A method for detecting a fault in one or more shutoff valves in a refrigeration cycle of a vehicle

Abstract

According to the invention, there is described a method for the diagnostics of a fault, such a stuck condition in the open position or in the closed position, of one or more shutoff valves (SV_EVAP, SV _CHL1, SV _CHL2) upstream of corresponding one or more evaporation devices (EVAP, EV_B1, EV_B2) of a refrigeration cycle thermal conditioning circuit (CC) of a vehicle, specifically a vehicle with an electric powertrain, by using, as a diagnostic element, the same evaporation device, the flow of refrigerant fluid whereof is enabled or disabled by the same valves. This enables diagnosing a fault - generally a mechanical jamming with a consequent stuck condition in the open position or in the closed position - for the shutoff valves (SV_EVAP and / or SV_CHL1 and / or SV_CHL2) without resorting to valves provided with sensors, which are adapted to diagnose said conditions directly but which are unacceptable as regards costs and complexity.

Description

[0001] A METHOD FOR DETECTING A FAULT IN ONE OR MORE SHUTOFFVALVES IN A REFRIGERATION CYCLE OFA VEHICLE

[0002] TEXT OF THE DESCRIPTION

[0003] Field of the Invention

[0004] The present invention refers to refrigeration cycle thermal conditioning circuits for vehicles. The invention was developed with particular reference to a thermal conditioning circuit for a vehicle with an electric powertrain.

[0005] Prior Art

[0006] In the refrigeration cycle cooling circuits comprising one or mmoorree evaporation devices for the refrigerant fluid, ssuucchh aass a cabin evaporator for the conditioning of a passenger compartment of the vehicle, and, with reference to the vehicles with an electric powertrain, one or more chillers for the thermal conditioning of a high-voltage battery which supplies one or more electric traction motors of the vehicle (in addition to the cabin evaporators), there are provided both components which are fully provided with sensors and / or which are adapted to generate a diagnostic signal to indicate the presence of possible fault conditions, and components which have no diagnostic equipment at all, and therefore cannot perform fault diagnostics.

[0007] The latter group comprises the shutoff valves arranged upstream of each evaporation device: unlike the expansion / throttling valves with onboard electronics, which are equally arranged upstream of each evaporation device, and which comprise a diagnostic equipment adapted to signal the presence of a fault (typically, a stuck condition in the open or in the closed position), the shutoff valves are simple two-position (open / closed) electromechanical valves, which offer no feedback about the actuation and have no diagnostic equipment of any sort. If, on the one hand, such a choice is dictated by the simplicity and the low cost of such components, on the other hand this poses serious problems as regards the diagnostics of possible faults, with consequences which may vary as a function of the type of fault.

[0008] For example, if the shutoff valve arranged upstream of the cabin evaporator or of the chiller is stuck in the open position despite a request for switching to the closed position, and the compressor of the conditioning circuit is operating, this will cause an unrequested conditioning (of the passenger compartment of the vehicle or of the battery) in addition to a waste of electric power.

[0009] On the contrary, if the sshhuuttooffff valve arranged upstream of the cabin evaporator or of the chiller is stuck in the closed position despite a request for switching to the open position, the refrigerant fluid will not circulate in the circuit and the lubricant will not circulate in the compressor, with a consequent risk of faults of the same compressor.

[0010] Object of the Invention

[0011] The invention aims at solving the technical problems outlined in the foregoing. Specifically, the object of the invention consists in providing a method for detecting a fault in one or more shutoff valves in a refrigeration cycle thermal conditioning circuit of a vehicle, especially a vehicle with an electric powertrain, even in the absence of any diagnostic equipment on board the same shutoff valves.

[0012] Summary of the Invention

[0013] 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.

[0014] Brief Description of the Figures The invention will now be described with reference to the annexed Figures, which are provided by way of non-limiting example only and wherein:

[0015] - Figure 1 shows a general diagram of a cooling circuit on which a method according to the invention may be implemented,

[0016] - Figures 2 to 5 show aspects of the circuit in Figure 1, and

[0017] - Figures 6 to 13 show implementation aspects of the method according to the invention.

[0018] Detailed Description

[0019] Figure 1 schematically shows the general structure of a cooling circuit CC on which it is possible to implement a method for detecting a fault in one or more shutoff valves in a refrigeration cycle thermal conditioning circuit of a vehicle, especially a vehicle with an electric powertrain, according to the invention. The circuit CC comprises an electrically powered compressor EAC, the delivery port thereof is in fluid communication with the inlet of a condenser CNDS. The condenser CNDS is in heat exchange relationship with a flow rate of air ṁAIR_CNDS, which is partly supplied by a fan F arranged downstream of a set of radiating elements comprising a condenser CNDS and a radiator RAD (the latter being arranged downstream of the condenser CNDS and upstream of the fan F), and partly supplied by the movement of the vehicle. The radiator RAD is part of a cooling circuit of the traction elements of the powertrain of the vehicle, comprising one or more electric traction motors, the respective drivetrains which connect each motor to one or more corresponding wheels of the vehicle, and the gear oils. In the cooling circuit including the radiator RAD, a flow rate of coolant flows, which is provided by a circulation pump

[0020] P_RAD. Other sections of said circuit beside the pump

[0021] P_RAD, the radiator RAD and the fan F are not shown, as the circuit is known in itself.

[0022] The outlet of the condenser CNDS is in fluid communication with a first circuit node Nl, wherefrom two circuit branches depart, a first branch being directed to the inlet of a cabin evaporator EVAP, and a second branch being directed to a second circuit node N2, downstream whereof the second circuit branch forks into a third and a fourth circuit branch, which are directed to the inlets of a first refrigeration device (specifically a first chiller) CHL1 and of a second refrigeration device (specifically a second chiller) CHL2.

[0023] The cabin evaporator EVAP is in heat exchange relationship with a flow rate of cabin air ṁAIR_CAB_EVAP, which is processed and provided to the evaporator EVAP (and therefore which is supplied to the passenger compartment of the vehicle) by means of a blower BL of the passenger compartment.

[0024] Each of the chillers CHL1 and CHL2 comprises a respective battery evaporator EV_B1, EV_B2 (which receives the refrigerant fluid flowing in the circuit CC) in heat exchange relationship with a heat transfer fluid, specifically a coolant which flows in a battery cooling circuit of the one or more batteries of the electric powertrain. By way of non-limiting example only, Figure 1 shows two cooling circuits of a high- voltage battery BATT which supplies one or more electric traction motors of the vehicle, wherein a first cooling circuit CL_B1 is in heat exchange relationship with the evaporator EV_B1 of the chiller CHL1 and comprises a first circulation pump CP1 which treats a first flow rate of coolant ṁCLN_CHL1, and a second cooling circuit CL_B2 is in heat exchange relationship with the evaporator EV_B2 of the chiller CHL2 and comprises a second circulation pump CP1 which treats a second flow rate of coolant ṁCLN_CHL2. The flow rates ṁCLN_CHL1and ṁCLN_CHL2are in heat exchange relationship with the battery BATT for the thermal conditioning thereof, and may be available either individually or in combination as a function of the number of chillers which are operating simultaneously. Moreover, it is possible to envisage a single cooling circuit in common with both chillers CHL1, CHL2, therefore a single circulation pump, either keeping both chillers CHL1, CHL1 always active or disabling one of them (in this case, there will be no thermal exchange between the evaporator of the disabled chiller and the cooling circuit of the battery), as well as a single chiller with a single battery cooling circuit.

[0025] Upstream of the evaporator EVAP there is arranged an expansion / throttling valve TXV_EVAP, in the same way as upstream of the battery evaporators of the chillers CHL1 and CHL2 there are arranged respective expansion valves TXV_CHL1 and TXV_CHL2. The expansion / evaporation valves enable, by varying the respective hydraulic resistance as a function of the flow rate of the refrigerant fluid (which is in the liquid phase when it traverses them - in Figure 1 the valves are represented as variable hydraulic resistances), adjusting the pressure of the refrigerant fluid entering the evaporator EVAP and the battery evaporators EV_B1, EV_B2 of the chillers CHL1 and CHL2, so as to bring about a complete evaporation of the refrigerating fluid therein, and to avoid the inlet into the compressor EAC of a biphasic flow rate (liquid + vapour).

[0026] Upstream of each of the valves TXV_EVAP, TXV_CHL1, TXV_CHL2 - therefore upstream of the respective evaporation devices (the evaporator EVAP and the battery evaporators of the chillers CHL1, CHL2) there are arranged shutoff valves SV_EVAP, SV_CHL1, SV_CHL2, respectively. The shutoff valves SV_EVAP, SV_CHL1, SV_CHL2 may alternately be arranged between the corresponding valve TXV_EVAP, TXV_CHL1, TXV_CHL2 and respectively - the cabin evaporator EVAP, the battery evaporator of the chiller CHL1 and the battery evaporator of the chiller CHL2 (in other words, what matters is only that they be arranged respectively upstream of the evaporator EVAP and of the battery evaporators of the chillers CHL1 and CHL2). The shutoff valves SV_EVAP,

[0027] SV_CHL1, SV_CHL2 respectively comprise a first, open, operating condition and a second, closed, operating condition, and they are normally in the open operating condition. The function of each of them is to shut off, from the circuit CC, the circuit branch downstream thereof, i.e. to shut off the evaporator EVAP and one or both battery evaporators of the chillers CHL1 e CHL2 according to need (therefore disabling the respective chiller).

[0028] The outlet of the chillers CHL1 and CHL2 (therefore of the battery evaporators EV_B1, EV_B2 of the chillers CHL1, CHL2) converges into a third circuit node N3 and into a single fifth circuit branch which converges, together with the section of the first circuit branch which departs from the outlet of the cabin evaporator

[0029] EVAP, into a fourth circuit node N4, downstream whereof the cooling circuit CC is closed at the inlet port of the compressor EAC. The compressor EAC sends into the circuit CC an overall flow rate of refrigerant fluid ṁRFR_TOTin the vapour phase. The flow rate ṁRFR_TOTflows through the condenser and converts to the liquid phase, and reaches the node Nl, wherefrom it is distributed to the cabin evaporator EVAP (flow rate ṁRFR_CAB_EVAP) and to the battery evaporators EV_B1, EV_B2 of the chillers CHL1 and CHL2 (ṁRFR_CHLglobally entering the node N2, with a distribution ṁRFR_CHL1to the evaporator EV_B1 and ṁRFR_CHL2to the evaporator EV_B2). The flow rates ṁRFR_CAB_EVAPand ṁRFR_CHLundergo evaporation (at a substantially constant pressure) within the battery evaporators EV_B1, EV_B2 of the chillers CHL1 and CHL2 and within the cabin evaporator EVAP, thereby cooling the coolant of the one or more batteries and the air of the passenger compartment, respectively. The flow rates ṁRFR_CAB_EVAPe ṁRFR_CHLin the vapour phase are mixed, at the node N4, into the flow rate ṁRFR_TOT, which is drawn back by the compressor EAC to re-enter the circuit CC.

[0030] Figures 2, 3, 4, 5 show, in greater detail, some features of the chillers CHL1 and CHL2 and of the evaporator EVAP, specifically:

[0031] - each chiller CHL1 and CHL2 treats a flow rate of refrigerant fluid ṁRFR_CHL1and ṁRFR_CHL2respectively by means of the battery evaporators EV_B1 and EV_B2, with ṁRFR_CHL1+ ṁRFR_CHL2= ṁRFR_CHL, and a flow rate of coolant ṁCLN_CHL1and ṁCLN_CHL2, respectively. IInn the diagram of Figure 1, the flow rates ṁCLN_CHL1and ṁCLN_CHL2depend on the rotational speeds CP1_n and CP2_n of the pumps CP1 and CP2, respectively (Figure 3 - the flow rates depend on the rotational speed of the circulation pump also in the case of a single circuit of coolant and a single circulation pump for both chillers), and they enter the chillers CHL1, CHL2 through respective inlet ports

[0032] CHL1_IN, CHL2_IN (each being equipped with a sensor of the temperature of the coolant TS_CLN_IN), then they exit through outlet ports CHL1_OUT, CHL2_OUT (each being equipped with a respective sensor of the temperature of the coolant TS_CLN_OUT);

[0033] - the cabin evaporator EVAP (Figure 5) treats the flow rate of refrigerant fluid ṁRFR_CAB_EVAPand it is lapped by the flow rate of the passenger compartment air ṁAIR_CAB_EVAP, which impinges upon the evaporator EVAP at an inlet section EVAP_IN and leaves the evaporator at an outlet section EVAP_OUT, while being in heat exchange relationship with the flow rate ṁRFR_CAB_EVAPin the passage from EVAP_IN to EVAP_OUT. The flow rate ṁAIR_CAB_EVAPdepends on the rotational speed BL_n of the blower BL of the passenger compartment (Figure 5).

[0034] Generally speaking, beside the exemplary circuit configuration of Figure 1, the method according to the invention may be applied to any refrigeration cycle thermal conditioning circuit of a vehicle, especially a vehicle with an electric powertrain, wherein the conditioning circuit comprises:

[0035] - a compressor (EAC in the circuit CC of Figure 1), having an inlet port and a delivery port,

[0036] - a condenser (CNDS in the circuit CC of Figure 1), having an inlet in fluid communication with the delivery port of the compressor,

[0037] - at least one evaporation device (EVAP, EV_B1, EV_B2 in the circuit CC of Figure 1) having an inlet in fluid communication with an outlet of the condenser and an outlet in fluid communication with the inlet port of the compressor, wherein the at least one evaporation device is in heat exchange relationship with a respective heat transfer fluid other than the refrigerant fluid circulating in the refrigeration cycle thermal conditioning circuit (air of the passenger compartment for the evaporator EVAP, coolant for the evaporators EV_B1, EV_B2 in the circuit CC of Figure 1), a shutoff valve (TXV in the circuit CC of Figure 1) arranged upstream of the inlet of the at least one evaporation device, preferably of each evaporation device, each shutoff valve having aa first, open, operating condition and a second, closed, operating condition.

[0038] According to the invention, and with reference to the Figures 6 to 13, the method includes:

[0039] - determining, for the at least one evaporation device EVAP, EV_B1, EV_B2, a thermal power ĖCAB_CLG, ĖCHL(respectively) currently exchanged with the respective heat transfer fluid;

[0040] - determining, for the at least one evaporation device EVAP, EV_B1, EV_B2, a first threshold thermal power ĖEVAP_SV_SC, ĖCHL_SV_SC(respectively), a first diagnostic enable condition EVAP_SV_SC_EN, CHL SV SC EN (respectively), a second tthhrreesshhoolldd thermal power ĖEVAP_SV_SO,ĖCHL_SV_SO(respectively), and a second diagnostic enable condition EVAP_SV_SO_EN, CHL_SV_SO_EN (respectively), indicating a stuck condition in the closed operating condition of the shutoff valve SV_EVAP, SV_CHL1, SV_CHL2 arranged upstream of the evaporation device EVAP, EV_B1, EV_B2 (respectively) if the thermal power ĖCAB_CLG, ĖCHLcurrently exchanged with the respective heat transfer fluid is less than the first threshold thermal power ĖEVAP_SV_SC, ĖCHL_SV_SCor a first predetermined time interval ΔtEVAP_SV_SC, ΔtCHL_SV_SC, and if the first diagnostic enable condition EVAP_SV_SC_EN, CHL SV SC EN is met,

[0041] - indicating a stuck condition in the open operating condition of the shutoff valve SV_EVAP, SV_CHL1, SV_CHL2 arranged upstream of the evaporation device EVAP, EV_B1, EV_B2 (respectively) if the thermal power ĖCAB_CLG, ĖCHLcurrently exchanged with the respective heat transfer fluid is greater than the second threshold thermal power ĖEVAP_SV_SO, ĖCHL_SV_SOfor aa second predetermined time interval ΔtEVAP_SV_SO, ΔtCHL_SV_SO, and if the second diagnostic enable condition EVAP_SV_SO_EN, CHL_SV_SO_EN is met.

[0042] The thermal powers ĖCAB_CLG, ĖCHL(the latter referring to the single chiller: for convenience, in the following the notations ĖCHL1, ĖCHL2will be used for the chillers

[0043] CHL1, CHL2)) currrently exchanged by the evaporation devices; EVAP, EV_B1, EV_B2 may be expressed aass a function of the mass flow rates of the respective heat transfer fluids in heat exchange relationship therewith, and as a function of the differences in enthalpy of the same heat transfer fluids in the interaction with the evaporation device EVAP, EV_B1, EV_B2, thus wherein: ĖCAB_CLGis the thermal power exchanged by the cabin evaporator EVAP with the air supplied to the passenger compartment ĖCHLis the thermal power exchanged by the battery evaporator EV_B1, EV_B2 with the coolant flowing through the chiller CHL1, CHL2, ṁAIR_CAB_EVAPis the mass flow rate of air lapping the evaporator EVAP flowing from the inlet section EVAP_IN to the outlet section EVAP_OUT ṁCLN_CHLis the mass flow rate of coolant flowing through a chiller from the inlet to the outlet thereof

[0044] Cp_AIRis the specific heat of air at constant pressure Cp_CLNis specific heat of the coolant at constant pressure TAIR_EVAP_INis the temperature of the air at the inlet section EVAP_IN of the evaporator EVAP,

[0045] TAIR_EVAP_OUTis the temperature of the air at the outlet section EVAP_OUT of the evaporator EVAP

[0046] TCLN_CHL_INis the temperature of the coolant at the inlet of the chiller TCLN_CHL_OUTis the temperature of the coolant at the outlet of the chiller

[0047] Or else, expressed specifically for the chillers CHL1,

[0048] CHL2 ĖCHL1= ṁCLN_CHL1·Cp_CLN·(TCLN_CHL1_INTCLN_CHL1_OUT) ĖCHL2= ṁCLN_CHL2·Cp_CLN·(TCLN_CHL2_INTCLN_CHL2_OUT) wherein: ṁCLN_CHL1is the mass flow rate of the coolant flowing through the chiller CHL1 from the inlet CHL1_IN to the outlet CHL1 OUT ṁCLN_CHL2is the mass flow rate of the coolant flowing through the chiller CHL2 from the inlet CHL2_IN to the outlet CHL2 OUT

[0049] CP_AIRis the specific heat of air at constant pressure

[0050] Cp_CLNis the specific heat of the coolant at constant pressure

[0051] TCLN_CHL1_INis the temperature of the coolant at the inlet of the chiller CHL1

[0052] TCLN_CHL1_OUTis the temperature of the coolant at the outlet of the chiller CHL1

[0053] TCLN_CHL2_INis the temperature of the coolant at the inlet of the chiller CHL2

[0054] TCLN_CHL2_OUTis the temperature of the coolant at the outlet of the chiller CHL1

[0055] As regards the threshold thermal powers ĖEVAP_SV_SO, ĖCHL_SV_SCnd ĖEVAP_SV_SO. ĖCHL_SV_SOas well as the time intervals ΔtEVAP_SV_SC, ΔtCHL_SV_SCΔtEVAP_SV_SO, ΔtCHL_SV_SOthe respective values are generally predetermined and are derived from experimental tests. The threshold thermal powers ĖCHL_SV_SCĖCHL_SV_So identical for each of the chillers CHL1, CHL2, but they may differ from each other if the chillers have different sizes oorr generally different performances.

[0056] Figures 6, 7 and 8, 9 show in further detail aspects of the determination of a stuck condition in the closed condition, while Figures 10, 11 and 12, 13 - having the same meaning - show in further detail aspects of the determination of a stuck condition in the open condition.

[0057] With reference to Figure 6, reference 100 generally denotes a set of conditions which must be met simultaneously (AND condition) in the case of the evaporator EVAP, in order to meet the first diagnostic enable condition EVAP_SV_SC_EN for the evaporator EVAP.

[0058] In detail, meeting the first diagnostic enable condition EVAP_SV_SC_EN (in logic terms EVAP_SV_SC_EN = 1) for the evaporator EVAP comprises simultaneously meeting the following conditions:

[0059] - absence of faults in the refrigeration cycle thermal conditioning system, 102

[0060] - absence of faults in the system for supplying air to the passenger compartment of the vehicle, 104,

[0061] - rotational speed of said compressor above a respective threshold value, 106 rotational speed of a passenger compartment blower above a respective threshold value, 108,

[0062] - request for thermal conditioning of the air supplied to the vehicle passenger compartment by means of the cabin evaporator, 110.

[0063] As can be seen in Figure 6, the conditions 102 to 110 are input into a logic AND operator 112, the truth table whereof yields the logic state "1" (true) only if all the input data 102 to 110 have in turn the logic state "1", i.e. if all the conditions are met.

[0064] Each of the conditions 102 to 110 has a specific technical meaning in the context of the method according to the invention, specifically:

[0065] - for the conditions 102, 104, the method according to the invention executes a fundamentally indirect diagnostic activity, i.e. a diagnostic activity which is not based on data directly coming from the valve SV_EVAP, but which makes use, as a diagnostic variable, of the thermal power currently exchanged with the air transfer fluid, i.e. air, in heat exchange relationship with the evaporator EVAP. In this regard, the presence of faults in the refrigeration cycle circuit, or in the system for supplying air to the ppaasssseennggeerr compartment of the vehicle, practically mmaakkeess aannyy reliable diagnosis impossible, since the value of the currently exchanged thermal power would be influenced by the fault more than by the effects of a stuck condition in an open or in a closed position of the valve SV_EVAP;

[0066] - for the conditions 106 and 108, the rational consists in executing the diagnostics on the valve SV EVAP with flow rates of refrigerant fluid and of passenger compartment air of an appreciable entity (the entity of such flow rates depends on the rotational speeds of the compressor and of the passenger compartment blower). If this were not the case, the heat exchange dynamics in conditions of low or very low flow rates would be affected mainly by the smallness of such flow rates, thereby making it impossible to detect possible effects due to faults of one or more of the valves

[0067] SV_EVAP, SV_CHL1, SV_CHL2;

[0068] - as regards condition 110, the latter is self- evident; tthhee stuck condition in the closed operating condition is meaningful only in the presence of a request for thermal conditioning of the passenger compartment air by means of the evaporator EVAP, because otherwise the closed condition of the valve SV_EVAP would be a normal condition.

[0069] Referring to Figure 7, reference 220000 generally denotes a set of conditions which must be met simultaneously (AND condition) as regards the chillers CHL1, CHL2 (which are generally one or more chillers, and the conditions must be met for each chiller in the case of a simultaneous presence of more than one chiller) in such a way as to meet the first diagnostic enable condition CHL_SV_SC_EN for the corresponding chiller CHL1, CHL2.

[0070] In detail, meeting the first diagnostic enable condition CHL_SV_SC_EN (in logic terms CHL_SV_SC_EN = 1) for each chiller CHL1, CHL2 comprises simultaneously meeting the following conditions:

[0071] - absence of faults in the refrigeration cycle thermal conditioning circuit, 202

[0072] - absence of faults in the chiller (in each chiller) CHL1, CHL2, 204 rotational speed of the compressor above a respective threshold value, 206 (which is generally identical with the threshold value envisaged for condition 106; however, it is possible to set different thresholds for the evaporator EVAP and the chillers CHL1, CHL2),

[0073] - rotational speed of one or more circulation pumps associated with the chiller (with each chiller) CHL1, CHL2 above a respective threshold value, 208; in the case of the circuit CC the condition is applied to each pair CP1-CHL1 and CP2-CHL2, due to the association thereof. However, other options may be envisaged in the case of different configurations of the chillers and of the cooling circuits;

[0074] - request for thermal conditioning of the battery BATT by means of one or more chillers CHL1, CHL2, 210.

[0075] As can be seen in Figure 7, the conditions 202 to 210 are input into a logical AND operator 212, the truth table whereof yields the logic state "1" (true) only if all the input data 202 to 210 have in turn the logic state "1", i.e. if all the conditions are met.

[0076] Each of the conditions 202 to 210 has, in the same way as the conditions 102 to 110, a specific technical meaning in the context of the method according to the invention, in detail:

[0077] - for the conditions 202, 204, the method according to the invention performs a diagnostic activity in a fundamentally indirect fashion, and therefore not on the basis of data directly derived from the valves SV_CHL1 and / or SV_CHL2, but by using, as a diagnostic variable, the thermal power currently exchanged with the heat transfer fluid - the coolant - in heat exchange relationship with each chiller CHL1, CHL2. In this regard, the presence of faults in the refrigeration cycle circuit or in the chiller associated with the shutoff valve whereof a possible actual fault must be detected, makes any reliable diagnosis impossible, since the value of the thermal power currently exchanged would be affected more by the effects of the same fault than it would be affected by the effects of a stuck condition in the open or in the closed position of the valve SV_CHL1, SV_CHL2;

[0078] - for the conditions 206 and 208 the rational is to perform the diagnostics on the valve SV_CHL1 and SV_CHL2 with flow rates of refrigerant fluid and of coolant of appreciable entity (the entity of such flow rates depends on the rotational speeds of the compressor and of the pumps CP1, CP2). If this were not true, the heat exchange dynamics in conditions of low or very low flow rate would mainly be affected by the smallness of such flow rates, thereby making it impossible to distinguish possible effects due to faults in one or both valves SV_CHL1, SV_CHL2;

[0079] - as regards the condition 210, the latter is self- evident; the diagnosis of a stuck condition in the closed operating condition is meaningful only if a thermal conditioning of the battery BATT is requested by means of one of the chillers CHL1, CHL2, since otherwise the closed condition of the valves SV_CHL1, SV_CHL2 would be a normal condition.

[0080] Referring to Figures 8 and 9, the references 1000 and 2000 ddeennoottee state diagrams which represent the evolution of the diagnostic process in the method according to the invention, in the case of a diagnosis of a stuck condition in the open operating condition. Each of the diagrams 1000 and 2000 comprises a state

[0081] 1002, 2002 of checking if the first diagnostic enable condition EVAP_SV_SC_EN, CHL_SV_SC_EN is met, a state 1004, 2004 of starting the diagnostics, and a state 1006, 2006 of diagnostics completion, with the detection of a stuck condition in the closed position. With the exception of the transition from the state 1002, 2002 to the state 1004, 2004 following meeting the first diagnostic enable condition (EVAP_SV_SC_EN = 1,

[0082] CHL_SV_SC_EN 1 respectively) , the remaining transitions are controlled via intermediate nodes, which are identified by the following references (this also applies to the following Figures 12, 13):

[0083] - nodes J1, J2, which define a direct route from the state 1004, 2004 to the state 1006, 2006, and which correspond to a state transition without variation of boundary (operating and enable) conditions;

[0084] - nodes L1, L2, which define a return route to the state 1002, 2002, and which correspond to a variation of any one of the conditions 102 to 110 and 202 to 210 after the start of the diagnostics, i.e. to a oss of the diagnostic enable condition ((EVAP_SV_SC_EN and / or CHL_SV_SC_EN go back to the logic state "0");

[0085] - nodes R1, R2, R1A, which define a return route to the state 1004, 2004, and which correspond to a failure to meet the diagnostic enable condition based on the thermal power currently exchanged (and which therefore correspond to aa situation wherein the relationships ĖCAB_CLG< ĖEVAP_SV_SCand / or ĖCHL< ĖCHL_SV_SCare no longer met, whereas the diagnostic enable condition (EVAP_SV_SC_EN = 1 and CHL_SV_SC_EN = 1) is still met in both cases.

[0086] The layering of the nodes is due to the difference of the instant of time when the event occurs which leads to the deviation from the rroouuttee defined by the intermediate nodes J1, J2.

[0087] In more detail, after having ascertained that the first diagnostic enable condition is met, the diagnostic process switches from the state 1002, 2002 to the state 1004, 2004, setting a time counter to zero (t = 0). In the transition from the state 1004, 2004 to the state 1006, 2006, substantially simultaneously (t = 0) with ascertaining meeting the first diagnostic enable condition, a first checking is moreover performed - node J1 - on the operating condition based on the thermal power currently exchanged with the heat transfer fluid and on the diagnostic enable condition. If the operating condition is met, i.e. if ĖCAB_CLG< ĖEVAP_SV_SCand ĖCHL< ĖCHL_SV_SChold true (generally speaking, whereas specifically referring to the chillers CHL1 and CHL2, the condition is written as ĖCHL1< ĖCHL_SV_SCand ĖCHL2< ĖCHL_SV_SC), and if the diagnostic enable condition is still met, then the process switches from node J1 to node J2, incrementing the time counter by an interval Δt. If the operating condition is not met, i.e. if ĖCAB_CLG> ĖEVAP_SV_SCand ĖCHL> ĖCHL_SV_SChold true (generally speaking, whereas specifically referring to the chillers CHL1 and CHL2, the condition is written as ĖCHL1> ĖCHL_SV_SCand ĖCHL2> ĖCHL_SV_SC), a return to the state 1004, 2004 takes place, through the nodes R1 and R1A. If, on the contrary, the diagnostic enable condition is not met, therefore if EVAP_SV_SC = 0, CHL_SV_SC = 0 holds true, a return to the state 1002, 2002 takes place, through the node L1, irrespective of whether the operating condition based on the exchanged thermal power is met.

[0088] At node J2, a second check is performed which is totally identical with the first check, and which yields a similar result: if the operating condition about the thermal power currently exchanged is not met, a return takes place to the state 1004, 2004, through the nodes R2, R2, R1A, whereas, if the diagnostic enable condition is not met, a return takes place to the state 1002, 2002, through the nodes L1, L2, irrespective of whether the operating condition based on the exchanged thermal power is met.

[0089] If, however, both the operating and the diagnostic enable conditions are met throughout the transition from the state 1004, 2004 to the state 1006, 2006 ((i.e. at each check at the nodes J1, J2), the time counter is further incremented, thereby reaching the duration of the predetermined time intervals ΔtEVAP_SV_SC, ΔtCHL_SV_SC. In such circumstances, as stated in the foregoing, at the state 1006, 2006 a stuck condition of the valves SV_EVAP,

[0090] SV_CHL1 and / or SV_CHL2 in the cclloosseedd position is reported, since the condition ĖCAB_CLG< ĖEVAP_SV_SCand ĖCHL< ĖCHL_SV_SCĖCHL1< ĖCHL_SV_SCand ĖCHL2< ĖCHL_SV_SChas been ascertained throughout the time interval ΔtEVAP_SV_SC, ΔtCHL_SV_SCregards the operating condition based on the thermal power currently exchanged, the physical meaning is immediately clear: if a shutoff valve upstream of an evaporation device is stuck in a closed condition, the thermal power exchanged with the heat transfer fluid other than the refrigerating fluid is lower than expected: by calibrating the threshold thermal powers ĖEVAP_SV_SCand ĖCHL_SV_SCn such a way as to represent the expected value which has not been reached, it is possible to perform the diagnostics without placing sensors on the shutoff valves. The choice of checking the operating condition for a long time, throughout the time interval ΔtEVAP_SV_SC, ΔtCHL_SV_SC, has the purpose of excluding positive diagnostic events (thus a diagnosis of a stuck condition in the closed position) due to transient conditions. In other words, each time interval ΔtEVAP_SV_SC, ΔtCHL_SV_SCis calibrated in such a way that it has a longer duration than a typical transient (e.g., a transient following the activation of the cooling of the passenger compartment and / or of the cooling of the battery BATT). The time intervals ΔtEVAP_SV_SC, ΔtCHL_SV_SCmay have the same duration or different durations, as a function of the characteristics of the components of the circuit CC (the evaporator EVAP and the one or more chillers CHL1, CHL2).

[0091] As regards the diagnosis of a stuck condition of the valves SV_EVAP and / or SV_CHL1 and / or SV_CHL2 in the open position, reference will be made to the Figures 10 to 13.

[0092] In Figure 10, reference 300 generally denotes a set of conditions which must be met simultaneously (AND condition) in the case of the evaporator EVAP, in such a way that the second diagnostic enable condition EVAP_SV_SO_EN is met for the evaporator EVAP.

[0093] In detail, meeting the second diagnostic enable condition EVAP_SV_SO_EN (in logic terms EVAP_SV_SO_EN = 1) for tthhee evaporator EVAP comprises simultaneously meeting the following conditions:

[0094] - absence of faults in the refrigeration cycle thermal conditioning circuit, 302

[0095] - absence of faults in the system for supplying air to the passenger compartment of the vehicle, 304

[0096] - rotational speed of said compressor above a respective threshold value, 306 rotational speed of a passenger compartment blower above a respective threshold value, 308

[0097] - no request for thermal conditioning of the air supplied to the vehicle passenger compartment by means of the cabin evaporator, 310.

[0098] As may be seen in Figure 10, the conditions 302 to 310 are input into a logical AND operator 312, the truth table whereof yields the logic state "1" (true) only if all input data 302 to 310 have in turn the logic state "1", and therefore if all the conditions are met.

[0099] Each of the conditions 302 to 310 has a specific technical meaning in the context of the method according to the invention, in detail:

[0100] - for the conditions 302, 304, the meaning is the same as for the conditions 102, 104,

[0101] - for the conditions 306 and 308, the rational is the same as for the conditions 106 and 108;

[0102] - as regards the condition 310, it is self-evident; the diagnosis of a stuck condition in the closed operating condition is meaningful only if aa thermal conditioning of the passenger compartment air by means of the evaporator EVAP is not requested, since otherwise the open condition of the valve SV_EVAP would be a normal condition.

[0103] Referring to Figure 11, reference 400 generally denotes a set of conditions which must be met simultaneously (AND condition) in the case of the chillers CHL1, CHL2 (which are generally one or more, and the conditions must be met for each chiller in the case of a contemporary presence of more than one chiller), in such a way that the second diagnostic enable condition CHL_SV_SO_EN is met for the corresponding chiller CHL1, CHL2. In more detail, meeting the second diagnostic enable condition CHL_SV_SO_EN (in logic terms, CHL_SV_SO_EN = 1) for each chiller CHL1, CHL2 comprises simultaneously meeting the following conditions: - absence of faults in the refrigeration cycle thermal conditioning circuit, 402 - absence of faults in the chiller (in each chiller) CHL1, CHL2, 404 rotational speed of tthhee compressor above a respective threshold value, 440066 (generally speaking, this value is identical to the threshold value envisaged for condition 306, but it is possible to set different thresholds for the evaporator EVAP and for the chillers CHL1, CHL2)

[0104] - rotational speed of one or more circulation pumps associated with the chiller (with each chiller) CHL1,

[0105] CHL2 above a respective threshold value, 440088;; in the case of circuit CC, the condition is applied to each pair CP1-CHL1 and CP2-CHL2 due ttoo the association thereof. However, it is possible to envisage other options in the case of different configurations of the chillers and of the cooling circuits;

[0106] - request for thermal conditioning of the battery

[0107] BATT by means of one or more chillers CHL1, CHL2, 410. As can be seen in Figure 11, the conditions 402 to

[0108] 410 are input into a logical AND operator 412, the truth table whereof yield the logic state "1" (true) only if all the input data 402 to 410 have in turn the logic state "1", i.e. if all the conditions are met.

[0109] Each of the conditions 402 to 410 has, in the same way as the conditions 302 to 310, a specific technical meaning in the context of the method according to the invention, in detail:

[0110] - for the conditions 402, the meaning is the same as for the conditions 202, 204

[0111] - for the conditions 406 and 408 the rational is the same as for the conditions 206 and 208:

[0112] - as regards the condition 410, it is self-evident: the ddiiaaggnnoossiiss of a stuck condition in the closed operating position has aa meaning oonnllyy iiff a thermal conditioning of the battery BATT by means of one or more of the chillers CHL1, CHL2 is not requested, since otherwise the open condition of the valves SV_CHL1,

[0113] SV CHL2 would be a normal condition.

[0114] Referring to the Figures 12 and 13, the references 3000 and 4000 denote state diagrams which represent the evolution of the diagnostic process in the method according to the invention, in the case of the diagnosis of aa stuck condition in the open operating position. Each of the diagrams 3000 and 4000 comprises a state 3002, 4002 of checking whether the second diagnostic enable condition EVAP_SV_SO_EN, CHL_SV_SO_EN is met, a state 3004, 4004 of starting the diagnostics, and a state 3006, 4006 of diagnostics completion, with the detection of a stuck condition in the closed position. With the exception of the transition from the state 3002, 4002 to the state 3004, 4004 following meeting the second diagnostic enable condition (EVAP_SV_SO_EN = 1,

[0115] CHL SV SO EN 1 respectively) , the remaining transitions are controlled, in the same way as in the diagrams 1000, 2000, through intermediate nodes identified by the following references (this also applies to the following Figures 12, 13):

[0116] - nodes J1, J2, which define a direct route from the state 3004, 4004 to the state 3006, 4006, and which correspond to a state transition without variation of the boundary (operating and enable) conditions,

[0117] - nodes L1, L2, which define a return route to the state 3002, 4002 and which correspond to a variation of any one of the conditions 302 to 310 and 402 to 410 after the start of the diagnostics, and therefore to a loss of the diagnostic enable condition (EVAP_SV_SO_EN and / or CHL_SV_SO_EN go back to the logic value "0");

[0118] - nodes R1, R2, R1A, which define a return route to the state 3004, 4004, and which correspond to a failure to meet the diagnostic condition based on the thermal power currently exchanged (and which therefore correspond to a situation wwhheerreeiinn the relationships ĖCAB_CLG>EVAP_SV_SOand / or ĖCHL> > ĖCHL_SV_SOare no longer met, while the diagnostic enable condition (EVAP_SV_SO_EN = 1 and CHL_SV_SO_EN = 1) is still met in both cases.

[0119] The layering of the nodes is due, as stated in the foregoing, to the difference of the instant of time when the event occurs which leads to the deviation from the route defined by the intermediate nodes J1, J2.

[0120] In detail, after having ascertained that the second diagnostic enable condition is met, the diagnostic process switches from the state 3002, 4002 to the state 3004, 4004, with a time counter being set to zero (t = 0). In the transition from the state 3004, 4004 to the state 3006, 4006, substantially simultaneously (t = 0) with ascertaining that the second diagnostic enable condition is met, a first check is moreover carried out - node J1 - about the operating condition based on the thermal power currently exchanged with the heat transfer fluid and about the diagnostic enable condition. If the operating condition is met, i.e. if ĖCAB_CLG> ĖEVAP_SV_SOand ĖCHL> ĖCHL_SV_SOhold true (generally speaking, whereas, in a form specific for the chillers CHL1 and CHL2, the condition is written as ĖCHL1> ĖCHL_SV_SOand ĖCHL2> ĖCHL_SV_SO), and if the diagnostic enable condition is still met, then a passage occurs from node J1 to node J2, incrementing the time counter by an interval Δt. If the operating condition is not met, and therefore if ĖCAB_CLG< ĖEVAPsv so and ĖCHLĖCHL_SV_SOhold true (generally speaking, whereas, in a form specific for the chillers CHL1 and CHL2, the condition is written as ĖCHL1< ĖCHL_SV_SOand ĖCHL2< ĖCHL_SV_SO), a return is made to the state 3004, 4004, through the nodes R1 and R1A. If, on the contrary, the diagnostic enable condition is not met, and therefore EVAP_SV_SO_EN = 0, CHL_SV_SO_EN = 0 holds through, a return is made to the state 3002, 44000022,, through node L1, irrespective of whether the operating condition based on the exchanged thermal power is met.

[0121] At node J2, a second check is carried out which is identical to the first check and yields a similar result: if the operating condition about the thermal power currently exchanged is not met, a return is made to the state 3004, 4004, through the nodes R2, R1, R1A, whereas if the diagnostic enable condition is not met a return is made to the state 3002, 4002 through the nodes L1, L2, irrespective of whether the operating condition based on the exchanged thermal power is met.

[0122] If, however, both (operating and diagnostic enable) conditions are met throughout the transition from the state 3004, 4004 to the state 3006, 4006 (therefore at each check at the nodes J1, J2), then the time counter is further incremented,, reaching the duration of the predetermined time intervals ΔtEVAP_SV_SO, ΔtCHL_SV_SO. In such circumstances, as stated in the foregoing, at the state 3006, 4006 a stuck condition of the valves SV_EVAP, SV_CHL1 and / or SV_CHL2 in the open position is reported, since the condition ĖCAB_CLG> ĖEVAP_SV_SOand ĖCHL> ĖCHL_SV_SO(ĖCHL1> ĖCHL_SV_SOand ĖCHL2> ĖCHL_SV_SO) has been ascertained throughout the time interval ΔtEVAP_SV_SO, ΔtCHL_SV_SC.As for the operating condition based oonn tthhee thermal power currently exchanged, the physical meaning is clearly understandable: if a shutoff valve upstream of an evaporation device is stuck in the open condition, the thermal power exchanged with the heat transfer fluid other than the refrigerant fluid is greater than expected: by calibrating the threshold thermal powers ĖEVAP_SV_SOand ĖCHL_SV_SOis such a way as to represent the exceeded expected value, it is possible to execute the diagnostics without providing sensors oonn the shutoff valves. The choice of checking the operating condition for a long time, throughout the time interval ΔtEVAP_SV_SO, ΔtCHL_SV_SO, enables excluding positive diagnostic events (i.e., a diagnosis of a stuck condition in the open position) due to transient conditions. In other words, each time interval ΔtEVAP_SV_SO, ΔtCHL_SV_SOis calibrated in such a way as to have a duration longer than a typical transient (e.g. a transient following disabling the cooling in the passenger compartment and / or the cooling of the battery BATT). The time intervals ΔtEVAP_SV_SO, ΔtCHL_SV_SOmay be equal or different in duration, as a function of the characteristics of the components of the circuit CC (the evaporator EVAP and the one or more chillers CHL1, CHL2).

[0123] Thanks to the method according to the invention, it is therefore possible to diagnose a fault such as a stuck condition in the open position or in the closed position of the shutoff valves SV_EVAP and / or SV_CHL1 and / or SV_CHL2 by using, as a diagnostic element, the evaporation device itself, the flow of refrigerant fluid whereof is enabled or disabled by the same valves. This enables diagnosing faults - generally a mechanical jamming with a consequent stuck condition in the open position or in the closed position - for the valves SV_EVAP and / or SV_CHL1 and / or SV_CHL2 without resorting to valves provided with sensors, which are certainly adapted to directly diagnose said conditions, but which are unacceptable as regards costs and complexity.

[0124] 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 in the annexed claims.

Claims

CLAIMS1. A method for detecting a fault in one or more shutoff valves (SV_EVAP, SV_CHL1, SV_CHL2) in a refrigeration cycle thermal conditioning (CC) circuit of a vehicle, especially a vehicle with an electric powertrain, the thermal conditioning (CC) circuit comprising:- a compressor (EAC) having an inlet port and a delivery port,- a condenser (CNDS) having an inlet in fluid communication with said delivery port of the compressor (EAC),- at least one evaporation device (EVAP, EV_B1, EV_B2) having an inlet in fluid communication with an outlet of said condenser (CNDS) and an outlet in fluid communication with the inlet port of the compressor (EAC), said at least one evaporation device (EVAP, EV_B1, EV_B2) being in heat exchange relationship with a respective heat transfer fluid other than a refrigerant fluid circulating in said refrigerant cycle thermal conditioning circuit (CC), a shutoff valve (SV_EVAP, SV_CHL1, SV_CHL2) arranged upstream of the inlet of said at least one evaporation device (EVAP, EV_B1, EV_B2), preferably of each evaporation device (EVAP, EV_B1, EV_B2), each shutoff valve having a first, open, operating condition and a second, closed, operating condition, the method including:- determining, for said at least one evaporation device (EVAP, EV_B1, EV_B2), a thermal power (ĖCAB_CLG, ĖCHL) currently eexxcchhaannggeedd wwiitthh the respective heat transfer fluid;- determining, for said at least one evaporation device (EVAP, EV_B1, EV_B2), a first threshold thermal power (ĖEVAP_SV_SC, ĖCHL_SV_SC) a first diagnostic enablecondition (EVAP_SV_SC_EN, CHL_SV_SC_EN) , a second threshold thermal power (ĖEVAP_SV_SO, ĖCHL_SV_SO) / and a second diagnostic enable condition (EVAP_SV_SO_EN, CHL_SV_SO_EN),- indicating a stuck condition in the closed operating condition of the sshhuuttooffff valve (SV_EVAP, SV_CHL1, SV_CHL2) arranged upstream of the evaporation device (EVAP, EV_B1, EV_B2) if the thermal power (ĖCAB_CLG, ĖCHL) currently exchanged with the respective heat transfer fluid is less than said first threshold thermal power (ĖEVAP_SV_SC, ĖCHL_SV_SC) for a first predetermined time interval (ΔtCHL_SV_SC, ΔtCHL_SV_SC), and if said first diagnostic enable condition (EVAP_SV_SC_EN, CHL_SV_SC_EN) is met,- indicating a stuck condition in the open operating condition of the shutoff valve (SV_EVAP, SV_CHL1, SV_CHL2) arranged upstream of the evaporation device (EVAP, EV_B1, EV_B2) if the thermal power (ĖCAB_CLG, ĖCHL) currently exchanged with the respective heat transfer fluid is greater than said second threshold heat output (ĖEVAP_SV_SO, ĖCHL_SV_SO) for a second predetermined time interval (ΔtEVAP_SV_SO, ΔtCHL_SV_SO), and if said second diagnostic enable condition (EVAP_SV_SO_EN, CHL_SV_SO_EN) is met.

2. The method according to claim 1, wherein said at least one evaporator device (EVAP, EV_B1, EV_B2) comprises a cabin evaporator (EVAP) for thermal conditioning of a passenger compartment of the vehicle, and wherein said heat transfer fluid comprises air supplied to the passenger compartment of the vehicle.

3. The method according to claim 1, or claim 2, wherein said at least one evaporation device comprises one or more battery evaporators (EV_B1, EV_B2) of corresponding one or more chillers (CHL1, CHL2) for thermal conditioning of a battery (BATT) of the electricpowertrain of the vehicle, and wherein said heat transfer fluid comprises a coolant of said battery (BATT) flowing in a circuit in heat exchange relationship with a corresponding battery evaporator (EV_B1).

4. The method according to claim 2, wherein said first diagnostic enable condition (EVAP_SV_SC_EN) comprises the following conditions:- absence of faults (102) in the refrigeration cycle thermal conditioning (CC) circuit, absence of faults (104) in the system for supplying air to the passenger compartment of the vehicle,- rotational speed of said compressor (EAC) above a respective threshold value (106), rotational speed of a passenger compartment blower above a respective threshold value (108),- request for thermal conditioning of the air supplied to the vehicle passenger compartment by means of the cabin evaporator (EVAP).

5. The method according to claim 2 or claim 4, wherein said second diagnostic enable condition (EVAP_SV_SO_EN) comprises the following conditions:- absence of faults (302) in the refrigeration cycle thermal conditioning (CC) circuit, absence of faults (304) in the system for supplying air to the passenger compartment of the vehicle,- rotational speed of said compressor (EAC) above a respective threshold value (306), rotational speed of a passenger compartment blower above a respective threshold value (308),- no request (310) for thermal conditioning of the air supplied to the vehicle passenger compartment by means of the cabin evaporator (EVAP).

6. The method according to claim 3, wherein saidfirst diagnostic enable condition (CHL SV SC EN) comprises the following conditions:- no faults (202) in the refrigeration cycle thermal conditioning (CC) circuit,- absence of faults (204) in the one or more chillers (CHL1, CHL2),- rotational speed of said compressor (EAC) above a respective threshold value (206),- rotational speed of one or more circulation pumps (CPI, CP2) of the coolant associated with corresponding one or more chillers (CHL1, CHL2) higher than a respective threshold value (208),- request for thermal conditioning (210) of the battery (BATT) by the one or more chillers (CHL1, CHL2).

7. The method according to claim 3 or claim 6, wherein said second diagnostic enable condition (CHL_SV_SO_EN) comprises the following conditions:- absence of faults (402) in the refrigeration cycle (CC) thermal conditioning circuit,- absence of faults (404) in the one or more chillers (CHL1, CHL2),- rotational speed of said compressor (EAC) above a respective threshold value (406),- rotational speed of one or more circulation pumps (CP1, CP2) of the coolant associated with corresponding one or more chillers (CHL1, CHL2) above a respective threshold value (408),- no request for thermal conditioning (410) of the battery (BATT) by means of the one or more chillers (CHL1, CHL2).

8. The method according to any of the preceding claims, comprising a shutoff valve (SV_EVAP, SV_CHL1, SV_CHL2) upstream of each evaporator device (EVAP, EV_B1, EV_B2), the method comprising: determining, for each evaporation device (EVAP,EV_B1, EV_B2), a thermal power (ĖCAB_CLG, ĖCHL) currently exchanged with the respective heat transfer fluid;- determining, for each evaporation device (EVAP, EV_B1, EV_B2), a first threshold thermal power (ĖEVAP_SV_SC, ĖCHL_SV_SC) a first diagnostic enable condition (EVAP_SV_SC_EN, CHL_SV_SC_EN), a threshold thermal power (ĖEVAP_SV_SO, ĖCHL_SV_SO) and a second diagnostic enable condition (EVAP_SV_SO_EN, CHL_SV_SO_EN),- indicating a stuck condition in the closed operating condition for each shutoff valve (SV_EVAP, SV_CHL1, SV_CHL2) arranged upstream of the corresponding evaporation device (EVAP, EV_B1, EV_B2) if the thermal power (ĖCAB_CLG, ĖCHL) currently exchanged with the respective heat transfer fluid is lower than said first threshold thermal power (ĖEVAP_SV_SC, ĖCHL_SV_SC) for said first predetermined time interval (ΔtEVAP_SV_SC, ΔtCHL_SV_SC), and if said first diagnostic enable condition is met (EVAP_SV_SC_EN, CHL_SV_SC_EN),- indicating a stuck condition in the open operating condition for each shutoff valve (SV_EVAP, SV_CHL1, SV_CHL2) arranged upstream of the corresponding evaporation device if the thermal power (ĖCAB_CLG, ĖCHL) currently exchanged with the respective heat transfer fluid is greater than said second threshold thermal power (ĖEVAP_SV_SO, ĖCHL_SV_SO) for said second predetermined time interval (ΔtEVAP_SV_SO, ΔtCHL_SV_SO), and if said second diagnostic enabling condition is met (EVAP_SV_SO_EN, CHL_SV_SO_EN) .

9. The method according to any one of claims 2, 4, 5, wherein said currently exchanged thermal power can be expressed aswherein: ĖCAB_CLGis the thermal power currently exchanged by the cabin evaporator (EVAP) with the air supplied to the passenger compartment, ṁAIR_CAB_EVAPis the mass flow rate of air lapping the cabin evaporator (EVAP) flowing from an inlet section (EVAP_IN) of the cabin evaporator (EVAP) to an outlet section (EVAP_OUT) of the cabin evaporator (EVAP), Cp_AIRis air specific heat at constant pressure, TAIR_EVAP_INis the air temperature at the inlet section of the cabin evaporator (EVAP), TAIR_EVAP_OUTis the air temperature at the outlet section of the cabin evaporator (EVAP).

10. The method according to any one of claims 3, 6,7, wherein said currently exchanged thermal power can be expressed aswherein: ĖCHLis the thermal power exchanged by the battery (EV_B1, EV_B2) with the coolant flowing through the chiller, ṁCLN_CHLis the mass flow rate of coolant flowing through a chiller from an inlet to an outlet thereof,Cp_CLNis the specific heat at constant pressure of the coolant,TCLN_CHL_INis the temperature of the coolant at the inlet of the chiller, TCLN_CHL_OUTis the temperature of the coolant at the outlet of the chiller.

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