be within an interval comprising the first power P1. ln similar way, the secondtorque M2 may be within an interval comprising the first torque M1. ln one example the intervals may be predetermined.

Thus, as previously mentioned, the first power P1 and the second power P2 may be inthe same order of magnitude i.e. the power may be maintained after the gear shift or reduced only by a minimum.

A simplified relationship between engine power PX, engine torque MX and engine speedwx from the vehicle's engine 110 before transmission is shown in equation [1]:Px = MX * wx [1] The engine power P1 at the first engine speed w1 and a first engine torque M1 maytherefore be expressed by using the relationship in equation [1]:P1 = |\/|1 * 001 [2] The second engine speed w2 where the second engine power P2 is maintained orreduced only by a minimum compared to the first engine power P1 at the first engine lOspeed m1, may be expressed by using the relationship in equation [3], where M2 is thesecond engine torque:ou2= P2/ I\/I2 Where P2 = P1 [3] The power and torque provided to the vehicle's drive wheels 111, 112 and therotational speed after the transmission, e.g. rotational speed of a cardan shaft, dependon the applied gear and friction |osses in the drive train. The torque and the rotationalspeed will be affected by an applied gear ratio, while the transmitted power will remainmore or less constant, except for some |osses in the vehicle's drivetrain.

Maintaining the engine power at the second engine speed w2 in the same order ofmagnitude as at the first engine speed w1 may result in the second engine torque M2before the transmission being different from the first engine torque M1. However, thesecond torque M2 after the transmission i.e. delivered to the drive wheels 111, 112 ofthe vehicle 100 may be maintained within a required interval from the first torque M1,by shifting gears from a first gear g1 to a second gear g2. As previously mentioned, thesecond gear g2 may be determined in a control arrangement of the vehicle 100 in aconventional way by using an appropriate algorithm. The second gear g2 associatedwith the second engine speed w2, may in one example be determined so that thesecond power P2 and/or the second torque M2 provided to the drive wheels 111, 112of the vehicle 100 may be within an interval comprising the first power P1 and/or the first torque Mln an embodiment, requesting 230 a gear shift from the first gear g1 to the second gearg2 may be done prior to a torque reduction associated with the hardware limitation of the combustion engine system 101 is requested.

Thus, if the monitored temperature of a component of the vehicle's combustion enginesystem needs to be further reduced after the gear shift the vehicle's engine torque maybe reduced according to conventional methods. Reducing the engine torque after agear shift according to method 200, may result in a smaller torque reduction andimproved vehicle performance than if no gear shift was performed. lO ln addition to the method steps 210 - 230 described with reference to Figure 3 themethod 200 may in an embodiment comprise optional steps which are disclosed in the flow chart in Figurelt should be noted that the method steps i||ustrated in Figure 4 and described hereindo not necessarily have to be executed in the order i||ustrated in Figure 4. The stepsmay essentially be executed in any suitable order, as long as the physical requirementsand the information needed to execute each method step is available when the step is executed. ln step 210 in Figure 4, as described with reference to Figure 3, a temperatureparameter Ti associated with a hardware limitation of the combustion engine system101 and a first engine speed un is monitored. Monitoring the temperature parameterTi, may in one example be done by means of at least one temperature sensormeasuring the temperature of a combustion engine system component wherein thehardware limitation of the component may be defined by at least one temperaturethreshold value TTh_i. ln another example, the temperature parameter may bemonitored based on a simulated temperature or change of temperature of acombustion engine system component. Such simulation may be performed accordingto conventional methods based on e.g. an anticipated load on the vehicle's enginecorresponding to a propulsion force needed to propel the vehicle at a desired speed.For example, by using Newton's laws of motion the propulsion force may be calculatedfor each time instance based on parameters like the vehicle's mass, the inclination ofthe road in front of the vehicle to mention a few. The temperature or the change oftemperature of the component may be then calculated based on a theoretical model ofthe component's temperature as a function of the engine load.

The vehicle internal parameters like the vehicle's mass may be obtained from thevehicle's control system via one or more communication buses linking the controlarrangement 150 with various components and controllers located on the vehicle.Parameters associated with the characteristics of the road section in front of the vehicle may be obtained from map data as will be described further on. lOThe temperature parameter may be monitored continuously during the operation of thevehicle. As previously mentioned, the monitored temperature parameter may indicatea temperature and be associated with a first engine speed om which may e.g. be thespeed of the vehicle's internal combustion engine 110 at the time instance of thetemperature measurement. ln another example, the monitoring of the temperatureparameter may be done by determining a change of temperature, i.e. a temperaturederivative, and may be based on e.g. temperature measurements during at least twodifferent time instances. The monitored temperature parameter may in this caseindicate a temperature change and be associated with a first engine speed om whichmay e.g. be the speed of the vehicle's internal combustion engine 110 at the time instance of the most recent temperature measurement.

The temperature threshold value TTh_i associated with a hardware limitation of acomponent of the combustion engine system may in one example be preconfigured inthe vehicle and be based on the characteristics of the HW component e.g. operating temperature range. ln an optional step 212 in Figure 4, map data and/or traffic data is obtained. The mapdata and/or traffic data may in an embodiment be for or associated with an upcomingroad section for the vehicle 100. ln an embodiment, determining a second enginespeed wz in step 220 in Figure 4 may be based on the hardware limitation and theobtained map data and/or traffic data as will be explained further on.

Information for the upcoming road section may e.g. comprise topographicalinformation, like road gradients, curvature of the road section, anticipated stops ahead,speed limitations, traffic signs etc. Such information may be obtained from digital mapsin combination with positioning information, e.g. global positioning system (GPS)information. The positioning information may be used to determine the location of thevehicle relative to the map data so that the road section information may be extractedfrom the map data. Various present-day cruise control systems use map data andpositioning information. Such systems may then provide the system for the present invention with map data and positioning information. Moreover, information for the lOupcoming road section may comprise traffic related information, like information relatedto vehicles in front on the vehicle 100, traffic situation ahead, anticipated traffic stopsdue to e.g. trafficjam or a traffic accident ahead of the vehicle 100 etc. Such informationmay be received via traffic data. i.e. in communication from a traffic flow monitoringsystem. Such communication may, e.g. be received by means of V2l communication and/or wireless communication from at least one external communication entity. ln step 220 in Figure 4, a second engine speed wz is determined. As described withreference to Figure 3 the second engine speed wz is based on the hardware limitationwhen the temperature parameter Ti meets a temperature threshold value TTii_iassociated with the hardware limitation, wherein the first engine speed wi is associatedwith a first gear gi and the second engine speed m2 is associated with a second gear gz.

According to embodiments of the invention, determining the second engine speed wzmay be carried according to a procedure comprising one or more further steps I-Vi inFigureln step I in Figure 4, it is determined if the monitored temperature parameter Ti meetsor is about to meet or exceed a temperature threshold value TTii_i, wherein thetemperature threshold value Tiii_i is associated with a hardware limitation of acomponent of the combustion engine system 101. The temperature threshold valueTTii_i may in one example be preconfigured in the vehicle.

As previously explained, the temperature parameter may be a temperature or a changeof temperature of a component of the combustion engine system 101. ln one example,it may be determined that the monitored temperature parameter Ti meets or is aboutto meet or exceed a temperature threshold value TTii_i, if the monitored temperature ofthe component of the combustion engine system 101 is within an interval of thetemperature threshold value Tiii_i_ ln another example, it may be determined that themonitored temperature parameter Ti meets or is about to meet or exceed atemperature threshold value Tiii_i, if the monitored change of temperature, or thetemperature derivative, of the component of the combustion engine system 101indicates that the temperature of the component is about to reach the temperature lOthreshold value TTh_i within a predetermined time period. lf Yes (Y) in step I theprocedure continues to step ll, and if No (N) in step l, the procedure returns back tostepln an optional step ll in Figure 4, which may be executed if map data and/or traffic datafor an upcoming road section for the vehicle 100 was obtained in step 212, it may bedetermined if a gear shift is needed. For example, if it is determined, based on theobtained map data and/or traffic data that the vehicle is driving in or is about to enteran uphill slope, a gear shift to a higher gear may not be optimal. ln another example agear shift may not be needed if it is determined, based on the obtained map data and/ortraffic data, that the vehicle 100 is about to be braked to standstill or is about todecrease its speed. For example, a standstill position may be determined of if may bedetermined that the vehicle 100 is approaching a second vehicle, in front of the vehicle100, wherein the second vehicle is driving with a lower speed so that the vehicle 100.lf it is determined that a gear shift is not needed, the engine may be protected fromoverheating by requesting a torque reduction in step 240. lf Yes (Y) in step ll theprocedure continues to step lll, and if No (N) in step ll the procedure continues to stepln step lll in Figure 4, the second engine speed wz is determined to be higher than thefirst engine speed om so that the temperature of the monitored hardware componentmay be reduced. Step lll is executed when the temperature parameter Ti refers to a temperature or a change of temperature of an engine coolant or an engine oil.

Both the engine coolant, used in the engine cooling system of the combustion enginesystem for engine cooling and the engine oil, which may e.g. be used for lubricationand cooling of engine components, must be kept under a certain temperature toprevent the engine from overheating. By shifting gear resulting in a second enginespeed wz which is higher than the first engine speed un, a speed of a water pump inthe engine cooling system driving the hot coolant from the engine to a radiator forcooling may be increased. Moreover, a speed of a fan in the cooling system may alsobe increased. Thereby, the temperature of the coolant may be decreased. ln similarway, by increasing the engine speed to a second engine speed, the speed of the oil lOpump circulating the engine oil in the engine is increased which may result in increasedoil flow in the engine and thereby reduced engine oil temperature. When the second engine speed wz is determined, the procedure continues to stepln step IV in Figure 4, the second engine speed wz is determined to be lower than thefirst engine speed om so that the temperature of the monitored hardware componentmay be reduced. Step IV is executed when the temperature parameter Ti refers to aboost temperature or a change of boost temperature. The boost temperature refers tothe temperature of the compressed air from the turbo system 120 which has beencooled down in a charge air cooler 129 and conveyed through the inlet manifold 121into the cylinders 122 as explained with reference to Figure 2b. ln an embodiment, theboost temperature or the change of the boost temperature may be monitored at aninlet manifold 121. By decreasing the engine speed to a second engine speed wz theair flow through the turbo system will decrease due to decreased exhaust gas flowresulting in lower speed of the turbo turbine 125. Decreased airflow through the turbosystem will result in more efficient cooling in the charge air cooler 129 and thusdecreased boost temperature. When the second engine speed wz has been determined, the procedure continues to stepStep V in Figure 4 is executed if a temperature or a change of the temperature of amonitored hardware component may reach a temperature threshold when the enginespeed reaches above a maximum engine speed threshold (om as well when theengine speed drops below a minimum engine speed threshold (mm. ln other words, theengine speed needs to be within a certain engine speed interval, i.e. between a minimum engine speed threshold (mm and a maximum engine speed threshold wfhz. ln an embodiment, the monitored hardware component may be related to exhaust gas.ln one example, the engine speed interval may be between 1100 and 1500rpm. Toohigh exhaust gas temperatures may be obtained when the engine speed is above1500rpm as well as below 1100rpm. The temperature or the change of the temperatureof the exhaust gas may be determined at an engine outlet 128 or at an exhaust treatment systemlO ln a further embodiment, the monitored hardware component may be related to turbocompression. The temperature or the change of the temperature of the turbocompression may be determined at a turbo compressor 124. Engine speed outside therequired engine speed interva| may result in temperature increase due to unfavourable distribution of fuel and air in the engine. lf the first engine speed (oi is within the required engine speed interva|, i.e. Yes (Y) instep V, it may be determined that no engine speed change is needed to decrease thetemperature of the hardware component and the procedure may continue to stepOthervi/ise, if No (N) in step V, the procedure continues to step VI. ln step VI in Figure 4, the second engine speed (oz is determined based on the firstengine speed (oi and on the required engine speed interva|. ln an embodiment, when the temperature parameter Ti exceeds the temperaturethreshold value Tfii_i and the first engine speed (oi is lower than a first engine speedthreshold value (miii the second engine speed (oz may be determined to be higher thanthe first engine speed (oi and within the required engine speed interva| i.e. between aminimum engine speed (miii and a maximum engine speed (miiz. When thetemperature parameter Ti, in an embodiment exceeds the temperature threshold valueTfii_i and the first engine speed (oi is higher than a second engine speed thresholdvalue (miiz the second engine speed (oz may be determined to be lower than the firstengine speed (oi and within the required engine speed interva| i.e. between a minimumengine speed (miii and a maximum engine speed (miiz. When the second engine speed (oz has been determined, the procedure continues to stepAccording to another example, the determining of the second engine speed (oz mayfurther be based on engine characteristics specifying relevant engine speedsassociated with different hardware requirements. Thus, an appropriate engine speedmay be determined such that the temperature parameter Ti, is decreased below the temperature threshold value Tfii_i.

As previously described the second speed (oz is may be determined such that the engine power output for the first engine speed (oi associated with a first gear gi is lOmaintained or with a minimum reduction when the engine speed is changed to the second engine speed wz associated with a second gear gz. ln step 230 in Figure 4, a gear shift is requested as previously described with referenceto Figure 3. ln one example, the second gear g2 associated with the second enginespeed wz may be selected so that the second torque M2 delivered to the drive wheels111, 112 of the vehicle 100 after the gear shift to the second gear g2 may be maintainedwithin a required interval from the first torque M1, provided by the first gear gi and thefirst engine speed wi.

The optional step 240 in Figure 4 may be executed when the monitored temperatureof an engine component needs to be reduced further after a gear shift has beenperformed. Such temperature reduction may be done by requesting a reduction of the maximum delivered engine torque, as previously explained with reference to FigureAccording to an aspect of the invention, a control arrangement 160 for controlling avehicle 100 is presented wherein the vehicle 100 comprises a combustion enginesystem 101, the control arrangement 160 being configured to monitor 210 atemperature parameter Ti associated with a hardware limitation of the combustionengine system 101 and a first engine speed wi; determine 220 a second engine speedwz based on the hardware limitation when the temperature parameter Ti meets atemperature threshold value TTii_i associated with the hardware limitation, wherein thefirst engine speed wi is associated with a first gear gi and the second engine speedwz is associated with a second gear gz; and request 230 a gear shift from the first gear gi to the second gear gz.

The control arrangement 160 includes means 161 arranged for monitoring atemperature parameter Ti associated with a hardware limitation of the combustionengine system 101 and a first engine speed (m.

The control arrangement 160 further includes means 162 arranged for thereafterdetermining 220 a second engine speed wz based on the hardware limitation when thetemperature parameter Ti meets a temperature threshold value Tfii_i associated with lOthe hardware Iimitation, wherein the first engine speed om is associated with a first gear g1 and the second engine speed m2 is associated with a second gear gz.

The control arrangement 160 further includes means 163 arranged for requestinga gear shift from the first gear g1 to the second gear gz.

The control arrangement 160, e.g. a device or a control device, according to theinvention may be arranged for performing all of the above, in the claims, and in theherein described embodiments method steps. The control arrangement 160 is hereby provided with the above described advantages for each respective embodiment.

The invention is also related to a vehicle 100 including the control arrangement 160.Now turning to Figure 5 which illustrates the control arrangement 600/160, which maycorrespond to or may include one or more of the above-mentioned control units 161 -163 i.e. the control units performing the method steps of the disclosed invention. Thecontrol arrangement 600/160 comprises a computing unit 601, which can beconstituted by essentially any suitable type of processor or microcomputer, e.g. acircuit for digital signal processing (Digital Signal Processor, DSP), or a circuit havinga predetermined specific function (Application Specific Integrated Circuit, ASIC). Thecomputing unit 601 is connected to a memory unit 602 arranged in the controlarrangement 600/160, which memory unit provides the computing unit 601 with, e.g.,the stored program code and/or the stored data which the computing unit 601 requiresto be able to perform computations. The computing unit 601 is also arranged to storepartial or final results of computations in the memory unitln addition, the control arrangement 600/160 is provided with devices 611, 612, 613,614 for receiving and transmitting input and output signals. These input and outputsignals can contain waveforms, impulses, or other attributes which, by the devices 611,613 for the reception of input signals, can be detected as information and can beconverted into signals which can be processed by the computing unit 601. Thesesignals are then made available to the computing unit 601. The devices 612, 614 for the transmission of output signals are arranged to convert signals received from the lOcomputing unit 601 in order to create output signals by, e.g., modulating the signals, which can be transmitted to other parts of and/or systems in the vehicleEach of the connections to the devices for receiving and transmitting input and outputsignals can be constituted by one or more of a cable; a data bus, such as a CAN bus(Controller Area Network bus), a MOST bus (Media Orientated Systems Transportbus), or some other bus configuration; or by a wireless connection. A person skilled inthe art will appreciate that the above-stated computer can be constituted by thecomputing unit 601 and that the above- stated memory can be constituted by the memory unitControl systems in modern vehicles commonly comprise communication bus systemsconsisting of one or more communication buses for linking a number of electroniccontrol units (ECU's), or controllers, and various components located on the vehicle.Such a control system can comprise a large number of control units and theresponsibility for a specific function can be divided amongst more than one control unit.Vehicles of the shown type thus often comprise significantly more control units thanare shown in Figures 1 and 4, which is well known to the person skilled in the art within this technical field. ln a shown embodiment, the invention may be implemented by the one or more abovementioned control units 161, 162 and 163. The invention can also, however, beimplemented wholly or partially in one or more other control units already in the vehicle100, or in some control unit dedicated to the invention.

Here and in this document, units are often described as being arranged for performingsteps of the method according to the invention. This also includes that the units are designed to and/or configured to perform these method steps.

The one or more control units 161 , 162 and 163 are in Figure 2a illustrated as separateunits. These units may, however, be logically separated but physically implemented inthe same unit or can be both logically and physically arranged together. These unitsmay e.g. correspond to groups of instructions, which can be in the form of programming lOcode, that are input into, and are utilized by a processor/computing unit 601 when the units are active and/or are utilized for performing its method step, respectively.

The person skilled in the art will appreciate that the herein described embodiments forcontrolling an engine may also be implemented in a computer program, which, whenit is executed in a computer, instructs the computer to execute the method. Thecomputer program is usually constituted by a computer program product 603 storedon a non-transitory/non-volatile digital storage medium, in which the computer programis incorporated in the computer-readable medium of the computer program product.The computer-readable medium comprises a suitable memory, such as, e.g.: ROM(Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (ErasablePROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk unit, etc.The invention is not limited to the above described embodiments. lnstead, the inventionrelates to, and encompasses all different embodiments being included within the scopeof the independent claims.

Claims (18)

1. A method (200) for operating an engine of a vehicle (100) comprising a combustionengine system (101 ), the method (200) comprising monitoring (210) a temperature parameter (Ti) associated with a hardwarelimitation of the combustion engine system (101) and a first engine speed (w1); determining (220) a second engine speed (oo2) based on the hardware Iimitationwhen the temperature parameter (Ti) meets a temperature threshold value (TTii_i)associated with the hardware limitation, wherein the first engine speed (w1) isassociated with a first gear (g1) and the second engine speed (m2) is associated witha second gear (g2); and requesting (230) a gear shift from the first gear (g1) to the second gear (g2).

2. The method (200) according to c|aim 1, wherein the first gear (g1) and the first enginespeed (m1) together provide a first power (P1) and a first torque (M1) to drive wheels(111, 112) and the second gear (g2) and the second engine speed (w2) togetherprovide a second power (P2) and a second torque (M2) to the drive wheels (111, 112),wherein the second power (P2) is within an interval comprising the first power (P1)and/or the second torque (M2) is within an interval comprising the first torque (M1).

3. The method (200) according to c|aim 1 or 2, wherein the method (200) comprises requesting (230) the gear shift from the first gear (g1) to the second gear (g2) priorto requesting a torque reduction associated with the hardware Iimitation of thecombustion engine system (101).

4. The method (200) according to any one of the preceding claims, wherein the method(200) comprises determining (220) the second engine speed (002) to be higher than the first enginespeed (m1) when the temperature parameter (Ti) exceeds the temperature threshold value (TTh_i). lO

5. The method (200) according to claim 4, wherein the temperature parameter (Ti)indicates a temperature or a change ofa temperature ofan engine coolant or an engine oil.

6. The method (200) according to any one of claims 1-3, wherein the method (200)comprises determining (220) the second engine speed (ooz) to be lower than the first enginespeed (mi) when the temperature parameter (Ti) exceeds the temperature threshold value (TTii_i).

7. The method (200) according to claim 6, wherein the temperature parameter (Ti) indicates a boost temperature or a change of a boost temperature.

8. The method (200) according to claim 7, wherein the boost temperature or the change of the boost temperature is at an in|et manifold (121).

9. The method (200) according to any one of claims 1-3, wherein the method (200)comprises at least one of determining (220) the second engine speed (ooz) to be higher than the first enginespeed (mi) when the temperature parameter (Ti) exceeds the temperature thresholdvalue (Tfii_i) and the first engine speed (mi) is lower than a first engine speed thresholdvalue (wfiii); and determining (220) the second engine speed (ooz) to be lower than the first enginespeed (mi) when the temperature parameter (Ti) exceeds the temperature thresholdvalue (Tfii_i) and the first engine speed (wi) is higher than a second engine speedthreshold value (wfiiz).

10. The method (200) according to anyone of claims 1-6 or 9, wherein the temperatureparameter (Ti) indicates a temperature or a change of a temperature of an exhaust gas. lO

11. The method (200) according to claim 10, wherein the temperature or the changeof the temperature of the exhaust gas is at an engine outlet (128) or at an exhausttreatment system (130).

12. The method (200) according to claim 9, wherein the temperature parameter (Ti) indicates a temperature or a change of a temperature of a turbo compression.

13. The method (200) according to claim 12, wherein the temperature or the changeof the temperature of the turbo compression is at a turbo compressor (124).

14. The method (200) according to any one of the preceding claims, wherein themethod (200) comprises obtaining (212) map data and/or traffic data for an upcoming road section for thevehicle (100); and determining (220) the second engine speed (wz) based on the hardware Iimitationand the map data and/or the traffic data for the upcoming road section.

15. A control arrangement (160) for contro||ing vehicle (100) comprising a combustionengine system (101 ), the control arrangement (160) being configured to monitor (210) a temperature parameter (Ti) associated with a hardware Iimitationof the combustion engine system (101) and a first engine speed (w1); determine (220) a second engine speed (wz) based on the hardware Iimitationwhen the temperature parameter (Ti) meets a temperature threshold value (Tfh_i)associated with the hardware Iimitation, wherein the first engine speed (un) isassociated with a first gear (g1) and the second engine speed (m2) is associated witha second gear (g2); and request (230) a gear shift from the first gear (g1) to the second gear (gz).

16. A vehicle (100) comprising a control arrangement (160) according to claim 15.

17. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method (200) according to any one of the claims 1 to

18. A computer-readable medium comprising instructions which, when executed by acomputer, cause the computer to carry out the method (200) according to any one ofthe claims 1 to 14.