A method for combined management of a system for modulating a cooling air flow rate and a cooling fan of one or more heat exchange units of a vehicle with electric powertrain

Abstract

There is described a method for the combined management of a cooling air flow rate modulation system (AGS ) and of a cooling fan ( F) of one or more heat exchange units (CNDS, RAD) of a vehicle with an electric powertrain, wherein the cooling is managed dynamically and with a reduced consumption of electric power.

Description

[0001] "A method for combined management of a system for modulating a cooling air flow rate and a cooling fan of one or more heat exchange units of a vehicle with electric powertrain"

[0002] ★ ★ ★ ★

[0003] TEXT OF THE DESCRIPTION

[0004] Field of the Invention

[0005] The present invention relates to vehicles with an electric powertrain, speci fically to BEVs . The invention was developed with reference to the management of the thermal evolution profile of said vehicles .

[0006] Known Art

[0007] The vehicles with an electric powertrain generally comprise a pair of radiating elements ( i . e . , heat exchange elements ) arranged in such a position as to intercept a cooling air flow rate during the advancement of the vehicle . A diagram of such a configuration is shown in Figure 1 .

[0008] Such radiating elements comprise a condenser CNDS and a radiator RAD, the former being arranged in front of the latter in the advancement direction of the vehicle , so that an air flow rate mAirintercepted during the advancement impinges first upon the condenser CNDS and then upon the radiator RAD ( after traversing the condenser CNDS ) .

[0009] With further reference to the Figures 8 , 9 , 10A, 11A, the condenser SNDS is traversed by a refrigerant fluid ( flow rate riiRfr} which is caused to change its phase ( from gas to liquid) . The refrigerant fluid circulates in a refrigerant cycle system which further comprises a compressor C and at least one evaporation element EVAP, CHL of the same fluid . The at least one evaporation element comprises an evaporator EVAP of an air conditioning system for the passenger compartment of the vehicle ( so-called cabin evaporator ) , and preferably at least one chiller CHL for cooling a corresponding high-voltage battery of the vehicle ( the high-voltage battery, as is commonly known, supplies the electric traction motors of the electric powertrain of the vehicle ) .

[0010] The radiator RAD is traversed by a coolant ( flow rate 'rhcint ') which does not undergo phase changes during the circulation, and which circulates in a plurally branched hydraulic circuit comprising, i . a . , a cabin heater CB_HT which is part of the air-conditioning system mentioned in the foregoing, a cooling circuit M of each electric motor, and a cooling circuit BT of the high- voltage battery, the latter being in a heat exchange relation with the one or more corresponding chillers CHL .

[0011] Upstream of the set of heat exchange devices described in the foregoing ( condenser and radiator ) there is arranged an active modulation device of the air flow rate denoted by the reference AGS in Figure 1 . The reference corresponds to the acronym which is commonly used to refer to this type of devices , i . e . Active Grille Shutter . The device AGS comprise , as is commonly known, a plurality o f louvers LV which can be oriented by rotation around respective rotation axes orthogonal to the plane of the drawing, in such a way as to define a passage section which enables the transit of an air flow rate frtAir AGS varying from a maximum value , wherein all the louvers LV are rotated to be substantially aligned with the direction of the air flow rate to a minimum value wherein all the louvers LV are united to define a blind wall which is substantially impermeable to the air flow rate mAir( therefore , rii-Air=m-Air-AGS=0) .

[0012] Downstream of the unit of heat exchange devices described in the foregoing ( condenser and radiator ) , i . e . downstream of the device AGS , there is moreover arranged a cooling fan F, configured to generate an air flow rate riiAir FANthrough the unit of heat exchange devices for the cooling needs of said devices (phase change - condensation - in the condenser CNDS , and temperature decrease of the coolant in the radiator RAD) . The flow rate riiAir_FAN is inparticular generated as a further flow rate in addition to the flow rate riiAir AGS r so as to increase the flow rate mAirup to values that cannot be reached naturally with the advancement of the vehicle and only with the device AGS in the configuration of the maximum passage area .

[0013] Both the device AGS and the fan F are therefore adapted to influence the amount of the air flow rate which impinges upon the unit of heat exchange devices . Both devices , however, operate based on speci fic needs : in the case of the device AGS , such needs may comprise the increase of the aerodynamic ef ficiency of the vehicle and the cooling of the unit of heat exchange devices , but also an operation for preventing aging and j amming, whereas for the fan F the cooling needs add up to the need of reducing noise emissions . In the known art , such needs are satis fied only individually, without attempting to reach a synergy or any goal of global energy ef ficiency of the vehicle , with the result of j eopardi zing the latter in order to satis fy the individual needs .

[0014] Obj ect of the Invention

[0015] The invention aims at solving the technical problem outlined in the foregoing . Speci fically, the obj ect of the invention consists in providing a method for the combined management of a cooling air flow rate modulation system (AGS ) and of a cooling fan of one or more heat exchange units of a vehicle with an electric powertrain, which enables satis fying the needs of each device (AGS and fan) synergically and ef ficiently as regards energy consumption .

[0016] Summary of the Invention

[0017] The obj ect of the invention is achieved by means of a method having the features set forth in the claims that follow, which form an integral part of the technical disclosure provided herein in relation to the invention .

[0018] Brief Description of the Figures

[0019] The invention will now be described with reference to the annexed Figures , which are provided by way of non-limiting example only, and wherein :

[0020] - Figure 1 shows a unit of heat exchange devices assisted by a cooling air flow rate modulation system AGS and by a cooling fan, for which a method according to the invention may be implemented,

[0021] - Figure 2 shows a flow diagram exempli fying the method according to the invention,

[0022] Figure 3 shows a functional block diagram exempli fying the method according to the invention,

[0023] - Figures 4 to 7 each show diagrams exempli fying determinations operated in the execution of the method according to the invention,

[0024] - Figures 8 and 9 show a circuit diagram of a refrigerant cycle circuit on board the vehicle whereon the method according to the invention is implemented, and

[0025] - Figures 10 to 23 show, in the same way as Figures 4 to 7 , diagrams exempli fying determinations operated in the execution of the method according to the invention .

[0026] Detailed Description

[0027] With reference to Figures 2 , 3 and - for the circuit references - Figures 8 , 9 and 10A, 11A, reference number 1 generally denotes a method for the combined management of a cooling air flow rate modulation system AGS and of a cooling fan F of one or more heat exchange units EVAP, RAD of a vehicle with an electric powertrain . As a general premise , every time the following ( and previous ) description makes reference to a fluid or liquid flow rate , said flow rate shall be understood as a mass flow rate , and to this end it is denoted with a reference which starts with m (unit of measure : [ kg / s ] or corresponding multiples or submultiples ) . Any deviation from said premise is explicitly indicated, where needed .

[0028] This being said, the vehicle generally comprises ( for the description of the individual components reference is being made to the previous as well as to the following description) :

[0029] - a first refrigerant cycle circuit Cl through which a refrigerant fluid flows , the first circuit comprising a first heat exchange unit including a condenser CNDS , and further including at least one evaporator EVAP, CHL, and a compressor C, a second cooling circuit C2 through which a coolant flows , the second circuit C2 comprising a second heat exchange unit including a radiator RAD for the coolant ,

[0030] - an air flow rate modulation device AGS arranged upstream of the condenser CNDS , the air flow rate modulation device AGS having a variable passage area configuration that results in a first cooling air flow rate mAtr AGSvarying from a minimum or zero value to a respective maximum value , a cooling fan F arranged downstream of the modulation device AGS and configured to generate a second cooling air flow rate rii-Air FAN through the condenser CNDS and the radiator RAD, wherein the condenser CNDS of the first circuit Cl is installed on the vehicle in front of the radiator RAD of the second circuit C2 in a flow direction of a total air flow rate mAtrfed through the condenser CNDS and the radiator RAD, the method including :

[0031] - defining (block 2 ) a maximum value mAtr Maxof the total air flow rate mAtrtraversing the condenser CNDS and the radiator RAD as a function of a vehicle advancement speed Vehicle_Speed and of a maximum rotational speed FANSpd MAXof the cooling fan F,

[0032] - defining a first target value fiiRad Airjr,gt (block 4 ) of an air flow rate vhRad Atrtraversing the radiator RAD and being in heat exchange relation with the coolant flowing therethrough as a function of a target value TRCUI cint out Tgt of the temperature of the coolant leaving the radiator RAD,

[0033] - defining a second target value riiCndsAir Tgt (block 6 ) of an air flow rate mCnds Airtraversing the condenser CNDS and being in heat exchange relation with the refrigerant fluid flowing therethrough as a function of a target pressure value PRfr@cnd.sTgt of the refrigerant fluid flowing through the condenser ; preferably, according to the invention the target value PRfr@cndsTgt is determined in such a way as to reduce an overall consumption of electric power by the vehicle V, as described in the following (block 8 ) ,

[0034] - determining (block 10 ) a target value mAir Tgtof the total air flow rate riiAtr traversing said condenser CNDS and said radiator RAD as a function of the first target value diRad Air Tgt, of the second target value mends Air Tgt t and also as a function of said maximum value ^-Atr Max of the total air flow rate idAir, defining (block 12 ) a target passage area configuration AGSOperdngjgtof said cooling air flow rate modulation device AGS as a function of said target value ^-Atr Tgt of the total air flow rate ThAir, and as a function of the advancement speed of the vehicle Vehicle_Speed ,

[0035] - defining (block 14 ) a target value FANSpd Tgtfor the rotational speed of said cooling fan F as a function of said target value ThAir Tgtof the total air flow rate as a function of the advancement speed of the vehicle Vehicle_Speed, and as a function of a noise emission target for the cooling fan F,

[0036] - operating said cooling air flow rate modulation device and said fan in accordance with said target passage area configuration AGSOpening Tgt, and with said target value FANSpd Tgtof the rotational speed of said cooling fan F, respectively .

[0037] The following Figures 4 to 7 and 10 to 23 schematically and individually show the preferred procedures for the determinations and the deductions operated in the method according to the invention .

[0038] With reference to Figure 4 , diagram 20 ( corresponding to the block 2 of the Figures 2 and 3 ) , the determination of the maximum value 'fhAir Maxof the total air flow rate ihAtrwhich may flow through the condenser CNDS and the radiator RAD is operated by means of a map M22 which uses , as input data, a maximum rotational speed FANSpd MAXof the cooling fan F (which is the variable on the X-axis ) and the advancement speed of the vehicle Vehicle_Speed , which is the variable according to which the curves of maximum flow rate riiAir_Max are parametri zed . Speci fically, the curves on the map M22 correspond to values of advancement speed Vehicle_Speed = VS1, VS2, VS3, VS4, with VS1 > VS2 > VS3 > VS4.

[0039] With reference to Figure 5 , diagram 30 ( representative of the block 4 in Figure 2 and in Figure 3 ) , the determination of the first target flow rate value ^Rad Air Tgt traversing the radiator RAD and being in heat exchange relation with the coolant flow rate 'rhRadcint flowing therethrough as a function of a target temperature value TRad Cint Out Tgtof the coolant leaving the radiator RAD comprises defining the first target flow rate value riiRad_Air_Tgta sthe sum (block 32 ) of a value '^lRad_Atr_Tgt_OL determined by open-loop calculation and a value mRad Air Tgt CLdetermined by closed-loop calculation .

[0040] With reference to Figure 6 , diagram 40 , the value ^Rad Air Tgt OL determined by open-loop calculation is determined as a function of :

[0041] - a target value mRad ctnt Tgtof the coolant flow rate traversing the radiator RAD,

[0042] - a ratio Q Rad Ctnt / (j^Rad Ctnt In ~ ^Rad Air In) i wherein QRad_cint isathermal power that the radiator shall dispose of to meet the target temperature value of the coolant TRad_cint_out Tgt leaving the radiator RAD, TRad ant Inis a temperature of the coolant entering the radiator RAD, whereas TRad Air Inis a temperature of the air flow rate

[0043] Rad Air which impinges upon and traverses the radiator RAD and which is in heat exchange relation with the flow rate mRad Cint. Thanks to the arrangement of the radiator RAD downstream of the condenser CNDS , the temperature TRad_Atr_in is equal to a temperature of the air downstream of traversing the condenser CNDS ( and therefore at the outlet of the condenser CNDS ) , denoted with the reference Tcnds_Atr_outand being calculated at block 6 ( Figures as referred to in the following description) .

[0044] On an operational level , the target value mRad ctnt Tgtand the ratio QRad_cint / (TRad Cint ln- TRad Air^ are used as input data into a map M42 which then outputs the value mRad Air Tgt OL • The ratio Q Rad Ctnt / (j^Rad Ctnt In ~ TRad Airjn) is the variable on the X-axis - the blocks 44 ( di f ference ) and 46 ( division) define said ratio - whereas the flow rate rh-Rad ctnt Tgt is the variable according to which the curves on the map M42 are parametri zed . By way of example , the map M42 shows four curves , each being associated with a respective value rilRadcint_Tgt 1, ™Rad_Clnt_Tgt 2 ! i ^Rad Ctnt Tgt^ r > ™Rad_Clnt Tgt with tilRadcint Tgt 1 < Rad Ctnt Tgt 2 < W-Rad Ctnt Tgt^ < W-Rad cint Tgt 4. From a qualitative point of view, the value iTT-Rad_Air Tgt_OL increases as the target flow rate ™Rad_cint_Tgt decreases and as the ratio Q Rad_Clnt I (rRadcintjn TRad Atr jn) increases .

[0045] With reference to Figure 7 , diagram 50 , the value rh-Rad Air Tgt CL is determined by means of a proportionalintegral control 51 as a function of a di f ference 52 between a current value TRad Cint Outof the temperature of the coolant leaving the radiator RAD and the target temperature value of the coolant TRad Cint Out Tgt. The proportional-integral control 51 comprises moreover an upper saturation limit 53 equal to a di f ference 54 between the maximum value mAtr Maxof the air flow rate traversing the condenser CNDS and the radiator RAD and the value determined by open-loop calculation mRad_Atr_Tgt_OL r and a lower saturation limit 55 equal to a zero value (block 56 ) .

[0046] The following description concerns the calculation of a second target value mcndsjdr Tgt °fanain flow rate mCndsAir traversing the condenser CNDS and being in heat exchange relation with the refrigerant fluid flowing through the condenser, as a function of a target value PRfr@cndsTgt of the pressure of the refrigerant fluid flowing through the condenser CNDS . As will become apparent in the following description, this ultimately concerns also the determinations as per block 4 , since among the values of the state variables of the refrigerant fluid and of the air in the control volume of the condenser CNDS there is also the temperature Tcnds_Air_out of theairdownstream of traversing the condenser CNDS , which corresponds to the temperature of the air upstream of the radiator RAD . Therefore , the Figures 10 to 19 commented in the following shall be considered as representative of the deductions operated by the block 6 .

[0047] Referring to the Figures 1 , 8 , the first circuit Cl is traversed by a refrigerant fluid as a working fluid of a refrigerant cycle , which implies that the refrigerant fluid undergoes phase changes during the cycle . In a way known per se , the first circuit Cl comprises , in addition to the aforementioned condenser CNDS (wherein the phase change gas-to-liquid of the refrigerant fluid takes place ) , a cabin evaporator EVAP, preferably one or more chillers CHL (which are further evaporation devices for the cooling needs of the powertrain, as described with reference to the following Figures 10A, 11A, a compressor C having an intake in fluid communication with an outlet of the evaporator EVAP and a delivery in fluid communication with an inlet of the condenser CNDS , and an expansion ( or throttling) valve EXV having an inlet in fluid communication with an outlet of the condenser CNDS , and an outlet in fluid communication with an inlet of the evaporator EVAP . The valve EXV may by electrically actuated, or it may be purely mechanical , with a shutof f valve associated therewith .

[0048] Upstream the valve EXV, directly at the outlet of the condenser CNDS , there are arranged a first pressure sensor PS I and a first temperature sensor TS1 , configured to detect the pressure (PRfr@cnds) and the temperature CTRfr@cnd.sOut ') of the refrigerant fluid at the outlet of the condenser . The reference mRfrin Figure 8 ( as well as in the other Figures ) denotes a mass flow rate of refrigerant fluid circulating in the circuit Cl . Figures 1 and 8 moreover show - also graphically, though schematically - the mass flow rate friends Air traversing the condenser CNDS ( and, downstream thereof , the radiator RAD) .

[0049] It shall be kept in mind that the flow rate riiCncis Airis the result of the supply by the fan F in combination with a supply of a dynamic nature during the advancement of the vehicle (mediated by the device AGS ) ; therefore , when the vehicle travels in reverse gear or does not move , the air flow rate is supplied only by the fan F . This is due to the fact that the condenser CNDS is preferably arranged upstream of the exchanger RAD in a direction of advancement of the vehicle . In the preferred embodiments of the invention - such as those shown in Figure 1 - the fan F is arranged downstream of the heat exchanger RAD in the flow direction of the flow rate ends Air and with respect to the direction of advancement of the vehicle , so that the flow rate riiCnds Airis the result both of the dynamic action due to the advancement of the vehicle and of the action of the fan F, the latter remaining the only action when the vehicle does not move or moves in reverse gear .

[0050] Figure 9 schematically shows the general structure of the circuit C2 . The coolant does not undergo phase changes during normal operation, always remaining in the liquid phase . A second temperature sensor TS2 ( see also Figure 1 ) is configured to detect a temperature of the coolant TctnRadInat the inlet of the exchanger RAD, and preferably it is combined with a temperature sensor TS2B configured to detect a temperature of the coolant TcinRadOut at the outlet of the exchanger RAD . In the embodiment of the method according to the invention, the sensor TS2B is used for a closed-loop control associated with the calculation described in Figure 7 .

[0051] The mass flow rate o f coolant circulating in the radiator RAD - which is denoted herein by the references mcinRadin and mClnRadout ~ is divided into circuital branches in parallel with one another, which provide for the cooling of users such as one or more electric traction motors M of the vehicle , a battery set BT which supplies the one or more electric traction motors M of the vehicle , and a cabin heater CB_HT . Referring to Figure 10A, at the users BT and CB_HT there is moreover implemented - according to a fashion known per se - a direct heat exchange relation between the refrigerant fluid of the circuit Cl and the coolant of the circuit C2 . The thermal conditioning of the battery set ( or sets ) BT of the vehicle is accomplished by means of one or more corresponding chillers ( reference CHL in Figure 10A) , which operate by using the coolant of the second circuit C2 as a first thermal carrier, i . e . as the thermal carrier for the disposal of the heat produced by the battery set BT , and the refrigerant fluid of the first circuit Cl as a second thermal carrier , i . e . as the thermal carrier for the disposal of a heat flow absorbed by the coolant . Each chiller CHL is part both of the circuit Cl , in which it operates as a further evaporator in parallel to the evaporator EVAP, and of the circuit C2 , in which it operates as a further heat exchanger . The chiller CHL is therefore supplied with a mass flow rate of refrigerant fluid at the inlet ThR^rChinInand it discharges a mass flow rate of refrigerant fluid at the outlet mRfrchtiiout r wherein the mass flow rates mRfrChiiiin and mRfrChaiOutgenerally have a di f ferent phase ( the former has a liquid phase , the latter has a gaseous phase ) due to the operation as an evaporator, and it is moreover supplied with a mass flow rate of coolant at the inlet ThCinChiuIn, which is then disposed of as a mass flow rate of coolant at the outlet Thcinctuiiout t at a temperature lower than the mass flow rate of the coolant at the inlet ThCinChinIn. At an inlet CLN_IN of the coolant into the chiller CHL and at an outlet CLN_OUT of the coolant from the chiller CHL there are arranged, respectively, a third temperature sensor TS3 and a fourth temperature sensor TS4 , configured to detect the temperature , respectively, of the flow rates ThCinChiuInand ™ClnChillOut • With reference to Figure 11A, a similar interaction takes place at the evaporator EVAP : the latter is supplied with a mass flow rate of refrigerant fluid at the inlet riiRfrEvapInand disposes of a mass flow rate of refrigerant fluid at the outlet ThR^rEvapOut, wherein the flow rates mRfrEvapInand mRfrEvapOutgenerally have di f ferent phases ( the former having a liquid phase , the second having a gaseous phase ) due to the operation of the evaporator EVAP, and it is also impinged upon by a cabin air mass flow rate mAirCabinEvapIn, which f lows out as a cabin air mass flow rate mAirCabinEvapOuthaving a temperature lower than the cabin air mass flow rate '^-AtrCabtnEvapin and generally with a di f ferent amount of moisture . Astride the evaporator EVAP there are arranged, respectively, a fi fth temperature sensor TS 5 and a sixth temperature sensor TS 6 , configured to detect the temperature , respectively, of the flow rates ™AirCabinEvapIn and TTT-AirCabinEvapOut •

[0052] In order to determine the temperature of the air flow rate m ends Air downstream of traversing the condenser CNDS , it is necessary to determine a thermal power Qcnds rej ected by the condenser CNDS during the traversing by the flow rate riiCnds Airas a function of the flow rate of refrigerant fluid mRfrthrough the condenser CNDS ( it i s a flow rate which undergoes a phase change from gas to liquid) and a di f ference in enthalpy of the refrigerant fluid between the inlet ( enthalpy hRfr@Cnds In) and the outlet ( enthalpy denoted as hRfr@Cnds Out) of the condenser CNDS ( thus Qcnds ~ ™Rfr ' (J^Rfr&Cnds In ~ hRfr@Cnds_Out) ) • the calculation, reference is preferably made to values of speci fic enthalpy, expressed in [ kJ / kg] . The enthalpy values hRfr@Cnds Inand hRfr@Cnds Outare derived from the enthalpy diagrams characteristic of the refrigerant fluid employed, by using, as input data, the pressure and the temperature of the refrigerant fluid in the conditions of entering or leaving the condenser CNDS . At the outlet of the condenser CNDS , the pressure and the temperature of the refrigerant fluid are moreover measured by the sensors PS I and TS 1 , whereas for the conditions at the inlet the pressure and the temperature of the refrigerant fluid are determined based on the following .

[0053] The phase of transition to liquid of the refrigerant fluid, which takes place while traversing the condenser CNDS , may be considered as an isobaric trans formation, and therefore the pressure at the inlet of the condenser CNDS may be assumed as equal or substantially equal to the pressure at the outlet of the condenser CNDS , measured by the sensor PS I .

[0054] As regards the temperature o f the refrigerant fluid at the inlet of the condenser CNDS , it may be calculated by considering the compression of the refrigerant fluid in the gaseous phase by the compressor C as an adiabatic compression, which stars with the refrigerant fluid in the conditions at the outlet of the evaporator EVAP . In turn, this requires the calculation of the pressure and temperature conditions of the refrigerant fluid in the gaseous phase at the outlet of the evaporation devices , therefore of the cabin evaporator EVAP and of the one or more chillers CHL, according to the fashion already described with reference to the Figures 10A, 11A.

[0055] The temperature and the pressure of the refrigerant fluid remain constant or substantially constant during the evaporation stage through the evaporator EVAP . As described in the foregoing, temperature sensors are present at the inlets and at the outlets of the circuits C2 on the chiller CHL ( sensors TS3 and TS4 at the inlet CLN_IN and CLN_OUT ) and of the circuit of the cabin air on the evaporator EVAP ( sensors TS5 and TS 6 at the inlet AIR_IN and at the outlet AIR_OUT ) . There is a direct dependency between the flow rate of the coolant riicinchiii ( circuit C2 ) and the rotational speed ChillPSpeedof a circulation pump thereof on board the chiller CHL, as well as between the cabin air flow rate mAirCabinEvapwhich impinges upon the evaporator EVAP and the rotational speed of a cabin blower EvapBspeedassociated to the evaporator EVAP . Such relations are the obj ect of the diagrams mCinchiii - ChillPSpeedin Figure 10B and mAirCabinEvap- EvapBspeedin Figure 11B .

[0056] The cooling thermal power Qchiii trans ferred to the coolant in the chiller CHL and the cooling thermal power QcabinEvap trans ferred to the air which impinges upon the evaporator EVAP may be calculated according to the following equations ( for which it is moreover possible to use some calculation hypotheses which are described in the following and summari zed in a table )

[0057] Q Chill ~ rilcinChill ' <-p,Cln ' (TcinChillln ^CJnChiHOut)

[0058] QcabinEvap ™AirCabinEvap ' <-p,Air ' (T / iirCabinEvapln T / drEabinEvapOut) wherein :

[0059] - riicinchiii is the coolant flow rate through the chiller CHL ( inlet at CLN_IN, outlet at CLM_OUT ) ,

[0060] -cp,cin is the speci fic heat at constant pressure of the coolant ,

[0061] - TCinChinInis the temperature of the coolant at the inlet CLN_IN of the chiller CHL (measured via the sensor TS3 ) ,

[0062] - Tcinchtiiout is the temperature of the coolant at the outlet CLN_OUT of the chiller CHL (measured via the sensor TS4 ) ,

[0063] - ™AirCabinEvap is the cabin air flow rate which impinges upon the evaporator EVAP,

[0064] -cp,Air is the speci fic heat at constant pressure of the cabin air,

[0065] -TAirCabinEvapin is the temperature of the cabin air flow rate at the inlet of the evaporator EVAP,

[0066] -TAirCabinEvapOut is the temperature of the cabin air flow rate at the outlet of the evaporator EVAP .

[0067] The temperature of the refrigerant fluid in the chiller CHL is calculated based on the equation of the thermal power exchanged with the cabin air and with the coolant , respectively in the case of the evaporator EVAP and of the chiller CHL .

[0068] TRfr@Chi.ll ~ Tcinchimn— Qchill ' ^ThChill

[0069] TRfr@CabinEvap ~ T^irEai)inEvapin— QcabinEvap ' ^ThCabinEvap wherein :

[0070] - TRfr@chiu is the temperature of the refrigerant fluid traversing the chiller CHL,

[0071] - TctnChiiiInis the temperature of the coolant at the inlet CLN_IN of the chiller CHL (measured via the sensor TS3 ) ,

[0072] - RrhChiii isathermal resistance of the chiller CHL,

[0073] - TRfr@cabinEvap is the temperature of the refrigerant fluid traversing the evaporator EVAP,

[0074] RncabinEvap is a thermal resistance of the evaporator EVAP .

[0075] The correlation between the thermal resistance and the flow rate is known for the coolant of the circuit C2 and for the cabin air, and it is shown for the pair RrhChiii - mcmchiii in Figure 12A and for the pair RThCabinEVap - ^AirCabinEvap in Figure 12B .

[0076] As regards the refrigerant fluid, when it is in the vapour phase ( grey-coloured area in the pres sureenthalpy diagram PRef- hRef for the refrigerant fluid) the correlation between the temperature TRfr@Evapand the pressure PRfr@Evap is known, and it is shown in the diagram of Figure 13B which comprises , on the X-axis , the temperature of the refrigerant fluid in the vapour phase TRefrvap and, on the Y-axis , the pressure of the refrigerant fluid in the vapour phase pRefrVap •

[0077] When the chiller CHL and the evaporator EVAP are activated at the same time , the temperature and the pressure of the refrigerant fluid at the outlet of both components are substantially the same . In this case , the chiller CHL is considered as a reference for calculating TRfr@Evap and PRfr@Evap r since the temperature data relating to the coolant flow rate through the chiller CHL are more accurate than the data relating to the cabin air flow rate . In all other cases , therefore , when only one of the components EVAP and CHL is active ( or i f only one of them, e . g . EVAP, is present ) , the calculation is performed on the basis of the active component .

[0078] In the following a table summari zes calculation hypotheses ( and modes )

[0079] EVAP and ( one or TRfr@Evap ~ ^CJnChinZn Q Chill ' PThChill more ) CHL are active at the same time

[0080] Only ( one or more ) TRfr@Evap ~ ^CJnChinZn—Q Chill ' PThChill

[0081] CHL is active

[0082] Only EVAP is active TRfr@CabinEvap ~

[0083] TAirCa.binEva.pin~ QcabinEvap ' PThCabinEvapp

[0084] In the compression phase of the refrigerant fluid, the latter undergoes an adiabatic trans formation, and therefore it becomes possible to calculate the temperature at the outlet ( delivery) of the compressor C - which coincides with the temperature of the refrigerant fluid at the inlet of the condenser CNDS - by using the following equation : r-i

[0085] _ [ PRfr@Cnds\Y_ _

[0086] TRfr@CndsIn ~1Rfr@Evap I p I— 1Rfr@Evapr

[0087] \^Rfr@Evap / wherein :

[0088] - y is equal to the ratio between the speci fic heat at constant pressure cp,Rfrand the speci fic heat at constant volume cv R^rfor the refrigerant fluid (y =cV,Rfr cv,Rfr

[0089] - TRfr@CnaSInis the temperature of the refrigerant fluid at the outlet of the compressor C, i . e . at the inlet of the condenser CNDS ,

[0090] - TRfr@Evap is the temperature of the refrigerant fluid at the inlet ( intake ) of the compressor C, i . e . at the outlet of the evaporator EVAP,

[0091] - PRfr@cnds is the pressure of the refrigerant fluid within the condenser CNDS (which is constant or substantially constant , see the diagram in Figure 8 ) ,

[0092] - PRfr@Evap is the pressure of the refrigerant fluid within the evaporator EVAP (which is constant or substantially constant , see the diagram in Figure 8 ) ,

[0093] - CR is a compression ratio of the compressor C ( equal toPRfr@Cndsfi . e . to the ratio between the delivery

[0094] PRfr@Evap pressure and the intake pressure , with the evolutions in the condenser and in the evaporator ( s ) which are assumed as isobaric ) .

[0095] With the calculated value of the temperature TRfr@cndsin and with the value of the pressure PRfr@cnds measured by the sensor PS I , which represents both the pressure at the inlet of the condenser CNDS and the pressure at the outlet of the condenser CNDS , it is possible - by means of an enthalpy diagram characteristic of the refrigerant fluid - to extrapolate the enthalpy value hRefr@CndsInof the refrigerant fluid at the inlet of the condenser CNDS . The mass flow rate of the refrigerant fluid riiRfrthrough the condenser CNDS is calculated as the product of a rotational speed nCompof the compressor C ( expressed in turns per second) , of a density PRfr@Evap at the inlet of the compressor C, of a volumetric ef ficiency TfVoiof the compressor C and of a displacement Vcomp of the compressor C :

[0096] — (nComP\ . . . TZ

[0097] ™Rfr ~ y 6Q J ' PRfr@Evap ' Rvol ' '' Comp

[0098] The volumetric e f ficiency rjVoimay be extrapolated from the maps of the compressor C, speci fically from a map M60 shown in Figure 14 , which provides the value of volumetric ef ficiency TfVoias a function of the speedncomp ,aH being parametri zed as a function of the compression ratio CR ( inlet / outlet , see above ) of the compressor C . In Figure 14 there are shown four parametric curves , each being associated with a di f ferent compression ratio CR1 , CR2 , CR3 , CR4 ) . In other words , the data input into the map of Figure 14 are the speed ncomp for the input on the X-axis , and the compression ratio CR for the selection of the parametric curve from which the data item T]Voiis to be read on the Y-axis .

[0099] The density of the refrigerant fluid PRfr@Evap at the inlet of compressor C may be calculated according to the following equation ( ideal gas equation) :

[0100] _ Mpj'r ‘ PRfr@Evap

[0101] PRfr@Evap ~ ~^T

[0102] ^Rfr '1Rf'r&Evap wherein :

[0103] - ^Rfr i S the molar mass of the refrigerant fluid,

[0104] Rpfris a constant characteristic of the refrigerant fluid, - pFfris the pressure of the refrigerant fluid at the inlet of the compressor C.

[0105] The thermal power Qcnds rejected by the condenser CNDS upon being traversed by the air flow rate mAtris absorbed by the flow rate mAtritself, which is about to traverse the radiator RAD. The flow rate diAiris characterized by a temperature TAirCndsIn(equal to the ambient temperature) upstream of traversing the condenser CNDS and by a temperature TAirCndsOutdownstream of traversing the condenser CNDS itself. The power Qcnds may therefore be expressed alternatively (i.e. as an alternative to the expression referred to the refrigerant fluid) as:

[0106] Qcnds ~ ™Air ' Cp,Atr ' (TAirCndsOut ^AirCndsIn) wherein cpAiris the specific heat at constant pressure of the air, whereas the flow rate mAtris the total air flow rate impinging upon the condenser CNDS and the radiator RAD. Said flow rate is equal to the sum of the contribution riiAirAGSdue to the air flow rate modulation device AGS and of the contribution mAir FANdue to the fan F.

[0107] The calculation of the total air flow rate mAtris shown in Figure 15, diagram 70: both flow rates mAtr AGSand mAirFANmay be extrapolated from a respective map M70_AGS (flow rate mAir AGS) , M70_FAN (flow rate mAir FAN) , which show: a) on the X-axis, a passage area configuration AGSOpeningof the device AGS for the map M70_AGS, and on the Y-axis the flow rate mAtr AGS; by way of example, the map M70 contains four curves mAirAGS— AGSOpeningwhich are parametrized as a function of the advancement speed of the vehicle Vehicle_Speed, and specifically corresponding to values of advancement speed of the vehicle VS1, VS2, VS3 , VS4 with VS 1 > VS2 > VS3 > VS4 . In other words , the data input into the map M70_AGS are the passage area configuration AGSOpentng for the inlet on the X-axis , and the advancement speed of the vehicle VS 1 , VS2 , VS3 , VS4 for the selection of the parametric curve wherefrom the data item mAir AGSon the Y-axis is to be read; b ) on the X-axis , a rotational speed FANSpdof the fan F for the map M70_FAN, and on the Y-axis the flow rate mAir FAN the map M70_FAN contains , by way of example , four curves riiAir FAN- FANSpdparametri zed as a function of the advancement speed of the vehicle Vehicle_Speed , and speci fically corresponding to values of advancement speed of the vehicle VS 1 , VS2 , VS3 , VS4 with VS 1 > VS2 > VS3 > VS4 . In other words , the data input into the map M70_FAN are the rotational speed FANSpdfor the input on the X-axis , and the advancement speed of the vehicle VS 1 , VS2 , VS3 , VS4 for the selection of the parametric curve from which the data item mAtr FANon the Y-axis is to be read .

[0108] The total value of air flow rate mAtris therefore determined as a sum, block 72 , riiAir AGS+ mAir FAN, whereinr^Air_AGS and ritAir FANaredetermined by the maps M70_AGS and M70_FAN as described in the foregoing .

[0109] Once the thermal power QGndsis known by extraction of the speci fic enthalpy values at the inlet and at the outlet of the condenser CNDS hRfrCndsInand hRfrCndsOut- after the complete determination of the pressure and temperature conditions PRfr@cndsin>TRfr@cndsin at the inlet of the condenser by means of the calculation described in the foregoing, and of the pressure and temperature conditions at the outlet of the condenser CNDS by means of the reading of the sensors PS I and TS 1 - it is possible to determine , by inverting the equation for calculating Qcnds provided in the foregoing, the temperature TCnds Air Outof the air flow rate mAir downstream of traversing the condenser CNDS as a sum of the temperature Tcnds_Air_in of the air upstream of traversing the condenser CNDS and a ratio between the thermal power E and a product between the air flow rate mAirand the speci fic heat at constant pressure of the air cp Air. Moreover, the temperatureTcnds_Air_out corresponds to the temperature TRad Air Inused in the determinations as per block 4 , as can be seen in the diagram of Figure 3 , wherein it is possible to observe the supply

[0110] , Q Cnds

[0111] Tends Air Out ‘ Cnds Air In mAir ‘ Cp / Air

[0112] In this expression, the term TCnds Air Inis a boundary condition ( it is the ambient temperature ) , cp Airis a constant , depends on the characteristics of the device AGS and of the fan F and on the speed of the vehicle , and therefore is not a control variable as regards the thermal management of the system, whereas the temperature TCnds Air Outis strictly connected to the thermal power Qcnds rej ected by the condenser CNDS , i . e . to the performances and to the operation of the condenser itsel f and generally of the circuit Cl . The rej ected thermal power QcndsmaY therefore be subj ected to a calibration, in order to minimize the consumption of electric power in the circuit Cl , primarily the consumption of electric power by the compressor C . The calibration may conveniently be operated by means of the definition of a target pressure PRfr@cndsTgt of the refrigerant fluid in the condenser ( the pressure PRfr@cndsTgt is assumed as constant in the evolution through the condenser, as per the pressure-enthalpy diagram in Figure 8 ) , which corresponds to a global consumption of electric power in the circuit Cl , considering the contributions of the device AGS and of the fan F . Increasing the pressure PRfr@cnds of the refrigerant fluid in the condenser raises the consumption of electric power by the compressor C, but at the same time it reduces the consumption of electric power by the device AGS and the fan F, since it increases the temperature di f ference of the refrigerant fluid with respect to the external air, and therefore increases the power Qcnds with equal air flow rate rii-Air r and consequently with the same power Qcnds a lesser air flow rate is necessary ( therefore , the device AGS is less open, the vehicle is more ef f icient from the aerodynamic point of view and less electric power is consumed for traction; moreover, the fan F rotates with a lower number of turns . Experimentally, it is possible to find a target value of the pressure in the refrigerant fluid PRfr@cndsTgta s acompromise between the consumption of electric power by the compressor C and the absorption of electric power by the vehicle ( for the device AGS ) and by the fan F . Said target value of the pressure in the refrigerant fluid PRfr@cndsTgt corresponds to a target value of cooling power Qcig_Tgt which shall be expressed by the evaporation devices which are active , i . e . by the evaporator EVAP and / or by the one or more chillers CHL .

[0113] In the calibration of the value PRfr@cndsTgt it is necessary to take into account the variables of the external temperature Tamb= TCnds Air Inand of the advancement speed of the vehicle VehicleSpeed . Again experimentally, it may be observed that there is a linear relationship between the target pressure PRfr@cndsTgt and the target power Qcig Tgt , wherein the angular coef ficient a and the known term b ( of fset ) of the set of parallel straight lines which connects a raw (unfiltered) value PRfr@cndsTgtRaw o f the target pressure PRfr@cndsTgtRawand the target power Qcig Tgt according to the equation PRfr@CndsTgtRaw ' Qcig_Tgt + depend on the external temperature Tamband on the vehicle speed VehicleSpeed as shown in Figure 16 , diagram 80 .

[0114] In this diagram it is possible to see a map M81 , which is used to determine the value of the angular coef ficient a, and a map M82 which is used to determine the value of the known term b . Each map uses , as input data, pairs of values VehicleSpeed e Tamb, wherein VehicleSpeed is the variable on the X-axis in each map, whereas Tambis the variable with respect to which the curves mapping the angular coef ficient a and the known term b are parametri zed . Each of the maps M81 , M82 shows , by way of example , a set of four curves , each being parametri zed with respect to a corresponding temperature value Tambl> Tamb2, Tamb3, Tamb4 with Tambl > Tamb2 > Tamb3 > Tamb4 . The value of the angular coef ficient a determined by means of the map M81 is supplied to a multiplier 83 , which also receives the target value of cooling power for the one or more evaporation devices Qcig Tgtr and the output of the multiplier 83 ( Qcig_Tgt ') is input into an adder 84 , which also receives the value of the known term b determined by means of the map M82 . The result of the adder 84 { a ■ QcigTgt+ b ) corresponds to the raw value PRfr@cndsTgtRaw r which is then subj ected to filtering via a variation rate l imiter block 85 . The limitation of the variation rate is performed in such a way as to avoid damaging the compressor C due to excessively rapid variations or oscillations of the target pressure value of the refrigerant fluid in the condenser CNDS . The output of block 85 corresponds to a filtered target value of the pressure within the condenser, denoted with a reference PRfr@cndsTgtFit r and it does not correspond yet to the target value PRfr@cndsTgt since a further upper limitation is required (block 86 , MIN) to a limit value PRfr@cnd.sLim of pressure of the refrigerant fluid within the condenser, as admitted in the design stage . The output of the block 86 , therefore , corresponds to the target value PRfr@cndsTgt • Once the pressure PRfr@cndsTgt is known, it is possible to determine the corresponding target temperature of the refrigerant fluid at the outlet of the condenser, which is denoted with the reference PRfr@cndsOutTgt • this is shown in the following Figure 17 , diagram 90 .

[0115] The temperature TRfr@CndsOutTgtrepresents the temperature at the end of the condensation phase , and it may be expressed as a di f ference between a target temperature TRfr@CndsTgtof the refrigerant fluid in saturation conditions ( therefore , within the limits of the curve of saturated vapour ) and a target di f ference of under-cooling temperature &TRfr@CndsSubCigTgt( therefore PRfr@CndsOutTgt ~ PRfr@CndsTgt ~ ^PRfr@CndsSubClgTgt ^ r wherein both values TRfr@CndsTgtand ^TRfr&CndsSubCigTgtare extrapolated from respective maps M92 , M94 , wherein the map M92 provides the value of the temperature TRfr@CndsTgtas a function of the pressure PRfr@cnds of the refrigerant fluid in the condenser CNDS , while the map M94 provides the value of the temperature di f ference &TRfr@CndsSubCigTgtas a function of the pressure PRfr@cnds of the refrigerant fluid in the condenser CNDS . The values TRfr@CndsTgtand ^TRfr@cndsSubcigTgt are input into a subtraction block 96 , the output whereof is , due to what has been described in the foregoing, the value TR^r@CndsOutTgt. From the two values PRfr@cndsTgt and TRfr@CndsOutTgtit is possible to calculate the target enthalpy value hR^r@CndsOutTgtat the outlet of the condenser CNDS , and hence the value of the target thermal power which shall be rej ected by the condenser Qcnds_Tgt according to the relationship wherein :

[0116] - hRfr@cndsin is the enthalpy of the refrigerant fluid at the inlet of the condenser CNDS ,

[0117] -hRfr@cndsOutTgt is the enthalpy of the refrigerant fluid at the outlet of the condenser CNDS in the presence of a condensation pressure equal to PRfr@cndsTgt and of a temperature TR^r@CndsOutTgtat the outlet of the condenser CNDS .

[0118] In other words , due to what has been described in the foregoing, the following applies :

[0119] Substantially, considering the target cooling thermal power Qcig Tgt at the one or more evaporation devices EVAP and / or CHL, on the basis whereof there is defined an optimal value of high pressure at the inlet of the condenser PRfr@cndsTgt r as described with reference to Figure 16 , it is possible to determine the value Qcnds_Tgt ° f the thermal power to be disposed of by the condenser CNDS , which also incorporates the part of further power due to the work increase of the compressor C .

[0120] Once the target thermal power Qcnds Tgt is known which is to be rej ected by the condenser CNDS , it is then possible to calculate the target value mCnds Air Tgtof the air flow rate which shall flow through the condenser CNDS . The calculation of the air flow rate riicnds_Air_Tgt comprises the algebraic sum of a target value mCnds Air Tg t 0Ldetermined by open-loop calculation and of a target value '^lcnds_Atr_Tgt_CL determined by closed-loop calculation . This is the obj ect of the following Figures 18 ( open loop ) and 19 ( closed loop ) .

[0121] As regards the determination of the value '^lcnds_Atr Tgt_OL / diagram 100 in Figure 18 , it is operated on the basis of a map M102 which provides the value ™cnds Air Tgt OL by using, as input data, the ratio

[0122] (block 104 ) between the target thermal power

[0123] TRfr@ CndsIn~T amb

[0124] Qcnds_Tgt to be rej ected by the condenser CNDS and the di f ference (block 102 ) between the temperature of the refrigerant fluid at the inlet of the condenser TRfr@CndsIn

[0125] ( equal to TRrr@Evav(Rfr@CndsTst\7j and the ambient

[0126] 7 K\pRfr@>Evap / temperature Tamb. The curves on the map M102 are parametri zed as a function of the value 'rhRfrof the refrigerant fluid flow rate through the condenser CNDS . By way of exemplary and qualitative example , the map 102 shows four curves parametri zed for respective values of the flow rate mRfrl, mR?r2, mRfr3, mRfr4 with mRfrl < mRfr2 < mRfr3 < mRfr4. Therefore , the value mCnds Air Tgt 0Lincreases as the flow rate 'rhRfrdecreases and as the , . Qcnds Tat ratio - - - increases . pRfr@ CndsIn~T amb

[0127] Referring to Figure 19 , diagram 110 , the target value determined by closed-loop calculation mCnds Air Tgt CLis determined by means of a proportional-integral control 111 as a function of a di f ference (block 112 ) between a current value PRfr@cnds of the pressure of the refrigerant fluid within the condenser and the target pressure value PRfr@cndsTgt r wherein the proportionalintegral control 111 has an upper saturation limit 113 equal to a di f ference 114 between the maximum value Air Max of the air flow rate traversing the condenser ( CNDS ) and the radiator (RAD) and the target value determined by open-loop calculation ( riiCnds Air Tgt 0L) i and a lower saturation limit 115 equal to the null value (block 116 ) . Moreover, it is possible to observe that the set of the Figures 8 to 19 corresponds to an extended representation of the block 6 of the Figures 2 , 3 and of the block 8 of Figure 2 .

[0128] With reference to Figure 20 , diagram 120 ( corresponding to the block 10 of the Figures 2 , 3 ) once the target values of the air flow rates FdRad Airjgtand ™cr.<is_Air Tgtareknown, being calculated as described in the foregoing, it is then possible to calculate the target value mAir Tgtof the air flow rate traversing the condenser CNDS and the radiator RAD, which is determined as the lower (block 122 , "MIN" ) between the maximum value Air Max and the higher (block 124 , "MAX" ) between the values of the flow rates mRad Air Tgtand mCnds Air Tgt. The function of the maximum operator at block 124 is to select the flow rate value which can tackle with the more burdensome request between the condenser CNDS and the radiator RAD, which therefore is satis fying also with respect to the less burdensome request .

[0129] Thanks to the calculation of the target value mAir Tgtit is finally possible to determine the target passage area configuration AGSOpening Tgtfor the device AGS and the target value FANSpd Tgtof the rotational speed of the cooling fan F, in such a way as to control the one or the other as a function thereof .

[0130] Referring to Figure 21 , diagram 130 ( corresponding to the block 12 of Figures 2 , 3 ) , the target passage area configuration AGSOpening Tgtfor the device AGS is determined by using a map M132 which outputs a target passage area configuration AGSOpening ctgfor cooling purposes by using, as input data, the target value hiAir Tgt(which is the variable on the X-axis ) and the advancement speed of the vehicle Vehicle_Speed , which is the variable with respect to which the curves are drawn by way of example in the map M132 . Speci fically, the curves on the map M132 correspond to values of advancement speed Vehicle_Speed = VS1, VS2, VS3, VS4 with VS1 < VS2 < VS3 < VS4. From a qualitative point of view, the target passage area configuration AGSOpening ctg( substantially an opening degree of the device AGS ) increases as riiAir Tgtincreases and as Vehicle_Speed decreases . The target passage area configuration AGSOpening ctgdetermined by means of the map M132 is input into a maximum operator 134 which extracts the highest value between AGSOpening ctgand two further target passage area configurations ( again, two opening degrees of the device AGS ) AGSOpening Antistkand AGSOpening AntiAgingderived from methods aiming at avoiding the sticking or j amming of the device AGS , especially in conditions of high-speed driving (AGSOpening Antistk- an example is described in the Patent Application no . 102024000008917 in the name of the same Applicant ) and at avoiding an early aging of the device AGS , especially during low-speed manoeuvres (AGSOpening AntiAging- an example is described in the Patent Application no . 102024000008914 in the name of the same Applicant ) . In this way, as well as in other instances , there is the certainty to select the target configuration which meets the most burdensome needs . Alternatively, the values AGSOpeningAntiStk and AGSOpenlng AntiAgingmay be derived from characteristic maps of the device AGS , i . e . they may be determined simply as a function of variables input into the same maps .

[0131] Referring to Figure 22 , diagram 140 , a target air flow rate mAir FAN Tgtfor the fan F ( and consequently, Figure 23 , the target rotational speed of the fan F FANSpd Tgt( Figures 22 and 23 together represent the block 14 in Figures 2 , 3 ) is determined with respect to a reference condition which corresponds to having a passage area configuration of the device AGS which is equal to the maximum available passage area ( full opening) .

[0132] This is due essentially to the fact that the intervention of the fan F is required i f an air flow rate riiAir_AGS_open naturally generated by the advancement of the vehicle , with the device AGS in the maximum opening configuration, is not suf ficient to meet the target air flow rate ThAir Tgt. Operatively, this envisages calculating the target air flow rate mAir FAN Tgtfor the fan F by means of a di f ference (block 142 ) between the target air flow rate mAir Tgtand the flow rate mAir AGS Openin the conditions of maximum passage area of the device AGS , determined by means of a map M144 which employs the speed of the vehicle Vehicle_Speed as an input data item for determining ThAir AGS Open. From a qualitative point of view, the air flow rate mAir AGS Openincreases as the speed of the vehicle Vehicle_Speed increases .

[0133] With reference to Figure 23 , diagram 150 , the target rotational speed of the fan F FANSpd Tgtis determined by using a map M152 which outputs a value of the rotational speed FANSpd Cigof the fan F for cooling purposes , by using as input data the target value mAir FAN Tgtdetermined as described for Figure 22 (which is the variable on the X-axis ) and the advancement speed of the vehicle Vehicle_Speed , which is the variable with respect to which the curves shown by way of example in the map M152 are drawn . Speci fically, the curves on the map M152 correspond to values of advancement speed Vehicle_Speed = VS1, VS2, VS3, VS4 with VS1 < VS2 < VS3 < VS4. From a qualitative point of view, the target rotational speed FANSpd Tgtof the fan F increases as riiAir Tgtincreases and as Vehicle_Speed decreases . The target rotational speed F ANspd Tgt of the fan F, determined by means of the map M152 , is input into a maximum operator 154 , which extracts the higher value between the rotational speed F ANSpd_ Cig of the fan F and a minimum value of rotational speed FANSpd Min of the fan F, derived from a parallel method which aims at reducing the noise emissions (NVH) of the fan F . In this fashion, the value of the rotational speed FANSpd Tgtdownstream of the calculation has anyway a lower limit at the value FANSpd Min, below which the temperatures of the whole system would become critical . The output of the block 154 is then fed to the input of a further block 156 , which extracts the minimum value (MIN) between the value output from block 154 (which is the greater between FANSpd Cigand FANSpd Min) and a maximum value of rotational speed FANSpd Maxof the fan F, which corresponds to a maximum value of rotational speed tolerable with a view of limiting the noise emissions of the fan F . In other words , the value F ANSpd Tgthas an upper limit at the maximum value FANSpd Max. An example of a method for determining the values FANSpd Minand FANSpd Maxis described in the Patent Application no . 102024000008902 in the name of the same Applicant . Alternatively, the speeds FANSpd Minand FANSpd Maxmay be extrapolated from a map adapted to the characteristics of the fan F and of the heat exchange units of the vehicle .

[0134] Then, by updating the calculation of the frequency envisaged by an electronic control unit which manages the method according to the invention and which controls the actuators in the circuits Cl and C2 , the device AGS and the fan F are driven based on the respective targets AGSOpening Tgte FANSpd Tgt, thereby enabling managing the cooling of both circuits Cl , C2 dynamically and with a low consumption of electric power . Moreover, it shall be kept in mind that the method described herein does not necessarily require the arrangement of the fan F downstream of the radiator RAD, but can be applied also in the presence of a fan F upstream of the thermal exchange devices CNDS and RAD, immediately downstream of the device AGS .

[0135] Of course , the implementation details and the embodiments may amply vary with respect to what has been described and illustrated, without departing from the extent of the present invention, as defined by the annexed claims .

Claims

CLAIMS1. A method for the combined management of a cooling air flow rate modulation system (AGS) and a cooling fan (F) of one or more heat exchange units (CNDS, RAD) of a vehicle with an electric powertrain, wherein the vehicle comprises :- a first refrigerant cycle circuit (Cl) through which a refrigerant fluid flows, the first circuit comprising a first heat exchange unit including a condenser (CNDS) , and further includes at least one evaporator (EVAP, CHL) , and a compressor (C) ,- a second cooling circuit (C2) through which a coolant flows, the second circuit (C2) comprising a second heat exchange unit including a radiator (RAD) for the coolant,- an air flow rate modulation device (AGS) arranged upstream of the condenser (CNDS) , the air flow rate modulation device (AGS) having a variable passage area configuration that results in a first cooling air flow rate (mAir AGs') varying from a minimum or zero value to a respective maximum value,- a cooling fan (F) arranged downstream of the modulation device (AGS) and configured to generate a second cooling air flow rate (^tiirjuiN) through the condenser (CNDS) and the radiator (RAD) , wherein the condenser (CNDS) of the first circuit (Cl) is installed on the vehicle in front of the radiator (RAD) of the second circuit (C2) in a flow direction of a total air flow rate ('riiAir') fed through the condenser (CNDS) and the radiator (RAD) , the method including:- defining (2) a maximum value (fiiAtr Max') °f the total air flow rate traversing the condenser (CNDS) and the radiator (RAD) as a function of a vehicle advancement speed ( Vehicle_Speed) and a maximum rotational speed( FANSpd MAX) of the cooling fan (F) ,- defining (4) a first target value {hiRad_Air_Tgt') of an air flow rate {mRad Air) traversing the radiator (RAD) and in heat exchange relation with the coolant flowing therethrough as a function of a target value CrRadj:int_out_Tgt') of the temperature of the coolant leaving the radiator (RAD) ,- defining (6, 8) a second target value (rii-cnds Air rgit of an air flow rate ( riiCnds Air) traversing the condenser (CNDS) and in heat exchange relation with the refrigerant fluid flowing therethrough as a function of a target value (PRfr@cndsTgt') of pressure of the refrigerant fluid flowing through the condenser (CNDS) ,- determining (10) a target value {riiAir Tgt') of the total air flow rate (^biir) traversing the condenser (CNDS) and the radiator (RAD) as a function of the first target value {hT-Rad Air rgtj t the second target value (™cnds_Air_Tgt') r and also as a function of said maximum value ( ?it4ir_Max ) °f the total air flow rate (fibur) ,- defining (12) a target passage area configuration {AGSOpening Tgt) of the cooling air flow rate modulation device (AGS) as a function of said target value ('fhAir Tgt') of the total air flow rate trii-Air') / and as a function of the advancement speed of the vehicle {Vehicle _Speed) ,- defining (14) a target value {FANSpd Tgt) for the rotational speed of the cooling fan (F) as a function of said target value {riiAir Tgt) of the total air flow rate (m^ir) , as a function of the advancement speed of the vehicle ( Vehicle_Speed) , and as a function of a minimum value {FANSpd Min) and a maximum value {FANSpd Max) of the rotational speed of the cooling fan (F) ,- operating the cooling air flow rate modulation device (AGS) and the cooling fan (F) in accordance with the target pass-through area configuration {AGSOpening Tgt) and the target value {FANSpd Tgt) of the rotational speedof the cooling fan (F) , respectively.

2. The method of claim 1, wherein said determining the total value of the air flow rate ('rii-Air') traversing the condenser (CNDS) and the heat exchanger (RAD) includes limiting said total value ('fhAir') to the maximum value (')TT-Air_Max') of the air flow rate traversing the condenser (CNDS) and the radiator (RAD) .

3. The method according to any of the above claims, wherein said defining (4) the first target value (^RadMrTgt') of the flow rate (mRad Air) through the radiator (RAD) and in heat exchange relation with the coolant flowing therethrough includes defining said first target value (i’hRad_Air_Tgt') as the sum of a value determined by open-loop calculation (mRad Air Tgt 0L) and a value determined by closed-loop calculation mRad Air Tgt CL l •4. The method of claim 3, wherein said value determined by open-loop calculation (rii-Rad Air Tgt OL ) is determined as a function of:- a target value ('^Rad_cint_Tgt ) of the coolant flow rate entering the radiator (RAD) ,- a ratio QRad cint / (j^Rad cint in ~ ^Rad Air in) i wherein QRad_cint is a thermal power that the radiator shall dispose of to meet the target temperature value of the coolant (TRad_cint_outTgt') leaving said radiator (RAD) , TRad Cint Inis a temperature of the coolant entering the radiator (RAD) , and TRad Air Inis a temperature of an air flow rate at the radiator intake (RAD) .

5. The method of claim 3 or claim 4, wherein said value determined by closed-loop calculation (™Rad_Air_Tgt_CL ) is determined by means of a proportionalintegral control (51) as a function of a difference (52) between a current value (TRad ctnt Out) of the temperature of the coolant leaving the radiator (RAD) and the target temperature value (TRad Cint Out Tgt') of the coolant leavingthe radiator (RAD) , said proportional-integral control (51) having an upper saturation limit (53) equal to a difference (54) between the said maximum value (mAir Max') of the total air flow rate traversing the condenser (CNDS) and the radiator (RAD) and said value determined by open loop calculation (mRad Air Tfjt 0L) i and a lower saturation limit (55) equal to a zero value (56) .

6. The method of any of the above claims, wherein said defining (6, 8) a second target value (mCnds Air Tfjt) of the air flow rate (riicnds_Air') traversing the condenser (CNDS) and in heat exchange relation with the refrigerant fluid flowing through the condenser as a function of a target value (PRfr@cnd.sTgt') of the pressure of the refrigerant fluid flowing through the condenser (CNDS) includes : determining a temperature of the refrigerant fluid at the inlet (TRfr@CndsIn) of the condenser (CNDS) as a function of said target pressure value (PRfr@cndsTgt') of the refrigerant fluid, and determining a target temperature of the refrigerant fluid at the outlet (PRfr@cndsOutTgt') of the condenser (CNDS) as a function of said target pressure value (PRfr@cndsTgt') of the refrigerant fluid, determining a target thermal power (Qcnds_Tgt') rejected by said condenser (CNDS) upon being traversed by said second target value (riicnds_Air_Tgt') of the air flow rate as a function of a flow rate (mRyr) of that refrigerant fluid through the condenser (CNDS) and a difference in enthalpy of said refrigerant fluid between the outlet (hRfr@CndsOut) and the inlet (hRfr@CndsIn) of said condenser (CNDS) determined as a function of said temperature of the refrigerant fluid at the inlet (PRfr@cndsin') of the condenser (CNDS) , target temperature of the refrigerant at the outlet (TRfr@CndsOutTgt') of the condenser (CNDS) , and of said target pressure value(PRfr@cndsTgt'> of the refrigerant fluid,- determining said second target value (mCnds Air Tgt) of the air flow rate (ritCnds Air) traversing the condenser (CNDS) as a function of the target thermal power (Qcndsjrgt) rejected by the condenser (CNDS) .

7. The method of claim 6, including determining a temperature ( TCnds Air Out) of the air flow rate (mCnds Air) downstream of traversing said condenser (CNDS) as a function of said target thermal power (Qcndsjrgt) rejected by said condenser (CNDS) , said temperature ( TCnds Air Out) of the air flow rate (mends Air) downstream of traversing said condenser (CNDS) corresponding to said temperature PRad_Air_in ofanair flow rate at the radiator (RAD) intake.

8. The method of claim 6 or claim 7, wherein the target pressure value (PRfr@cndsTgt) of the refrigerant fluid is determined by:- definition of a raw value (PRfr@cndsTgtRaw ) of said target pressure value (PRfr@cndsTgt) of the refrigerant fluid according to the relationshipPRfr@CndsTgtRaw ' QcigTgt+ wherein- PRfr@cndsTgtRaw is the raw value of said target pressure value (PRfr@cndsTgt) of the refrigerant fluid- Qcig Tgt isatarget value of cooling thermal power for said at least one evaporator (EVAP, CHL) ,- a and b are coefficients variable as a function of a vehicle advancement speed ( Vehicle_Speed) and an ambient temperature (Tamb) , definition of a filtered target value (PRfr@cndsTgtFit) of said raw value by limiting a rate of time variation (85) of said filtered target value ( PRfr@CndsTgtFlt ) r definition of said pressure target value(PRfr@cndsTgt') of the refrigerant fluid as the lesser of the filtered target value (PRfr@cndsTgtFit') and a limit pressure value (PRfr@cndsLim') of the refrigerant fluid.

9. The method of any of claims 6 to 8, wherein said defining (4) first target value (riiRad_Air_Tgt') of the flow rate through the radiator (RAD) and in heat exchange relation with the coolant flowing therethrough includes defining said first target value (riiRad_Air_Tgt') as the sum of a value determined by open-loop calculation ('l^lRad_Atr_Tgt_OL') and a value determined by closed-loop calculation (mRad Air Tgt CL) , wherein said value determined by open-loop calculation (riiRad_Air_Tgt_OL ) is determined as a function of :- a ratio Qcnds Tgt / (j^Rfr@Cnds In ' ~ ?Amb ), wherein Qcnds_Tgt is said target thermal power rejected by said condenser (CNDS) , TRfr@Cnds Inis a temperature of the refrigerant fluid entering the condenser (CNDS) , and TAmbis the ambient temperature,- the flow rate (mRyr) of refrigerant fluid flowing through the condenser (CNDS) .

10. The method of claim 9, wherein said value determined by closed-loop calculation (mCnds Air Tgt CL) is determined by means of a proportional-integral control (111) as a function of a difference (112) between a current pressure value (PRfr@cnds') of the refrigerant fluid in the condenser (CNDS) and the target pressure value (PRfr@cnd.sTgt') of the refrigerant fluid in the condenser (CNDS) , the proportional-integral control (111) having an upper saturation limit (113) equal to a difference (114) between the maximum value (mAir Max') of the total air flow rate traversing the condenser (CNDS) and the radiator (RAD) and the value determined by openloop calculation (riicnds_Air_Tgt_OL ) i andalower saturation limit (115) equal to a zero value (116) .

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