A method for managing a thermal conditioning circuit of a vehicle cabin comprising a cabin heater with heat recovery from a cooling circuit of one or more traction components of an electric powertrain of the vehicle

Abstract

There is described a method for managing a thermal conditioning circuit, particularly a combined circuit for heating (CAB) a passenger compartment of a vehicle with an electric powertrain, and for cooling one or more traction components (TRC) of the electric powertrain of the vehicle. Thanks to the method according to the invention it is possible to recover the thermal energy dissipated in cooling the one or more traction components, thus limiting the expense of electrical energy consumed for heating the passenger compartment, resulting in the availability of more energy in the highvoltage battery for supplying the one or more electric traction motors of the vehicle. In this fashion, it becomes possible to improve the energetic efficiency of the vehicle, thereby obtaining benefits as regards the driving range thereof.

Description

[0001] "A method for managing a thermal conditioning circuit of a vehicle cabin comprising a cabin heater with heat recovery from a cooling circuit of one or more traction components of an electric powertrain of the vehicle"

[0002] TEXT OF THE DESCRIPTION

[0003] Field of the Invention

[0004] The present invention refers to thermal conditioning circuits, specifically to circuits employing a heat transfer liquid. The invention was developed with particular reference to a thermal conditioning circuit employing a heat transfer liquid, which operates in a heat exchange relationship with a passenger compartment, and to the possibility of improving the energy efficiency thereof.

[0005] Known Art

[0006] The vehicles with an electric powertrain, particularly BEVs, require a thermal conditioning system of the traction components (as well as a thermal conditioning system of a high-voltage battery supplying the electric motors) in addition to the traditional thermal conditioning system of the passenger compartment of the vehicle. The phrase "traction components" generally denotes each electric traction motor of the vehicle, and possibly the corresponding transmission which connects the motor to the one or more drive wheels operatively connected thereto.

[0007] As regards cooling the traction components, this is achieved by means of heat exchange between a heat transfer liquid, which circulates in a circuit in a heat exchange relationship with the same traction components, and which includes a radiator for dissipating the heat transferred from the traction components to the heat transfer liquid.

[0008] The functions of cooling and heating the passenger compartment are performed, respectively, by means of the interaction with a refrigeration cycle cooling circuit traversed by a coolant, the latter undergoing phase changes from liquid to gas and from gas to liquid (for cooling), and by means of a direct heat exchange between the heat transfer liquid and the cabin (for heating).

[0009] A known configuration of a circuit for cabin heating comprises providing an electric heater (so-called "ECH" - Electrical Coolant Heater) upstream of the cabin heater, arranged downstream of a cabin evaporator and impinged upon by a flow of air coming from the same cabin evaporator, in an amount variable as a function of the position of a mixing shutter. The electric heater is activated in order to rapidly raise the temperature of the heat transfer liquid traversing the heating circuit, so as to reach the thermal comfort targets in the cabin as rapidly as possible.

[0010] From the previous considerations, a twofold technical problem immediately becomes clear which is inherent in the operational modes described in the foregoing: thermal energy is dissipated at the radiator, which decreases the temperature of the heat transfer liquid used for cooling the traction components, while electric energy is consumed for heating the heat transfer liquid which enters the cabin heater. If, on one hand, it may appear obvious to recover the heat dissipated at the radiator in order to heat the heat transfer liquid entering the cabin heater, on the other hand such an operation is all but feasible a priori. Indeed, operational limits are present both as regards the flow rate of the heat transfer liquid which may be employed for recovering heat, and as regards energy efficiency, which make the solution not immediately feasible.

[0011] Object of the Invention

[0012] The invention aims at solving the technical problems outlined in the foregoing. Specifically, the object of the invention consists in providing a method for managing a thermal conditioning circuit of a vehicle cabin comprising a cabin heater with heat recovery from a cooling circuit of traction components of an electric powertrain of the vehicle, wherein the heat recovery is performed in advantageous conditions as regards energy efficiency and operation.

[0013] Summary of the Invention

[0014] The object 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.

[0015] Brief Description of the Figures

[0016] The invention will now be described with reference to the annexed Figures, which are provided by way of non-limiting example only and wherein:

[0017] - Figure 1 shows a thermal conditioning circuit for which the method according to the invention can be implemented,

[0018] - Figure 2 shows a flow diagram exemplifying the method according to the invention, and

[0019] Figures 3 to 7 respectively show diagrams exemplifying determinations operated in the execution of the method according to the invention.

[0020] Detailed Description

[0021] Reference C in Figure 1 generally denotes a thermal conditioning circuit, particularly a combined circuit for heating a passenger compartment of a vehicle with an electric powertrain and for cooling one or more traction components of the electric powertrain of the vehicle, which is used as an example for the description of the implementation of the method according to the invention.

[0022] The circuit C comprises: at least one traction component TRC of the powertrain, which is traversed by a first flow rate of heat transfer liquid mTrcin a first flow direction Fl, wherein the at least one traction component comprises - alternatively or in combination, depending on whether they interact with the flow rate mTrc- an electric traction motor, an inverter operatively connected to the electric traction motor, a transmission connecting an electric traction motor to one or more corresponding drive wheels of the vehicle, thereby meaning that the components under consideration comprise a cooling jacket traversed by the heat transfer liquid of the circuit C, or they comprise an operating fluid - for example an oil for the transmission - which is brought into a heat exchange relationship with the flow rate mTrcby means of a heat exchanger which is traversed, (only) in a heat exchange relationship, by the flow rate mTrcor by a fraction thereof, as a function of the ramification of the circuit and of the flow rate of operating fluid;

[0023] - a first circulation pump TP having a delivery port arranged upstream of the at least one traction component TRC with respect to the first flow direction Fl of the heat transfer liquid. The first circulation pump TP supplies the first flow rate mTrcto the at least one traction component TRC;

[0024] - a first recirculation branch R1 connecting an outlet of the at least one traction component TRC with a suction port of the first circulation pump TP, wherein a first heat exchange device RAD is arranged along the first recirculation branch R1. The recirculation branch R1 and the first heat exchange device RAD are traversed by a first recirculation flow rate mRad;

[0025] - a second heat exchange device CAB traversed by a second flow rate mCabof heat transfer liquid in a second flow direction F2,

[0026] - an electric heater ECH arranged upstream of the second heat exchange device CAB with respect to the second flow direction F2 of the heat transfer liquid,

[0027] - a second circulation pump CP having a delivery port arranged upstream of the electric heater ECH with respect to the second flow direction F2 of said heat transfer liquid. The second circulation pump CP supplies the second flow rate mCabto the electric heater ECH and to the second heat exchange device CAB,

[0028] - a second recirculation branch R2 connecting an outlet of the second heat exchange device CAB with a suction port of the second circulation pump CPI, the second recirculation branch being traversed by a second recirculation flow rate, in particular corresponding to the second flow rate mCab,

[0029] - a first branch Bl configured for the transit of a spill flow rate 'rhspiit from the first recirculation branch R1 to the suction port of the second circulation pump CP,

[0030] - a second branch B2 configured for the transit of from the second recirculation branch R2 to the first recirculation branch Rl, wherein a spill valve VI is arranged upstream of the second branch B2 to regulate the transit of the spill flow rate from the second recirculation branch R2 to the first recirculation branch Rl (the phrase "to regulate the transit of the spill flow rate ThSpnt" indicates that the valve VI is configured to deliver a flow rate m^p^ to the branch Rl in an amount which is variable continuously, by varying a throttling degree of the same valve, between a zero flow rate and a maximum flow rate admissible by the valve VI, which may amount up to 'rhCab). As a general prescription, each reference to a "flow rate" in the present description must be construed with reference to a mass flow rate, as attested by the choice of the notation m for all flow rates. Always referring to Figure 1, the recirculation branch R1 and the recirculation branch R2 substantially define a return path of the heat transfer liquid towards the suction ports of the pumps TP and CP, respectively. Moreover, circuit C has circuit nodes denoted with the references Nl, N2, N3. The circuit node N1 is arranged downstream of the at least one traction component TRC and upstream of the circuit node N2, the latter in turn being arranged upstream of the suction port of the pump CP. The branch Bl extends from the node Nl to the node N2. The arrangement "upstream" is defined herein with respect to the one flow direction admissible in the branch Bl, going from the node Nl towards the suction port of the pump CP, due to the presence of a non-return valve NRV along the same branch Bl between the nodes Nl and N2. The node N3 is arranged upstream of the suction port of the pump TP and downstream of the valve VI. The valve VI is preferably a three-port continuously adjustable valve, comprising a first port Vl / 1, a second port Vl / 2 and a third port Vl / 3, wherein the ports Vl / 1 and Vl / 2 are always in fluid communication with each other (except when the flow rate equals the flow rate mCab; in this case it is optionally possible to exclude the mutual fluid communication) in order to enable the recirculation of the flow rate mCabtowards the suction port of the pump CP, whereas the port Vl / 3 is in fluid communication with the ports Vl / 1 and Vl / 2 in a variable amount (including an absence of fluid communication) as a function of the amount of the spill flow rate m^p^ to be supplied to the node N3 and to the recirculation branch R1.

[0031] The second branch B2 extends from the valve VI - specifically from the port Vl / 3 - to the node N3. The locations "upstream" and "downstream" are defined by the unique function of the suction port (which admits only one flow direction) and by the need to return the spill flow rate from the branch R2 (which extends from an outlet of the heat exchange device CAB to the valve VI - specifically to the port Vl / 1) to the branch R1 and to the suction port of the same pump TP.

[0032] In the circuit C of Figure 1, corresponding to a preferred embodiment, the first heat exchange device RAD is a radiator for cooling the first recirculation flow rate coming from the at least one traction component TRC, and the second heat exchange device CAB is a cabin heater for heating a passenger compartment of the vehicle.

[0033] As can be observed in the circuit diagram of Figure 1, the flow rate m^p^ is spilled from the flow rate mTrcaccording to ways described in the following, and it is sent to the suction port of the pump CP directly through the branch Bl. Therefore, the flow rate til-cab will comprise a flow rate possibly increased by the value mspiitr if the latter is different from the null value. Since the flow rate m^p^ is required for cooling the at least one traction component, it must return to the suction port of the pump TP, and this is achieved through the branch B2 and the valve VI. The flow rate rii-Rad. recirculating to the branch R1 is therefore reduced by the flow rate riispiitr the latter flow rate being reintegrated at the node N3.

[0034] The circuit C moreover comprises a plurality of temperature sensors, including:

[0035] - a sensor TS_A configured to detect a temperature Tcint_Trc_in of the heat transfer liquid entering the at least one traction component TRC, specifically to the suction port of the pump TP,

[0036] - a sensor TS_B configured to detect a temperature TTrccintout of the heat transfer liquid exiting the at least one traction component TRC (the hottest part of the cooling circuit of the at least one traction component),

[0037] - a sensor TS_C configured to detect a temperature of the heat transfer liquid exiting the port Vl / 2 immediately upstream of the node N2, and

[0038] - a sensor TS_D configured to detect a temperature TEcH_cint_in of the heat transfer liquid entering the heater ECH.

[0039] In the light of the above, and referring to Figure 2, wherein reference 1 generally denotes an exemplary flow diagram of the method according to the invention, the method according to the invention comprises:

[0040] - determining (block 2) a limit value for said spill flow rate m^p^ as a function of a limit value of said first flow rate mTrcMax, of a target value of said first recirculation flow rate ThRadTgt, and of a target value of the second flow rate ThCabTgt,

[0041] - defining (block 4) an enablement Trc_Heat_Rej_Rec_En of the transit of the spill flow rate as a function of a difference between the temperature TTrc ctnt Outof the heat transfer liquid at the outlet of the at least one traction component and a temperature of the heat transfer liquid TCab ctnt_out at the outlet of the second heat exchange device CAB,

[0042] - determining (block 6) a target value of the spill flow rate riiSpiitTgtas a function of a target value mCabTgtof the second flow rate riiCabTgt, as a function of the difference between the temperature of the heat transfer liquid TCab ctntout at the outlet of the at least one traction component TRC and the temperature Tcab_cint_out of the heat transfer liquid at the outlet of the second heat exchange device CAB (the coldest part of the circuit), and as a function of a value of thermal power QECH_Eiect which the electric heater ECH shall output in order to satisfy a target temperature value TCab ctnt In Tgt at the inlet of the second heat exchange device CAB .

[0043] The description will be set forth with reference to a circuit C equipping a vehicle with an electric powertrain, with the first heat exchange device RAD corresponding to a radiator for cooling the first recirculation flow rate coming from the at least one traction component TRC, and the second heat exchange device CAB corresponding to a cabin heater for heating a passenger compartment of the vehicle . It is to be noted that the method is applicable to any circuit C having a similar structure and similar needs .

[0044] Reference 10 in Figure 3 generally denotes a diagram representative of the determination of the limit value of the spill flow rate ThSpiit Max. In detail , this comprises determining the limit value rii-spiit Max of the spill flow rate as the greater (block 12 , MAX ) out of a zero value (" 0" ) , block 14 ) and the lower (block 16 , MIN) of the target value ThCab Tgtof the second flow rate mCaband a di f ference (block 18 ) between the limit value mTrc Maxof the first flow rate mTrc, and the target value ThRad Tgtof the first recirculation flow rate ThRad . The value mTrcMax is approximated as a function of a maximum rotational speed of the pump TP, whereas the target value riiRaa rgt is defined as a function of the cooling needs of the one or more traction components , while taking into account a target temperature at the inlet into the one or more traction components . The spill flow rate ThSpntis limited to the value ThSpiit Max, in such a way as to avoid subtracting an excessive flow rate of heat trans fer liquid from the radiator RAD (which would lead to overheating the one or more traction components ) , and in such a way as to avoid exceeding the target value ThCab Tgtof the second flow rate . The value of ThSpntcan never be negative - and therefore the lower limit is zero - in order to avoid an undesirable reversal of the flow direction.

[0045] Reference 20 in Figure 4 generally denotes a diagram representative of the definition of the enablement Trc_Heat_Rej_Rec_En of the transit of the spill flow rate rii-spiit• The value Trc_Heat_Rej_Rec_En has a logic state equalling either "0" (enablement denied, spill flow rate disabled) or "1" (enablement allowed, spill flow rate enabled). In order to avoid so-called toggling events, i.e. a continuous switching between the logic states "0" and "1" which is not required by the circumstances, the definition of the enablement Trc_Heat_Rej_Rec_En uses a set-reset flip-flop control 22, which comprises enabling a transit of spill flow rate ThSpnt(Trc_Eleat_Rej_Rec_En = 1, SET) if the difference (block 24) between the temperature TTrc_cint_out of the heat transfer liquid at the outlet of the at least one traction component TRC (the hottest part of the circuit C) and the temperature Tcab_cint_out of the heat transfer liquid at the outlet of the second heat exchange device / cabin heater CAB (the hottest part of the circuit C) is greater than or equal to (block 26) a first threshold value Value_Hi, and disabling a transit of the spill flow rate (Trc_Eleat_Rej_Rec_En = 0, RESET) if the difference (block 24) between the temperature TTrc ctnt Outof the heat transfer liquid at the outlet of the at least one traction component TRC and the temperature TCab ctntout of the heat transfer liquid at the outlet of the second heat exchange device / cabin heater CAB is lower than or equal to (block 28) a second threshold value Value_Lo, wherein the second threshold value Value_Lo is lower than the first threshold value Value_Hi. This means that, when the temperature of the heat transfer liquid which cools the at least one traction component is higher than the temperature of the heat transfer liquid which transits in the cabin heater CAB (at least by the threshold value Value_Eli'), it is possible to transfer thermal power from the cooling circuit of the at least one traction component TRC to the cabin heater CAB by means of the flow rate rii-spiit• Beside avoiding toggling, the thresholds Value_Hi and Value_Lo enable maintaining a safety margin and avoiding the loss of thermal power.

[0046] Reference 30 in Figure 5 globally denotes a diagram representative of the determination of the target value Thsputrgt °f the spill flow rate mSpiit. It is determined as the greater (block 32, MAX) out of a null value ("0", block 34) and the lower (block 36, MIN) between the limit value ThSpiit Tgtof the spill flow rate mSpiitand a sum (block 38) of a target spill flow rate value, determined by open-loop calculation mSpiit Tgt 0Land a target spill flow rate value determined by closed-loop calculation ThSpiitTgt_CL• As described in the foregoing, the flow rate ThSpiitTgt cannot be negative, in order to avoid an undesirable reversal of the flow direction.

[0047] Reference 40 in Figure 6 generally denotes a diagram representative of the determination of the target spill flow rate value determined by open-loop calculation ThSpiitTgt_OL• It is generally determined as a function of a sum of a base value riT-spiitTgtOLRaw and of an additional value ThSpiit Tgt 0L Add. In the present instance, the phrase "as a function of" represents the fact that the calculation of the target spill flow rate value determined by open-loop calculation riT-spiitTgtOL is generally performed as the sum mSpUt Tgt 0L Raw+ 'W-spittTgtOLAdd but, in the preferred embodiment of the method as shown in the Figures, the actual correspondence of such a sum to the final value assumed by mSpiit Tgt 0Ldepends on further conditions and circumstances, e.g. an upper and a lower saturation limit, and the meeting of certain requirements.

[0048] In detail, with reference to Figure 6, the spill flow rate value determined by open-loop calculation m-spiit_Tgt_OL is determined as: i) the greater (block 40, MAX) of the zero value (block 42, "0") and the lower value (block 43, "MIN") between the limit value of the spill flow rate rii-spiitMax and the sum (block 44) of the base value riispiit_Tgt_OL_Raw and of the additional value riispittTgt 0L Addif the transit of the spill flow rate mspitt is enabled, and if there is a request for heating the vehicle cabin by means of said cabin heater (CAB), ii) the zero value, if the transit of said spill flow rate is not enabled, or if there is no request for heating the vehicle cabin by means of said cabin heater (CAB).

[0049] As regards the situation i), Figure 6 shows a switch SW40 which represents the block of the conditions which originate the decision. The switch SW40 enables feeding the sum of the base value riispiit_Tgt_OL_Raw and of the additional value riispittTgt 0L Addinto the block 43 (MIN) if both conditions (block 40G, "AND") Trc_Heat_Rej_Rec_En = 1 and Cab_Heat_Req = 1 hold true. If at least one of such conditions is not satisfied (situation ii)), the switch SW40 feeds into the block 43 the null value "0" (block 40D).

[0050] Upstream in the diagram of Figure 6, there is moreover schematically shown the determination of the base value riispittTgt_OLRaw (blocks 45-48). Specifically, it is determined according to the relationship wherein: TECH_cint_in_Tgt isatarget temperature value of the heat transfer liquid at the inlet of the electric heater ECH, Tcab_cint_out isacurrent temperature value of the heat transfer liquid at the outlet of the second heat exchange device / cabin heater CAB, TTrc_cint_out is a current temperature value of the heat transfer liquid at the outlet of the at least one traction component TRC (as detected by the sensor TS_B), and

[0051] ThCab_Tgt is the target value of the second flow rate mCab.

[0052] Indeed, one may observe that at the blocks 45 and 46 the differences (TECH Cint In Tgt-TCab Cint Out) and (TTrc_cint_out- TCab_cint_out') are respectively calculated, whereas the block 47 multiplies the difference calculated at the block 47 by the value ThCab Tgt, and the block 48 divides the result of the block 47 by the difference calculated at the block 46, thereby obtaining the base value mSpUtTgt0L Raw.

[0053] Moreover, as regards the calculation of ^spiitTgtOLRaw / with reference to the blocks 49 and 49A of Figure 6, the target temperature value TECH ctnt In Tgtof the heat transfer liquid at the inlet of the electric heater ECH is determined as the lower (block 49) out of a limit temperature value TECH ctnt In Maxat the inlet of the electric heater ECH - which is a design feature of the same heater ECH - and a sum (block 49A) of the target temperature value TCab ctnt In Tgtat the inlet of the second heat exchange device / cabin heater CAB and a reference increase ATR6Cplus of the target temperature value Tcab_cint_in_Tgt at the inlet of the second heat exchange device / cabin heater CAB. The increase of the reference temperature &TRec Piusis adjusted so as to minimize the use of electric energy by the electric heater ECH, by compensating the reduction of expense of electric energy with the thermal energy (from which &TRec Piusderives) recovered from the cooling circuit of the at least one traction component TRC.

[0054] On the other hand, the additional value mSpiit Tgt 0L Addwhich is used at the inlet to block 44 is determined according to the relationship wherein:

[0055] QscH_Eiect is the value of thermal power that the electric heater ECH shall output in order to satisfy the target temperature value TCab ctnt In Tgtat the inlet of the second heat exchange device / cabin heater CAB

[0056] Cpcint is the specific heat at constant pressure of said heat transfer liquid (the other terms with a notation equal to what has already been used herein have the same meaning).

[0057] From the definition of the terms mSpiit Tgt 0L Rawandr^lspitt_Tgt_OL_Add it is immediately clear that the former - the base value - refers to all the energy expenses of a purely thermal nature, including the recovery of thermal energy from the cooling circuit of the one or more traction components through the term &TRecPius, whereas the latter - the additional value - refers to the energy expense of a purely electrical nature, which is consumed in the heater ECH. As observed in the foregoing, the calibration of &TRecPiusin the calculation of the base value leads the additional value to be as low as possible (so that the electrical expense consumed in the heater ECH is as low as possible) while taking into account the other constraints of the system.

[0058] Finally, referring to Figure 7, number 50 globally denotes a diagram which exemplifies the computation of the spill flow rate value determined by closed-loop calculation mSpUtTgtCL. The value mSpUtTgtCLis determined by means of a proportional-integral control 51 operating on the basis of a difference (block 52) between the target temperature value TECH ctnt In Tgtof the heat transfer liquid at the inlet of said electric heater (ECH) and a current temperature value TECH ctnt In(detected by the sensor TS_D) of the heat transfer liquid at the inlet of the electric heater ECH. As regards the calculation of TECH cintinTgtt it is identical to what has been described in Figure 6 with reference to ThSpiit Tgt 0L Raw, i.e. a block 53 and a block 54 dedicated to the calculation of TECH_cint_in_Tgt have the same inputs, outputs and functions as the blocks 49 and 49A, correspondingly.

[0059] The proportional-integral control 51 moreover comprises an upper saturation limit, corresponding to a difference (block 55) between the limit value of the spill flow rate riiSpiit Maxand the target value of the spill flow rate determined by open-loop calculation mSpiit Tgt 0L(which substantially corresponds to the residual correction margin after the open-loop correction), and a lower saturation limit 56, corresponding to the opposite (—Thspitt_Tgt_OL} °f the target value of the spill flow rate determined by open-loop calculation riiSpiit Tgt 0L. The purpose of the lower saturation limit is reaching no more than a zeroing - downstream of the sum rii-spiitTgtOL + m-spiit_Tgt_CL ~ of the flow rate mSpUt Max, without ever reaching negative flow rates.

[0060] Again, similarly to what has already been described for the open-loop calculation of Thspitt_Tgt_OLr and with reference to a switch SW50 in Figure 7, the value of the spill flow rate determined by closed-loop calculation riispiitTgt_CL is determined as the output of the proportional-integral control 51 if the transit of the spill flow rate rii-spiit is enabled, and if there is a request for heating the vehicle passenger compartment by means of the cabin heater CAB, i.e. if both conditions (block 50G, "AND") Trc_Heat_Rej_Rec_En = 1 and Cab_Heat_Req = 1 hold true. If at least one of such conditions is not met, the switch SW50 determines, as output value, the null value "0" - block 50D.

[0061] Thanks to the method according to the invention, it is possible to recover the thermal energy (and the thermal power) which is dissipated while cooling the one or more traction components, thereby limiting the expense of electrical energy consumed in the heater ECH, leading therefore to a greater availability of energy in the high-voltage battery for supplying the one or more electric traction motors of the vehicle. In this way, it becomes possible to make the vehicle more efficient from the point of view of energy consumption, with a consequent benefit in terms of driving range. Moreover, thanks to the definition of the enablement of the transit of the spill flow rate according to the fashion described in the foregoing, the recovery of thermal energy is implemented in convenient conditions from the point of view both of energy and of performance, without jeopardizing the correct operation of the one or more traction components involved in the recovery of thermal energy.

[0062] Of course, the implementation details and the embodiments may amply vary with respect to what has been described and illustrated herein without departing from the extent of the present invention, as defined in the annexed claims.

Claims

CLAIMS1. A method for the operation of a thermal conditioning circuit (C) of a vehicle with an electric powertrain, the circuit comprising:- at least one traction component (TRC) of said powertrain traversed by a first flow rate of heat transfer liquid ('rhTrc') in a first flow direction (Fl), said at least one traction component (TRC) comprising an electric traction motor and / or a transmission connecting an electric traction motor to one or more corresponding drive wheels of the vehicle,- a first circulation pump (TP) having a delivery port arranged upstream of said at least one traction component (TRC) with respect to the first flow direction (Fl) of said heat transfer liquid, the first circulation pump (TP) supplying said first flow rate (mTrc) to at least one traction component (TRC),- a first recirculation branch (Rl) connecting an outlet of at least one traction component (TRC) with a suction port of the first circulation pump (TP), wherein a first heat exchange device (RAD) is arranged along the first recirculation branch (Rl), the first recirculation branch (Rl) and the first heat exchange device (RAD) being traversed by a first recirculation flow rate (mRad),- a second heat exchange device (CAB) travesed by a second flow rate ('rhcab') of heat transfer liquid in a second flow direction (F2),- an electric heater (ECH) arranged upstream of the second heat exchange device (CAB) with respect to the second flow direction (F2) of said heat transfer liquid,- a second circulation pump (CP) with a delivery port arranged upstream of the electric heater (ECH) with respect to the second flow direction (F2) of the heat transfer liquid, the second circulation pump (CP)supplying said second flow rate (riiCab} to the electric heater (ECH) and to the second heat exchange device (CAB),- a second recirculation branch (R2) connecting an outlet of the second heat exchange device (CAB) with a suction port of the second circulation pump (CPI), the second recirculation branch being traversed by a second recirculation flow rate i'^-cab') / in particular corresponding to said second flow rate (Jiicafe),- a first branch (Bl) configured for the transit of a spill flow rate ('rhspiit') from the first recirculation branch (Rl) to the suction port of the second circulation pump (CP),- a second branch (B2) configured for the transitfrom said second recirculation branch (R2) to the first recirculation branch (Rl), wherein a spill valve (VI) is arranged upstream of the second branch (B2) to regulate the transit of the spill flow rate ('rhspiit') from said second recirculation branch (R2) to the first recirculation branch (Rl), the method including:- determining (2) a limit value (mSpiitMax) for said spill flow rate as a function of a limit value of said first flow rate (mTrc Max), a target value of said first recirculation flow rate (riiRadj'gt')r and a target value of said second flow rate (riicab_Tgt')t- defining (4) an enablement (Trc_Heat_Rej_Rec_En'j of the transit of said spill flow rate ('rhspiit')as afunction of a difference between a temperature (TTrc ctnt Out) of the heat transfer liquid at the outlet of said at least one traction component (TRC) and a temperature (TCab CintOut) of the heat transfer liquid at the outlet of said second heat exchange device (CAB),- determining a target value of said spill flowrate (I'hspiitTgt'las afunction of a target value of said second flow rate (mCabTgt), of said difference between a temperature (TTrc ctnt Out) of the heat transfer liquid at the outlet of said at least one traction component (TRC) and a temperature (TCab Cint Out) of the heat transfer liquid at the outlet of said second heat exchange device (CAB), and as a function of a value of thermal power (QECH_Eiect} which said electric heater (ECH) shall output in order to satisfy a target temperature value (TCab ctnt In Tgt} at the inlet of said second heat exchange device (CAB).

2. The method of claim 1, wherein the first heat exchange device (RAD) is a radiator for cooling the first recirculation flow rate (?iiRad) from at least one traction component (TRC), and the second heat exchange device (CAB) is a cabin heater for heating a passenger compartment of the vehicle.

3. The method of claim 1 or claim 2, including determining (10) the limit value ('fftspittMax') of spill flow rate {'rnSput} as the greater (12) among a zero value (14) and the lower (16) of the target value (riiRadj'gt') of said second flow rate (riiRad') and a difference (18) between the limit value (riiTrcMax) of said first flow rate (mTrc) and the target value ^ Radj'gt') of said first recirculation flow rate (?iiRad).

4. The method of any of claims 1 to 3, wherein determining (4, 20) an enablement (Trc_Heat_Rej_Rec_En'j of the transit of said spill flow rate i'rhspiit') includes enabling (Trc_Heat_Rej_Rec_En = 1) a transit of said spill flow rate i'rhspiit') if the difference (24) between the temperature (TTrc ctnt Out) of the heat transfer liquid at the outlet of said at least one traction component (TRC) and the temperature of the heat transfer liquid (Tcabcintout) at the outlet of said second heat exchange device (CAB) is greater than a first threshold value (Value_Hi), and disabling (Trc_Eleat_Rej_Rec_En = 0) a transitof said spill flow rate (I'hspiit'l if the difference (24) between the temperature (TTrc ctnt Out) of the heat transfer liquid at the outlet of said at least one traction component (TRC) and the temperature of the heat transfer liquid (TCab ctnt Out) at the outlet of said second heat exchange device (CAB) is less than a second threshold value (Value_Lo), the second threshold value (Value_Lo) being lower than the first threshold value (Value_Hi').

5. The method of any of the preceding claims, wherein the target value of said spill flow rate (m-spittj'gt') is determined as the greater (32) among a zero value (34) and the lower (36) of the limit value (™spiit_Max') °f said spill flow ratesum (44) of a target spill flow rate value determined by openloop calculation (mSpiit Tgt 0L) and a target spill flow rate value determined by closed-loop calculation (mSpiit Tgt CL).

6. The method of Claim 5, wherein said target spill flow rate value determined by open-loop calculation ^ spitt_Tgt_OL} is determined as a function of a sum of a base value ^spiitTgtOLRaw and an additional value mSplitTgtOLAdd> where the base value Thspitt_Tgt_OL_Raw is determined according to the relationshipTECH_cintjn_Tgt is a target temperature value of the heat transfer liquid at the inlet of said electric heater (ECH),Tcab_cint_out is the current temperature value of the heat transfer liquid at the outlet of said second heat exchange device (CAB),TTrc_cint_out is the current temperature value of the heat transfer liquid at the outlet of said at least one traction component (TRC), and m-cabj'gt is the target value of said second flow rate(W ad , wherein the additional value riispittTgt 0L Addis further determined according to theQscH_Eiect is the thermal power that the electric heater (ECH) shall output in order to satisfy the target temperature value (TCab ctnt In Tgt} at the inlet of said second heat exchange device (CAB),Cpcint is the specific heat at constant pressure of said heat transfer liquid.

7. The method of claim 6, wherein the spill flow rate value determined by open-loop calculation (mspiitTgt_OL) is determined (40) as:- the greater (41) among a zero value (42) and the lower (43) of said limit value (mSpiit Max) of the spill flow rate (Wp;it) and said sum (44) of the base value mSpiitTgt_OL_Raw and the additional value mSpUtTgt0LAddif a transit of said spill flow rate i'rhspiit') is enabled (Trc_Heat_Rej_Rec_En = 1) and if there is a request for heating of the passenger compartment of the vehicle (Cab_Heat_Req = 1) by means of said cabin heater (CAB),- the null value (40D, SW40) if a transit of said spill flow rate (WPJU) is not enabled (Trc_Heat_Rej_Rec_En = 0) or if there is no request for heating of the passenger compartment of the vehicle (Cab_Heat_Req = 0) by means of said cabin heater (CAB).

8. The method under claim 6 or claim 7, in which that target temperature value (TECH ctnt In Tgt) of the heat transfer liquid at the inlet of said electric heater (ECH) is determined as the lower (49) of a limit temperature value (TECH ctnt In Max) at the inlet of said electric heater (ECH) and a sum of the target temperature value (TCab ctnt In Tgt) at the inlet of that second heatexchange device (CAB) and a reference increase (&TRec Pius) of the target temperature value at the inlet of said second heat exchange device (CAB).

9. The method of any of claims 6 to 8, wherein said spill flow rate value determined by closed-loop calculation (i'hspiit_Tgt_CL} is determined by means of a proportional-integral control operating on the basis of a difference between the target temperature value ^ECH_cint_in_Tgt) of the heat transfer liquid at the inlet of said electric heater (ECH) and a current temperature value (TECH CTNT IN) of the heat transfer liquid at the inlet of said electric heater (ECH).

10. The method of claim 9, wherein said proportional-integral control includes an upper saturation limit corresponding to a difference (55) between the limit value of the spill flow rate (mSpiit Max) and the target spill flow rate value determined by openloop calculation (^spiit_Tgt_OL^ and includes a lower saturation limit corresponding to the opposite (—mSpiit Tgt 0L) of said target spill flow rate value determined by open-loop calculation (mSpiit Tgt 0L).

Images